all: support empty HTTP config

We don't really need an HTTP server when running syz-manager during kernel
image testing and when running syz-diff automatically.

Don't require the config to be set and don't start the HTTP server in
this case.

pkg/manager/http.go

@@ -68,6 +68,9 @@ type HTTPServer struct {
 }
 
 func (serv *HTTPServer) Serve() {
+	if serv.Cfg.HTTP == "" {
+		log.Fatalf("starting a disabled HTTP server")
+	}
 	if serv.Pool != nil {
 		serv.Pools = map[string]*vm.Dispatcher{"": serv.Pool}
 	}

pkg/mgrconfig/load.go

@@ -145,7 +145,6 @@ func Complete(cfg *Config) error {
 		cfg.TargetArch, "target",
 		cfg.Workdir, "workdir",
 		cfg.Syzkaller, "syzkaller",
-		cfg.HTTP, "http",
 		cfg.Type, "type",
 		cfg.SSHUser, "ssh_user",
 	); err != nil {

syz-ci/manager.go

@@ -591,8 +591,7 @@ func (mgr *Manager) createTestConfig(imageDir string, info *BuildInfo) (*mgrconf
 	*mgrcfg = *mgr.managercfg
 	mgrcfg.Name += "-test"
 	mgrcfg.Tag = info.KernelCommit
-	// Use designated ports not to collide with the ports of other managers.
-	mgrcfg.HTTP = fmt.Sprintf("localhost:%v", mgr.mgrcfg.testHTTPPort)
+	mgrcfg.HTTP = "" // Don't start the HTTP server.
 	// For GCE VMs, we need to bind to a real networking interface, so no localhost.
 	mgrcfg.RPC = fmt.Sprintf(":%v", mgr.mgrcfg.testRPCPort)
 	mgrcfg.Workdir = filepath.Join(imageDir, "workdir")

syz-ci/syz-ci.go

@@ -225,8 +225,7 @@ type ManagerConfig struct {
 	managercfg       *mgrconfig.Config
 
 	// Auto-assigned ports used by test instances.
-	testHTTPPort int
-	testRPCPort  int
+	testRPCPort int
 }
 
 type ManagerJobs struct {
@@ -461,8 +460,6 @@ func loadManagerConfig(cfg *Config, mgr *ManagerConfig) error {
 		managercfg.RPC = fmt.Sprintf(":%v", cfg.RPCPort)
 		cfg.RPCPort++
 	}
-	mgr.testHTTPPort = cfg.ManagerPort
-	cfg.ManagerPort++
 	mgr.testRPCPort = cfg.RPCPort
 	cfg.RPCPort++
 	// Note: we don't change Compiler/Ccache because it may be just "gcc" referring

syz-manager/manager.go

@@ -282,6 +282,7 @@ func RunManager(mode *Mode, cfg *mgrconfig.Config) {
 		mgr.cfg.Procs = 1
 	}
 	mgr.http = &manager.HTTPServer{
+		// Note that if cfg.HTTP == "", we don't start the server.
 		Cfg:        cfg,
 		StartTime:  time.Now(),
 		CrashStore: mgr.crashStore,
@@ -355,7 +356,9 @@ func RunManager(mode *Mode, cfg *mgrconfig.Config) {
 	mgr.http.TogglePause = mgr.pool.TogglePause
 
 	ctx := vm.ShutdownCtx()
-	go mgr.http.Serve()
+	if mgr.cfg.HTTP != "" {
+		go mgr.http.Serve()
+	}
 	go mgr.trackUsedFiles()
 	go mgr.processFuzzingResults(ctx)
 	mgr.pool.Loop(ctx)
@@ -1437,6 +1440,9 @@ func (mgr *Manager) CoverageFilter(modules []*vminfo.KernelModule) []uint64 {
 }
 
 func publicWebAddr(addr string) string {
+	if addr == "" {
+		return ""
+	}
 	_, port, err := net.SplitHostPort(addr)
 	if err == nil && port != "" {
 		if host, err := os.Hostname(); err == nil {

tools/syz-diff/diff.go

@@ -87,18 +87,19 @@ func main() {
 		new:           new,
 		store:         store,
 		reproAttempts: map[string]int{},
-		http: &manager.HTTPServer{
+	}
+	if newCfg.HTTP != "" {
+		diffCtx.http = &manager.HTTPServer{
 			Cfg:       newCfg,
 			StartTime: time.Now(),
 			DiffStore: store,
-		},
-	}
-	diffCtx.http.Pools = map[string]*vm.Dispatcher{
-		new.name:  new.pool,
-		base.name: base.pool,
+			Pools: map[string]*vm.Dispatcher{
+				new.name:  new.pool,
+				base.name: base.pool,
+			},
+		}
+		new.http = diffCtx.http
 	}
-	new.http = diffCtx.http
-
 	diffCtx.Loop(ctx)
 }
 
@@ -116,7 +117,10 @@ type diffContext struct {
 
 func (dc *diffContext) Loop(ctx context.Context) {
 	reproLoop := manager.NewReproLoop(dc, dc.new.pool.Total()-dc.new.cfg.FuzzingVMs, false)
-	dc.http.ReproLoop = reproLoop
+	if dc.http != nil {
+		dc.http.ReproLoop = reproLoop
+		go dc.http.Serve()
+	}
 	go func() {
 		// Let both base and patched instances somewhat progress in fuzzing before we take
 		// VMs away for bug reproduction.
@@ -128,10 +132,8 @@ func (dc *diffContext) Loop(ctx context.Context) {
 
 	go dc.base.Loop()
 	go dc.new.Loop()
-	go dc.http.Serve()
 
 	runner := &reproRunner{done: make(chan reproRunnerResult, 2), kernel: dc.base}
-
 	rareStat := time.NewTicker(5 * time.Minute)
 	for {
 		select {