Electron: Protocol

[xwcoder]

Electron: Protocol

Protocol module is used to register a custom protocol and intercept existing protocol requests.

What is scheme

RFC 3986

Primary methods

protocol.registerSchemesAsPrivileged(customSchemes)

• Code example

  // src/main.js
  const { protocol } = require('electron');
  
  protocol.registerSchemesAsPrivileged([
  	{
  		scheme: 'vscode-webview',
  		privileges: { standard: true, secure: true, supportFetchAPI: true, corsEnabled: true, allowServiceWorkers: true, }
  	},
  	{
  		scheme: 'vscode-file',
  		privileges: { secure: true, standard: true, supportFetchAPI: true, corsEnabled: true }
  	}
  ]);

• Registers the scheme as standard, which means relative and absolute resources can be resolved correctly, allow to files through the FileSystem API , allow to use web storage apis, etc.

• Non standard scheme will behave like the file protocol. file is not standard scheme.

• Can be used before the ready event of the app module gets emitted and can be called only once.

protocol.registerFileProtocol(scheme, handler)

• Registers a protocol of scheme that will send a file as the response.

• Code example

  // vs/platform/protocol/electron-main/protocolMainService.ts
  
  // Register vscode-file:// handler
  defaultSession.protocol.registerFileProtocol('vscode-file', (request, callback) => this.handleResourceRequest(request, callback));

protocol.interceptFileProtocol(scheme, handler)

• Intercepts scheme protocol and uses handler as the protocol's new handler which sends a file as a response.

• Code example

  // vs/platform/protocol/electron-main/protocolMainService.ts
  
  // Block any file:// access
  defaultSession.protocol.interceptFileProtocol('file', (request, callback) => this.handleFileRequest(request, callback));
  
  ...
  
  private handleFileRequest(request: Electron.ProtocolRequest, callback: ProtocolCallback) {
  		const uri = URI.parse(request.url);
  
  		this.logService.error(`Refused to load resource ${uri.fsPath} from ${Schemas.file}: protocol (original URL: ${request.url})`);
  
  		return callback({ error: -3 /* ABORTED */ });
  	}

protocol.registerXXXProtocol(scheme, handler)

protocol.interceptXXXProtocol(scheme, handler)

Using protocol with a custom partition or session

• A protocol is registered to a specific Electron session object.

• If not specify a session, the protocol will be applied to the default session.

• Code example

  const { session, app, protocol } = require('electron')
  const path = require('path')
  
  app.whenReady().then(() => {
    const partition = 'persist:example'
    const ses = session.fromPartition(partition)
  
    ses.protocol.registerFileProtocol('atom', (request, callback) => {
      const url = request.url.substr(7)
      callback({ path: path.normalize(`${__dirname}/${url}`) })
    })
  
    mainWindow = new BrowserWindow({ webPreferences: { partition } })
  })