Fix preparePayment when using source.amount/destination.minAmount (#1295)

See: https://github.com/ripple/ripple-lib/issues/1237#issuecomment-631670946

Fix #1237

Thanks to @leobel

src/transaction/payment.ts

@@ -87,7 +87,12 @@ function applyAnyCounterpartyEncoding(payment: Payment): void {
 
 function createMaximalAmount(amount: Amount): Amount {
   const maxXRPValue = '100000000000'
-  const maxIOUValue = '9999999999999999e80'
+
+  // Equivalent to '9999999999999999e80' but we cannot use that because sign()
+  // now checks that the encoded representation exactly matches the transaction
+  // as it was originally provided.
+  const maxIOUValue = '999999999999999900000000000000000000000000000000000000000000000000000000000000000000000000000000'
+
   let maxValue
   if (amount.currency === 'XRP') {
     maxValue = maxXRPValue

test/api/preparePayment/index.ts

@@ -2,6 +2,11 @@ import {assertResultMatch, TestSuite, assertRejects} from '../../utils'
 import responses from '../../fixtures/responses'
 import requests from '../../fixtures/requests'
 import {ValidationError} from 'ripple-api/common/errors'
+import binary from 'ripple-binary-codec'
+import assert from 'assert-diff'
+import {RippleAPI} from 'ripple-api'
+
+const {schemaValidator} = RippleAPI._PRIVATE
 const instructionsWithMaxLedgerVersionOffset = {maxLedgerVersionOffset: 100}
 const {preparePayment: REQUEST_FIXTURES} = requests
 const {preparePayment: RESPONSE_FIXTURES} = responses
@@ -288,6 +293,55 @@ export default <TestSuite>{
     assertResultMatch(response, RESPONSE_FIXTURES.noCounterparty, 'prepare')
   },
 
+  'preparePayment with source.amount/destination.minAmount can be signed': async (api, address) => {
+    // See also: 'sign succeeds with source.amount/destination.minAmount'
+
+    const localInstructions = {
+      ...instructionsWithMaxLedgerVersionOffset,
+      sequence: 23
+    }
+    const response = await api.preparePayment(
+      address,
+      {
+        "source": {
+          address,
+          "amount": {
+            "currency": "GBP",
+            "value": "0.1",
+            "counterparty": "rpat5TmYjDsnFSStmgTumFgXCM9eqsWPro"
+          }
+        },
+        "destination": {
+          "address": "rEX4LtGJubaUcMWCJULcy4NVxGT9ZEMVRq",
+          "minAmount": {
+            "currency": "USD",
+            "value": "0.1248548562296331",
+            "counterparty": "rMaa8VLBTjwTJWA2kSme4Sqgphhr6Lr6FH"
+          }
+        }
+      },
+      localInstructions
+    )
+
+    // Important: check that the prepared transaction can actually be signed
+    // https://github.com/ripple/ripple-lib/issues/1237#issuecomment-631670946
+
+    const secret = 'shotKgaEotpcYsshSE39vmSnBDRim'
+    const result = api.sign(response.txJSON, secret)
+    const expectedResult = {
+      signedTransaction:
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
+      id: '1C558AA9B926C24FB6BBD6950B2DB1350A83F9F12E4385208867907019761A2D'
+    }
+    const decoded = binary.decode(result.signedTransaction)
+    assert(
+      decoded.Flags === 2147614720,
+      `Flags = ${decoded.Flags}, should be 2147614720`
+    )
+    assert.deepEqual(result, expectedResult)
+    schemaValidator.schemaValidate('sign', result)
+  },
+
   'destination.minAmount': async (api, address) => {
     const response = await api.preparePayment(
       address,

test/api/sign/index.ts

@@ -4,6 +4,7 @@ import binary from 'ripple-binary-codec'
 import requests from '../../fixtures/requests'
 import responses from '../../fixtures/responses'
 import {TestSuite} from '../../utils'
+
 const {schemaValidator} = RippleAPI._PRIVATE
 const {sign: REQUEST_FIXTURES} = requests
 const {sign: RESPONSE_FIXTURES} = responses
@@ -145,6 +146,27 @@ export default <TestSuite>{
     schemaValidator.schemaValidate('sign', result)
   },
 
+  'sign succeeds with source.amount/destination.minAmount': async (api, address) => {
+    // See also: 'preparePayment with source.amount/destination.minAmount'
+
+    const txJSON =
+      '{"TransactionType":"Payment","Account":"r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59","Destination":"rEX4LtGJubaUcMWCJULcy4NVxGT9ZEMVRq","Amount":{"currency":"USD","issuer":"rMaa8VLBTjwTJWA2kSme4Sqgphhr6Lr6FH","value":"999999999999999900000000000000000000000000000000000000000000000000000000000000000000000000000000"},"Flags":2147614720,"SendMax":{"currency":"GBP","issuer":"rpat5TmYjDsnFSStmgTumFgXCM9eqsWPro","value":"0.1"},"DeliverMin":{"currency":"USD","issuer":"rMaa8VLBTjwTJWA2kSme4Sqgphhr6Lr6FH","value":"0.1248548562296331"},"Sequence":23,"LastLedgerSequence":8820051,"Fee":"12"}'
+    const secret = 'shotKgaEotpcYsshSE39vmSnBDRim'
+    const result = api.sign(txJSON, secret)
+    const expectedResult = {
+      signedTransaction:
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
+      id: '1C558AA9B926C24FB6BBD6950B2DB1350A83F9F12E4385208867907019761A2D'
+    }
+    const decoded = binary.decode(result.signedTransaction)
+    assert(
+      decoded.Flags === 2147614720,
+      `Flags = ${decoded.Flags}, should be 2147614720`
+    )
+    assert.deepEqual(result, expectedResult)
+    schemaValidator.schemaValidate('sign', result)
+  },
+
   'throws when encoded tx does not match decoded tx - prepared payment': async (
     api,
     address

test/fixtures/responses/prepare-payment-min-amount.json

@@ -1,5 +1,5 @@
 {
-  "txJSON": "{\"Flags\":2147614720,\"TransactionType\":\"Payment\",\"Account\":\"r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59\",\"Destination\":\"ra5nK24KXen9AHvsdFTKHSANinZseWnPcX\",\"Amount\":{\"value\":\"9999999999999999e80\",\"currency\":\"USD\",\"issuer\":\"ra5nK24KXen9AHvsdFTKHSANinZseWnPcX\"},\"SendMax\":{\"value\":\"5\",\"currency\":\"USD\",\"issuer\":\"r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59\"},\"DeliverMin\":{\"value\":\"4.93463759481038\",\"currency\":\"USD\",\"issuer\":\"ra5nK24KXen9AHvsdFTKHSANinZseWnPcX\"},\"Paths\":[[{\"account\":\"rvYAfWj5gh67oV6fW32ZzP3Aw4Eubs59B\"},{\"currency\":\"XRP\"},{\"issuer\":\"rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q\",\"currency\":\"USD\"},{\"account\":\"rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q\"},{\"account\":\"rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn\"}],[{\"account\":\"rvYAfWj5gh67oV6fW32ZzP3Aw4Eubs59B\"},{\"currency\":\"XRP\"},{\"issuer\":\"rfsEoNBUBbvkf4jPcFe2u9CyaQagLVHGfP\",\"currency\":\"USD\"},{\"account\":\"rfsEoNBUBbvkf4jPcFe2u9CyaQagLVHGfP\"},{\"account\":\"rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q\"}]],\"LastLedgerSequence\":8820051,\"Fee\":\"12\",\"Sequence\":23}",
+  "txJSON": "{\"Flags\":2147614720,\"TransactionType\":\"Payment\",\"Account\":\"r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59\",\"Destination\":\"ra5nK24KXen9AHvsdFTKHSANinZseWnPcX\",\"Amount\":{\"value\":\"999999999999999900000000000000000000000000000000000000000000000000000000000000000000000000000000\",\"currency\":\"USD\",\"issuer\":\"ra5nK24KXen9AHvsdFTKHSANinZseWnPcX\"},\"SendMax\":{\"value\":\"5\",\"currency\":\"USD\",\"issuer\":\"r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59\"},\"DeliverMin\":{\"value\":\"4.93463759481038\",\"currency\":\"USD\",\"issuer\":\"ra5nK24KXen9AHvsdFTKHSANinZseWnPcX\"},\"Paths\":[[{\"account\":\"rvYAfWj5gh67oV6fW32ZzP3Aw4Eubs59B\"},{\"currency\":\"XRP\"},{\"issuer\":\"rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q\",\"currency\":\"USD\"},{\"account\":\"rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q\"},{\"account\":\"rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn\"}],[{\"account\":\"rvYAfWj5gh67oV6fW32ZzP3Aw4Eubs59B\"},{\"currency\":\"XRP\"},{\"issuer\":\"rfsEoNBUBbvkf4jPcFe2u9CyaQagLVHGfP\",\"currency\":\"USD\"},{\"account\":\"rfsEoNBUBbvkf4jPcFe2u9CyaQagLVHGfP\"},{\"account\":\"rMwjYedjc7qqtKYVLiAccJSmCwih4LnE2q\"}]],\"LastLedgerSequence\":8820051,\"Fee\":\"12\",\"Sequence\":23}",
   "instructions": {
     "fee": "0.000012",
     "sequence": 23,