Limit to 100 env vars per layer

Author: monkbroc

lib/moduleEncoding.js

@@ -28,6 +28,7 @@ const ENV_ASSET_NAME = 'env';
 const ENV_JSON_FILE = 'env.json';
 
 const MAX_ENV_SIZE = 16 * 1024;
+const MAX_ENV_VARS = 100;
 
 function moduleFunctionToString(func) {
 	switch (func) {
@@ -1683,12 +1684,16 @@ async function createProtectedModule(module, certificate) {
  * @param {String|Number} snapshot.updatedAt Snapshot creation time. Can be a string in a format
  *        supported by `Date.parse()` or a numeric timestamp.
  * @param {Number} [maxSize=MAX_ENV_SIZE] Maximum allowed size of the resulting module.
+ * @param {Number} [maxVars=MAX_ENV_VARS] Maximum allowed number of variables in the resulting module.
  * @returns {Promise<Buffer>} Asset data.
  */
-async function encodeEnvVarsAsset(vars, snapshot = undefined, maxSize = MAX_ENV_SIZE) {
+async function encodeEnvVarsAsset(vars, snapshot = undefined, maxSize = MAX_ENV_SIZE, maxVars = MAX_ENV_VARS) {
 	if (!vars || typeof vars !== 'object') {
 		throw new Error('Expected variable values to be an object');
 	}
+	if (Object.keys(vars).length > maxVars) {
+		throw new Error(`Number of variables exceeds the maximum of ${maxVars}`);
+	}
 	if (JSON.stringify(vars).length > maxSize) {
 		throw new Error('Asset exceeds the maximum size');
 	}
@@ -1745,17 +1750,18 @@ async function encodeEnvVarsAsset(vars, snapshot = undefined, maxSize = MAX_ENV_
  * @param {String|Number} snapshot.updatedAt Snapshot creation time. Can be a string in a format
  *        supported by `Date.parse()` or a numeric timestamp.
  * @param {Number} [maxSize=MAX_ENV_SIZE] Maximum allowed size of the resulting module.
+ * @param {Number} [maxVars=MAX_ENV_VARS] Maximum allowed number of variables in the resulting module.
  * @returns {Promise<Buffer>} Module binary.
  */
-async function createEnvVarsAssetModule(vars, snapshot = undefined, maxSize = MAX_ENV_SIZE) {
+async function createEnvVarsAssetModule(vars, snapshot = undefined, maxSize = MAX_ENV_SIZE, maxVars = MAX_ENV_VARS) {
 	let assetData;
 	if (Buffer.isBuffer(vars)) {
 		if (snapshot) {
 			throw new Error('Cannot set snapshot details in already encoded asset data');
 		}
 		assetData = vars;
 	} else {
-		assetData = await encodeEnvVarsAsset(vars, snapshot, maxSize);
+		assetData = await encodeEnvVarsAsset(vars, snapshot, maxSize, maxVars);
 	}
 
 	const assetModule = await createAssetModule(assetData, ENV_ASSET_NAME, {

specs/lib/moduleEncoding.spec.js

@@ -1039,6 +1039,16 @@ describe('moduleEncoding', () => {
 				const msg = 'Asset exceeds the maximum size';
 				await expect(createEnvVarsAssetModule({ 'ABC': '1'.repeat(20000) })).to.be.eventually.rejectedWith(Error, msg);
 			});
+
+
+			it('asset exceeds the maximum number of variables', async () => {
+				const msg = 'Number of variables exceeds the maximum of 100';
+				const vars = {};
+				for (let i = 0; i < 101; i++) {
+					vars['VAR' + i] = 'value';
+				}
+				await expect(createEnvVarsAssetModule(vars)).to.be.eventually.rejectedWith(Error, msg);
+			});
 		});
 	});
 });