socket(3SOCKET) 					     Sockets Library Functions						   socket(3SOCKET)

NAME

       socket - create an endpoint for communication

SYNOPSIS

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

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

DESCRIPTION

       The socket() function creates an endpoint for communication and returns a descriptor.

       The  domain argument specifies the protocol family within which communication takes place. The protocol family is generally the same as the
       address family for the addresses supplied in later operations on the socket. These families are defined in <sys/socket.h>.

       The currently supported protocol families are:

       PF_UNIX	   UNIX system internal protocols

       PF_INET	   Internet Protocol Version 4 (IPv4)

       PF_INET6    Internet Protocol Version 6 (IPv6)

       PF_NCA	   Network Cache and Accelerator (NCA) protocols

       The socket has the indicated type, which specifies the communication semantics. Currently defined types are:

	 SOCK_STREAM
	 SOCK_DGRAM
	 SOCK_RAW
	 SOCK_SEQPACKET
	 SOCK_RDM

       There must be an entry in the netconfig(4) file for at least each protocol family and type required. If	a non-zero protocol has been spec-
       ified  but  no  exact  match for the protocol family, type, and protocol is found, then the first entry containing the specified family and
       type with a protocol value of zero will be used.

       A SOCK_STREAM type provides sequenced, reliable, two-way connection-based byte streams. An out-of-band data transmission mechanism  may	be
       supported.  A  SOCK_DGRAM  socket  supports  datagrams (connectionless, unreliable messages of a fixed (typically small) maximum length). A
       SOCK_SEQPACKET socket may provide a sequenced, reliable, two-way connection-based data transmission path for  datagrams	of  fixed  maximum
       length;	a  consumer may be required to read an entire packet with each read system call. This facility is protocol specific, and presently
       not implemented for any protocol family. SOCK_RAW sockets provide access to internal network  interfaces.  The  types  SOCK_RAW,  which	is
       available  only	to  a user with the net_rawaccess privilege, and SOCK_RDM, for which no implementation currently exists, are not described
       here.

       The protocol parameter is a protocol-family-specific value which specifies a particular protocol to be used with the socket.  Normally this
       value  is zero, as commonly only a single protocol exists to support a particular socket type within a given protocol family. However, mul-
       tiple protocols may exist, in which case a particular protocol may be specified in this manner.

       Sockets of type SOCK_STREAM are full-duplex byte streams, similar to pipes. A stream socket must be in a connected state  before  any  data
       may  be	sent or received on it. A connection to another socket is created with a connect(3SOCKET) call. Once connected, data may be trans-
       ferred using read(2) and write(2) calls or some variant of the send(3SOCKET) and recv(3SOCKET) calls. When a session has been completed,  a
       close(2) may be performed. Out-of-band data may also be transmitted as described on the send(3SOCKET) manual page and received as described
       on the recv(3SOCKET) manual page.

       The communications protocols used to implement a SOCK_STREAM insure that data is not lost or duplicated.  If a piece of data for which  the
       peer  protocol  has  buffer  space cannot be successfully transmitted within a reasonable length of time, then the connection is considered
       broken and calls will indicate an error with -1 returns and with ETIMEDOUT as the specific code in the global variable errno. The protocols
       optionally  keep  sockets "warm" by forcing transmissions roughly every minute in the absence of other activity. An error is then indicated
       if no response can be elicited on an otherwise idle connection for a extended period (for instance 5 minutes). A SIGPIPE signal	is  raised
       if a thread sends on a broken stream; this causes naive processes, which do not handle the signal, to exit.

       SOCK_SEQPACKET sockets employ the same system calls as SOCK_STREAM sockets. The only difference is that	read(2) calls will return only the
       amount of data requested, and any remaining in the arriving packet will be discarded.

       SOCK_DGRAM and SOCK_RAW sockets allow datagrams to be sent to correspondents  named  in	sendto(3SOCKET)  calls.  Datagrams  are  generally
       received with recvfrom(3SOCKET), which returns the next datagram with its return address.

       An  fcntl(2)  call  can be used to specify a process group to receive a SIGURG signal when the out-of-band data arrives. It can also enable
       non-blocking I/O.

       The operation of sockets is controlled by socket level options. These options are defined in the file  <sys/socket.h>.  setsockopt(3SOCKET)
       and getsockopt(3SOCKET) are used to set and get options, respectively.

RETURN VALUES

       Upon  successful  completion,  a  descriptor referencing the socket is returned. Otherwise, -1 is returned and errno is set to indicate the
       error.

ERRORS

       The socket() function will fail if:

       EACCES		  Permission to create a socket of the specified type or protocol is denied.

       EAGAIN		  There were insufficient resources available to complete the operation.

       EAFNOSUPPORT	  The specified address family is not supported by the protocol family.

       EMFILE		  The per-process descriptor table is full.

       ENOMEM		  Insufficient user memory is available.

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

       EPFNOSUPPORT	  The specified protocol family is not supported.

       EPROTONOSUPPORT	  The protocol type is not supported by the address family.

       EPROTOTYPE	  The socket type is not supported by the protocol.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       nca(1), close(2), fcntl(2), ioctl(2), read(2), write(2), accept(3SOCKET), bind(3SOCKET), connect(3SOCKET),  getsockname(3SOCKET),  getsock-
       opt(3SOCKET),  in.h(3HEAD),listen(3SOCKET),  recv(3SOCKET), setsockopt(3SOCKET), send(3SOCKET), shutdown(3SOCKET), socket.h(3HEAD), socket-
       pair(3SOCKET), attributes(5)

NOTES

       Historically, AF_* was commonly used in places where PF_* was meant. New code should be careful to use PF_* as necessary.

SunOS 5.11							    28 Jan 2009 						   socket(3SOCKET)