[lwip-devel] [task #6849] Test how checksum on copy could be integrated into the stack

[Jonathan Larmour]

Follow-up Comment #1, task #6849 (project lwip):

For UDP pbufs that need to be copied this is sensible, but for TCP it's more
difficult - what you enqueue doesn't necessarily correspond to what gets sent
- each time you enqueue something you may be adding it to an existing segment,
and you don't want to have to recalculate the checksum each time something is
queued.

OOI, some network hardware, nevermind network drivers, have hardware assist
for checking checksums. But  in both cases that's already handled in lwIP
with e.g. disabling CHECKSUM_GEN_TCP and/or CHECKSUM_CHECK_TCP. So if someone
wants to write a driver that checks the checksum on receive, I think they have
what they need from lwIP to do that.


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