ci: add basic validation for declarative function names (#390)

Adds basic function name validation for registered functions. As almost any sequence of strings can be URL encoded into a valid URL when URL encoded, we check for valid function names using a regex.

Fixes GoogleCloudPlatform#388

Author: grant

src/function_registry.ts

@@ -33,12 +33,31 @@ const register = (
   signatureType: SignatureType,
   userFunction: HandlerFunction
 ): void => {
+  if (!isValidFunctionName(functionName)) {
+    throw new Error(`Invalid function name: ${functionName}`);
+  }
+
   registrationContainer.set(functionName, {
     signatureType,
     userFunction,
   });
 };
 
+/**
+ * Returns true if the function name is valid
+ * - must contain only alphanumeric, numbers, or dash characters
+ * - must be <= 63 characters
+ * - must start with a letter
+ * - must end with a letter or number
+ * @param functionName the function name
+ * @returns true if the function name is valid
+ */
+export const isValidFunctionName = (functionName: string): boolean => {
+  // Validate function name with alpha characters, and dashes
+  const regex = /^[A-Za-z](?:[-_A-Za-z0-9]{0,61}[A-Za-z0-9])?$/;
+  return regex.test(functionName);
+};
+
 /**
  * Get a declaratively registered function
  * @param functionName the name with which the function was registered

test/function_registry.ts

@@ -30,4 +30,22 @@ describe('function_registry', () => {
     assert.deepStrictEqual('cloudevent', signatureType);
     assert.deepStrictEqual((userFunction as () => string)(), 'CE_PASS');
   });
+
+  it('throws an error if you try to register a function with an invalid URL', () => {
+    // Valid function names
+    const validFunctions = ['httpFunction', 'ceFunction', 'test-func'];
+    validFunctions.forEach(functionName => {
+      assert.doesNotThrow(() => {
+        FunctionRegistry.http(functionName, () => 'OK');
+      });
+    });
+
+    // Invalid function names
+    const invalidFunctions = ['', 'foo bar', 'ស្ថានីយ'];
+    invalidFunctions.forEach(functionName => {
+      assert.throws(() => {
+        FunctionRegistry.http(functionName, () => 'OK');
+      });
+    });
+  });
 });