Re: [lwip-users] tcp_enqueue problem, using socket:

[Jonathan Larmour]

Piero 74 wrote:
> here THE LAST report.
> i did the test using "manual sending" on sw on serial port....
> 
> after some clicks (...means.. after some quick send operation on uart,
> and, from lwip to pc tcp client) the problem appears:
> i saw tcp retransmission with checksum error again!!!

Perhaps you are just getting serial errors for the packets you read from
serial before lwip even touches them.

You could experiment with verifying the checksum yourself at the point you
forward the packet to see when this is happening. Remember to only check
starting from the IP header i.e. not including any link level headers.
"lwip/ipv4/inet_chksum.h" has an inet_chksum_pbuf() function, And you can
use pbuf_header to move the header pointer around and then back again. You
will also have to temporarily set the checksum to 0 for the calculation.

Jifl
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