client/web: pass URL prefix to frontend

This allows wouter to route URLs properly when running in CGI mode.

Updates tailscale/corp#14335

Signed-off-by: Will Norris <will@tailscale.com>

client/web/src/components/app.tsx

@@ -8,7 +8,7 @@ import useAuth, { AuthResponse } from "src/hooks/auth"
 import useNodeData, { NodeData, NodeUpdate } from "src/hooks/node-data"
 import { ReactComponent as TailscaleIcon } from "src/icons/tailscale-icon.svg"
 import ProfilePic from "src/ui/profile-pic"
-import { Link, Route, Switch, useLocation } from "wouter"
+import { Link, Route, Router, Switch, useLocation } from "wouter"
 import DeviceDetailsView from "./views/device-details-view"
 
 export default function App() {
@@ -46,6 +46,7 @@ function WebClient({
       {/* TODO(sonia): get rid of the conditions here once full/readonly
        * views live on same components */}
       {data.DebugMode === "full" && auth?.ok && <Header node={data} />}
+      <Router base={data.URLPrefix}>
         <Switch>
           <Route path="/">
             <HomeView
@@ -70,6 +71,7 @@ function WebClient({
             <h2 className="mt-8">Page not found</h2>
           </Route>
         </Switch>
+      </Router>
     </>
   )
 }

client/web/src/hooks/node-data.ts

@@ -15,6 +15,7 @@ export type NodeData = {
   IsUnraid: boolean
   UnraidToken: string
   IPNVersion: string
+  URLPrefix: string
 
   DebugMode: "" | "login" | "full" // empty when not running in any debug mode
 }

client/web/web.go

@@ -504,6 +504,7 @@ type nodeData struct {
 	UnraidToken       string
 	IPNVersion        string
 	DebugMode         string // empty when not running in any debug mode
+	URLPrefix         string // if set, the URL prefix the client is served behind
 }
 
 func (s *Server) serveGetNodeData(w http.ResponseWriter, r *http.Request) {
@@ -537,6 +538,7 @@ func (s *Server) serveGetNodeData(w http.ResponseWriter, r *http.Request) {
 		IsUnraid:    distro.Get() == distro.Unraid,
 		UnraidToken: os.Getenv("UNRAID_CSRF_TOKEN"),
 		IPNVersion:  versionShort,
+		URLPrefix:   strings.TrimSuffix(s.pathPrefix, "/"),
 		DebugMode:   debugMode, // TODO(sonia,will): just pass back s.mode directly?
 	}
 	for _, r := range prefs.AdvertiseRoutes {