Provide a dedicated API endpoint for app FQDN resolving (#6449)

Currently, an app's target FQDN can be obtained only using the endpoint for creating new app sessions. The OAuth-style back-and-forth redirects between the app launcher and the app itself are therefore forced to generate an unnecessary additional app session just to resolve the FQDN. The new endpoint introduced here allows to resolve such FQDNs by invoking a dedicated endpoint.
gravitational · Apr 28, 2021 · 760c5d9 · 760c5d9
1 parent 41660eb
commit 760c5d9
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Showing 5 changed files with 97 additions and 43 deletions.
diff --git a/integration/app_integration_test.go b/integration/app_integration_test.go
@@ -765,7 +765,7 @@ func (p *pack) createAppSession(t *testing.T, publicAddr, clusterName string) st
 	require.NotEmpty(t, p.webToken)
 
 	casReq, err := json.Marshal(web.CreateAppSessionRequest{
-		FQDN:        publicAddr,
+		FQDNHint:    publicAddr,
 		PublicAddr:  publicAddr,
 		ClusterName: clusterName,
 	})

diff --git a/lib/web/apiserver.go b/lib/web/apiserver.go
@@ -352,6 +352,9 @@ func NewHandler(cfg Config, opts ...HandlerOption) (*RewritingHandler, error) {
 	h.POST("/webapi/trustedcluster", h.WithAuth(h.upsertTrustedClusterHandle))
 	h.DELETE("/webapi/trustedcluster/:name", h.WithAuth(h.deleteTrustedCluster))
 
+	h.GET("/webapi/apps/:fqdnHint", h.WithAuth(h.getAppFQDN))
+	h.GET("/webapi/apps/:fqdnHint/:clusterName/:publicAddr", h.WithAuth(h.getAppFQDN))
+
 	// if Web UI is enabled, check the assets dir:
 	var indexPage *template.Template
 	if cfg.StaticFS != nil {
@@ -1244,7 +1247,7 @@ func newSessionResponse(ctx *SessionContext) (*CreateSessionResponse, error) {
 
 // createWebSession creates a new web session based on user, pass and 2nd factor token
 //
-// POST /v1/webapi/sessions
+// POST /v1/webapi/sessions/web
 //
 // {"user": "alex", "pass": "abc123", "second_factor_token": "token", "second_factor_type": "totp"}
 //

diff --git a/lib/web/apiserver_test.go b/lib/web/apiserver_test.go
@@ -1839,7 +1839,7 @@ func TestApplicationAccessDisabled(t *testing.T) {
 
 	endpoint := pack.clt.Endpoint("webapi", "sessions", "app")
 	_, err = pack.clt.PostJSON(context.Background(), endpoint, &CreateAppSessionRequest{
-		FQDN:        "panel.example.com",
+		FQDNHint:    "panel.example.com",
 		PublicAddr:  "panel.example.com",
 		ClusterName: "localhost",
 	})
@@ -1892,7 +1892,7 @@ func (s *WebSuite) TestCreateAppSession(c *C) {
 		{
 			inComment: Commentf("Valid request: all fields."),
 			inCreateRequest: &CreateAppSessionRequest{
-				FQDN:        "panel.example.com",
+				FQDNHint:    "panel.example.com",
 				PublicAddr:  "panel.example.com",
 				ClusterName: "localhost",
 			},
@@ -1913,7 +1913,7 @@ func (s *WebSuite) TestCreateAppSession(c *C) {
 		{
 			inComment: Commentf("Valid request: only FQDN."),
 			inCreateRequest: &CreateAppSessionRequest{
-				FQDN: "panel.example.com",
+				FQDNHint: "panel.example.com",
 			},
 			outError:    false,
 			outFQDN:     "panel.example.com",
@@ -1936,7 +1936,7 @@ func (s *WebSuite) TestCreateAppSession(c *C) {
 		{
 			inComment: Commentf("Invalid application."),
 			inCreateRequest: &CreateAppSessionRequest{
-				FQDN:        "panel.example.com",
+				FQDNHint:    "panel.example.com",
 				PublicAddr:  "invalid.example.com",
 				ClusterName: "localhost",
 			},
@@ -1945,7 +1945,7 @@ func (s *WebSuite) TestCreateAppSession(c *C) {
 		{
 			inComment: Commentf("Invalid cluster name."),
 			inCreateRequest: &CreateAppSessionRequest{
-				FQDN:        "panel.example.com",
+				FQDNHint:    "panel.example.com",
 				PublicAddr:  "panel.example.com",
 				ClusterName: "example.com",
 			},
@@ -1954,7 +1954,7 @@ func (s *WebSuite) TestCreateAppSession(c *C) {
 		{
 			inComment: Commentf("Malicious request: all fields."),
 			inCreateRequest: &CreateAppSessionRequest{
-				FQDN:        "panel.example.com@malicious.com",
+				FQDNHint:    "panel.example.com@malicious.com",
 				PublicAddr:  "panel.example.com",
 				ClusterName: "localhost",
 			},
@@ -1965,7 +1965,7 @@ func (s *WebSuite) TestCreateAppSession(c *C) {
 		{
 			inComment: Commentf("Malicious request: only FQDN."),
 			inCreateRequest: &CreateAppSessionRequest{
-				FQDN: "panel.example.com@malicious.com",
+				FQDNHint: "panel.example.com@malicious.com",
 			},
 			outError: true,
 		},

diff --git a/lib/web/app/fragment.go b/lib/web/app/fragment.go
@@ -43,21 +43,22 @@ type fragmentRequest struct {
 func (h *Handler) handleFragment(w http.ResponseWriter, r *http.Request, p httprouter.Params) error {
 	switch r.Method {
 	case http.MethodGet:
+		q := r.URL.Query()
 		// If the state query parameter is not set, generate a new state token,
 		// store it in a cookie and redirect back to the app launcher.
-		if r.URL.Query().Get("state") == "" {
+		if q.Get("state") == "" {
 			stateToken, err := utils.CryptoRandomHex(auth.TokenLenBytes)
 			if err != nil {
 				h.log.WithError(err).Debugf("Failed to generate and encode random numbers.")
 				return trace.AccessDenied("access denied")
 			}
 			h.setAuthStateCookie(w, stateToken)
-			p := launcherURLParams{
-				clusterName: r.URL.Query().Get("cluster"),
-				publicAddr:  r.URL.Query().Get("addr"),
+			urlParams := launcherURLParams{
+				clusterName: q.Get("cluster"),
+				publicAddr:  q.Get("addr"),
 				stateToken:  stateToken,
 			}
-			return h.redirectToLauncher(w, r, p)
+			return h.redirectToLauncher(w, r, urlParams)
 		}
 
 		nonce, err := utils.CryptoRandomHex(auth.TokenLenBytes)

diff --git a/lib/web/apps.go b/lib/web/apps.go
@@ -55,26 +55,62 @@ func (h *Handler) siteAppsGet(w http.ResponseWriter, r *http.Request, p httprout
 	return makeResponse(ui.MakeApps(h.auth.clusterName, h.proxyDNSName(), appClusterName, appServers))
 }
 
-type CreateAppSessionRequest struct {
-	// FQDN is the fully qualified domain name of the application.
-	FQDN string `json:"fqdn"`
-
-	// PublicAddr is the public address of the application.
-	PublicAddr string `json:"public_addr"`
+type GetAppFQDNRequest resolveAppParams
 
-	// ClusterName is the cluster within which this application is running.
-	ClusterName string `json:"cluster_name"`
+type GetAppFQDNResponse struct {
+	// FQDN is application FQDN.
+	FQDN string `json:"fqdn"`
 }
 
+type CreateAppSessionRequest resolveAppParams
+
 type CreateAppSessionResponse struct {
 	// CookieValue is the application session cookie value.
 	CookieValue string `json:"value"`
 	// FQDN is application FQDN.
 	FQDN string `json:"fqdn"`
 }
 
+// getAppFQDN resolves the input params to a known application and returns
+// its valid FQDN.
+//
+// GET /v1/webapi/apps/:fqdnHint/:clusterName/:publicAddr
+func (h *Handler) getAppFQDN(w http.ResponseWriter, r *http.Request, p httprouter.Params, ctx *SessionContext) (interface{}, error) {
+	req := GetAppFQDNRequest{
+		FQDNHint:    p.ByName("fqdnHint"),
+		ClusterName: p.ByName("clusterName"),
+		PublicAddr:  p.ByName("publicAddr"),
+	}
+
+	// Get an auth client connected with the user's identity.
+	authClient, err := ctx.GetClient()
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	// Get a reverse tunnel proxy aware of the user's permissions.
+	proxy, err := h.ProxyWithRoles(ctx)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	// Use the information the caller provided to attempt to resolve to an
+	// application running within either the root or leaf cluster.
+	result, err := h.resolveApp(r.Context(), authClient, proxy, resolveAppParams(req))
+	if err != nil {
+		return nil, trace.Wrap(err, "unable to resolve FQDN: %v", req.FQDNHint)
+	}
+
+	return &GetAppFQDNResponse{
+		FQDN: result.FQDN,
+	}, nil
+}
+
+// createAppSession creates a new application session.
+//
+// POST /v1/webapi/sessions/app
 func (h *Handler) createAppSession(w http.ResponseWriter, r *http.Request, p httprouter.Params, ctx *SessionContext) (interface{}, error) {
-	var req *CreateAppSessionRequest
+	var req CreateAppSessionRequest
 	if err := httplib.ReadJSON(r, &req); err != nil {
 		return nil, trace.Wrap(err)
 	}
@@ -93,9 +129,9 @@ func (h *Handler) createAppSession(w http.ResponseWriter, r *http.Request, p htt
 
 	// Use the information the caller provided to attempt to resolve to an
 	// application running within either the root or leaf cluster.
-	result, err := h.validateAppSessionRequest(r.Context(), authClient, proxy, req)
+	result, err := h.resolveApp(r.Context(), authClient, proxy, resolveAppParams(req))
 	if err != nil {
-		return nil, trace.Wrap(err, "Unable to resolve FQDN: %v", req.FQDN)
+		return nil, trace.Wrap(err, "unable to resolve FQDN: %v", req.FQDNHint)
 	}
 
 	h.log.Debugf("Creating application web session for %v in %v.", result.PublicAddr, result.ClusterName)
@@ -175,7 +211,30 @@ func (h *Handler) waitForAppSession(ctx context.Context, sessionID, user string)
 	return auth.WaitForAppSession(ctx, sessionID, user, h.cfg.AccessPoint)
 }
 
-func (h *Handler) validateAppSessionRequest(ctx context.Context, clt app.Getter, proxy reversetunnel.Tunnel, req *CreateAppSessionRequest) (*validateAppSessionResult, error) {
+type resolveAppParams struct {
+	// FQDNHint indicates (tentatively) the fully qualified domain name of the application.
+	FQDNHint string `json:"fqdn"`
+
+	// PublicAddr is the public address of the application.
+	PublicAddr string `json:"public_addr"`
+
+	// ClusterName is the cluster within which this application is running.
+	ClusterName string `json:"cluster_name"`
+}
+
+type resolveAppResult struct {
+	// ServerID is the ID of the server this application is running on.
+	ServerID string
+	// FQDN is the best effort FQDN resolved for this application.
+	FQDN string
+	// PublicAddr of application requested.
+	PublicAddr string
+	// ClusterName is the name of the cluster within which the application
+	// is running.
+	ClusterName string
+}
+
+func (h *Handler) resolveApp(ctx context.Context, clt app.Getter, proxy reversetunnel.Tunnel, params resolveAppParams) (*resolveAppResult, error) {
 	var (
 		app            *services.App
 		server         services.Server
@@ -186,37 +245,28 @@ func (h *Handler) validateAppSessionRequest(ctx context.Context, clt app.Getter,
 	// If the request contains a public address and cluster name (for example, if it came
 	// from the application launcher in the Web UI) then directly exactly resolve the
 	// application that the caller is requesting. If it does not, do best effort FQDN resolution.
-	if req.PublicAddr != "" && req.ClusterName != "" {
-		app, server, appClusterName, err = h.resolveDirect(ctx, proxy, req.PublicAddr, req.ClusterName)
-	} else {
-		app, server, appClusterName, err = h.resolveFQDN(ctx, clt, proxy, req.FQDN)
+	switch {
+	case params.PublicAddr != "" && params.ClusterName != "":
+		app, server, appClusterName, err = h.resolveDirect(ctx, proxy, params.PublicAddr, params.ClusterName)
+	case params.FQDNHint != "":
+		app, server, appClusterName, err = h.resolveFQDN(ctx, clt, proxy, params.FQDNHint)
+	default:
+		err = trace.BadParameter("no inputs to resolve application")
 	}
 	if err != nil {
 		return nil, trace.Wrap(err)
 	}
 
 	fqdn := ui.AssembleAppFQDN(h.auth.clusterName, h.proxyDNSName(), appClusterName, app)
 
-	return &validateAppSessionResult{
+	return &resolveAppResult{
 		ServerID:    server.GetName(),
 		FQDN:        fqdn,
 		PublicAddr:  app.PublicAddr,
 		ClusterName: appClusterName,
 	}, nil
 }
 
-type validateAppSessionResult struct {
-	// ServerID is the ID of the server this application is running on.
-	ServerID string
-	// FQDN is the best effort FQDN resolved for this application.
-	FQDN string
-	// PublicAddr of application requested.
-	PublicAddr string
-	// ClusterName is the name of the cluster within which the application
-	// is running.
-	ClusterName string
-}
-
 // resolveDirect takes a public address and cluster name and exactly resolves
 // the application and the server on which it is running.
 func (h *Handler) resolveDirect(ctx context.Context, proxy reversetunnel.Tunnel, publicAddr string, clusterName string) (*services.App, services.Server, string, error) {