As far as I know there is no default option to set a SOCKS or HTTP proxy for fsockopen or stream_socket_client (we could create a context and set a proxy in HTTP options, but that doesn't apply to stream_socket_client). However we can establish a connection manually.
Connecting to HTTP proxies is quite simple:
- The client connects to the proxy server and submits a CONNECT request.
- The server responds 200 if the request is accepted.
- The server then proxies all requests between the client and destination host.
<!- -!>
function connect_to_http_proxy($host, $port, $destination) {
$fp = fsockopen($host, $port, $errno, $errstr);
if ($errno == 0) {
$connect = "CONNECT $destination HTTP/1.1\r\n\r\n";
fwrite($fp, $connect);
$rsp = fread($fp, 1024);
if (preg_match('/^HTTP\/\d\.\d 200/', $rsp) == 1) {
return $fp;
}
echo "Request denied, $rsp\n";
return false;
}
echo "Connection failed, $errno, $errstr\n";
return false;
}
This function returns a file pointer resource if the connection is successful, else FALSE. We can use that resource to communicate with the destination host.
$proxy = "138.204.48.233";
$port = 8080;
$destination = "api.ipify.org:80";
$fp = connect_to_http_proxy($proxy, $port, $destination);
if ($fp) {
fwrite($fp, "GET /?format=json HTTP/1.1\r\nHost: $destination\r\n\r\n");
echo fread($fp, 1024);
fclose($fp);
}
The communication protocol for SOCKS5 proxies is a little more complex:
- The client connects to the proxy server and sends (at least) three bytes: The first byte is the SOCKS version, the second is the number of authentication methods, the next byte(s) is the authentication method(s).
- The server responds with two bytes, the SOCKS version and the selected authentication method.
- The client requests a connection to the destination host. The request contains the SOCKS version, followed by the command (CONNECT in this case), followed by a null byte. The fourth byte specifies the address type, and is followed by the address and port.
- The server finally sends ten bytes (or seven or twenty-two, depending on the destination address type). The second byte contains the status and it should be zero, if the request is successful.
- The server proxies all requests.
<!- -!>
More details: SOCKS Protocol Version 5.
function connect_to_socks5_proxy($host, $port, $destination) {
$fp = fsockopen($host, $port, $errno, $errstr);
if ($errno == 0) {
fwrite($fp, "\05\01\00");
$rsp = fread($fp, 2);
if ($rsp === "\05\00" ) {
list($host, $port) = explode(":", $destination);
$host = gethostbyname($host); //not required if $host is an IP
$req = "\05\01\00\01" . inet_pton($host) . pack("n", $port);
fwrite($fp, $req);
$rsp = fread($fp, 10);
if ($rsp[1] === "\00") {
return $fp;
}
echo "Request denied, status: " . ord($rsp[1]) . "\n";
return false;
}
echo "Request denied\n";
return false;
}
echo "Connection failed, $errno, $errstr\n";
return false;
}
This function works the same way as connect_to_http_proxy. Although both functions are tested, it would be best to use a library; the code is provided mostly for educational purposes.
SSL support and authentication.
We can't create an SSL connection with fsockopen using the ssl:// or tls:// protocol, because that would attempt to create an SSL connection with the proxy server, not the destination host. But it is possible to enable SSL with stream_socket_enable_crypto and create a secure communication channel with the destination, after the connenection with the proxy server has been established. This requires to disable peer verification, which can be done with stream_socket_client using a custom context. Note that disabling peer verification may be a security issue.
For HTTP proxies we can add authentication with the Proxy-Authenticate header. The value of this header is the authentication type, followed by the username and password, base64 encoded (Basic Authentication).
For SOCKS5 proxies the authentication process is - again - more complex. It seems we have to change the authentication code fron 0x00 (NO AUTHENTICATION REQUIRED) to 0x02 (USERNAME/PASSWORD authentication). It is not clear to me how to create a request with the authentication values, so I can not provide an example.
function connect_to_http_proxy($host, $port, $destination, $creds=null) {
$context = stream_context_create(
['ssl'=> ['verify_peer'=> false, 'verify_peer_name'=> false]]
);
$soc = stream_socket_client(
"tcp://$host:$port", $errno, $errstr, 20,
STREAM_CLIENT_CONNECT, $context
);
if ($errno == 0) {
$auth = $creds ? "Proxy-Authorization: Basic ".base64_encode($creds)."\r\n": "";
$connect = "CONNECT $destination HTTP/1.1\r\n$auth\r\n";
fwrite($soc, $connect);
$rsp = fread($soc, 1024);
if (preg_match('/^HTTP\/\d\.\d 200/', $rsp) == 1) {
return $soc;
}
echo "Request denied, $rsp\n";
return false;
}
echo "Connection failed, $errno, $errstr\n";
return false;
}
$host = "proxy IP";
$port = "proxy port";
$destination = "chat.freenode.net:6697";
$credentials = "user:pass";
$soc = connect_to_http_proxy($host, $port, $destination, $credentials);
if ($soc) {
stream_socket_enable_crypto($soc, true, STREAM_CRYPTO_METHOD_ANY_CLIENT);
fwrite($soc,"USER test\nNICK test\n");
echo fread($soc, 1024);
fclose($soc);
}
