Originální popis anglicky:
socket - create an endpoint for communication
Návod, kniha: POSIX Programmer's Manual
#include <sys/socket.h>
int socket(int
domain, int
type , int protocol);
The
socket() function shall create an unbound socket in a communications
domain, and return a file descriptor that can be used in later function calls
that operate on sockets.
The
socket() 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-defined.
Symbolic constants that can be used for the domain argument are defined in the
<sys/socket.h> header.
The
type argument specifies the socket type, which determines the
semantics of communication over the socket. The following socket types are
defined; implementations may specify additional socket types:
- 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 paths 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 shall specify a protocol that is
supported by the address family. If the
protocol argument is zero, the
default protocol for this address family and type shall be used. The protocols
supported by the system are implementation-defined.
The process may need to have appropriate privileges to use the
socket()
function or to create some sockets.
Upon successful completion,
socket() shall return a non-negative integer,
the socket file descriptor. Otherwise, a value of -1 shall be returned and
errno set to indicate the error.
The
socket() function shall 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.
The following sections are informative.
None.
The documentation for specific address families specifies which protocols each
address family supports. The documentation for specific protocols specifies
which socket types each protocol supports.
The application can determine whether an address family is supported by trying
to create a socket with
domain set to the protocol in question.
None.
None.
accept() ,
bind() ,
connect() ,
getsockname() ,
getsockopt() ,
listen() ,
recv() ,
recvfrom() ,
recvmsg() ,
send() ,
sendmsg() ,
setsockopt() ,
shutdown() ,
socketpair() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<netinet/in.h>,
<sys/socket.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
