c-ares / c-ares / 28687780094

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push

github

Committed by web-flow

Commit Message

ares_getaddrinfo: handle NULL node per POSIX and implement ARES_AI_PASSIVE (#1186)

`ares_getaddrinfo()` dereferenced the `name` (node) argument with no
NULL check, so calling it with a NULL name crashed in `fake_addrinfo()`
(issue #1035).

Per POSIX, a NULL node is valid as long as a service is provided — the
returned addresses are then synthesized from the service:

- **`ARES_AI_PASSIVE` set** → wildcard address (`0.0.0.0` / `::`),
suitable for `bind()`ing a listening socket.
- **not set** → loopback address (`127.0.0.1` / `::1`), for connecting
to a peer on the local host.
- **both node and service NULL** → `ARES_ENOTFOUND` (POSIX
`EAI_NONAME`).

`ARES_AI_PASSIVE` was already declared in the public API and included in
`ARES_AI_MASK`, but had no implementation. It is now honored.

### Changes
- Guard the both-NULL case with `ARES_ENOTFOUND`.
- Synthesize wildcard/loopback nodes honoring `ai_family`,
`ai_socktype`, `ai_protocol` when `name` is NULL.
- Defensive NULL guard in `fake_addrinfo()`.
- Document NULL-node behavior and the `ARES_AI_PASSIVE` flag in
`ares_getaddrinfo.3`.
- Tests: loopback, passive/wildcard, `AF_INET`/`AF_INET6` selection, and
the both-NULL error case.

All 1074 non-live tests pass locally.

Fixes #1035

Signed-off-by: Brad House <brad@brad-house.com>

Coverage Stats

98 of 100 new or added lines in 2 files covered. (98.0%)

4 existing lines in 4 files now uncovered.

23909 of 26103 relevant lines covered (91.59%)

12336.16 hits per line