Stay connected to download images with fsockopen? - php

Question

I've made a basic script to get the html page and images. But I would like to continue to stay connected while I am retrieve pictures.
- What I did with the test script was kept on asking for addresses on the web server. But It did not work. So how do I do it or what have I done wrong?
Basic script:
function fetch( $server, $url, $port = 80, &$resp_head )
{
if ( !$con = #fsockopen($server, $port, $error_number, $error_string, 30) ) return False;
stream_set_timeout( $con, 8600 );
// Reguest
$qry_header = 'GET '.$url." HTTP/1.1\r\n";
$qry_header .= 'Host: '.$server."\r\n";
$qry_header .= 'User-Agent: Mihtyom; (+http://'.$_SERVER['HTTP_HOST']."/)\r\n";
$qry_header .= "Accept: */*\r\n"; //google check the 3 "Accept"
$qry_header .= "Accept-Language: *\r\n";
$qry_header .= "Accept-Encoding: *\r\n";
$qry_header .= "Connection: Close\r\n\r\n";
fwrite( $con, $qry_header );
$inheader = True;
$data = '';
while (!feof( $con ))
{
$line = fgets( $con );
if (!$inheader)
{
$data .= $line;
continue;
}
if ($line == "\n" || $line == "\r\n")
{
$inheader = False;
continue;
}
$resp_head[] = trim($line);
}
fclose( $con );
return $data;
}
Test script:
function fetch( $server, $urls, $port = 80, &$resp_head )
{
if ( !$con = #fsockopen($server, $port, $error_number, $error_string, 30) ) return False;
stream_set_timeout( $con, 8600 );
$resp_head = array();
$data = array();
foreach ($urls as $key => $url)
{
$inheader = True;
$data[$key] = '';
// Reguest
$qry_header = 'GET '.$url." HTTP/1.1\r\n";
$qry_header .= 'Host: '.$server."\r\n";
$qry_header .= 'User-Agent: Mihtyom; (+http://'.$_SERVER['HTTP_HOST']."/)\r\n";
$qry_header .= "Accept: */*\r\n"; //google check the 3 "Accept"
$qry_header .= "Accept-Language: *\r\n";
$qry_header .= "Accept-Encoding: *\r\n";
$qry_header .= "Connection: Close\r\n\r\n";
fwrite( $con, $qry_header );
while (!feof( $con ))
{
$line = fgets( $con );
if (!$inheader)
{
$data[$key] .= $line;
continue;
}
if ($line == "\n" || $line == "\r\n")
{
$inheader = False;
continue;
}
$resp_head[$key][] = trim($line);
}
}
fclose( $con );
return $data;
}
New script (21-07-12 12:34):
function fetch( $server, $urls, $port = 80, &$resp_head )
{
if ( !$con = #pfsockopen($server, $port, $error_number, $error_string, 30) ) return False;
stream_set_timeout( $con, 8600 );
$resp_head = array();
$data = '';
$i = count($urls);
foreach ($urls as $key => $url )
{
$i--;
// Reguest
$qry_header = 'GET '.$url." HTTP/1.1\r\n";
$qry_header .= 'Host: '.$server."\r\n";
$qry_header .= 'User-Agent: Mihtyom; (+http://'.$_SERVER['HTTP_HOST']."/)\r\n";
$qry_header .= "Accept: */*\r\n";
$qry_header .= "Accept-Language: *\r\n";
$qry_header .= "Connection: ".($i == 0 ? 'Close' : 'keep-alive')."\r\n\r\n";
fwrite( $con, $qry_header );
}
while (!feof( $con ))
{
$line = fgets( $con );
if ($line == "\r\n\r\n" || $line == "\n\n") break;
$data .= $line;
}
fclose( $con );
return $data;
}

Answer 1

You specify Connection: Close in the HTTP header, which basically tells the server: "give me this one file and then close the connection immediately". You are actually forcing the connection to close yourself.
Instead, you can specify Connection: Keep-Alive, which tells the server (explicitly) to not close the TCP session so you can reuse it for another request.
However, the server must not accept this in any case - it may ignore your request and answer with Connection: Close. Also, each side of the connection may at any time close the connection and/or tell the other side to do so in the (next) header, via Connection: Close.
For a correct implementation, you should specify Connection: Close when your loop processes the last URL.
Find more details about persistent connections in HTTP 1.1 / RFC 2068 Section 14.10, HTTP 1.1 / RFC 2616 Section 19.6.2.