fix(limit-order): limit max salt and amounts (#20)

src/limit-order/limit-order.ts

@@ -1,5 +1,5 @@
 import {AbiCoder} from 'ethers'
-import {isHexString, UINT_160_MAX} from '@1inch/byte-utils'
+import {isHexString, UINT_160_MAX, UINT_256_MAX} from '@1inch/byte-utils'
 import assert from 'assert'
 import {
     buildOrderTypedData,
@@ -11,6 +11,7 @@ import {LimitOrderV4Struct, OrderInfoData} from './types'
 import {MakerTraits} from './maker-traits'
 import {Extension} from './extension'
 import {Address} from '../address'
+import {randBigInt} from '../utils/rand-bigint'
 
 export class LimitOrder {
     private static readonly Web3Type = `tuple(${[
@@ -54,6 +55,10 @@ export class LimitOrder {
         this.receiver = orderInfo.receiver || Address.ZERO_ADDRESS
         this.makerTraits = makerTraits
 
+        assert(this.salt <= UINT_256_MAX, 'salt too big')
+        assert(this.makingAmount <= UINT_256_MAX, 'makingAmount too big')
+        assert(this.takingAmount <= UINT_256_MAX, 'takingAmount too big')
+
         if (!extension.isEmpty()) {
             this.makerTraits.withExtension()
         }
@@ -70,7 +75,7 @@ export class LimitOrder {
      */
     static buildSalt(
         extension: Extension,
-        baseSalt = BigInt(Math.round(Math.random() * Date.now()))
+        baseSalt = randBigInt((2n << 96n) - 1n)
     ): bigint {
         if (extension.isEmpty()) {
             return baseSalt

src/utils/rand-bigint.spec.ts

@@ -0,0 +1,14 @@
+import {randBigInt} from './rand-bigint'
+
+describe('randBigint', () => {
+    it('should generate rand bigint in correct interval', () => {
+        expect(randBigInt(1)).toBeGreaterThanOrEqual(0n)
+        expect(randBigInt(1)).toBeLessThanOrEqual(1n)
+
+        expect(randBigInt(10n)).toBeGreaterThanOrEqual(0)
+        expect(randBigInt(10n)).toBeLessThanOrEqual(10n)
+
+        expect(randBigInt(2n << 96n)).toBeGreaterThanOrEqual(0)
+        expect(randBigInt(2n << 96n)).toBeLessThanOrEqual(2n << 96n)
+    })
+})

src/utils/rand-bigint.ts

@@ -1,3 +1,20 @@
-export function randBigInt(max: number): bigint {
-    return BigInt(Math.floor(Math.random() * max))
+import {randomBytes} from 'ethers'
+
+export function randBigInt(max: number | bigint): bigint {
+    let bytesCount = 0
+    max = BigInt(max) + 1n
+    let rest = max
+    while (rest) {
+        rest = rest >> 8n
+        bytesCount += 1
+    }
+
+    const bytes = randomBytes(bytesCount)
+
+    const val = bytes.reduce(
+        (acc, val, i) => acc + (BigInt(val) << BigInt(i * 8)),
+        0n
+    )
+
+    return val % max
 }