X-Recipient: archive-cygwin AT delorie DOT com X-SWARE-Spam-Status: No, hits=1.4 required=5.0 tests=AWL,BAYES_05,RFC_ABUSE_POST,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org From: "Estabrook, Edward" To: "cygwin AT cygwin DOT com" Date: Tue, 21 Dec 2010 14:05:43 -0800 Subject: Re: Bug? UDP packet transmitted via sendto() intermitently not being transmitted to network Message-ID: <4483E11778CA964F9644B68621E1CA46479572A1@CRPMBOXPRD02.polycom.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com 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.=20=20 Whether it works or not, it'll tell me if the issue is a change between=20 those versions or something older. (Plus the build instructions and=20 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 versio= n 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 >strace. OK, thanks. I see debug_printf() and syscall_printf() statements sprinkled= around the source. Where do these end up displayed / logged? How are the= y enabled?=20=20 > Corinna wrote: >Apart from actual debugging it yourself, a testcase, as outlined above, >might be helpful. The details describe *what* happens, but unfortunately >don't even allow to guess *why* it happens. Understood. I need to perform more investigation before I can guess why, e= ither. Best Regards, Ed -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple