fix: clear userauth state on bad service

[ejohnstown]

A USERAUTH_REQUEST naming a service other than "ssh-connection" is
refused before method dispatch, so it drops the per-method state there
too. A following USERAUTH_INFO_RESPONSE is no longer run against a
keyboard-interactive exchange the server has already failed.

• reset ssh->authId and clear ssh->kbSetupPending on the refusal
• leave ssh->kbAuth alone; clients free those buffers by promptCount
• add wolfSSH_TestDoUserAuthInfoResponse() for the tests
• cover the refusal and the stale INFO_RESPONSE in tests/unit.c

Issue: F-10575

[Copilot]

Pull request overview

This PR fixes a server-side USERAUTH edge case where a USERAUTH_REQUEST with an invalid service name (not "ssh-connection") was refused before method dispatch but could leave keyboard-interactive state (e.g., authId, kbSetupPending) in a stale/incorrect state, allowing a subsequent USERAUTH_INFO_RESPONSE to be processed against an exchange the server already failed.

Changes:

• Clear ssh->authId (and ssh->kbSetupPending when enabled) when rejecting USERAUTH due to an invalid service name.
• Expose a new internal test hook wolfSSH_TestDoUserAuthInfoResponse() (keyboard-interactive only) for unit testing.
• Add a regression unit test to ensure bad-service refusal clears keyboard-interactive state and rejects stale INFO_RESPONSE without invoking the userauth callback.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/internal.c	Clears userauth/keyboard-interactive state on invalid service name; adds test wrapper for DoUserAuthInfoResponse().
wolfssh/internal.h	Declares the new internal test entry point for USERAUTH_INFO_RESPONSE handling (keyboard-interactive only).
tests/unit.c	Adds a regression test that validates the state reset on bad service and ensures stale INFO_RESPONSE doesn’t reach the auth callback.

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[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #1201

Scan targets checked: wolfssh-bugs, wolfssh-src

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.