PHP fsockopen client doesn't receive sent data - php

Question

I have the following (stripped-down) piece of code:
function curl_request_async($url, $params)
{
foreach ($params as $key => $val) {
$post_params[] = $key.'='.urlencode($val);
}
$post_string = implode('&', $post_params);
$parts=parse_url($url);
$fp = fsockopen($parts['host'],
isset($parts['port'])?$parts['port']:80,
$errno, $errstr, 30);
fwrite($fp, "$type ".$parts['path']." HTTP/1.1\r\n");
fwrite($fp, "Host: ".$parts['host']."\r\n");
fwrite($fp, "Content-Type: application/x-www-form-urlencoded\r\n");
fwrite($fp, "Content-Length: ".strlen($post_string)."\r\n");
fwrite($fp, "Connection: Close\r\n\r\n");
$bytes_written = fwrite($fp, $post_string);
var_dump($bytes_written, strlen($post_string));
// fread($fp, 1);
// fflush($fp);
fclose($fp);
}
The problem with this code is that I found no evidence the request reached the server called. The line var_dump($bytes_written, strlen($post_string)); outputted int(493) int(493), so it should have received all data, yet it didn't.
If I uncomment fread($fp, 1); it works without a problem. That could be working solution, but it doesn't seem to make sense. There has to be a better way!
My question then is two-fold: why does fread($fp, 1); fix my problem and is there a better solution?

Answer 1

your problem is probably that you wrote the server code in PHP, and you dont have ignore_user_abort=true by default (see http://php.net/manual/en/misc.configuration.php#ini.ignore-user-abort ), so when you close the connection, your server stop executing your php code, thus fread(fp,1) fix your problem - connection dont close before php start writing a response
you can use this code to make a server to test if its actually connecting or not -
<?php
error_reporting(E_ALL);
ini_set('display_errors',1);
$sck=socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
if($sck===FALSE){
die('socket_create failed!');
}
if(!socket_set_block($sck)){
die("socket_set_block failed!");
}
if(!socket_bind($sck, '0.0.0.0',1337)){
die("FAILED to bind to port 1337");
}
if(!socket_listen($sck,0)){
die("socket_listen failed!");
}
$fullFile='';
while((print('listening for connections!'.PHP_EOL)) && false!==($conn=socket_accept($sck))){
echo "new connection!".PHP_EOL;
echo "generating crypto iv..";
while(false!==($buffi=socket_recv($conn,$buff,1024,MSG_WAITALL))){
if($buffi===0){
break;//socket_recv's way of
//saying that the connection closed,
//apparently. the docs say it should return
// false, but it doesn't, it just infinitely returns int(0).
// at least on windows 7 x64 sp1.
}
$fullFile.=$buff;
echo "recieved ".strlen($fullFile)." bytes...".PHP_EOL;
$buff='';//do i need to clear it? or wiill recv do it for me?
}
echo "all bytes recieved (i guess, todo, socket_last_error confirm).";
echo PHP_EOL;var_dump($fullFule);
echo "done!".PHP_EOL;
}
die("should never reach this code...");
it will make a netcat-style server on http://127.0.0.1:1337

Answer 2

fread needs two parameters: a resource and a length number of bytes to read.
Right now you are only reading 1 byte. fread($fp, 1);
If you want to read the complete result, loop it until readed completely:
while(!feof($fp)){
echo fread($fp, 128);
}