ipn/ipnlocal/peerapi: refactoring taildrop to just one endpoint (#9832)

Updates #14772

Signed-off-by: Rhea Ghosh <rhea@tailscale.com>

ipn/ipnlocal/peerapi.go

@@ -305,12 +305,10 @@ func (h *peerAPIHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("X-Frame-Options", "DENY")
 		w.Header().Set("X-Content-Type-Options", "nosniff")
 	}
-	if strings.HasPrefix(r.URL.Path, "/v0/partial-files/") {
-		h.handlePartialFileGet(w, r)
-		return
-	}
 	if strings.HasPrefix(r.URL.Path, "/v0/put/") {
+		if r.Method == "PUT" {
 			metricPutCalls.Add(1)
+		}
 		h.handlePeerPut(w, r)
 		return
 	}
@@ -631,45 +629,35 @@ func (h *peerAPIHandler) peerHasCap(wantCap tailcfg.PeerCapability) bool {
 	return h.ps.b.PeerCaps(h.remoteAddr.Addr()).HasCapability(wantCap)
 }
 
-var errMisconfiguredInternals = errors.New("misconfigured internals")
-
-func (h *peerAPIHandler) extractBaseName(rawPath, prefix string) (ret string, err error) {
-	prefix, ok := strings.CutPrefix(rawPath, prefix)
-	if !ok {
-		return "", errMisconfiguredInternals
-	}
-	if prefix == "" {
-		return "", taildrop.ErrInvalidFileName
-	}
-	if strings.Contains(prefix, "/") {
-		return "", taildrop.ErrInvalidFileName
-	}
-	baseName, err := url.PathUnescape(prefix)
-	if err == errMisconfiguredInternals {
-		return "", errMisconfiguredInternals
-	} else if err != nil {
-		return "", taildrop.ErrInvalidFileName
+func (h *peerAPIHandler) handlePeerPut(w http.ResponseWriter, r *http.Request) {
+	if !h.canPutFile() {
+		http.Error(w, taildrop.ErrNoTaildrop.Error(), http.StatusForbidden)
+		return
 	}
-	return baseName, nil
-}
-
-func (h *peerAPIHandler) handlePartialFileGet(w http.ResponseWriter, r *http.Request) {
 	if !h.ps.b.hasCapFileSharing() {
 		http.Error(w, taildrop.ErrNoTaildrop.Error(), http.StatusForbidden)
 		return
 	}
-	if r.Method != "GET" {
-		http.Error(w, "expected method GET", http.StatusMethodNotAllowed)
+	rawPath := r.URL.EscapedPath()
+	prefix, ok := strings.CutPrefix(rawPath, "/v0/put/")
+	if !ok {
+		http.Error(w, "misconfigured internals", http.StatusForbidden)
+		return
+	}
+	baseName, err := url.PathUnescape(prefix)
+	if err != nil {
+		http.Error(w, taildrop.ErrInvalidFileName.Error(), http.StatusBadRequest)
 		return
 	}
+	switch r.Method {
+	case "GET":
 		var resp any
 		var err error
 		id := taildrop.ClientID(h.peerNode.StableID())
 
-	if r.URL.Path == "/v0/partial-files/" {
+		if r.URL.Path == "/v0/put/"+baseName {
 			resp, err = h.ps.taildrop.PartialFiles(id)
 		} else {
-		baseName, _ := h.extractBaseName(r.URL.EscapedPath(), "/v0/partial-files/")
 			ranges, ok := httphdr.ParseRange(r.Header.Get("Range"))
 			if !ok || len(ranges) != 1 || ranges[0].Length < 0 {
 				http.Error(w, "invalid Range header", http.StatusBadRequest)
@@ -690,27 +678,7 @@ func (h *peerAPIHandler) handlePartialFileGet(w http.ResponseWriter, r *http.Req
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
 		}
-
-}
-
-func (h *peerAPIHandler) handlePeerPut(w http.ResponseWriter, r *http.Request) {
-	if !h.canPutFile() {
-		http.Error(w, taildrop.ErrNoTaildrop.Error(), http.StatusForbidden)
-		return
-	}
-	if !h.ps.b.hasCapFileSharing() {
-		http.Error(w, "file sharing not enabled by Tailscale admin", http.StatusForbidden)
-		return
-	}
-	if r.Method != "PUT" {
-		http.Error(w, "expected method PUT", http.StatusMethodNotAllowed)
-		return
-	}
-	baseName, err := h.extractBaseName(r.URL.EscapedPath(), "/v0/put/")
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
-		return
-	}
+	case "PUT":
 		t0 := h.ps.b.clock.Now()
 		id := taildrop.ClientID(h.peerNode.StableID())
 
@@ -738,6 +706,9 @@ func (h *peerAPIHandler) handlePeerPut(w http.ResponseWriter, r *http.Request) {
 		default:
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 		}
+	default:
+		http.Error(w, "expected method GET or PUT", http.StatusMethodNotAllowed)
+	}
 }
 
 func approxSize(n int64) string {

ipn/ipnlocal/peerapi_test.go

@@ -183,7 +183,7 @@ func TestHandlePeerAPI(t *testing.T) {
 			reqs:       []*http.Request{httptest.NewRequest("PUT", "/v0/put/foo", nil)},
 			checks: checks(
 				httpStatus(http.StatusForbidden),
-				bodyContains("file sharing not enabled by Tailscale admin"),
+				bodyContains("Taildrop disabled"),
 			),
 		},
 		{
@@ -204,7 +204,7 @@ func TestHandlePeerAPI(t *testing.T) {
 			reqs:       []*http.Request{httptest.NewRequest("POST", "/v0/put/foo", nil)},
 			checks: checks(
 				httpStatus(405),
-				bodyContains("expected method PUT"),
+				bodyContains("expected method GET or PUT"),
 			),
 		},
 		{

ipn/localapi/localapi.go

@@ -1325,7 +1325,7 @@ func (h *Handler) serveFilePut(w http.ResponseWriter, r *http.Request) {
 			Transport: h.b.Dialer().PeerAPITransport(),
 			Timeout:   10 * time.Second,
 		}
-		req, err := http.NewRequestWithContext(r.Context(), "GET", "http://peer/v0/partial-files/"+filenameEscaped, nil)
+		req, err := http.NewRequestWithContext(r.Context(), "GET", "http://peer/v0/put/"+filenameEscaped, nil)
 		if err != nil {
 			return taildrop.FileChecksums{}, err
 		}