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firezone/rust/connlib
Thomas Eizinger 91c6242ccc refactor(connlib): dynamic sockets for upstream TCP DNS servers (#8334)
Currently - because we know all our upstream DNS servers at the time of
initialisation - we configure them on the TCP DNS client in `connlib`
upfront. This allocates the necessary ports and sockets to emit TCP
packets for queries that we want to send to upstream DNS servers, e.g.
if the Internet Resource is active or if the Firezone-configured
upstream DNS server is also a CIDR resource.

In order to resolve SRV and TXT records within the DNS context of a site
(#8221), we need to send DNS queries to the Gateway's TUN device which
now hosts a DNS server on port 53535 (#8285). The IPs of Gateway's
aren't known until we connect to them, meaning we cannot include them in
the set of upstream resolver IPs that we want our DNS-over-TCP client to
connect to.

To be able to reuse the same library, we refactor the
`dns_over_tcp::Client` implementation to dynamically allocate sockets
for upstream resolvers. With that in place, we will be able to send
DNS-over-TCP queries to Gateway's in case the application requests SRV
or TXT records for a DNS resource.

Related: #8221
2025-03-03 20:50:27 +00:00
..

Connlib

Firezone's connectivity library shared by all clients.

Building Connlib

You shouldn't need to build connlib directly; it's typically built as a dependency of one of the other Firezone components. See READMEs in those directories for relevant instructions.