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

[Simon Goldschmidt]

Follow-up Comment #6, bug #32417 (project lwip):

> 1. pcb->last_oversize would not match last_seg->oversize_left

Agreed: we need to reset oversize_left when sending a segment.

> 2.

Is that so? If so, that wouldn't be a bug of TCP_OVERSIZE but a general
problem with retransmission. I.e. segments should be resent as long as they
contain unacked data. The remote host is free to send ACKs to any amount of
data, so that could always hit us in the middle of a segment. By adding your
change (TF_SEG_SENT flag), I fear we would only hide a more general problem.

> 3. 

Agreed, but that's already fixed differently than in your patch (I changed
tcp_pbuf_prealloc() to use pcb->mss for allocation instead of TCP_MSS, so
there's no need for #ifdef in tcp_write.c:428).


Summed up, what's left is a debug-assert that triggers, but in release mode,
no problems should appear.

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