x/mobile: Calling net.Listen fails on Android 11+

[wlynxg]

Go version

go version go1.20.11 darwin/arm64

Output of go env in your module/workspace:

GO111MODULE="on"
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/xxxx/Library/Caches/go-build"
GOENV="/Users/xxxx/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/xxxx/go/pkg/mod"
GONOPROXY="sum.golang.google.cn"
GONOSUMDB="sum.golang.google.cn"
GOOS="darwin"
GOPATH="/Users/xxxx/go"
GOPRIVATE=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.20.11"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/xxxx/Desktop/xxxx/gomobile/go.mod"
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 arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/tl/pjq29cdd6s53760n3zjwwr3c0000gn/T/go-build3441012208=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

package mobile

import (
	"fmt"
	"log"
	"net"
	"net/netip"
	"syscall"

	"github.com/wlynxg/anet"
)

func Greetings(name string) string {
	anet.SetAndroidVersion(14)
	allifaces, err := anet.Interfaces()
	if err != nil {
		return fmt.Sprintf("Error: %s!", err)
	}
	s := ""

	for _, iface := range allifaces {
		s += iface.Name
		addrs, err := anet.InterfaceAddrsByInterface(&iface)
		if err != nil {
			s += fmt.Sprintf("Error: %s", err) + "\n"
		} else {
			s += fmt.Sprintf("%s \n", addrs)
		}

		for _, addr := range addrs {
			parseAddr, err := netip.ParsePrefix(addr.String())
			if err != nil {
				continue
			}

			if parseAddr.Addr().Is4() || parseAddr.Addr().IsMulticast() {
				continue
			}

			addr := fmt.Sprintf("[%s%%%s]:0", parseAddr.Addr().String(), iface.Name)

			_, err = net.Listen("tcp", addr)
			if err != nil {
				log.Printf("listen %s error: %s", addr, err)
			}
		}
	}
	return fmt.Sprintf("Hello, %s!", s)
}

What did you see happen?

listen [fe80::d461:24ff:fe95:d487%wlan0]:0 error: listen tcp [fe80::d461:24ff:fe95:d487%wlan0]:0: bind: invalid argument
listen [fe80::b6ee:d454:7f5b:6fe%rmnet_data1]:0 error: listen tcp [fe80::b6ee:d454:7f5b:6fe%rmnet_data1]:0: bind: invalid argument
listen [fe80::64bd:d9ff:fe5b:92a6%dummy0]:0 error: listen tcp [fe80::64bd:d9ff:fe5b:92a6%dummy0]:0: bind: invalid argument
listen [fe80::e0f1:31ff:fe88:8eb%ifb0]:0 error: listen tcp [fe80::e0f1:31ff:fe88:8eb%ifb0]:0: bind: invalid argument
listen [fe80::6cbb:96ff:fe13:ff68%ifb1]:0 error: listen tcp [fe80::6cbb:96ff:fe13:ff68%ifb1]:0: bind: invalid argument
listen [fe80::b0a1:c3ff:fe6d:c67%ifb2]:0 error: listen tcp [fe80::b0a1:c3ff:fe6d:c67%ifb2]:0: bind: invalid argument
listen [fe80::d41b:7750:b2d1:8fc6%rmnet_data0]:0 error: listen tcp [fe80::d41b:7750:b2d1:8fc6%rmnet_data0]:0: bind: invalid argument
listen [fe80::84bb:a6ff:cd2d:2ff1%rmnet_data3]:0 error: listen tcp [fe80::84bb:a6ff:cd2d:2ff1%rmnet_data3]:0: bind: invalid argument
listen [fe80::5bec:aaaf:e221:d681%rmnet_data4]:0 error: listen tcp [fe80::5bec:aaaf:e221:d681%rmnet_data4]:0: bind: invalid argument

What did you expect to see?

listen success

[gabyhelp]

Similar Issues

• syscall: accept(2) syscall blocked on Android, use accept4(2) instead #45767
• x/mobile: network unreachable on Android 10+ via Network request API #52702
• net: conn.WriteToUDP([]byte("not ok"), addr) #34758
• net.ListenIP: failed when network is ip:50 #49612
• x/mobile: Calling net.InterfaceAddrs() fails on Android SDK 30 #40569
• x/mobile: fix net.Interface() and net.InterfaceAddrs() in Android11 version #61089
• x/mobile: #20722
• net.Dial fails with an ip6 addres - connect: invalid argument #43950
• net: "127.0.0.1:" should be an invalid tcp4 address for ResolveTCPAddr #56144
• net: tips all.bash test failed: interface_test.go:74: route ip+net: invalid network interface name #14706

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

[wlynxg]

The error comes from https://github.com/torvalds/linux/blob/e5b3efbe1ab1793bb49ae07d56d0973267e65112/net/ipv6/af_inet6.c#L364

In my code, I specified the zone name, and go needs to obtain the corresponding relationship between zone name and zone index from zoneCache when parsing.
The data in zoneCache comes from

go/src/net/interface.go

Line 217 in 4f77a83

if ift, err = interfaceTable(0); err != nil {

,
but because there is a problem when go calls interfaceTable on the Android side #40569,
go fails when doing zone name -> zone index mapping, so in order to pass a valid zone id to the socket

I fixed this problem in anet: wlynxg/anet@a8525cb

[Zxilly]

It might be possible to commit these changes to the standard library.

[wlynxg]

It might be possible to commit these changes to the standard library.

This is difficult in some ways because the changes are tied to the Android version.

[vikulin]

The error comes from https://github.com/torvalds/linux/blob/e5b3efbe1ab1793bb49ae07d56d0973267e65112/net/ipv6/af_inet6.c#L364

In my code, I specified the zone name, and go needs to obtain the corresponding relationship between zone name and zone index from zoneCache when parsing. The data in zoneCache comes from

go/src/net/interface.go

Line 217 in 4f77a83

if ift, err = interfaceTable(0); err != nil {

,
but because there is a problem when go calls interfaceTable on the Android side #40569,
go fails when doing zone name -> zone index mapping, so in order to pass a valid zone id to the socket

I fixed this problem in anet: wlynxg/anet@a8525cb

How to get zone id ? I noticed that Android works with scope id for link local addresses not with zone name:
https://developer.android.com/reference/java/net/Inet6Address

[wlynxg]

@vikulin The zone id is actually the index of the interface

go/src/net/interface.go

Line 43 in 9d33956

Index int // positive integer that starts at one, zero is never used

.
In fact, when passing the zone id, you can choose the name

go/src/net/interface.go

Line 263 in 9d33956

index, ok = zoneCache.toIndex[name]

or directly pass the index

go/src/net/interface.go

Line 267 in 9d33956

index, _, _ = dtoi(name)

[vikulin]

@wlynxg I'm not sure that zone id is what I'm looking for. Obviously zone id = 46 is not the index since the Android device never had so many interfaces. Linux devices return interface names - this is where the difference. Code is expecting interface name but getting scope id.

nBytes, rcm, fromAddr, err := m.sock.ReadFrom(bs)
from := fromAddr.(*net.UDPAddr)
log.Infoln(from.String())

returns

[fe80::33d6:4970:9c23:5f7c%46]:9001