feat(ip_recverr): ADD IP_RECVERR and IPV6_RECVERR support for linux

[RaghavendraRQ]

On Linux, enables IP_RECVERR and IPV6_RECVERR socket options

This allows the socket to receive ICMP errors via the error queue, enabling faster detection of network unreachability instead of waiting for connection timeouts.

Features Implemented

• Enable IP_RECVERR and IPV6_RECVERR socket options on Linux
• Add error queue polling in recv path
• Add IcmpError type for ICMP error reporting
• Add tests for ICMP error handling (Not Completed)

Closes #2052

[mxinden]

Good work. I will take a more in-depth look.

[mxinden]

I wonder what performance impact this additional sys call has. Would you mind running the benchmark suite with and without and post the results here?

https://github.com/quinn-rs/quinn/blob/main/quinn-udp/benches/throughput.rs

[thomaseizinger]

Even if it has low overhead, I think it might be better to add a new function to the socket, called something like: recv_icmp_errors.

That means users who don't care about this functionality don't need to pay its cost, plus it will allow us to return a strongly-typed struct like IcmpError from this function without having to change existing APIs.

Returning ICMP messages as errors from recv seems a bit odd to me because it is not the recv call that is failing.