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vquic: use apple recvmsg_x - #22341

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icing wants to merge 6 commits into
curl:masterfrom
icing:apple-rcvmsg_x
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vquic: use apple recvmsg_x#22341
icing wants to merge 6 commits into
curl:masterfrom
icing:apple-rcvmsg_x

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@icing

@icing icing commented Jul 17, 2026 •
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Using Apple's secret recvmsg_x and sendmsg_x syscalls for receiving/sending batches of UDP packets.

Since this uses undocumented calls, we'll need an "opt-in" configure/cmake option.

@github-actions github-actions Bot added the tests label Jul 17, 2026
@vszakats vszakats added the appleOS specific to an Apple operating system label Jul 18, 2026
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vszakats reviewed Jul 27, 2026
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Comment thread lib/vquic/vquic.c
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vszakats commented Jul 27, 2026

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Which would be better to add cmake/autotools build bits for this?

  • merging as-is, then I do it in a next PR?
  • I do it stacked on this in a PR now, then merge this, rebase, and merge the build part when both are ready.

Either case I think this needs a rebase on master. (git am and patch -p1 both fail ATM.)

@github-actions github-actions Bot added the HTTP/3 h3 or quic related label Jul 28, 2026
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icing commented Jul 28, 2026

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rebased. Do with this PR how you find the easiest. Maybe just take the patch into you own and we close this?

@vszakats vszakats mentioned this pull request Jul 28, 2026
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vszakats requested a review from Copilot July 28, 2026 23:53
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vszakats commented Jul 28, 2026 •
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Copilot reported issues when I run it over the build-PR (which has this PR verbatim):
#22417 (review)

Also run it here, just in case. (edit: it's reporting two different issues in this run.)

Copilot AI reviewed Jul 28, 2026
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Pull request overview

This PR adds an Apple-specific fast path for QUIC UDP I/O by using Apple’s undocumented recvmsg_x/sendmsg_x syscalls to send/receive batches of datagrams, aiming to reduce syscall overhead similarly to recvmmsg/sendmmsg on other platforms.

Changes:

  • Detect Apple recvmsg_x/sendmsg_x availability and route QUIC send/recv through new syscall(SYS_*msg_x, ...) implementations.
  • Adjust logging to reflect the actual send method used and unify trace output placement.
  • Exclude UDP GRO parsing helpers on Apple when *_msg_x is used.

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Comment thread lib/vquic/vquic.c
Comment thread lib/vquic/vquic.c
Comment on lines +198 to +200
while((rc = syscall(SYS_sendmsg_x, qctx->sockfd, &mmsg, batch, 0)) == -1 &&
(SOCKERRNO == SOCKEINTR || SOCKERRNO == SOCKEMSGSIZE))
;
Comment thread lib/vquic/vquic.c
Comment on lines +212 to +215
failf(data, "QUIC: sendmsg_x() unexpectedly returned %d (errno=%d; %s)",
rc, SOCKERRNO, errstr);
result = CURLE_RECV_ERROR;
goto out;
@vszakats vszakats closed this in 079a11b Jul 29, 2026
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vszakats commented Jul 29, 2026

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Merged via 079a11b #22417

vszakats added a commit to curl/curl-for-win that referenced this pull request Jul 29, 2026
@vszakats
curl.sh: enable experimental Apple fast UDP [ci skip]
577be9c 
curl/curl@079a11b
curl/curl#22341
curl/curl#22417
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