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[lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open con
From: |
Joel Cunningham |
Subject: |
[lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection |
Date: |
Tue, 5 Jul 2016 15:30:54 +0000 (UTC) |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0 |
Follow-up Comment #5, patch #9039 (project lwip):
I reviewed RFC 793 and I think the only check we aren't doing is if the ACK is
acceptable and no SYN is contained, then the packet is silently ignored.
I honestly can't think of a situation where the remote TCP would only ACK our
SYN, but regardless we aren't exactly following the steps listed:
https://tools.ietf.org/html/rfc793#page-66
If in SYN-SENT:
1. Check for ACK
2. Check for RST
3. Check security precedence
4. Check for SYN
5. If neither SYN or RST, drop
I also noticed during this analysis that it looks like we don't handle
simultaneous opens. This is when both TCPs perform an active open at the same
time, going from SYN-SENT to SYN-RCVD by receiving only a SYN packet. This
can be seen on page 32: https://tools.ietf.org/html/rfc793#page-32. In our
handling of SYN-SENT we only check for both SYN and ACK flags. If my static
analysis is correct, I can open a new bug
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- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Simon Goldschmidt, 2016/07/04
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Simon Goldschmidt, 2016/07/04
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Simon Goldschmidt, 2016/07/04
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Michael Brown, 2016/07/04
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Sylvain Rochet, 2016/07/04
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Simon Goldschmidt, 2016/07/04
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection,
Joel Cunningham <=
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Joel Cunningham, 2016/07/19
- Message not available
- [lwip-devel] [patch #9039] tcp: Avoid 3-second delay for a half-open connection, Joel Cunningham, 2016/07/19