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consomme: add support for dns over tcp - #2807
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Pull request overview
This PR adds DNS over TCP support to the consomme network stack, complementing the existing DNS over UDP functionality introduced in PR #2633. When a guest initiates a TCP connection to the gateway IP on port 53, consomme intercepts the connection and handles DNS queries using platform-specific system resolvers (DnsQueryRaw on Windows, res_nsend on Unix) instead of creating a real host socket.
Changes:
- Implements virtual TCP DNS handler that processes DNS queries over TCP without real sockets
- Adds TCP transport support to platform-specific DNS resolver backends (RES_USEVC flag for Unix, DNS_PROTOCOL_TCP for Windows)
- Refactors DNS backend to use Arc instead of Box to enable sharing between UDP and TCP handlers
Reviewed changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| vm/devices/net/net_consomme/consomme/src/lib.rs | Defines DNS_PORT constant at crate level for reuse |
| vm/devices/net/net_consomme/consomme/src/udp.rs | Updates UDP DNS handler to include transport type in DnsFlow |
| vm/devices/net/net_consomme/consomme/src/tcp/ring.rs | Removes test-only attribute from is_empty() method (now used in production) |
| vm/devices/net/net_consomme/consomme/src/tcp.rs | Adds TcpBackend enum, DNS TCP connection handling, and poll_dns_backend method |
| vm/devices/net/net_consomme/consomme/src/dns_resolver/mod.rs | Adds DnsTransport enum and changes backend from Box to Arc for sharing |
| vm/devices/net/net_consomme/consomme/src/dns_resolver/dns_tcp.rs | New module implementing DNS TCP framing and message handling per RFC 1035 |
| vm/devices/net/net_consomme/consomme/src/dns_resolver/windows/mod.rs | Adds DNS_PROTOCOL_TCP support to Windows resolver backend |
| vm/devices/net/net_consomme/consomme/src/dns_resolver/unix/glibc.rs | Adds RES_USEVC flag support for TCP queries and refactors ResState structure |
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Pull request overview
Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.
Comments suppressed due to low confidence (1)
vm/devices/net/net_consomme/consomme/src/dns_resolver/unix/glibc.rs:227
- This test comment says “With RES_USEVC set, this should use TCP instead of UDP”, but the test doesn’t actually assert anything about transport selection (it only calls
send_queryand ignores the result). Consider either renaming the test to reflect what it verifies (options bit manipulation) or adding a deterministic assertion; otherwise it adds extra resolver I/O without validating the intended behavior.
// With RES_USEVC set, this should use TCP instead of UDP.
let _answer_len = state.send_query(&sample_dns_query());
Ben Hillis (benhillis)
dismissed
John Starks (jstarks)’s stale review
March 8, 2026 19:28
Stale comments.
Ben Hillis (benhillis)
approved these changes
Mar 10, 2026
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Pull request overview
Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.
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Daman Mulye (damanm24)
merged commit Mar 10, 2026
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84 of 86 checks passed
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This PR adds support for DNS over TCP.
If a TCP connection is being initiated (by the guest), addressed to consommé's gateway IP on port 53, consommé's TCP module will intercept the request and instead of creating a socket on the host it will submit the DNS query on behalf of the guest using the resolver implementation that was introduced in #2633.