[reSIProcate] Multiple Addresses on the same interface

[Gabriel Hege]

Just an addition:

After thinking about it I realized the described problem not only 
applies to when there are multiple addresses on the same interface, but 
always when there are multiple routes to the target.

Best regard,
  gabriel


Gabriel Hege wrote:
> Hi!
> 
> I have a problem using the resiprocate stack on a (Windows) machine with 
> multiple IP addresses assigned to the same interface.
> 
> The setup is the following:
> To be able to run multiple services on the same port on a single 
> machine, it has multiple IPs from the same subnet assigned to its 
> network interface. When I tell the stack to not bind to the primary 
> address but to any other address of this interface, it can't send any 
> locally initiated transactions, but fails with the following message:
> SIP/2.0 503 No matching transport found
> 
> Replying to incoming messages works properly.
> 
> I think the problem lies in how the outgoing transport is chosen:
> WinCompat::determineSourceInterfaceWithoutIPv6() only returns the first 
> matching entry from GetIpAddrTable(), but in my case for example the 
> second would actually be the right one. So I see two solutions to this 
> problem:
> 1. Either checking if we have got a transport for the chosen address in 
> determineSourceInterfaceWithoutIPv6() and else trying the next one.
> 
> 2. Or having determineSourceInterfaceWithoutIPv6() return a list of 
> matching addresses and calling findTransportBySource() on all of them in 
> TransportSelector::transmit() until we find a matching one.
> 
> 
> Are there any better solutions to this problem?
> 
> I get the same error, when compiling with NO_IPHLPAPI. I haven't looked 
> into this code yet, but I guess the problem is pretty much the same and 
> might also apply on Unix/Linux.
> 
> 
> 
> By the way, why is there all this windows-specific code for iphlpapi.dll 
> when doing it the standard way works as well? Especially seeing the 
> following comment in front of determineSourceInterfaceWithoutIPv6():
> 
> // !slg! - This function is horribly slow (upto 200ms) and can cause 
> serious performance issues for servers.
> //         We should consider finding more efficient APIs, or caching 
> some of the results.
> 
> 
> 
> best regards,
>  gabriel
> _______________________________________________
> resiprocate-devel mailing list
> resiprocate-devel at resiprocate.org
> https://list.resiprocate.org/mailman/listinfo/resiprocate-devel