_setupListeners()

in src/index.js [110:169]

• 51 lines of code
• 6 McCabe index (conditional complexity)

  _setupListeners() {
    this._socket.addEventListener('message', async event => {
      try {
        // When we receive data from the channelserver, pump it through the TLS connection
        // to decrypt it, then echo it back out to consumers as an event.
        const channelServerEnvelope = JSON.parse(event.data);
        const payload = await this._connection.recv(base64urlToBytes(channelServerEnvelope.message));
        if (payload !== null) {
          const data = JSON.parse(bytesToUtf8(payload));
          this.dispatchEvent(new CustomEvent('message', {
            detail: {
              data,
              sender: channelServerEnvelope.sender,
            },
          }));
        }
      } catch (error) {
        let event;
        // The underlying TLS connection will signal a clean shutdown of the channel
        // by throwing a special error, because it doesn't really have a better
        // signally mechanism available.
        if (error instanceof TLSCloseNotify) {
          this._peerClosed = true;
          if (this._selfClosed) {
            this._shutdown();
          }
          event = new CustomEvent('close');
        } else {
          event = new CustomEvent('error', {
            detail: {
              error,
            }
          });
        }
        this.dispatchEvent(event);
      }
    });
    // Relay the WebSocket events.
    this._socket.addEventListener('error', () => {
      this._shutdown();
      // The dispatched event that we receive has no useful information.
      this.dispatchEvent(new CustomEvent('error', {
        detail: {
          error: new Error('WebSocket error.'),
        },
      }));
    });
    // In TLS, the peer has to explicitly send a close notification,
    // which we dispatch above.  Unexpected socket close is an error.
    this._socket.addEventListener('close', () => {
      this._shutdown();
      if (! this._peerClosed) {
        this.dispatchEvent(new CustomEvent('error', {
          detail: {
            error: new Error('WebSocket unexpectedly closed'),
          }
        }));
      }
    });
  }