.TH ATALK 4F "17 Dec 1991" "netatalk 1.2"
.SH NAME
atalk \- AppleTalk protocol family
.SH SYNOPSIS
.B #include <sys/types.h>
.br
.B #include <netatalk/at.h>
.SH DESCRIPTION
The AppleTalk protocol family is a collection of protocols layered
above the Datagram Delivery Protocol (DDP), and using AppleTalk address
format. The AppleTalk family may provide SOCK_STREAM (ADSP), SOCK_DGRAM
(DDP), SOCK_RDM (ATP), and SOCK_SEQPACKET (ASP). Currently, only DDP is
implemented in the kernel; ATP and ASP are implemented in user level
libraries; and ADSP is planned.
.SH ADDRESSING
AppleTalk addresses are three byte quantities, stored in network
byte order. The include file
.RB < netatalk/at.h >
defines the AppleTalk address format.
.LP
Sockets in the AppleTalk protocol family use the following address
structure:
.sp 1
.RS
.nf
struct sockaddr_at {
	short		sat_family;
	u_char		sat_port;
	struct at_addr	sat_addr;
	char		sat_zero[ 8 ];
};
.fi
.RE
.sp 1
The port of a socket may be set with
.BR bind (2).
The node for
.B bind
must always be
.BR ATADDR_ANYNODE :
``this node.'' The net may be
.B ATADDR_ANYNET
or
.BR ATADDR_LATENET .
.B ATADDR_ANYNET
coresponds to the machine's ``primary'' address (the first
configured).
.B ATADDR_LATENET
causes the address in outgoing packets to be determined when a packet
is sent, i.e. determined late.
.B ATADDR_LATENET
is equivalent to opening one socket for each network interface.  The
port of a socket and either the primary address or
.B ATADDR_LATENET
are returned with
.BR getsockname (2).
.SH SEE ALSO
.\" .BR ddp (4P),
.\" .BR atp (3N),
.\" .BR asp (3N),
.BR bind (2),
.BR getsockname (2),
.BR atalkd (8).