socket_write()

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

Write to a socket

说明

socket_write(resource $socket,string $buffer[,int $length= 0]): int

The function socket_write() writes to the$socketfrom the given$buffer.

参数

$socket
$buffer: The buffer to be written.
$length: The optional parameter$lengthcan specify an alternate length of bytes written to the socket. If this length is greater than the buffer length, it is silently truncated to the length of the buffer.

返回值

Returns the number of bytes successfully written to the socket 或者在失败时返回FALSE. The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual explanation of the error.

Note:
It is perfectly valid for socket_write() to return zero which means no bytes have been written. Be sure to use the===operator to check for FALSE in case of an error.

注释

Note:
socket_write() does not necessarily write all bytes from the given buffer. It's valid that, depending on the network buffers etc., only a certain amount of data, even one byte, is written though your buffer is greater. You have to watch out so you don't unintentionally forget to transmit the rest of your data.

参见

socket_accept()Accepts a connection on a socket
socket_bind()给套接字绑定名字
socket_connect()开启一个套接字连接
socket_listen()Listens for a connection on a socket
socket_read()Reads a maximum of length bytes from a socket
socket_strerror()Return a string describing a socket error

Here we have the same function to write a socket but with improved performance.
If the messager are not larger, they will be written entirely with a single socket_write() call. And is not needed to call the substr() function for the first bucle.
<?php
$st="Message to sent";
$length = strlen($st);
    
  while (true) {
    
    $sent = socket_write($socket, $st, $length);
      
    if ($sent === false) {
    
      break;
    }
      
    // Check if the entire message has been sented
    if ($sent < $length) {
        
      // If not sent the entire message.
      // Get the part of the message that has not yet been sented as message
      $st = substr($st, $sent);
        
      // Get the length of the not sented part
      $length -= $sent;
    } else {
      
      break;
    }
      
  }
?>

I often read in php docs users not checking for the php function returned value, and in the case of socket_write, I could not see here in the comment anyone botering to read on the socket the server reply.
Then one user thought it would be a good idea to use usleep after a socket_write on a smtp connection.
Actually, if you check the server reply, not only will it give time for the server to reply before you write again on the socket, but also this is a great opportunity to check what the server replied you.
For instance, for smtp connection :
In this example MAIL_SERVER, MAIL_PORT and DEBUG are constants I defined.
<?php
function sendmail( $param )
{
  $from  = &$param[ 'from' ];
  $to   = &$param[ 'to' ];
  $message = &$param[ 'data' ];
  
  $isError = function( $string )
  {
    if( preg_match( '/^((\d)(\d{2}))/', $string, $matches ) )
    {
      if( $matches[ 2 ] == 4 || $matches[ 2 ] == 5 ) return( $matches[ 1 ] );
    }
    else
    {
      return( false );
    }
  };
  
  try
  {
    $socket = null;
    if( ( $socket = socket_create( AF_INET, SOCK_STREAM, SOL_TCP ) ) == false )
    {
      throw new Exception( sprintf( "Unable to create a socket: %s", socket_strerror( socket_last_error() ) ) );
    }
    if( !socket_connect( $socket, MAIL_SERVER, MAIL_PORT ) ) 
    {
      throw new Exception( sprintf( "Unable to connect to server %s: %s", MAIL_SERVER, socket_strerror( socket_last_error() ) ) );
    }
    $read = socket_read( $socket, 1024 );
    if( $read == false )
    {
      throw new Exception( sprintf( "Unable to read from socket: %s", socket_strerror( socket_last_error() ) ) );
    }
    
    if( socket_write( $socket, sprintf( "HELO %s\r\n", gethostname() ) ) === false )
    {
      throw new Exception( sprintf( "Unable to write to socket: %s", socket_strerror( socket_last_error() ) ) );
    }
    $read = socket_read( $socket, 1024 );
    if( $read == false )
    {
      throw new Exception( sprintf( "Unable to read from socket: %s", socket_strerror( socket_last_error() ) ) );
    }
    else
    {
      if( ( $errCode = $isError( $read ) ) ) throw new Exception( "Server responded with an error code $errCode" );
    }
    
    if( socket_write( $socket, sprintf( "MAIL FROM: %s\r\n", $from ) ) === false )
    {
      throw new Exception( sprintf( "Unable to write to socket: %s", socket_strerror( socket_last_error() ) ) );
    }
    $read = socket_read( $socket, 1024 );
    if( $read == false )
    {
      throw new Exception( sprintf( "Unable to read from socket: %s", socket_strerror( socket_last_error() ) ) );
    }
    else
    {
      if( ( $errCode = $isError( $read ) ) ) throw new Exception( "Server responded with an error code $errCode" );
    }
    /* And some more code, but not enough place in comment */
    return( $totalWriten );
  }
  catch( Exception $e )
  {
    $ERROR = sprintf( "Error sending mail message at line %d. ", $e->getLine() ) . $e->getMessage();
    return( false );
  }
}

from http://www.manualy.sk/sock-faq/unix-socket-faq-2.html
read() is equivalent to recv() with a flags parameter of 0. Other values for the flags parameter change the behaviour of recv(). Similarly, write() is equivalent to send() with flags == 0.

If you connect to a Server in a way like you do with telnet or some similar protokoll you may have problems with sending data to the server. I found out that at some servers there is a different between:
<?php
  
  socket_write ($my_socket, $line, strlen ($line));
  socket_write ($my_socket, "\r\n", strlen ("\r\n"));
  
?>
witch worked at least, and 
<?php
  socket_write ($my_socket, $line."\r\n", strlen ($line."\r\n"));
?>
wich made the server stop sending any data.
I hope this helps to save a lot of time. I needed about two days to find out, that this was the problem ;)

Some clients (Flash's XMLSocket for example) won't fire a read event until a new line is recieved.
<?php
  /*
   * Write to a socket
   * add a newline and null character at the end
   * some clients don't read until new line is recieved
   *
   * try to send the rest of the data if it gets truncated
   */
  function write(&$sock,$msg) {
    $msg = "$msg\n\0";
    $length = strlen($msg);
    while(true) {
      $sent = socket_write($sock,$msg,$length);
      if($sent === false) {
        return false;
      }
      if($sent < $length) {
        $msg = substr($msg, $sent);
        $length -= $sent;
        print("Message truncated: Resending: $msg");
      } else {
        return true;
      }
    }
    return false;
  }
?>

Hi,
if you got same problems like i have
<?php
@socket_write($xd, "Good Bye!\n\r");
@socket_shutdown($xd, 2);
@socket_close($xd);
?>
wont'tx send "Good Bye!\n\r" to the opened socket.
but if you put a
usleep or something like echo "";
between write and shutdown its working.

function AddTCPChecksum(&$data){
//feel free to add some error handling for strlen($data)>65535...
$data=pack("v",strlen($data)).$data;
}