crypto: add getIntOption function to reduce dupl

This commit adds a getIntOption function to reduce the code duplicated
for getting the padding, and saltLength options.

PR-URL: #20247
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/internal/crypto/sig.js

@@ -53,6 +53,25 @@ Sign.prototype.update = function update(data, encoding) {
  return this;
 };
 
+function getPadding(options) {
+ return getIntOption('padding', RSA_PKCS1_PADDING, options);
+}
+
+function getSaltLength(options) {
+ return getIntOption('saltLength', RSA_PSS_SALTLEN_AUTO, options);
+}
+
+function getIntOption(name, defaultValue, options) {
+ if (options.hasOwnProperty(name)) {
+ if (options[name] === options[name] >> 0) {
+ return options[name];
+ } else {
+ throw new ERR_INVALID_OPT_VALUE(name, options[name]);
+ }
+ }
+ return defaultValue;
+}
+
 Sign.prototype.sign = function sign(options, encoding) {
  if (!options)
  throw new ERR_CRYPTO_SIGN_KEY_REQUIRED();
@@ -61,23 +80,9 @@ Sign.prototype.sign = function sign(options, encoding) {
  var passphrase = options.passphrase || null;
 
  // Options specific to RSA
- var rsaPadding = RSA_PKCS1_PADDING;
- if (options.hasOwnProperty('padding')) {
- if (options.padding === options.padding >> 0) {
- rsaPadding = options.padding;
- } else {
- throw new ERR_INVALID_OPT_VALUE('padding', options.padding);
- }
- }
+ var rsaPadding = getPadding(options);
 
- var pssSaltLength = RSA_PSS_SALTLEN_AUTO;
- if (options.hasOwnProperty('saltLength')) {
- if (options.saltLength === options.saltLength >> 0) {
- pssSaltLength = options.saltLength;
- } else {
- throw new ERR_INVALID_OPT_VALUE('saltLength', options.saltLength);
- }
- }
+ var pssSaltLength = getSaltLength(options);
 
  key = toBuf(key);
  if (!isArrayBufferView(key)) {
@@ -119,23 +124,9 @@ Verify.prototype.verify = function verify(options, signature, sigEncoding) {
  sigEncoding = sigEncoding || getDefaultEncoding();
 
  // Options specific to RSA
- var rsaPadding = RSA_PKCS1_PADDING;
- if (options.hasOwnProperty('padding')) {
- if (options.padding === options.padding >> 0) {
- rsaPadding = options.padding;
- } else {
- throw new ERR_INVALID_OPT_VALUE('padding', options.padding);
- }
- }
+ var rsaPadding = getPadding(options);
 
- var pssSaltLength = RSA_PSS_SALTLEN_AUTO;
- if (options.hasOwnProperty('saltLength')) {
- if (options.saltLength === options.saltLength >> 0) {
- pssSaltLength = options.saltLength;
- } else {
- throw new ERR_INVALID_OPT_VALUE('saltLength', options.saltLength);
- }
- }
+ var pssSaltLength = getSaltLength(options);
 
  key = toBuf(key);
  if (!isArrayBufferView(key)) {