Issue 374: Allow an option to choose the hashing algorithm

- hashAlgorithm key added to DEFAULT_OPTIONS
- hashAlgorithm key can be overriden by value given in options argument
- buildOptions function will ensure a default a hashAlgorithm exists,
  and throw an error if the provided option is not supported by the
  system.
  - throws early error during app setup, rather than waiting
    until an upload is attempted
- memHandler and tempFileHandler use the hashAlgorithm option now
- Updated tests for buildOptions function in utilities.spec.js

ref: #374

lib/index.js

@@ -20,7 +20,8 @@ const DEFAULT_OPTIONS = {
   createParentPath: false,
   parseNested: false,
   useTempFiles: false,
-  tempFileDir: path.join(process.cwd(), 'tmp')
+  tempFileDir: path.join(process.cwd(), 'tmp'),
+  hashAlgorithm: 'md5'
 };
 
 /**

lib/memHandler.js

@@ -10,7 +10,7 @@ const { debugLog } = require('./utilities');
  */
 module.exports = (options, fieldname, filename) => {
   const buffers = [];
-  const hash = crypto.createHash('md5');
+  const hash = crypto.createHash(options.hashAlgorithm);
   let fileSize = 0;
   let completed = false;
 

lib/tempFileHandler.js

@@ -14,8 +14,8 @@ module.exports = (options, fieldname, filename) => {
   checkAndMakeDir({ createParentPath: true }, tempFilePath);
 
   debugLog(options, `Temporary file path is ${tempFilePath}`);
- 
-  const hash = crypto.createHash('md5');
+
+  const hash = crypto.createHash(options.hashAlgorithm);
   let fileSize = 0;
   let completed = false;
 

lib/utilities.js

@@ -2,6 +2,7 @@
 
 const fs = require('fs');
 const path = require('path');
+const crypto = require('crypto');
 const { Readable } = require('stream');
 
 // Parameters for safe file name parsing.
@@ -75,6 +76,20 @@ const buildOptions = function() {
     if (!options || typeof options !== 'object') return;
     Object.keys(options).forEach(i => result[i] = options[i]);
   });
+
+  // Ensure a hashAlgorithm option exists.
+  if (!result.hashAlgorithm) {
+    result.hashAlgorithm = 'md5';
+  }
+
+  // Ensure the configured hashAlgorithm is available on the system
+  if (crypto.getHashes().find(h => result.hashAlgorithm === h) === undefined) {
+    throw Error(
+      `Hashing algorithm '${result.hashAlgorithm}' is not supported by this system's OpenSSL ` +
+      `version`
+    );
+  }
+
   return result;
 };
 

test/utilities.spec.js

@@ -199,25 +199,32 @@ describe('utilities: Test of the utilities functions', function() {
   describe('Test buildOptions function', () => {
 
     const source = { option1: '1', option2: '2' };
-    const sourceAddon = { option3: '3'};
-    const expected = { option1: '1', option2: '2' };
-    const expectedAddon = { option1: '1', option2: '2', option3: '3'};
+    const sourceAddon = { option3: '3', hashAlgorithm: 'sha256'};
+    const expected = { option1: '1', option2: '2', hashAlgorithm: 'md5' };
+    const expectedAddon = { option1: '1', option2: '2', option3: '3', hashAlgorithm: 'sha256'};
 
-    it('buildOptions returns and equal object to the object which was paased', () => {
-      let result = buildOptions(source);
-      assert.deepStrictEqual(result, source);
-    });
+    it(
+      'buildOptions returns an equal object to the object which was passed + hashAlgorithm '
+      + 'property',
+      () => {
+        let result = buildOptions(source);
+        assert.deepStrictEqual(result, expected);
+      }
+    );
 
     it('buildOptions doesnt add non object or null arguments to the result', () => {
       let result = buildOptions(source, 2, '3', null);
       assert.deepStrictEqual(result, expected);
     });
 
-    it('buildOptions adds value to the result from the several source argumets', () => {
+    it('buildOptions adds value to the result from the several source arguments', () => {
       let result = buildOptions(source, sourceAddon);
       assert.deepStrictEqual(result, expectedAddon);
     });
 
+    it('buildOptions throws an error when given an unsupported hashAlgorithm', () => {
+      assert.throws(() => buildOptions({ hashAlgorithm: 'not-actual-algo' }));
+    });
   });
   //buildFields tests
   describe('Test buildFields function', () => {