+++ /dev/null
-'\" t
-.\" Copyright (c) 2008 Petr Baudis <pasky@suse.cz>
-.\" and copyright (c) 2009, Linux Foundation, written by Michael Kerrisk
-.\" <mtk.manpages@gmail.com>
-.\"
-.\" SPDX-License-Identifier: Linux-man-pages-copyleft
-.\"
-.\" Redistribution and use in source and binary forms, with or without
-.\" modification, are permitted provided that the following conditions
-.\" are met:
-.\"
-.\" 2008-12-08 Petr Baudis <pasky@suse.cz>
-.\" Rewrite the BSD manpage in the Linux man pages style and account
-.\" for glibc specificities, provide an example.
-.\" 2009-01-14 mtk, many edits and changes, rewrote example program.
-.\"
-.TH getifaddrs 3 (date) "Linux man-pages (unreleased)"
-.SH NAME
-getifaddrs, freeifaddrs \- get interface addresses
-.SH LIBRARY
-Standard C library
-.RI ( libc ", " \-lc )
-.SH SYNOPSIS
-.nf
-.B #include <sys/types.h>
-.B #include <ifaddrs.h>
-.P
-.BI "int getifaddrs(struct ifaddrs **" "ifap" );
-.BI "void freeifaddrs(struct ifaddrs *" "ifa" );
-.fi
-.SH DESCRIPTION
-The
-.BR getifaddrs ()
-function creates a linked list of structures describing
-the network interfaces of the local system,
-and stores the address of the first item of the list in
-.IR *ifap .
-The list consists of
-.I ifaddrs
-structures, defined as follows:
-.P
-.in +4n
-.EX
-struct ifaddrs {
- struct ifaddrs *ifa_next; /* Next item in list */
- char *ifa_name; /* Name of interface */
- unsigned int ifa_flags; /* Flags from SIOCGIFFLAGS */
- struct sockaddr *ifa_addr; /* Address of interface */
- struct sockaddr *ifa_netmask; /* Netmask of interface */
- union {
- struct sockaddr *ifu_broadaddr;
- /* Broadcast address of interface */
- struct sockaddr *ifu_dstaddr;
- /* Point\-to\-point destination address */
- } ifa_ifu;
-#define ifa_broadaddr ifa_ifu.ifu_broadaddr
-#define ifa_dstaddr ifa_ifu.ifu_dstaddr
- void *ifa_data; /* Address\-specific data */
-};
-.EE
-.in
-.P
-The
-.I ifa_next
-field contains a pointer to the next structure on the list,
-or NULL if this is the last item of the list.
-.P
-The
-.I ifa_name
-points to the null-terminated interface name.
-.\" The constant
-.\" .B IF NAMESIZE
-.\" indicates the maximum length of this field.
-.P
-The
-.I ifa_flags
-field contains the interface flags, as returned by the
-.B SIOCGIFFLAGS
-.BR ioctl (2)
-operation (see
-.BR netdevice (7)
-for a list of these flags).
-.P
-The
-.I ifa_addr
-field points to a structure containing the interface address.
-(The
-.I sa_family
-subfield should be consulted to determine the format of the
-address structure.)
-This field may contain a null pointer.
-.P
-The
-.I ifa_netmask
-field points to a structure containing the netmask associated with
-.IR ifa_addr ,
-if applicable for the address family.
-This field may contain a null pointer.
-.P
-Depending on whether the bit
-.B IFF_BROADCAST
-or
-.B IFF_POINTOPOINT
-is set in
-.I ifa_flags
-(only one can be set at a time),
-either
-.I ifa_broadaddr
-will contain the broadcast address associated with
-.I ifa_addr
-(if applicable for the address family) or
-.I ifa_dstaddr
-will contain the destination address of the point-to-point interface.
-.P
-The
-.I ifa_data
-field points to a buffer containing address-family-specific data;
-this field may be NULL if there is no such data for this interface.
-.P
-The data returned by
-.BR getifaddrs ()
-is dynamically allocated and should be freed using
-.BR freeifaddrs ()
-when no longer needed.
-.SH RETURN VALUE
-On success,
-.BR getifaddrs ()
-returns zero;
-on error, \-1 is returned, and
-.I errno
-is set to indicate the error.
-.SH ERRORS
-.BR getifaddrs ()
-may fail and set
-.I errno
-for any of the errors specified for
-.BR socket (2),
-.BR bind (2),
-.BR getsockname (2),
-.BR recvmsg (2),
-.BR sendto (2),
-.BR malloc (3),
-or
-.BR realloc (3).
-.SH ATTRIBUTES
-For an explanation of the terms used in this section, see
-.BR attributes (7).
-.TS
-allbox;
-lbx lb lb
-l l l.
-Interface Attribute Value
-T{
-.na
-.nh
-.BR getifaddrs (),
-.BR freeifaddrs ()
-T} Thread safety MT-Safe
-.TE
-.SH STANDARDS
-None.
-.SH HISTORY
-This function first appeared in BSDi and is
-present on the BSD systems, but with slightly different
-semantics documented\[em]returning one entry per interface,
-not per address.
-This means
-.I ifa_addr
-and other fields can actually be NULL if the interface has no address,
-and no link-level address is returned if the interface has an IP address
-assigned.
-Also, the way of choosing either
-.I ifa_broadaddr
-or
-.I ifa_dstaddr
-differs on various systems.
-.\" , but the BSD-derived documentation generally
-.\" appears to be confused and obsolete on this point.
-.\" i.e., commonly it still says one of them will be NULL, even if
-.\" the ifa_ifu union is already present
-.P
-.BR getifaddrs ()
-first appeared in glibc 2.3, but before glibc 2.3.3,
-the implementation supported only IPv4 addresses;
-IPv6 support was added in glibc 2.3.3.
-Support of address families other than IPv4 is available only
-on kernels that support netlink.
-.SH NOTES
-The addresses returned on Linux will usually be the IPv4 and IPv6 addresses
-assigned to the interface, but also one
-.B AF_PACKET
-address per interface containing lower-level details about the interface
-and its physical layer.
-In this case, the
-.I ifa_data
-field may contain a pointer to a
-.IR "struct rtnl_link_stats" ,
-defined in
-.I <linux/if_link.h>
-(in Linux 2.4 and earlier,
-.IR "struct net_device_stats" ,
-defined in
-.IR <linux/netdevice.h> ),
-which contains various interface attributes and statistics.
-.SH EXAMPLES
-The program below demonstrates the use of
-.BR getifaddrs (),
-.BR freeifaddrs (),
-and
-.BR getnameinfo (3).
-Here is what we see when running this program on one system:
-.P
-.in +4n
-.EX
-$ \fB./a.out\fP
-lo AF_PACKET (17)
- tx_packets = 524; rx_packets = 524
- tx_bytes = 38788; rx_bytes = 38788
-wlp3s0 AF_PACKET (17)
- tx_packets = 108391; rx_packets = 130245
- tx_bytes = 30420659; rx_bytes = 94230014
-em1 AF_PACKET (17)
- tx_packets = 0; rx_packets = 0
- tx_bytes = 0; rx_bytes = 0
-lo AF_INET (2)
- address: <127.0.0.1>
-wlp3s0 AF_INET (2)
- address: <192.168.235.137>
-lo AF_INET6 (10)
- address: <::1>
-wlp3s0 AF_INET6 (10)
- address: <fe80::7ee9:d3ff:fef5:1a91%wlp3s0>
-.EE
-.in
-.SS Program source
-\&
-.EX
-#define _GNU_SOURCE /* To get defns of NI_MAXSERV and NI_MAXHOST */
-#include <arpa/inet.h>
-#include <sys/socket.h>
-#include <netdb.h>
-#include <ifaddrs.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <linux/if_link.h>
-\&
-int main(int argc, char *argv[])
-{
- struct ifaddrs *ifaddr;
- int family, s;
- char host[NI_MAXHOST];
-\&
- if (getifaddrs(&ifaddr) == \-1) {
- perror("getifaddrs");
- exit(EXIT_FAILURE);
- }
-\&
- /* Walk through linked list, maintaining head pointer so we
- can free list later. */
-\&
- for (struct ifaddrs *ifa = ifaddr; ifa != NULL;
- ifa = ifa\->ifa_next) {
- if (ifa\->ifa_addr == NULL)
- continue;
-\&
- family = ifa\->ifa_addr\->sa_family;
-\&
- /* Display interface name and family (including symbolic
- form of the latter for the common families). */
-\&
- printf("%\-8s %s (%d)\en",
- ifa\->ifa_name,
- (family == AF_PACKET) ? "AF_PACKET" :
- (family == AF_INET) ? "AF_INET" :
- (family == AF_INET6) ? "AF_INET6" : "???",
- family);
-\&
- /* For an AF_INET* interface address, display the address. */
-\&
- if (family == AF_INET || family == AF_INET6) {
- s = getnameinfo(ifa\->ifa_addr,
- (family == AF_INET) ? sizeof(struct sockaddr_in) :
- sizeof(struct sockaddr_in6),
- host, NI_MAXHOST,
- NULL, 0, NI_NUMERICHOST);
- if (s != 0) {
- printf("getnameinfo() failed: %s\en", gai_strerror(s));
- exit(EXIT_FAILURE);
- }
-\&
- printf("\et\etaddress: <%s>\en", host);
-\&
- } else if (family == AF_PACKET && ifa\->ifa_data != NULL) {
- struct rtnl_link_stats *stats = ifa\->ifa_data;
-\&
- printf("\et\ettx_packets = %10u; rx_packets = %10u\en"
- "\et\ettx_bytes = %10u; rx_bytes = %10u\en",
- stats\->tx_packets, stats\->rx_packets,
- stats\->tx_bytes, stats\->rx_bytes);
- }
- }
-\&
- freeifaddrs(ifaddr);
- exit(EXIT_SUCCESS);
-}
-.EE
-.SH SEE ALSO
-.BR bind (2),
-.BR getsockname (2),
-.BR socket (2),
-.BR packet (7),
-.BR ifconfig (8)
projects / thirdparty / man-pages.git / blobdiff