This is a known bug against RFC3261. http://bugs.sipit.net/show_bug.cgi?id=648
On Thu, May 20, 2010 at 6:31 PM, Aaron Clauson <[email protected]> wrote: > I have a problem understanding how RFC3261 would allow loop detection for a > request that was bouncing between two or more proxies. > > Section 16.6.8 states: > > "Loop detection is performed by verifying that, when a request > returns to a proxy, those fields having an impact on the > processing of the request have not changed." > > That makes sense but then it goes on to state: > > "A common way to create this value is to compute a > cryptographic hash of the To tag, From tag, Call-ID header > field, the Request-URI of the request received (before > translation), the topmost Via header, and the sequence number > from the CSeq header field, in addition to any Proxy-Require > and Proxy-Authorization header fields that may be present." > > If the topmost Via header is included in the hash which is being used to > construct the proxy's own Via header won't it only ever detect a loop if the > request is returned to it without another Via header being added? > > So if Proxy 1 forwards to Proxy 2 which forwards back to Proxy 1 without any > of the fields that impact processing of the request changing how would Proxy > 1 be able to detect the loop given that the hash it creates the second time > the request arrives will be different due to the topmost Via header? > > Aaron > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
