Reject client conn messages before key exchange

[ejohnstown]

• IsMessageAllowedClient() gated the post-userauth rejection on connectState >= CONNECT_KEYED, so every state below it allowed msgid 80 and above.
• A client in the pre-key-exchange DoReceive() loops accepted an unencrypted CHANNEL_OPEN, created the channel and replied with CHANNEL_OPEN_CONF.
• Add a state sweep over the connection-protocol range and a full DoReceive() of a plaintext CHANNEL_OPEN from a pre-auth state.

Issue: F-7628

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[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #1147

Scan targets checked: wolfssh-bugs, wolfssh-src

No new issues found in the changed files. ✅

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Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (3)

src/internal.c:855

• The comment says 'Is client userauth complete?' but the condition checks the opposite (userauth not yet complete). Please update the comment to match the logic (e.g., 'Is client userauth incomplete?') or invert the condition so comment and behavior stay consistent.

    /* Is client userauth complete? */
    if (ssh->connectState < CONNECT_SERVER_USERAUTH_ACCEPT_DONE) {

tests/regress.c:1692

• MSGIDLIMIT_CONN_MAX looks like a limit/sentinel constant rather than a real on-the-wire message ID. Passing it into wolfSSH_TestIsMessageAllowed() could be invalid and (depending on implementation) risk out-of-range indexing or unintended paths. Consider replacing it with a concrete highest valid connection-protocol msgid, or explicitly testing the boundary as MSGIDLIMIT_CONN_MAX - 1 (and, if desired, a separate test for the sentinel/invalid value with clear intent).

    static const byte connMsgs[] = {
        MSGID_GLOBAL_REQUEST, MSGID_CHANNEL_OPEN, MSGID_CHANNEL_DATA,
        MSGID_CHANNEL_REQUEST, MSGIDLIMIT_CONN_MAX
    };

tests/regress.c:1744

• This test relies on BuildChannelOpenPacket() fitting into a fixed 256-byte stack buffer, but it doesn't assert that the returned pktSz is non-zero and <= sizeof(pkt). Adding an assertion here will make failures clearer and prevent accidental truncation/overflow as packet formats evolve.

    byte pkt[256];
    byte out[256];
    word32 pktSz;

    pktSz = BuildChannelOpenPacket("session", 0, 131072, 16384, NULL, 0,
            pkt, sizeof(pkt));