Re: [PATCH gwproxy v8 2/2] gwproxy: refactor code base to add experimental raw DNS backend

[Ahmad Gani <reyuki@gnuweeb.org>]

On Sat, Sep 6, 2025 at 6:27 PM Ahmad Gani wrote:
> On Sat, Sep 6, 2025 at 11:32 AM Ahmad Gani wrote:
> (( I'll finish this first before working on the single UDP socket model. ))

Now assuming we are using a single UDP socket, how do we match answers to
the DNS queries with the corresponding proxy session? Currently this is
achieved by one UDP socket for each query. In the epoll model, when the
socket is ready for a particular event, it already stores the pointer to
the corresponding proxy session (gwp_conn_pair). And if we are using only
one UDP socket for all queries from all proxy sessions, we might not be
able to rely on the pointer returned by epoll anymore.

So, what are our options in this case? If you want to take a look, I've
pushed new commits in the experimental-raw-dns branch [1].

[1]:
Now the UDP socket only created once at:
https://github.com/realyukii/gwproxy/blob/2b2a85b08b8b178775a064b7e3583540f7397956/src/gwproxy/dns.c#L826-L829
and only registered to epoll once at:
https://github.com/realyukii/gwproxy/blob/2b2a85b08b8b178775a064b7e3583540f7397956/src/gwproxy/ev/epoll.c#L1163-L1171
it can send data over the socket just fine at:
https://github.com/realyukii/gwproxy/blob/2b2a85b08b8b178775a064b7e3583540f7397956/src/gwproxy/ev/epoll.c#L816-L820
and the question is how we fill out udata upon receiving a response at:
https://github.com/realyukii/gwproxy/blob/2b2a85b08b8b178775a064b7e3583540f7397956/src/gwproxy/ev/epoll.c#L1102
one option I can think of is to perform some sort of lookup at:
https://github.com/realyukii/gwproxy/blob/2b2a85b08b8b178775a064b7e3583540f7397956/src/gwproxy/dns.c#L255-L263
after recv, we can use the txid received from the buffer as a key to look
up the corresponding key in the array, what do you think?

--
Ahmad Gani