Description:
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I have a problem with stream socket and SSL in PHP 5.6. It seems that SSL is buffering output. In the example below "ehlo" command is ignored (server is not responding). But when something else is sent after "ehlo" e.g. a new line in another call to fwrite, server sends response.

I've tried using stunnel to check if it's a PHP SSL wrapper issue and when I change $host to $host = 'localhost:110;' (my stunnel configuration) everything works perfectly (without adding that special fwrite method).

In PHP 5.4.45 this case work perfectly.

Test script:
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$streamContext = stream_context_create();
$host = 'ssl://smtp.some.server.com:465';
$stream = stream_socket_client($host, $errno, $errstr, $timeout, STREAM_CLIENT_CONNECT, $streamContext);
stream_set_blocking($stream, 1);
stream_set_timeout($stream, $timeout);
stream_set_write_buffer($stream, 0);

$fgets = fgets($stream);
print_r($fgets);

fwrite($stream, "ehlo [127.0.0.1]\r\n");
fwrite($stream, "\r\n"); //when I write this into socket result is OK, without this socket seems to be buffered

$response = '';
do {
    $line = fgets($stream);
    $response .= $line;
} while (null !== $line && false !== $line && ' ' != $line{3});
print_r($response);


Expected result:
----------------
220 epicserver.net.pl ESMTP IdeaSmtpServer v0.80.2 ready.
250-epicserver.net.pl Hello ip-166-242.pl [94.183.162.232], pleased to meet you
250-PIPELINING
250-ENHANCEDSTATUSCODES
250-SIZE
250-8BITMIME
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250 HELP

Actual result:
--------------
220 epicserver.net.pl ESMTP IdeaSmtpServer v0.80.2 ready.