Add missing retransmissions for SYN/SYNACK/FIN segments

[danielinux]

No description provided.

[Copilot]

Pull request overview

This pull request implements retransmission logic for TCP control segments (SYN, SYNACK, and FIN) to improve connection reliability when these critical packets are lost. The implementation adds a separate control-segment retransmission timeout (RTO) mechanism that operates independently from the existing data-segment RTO, using exponential backoff with a configurable maximum retry limit.

Changes:

• Added TCP control segment retransmission with separate RTO tracking (ctrl_rto_active, ctrl_rto_retries)
• Implemented exponential backoff for control segment retransmissions with a maximum of 6 retries
• Enhanced tcp_rto_cb to handle SYN_SENT, SYN_RCVD, FIN_WAIT_1, and LAST_ACK states
• Updated FIN acknowledgement detection to properly check for sequence number wraparound
• Added comprehensive unit tests covering retransmission scenarios and edge cases

Reviewed changes

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

File	Description
src/wolfip.c	Added control RTO infrastructure, timer management functions, updated tcp_rto_cb to retransmit control segments, enhanced tcp_ack to detect FIN acknowledgements and stop control timers, initialized control RTO state in connect/close paths, prevented data RTO interference with control states
src/test/unit/unit.c	Added tests for SYN/FINACK retransmission, SYNACK cancellation, FIN_WAIT_1 transition, retry cap enforcement; corrected existing test to use seq+1 for FIN ACK; updated non-established test to use TCP_CLOSED instead of TCP_SYN_SENT

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