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Differential D35909

sockets: implement MSG_TRUNC recv/recvmsg flag
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Authored by melifaro on Jul 25 2022, 7:48 PM.
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pauamma_chezdork.com
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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

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.
melifaro updated this revision to Diff 108505.Jul 25 2022, 8:11 PM

.

Harbormaster completed remote builds in B46554: Diff 108505.Jul 25 2022, 8:12 PM
pauamma_chezdork.com accepted this revision.Jul 26 2022, 10:12 PM
pauamma_chezdork.com added a subscriber: pauamma_chezdork.com.

Both are minor and can be changed on commit. (And as always, I can't review the C source.)

lib/libc/sys/recv.2
31

Bump.

190
This revision is now accepted and ready to land.Jul 26 2022, 10:12 PM
melifaro updated this revision to Diff 108633.Jul 28 2022, 11:55 AM

Fix mbuf leak & MSG_TRUNC flag clearning, address comments.

This revision now requires review to proceed.Jul 28 2022, 11:55 AM
Herald added subscribers: bz, ae. · View Herald TranscriptJul 28 2022, 11:55 AM
Harbormaster completed remote builds in B46630: Diff 108633.Jul 28 2022, 11:55 AM
melifaro updated this revision to Diff 108634.Jul 28 2022, 11:56 AM

.

Harbormaster completed remote builds in B46631: Diff 108634.Jul 28 2022, 11:56 AM
pauamma_chezdork.com accepted this revision.Jul 29 2022, 10:22 PM
This revision is now accepted and ready to land.Jul 29 2022, 10:22 PM
Closed by commit rGbe1f485d7d6b: sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg(). (authored by melifaro). · Explain WhyJul 30 2022, 6:47 PM
This revision was automatically updated to reflect the committed changes.
melifaro added a commit: rGbe1f485d7d6b: sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg()..
melifaro added a commit: rGadaf752192c1: sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg()..Feb 9 2023, 6:02 PM

Revision Contents
Changeset List

PathSize
lib/
libc/
sys/
12 lines
sys/
kern/
13 lines
29 lines
netinet6/
2 lines
61 lines
tests/
sys/
kern/
1 line
169 lines
netinet6/
4 lines

Diff 108633

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lib/libc/sys/recv.2

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sys/kern/uipc_socket.c

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sys/kern/uipc_usrreq.c

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sys/netinet6/ip6_input.c

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sys/netinet6/ip6_output.c

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tests/sys/kern/Makefile

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tests/sys/kern/socket_msg_trunc.c

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tests/sys/netinet6/test_ip6_output.py

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