feat(discovery): android compatibility

cmd/discover/main.go

@@ -5,25 +5,30 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"time"
 
 	"forge.cadoles.com/cadoles/go-emlid/reach/discovery"
 	"github.com/pkg/errors"
 )
 
 func main() {
-	services, err := discovery.Watch(context.Background())
+	resolver := discovery.NewResolver()
+
+	found, err := resolver.Scan(context.Background(), 1*time.Second)
 	if err != nil {
 		fmt.Printf("[FATAL] %+v", errors.WithStack(err))
 		os.Exit(1)
 	}
 
-	for srv := range services {
+	for srv := range found {
 		data, err := json.MarshalIndent(struct {
-			Addr string `json:"addr"`
+			Addr   string `json:"addr"`
-			Name string `json:"name"`
+			Name   string `json:"name"`
+			Device string `json:"device"`
 		}{
-			Name: srv.Name,
+			Name:   srv.Name,
-			Addr: fmt.Sprintf("%s:%d", srv.AddrV4.String(), srv.Port),
+			Addr:   fmt.Sprintf("%s:%d", srv.AddrV4.String(), srv.Port),
+			Device: srv.Device,
 		}, "", "  ")
 		if err != nil {
 			fmt.Printf("[FATAL] %+v", errors.WithStack(err))

go.mod

@@ -14,8 +14,10 @@ require (
 require (
 	github.com/cenkalti/backoff v2.2.1+incompatible // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
-	github.com/miekg/dns v1.1.27 // indirect
+	github.com/hashicorp/mdns v1.0.5 // indirect
+	github.com/miekg/dns v1.1.41 // indirect
+	github.com/wlynxg/anet v0.0.4-0.20240806025826-e684438fc7c6 // indirect
 	golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550 // indirect
-	golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa // indirect
+	golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1 // indirect
-	golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe // indirect
+	golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44 // indirect
 )

go.sum

@@ -12,12 +12,20 @@ github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aN
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/grandcat/zeroconf v1.0.0 h1:uHhahLBKqwWBV6WZUDAT71044vwOTL+McW0mBJvo6kE=
 github.com/grandcat/zeroconf v1.0.0/go.mod h1:lTKmG1zh86XyCoUeIHSA4FJMBwCJiQmGfcP2PdzytEs=
+github.com/hashicorp/mdns v1.0.5 h1:1M5hW1cunYeoXOqHwEb/GBDDHAFo0Yqb/uz/beC6LbE=
+github.com/hashicorp/mdns v1.0.5/go.mod h1:mtBihi+LeNXGtG8L9dX59gAEa12BDtBQSp4v/YAJqrc=
 github.com/miekg/dns v1.1.27 h1:aEH/kqUzUxGJ/UHcEKdJY+ugH6WEzsEBBSPa8zuy1aM=
 github.com/miekg/dns v1.1.27/go.mod h1:KNUDUusw/aVsxyTYZM1oqvCicbwhgbNgztCETuNZ7xM=
+github.com/miekg/dns v1.1.41 h1:WMszZWJG0XmzbK9FEmzH2TVcqYzFesusSIB41b8KHxY=
+github.com/miekg/dns v1.1.41/go.mod h1:p6aan82bvRIyn+zDIv9xYNUpwa73JcSh9BKwknJysuI=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/wlynxg/anet v0.0.3 h1:PvR53psxFXstc12jelG6f1Lv4MWqE0tI76/hHGjh9rg=
+github.com/wlynxg/anet v0.0.3/go.mod h1:eay5PRQr7fIVAMbTbchTnO9gG65Hg/uYGdc7mguHxoA=
+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=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550 h1:ObdrDkeb4kJdCP557AjRjq69pTHfNouLtWZG7j9rPN8=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
@@ -27,12 +35,25 @@ golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20190923162816-aa69164e4478/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa h1:F+8P+gmewFQYRk6JoLQLwjBCTu3mcIURZfNkVweuRKA=
 golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1 h1:4qWs8cYYH6PoEFy4dfhDFgoMGkwAcETd+MmPdCPMzUc=
+golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1/go.mod h1:9tjilg8BloeKEkVJvy7fQ90B1CfIiPueXVOjqfkSzI8=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 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 v0.0.0-20190924154521-2837fb4f24fe h1:6fAMxZRR6sl1Uq8U61gxU+kPTs2tR8uOySCbBP7BN/M=
 golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe/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 h1:Bli41pIlzTzf3KEY06n+xnzK/BESIg2ze4Pgfh/aI8c=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 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 v0.0.0-20191216052735-49a3e744a425/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

reach/discovery/discovery.go

@@ -1,68 +0,0 @@
-package discovery
-
-import (
-	"context"
-	"net"
-
-	"github.com/grandcat/zeroconf"
-	"github.com/pkg/errors"
-)
-
-// Service is a ReachRS service discovered via MDNS-SD
-type Service struct {
-	Name   string
-	AddrV4 *net.IP
-	Port   int
-}
-
-// Discover tries to discover ReachRS services on the local network via mDNS-SD
-func Discover(ctx context.Context) ([]Service, error) {
-	services := make([]Service, 0)
-
-	watch, err := Watch(ctx)
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-
-	for srv := range watch {
-		services = append(services, srv)
-	}
-
-	return services, nil
-}
-
-// Watch watches ReachRS services on the local network via mDNS-SD
-func Watch(ctx context.Context) (chan Service, error) {
-	out := make(chan Service, 0)
-
-	resolver, err := zeroconf.NewResolver()
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-
-	entries := make(chan *zeroconf.ServiceEntry)
-
-	go func() {
-		defer close(out)
-
-		for e := range entries {
-			var addr *net.IP
-			if len(e.AddrIPv4) > 0 {
-				addr = &e.AddrIPv4[0]
-			}
-			srv := Service{
-				Name:   e.Instance,
-				AddrV4: addr,
-				Port:   e.Port,
-			}
-			out <- srv
-		}
-
-	}()
-
-	if err = resolver.Browse(ctx, "_reach._tcp", ".local", entries); err != nil {
-		return nil, err
-	}
-
-	return out, nil
-}

reach/discovery/resolver.go

@@ -0,0 +1,224 @@
+package discovery
+
+import (
+	"context"
+	"log"
+	"net"
+	"strings"
+	"time"
+
+	"github.com/davecgh/go-spew/spew"
+	"github.com/hashicorp/mdns"
+	"github.com/pkg/errors"
+	"github.com/wlynxg/anet"
+)
+
+const ReachService = "_reach._tcp"
+
+type Resolver struct {
+}
+
+func NewResolver() *Resolver {
+	r := &Resolver{}
+
+	return r
+}
+
+func (r *Resolver) Scan(ctx context.Context, interval time.Duration) (chan Service, error) {
+	found := make(chan Service)
+	entries := make(chan *mdns.ServiceEntry)
+
+	go r.listener(ctx, entries, found)
+
+	ifaces, err := findMulticastInterfaces(ctx)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	for _, iface := range ifaces {
+		err := func(iface net.Interface) error {
+			hasIPv4, hasIPv6, err := retrieveSupportedProtocols(iface)
+			if err != nil {
+				return errors.WithStack(err)
+			}
+
+			if !hasIPv4 && !hasIPv6 {
+				return nil
+			}
+
+			log.Printf("querying iface %s with timeout %v", iface.Name, interval)
+
+			err = r.queryIface(entries, iface, !hasIPv4, !hasIPv6, interval)
+			if err != nil && !(errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled)) {
+				return errors.WithStack(err)
+			}
+
+			go func(iface net.Interface) {
+				defer close(entries)
+
+				if err := r.pollInterface(ctx, entries, iface, interval, !hasIPv4, !hasIPv6); err != nil {
+					log.Printf("[ERROR] %+v", errors.WithStack(err))
+				}
+			}(iface)
+
+			return nil
+		}(iface)
+		if err != nil {
+			return nil, errors.WithStack(err)
+		}
+	}
+
+	return found, nil
+}
+
+func (r *Resolver) queryIface(entries chan *mdns.ServiceEntry, iface net.Interface, disableIPv4, disableIPv6 bool, timeout time.Duration) error {
+	err := mdns.Query(&mdns.QueryParam{
+		Service:     ReachService,
+		Domain:      "local",
+		Timeout:     timeout,
+		Entries:     entries,
+		Interface:   &iface,
+		DisableIPv6: disableIPv6,
+		DisableIPv4: disableIPv4,
+	})
+	if err != nil {
+		return errors.WithStack(err)
+	}
+
+	return nil
+}
+
+func (r *Resolver) pollInterface(ctx context.Context, entries chan *mdns.ServiceEntry, iface net.Interface, interval time.Duration, disableIPv4, disableIPv6 bool) error {
+	ticker := time.NewTicker(interval)
+	for {
+		select {
+		case <-ticker.C:
+			if err := r.queryIface(entries, iface, disableIPv4, disableIPv6, interval); err != nil {
+				if errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled) {
+					continue
+				}
+
+				return errors.WithStack(err)
+			}
+
+		case <-ctx.Done():
+			if err := ctx.Err(); err != nil {
+				return errors.WithStack(err)
+			}
+
+			return nil
+		}
+	}
+}
+
+func (r *Resolver) listener(ctx context.Context, entries chan *mdns.ServiceEntry, found chan Service) {
+	defer close(found)
+
+	for {
+		select {
+		case entry, ok := <-entries:
+			if !ok {
+				return
+			}
+
+			if entry == nil {
+				continue
+			}
+
+			info := decodeTxtRecord(entry.Info)
+
+			srv := Service{
+				Name:   info["local_name"],
+				Device: info["device"],
+				AddrV4: entry.AddrV4,
+				Port:   entry.Port,
+			}
+
+			spew.Sdump(srv)
+
+			found <- srv
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func decodeTxtRecord(txt string) map[string]string {
+	m := make(map[string]string)
+
+	s := strings.Split(txt, "|")
+	for _, v := range s {
+		s := strings.Split(v, "=")
+		if len(s) == 2 {
+			m[s[0]] = s[1]
+		}
+	}
+
+	return m
+}
+
+func isIPv4(ip net.IP) bool {
+	return strings.Count(ip.String(), ":") < 2
+}
+
+func isIPv6(ip net.IP) bool {
+	return strings.Count(ip.String(), ":") >= 2
+}
+
+func findMulticastInterfaces(ctx context.Context) ([]net.Interface, error) {
+	ifaces, err := anet.Interfaces()
+	if err != nil {
+		return nil, nil
+	}
+
+	multicastIfaces := make([]net.Interface, 0)
+
+	for _, iface := range ifaces {
+		if iface.Flags&net.FlagLoopback == net.FlagLoopback {
+			continue
+		}
+
+		if iface.Flags&net.FlagRunning != net.FlagRunning {
+			continue
+		}
+
+		if iface.Flags&net.FlagMulticast != net.FlagMulticast {
+			continue
+		}
+
+		multicastIfaces = append(multicastIfaces, iface)
+	}
+
+	return multicastIfaces, nil
+}
+
+func retrieveSupportedProtocols(iface net.Interface) (bool, bool, error) {
+	adresses, err := anet.InterfaceAddrsByInterface(&iface)
+	if err != nil {
+		return false, false, errors.WithStack(err)
+	}
+
+	hasIPv4 := false
+	hasIPv6 := false
+
+	for _, addr := range adresses {
+		ip, _, err := net.ParseCIDR(addr.String())
+		if err != nil {
+			return false, false, errors.WithStack(err)
+		}
+
+		if isIPv4(ip) {
+			hasIPv4 = true
+		}
+
+		if isIPv6(ip) {
+			hasIPv6 = true
+		}
+
+		if hasIPv4 && hasIPv6 {
+			return hasIPv4, hasIPv6, nil
+		}
+	}
+
+	return hasIPv4, hasIPv6, nil
+}

reach/discovery/resolver_test.go

@@ -7,17 +7,33 @@ import (
 	"time"
 
 	"forge.cadoles.com/cadoles/go-emlid/reach"
+	"github.com/davecgh/go-spew/spew"
+	"github.com/pkg/errors"
 )
 
-func TestDiscovery(t *testing.T) {
+func TestResolver(t *testing.T) {
 	reach.AssertIntegrationTests(t)
 
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 
-	services, err := Discover(ctx)
+	resolver := NewResolver()
+
+	found, err := resolver.Scan(ctx, 500*time.Millisecond)
 	if err != nil {
-		t.Fatal(err)
+		t.Fatalf("%+v", errors.WithStack(err))
+	}
+
+	services := make([]Service, 0)
+OUTER:
+	for {
+		select {
+		case s := <-found:
+			t.Logf("%s", spew.Sdump(s))
+			services = append(services, s)
+		case <-ctx.Done():
+			break OUTER
+		}
 	}
 
 	if g, e := len(services), 1; g < e {

reach/discovery/service.go

@@ -0,0 +1,10 @@
+package discovery
+
+import "net"
+
+type Service struct {
+	Name   string
+	Device string
+	AddrV4 net.IP
+	Port   int
+}