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[lwip-devel] [bug #48563] TCP: simultaneous open not supported
From: |
Joel Cunningham |
Subject: |
[lwip-devel] [bug #48563] TCP: simultaneous open not supported |
Date: |
Tue, 19 Jul 2016 19:08:50 +0000 (UTC) |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0 |
URL:
<http://savannah.nongnu.org/bugs/?48563>
Summary: TCP: simultaneous open not supported
Project: lwIP - A Lightweight TCP/IP stack
Submitted by: jcunningham
Submitted on: Tue 19 Jul 2016 07:08:48 PM GMT
Category: TCP
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
_______________________________________________________
Details:
During static analysis of the code referenced in patch #9039, I've noticed
that LwIP's TCP implementation doesn't seem to handle simultaneous opens.
A simultaneous open is when two hosts perform an active open at the same time,
going from SYN-SENT to SYN-RCVD by receiving only a SYN packet (no ACK flag is
set). This results in a single TCP connection between the two hosts
This is described in RFC 793, page 32:
https://tools.ietf.org/html/rfc793#page-32.
RFC 1122 (page 87) https://tools.ietf.org/html/rfc1122#page-87, further
clarifies simultaneous opens as a MUST and addresses errata from 793
In our handling of SYN-SENT (in tcp_process) we only check for both SYN and
ACK flags, not making it possible to only receive a SYN
_______________________________________________________
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- [lwip-devel] [bug #48563] TCP: simultaneous open not supported,
Joel Cunningham <=