1
0
mirror of https://github.com/golang/go synced 2024-11-23 08:30:05 -07:00
Commit Graph

50 Commits

Author SHA1 Message Date
Roland Shoemaker
e36b4d76ad doc/godebug: document we removed x509sha1
Change-Id: I4a4ff0b9e0d3584b96e414d60b889d68fa8660c0
Reviewed-on: https://go-review.googlesource.com/c/go/+/630236
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
2024-11-20 19:29:11 +00:00
Roland Shoemaker
7c7170e939 crypto/x509: remove x509sha1 GODEBUG
Fixes #41682

Change-Id: I37760f2186e75ec7df9674db25ae466cf453d66d
Reviewed-on: https://go-review.googlesource.com/c/go/+/629676
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
2024-11-20 18:27:31 +00:00
Roland Shoemaker
bc1da38c3d crypto/subtle: add DIT closure
Add a new function, WithDataIndependentTiming, which takes a function as
an argument, and encloses it with calls to set/unset the DIT PSTATE bit
on Arm64.

Since DIT is OS thread-local, for the duration of the execution of
WithDataIndependentTiming, we lock the goroutine to the OS thread, using
LockOSThread. For long running operations, this is likely to not be
performant, but we expect this to be tightly scoped around cryptographic
operations that have bounded execution times.

If locking to the OS thread turns out to be too slow, another option is
to add a bit to the g state indicating if a goroutine has DIT enabled,
and then have the scheduler enable/disable DIT when scheduling a g.

Additionally, we add a new GODEBUG, dataindependenttiming, which allows
setting DIT for an entire program. Running a program with
dataindependenttiming=1 enables DIT for the program during
initialization. In an ideal world PSTATE.DIT would be inherited from
the parent thread, so we'd only need to set it in the main thread and
then all subsequent threads would inherit the value. While this does
happen in the Linux kernel [0], it is not the case for darwin [1].
Rather than add complex logic to only set it on darwin for each new
thread, we just unconditionally set it in mstart1 and cgocallbackg1
regardless of the OS. DIT will already impose some overhead, and the
cost of setting the bit is only ~two instructions (CALL, MSR), so it
should be cheap enough.

Fixes #66450
Updates #49702

[0] e8bdb3c8be/arch/arm64/kernel/process.c (L373)
[1] 8d741a5de7/osfmk/arm64/status.c (L1666)

Change-Id: I78eda691ff9254b0415f2b54770e5850a0179749
Reviewed-on: https://go-review.googlesource.com/c/go/+/598336
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-11-19 16:47:03 +00:00
Ian Lance Taylor
b6aada5e81 doc/godebug: document that unrecognized GODEBUG entries are ignored
Change-Id: I6debc82913ae9fa02bee55dc87d35574f5265008
Reviewed-on: https://go-review.googlesource.com/c/go/+/629576
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
2024-11-19 03:56:07 +00:00
Ian Lance Taylor
aae088b16a doc/godebug: fix tipo
Change-Id: Ib67d81d8e3aa33c6a506813194cc5710b3d5cdd0
Reviewed-on: https://go-review.googlesource.com/c/go/+/629575
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
2024-11-19 03:52:47 +00:00
Austin Clements
3e7cb78800 cmd/go: re-enable build JSON from go test -json, now with GODEBUG
This re-enables the behavior of CL 536399 (by effectively reverting CL
628955), so now go test -json again includes build output and failures
as JSON rather than text.

However, since this behavior is clearly enough to trip up some build
systems, this CL includes a GODEBUG=gotestjsonbuildtext that can be
set to 1 to revert to the old behavior.

Fixes #70402.
Updates #62067.

Cq-Include-Trybots: luci.golang.try:gotip-darwin-arm64_13,gotip-linux-amd64-longtest,gotip-windows-amd64-longtest
Change-Id: I84e778cd844783dacfc83433e391b5ccb5925127
Reviewed-on: https://go-review.googlesource.com/c/go/+/629335
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Austin Clements <austin@google.com>
2024-11-19 02:39:44 +00:00
Filippo Valsorda
0138c1abef Revert "crypto/rand: add randcrash=0 GODEBUG"
A GODEBUG is actually a security risk here: most programs will start to
ignore errors from Read because they can't happen (which is the intended
behavior), but then if a program is run with GODEBUG=randcrash=0 it will
use a partial buffer in case an error occurs, which may be catastrophic.

Note that the proposal was accepted without the GODEBUG, which was only
added later.

This (partially) reverts CL 608435. I kept the tests.

Updates #66821

Change-Id: I3fd20f9cae0d34115133fe935f0cfc7a741a2662
Reviewed-on: https://go-review.googlesource.com/c/go/+/622115
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
2024-10-28 14:46:33 +00:00
Filippo Valsorda
63cd5a39e9 crypto/rand: add randcrash=0 GODEBUG
For #66821

Change-Id: I525c308d6d6243a2bc805e819dcf40b67e52ade5
Reviewed-on: https://go-review.googlesource.com/c/go/+/608435
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
2024-10-07 15:34:42 +00:00
Aperence
3d4daa38a7 net: enable multipath TCP by default for listeners
A previous change [1] was introduced to enable MPTCP by default
for both the clients and servers, based on the discussions [2] in
golang#56539, where MPTCP would be an opt-in for a release or
two, and then would become an opt-out.

This change was not accepted at the time because the support for
a few socket options was missing [3]. Now that this support has been
added [4] and backported to stable versions not to block MPTCP
deployment with Go, it sounds like a good time to reconsider the use
of MPTCP by default.

Instead of enabling MPTCP on both ends by default, as a first step,
it seems safer to change the default behaviour only for the server
side (Listeners). On the server side, the impact is minimal: when
clients don't request to use MPTCP, server applications will create
"plain" TCP sockets within the kernel when connections are accepted,
making the performance impact minimal. This should also ease
experiments where MPTCP is enabled by default on the client side
(Dialer).

The changes in this patch consist of a duplication of the mptcpStatus
enumeration to have both a mptcpStatusDial and a mptcpStatusListen,
where MPTCP is enabled by default in mptcpStatusListen, but disabled
by default in mptcpStatusDial. It is still possible to turn MPTCP support
on and off by using GODEBUG=multipathtcp=1.

[1] https://go-review.googlesource.com/c/go/+/563575
[2] https://go.dev/issue/56539#issuecomment-1309294637
[3] https://github.com/multipath-tcp/mptcp_net-next/issues/383
[4] bd11dc4fb9
[5] https://www.mptcp.dev/faq.html#why--when-should-mptcp-be-enabled-by-default

Updates #56539

Change-Id: I1ca0d6aaf74d3bda5468af135e29cdb405d3fd00
GitHub-Last-Rev: 5f9f29bfc1
GitHub-Pull-Request: golang/go#69016
Reviewed-on: https://go-review.googlesource.com/c/go/+/607715
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
2024-09-03 15:27:29 +00:00
Paschalis T
894ead51c5 doc: fix wording of GODEBUG history item from CL 606055
Change-Id: Ia53d4a58810948d83a3e87e08239602da1bad815
Reviewed-on: https://go-review.googlesource.com/c/go/+/609935
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Cherry Mui <cherryyz@google.com>
2024-08-30 22:56:21 +00:00
Paschalis T
d2b6bdb035 math/rand: make calls to Seed no-op
Makes calls to the global Seed a no-op. The GODEBUG=randseednop=0
setting can be used to revert this behavior.

Fixes #67273

Change-Id: I79c1b2b23f3bc472fbd6190cb916a9d7583250f4
Reviewed-on: https://go-review.googlesource.com/c/go/+/606055
Auto-Submit: Cherry Mui <cherryyz@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-08-19 20:47:27 +00:00
Damien Neil
879ace1434 net/http: keep Content-Encoding in Error, add GODEBUG for ServeContent
This reverts the changes to Error from CL 571995, and adds a
GODEBUG controlling the changes to ServeContent/ServeFile/ServeFS.

The change to remove the Content-Encoding header when serving an error
breaks middleware which sets Content-Encoding: gzip and wraps a
ResponseWriter in one which compresses the response body.

This middleware already breaks when ServeContent handles a Range request.
Correct uses of ServeContent which serve pre-compressed content with
a Content-Encoding: gzip header break if we don't remove that header
when serving errors. Therefore, we keep the change to ServeContent/
ServeFile/ServeFS, but we add the ability to disable the new behavior
by setting GODEBUG=httpservecontentkeepheaders=1.

We revert the change to Error, because users who don't want to include
a Content-Encoding header in errors can simply remove the header
themselves, or not add it in the first place.

Fixes #66343

Change-Id: Ic19a24b73624a5ac1a258ed7a8fe7d9bf86c6a38
Reviewed-on: https://go-review.googlesource.com/c/go/+/593157
Reviewed-by: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-06-18 19:33:10 +00:00
Roland Shoemaker
b691da9f78 Revert "crypto/x509: reject serial numbers longer than 20 octets"
This reverts commit 8524931a2c.

Reason for revert: It turns out, basically no one in private PKIs can
get this right. It causes way too much breakage, and every other impl
also ignores it, so we'll continue to be in good company.

Change-Id: I2da808b411ec12f72112c49079faf9f68ae465c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/589615
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
2024-06-18 15:27:01 +00:00
Ian Lance Taylor
ee4a42bd58 net: add GODEBUG=netedns0=0 to disable sending EDNS0 header
It reportedly breaks the DNS server on some modems.

For #6464
For #21160
For #44135
For #51127
For #51153
Fixes #67925

Change-Id: I54a11906159f00246d08a54cc8be7327e9ebfd2c
Reviewed-on: https://go-review.googlesource.com/c/go/+/591995
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
2024-06-12 17:31:13 +00:00
Rhys Hiltner
ca7d300509 Revert "runtime: remove GODEBUG=runtimecontentionstacks"
This reverts commit 87e930f728 (CL 585639)

Reason for revert: This is part of a patch series that changed the
handling of contended lock2/unlock2 calls, reducing the maximum
throughput of contended runtime.mutex values, and causing a performance
regression on applications where that is (or became) the bottleneck.

Updates #66999
Updates #67585

Change-Id: I1e286d2a16d16e4af202cd5dc04b2d9c4ee71b32
Reviewed-on: https://go-review.googlesource.com/c/go/+/589097
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Rhys Hiltner <rhys.hiltner@gmail.com>
2024-05-30 17:52:17 +00:00
Mordy Ovits
fd1363240a doc: fix two instances of "the the" in godebug.md
Remove two instances of "the the" introduced recently
in CL 562343 and CL 562975.

Change-Id: Ib32ca80fcd6764343021c84135bd65853945c9ea
GitHub-Last-Rev: 0bd2c0b4bd
GitHub-Pull-Request: golang/go#67594
Reviewed-on: https://go-review.googlesource.com/c/go/+/587717
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
2024-05-23 01:45:30 +00:00
Roland Shoemaker
56ec5d96bc crypto/tls: populate Leaf in X509KeyPair
Fixes #67065

Change-Id: I189e194de8aa94523eb64e1dd294a70cb81cbdf6
Reviewed-on: https://go-review.googlesource.com/c/go/+/585856
Auto-Submit: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
2024-05-22 22:58:43 +00:00
Filippo Valsorda
032660573c crypto/tls: disable 3-DES by default
Fixes #66214

Change-Id: Iba8006a17fc7cd33c7485ab1a1ef8f56531c0ed1
Reviewed-on: https://go-review.googlesource.com/c/go/+/587295
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
2024-05-22 21:30:50 +00:00
Roland Shoemaker
0ec709f180 html: update jstmpllitinterp doc
We no longer do anything with this GODEBUG.

Fixes #66217

Change-Id: I998797b6a573013f5b9c8ded835acae572327d18
Reviewed-on: https://go-review.googlesource.com/c/go/+/584117
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Roland Shoemaker <roland@golang.org>
2024-05-22 18:04:29 +00:00
Roland Shoemaker
8524931a2c crypto/x509: reject serial numbers longer than 20 octets
Updates #65085

Change-Id: I8e5fb6c77c54f07247b30afea9fe8c548bf6d0be
Reviewed-on: https://go-review.googlesource.com/c/go/+/562975
Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
2024-05-22 17:23:31 +00:00
Roland Shoemaker
db13584bae crypto/x509: reject negative serial numbers
There is only one trusted certificate I could find in the web pki which
has a negative serial number. Removing this exception seems reasonable.

Updates #65085

Change-Id: I55435b3d75479dcb41d523383e4ff7894a1496ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/562343
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
2024-05-22 17:23:27 +00:00
Filippo Valsorda
d0edd9acc8 crypto/tls: implement X25519Kyber768Draft00
Forced the testConfig CurvePreferences to exclude X25519Kyber768Draft00
to avoid bloating the transcripts, but I manually tested it and the
tests all update and pass successfully, causing 7436 insertions(+), 3251
deletions(-).

Fixes #67061

Change-Id: If6f13bca561835777ab0889a490487b7c2366c3c
Reviewed-on: https://go-review.googlesource.com/c/go/+/586656
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-05-22 14:56:25 +00:00
Rhys Hiltner
87e930f728 runtime: remove GODEBUG=runtimecontentionstacks
Go 1.22 promised to remove the setting in a future release once the
semantics of runtime-internal lock contention matched that of
sync.Mutex. That work is done, remove the setting.

For #66999

Change-Id: I3c4894148385adf2756d8754e44d7317305ad758
Reviewed-on: https://go-review.googlesource.com/c/go/+/585639
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Rhys Hiltner <rhys.hiltner@gmail.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
2024-05-21 17:17:36 +00:00
Russ Cox
6ccd8e4cf6 cmd/go: add support for godebug lines in go.mod and go.work
The fact that the go line sets both the language version and the
GODEBUG compatibility version can be a problem, especially since
the go line is also required to be ≥ the go lines of any required
dependency modules.

This change adds a new 'godebug' line to go.mod and go.work
to allow setting the GODEBUG values for the entire module.

It also adds a new meta-value default=go1.21 that means
take the defaults from Go 1.21 no matter what the go line says.

These were discussed in proposal #65573.

Fixes #65573.

Change-Id: I91746322a10178370ed1015ce5278372a024c824
Reviewed-on: https://go-review.googlesource.com/c/go/+/584476
Auto-Submit: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
2024-05-15 13:52:10 +00:00
Russ Cox
bbdad50c09 doc/godebug: correct gotypealias=1 deprecation
Per the note earlier in the page, GODEBUGs are maintained for a
minimum of two years (four Go releases). Not said but certainly
implied is that they are maintained for four Go releases from the
point where people started needing to use them.

Since people would start needing gotypesalias=0 in Go 1.23,
it can be removed in Go 1.27.

Change-Id: Ifad63a1fff63c3f96f2ee192ca74bd1ce8bdb61f
Reviewed-on: https://go-review.googlesource.com/c/go/+/585457
Auto-Submit: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Eli Bendersky <eliben@google.com>
2024-05-15 12:20:56 +00:00
Ian Lance Taylor
b1ae67501a doc: fix tense in godebug (s/revert/reverted)
Change-Id: Ida6ed22102a6da36739c7581aeab297fdd7bc9f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/561715
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
2024-04-16 17:29:58 +00:00
Russ Cox
966609ad9e time: avoid stale receives after Timer/Ticker Stop/Reset return
A proposal discussion in mid-2020 on #37196 decided to change
time.Timer and time.Ticker so that their Stop and Reset methods
guarantee that no old value (corresponding to the previous configuration
of the Timer or Ticker) will be received after the method returns.

The trivial way to do this is to make the Timer/Ticker channels
unbuffered, create a goroutine per Timer/Ticker feeding the channel,
and then coordinate with that goroutine during Stop/Reset.
Since Stop/Reset coordinate with the goroutine and the channel
is unbuffered, there is no possibility of a stale value being sent
after Stop/Reset returns.

Of course, we do not want an extra goroutine per Timer/Ticker,
but that's still a good semantic model: behave like the channels
are unbuffered and fed by a coordinating goroutine.

The actual implementation is more effort but behaves like the model.
Specifically, the timer channel has a 1-element buffer like it always has,
but len(t.C) and cap(t.C) are special-cased to return 0 anyway, so user
code cannot see what's in the buffer except with a receive.
Stop/Reset lock out any stale sends and then clear any pending send
from the buffer.

Some programs will change behavior. For example:

	package main

	import "time"

	func main() {
		t := time.NewTimer(2 * time.Second)
		time.Sleep(3 * time.Second)
		if t.Reset(2*time.Second) != false {
			panic("expected timer to have fired")
		}
		<-t.C
		<-t.C
	}

This program (from #11513) sleeps 3s after setting a 2s timer,
resets the timer, and expects Reset to return false: the Reset is too
late and the send has already occurred. It then expects to receive
two values: the one from before the Reset, and the one from after
the Reset.

With an unbuffered timer channel, it should be clear that no value
can be sent during the time.Sleep, so the time.Reset returns true,
indicating that the Reset stopped the timer from going off.
Then there is only one value to receive from t.C: the one from after the Reset.

In 2015, I used the above example as an argument against this change.

Note that a correct version of the program would be:

	func main() {
		t := time.NewTimer(2 * time.Second)
		time.Sleep(3 * time.Second)
		if !t.Reset(2*time.Second) {
			<-t.C
		}
		<-t.C
	}

This works with either semantics, by heeding t.Reset's result.
The change should not affect correct programs.

However, one way that the change would be visible is when programs
use len(t.C) (instead of a non-blocking receive) to poll whether the timer
has triggered already. We might legitimately worry about breaking such
programs.

In 2020, discussing #37196, Bryan Mills and I surveyed programs using
len on timer channels. These are exceedingly rare to start with; nearly all
the uses are buggy; and all the buggy programs would be fixed by the new
semantics. The details are at [1].

To further reduce the impact of this change, this CL adds a temporary
GODEBUG setting, which we didn't know about yet in 2015 and 2020.
Specifically, asynctimerchan=1 disables the change and is the default
for main programs in modules that use a Go version before 1.23.
We hope to be able to retire this setting after the minimum 2-year window.
Setting asynctimerchan=1 also disables the garbage collection change
from CL 568341, although users shouldn't need to know that since
it is not a semantically visible change (unless we have bugs!).

As an undocumented bonus that we do not officially support,
asynctimerchan=2 disables the channel buffer change but keeps
the garbage collection change. This may help while we are
shaking out bugs in either of them.

Fixes #37196.

[1] https://github.com/golang/go/issues/37196#issuecomment-641698749

Change-Id: I8925d3fb2b86b2ae87fd2acd055011cbf7bd5916
Reviewed-on: https://go-review.googlesource.com/c/go/+/568341
Reviewed-by: Austin Clements <austin@google.com>
Auto-Submit: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-03-14 18:25:25 +00:00
Russ Cox
508bb17edd time: garbage collect unstopped Tickers and Timers
From the beginning of Go, the time package has had a gotcha:
if you use a select on <-time.After(1*time.Minute), even if the select
finishes immediately because some other case is ready, the underlying
timer from time.After keeps running until the minute is over. This
pins the timer in the timer heap, which keeps it from being garbage
collected and in extreme cases also slows down timer operations.
The lack of garbage collection is the more important problem.

The docs for After warn against this scenario and suggest using
NewTimer with a call to Stop after the select instead, purely to work
around this garbage collection problem.

Oddly, the docs for NewTimer and NewTicker do not mention this
problem, but they have the same issue: they cannot be collected until
either they are Stopped or, in the case of Timer, the timer expires.
(Tickers repeat, so they never expire.) People have built up a shared
knowledge that timers and tickers need to defer t.Stop even though the
docs do not mention this (it is somewhat implied by the After docs).

This CL fixes the garbage collection problem, so that a timer that is
unreferenced can be GC'ed immediately, even if it is still running.
The approach is to only insert the timer into the heap when some
channel operation is blocked on it; the last channel operation to stop
using the timer takes it back out of the heap. When a timer's channel
is no longer referenced, there are no channel operations blocked on
it, so it's not in the heap, so it can be GC'ed immediately.

This CL adds an undocumented GODEBUG asynctimerchan=1
that will disable the change. The documentation happens in
the CL 568341.

Fixes #8898.
Fixes #61542.

Change-Id: Ieb303b6de1fb3527d3256135151a9e983f3c27e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/512355
Reviewed-by: Austin Clements <austin@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Russ Cox <rsc@golang.org>
2024-03-13 21:36:04 +00:00
qmuntal
b09ac10bad os: don't normalize volumes to drive letters in os.Readlink
This CL updates os.Readlink so it no longer tries to normalize volumes
to drive letters, which was not always even possible.

This behavior is controlled by the `winreadlinkvolume` setting.
For Go 1.23, it defaults to `winreadlinkvolume=1`.
Previous versions default to `winreadlinkvolume=0`.

Fixes #63703.

Cq-Include-Trybots: luci.golang.try:gotip-windows-amd64-longtest,gotip-windows-arm64
Change-Id: Icd6fabbc8f0b78e23a82eef8db89940e89e9222d
Reviewed-on: https://go-review.googlesource.com/c/go/+/567735
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-03-04 20:38:54 +00:00
qmuntal
7986e26a39 os: don't treat mount points as symbolic links
This CL changes the behavior of os.Lstat to stop setting the
os.ModeSymlink type mode bit for mount points on Windows. As a result,
filepath.EvalSymlinks no longer evaluates mount points, which was the
cause of many inconsistencies and bugs.

Additionally, os.Lstat starts setting the os.ModeIrregular type mode bit
for all reparse tags on Windows, except for those that are explicitly
supported by the os package, which, since this CL, doesn't include mount
points. This helps to identify files that need special handling outside
of the os package.

This behavior is controlled by the `winsymlink` GODEBUG setting.
For Go 1.23, it defaults to `winsymlink=1`.
Previous versions default to `winsymlink=0`.

Fixes #39786
Fixes #40176
Fixes #61893
Updates #63703
Updates #40180
Updates #63429

Cq-Include-Trybots: luci.golang.try:gotip-windows-amd64-longtest,gotip-windows-arm64
Change-Id: I2e7372ab8862f5062667d30db6958d972bce5407
Reviewed-on: https://go-review.googlesource.com/c/go/+/565136
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
2024-03-04 18:59:50 +00:00
Benjamin Peterson
9853da523e doc: fix typo of gotypesalias
Change-Id: I943a7794dab919b7377661a4b9e2e1d9865f2922
GitHub-Last-Rev: 2a66fce273
GitHub-Pull-Request: golang/go#66063
Reviewed-on: https://go-review.googlesource.com/c/go/+/568495
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
2024-03-04 17:31:32 +00:00
Michael Pratt
c4e4afc90e Revert "os: make FindProcess use pidfd on Linux"
This reverts CL 542699.

Reason for revert: Some applications assume FindProcess does not return
errors.

For #62654.
Fixes #65866.

Change-Id: Ic185a6253c8e508b08150b618c39a9905f6cdd60
Reviewed-on: https://go-review.googlesource.com/c/go/+/566476
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
2024-02-23 18:29:45 +00:00
Kir Kolyshkin
cdf3249d74 os: make FindProcess use pidfd on Linux
Amend FindProcess to use pidfdFind, and make it return ErrProcessDone
if pidfdFind is used and the process is not found.

Since this is a change in API, introduce GODEBUG osfinderr=0 setting
to disable the feature.

Change-Id: I724c6f622f0c99f21a70b864cf7cf2b8836869ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/542699
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
2024-02-21 21:27:03 +00:00
Roland Shoemaker
b18b058816 crypto/x509: gate Policies marshaling with GODEBUG
Use a GODEBUG to choose which certificate policy field to use. If
x509usepolicies=1 is set, use the Policies field, otherwise use the
PolicyIdentifiers field.

Fixes #64248

Change-Id: I3f0b56102e0bac4ebe800497717c61c58ef3f092
Reviewed-on: https://go-review.googlesource.com/c/go/+/546916
Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2023-12-11 23:29:45 +00:00
Michael Pratt
3b8b550a35 doc: document runtimecontentionstacks
For #57071.

Change-Id: Ic1645af57aa589917c67154a5e4ad0b4edd7ba90
Reviewed-on: https://go-review.googlesource.com/c/go/+/547058
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Rhys Hiltner <rhys@justin.tv>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
2023-12-06 21:50:28 +00:00
Michael Anthony Knyszek
c915215af6 runtime: add the disablethp GODEBUG setting
Go 1.21.1 and Go 1.22 have ceased working around an issue with Linux
kernel defaults for transparent huge pages that can result in excessive
memory overheads. (https://bugzilla.kernel.org/show_bug.cgi?id=93111)

Many Linux distributions disable huge pages altogether these days, so
this problem isn't quite as far-reaching as it used to be. Also, the
problem only affects Go programs with very particular memory usage
patterns.

That being said, because the runtime used to actively deal with this
problem (but with some unpredictable behavior), it's preventing users
that don't have a lot of control over their execution environment from
upgrading to Go beyond Go 1.20.

This change adds a GODEBUG to smooth over the transition. The GODEBUG
setting disables transparent huge pages for all heap memory on Linux,
which is much more predictable than restoring the old behavior.

Fixes #64332.

Change-Id: I73b1894337f0f0b1a5a17b90da1221e118e0b145
Reviewed-on: https://go-review.googlesource.com/c/go/+/547475
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2023-12-05 20:14:52 +00:00
Filippo Valsorda
8eecf26e3f crypto/tls: disable ExportKeyingMaterial without EMS
Fixes #43922

Change-Id: Idaad7daa6784807ae3a5e4d944e88e13d01fd0b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/544155
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
2023-11-21 16:29:49 +00:00
Roland Shoemaker
67d555e089 crypto/tls: remove RSA KEX ciphers from the default list
Removes the RSA KEX based ciphers from the default list. This can be
reverted using the tlsrsakex GODEBUG.

Fixes #63413

Change-Id: Id221be3eb2f6c24b91039d380313f0c87d339f98
Reviewed-on: https://go-review.googlesource.com/c/go/+/541517
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
2023-11-14 18:03:29 +00:00
Roland Shoemaker
362bf4fc6d crypto/tls: change default minimum version to 1.2
Updates the default from 1.0 -> 1.2 for servers, bringing it in line
with clients. Add a GODEBUG setting, tls10server, which lets users
revert this change.

Fixes #62459

Change-Id: I2b82f85b1c2d527df1f9afefae4ab30a8f0ceb41
Reviewed-on: https://go-review.googlesource.com/c/go/+/541516
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
2023-11-14 18:03:20 +00:00
Robert Griesemer
30de0b5ef4 go/types, types2: implement Alias proposal (export API)
This CL exports the previously unexported Alias type and
corresponding functions and methods per issue #63223.

Whether Alias types are used or not is controlled by
the gotypesalias setting with the GODEBUG environment
variable. Setting gotypesalias to "1" enables the Alias
types:

	GODEBUG=gotypesalias=1

By default, gotypesalias is not set.

Adjust test cases that enable/disable the use of Alias
types to use -gotypesalias=1 or -gotypesalias=0 rather
than -alias and -alias=false for consistency and to
avoid confusion.

For #63223.

Change-Id: I51308cad3320981afac97dd8c6f6a416fdb0be55
Reviewed-on: https://go-review.googlesource.com/c/go/+/541737
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
2023-11-13 20:18:45 +00:00
Roland Shoemaker
3839447ac3 doc: add missing space in godebug.md
Change-Id: I941b6397e2f09a4abb30c0caf91cc2ff2212a445
Reviewed-on: https://go-review.googlesource.com/c/go/+/536675
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Roland Shoemaker <roland@golang.org>
2023-10-21 03:03:54 +00:00
Jonathan Amsterdam
eb070d7483 net/http: add GODEBUG setting for old ServeMux behavior
Add the GODEBUG setting httpmuxgo121.
When set to "1", ServeMux behaves exactly like it did in Go 1.21.

Implemented by defining a new, unexported type, serveMux121, that
uses the original code.

Updates #61410.

Change-Id: I0a9d0fe2a2286e442d680393e62895ab50683cea
Reviewed-on: https://go-review.googlesource.com/c/go/+/530461
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
2023-10-02 20:28:30 +00:00
Cian Ruane
b3c9db8934 doc: fix broken x509sha1 setting link
The link was missing the /pkg/ prefix.

Fixes #62034.

Change-Id: I96c43f06621e30241e140948129e90f0bd5f8d13
GitHub-Last-Rev: c1e7413f76
GitHub-Pull-Request: golang/go#62040
Reviewed-on: https://go-review.googlesource.com/c/go/+/519575
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
2023-08-15 19:38:07 +00:00
Mauri de Souza Meneguzzo
610d47a584 net/http: disallow empty Content-Length header
The Content-Length must be a valid numeric value, empty values should not be accepted.

See: https://www.rfc-editor.org/rfc/rfc9110.html#name-content-length

Fixes #61679

Change-Id: Icbcd933087fe5e50199b62ff34c58bf92a09d3d4
GitHub-Last-Rev: 932e46b55b
GitHub-Pull-Request: golang/go#61865
Reviewed-on: https://go-review.googlesource.com/c/go/+/517336
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-11 22:04:35 +00:00
Roland Shoemaker
162469b3cf crypto/tls: add GODEBUG to control max RSA key size
Add a new GODEBUG setting, tlsmaxrsasize, which allows controlling the
maximum RSA key size we will accept during TLS handshakes.

Change-Id: I52f060be132014d219f4cd438f59990011a35c96
Reviewed-on: https://go-review.googlesource.com/c/go/+/517495
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-10 20:33:01 +00:00
Matthieu Baerts
6a063b01b0 net: mptcp: force using MPTCP with GODEBUG
When adding MPTCP support to address the proposal #56539, I missed the
GODEBUG setting from Russ Cox's plan:

  I am inclined to say that we add MPTCP as an opt-in for a release or
  two, and then make it opt-out. There should be a GODEBUG setting (...)

See: https://github.com/golang/go/issues/56539#issuecomment-1309294637

Thanks to andrius4669 for having reported this issue to me.

It makes sense to have this GODEBUG setting not to have to modify
applications to use MPTCP (if available). It can then be useful to
estimate the impact in case we want to switch from opt-in to opt-out
later.

The MPTCP E2E test has been modified to make sure we can enable MPTCP
either via the source code like it was already the case before or with
this environment variable:

  GODEBUG=multipathtcp=1

The documentation has been adapted accordingly.

I don't know if it is too late for Go 1.21 but I had to put a version in
the documentation. The modification is small, the risk seems low and
this was supposed to be there from the beginning according to Russ Cox's
specifications. It can also be backported or only be present in the
future v1.22 if it is easier.

Note: I didn't re-open #56539 or open a new one. It is not clear to me
what I should do in this case.

Fixes #56539

Change-Id: I9201f4dc0b99e3643075a34c7032a95528c48fa0
Reviewed-on: https://go-review.googlesource.com/c/go/+/507375
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
2023-07-11 00:36:57 +00:00
Brad Fitzpatrick
9b41418074 cmd/go/internal/cache: use internal/godebug for three GODEBUGs
And register/document them.

Change-Id: If0f1cf3c09230e0f63d03c52e56e51a030468ab2
Reviewed-on: https://go-review.googlesource.com/c/go/+/487655
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
2023-05-24 22:05:27 +00:00
Michael Anthony Knyszek
0d719823af html/template,mime/multipart: document new GODEBUG settings
This change documents the new GODEBUG settings introduced for
html/template and mime/multipart, released with Go 1.19.8 and Go 1.20.3
as part of a security fix.

Updates #59153.
Updates #59234.

Change-Id: I25f4d8245da3301dccccfb44da8ff1a5985392a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/482238
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-04-05 15:42:48 +00:00
Russ Cox
45eded3afd doc: fix template mistake in godebug.md
This file is itself template input, so have to hide the template
in the go command example.

Change-Id: Ifc4eaff35ca8dc2fb479f8e28d64c06b2a9c9d3b
Reviewed-on: https://go-review.googlesource.com/c/go/+/480995
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
2023-04-03 17:06:45 +00:00
Russ Cox
a7fd2fab0e doc: add godebug.md, documenting GODEBUG
Document the changes to GODEBUG implemented as
part of proposal #56986.

Fixes #56986.

Change-Id: I23153a123e23820c5b22db4767620e037bbdd083
Reviewed-on: https://go-review.googlesource.com/c/go/+/462202
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
2023-03-31 16:05:14 +00:00