Bug? UDP packet transmitted via sendto() intermitently not being transmitted to network
Wed Dec 22 10:17:00 GMT 2010
On Tue, Dec 21, 2010 at 02:05:43PM -0800, Estabrook, Edward wrote:
>On Dec 10 14:37, Estabrook, Edward wrote:
>>> Generally I am seeking information regarding:
>>> 1) Where can I download and install an older version of Cygwin (say
>>> 1.5 era) to test if the problem is newly introduced?
>> Corinna wrote:
>What for? If it doesn't work on 1.5 you're exactly at the same spot as
>>now. If it works on 1.5, we know it works on 1.5 but we still don't
>>know why it doesn't work on 1.7, which means, you're still exactly at
>>the same spot as now. So that's not really an option. The best option
>>is either to debug the (slim) layer in Cygwin which provides send/recv,
>>or at least to send an as-simple-as-possible, self-sufficient testcase,
>>preferredly in plain C, which allows to reproduce the problem.
>Two reasons. If it works on 1.5, I'll simply use it to perform my testing
>and the time-pressure to solve the root cause is lessened.
>Whether it works or not, it'll tell me if the issue is a change between
>those versions or something older. (Plus the build instructions and
>distributed executable are for SIPp are written with cygwin 1.5 in mind.
>The setup-legacy installer for older versions of Windows is exactly what I
>needed. I tested this out and confirmed the issue exists in the old version as well.
>>> 2) What tools are available to measure potential packet loss within
>>> cygwin itself? (the Windows stack is not reporting dropped UDP
>>> packets, and the packets are not even making it into a locally running
>>> instance of wireshark). Is there a way to dump / access / sniff the
>>> inputs and outputs to the cygwin IP stack? Traffic volume is low so
>>> verbosity would not pose a problem.
>> Corinna wrote:
>>You can add debug output to Cygwin's send and receive functions and use
>OK, thanks. I see debug_printf() and syscall_printf() statements
>sprinkled around the source. Where do these end up displayed / logged?
>How are they enabled?
Via strace, as Corinna said.
strace is a program which is somewhat similar to the linux program
of the same name.
Problem reports: http://cygwin.com/problems.html
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
More information about the Cygwin