Add lens:// protocol handling with a routing mechanism (#1949)

- Add lens:// protocol handling with a routing mechanism

- document the methods in an extension guide

- remove handlers when an extension is deactivated or removed

- make sure that the found extension when routing a request is currently enabled (as a backup)

- added documentation about the above behaviour to the guide

- tweaked the naming convention so that it is clearer that the router uses extension names as not IDs (which currently are folder paths)

- Convert the extension API to use an array for registering handlers

- switch design to execute both main and renderer handlers simultaneously, without any overlap checking

- change open to be a dev dep

- improve docs, export types for extensions, skip integration tests

- switch to event emitting renderer being ready

- Add logging and fix renderer:loaded send to main

Signed-off-by: Sebastian Malton <sebastian@malton.name>

src/common/ipc/ipc.ts

@@ -47,7 +47,7 @@ export async function broadcastMessage(channel: string, ...args: any[]) {
         view.sendToFrame([frameInfo.processId, frameInfo.frameId], channel, ...args);
       }
     } catch (error) {
-      logger.error("[IPC]: failed to send IPC message", { error });
+      logger.error("[IPC]: failed to send IPC message", { error: String(error) });
     }
   }
 }

src/common/protocol-handler/error.ts

@@ -0,0 +1,36 @@
+import Url from "url-parse";
+
+export enum RoutingErrorType {
+  INVALID_PROTOCOL = "invalid-protocol",
+  INVALID_HOST = "invalid-host",
+  INVALID_PATHNAME = "invalid-pathname",
+  NO_HANDLER = "no-handler",
+  NO_EXTENSION_ID = "no-ext-id",
+  MISSING_EXTENSION = "missing-ext",
+}
+
+export class RoutingError extends Error {
+  /**
+   * Will be set if the routing error originated in an extension route table
+   */
+  public extensionName?: string;
+
+  constructor(public type: RoutingErrorType, public url: Url) {
+    super("routing error");
+  }
+
+  toString(): string {
+    switch (this.type) {
+      case RoutingErrorType.INVALID_HOST:
+        return "invalid host";
+      case RoutingErrorType.INVALID_PROTOCOL:
+        return "invalid protocol";
+      case RoutingErrorType.INVALID_PATHNAME:
+        return "invalid pathname";
+      case RoutingErrorType.NO_EXTENSION_ID:
+        return "no extension ID";
+      case RoutingErrorType.MISSING_EXTENSION:
+        return "extension not found";
+    }
+  }
+}

src/common/protocol-handler/index.ts

@@ -0,0 +1,2 @@
+export * from "./error";
+export * from "./router";

src/common/protocol-handler/router.ts

@@ -0,0 +1,218 @@
+import { match, matchPath } from "react-router";
+import { countBy } from "lodash";
+import { Singleton } from "../utils";
+import { pathToRegexp } from "path-to-regexp";
+import logger from "../../main/logger";
+import Url from "url-parse";
+import { RoutingError, RoutingErrorType } from "./error";
+import { extensionsStore } from "../../extensions/extensions-store";
+import { extensionLoader } from "../../extensions/extension-loader";
+import { LensExtension } from "../../extensions/lens-extension";
+import { RouteHandler, RouteParams } from "../../extensions/registries/protocol-handler-registry";
+
+// IPC channel for protocol actions. Main broadcasts the open-url events to this channel.
+export const ProtocolHandlerIpcPrefix = "protocol-handler";
+
+export const ProtocolHandlerInternal = `${ProtocolHandlerIpcPrefix}:internal`;
+export const ProtocolHandlerExtension= `${ProtocolHandlerIpcPrefix}:extension`;
+
+/**
+ * These two names are long and cumbersome by design so as to decrease the chances
+ * of an extension using the same names.
+ *
+ * Though under the current (2021/01/18) implementation, these are never matched
+ * against in the final matching so their names are less of a concern.
+ */
+const EXTENSION_PUBLISHER_MATCH = "LENS_INTERNAL_EXTENSION_PUBLISHER_MATCH";
+const EXTENSION_NAME_MATCH = "LENS_INTERNAL_EXTENSION_NAME_MATCH";
+
+export abstract class LensProtocolRouter extends Singleton {
+  // Map between path schemas and the handlers
+  protected internalRoutes = new Map<string, RouteHandler>();
+
+  public static readonly LoggingPrefix = "[PROTOCOL ROUTER]";
+
+  protected static readonly ExtensionUrlSchema = `/:${EXTENSION_PUBLISHER_MATCH}(\@[A-Za-z0-9_]+)?/:${EXTENSION_NAME_MATCH}`;
+
+  /**
+   *
+   * @param url the parsed URL that initiated the `lens://` protocol
+   */
+  protected _routeToInternal(url: Url): void {
+    this._route(Array.from(this.internalRoutes.entries()), url);
+  }
+
+  /**
+   * match against all matched URIs, returning either the first exact match or
+   * the most specific match if none are exact.
+   * @param routes the array of path schemas, handler pairs to match against
+   * @param url the url (in its current state)
+   */
+  protected _findMatchingRoute(routes: [string, RouteHandler][], url: Url): null | [match<Record<string, string>>, RouteHandler] {
+    const matches: [match<Record<string, string>>, RouteHandler][] = [];
+
+    for (const [schema, handler] of routes) {
+      const match = matchPath(url.pathname, { path: schema });
+
+      if (!match) {
+        continue;
+      }
+
+      // prefer an exact match
+      if (match.isExact) {
+        return [match, handler];
+      }
+
+      matches.push([match, handler]);
+    }
+
+    // if no exact match pick the one that is the most specific
+    return matches.sort(([a], [b]) => compareMatches(a, b))[0] ?? null;
+  }
+
+  /**
+   * find the most specific matching handler and call it
+   * @param routes the array of (path schemas, handler) paris to match against
+   * @param url the url (in its current state)
+   */
+  protected _route(routes: [string, RouteHandler][], url: Url, extensionName?: string): void {
+    const route = this._findMatchingRoute(routes, url);
+
+    if (!route) {
+      const data: Record<string, string> = { url: url.toString() };
+
+      if (extensionName) {
+        data.extensionName = extensionName;
+      }
+
+      return void logger.info(`${LensProtocolRouter.LoggingPrefix}: No handler found`, data);
+    }
+
+    const [match, handler] = route;
+
+    const params: RouteParams = {
+      pathname: match.params,
+      search: url.query,
+    };
+
+    if (!match.isExact) {
+      params.tail = url.pathname.slice(match.url.length);
+    }
+
+    handler(params);
+  }
+
+  /**
+   * Tries to find the matching LensExtension instance
+   *
+   * Note: this needs to be async so that `main`'s overloaded version can also be async
+   * @param url the protocol request URI that was "open"-ed
+   * @returns either the found name or the instance of `LensExtension`
+   */
+  protected async _findMatchingExtensionByName(url: Url): Promise<LensExtension | string> {
+    interface ExtensionUrlMatch {
+      [EXTENSION_PUBLISHER_MATCH]: string;
+      [EXTENSION_NAME_MATCH]: string;
+    }
+
+    const match = matchPath<ExtensionUrlMatch>(url.pathname, LensProtocolRouter.ExtensionUrlSchema);
+
+    if (!match) {
+      throw new RoutingError(RoutingErrorType.NO_EXTENSION_ID, url);
+    }
+
+    const { [EXTENSION_PUBLISHER_MATCH]: publisher, [EXTENSION_NAME_MATCH]: partialName } = match.params;
+    const name = [publisher, partialName].filter(Boolean).join("/");
+
+    const extension = extensionLoader.userExtensionsByName.get(name);
+
+    if (!extension) {
+      logger.info(`${LensProtocolRouter.LoggingPrefix}: Extension ${name} matched, but not installed`);
+
+      return name;
+    }
+
+    if (!extensionsStore.isEnabled(extension.id)) {
+      logger.info(`${LensProtocolRouter.LoggingPrefix}: Extension ${name} matched, but not enabled`);
+
+      return name;
+    }
+
+    logger.info(`${LensProtocolRouter.LoggingPrefix}: Extension ${name} matched`);
+
+    return extension;
+  }
+
+  /**
+   * Find a matching extension by the first one or two path segments of `url` and then try to `_route`
+   * its correspondingly registered handlers.
+   *
+   * If no handlers are found or the extension is not enabled then `_missingHandlers` is called before
+   * checking if more handlers have been added.
+   *
+   * Note: this function modifies its argument, do not reuse
+   * @param url the protocol request URI that was "open"-ed
+   */
+  protected async _routeToExtension(url: Url): Promise<void> {
+    const extension = await this._findMatchingExtensionByName(url);
+
+    if (typeof extension === "string") {
+      // failed to find an extension, it returned its name
+      return;
+    }
+
+    // remove the extension name from the path name so we don't need to match on it anymore
+    url.set("pathname", url.pathname.slice(extension.name.length + 1));
+
+    const handlers = extension
+      .protocolHandlers
+      .map<[string, RouteHandler]>(({ pathSchema, handler }) => [pathSchema, handler]);
+
+    try {
+      this._route(handlers, url, extension.name);
+    } catch (error) {
+      if (error instanceof RoutingError) {
+        error.extensionName = extension.name;
+      }
+
+      throw error;
+    }
+  }
+
+  /**
+   * Add a handler under the `lens://app` tree of routing.
+   * @param pathSchema the URI path schema to match against for this handler
+   * @param handler a function that will be called if a protocol path matches
+   */
+  public addInternalHandler(urlSchema: string, handler: RouteHandler): void {
+    pathToRegexp(urlSchema); // verify now that the schema is valid
+    logger.info(`${LensProtocolRouter.LoggingPrefix}: internal registering ${urlSchema}`);
+    this.internalRoutes.set(urlSchema, handler);
+  }
+
+  /**
+   * Remove an internal protocol handler.
+   * @param pathSchema the path schema that the handler was registered under
+   */
+  public removeInternalHandler(urlSchema: string): void {
+    this.internalRoutes.delete(urlSchema);
+  }
+}
+
+/**
+ * a comparison function for `array.sort(...)`. Sort order should be most path
+ * parts to least path parts.
+ * @param a the left side to compare
+ * @param b the right side to compare
+ */
+function compareMatches<T>(a: match<T>, b: match<T>): number {
+  if (a.path === "/") {
+    return 1;
+  }
+
+  if (b.path === "/") {
+    return -1;
+  }
+
+  return countBy(b.path)["/"] - countBy(a.path)["/"];
+}

src/common/utils/delay.ts

@@ -1,8 +1,19 @@
+import { AbortController } from "abort-controller";
+
 /**
  * Return a promise that will be resolved after at least `timeout` ms have
- * passed
+ * passed. If `failFast` is provided then the promise is also resolved if it has
+ * been aborted.
  * @param timeout The number of milliseconds before resolving
+ * @param failFast An abort controller instance to cause the delay to short-circuit
  */
-export function delay(timeout = 1000): Promise<void> {
-  return new Promise(resolve => setTimeout(resolve, timeout));
+export function delay(timeout = 1000, failFast?: AbortController): Promise<void> {
+  return new Promise(resolve => {
+    const timeoutId = setTimeout(resolve, timeout);
+
+    failFast?.signal.addEventListener("abort", () => {
+      clearTimeout(timeoutId);
+      resolve();
+    });
+  });
 }

src/common/utils/index.ts

@@ -18,4 +18,4 @@ export * from "./openExternal";
 export * from "./downloadFile";
 export * from "./escapeRegExp";
 export * from "./tar";
-export * from "./delay";
+export * from "./type-narrowing";

src/common/utils/type-narrowing.ts

@@ -0,0 +1,13 @@
+/**
+ * Narrows `val` to include the property `key` (if true is returned)
+ * @param val The object to be tested
+ * @param key The key to test if it is present on the object
+ */
+export function hasOwnProperty<V extends object, K extends PropertyKey>(val: V, key: K): val is (V & { [key in K]: unknown }) {
+  // this call syntax is for when `val` was created by `Object.create(null)`
+  return Object.prototype.hasOwnProperty.call(val, key);
+}
+
+export function hasOwnProperties<V extends object, K extends PropertyKey>(val: V, ...keys: K[]): val is (V & { [key in K]: unknown}) {
+  return keys.every(key => hasOwnProperty(val, key));
+}