SOCKET(3XNET) X/Open Networking Services Library Functions SOCKET(3XNET)

NAME

socket - create an endpoint for communication

SYNOPSIS

cc [ flag ... ] file ... -lxnet [ library ... ]
#include <sys/socket.h>

int socket(int domain, int type, int protocol);

DESCRIPTION

The socket() function creates an unbound socket in a communications
domain, and returns a file descriptor that can be used in later function
calls that operate on sockets.


The <sys/socket.h> header defines at least the following values for the
domain argument:

AF_UNIX
File system pathnames.


AF_INET
Internet Protocol version 4 (IPv4) address.


AF_INET6
Internet Protocol version 6 (IPv6) address.


The type argument specifies the socket type, which determines the
semantics of communication over the socket. The socket types supported
by the system are implementation-dependent. Possible socket types
include:

SOCK_STREAM
Provides sequenced, reliable, bidirectional,
connection-mode byte streams, and may provide a
transmission mechanism for out-of-band data.


SOCK_DGRAM
Provides datagrams, which are connectionless-mode,
unreliable messages of fixed maximum length.


SOCK_SEQPACKET
Provides sequenced, reliable, bidirectional,
connection-mode transmission path for records. A
record can be sent using one or more output operations
and received using one or more input operations, but a
single operation never transfers part of more than one
record. Record boundaries are visible to the receiver
via the MSG_EOR flag.


If the protocol argument is non-zero, it must specify a protocol that is
supported by the address family. The protocols supported by the system
are implementation-dependent.


The process may need to have appropriate privileges to use the socket()
function or to create some sockets.

PARAMETERS

The function takes the following arguments:

domain
Specifies the communications domain in which a socket is to
be created.


type
Specifies the type of socket to be created.


protocol
Specifies a particular protocol to be used with the socket.
Specifying a protocol of 0 causes socket() to use an
unspecified default protocol appropriate for the requested
socket type.


The domain argument specifies the address family used in the
communications domain. The address families supported by the system are
implementation-dependent.

USAGE

The documentation for specific address families specify which protocols
each address family supports. The documentation for specific protocols
specify which socket types each protocol supports.


The application can determine if an address family is supported by trying
to create a socket with domain set to the protocol in question.

RETURN VALUES

Upon successful completion, socket() returns a nonnegative integer, the
socket file descriptor. Otherwise a value of -1 is returned and errno is
set to indicate the error.

ERRORS

The socket() function will fail if:

EAFNOSUPPORT
The implementation does not support the specified
address family.


EMFILE
No more file descriptors are available for this
process.


ENFILE
No more file descriptors are available for the system.


EPROTONOSUPPORT
The protocol is not supported by the address family,
or the protocol is not supported by the
implementation.


EPROTOTYPE
The socket type is not supported by the protocol.


The socket() function may fail if:

EACCES
The process does not have appropriate privileges.


ENOBUFS
Insufficient resources were available in the system to perform
the operation.


ENOMEM
Insufficient memory was available to fulfill the request.


ENOSR
There were insufficient STREAMS resources available for the
operation to complete.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

accept(3XNET), bind(3XNET), connect(3XNET), getsockname(3XNET),
getsockopt(3XNET), listen(3XNET), recv(3XNET), recvfrom(3XNET),
recvmsg(3XNET), send(3XNET), sendmsg(3XNET), setsockopt(3XNET),
shutdown(3XNET), socketpair(3XNET), attributes(7), standards(7)

June 10, 2002 SOCKET(3XNET)