cmd/derper, derp/derphttp: move bulk of derp mesh code into derphttp

To be reused in various other tools.

cmd/derper/mesh.go

@@ -9,8 +9,6 @@ import (
 	"fmt"
 	"log"
 	"strings"
-	"sync"
-	"time"
 
 	"tailscale.com/derp"
 	"tailscale.com/derp/derphttp"
@@ -40,107 +38,8 @@ func startMeshWithHost(s *derp.Server, host string) error {
 		return err
 	}
 	c.MeshKey = s.MeshKey()
-	go runMeshClient(s, c, logf)
+	add := func(k key.Public) { s.AddPacketForwarder(k, c) }
+	remove := func(k key.Public) { s.AddPacketForwarder(k, c) }
+	go c.RunWatchConnectionLoop(s.PublicKey(), add, remove)
 	return nil
 }
-
-func runMeshClient(s *derp.Server, c *derphttp.Client, logf logger.Logf) {
-	const retryInterval = 5 * time.Second
-	const statusInterval = 10 * time.Second
-	var (
-		mu              sync.Mutex
-		present         = map[key.Public]bool{}
-		loggedConnected = false
-	)
-	clear := func() {
-		mu.Lock()
-		defer mu.Unlock()
-		if len(present) == 0 {
-			return
-		}
-		logf("reconnected; clearing %d forwarding mappings", len(present))
-		for k := range present {
-			s.RemovePacketForwarder(k, c)
-		}
-		present = map[key.Public]bool{}
-	}
-	lastConnGen := 0
-	lastStatus := time.Now()
-	logConnectedLocked := func() {
-		if loggedConnected {
-			return
-		}
-		logf("connected; %d peers", len(present))
-		loggedConnected = true
-	}
-
-	const logConnectedDelay = 200 * time.Millisecond
-	timer := time.AfterFunc(2*time.Second, func() {
-		mu.Lock()
-		defer mu.Unlock()
-		logConnectedLocked()
-	})
-	defer timer.Stop()
-
-	updatePeer := func(k key.Public, isPresent bool) {
-		if isPresent {
-			s.AddPacketForwarder(k, c)
-		} else {
-			s.RemovePacketForwarder(k, c)
-		}
-
-		mu.Lock()
-		defer mu.Unlock()
-		if isPresent {
-			present[k] = true
-			if !loggedConnected {
-				timer.Reset(logConnectedDelay)
-			}
-		} else {
-			// If we got a peerGone message, that means the initial connection's
-			// flood of peerPresent messages is done, so we can log already:
-			logConnectedLocked()
-			delete(present, k)
-		}
-	}
-
-	for {
-		err := c.WatchConnectionChanges()
-		if err != nil {
-			clear()
-			logf("WatchConnectionChanges: %v", err)
-			time.Sleep(retryInterval)
-			continue
-		}
-
-		if c.ServerPublicKey() == s.PublicKey() {
-			logf("detected self-connect; ignoring host")
-			return
-		}
-		for {
-			m, connGen, err := c.RecvDetail()
-			if err != nil {
-				clear()
-				logf("Recv: %v", err)
-				time.Sleep(retryInterval)
-				break
-			}
-			if connGen != lastConnGen {
-				lastConnGen = connGen
-				clear()
-			}
-			switch m := m.(type) {
-			case derp.PeerPresentMessage:
-				updatePeer(key.Public(m), true)
-			case derp.PeerGoneMessage:
-				updatePeer(key.Public(m), false)
-			default:
-				continue
-			}
-			if now := time.Now(); now.Sub(lastStatus) > statusInterval {
-				lastStatus = now
-				logf("%d peers", len(present))
-			}
-		}
-	}
-}