Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2026-02-06 18:00:01 +00:00
Code Issues Projects Releases Packages Wiki Activity

net: don't wait 5 seconds to re-read /etc/resolv.conf

Browse source 
If a Go process starts up, finds /etc/resolv.conf empty, then the DHCP
client writes /etc/resolv.conf, the Go program would find itself
broken for up to 5 seconds.

We noticed this during integration tests in ephemeral VMs using
gokrazy that boot into our application.

Change-Id: Ia64c2b5c698a4ee3efc15d8a8f1850c47e531b84
Reviewed-on: https://go-review.googlesource.com/c/go/+/739620
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Brad Fitzpatrick 2026-01-27 09:05:48 -08:00
parent 11d5284363
commit 6de7a19fea
2 changed files with 9 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/net/conf_test.go
View file

@ -396,7 +396,7 @@ func TestConfHostLookupOrder(t *testing.T) {
defer conf.teardown()
for _, tt := range tests {
if !conf.forceUpdateConf(tt.resolv, time.Now().Add(time.Hour)) {
if !conf.forceUpdateConf(tt.resolv, distantFuture) {
t.Errorf("%s: failed to change resolv config", tt.name)
}
for _, ht := range tt.hostTests {

10
src/net/dnsclient_unix.go
View file

@ -382,13 +382,18 @@ func (conf *resolverConfig) init() {
conf.ch = make(chan struct{}, 1)
}
// distantFuture is a sentinel time used for tests to signal that
// resolv.conf should not be rechecked.
var distantFuture = time.Date(3000, 1, 2, 3, 4, 5, 6, time.UTC)
// tryUpdate tries to update conf with the named resolv.conf file.
// The name variable only exists for testing. It is otherwise always
// "/etc/resolv.conf".
func (conf *resolverConfig) tryUpdate(name string) {
conf.initOnce.Do(conf.init)
if conf.dnsConfig.Load().noReload {
dc := conf.dnsConfig.Load()
if dc.noReload {
return
}
@ -399,7 +404,8 @@ func (conf *resolverConfig) tryUpdate(name string) {
defer conf.releaseSema()
now := time.Now()
if conf.lastChecked.After(now.Add(-5 * time.Second)) {
if (len(dc.servers) > 0 && conf.lastChecked.After(now.Add(-5*time.Second))) ||
conf.lastChecked == distantFuture {
return
}
conf.lastChecked = now