feat: add endpoint to get listening ports in agent (#4260)

coderd/workspaceagents.go

@@ -219,6 +219,52 @@ func (api *API) workspaceAgentPTY(rw http.ResponseWriter, r *http.Request) {
 	_, _ = io.Copy(ptNetConn, wsNetConn)
 }
 
+func (api *API) workspaceAgentListeningPorts(rw http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	workspace := httpmw.WorkspaceParam(r)
+	workspaceAgent := httpmw.WorkspaceAgentParam(r)
+	if !api.Authorize(r, rbac.ActionRead, workspace) {
+		httpapi.ResourceNotFound(rw)
+		return
+	}
+
+	apiAgent, err := convertWorkspaceAgent(api.DERPMap, api.TailnetCoordinator, workspaceAgent, nil, api.AgentInactiveDisconnectTimeout)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error reading workspace agent.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+	if apiAgent.Status != codersdk.WorkspaceAgentConnected {
+		httpapi.Write(ctx, rw, http.StatusPreconditionRequired, codersdk.Response{
+			Message: fmt.Sprintf("Agent state is %q, it must be in the %q state.", apiAgent.Status, codersdk.WorkspaceAgentConnected),
+		})
+		return
+	}
+
+	agentConn, release, err := api.workspaceAgentCache.Acquire(r, workspaceAgent.ID)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error dialing workspace agent.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+	defer release()
+
+	portsResponse, err := agentConn.ListeningPorts(ctx)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error fetching listening ports.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	httpapi.Write(ctx, rw, http.StatusOK, portsResponse)
+}
+
 func (api *API) dialWorkspaceAgentTailnet(r *http.Request, agentID uuid.UUID) (*codersdk.AgentConn, error) {
 	clientConn, serverConn := net.Pipe()
 	go func() {