Use serverUID for web scp target (#23124) (#23153)

* Use serverUID for scp target

Revert unneeded hostname change

Remove comment

Get name

* Change name to serverId

* Fix lint errors

* Add comment

* Fix comment and signature format

lib/client/api.go

@@ -2360,7 +2360,7 @@ func PlayFile(ctx context.Context, tarFile io.Reader, sid string) error {
 
 // ExecuteSCP executes SCP command. It executes scp.Command using
 // lower-level API integrations that mimic SCP CLI command behavior
-func (tc *TeleportClient) ExecuteSCP(ctx context.Context, cmd scp.Command) (err error) {
+func (tc *TeleportClient) ExecuteSCP(ctx context.Context, serverAddr string, cmd scp.Command) error {
 	ctx, span := tc.Tracer.Start(
 		ctx,
 		"teleportClient/ExecuteSCP",
@@ -2379,19 +2379,11 @@ func (tc *TeleportClient) ExecuteSCP(ctx context.Context, cmd scp.Command) (err
 	}
 	defer proxyClient.Close()
 
-	// which nodes are we executing this commands on?
-	nodeAddrs, err := tc.getTargetNodes(ctx, proxyClient)
-	if err != nil {
-		return trace.Wrap(err)
-	}
-	if len(nodeAddrs) == 0 {
-		return trace.BadParameter("no target host specified")
-	}
-
 	nodeClient, err := tc.ConnectToNode(
 		ctx,
 		proxyClient,
-		NodeDetails{Addr: nodeAddrs[0], Namespace: tc.Namespace, Cluster: tc.SiteName},
+		// We append the ":0" to tell the server to figure out the port for us.
+		NodeDetails{Addr: serverAddr + ":0", Namespace: tc.Namespace, Cluster: tc.SiteName},
 		tc.Config.HostLogin,
 	)
 	if err != nil {

lib/web/files.go

@@ -33,7 +33,7 @@ import (
 // fileTransferRequest describes HTTP file transfer request
 type fileTransferRequest struct {
 	// Server describes a server to connect to (serverId|hostname[:port]).
-	server string
+	serverID string
 	// Login is Linux username to connect as.
 	login string
 	// Namespace is node namespace.
@@ -51,7 +51,7 @@ func (h *Handler) transferFile(w http.ResponseWriter, r *http.Request, p httprou
 	req := fileTransferRequest{
 		cluster:        p.ByName("site"),
 		login:          p.ByName("login"),
-		server:         p.ByName("server"),
+		serverID:       p.ByName("server"),
 		remoteLocation: query.Get("location"),
 		filename:       query.Get("filename"),
 		namespace:      defaults.Namespace,
@@ -106,7 +106,7 @@ func (f *fileTransfer) download(req fileTransferRequest, httpReq *http.Request,
 		return trace.Wrap(err)
 	}
 
-	err = tc.ExecuteSCP(httpReq.Context(), cmd)
+	err = tc.ExecuteSCP(httpReq.Context(), req.serverID, cmd)
 	if err != nil {
 		return trace.Wrap(err)
 	}
@@ -130,7 +130,7 @@ func (f *fileTransfer) upload(req fileTransferRequest, httpReq *http.Request) er
 		return trace.Wrap(err)
 	}
 
-	err = tc.ExecuteSCP(httpReq.Context(), cmd)
+	err = tc.ExecuteSCP(httpReq.Context(), req.serverID, cmd)
 	if err != nil {
 		return trace.Wrap(err)
 	}
@@ -152,9 +152,9 @@ func (f *fileTransfer) createClient(req fileTransferRequest, httpReq *http.Reque
 		return nil, trace.Wrap(err)
 	}
 
-	hostName, hostPort, err := resolveServerHostPort(req.server, servers)
+	hostName, hostPort, err := resolveServerHostPort(req.serverID, servers)
 	if err != nil {
-		return nil, trace.BadParameter("invalid server name %q: %v", req.server, err)
+		return nil, trace.BadParameter("invalid server name %q: %v", req.serverID, err)
 	}
 
 	cfg, err := makeTeleportClientConfig(httpReq.Context(), f.ctx)