udplite: fix checksum computation on the sender side
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Authored by tuexen on Oct 18 2023, 11:08 AM.

Details

Reviewers

rscheff
glebius

Group Reviewers

transport

Commits

rG15eda0e9027d: udplite: fix checksum computation on the sender side
rG3a89a5d54daa: udplite: fix checksum computation on the sender side
rGaa64a8f5c35c: udplite: fix checksum computation on the sender side

Summary

When the checksum on the sender side is computed, the pseudo header is considered. This shares the memory with the IPv4 header. Therefore several fields in the header can only be set after the checksum has been computed. These fields include the IP version field and the DF bit.

While there, write fields in the sequence they appear in the header.

Test Plan

Run a client and server using UDPLite and also set the IP_DONTFRAG option on the sender side.

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

tuexen created this revision.Oct 18 2023, 11:08 AM

Herald added a reviewer: transport. · View Herald TranscriptOct 18 2023, 11:08 AM

Herald added subscribers: melifaro, imp. · View Herald Transcript

tuexen requested review of this revision.Oct 18 2023, 11:08 AM

glebius accepted this revision.Oct 19 2023, 5:36 AM

glebius added inline comments.

sys/netinet/udp_usrreq.c
1332–1338	Now definitely needed :) Can you please remove XXX and add a comment here: /* Filling only those fields of udpiphdr that participate in the checksum calculation. The rest must be zeroed and will be filled later. */ Wording can be improved or changed, of course.
1397	Let's not keep this XXX unless anybody can remember what it actually warns about.