ZapTCP is a (very) small System Extension (INIT), which should be useful to people writing applications which use Apple's MacTCP, or for people using MacTCP applications which may be prone to crashes or unexpected quits.
As anyone who has written MacTCP programs knows, it is a long process involving the crashing and rebooting of the Mac about 20-30 times an hour (at least that's how it turns out for me). To help my finger heal up (it was getting tired of hitting the reset key), I wrote ZapTCP.
The INIT works by installing a system-wide patch which takes control when an application quits (or is quit by a forced MacsBug "es" or force-quit key combination). When it runs, the code scans through all of the currently open MacTCP streams and connections, looking for those that have their stream buffers allocated within the heap that is about to disappear. When ZapTCP finds a stream whose buffers are about to enter na-na land, it forces the connection closed and releases the stream, posting a notification to the user.
ZapTCP used to assume that there were no holes in the list of connections returned by the MacTCP driver. This was found to be incorrect, so that if an application opened up three connections and then closed the second one, only the first would be released by ZapTCP. ZapTCP now searches all possible slots in the list for active streams.
Version 1.2 (2/93 SJF)
---------------------
Previously, ZapTCP opened the MacTCP driver everytime _ExitToShell was called, even if the driver was not open previously. This caused hangs/crashes/other bad things on systems where MacTCP was not available or in special cases, such as SLIP mdevs. In addition, you no longer will have an annoying 2-3 second lock up when the first application exits.
