net: ipv6 address parsing allows extra 0

[mpetrunic]

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

go1.19.5 linux/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
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/mpetrunic/.cache/go-build"
GOENV="/home/mpetrunic/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/mpetrunic/.gvm/pkgsets/go1.19.5/global/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/mpetrunic/.gvm/pkgsets/go1.19.5/global"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/mpetrunic/.gvm/gos/go1.19.5"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/mpetrunic/.gvm/gos/go1.19.5/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.19.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build708551667=/tmp/go-build -gno-record-gcc-switches"

What did you do?

When parsing ipv6 address that contains group with more than 4 zeroes, it says it's valid like: 0:0:0:0:000000:ffff:127.1.2.3

What did you expect to see?

I expected nil result.

What did you see instead?

Parsed IP address

[gopherbot]

Change https://go.dev/cl/461605 mentions this issue: net/ip: proper ipv6 address parsing

[seankhliao]

according to rfc 4291 section 2.2
each segment is at most 4 characters.

[mpetrunic]

according to rfc 4291 section 2.2 each segment is at most 4 characters.

Tnx, yeah, I forgot to link rf^^

[seankhliao]

Is there some standard that says more zeros are a valid representation?

[mpetrunic]

Is there some standard that says more zeros are a valid representation?

Don't think so since other languages are limiting to 4 characters:

• node - https://github.com/nodejs/node/blob/main/lib/internal/net.js#L27
• rust - https://github.com/rust-lang/rust/blob/master/library/std/src/net/parser.rs#L182

[seankhliao]

cc @neild @ianlancetaylor