Question

Note: solution at the end

If I attempt to do a HTTP POST of over 1024 characters, it fails. Why? Here is a minimal example:

recipient.php:

<?php if (strlen(file_get_contents('php://input')) > 1000     || strlen($HTTP_RAW_POST_DATA) > 1000) {  echo 'This was a triumph.'; } ?> 

sender.php:

<?php function try_to_post($char_count) {  $url = 'http://gpx3quaa.joyent.us/test/recipient.php';  $post_data = str_repeat('x', $char_count);  $c = curl_init();  curl_setopt_array($c,                     array(  CURLOPT_URL => $url,                             CURLOPT_HEADER => false,                             CURLOPT_CONNECTTIMEOUT => 999,                             CURLOPT_RETURNTRANSFER => true,                             CURLOPT_POST => 1,                             CURLOPT_POSTFIELDS => $post_data                     )  );  $result = curl_exec($c);  echo '{$result}\n';  curl_close($c); }  for ($i=1020;$i<1030;$i++) {  echo 'Trying {$i} - ';  try_to_post($i); } ?> 

output:

Trying 1020 - This was a triumph. Trying 1021 - This was a triumph. Trying 1022 - This was a triumph. Trying 1023 - This was a triumph. Trying 1024 - This was a triumph. Trying 1025 -  Trying 1026 -  Trying 1027 -  Trying 1028 -  Trying 1029 -  

configuration:

PHP Version 5.2.6 libcurl/7.18.0 OpenSSL/0.9.8g zlib/1.2.3 libidn/1.8 lighttpd-1.4.19 

Solution

Add the following option for cURL:

curl_setopt($ch,CURLOPT_HTTPHEADER,array('Expect:')); 

The reason seems to be that any POST over 1024 character causes the ‘Expect: 100-continue’ HTTP header to be sent, and Lighttpd 1.4.* does not support it. I found a ticket for it: http://redmine.lighttpd.net/issues/show/1017

They say it works in 1.5.

Answer 1

You can convince PHP’s curl backend to stop doing the 100-continue-thing by setting an explicit request header:

curl_setopt($ch, CURLOPT_HTTPHEADER, array('Expect:')); 

This way you can post a request however long you would ever want and curl will not do the dual phase post.

I’ve blogged about this nearly two years ago.