AM linker

README.md

@@ -192,6 +192,38 @@ rudderanalytics.ready(
 ```
 
 # [](https://github.com/rudderlabs/rudder-sdk-js/blob/master/README.md#adding-callbacks-to-standard-methods)Adding callbacks to standard methods
+| **For detailed technical documentation and troubleshooting guide on the RudderStack’s JavaScript SDK, check out our [docs](https://docs.rudderlabs.com/sdk-integration-guide/getting-started-with-javascript-sdk).** |
+|:------|
+
+# [](https://github.com/rudderlabs/rudder-sdk-js/blob/master/README.md#querystring-api)Querystring API
+
+RudderStack's Querystring API allows you to trigger `track`, `identify` calls using query parameters. If you pass the following parameters in the URL, then it will trigger the corresponding SDK API call.
+
+For example:
+
+```
+http://hostname.com/?ajs_uid=12345&ajs_event=test%20event&ajs_aid=abcde&ajs_prop_testProp=prop1&ajs_trait_name=Firstname+Lastname
+```
+For the above URL, the below SDK calls will be triggered:
+
+```
+rudderanalytics.identify("12345", {name: "Firstname Lastname"});
+rudderanalytics.track("test event", {testProp: "prop1"});
+rudderanalytics.setAnonymousId("abcde");
+```
+
+You may use the below parameters as querystring parameter and trigger the corresponding call.
+
+`ajs_uid` 		: Makes a `rudderanalytics.identify()` call with `userId` having the value of the parameter value.
+
+`ajs_aid` 		: Makes a `rudderanalytics.setAnonymousId()` call with `anonymousId` having the value of the parameter value.
+
+`ajs_event`		: Makes a `rudderanalytics.track()` call with `event` name as parameter value.
+
+`ajs_prop_<property>`	: If `ajs_event` is passed as querystring, value of this parameter will populate the `properties` of the corresponding event in the `track` call.
+
+`ajs_trait_<trait>` 	: If `ajs_uid` is provided as querysting, value of this parameter will populate the `traits` of the `identify` call made.
+
 
 One can also define callbacks to common methods of  `rudderanalytics`  object.  _**Note**_: For now, the functionality is supported for  `syncPixel`  method which is called in Rudder SDK when making sync calls in integrations for relevant destinations.
 

analytics.js

@@ -38,6 +38,7 @@ import { EventRepository } from "./utils/EventRepository";
 import logger from "./utils/logUtil";
 import { addDomEventHandlers } from "./utils/autotrack.js";
 import ScriptLoader from "./integrations/ScriptLoader";
+import parseLinker from "./utils/linker";
 
 const queryDefaults = {
   trait: "ajs_trait_",
@@ -830,9 +831,21 @@ class Analytics {
     return this.anonymousId;
   }
 
-  setAnonymousId(anonymousId) {
+  /**
+   * Sets anonymous id in the followin precedence:
+   * 1. anonymousId: Id directly provided to the function.
+   * 2. rudderAmpLinkerParm: value generated from linker query parm (rudderstack)
+   *    using praseLinker util.
+   * 3. generateUUID: A new uniquie id is generated and assigned.
+   * 
+   * @param {string} anonymousId 
+   * @param {string} rudderAmpLinkerParm 
+   */
+  setAnonymousId(anonymousId, rudderAmpLinkerParm) {
     // if (!this.loaded) return;
-    this.anonymousId = anonymousId || generateUUID();
+    const parsedAnonymousIdObj = rudderAmpLinkerParm ? parseLinker(rudderAmpLinkerParm) : null;
+    const parsedAnonymousId = parsedAnonymousIdObj ? parsedAnonymousIdObj.rs_amp_id : null;
+    this.anonymousId = anonymousId || parsedAnonymousId || generateUUID();
     this.storage.setAnonymousId(this.anonymousId);
   }
 

utils/linker/base64decoder.js

@@ -0,0 +1,26 @@
+/**
+ * @description This is utility function for decoding from base 64 to utf8
+ * @version v1.0.0 
+ */
+
+ /**
+  * @param {string} str base64
+  * @returns {string} utf8 
+  */
+function b64DecodeUnicode(str) {
+  // Going backwards: from bytestream, to percent-encoding, to original string.
+  return decodeURIComponent(atob(str).split('').map(function (c) {
+    return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);
+  }).join(''));
+}
+
+/**
+ * @param {string} value
+ * @return {string}
+ */
+function decode(data = "") {
+  data = data.endsWith("..") ? data.substr(0, data.length - 2) : data;
+  return b64DecodeUnicode(data);
+}
+
+export default decode

utils/linker/crc32.js

@@ -0,0 +1,42 @@
+/**
+ * @description This is utility function for crc32 algorithm
+ * @version v1.0.0 
+ */
+
+/**
+ * @description generate crc table
+ * @params none
+ * @returns arrray of CRC table
+ */
+
+const makeCRCTable = function () {
+  const crcTable = []
+  let c
+  for (var n = 0; n < 256; n++) {
+    c = n
+    for (var k = 0; k < 8; k++) {
+      c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1
+    }
+    crcTable[n] = c
+  }
+  return crcTable
+}
+
+
+/**
+ * 
+ * @param {string} str
+ * @returns {Bystream} crc32
+ */
+const crc32 = function (str) {
+  const crcTable = makeCRCTable()
+  let crc = 0 ^ -1
+
+  for (let i = 0; i < str.length; i++) {
+    crc = (crc >>> 8) ^ crcTable[(crc ^ str.charCodeAt(i)) & 0xff]
+  }
+
+  return (crc ^ -1) >>> 0
+}
+
+export default crc32

utils/linker/index.js

@@ -0,0 +1,140 @@
+/**
+ * @description AMP Linker Parser (works for Rudder, GA or any other linker created by following Google's linker standard.)
+ * @version v1.0.0
+ * @author Parth Mahajan, Ayush Mehra
+ */
+
+import crc32 from "./crc32";
+import USER_INTERFACE from "./userLib";
+import decode from "./base64decoder";
+
+const KEY_VALIDATOR = /^[a-zA-Z0-9\-_.]+$/;
+const CHECKSUM_OFFSET_MAX_MIN = 1;
+const VALID_VERSION = 1;
+const DELIMITER = "*";
+
+/**
+ * Return the key value pairs
+ * @param {string} value
+ * @return {?Object<string, string>}
+ */
+function parseLinker(value) {
+  const linkerObj = parseLinkerParamValue(value);
+  if (!linkerObj) {
+    return null;
+  }
+  const { checksum, serializedIds } = linkerObj;
+  if (!isCheckSumValid(serializedIds, checksum)) {
+    return null;
+  }
+  return deserialize(serializedIds);
+}
+
+/**
+ * Parse the linker param value to version checksum and serializedParams
+ * @param {string} value
+ * @return {?Object}
+ */
+function parseLinkerParamValue(value) {
+  const parts = value.split(DELIMITER);
+  const isEven = parts.length % 2 == 0;
+
+  if (parts.length < 4 || !isEven) {
+    // Format <version>*<checksum>*<key1>*<value1>
+    // Note: linker makes sure there's at least one pair of non empty key value
+    // Make sure there is at least three delimiters.
+    return null;
+  }
+
+  const version = Number(parts.shift());
+  if (version !== VALID_VERSION) {
+    return null;
+  }
+
+  const checksum = parts.shift();
+  const serializedIds = parts.join(DELIMITER);
+  return {
+    checksum,
+    serializedIds,
+  };
+}
+
+/**
+ * Check if the checksum is valid with time offset tolerance.
+ * @param {string} serializedIds
+ * @param {string} checksum
+ * @return {boolean}
+ */
+function isCheckSumValid(serializedIds, checksum) {
+  const userAgent = USER_INTERFACE.getUserAgent();
+  const language = USER_INTERFACE.getUserLanguage();
+  for (let i = 0; i <= CHECKSUM_OFFSET_MAX_MIN; i++) {
+    const calculateCheckSum = getCheckSum(
+      serializedIds,
+      i,
+      userAgent,
+      language
+    );
+    if (calculateCheckSum == checksum) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/**
+ * Deserialize the serializedIds and return keyValue pairs.
+ * @param {string} serializedIds
+ * @return {!Object<string, string>}
+ */
+function deserialize(serializedIds) {
+  const keyValuePairs = {};
+  const params = serializedIds.split(DELIMITER);
+  for (let i = 0; i < params.length; i += 2) {
+    const key = params[i];
+    const valid = KEY_VALIDATOR.test(key);
+    if (!valid) {
+      continue;
+    }
+    const value = decode(params[i + 1]);
+    //const value = params[i + 1];
+    keyValuePairs[key] = value;
+  }
+  return keyValuePairs;
+}
+
+/**
+ * Create a unique checksum hashing the fingerprint and a few other values.
+ * @param {string} serializedIds
+ * @param {number=} opt_offsetMin
+ * @return {string}
+ */
+function getCheckSum(serializedIds, opt_offsetMin, userAgent, language) {
+  const fingerprint = getFingerprint(userAgent, language);
+  const offset = opt_offsetMin || 0;
+  const timestamp = getMinSinceEpoch() - offset;
+  const crc = crc32([fingerprint, timestamp, serializedIds].join(DELIMITER));
+  // Encoded to base36 for less bytes.
+  return crc.toString(36);
+}
+
+/**
+ * Generates a semi-unique value for page visitor.
+ * @return {string}
+ */
+function getFingerprint(userAgent, language) {
+  const date = new Date();
+  const timezone = date.getTimezoneOffset();
+  return [userAgent, timezone, language].join(DELIMITER);
+}
+
+/**
+ * Rounded time used to check if t2 - t1 is within our time tolerance.
+ * @return {number}
+ */
+function getMinSinceEpoch() {
+  // Timestamp in minutes, floored.
+  return Math.floor(Date.now() / 60000);
+}
+
+export default parseLinker;

utils/linker/userLib.js

@@ -0,0 +1,20 @@
+/**
+ * @description An interface to fetch user device details.
+ * @version v1.0.0
+ */
+
+const USER_INTERFACE = {
+  /**
+   * @param {*} req
+   * @returns {string} user language
+   */
+  getUserLanguage: () => navigator && navigator.language,
+
+  /** 
+   * @param {*} req 
+   * @returns {string} userAgent
+   */
+  getUserAgent:  () => navigator && navigator.userAgent
+}
+
+export default USER_INTERFACE;