CURL ERROR: Recv failure: Connection reset by peer - PHP Curl

Introduction

The remote server has sent you a RST packet, which indicates an immediate dropping of the connection, rather than the usual handshake.

Possible Causes

A. TCP/IP

It might be a TCP/IP issue you need to resolve with your host or upgrade your OS most times connection is closed with remote server before it finished downloading the content resulting in Connection reset by peer.....

B. Kernel Bug

Note that there are some issues with TCP window scaling on some Linux kernels after v2.6.17. See the following bug reports for more information:

https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.17/+bug/59331

https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/89160

C. PHP & CURL Bug

You are using PHP/5.3.3 which has some serious bugs too ... I would advise you to work with a more recent version of PHP and CURL

https://bugs.php.net/bug.php?id=52828

https://bugs.php.net/bug.php?id=52827

https://bugs.php.net/bug.php?id=52202

https://bugs.php.net/bug.php?id=50410

D. Maximum Transmission Unit

One common cause of this error is that the MTU (Maximum Transmission Unit) size of packets travelling over your network connection has been changed from the default of 1500 bytes. If you have configured a VPN this most likely must changed during configuration

D. Firewall: iptables

If you don't know your way around these guys they can cause some serious issues .. try and access the server you are connecting to check the following

• You have access to port 80 on that server

Example

 -A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT`

• The Following is at the last line not before any other ACCEPT

Example

  -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited 

• Check for ALL DROP, REJECT and make sure they are not blocking your connection

• Temporary allow all connection as see if it foes through

Experiment

Try on a different server or on a remote server ( So many free cloud hosting online) and test the same script. If it works then my guesses are correct ... You need to update your system

Others Code Related

A. SSL

If Yii::app()->params['pdfUrl'] is a url with https not including proper SSL settings can also cause this error in old version of curl

Resolution: Make sure OpenSSL is installed and enabled then add this to your code

curl_setopt($c, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($c, CURLOPT_SSL_VERIFYHOST, false);

Normally this error means that a connection was established with a server but that connection was closed by the remote server. This could be due to a slow server, a problem with the remote server, a network problem, or (maybe) some kind of security error with data being sent to the remote server but I find that unlikely.

Normally a network error will resolve itself given a bit of time, but it sounds like you’ve already given it a bit of time.

cURL sometimes having issue with SSL and SSL certificates. I think that your Apache and/or PHP was compiled with a recent version of the cURL and cURL SSL libraries plus I don't think that OpenSSL was installed in your web server.

Although I can not be certain However, I believe cURL has historically been flakey with SSL certificates, whereas, Open SSL does not.

Anyways, try installing Open SSL on the server and try again and that should help you get rid of this error.

So what is the URL that Yii::app()->params['pdfUrl'] gives? You say it should be https, but the log shows it's connecting on port 80... which almost no server is setup to accept https connections on. cURL is smart enough to know https should be on port 443... which would suggest that your URL has something wonky in it like: https://196.41.139.168:80/serve/?r=pdf/generatePdf

That's going to cause the connection to be terminated, when the Apache at the other end cannot do https communication with you on that port.

You realize your first $body definition gets replaced when you set $body to an array two lines later? {Probably just an artifact of you trying to solve the problem} You're also not encoding the client_url and client_id values (the former quite possibly containing characters that need escaping!) Oh and you're appending to $body_str without first initializing it.

From your verbose output we can see cURL is adding a content-length header, but... is it correct? I can see some comments out on the internets of that number being wrong (especially with older versions)... if that number was to small (for example) you'd get a connection-reset before all the data is sent. You can manually insert the header:

curl_setopt ($c, CURLOPT_HTTPHEADER, 
   array("Content-Length: ". strlen($body_str))); 

Oh and there's a handy function http_build_query that'll convert an array of name/value pairs into a URL encoded string for you.

All this rolls up into the final code:

$post=http_build_query(array(
  "client_url"=>Yii::app()->params['pdfClientURL'],
  "client_id"=>Yii::app()->params['pdfClientID'],
  "title"=>$title,
  "content"=>$content));

//Open to URL
$c=curl_init(Yii::app()->params['pdfUrl']);
//Send post
curl_setopt ($c, CURLOPT_POST, true);
//Optional: [try with/without]
curl_setopt ($c, CURLOPT_HTTPHEADER, array("Content-Length: ".strlen($post))); 
curl_setopt ($c, CURLOPT_POSTFIELDS, $post);
curl_setopt ($c, CURLOPT_RETURNTRANSFER, true);
curl_setopt ($c, CURLOPT_CONNECTTIMEOUT , 0);
curl_setopt ($c, CURLOPT_TIMEOUT  , 20);
//Collect result
$pdf = curl_exec ($c);
$curlInfo = curl_getinfo($c);
curl_close($c);

I faced same error but in a different way.

When you curl a page with a specific SSL protocol.

curl --sslv3 https://example.com

If --sslv3 is not supported by the target server then the error will be

curl: (35) TCP connection reset by peer

With the supported protocol, error will be gone.

curl --tlsv1.2 https://example.com