From e171a36dab67ba4fef49324e644950778fd22eb2 Mon Sep 17 00:00:00 2001
From: Kazuki Sawada <kazuki@6715.jp>
Date: Sun, 30 Jun 2019 21:52:07 +0900
Subject: [PATCH] beacon: use all interface

---
 beacon/beacon.go  |  20 +-------
 beacon/service.go | 125 ++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 122 insertions(+), 23 deletions(-)

diff --git a/beacon/beacon.go b/beacon/beacon.go
index 2ad3480..a804a8d 100644
--- a/beacon/beacon.go
+++ b/beacon/beacon.go
@@ -23,24 +23,8 @@ var (
 )
 
 func StartService(g *echo.Group) {
-	go func() {
-		for {
-			ch := make(chan error)
-			go sendBeacon(ch)
-			logger.Println("Beacon sending goroutine has been started")
-			logger.Printf("Sending beacon failed: %v\n", <-ch)
-			close(ch)
-		}
-	}()
-	go func() {
-		for {
-			ch := make(chan error)
-			go recvBeacon(ch)
-			logger.Println("Beacon receiving goroutine has been started")
-			logger.Printf("Receiving beacon failed: %v\n", <-ch)
-			close(ch)
-		}
-	}()
+	go startSender()
+	go startReceiver()
 
 	g.GET("/nodes", getNodes)
 	g.DELETE("/node", deleteNode)
diff --git a/beacon/service.go b/beacon/service.go
index 6e26b5d..6839271 100644
--- a/beacon/service.go
+++ b/beacon/service.go
@@ -7,8 +7,95 @@ import (
 	"github.com/kaz/flos/messaging"
 )
 
-func sendBeacon(ch chan error) {
-	conn, err := net.Dial("udp", UDP_ADDR)
+func getNIFs() ([]net.Interface, error) {
+	nifs, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+
+	result := []net.Interface{}
+	for _, nif := range nifs {
+		if nif.Flags&net.FlagUp == 0 {
+			continue
+		}
+		if nif.Flags&net.FlagMulticast == 0 {
+			continue
+		}
+		if nif.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+
+		result = append(result, nif)
+	}
+
+	return result, nil
+}
+func getAddrs4(nif net.Interface) ([]net.IP, error) {
+	addrs, err := nif.Addrs()
+	if err != nil {
+		return nil, err
+	}
+
+	result := []net.IP{}
+	for _, addr := range addrs {
+		var ip net.IP = nil
+
+		switch v := addr.(type) {
+		case *net.IPNet:
+			ip = v.IP.To4()
+		case *net.IPAddr:
+			ip = v.IP.To4()
+		}
+
+		if ip != nil {
+			result = append(result, ip)
+		}
+	}
+
+	return result, nil
+}
+
+func startSender() {
+	nifs, err := getNIFs()
+	if err != nil {
+		logger.Printf("failed to get interfaces: %v\n", err)
+		return
+	}
+
+	for _, nif := range nifs {
+		addrs, err := getAddrs4(nif)
+		if err != nil {
+			logger.Printf("failed to get addrs: %v\n", err)
+			continue
+		}
+
+		for _, addr := range addrs {
+			laddr, err := net.ResolveUDPAddr("udp", addr.String()+":11239")
+			if err != nil {
+				logger.Printf("failed to resolve addr: %v\n", err)
+				continue
+			}
+
+			go func(nif net.Interface, laddr net.UDPAddr) {
+				for {
+					ch := make(chan error)
+					go sendBeacon(ch, &laddr)
+					logger.Printf("sending (dev=%s)\n", nif.Name)
+					logger.Printf("send failed (dev=%s): %v\n", nif.Name, <-ch)
+					close(ch)
+				}
+			}(nif, *laddr)
+		}
+	}
+}
+func sendBeacon(ch chan error, laddr *net.UDPAddr) {
+	raddr, err := net.ResolveUDPAddr("udp", UDP_ADDR)
+	if err != nil {
+		ch <- err
+		return
+	}
+
+	conn, err := net.DialUDP("udp", laddr, raddr)
 	if err != nil {
 		ch <- err
 		return
@@ -30,14 +117,42 @@ func sendBeacon(ch chan error) {
 	}
 }
 
-func recvBeacon(ch chan error) {
-	address, err := net.ResolveUDPAddr("udp", UDP_ADDR)
+func startReceiver() {
+	nifs, err := getNIFs()
+	if err != nil {
+		logger.Printf("failed to get interfaces: %v\n", err)
+		return
+	}
+
+	for _, nif := range nifs {
+		addrs, err := getAddrs4(nif)
+		if err != nil {
+			logger.Printf("failed to get addrs: %v\n", err)
+			continue
+		}
+		if len(addrs) == 0 {
+			continue
+		}
+
+		go func(nif net.Interface) {
+			for {
+				ch := make(chan error)
+				go recvBeacon(ch, &nif)
+				logger.Printf("receiving (dev=%s)\n", nif.Name)
+				logger.Printf("receive failed (dev=%s): %v\n", nif.Name, <-ch)
+				close(ch)
+			}
+		}(nif)
+	}
+}
+func recvBeacon(ch chan error, nif *net.Interface) {
+	raddr, err := net.ResolveUDPAddr("udp", UDP_ADDR)
 	if err != nil {
 		ch <- err
 		return
 	}
 
-	listener, err := net.ListenMulticastUDP("udp", nil, address)
+	listener, err := net.ListenMulticastUDP("udp", nif, raddr)
 	if err != nil {
 		ch <- err
 		return