03 Jun 2016



Google SoC lwIP Report Week 2

In my second week of working on this project, I have made some progress in linking the Winsock listen() and connect() calls to their lwIP implementations. As with last week, Art Yerkes has been a great souce of information whenever I get stuck on anything. 

I spent the first part of the week figuring out how to extract the information I need from the IRP my driver receives in order to pass it along to lwIP. I also spent some time reading about NT kernel locks so I can safely alter reference objects in my code. I managed to make a successful link between listen() and lwIP's tcp_listen(), but both my server and client test programs stopped responding to the terminal Ctrl-C command. The server freezes when it makes the call to accept(), and the client freezes when it makes the call to connect(). I suspect I am using locks improperly, but I will need Art's help to figure out what is actually going on. 

I figured that making moderate progress in ironing out concurrency bugs would take a large amount of time and effort. Therefore, for the second half of the week, I decided to move onto linking the Winsock connect() call to its lwIP counterpart. Here, my first attempt to call the lwIP tcp_connect() function resulted in an OS crash. While I suspect this may have something to do with my test programs' freezing, I also found that the connect IRP my driver received contained the wrong IP address and port number. Tracing up from my driver, I found that the IP address Winsock sent to its Ancillary Function Driver was also wrong. My last task this week was figuring out how to add debug printouts to a DLL in order to debug Winsock. 

Next week, I will trace the IP address from my client test program down through Winsock to try to figure out where it gets lost or corrupted. I also plan on comparing my branch of ReactOS with trunk to see if they have the same problem. If that goes well, I will either move onto linking Winsock's accept() call with its lwIP counterpart or try to fix my test programs' freezing problem. 


This blog post represents the personal opinion of the author and is not representative of the position of the ReactOS Project.

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