@node Sockets, Low-Level Terminal Interface, Pipes and FIFOs, Top
+@c %MENU% A more complicated IPC mechanism, with networking support
@chapter Sockets
This chapter describes the GNU facilities for interprocess
@cindex socket
@cindex interprocess communication, with sockets
A @dfn{socket} is a generalized interprocess communication channel.
-Like a pipe, a socket is represented as a file descriptor. But,
-unlike pipes, sockets support communication between unrelated
-processes, and even between processes running on different machines
-that communicate over a network. Sockets are the primary means of
-communicating with other machines; @code{telnet}, @code{rlogin},
-@code{ftp}, @code{talk}, and the other familiar network programs use
-sockets.
-
-Not all operating systems support sockets. In the GNU library, the
+Like a pipe, a socket is represented as a file descriptor. Unlike pipes
+sockets support communication between unrelated processes, and even
+between processes running on different machines that communicate over a
+network. Sockets are the primary means of communicating with other
+machines; @code{telnet}, @code{rlogin}, @code{ftp}, @code{talk} and the
+other familiar network programs use sockets.
+
+Not all operating systems support sockets. In @theglibc{}, the
header file @file{sys/socket.h} exists regardless of the operating
system, and the socket functions always exist, but if the system does
-not really support sockets, these functions always fail.
+not really support sockets these functions always fail.
@strong{Incomplete:} We do not currently document the facilities for
-broadcast messages or for configuring Internet interfaces.
+broadcast messages or for configuring Internet interfaces. The
+reentrant functions and some newer functions that are related to IPv6
+aren't documented either so far.
@menu
* Socket Concepts:: Basic concepts you need to know about.
-* Communication Styles::Stream communication, datagrams, and other styles.
+* Communication Styles::Stream communication, datagrams and other styles.
* Socket Addresses:: How socket names (``addresses'') work.
-* File Namespace:: Details about the file namespace.
+* Interface Naming:: Identifying specific network interfaces.
+* Local Namespace:: Details about the local namespace.
* Internet Namespace:: Details about the Internet namespace.
* Misc Namespaces:: Other namespaces not documented fully here.
* Open/Close Sockets:: Creating sockets and destroying them.
@cindex byte stream
@cindex stream (sockets)
@strong{What are the units of data transmission?} Some communication
-styles regard the data as a sequence of bytes, with no larger
+styles regard the data as a sequence of bytes with no larger
structure; others group the bytes into records (which are known in
this context as @dfn{packets}).
@item
@strong{Is communication entirely with one partner?} Some
communication styles are like a telephone call---you make a
-@dfn{connection} with one remote socket, and then exchange data
+@dfn{connection} with one remote socket and then exchange data
freely. Other styles are like mailing letters---you specify a
destination address for each message you send.
@end itemize
The rules of a protocol apply to the data passing between two programs,
perhaps on different computers; most of these rules are handled by the
-operating system, and you need not know about them. What you do need to
+operating system and you need not know about them. What you do need to
know about protocols is this:
@itemize @bullet
communication and the Internet namespace.
@item
-For each combination of style and namespace, there is a @dfn{default
-protocol} which you can request by specifying 0 as the protocol
+For each combination of style and namespace there is a @dfn{default
+protocol}, which you can request by specifying 0 as the protocol
number. And that's what you should normally do---use the default.
@end itemize
Throughout the following description at various places
variables/parameters to denote sizes are required. And here the trouble
starts. In the first implementations the type of these variables was
-simply @code{int}. This type was on almost all machines of this time 32
-bits wide and so a de-factor standard required 32 bit variables. This
-is important since references to variables of this type are passed to
-the kernel.
-
-But now the POSIX people came and unified the interface with their words
-"all size values are of type @code{size_t}". But on 64 bit machines
-@code{size_t} is 64 bits wide and so variable references are not anymore
+simply @code{int}. On most machines at that time an @code{int} was 32
+bits wide, which created a @emph{de facto} standard requiring 32-bit
+variables. This is important since references to variables of this type
+are passed to the kernel.
+
+Then the POSIX people came and unified the interface with the words "all
+size values are of type @code{size_t}". On 64-bit machines
+@code{size_t} is 64 bits wide, so pointers to variables were no longer
possible.
-A solution provides the Unix98 specification which finally introduces a
-type @code{socklen_t}. This type is used in all of the cases that were
-previously changed to use @code{size_t}. The only requirement of this
-type is that it is an unsigned type of at least 32 bits. Therefore,
-implementations which require references to 32 bit variables be passed
-can be as happy as implementations which use right from the start 64 bit
-values.
+The Unix98 specification provides a solution by introducing a type
+@code{socklen_t}. This type is used in all of the cases that POSIX
+changed to use @code{size_t}. The only requirement of this type is that
+it be an unsigned type of at least 32 bits. Therefore, implementations
+which require that references to 32-bit variables be passed can be as
+happy as implementations which use 64-bit values.
@node Communication Styles
@section Communication Styles
-The GNU library includes support for several different kinds of sockets,
+@Theglibc{} includes support for several different kinds of sockets,
each with different characteristics. This section describes the
supported socket types. The symbolic constants listed here are
defined in @file{sys/socket.h}.
@pindex sys/socket.h
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int SOCK_STREAM
-The @code{SOCK_STREAM} style is like a pipe (@pxref{Pipes and FIFOs});
-it operates over a connection with a particular remote socket, and
+@standards{BSD, sys/socket.h}
+The @code{SOCK_STREAM} style is like a pipe (@pxref{Pipes and FIFOs}).
+It operates over a connection with a particular remote socket and
transmits data reliably as a stream of bytes.
Use of this style is covered in detail in @ref{Connections}.
@end deftypevr
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int SOCK_DGRAM
+@standards{BSD, sys/socket.h}
The @code{SOCK_DGRAM} style is used for sending
-individually-addressed packets, unreliably.
+individually-addressed packets unreliably.
It is the diametrical opposite of @code{SOCK_STREAM}.
Each time you write data to a socket of this kind, that data becomes
sixth, and may arrive a second time after the sixth.
The typical use for @code{SOCK_DGRAM} is in situations where it is
-acceptable to simply resend a packet if no response is seen in a
+acceptable to simply re-send a packet if no response is seen in a
reasonable amount of time.
@xref{Datagrams}, for detailed information about how to use datagram
@ignore
@c This appears to be only for the NS domain, which we aren't
@c discussing and probably won't support either.
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int SOCK_SEQPACKET
-This style is like @code{SOCK_STREAM} except that the data is
+@standards{BSD, sys/socket.h}
+This style is like @code{SOCK_STREAM} except that the data are
structured into packets.
A program that receives data over a @code{SOCK_SEQPACKET} socket
@end ignore
@ignore
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int SOCK_RDM
+@standards{BSD, sys/socket.h}
This style is a reliable version of @code{SOCK_DGRAM}: it sends
individually addressed packets, but guarantees that each packet sent
arrives exactly once.
@end deftypevr
@end ignore
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int SOCK_RAW
+@standards{BSD, sys/socket.h}
This style provides access to low-level network protocols and
interfaces. Ordinary user programs usually have no need to use this
style.
give it an address. We call this @dfn{binding} the address to the
socket, and the way to do it is with the @code{bind} function.
-You need be concerned with the address of a socket if other processes
+You need only be concerned with the address of a socket if other processes
are to find it and start communicating with it. You can specify an
address for other sockets, but this is usually pointless; the first time
you send data from a socket, or use it to initiate a connection, the
system assigns an address automatically if you have not specified one.
Occasionally a client needs to specify an address because the server
-discriminates based on addresses; for example, the rsh and rlogin
-protocols look at the client's socket address and don't bypass password
-checking unless it is less than @code{IPPORT_RESERVED} (@pxref{Ports}).
+discriminates based on address; for example, the rsh and rlogin
+protocols look at the client's socket address and only bypass passphrase
+checking if it is less than @code{IPPORT_RESERVED} (@pxref{Ports}).
The details of socket addresses vary depending on what namespace you are
-using. @xref{File Namespace}, or @ref{Internet Namespace}, for specific
+using. @xref{Local Namespace}, or @ref{Internet Namespace}, for specific
information.
Regardless of the namespace, you use the same functions @code{bind} and
address or construct one; for that, you must use the proper data type
for the socket's namespace.
-Thus, the usual practice is to construct an address in the proper
+Thus, the usual practice is to construct an address of the proper
namespace-specific type, then cast a pointer to @code{struct sockaddr *}
when you call @code{bind} or @code{getsockname}.
The one piece of information that you can get from the @code{struct
-sockaddr} data type is the @dfn{address format} designator which tells
+sockaddr} data type is the @dfn{address format designator}. This tells
you which data type to use to understand the address fully.
@pindex sys/socket.h
The symbols in this section are defined in the header file
@file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
-@deftp {Date Type} {struct sockaddr}
+@deftp {Data Type} {struct sockaddr}
+@standards{BSD, sys/socket.h}
The @code{struct sockaddr} type itself has the following members:
@table @code
Each of them corresponds to a @samp{PF_} symbol which designates the
corresponding namespace. Here is a list of address format names:
-@table @code
-@comment sys/socket.h
-@comment GNU
-@item AF_FILE
-@vindex AF_FILE
-This designates the address format that goes with the file namespace.
-(@code{PF_FILE} is the name of that namespace.) @xref{File Namespace
+@vtable @code
+@item AF_LOCAL
+@standards{POSIX, sys/socket.h}
+This designates the address format that goes with the local namespace.
+(@code{PF_LOCAL} is the name of that namespace.) @xref{Local Namespace
Details}, for information about this address format.
-@comment sys/socket.h
-@comment BSD
@item AF_UNIX
-@vindex AF_UNIX
-This is a synonym for @code{AF_FILE}, for compatibility.
-(@code{PF_UNIX} is likewise a synonym for @code{PF_FILE}.)
+@standards{BSD, sys/socket.h}
+@standards{Unix98, sys/socket.h}
+This is a synonym for @code{AF_LOCAL}. Although @code{AF_LOCAL} is
+mandated by POSIX.1g, @code{AF_UNIX} is portable to more systems.
+@code{AF_UNIX} was the traditional name stemming from BSD, so even most
+POSIX systems support it. It is also the name of choice in the Unix98
+specification. (The same is true for @code{PF_UNIX}
+vs. @code{PF_LOCAL}).
+
+@item AF_FILE
+@standards{GNU, sys/socket.h}
+This is another synonym for @code{AF_LOCAL}, for compatibility.
+(@code{PF_FILE} is likewise a synonym for @code{PF_LOCAL}.)
-@comment sys/socket.h
-@comment BSD
@item AF_INET
-@vindex AF_INET
+@standards{BSD, sys/socket.h}
This designates the address format that goes with the Internet
namespace. (@code{PF_INET} is the name of that namespace.)
@xref{Internet Address Formats}.
-@comment sys/socket.h
-@comment IPv6 Basic API
@item AF_INET6
+@standards{IPv6 Basic API, sys/socket.h}
This is similar to @code{AF_INET}, but refers to the IPv6 protocol.
(@code{PF_INET6} is the name of the corresponding namespace.)
-@comment sys/socket.h
-@comment BSD
@item AF_UNSPEC
-@vindex AF_UNSPEC
+@standards{BSD, sys/socket.h}
This designates no particular address format. It is used only in rare
cases, such as to clear out the default destination address of a
``connected'' datagram socket. @xref{Sending Datagrams}.
The corresponding namespace designator symbol @code{PF_UNSPEC} exists
for completeness, but there is no reason to use it in a program.
-@end table
+@end vtable
@file{sys/socket.h} defines symbols starting with @samp{AF_} for many
-different kinds of networks, all or most of which are not actually
-implemented. We will document those that really work, as we receive
+different kinds of networks, most or all of which are not actually
+implemented. We will document those that really work as we receive
information about how to use them.
@node Setting Address
@pindex sys/socket.h
Use the @code{bind} function to assign an address to a socket. The
prototype for @code{bind} is in the header file @file{sys/socket.h}.
-For examples of use, see @ref{File Namespace}, or see @ref{Inet Example}.
+For examples of use, see @ref{Local Socket Example}, or see @ref{Inet Example}.
-@comment sys/socket.h
-@comment BSD
@deftypefun int bind (int @var{socket}, struct sockaddr *@var{addr}, socklen_t @var{length})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c Direct syscall, except on Hurd.
The @code{bind} function assigns an address to the socket
@var{socket}. The @var{addr} and @var{length} arguments specify the
address; the detailed format of the address depends on the namespace.
The first part of the address is always the format designator, which
-specifies a namespace, and says that the address is in the format for
+specifies a namespace, and says that the address is in the format of
that namespace.
The return value is @code{0} on success and @code{-1} on failure. The
Internet socket. The prototype for this function is in the header file
@file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
@deftypefun int getsockname (int @var{socket}, struct sockaddr *@var{addr}, socklen_t *@var{length-ptr})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsmem{/hurd}}}
+@c Direct syscall, except on Hurd, where it seems like it might leak
+@c VM if cancelled.
The @code{getsockname} function returns information about the
address of the socket @var{socket} in the locations specified by the
@var{addr} and @var{length-ptr} arguments. Note that the
consistent with the rest of the system; in general, there's no way to
find a file's name from a descriptor for that file.
-@node File Namespace
-@section The File Namespace
-@cindex file namespace, for sockets
+@node Interface Naming
+@section Interface Naming
+
+Each network interface has a name. This usually consists of a few
+letters that relate to the type of interface, which may be followed by a
+number if there is more than one interface of that type. Examples
+might be @code{lo} (the loopback interface) and @code{eth0} (the first
+Ethernet interface).
+
+Although such names are convenient for humans, it would be clumsy to
+have to use them whenever a program needs to refer to an interface. In
+such situations an interface is referred to by its @dfn{index}, which is
+an arbitrarily-assigned small positive integer.
+
+The following functions, constants and data types are declared in the
+header file @file{net/if.h}.
+
+@deftypevr Constant size_t IFNAMSIZ
+@standards{???, net/if.h}
+This constant defines the maximum buffer size needed to hold an
+interface name, including its terminating zero byte.
+@end deftypevr
+
+@deftypefun {unsigned int} if_nametoindex (const char *@var{ifname})
+@standards{IPv6 basic API, net/if.h}
+@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
+@c It opens a socket to use ioctl on the fd to get the index.
+@c opensock may call socket and access multiple times until it finds a
+@c socket family that works. The Linux implementation has a potential
+@c concurrency issue WRT last_type and last_family not being updated
+@c atomically, but it is harmless; the generic implementation, OTOH,
+@c takes a lock, which makes all callers AS- and AC-Unsafe.
+@c opensock @asulock @aculock @acsfd
+This function yields the interface index corresponding to a particular
+name. If no interface exists with the name given, it returns 0.
+@end deftypefun
+
+@deftypefun {char *} if_indextoname (unsigned int @var{ifindex}, char *@var{ifname})
+@standards{IPv6 basic API, net/if.h}
+@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{}}}
+@c It opens a socket with opensock to use ioctl on the fd to get the
+@c name from the index.
+This function maps an interface index to its corresponding name. The
+returned name is placed in the buffer pointed to by @code{ifname}, which
+must be at least @code{IFNAMSIZ} bytes in length. If the index was
+invalid, the function's return value is a null pointer, otherwise it is
+@code{ifname}.
+@end deftypefun
+
+@deftp {Data Type} {struct if_nameindex}
+@standards{IPv6 basic API, net/if.h}
+This data type is used to hold the information about a single
+interface. It has the following members:
-This section describes the details of the file namespace, whose
-symbolic name (required when you create a socket) is @code{PF_FILE}.
+@table @code
+@item unsigned int if_index;
+This is the interface index.
+
+@item char *if_name
+This is the null-terminated index name.
+
+@end table
+@end deftp
+
+@deftypefun {struct if_nameindex *} if_nameindex (void)
+@standards{IPv6 basic API, net/if.h}
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{/hurd}}@acunsafe{@aculock{/hurd} @acsfd{} @acsmem{}}}
+@c if_nameindex @ascuheap @asulock/hurd @aculock/hurd @acsfd @acsmem
+@c [linux]
+@c netlink_open @acsfd @acsmem/hurd
+@c socket dup @acsfd
+@c memset dup ok
+@c bind dup ok
+@c netlink_close dup @acsfd
+@c getsockname dup @acsmem/hurd
+@c netlink_request @ascuheap @acsmem
+@c getpagesize dup ok
+@c malloc dup @ascuheap @acsmem
+@c netlink_sendreq ok
+@c memset dup ok
+@c sendto dup ok
+@c recvmsg dup ok
+@c memcpy dup ok
+@c free dup @ascuheap @acsmem
+@c netlink_free_handle @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c netlink_close @acsfd
+@c close dup @acsfd
+@c malloc dup @asuheap @acsmem
+@c strndup @ascuheap @acsmem
+@c if_freenameindex @ascuheap @acsmem
+@c [hurd]
+@c opensock dup @asulock @aculock @acsfd
+@c hurd_socket_server ok
+@c pfinet_siocgifconf ok
+@c malloc @ascuheap @acsmem
+@c strdup @ascuheap @acsmem
+@c ioctl dup ok
+@c free @ascuheap @acsmem
+This function returns an array of @code{if_nameindex} structures, one
+for every interface that is present. The end of the list is indicated
+by a structure with an interface of 0 and a null name pointer. If an
+error occurs, this function returns a null pointer.
+
+The returned structure must be freed with @code{if_freenameindex} after
+use.
+@end deftypefun
+
+@deftypefun void if_freenameindex (struct if_nameindex *@var{ptr})
+@standards{IPv6 basic API, net/if.h}
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}}
+@c if_freenameindex @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+This function frees the structure returned by an earlier call to
+@code{if_nameindex}.
+@end deftypefun
+
+@node Local Namespace
+@section The Local Namespace
+@cindex local namespace, for sockets
+
+This section describes the details of the local namespace, whose
+symbolic name (required when you create a socket) is @code{PF_LOCAL}.
+The local namespace is also known as ``Unix domain sockets''. Another
+name is file namespace since socket addresses are normally implemented
+as file names.
@menu
-* Concepts: File Namespace Concepts. What you need to understand.
-* Details: File Namespace Details. Address format, symbolic names, etc.
-* Example: File Socket Example. Example of creating a socket.
+* Concepts: Local Namespace Concepts. What you need to understand.
+* Details: Local Namespace Details. Address format, symbolic names, etc.
+* Example: Local Socket Example. Example of creating a socket.
@end menu
-@node File Namespace Concepts
-@subsection File Namespace Concepts
+@node Local Namespace Concepts
+@subsection Local Namespace Concepts
-In the file namespace, socket addresses are file names. You can specify
+In the local namespace socket addresses are file names. You can specify
any file name you want as the address of the socket, but you must have
-write permission on the directory containing it. In order to connect to
-a socket, you must have read permission for it. It's common to put
-these files in the @file{/tmp} directory.
+write permission on the directory containing it.
+@c XXX The following was said to be wrong.
+@c In order to connect to a socket you must have read permission for it.
+It's common to put these files in the @file{/tmp} directory.
-One peculiarity of the file namespace is that the name is only used when
-opening the connection; once that is over with, the address is not
-meaningful and may not exist.
+One peculiarity of the local namespace is that the name is only used
+when opening the connection; once open the address is not meaningful and
+may not exist.
Another peculiarity is that you cannot connect to such a socket from
another machine--not even if the other machine shares the file system
the same file systems. Instead, send each new client an identifying
number if you want it to have one.
-After you close a socket in the file namespace, you should delete the
+After you close a socket in the local namespace, you should delete the
file name from the file system. Use @code{unlink} or @code{remove} to
do this; see @ref{Deleting Files}.
-The file namespace supports just one protocol for any communication
+The local namespace supports just one protocol for any communication
style; it is protocol number @code{0}.
-@node File Namespace Details
-@subsection Details of File Namespace
+@node Local Namespace Details
+@subsection Details of Local Namespace
@pindex sys/socket.h
-To create a socket in the file namespace, use the constant
-@code{PF_FILE} as the @var{namespace} argument to @code{socket} or
+To create a socket in the local namespace, use the constant
+@code{PF_LOCAL} as the @var{namespace} argument to @code{socket} or
@code{socketpair}. This constant is defined in @file{sys/socket.h}.
-@comment sys/socket.h
-@comment GNU
-@deftypevr Macro int PF_FILE
-This designates the file namespace, in which socket addresses are file
-names, and its associated family of protocols.
+@deftypevr Macro int PF_LOCAL
+@standards{POSIX, sys/socket.h}
+This designates the local namespace, in which socket addresses are local
+names, and its associated family of protocols. @code{PF_LOCAL} is the
+macro used by POSIX.1g.
@end deftypevr
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int PF_UNIX
-This is a synonym for @code{PF_FILE}, for compatibility's sake.
+@standards{BSD, sys/socket.h}
+This is a synonym for @code{PF_LOCAL}, for compatibility's sake.
@end deftypevr
-The structure for specifying socket names in the file namespace is
+@deftypevr Macro int PF_FILE
+@standards{GNU, sys/socket.h}
+This is a synonym for @code{PF_LOCAL}, for compatibility's sake.
+@end deftypevr
+
+The structure for specifying socket names in the local namespace is
defined in the header file @file{sys/un.h}:
@pindex sys/un.h
-@comment sys/un.h
-@comment BSD
@deftp {Data Type} {struct sockaddr_un}
-This structure is used to specify file namespace socket addresses. It has
+@standards{BSD, sys/un.h}
+This structure is used to specify local namespace socket addresses. It has
the following members:
@table @code
@item short int sun_family
This identifies the address family or format of the socket address.
-You should store the value @code{AF_FILE} to designate the file
+You should store the value @code{AF_LOCAL} to designate the local
namespace. @xref{Socket Addresses}.
@item char sun_path[108]
This is the file name to use.
@strong{Incomplete:} Why is 108 a magic number? RMS suggests making
-this a zero-length array and tweaking the example following to use
+this a zero-length array and tweaking the following example to use
@code{alloca} to allocate an appropriate amount of storage based on
the length of the filename.
@end table
@end deftp
You should compute the @var{length} parameter for a socket address in
-the file namespace as the sum of the size of the @code{sun_family}
+the local namespace as the sum of the size of the @code{sun_family}
component and the string length (@emph{not} the allocation size!) of
-the file name string.
+the file name string. This can be done using the macro @code{SUN_LEN}:
+
+@deftypefn {Macro} int SUN_LEN (@emph{struct sockaddr_un *} @var{ptr})
+@standards{BSD, sys/un.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+This macro computes the length of the socket address in the local namespace.
+@end deftypefn
-@node File Socket Example
-@subsection Example of File-Namespace Sockets
+@node Local Socket Example
+@subsection Example of Local-Namespace Sockets
-Here is an example showing how to create and name a socket in the file
+Here is an example showing how to create and name a socket in the local
namespace.
@smallexample
@section The Internet Namespace
@cindex Internet namespace, for sockets
-This section describes the details the protocols and socket naming
+This section describes the details of the protocols and socket naming
conventions used in the Internet namespace.
-To create a socket in the Internet namespace, use the symbolic name
+Originally the Internet namespace used only IP version 4 (IPv4). With
+the growing number of hosts on the Internet, a new protocol with a
+larger address space was necessary: IP version 6 (IPv6). IPv6
+introduces 128-bit addresses (IPv4 has 32-bit addresses) and other
+features, and will eventually replace IPv4.
+
+To create a socket in the IPv4 Internet namespace, use the symbolic name
@code{PF_INET} of this namespace as the @var{namespace} argument to
-@code{socket} or @code{socketpair}. This macro is defined in
-@file{sys/socket.h}.
+@code{socket} or @code{socketpair}. For IPv6 addresses you need the
+macro @code{PF_INET6}. These macros are defined in @file{sys/socket.h}.
@pindex sys/socket.h
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int PF_INET
-This designates the Internet namespace and associated family of
+@standards{BSD, sys/socket.h}
+This designates the IPv4 Internet namespace and associated family of
+protocols.
+@end deftypevr
+
+@deftypevr Macro int PF_INET6
+@standards{X/Open, sys/socket.h}
+This designates the IPv6 Internet namespace and associated family of
protocols.
@end deftypevr
@item
The address of the machine you want to connect to. Internet addresses
can be specified in several ways; these are discussed in @ref{Internet
-Address Formats}, @ref{Host Addresses}, and @ref{Host Names}.
+Address Formats}, @ref{Host Addresses} and @ref{Host Names}.
@item
A port number for that machine. @xref{Ports}.
@menu
* Internet Address Formats:: How socket addresses are specified in the
Internet namespace.
-* Host Addresses:: All about host addresses of internet host.
-* Protocols Database:: Referring to protocols by name.
+* Host Addresses:: All about host addresses of Internet host.
* Ports:: Internet port numbers.
* Services Database:: Ports may have symbolic names.
* Byte Order:: Different hosts may use different byte
ordering conventions; you need to
canonicalize host address and port number.
+* Protocols Database:: Referring to protocols by name.
* Inet Example:: Putting it all together.
@end menu
are defined in the header file @file{netinet/in.h}.
@pindex netinet/in.h
-@comment netinet/in.h
-@comment BSD
@deftp {Data Type} {struct sockaddr_in}
+@standards{BSD, netinet/in.h}
This is the data type used to represent socket addresses in the
Internet namespace. It has the following members:
@table @code
-@item short int sin_family
+@item sa_family_t sin_family
This identifies the address family or format of the socket address.
-You should store the value of @code{AF_INET} in this member.
-@xref{Socket Addresses}.
+You should store the value @code{AF_INET} in this member. The address
+family is stored in host byte order. @xref{Socket Addresses}.
@item struct in_addr sin_addr
-This is the Internet address of the host machine. @xref{Host
-Addresses}, and @ref{Host Names}, for how to get a value to store
-here.
+This is the IPv4 address. @xref{Host Addresses}, and @ref{Host
+Names}, for how to get a value to store here. The IPv4 address is
+stored in network byte order.
@item unsigned short int sin_port
-This is the port number. @xref{Ports}.
+This is the port number. @xref{Ports}. The port number is stored in
+network byte order.
@end table
@end deftp
When you call @code{bind} or @code{getsockname}, you should specify
@code{sizeof (struct sockaddr_in)} as the @var{length} parameter if
-you are using an Internet namespace socket address.
+you are using an IPv4 Internet namespace socket address.
@deftp {Data Type} {struct sockaddr_in6}
This is the data type used to represent socket addresses in the IPv6
namespace. It has the following members:
@table @code
-@item short int sin6_family
+@item sa_family_t sin6_family
This identifies the address family or format of the socket address.
You should store the value of @code{AF_INET6} in this member.
-@xref{Socket Addresses}.
+@xref{Socket Addresses}. The address family is stored in host byte
+order.
@item struct in6_addr sin6_addr
This is the IPv6 address of the host machine. @xref{Host
Addresses}, and @ref{Host Names}, for how to get a value to store
-here.
+here. The address is stored in network byte order.
@item uint32_t sin6_flowinfo
-This is a currently unimplemented field.
+@cindex flow label
+@cindex IPv6 flow label
+@cindex traffic class
+@cindex IPv6 traffic class
+This combines the IPv6 traffic class and flow label values, as found
+in the IPv6 header. This field is stored in network byte order. Only
+the 28 lower bits (of the number in network byte order) are used; the
+remainig bits must be zero. The lower 20 bits are the flow label, and
+bits 20 to 27 are the the traffic class. Typically, this field is
+zero.
+
+@item uint32_t sin6_scope_id
+@cindex scope ID
+@cindex IPv6 scope ID
+For link-local addresses, this identifies the interface on which this
+address is valid. The scope ID is stored in host byte order.
+Typically, this field is zero.
@item uint16_t sin6_port
-This is the port number. @xref{Ports}.
+This is the port number. @xref{Ports}. The port number is stored in
+network byte order.
@end table
@end deftp
colons, as in @samp{5f03:1200:836f:c100::1}.
Each computer also has one or more @dfn{host names}, which are strings
-of words separated by periods, as in @samp{churchy.gnu.ai.mit.edu}.
+of words separated by periods, as in @samp{www.gnu.org}.
Programs that let the user specify a host typically accept both numeric
-addresses and host names. But the program needs a numeric address to
-open a connection; to use a host name, you must convert it to the
-numeric address it stands for.
+addresses and host names. To open a connection a program needs a
+numeric address, and so must convert a host name to the numeric address
+it stands for.
@menu
* Abstract Host Addresses:: What a host number consists of.
numbers which identify that computer among all those on the Internet.
@end ifinfo
-@c I think this whole section could possibly be removed. It is slightly
-@c misleading these days.
-
@cindex network number
@cindex local network address number
-An Internet host address is a number containing four bytes of data.
-These are divided into two parts, a @dfn{network number} and a
-@dfn{local network address number} within that network. The network
-number consists of the first one, two or three bytes; the rest of the
-bytes are the local address.
-
-Network numbers are registered with the Network Information Center
-(NIC), and are divided into three classes---A, B, and C. The local
+An IPv4 Internet host address is a number containing four bytes of data.
+Historically these are divided into two parts, a @dfn{network number} and a
+@dfn{local network address number} within that network. In the
+mid-1990s classless addresses were introduced which changed this
+behavior. Since some functions implicitly expect the old definitions,
+we first describe the class-based network and will then describe
+classless addresses. IPv6 uses only classless addresses and therefore
+the following paragraphs don't apply.
+
+The class-based IPv4 network number consists of the first one, two or
+three bytes; the rest of the bytes are the local address.
+
+IPv4 network numbers are registered with the Network Information Center
+(NIC), and are divided into three classes---A, B and C. The local
network address numbers of individual machines are registered with the
administrator of the particular network.
network numbers, with the first byte in the range 128 to 191. Class C
networks are the smallest; they have three-byte network numbers, with
the first byte in the range 192-255. Thus, the first 1, 2, or 3 bytes
-of an Internet address specifies a network. The remaining bytes of the
+of an Internet address specify a network. The remaining bytes of the
Internet address specify the address within that network.
The Class A network 0 is reserved for broadcast to all networks. In
addition, the host number 0 within each network is reserved for broadcast
-to all hosts in that network.
+to all hosts in that network. These uses are obsolete now but for
+compatibility reasons you shouldn't use network 0 and host number 0.
The Class A network 127 is reserved for loopback; you can always use
the Internet address @samp{127.0.0.1} to refer to the host machine.
supposed to be more than one machine with the same host address.
@c !!! this section could document the IN_CLASS* macros in <netinet/in.h>.
+@c No, it shouldn't since they're obsolete.
@cindex standard dot notation, for Internet addresses
@cindex dot notation, for Internet addresses
@table @code
@item @var{a}.@var{b}.@var{c}.@var{d}
-This specifies all four bytes of the address individually.
+This specifies all four bytes of the address individually and is the
+commonly used representation.
@item @var{a}.@var{b}.@var{c}
The last part of the address, @var{c}, is interpreted as a 2-byte quantity.
network address number @code{@var{a}.@var{b}}.
@item @var{a}.@var{b}
-The last part of the address, @var{c}, is interpreted as a 3-byte quantity.
+The last part of the address, @var{b}, is interpreted as a 3-byte quantity.
This is useful for specifying host addresses in a Class A network with
network address number @var{a}.
hexadecimal radix; a leading @samp{0} implies octal; and otherwise decimal
radix is assumed.
+@subsubheading Classless Addresses
+
+IPv4 addresses (and IPv6 addresses also) are now considered classless;
+the distinction between classes A, B and C can be ignored. Instead an
+IPv4 host address consists of a 32-bit address and a 32-bit mask. The
+mask contains set bits for the network part and cleared bits for the
+host part. The network part is contiguous from the left, with the
+remaining bits representing the host. As a consequence, the netmask can
+simply be specified as the number of set bits. Classes A, B and C are
+just special cases of this general rule. For example, class A addresses
+have a netmask of @samp{255.0.0.0} or a prefix length of 8.
+
+Classless IPv4 network addresses are written in numbers-and-dots
+notation with the prefix length appended and a slash as separator. For
+example the class A network 10 is written as @samp{10.0.0.0/8}.
+
+@subsubheading IPv6 Addresses
+
+IPv6 addresses contain 128 bits (IPv4 has 32 bits) of data. A host
+address is usually written as eight 16-bit hexadecimal numbers that are
+separated by colons. Two colons are used to abbreviate strings of
+consecutive zeros. For example, the IPv6 loopback address
+@samp{0:0:0:0:0:0:0:1} can just be written as @samp{::1}.
+
@node Host Address Data Type
@subsubsection Host Address Data Type
-Internet host addresses are represented in some contexts as integers
-(type @code{unsigned long int}). In other contexts, the integer is
+IPv4 Internet host addresses are represented in some contexts as integers
+(type @code{uint32_t}). In other contexts, the integer is
packaged inside a structure of type @code{struct in_addr}. It would
be better if the usage were made consistent, but it is not hard to extract
the integer from the structure or put the integer into a structure.
-The following basic definitions for Internet addresses appear in the
-header file@*@file{netinet/in.h}:
+You will find older code that uses @code{unsigned long int} for
+IPv4 Internet host addresses instead of @code{uint32_t} or @code{struct
+in_addr}. Historically @code{unsigned long int} was a 32-bit number but
+with 64-bit machines this has changed. Using @code{unsigned long int}
+might break the code if it is used on machines where this type doesn't
+have 32 bits. @code{uint32_t} is specified by Unix98 and guaranteed to have
+32 bits.
+
+IPv6 Internet host addresses have 128 bits and are packaged inside a
+structure of type @code{struct in6_addr}.
+
+The following basic definitions for Internet addresses are declared in
+the header file @file{netinet/in.h}:
@pindex netinet/in.h
-@comment netinet/in.h
-@comment BSD
@deftp {Data Type} {struct in_addr}
-This data type is used in certain contexts to contain an Internet host
-address. It has just one field, named @code{s_addr}, which records the
-host address number as an @code{unsigned long int}.
+@standards{BSD, netinet/in.h}
+This data type is used in certain contexts to contain an IPv4 Internet
+host address. It has just one field, named @code{s_addr}, which records
+the host address number as an @code{uint32_t}.
@end deftp
-@comment netinet/in.h
-@comment BSD
-@deftypevr Macro {unsigned int} INADDR_LOOPBACK
+@deftypevr Macro {uint32_t} INADDR_LOOPBACK
+@standards{BSD, netinet/in.h}
You can use this constant to stand for ``the address of this machine,''
-instead of finding its actual address. It is the Internet address
+instead of finding its actual address. It is the IPv4 Internet address
@samp{127.0.0.1}, which is usually called @samp{localhost}. This
special constant saves you the trouble of looking up the address of your
own machine. Also, the system usually implements @code{INADDR_LOOPBACK}
talking to itself.
@end deftypevr
-@comment netinet/in.h
-@comment BSD
-@deftypevr Macro {unsigned int} INADDR_ANY
-You can use this constant to stand for ``any incoming address,'' when
+@deftypevr Macro {uint32_t} INADDR_ANY
+@standards{BSD, netinet/in.h}
+You can use this constant to stand for ``any incoming address'' when
binding to an address. @xref{Setting Address}. This is the usual
address to give in the @code{sin_addr} member of @w{@code{struct
sockaddr_in}} when you want to accept Internet connections.
@end deftypevr
-@comment netinet/in.h
-@comment BSD
-@deftypevr Macro {unsigned int} INADDR_BROADCAST
+@deftypevr Macro {uint32_t} INADDR_BROADCAST
+@standards{BSD, netinet/in.h}
This constant is the address you use to send a broadcast message.
@c !!! broadcast needs further documented
@end deftypevr
-@comment netinet/in.h
-@comment BSD
-@deftypevr Macro {unsigned int} INADDR_NONE
+@deftypevr Macro {uint32_t} INADDR_NONE
+@standards{BSD, netinet/in.h}
This constant is returned by some functions to indicate an error.
@end deftypevr
-@comment netinet/in.h
-@comment IPv6 basic API
@deftp {Data Type} {struct in6_addr}
+@standards{IPv6 basic API, netinet/in.h}
This data type is used to store an IPv6 address. It stores 128 bits of
data, which can be accessed (via a union) in a variety of ways.
@end deftp
-@comment netinet/in.h
-@comment IPv6 basic API
-@deftypevr Constant {struct in6_addr} in6addr_loopback.
+@deftypevr Constant {struct in6_addr} in6addr_loopback
+@standards{IPv6 basic API, netinet/in.h}
This constant is the IPv6 address @samp{::1}, the loopback address. See
above for a description of what this means. The macro
-@code{IN6ADDR_LOOPBACK_INIT} is provided to allow you to initialise your
+@code{IN6ADDR_LOOPBACK_INIT} is provided to allow you to initialize your
own variables to this value.
@end deftypevr
-@comment netinet/in.h
-@comment IPv6 basic API
@deftypevr Constant {struct in6_addr} in6addr_any
+@standards{IPv6 basic API, netinet/in.h}
This constant is the IPv6 address @samp{::}, the unspecified address. See
above for a description of what this means. The macro
-@code{IN6ADDR_ANY_INIT} is provided to allow you to initialise your
+@code{IN6ADDR_ANY_INIT} is provided to allow you to initialize your
own variables to this value.
@end deftypevr
@pindex arpa/inet.h
@noindent
These additional functions for manipulating Internet addresses are
-declared in@*@file{arpa/inet.h}. They represent Internet addresses in
-network byte order; they represent network numbers and
-local-address-within-network numbers in host byte order.
-@xref{Byte Order}, for an explanation of network and host byte order.
+declared in the header file @file{arpa/inet.h}. They represent Internet
+addresses in network byte order, and network numbers and
+local-address-within-network numbers in host byte order. @xref{Byte
+Order}, for an explanation of network and host byte order.
-@comment arpa/inet.h
-@comment BSD
@deftypefun int inet_aton (const char *@var{name}, struct in_addr *@var{addr})
-This function converts the Internet host address @var{name}
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}}
+@c inet_aton @mtslocale
+@c isdigit dup @mtslocale
+@c strtoul dup @mtslocale
+@c isascii dup @mtslocale
+@c isspace dup @mtslocale
+@c htonl dup ok
+This function converts the IPv4 Internet host address @var{name}
from the standard numbers-and-dots notation into binary data and stores
it in the @code{struct in_addr} that @var{addr} points to.
@code{inet_aton} returns nonzero if the address is valid, zero if not.
@end deftypefun
-@comment arpa/inet.h
-@comment BSD
-@deftypefun {unsigned long int} inet_addr (const char *@var{name})
-This function converts the Internet host address @var{name} from the
+@deftypefun {uint32_t} inet_addr (const char *@var{name})
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}}
+@c inet_addr @mtslocale
+@c inet_aton dup @mtslocale
+This function converts the IPv4 Internet host address @var{name} from the
standard numbers-and-dots notation into binary data. If the input is
not valid, @code{inet_addr} returns @code{INADDR_NONE}. This is an
-obsolete interface to @code{inet_aton}, described immediately above; it
+obsolete interface to @code{inet_aton}, described immediately above. It
is obsolete because @code{INADDR_NONE} is a valid address
(255.255.255.255), and @code{inet_aton} provides a cleaner way to
indicate error return.
@end deftypefun
-@comment arpa/inet.h
-@comment BSD
-@deftypefun {unsigned long int} inet_network (const char *@var{name})
+@deftypefun {uint32_t} inet_network (const char *@var{name})
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}}
+@c inet_network @mtslocale
+@c isdigit dup @mtslocale
+@c isxdigit dup @mtslocale
+@c tolower dup @mtslocale
+@c isspace dup @mtslocale
This function extracts the network number from the address @var{name},
-given in the standard numbers-and-dots notation. The returned address is
-in host order. If the input is not valid, @code{inet_network} returns
+given in the standard numbers-and-dots notation. The returned address is
+in host order. If the input is not valid, @code{inet_network} returns
@code{-1}.
+
+The function works only with traditional IPv4 class A, B and C network
+types. It doesn't work with classless addresses and shouldn't be used
+anymore.
@end deftypefun
-@comment arpa/inet.h
-@comment BSD
@deftypefun {char *} inet_ntoa (struct in_addr @var{addr})
-This function converts the Internet host address @var{addr} to a
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{@mtslocale{}}@asunsafe{@asurace{}}@acsafe{}}
+@c inet_ntoa @mtslocale @asurace
+@c writes to a thread-local static buffer
+@c snprintf @mtslocale [no @ascuheap or @acsmem]
+This function converts the IPv4 Internet host address @var{addr} to a
string in the standard numbers-and-dots notation. The return value is
a pointer into a statically-allocated buffer. Subsequent calls will
overwrite the same buffer, so you should copy the string if you need
to save it.
-In multi-threaded programs each thread has an own statically-allocated
+In multi-threaded programs each thread has its own statically-allocated
buffer. But still subsequent calls of @code{inet_ntoa} in the same
thread will overwrite the result of the last call.
+
+Instead of @code{inet_ntoa} the newer function @code{inet_ntop} which is
+described below should be used since it handles both IPv4 and IPv6
+addresses.
@end deftypefun
-@comment arpa/inet.h
-@comment BSD
-@deftypefun {struct in_addr} inet_makeaddr (int @var{net}, int @var{local})
-This function makes an Internet host address by combining the network
+@deftypefun {struct in_addr} inet_makeaddr (uint32_t @var{net}, uint32_t @var{local})
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c inet_makeaddr ok
+@c htonl dup ok
+This function makes an IPv4 Internet host address by combining the network
number @var{net} with the local-address-within-network number
@var{local}.
@end deftypefun
-@comment arpa/inet.h
-@comment BSD
-@deftypefun int inet_lnaof (struct in_addr @var{addr})
+@deftypefun uint32_t inet_lnaof (struct in_addr @var{addr})
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c inet_lnaof ok
+@c ntohl dup ok
+@c IN_CLASSA ok
+@c IN_CLASSB ok
This function returns the local-address-within-network part of the
Internet host address @var{addr}.
+
+The function works only with traditional IPv4 class A, B and C network
+types. It doesn't work with classless addresses and shouldn't be used
+anymore.
@end deftypefun
-@comment arpa/inet.h
-@comment BSD
-@deftypefun int inet_netof (struct in_addr @var{addr})
+@deftypefun uint32_t inet_netof (struct in_addr @var{addr})
+@standards{BSD, arpa/inet.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c inet_netof ok
+@c ntohl dup ok
+@c IN_CLASSA ok
+@c IN_CLASSB ok
This function returns the network number part of the Internet host
address @var{addr}.
+
+The function works only with traditional IPv4 class A, B and C network
+types. It doesn't work with classless addresses and shouldn't be used
+anymore.
@end deftypefun
-@comment arpa/inet.h
-@comment IPv6 basic API
@deftypefun int inet_pton (int @var{af}, const char *@var{cp}, void *@var{buf})
+@standards{IPv6 basic API, arpa/inet.h}
+@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}}
+@c inet_pton @mtslocale
+@c inet_pton4 ok
+@c memcpy dup ok
+@c inet_pton6 @mtslocale
+@c memset dup ok
+@c tolower dup @mtslocale
+@c strchr dup ok
+@c inet_pton4 dup ok
+@c memcpy dup ok
This function converts an Internet address (either IPv4 or IPv6) from
presentation (textual) to network (binary) format. @var{af} should be
either @code{AF_INET} or @code{AF_INET6}, as appropriate for the type of
responsibility to make sure the buffer is large enough.
@end deftypefun
-@comment arpa/inet.h
-@comment IPv6 basic API
-@deftypefun {char *} inet_ntop (int @var{af}, const void *@var{cp}, char *@var{buf}, size_t @var{len})
+@deftypefun {const char *} inet_ntop (int @var{af}, const void *@var{cp}, char *@var{buf}, socklen_t @var{len})
+@standards{IPv6 basic API, arpa/inet.h}
+@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}}
+@c inet_ntop @mtslocale
+@c inet_ntop4 @mtslocale
+@c sprintf dup @mtslocale [no @ascuheap or @acsmem]
+@c strcpy dup ok
+@c inet_ntop6 @mtslocale
+@c memset dup ok
+@c inet_ntop4 dup @mtslocale
+@c sprintf dup @mtslocale [no @ascuheap or @acsmem]
+@c strcpy dup ok
This function converts an Internet address (either IPv4 or IPv6) from
network (binary) to presentation (textual) form. @var{af} should be
either @code{AF_INET} or @code{AF_INET6}, as appropriate. @var{cp} is a
Besides the standard numbers-and-dots notation for Internet addresses,
you can also refer to a host by a symbolic name. The advantage of a
symbolic name is that it is usually easier to remember. For example,
-the machine with Internet address @samp{128.52.46.32} is also known as
-@samp{churchy.gnu.ai.mit.edu}; and other machines in the @samp{gnu.ai.mit.edu}
-domain can refer to it simply as @samp{churchy}.
+the machine with Internet address @samp{158.121.106.19} is also known as
+@samp{alpha.gnu.org}; and other machines in the @samp{gnu.org}
+domain can refer to it simply as @samp{alpha}.
@pindex /etc/hosts
@pindex netdb.h
in @file{netdb.h}. They are BSD features, defined unconditionally if
you include @file{netdb.h}.
-@comment netdb.h
-@comment BSD
@deftp {Data Type} {struct hostent}
+@standards{BSD, netdb.h}
This data type is used to represent an entry in the hosts database. It
has the following members:
This is the host address type; in practice, its value is always either
@code{AF_INET} or @code{AF_INET6}, with the latter being used for IPv6
hosts. In principle other kinds of addresses could be represented in
-the data base as well as Internet addresses; if this were done, you
+the database as well as Internet addresses; if this were done, you
might find a value in this field other than @code{AF_INET} or
@code{AF_INET6}. @xref{Socket Addresses}.
As far as the host database is concerned, each address is just a block
of memory @code{h_length} bytes long. But in other contexts there is an
-implicit assumption that you can convert this to a @code{struct in_addr} or
-an @code{unsigned long int}. Host addresses in a @code{struct hostent}
-structure are always given in network byte order; see @ref{Byte Order}.
+implicit assumption that you can convert IPv4 addresses to a
+@code{struct in_addr} or an @code{uint32_t}. Host addresses in
+a @code{struct hostent} structure are always given in network byte
+order; see @ref{Byte Order}.
You can use @code{gethostbyname}, @code{gethostbyname2} or
@code{gethostbyaddr} to search the hosts database for information about
need to save it across calls. You can also use @code{getaddrinfo} and
@code{getnameinfo} to obtain this information.
-@comment netdb.h
-@comment BSD
@deftypefun {struct hostent *} gethostbyname (const char *@var{name})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:hostbyname} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{} @acsfd{}}}
+@c gethostbyname @mtasurace:hostbyname @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c nss_hostname_digits_dots @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_maybe_init(!preinit) @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_iclose @acsuheap @acsmem @acsfd
+@c close_not_cancel_no_status dup @acsfd
+@c free dup @acsuheap @acsmem
+@c res_vinit @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_randomid ok
+@c getpid dup ok
+@c getenv dup @mtsenv
+@c strncpy dup ok
+@c fopen dup @ascuheap @asulock @acsmem @acsfd @aculock
+@c fsetlocking dup ok [no concurrent uses]
+@c fgets_unlocked dup ok [no concurrent uses]
+@c MATCH ok
+@c strncmp dup ok
+@c strpbrk dup ok
+@c strchr dup ok
+@c inet_aton dup @mtslocale
+@c htons dup
+@c inet_pton dup @mtslocale
+@c malloc dup @ascuheap @acsmem
+@c IN6_IS_ADDR_LINKLOCAL ok
+@c htonl dup ok
+@c IN6_IS_ADDR_MC_LINKLOCAL ok
+@c if_nametoindex dup @asulock @aculock @acsfd
+@c strtoul dup @mtslocale
+@c ISSORTMASK ok
+@c strchr dup ok
+@c isascii dup @mtslocale
+@c isspace dup @mtslocale
+@c net_mask ok
+@c ntohl dup ok
+@c IN_CLASSA dup ok
+@c htonl dup ok
+@c IN_CLASSB dup ok
+@c res_setoptions @mtslocale
+@c strncmp dup ok
+@c atoi dup @mtslocale
+@c fclose dup @ascuheap @asulock @aculock @acsmem @acsfd
+@c inet_makeaddr dup ok
+@c gethostname dup ok
+@c strcpy dup ok
+@c rawmemchr dup ok
+@c res_ninit @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_vinit dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c isdigit dup @mtslocale
+@c isxdigit dup @mtslocale
+@c strlen dup ok
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c memset dup ok
+@c inet_aton dup @mtslocale
+@c inet_pton dup @mtslocale
+@c strcpy dup ok
+@c memcpy dup ok
+@c strchr dup ok
+@c gethostbyname_r dup @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c set_h_errno ok
The @code{gethostbyname} function returns information about the host
named @var{name}. If the lookup fails, it returns a null pointer.
@end deftypefun
-@comment netdb.h
-@comment IPv6 Basic API
@deftypefun {struct hostent *} gethostbyname2 (const char *@var{name}, int @var{af})
+@standards{IPv6 Basic API, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:hostbyname2} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{} @acsfd{}}}
+@c gethostbyname2 @mtasurace:hostbyname2 @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c nss_hostname_digits_dots dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c gethostbyname2_r dup @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c set_h_errno dup ok
The @code{gethostbyname2} function is like @code{gethostbyname}, but
allows the caller to specify the desired address family (e.g.@:
-@code{AF_INET} or @code{AF_INET6}) for the result.
+@code{AF_INET} or @code{AF_INET6}) of the result.
@end deftypefun
-@comment netdb.h
-@comment BSD
-@deftypefun {struct hostent *} gethostbyaddr (const char *@var{addr}, int @var{length}, int @var{format})
+@deftypefun {struct hostent *} gethostbyaddr (const void *@var{addr}, socklen_t @var{length}, int @var{format})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:hostbyaddr} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{} @acsfd{}}}
+@c gethostbyaddr @mtasurace:hostbyaddr @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c gethostbyaddr_r dup @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c set_h_errno dup ok
The @code{gethostbyaddr} function returns information about the host
-with Internet address @var{addr}. The @var{length} argument is the
-size (in bytes) of the address at @var{addr}. @var{format} specifies
-the address format; for an Internet address, specify a value of
-@code{AF_INET}.
+with Internet address @var{addr}. The parameter @var{addr} is not
+really a pointer to char - it can be a pointer to an IPv4 or an IPv6
+address. The @var{length} argument is the size (in bytes) of the address
+at @var{addr}. @var{format} specifies the address format; for an IPv4
+Internet address, specify a value of @code{AF_INET}; for an IPv6
+Internet address, use @code{AF_INET6}.
If the lookup fails, @code{gethostbyaddr} returns a null pointer.
@end deftypefun
fails, you can find out the reason by looking at the value of the
variable @code{h_errno}. (It would be cleaner design for these
functions to set @code{errno}, but use of @code{h_errno} is compatible
-with other systems.) Before using @code{h_errno}, you must declare it
-like this:
-
-@smallexample
-extern int h_errno;
-@end smallexample
+with other systems.)
Here are the error codes that you may find in @code{h_errno}:
-@table @code
-@comment netdb.h
-@comment BSD
+@vtable @code
@item HOST_NOT_FOUND
-@vindex HOST_NOT_FOUND
-No such host is known in the data base.
+@standards{BSD, netdb.h}
+No such host is known in the database.
-@comment netdb.h
-@comment BSD
@item TRY_AGAIN
-@vindex TRY_AGAIN
+@standards{BSD, netdb.h}
This condition happens when the name server could not be contacted. If
you try again later, you may succeed then.
-@comment netdb.h
-@comment BSD
@item NO_RECOVERY
-@vindex NO_RECOVERY
+@standards{BSD, netdb.h}
A non-recoverable error occurred.
-@comment netdb.h
-@comment BSD
@item NO_ADDRESS
-@vindex NO_ADDRESS
+@standards{BSD, netdb.h}
The host database contains an entry for the name, but it doesn't have an
associated Internet address.
-@end table
+@end vtable
+
+The lookup functions above all have one thing in common: they are not
+reentrant and therefore unusable in multi-threaded applications.
+Therefore provides @theglibc{} a new set of functions which can be
+used in this context.
+
+@deftypefun int gethostbyname_r (const char *restrict @var{name}, struct hostent *restrict @var{result_buf}, char *restrict @var{buf}, size_t @var{buflen}, struct hostent **restrict @var{result}, int *restrict @var{h_errnop})
+@standards{GNU, netdb.h}
+@safety{@prelim{}@mtsafe{@mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{} @acsfd{}}}
+@c gethostbyname_r @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c nss_hostname_digits_dots dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c nscd_gethostbyname_r @mtsenv @ascuheap @acsfd @acsmem
+@c nscd_gethst_r @mtsenv @ascuheap @acsfd @acsmem
+@c getenv dup @mtsenv
+@c nscd_get_map_ref dup @ascuheap @acsfd @acsmem
+@c nscd_cache_search dup ok
+@c memcpy dup ok
+@c nscd_open_socket dup @acsfd
+@c readvall dup ok
+@c readall dup ok
+@c close_not_cancel_no_status dup @acsfd
+@c nscd_drop_map_ref dup @ascuheap @acsmem
+@c nscd_unmap dup @ascuheap @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_hconf_init @mtsenv @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem [no @asuinit:reshconf @acuinit:reshconf, conditionally called]
+@c res_hconf.c:do_init @mtsenv @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem
+@c memset dup ok
+@c getenv dup @mtsenv
+@c fopen dup @ascuheap @asulock @acsmem @acsfd @aculock
+@c fsetlocking dup ok [no concurrent uses]
+@c fgets_unlocked dup ok [no concurrent uses]
+@c strchrnul dup ok
+@c res_hconf.c:parse_line @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem
+@c skip_ws dup @mtslocale
+@c skip_string dup @mtslocale
+@c strncasecmp dup @mtslocale
+@c strlen dup ok
+@c asprintf dup @mtslocale @ascuheap @acsmem
+@c fxprintf dup @asucorrupt @aculock @acucorrupt
+@c free dup @ascuheap @acsmem
+@c arg_trimdomain_list dup @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem
+@c arg_spoof dup @mtslocale
+@c arg_bool dup @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem
+@c isspace dup @mtslocale
+@c fclose dup @ascuheap @asulock @acsmem @acsfd @aculock
+@c arg_spoof @mtslocale
+@c skip_string @mtslocale
+@c isspace dup @mtslocale
+@c strncasecmp dup @mtslocale
+@c arg_bool @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem
+@c strncasecmp dup @mtslocale
+@c asprintf dup @mtslocale @ascuheap @acsmem
+@c fxprintf dup @asucorrupt @aculock @acucorrupt
+@c free dup @ascuheap @acsmem
+@c arg_trimdomain_list @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem
+@c skip_string dup @mtslocale
+@c asprintf dup @mtslocale @ascuheap @acsmem
+@c fxprintf dup @asucorrupt @aculock @acucorrupt
+@c free dup @ascuheap @acsmem
+@c strndup dup @ascuheap @acsmem
+@c skip_ws @mtslocale
+@c isspace dup @mtslocale
+@c nss_hosts_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_database_lookup dup @mtslocale @ascuheap @asulock @acucorrupt @acsmem @acsfd @aculock
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_gethostbyname_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_hconf_reorder_addrs @asulock @ascuheap @aculock @acsmem @acsfd
+@c socket dup @acsfd
+@c libc_lock_lock dup @asulock @aculock
+@c ifreq @ascuheap @acsmem
+@c malloc dup @ascuheap @acsmem
+@c if_nextreq dup ok
+@c ioctl dup ok
+@c realloc dup @ascuheap @acsmem
+@c if_freereq dup @acsmem
+@c libc_lock_unlock dup @aculock
+@c close dup @acsfd
+The @code{gethostbyname_r} function returns information about the host
+named @var{name}. The caller must pass a pointer to an object of type
+@code{struct hostent} in the @var{result_buf} parameter. In addition
+the function may need extra buffer space and the caller must pass a
+pointer and the size of the buffer in the @var{buf} and @var{buflen}
+parameters.
+
+A pointer to the buffer, in which the result is stored, is available in
+@code{*@var{result}} after the function call successfully returned. The
+buffer passed as the @var{buf} parameter can be freed only once the caller
+has finished with the result hostent struct, or has copied it including all
+the other memory that it points to. If an error occurs or if no entry is
+found, the pointer @code{*@var{result}} is a null pointer. Success is
+signalled by a zero return value. If the function failed the return value
+is an error number. In addition to the errors defined for
+@code{gethostbyname} it can also be @code{ERANGE}. In this case the call
+should be repeated with a larger buffer. Additional error information is
+not stored in the global variable @code{h_errno} but instead in the object
+pointed to by @var{h_errnop}.
+
+Here's a small example:
+@smallexample
+struct hostent *
+gethostname (char *host)
+@{
+ struct hostent *hostbuf, *hp;
+ size_t hstbuflen;
+ char *tmphstbuf;
+ int res;
+ int herr;
+
+ hostbuf = malloc (sizeof (struct hostent));
+ hstbuflen = 1024;
+ tmphstbuf = malloc (hstbuflen);
+
+ while ((res = gethostbyname_r (host, hostbuf, tmphstbuf, hstbuflen,
+ &hp, &herr)) == ERANGE)
+ @{
+ /* Enlarge the buffer. */
+ hstbuflen *= 2;
+ tmphstbuf = realloc (tmphstbuf, hstbuflen);
+ @}
+
+ free (tmphstbuf);
+ /* Check for errors. */
+ if (res || hp == NULL)
+ return NULL;
+ return hp;
+@}
+@end smallexample
+@end deftypefun
+
+@deftypefun int gethostbyname2_r (const char *@var{name}, int @var{af}, struct hostent *restrict @var{result_buf}, char *restrict @var{buf}, size_t @var{buflen}, struct hostent **restrict @var{result}, int *restrict @var{h_errnop})
+@standards{GNU, netdb.h}
+@safety{@prelim{}@mtsafe{@mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{} @acsfd{}}}
+@c gethostbyname2_r @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c nss_hostname_digits_dots dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c nscd_gethostbyname2_r @mtsenv @ascuheap @asulock @aculock @acsfd @acsmem
+@c nscd_gethst_r dup @mtsenv @ascuheap @asulock @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_hconf_init dup @mtsenv @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem [no @asuinit:reshconf @acuinit:reshconf, conditionally called]
+@c nss_hosts_lookup2 dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_gethostbyname2_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_hconf_reorder_addrs dup @asulock @ascuheap @aculock @acsmem @acsfd
+The @code{gethostbyname2_r} function is like @code{gethostbyname_r}, but
+allows the caller to specify the desired address family (e.g.@:
+@code{AF_INET} or @code{AF_INET6}) for the result.
+@end deftypefun
+
+@deftypefun int gethostbyaddr_r (const void *@var{addr}, socklen_t @var{length}, int @var{format}, struct hostent *restrict @var{result_buf}, char *restrict @var{buf}, size_t @var{buflen}, struct hostent **restrict @var{result}, int *restrict @var{h_errnop})
+@standards{GNU, netdb.h}
+@safety{@prelim{}@mtsafe{@mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{} @acsfd{}}}
+@c gethostbyaddr_r @mtsenv @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @aculock @acucorrupt @acsmem @acsfd
+@c memcmp dup ok
+@c nscd_gethostbyaddr_r @mtsenv @ascuheap @asulock @aculock @acsfd @acsmem
+@c nscd_gethst_r dup @mtsenv @ascuheap @asulock @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c res_hconf_init dup @mtsenv @mtslocale @asucorrupt @ascuheap @aculock @acucorrupt @acsmem [no @asuinit:reshconf @acuinit:reshconf, conditionally called]
+@c nss_hosts_lookup2 dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_gethostbyaddr_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_hconf_reorder_addrs dup @asulock @ascuheap @aculock @acsmem @acsfd
+@c res_hconf_trim_domains @mtslocale
+@c res_hconf_trim_domain @mtslocale
+@c strlen dup ok
+@c strcasecmp dup @mtslocale
+The @code{gethostbyaddr_r} function returns information about the host
+with Internet address @var{addr}. The parameter @var{addr} is not
+really a pointer to char - it can be a pointer to an IPv4 or an IPv6
+address. The @var{length} argument is the size (in bytes) of the address
+at @var{addr}. @var{format} specifies the address format; for an IPv4
+Internet address, specify a value of @code{AF_INET}; for an IPv6
+Internet address, use @code{AF_INET6}.
+
+Similar to the @code{gethostbyname_r} function, the caller must provide
+buffers for the result and memory used internally. In case of success
+the function returns zero. Otherwise the value is an error number where
+@code{ERANGE} has the special meaning that the caller-provided buffer is
+too small.
+@end deftypefun
You can also scan the entire hosts database one entry at a time using
-@code{sethostent}, @code{gethostent}, and @code{endhostent}. Be careful
-in using these functions, because they are not reentrant.
+@code{sethostent}, @code{gethostent} and @code{endhostent}. Be careful
+when using these functions because they are not reentrant.
-@comment netdb.h
-@comment BSD
@deftypefun void sethostent (int @var{stayopen})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:hostent} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c sethostent @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_setent(nss_hosts_lookup2) @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c set_h_errno dup ok
+@c setup(nss_hosts_lookup2) @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *lookup_fct = nss_hosts_lookup2 dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:hostent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock dup @aculock
This function opens the hosts database to begin scanning it. You can
then call @code{gethostent} to read the entries.
reopening the database for each call.
@end deftypefun
-@comment netdb.h
-@comment BSD
-@deftypefun {struct hostent *} gethostent ()
+@deftypefun {struct hostent *} gethostent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:hostent} @mtasurace{:hostentbuf} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c gethostent @mtasurace:hostent @mtasurace:hostentbuf @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent(gethostent_r) @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c malloc dup @ascuheap @acsmem
+@c *func = gethostent_r dup @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c gethostent_r @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent_r(nss_hosts_lookup2) @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c setup(nss_hosts_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:hostent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *sfct.f @mtasurace:hostent @ascuplugin
+@c libc_lock_unlock dup @aculock
+
This function returns the next entry in the hosts database. It
returns a null pointer if there are no more entries.
@end deftypefun
-@comment netdb.h
-@comment BSD
-@deftypefun void endhostent ()
+@deftypefun void endhostent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:hostent} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c endhostent @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock @asulock @aculock
+@c nss_endent(nss_hosts_lookup2) @mtasurace:hostent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c setup(nss_passwd_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:hostent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock @aculock
This function closes the hosts database.
@end deftypefun
@pindex netinet/in.h
These macros are defined in the header file @file{netinet/in.h}.
-@comment netinet/in.h
-@comment BSD
@deftypevr Macro int IPPORT_RESERVED
+@standards{BSD, netinet/in.h}
Port numbers less than @code{IPPORT_RESERVED} are reserved for
superuser use.
@end deftypevr
-@comment netinet/in.h
-@comment BSD
@deftypevr Macro int IPPORT_USERRESERVED
+@standards{BSD, netinet/in.h}
Port numbers greater than or equal to @code{IPPORT_USERRESERVED} are
reserved for explicit use; they will never be allocated automatically.
@end deftypevr
the services database.
@pindex netdb.h
-@comment netdb.h
-@comment BSD
@deftp {Data Type} {struct servent}
+@standards{BSD, netdb.h}
This data type holds information about entries from the services database.
It has the following members:
is returned in a statically-allocated structure; you must copy the
information if you need to save it across calls.
-@comment netdb.h
-@comment BSD
@deftypefun {struct servent *} getservbyname (const char *@var{name}, const char *@var{proto})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:servbyname} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getservbyname =~ getpwuid @mtasurace:servbyname @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c getservbyname_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getservbyname_r =~ getpwuid_r @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nscd_getservbyname_r @ascuheap @acsfd @acsmem
+@c nscd_getserv_r @ascuheap @acsfd @acsmem
+@c nscd_get_map_ref dup @ascuheap @acsfd @acsmem
+@c strlen dup ok
+@c malloc dup @ascuheap @acsmem
+@c mempcpy dup ok
+@c memcpy dup ok
+@c nscd_cache_search dup ok
+@c nscd_open_socket dup @acsfd
+@c readvall dup ok
+@c readall dup ok
+@c close_not_cancel_no_status dup @acsfd
+@c nscd_drop_map_ref dup @ascuheap @acsmem
+@c nscd_unmap dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c nss_services_lookup2 =~ nss_passwd_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_getservbyname_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
The @code{getservbyname} function returns information about the
service named @var{name} using protocol @var{proto}. If it can't find
such a service, it returns a null pointer.
use it to determine which port they should listen on (@pxref{Listening}).
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun {struct servent *} getservbyport (int @var{port}, const char *@var{proto})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:servbyport} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getservbyport =~ getservbyname @mtasurace:servbyport @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c getservbyport_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getservbyport_r =~ getservbyname_r @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nscd_getservbyport_r @ascuheap @acsfd @acsmem
+@c nscd_getserv_r dup @ascuheap @acsfd @acsmem
+@c nss_services_lookup2 =~ nss_passwd_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_getservbyport_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
The @code{getservbyport} function returns information about the
service at port @var{port} using protocol @var{proto}. If it can't
find such a service, it returns a null pointer.
@noindent
You can also scan the services database using @code{setservent},
-@code{getservent}, and @code{endservent}. Be careful in using these
-functions, because they are not reentrant.
+@code{getservent} and @code{endservent}. Be careful when using these
+functions because they are not reentrant.
-@comment netdb.h
-@comment BSD
@deftypefun void setservent (int @var{stayopen})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:servent} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c setservent @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_setent(nss_services_lookup2) @mtasurace:servenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c setup(nss_services_lookup2) @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *lookup_fct = nss_services_lookup2 dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:servent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock dup @aculock
This function opens the services database to begin scanning it.
If the @var{stayopen} argument is nonzero, this sets a flag so that
reopening the database for each call.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun {struct servent *} getservent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:servent} @mtasurace{:serventbuf} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getservent @mtasurace:servent @mtasurace:serventbuf @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent(getservent_r) @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c malloc dup @ascuheap @acsmem
+@c *func = getservent_r dup @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getservent_r @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent_r(nss_services_lookup2) @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c setup(nss_services_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:servent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *sfct.f @mtasurace:servent @ascuplugin
+@c libc_lock_unlock dup @aculock
This function returns the next entry in the services database. If
there are no more entries, it returns a null pointer.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun void endservent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:servent} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c endservent @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock @asulock @aculock
+@c nss_endent(nss_services_lookup2) @mtasurace:servent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c setup(nss_services_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:servent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock @aculock
This function closes the services database.
@end deftypefun
So that machines with different byte order conventions can
communicate, the Internet protocols specify a canonical byte order
convention for data transmitted over the network. This is known
-as the @dfn{network byte order}.
+as @dfn{network byte order}.
When establishing an Internet socket connection, you must make sure that
the data in the @code{sin_port} and @code{sin_addr} members of the
-@code{sockaddr_in} structure are represented in the network byte order.
+@code{sockaddr_in} structure are represented in network byte order.
If you are encoding integer data in the messages sent through the
socket, you should convert this to network byte order too. If you don't
do this, your program may fail when running on or talking to other kinds
If you use @code{getservbyname} and @code{gethostbyname} or
@code{inet_addr} to get the port number and host address, the values are
-already in the network byte order, and you can copy them directly into
+already in network byte order, and you can copy them directly into
the @code{sockaddr_in} structure.
-Otherwise, you have to convert the values explicitly. Use
-@code{htons} and @code{ntohs} to convert values for the @code{sin_port}
-member. Use @code{htonl} and @code{ntohl} to convert values for the
+Otherwise, you have to convert the values explicitly. Use @code{htons}
+and @code{ntohs} to convert values for the @code{sin_port} member. Use
+@code{htonl} and @code{ntohl} to convert IPv4 addresses for the
@code{sin_addr} member. (Remember, @code{struct in_addr} is equivalent
-to @code{unsigned long int}.) These functions are declared in
+to @code{uint32_t}.) These functions are declared in
@file{netinet/in.h}.
@pindex netinet/in.h
-@comment netinet/in.h
-@comment BSD
-@deftypefun {unsigned short int} htons (unsigned short int @var{hostshort})
-This function converts the @code{short} integer @var{hostshort} from
+@deftypefun {uint16_t} htons (uint16_t @var{hostshort})
+@standards{BSD, netinet/in.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c htons ok
+@c bswap_16 ok
+@c bswap_constant_16 ok
+
+This function converts the @code{uint16_t} integer @var{hostshort} from
host byte order to network byte order.
@end deftypefun
-@comment netinet/in.h
-@comment BSD
-@deftypefun {unsigned short int} ntohs (unsigned short int @var{netshort})
-This function converts the @code{short} integer @var{netshort} from
+@deftypefun {uint16_t} ntohs (uint16_t @var{netshort})
+@standards{BSD, netinet/in.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c Alias to htons.
+This function converts the @code{uint16_t} integer @var{netshort} from
network byte order to host byte order.
@end deftypefun
-@comment netinet/in.h
-@comment BSD
-@deftypefun {unsigned long int} htonl (unsigned long int @var{hostlong})
-This function converts the @code{long} integer @var{hostlong} from
+@deftypefun {uint32_t} htonl (uint32_t @var{hostlong})
+@standards{BSD, netinet/in.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c htonl ok
+@c bswap_32 dup ok
+This function converts the @code{uint32_t} integer @var{hostlong} from
host byte order to network byte order.
+
+This is used for IPv4 Internet addresses.
@end deftypefun
-@comment netinet/in.h
-@comment BSD
-@deftypefun {unsigned long int} ntohl (unsigned long int @var{netlong})
-This function converts the @code{long} integer @var{netlong} from
+@deftypefun {uint32_t} ntohl (uint32_t @var{netlong})
+@standards{BSD, netinet/in.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c Alias to htonl.
+This function converts the @code{uint32_t} integer @var{netlong} from
network byte order to host byte order.
+
+This is used for IPv4 Internet addresses.
@end deftypefun
@node Protocols Database
@cindex protocols database
The communications protocol used with a socket controls low-level
-details of how data is exchanged. For example, the protocol implements
+details of how data are exchanged. For example, the protocol implements
things like checksums to detect errors in transmissions, and routing
instructions for messages. Normal user programs have little reason to
mess with these details directly.
protocols database. These are declared in @file{netdb.h}.
@pindex netdb.h
-@comment netdb.h
-@comment BSD
@deftp {Data Type} {struct protoent}
+@standards{BSD, netdb.h}
This data type is used to represent entries in the network protocols
database. It has the following members:
returned in a statically-allocated structure; you must copy the
information if you need to save it across calls.
-@comment netdb.h
-@comment BSD
@deftypefun {struct protoent *} getprotobyname (const char *@var{name})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:protobyname} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getprotobyname =~ getpwuid @mtasurace:protobyname @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c getprotobyname_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getprotobyname_r =~ getpwuid_r @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c no nscd support
+@c nss_protocols_lookup2 =~ nss_passwd_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_getprotobyname_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
The @code{getprotobyname} function returns information about the
network protocol named @var{name}. If there is no such protocol, it
returns a null pointer.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun {struct protoent *} getprotobynumber (int @var{protocol})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:protobynumber} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getprotobynumber =~ getpwuid @mtasurace:protobynumber @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c getprotobynumber_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getprotobynumber_r =~ getpwuid_r @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c no nscd support
+@c nss_protocols_lookup2 =~ nss_passwd_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_getprotobynumber_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
The @code{getprotobynumber} function returns information about the
network protocol with number @var{protocol}. If there is no such
protocol, it returns a null pointer.
@end deftypefun
You can also scan the whole protocols database one protocol at a time by
-using @code{setprotoent}, @code{getprotoent}, and @code{endprotoent}.
-Be careful in using these functions, because they are not reentrant.
+using @code{setprotoent}, @code{getprotoent} and @code{endprotoent}.
+Be careful when using these functions because they are not reentrant.
-@comment netdb.h
-@comment BSD
@deftypefun void setprotoent (int @var{stayopen})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:protoent} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c setprotoent @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_setent(nss_protocols_lookup2) @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c setup(nss_protocols_lookup2) @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *lookup_fct = nss_protocols_lookup2 dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:protoent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock dup @aculock
This function opens the protocols database to begin scanning it.
If the @var{stayopen} argument is nonzero, this sets a flag so that
reopening the database for each call.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun {struct protoent *} getprotoent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:protoent} @mtasurace{:protoentbuf} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getprotoent @mtasurace:protoent @mtasurace:protoentbuf @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent(getprotoent_r) @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c malloc dup @ascuheap @acsmem
+@c *func = getprotoent_r dup @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getprotoent_r @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent_r(nss_protocols_lookup2) @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c setup(nss_protocols_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:servent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *sfct.f @mtasurace:protoent @ascuplugin
+@c libc_lock_unlock dup @aculock
This function returns the next entry in the protocols database. It
returns a null pointer if there are no more entries.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun void endprotoent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:protoent} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c endprotoent @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock @asulock @aculock
+@c nss_endent(nss_protocols_lookup2) @mtasurace:protoent @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c setup(nss_protocols_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:protoent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock @aculock
This function closes the protocols database.
@end deftypefun
not actually implemented.
@code{PF_IMPLINK} is used for communicating between hosts and Internet
-Message Processors. For information on this, and on @code{PF_ROUTE}, an
+Message Processors. For information on this and @code{PF_ROUTE}, an
occasionally-used local area routing protocol, see the GNU Hurd Manual
(to appear in the future).
declared in @file{sys/socket.h}.
@pindex sys/socket.h
-@comment sys/socket.h
-@comment BSD
@deftypefun int socket (int @var{namespace}, int @var{style}, int @var{protocol})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
This function creates a socket and specifies communication style
@var{style}, which should be one of the socket styles listed in
@ref{Communication Styles}. The @var{namespace} argument specifies
-the namespace; it must be @code{PF_FILE} (@pxref{File Namespace}) or
+the namespace; it must be @code{PF_LOCAL} (@pxref{Local Namespace}) or
@code{PF_INET} (@pxref{Internet Namespace}). @var{protocol}
designates the specific protocol (@pxref{Socket Concepts}); zero is
usually right for @var{protocol}.
@item ENFILE
The system already has too many file descriptors open.
-@item EACCESS
-The process does not have privilege to create a socket of the specified
+@item EACCES
+The process does not have the privilege to create a socket of the specified
@var{style} or @var{protocol}.
@item ENOBUFS
@end table
The file descriptor returned by the @code{socket} function supports both
-read and write operations. But, like pipes, sockets do not support file
+read and write operations. However, like pipes, sockets do not support file
positioning operations.
@end deftypefun
For examples of how to call the @code{socket} function,
-see @ref{File Namespace}, or @ref{Inet Example}.
+see @ref{Local Socket Example}, or @ref{Inet Example}.
@node Closing a Socket
@cindex shutting down a socket
@cindex socket shutdown
-When you are finished using a socket, you can simply close its
+When you have finished using a socket, you can simply close its
file descriptor with @code{close}; see @ref{Opening and Closing Files}.
If there is still data waiting to be transmitted over the connection,
normally @code{close} tries to complete this transmission. You
specify a timeout period; see @ref{Socket Options}.
@pindex sys/socket.h
-You can also shut down only reception or only transmission on a
+You can also shut down only reception or transmission on a
connection by calling @code{shutdown}, which is declared in
@file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
@deftypefun int shutdown (int @var{socket}, int @var{how})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{shutdown} function shuts down the connection of socket
@var{socket}. The argument @var{how} specifies what action to
perform:
pipe has one input-only end and one output-only end (@pxref{Pipes and
FIFOs}).
-@comment sys/socket.h
-@comment BSD
@deftypefun int socketpair (int @var{namespace}, int @var{style}, int @var{protocol}, int @var{filedes}@t{[2]})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
This function creates a socket pair, returning the file descriptors in
@code{@var{filedes}[0]} and @code{@var{filedes}[1]}. The socket pair
is a full-duplex communications channel, so that both reading and writing
may be performed at either end.
-The @var{namespace}, @var{style}, and @var{protocol} arguments are
+The @var{namespace}, @var{style} and @var{protocol} arguments are
interpreted as for the @code{socket} function. @var{style} should be
one of the communication styles listed in @ref{Communication Styles}.
The @var{namespace} argument specifies the namespace, which must be
-@code{AF_FILE} (@pxref{File Namespace}); @var{protocol} specifies the
+@code{AF_LOCAL} (@pxref{Local Namespace}); @var{protocol} specifies the
communications protocol, but zero is the only meaningful value.
If @var{style} specifies a connectionless communication style, then
initiate a connection with a server.
@item
-@ref{Listening}, and @ref{Accepting Connections}, describe what the
+@ref{Listening} and @ref{Accepting Connections} describe what the
server program must do to wait for and act upon connection requests
from clients.
@item
-@ref{Transferring Data}, describes how data is transferred through the
+@ref{Transferring Data}, describes how data are transferred through the
connected socket.
@end itemize
@end iftex
In making a connection, the client makes a connection while the server
waits for and accepts the connection. Here we discuss what the client
-program must do, using the @code{connect} function, which is declared in
+program must do with the @code{connect} function, which is declared in
@file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
@deftypefun int connect (int @var{socket}, struct sockaddr *@var{addr}, socklen_t @var{length})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{connect} function initiates a connection from the socket
with file descriptor @var{socket} to the socket whose address is
specified by the @var{addr} and @var{length} arguments. (This socket
connection in progress (see @code{EINPROGRESS} above).
@end table
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, file descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
connection to it is requested. @xref{Inetd Servers}.
In the Internet namespace, there are no special protection mechanisms
-for controlling access to connect to a port; any process on any machine
+for controlling access to a port; any process on any machine
can make a connection to your server. If you want to restrict access to
your server, make it examine the addresses associated with connection
requests or implement some other handshaking or identification
protocol.
-In the File namespace, the ordinary file protection bits control who has
+In the local namespace, the ordinary file protection bits control who has
access to connect to the socket.
-@comment sys/socket.h
-@comment BSD
-@deftypefun int listen (int @var{socket}, unsigned int @var{n})
+@deftypefun int listen (int @var{socket}, int @var{n})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
The @code{listen} function enables the socket @var{socket} to accept
connections, thus making it a server socket.
A socket that has been established as a server can accept connection
requests from multiple clients. The server's original socket
-@emph{does not become part} of the connection; instead, @code{accept}
+@emph{does not become part of the connection}; instead, @code{accept}
makes a new socket which participates in the connection.
@code{accept} returns the descriptor for this socket. The server's
original socket remains available for listening for further connection
The number of pending connection requests on a server socket is finite.
If connection requests arrive from clients faster than the server can
act upon them, the queue can fill up and additional requests are refused
-with a @code{ECONNREFUSED} error. You can specify the maximum length of
+with an @code{ECONNREFUSED} error. You can specify the maximum length of
this queue as an argument to the @code{listen} function, although the
system may also impose its own internal limit on the length of this
queue.
-@comment sys/socket.h
-@comment BSD
-@deftypefun int accept (int @var{socket}, struct sockaddr *@var{addr}, socklen_t *@var{length-ptr})
+@deftypefun int accept (int @var{socket}, struct sockaddr *@var{addr}, socklen_t *@var{length_ptr})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
This function is used to accept a connection request on the server
socket @var{socket}.
connections immediately available.
@end table
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, file descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
@node Who is Connected
@subsection Who is Connected to Me?
-@comment sys/socket.h
-@comment BSD
-@deftypefun int getpeername (int @var{socket}, struct sockaddr *@var{addr}, size_t *@var{length-ptr})
+@deftypefun int getpeername (int @var{socket}, struct sockaddr *@var{addr}, socklen_t *@var{length-ptr})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{getpeername} function returns the address of the socket that
@var{socket} is connected to; it stores the address in the memory space
specified by @var{addr} and @var{length-ptr}. It stores the length of
@code{send} functions instead of the more generic @code{read} and
@code{write} functions. The @code{recv} and @code{send} functions take
an additional argument which you can use to specify various flags to
-control the special I/O modes. For example, you can specify the
+control special I/O modes. For example, you can specify the
@code{MSG_OOB} flag to read or write out-of-band data, the
@code{MSG_PEEK} flag to peek at input, or the @code{MSG_DONTROUTE} flag
to control inclusion of routing information on output.
you get a @code{SIGPIPE} signal for any use of @code{send} or
@code{write} (@pxref{Miscellaneous Signals}).
-@comment sys/socket.h
-@comment BSD
-@deftypefun int send (int @var{socket}, void *@var{buffer}, size_t @var{size}, int @var{flags})
+@deftypefun ssize_t send (int @var{socket}, const void *@var{buffer}, size_t @var{size}, int @var{flags})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{send} function is like @code{write}, but with the additional
flags @var{flags}. The possible values of @var{flags} are described
in @ref{Socket Data Options}.
@code{send} fails with @code{EPIPE}.
@end table
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, file descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
just as well use @code{read} instead of @code{recv}; see @ref{I/O
Primitives}.
-@comment sys/socket.h
-@comment BSD
-@deftypefun int recv (int @var{socket}, void *@var{buffer}, size_t @var{size}, int @var{flags})
+@deftypefun ssize_t recv (int @var{socket}, void *@var{buffer}, size_t @var{size}, int @var{flags})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{recv} function is like @code{read}, but with the additional
flags @var{flags}. The possible values of @var{flags} are described
-In @ref{Socket Data Options}.
+in @ref{Socket Data Options}.
-If nonblocking mode is set for @var{socket}, and no data is available to
+If nonblocking mode is set for @var{socket}, and no data are available to
be read, @code{recv} fails immediately rather than waiting. @xref{File
Status Flags}, for information about nonblocking mode.
You never connected this socket.
@end table
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, file descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
to obtain a value for this argument. All are defined in the header
file @file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int MSG_OOB
+@standards{BSD, sys/socket.h}
Send or receive out-of-band data. @xref{Out-of-Band Data}.
@end deftypevr
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int MSG_PEEK
+@standards{BSD, sys/socket.h}
Look at the data but don't remove it from the input queue. This is
only meaningful with input functions such as @code{recv}, not with
@code{send}.
@end deftypevr
-@comment sys/socket.h
-@comment BSD
@deftypevr Macro int MSG_DONTROUTE
+@standards{BSD, sys/socket.h}
Don't include routing information in the message. This is only
meaningful with output operations, and is usually only of interest for
diagnostic or routing programs. We don't try to explain it here.
particularly interesting once it has connected to the server; it just
sends a text string to the server and exits.
+This program uses @code{init_sockaddr} to set up the socket address; see
+@ref{Inet Example}.
+
@smallexample
@include inetcli.c.texi
@end smallexample
client when it detects an end-of-file condition (resulting from the
client shutting down its end of the connection).
-This program uses @code{make_socket} and @code{init_sockaddr} to set
-up the socket address; see @ref{Inet Example}.
+This program uses @code{make_socket} to set up the socket address; see
+@ref{Inet Example}.
@smallexample
@include inetsrv.c.texi
Streams with connections permit @dfn{out-of-band} data that is
delivered with higher priority than ordinary data. Typically the
reason for sending out-of-band data is to send notice of an
-exceptional condition. The way to send out-of-band data is using
+exceptional condition. To send out-of-band data use
@code{send}, specifying the flag @code{MSG_OOB} (@pxref{Sending
Data}).
-Out-of-band data is received with higher priority because the
+Out-of-band data are received with higher priority because the
receiving process need not read it in sequence; to read the next
available out-of-band data, use @code{recv} with the @code{MSG_OOB}
flag (@pxref{Receiving Data}). Ordinary read operations do not read
-out-of-band data; they read only the ordinary data.
+out-of-band data; they read only ordinary data.
@cindex urgent socket condition
-When a socket finds that out-of-band data is on its way, it sends a
+When a socket finds that out-of-band data are on their way, it sends a
@code{SIGURG} signal to the owner process or process group of the
socket. You can specify the owner using the @code{F_SETOWN} command
to the @code{fcntl} function; see @ref{Interrupt Input}. You must
for I/O}, for more information about @code{select}.
Notification of out-of-band data (whether with @code{SIGURG} or with
-@code{select}) indicates that out-of-band data is on the way; the data
+@code{select}) indicates that out-of-band data are on the way; the data
may not actually arrive until later. If you try to read the
out-of-band data before it arrives, @code{recv} fails with an
@code{EWOULDBLOCK} error.
the mark:
@smallexample
-success = ioctl (socket, SIOCATMARK, &result);
+success = ioctl (socket, SIOCATMARK, &atmark);
@end smallexample
+The @code{integer} variable @var{atmark} is set to a nonzero value if
+the socket's read pointer has reached the ``mark''.
+
+@c Posix 1.g specifies sockatmark for this ioctl. sockatmark is not
+@c implemented yet.
+
Here's a function to discard any ordinary data preceding the
out-of-band mark:
@{
/* @r{This is not an arbitrary limit; any size will do.} */
char buffer[1024];
- int result, success;
+ int atmark, success;
/* @r{If we have reached the mark, return.} */
- success = ioctl (socket, SIOCATMARK, &result);
+ success = ioctl (socket, SIOCATMARK, &atmark);
if (success < 0)
perror ("ioctl");
if (result)
@smallexample
struct buffer
@{
- char *buffer;
+ char *buf;
int size;
struct buffer *next;
@};
@r{It may be necessary to read some ordinary data}
@r{in order to make room for the out-of-band data.}
- @r{If so, the ordinary data is saved as a chain of buffers}
+ @r{If so, the ordinary data are saved as a chain of buffers}
@r{found in the `next' field of the value.} */
struct buffer *
@{
/* @r{This is an arbitrary limit.}
@r{Does anyone know how to do this without a limit?} */
- char *buffer = (char *) xmalloc (1024);
- struct buffer *link;
+#define BUF_SZ 1024
+ char *buf = (char *) xmalloc (BUF_SZ);
int success;
- int result;
+ int atmark;
/* @r{Try again to read the out-of-band data.} */
- success = recv (socket, buffer, sizeof buffer, MSG_OOB);
+ success = recv (socket, buf, BUF_SZ, MSG_OOB);
if (success >= 0)
@{
/* @r{We got it, so return it.} */
struct buffer *link
= (struct buffer *) xmalloc (sizeof (struct buffer));
- link->buffer = buffer;
+ link->buf = buf;
link->size = success;
link->next = list;
return link;
@}
/* @r{If we fail, see if we are at the mark.} */
- success = ioctl (socket, SIOCATMARK, &result);
+ success = ioctl (socket, SIOCATMARK, &atmark);
if (success < 0)
perror ("ioctl");
- if (result)
+ if (atmark)
@{
/* @r{At the mark; skipping past more ordinary data cannot help.}
@r{So just wait a while.} */
/* @r{Otherwise, read a bunch of ordinary data and save it.}
@r{This is guaranteed not to read past the mark}
@r{if it starts before the mark.} */
- success = read (socket, buffer, sizeof buffer);
+ success = read (socket, buf, BUF_SZ);
if (success < 0)
perror ("read");
@{
struct buffer *link
= (struct buffer *) xmalloc (sizeof (struct buffer));
- link->buffer = buffer;
+ link->buf = buf;
link->size = success;
/* @r{Add the new link to the end of the list.} */
independent communication. You specify the destination for each
packet individually.
-Datagram packets are like letters: you send each one independently,
+Datagram packets are like letters: you send each one independently
with its own destination address, and they may arrive in the wrong
order or not at all.
* Sending Datagrams:: Sending packets on a datagram socket.
* Receiving Datagrams:: Receiving packets on a datagram socket.
* Datagram Example:: An example program: packets sent over a
- datagram socket in the file namespace.
+ datagram socket in the local namespace.
* Example Receiver:: Another program, that receives those packets.
@end menu
You can call @code{connect} on a datagram socket, but this only
specifies a default destination for further data transmission on the
-socket. When a socket has a default destination, then you can use
+socket. When a socket has a default destination you can use
@code{send} (@pxref{Sending Data}) or even @code{write} (@pxref{I/O
Primitives}) to send a packet there. You can cancel the default
destination by calling @code{connect} using an address format of
@code{AF_UNSPEC} in the @var{addr} argument. @xref{Connecting}, for
more information about the @code{connect} function.
-@comment sys/socket.h
-@comment BSD
-@deftypefun int sendto (int @var{socket}, void *@var{buffer}. size_t @var{size}, int @var{flags}, struct sockaddr *@var{addr}, socklen_t @var{length})
+@deftypefun ssize_t sendto (int @var{socket}, const void *@var{buffer}, size_t @var{size}, int @var{flags}, struct sockaddr *@var{addr}, socklen_t @var{length})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{sendto} function transmits the data in the @var{buffer}
through the socket @var{socket} to the destination address specified
by the @var{addr} and @var{length} arguments. The @var{size} argument
The return value and error conditions are also the same as for
@code{send}, but you cannot rely on the system to detect errors and
report them; the most common error is that the packet is lost or there
-is no one at the specified address to receive it, and the operating
+is no-one at the specified address to receive it, and the operating
system on your machine usually does not know this.
It is also possible for one call to @code{sendto} to report an error
-due to a problem related to a previous call.
+owing to a problem related to a previous call.
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, file descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
also tells you where it was sent from. This function is declared in
@file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
-@deftypefun int recvfrom (int @var{socket}, void *@var{buffer}, size_t @var{size}, int @var{flags}, struct sockaddr *@var{addr}, socklen_t *@var{length-ptr})
+@deftypefun ssize_t recvfrom (int @var{socket}, void *@var{buffer}, size_t @var{size}, int @var{flags}, struct sockaddr *@var{addr}, socklen_t *@var{length-ptr})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{recvfrom} function reads one packet from the socket
@var{socket} into the buffer @var{buffer}. The @var{size} argument
specifies the maximum number of bytes to be read.
If the packet is longer than @var{size} bytes, then you get the first
-@var{size} bytes of the packet, and the rest of the packet is lost.
+@var{size} bytes of the packet and the rest of the packet is lost.
There's no way to read the rest of the packet. Thus, when you use a
packet protocol, you must always know how long a packet to expect.
The @var{addr} and @var{length-ptr} arguments are used to return the
address where the packet came from. @xref{Socket Addresses}. For a
-socket in the file domain, the address information won't be meaningful,
-since you can't read the address of such a socket (@pxref{File
+socket in the local domain the address information won't be meaningful,
+since you can't read the address of such a socket (@pxref{Local
Namespace}). You can specify a null pointer as the @var{addr} argument
if you are not interested in this information.
(@pxref{Socket Data Options}). The return value and error conditions
are also the same as for @code{recv}.
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, file descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
You can use plain @code{recv} (@pxref{Receiving Data}) instead of
-@code{recvfrom} if you know don't need to find out who sent the packet
+@code{recvfrom} if you don't need to find out who sent the packet
(either because you know where it should come from or because you
treat all possible senders alike). Even @code{read} can be used if
you don't want to specify @var{flags} (@pxref{I/O Primitives}).
@c supporting or that we support them.
@c !!! they can do more; it is hairy
-@comment sys/socket.h
-@comment BSD
@deftp {Data Type} {struct msghdr}
+@standards{BSD, sys/socket.h}
@end deftp
-@comment sys/socket.h
-@comment BSD
-@deftypefun int sendmsg (int @var{socket}, const struct msghdr *@var{message}, int @var{flags})
+@deftypefun ssize_t sendmsg (int @var{socket}, const struct msghdr *@var{message}, int @var{flags})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, files descriptors, semaphores or
+whatever) are freed even if the thread is cancel.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
-@comment sys/socket.h
-@comment BSD
-@deftypefun int recvmsg (int @var{socket}, struct msghdr *@var{message}, int @var{flags})
+@deftypefun ssize_t recvmsg (int @var{socket}, struct msghdr *@var{message}, int @var{flags})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
-This function is defined as a cancelation point in multi-threaded
-programs. So one has to be prepared for this and make sure that
-possibly allocated resources (like memory, files descriptors,
-semaphores or whatever) are freed even if the thread is cancel.
+This function is defined as a cancellation point in multi-threaded
+programs, so one has to be prepared for this and make sure that
+allocated resources (like memory, files descriptors, semaphores or
+whatever) are freed even if the thread is canceled.
@c @xref{pthread_cleanup_push}, for a method how to do this.
@end deftypefun
@end ignore
@subsection Datagram Socket Example
Here is a set of example programs that send messages over a datagram
-stream in the file namespace. Both the client and server programs use the
-@code{make_named_socket} function that was presented in @ref{File
-Namespace}, to create and name their sockets.
+stream in the local namespace. Both the client and server programs use
+the @code{make_named_socket} function that was presented in @ref{Local
+Socket Example}, to create and name their sockets.
First, here is the server program. It sits in a loop waiting for
messages to arrive, bouncing each message back to the sender.
-Obviously, this isn't a particularly useful program, but it does show
+Obviously this isn't a particularly useful program, but it does show
the general ideas involved.
@smallexample
Keep in mind that datagram socket communications are unreliable. In
this example, the client program waits indefinitely if the message
never reaches the server or if the server's response never comes
-back. It's up to the user running the program to kill it and restart
-it, if desired. A more automatic solution could be to use
+back. It's up to the user running the program to kill and restart
+it if desired. A more automatic solution could be to use
@code{select} (@pxref{Waiting for I/O}) to establish a timeout period
-for the reply, and in case of timeout either resend the message or
+for the reply, and in case of timeout either re-send the message or
shut down the socket and exit.
@node Inetd
listening. Such a server must already be running in order for anyone
to connect to it.
-Another way to provide service for an Internet port is to let the daemon
+Another way to provide a service on an Internet port is to let the daemon
program @code{inetd} do the listening. @code{inetd} is a program that
runs all the time and waits (using @code{select}) for messages on a
specified set of ports. When it receives a message, it accepts the
process starts. The connection already exists at this time; the
socket is available as the standard input descriptor and as the
standard output descriptor (descriptors 0 and 1) in the server
-process. So the server program can begin reading and writing data
+process. Thus the server program can begin reading and writing data
right away. Often the program needs only the ordinary I/O facilities;
in fact, a general-purpose filter program that knows nothing about
sockets can work as a byte stream server run by @code{inetd}.
You can also use @code{inetd} for servers that use connectionless
communication styles. For these servers, @code{inetd} does not try to accept
-a connection, since no connection is possible. It just starts the
+a connection since no connection is possible. It just starts the
server program, which can read the incoming datagram packet from
descriptor 0. The server program can handle one request and then
exit, or you can choose to write it to keep reading more requests
until no more arrive, and then exit. You must specify which of these
-two techniques the server uses, when you configure @code{inetd}.
+two techniques the server uses when you configure @code{inetd}.
@node Configuring Inetd
@subsection Configuring @code{inetd}
The @var{wait} field should be either @samp{wait} or @samp{nowait}.
Use @samp{wait} if @var{style} is a connectionless style and the
-server, once started, handles multiple requests, as many as come in.
+server, once started, handles multiple requests as they come in.
Use @samp{nowait} if @code{inetd} should start a new process for each message
or request that comes in. If @var{style} uses connections, then
@var{wait} @strong{must} be @samp{nowait}.
@var{user} is the user name that the server should run as. @code{inetd} runs
as root, so it can set the user ID of its children arbitrarily. It's
best to avoid using @samp{root} for @var{user} if you can; but some
-servers, such as Telnet and FTP, read a username and password
+servers, such as Telnet and FTP, read a username and passphrase
themselves. These servers need to be root initially so they can log
in as commanded by the data coming over the network.
If you edit @file{/etc/inetd.conf}, you can tell @code{inetd} to reread the
file and obey its new contents by sending the @code{inetd} process the
@code{SIGHUP} signal. You'll have to use @code{ps} to determine the
-process ID of the @code{inetd} process, as it is not fixed.
+process ID of the @code{inetd} process as it is not fixed.
@c !!! could document /etc/inetd.sec
Here are the functions for examining and modifying socket options.
They are declared in @file{sys/socket.h}.
-@comment sys/socket.h
-@comment BSD
@deftypefun int getsockopt (int @var{socket}, int @var{level}, int @var{optname}, void *@var{optval}, socklen_t *@var{optlen-ptr})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{getsockopt} function gets information about the value of
option @var{optname} at level @var{level} for socket @var{socket}.
-The option value is stored in a buffer that @var{optval} points to.
+The option value is stored in the buffer that @var{optval} points to.
Before the call, you should supply in @code{*@var{optlen-ptr}} the
size of this buffer; on return, it contains the number of bytes of
information actually stored in the buffer.
@end table
@end deftypefun
-@comment sys/socket.h
-@comment BSD
-@deftypefun int setsockopt (int @var{socket}, int @var{level}, int @var{optname}, void *@var{optval}, socklen_t @var{optlen})
+@deftypefun int setsockopt (int @var{socket}, int @var{level}, int @var{optname}, const void *@var{optval}, socklen_t @var{optlen})
+@standards{BSD, sys/socket.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
This function is used to set the socket option @var{optname} at level
@var{level} for socket @var{socket}. The value of the option is passed
-in the buffer @var{optval}, which has size @var{optlen}.
+in the buffer @var{optval} of size @var{optlen}.
@c Argh. -zw
@iftex
@node Socket-Level Options
@subsection Socket-Level Options
-@comment sys/socket.h
-@comment BSD
@deftypevr Constant int SOL_SOCKET
+@standards{BSD, sys/socket.h}
Use this constant as the @var{level} argument to @code{getsockopt} or
@code{setsockopt} to manipulate the socket-level options described in
this section.
@pindex sys/socket.h
@noindent
Here is a table of socket-level option names; all are defined in the
-header file@*@file{sys/socket.h}.
+header file @file{sys/socket.h}.
-@table @code
-@comment sys/socket.h
-@comment BSD
+@vtable @code
@item SO_DEBUG
+@standards{BSD, sys/socket.h}
@c Extra blank line here makes the table look better.
This option toggles recording of debugging information in the underlying
protocol modules. The value has type @code{int}; a nonzero value means
``yes''.
@c !!! should say how this is used
-@c Ok, anyone who knows, please explain.
+@c OK, anyone who knows, please explain.
-@comment sys/socket.h
-@comment BSD
@item SO_REUSEADDR
+@standards{BSD, sys/socket.h}
This option controls whether @code{bind} (@pxref{Setting Address})
should permit reuse of local addresses for this socket. If you enable
this option, you can actually have two sockets with the same Internet
port number; but the system won't allow you to use the two
identically-named sockets in a way that would confuse the Internet. The
reason for this option is that some higher-level Internet protocols,
-including FTP, require you to keep reusing the same socket number.
+including FTP, require you to keep reusing the same port number.
The value has type @code{int}; a nonzero value means ``yes''.
-@comment sys/socket.h
-@comment BSD
@item SO_KEEPALIVE
+@standards{BSD, sys/socket.h}
This option controls whether the underlying protocol should
periodically transmit messages on a connected socket. If the peer
fails to respond to these messages, the connection is considered
broken. The value has type @code{int}; a nonzero value means
``yes''.
-@comment sys/socket.h
-@comment BSD
@item SO_DONTROUTE
+@standards{BSD, sys/socket.h}
This option controls whether outgoing messages bypass the normal
message routing facilities. If set, messages are sent directly to the
network interface instead. The value has type @code{int}; a nonzero
value means ``yes''.
-@comment sys/socket.h
-@comment BSD
@item SO_LINGER
+@standards{BSD, sys/socket.h}
This option specifies what should happen when the socket of a type
that promises reliable delivery still has untransmitted messages when
it is closed; see @ref{Closing a Socket}. The value has type
@code{struct linger}.
-@comment sys/socket.h
-@comment BSD
@deftp {Data Type} {struct linger}
+@standards{BSD, sys/socket.h}
This structure type has the following members:
@table @code
@item int l_onoff
This field is interpreted as a boolean. If nonzero, @code{close}
-blocks until the data is transmitted or the timeout period has expired.
+blocks until the data are transmitted or the timeout period has expired.
@item int l_linger
This specifies the timeout period, in seconds.
@end table
@end deftp
-@comment sys/socket.h
-@comment BSD
@item SO_BROADCAST
+@standards{BSD, sys/socket.h}
This option controls whether datagrams may be broadcast from the socket.
The value has type @code{int}; a nonzero value means ``yes''.
-@comment sys/socket.h
-@comment BSD
@item SO_OOBINLINE
+@standards{BSD, sys/socket.h}
If this option is set, out-of-band data received on the socket is
placed in the normal input queue. This permits it to be read using
@code{read} or @code{recv} without specifying the @code{MSG_OOB}
flag. @xref{Out-of-Band Data}. The value has type @code{int}; a
nonzero value means ``yes''.
-@comment sys/socket.h
-@comment BSD
@item SO_SNDBUF
+@standards{BSD, sys/socket.h}
This option gets or sets the size of the output buffer. The value is a
@code{size_t}, which is the size in bytes.
-@comment sys/socket.h
-@comment BSD
@item SO_RCVBUF
+@standards{BSD, sys/socket.h}
This option gets or sets the size of the input buffer. The value is a
@code{size_t}, which is the size in bytes.
-@comment sys/socket.h
-@comment GNU
@item SO_STYLE
-@comment sys/socket.h
-@comment BSD
@itemx SO_TYPE
+@standards{GNU, sys/socket.h}
+@standardsx{SO_TYPE, BSD, sys/socket.h}
This option can be used with @code{getsockopt} only. It is used to
get the socket's communication style. @code{SO_TYPE} is the
historical name, and @code{SO_STYLE} is the preferred name in GNU.
The value has type @code{int} and its value designates a communication
style; see @ref{Communication Styles}.
-@comment sys/socket.h
-@comment BSD
@item SO_ERROR
+@standards{BSD, sys/socket.h}
@c Extra blank line here makes the table look better.
This option can be used with @code{getsockopt} only. It is used to reset
the error status of the socket. The value is an @code{int}, which represents
the previous error status.
@c !!! what is "socket error status"? this is never defined.
-@end table
+@end vtable
@node Networks Database
@section Networks Database
@file{/etc/networks} or in an equivalent from a name server. This data
base is useful for routing programs such as @code{route}, but it is not
useful for programs that simply communicate over the network. We
-provide functions to access this data base, which are declared in
+provide functions to access this database, which are declared in
@file{netdb.h}.
-@comment netdb.h
-@comment BSD
@deftp {Data Type} {struct netent}
+@standards{BSD, netdb.h}
This data type is used to represent information about entries in the
networks database. It has the following members:
information is returned in a statically-allocated structure; you must
copy the information if you need to save it.
-@comment netdb.h
-@comment BSD
@deftypefun {struct netent *} getnetbyname (const char *@var{name})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:netbyname} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getnetbyname =~ getpwuid @mtasurace:netbyname @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c getnetbyname_r dup @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getnetbyname_r =~ getpwuid_r @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c no nscd support
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c nss_networks_lookup2 =~ nss_passwd_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_getnetbyname_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
The @code{getnetbyname} function returns information about the network
named @var{name}. It returns a null pointer if there is no such
network.
@end deftypefun
-@comment netdb.h
-@comment BSD
-@deftypefun {struct netent *} getnetbyaddr (long @var{net}, int @var{type})
+@deftypefun {struct netent *} getnetbyaddr (uint32_t @var{net}, int @var{type})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:netbyaddr} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getnetbyaddr =~ getpwuid @mtasurace:netbyaddr @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c malloc dup @ascuheap @acsmem
+@c getnetbyaddr_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getnetbyaddr_r =~ getpwuid_r @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c no nscd support
+@c nss_networks_lookup2 =~ nss_passwd_lookup2 @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.l -> _nss_*_getnetbyaddr_r @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
The @code{getnetbyaddr} function returns information about the network
of type @var{type} with number @var{net}. You should specify a value of
@code{AF_INET} for the @var{type} argument for Internet networks.
@end deftypefun
You can also scan the networks database using @code{setnetent},
-@code{getnetent}, and @code{endnetent}. Be careful in using these
-functions, because they are not reentrant.
+@code{getnetent} and @code{endnetent}. Be careful when using these
+functions because they are not reentrant.
-@comment netdb.h
-@comment BSD
@deftypefun void setnetent (int @var{stayopen})
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:netent} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c setnetent @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_setent(nss_networks_lookup2) @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c setup(nss_networks_lookup2) @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *lookup_fct = nss_networks_lookup2 dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:netent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock dup @aculock
This function opens and rewinds the networks database.
If the @var{stayopen} argument is nonzero, this sets a flag so that
reopening the database for each call.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun {struct netent *} getnetent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:netent} @mtasurace{:netentbuf} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c getnetent @mtasurace:netent @mtasurace:netentbuf @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent(getnetent_r) @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c malloc dup @ascuheap @acsmem
+@c *func = getnetent_r dup @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c realloc dup @ascuheap @acsmem
+@c free dup @ascuheap @acsmem
+@c libc_lock_unlock dup @aculock
+@c
+@c getnetent_r @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock dup @asulock @aculock
+@c nss_getent_r(nss_networks_lookup2) @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c setup(nss_networks_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:servent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c nss_lookup dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *sfct.f @mtasurace:netent @ascuplugin
+@c libc_lock_unlock dup @aculock
This function returns the next entry in the networks database. It
returns a null pointer if there are no more entries.
@end deftypefun
-@comment netdb.h
-@comment BSD
@deftypefun void endnetent (void)
+@standards{BSD, netdb.h}
+@safety{@prelim{}@mtunsafe{@mtasurace{:netent} @mtsenv{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
+@c endnetent @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_lock @asulock @aculock
+@c nss_endent(nss_networks_lookup2) @mtasurace:netent @mtsenv @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c res_maybe_init(!preinit) dup @mtsenv @mtslocale @ascuheap @asulock @aculock @acsmem @acsfd
+@c setup(nss_networks_lookup2) dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c *fct.f @mtasurace:netent @ascuplugin
+@c nss_next2 dup @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem
+@c libc_lock_unlock @aculock
This function closes the networks database.
@end deftypefun
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