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[lwip-devel] [bug #49717] Window size in received SYN and SYN-ACK assume
From: |
Ambroz Bizjak |
Subject: |
[lwip-devel] [bug #49717] Window size in received SYN and SYN-ACK assumed scaled but is not |
Date: |
Sun, 27 Nov 2016 19:01:51 +0000 (UTC) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.90 Safari/537.36 |
URL:
<http://savannah.nongnu.org/bugs/?49717>
Summary: Window size in received SYN and SYN-ACK assumed
scaled but is not
Project: lwIP - A Lightweight TCP/IP stack
Submitted by: abizjak
Submitted on: Sun 27 Nov 2016 07:01:49 PM GMT
Category: None
Severity: 3 - Normal
Item Group: Faulty Behaviour
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Planned Release: None
lwIP version: git head
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Details:
>From looking at the code I believe lwIP incorrectly interprets the window size
values in received SYN and SYN-ACK segments.
RFC 7323 states:
"The window field in a segment where the SYN bit is set (i.e., a <SYN> or
<SYN,ACK>) MUST NOT be scaled."
In the code this is in tcp_in.c lines 605 (SYN) 754 (SYN-ACK). In both cases
pcb->snd_wnd is set to SND_WND_SCALE(pcb, tcphdr->wnd) after tcp_parseopt is
called which would have set pcb->snd_scale if the window scale option is
present.
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Reply to this item at:
<http://savannah.nongnu.org/bugs/?49717>
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- [lwip-devel] [bug #49717] Window size in received SYN and SYN-ACK assumed scaled but is not,
Ambroz Bizjak <=