#28141 [Opn]: socket_read return type: false vs "", when PHP_NORMAL_READ

ID: 28141 Updated by: sniper@php.net Reported By: php at richardneill dot org Status: Open Bug Type: Documentation problem Operating System: Linux PHP Version: 4CVS, 5CVS (2005-02-14) Assigned To: andrey New Comment: Forgot this part from that: recv() function is what socket_read() uses internally. Previous Comments: ------------------------------------------------------------------------ [2005-02-14 22:20:51] sniper@php.net From recv() manpage: "Upon successful completion, recv() shall return the length of the message in bytes. If no messages are available to be received and the peer has performed an orderly shutdown, recv() shall return 0. Otherwise, -1 shall be returned and errno set to indicate the error." ------------------------------------------------------------------------ [2005-02-14 17:30:00] php at richardneill dot org Thanks. That makes sense. However, it still leaves a few problems, essentially with wrong documentation. ------------------- 1)The documentation for socket_read http://uk.php.net/manual/en/function.socket-read.php claims: "Note: socket_read() may return a zero length string ("") indicating the end of communication (i.e. the remote end point has closed the connection)." which is obviously not true. --------------------- 2)Example 1 on the sockets page http://uk.php.net/manual/en/ref.sockets.php also supports the interpretation that False => error; null => connection closed if (false === ($buf = socket_read($msgsock, 2048, PHP_NORMAL_READ))) { echo "socket_read() failed: reason: " . socket_strerror($ret) . "\n"; break 2; } if (!$buf = trim($buf)) { continue; } ---------------------- 3)How is one to determine the difference between i)the other side closing the connection normally and ii)something going very wrong with the function? According to the documentation, "" => (i) false => (ii) In fact, it seems that false => (i) or (ii), with no way to tell "" => never actually happens Thanks for your help, Richard ------------------------------------------------------------------------ [2005-02-14 09:10:12] sniper@php.net There is no bug to fix here. You're actually getting "Connection reset by peer" (ECONNRESET) and that makes recv() to return -1 -> PHP socket_read() returns an error and FALSE. Here's simplified WORKING script: #!/usr/local/bin/php <?php error_reporting(E_ALL); /* Allow the script to hang around waiting for connections. */ set_time_limit(0); /* Turn on implicit output flushing so we see what we're getting as it comes in. */ ob_implicit_flush(); $address = '127.0.0.1'; $port = 1111; $sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); socket_bind($sock, $address, $port); socket_listen($sock, 5); do { $msgsock = socket_accept($sock); do { $buf = socket_read($msgsock, 2048, PHP_NORMAL_READ); var_dump($buf); } while ($buf !== FALSE && $buf !== ''); echo socket_strerror(socket_last_error($msgsock)); socket_close($msgsock); echo "Closed msgsocket; waiting for another connection\n"; } while (true); socket_close($sock); echo "Closed main socket, exiting\n"; ?> ------------------------------------------------------------------------ [2004-04-25 06:56:24] php at richardneill dot org Description: ------------ According to the documentation, socket_read() can return: 1)A string - normal data 2)An empty string "" - the other end closed the connection 3)false - something went wrong. But it seems to be returning false on connection close. Reproduce code: --------------- $buffer=socket_read($socket,2048,PHP_NORMAL_READ); if ($buffer===false){ echo "Error: socket_read() failed: reason: ".socket_strerror(socket_last_error())." \n"; exit (1); }elseif ($buffer==''){ echo "Socket $socket returned an empty string. Closing connection\n"; socket_close($socket); }else{ echo "Received data".trim($buffer)."\n"; } Expected result: ---------------- I'm using netcat as a client, and then killing the netcat process with Ctrl-C to simulate remote host disconnecting. I expect to see the socket close. Actual result: -------------- Actually, the php script exits, because socket_read returns false instead of "". This may be a bug in the documentation for socket_read, rather than in its behaviour. Thanks for your help - Richard ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=28141&edit=1