DevTools: implement proxy server for hosted mode

third_party/WebKit/Source/devtools/hosted_mode/server.js

+var fs = require("fs");
+var http = require("http");
+var path = require("path");
+var parseUrl = require("url").parse;
+
+var protocolFilesProxy = require("./protocol_files_proxy.js");
+
+var port = parseInt(process.env.PORT, 10) || 9999;

[lushnikov, 2016/07/22 02:56:21]

|| 8090; (the default port atm)

[chenwilliam, 2016/07/22 17:35:25]

OK, I can change it. I got the 9999 from the Chrome DevTools Contribution guide
so we should update that as well. Do we document 8090 somewhere?

https://docs.google.com/document/d/1WNF-KqRSzPLUUfZqQG5AFeU_Ll8TfWYcJasa_XGf7...

+
+http.createServer(requestHandler).listen(port);
+protocolFilesProxy.loadCache();
+console.log("Starting hosted mode server at:\n  http://localhost:" + port);
+
+function requestHandler(request, response)
+{
+    var url = parseUrl(request.url).pathname;
+
+    if (url === "/front_end/InspectorBackendCommands.js") {
+        sendResponse(200, " ");

[lushnikov, 2016/07/22 02:56:21]

can we pass just "" here?

[chenwilliam, 2016/07/22 17:35:25]

I initially tried it with an empty string but then I still get the following
console error. The " " is hacky, but seems like an OK workaround.

Runtime.js:161 Empty response arrived for script
'http://localhost:9999/front_end/InspectorBackendCommands.js'

+        return;
+    }
+
+    if (protocolFilesProxy.protocolFiles.indexOf(url) > -1) {
+        protocolFilesProxy.getProtocolFile(url)
+            .then(data => sendResponse(200, data))
+            .catch(err => console.log(`Error getting ${protocolFile}:`, err));
+        return;
+    }
+
+    var filePath = path.join(process.cwd(), url);
+    fs.exists(filePath, fsExistsCallback);
+
+    function fsExistsCallback(fileExists)
+    {
+        if (!fileExists) {
+            sendResponse(404, "404 - File not found");
+            return;
+        }
+        fs.readFile(filePath, "binary", readFileCallback);
+    }
+
+    function readFileCallback(err, file)
+    {
+        if (err) {
+            sendResponse(500, `500 - Can't read file: ${err}`);
+            return;
+        }
+        sendResponse(200, file);
+    }
+
+    function sendResponse(statusCode, data)
+    {
+        response.writeHead(statusCode);
+        response.write(data, "binary");
+        response.end();
+    }
+}