socket_create()

(PHP 4 >= 4.1.0, PHP 5, PHP 7)

创建一个套接字（通讯节点）

说明

创建并返回一个套接字，也称作一个通讯节点。一个典型的网络连接由 2 个套接字构成，一个运行在客户端，另一个运行在服务器端。

参数

$domain参数指定哪个协议用在当前套接字上。

$type参数用于选择套接字使用的类型。

$protocol参数，是设置指定$domain套接字下的具体协议。这个值可以使用getprotobyname()函数进行读取。如果所需的协议是 TCP 或 UDP，可以直接使用常量SOL_TCP和SOL_UDP。

返回值

socket_create()正确时返回一个套接字，失败时返回FALSE。要读取错误代码，可以调用socket_last_error()。这个错误代码可以通过socket_strerror()读取文字的错误说明。

更新日志

错误／异常

如果使用一个无效的$domain或$type，socket_create()会使用AF_INET和SOCK_STREAM替代无效参数，同时会发出E_WARNING警告信息。

参见

• socket_accept()接受套接字上的连接
• socket_bind()给套接字绑定名字
• socket_connect()开启一个套接字连接
• socket_listen()监听一个套接字的连接
• socket_last_error()返回套接字上的最后一个错误
• socket_strerror()返回一个描述套接字错误的字符串

Took me about 20 minutes to figure out the proper arguments to supply for a AF_UNIX socket. Anything else, and I would get a PHP warning about the 'type' not being supported. I hope this saves someone else time. 

It took some time to understand how one PHP process can communicate with another by means of unix udp sockets. Examples of 'server' and 'client' code are given below. Server is assumed to run before client starts.
'Server' code

'Client' code 

Note that if you create a socket with AF_UNIX, a file will be created in the filesystem. This file is not removed when you call socket_close - you should unlink the file after you close the socket.

Please be aware that RAW sockets (as used for the ping example) are restricted to root accounts on *nix systems. Since web servers hardly ever run as root, they won't work on webpages.
On Windows based servers it should work regardless.

Okay I talked with Richard a little (via e-mail). We agree that getprotobyname() and using the constants should be the same in functionality and speed, the use of one or the other is merely coding style. Personally, we both think the constants are prettier :).
The eight different protocols are the ones implemented in PHP- not the total number in existance (RFC 1340 has 98).
All we disagree on is using 0- Richard says that "accordning to the official unix/bsd sockets 0 is more than fine." I think that since 0 is a reserved number according to RFC 1320, and when used usually refers to IP, not one of it's sub-protocols (TCP, UDP, etc.)

I've written the ping() function using socket_create() with SOCK_RAW.
(on Unix System, you need to have the root acces to execute this function) 

Here is a ping function for PHP without using exec/system/passthrough/etc... Very useful to use to just test if a host is online before attempting to connect to it. Timeout is in seconds. 

Here's a ping function that uses sockets instead of exec(). Note: I was unable to get socket_create() to work without running from CLI as root. I've already calculated the package's checksum to simplify the code (the message is 'ping' but it doesn't actually matter). 

On UNIX systems php needs /etc/protocols for constants like SOL_UDP and SOL_TCP.
This file was missing on my embedded platform.

Seems there aren't any examples of UDP clients out there. This is a tftp client. I hope this makes someone's life easier. 

Sometimes when you are running CLI, you need to know your own ip address. 

Here's a solution for icmpv6 ping with php, dropping it here in case if someone has problems with icmpv6 with php.