[KingUdo]

Summary of Changes

• Implemented RFC 854 state-aware IAC parser (filter_telnet_iac) that properly handles:
  • 3-byte option negotiations (WILL, WONT, DO, DONT)
  • Variable-length subnegotiations (IAC SB ... IAC SE)
  • Escaped byte sequences (IAC IAC -> 0xFF)
  • 2-byte commands (NOP, BREAK, etc.)
  • Split packets / trailing incomplete IAC bytes across socket reads.
• Replaced single recv with buffered line reading in telnet_read_filtered_input so input chunks are accumulated until newline (\r or \n) is encountered.
• Added MAX_INPUT_LENGTH (default: 256 chars, configurable via environment variable) to cap username and password inputs, preventing memory exhaustion attacks from oversized payloads.
• Added comprehensive unit tests in test_additional.py verifying RFC 854 command parsing, fragmented stream assembly, and length capping.
• Fixes Telnet protocol byte desynchronization and lack of line buffering/length caps #4.

Test Results

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