Add basic validation for contract execute values (#3118)

js/src/util/validation.js

@@ -14,6 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
+import BigNumber from 'bignumber.js';
+
 import util from '../api/util';
 
 export const ERRORS = {
@@ -22,7 +24,10 @@ export const ERRORS = {
   invalidChecksum: 'address has failed the checksum formatting',
   invalidName: 'name should not be blank and longer than 2',
   invalidAbi: 'abi should be a valid JSON array',
-  invalidCode: 'code should be the compiled hex string'
+  invalidCode: 'code should be the compiled hex string',
+  invalidNumber: 'invalid number format',
+  negativeNumber: 'input number should be positive',
+  decimalNumber: 'input number should not contain decimals'
 };
 
 export function validateAbi (abi, api) {
@@ -88,3 +93,23 @@ export function validateName (name) {
     nameError
   };
 }
+
+export function validateUint (value) {
+  let valueError = null;
+
+  try {
+    const bn = new BigNumber(value);
+    if (bn.lt(0)) {
+      valueError = ERRORS.negativeNumber;
+    } else if (bn.toString().indexOf('.') !== -1) {
+      valueError = ERRORS.decimalNumber;
+    }
+  } catch (e) {
+    valueError = ERRORS.invalidNumber;
+  }
+
+  return {
+    value,
+    valueError
+  };
+}