fix(jetsocat): validate JMUX listener destination at CLI parse time#1823
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Benoît Cortier (CBenoit) merged 1 commit intoJun 11, 2026
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Previously, a `tcp-listen://<addr>/<destination>` argument without a port (e.g. a missing `:22`) was accepted at startup, but every incoming connection was then silently dropped with only a debug-level log. The tunnel appeared to work yet forwarded nothing. The listener destination is now parsed during CLI argument parsing, so a malformed destination fails immediately and visibly with a clear error, before any listener is bound.
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Pull request overview
This PR improves jetsocat jmux-proxy reliability by validating the JMUX TCP listener destination during CLI parsing, so malformed destinations fail fast with a clear error instead of causing silent runtime drops.
Changes:
- Add a CLI regression test ensuring a missing destination port fails during argument parsing.
- Parse
tcp-listen://<bind>/<destination>destinations intoDestinationUrlat CLI parse time (rather than per-connection at runtime). - Refactor TCP listener handling to carry a parsed
DestinationUrland emit higher-visibility warnings on JMUX API failures.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| testsuite/tests/cli/jetsocat.rs | Adds a regression test asserting missing destination port is rejected during CLI parsing. |
| jetsocat/src/main.rs | Parses/validates TCP listener destination into DestinationUrl during CLI arg parsing. |
| jetsocat/src/listener.rs | Switches TCP listener to use parsed DestinationUrl and removes per-connection destination parsing. |
| crates/jmux-proto/src/lib.rs | Introduces DestinationUrl::with_scheme and refactors parse_str to use it. |
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| Self::with_scheme(scheme, rest) | ||
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Marc-André Moreau (mamoreau-devolutions)
approved these changes
Jun 11, 2026
Benoît Cortier (CBenoit)
deleted the
fix/jetsocat-fail-loudly-on-invalid-arg
branch
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Previously, a
tcp-listen://<addr>/<destination>argument without a port (e.g. a missing:22) was accepted at startup, but every incoming connection was then silently dropped with only a debug-level log. The tunnel appeared to work yet forwarded nothing.The listener destination is now parsed during CLI argument parsing, so a malformed destination fails immediately and visibly with a clear error, before any listener is bound.