NAME

appletalk − AppleTalk protocol family

SYNOPSIS

#include <netat/atalk.h>

DESCRIPTION

The AppleTalk protocol family provides basic communications for AppleTalk datagram delivery packetized in Ethernet packets. It provides protocol support only for the SOCK_DGRAM socket type.  Other protocols in the suite can be layered atop this facility using the standard socket interfaces. 

ADDRESSING

AppleTalk addresses are four-byte quantities, stored in network-standard format (on the Balance and Symmetry series the addresses are word- and byte-reversed).  The include file <netat/atalk.h> defines this address as a discriminated union.

Sockets bound to the AppleTalk protocol family utilize the following addressing structure:

structsockaddr_at {
shortat_family;/∗ AF_APPLETALK ∗/
struct a_addrat_addr;/∗ 4 bytes ∗/
u_charat_sno;/∗ ddp socket number ∗/
u_charat_ptype;/∗ ddp protocol type ∗/
charat_dummy[8];/∗ fill ∗/
};

where:

structa_addr{
union{
struct{
u_shortNet;
u_charNode;
u_charAbridge;
} at_chrs;
longAddr;
} at_un;
};

#defineat_Netat_un.at_chrs.Net
#defineat_Nodeat_un.at_chrs.Node
#defineat_Abridgeat_un.at_chrs.Abridge
#defineat_adrat_un.Addr

Sockets may be created with the address at_Net and at_Node equal to zero (0) to effect “wildcard” matching on incoming messages.  A connect() that specifies at_Net and at_Node equal to zero (0) returns the current values for the host. 

PROTOCOLS

The AppleTalk protocol family consists of the Datagram Delivery Protocol (DDP) only.  It is used to support the SOCK_DGRAM abstraction. 

SEE ALSO

ddp(4P)

DYNIX