[asterisk-scf-dev] PJSIP TCP transport

[Mark Michelson]

Hi list,

One limitation of PJSIP is that it currently does not allow for IPv6 TCP 
transports to be used, because the code is written with the assumption 
that only IPv4 addresses will be used. I have made changes to the code 
to allow for IPv6 to be used for TCP transports. I've been running the 
included transport_tcp_test and it is failing. I'm baffled as to why 
this might be.

The crux of the problem lies in a call to connect() that is failing and 
setting errno to EINVAL. According to the manpage, EINVAL may happen if 
"The address_len argument is not a valid length for the address family; 
or invalid address family in the sockaddr structure." I have added 
printf debugging to be sure that the address_len is correct and the 
address family in the sockaddr structure are set properly. I also have 
added printf debugging to make sure that the address and port in the 
sockaddr structure, as well as the type of socket passed to connect() 
are the correct types.

For reference, if I change the test back to use IPv4, the test passes. 
While this may seem to point to an issue where an IPv4 assumption in the 
code has not been corrected, I contend that such matters would not 
result in the failed connect() call that I'm seeing. The parameters 
passed to connect are all valid, so it should not be failing. Does 
anyone know of any other reasons that connect() might fail and set errno 
to EINVAL?

Here is a snippet of logs from when the test runs. The initial data is 
retrieved by calling pj_getsockname() on the originating socket, and the 
latter data is retrieved from the pj_sockaddr structure passed to 
pj_sock_connect().

"On v6 connect, trying to connect from socket bound to [::]:43702
Address family is really set correctly
And the len after getsockname is 28
On v6 connect, trying to connect to [fe80::221:9bff:fe02:8e33]:44373
Address family is really set correctly
And the len is 28"

A few more notes:
* The "really set correctly" line is to double-check that the address 
family of the pj_sockaddr is AF_INET6.
* fe80::221:9bff:fe02:8e33 is the link-local IPv6 address of the machine 
on which the test is running.
* I have confirmed through separate tests that 28 is the correct length 
of a sockaddr_in6 structure on this machine.

If anyone has any idea about what's going on, please push me in a proper 
direction. Also, if you want to see the changes I've made, you can 
checkout the "veesix" branch of the pjproject repo.

Thanks!