We have php 3.0.12/apache running on a Mandrake Linux 6.1 server, attempting to communicate with a socket on a Windows NT 4.0 sp5 machine.  Write operations to the socket are successful, but reading back from the socket always blocks until timeout.

Here's what's supposed to happen:
1. PHP opens a socket to the Windows machine
2. PHP writes a string (a processing instruction to the app on Windows)
3. The app on Windows writes a reply back to PHP
4. PHP reads the reply into a variable, etc etc

Steps 1-3 work correctly.  However, php always fails to read back the reply from the Windows application using any number of approaches, such as:

function doTest(&$command) {
  $reply;
  $fp = fsockopen("marlin.ssc.nmfs.gov", 6692, &$errno, &$errstr, 30);
  if(!$fp) {
    return "Error opening socket.";
  } else {
    fputs($fp,$command);
    while ($buffer = fgets($fp, 128)) {
      $reply .= $buffer;
    }
    fclose($fp);
  }
  return $reply;
}

or replace the fgets with calls to fgetc, or any other piece of file-reading code.

Note the similarity to jisun66@hotmail.com's comment on the fgets manual page online, and the similarity to bug #2493.

FWIW, reading from the windows socket using a java program works without a hitch, so it does appear to be a php-specific problem.