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Reviewers

Group Reviewers

manpages
network

Commits

rGadaf752192c1: sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg().
rGbe1f485d7d6b: sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg().

Summary

Implement Linux-variant of MSG_TRUNC flag used in recv(), recvfrom() and recvmsg().

Posix defines MSG_TRUNC as an output flag, indicating packet/datagram truncation. Linux extended it a while (~15+ years) ago to act as input flag, making the returned number of bytes being the full packet size.

It's a (relatively) popular pattern to do recvmsg( MSG_PEEK | MSG_TRUNC) to get the packet size, allocate the buffer and issue another call to fetch the packet. In particular, it's popular in userland netlink code, which is the primary driving factor of this change.

This diff implements the aforementioned behaviour for SOCK_DGRAM sockets (udp, unix, all soreceive_generic() users).

Test Plan

20:09 [2] m@devel0 s kyua debug -k /usr/tests/sys/netinet/Kyuafile socket_afinet:socket_afinet_unix_recv_trunc
socket_afinet:socket_afinet_unix_recv_trunc  ->  passed
20:09 [2] m@devel0 s kyua debug -k /usr/tests/sys/netinet/Kyuafile socket_afinet:socket_afinet_udp_recv_trunc
socket_afinet:socket_afinet_udp_recv_trunc  ->  passed

Diff Detail

Repository

rS FreeBSD src repository - subversion

Lint

Lint Passed

Unit

No Test Coverage

Build Status

Buildable 46553
Build 43442: arc lint + arc unit

Event Timeline

melifaro created this revision.Jul 25 2022, 7:48 PM

Herald added a reviewer: manpages. · View Herald TranscriptJul 25 2022, 7:48 PM

Herald added subscribers: glebius, asomers, imp. · View Herald Transcript

melifaro requested review of this revision.Jul 25 2022, 7:48 PM

Harbormaster completed remote builds in B46553: Diff 108504.Jul 25 2022, 7:48 PM

melifaro retitled this revision from sockets: implement MSG_TRUNC socket option. to sockets: implement MSG_TRUNC recv/recvmsg flag.Jul 25 2022, 8:09 PM

melifaro edited the summary of this revision. (Show Details)

melifaro edited the test plan for this revision. (Show Details)

melifaro added a reviewer: network.