sdk: quote destination amount truncation fix (#560)

* sdk: quote destination amount truncation fix

Fixes an issue where calling quote with an amount that has
more fractional digits than the destination chain supports
throws an error. We need to truncate and scale the destination
amount to destination chain decimals.

* refactor

* rename, added comments

* rename function

Author: kev1n-peters

sdk/route/src/automatic.ts

@@ -121,12 +121,17 @@ export class NttAutomaticRoute<N extends Network>
       request.toChain.config.nativeTokenDecimals
     );
 
-    const amt = amount.parse(params.amount, request.source.decimals);
+    const parsedAmount = amount.parse(params.amount, request.source.decimals);
+    // The trimmedAmount may differ from the parsedAmount if the parsedAmount includes dust
+    const trimmedAmount = NttRoute.trimAmount(
+      parsedAmount,
+      request.destination.decimals
+    );
 
     const validatedParams: Vp = {
       amount: params.amount,
       normalizedParams: {
-        amount: amt,
+        amount: trimmedAmount,
         sourceContracts: NttRoute.resolveNttContracts(
           this.staticConfig,
           request.source.id
@@ -160,6 +165,11 @@ export class NttAutomaticRoute<N extends Network>
       params.normalizedParams.options
     );
 
+    const dstAmount = amount.scale(
+      params.normalizedParams.amount,
+      request.destination.decimals
+    );
+
     const result: QR = {
       success: true,
       params,
@@ -169,7 +179,7 @@ export class NttAutomaticRoute<N extends Network>
       },
       destinationToken: {
         token: request.destination.id,
-        amount: amount.parse(params.amount, request.destination.decimals),
+        amount: dstAmount,
       },
       relayFee: {
         token: Wormhole.tokenId(fromChain.chain, "native"),
@@ -190,10 +200,6 @@ export class NttAutomaticRoute<N extends Network>
     const duration = await dstNtt.getRateLimitDuration();
     if (duration > 0n) {
       const capacity = await dstNtt.getCurrentInboundCapacity(fromChain.chain);
-      const dstAmount = amount.parse(
-        params.amount,
-        request.destination.decimals
-      );
       if (
         NttRoute.isCapacityThresholdExceeded(amount.units(dstAmount), capacity)
       ) {

sdk/route/src/manual.ts

@@ -102,7 +102,13 @@ export class NttManualRoute<N extends Network>
   ): Promise<Vr> {
     const options = params.options ?? this.getDefaultOptions();
 
-    const amt = amount.parse(params.amount, request.source.decimals);
+    const parsedAmount = amount.parse(params.amount, request.source.decimals);
+    // The trimmedAmount may differ from the parsedAmount if the parsedAmount includes dust
+    const trimmedAmount = NttRoute.trimAmount(
+      parsedAmount,
+      request.destination.decimals
+    );
+
     const gasDropoff = amount.units(
       amount.parse(
         options.gasDropoff ?? "0.0",
@@ -113,7 +119,7 @@ export class NttManualRoute<N extends Network>
     const validatedParams: Vp = {
       amount: params.amount,
       normalizedParams: {
-        amount: amt,
+        amount: trimmedAmount,
         sourceContracts: NttRoute.resolveNttContracts(
           this.staticConfig,
           request.source.id
@@ -137,6 +143,11 @@ export class NttManualRoute<N extends Network>
     request: routes.RouteTransferRequest<N>,
     params: Vp
   ): Promise<QR> {
+    const dstAmount = amount.scale(
+      params.normalizedParams.amount,
+      request.destination.decimals
+    );
+
     const result: QR = {
       success: true,
       params,
@@ -146,7 +157,7 @@ export class NttManualRoute<N extends Network>
       },
       destinationToken: {
         token: request.destination.id,
-        amount: amount.parse(params.amount, request.destination.decimals),
+        amount: dstAmount,
       },
       eta: finality.estimateFinalityTime(request.fromChain.chain),
     };
@@ -157,10 +168,6 @@ export class NttManualRoute<N extends Network>
     const duration = await dstNtt.getRateLimitDuration();
     if (duration > 0n) {
       const capacity = await dstNtt.getCurrentInboundCapacity(fromChain.chain);
-      const dstAmount = amount.parse(
-        params.amount,
-        request.destination.decimals
-      );
       if (
         NttRoute.isCapacityThresholdExceeded(amount.units(dstAmount), capacity)
       ) {

sdk/route/src/types.ts

@@ -18,6 +18,8 @@ export namespace NttRoute {
   // Currently only wormhole attestations supported
   export type TransceiverType = "wormhole";
 
+  export const TRIMMED_DECIMALS = 8;
+
   export type TransceiverConfig = {
     type: TransceiverType;
     address: string;
@@ -212,4 +214,16 @@ export namespace NttRoute {
     const threshold = (capacity * 95n) / 100n;
     return amount > threshold;
   }
+
+  export function trimAmount(
+    amt: amount.Amount,
+    dstTokenDecimals: number
+  ): amount.Amount {
+    // remove dust to avoid `TransferAmountHasDust` revert reason
+    const truncatedAmount = amount.truncate(
+      amt,
+      Math.min(amt.decimals, dstTokenDecimals, NttRoute.TRIMMED_DECIMALS)
+    );
+    return truncatedAmount;
+  }
 }