----- Original Message ----- From: "Adam Fullerton" <a...@ardware.co.uk>
To: <lwip-users@nongnu.org> Sent: Saturday, June 26, 2010 7:25 AM Subject: [lwip-users] netif error
Hi All, Has anyone got any idea of what is going wrong in this Wireshark capture? The client sent the character + in frame 6, frame 7 is expected data and the server's reply is in frame 9.
What problem are you observing? I can't see anything wrong with the TCP headers, and I don't know what you expect in the way of data in frame 7.
Frame 7's data does look peculiar - it seems to be a repeat of the data in frame 4, with the data received in frame 6 overwriting the first character, and some binary data appended.
This looks suspiciously like reuse of a pbuf before LWIP had finished with it. Somehow incoming data overwrote data in a previously transmitted segment, and the entire previously transmitted segment is being treated as new data, resulting in it being transmitted again in frame 7 with some new data from the application appended, and an updated TCP header indicating the sequence number has advanced.
A threading issue (multiple allocation of the same pbuf chain) seems most likely.
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