Using mDNS to discover remotes

server/go.mod

@@ -1,3 +1,13 @@
 module musique/server
 
 go 1.19
+
+require github.com/RobertBendun/zeroconf/v2 v2.0.0-20230102034354-649340f2f3b6
+
+require (
+	github.com/miekg/dns v1.1.50 // indirect
+	golang.org/x/mod v0.7.0 // indirect
+	golang.org/x/net v0.4.0 // indirect
+	golang.org/x/sys v0.3.0 // indirect
+	golang.org/x/tools v0.4.0 // indirect
+)

server/go.sum

@@ -1,23 +1,45 @@
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/RobertBendun/zeroconf/v2 v2.0.0-20230102034354-649340f2f3b6 h1:u4H25RhCTadMtZmrvcS5ze8qUOBQ20gAoTJ4qzvp8hs=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/RobertBendun/zeroconf/v2 v2.0.0-20230102034354-649340f2f3b6/go.mod h1:KcFfULkjW8Z9cUQxr3MlM8aZ/SKMB5IRPUiX75nfe88=
-github.com/k0kubun/go-ansi v0.0.0-20180517002512-3bf9e2903213/go.mod h1:vNUNkEQ1e29fT/6vq2aBdFsgNPmy8qMdSay1npru+Sw=
+github.com/miekg/dns v1.1.43/go.mod h1:+evo5L0630/F6ca/Z9+GAqzhjGyn8/c+TBaOyfEl0V4=
-github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/miekg/dns v1.1.50 h1:DQUfb9uc6smULcREF09Uc+/Gd46YWqJd5DbpPE9xkcA=
-github.com/mattn/go-runewidth v0.0.14 h1:+xnbZSEeDbOIg5/mE6JF0w6n9duR1l3/WmbinWVwUuU=
+github.com/miekg/dns v1.1.50/go.mod h1:e3IlAVfNqAllflbibAZEWOXOQ+Ynzk/dDozDxY7XnME=
-github.com/mattn/go-runewidth v0.0.14/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
+github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
-github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db h1:62I3jR2EmQ4l5rM/4FEfDWcRD+abF5XlKShorW5LRoQ=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db/go.mod h1:l0dey0ia/Uv7NcFFVbCLtqEBQbrT4OCwCSKTEv6enCw=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
+golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
-github.com/rivo/uniseg v0.4.3 h1:utMvzDsuh3suAEnhH0RdHmoPbU648o6CvXxTx4SBMOw=
+golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
-github.com/rivo/uniseg v0.4.3/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-github.com/schollz/progressbar v1.0.0 h1:gbyFReLHDkZo8mxy/dLWMr+Mpb1MokGJ1FqCiqacjZM=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-github.com/schollz/progressbar v1.0.0/go.mod h1:/l9I7PC3L3erOuz54ghIRKUEFcosiWfLvJv+Eq26UMs=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-github.com/schollz/progressbar/v3 v3.12.2 h1:yLqqqpQNMxGxHY8uEshRihaHWwa0rf0yb7/Zrpgq2C0=
+golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
-github.com/schollz/progressbar/v3 v3.12.2/go.mod h1:HFJYIYQQJX32UJdyoigUl19xoV6aMwZt6iX/C30RWfg=
+golang.org/x/net v0.0.0-20210423184538-5f58ad60dda6/go.mod h1:OJAsFXCWl8Ukc7SiCT/9KSuxbyM7479/AVlXFRxuMCk=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+golang.org/x/net v0.4.0 h1:Q5QPcMlvfxFTAPV0+07Xz/MpK9NTXu2VDUuy0FeMfaU=
-golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/net v0.4.0/go.mod h1:MBQ8lrhLObU/6UmLb4fmbmk5OcyYmqtbGd/9yIeKjEE=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210303074136-134d130e1a04/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210426080607-c94f62235c83/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
 golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.3.0 h1:qoo4akIqOcDME5bhc/NgxUdovd6BSS2uMsVjB56q1xI=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/term v0.3.0/go.mod h1:q750SLmJuPmVoN1blW3UFBPREJfb1KmY3vwxfr+nFDA=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.6-0.20210726203631-07bc1bf47fb2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/tools v0.4.0 h1:7mTAgkunk3fr4GAloyyCasadO6h9zSsQZbwvcaIciV4=
+golang.org/x/tools v0.4.0/go.mod h1:UE5sM2OK9E/d67R0ANs2xJizIymRP5gJU295PvKXxjQ=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

server/main.go

@@ -7,7 +7,6 @@ import (
 	"log"
 	"musique/server/proto"
 	"musique/server/router"
-	"musique/server/scan"
 	"net"
 	"os"
 	"strings"
@@ -273,28 +272,6 @@ func synchronizeHostsWithRemotes() {
 	}
 }
 
-func registerRemotes() error {
-	networks, err := scan.AvailableNetworks()
-	if err != nil {
-		return err
-	}
-
-	hosts := scan.TCPHosts(networks, []uint16{8081, 8082, 8083, 8084})
-
-	remotes = make(map[string]*Remote)
-	for host := range hosts {
-		if !isThisMyAddress(host.Address) {
-			remotes[host.Address] = &Remote{
-				Address: host.Address,
-				Nick:    host.Nick,
-				Version: host.Version,
-			}
-		}
-	}
-
-	return nil
-}
-
 func main() {
 	var (
 		logsPath string
@@ -320,6 +297,12 @@ func main() {
 		log.Fatalln("Please provide nick via --nick flag")
 	}
 
+	server, err := registerDNS()
+	if err != nil {
+		log.Fatalln("Failed to register DNS:", err)
+	}
+	defer server.Shutdown()
+
 	r := router.Router{}
 	registerRoutes(&r)
 	exit, err := r.Run(baseIP, uint16(port))
@@ -327,7 +310,7 @@ func main() {
 		log.Fatalln(err)
 	}
 
-	if err := registerRemotes(); err != nil {
+	if err := registerRemotes(5); err != nil {
 		log.Fatalln(err)
 	}
 

server/mdns.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"musique/server/proto"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/RobertBendun/zeroconf/v2"
+)
+
+func doHandshake(wg *sync.WaitGroup, service *zeroconf.ServiceEntry, remotes chan<- Remote, timeout time.Duration) {
+	for _, ip := range service.AddrIPv4 {
+		wg.Add(1)
+		go func(ip net.IP) {
+			defer wg.Done()
+			target := fmt.Sprintf("%s:%d", ip, service.Port)
+			if isThisMyAddress(target) {
+				return
+			}
+
+			var hs proto.HandshakeResponse
+			err := proto.CommandTimeout(target, proto.Handshake(), &hs, timeout)
+			if err == nil {
+				log.Println("Received handshake response", target, hs)
+				remotes <- Remote{
+					Address: target,
+					Nick:    hs.Nick,
+					Version: hs.Version,
+				}
+			}
+		}(ip)
+	}
+}
+
+// Register all remotes that cane be found in `waitTime` seconds
+func registerRemotes(waitTime int) error {
+	wg := sync.WaitGroup{}
+	done := make(chan error, 1)
+	incomingRemotes := make(chan Remote, 32)
+	entries := make(chan *zeroconf.ServiceEntry, 12)
+	timeout := time.Second*time.Duration(waitTime)
+
+	wg.Add(1)
+	go func(results <-chan *zeroconf.ServiceEntry) {
+		for entry := range results {
+			log.Println("Found service at", entry.HostName, "at addrs", entry.AddrIPv4)
+			doHandshake(&wg, entry, incomingRemotes, timeout)
+		}
+		wg.Done()
+		done <- nil
+	}(entries)
+
+	go func() {
+		wg.Wait()
+		close(incomingRemotes)
+	}()
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	go func() {
+		err := zeroconf.Browse(ctx, "_musique._tcp", "local", entries)
+		if err != nil {
+			done <- fmt.Errorf("failed to browse: %v", err)
+		}
+		<-ctx.Done()
+	}()
+
+	remotes = make(map[string]*Remote)
+	for remote := range incomingRemotes {
+		remote := remote
+		remotes[remote.Address] = &remote
+	}
+
+	return <-done
+}
+
+type dnsServer interface {
+	Shutdown()
+}
+
+func registerDNS() (dnsServer, error) {
+	return zeroconf.Register("Musique", "_musique._tcp", "local", port, []string{}, nil)
+}

server/musique-bridge.go

@@ -9,6 +9,11 @@ import (
 	"sort"
 )
 
+const (
+	initialWaitingTime         = 3
+	userRequestedWatingingTime = 5
+)
+
 //export ServerInit
 func ServerInit(inputNick string, inputPort int) {
 	logFile, err := os.OpenFile("musique.log", os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0o640)
@@ -27,7 +32,7 @@ func ServerInit(inputNick string, inputPort int) {
 		log.Fatalln(err)
 	}
 
-	if err := registerRemotes(); err != nil {
+	if err := registerRemotes(initialWaitingTime); err != nil {
 		log.Fatalln(err)
 	}
 
@@ -51,7 +56,7 @@ func ServerBeginProtocol() {
 //export Discover
 func Discover() {
 	if len(remotes) == 0 {
-		if err := registerRemotes(); err != nil {
+		if err := registerRemotes(userRequestedWatingingTime); err != nil {
 			log.Println("discover:", err)
 		}
 	}

server/scan/scanner.go

@@ -1,92 +0,0 @@
-package scan
-
-import (
-	"fmt"
-	"log"
-	"musique/server/proto"
-	"net"
-	"sync"
-	"time"
-)
-
-type Network struct {
-	FirstAddress  string
-	MaxHostsCount int
-}
-
-const timeoutTCPHosts = time.Duration(1) * time.Second
-
-func nextIP(ip net.IP) (next net.IP) {
-	// FIXME Proper next IP address in network calculation
-	next = make([]byte, 4)
-	bytes := []byte(ip)
-	bytes = bytes[len(bytes)-4:]
-	next[0], next[1], next[2], next[3] = bytes[0], bytes[1], bytes[2], bytes[3]+1
-	return
-}
-
-// AvailableNetworks returns all IPv4 networks that are available to the host
-func AvailableNetworks() ([]Network, error) {
-	addrs, err := net.InterfaceAddrs()
-	if err != nil {
-		return nil, fmt.Errorf("getting interfaces info: %v", err)
-	}
-
-	networks := []Network{}
-
-	for _, addr := range addrs {
-		_, ipNet, err := net.ParseCIDR(addr.String())
-		if err != nil {
-			continue
-		}
-
-		if ipNet.IP.IsGlobalUnicast() {
-			if ip := ipNet.IP.To4(); ip != nil {
-				// FIXME We assume mask /24. This is a reasonable assumption performance wise
-				// but may lead to inability to recognize some of the host in network
-				networks = append(networks, Network{nextIP(ipNet.IP).String(), 253})
-			}
-		}
-	}
-
-	return networks, nil
-}
-
-type Response struct {
-	proto.HandshakeResponse
-	Address string
-}
-
-// TCPHosts returns all TCP hosts that are in given networks on one of given ports
-func TCPHosts(networks []Network, ports []uint16) <-chan Response {
-	ips := make(chan Response, 256)
-
-	log.Printf("tcphosts: %+v\n", networks)
-
-	wg := sync.WaitGroup{}
-	for _, network := range networks {
-		ip := net.ParseIP(network.FirstAddress)
-		for i := 0; i < network.MaxHostsCount; i++ {
-			for _, port := range ports {
-				wg.Add(1)
-				go func(ip net.IP, port uint16) {
-					defer wg.Done()
-					target := fmt.Sprintf("%s:%d", ip, port)
-					var hs proto.HandshakeResponse
-					err := proto.CommandTimeout(target, proto.Handshake(), &hs, timeoutTCPHosts)
-					if err == nil {
-						ips <- Response{hs, target}
-					}
-				}(ip, port)
-			}
-			ip = nextIP(ip)
-		}
-	}
-
-	go func() {
-		wg.Wait()
-		close(ips)
-	}()
-
-	return ips
-}