[feature] Allow http/https scheme

Allow HTTP(S) URLs to be used in the WebSocket constructor. They are
immediately converted to the ws and wss schemes.

Refs: whatwg/websockets#45

lib/websocket.js

@@ -667,24 +667,30 @@ function initAsClient(websocket, address, protocols, options) {
 
   if (address instanceof URL) {
     parsedUrl = address;
-    websocket._url = address.href;
   } else {
     try {
       parsedUrl = new URL(address);
     } catch (e) {
       throw new SyntaxError(`Invalid URL: ${address}`);
     }
+  }
 
-    websocket._url = address;
+  if (parsedUrl.protocol === 'http:') {
+    parsedUrl.protocol = 'ws:';
+  } else if (parsedUrl.protocol === 'https:') {
+    parsedUrl.protocol = 'wss:';
   }
 
+  websocket._url = parsedUrl.href;
+
   const isSecure = parsedUrl.protocol === 'wss:';
   const isIpcUrl = parsedUrl.protocol === 'ws+unix:';
   let invalidUrlMessage;
 
   if (parsedUrl.protocol !== 'ws:' && !isSecure && !isIpcUrl) {
     invalidUrlMessage =
-      'The URL\'s protocol must be one of "ws:", "wss:", or "ws+unix:"';
+      'The URL\'s protocol must be one of "ws:", "wss:", ' +
+      '"http:", "https", or "ws+unix:"';
   } else if (isIpcUrl && !parsedUrl.pathname) {
     invalidUrlMessage = "The URL's pathname is empty";
   } else if (parsedUrl.hash) {

test/websocket.test.js

@@ -36,8 +36,16 @@ describe('WebSocket', () => {
       );
 
       assert.throws(
-        () => new WebSocket('https://websocket-echo.com'),
-        /^SyntaxError: The URL's protocol must be one of "ws:", "wss:", or "ws\+unix:"$/
+        () => new WebSocket('bad-scheme://websocket-echo.com'),
+        (err) => {
+          assert.strictEqual(
+            err.message,
+            'The URL\'s protocol must be one of "ws:", "wss:", ' +
+              '"http:", "https", or "ws+unix:"'
+          );
+
+          return true;
+        }
       );
 
       assert.throws(
@@ -72,6 +80,30 @@ describe('WebSocket', () => {
       const ws = new WebSocket(new URL('ws://[::1]'), { agent });
     });
 
+    it('allows the http scheme', (done) => {
+      const agent = new CustomAgent();
+
+      agent.addRequest = (req, opts) => {
+        assert.strictEqual(opts.host, 'localhost');
+        assert.strictEqual(opts.port, 80);
+        done();
+      };
+
+      const ws = new WebSocket('http://localhost', { agent });
+    });
+
+    it('allows the https scheme', (done) => {
+      const agent = new https.Agent();
+
+      agent.addRequest = (req, opts) => {
+        assert.strictEqual(opts.host, 'localhost');
+        assert.strictEqual(opts.port, 443);
+        done();
+      };
+
+      const ws = new WebSocket('https://localhost', { agent });
+    });
+
     describe('options', () => {
       it('accepts the `options` object as 3rd argument', () => {
         const agent = new http.Agent();
@@ -539,10 +571,18 @@ describe('WebSocket', () => {
       });
 
       it('exposes the server url', () => {
-        const url = 'ws://localhost';
-        const ws = new WebSocket(url, { agent: new CustomAgent() });
+        const schemes = new Map([
+          ['ws', 'ws'],
+          ['wss', 'wss'],
+          ['http', 'ws'],
+          ['https', 'wss']
+        ]);
+
+        for (const [key, value] of schemes) {
+          const ws = new WebSocket(`${key}://localhost/`, { lookup() {} });
 
-        assert.strictEqual(ws.url, url);
+          assert.strictEqual(ws.url, `${value}://localhost/`);
+        }
       });
     });
   });
@@ -1174,7 +1214,9 @@ describe('WebSocket', () => {
 
     it('emits an error if the redirect URL is invalid (2/2)', (done) => {
       server.once('upgrade', (req, socket) => {
-        socket.end('HTTP/1.1 302 Found\r\nLocation: http://localhost\r\n\r\n');
+        socket.end(
+          'HTTP/1.1 302 Found\r\nLocation: bad-scheme://localhost\r\n\r\n'
+        );
       });
 
       const ws = new WebSocket(`ws://localhost:${server.address().port}`, {
@@ -1186,7 +1228,8 @@ describe('WebSocket', () => {
         assert.ok(err instanceof SyntaxError);
         assert.strictEqual(
           err.message,
-          'The URL\'s protocol must be one of "ws:", "wss:", or "ws+unix:"'
+          'The URL\'s protocol must be one of "ws:", "wss:", ' +
+            '"http:", "https", or "ws+unix:"'
         );
         assert.strictEqual(ws._redirects, 1);