crypto: createDiffieHellman throw for bad args

Previously crypto.createDiffieHellman() would fail silently when a bad
argument was passed for prime/prime_length. Now throws TypeError.

Fixes: https://github.com/joyent/node/issues/8480
Signed-off-by: Trevor Norris <trev.norris@gmail.com>

lib/crypto.js

@@ -376,6 +376,11 @@ function DiffieHellman(sizeOrKey, keyEncoding, generator, genEncoding) {
   if (!(this instanceof DiffieHellman))
     return new DiffieHellman(sizeOrKey, keyEncoding, generator, genEncoding);
 
+  if (!util.isBuffer(sizeOrKey) &&
+      typeof sizeOrKey !== 'number' &&
+      typeof sizeOrKey !== 'string')
+    throw new TypeError('First argument should be number, string or Buffer');
+
   if (keyEncoding) {
     if (typeof keyEncoding !== 'string' ||
         (!Buffer.isEncoding(keyEncoding) && keyEncoding !== 'buffer')) {

test/simple/test-crypto.js

@@ -719,6 +719,22 @@ assert.equal(secret1, secret2.toString('base64'));
 assert.equal(dh1.verifyError, 0);
 assert.equal(dh2.verifyError, 0);
 
+assert.throws(function() {
+  crypto.createDiffieHellman([0x1, 0x2]);
+});
+
+assert.throws(function() {
+  crypto.createDiffieHellman(function() { });
+});
+
+assert.throws(function() {
+  crypto.createDiffieHellman(/abc/);
+});
+
+assert.throws(function() {
+  crypto.createDiffieHellman({});
+});
+
 // Create "another dh1" using generated keys from dh1,
 // and compute secret again
 var dh3 = crypto.createDiffieHellman(p1, 'buffer');