1 files changed, 273 insertions, 0 deletions
diff --git a/remote/cdp/CDPConnection.sys.mjs b/remote/cdp/CDPConnection.sys.mjs
new file mode 100644
index 0000000000..627bb57c3f
--- /dev/null
+++ b/remote/cdp/CDPConnection.sys.mjs
@@ -0,0 +1,273 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+import { WebSocketConnection } from "chrome://remote/content/shared/WebSocketConnection.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+  UnknownMethodError: "chrome://remote/content/cdp/Error.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "logger", () =>
+  lazy.Log.get(lazy.Log.TYPES.CDP)
+);
+
+export class CDPConnection extends WebSocketConnection {
+  /**
+   * @param {WebSocket} webSocket
+   *     The WebSocket server connection to wrap.
+   * @param {Connection} httpdConnection
+   *     Reference to the httpd.js's connection needed for clean-up.
+   */
+  constructor(webSocket, httpdConnection) {
+    super(webSocket, httpdConnection);
+
+    this.sessions = new Map();
+    this.defaultSession = null;
+  }
+
+  /**
+   * Register a new Session to forward the messages to.
+   *
+   * A session without any `id` attribute will be considered to be the
+   * default one, to which messages without `sessionId` attribute are
+   * forwarded to. Only one such session can be registered.
+   *
+   * @param {Session} session
+   *     The session to register.
+   */
+  registerSession(session) {
+    // CDP is not compatible with Fission by default, check the appropriate
+    // preferences are set to ensure compatibility.
+    if (
+      Services.prefs.getIntPref("fission.webContentIsolationStrategy") !== 0 ||
+      Services.prefs.getBoolPref("fission.bfcacheInParent")
+    ) {
+      lazy.logger.error(
+        `Invalid browser preferences for CDP. Set "fission.webContentIsolationStrategy"` +
+          `to 0 and "fission.bfcacheInParent" to false before Firefox starts.`
+      );
+    }
+
+    if (!session.id) {
+      if (this.defaultSession) {
+        throw new Error(
+          "Default session is already set on Connection, " +
+            "can't register another one."
+        );
+      }
+      this.defaultSession = session;
+    }
+
+    this.sessions.set(session.id, session);
+  }
+
+  /**
+   * Send an error back to the CDP client.
+   *
+   * @param {Number} id
+   *     Id of the packet which lead to an error.
+   * @param {Error} err
+   *     Error object with `message` and `stack` attributes.
+   * @param {String=} sessionId
+   *     Id of the session used to send this packet. Falls back to the
+   *     default session if not specified.
+   */
+  sendError(id, err, sessionId) {
+    const error = {
+      message: err.message,
+      data: err.stack,
+    };
+
+    this.send({ id, error, sessionId });
+  }
+
+  /**
+   * Send an event coming from a Domain to the CDP client.
+   *
+   * @param {String} method
+   *     The event name. This is composed by a domain name, a dot character
+   *     followed by the event name, e.g. `Target.targetCreated`.
+   * @param {Object} params
+   *     A JSON-serializable object, which is the payload of this event.
+   * @param {Sting=} sessionId
+   *     The sessionId from which this packet is emitted. Falls back to the
+   *     default session if not specified.
+   */
+  sendEvent(method, params, sessionId) {
+    this.send({ method, params, sessionId });
+
+    // When a client attaches to a secondary target via
+    // `Target.attachToTarget`, we should emit an event back with the
+    // result including the `sessionId` attribute of this secondary target's
+    // session. `Target.attachToTarget` creates the secondary session and
+    // returns the session ID.
+    if (sessionId) {
+      // receivedMessageFromTarget is expected to send a raw CDP packet
+      // in the `message` property and it to be already serialized to a
+      // string
+      this.send({
+        method: "Target.receivedMessageFromTarget",
+        params: { sessionId, message: JSON.stringify({ method, params }) },
+      });
+    }
+  }
+
+  /**
+   * Interpret a given CDP packet for a given Session.
+   *
+   * @param {String} sessionId
+   *     ID of the session for which we should execute a command.
+   * @param {String} message
+   *     The stringified JSON payload of the CDP packet, which is about
+   *     executing a Domain's function.
+   */
+  sendMessageToTarget(sessionId, message) {
+    const session = this.sessions.get(sessionId);
+    if (!session) {
+      throw new Error(`Session '${sessionId}' doesn't exist.`);
+    }
+    // `message` is received from `Target.sendMessageToTarget` where the
+    // message attribute is a stringified JSON payload which represent a CDP
+    // packet.
+    const packet = JSON.parse(message);
+
+    // The CDP packet sent by the client shouldn't have a sessionId attribute
+    // as it is passed as another argument of `Target.sendMessageToTarget`.
+    // Set it here in order to reuse the codepath of flatten session, where
+    // the client sends CDP packets with a `sessionId` attribute instead
+    // of going through the old and probably deprecated
+    // `Target.sendMessageToTarget` API.
+    packet.sessionId = sessionId;
+    this.onPacket(packet);
+  }
+
+  /**
+   * Send the result of a call to a Domain's function back to the CDP client.
+   *
+   * @param {Number} id
+   *     The request id being sent by the client to call the domain's method.
+   * @param {Object} result
+   *     A JSON-serializable object, which is the actual result.
+   * @param {String=} sessionId
+   *     The sessionId from which this packet is emitted. Falls back to the
+   *     default session if not specified.
+   */
+  sendResult(id, result, sessionId) {
+    result = typeof result != "undefined" ? result : {};
+    this.send({ id, result, sessionId });
+
+    // When a client attaches to a secondary target via
+    // `Target.attachToTarget`, and it executes a command via
+    // `Target.sendMessageToTarget`, we should emit an event back with the
+    // result including the `sessionId` attribute of this secondary target's
+    // session. `Target.attachToTarget` creates the secondary session and
+    // returns the session ID.
+    if (sessionId) {
+      // receivedMessageFromTarget is expected to send a raw CDP packet
+      // in the `message` property and it to be already serialized to a
+      // string
+      this.send({
+        method: "Target.receivedMessageFromTarget",
+        params: { sessionId, message: JSON.stringify({ id, result }) },
+      });
+    }
+  }
+
+  // Transport hooks
+
+  /**
+   * Called by the `transport` when the connection is closed.
+   */
+  onClosed() {
+    // Cleanup all the registered sessions.
+    for (const session of this.sessions.values()) {
+      session.destructor();
+    }
+    this.sessions.clear();
+
+    super.onClosed();
+  }
+
+  /**
+   * Receive a packet from the WebSocket layer.
+   *
+   * This packet is sent by a CDP client and is meant to execute
+   * a particular function on a given Domain.
+   *
+   * @param {Object} packet
+   *        JSON-serializable object sent by the client.
+   */
+  async onPacket(packet) {
+    super.onPacket(packet);
+
+    try {
+      const { id, method, params, sessionId } = packet;
+
+      // First check for mandatory field in the packets
+      if (typeof id == "undefined") {
+        throw new TypeError("Message missing 'id' field");
+      }
+      if (typeof method == "undefined") {
+        throw new TypeError("Message missing 'method' field");
+      }
+
+      // Extract the domain name and the method name out of `method` attribute
+      const { domain, command } = splitMethod(method);
+
+      // If a `sessionId` field is passed, retrieve the session to which we
+      // should forward this packet. Otherwise send it to the default session.
+      let session;
+      if (!sessionId) {
+        if (!this.defaultSession) {
+          throw new Error("Connection is missing a default Session.");
+        }
+        session = this.defaultSession;
+      } else {
+        session = this.sessions.get(sessionId);
+        if (!session) {
+          throw new Error(`Session '${sessionId}' doesn't exists.`);
+        }
+      }
+
+      // Bug 1600317 - Workaround to deny internal methods to be called
+      if (command.startsWith("_")) {
+        throw new lazy.UnknownMethodError(command);
+      }
+
+      // Finally, instruct the targeted session to execute the command
+      const result = await session.execute(id, domain, command, params);
+      this.sendResult(id, result, sessionId);
+    } catch (e) {
+      this.sendError(packet.id, e, packet.sessionId);
+    }
+  }
+}
+
+/**
+ * Splits a CDP method into domain and command components.
+ *
+ * @param {String} method
+ *     Name of the method to split, e.g. "Browser.getVersion".
+ *
+ * @returns {Object<String, String>}
+ *     Object with the domain ("Browser") and command ("getVersion")
+ *     as properties.
+ */
+export function splitMethod(method) {
+  const parts = method.split(".");
+
+  if (parts.length != 2 || !parts[0].length || !parts[1].length) {
+    throw new TypeError(`Invalid method format: '${method}'`);
+  }
+
+  return {
+    domain: parts[0],
+    command: parts[1],
+  };
+}