Reject over-long unix socket paths in server_ports

[moonchen]

Problem

A unix domain socket path in proxy.config.http.server_ports longer than sun_path (108 bytes including the terminator) is silently truncated: UnAddr's constructors strncpy into the 108-byte buffer, and an over-long input also leaves it unterminated (strncpy writes no terminator when it truncates). ATS then binds a listener on the wrong filesystem path — observed as the 107-byte truncated path plus a garbage byte in ss -xl — or dies at startup with Could not bind or listen to port 0 ... (error: 98) Address already in use when the truncated prefix happens to name an existing directory. Nothing tells the operator the configured path was too long. (The jsonrpc server already rejects an over-long socket path with a clear error; the traffic listener did not.)

Fix

• HttpProxyPort::processOptions: reject a unix path that cannot fit sun_path, with a Warning naming the limit, like other invalid port tokens. The descriptor is dropped; as with any fully-invalid descriptor, ATS falls back to the default port if nothing valid remains.
• UnAddr(const char *) / UnAddr(const std::string &): always null-terminate _path, so no future caller can produce an unterminated path buffer.

Tests

• test_RecHttp: a normal unix path parses; the maximum-length (107-byte) path parses intact; a 108-byte path is rejected with the new warning.
• test_ink_inet: over-long UnAddr construction yields a terminated, truncated _path from both string constructors.

[Copilot]

Pull request overview

This PR hardens UNIX domain socket support in proxy.config.http.server_ports by preventing over-long sun_path values from being accepted (which previously could be silently truncated and/or unterminated), and adds unit tests to lock in the new behavior.

Changes:

• Reject AF_UNIX server port descriptors whose path length cannot fit in sockaddr_un::sun_path, emitting a warning and dropping the invalid descriptor.
• Ensure UnAddr string constructors always null-terminate _path even when truncation occurs.
• Add unit tests covering max-length parsing, rejection behavior, and null-termination guarantees.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/records/RecHttp.cc	Adds validation to reject over-long UNIX socket paths during server_ports parsing, with a clear warning.
include/tscore/ink_inet.h	Makes UnAddr string constructors always null-terminate _path to prevent unterminated buffers on truncation.
src/records/unit_tests/test_RecHttp.cc	Adds coverage for valid UNIX paths, maximum-length paths, and rejection of too-long paths (including warning behavior).
src/tscore/unit_tests/test_ink_inet.cc	Adds coverage ensuring over-long UnAddr construction still yields a terminated, truncated _path.