solana gas dropoff rent min to fresh wallets (#1082)

Co-authored-by: Evan Gray <battledingo@gmail.com>

sdk/src/contexts/solana/context.ts

@@ -1040,7 +1040,18 @@ export class SolanaContext<
       BigNumber.from(amount).toBigInt(),
       decimals,
     );
-    return BigNumber.from(nativeTokenAmount);
+    // an non-existent account cannot be sent less than the rent exempt amount
+    // in order to create the wallet, it must be sent at least the rent exemption minimum
+    const acctExists =
+      (await this.connection!.getAccountInfo(new PublicKey(walletAddress))) !==
+      null;
+    if (acctExists) return BigNumber.from(nativeTokenAmount);
+    const minBalance = await this.connection!.getMinimumBalanceForRentExemption(
+      0,
+    );
+    return nativeTokenAmount > minBalance
+      ? BigNumber.from(nativeTokenAmount)
+      : BigNumber.from(0);
   }
 
   async calculateMaxSwapAmount(

wormhole-connect/src/utils/routes/operator.ts

@@ -1,3 +1,4 @@
+import { PublicKey } from '@solana/web3.js';
 import {
   ChainId,
   ChainName,
@@ -12,7 +13,14 @@ import { RelayRoute } from './relay';
 // import { HashflowRoute } from './hashflow';
 import { CCTPRelayRoute } from './cctpRelay';
 import { CosmosGatewayRoute } from './cosmosGateway';
-import { ParsedMessage, PayloadType, getMessage, isEvmChain, wh } from '../sdk';
+import {
+  ParsedMessage,
+  PayloadType,
+  getMessage,
+  isEvmChain,
+  solanaContext,
+  wh,
+} from '../sdk';
 import { isCosmWasmChain } from '../cosmos';
 import RouteAbstract from './routeAbstract';
 import {
@@ -484,6 +492,29 @@ export class Operator {
     return r.maxSwapAmount(destChain, token, walletAddress);
   }
 
+  async minSwapAmountNative(
+    route: Route,
+    destChain: ChainName | ChainId,
+    token: TokenId,
+    walletAddress: string,
+  ): Promise<BigNumber> {
+    const chainName = wh.toChainName(destChain);
+    if (chainName === 'solana') {
+      const context = solanaContext();
+      // an non-existent account cannot be sent less than the rent exempt amount
+      // in order to create the wallet, it must be sent at least the rent exemption minimum
+      const acctExists =
+        (await context.connection!.getAccountInfo(
+          new PublicKey(walletAddress),
+        )) !== null;
+      if (acctExists) return BigNumber.from(0);
+      const minBalance =
+        await context.connection!.getMinimumBalanceForRentExemption(0);
+      return BigNumber.from(minBalance);
+    }
+    return BigNumber.from(0);
+  }
+
   tryFetchRedeemTx(
     route: Route,
     txData: UnsignedMessage,

wormhole-connect/src/views/Bridge/NativeGasSlider.tsx

@@ -1,6 +1,6 @@
 import Slider, { SliderThumb } from '@mui/material/Slider';
 import { styled } from '@mui/material/styles';
-import { BigNumber, utils } from 'ethers';
+import { utils } from 'ethers';
 import React, { useEffect, useMemo, useState } from 'react';
 import { useDispatch, useSelector } from 'react-redux';
 import { makeStyles } from 'tss-react/mui';
@@ -88,6 +88,7 @@ function formatAmount(amount?: number): number {
 
 const INITIAL_STATE = {
   disabled: false,
+  min: 0,
   max: 0,
   nativeGas: 0,
   token: formatAmount(),
@@ -137,7 +138,7 @@ function GasSlider(props: { disabled: boolean }) {
     if (actualMaxSwap) {
       // address the bug that the swapAmount='maxSwapAmount' results in a 'minimumSendAmount'
       // that could be higher than 'amount' (due to the buffer packed into minimumSendAmount)
-      // not a perfect fix for all posible 'getMinSendAmount' functions - but valid for linear ones
+      // not a perfect fix for all possible 'getMinSendAmount' functions - but valid for linear ones
       //
       // For example, if 'amount' is 1.1, and relayerFee is 1, then 'amountNum' (the receive amount) is
       // 0.1, and 'actualMaxSwap' is 0.1.
@@ -178,30 +179,35 @@ function GasSlider(props: { disabled: boolean }) {
       !RouteOperator.getRoute(route).NATIVE_GAS_DROPOFF_SUPPORTED ||
       !receivingWallet.address ||
       !receivingToken
-    )
+    ) {
       return;
+    }
 
-    const tokenId = receivingToken.tokenId!;
-    RouteOperator.maxSwapAmount(
-      route,
-      toChain,
-      tokenId,
-      receivingWallet.address,
-    )
-      .then((res: BigNumber) => {
-        if (!res) {
+    let cancelled = false;
+    (async () => {
+      const tokenId = receivingToken.tokenId!;
+
+      try {
+        const maxSwapAmount = await RouteOperator.maxSwapAmount(
+          route,
+          toChain,
+          tokenId,
+          receivingWallet.address,
+        );
+        if (cancelled) return;
+        if (!maxSwapAmount) {
           dispatch(setMaxSwapAmt(undefined));
           return;
         }
         const toChainDecimals = getTokenDecimals(
           wh.toChainId(toChain),
           tokenId,
         );
-        const amt = toDecimals(res, toChainDecimals, 6);
+        const amt = toDecimals(maxSwapAmount, toChainDecimals, 6);
         dispatch(setMaxSwapAmt(Number.parseFloat(amt)));
-      })
-      .catch((e) => {
-        if (e.message.includes('swap rate not set')) {
+      } catch (e: any) {
+        if (cancelled) return;
+        if (e.message?.includes('swap rate not set')) {
           if (route === Route.CCTPRelay) {
             dispatch(setTransferRoute(Route.CCTPManual));
           } else {
@@ -210,13 +216,32 @@ function GasSlider(props: { disabled: boolean }) {
         } else {
           throw e;
         }
-      });
+      }
 
-    // get conversion rate of token
-    const { gasToken } = CHAINS[toChain]!;
-    getConversion(token, gasToken).then((res: number) => {
-      setState((prevState) => ({ ...prevState, conversionRate: res }));
-    });
+      // get conversion rate of token
+      const { gasToken } = CHAINS[toChain]!;
+      const conversionRate = await getConversion(token, gasToken);
+      if (cancelled) return;
+      const minNative = await RouteOperator.minSwapAmountNative(
+        route,
+        toChain,
+        tokenId,
+        receivingWallet.address,
+      );
+      const minNativeAdjusted = Number.parseFloat(
+        toDecimals(
+          minNative,
+          getTokenDecimals(wh.toChainId(toChain), 'native'),
+        ),
+      );
+      if (cancelled) return;
+      const min = conversionRate ? minNativeAdjusted / conversionRate : 0;
+      setState((prevState) => ({ ...prevState, conversionRate, min }));
+    })();
+
+    return () => {
+      cancelled = true;
+    };
   }, [
     sendingToken,
     receivingToken,
@@ -255,9 +280,10 @@ function GasSlider(props: { disabled: boolean }) {
   // compute amounts on change
   const handleChange = (e: any) => {
     if (!amountNum || !state.conversionRate) return;
-    const newGasAmount = e.target.value * state.conversionRate;
-    const newTokenAmount = amountNum - e.target.value;
-    const swapAmount = e.target.value;
+    const value = e.target.value < state.min ? 0 : e.target.value;
+    const newGasAmount = value * state.conversionRate;
+    const newTokenAmount = amountNum - value;
+    const swapAmount = value;
     const conversion = {
       nativeGas: formatAmount(newGasAmount),
       token: formatAmount(newTokenAmount),
@@ -368,6 +394,9 @@ function GasSlider(props: { disabled: boolean }) {
                 }
                 valueLabelDisplay="auto"
                 onChange={handleChange}
+                marks={
+                  state.min ? [{ value: state.min, label: 'Min' }] : undefined
+                }
               />
               <div className={classes.amounts}>
                 <div className={classes.amountDisplay}>