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NAME

ddp - Linux AppleTalk protocol implementation
 

SYNOPSIS

ddp_socket = socket(PF_APPLETALK, SOCK_DGRAM, 0);
raw_socket = socket(PF_APPLETALK, SOCK_RAW, protocol);  

DESCRIPTION

The communication between Appletalk and the user program works using a BSD-compatible socket interface. For more information on sockets, see socket(4).

An AppleTalk socket is created by calling the socket(2) function with a PF_APPLETALK socket family argument. Valid socket types are SOCK_DGRAM to open a ddp socket or SOCK_RAW to open a raw socket. protocol is the Appletalk protocol to be received or sent. For SOCK_RAW you must specify ATPROTO_DDP.

Raw sockets may be only opened by a process with effective user id 0 or when the process has the CAP_NET_RAW capability.  

ADDRESS FORMAT

struct at_addr {
    u_short         s_net;
    u_char          s_node;
};

struct sockaddr_atalk {
    sa_family_t     sat_family; /* address family */
    u_char          sat_port;   /* port */
    struct at_addr  sat_addr;   /* net/node */
};

sat_family is always set to AF_APPLETALK. sat_port contains the port. The port numbers below 129 are known as reserved ports. Only processes with the effective user id 0 or the CAP_NET_BIND_SERVICE attribute set may bind(2) to these sockets. sat_addr is the host address. The net member of struct at_addr contains the host network in network byte order. The value of AT_ANYNET is a wildcard and also implies lqthis network.rq The node member of struct at_addr contains the host node number. The value of AT_ANYNODE is a wildcard and also implies lqthis node.rq The value of ATADDR_BCAST is a link local broadcast address.  

SOCKET OPTIONS

SYSCTLS

aarp-expiry-time

The time interval (in seconds) before an AARP cache entry expires.

aarp-resolve-time

The time interval (in seconds) before an AARP cache entry is resolved.

aarp-retransmit-limit

The number of retransmissions of an AARP query before the node is declared dead.

aarp-tick-time

The timer rate (in seconds) for the timer driving AARP.

The default values match the specification and should never need to be changed.  

IOCTLS

error = ioctl(atalk_socket, ioctl_type, value_ptr);

SIOCGSTAMP

Return a struct timeval with the receive timestamp of the last packet passed to the user. This is useful for accurate round trip time measurements. See setitimer(2) for a description of struct timeval.

FIOCSETOWN and SIOCSPGRP

Set the process or process group (negative value passed with a process group id of the absolute value) to send SIGIO signal to when an asynchronous IO operation has finished. Argument is a pid_t. Only processes of effective user id 0 may set this value to arbitrary pids; all others are only for processes with a matching group id or effective user id.

FIOASYNC

Set a flag to enable or disable asynchronous mode of the socket. Asynchronous mode means that SIGIO is raised when a new I/O event occurs.

Valid I/O events are: new data arrives; the socket send buffer has enough room to queue new data; a new connection arrives (for connection-oriented protocols); or the connection is broken. SIGIO is not sent when the connection is broken from the local end using shutdown(2) or close(2). In some situations (multiple processes or the kernel sending data to a single socket) the condition that caused the SIGIO might already have disappeared when the SIGIO is processed by the user process. When this happens the user process should just wait again because Linux guarantees to resend a new SIGIO later.

FIOCGETOWN and SIOCGPGRP

Get the current process or process group that receive SIGIO or SIGURG signals, or 0 when none is set. Argument is a pid_t.

NOTES

VERSIONS

ERRORS

ENOTCONN

The operation is only defined on a connected socket, but the socket wasn't connected.

EINVAL

Invalid argument passed.

EMSGSIZE

Datagram is bigger than the DDP MTU.

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 CAP_NET_BIND_SERVICE.

EADDRINUSE

Tried to bind to an address already in use.

ENOMEM and ENOBUFS

Not enough memory available.

ENOPROTOOPT and EOPNOTSUPP

Invalid socket option passed.

EPERM

User doesn't have permission to set high priority, make a configuration change, or send signals to the requested process or group,

EADDRNOTAVAIL

A non-existent interface was requested or the requested source address was not local.

EAGAIN

Operation on a nonblocking socket would block.

ESOCKTNOSUPPORT

The socket was unconfigured, or an unknown socket type was requested.

EISCONN

connect(2) was called on an already connected socket.

EALREADY

A connection operation on a non-blocking socket is already in progress.

ECONNABORTED

A connection was closed during an accept(2).

EPIPE

The connection was unexpectedly closed or shut down by the other end.

ENOENT

SIOCGSTAMP was called on a socket where no packet arrived.

EHOSTUNREACH

No routing table entry matches the destination address.

ENODEV

Network device not available or not capable of sending IP.

ENOPKG

A kernel subsystem was not configured.

COMPATIBILITY

The raw socket mode is unique to Linux and exists to support the alternative CAP package and AppleTalk monitoring tools more easily.  

BUGS

The ioctls used to configure routing tables, devices, AARP tables and other devices are not yet described.  

SEE ALSO

Index

NAME

SYNOPSIS

DESCRIPTION

ADDRESS FORMAT

SOCKET OPTIONS

SYSCTLS

IOCTLS

NOTES

VERSIONS

ERRORS

COMPATIBILITY

BUGS

SEE ALSO

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