Description:
------------
stream_socket_client() leaves $errno and $errstr empty, when the certificate check for ssl fails.
The manual says "If the value returned in errno is 0 and the function returned FALSE, it is an indication that the error occurred before the connect() call."
But connect() must have been successful to perform a certificate check.

Also, stream_socket_client() throws 3 warnings, but only the first one gives you a hint what went wrong. $php_errormsg gives only the last warning. So the only way to fetch a useful error string is using a custom error handler.

Test script:
---------------
<?php
	ini_set('php_track_errors','1');
	$address = 'ssl://j-matschke.de:443';
	$errno = 0;
	$errstr = '';
	$opt = array(
		'ssl' => array(
			'verify_peer' => true,
			'cafile' => '/etc/ssl/certs/ca-certificates.crt',
			'CN_match' => 'j-matschke.de',
			),
		);
	$context = stream_context_create($opt);
	$conn = stream_socket_client($address, $errno, $errstr, 5, STREAM_CLIENT_CONNECT, $context);
	var_dump($conn);
	var_dump($errno);
	var_dump($errstr);
	var_dump($php_errormsg);
?>

Expected result:
----------------
Only one warning should be thrown. This warning should also be used as $errstr.

Actual result:
--------------
Warning: stream_socket_client(): Peer certificate CN=`*.kasserver.com' did not match expected CN=`j-matschke.de' in /mnt/Daten/home/Code/PHP/Web/servercheck3/buggy/ssl.php on line 14

Warning: stream_socket_client(): Failed to enable crypto in /mnt/Daten/home/Code/PHP/Web/servercheck3/buggy/ssl.php on line 14

Warning: stream_socket_client(): unable to connect to ssl://j-matschke.de:443 (Unknown error) in /mnt/Daten/home/Code/PHP/Web/servercheck3/buggy/ssl.php on line 14
bool(false)
int(0)
string(0) ""
string(84) "stream_socket_client(): unable to connect to ssl://j-matschke.de:443 (Unknown error)"