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/build-pkg.go

@@ -13,7 +13,6 @@ import (
 	"path"
 
 	"github.com/tailscale/hujson"
-	"tailscale.com/util/precompress"
 	"tailscale.com/version"
 )
 
@@ -39,10 +38,6 @@ func runBuildPkg() {
 
 	runEsbuild(*buildOptions)
 
-	if err := precompressWasm(); err != nil {
-		log.Fatalf("Could not pre-recompress wasm: %v", err)
-	}
-
 	log.Printf("Generating types...\n")
 	if err := runYarn("pkg-types"); err != nil {
 		log.Fatalf("Type generation failed: %v", err)
@@ -59,13 +54,6 @@ func runBuildPkg() {
 	log.Printf("Built package version %s", version.Long())
 }
 
-func precompressWasm() error {
-	log.Printf("Pre-compressing main.wasm...\n")
-	return precompress.Precompress(path.Join(*pkgDir, "main.wasm"), precompress.Options{
-		FastCompression: *fastCompression,
-	})
-}
-
 func updateVersion() error {
 	packageJSONBytes, err := os.ReadFile("package.json.tmpl")
 	if err != nil {

cmd/tsconnect/tsconfig.json

@@ -8,7 +8,8 @@
     "forceConsistentCasingInFileNames": true,
     "sourceMap": true,
     "jsx": "react-jsx",
-    "jsxImportSource": "preact"
+    "jsxImportSource": "preact",
+    "types": ["golang-wasm-exec", "qrcode"]
   },
   "include": ["src/**/*"],
   "exclude": ["node_modules"]

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

@@ -0,0 +1,405 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+// This file bridges the Taildrop FileOps interface to JS callbacks,
+// using the same channel+FuncOf pattern as the Go stdlib's WASM HTTP
+// transport (src/net/http/roundtrip_js.go): Go passes a js.FuncOf to JS,
+// then blocks on a channel until JS calls it back — which may be async.
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"net/http"
+	"net/url"
+	"os"
+	"syscall/js"
+	"time"
+
+	"tailscale.com/client/tailscale/apitype"
+	"tailscale.com/feature/taildrop"
+	"tailscale.com/ipn"
+	"tailscale.com/ipn/ipnlocal"
+	"tailscale.com/tailcfg"
+	"tailscale.com/util/progresstracking"
+	"tailscale.com/util/rands"
+)
+
+// Compile-time check that jsFileOps implements taildrop.FileOps.
+var _ taildrop.FileOps = (*jsFileOps)(nil)
+
+// taildropExt returns the taildrop extension, or an error if unavailable.
+func (i *jsIPN) taildropExt() (*taildrop.Extension, error) {
+	ext, ok := ipnlocal.GetExt[*taildrop.Extension](i.lb)
+	if !ok {
+		return nil, errors.New("taildrop extension not available")
+	}
+	return ext, nil
+}
+
+// listFileTargets returns the peers that can receive Taildrop files as a JSON
+// array of {stableNodeID, name, addresses, os} objects.
+func (i *jsIPN) listFileTargets() js.Value {
+	return makePromise(func() (any, error) {
+		ext, err := i.taildropExt()
+		if err != nil {
+			return nil, err
+		}
+		fts, err := ext.FileTargets()
+		if err != nil {
+			return nil, err
+		}
+		type jsTarget struct {
+			StableNodeID string   `json:"stableNodeID"`
+			Name         string   `json:"name"`
+			Addresses    []string `json:"addresses"`
+			OS           string   `json:"os"`
+		}
+		out := make([]jsTarget, 0, len(fts))
+		for _, ft := range fts {
+			addrs := make([]string, 0, len(ft.Node.Addresses))
+			for _, a := range ft.Node.Addresses {
+				addrs = append(addrs, a.Addr().String())
+			}
+			out = append(out, jsTarget{
+				StableNodeID: string(ft.Node.StableID),
+				Name:         ft.Node.Name,
+				Addresses:    addrs,
+				OS:           ft.Node.Hostinfo.OS(),
+			})
+		}
+		b, err := json.Marshal(out)
+		if err != nil {
+			return nil, err
+		}
+		return string(b), nil
+	})
+}
+
+// sendFile sends data 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 {
+	return makePromise(func() (any, error) {
+		ext, err := i.taildropExt()
+		if err != nil {
+			return nil, err
+		}
+		fts, err := ext.FileTargets()
+		if err != nil {
+			return nil, err
+		}
+		var ft *apitype.FileTarget
+		for _, x := range fts {
+			if x.Node.StableID == tailcfg.StableNodeID(stableNodeID) {
+				ft = x
+				break
+			}
+		}
+		if ft == nil {
+			return nil, fmt.Errorf("node %q not found or not a file target", stableNodeID)
+		}
+		dstURL, err := url.Parse(ft.PeerAPIURL)
+		if err != nil {
+			return nil, fmt.Errorf("bogus peer URL: %w", err)
+		}
+		b := make([]byte, data.Get("byteLength").Int())
+		js.CopyBytesToGo(b, data)
+
+		outgoing := &ipn.OutgoingFile{
+			ID:           rands.HexString(30),
+			PeerID:       tailcfg.StableNodeID(stableNodeID),
+			Name:         filename,
+			DeclaredSize: int64(len(b)),
+			Started:      time.Now(),
+		}
+		updates := map[string]*ipn.OutgoingFile{outgoing.ID: outgoing}
+
+		// Report final state (success or failure) when the function returns.
+		var sendErr error
+		defer func() {
+			outgoing.Finished = true
+			outgoing.Succeeded = sendErr == nil
+			ext.UpdateOutgoingFiles(updates)
+		}()
+
+		body := progresstracking.NewReader(bytes.NewReader(b), 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)
+		if err != nil {
+			sendErr = err
+			return nil, err
+		}
+		req.ContentLength = int64(len(b))
+		client := &http.Client{Transport: i.lb.Dialer().PeerAPITransport()}
+		resp, err := client.Do(req)
+		if err != nil {
+			sendErr = err
+			return nil, err
+		}
+		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))
+			return nil, sendErr
+		}
+		return nil, nil
+	})
+}
+
+// waitingFiles returns received files waiting for pickup as a JSON array of
+// {name, size} objects. Always returns an array (never null).
+func (i *jsIPN) waitingFiles() js.Value {
+	return makePromise(func() (any, error) {
+		ext, err := i.taildropExt()
+		if err != nil {
+			return nil, err
+		}
+		wfs, err := ext.WaitingFiles()
+		if err != nil {
+			return nil, err
+		}
+		type jsWaitingFile struct {
+			Name string `json:"name"`
+			Size int64  `json:"size"`
+		}
+		out := make([]jsWaitingFile, len(wfs))
+		for i, wf := range wfs {
+			out[i] = jsWaitingFile{Name: wf.Name, Size: wf.Size}
+		}
+		b, err := json.Marshal(out)
+		if err != nil {
+			return nil, err
+		}
+		return string(b), nil
+	})
+}
+
+// openWaitingFile returns the contents of a received file as a Uint8Array.
+func (i *jsIPN) openWaitingFile(name string) js.Value {
+	return makePromise(func() (any, error) {
+		ext, err := i.taildropExt()
+		if err != nil {
+			return nil, err
+		}
+		rc, _, err := ext.OpenFile(name)
+		if err != nil {
+			return nil, err
+		}
+		defer rc.Close()
+		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
+	})
+}
+
+// deleteWaitingFile deletes a received file by name.
+func (i *jsIPN) deleteWaitingFile(name string) js.Value {
+	return makePromise(func() (any, error) {
+		ext, err := i.taildropExt()
+		if err != nil {
+			return nil, err
+		}
+		return nil, ext.DeleteFile(name)
+	})
+}
+
+// wireTaildropFileOps installs a JS-backed FileOps on the taildrop extension
+// if jsObj is a non-null JS object. It must be called after NewLocalBackend
+// and before lb.Start (i.e. before run() is called by the user), so that the
+// FileOps is in place when the extension's onChangeProfile hook fires on init.
+//
+// SetStagedFileOps is used instead of SetFileOps so that files are staged for
+// explicit retrieval via WaitingFiles/OpenFile rather than delivered directly
+// (DirectFileMode=false). The JS caller fetches them via waitingFiles() et al.
+func wireTaildropFileOps(lb *ipnlocal.LocalBackend, jsObj js.Value) {
+	if jsObj.IsUndefined() || jsObj.IsNull() {
+		return
+	}
+	ext, ok := ipnlocal.GetExt[*taildrop.Extension](lb)
+	if !ok {
+		return
+	}
+	ext.SetStagedFileOps(&jsFileOps{v: jsObj})
+}
+
+// jsFileOps implements [taildrop.FileOps] by delegating to JS callbacks.
+// JS methods use one of two callback conventions:
+//
+// Void ops (openWriter, write, closeWriter, remove): cb(err?: string)
+//
+//	on success: cb()  or  cb("")
+//	on error:   cb("error message")
+//	not found:  cb("ENOENT")
+//
+// Result ops (rename, listFiles, stat, openReader): cb(result: T | null, err?: string)
+//
+//	on success: cb(result)
+//	on error:   cb(null, "error message")
+//	not found:  cb(null, "ENOENT")
+type jsFileOps struct {
+	v js.Value
+}
+
+// jsCallResult invokes method on j.v, appending a Go-owned js.FuncOf as the
+// final argument. It blocks until JS calls back with (result, errStr?), then
+// returns (result, error). An absent or empty errStr means success.
+//
+// JS convention for result ops: cb(result: T | null, err?: string)
+func (j jsFileOps) jsCallResult(method string, args ...any) (js.Value, error) {
+	type result struct {
+		val js.Value
+		err error
+	}
+	ch := make(chan result, 1)
+	cb := js.FuncOf(func(this js.Value, cbArgs []js.Value) any {
+		var r result
+		if len(cbArgs) > 0 {
+			if t := cbArgs[0].Type(); t != js.TypeNull && t != js.TypeUndefined {
+				r.val = cbArgs[0]
+			}
+		}
+		if len(cbArgs) > 1 && cbArgs[1].Type() == js.TypeString {
+			if s := cbArgs[1].String(); s != "" {
+				r.err = errors.New(s)
+			}
+		}
+		ch <- r
+		return nil
+	})
+	defer cb.Release()
+	j.v.Call(method, append(args, cb)...)
+	r := <-ch
+	return r.val, r.err
+}
+
+// jsCallVoid invokes method on j.v for operations that return no result,
+// appending a Go-owned js.FuncOf as the final argument. It blocks until JS
+// calls back with an optional error string, then returns the error or nil.
+//
+// JS convention for void ops: cb(err?: string)
+func (j jsFileOps) jsCallVoid(method string, args ...any) error {
+	ch := make(chan error, 1)
+	cb := js.FuncOf(func(this js.Value, cbArgs []js.Value) any {
+		var err error
+		if len(cbArgs) > 0 && cbArgs[0].Type() == js.TypeString {
+			if s := cbArgs[0].String(); s != "" {
+				err = errors.New(s)
+			}
+		}
+		ch <- err
+		return nil
+	})
+	defer cb.Release()
+	j.v.Call(method, append(args, cb)...)
+	return <-ch
+}
+
+// isJSNotExist reports whether err is the sentinel "ENOENT" from JS.
+func isJSNotExist(err error) bool {
+	return err != nil && err.Error() == "ENOENT"
+}
+
+func (j jsFileOps) OpenWriter(name string, offset int64, _ os.FileMode) (io.WriteCloser, string, error) {
+	if err := j.jsCallVoid("openWriter", name, offset); err != nil {
+		return nil, "", err
+	}
+	return &jsWriteCloser{ops: j, name: name}, name, nil
+}
+
+type jsWriteCloser struct {
+	ops  jsFileOps
+	name string
+}
+
+func (w *jsWriteCloser) Write(p []byte) (int, error) {
+	buf := js.Global().Get("Uint8Array").New(len(p))
+	js.CopyBytesToJS(buf, p)
+	if err := w.ops.jsCallVoid("write", w.name, buf); err != nil {
+		return 0, err
+	}
+	return len(p), nil
+}
+
+func (w *jsWriteCloser) Close() error {
+	return w.ops.jsCallVoid("closeWriter", w.name)
+}
+
+func (j jsFileOps) Remove(name string) error {
+	err := j.jsCallVoid("remove", name)
+	if isJSNotExist(err) {
+		return &fs.PathError{Op: "remove", Path: name, Err: fs.ErrNotExist}
+	}
+	return err
+}
+
+func (j jsFileOps) Rename(oldPath, newName string) (string, error) {
+	val, err := j.jsCallResult("rename", oldPath, newName)
+	if err != nil {
+		return "", err
+	}
+	return val.String(), nil
+}
+
+func (j jsFileOps) ListFiles() ([]string, error) {
+	val, err := j.jsCallResult("listFiles")
+	if err != nil {
+		return nil, err
+	}
+	n := val.Length()
+	names := make([]string, n)
+	for i := 0; i < n; i++ {
+		names[i] = val.Index(i).String()
+	}
+	return names, nil
+}
+
+func (j jsFileOps) Stat(name string) (fs.FileInfo, error) {
+	val, err := j.jsCallResult("stat", name)
+	if isJSNotExist(err) {
+		return nil, &fs.PathError{Op: "stat", Path: name, Err: fs.ErrNotExist}
+	}
+	if err != nil {
+		return nil, err
+	}
+	// Use Float to correctly handle files larger than 2 GiB (int is 32-bit on wasm).
+	return &jsFileInfo{name: name, size: int64(val.Float())}, nil
+}
+
+func (j jsFileOps) OpenReader(name string) (io.ReadCloser, error) {
+	val, err := j.jsCallResult("openReader", name)
+	if isJSNotExist(err) {
+		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
+	}
+	if err != nil {
+		return nil, err
+	}
+	b := make([]byte, val.Get("byteLength").Int())
+	js.CopyBytesToGo(b, val)
+	return io.NopCloser(bytes.NewReader(b)), nil
+}
+
+// jsFileInfo is a minimal [fs.FileInfo] backed by a name and a size.
+// Only Size() is used by the taildrop manager; the other fields are stubs.
+type jsFileInfo struct {
+	name string
+	size int64
+}
+
+func (i *jsFileInfo) Name() string       { return i.name }
+func (i *jsFileInfo) Size() int64        { return i.size }
+func (i *jsFileInfo) Mode() fs.FileMode  { return 0o444 }
+func (i *jsFileInfo) ModTime() time.Time { return time.Time{} }
+func (i *jsFileInfo) IsDir() bool        { return false }
+func (i *jsFileInfo) Sys() any           { return nil }

cmd/tsconnect/wasm/wasm_js.go

@@ -18,17 +18,21 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"log"
 	"math/rand/v2"
 	"net"
 	"net/http"
+	"net/http/httptest"
 	"net/netip"
 	"strconv"
 	"strings"
+	"sync"
 	"syscall/js"
 	"time"
 
 	"golang.org/x/crypto/ssh"
+	"golang.org/x/net/dns/dnsmessage"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
@@ -40,15 +44,18 @@ import (
 	"tailscale.com/ipn/ipnauth"
 	"tailscale.com/ipn/ipnlocal"
 	"tailscale.com/ipn/ipnserver"
+	"tailscale.com/ipn/localapi"
 	"tailscale.com/ipn/store/mem"
 	"tailscale.com/logpolicy"
 	"tailscale.com/logtail"
 	"tailscale.com/net/bakedroots"
 	"tailscale.com/net/netns"
+	"tailscale.com/net/tsaddr"
 	"tailscale.com/net/tsdial"
 	"tailscale.com/safesocket"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tsd"
+	"tailscale.com/types/logid"
 	"tailscale.com/types/views"
 	"tailscale.com/wgengine"
 	"tailscale.com/wgengine/netstack"
@@ -151,6 +158,10 @@ 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 {
@@ -159,19 +170,23 @@ func newIPN(jsConfig js.Value) map[string]any {
 	if err := ns.Start(lb); err != nil {
 		log.Fatalf("failed to start netstack: %v", err)
 	}
+	wireTaildropFileOps(lb, jsConfig.Get("fileOps"))
 	srv.SetLocalBackend(lb)
 
 	jsIPN := &jsIPN{
-		dialer:     dialer,
-		srv:        srv,
-		lb:         lb,
-		ns:         ns,
-		controlURL: controlURL,
-		authKey:    authKey,
-		hostname:   hostname,
+		dialer:      dialer,
+		srv:         srv,
+		lb:          lb,
+		ns:          ns,
+		controlURL:  controlURL,
+		authKey:     authKey,
+		hostname:    hostname,
+		logID:       logid,
+		funnelPorts: make(map[uint16]*funnelListenerEntry),
 	}
+	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({
@@ -252,7 +267,118 @@ func newIPN(jsConfig js.Value) map[string]any {
 			}
 			return jsIPN.dialTLS(args[0].String(), opts)
 		}),
+		"setExitNode": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 1 {
+				log.Printf("Usage: setExitNode(stableNodeID)")
+				return nil
+			}
+			return jsIPN.setExitNode(args[0].String())
+		}),
+		"setExitNodeEnabled": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 1 {
+				log.Printf("Usage: setExitNodeEnabled(enabled)")
+				return nil
+			}
+			return jsIPN.setExitNodeEnabled(args[0].Bool())
+		}),
+		"listFileTargets": js.FuncOf(func(this js.Value, args []js.Value) any {
+			return jsIPN.listFileTargets()
+		}),
+		"sendFile": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 3 {
+				log.Printf("Usage: sendFile(stableNodeID, filename, data)")
+				return nil
+			}
+			return jsIPN.sendFile(args[0].String(), args[1].String(), args[2])
+		}),
+		"waitingFiles": js.FuncOf(func(this js.Value, args []js.Value) any {
+			return jsIPN.waitingFiles()
+		}),
+		"openWaitingFile": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 1 {
+				log.Printf("Usage: openWaitingFile(name)")
+				return nil
+			}
+			return jsIPN.openWaitingFile(args[0].String())
+		}),
+		"deleteWaitingFile": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 1 {
+				log.Printf("Usage: deleteWaitingFile(name)")
+				return nil
+			}
+			return jsIPN.deleteWaitingFile(args[0].String())
+		}),
+		"getCert": js.FuncOf(func(this js.Value, args []js.Value) any {
+			return jsIPN.getCert()
+		}),
+		"listenTLS": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 3 {
+				log.Printf("Usage: listenTLS(addr, certPEM, keyPEM)")
+				return nil
+			}
+			return jsIPN.listenTLS(args[0].String(), args[1].String(), args[2].String())
+		}),
+		"setFunnel": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) != 3 {
+				log.Printf("Usage: setFunnel(hostname, port, enabled)")
+				return nil
+			}
+			return jsIPN.setFunnel(args[0].String(), uint16(args[1].Int()), args[2].Bool())
+		}),
+		"whoIs": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) < 1 {
+				log.Printf("Usage: whoIs(addrPort[, proto])")
+				return nil
+			}
+			proto := ""
+			if len(args) >= 2 {
+				proto = args[1].String()
+			}
+			return jsIPN.whoIs(args[0].String(), proto)
+		}),
+		"queryDNS": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) < 1 {
+				log.Printf("Usage: queryDNS(name[, type])")
+				return nil
+			}
+			qtype := 1 // TypeA
+			if len(args) >= 2 {
+				qtype = args[1].Int()
+			}
+			return jsIPN.queryDNS(args[0].String(), qtype)
+		}),
+		"ping": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) < 1 {
+				log.Printf("Usage: ping(ip[, type[, size]])")
+				return nil
+			}
+			pingType := "TSMP"
+			if len(args) >= 2 {
+				pingType = args[1].String()
+			}
+			size := 0
+			if len(args) >= 3 {
+				size = args[2].Int()
+			}
+			return jsIPN.ping(args[0].String(), pingType, size)
+		}),
+		"suggestExitNode": js.FuncOf(func(this js.Value, args []js.Value) any {
+			return jsIPN.suggestExitNode()
+		}),
+		"localAPI": js.FuncOf(func(this js.Value, args []js.Value) any {
+			if len(args) < 2 {
+				log.Printf("Usage: localAPI(method, path[, body])")
+				return nil
+			}
+			body := ""
+			if len(args) >= 3 {
+				body = args[2].String()
+			}
+			return jsIPN.localAPI(args[0].String(), args[1].String(), body)
+		}),
 	}
+	wireDriveJS(jsIPN, driveFS, m)
+	return m
 }
 
 type jsIPN struct {
@@ -263,6 +389,16 @@ type jsIPN struct {
 	controlURL string
 	authKey    string
 	hostname   string
+	logID      logid.PublicID
+
+	funnelMu    sync.Mutex
+	funnelPorts map[uint16]*funnelListenerEntry
+}
+
+// funnelListenerEntry is the per-port state for routing Funnel connections to a listenTLS listener.
+type funnelListenerEntry struct {
+	ch     chan net.Conn
+	tlsCfg *tls.Config
 }
 
 var jsIPNState = map[ipn.State]string{
@@ -304,6 +440,31 @@ func (i *jsIPN) run(jsCallbacks js.Value) {
 			notifyState(*n.State)
 		}
 		if nm := n.NetMap; nm != nil {
+			// Determine which address families we have, for peer peerAPI URL selection.
+			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
+				}
+			}
+
+			// Self peerAPI URL: own port as reported by LocalBackend.
+			selfPeerAPIURL := ""
+			for _, a := range nm.GetAddresses().All() {
+				if !a.IsSingleIP() {
+					continue
+				}
+				if port, ok := i.lb.GetPeerAPIPort(a.Addr()); ok && port != 0 {
+					selfPeerAPIURL = fmt.Sprintf("http://%v", netip.AddrPortFrom(a.Addr(), port))
+					break
+				}
+			}
+
 			jsNetMap := jsNetMap{
 				Self: jsNetMapSelfNode{
 					jsNetMapNode: jsNetMapNode{
@@ -311,6 +472,7 @@ func (i *jsIPN) run(jsCallbacks js.Value) {
 						Addresses:  mapSliceView(nm.GetAddresses(), func(a netip.Prefix) string { return a.Addr().String() }),
 						NodeKey:    nm.NodeKey.String(),
 						MachineKey: nm.MachineKey.String(),
+						PeerAPIURL: selfPeerAPIURL,
 					},
 					MachineStatus: jsMachineStatus[nm.GetMachineStatus()],
 				},
@@ -321,18 +483,25 @@ func (i *jsIPN) run(jsCallbacks js.Value) {
 						name = p.Hostinfo().Hostname()
 					}
 					addrs := make([]string, p.Addresses().Len())
-					for i, ap := range p.Addresses().All() {
-						addrs[i] = ap.Addr().String()
+					for idx, ap := range p.Addresses().All() {
+						addrs[idx] = ap.Addr().String()
 					}
+
+					// Peer peerAPI URL from the peer's advertised Services.
+					peerURL := buildPeerAPIURL(p, selfHave4, selfHave6)
+
 					return jsNetMapPeerNode{
 						jsNetMapNode: jsNetMapNode{
 							Name:       name,
 							Addresses:  addrs,
 							MachineKey: p.Machine().String(),
 							NodeKey:    p.Key().String(),
+							PeerAPIURL: peerURL,
 						},
 						Online:              p.Online().Clone(),
 						TailscaleSSHEnabled: p.Hostinfo().TailscaleSSHEnabled(),
+						ExitNodeOption:      tsaddr.ContainsExitRoutes(p.AllowedIPs()),
+						StableNodeID:        string(p.StableID()),
 					}
 				}),
 				LockedOut: nm.TKAEnabled && nm.SelfNode.KeySignature().Len() == 0,
@@ -343,9 +512,52 @@ func (i *jsIPN) run(jsCallbacks js.Value) {
 				log.Printf("Could not generate JSON netmap: %v", err)
 			}
 		}
+		if n.Prefs != nil && n.Prefs.Valid() {
+			jsCallbacks.Call("notifyExitNode", string(n.Prefs.ExitNodeID()))
+		}
 		if n.BrowseToURL != nil {
 			jsCallbacks.Call("notifyBrowseToURL", *n.BrowseToURL)
 		}
+		if n.FilesWaiting != nil {
+			jsCallbacks.Call("notifyFilesWaiting")
+		}
+		if n.IncomingFiles != nil {
+			files := make([]jsIncomingFile, len(n.IncomingFiles))
+			for i, f := range n.IncomingFiles {
+				files[i] = jsIncomingFile{
+					Name:         f.Name,
+					Started:      f.Started.UnixMilli(),
+					DeclaredSize: f.DeclaredSize,
+					Received:     f.Received,
+					Done:         f.Done,
+				}
+			}
+			if b, err := json.Marshal(files); err == nil {
+				jsCallbacks.Call("notifyIncomingFiles", string(b))
+			} else {
+				log.Printf("could not marshal IncomingFiles: %v", err)
+			}
+		}
+		if n.OutgoingFiles != nil {
+			files := make([]jsOutgoingFile, len(n.OutgoingFiles))
+			for i, f := range n.OutgoingFiles {
+				files[i] = jsOutgoingFile{
+					ID:           f.ID,
+					PeerID:       string(f.PeerID),
+					Name:         f.Name,
+					Started:      f.Started.UnixMilli(),
+					DeclaredSize: f.DeclaredSize,
+					Sent:         f.Sent,
+					Finished:     f.Finished,
+					Succeeded:    f.Succeeded,
+				}
+			}
+			if b, err := json.Marshal(files); err == nil {
+				jsCallbacks.Call("notifyOutgoingFiles", string(b))
+			} else {
+				log.Printf("could not marshal OutgoingFiles: %v", err)
+			}
+		}
 	})
 
 	go func() {
@@ -576,6 +788,24 @@ func (i *jsIPN) fetch(url string) js.Value {
 	})
 }
 
+func (i *jsIPN) setExitNode(stableNodeID string) js.Value {
+	return makePromise(func() (any, error) {
+		mp := &ipn.MaskedPrefs{
+			ExitNodeIDSet: true,
+			Prefs:         ipn.Prefs{ExitNodeID: tailcfg.StableNodeID(stableNodeID)},
+		}
+		_, err := i.lb.EditPrefs(mp)
+		return nil, err
+	})
+}
+
+func (i *jsIPN) setExitNodeEnabled(enabled bool) js.Value {
+	return makePromise(func() (any, error) {
+		_, err := i.lb.SetUseExitNodeEnabled(ipnauth.Self, enabled)
+		return nil, err
+	})
+}
+
 func (i *jsIPN) dial(network, addr string) js.Value {
 	return makePromise(func() (any, error) {
 		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
@@ -691,6 +921,437 @@ func (i *jsIPN) listenICMP(network string) js.Value {
 	})
 }
 
+func (i *jsIPN) getCert() js.Value {
+	return makePromise(func() (any, error) {
+		nm := i.lb.NetMap()
+		if nm == nil {
+			return nil, errors.New("getCert: no network map available")
+		}
+		certDomains := nm.DNS.CertDomains
+		if len(certDomains) == 0 {
+			return nil, errors.New("getCert: this tailnet does not support TLS certificates")
+		}
+		pair, err := i.lb.GetCertPEM(context.Background(), certDomains[0])
+		if err != nil {
+			return nil, err
+		}
+		return map[string]any{
+			"certPEM": string(pair.CertPEM),
+			"keyPEM":  string(pair.KeyPEM),
+		}, nil
+	})
+}
+
+func (i *jsIPN) listenTLS(addr, certPEM, keyPEM string) js.Value {
+	return makePromise(func() (any, error) {
+		cert, err := tls.X509KeyPair([]byte(certPEM), []byte(keyPEM))
+		if err != nil {
+			return nil, fmt.Errorf("listenTLS: parsing cert/key: %w", err)
+		}
+		tlsCfg := &tls.Config{Certificates: []tls.Certificate{cert}}
+
+		tcpLn, err := i.ns.ListenTCP("tcp4", addr)
+		if err != nil {
+			return nil, err
+		}
+
+		// Determine the actual port (handles ":0" ephemeral assignment).
+		// Use SplitHostPort rather than netip.ParseAddrPort because gVisor
+		// may return ":443" (empty host) which ParseAddrPort rejects.
+		_, portStr, err := net.SplitHostPort(tcpLn.Addr().String())
+		if err != nil {
+			tcpLn.Close()
+			return nil, fmt.Errorf("listenTLS: getting port from listener addr: %w", err)
+		}
+		portNum, err := strconv.ParseUint(portStr, 10, 16)
+		if err != nil {
+			tcpLn.Close()
+			return nil, fmt.Errorf("listenTLS: parsing port %q: %w", portStr, err)
+		}
+		port := uint16(portNum)
+
+		// Register a Funnel entry so handleFunnelTCP can route to this listener.
+		entry := &funnelListenerEntry{
+			ch:     make(chan net.Conn, 8),
+			tlsCfg: tlsCfg,
+		}
+		i.funnelMu.Lock()
+		i.funnelPorts[port] = entry
+		i.funnelMu.Unlock()
+
+		ln := newCombinedTLSListener(tcpLn, tlsCfg, entry.ch, port, i)
+		return wrapTCPListener(ln), nil
+	})
+}
+
+// handleFunnelTCP is registered with LocalBackend.SetTCPHandlerForFunnelFlow.
+// It routes incoming Funnel connections to the matching listenTLS listener.
+func (i *jsIPN) handleFunnelTCP(src netip.AddrPort, dstPort uint16) func(net.Conn) {
+	i.funnelMu.Lock()
+	entry := i.funnelPorts[dstPort]
+	i.funnelMu.Unlock()
+	if entry == nil {
+		return nil
+	}
+	return func(conn net.Conn) {
+		tlsConn := tls.Server(conn, entry.tlsCfg)
+		select {
+		case entry.ch <- tlsConn:
+		default:
+			// Channel full; drop the connection rather than block.
+			conn.Close()
+		}
+	}
+}
+
+// combinedTLSListener merges TLS connections from the local netstack (direct
+// tailnet access) and from Funnel ingress into a single net.Listener.
+type combinedTLSListener struct {
+	tcpLn      net.Listener
+	tlsCfg     *tls.Config
+	funnelCh   <-chan net.Conn
+	port       uint16
+	ipn        *jsIPN
+	netstackCh chan net.Conn
+	errCh      chan error
+	done       chan struct{}
+	closeOnce  sync.Once
+}
+
+func newCombinedTLSListener(tcpLn net.Listener, tlsCfg *tls.Config, funnelCh <-chan net.Conn, port uint16, ipn *jsIPN) *combinedTLSListener {
+	l := &combinedTLSListener{
+		tcpLn:      tcpLn,
+		tlsCfg:     tlsCfg,
+		funnelCh:   funnelCh,
+		port:       port,
+		ipn:        ipn,
+		netstackCh: make(chan net.Conn, 8),
+		errCh:      make(chan error, 1),
+		done:       make(chan struct{}),
+	}
+	go l.drainNetstack()
+	return l
+}
+
+func (l *combinedTLSListener) drainNetstack() {
+	for {
+		conn, err := l.tcpLn.Accept()
+		if err != nil {
+			select {
+			case l.errCh <- err:
+			default:
+			}
+			return
+		}
+		tlsConn := tls.Server(conn, l.tlsCfg)
+		select {
+		case l.netstackCh <- tlsConn:
+		case <-l.done:
+			conn.Close()
+			return
+		}
+	}
+}
+
+func (l *combinedTLSListener) Accept() (net.Conn, error) {
+	select {
+	case conn := <-l.funnelCh:
+		return conn, nil
+	case conn := <-l.netstackCh:
+		return conn, nil
+	case err := <-l.errCh:
+		return nil, err
+	case <-l.done:
+		return nil, net.ErrClosed
+	}
+}
+
+func (l *combinedTLSListener) Close() error {
+	l.closeOnce.Do(func() {
+		close(l.done)
+		l.tcpLn.Close()
+		l.ipn.funnelMu.Lock()
+		delete(l.ipn.funnelPorts, l.port)
+		l.ipn.funnelMu.Unlock()
+	})
+	return nil
+}
+
+func (l *combinedTLSListener) Addr() net.Addr {
+	return l.tcpLn.Addr()
+}
+
+func (i *jsIPN) setFunnel(hostname string, port uint16, enabled bool) js.Value {
+	return makePromise(func() (any, error) {
+		hp := ipn.HostPort(fmt.Sprintf("%s:%d", hostname, port))
+		var cfg *ipn.ServeConfig
+		if enabled {
+			cfg = &ipn.ServeConfig{
+				AllowFunnel: map[ipn.HostPort]bool{hp: true},
+			}
+		} else {
+			cfg = &ipn.ServeConfig{}
+		}
+		return nil, i.lb.SetServeConfig(cfg, "")
+	})
+}
+
+func (i *jsIPN) whoIs(addr string, proto string) js.Value {
+	return makePromise(func() (any, error) {
+		// Accept both "ip:port" and bare "ip" (port 0 still resolves by IP).
+		var ipp netip.AddrPort
+		if ap, err := netip.ParseAddrPort(addr); err == nil {
+			ipp = ap
+		} else if ip, err := netip.ParseAddr(addr); err == nil {
+			ipp = netip.AddrPortFrom(ip, 0)
+		} else {
+			return nil, fmt.Errorf("whoIs: invalid address %q (want ip:port or ip)", addr)
+		}
+		n, u, ok := i.lb.WhoIs(proto, ipp)
+		if !ok {
+			return nil, nil
+		}
+		addrs := make([]any, n.Addresses().Len())
+		for idx, ap := range n.Addresses().All() {
+			addrs[idx] = ap.Addr().String()
+		}
+		return map[string]any{
+			"node": map[string]any{
+				"id":        string(n.StableID()),
+				"name":      n.Name(),
+				"addresses": addrs,
+			},
+			"user": map[string]any{
+				"id":            int64(u.ID),
+				"loginName":     u.LoginName,
+				"displayName":   u.DisplayName,
+				"profilePicURL": u.ProfilePicURL,
+			},
+		}, nil
+	})
+}
+
+func (i *jsIPN) queryDNS(name string, queryType int) js.Value {
+	return makePromise(func() (any, error) {
+		res, resolvers, err := i.lb.QueryDNS(name, dnsmessage.Type(queryType))
+
+		// Detect SERVFAIL with no upstream resolvers (common when an exit node is
+		// active but the DNS manager forwarder has no configured upstreams). Fall
+		// back to querying 8.8.8.8 via the dialer (which routes through the exit
+		// node), then as a last resort use the browser's default name resolver.
+		needsFallback := err != nil
+		if !needsFallback && len(resolvers) == 0 && len(res) > 0 {
+			var hdrParser dnsmessage.Parser
+			if hdr, hdrErr := hdrParser.Start(res); hdrErr == nil && hdr.RCode == dnsmessage.RCodeServerFailure {
+				needsFallback = true
+			}
+		}
+		if needsFallback {
+			qt := dnsmessage.Type(queryType)
+			if qt != dnsmessage.TypeA && qt != dnsmessage.TypeAAAA {
+				if err != nil {
+					return nil, fmt.Errorf("queryDNS: %w (no upstream resolver; only A/AAAA queries support fallback)", err)
+				}
+				return nil, fmt.Errorf("queryDNS: no upstream resolver available; only A/AAAA queries support fallback lookup")
+			}
+			ctx := context.Background()
+			d := i.dialer
+			r := &net.Resolver{
+				PreferGo: true,
+				Dial: func(rctx context.Context, network, address string) (net.Conn, error) {
+					return d.UserDial(rctx, "tcp", "8.8.8.8:53")
+				},
+			}
+			ips, rerr := r.LookupIPAddr(ctx, name)
+			if rerr != nil {
+				// Last resort: browser-native resolution (no exit-node routing).
+				ips, rerr = (&net.Resolver{PreferGo: false}).LookupIPAddr(ctx, name)
+				if rerr != nil {
+					return nil, fmt.Errorf("queryDNS: fallback resolution failed: %w", rerr)
+				}
+			}
+			var answers []any
+			for _, ia := range ips {
+				ip, ok := netip.AddrFromSlice(ia.IP)
+				if !ok {
+					continue
+				}
+				ip = ip.Unmap()
+				if qt == dnsmessage.TypeA && ip.Is4() {
+					answers = append(answers, ip.String())
+				} else if qt == dnsmessage.TypeAAAA && ip.Is6() {
+					answers = append(answers, ip.String())
+				}
+			}
+			return map[string]any{
+				"answers":   answers,
+				"resolvers": []any{},
+			}, nil
+		}
+
+		var p dnsmessage.Parser
+		if _, err := p.Start(res); err != nil {
+			return nil, fmt.Errorf("queryDNS: parsing response: %w", err)
+		}
+		if err := p.SkipAllQuestions(); err != nil {
+			return nil, fmt.Errorf("queryDNS: skipping questions: %w", err)
+		}
+		var answers []any
+		for {
+			h, err := p.AnswerHeader()
+			if err == dnsmessage.ErrSectionDone {
+				break
+			}
+			if err != nil {
+				return nil, fmt.Errorf("queryDNS: reading answer: %w", err)
+			}
+			switch h.Type {
+			case dnsmessage.TypeA:
+				r, err := p.AResource()
+				if err != nil {
+					return nil, fmt.Errorf("queryDNS: reading A record: %w", err)
+				}
+				answers = append(answers, netip.AddrFrom4(r.A).String())
+			case dnsmessage.TypeAAAA:
+				r, err := p.AAAAResource()
+				if err != nil {
+					return nil, fmt.Errorf("queryDNS: reading AAAA record: %w", err)
+				}
+				answers = append(answers, netip.AddrFrom16(r.AAAA).String())
+			case dnsmessage.TypeCNAME:
+				r, err := p.CNAMEResource()
+				if err != nil {
+					return nil, fmt.Errorf("queryDNS: reading CNAME record: %w", err)
+				}
+				answers = append(answers, r.CNAME.String())
+			case dnsmessage.TypeTXT:
+				r, err := p.TXTResource()
+				if err != nil {
+					return nil, fmt.Errorf("queryDNS: reading TXT record: %w", err)
+				}
+				for _, s := range r.TXT {
+					answers = append(answers, s)
+				}
+			default:
+				if err := p.SkipAnswer(); err != nil {
+					return nil, fmt.Errorf("queryDNS: skipping unknown answer: %w", err)
+				}
+			}
+		}
+		resolverAddrs := make([]any, len(resolvers))
+		for idx, r := range resolvers {
+			resolverAddrs[idx] = r.Addr
+		}
+		return map[string]any{
+			"answers":   answers,
+			"resolvers": resolverAddrs,
+		}, nil
+	})
+}
+
+func (i *jsIPN) ping(ip string, pingType string, size int) js.Value {
+	return makePromise(func() (any, error) {
+		addr, err := netip.ParseAddr(ip)
+		if err != nil {
+			return nil, fmt.Errorf("ping: invalid IP %q: %w", ip, err)
+		}
+		switch tailcfg.PingType(pingType) {
+		case tailcfg.PingDisco, tailcfg.PingTSMP, tailcfg.PingICMP, tailcfg.PingPeerAPI:
+			// valid
+		default:
+			return nil, fmt.Errorf("ping: unknown type %q, must be one of: disco, TSMP, ICMP, peerapi", pingType)
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+		pr, err := i.lb.Ping(ctx, addr, tailcfg.PingType(pingType), size)
+		if err != nil {
+			return nil, err
+		}
+		result := map[string]any{
+			"ip":             pr.IP,
+			"nodeIP":         pr.NodeIP,
+			"nodeName":       pr.NodeName,
+			"latencySeconds": pr.LatencySeconds,
+			"endpoint":       pr.Endpoint,
+			"derpRegionID":   pr.DERPRegionID,
+			"derpRegionCode": pr.DERPRegionCode,
+			"peerAPIURL":     pr.PeerAPIURL,
+			"isLocalIP":      pr.IsLocalIP,
+		}
+		if pr.Err != "" {
+			result["err"] = pr.Err
+		}
+		return result, nil
+	})
+}
+
+func (i *jsIPN) suggestExitNode() js.Value {
+	return makePromise(func() (any, error) {
+		resp, err := i.lb.SuggestExitNode()
+		if err != nil {
+			return nil, err
+		}
+		result := map[string]any{
+			"id":   string(resp.ID),
+			"name": resp.Name,
+		}
+		if l := resp.Location; l.Valid() {
+			result["location"] = map[string]any{
+				"country":     l.Country(),
+				"countryCode": l.CountryCode(),
+				"city":        l.City(),
+				"cityCode":    l.CityCode(),
+				"latitude":    l.Latitude(),
+				"longitude":   l.Longitude(),
+			}
+		}
+		return result, nil
+	})
+}
+
+func (i *jsIPN) localAPI(method, path, body string) js.Value {
+	return makePromise(func() (any, error) {
+		h := localapi.NewHandler(localapi.HandlerConfig{
+			Actor: &ipnauth.TestActor{
+				Name:       "wasm",
+				LocalAdmin: true,
+			},
+			Backend:  i.lb,
+			Logf:     log.Printf,
+			LogID:    i.logID,
+			EventBus: i.lb.Sys().Bus.Get(),
+		})
+		h.PermitRead = true
+		h.PermitWrite = true
+		h.PermitCert = true
+
+		var bodyReader io.Reader
+		if body != "" {
+			bodyReader = strings.NewReader(body)
+		}
+		req, err := http.NewRequest(method, "http://local-tailscaled.sock"+path, bodyReader)
+		if err != nil {
+			return nil, fmt.Errorf("localAPI: %w", err)
+		}
+		// Empty Host passes the validHost check in the LocalAPI handler.
+		req.Host = ""
+		if body != "" {
+			req.Header.Set("Content-Type", "application/json")
+		}
+		w := httptest.NewRecorder()
+		h.ServeHTTP(w, req)
+		resp := w.Result()
+		respBody, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return nil, fmt.Errorf("localAPI: reading response: %w", err)
+		}
+		return map[string]any{
+			"status": resp.StatusCode,
+			"body":   string(respBody),
+		}, nil
+	})
+}
+
 // wrapConn exposes a net.Conn to JavaScript with binary (Uint8Array) I/O.
 func wrapConn(conn net.Conn) map[string]any {
 	return map[string]any{
@@ -855,6 +1516,29 @@ func (w termWriter) Write(p []byte) (n int, err error) {
 	return len(p), nil
 }
 
+// jsIncomingFile is the JSON representation of an in-progress inbound file
+// transfer sent to the notifyIncomingFiles callback.
+type jsIncomingFile struct {
+	Name         string `json:"name"`
+	Started      int64  `json:"started"`      // Unix milliseconds; use new Date(started) in JS
+	DeclaredSize int64  `json:"declaredSize"` // -1 if unknown
+	Received     int64  `json:"received"`     // bytes received so far
+	Done         bool   `json:"done"`         // true once the file has been fully received
+}
+
+// jsOutgoingFile is the JSON representation of an outgoing file transfer
+// sent to the notifyOutgoingFiles callback.
+type jsOutgoingFile struct {
+	ID           string `json:"id"`
+	PeerID       string `json:"peerID"`
+	Name         string `json:"name"`
+	Started      int64  `json:"started"`      // Unix milliseconds
+	DeclaredSize int64  `json:"declaredSize"` // -1 if unknown
+	Sent         int64  `json:"sent"`         // bytes sent so far
+	Finished     bool   `json:"finished"`
+	Succeeded    bool   `json:"succeeded"` // only meaningful when finished
+}
+
 type jsNetMap struct {
 	Self      jsNetMapSelfNode   `json:"self"`
 	Peers     []jsNetMapPeerNode `json:"peers"`
@@ -862,10 +1546,11 @@ type jsNetMap struct {
 }
 
 type jsNetMapNode struct {
-	Name       string   `json:"name"`
-	Addresses  []string `json:"addresses"`
-	MachineKey string   `json:"machineKey"`
-	NodeKey    string   `json:"nodeKey"`
+	Name        string   `json:"name"`
+	Addresses   []string `json:"addresses"`
+	MachineKey  string   `json:"machineKey"`
+	NodeKey     string   `json:"nodeKey"`
+	PeerAPIURL  string   `json:"peerAPIURL,omitempty"`
 }
 
 type jsNetMapSelfNode struct {
@@ -875,8 +1560,10 @@ type jsNetMapSelfNode struct {
 
 type jsNetMapPeerNode struct {
 	jsNetMapNode
-	Online              *bool `json:"online,omitempty"`
-	TailscaleSSHEnabled bool  `json:"tailscaleSSHEnabled"`
+	Online              *bool  `json:"online,omitempty"`
+	TailscaleSSHEnabled bool   `json:"tailscaleSSHEnabled"`
+	ExitNodeOption      bool   `json:"exitNodeOption"`
+	StableNodeID        string `json:"stableNodeID"`
 }
 
 type jsStateStore struct {

feature/taildrop/ext.go

@@ -76,6 +76,12 @@ type Extension struct {
 	// This is currently being used for Android to use the Storage Access Framework.
 	fileOps FileOps
 
+	// directFileOps, when true, means that files received via fileOps should be
+	// delivered directly to the caller (DirectFileMode=true). Set by SetFileOps.
+	// SetStagedFileOps leaves this false so that received files are staged for
+	// explicit retrieval via WaitingFiles/OpenFile (used by the WASM JS bridge).
+	directFileOps bool
+
 	nodeBackendForTest ipnext.NodeBackend // if non-nil, pretend we're this node state for tests
 
 	mu             sync.Mutex // Lock order: lb.mu > e.mu
@@ -155,9 +161,10 @@ func (e *Extension) onChangeProfile(profile ipn.LoginProfileView, _ ipn.PrefsVie
 	// Use the provided [FileOps] implementation (typically for SAF access on Android),
 	// or create an [fsFileOps] instance rooted at fileRoot.
 	//
-	// A non-nil [FileOps] also implies that we are in DirectFileMode.
+	// A non-nil [FileOps] with directFileOps=true implies DirectFileMode (Android SAF).
+	// A non-nil [FileOps] with directFileOps=false uses staged mode (WASM JS bridge).
 	fops := e.fileOps
-	isDirectFileMode := fops != nil
+	isDirectFileMode := fops != nil && e.directFileOps
 	if fops == nil {
 		var fileRoot string
 		if fileRoot, isDirectFileMode = e.fileRoot(uid, activeLogin); fileRoot == "" {
@@ -411,6 +418,13 @@ func (e *Extension) taildropTargetStatus(p tailcfg.NodeView, nb ipnext.NodeBacke
 	return ipnstate.TaildropTargetAvailable
 }
 
+// UpdateOutgoingFiles updates the tracked set of outgoing file transfers and
+// sends an ipn.Notify with the full merged list. The updates map is keyed by
+// OutgoingFile.ID; existing entries not present in updates are preserved.
+func (e *Extension) UpdateOutgoingFiles(updates map[string]*ipn.OutgoingFile) {
+	e.updateOutgoingFiles(updates)
+}
+
 // updateOutgoingFiles updates b.outgoingFiles to reflect the given updates and
 // sends an ipn.Notify with the full list of outgoingFiles.
 func (e *Extension) updateOutgoingFiles(updates map[string]*ipn.OutgoingFile) {

feature/taildrop/fileops_fs.go

@@ -1,6 +1,6 @@
 // Copyright (c) Tailscale Inc & contributors
 // SPDX-License-Identifier: BSD-3-Clause
-//go:build !android
+//go:build !android && !js
 
 package taildrop
 

feature/taildrop/fileops_js.go

@@ -0,0 +1,16 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build js
+
+package taildrop
+
+import "errors"
+
+func init() {
+	// On WASM there is no real filesystem. newFileOps is only reached when
+	// SetFileOps was not called; return a clear error rather than panicking.
+	newFileOps = func(dir string) (FileOps, error) {
+		return nil, errors.New("taildrop: no filesystem on WASM; provide fileOps in the IPN config")
+	}
+}

feature/taildrop/paths.go

@@ -18,10 +18,21 @@ func (e *Extension) SetDirectFileRoot(root string) {
 	e.directFileRoot = root
 }
 
-// SetFileOps sets the platform specific file operations. This is used
+// SetFileOps sets the platform-specific file operations. This is used
 // to call Android's Storage Access Framework APIs.
+// It implies DirectFileMode, so received files are delivered directly to the
+// caller rather than staged for retrieval via WaitingFiles/OpenFile.
 func (e *Extension) SetFileOps(fileOps FileOps) {
 	e.fileOps = fileOps
+	e.directFileOps = true
+}
+
+// SetStagedFileOps sets the platform-specific file operations without enabling
+// DirectFileMode. Received files are staged for explicit retrieval via
+// WaitingFiles, OpenFile, and DeleteFile. Used by the WASM JS bridge.
+func (e *Extension) SetStagedFileOps(fileOps FileOps) {
+	e.fileOps = fileOps
+	e.directFileOps = false
 }
 
 func (e *Extension) setPlatformDefaultDirectFileRoot() {

feature/taildrop/send.go

@@ -134,8 +134,9 @@ func (m *manager) PutFile(id clientID, baseName string, r io.Reader, offset, len
 		}
 	}
 
-	// Copy the contents of the file to the writer.
-	copyLength, err := io.Copy(wc, r)
+	// Copy via inFile (which wraps wc) so [incomingFile.Write] can track
+	// progress and fire periodic sendFileNotify callbacks.
+	copyLength, err := io.Copy(inFile, r)
 	if err != nil {
 		return 0, m.redactAndLogError("Copy", err)
 	}

ipn/ipnlocal/cert.go

@@ -1,7 +1,7 @@
 // Copyright (c) Tailscale Inc & contributors
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:build !js && !ts_omit_acme
+//go:build !ts_omit_acme
 
 package ipnlocal
 
@@ -302,6 +302,9 @@ var errCertExpired = errors.New("cert expired")
 var testX509Roots *x509.CertPool // set non-nil by tests
 
 func (b *LocalBackend) getCertStore() (certStore, error) {
+	if runtime.GOOS == "js" {
+		return certStateStore{StateStore: b.store}, nil
+	}
 	switch b.store.(type) {
 	case *store.FileStore:
 	case *mem.Store:
@@ -333,6 +336,16 @@ func (b *LocalBackend) ConfigureCertsForTest(getCert func(hostname string) (*TLS
 	b.mu.Unlock()
 }
 
+// SetACMEHTTPClient sets a custom HTTP client for ACME certificate operations.
+// On js/wasm, this can be used to route requests through the Tailscale network
+// stack to bypass browser CORS if Let's Encrypt endpoints fail preflight.
+// A nil value (the default) uses the standard http.DefaultClient.
+func (b *LocalBackend) SetACMEHTTPClient(c *http.Client) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.acmeHTTPClient = c
+}
+
 // certFileStore implements certStore by storing the cert & key files in the named directory.
 type certFileStore struct {
 	dir string
@@ -550,6 +563,9 @@ var getCertPEM = func(ctx context.Context, b *LocalBackend, cs certStore, logf l
 	if err != nil {
 		return nil, err
 	}
+	b.mu.Lock()
+	ac.HTTPClient = b.acmeHTTPClient
+	b.mu.Unlock()
 
 	if !isDefaultDirectoryURL(ac.DirectoryURL) {
 		logf("acme: using Directory URL %q", ac.DirectoryURL)

ipn/ipnlocal/cert_disabled.go

@@ -1,7 +1,7 @@
 // Copyright (c) Tailscale Inc & contributors
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:build js || ts_omit_acme
+//go:build ts_omit_acme
 
 package ipnlocal
 

ipn/ipnlocal/local.go

@@ -412,6 +412,10 @@ type LocalBackend struct {
 	// See [LocalBackend.ConfigureCertsForTest].
 	getCertForTest func(hostname string) (*TLSCertKeyPair, error)
 
+	// acmeHTTPClient, if non-nil, is used for all ACME HTTP requests instead
+	// of http.DefaultClient. Set via SetACMEHTTPClient before first cert use.
+	acmeHTTPClient *http.Client
+
 	// existsPendingAuthReconfig tracks if a goroutine is waiting to
 	// acquire [LocalBackend]'s mutex inside of [LocalBackend.AuthReconfig].
 	// It is used to prevent goroutines from piling up to do the same

ipn/ipnlocal/serve.go

@@ -393,6 +393,11 @@ func (b *LocalBackend) setServeConfigLocked(config *ipn.ServeConfig, etag string
 		}
 	}
 
+	// Notify the control plane immediately so that changes to IngressEnabled /
+	// WireIngress (required for Funnel DNS provisioning) are not delayed until
+	// the next periodic heartbeat.
+	b.authReconfigLocked()
+
 	return nil
 }