x/net/route: ParseRIB fail to parse utun up InterfaceMessage

[ruokeqx]

Go version

go version go1.22.6 darwin/amd64

Output of go env in your module/workspace:

GO111MODULE='on'
GOARCH='amd64'
GOBIN=''
GOCACHE='/Users/ruokeqx/Library/Caches/go-build'
GOENV='/Users/ruokeqx/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/ruokeqx/go/pkg/mod'
GOOS='darwin'
GOPATH='/Users/ruokeqx/go'
GOPROXY='https://goproxy.cn,direct'
GOROOT='/usr/local/opt/go1.22'
GOSUMDB='off'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/opt/go1.22/pkg/tool/darwin_amd64'
GOVCS=''
GOVERSION='go1.22.6'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='clang'
CXX='clang++'
CGO_ENABLED='1'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/d8/c7cqtvp515v7tn7xmvv6v2m00000gn/T/go-build3070326303=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

try parse message from AF_ROUTE socket.

unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
msgs, err := route.ParseRIB(route.RIBTypeRoute, data[:n])

What did you see happen?

ParseRIB skip Interface message that indicate utun interface up

// data fetch from AF_ROUTE socket
data := []byte{112, 0, 5, 14, 0, 0, 0, 0, 81, 128, 0, 0, 28, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 220, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 237, 0, 107, 103, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

since no RTA_IFP flag

func (w *wireFormat) parseInterfaceMessage(_ RIBType, b []byte) (Message, error) {
...
	if attrs&syscall.RTA_IFP == 0 {
		return nil, nil
	}
...
}

not sure if it is intended

What did you expect to see?

should return InterfaceMessage with Index and flags?

[gabyhelp]

Related Issues

• x/net/route: ParseRIB fails with errMessageTooShort on an AF_ROUTE message from Darwin #44740 (closed)
• x/net/route: parseInterfaceMessage broken on Dragonfly #46674
• x/net/route: TestFetchAndParseRIB failure on freebsd-386-12_0 builder #37320
• affected/package: syscall on darwin amd64 — macOS 13.0 darwin xnu #56861 (closed)
• x/net/route: TestFetchAndParseRIB fails on IPv4-only or IPv6-only kernel #19298 (closed)
• x/net/route: ParseRIB panics on message from Darwin #70528 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[dmitshur]

CC @neild, @ianlancetaylor.

[ianlancetaylor]

Currently the code ensures that m.Name is set in the returned InterfaceMessage. If we permit a message for which RTA_IFP is not set, then the Name field won't be set. In the standard library's net package, that in turn will mean returning a value of type net.Interface for which the Name field is not set. How should programs handle an unnamed interface? Why is the name not being returned?