Make Il2Cpp::application.version fallback to IL2CPP module hash

Author: vfsfitvnm

src/application.ts

@@ -40,7 +40,8 @@ namespace Il2Cpp {
         /**
          * Gets the version name of the current application, e.g. `4.12.8`.
          *
-         * **This information is not guaranteed to exist.**
+         * In case the version cannot be retrieved, an hash of the IL2CPP
+         * module is returned instead.
          *
          * ```ts
          * Il2Cpp.perform(() => {
@@ -49,8 +50,8 @@ namespace Il2Cpp {
          * });
          * ```
          */
-        get version(): string | null {
-            return unityEngineCall("get_version");
+        get version(): string {
+            return unityEngineCall("get_version") ?? exportsHash(Il2Cpp.module).toString(16);
         }
     };
 

src/index.ts

@@ -2,6 +2,7 @@
 /// <reference path="./utils/console.ts">/>
 /// <reference path="./utils/decorate.ts">/>
 /// <reference path="./utils/getter.ts">/>
+/// <reference path="./utils/hash.ts">/>
 /// <reference path="./utils/lazy.ts">/>
 /// <reference path="./utils/native-struct.ts">/>
 /// <reference path="./utils/offset-of.ts">/>

src/tracer.ts

@@ -369,24 +369,4 @@ namespace Il2Cpp {
 
         return new Il2Cpp.Tracer(applier());
     }
-
-    /** https://stackoverflow.com/a/52171480/16885569 */
-    function cyrb53(str: string): number {
-        let h1 = 0xdeadbeef;
-        let h2 = 0x41c6ce57;
-
-        for (let i = 0, ch; i < str.length; i++) {
-            ch = str.charCodeAt(i);
-            h1 = Math.imul(h1 ^ ch, 2654435761);
-            h2 = Math.imul(h2 ^ ch, 1597334677);
-        }
-
-        h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
-        h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
-
-        h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
-        h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
-
-        return 4294967296 * (2097151 & h2) + (h1 >>> 0);
-    }
 }

src/utils/hash.ts

@@ -0,0 +1,30 @@
+/** @internal https://stackoverflow.com/a/52171480/16885569 */
+function cyrb53(str: string): number {
+    let h1 = 0xdeadbeef;
+    let h2 = 0x41c6ce57;
+
+    for (let i = 0, ch; i < str.length; i++) {
+        ch = str.charCodeAt(i);
+        h1 = Math.imul(h1 ^ ch, 2654435761);
+        h2 = Math.imul(h2 ^ ch, 1597334677);
+    }
+
+    h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
+    h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
+
+    h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
+    h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
+
+    return 4294967296 * (2097151 & h2) + (h1 >>> 0);
+}
+
+/** @internal */
+function exportsHash(module: Module): number {
+    return cyrb53(
+        module
+            .enumerateExports()
+            .sort((a, b) => a.name.localeCompare(b.name))
+            .map(_ => _.name + _.address.sub(module.base))
+            .join("")
+    );
+}

test/agent/src/assert.ts

@@ -37,7 +37,7 @@ class Assertion<T> {
         }
     }
 
-    not(unexpected: T) {
+    not(unexpected: T | null) {
         if (eq(unexpected, this.actual)) {
             throw new AssertionError(`\x1b[1m${unexpected}\x1b[22m was not expected`);
         }

test/agent/src/index.ts

@@ -11,6 +11,10 @@ Il2Cpp.perform(() => {
         assert(Il2Cpp.application.identifier).is("host");
     });
 
+    test("Application version is detected", () => {
+        assert(Il2Cpp.application.version).not(null);
+    });
+
     test("Il2Cpp.Thread::id", () => {
         assert(Il2Cpp.currentThread?.id).is(Process.getCurrentThreadId());
     });