How do I see if an established socket is stuck on a server that's expecting input?

Question

I have a script that scans ports for open proxy servers. Problem is if it encounters a login program (specifically telnet) then it hangs there forever since it doesn't know what to do and eventually the server closes the connection.

The simple solution would be to create a bunch of cases. If telnet, do this. If SSH, do that. If something else, blah blah blah. I'd like an umbrella solution since the script is not a high priority for me.

The script, as it is now, is available at http://parkrrr.net/socks/scan.phps

On a small scale (the page maybe averages 15 hits/day) it's fine but on a larger scale I'd be worried about a lot of open zombie sockets.

Swapping the !$strpos doesn't work since servers can return more information than what you requested (headers, ads, etc).

Only accepting a fixed number of bytes (as opposed to appending until EOF, which it does now) from the $fgets also does not seem to work. I am sure this is where it gets stuck: while (!feof($fp)) { $data.=fgets($fp,512); }

But what can I do? Any other suggestions/warnings would also be welcomed.

Answer 1

Use stream_set_timeout to set a read/write timeout on the socket.

Answer 2

Use non-blocking sockets and stream_select with a timeout or a strait poll.