man7/ddp.7

   1 .\" This man page is Copyright (C) 1998 Alan Cox.
   2 .\" Permission is granted to distribute possibly modified copies
   3 .\" of this page provided the header is included verbatim,
   4 .\" and in case of nontrivial modification author and date
   5 .\" of the modification is added to the header.
   6 .\" $Id: ddp.7,v 1.3 1999/05/13 11:33:22 freitag Exp $
   7 .TH DDP  7 1999-05-01 "Linux Man Page" "Linux Programmer's Manual"
   8 .SH NAME
   9 ddp \- Linux AppleTalk protocol implementation
  10 .SH SYNOPSIS
  11 .B #include <sys/socket.h>
  12 .br
  13 .B #include <netatalk/at.h>
  14 .sp
  15 .IB ddp_socket " = socket(PF_APPLETALK, SOCK_DGRAM, 0);"
  16 .br
  17 .IB raw_socket " = socket(PF_APPLETALK, SOCK_RAW, " protocol ");"
  18 .SH DESCRIPTION
  19 Linux implements the Appletalk protocols described in
  20 .IR "Inside Appletalk" .
  21 Only the DDP layer and AARP are present in
  22 the kernel. They are designed to be used via the
  23 .B netatalk
  24 protocol
  25 libraries. This page documents the interface for those who wish or need to
  26 use the DDP layer directly.
  27 .PP
  28 The communication between Appletalk and the user program works using a
  29 BSD-compatible socket interface. For more information on sockets, see
  30 .BR socket (7).
  31 .PP
  32 An AppleTalk socket is created by calling the
  33 .BR socket (2)
  34 function with a
  35 .B PF_APPLETALK
  36 socket family argument. Valid socket types are
  37 .B SOCK_DGRAM
  38 to open a
  39 .B ddp
  40 socket or
  41 .B SOCK_RAW
  42 to open a
  43 .B raw
  44 socket.
  45 .I protocol
  46 is the Appletalk protocol to be received or sent. For
  47 .B SOCK_RAW
  48 you must specify
  49 .BR ATPROTO_DDP .
  50 .PP
  51 Raw sockets may be only opened by a process with effective user id 0 or when the process has the
  52 .B CAP_NET_RAW
  53 capability.
  54 .SH "ADDRESS FORMAT"
  55 An Appletalk socket address is defined as a combination of a network number,
  56 a node number, and a port number.
  57 .PP
  58 .RS
  59 .nf
  60 .ta 4n 20n 32n
  61 struct at_addr {
  62         u_short s_net;
  63         u_char  s_node;
  64 };
  65
  66 struct sockaddr_atalk {
  67         sa_family_t     sat_family;     /* address family */
  68         u_char  sat_port;       /* port */
  69         struct at_addr  sat_addr;       /* net/node */
  70 };
  71 .ta
  72 .fi
  73 .RE
  74 .PP
  75 .I sat_family
  76 is always set to
  77 .B AF_APPLETALK.
  78 .I sat_port
  79 contains the port. The port numbers below 129 are known as
  80 .B reserved ports.
  81 Only processes with the effective user id 0 or the
  82 .B CAP_NET_BIND_SERVICE
  83 capability may
  84 .BR bind (2)
  85 to these sockets.
  86 .I sat_addr
  87 is the host address.
  88 The
  89 .I net
  90 member of
  91 .B struct at_addr
  92 contains the host network in network byte order.  The value of
  93 .B AT_ANYNET
  94 is a
  95 wildcard and also implies \(lqthis network.\(rq
  96 The
  97 .I node
  98 member of
  99 .B struct at_addr
 100 contains the host node number.  The value of
 101 .B AT_ANYNODE
 102 is a
 103 wildcard and also implies \(lqthis node.\(rq The value of
 104 .B ATADDR_BCAST
 105 is a link
 106 local broadcast address.
 107 .\" XXX this doesn't make sense [johnl]
 108 .SH "SOCKET OPTIONS"
 109 No protocol-specific socket options are supported.
 110 .SH SYSCTLS
 111 IP supports a sysctl interface to configure some global AppleTalk parameters.
 112 The sysctls can be accessed by reading or writing the
 113 .B /proc/sys/net/atalk/*
 114 files or with the
 115 .BR sysctl (2)
 116 interface.
 117 .TP
 118 .B aarp-expiry-time
 119 The time interval (in seconds) before an AARP cache entry expires.
 120 .TP
 121 .B aarp-resolve-time
 122 The time interval (in seconds) before an AARP cache entry is resolved.
 123 .TP
 124 .B aarp-retransmit-limit
 125 The number of retransmissions of an AARP query before the node is declared
 126 dead.
 127 .TP
 128 .B aarp-tick-time
 129 The timer rate (in seconds) for the timer driving AARP.
 130 .PP
 131 The default values match the specification and should never need to be
 132 changed.
 133
 134 .SH IOCTLS
 135 All ioctls described in
 136 .BR socket (7)
 137 apply to ddp.
 138
 139 .\" XXX Add a chapter about multicasting
 140
 141 .SH NOTES
 142 Be very careful with the
 143 .B SO_BROADCAST
 144 option \- it is not privileged in Linux. It is easy to overload the network
 145 with careless sending to broadcast addresses.
 146 .SH VERSIONS
 147 Appletalk is supported by Linux 2.0 or higher. The
 148 .B sysctl
 149 interface is
 150 new in Linux 2.2.
 151 .SH ERRORS
 152 .\" XXX document all errors. We should really fix the kernels to give more uniform
 153 .\"     error returns (ENOMEM vs ENOBUFS, EPERM vs EACCES etc.)
 154 .TP
 155 .B ENOTCONN
 156 The operation is only defined on a connected socket, but the socket wasn't
 157 connected.
 158 .TP
 159 .B EINVAL
 160 Invalid argument passed.
 161 .TP
 162 .B EMSGSIZE
 163 Datagram is bigger than the DDP MTU.
 164 .TP
 165 .B EACCES
 166 The user tried to execute an operation without the necessary permissions. These
 167 include sending to a broadcast address without having the broadcast flag set,
 168 and trying to bind to a reserved port without effective user id 0 or
 169 .BR CAP_NET_BIND_SERVICE .
 170 .TP
 171 .B EADDRINUSE
 172 Tried to bind to an address already in use.
 173 .TP
 174 .BR ENOMEM " and " ENOBUFS
 175 Not enough memory available.
 176 .TP
 177 .BR ENOPROTOOPT " and " EOPNOTSUPP
 178 Invalid socket option passed.
 179 .TP
 180 .B EPERM
 181 User doesn't have permission to set high priority, make a configuration change,
 182 or send signals to the requested process or group,
 183 .TP
 184 .B EADDRNOTAVAIL
 185 A non-existent interface was requested or the requested source address was
 186 not local.
 187 .TP
 188 .B EAGAIN
 189 Operation on a nonblocking socket would block.
 190 .TP
 191 .B ESOCKTNOSUPPORT
 192 The socket was unconfigured, or an unknown socket type was requested.
 193 .TP
 194 .B EISCONN
 195 .BR connect (2)
 196 was called on an already connected socket.
 197 .TP
 198 .B EALREADY
 199 A connection operation on a non-blocking socket is already in progress.
 200 .TP
 201 .B ECONNABORTED
 202 A connection was closed during an
 203 .BR accept (2).
 204 .TP
 205 .B EPIPE
 206 The connection was unexpectedly closed or shut down by the other end.
 207 .TP
 208 .B ENOENT
 209 .B SIOCGSTAMP
 210 was called on a socket where no packet arrived.
 211 .TP
 212 .B EHOSTUNREACH
 213 No routing table entry matches the destination address.
 214 .TP
 215 .B ENODEV
 216 Network device not available or not capable of sending IP.
 217 .TP
 218 .B ENOPKG
 219 A kernel subsystem was not configured.
 220 .SH COMPATIBILITY
 221 The basic AppleTalk socket interface is compatible with
 222 .B netatalk
 223 on BSD-derived systems. Many BSD systems fail to check
 224 .B SO_BROADCAST
 225 when sending broadcast frames; this can lead to compatibility problems.
 226 .PP
 227 The
 228 raw
 229 socket mode is unique to Linux and exists to support the alternative CAP
 230 package and AppleTalk monitoring tools more easily.
 231 .SH BUGS
 232 There are too many inconsistent error values.
 233 .PP
 234 The ioctls used to configure routing tables, devices, AARP tables and other
 235 devices are not yet described.
 236 .SH "SEE ALSO"
 237 .BR recvmsg (2),
 238 .BR sendmsg (2),
 239 .BR capabilities (7),
 240 .BR socket (7)