Pretty fun puzzle, but this kind of debugging is alien to me. Without going into too much detail, it's pretty easy to see something suspect is going on, and this hunch can be easily tested. This debugging tour takes you to strace, wireshark, all sorts of other low level debugging techniques, when really all you had to do was simulate the client with curl -d and the problem would have been pretty obvious.
And in this case the more complicated debugging tools didn't even explain anything. As the last page says, the answer is kind of a leap. If you already knew about this problem curl would have solved it immediately, and if you didn't you'd still be baffled even after knowing exactly why the stack traces are the way they are.
And in this case the more complicated debugging tools didn't even explain anything. As the last page says, the answer is kind of a leap. If you already knew about this problem curl would have solved it immediately, and if you didn't you'd still be baffled even after knowing exactly why the stack traces are the way they are.