Karlie/web snippet

AutoCollection/WebSnippet.ts

@@ -0,0 +1,148 @@
+import * as path from "path";
+import http = require("http");
+import fs = require('fs');
+
+import Logging = require("../Library/Logging");
+import TelemetryClient = require("../Library/TelemetryClient");
+
+class WebSnippet {
+
+    public static INSTANCE: WebSnippet;
+
+    private static _snippet: string;
+    private static _aiUrl: string;
+    private _isEnabled: boolean;
+    private _isInitialized: boolean;
+
+    constructor(client: TelemetryClient) {
+        if (!!WebSnippet.INSTANCE) {
+            throw new Error("Web snippet injection should be configured from the applicationInsights object");
+        }
+
+        WebSnippet.INSTANCE = this;
+        // AI URL used to validate if snippet already included
+        //WebSnippet._aiUrl = "https://az416426.vo.msecnd.net/scripts/b/ai.2";
+        WebSnippet._aiUrl = " https://js.monitor.azure.com/scripts/b/ai.2";
+
+        let snippetPath = path.resolve(__dirname, "../../AutoCollection/WebSnippet/snippet.min.js");
+        if (client.config.isDebugWebSnippet) {
+            snippetPath = path.resolve(__dirname, "../../AutoCollection/WebSnippet/snippet.js");
+        }
+        fs.readFile(snippetPath, function (err, snippet) {
+            if (err) {
+                Logging.warn("Failed to load AI Web snippet. Ex:" + err);
+            }
+            WebSnippet._snippet = snippet.toString().replace("INSTRUMENTATION_KEY", client.config.instrumentationKey);
+        });
+    }
+
+    public enable(isEnabled: boolean) {
+        this._isEnabled = isEnabled;
+
+        if (this._isEnabled && !this._isInitialized) {
+            this._initialize();
+        }
+    }
+
+    public isInitialized() {
+        return this._isInitialized;
+    }
+
+    private _initialize() {
+        this._isInitialized = true;
+        const originalHttpServer = http.createServer;
+        http.createServer = (requestListener?: (request: http.IncomingMessage, response: http.ServerResponse) => void) => {
+            const originalRequestListener = requestListener;
+            if (originalRequestListener) {
+                requestListener = (request: http.IncomingMessage, response: http.ServerResponse) => {
+                    // Patch response write method
+                    let originalResponseWrite = response.write;
+                    let isEnabled = this._isEnabled;
+                    response.write = function wrap(a: Buffer | string, b?: Function | string, c?: Function | string) {
+                        if (isEnabled) {
+                            if (WebSnippet.ValidateInjection(response, a)) {
+                                arguments[0] = WebSnippet.InjectWebSnippet(response, a);
+                            }
+                        }
+                        return originalResponseWrite.apply(response, arguments);
+                    }
+                    // Patch response end method for cases when HTML is added there
+                    let originalResponseEnd = response.end;
+
+                    response.end = function wrap(a?: Buffer | string | any, b?: Function | string, c?: Function) {
+                        if (isEnabled) {
+                            if (WebSnippet.ValidateInjection(response, a)) {
+                                arguments[0] = WebSnippet.InjectWebSnippet(response, a);
+                            }
+                        }
+                        originalResponseEnd.apply(response, arguments);
+                    }
+
+                    originalRequestListener(request, response);
+                }
+            }
+            return originalHttpServer(requestListener);
+        }
+    }
+
+    /**
+     * Validate response and try to inject Web snippet
+     */
+    public static ValidateInjection(response: http.ServerResponse, input: string | Buffer): boolean {
+        if (response && input) {
+            // insert snippet if only response returns 200
+            if (response.statusCode != 200) return false;
+            let contentType = response.getHeader('Content-Type');
+            let contentEncoding = response.getHeader('Content-Encoding'); // Compressed content not supported for injection
+            if (!contentEncoding && contentType && typeof contentType == "string" && contentType.toLowerCase().indexOf("text/html") >= 0) {
+                let html = input.toString();
+                if (html.indexOf("<head>") >= 0 && html.indexOf("</head>") >= 0) {
+                    // Check if snippet not already present looking for AI Web SDK URL
+                    if (html.indexOf(WebSnippet._aiUrl) < 0) {
+                        return true;
+                    }
+                }
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Inject Web snippet
+     */
+    public static InjectWebSnippet(response: http.ServerResponse, input: string | Buffer): string | Buffer {
+        try {
+            let hasContentHeader = !!response.getHeader('Content-Length');
+            // Clean content-length header
+            if (hasContentHeader) {
+                response.removeHeader('Content-Length');
+            }
+            // Read response stream
+            let html = input.toString();
+            // Try to add script before HTML head closure
+            let index = html.indexOf("</head>");
+            if (index >= 0) {
+                let subStart = html.substring(0, index);
+                let subEnd = html.substring(index);
+                input = subStart + '<script type="text/javascript">' + WebSnippet._snippet + '</script>' + subEnd;
+                html = subStart + '<script type="text/javascript">' + WebSnippet._snippet + '</script>' + subEnd;
+                // Set headers
+                if (hasContentHeader) {
+                    response.setHeader("Content-Length", input.length.toString());
+                }
+            }
+        }
+        catch (ex) {
+            Logging.info("Failed to change content-lenght headers for JS injection. Exception:" + ex);
+        }
+        return input;
+    }
+
+    public dispose() {
+        WebSnippet.INSTANCE = null;
+        this.enable(false);
+        this._isInitialized = false;
+    }
+}
+
+export = WebSnippet;

AutoCollection/WebSnippet/fetchSnippet.js

@@ -0,0 +1,26 @@
+const path = require('path');
+const fs = require('fs');
+const https = require('https');
+
+let snippetUrl = 'https://raw.githubusercontent.com/microsoft/ApplicationInsights-JS/master/AISKU/snippet/snippet.js';
+let snippetMinUrl = 'https://raw.githubusercontent.com/microsoft/ApplicationInsights-JS/master/AISKU/snippet/snippet.min.js';
+
+let snippetPath = path.resolve(__dirname, "snippet.js");
+var snippet = fs.createWriteStream(snippetPath);
+https.get(snippetUrl, function (res) {
+    res.on('data', function (data) {
+        snippet.write(data);
+    }).on('end', function () {
+        snippet.end();
+    });
+});
+
+let minSnippetPath = path.resolve(__dirname, "snippet.min.js");
+var minSnippet = fs.createWriteStream(minSnippetPath);
+https.get(snippetMinUrl, function (res) {
+    res.on('data', function (data) {
+        minSnippet.write(data);
+    }).on('end', function () {
+        minSnippet.end();
+    });
+});