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diff --git a/man7/ddp.7 b/man7/ddp.7 new file mode 100644 index 0000000..0b7eb15 --- /dev/null +++ b/man7/ddp.7 @@ -0,0 +1,245 @@ +.\" This man page is Copyright (C) 1998 Alan Cox. +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" $Id: ddp.7,v 1.3 1999/05/13 11:33:22 freitag Exp $ +.\" +.TH ddp 7 2023-05-26 "Linux man-pages 6.05.01" +.SH NAME +ddp \- Linux AppleTalk protocol implementation +.SH SYNOPSIS +.nf +.B #include <sys/socket.h> +.B #include <netatalk/at.h> +.PP +.IB ddp_socket " = socket(AF_APPLETALK, SOCK_DGRAM, 0);" +.IB raw_socket " = socket(AF_APPLETALK, SOCK_RAW, " protocol ");" +.fi +.SH DESCRIPTION +Linux implements the AppleTalk protocols described in +.IR "Inside AppleTalk" . +Only the DDP layer and AARP are present in +the kernel. +They are designed to be used via the +.B netatalk +protocol +libraries. +This page documents the interface for those who wish or need to +use the DDP layer directly. +.PP +The communication between AppleTalk and the user program works using a +BSD-compatible socket interface. +For more information on sockets, see +.BR socket (7). +.PP +An AppleTalk socket is created by calling the +.BR socket (2) +function with a +.B AF_APPLETALK +socket family argument. +Valid socket types are +.B SOCK_DGRAM +to open a +.B ddp +socket or +.B SOCK_RAW +to open a +.B raw +socket. +.I protocol +is the AppleTalk protocol to be received or sent. +For +.B SOCK_RAW +you must specify +.BR ATPROTO_DDP . +.PP +Raw sockets may be opened only by a process with effective user ID 0 +or when the process has the +.B CAP_NET_RAW +capability. +.SS Address format +An AppleTalk socket address is defined as a combination of a network number, +a node number, and a port number. +.PP +.in +4n +.EX +struct at_addr { + unsigned short s_net; + unsigned char s_node; +}; +\& +struct sockaddr_atalk { + sa_family_t sat_family; /* address family */ + unsigned char sat_port; /* port */ + struct at_addr sat_addr; /* net/node */ +}; +.EE +.in +.PP +.I sat_family +is always set to +.BR AF_APPLETALK . +.I sat_port +contains the port. +The port numbers below 129 are known as +.IR "reserved ports" . +Only processes with the effective user ID 0 or the +.B CAP_NET_BIND_SERVICE +capability may +.BR bind (2) +to these sockets. +.I sat_addr +is the host address. +The +.I net +member of +.I struct at_addr +contains the host network in network byte order. +The value of +.B AT_ANYNET +is a +wildcard and also implies \[lq]this network.\[rq] +The +.I node +member of +.I struct at_addr +contains the host node number. +The value of +.B AT_ANYNODE +is a +wildcard and also implies \[lq]this node.\[rq] The value of +.B ATADDR_BCAST +is a link +local broadcast address. +.\" FIXME . this doesn't make sense [johnl] +.SS Socket options +No protocol-specific socket options are supported. +.SS /proc interfaces +IP supports a set of +.I /proc +interfaces to configure some global AppleTalk parameters. +The parameters can be accessed by reading or writing files in the directory +.IR /proc/sys/net/atalk/ . +.TP +.I aarp\-expiry\-time +The time interval (in seconds) before an AARP cache entry expires. +.TP +.I aarp\-resolve\-time +The time interval (in seconds) before an AARP cache entry is resolved. +.TP +.I aarp\-retransmit\-limit +The number of retransmissions of an AARP query before the node is declared +dead. +.TP +.I aarp\-tick\-time +The timer rate (in seconds) for the timer driving AARP. +.PP +The default values match the specification and should never need to be +changed. +.SS Ioctls +All ioctls described in +.BR socket (7) +apply to DDP. +.\" FIXME . Add a section about multicasting +.SH ERRORS +.TP +.B EACCES +The user tried to execute an operation without the necessary permissions. +These include sending to a broadcast address without +having the broadcast flag set, +and trying to bind to a reserved port without effective user ID 0 or +.BR CAP_NET_BIND_SERVICE . +.TP +.B EADDRINUSE +Tried to bind to an address already in use. +.TP +.B EADDRNOTAVAIL +A nonexistent interface was requested or the requested source address was +not local. +.TP +.B EAGAIN +Operation on a nonblocking socket would block. +.TP +.B EALREADY +A connection operation on a nonblocking socket is already in progress. +.TP +.B ECONNABORTED +A connection was closed during an +.BR accept (2). +.TP +.B EHOSTUNREACH +No routing table entry matches the destination address. +.TP +.B EINVAL +Invalid argument passed. +.TP +.B EISCONN +.BR connect (2) +was called on an already connected socket. +.TP +.B EMSGSIZE +Datagram is bigger than the DDP MTU. +.TP +.B ENODEV +Network device not available or not capable of sending IP. +.TP +.B ENOENT +.B SIOCGSTAMP +was called on a socket where no packet arrived. +.TP +.BR ENOMEM " and " ENOBUFS +Not enough memory available. +.TP +.B ENOPKG +A kernel subsystem was not configured. +.TP +.BR ENOPROTOOPT " and " EOPNOTSUPP +Invalid socket option passed. +.TP +.B ENOTCONN +The operation is defined only on a connected socket, but the socket wasn't +connected. +.TP +.B EPERM +User doesn't have permission to set high priority, +make a configuration change, +or send signals to the requested process or group. +.TP +.B EPIPE +The connection was unexpectedly closed or shut down by the other end. +.TP +.B ESOCKTNOSUPPORT +The socket was unconfigured, or an unknown socket type was requested. +.SH VERSIONS +AppleTalk is supported by Linux 2.0 or higher. +The +.I /proc +interfaces exist since Linux 2.2. +.SH NOTES +Be very careful with the +.B SO_BROADCAST +option; it is not privileged in Linux. +It is easy to overload the network +with careless sending to broadcast addresses. +.SS Compatibility +The basic AppleTalk socket interface is compatible with +.B netatalk +on BSD-derived systems. +Many BSD systems fail to check +.B SO_BROADCAST +when sending broadcast frames; this can lead to compatibility problems. +.PP +The +raw +socket mode is unique to Linux and exists to support the alternative CAP +package and AppleTalk monitoring tools more easily. +.SH BUGS +There are too many inconsistent error values. +.PP +The ioctls used to configure routing tables, devices, +AARP tables, and other devices are not yet described. +.SH SEE ALSO +.BR recvmsg (2), +.BR sendmsg (2), +.BR capabilities (7), +.BR socket (7) |