telnet: abort on bad suboption sequence

[bagder]

Instead of trying to repair.

Reported-by: Huseyin Tintas

[Copilot]

Pull request overview

This PR changes the telnet protocol handler to abort on malformed suboption sequences instead of attempting to repair them. This is a security-focused change that removes complex error recovery logic that could potentially lead to infinite loops or other issues.

Key Changes:

• Removed error recovery logic for malformed telnet suboptions
• Simplified error handling to fail immediately with clear error message
• Removed unused process_iac label

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[bagder]

augment review

[augmentcode]

🤖 Augment PR Summary

Summary: Telnet suboption parsing now aborts immediately when an invalid IAC suboption sequence is encountered, instead of trying to recover.
Why: This avoids attempting to “repair” malformed suboptions, which could otherwise lead to incorrect parsing or looping behavior.

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[augmentcode]

Review completed. 1 suggestions posted.

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