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tls.c: send missing_extension alert on TLS 1.3 SNI absence #10332

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tls.c: send missing_extension alert on TLS 1.3 SNI absence #10332

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10 changes: 8 additions & 2 deletions src/tls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2595,7 +2595,10 @@ static int TLSX_SNI_VerifyParse(WOLFSSL* ssl, byte isRequest)
continue;
}

SendAlert(ssl, alert_fatal, handshake_failure);
SendAlert(ssl, alert_fatal,
IsAtLeastTLSv1_3(ssl->version)
? missing_extension
: handshake_failure);
Comment on lines +2598 to +2601
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Copilot AI Apr 27, 2026

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The TLS-version-dependent alert selection logic is duplicated across both error branches. To reduce repetition and keep future protocol tweaks consistent, consider computing the chosen alert once (e.g., a local int alert = ...) and reusing it in both places, or extracting a small helper for 'SNI required' alert selection.

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WOLFSSL_ERROR_VERBOSE(SNI_ABSENT_ERROR);
return SNI_ABSENT_ERROR;
}
Expand All @@ -2606,7 +2609,10 @@ static int TLSX_SNI_VerifyParse(WOLFSSL* ssl, byte isRequest)
if (ssl_sni->status != WOLFSSL_SNI_NO_MATCH)
continue;

SendAlert(ssl, alert_fatal, handshake_failure);
SendAlert(ssl, alert_fatal,
IsAtLeastTLSv1_3(ssl->version)
? missing_extension
: handshake_failure);
Comment on lines +2612 to +2615
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Copilot AI Apr 27, 2026

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missing_extension is intended for cases where a required extension is absent. In this branch, the SNI extension appears to be present but has WOLFSSL_SNI_NO_MATCH, so missing_extension is likely the wrong alert for TLS 1.3+. Consider using an alert that reflects 'name not recognized' (commonly unrecognized_name per RFC 6066) for the NO_MATCH case, and reserve missing_extension for the truly-absent-extension branch.

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Comment on lines +2612 to +2615
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Copilot AI Apr 27, 2026

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The TLS-version-dependent alert selection logic is duplicated across both error branches. To reduce repetition and keep future protocol tweaks consistent, consider computing the chosen alert once (e.g., a local int alert = ...) and reusing it in both places, or extracting a small helper for 'SNI required' alert selection.

Copilot uses AI. Check for mistakes.
WOLFSSL_ERROR_VERBOSE(SNI_ABSENT_ERROR);
return SNI_ABSENT_ERROR;
}
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