socket详解

最新推荐文章于 2025-08-12 00:30:00 发布

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#socket #internet #system #domain #descriptor #protocols

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Syntax

  #include <sys/types.h>
  #include <sys/socket.h>

  int socket(int address_family,
             int type,
             int protocol)

  Service Program Name: QSOSRV1

  Default Public Authority: *USE

  Threadsafe: Yes

The socket() function is used to create an end point for communications. The end point is represented by the socket descriptor returned by the socket() function.

Parameters

address_family

(Input) The address family to be used with the socket. Supported values are:

`AF_INET`	For interprocess communications between processes on the same system or different systems in the Internet domain using the Internet Protocol (IPv4).
`AF_INET6`	For interprocess communications between processes on the same system or different systems in the Internet domain using the Internet Protocol (IPv6 or IPv4).
`AF_NS`	For interprocess communications between processes on the same system or different systems in the domain defined by the Novell or Xerox protocol definitions. Note: The `AF_NS` address family is no longer supported as of V5R2.
`AF_UNIX`	For interprocess communications between processes on the same system in the UNIX domain.
`AF_UNIX_CCSID`	For interprocess communications between processes on the same system in the UNIX domain using the Qlg_Path_Name_T structure.
`AF_TELEPHONY`	For interprocess communications between processes on the same system in the telephony domain. Note: The `AF_TELEPHONY` address family is no longer supported as of V5R3.

type

(Input) The type of communications desired. Supported values are:

`SOCK_DGRAM`	Indicates a datagram socket is desired.
`SOCK_SEQPACKET`	Indicates a full-duplex sequenced packet socket is desired. Each input and output operation consists of exactly one record.
`SOCK_STREAM`	Indicates a full-duplex stream socket is desired.
`SOCK_RAW`	Indicates communication is directly to the network protocols. A process must have the appropriate privilege`*ALLOBJ` to use this type of socket. Used by users who want to access the lower-level protocols directly.

protocol

(Input) The protocol to be used on the socket. Supported values are:

0	Indicates that the default protocol for the type selected is to be used. For example, `IPPROTO_TCP` is chosen for the protocol if the type was set to `SOCK_STREAM` and the address family is `AF_INET`.
`IPPROTO_IP`	Equivalent to specifying the value zero (0).
`IPPROTO_TCP`	Indicates that the TCP protocol is to be used.
`IPPROTO_UDP`	Indicates that the UDP protocol is to be used.
`IPPROTO_RAW`	Indicates that communications is to the IP layer.
`IPPROTO_ICMP`	Indicates that the Internet Control Message Protocol (ICMP) is to be used.
`IPPROTO_ICMPV6`	Indicates that the Internet Control Message Protocol (ICMPv6) is to be used.
`TELPROTO_TEL`	Equivalent to specifying the value zero (0).

Note: When the type is SOCK_RAW, the protocol can be set to some predefined protocol number from 0-255. See Usage Notes for further details.

Authorities

When the SOCKET being created is of type SOCK_RAW, the thread must have *ALLOBJ special authority. When the thread does not have this authority, the EACCES is returned for errno.