Fix TCP checksum calculation to include Ethernet header#1331
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marcusb wants to merge 1 commit intoFreeRTOS:mainfrom
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Fix TCP checksum calculation to include Ethernet header#1331marcusb wants to merge 1 commit intoFreeRTOS:mainfrom
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When ipconfigDRIVER_INCLUDED_TX_IP_CHECKSUM is 0, the TCP checksum was calculated with xDataLength that did not include the Ethernet header size, resulting in incorrect checksums on outgoing TCP packets. This fix parallels the IPv6 implementation which already correctly includes the Ethernet header size (ipSIZE_OF_ETH_HEADER) in the checksum calculation. Add regression test that verifies usGenerateProtocolChecksum is called with the correct data length (ulLen + ipSIZE_OF_ETH_HEADER).
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Summary
Fixes a bug in FreeRTOS+TCP where the TCP checksum was calculated with incorrect data length when
ipconfigDRIVER_INCLUDED_TX_IP_CHECKSUM == 0.Problem
In
prvTCPReturnPacket_IPV4(), the TCP checksum was calculated usingpxNetworkBuffer->xDataLengthwhich at that point did NOT include the Ethernet header size, resulting in incorrect checksums on outgoing TCP packets.Fix
The fix calculate the total length (ulLen + ipSIZE_OF_ETH_HEADER) before calling usGenerateProtocolChecksum(), paralleling the IPv6 implementation which already correctly includes the Ethernet header.
Test
Added regression test
test_prvTCPReturnPacket_TxChecksum_DataLengththat verifies usGenerateProtocolChecksum is called with the correct data length (ulLen + ipSIZE_OF_ETH_HEADER).