From 947b6ad7aa93eb2174bf16ddac844c7afaf2677d Mon Sep 17 00:00:00 2001
From: Sergey Bobrenok <bobrofon@gmail.com>
Date: Fri, 16 Aug 2024 20:28:57 +0300
Subject: [PATCH] Restore local peer discovery mechanism on Android 11+ (#1158)

This solution is bases on https://github.com/wlynxg/anet project.
`github.com/wlynxg/anet` is a partial alternative implementation of the
`golang.org/x/net` module. The goal of `anet` module is to provide
workarounds of the issues https://github.com/golang/go/issues/40569 and
https://github.com/golang/go/issues/68082 on Android 11+.

Tested on AOSP 13.

Resolves: #1149
---
 go.mod                     |  1 +
 go.sum                     |  2 ++
 src/multicast/multicast.go | 10 +++++++---
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 5ff4479a..52b699d8 100644
--- a/go.mod
+++ b/go.mod
@@ -12,6 +12,7 @@ require (
 	github.com/kardianos/minwinsvc v1.0.2
 	github.com/quic-go/quic-go v0.45.1
 	github.com/vishvananda/netlink v1.1.0
+	github.com/wlynxg/anet v0.0.4-0.20240806025826-e684438fc7c6
 	golang.org/x/crypto v0.25.0
 	golang.org/x/mobile v0.0.0-20240716161057-1ad2df20a8b6
 	golang.org/x/net v0.27.0
diff --git a/go.sum b/go.sum
index 1cb8f5b8..a3c2888e 100644
--- a/go.sum
+++ b/go.sum
@@ -70,6 +70,8 @@ github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYp
 github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df/go.mod h1:JP3t17pCcGlemwknint6hfoeCVQrEMVwxRLRjXpq+BU=
 github.com/vishvananda/netns v0.0.0-20210104183010-2eb08e3e575f h1:p4VB7kIXpOQvVn1ZaTIVp+3vuYAXFe3OJEvjbUYJLaA=
 github.com/vishvananda/netns v0.0.0-20210104183010-2eb08e3e575f/go.mod h1:DD4vA1DwXk04H54A1oHXtwZmA0grkVMdPxx/VGLCah0=
+github.com/wlynxg/anet v0.0.4-0.20240806025826-e684438fc7c6 h1:c/wkXIJvpg2oot7iFqPESTBAO9UvhWTBnW97y9aPgyU=
+github.com/wlynxg/anet v0.0.4-0.20240806025826-e684438fc7c6/go.mod h1:eay5PRQr7fIVAMbTbchTnO9gG65Hg/uYGdc7mguHxoA=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 go.uber.org/mock v0.4.0 h1:VcM4ZOtdbR4f6VXfiOpwpVJDL6lCReaZ6mw31wqh7KU=
 go.uber.org/mock v0.4.0/go.mod h1:a6FSlNadKUHUa9IP5Vyt1zh4fC7uAwxMutEAscFbkZc=
diff --git a/src/multicast/multicast.go b/src/multicast/multicast.go
index 0fe72dc7..902d7729 100644
--- a/src/multicast/multicast.go
+++ b/src/multicast/multicast.go
@@ -14,6 +14,7 @@ import (
 
 	"github.com/Arceliar/phony"
 	"github.com/gologme/log"
+	"github.com/wlynxg/anet"
 
 	"github.com/yggdrasil-network/yggdrasil-go/src/core"
 	"golang.org/x/crypto/blake2b"
@@ -148,7 +149,8 @@ func (m *Multicast) _stop() error {
 func (m *Multicast) _updateInterfaces() {
 	interfaces := m._getAllowedInterfaces()
 	for name, info := range interfaces {
-		addrs, err := info.iface.Addrs()
+		// 'anet' package is used here to avoid https://github.com/golang/go/issues/40569
+		addrs, err := anet.InterfaceAddrsByInterface(&info.iface)
 		if err != nil {
 			m.log.Warnf("Failed up get addresses for interface %s: %s", name, err)
 			delete(interfaces, name)
@@ -156,6 +158,7 @@ func (m *Multicast) _updateInterfaces() {
 		}
 		info.addrs = addrs
 		interfaces[name] = info
+		m.log.Debugf("Discovered addresses for interface %s: %s", name, addrs)
 	}
 	m._interfaces = interfaces
 }
@@ -174,10 +177,11 @@ func (m *Multicast) Interfaces() map[string]net.Interface {
 func (m *Multicast) _getAllowedInterfaces() map[string]*interfaceInfo {
 	interfaces := make(map[string]*interfaceInfo)
 	// Ask the system for network interfaces
-	allifaces, err := net.Interfaces()
+	// 'anet' package is used here to avoid https://github.com/golang/go/issues/40569
+	allifaces, err := anet.Interfaces()
 	if err != nil {
 		// Don't panic, since this may be from e.g. too many open files (from too much connection spam)
-		// TODO? log something
+		m.log.Debugf("Failed to get interfaces: %s", err)
 		return nil
 	}
 	// Work out which interfaces to announce on