PHP TCP client socket
Creating a socket that uses the TCP (Transmission Control Protocol)
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);Make sure the socket is successfully created. The onSocketFailure function comes from Handling socket errors example in this topic.
if(!is_resource($socket)) onSocketFailure("Failed to create socket");Connect the socket to a specified address. The second line fails gracefully if connection failed. socket_connect($socket, "chat.stackoverflow.com", 6667) or
onSocketFailure("Failed to connect to chat.stackoverflow.com:6667", $socket);Sending data to the server
The socket_write function sends bytes through a socket. In PHP, a byte array is represented by a string, which is normally encoding-insensitive.
socket_write($socket, "NICK Alice\r\nUSER alice 0 * :Alice\r\n");Receiving data from the server
The following snippet receives some data from the server using the socket_read function. Passing PHP_NORMAL_READ as the third parameter reads until a \r/\n byte, and this byte is included in the return value.
Passing PHP_BINARY_READ, on the contrary, reads the required amount of data from the stream. If socket_set_nonblock was called in prior, and PHP_BINARY_READ is used, socket_read will return false immediately. Otherwise, the method blocks until enough data (to reach the length in the second parameter, or to reach a line ending) are received, or the socket is closed.
This example reads data from a supposedly IRC server.
while(true) {
// read a line from the socket
$line = socket_read($socket, 1024, PHP_NORMAL_READ);
if(substr($line, -1) === "\r") {
// read/skip one byte from the socket
// we assume that the next byte in the stream must be a \n.
// this is actually bad in practice; the script is vulnerable to unexpected values
socket_read($socket, 1, PHP_BINARY_READ);
}
$message = parseLine($line);
if($message->type === "QUIT") break;
}Closing the socket
Closing the socket frees the socket and its associated resources.
socket_close($socket);