Bug #66266 [Opn]: socket_sendto always returns true

Edit report at https://bugs.php.net/bug.php?id=66266&edit=1 ID: 66266 User updated by: chuck at jumis dot com Reported by: chuck at jumis dot com Summary: socket_sendto always returns true Status: Open Type: Bug Package: Sockets related Operating System: Darwin Kernel Version 13.0.0 PHP Version: 5.4.22 Block user comment: N Private report: N New Comment: Well let's expand things a little. "fsockopen" has the note about UDP. "UDP sockets will sometimes appear to have opened without an error, even if the remote host is unreachable. The error will only become apparent when you read or write data to/from the socket." And let's expand things a little with ICMP. e.g. "closed-port detection" for the UDP socket type in a non-root environment, functioning on OS X. Is that reasonable? It seems reasonable to me. Previous Comments: ------------------------------------------------------------------------ [2013-12-12 02:34:47] phpmpan at mpan dot pl This is a correct and expected behaviour. Please read some introduction to UDP. Wikipedia provides basic information on that matter: <https://en.wikipedia.org/wiki/User_Datagram_Protocol>. UDP is connectionless (hence there is no such thing as "UDP connection"), fire-and-forget protocol. There is no way to tell if the data was delivered, if it was delivered uncorrupted and sendto can not detect such condition. If you require such functionality, use TCP or proper application-level protocol. However, if you require to know synchronously that a particular packet was not delivered, only application-level protocol will do, and it will be extremely slow (even way below 1kB/s). It is possible to implement closed-port detection. If the remote machine cooperates and no devices on the route block it, one may receive ICMP type 3 code 3 packet. This is how network scanners and few other applications work. However, such solution is unsuitable for sendto as it requires wating for the mentioned packet. Also it may only detect errors: no-error conditions may be false positives. Also the documentation for socket_sendto contains no information you have written about. ------------------------------------------------------------------------ [2013-12-12 00:51:13] chuck at jumis dot com Description: ------------ This always returns true, and the full amount of bytes, even when the remote port is closed. Running socket_recvfrom simply results in an Unavailable error. This is in contrast to running something like socat which will return an error after sending data. Note that the manual does say that UDP connections should return an error following socket_sendto. I've not been able to find a work-around. At present I simply can not test if the target UDP port is open. May be an ICMP issue. Test script: --------------- $fp = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); $bytes = socket_sendto($fp, $json."\n", strlen($json)+1, 0, $ip, $port); $fp && $bytes > 0 && socket_last_error($fp) == 0; Expected result: ---------------- When the remote UDP port is closed, socket_sendto should return false or otherwise socket_recvfrom should return false. Actual result: -------------- The socket pointer and socket_sendto return true -- it is not distinguishable whether or not the remote UDP port is open. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=66266&edit=1