feat(wasm): expose taildrive WebDAV server and listDrivePeers via JS bridge

Add drive.go (build tag !ts_omit_drive): implements drive.FileSystemForRemote
with a JS-backed handler. Streams request bodies chunk-by-chunk via
readBodyChunk() and response bodies via write()/end() callbacks so no
full-body buffering occurs regardless of file size. The handler is nil-safe:
returns 404 until setDriveHandler() is called from JS.

Add drive_stub.go (build tag ts_omit_drive): no-op stubs for stripped builds.

Add peer.go: extract buildPeerAPIURL helper (previously inline in run()).

Modify wasm_js.go: call initDriveForRemote before NewLocalBackend (SubSystem
is set-once), expose setDriveHandler and listDrivePeers via wireDriveJS,
and refactor the inline peerAPI URL logic to use buildPeerAPIURL.

listDrivePeers mirrors native driveRemotesFromPeers: returns empty if
DriveAccessEnabled() is false, then filters peers by PeerCapabilityTaildriveSharer
using lb.PeerCaps(addr).HasCapability() (the live ACL-derived cap map).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cmd/tsconnect/wasm/drive.go

@@ -0,0 +1,301 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !ts_omit_drive
+
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"syscall/js"
+
+	"tailscale.com/drive"
+	"tailscale.com/tailcfg"
+	"tailscale.com/tsd"
+)
+
+// Compile-time check that jsFileSystemForRemote implements drive.FileSystemForRemote.
+var _ drive.FileSystemForRemote = (*jsFileSystemForRemote)(nil)
+
+// jsFileSystemForRemote implements drive.FileSystemForRemote by bridging
+// incoming WebDAV requests to a JS handler function. Auth and permission
+// parsing are handled upstream by handleServeDrive before this is called.
+type jsFileSystemForRemote struct {
+	mu sync.RWMutex
+	fn js.Value
+}
+
+func (fs *jsFileSystemForRemote) setHandler(fn js.Value) {
+	fs.mu.Lock()
+	fs.fn = fn
+	fs.mu.Unlock()
+}
+
+// SetFileServerAddr is a no-op: the JS handler owns its own storage.
+func (fs *jsFileSystemForRemote) SetFileServerAddr(_ string) {}
+
+// SetShares is a no-op: the JS handler controls which shares it exposes.
+func (fs *jsFileSystemForRemote) SetShares(_ []*drive.Share) {}
+
+// Close is a no-op.
+func (fs *jsFileSystemForRemote) Close() error { return nil }
+
+// ServeHTTPWithPerms handles a WebDAV request by bridging it to the JS handler.
+// It streams the request body to JS via readBodyChunk() and streams the
+// response body back via write()/end() callbacks, so no full-body buffering
+// occurs regardless of file size.
+//
+// The call blocks until JS calls end() (or a write error occurs).
+func (fs *jsFileSystemForRemote) ServeHTTPWithPerms(
+	perms drive.Permissions, w http.ResponseWriter, r *http.Request,
+) {
+	fs.mu.RLock()
+	fn := fs.fn
+	fs.mu.RUnlock()
+
+	if fn.IsUndefined() || fn.IsNull() {
+		http.NotFound(w, r)
+		return
+	}
+
+	// readBodyChunk is exposed to JS as req.readBodyChunk().
+	// Each call returns a Promise<Uint8Array|null>: null signals EOF.
+	readBodyChunk := js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		return makePromise(func() (any, error) {
+			buf := make([]byte, 65536)
+			n, err := r.Body.Read(buf)
+			if n > 0 {
+				arr := js.Global().Get("Uint8Array").New(n)
+				js.CopyBytesToJS(arr, buf[:n])
+				return arr, nil
+			}
+			if errors.Is(err, io.EOF) {
+				return js.Null(), nil
+			}
+			return nil, err
+		})
+	})
+
+	// doneCh receives nil when JS calls end(), or a write error if Write fails.
+	doneCh := make(chan error, 1)
+
+	// writeHead sets response headers and status code. Must be called before write().
+	writeHead := js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) < 1 {
+			return nil
+		}
+		status := args[0].Int()
+		if len(args) > 1 && !args[1].IsUndefined() && !args[1].IsNull() {
+			for k, vs := range jsHeadersToGo(args[1]) {
+				for _, v := range vs {
+					w.Header().Add(k, v)
+				}
+			}
+		}
+		w.WriteHeader(status)
+		return nil
+	})
+
+	// write streams a single response body chunk to the client.
+	write := js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) < 1 {
+			return nil
+		}
+		data := args[0]
+		buf := make([]byte, data.Get("length").Int())
+		js.CopyBytesToGo(buf, data)
+		if _, werr := w.Write(buf); werr != nil {
+			select {
+			case doneCh <- werr:
+			default:
+			}
+			return nil
+		}
+		if f, ok := w.(http.Flusher); ok {
+			f.Flush()
+		}
+		return nil
+	})
+
+	// end signals that the response is complete.
+	end := js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		select {
+		case doneCh <- nil:
+		default:
+		}
+		return nil
+	})
+
+	defer func() {
+		readBodyChunk.Release()
+		writeHead.Release()
+		write.Release()
+		end.Release()
+	}()
+
+	jsReq := map[string]any{
+		"method":        r.Method,
+		"path":          r.URL.Path,
+		"rawQuery":      r.URL.RawQuery,
+		"headers":       goHeadersToJS(r.Header),
+		"readBodyChunk": readBodyChunk,
+	}
+	jsRes := map[string]any{
+		"writeHead": writeHead,
+		"write":     write,
+		"end":       end,
+	}
+
+	fn.Invoke(jsReq, jsRes, drivePermsToJS(perms))
+
+	// Block this goroutine until JS calls end() or a write error occurs.
+	// The Go WASM scheduler yields back to JS while we wait.
+	<-doneCh
+}
+
+// drivePermsToJS converts drive.Permissions to a plain JS-friendly object.
+// Each share name maps to a numeric permission: 0=none, 1=read-only, 2=read-write.
+// The wildcard share name "*" is included if present.
+func drivePermsToJS(p drive.Permissions) map[string]any {
+	result := make(map[string]any, len(p))
+	for name, perm := range p {
+		result[name] = int(perm)
+	}
+	return result
+}
+
+// goHeadersToJS converts an http.Header to a map[string]any suitable for JS.
+// Single-value headers become a string; multi-value headers become a []any.
+func goHeadersToJS(h http.Header) map[string]any {
+	result := make(map[string]any, len(h))
+	for k, vs := range h {
+		if len(vs) == 1 {
+			result[k] = vs[0]
+		} else {
+			arr := make([]any, len(vs))
+			for i, v := range vs {
+				arr[i] = v
+			}
+			result[k] = arr
+		}
+	}
+	return result
+}
+
+// jsHeadersToGo parses a JS headers object into an http.Header map.
+// Values may be a string or an array of strings.
+func jsHeadersToGo(jsHeaders js.Value) http.Header {
+	h := make(http.Header)
+	keys := js.Global().Get("Object").Call("keys", jsHeaders)
+	for i := 0; i < keys.Length(); i++ {
+		key := keys.Index(i).String()
+		val := jsHeaders.Get(key)
+		switch val.Type() {
+		case js.TypeString:
+			h.Set(key, val.String())
+		case js.TypeObject:
+			if val.InstanceOf(js.Global().Get("Array")) {
+				for j := 0; j < val.Length(); j++ {
+					h.Add(key, val.Index(j).String())
+				}
+			}
+		}
+	}
+	return h
+}
+
+// initDriveForRemote creates the JS-backed FileSystemForRemote and registers
+// it with sys. Must be called before NewLocalBackend (SubSystem is set-once).
+func initDriveForRemote(sys *tsd.System) *jsFileSystemForRemote {
+	driveFS := &jsFileSystemForRemote{}
+	sys.Set(driveFS)
+	return driveFS
+}
+
+// wireDriveJS adds drive-related methods to the IPN JS methods map.
+// driveFS must be the value returned by initDriveForRemote.
+func wireDriveJS(i *jsIPN, driveFS *jsFileSystemForRemote, m map[string]any) {
+	m["setDriveHandler"] = js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) < 1 {
+			return nil
+		}
+		driveFS.setHandler(args[0])
+		return nil
+	})
+
+	m["listDrivePeers"] = js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		return i.listDrivePeers()
+	})
+}
+
+type jsDrivePeer struct {
+	Name         string  `json:"name"`
+	PeerAPIURL   string  `json:"peerAPIURL"`
+	StableNodeID string  `json:"stableNodeID"`
+	Online       *bool   `json:"online,omitempty"`
+}
+
+// listDrivePeers returns a JSON array of peers that carry
+// PeerCapabilityTaildriveSharer. Returns an empty array if the local node
+// does not have drive:access in its ACL (DriveAccessEnabled). This mirrors
+// the filtering in LocalBackend.driveRemotesFromPeers.
+func (i *jsIPN) listDrivePeers() js.Value {
+	return makePromise(func() (any, error) {
+		if !i.lb.DriveAccessEnabled() {
+			return "[]", nil
+		}
+
+		nm := i.lb.NetMap()
+		if nm == nil {
+			return nil, errors.New("listDrivePeers: no network map available")
+		}
+
+		var selfHave4, selfHave6 bool
+		for _, a := range nm.GetAddresses().All() {
+			if !a.IsSingleIP() {
+				continue
+			}
+			if a.Addr().Is4() {
+				selfHave4 = true
+			} else if a.Addr().Is6() {
+				selfHave6 = true
+			}
+		}
+
+		peers := make([]jsDrivePeer, 0)
+		for _, p := range nm.Peers {
+			// Check PeerCapabilityTaildriveSharer via the live PeerCaps map
+			// (derived from ACL rules), mirroring driveRemotesFromPeers.
+			hasCap := false
+			for _, a := range p.Addresses().All() {
+				if a.IsSingleIP() && i.lb.PeerCaps(a.Addr()).HasCapability(tailcfg.PeerCapabilityTaildriveSharer) {
+					hasCap = true
+					break
+				}
+			}
+			if !hasCap {
+				continue
+			}
+			peerURL := buildPeerAPIURL(p, selfHave4, selfHave6)
+			online := p.Online().Clone()
+			peers = append(peers, jsDrivePeer{
+				Name:         p.DisplayName(false),
+				PeerAPIURL:   peerURL,
+				StableNodeID: string(p.StableID()),
+				Online:       online,
+			})
+		}
+
+		b, err := json.Marshal(peers)
+		if err != nil {
+			return nil, fmt.Errorf("listDrivePeers: marshal: %w", err)
+		}
+		return string(b), nil
+	})
+}
+

cmd/tsconnect/wasm/drive_stub.go

@@ -0,0 +1,27 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build ts_omit_drive
+
+package main
+
+import (
+	"syscall/js"
+
+	"tailscale.com/tsd"
+)
+
+type jsFileSystemForRemote struct{}
+
+// initDriveForRemote is a no-op when the drive feature is omitted.
+func initDriveForRemote(_ *tsd.System) *jsFileSystemForRemote { return nil }
+
+// wireDriveJS is a no-op when the drive feature is omitted.
+func wireDriveJS(_ *jsIPN, _ *jsFileSystemForRemote, _ map[string]any) {}
+
+// listDrivePeers returns an empty list when the drive feature is omitted.
+func (i *jsIPN) listDrivePeers() js.Value {
+	return makePromise(func() (any, error) {
+		return "[]", nil
+	})
+}

cmd/tsconnect/wasm/peer.go

@@ -0,0 +1,41 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+package main
+
+import (
+	"fmt"
+	"net/netip"
+
+	"tailscale.com/tailcfg"
+)
+
+// buildPeerAPIURL returns the HTTP base URL for a peer's peerAPI server,
+// selecting IPv4 when available and falling back to IPv6. Returns an empty
+// string if the peer advertises no reachable peerAPI port.
+func buildPeerAPIURL(p tailcfg.NodeView, selfHave4, selfHave6 bool) string {
+	var pp4, pp6 uint16
+	for _, s := range p.Hostinfo().Services().All() {
+		switch s.Proto {
+		case tailcfg.PeerAPI4:
+			pp4 = s.Port
+		case tailcfg.PeerAPI6:
+			pp6 = s.Port
+		}
+	}
+	if selfHave4 && pp4 != 0 {
+		for _, a := range p.Addresses().All() {
+			if a.IsSingleIP() && a.Addr().Is4() {
+				return fmt.Sprintf("http://%v", netip.AddrPortFrom(a.Addr(), pp4))
+			}
+		}
+	}
+	if selfHave6 && pp6 != 0 {
+		for _, a := range p.Addresses().All() {
+			if a.IsSingleIP() && a.Addr().Is6() {
+				return fmt.Sprintf("http://%v", netip.AddrPortFrom(a.Addr(), pp6))
+			}
+		}
+	}
+	return ""
+}

cmd/tsconnect/wasm/taildrop.go

@@ -9,7 +9,6 @@
 package main
 
 import (
-	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -81,9 +80,11 @@ func (i *jsIPN) listFileTargets() js.Value {
 	})
 }
 
-// sendFile sends data as filename to the peer identified by stableNodeID,
+// sendFile sends stream as filename to the peer identified by stableNodeID,
 // reporting progress via notifyOutgoingFiles callbacks roughly once per second.
-func (i *jsIPN) sendFile(stableNodeID, filename string, data js.Value) js.Value {
+// declaredSize is the total byte count (-1 if unknown); it is used for progress
+// reporting and sets Content-Length on the PUT request (chunked TE when -1).
+func (i *jsIPN) sendFile(stableNodeID, filename string, stream js.Value, declaredSize int) js.Value {
 	return makePromise(func() (any, error) {
 		ext, err := i.taildropExt()
 		if err != nil {
@@ -107,14 +108,15 @@ func (i *jsIPN) sendFile(stableNodeID, filename string, data js.Value) js.Value
 		if err != nil {
 			return nil, fmt.Errorf("bogus peer URL: %w", err)
 		}
-		b := make([]byte, data.Get("byteLength").Int())
+
-		js.CopyBytesToGo(b, data)
+		reader := stream.Call("getReader")
+		body := &jsStreamReader{reader: reader}
 
 		outgoing := &ipn.OutgoingFile{
 			ID:           rands.HexString(30),
 			PeerID:       tailcfg.StableNodeID(stableNodeID),
 			Name:         filename,
-			DeclaredSize: int64(len(b)),
+			DeclaredSize: int64(declaredSize),
 			Started:      time.Now(),
 		}
 		updates := map[string]*ipn.OutgoingFile{outgoing.ID: outgoing}
@@ -127,17 +129,17 @@ func (i *jsIPN) sendFile(stableNodeID, filename string, data js.Value) js.Value
 			ext.UpdateOutgoingFiles(updates)
 		}()
 
-		body := progresstracking.NewReader(bytes.NewReader(b), time.Second, func(n int, _ error) {
+		progressBody := progresstracking.NewReader(body, time.Second, func(n int, _ error) {
 			outgoing.Sent = int64(n)
 			ext.UpdateOutgoingFiles(updates)
 		})
 
-		req, err := http.NewRequest("PUT", dstURL.String()+"/v0/put/"+url.PathEscape(filename), body)
+		req, err := http.NewRequest("PUT", dstURL.String()+"/v0/put/"+url.PathEscape(filename), progressBody)
 		if err != nil {
 			sendErr = err
 			return nil, err
 		}
-		req.ContentLength = int64(len(b))
+		req.ContentLength = int64(declaredSize)
 		client := &http.Client{Transport: i.lb.Dialer().PeerAPITransport()}
 		resp, err := client.Do(req)
 		if err != nil {
@@ -147,7 +149,13 @@ func (i *jsIPN) sendFile(stableNodeID, filename string, data js.Value) js.Value
 		defer resp.Body.Close()
 		if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusCreated {
 			respBody, _ := io.ReadAll(resp.Body)
-			sendErr = fmt.Errorf("send file: %s: %s", resp.Status, bytes.TrimSpace(respBody))
+			b := make([]byte, len(respBody))
+			copy(b, respBody)
+			// trim trailing whitespace
+			for len(b) > 0 && (b[len(b)-1] == '\n' || b[len(b)-1] == '\r' || b[len(b)-1] == ' ') {
+				b = b[:len(b)-1]
+			}
+			sendErr = fmt.Errorf("send file: %s: %s", resp.Status, b)
 			return nil, sendErr
 		}
 		return nil, nil
@@ -182,7 +190,8 @@ func (i *jsIPN) waitingFiles() js.Value {
 	})
 }
 
-// openWaitingFile returns the contents of a received file as a Uint8Array.
+// openWaitingFile returns the contents of a received file as a ReadableStream.
+// The stream emits Uint8Array chunks and closes when the file is fully read.
 func (i *jsIPN) openWaitingFile(name string) js.Value {
 	return makePromise(func() (any, error) {
 		ext, err := i.taildropExt()
@@ -193,14 +202,7 @@ func (i *jsIPN) openWaitingFile(name string) js.Value {
 		if err != nil {
 			return nil, err
 		}
-		defer rc.Close()
+		return jsReadableStream(rc), nil
-		data, err := io.ReadAll(rc)
-		if err != nil {
-			return nil, err
-		}
-		buf := js.Global().Get("Uint8Array").New(len(data))
-		js.CopyBytesToJS(buf, data)
-		return buf, nil
 	})
 }
 
@@ -234,6 +236,109 @@ func wireTaildropFileOps(lb *ipnlocal.LocalBackend, jsObj js.Value) {
 	ext.SetStagedFileOps(&jsFileOps{v: jsObj})
 }
 
+// jsStreamReader implements io.ReadCloser by pulling chunks from a JS
+// ReadableStreamDefaultReader. Each Read call awaits one reader.read() Promise,
+// using the channel+FuncOf pattern so Go blocks until JS delivers the chunk.
+type jsStreamReader struct {
+	reader js.Value
+	buf    []byte
+	done   bool
+}
+
+func (r *jsStreamReader) Read(p []byte) (int, error) {
+	if r.done {
+		return 0, io.EOF
+	}
+	if len(r.buf) > 0 {
+		n := copy(p, r.buf)
+		r.buf = r.buf[n:]
+		return n, nil
+	}
+	type chunkResult struct {
+		data []byte
+		done bool
+	}
+	ch := make(chan chunkResult, 1)
+	thenFn := js.FuncOf(func(this js.Value, args []js.Value) any {
+		result := args[0]
+		if result.Get("done").Bool() {
+			ch <- chunkResult{done: true}
+		} else {
+			value := result.Get("value")
+			b := make([]byte, value.Get("byteLength").Int())
+			js.CopyBytesToGo(b, value)
+			ch <- chunkResult{data: b}
+		}
+		return nil
+	})
+	defer thenFn.Release()
+	r.reader.Call("read").Call("then", thenFn)
+	result := <-ch
+	if result.done {
+		r.done = true
+		return 0, io.EOF
+	}
+	n := copy(p, result.data)
+	r.buf = result.data[n:]
+	return n, nil
+}
+
+func (r *jsStreamReader) Close() error {
+	r.reader.Call("cancel")
+	return nil
+}
+
+// jsReadableStream wraps rc in a pull-based JS ReadableStream. Each pull call
+// reads up to 64 KiB from rc and enqueues a Uint8Array chunk; the stream
+// closes on EOF or signals an error on any other read failure.
+func jsReadableStream(rc io.ReadCloser) js.Value {
+	var pullFn, cancelFn js.Func
+
+	cancelFn = js.FuncOf(func(this js.Value, args []js.Value) any {
+		rc.Close()
+		pullFn.Release()
+		cancelFn.Release()
+		return nil
+	})
+
+	pullFn = js.FuncOf(func(this js.Value, args []js.Value) any {
+		controller := args[0]
+		var execFn js.Func
+		execFn = js.FuncOf(func(this js.Value, rr []js.Value) any {
+			resolve := rr[0]
+			go func() {
+				defer execFn.Release()
+				buf := make([]byte, 65536)
+				n, err := rc.Read(buf)
+				if n > 0 {
+					chunk := js.Global().Get("Uint8Array").New(n)
+					js.CopyBytesToJS(chunk, buf[:n])
+					controller.Call("enqueue", chunk)
+				}
+				if err == io.EOF {
+					rc.Close()
+					pullFn.Release()
+					cancelFn.Release()
+					controller.Call("close")
+				} else if err != nil {
+					rc.Close()
+					pullFn.Release()
+					cancelFn.Release()
+					controller.Call("error", err.Error())
+				}
+				resolve.Invoke()
+			}()
+			return nil
+		})
+		return js.Global().Get("Promise").New(execFn)
+	})
+
+	return js.Global().Get("ReadableStream").New(map[string]any{
+		"pull":   pullFn,
+		"cancel": cancelFn,
+	})
+}
+
 // jsFileOps implements [taildrop.FileOps] by delegating to JS callbacks.
 // JS methods use one of two callback conventions:
 //
@@ -385,9 +490,9 @@ func (j jsFileOps) OpenReader(name string) (io.ReadCloser, error) {
 	if err != nil {
 		return nil, err
 	}
-	b := make([]byte, val.Get("byteLength").Int())
+	// val is a ReadableStream; wrap its reader for streaming delivery to Go.
-	js.CopyBytesToGo(b, val)
+	reader := val.Call("getReader")
-	return io.NopCloser(bytes.NewReader(b)), nil
+	return &jsStreamReader{reader: reader}, nil
 }
 
 // jsFileInfo is a minimal [fs.FileInfo] backed by a name and a size.

cmd/tsconnect/wasm/wasm_js.go

@@ -66,19 +66,20 @@ import (
 var ControlURL = ipn.DefaultControlURL
 
 func main() {
+	shutdownCh := make(chan struct{})
 	js.Global().Set("newIPN", js.FuncOf(func(this js.Value, args []js.Value) any {
 		if len(args) != 1 {
 			log.Fatal("Usage: newIPN(config)")
 			return nil
 		}
-		return newIPN(args[0])
+		return newIPN(args[0], shutdownCh)
 	}))
-	// Keep Go runtime alive, otherwise it will be shut down before newIPN gets
+	// Block until shutdown() is called on the IPN, then let main return so the
-	// called.
+	// Go runtime (and all its goroutines) can be collected by the JS engine.
-	<-make(chan bool)
+	<-shutdownCh
 }
 
-func newIPN(jsConfig js.Value) map[string]any {
+func newIPN(jsConfig js.Value, shutdownCh chan struct{}) map[string]any {
 	netns.SetEnabled(false)
 
 	var store ipn.StateStore
@@ -158,6 +159,10 @@ func newIPN(jsConfig js.Value) map[string]any {
 	sys.Tun.Get().Start()
 
 	logid := lpc.PublicID
+
+	// initDriveForRemote must be called before NewLocalBackend (SubSystem is set-once).
+	driveFS := initDriveForRemote(sys)
+
 	srv := ipnserver.New(logf, logid, sys.Bus.Get(), sys.NetMon.Get())
 	lb, err := ipnlocal.NewLocalBackend(logf, logid, sys, controlclient.LoginEphemeral)
 	if err != nil {
@@ -179,10 +184,11 @@ func newIPN(jsConfig js.Value) map[string]any {
 		hostname:    hostname,
 		logID:       logid,
 		funnelPorts: make(map[uint16]*funnelListenerEntry),
+		shutdownCh:  shutdownCh,
 	}
 	lb.SetTCPHandlerForFunnelFlow(jsIPN.handleFunnelTCP)
 
-	return map[string]any{
+	m := map[string]any{
 		"run": js.FuncOf(func(this js.Value, args []js.Value) any {
 			if len(args) != 1 {
 				log.Fatal(`Usage: run({
@@ -281,11 +287,11 @@ func newIPN(jsConfig js.Value) map[string]any {
 			return jsIPN.listFileTargets()
 		}),
 		"sendFile": js.FuncOf(func(this js.Value, args []js.Value) any {
-			if len(args) != 3 {
+			if len(args) != 4 {
-				log.Printf("Usage: sendFile(stableNodeID, filename, data)")
+				log.Printf("Usage: sendFile(stableNodeID, filename, stream, declaredSize)")
 				return nil
 			}
-			return jsIPN.sendFile(args[0].String(), args[1].String(), args[2])
+			return jsIPN.sendFile(args[0].String(), args[1].String(), args[2], args[3].Int())
 		}),
 		"waitingFiles": js.FuncOf(func(this js.Value, args []js.Value) any {
 			return jsIPN.waitingFiles()
@@ -361,6 +367,9 @@ func newIPN(jsConfig js.Value) map[string]any {
 		"suggestExitNode": js.FuncOf(func(this js.Value, args []js.Value) any {
 			return jsIPN.suggestExitNode()
 		}),
+		"shutdown": js.FuncOf(func(this js.Value, args []js.Value) any {
+			return jsIPN.shutdown()
+		}),
 		"setServices": js.FuncOf(func(this js.Value, args []js.Value) any {
 			if len(args) != 1 {
 				log.Printf("Usage: setServices(services)")
@@ -380,6 +389,8 @@ func newIPN(jsConfig js.Value) map[string]any {
 			return jsIPN.localAPI(args[0].String(), args[1].String(), body)
 		}),
 	}
+	wireDriveJS(jsIPN, driveFS, m)
+	return m
 }
 
 type jsIPN struct {
@@ -394,6 +405,12 @@ type jsIPN struct {
 
 	funnelMu    sync.Mutex
 	funnelPorts map[uint16]*funnelListenerEntry
+
+	// ln is the safesocket listener created by run(); stored here so shutdown
+	// can close it and unblock srv.Run.
+	ln           net.Listener
+	shutdownCh   chan struct{} // closed by shutdown() to unblock main()
+	shutdownOnce sync.Once
 }
 
 // funnelListenerEntry is the per-port state for routing Funnel connections to a listenTLS listener.
@@ -490,32 +507,7 @@ func (i *jsIPN) run(jsCallbacks js.Value) {
 					}
 
 					// Peer peerAPI URL from the peer's advertised Services.
-					peerURL := ""
+					peerURL := buildPeerAPIURL(p, selfHave4, selfHave6)
-					var pp4, pp6 uint16
-					for _, s := range p.Hostinfo().Services().All() {
-						switch s.Proto {
-						case tailcfg.PeerAPI4:
-							pp4 = s.Port
-						case tailcfg.PeerAPI6:
-							pp6 = s.Port
-						}
-					}
-					if selfHave4 && pp4 != 0 {
-						for _, a := range p.Addresses().All() {
-							if a.IsSingleIP() && a.Addr().Is4() {
-								peerURL = fmt.Sprintf("http://%v", netip.AddrPortFrom(a.Addr(), pp4))
-								break
-							}
-						}
-					}
-					if peerURL == "" && selfHave6 && pp6 != 0 {
-						for _, a := range p.Addresses().All() {
-							if a.IsSingleIP() && a.Addr().Is6() {
-								peerURL = fmt.Sprintf("http://%v", netip.AddrPortFrom(a.Addr(), pp6))
-								break
-							}
-						}
-					}
 
 					return jsNetMapPeerNode{
 						jsNetMapNode: jsNetMapNode{
@@ -603,14 +595,17 @@ func (i *jsIPN) run(jsCallbacks js.Value) {
 		}
 	}()
 
-	go func() {
 	ln, err := safesocket.Listen("")
 	if err != nil {
 		log.Fatalf("safesocket.Listen: %v", err)
 	}
+	i.ln = ln
 
-		err = i.srv.Run(context.Background(), ln)
+	go func() {
+		err := i.srv.Run(context.Background(), ln)
+		if err != nil && !errors.Is(err, net.ErrClosed) {
 			log.Fatalf("ipnserver.Run exited: %v", err)
+		}
 	}()
 }
 
@@ -629,6 +624,21 @@ func (i *jsIPN) logout() {
 	}()
 }
 
+func (i *jsIPN) shutdown() js.Value {
+	return makePromise(func() (any, error) {
+		i.shutdownOnce.Do(func() {
+			if i.lb != nil {
+				i.lb.Shutdown()
+			}
+			if i.ln != nil {
+				i.ln.Close()
+			}
+			close(i.shutdownCh)
+		})
+		return nil, nil
+	})
+}
+
 func (i *jsIPN) ssh(host, username string, termConfig js.Value) map[string]any {
 	jsSSHSession := &jsSSHSession{
 		jsIPN:      i,
@@ -857,6 +867,11 @@ func (i *jsIPN) listen(network, addr string) js.Value {
 			if n == "tcp" {
 				n = "tcp4"
 			}
+			// netstack.ListenTCP requires a full host:port; normalise the
+			// standard net.Listen form ":port" that omits the host.
+			if strings.HasPrefix(addr, ":") {
+				addr = "0.0.0.0" + addr
+			}
 			ln, err := i.ns.ListenTCP(n, addr)
 			if err != nil {
 				return nil, err
@@ -1359,7 +1374,7 @@ func (i *jsIPN) setServices(jsServices js.Value) js.Value {
 // userServicesFromView converts a hostinfo services slice to jsService entries,
 // filtering out internal peerapi protocol entries (already reflected in peerAPIURL).
 func userServicesFromView(svcs views.Slice[tailcfg.Service]) []jsService {
-	var out []jsService
+	out := make([]jsService, 0, svcs.Len())
 	for _, s := range svcs.All() {
 		switch s.Proto {
 		case tailcfg.PeerAPI4, tailcfg.PeerAPI6, tailcfg.PeerAPIDNS:
@@ -1618,7 +1633,7 @@ type jsNetMapNode struct {
 	MachineKey string      `json:"machineKey"`
 	NodeKey    string      `json:"nodeKey"`
 	PeerAPIURL string      `json:"peerAPIURL,omitempty"`
-	Services   []jsService `json:"services,omitempty"`
+	Services   []jsService `json:"services"`
 }
 
 type jsNetMapSelfNode struct {

control/controlclient/auto.go

@@ -302,6 +302,12 @@ func (c *Auto) restartMap() {
 	c.updateControl()
 }
 
+// RestartMap cancels the existing map poll and starts a fresh streaming one,
+// forcing the control server to send a new full netmap response.
+func (c *Auto) RestartMap() {
+	c.restartMap()
+}
+
 func (c *Auto) authRoutine() {
 	defer close(c.authDone)
 	bo := backoff.NewBackoff("authRoutine", c.logf, 30*time.Second)

ipn/ipnlocal/local.go

@@ -4980,9 +4980,16 @@ func (b *LocalBackend) SetExplicitServices(sl []tailcfg.Service) {
 	}
 	b.hostinfo.Services = sl
 	b.explicitServices = sl
+	ccAuto := b.ccAuto
 	b.mu.Unlock()
 
 	b.doSetHostinfoFilterServices()
+	// Restart the streaming map poll so the control server sends back a fresh
+	// netmap that includes our updated services in SelfNode, and so peers
+	// receive the update promptly via the control server's push.
+	if ccAuto != nil {
+		ccAuto.RestartMap()
+	}
 }
 
 // doSetHostinfoFilterServices calls SetHostinfo on the controlclient,

safesocket/safesocket_js.go

@@ -5,15 +5,22 @@ package safesocket
 
 import (
 	"context"
+	"fmt"
 	"net"
+	"sync/atomic"
 
 	"github.com/akutz/memconn"
 )
 
 const memName = "Tailscale-IPN"
 
+// memSeq ensures each IPN instance in the same WASM process gets a distinct
+// memconn address, so concurrent instances do not conflict on the registry.
+var memSeq atomic.Int64
+
 func listen(path string) (net.Listener, error) {
-	return memconn.Listen("memu", memName)
+	name := fmt.Sprintf("%s-%d", memName, memSeq.Add(1))
+	return memconn.Listen("memu", name)
 }
 
 func connect(ctx context.Context, _ string) (net.Conn, error) {