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I have a problem with the mbedtls server(stm32+lwip) send wrong length message. I am using this code in my project. https://github.com/straight-coding/straight-httpd-lwip-mbedtls-simulator

Wireshark packet trace. A TLSv1.2 "server hello" packet is selected

Server hello message include 150 byte message but in the packet details this message should be 576 byte. Selected packet is showing a red warning: "IPv4 total length exceeds packet length (136 bytes)"

When I checked the low_level_output function I can only see 150 byte data, why the packet length is wrong ? How can I solve the problem ?

gogogo
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  • Perhaps you could ask on networkengineering.stackexchange.com or the programming site. I'm not really sure your problem is electronics (hardware) related. – akwky Sep 30 '21 at 11:07
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    @akwky it appears to be related to this specific library or program, and networkengineering does not deal with individual computers on the network – user253751 Sep 30 '21 at 17:14
  • These kinds of mystery errors are often the worst part of using other people's open-source libraries. – user4574 Jul 16 '23 at 18:32

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I have the same problem with stm32f746 and lwip while sending a large data out.

I believe it's a cache problem since when I enable debug, problem somehow relieves. I could track the framelength before Ethernet transmit function and it seems that length is correct but less byte is being send out!

I found out that ST is trying to release a reworked driver for stm32f7 and stm32h7 but the f7 one is not out yet. I don't know whether this problem is fixed in that driver or not.

Did you find any fix for that?

Alireza
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