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net: go resolver on Windows takes disabled interfaces' DNS nameservers #56160

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zhzy0077 opened this issue Oct 11, 2022 · 3 comments
Closed

net: go resolver on Windows takes disabled interfaces' DNS nameservers #56160

zhzy0077 opened this issue Oct 11, 2022 · 3 comments
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NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. OS-Windows
Milestone
Unplanned

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@zhzy0077
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What version of Go are you using (go version)?

$ go version
go version go1.19.2 windows/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\xxx\AppData\Local\go-build
set GOENV=C:\Users\xxx\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\xxx\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\xxx\go
set GOPRIVATE=
set GOPROXY=https://goproxy.cn,direct
set GOROOT=C:\Program Files\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.19.2
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=C:\Users\xxx\Code\gosample\go.mod
set GOWORK=
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=C:\Users\xxx\AppData\Local\Temp\go-build106667779=/tmp/go-build -gno-record-gcc-switches

What did you do?

  1. Create a network interface like VPN or so, but do not connect to it, i.e. disable the interface.
  2. Run code below:
package main

import (
	"context"
	"fmt"
	"net"
)

func main() {
	c := context.TODO()

	r := &net.Resolver{
		PreferGo: true,
	}

	fmt.Println(r.LookupNetIP(c, "ip", "www.google.com"))
}

What did you expect to see?

Go uses the go resolver and picks the active interfaces nameserver.

What did you see instead?

Go starts with the nameserver configured at disabled network interface.

It is because the code here doesn't filter network interfaces by its operating status as per the docs
zhzy0077 added a commit to zhzy0077/go that referenced this issue Oct 11, 2022
@zhzy0077
net: filter disabled interfaces as nameservers on Windows
0a0c9b3 
Currently the code add nameservers from all network interfaces to the nameservers list. But nameservers on disabled interfaces are not accessible and should not be considered as a nameserver candidate.

Fixes golang#56160
@zhzy0077 zhzy0077 mentioned this issue Oct 11, 2022
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@gopherbot
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Change https://go.dev/cl/442375 mentions this issue: net: The Go DNS resolver on Windows should filter disabled interfaces

@seankhliao seankhliao added OS-Windows NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels Oct 12, 2022
@seankhliao
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cc @ianlancetaylor @neild

@seankhliao seankhliao changed the title net: The Go resolver on Windows takes disabled interfaces' DNS nameservers net: go resolver on Windows takes disabled interfaces' DNS nameservers Nov 1, 2022
@seankhliao seankhliao added this to the Unplanned milestone Nov 19, 2022
@gopherbot
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Change https://go.dev/cl/500375 mentions this issue: net: filter disabled interfaces in Windows DNS client

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net: The Go DNS resolver on Windows should filter disabled interfaces zhzy0077/go
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@gopherbot @zhzy0077 @seankhliao