captured: use multilisten

cmd/captured/captured.go

@@ -7,14 +7,18 @@ import (
 	"context"
 	"flag"
 	"log"
+	"os"
+	"os/signal"
 	"sync"
+	"syscall"
 
+	"router7/internal/multilisten"
+
+	"github.com/gokrazy/gokrazy"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 	"github.com/google/gopacket/pcapgo"
 
-	"golang.org/x/sync/errgroup"
-
 	_ "net/http/pprof"
 )
 
@@ -79,23 +83,48 @@ func (prb *packetRingBuffer) packetsLocked() []gopacket.Packet {
 	return packets
 }
 
+var sshListeners = multilisten.NewPool()
+
+func updateListeners(srv *server) error {
+	hosts, err := gokrazy.PrivateInterfaceAddrs()
+	if err != nil {
+		return err
+	}
+
+	sshListeners.ListenAndServe(hosts, func(host string) multilisten.Listener {
+		return srv.listenerFor(host)
+	})
+	return nil
+}
+
 func logic() error {
 	prb := newPacketRingBuffer(50000)
+	srv, err := newServer(prb)
+	if err != nil {
+		return err
+	}
+	if err := updateListeners(srv); err != nil {
+		return err
+	}
 
-	var eg errgroup.Group
-	eg.Go(func() error { return listenAndServe(prb) })
-	eg.Go(func() error {
-		packets, err := capturePackets(context.Background())
-		if err != nil {
-			return err
+	go func() {
+		ch := make(chan os.Signal, 1)
+		signal.Notify(ch, syscall.SIGUSR1)
+		for range ch {
+			if err := updateListeners(srv); err != nil {
+				log.Printf("updateListeners: %v", err)
+			}
 		}
-		for packet := range packets {
-			prb.writePacket(packet)
-		}
-		return nil
-	})
+	}()
 
-	return eg.Wait()
+	packets, err := capturePackets(context.Background())
+	if err != nil {
+		return err
+	}
+	for packet := range packets {
+		prb.writePacket(packet)
+	}
+	return nil
 }
 
 func main() {

cmd/captured/ssh.go

@@ -7,7 +7,6 @@ import (
 	"log"
 	"net"
 
-	"github.com/gokrazy/gokrazy"
 	"github.com/google/gopacket/layers"
 	"github.com/google/gopacket/pcapgo"
 	"golang.org/x/crypto/ssh"
@@ -104,7 +103,12 @@ func loadHostKey(path string) (ssh.Signer, error) {
 	return ssh.ParsePrivateKey(b)
 }
 
-func listenAndServe(prb *packetRingBuffer) error {
+type server struct {
+	config *ssh.ServerConfig
+	prb    *packetRingBuffer
+}
+
+func newServer(prb *packetRingBuffer) (*server, error) {
 	config := &ssh.ServerConfig{
 		PublicKeyCallback: func(conn ssh.ConnMetadata, pubKey ssh.PublicKey) (*ssh.Permissions, error) {
 			return nil, nil // authorize all users
@@ -113,53 +117,56 @@ func listenAndServe(prb *packetRingBuffer) error {
 
 	signer, err := loadHostKey(*hostKeyPath)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	config.AddHostKey(signer)
 
-	accept := func(listener net.Listener) {
-		for {
-			conn, err := listener.Accept()
-			if err != nil {
-				log.Printf("accept: %v", err)
-				continue
-			}
+	return &server{
+		config: config,
+		prb:    prb,
+	}, nil
+}
 
-			go func(conn net.Conn) {
-				_, chans, reqs, err := ssh.NewServerConn(conn, config)
-				if err != nil {
-					log.Printf("handshake: %v", err)
-					return
-				}
+func (s *server) listenerFor(host string) *serverListener {
+	return &serverListener{srv: s, host: host}
+}
 
-				// discard all out of band requests
-				go ssh.DiscardRequests(reqs)
+type serverListener struct {
+	srv  *server
+	host string
+	ln   net.Listener
+}
 
-				for newChannel := range chans {
-					handleChannel(newChannel, prb)
-				}
-			}(conn)
-		}
-	}
-
-	addrs, err := gokrazy.PrivateInterfaceAddrs()
+func (sl *serverListener) ListenAndServe() error {
+	ln, err := net.Listen("tcp", net.JoinHostPort(sl.host, "5022"))
 	if err != nil {
 		return err
 	}
-
-	for _, addr := range addrs {
-		hostport := net.JoinHostPort(addr, "5022")
-		listener, err := net.Listen("tcp", hostport)
+	sl.ln = ln
+	for {
+		conn, err := ln.Accept()
 		if err != nil {
 			return err
 		}
-		fmt.Printf("listening on %s\n", hostport)
-		go accept(listener)
+
+		go func(conn net.Conn) {
+			_, chans, reqs, err := ssh.NewServerConn(conn, sl.srv.config)
+			if err != nil {
+				log.Printf("handshake: %v", err)
+				return
+			}
+
+			// discard all out of band requests
+			go ssh.DiscardRequests(reqs)
+
+			for newChannel := range chans {
+				handleChannel(newChannel, sl.srv.prb)
+			}
+		}(conn)
 	}
-
-	fmt.Printf("host key fingerprint: %s\n", ssh.FingerprintSHA256(signer.PublicKey()))
-
-	select {}
-
 	return nil
 }
+
+func (sl *serverListener) Close() error {
+	return sl.ln.Close()
+}

internal/netconfig/netconfig.go

@@ -600,10 +600,11 @@ func Apply(dir, root string) error {
 	}
 
 	for _, process := range []string{
-		"dyndns",  // depends on the public IPv4 address
-		"dnsd",    // listens on private IPv4/IPv6
-		"diagd",   // listens on private IPv4/IPv6
-		"backupd", // listens on private IPv4/IPv6
+		"dyndns",   // depends on the public IPv4 address
+		"dnsd",     // listens on private IPv4/IPv6
+		"diagd",    // listens on private IPv4/IPv6
+		"backupd",  // listens on private IPv4/IPv6
+		"captured", // listens on private IPv4/IPv6
 	} {
 		if err := notify.Process("/user/"+process, syscall.SIGUSR1); err != nil {
 			log.Printf("notifying %s: %v", process, err)