CLIV. Socket Functions
The socket extension implements a low-level interface to the socket communication functions based on the popular BSD sockets, providing the possibility to act as a socket server as well as a client.
When using these functions, it is important to remember that while many of them have identical names to their C counterparts, they often have different declarations. Please be sure to read the descriptions to avoid confusion.
Those unfamiliar with socket programming can find a lot of useful material in the appropriate Unix man pages, and there is a great deal of tutorial information on socket programming in C on the web, much of which can be applied, with slight modifications, to socket programming in PHP. The Unix Socket FAQ might be a good start.
Note: This extension has been moved to the PECL repository and is no longer bundled with PHP as of PHP 5.3.0.
No external libraries are needed to build this extension.
The socket functions described here are part of an extension to
PHP which must be enabled at compile time by giving the
--enable-sockets option to
Note: IPv6 Support was added with PHP 5.0.0.
This extension has no configuration directives defined in php.ini.
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.
- AF_UNIX (integer)
- AF_INET (integer)
- AF_INET6 (integer)
- SOCK_STREAM (integer)
- SOCK_DGRAM (integer)
- SOCK_RAW (integer)
- SOCK_SEQPACKET (integer)
- SOCK_RDM (integer)
- MSG_OOB (integer)
- MSG_WAITALL (integer)
- MSG_PEEK (integer)
- MSG_DONTROUTE (integer)
- SO_DEBUG (integer)
- SO_REUSEADDR (integer)
- SO_KEEPALIVE (integer)
- SO_DONTROUTE (integer)
- SO_LINGER (integer)
- SO_BROADCAST (integer)
- SO_OOBINLINE (integer)
- SO_SNDBUF (integer)
- SO_RCVBUF (integer)
- SO_SNDLOWAT (integer)
- SO_RCVLOWAT (integer)
- SO_SNDTIMEO (integer)
- SO_RCVTIMEO (integer)
- SO_TYPE (integer)
- SO_ERROR (integer)
- SOL_SOCKET (integer)
- PHP_NORMAL_READ (integer)
- PHP_BINARY_READ (integer)
- SOL_TCP (integer)
- SOL_UDP (integer)
The socket extension was written to provide a usable interface to the powerful BSD sockets. Care has been taken that the functions work equally well on Win32 and Unix implementations. Almost all of the sockets functions may fail under certain conditions and therefore emit an E_WARNING message describing the error. Sometimes this doesn't happen to the desire of the developer. For example the function socket_read() may suddenly emit an E_WARNING message because the connection broke unexpectedly. It's common to suppress the warning with the @-operator and catch the error code within the application with the socket_last_error() function. You may call the socket_strerror() function with this error code to retrieve a string describing the error. See their description for more information.
Note: The E_WARNING messages generated by the socket extension are in English though the retrieved error message will appear depending on the current locale (LC_MESSAGES):
Warning - socket_bind() unable to bind address : Die Adresse wird bereits verwendet
Example 2. Socket example: Simple TCP/IP client
This example shows a simple, one-shot HTTP client. It simply connects to a page, submits a HEAD request, echoes the reply, and exits.
- Table of Contents
- socket_accept -- Accepts a connection on a socket
- socket_bind -- Binds a name to a socket
- socket_clear_error -- Clears the error on the socket or the last error code
- socket_close -- Closes a socket resource
- socket_connect -- Initiates a connection on a socket
- socket_create_listen -- Opens a socket on port to accept connections
- socket_create_pair -- Creates a pair of indistinguishable sockets and stores them in an array
- socket_create -- Create a socket (endpoint for communication)
- socket_get_option -- Gets socket options for the socket
- socket_getpeername -- Queries the remote side of the given socket which may either result in host/port or in a Unix filesystem path, dependent on its type
- socket_getsockname -- Queries the local side of the given socket which may either result in host/port or in a Unix filesystem path, dependent on its type
- socket_last_error -- Returns the last error on the socket
- socket_listen -- Listens for a connection on a socket
- socket_read -- Reads a maximum of length bytes from a socket
- socket_recv -- Receives data from a connected socket
- socket_recvfrom -- Receives data from a socket, connected or not
- socket_select -- Runs the select() system call on the given arrays of sockets with a specified timeout
- socket_send -- Sends data to a connected socket
- socket_sendto -- Sends a message to a socket, whether it is connected or not
- socket_set_block -- Sets blocking mode on a socket resource
- socket_set_nonblock -- Sets nonblocking mode for file descriptor fd
- socket_set_option -- Sets socket options for the socket
- socket_shutdown -- Shuts down a socket for receiving, sending, or both
- socket_strerror -- Return a string describing a socket error
- socket_write -- Write to a socket