[lwip-devel] [bug #32417] TCP_OVERSIZE seems to have problems with (fast-)retransmission

[tao tang]

Follow-up Comment #2, bug #32417 (project lwip):

When *seqno* is cycled from 2^32 to 0, it's low possible that the unack_list
will become an unordered list.

Supposed that:
1: unack_list is NULL;
2: cwnd >= 8 && MSS == 1024
3: unsent_list is:
packet1: seqno = 0xFFFFFF00;
packet2: seqno = 0x00000300;
packet3: seqno = 0x00000700;
...;
packet8: seqno = 0x00001B00;
4: after tcp_output called, Fast-retransmission occurred(happens on a spurious
event) , retransmitting the first segment of unack_list and now the
unsent_list is(unordered unack_list):
packet2: seqno = 0x00000300;
packet3: seqno = 0x00000700;
...;
packet8: seqno = 0x00001B00;
packet1: seqno = 0xFFFFFF00;
5: unfortunately, timeout-retransmission occurred, the cwnd is reset to 1. 
6: after total TCP_MAXRTX times retransmit packet2, the pcb will be purged.

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