Adding validations to SNTStrategy

gas-relayer/src/strategy/BaseStrategy.js

@@ -10,14 +10,15 @@ class BaseStrategy {
         this.config = config;
     }
 
-    async getBalance(token, message, gasToken){
+    async getBalance(address, token, message, gasToken){
         // Determining balances of token used
+        // TODO: probably token and gasToken can be unified
         if(token.symbol == "ETH"){
-            return new this.web3.utils.BN(await this.web3.eth.getBalance(message.input.address));
+            return new this.web3.utils.BN(await this.web3.eth.getBalance(address));
         } else {
             const Token = new this.web3.eth.Contract(erc20ABI.abi);
             Token.options.address = gasToken;
-            return new this.web3.utils.BN(await Token.methods.balanceOf(message.input.address).call());  
+            return new this.web3.utils.BN(await Token.methods.balanceOf(address).call());  
         }
     }
 

gas-relayer/src/strategy/IdentityStrategy.js

@@ -43,7 +43,7 @@ class IdentityStrategy extends Strategy {
 
         // gasPrice * limit calculation
         const gasToken = params('_gasToken');
-        const balance = await this.getBalance(token, message, gasToken);
+        const balance = await this.getBalance(message.input.address, token, message, gasToken);
         if(balance.lt(this.web3.utils.toBN(gasPrice.mul(gasLimit)))) {
             return {success: false, message: "Identity has not enough tokens for gasPrice*gasLimit"};
         }

gas-relayer/src/strategy/SNTStrategy.js

@@ -1,19 +1,35 @@
 const Strategy = require('./BaseStrategy');
 
+const TransferSNT = "0x916b6511";
+
 class SNTStrategy extends Strategy {
 
     async execute(message){
         const params = this._obtainParametersFunc(message);
 
-        // TODO: logic is needed for executeGasRelayed. 
-
+        // Verifying if token is allowed
+        const token = this.settings.getTokenBySymbol("SNT");
+        if(token == undefined) return {success: false, message: "Token not allowed"};
         
-        // TODO: Transfers are simple and only need to:
-        // -------- estimate cost of transfer
-        // -------- check balance is enough to cover transfer + gas estimate
-        // ------- notify if not enough balance for transfer too.
+        if(message.input.functionName == TransferSNT){
+            const estimatedGas = await this.web3.eth.estimateGas({
+                data: message.input.payload,
+                from: this.config.node.blockchain.account,
+                to: message.input.address
+            });
 
+            const gas = this.web3.utils.toBN(estimatedGas);
+            const balance = await this.getBalance(message.input.wallet, token, message, token.address);
+            const value = this.web3.utils.toBN(params('_amount'));
+            const requiredGas = value.add(gas); // Adding 10% - TODO: tune this value
 
+            if(balance.lt(requiredGas)){
+                return {success: false, message: "Address has not enough balance to transfer specified value + fees (" + requiredGas.toString() + ")"};
+            }
+        } else {
+            // TODO: logic is needed for executeGasRelayed. 
+        }
+        
         return {
             success: true,
             message: "Valid transaction"

test-dapp/app/components/transfersnt.js

@@ -97,7 +97,7 @@ class TransferSNT extends Component {
         }
     }
 
-    sendMessage = event => {
+    sendMessage = async event => {
         event.preventDefault();
 
         const {web3, kid, skid} = this.props;
@@ -117,6 +117,9 @@ class TransferSNT extends Component {
                                                                 this.state.gasPrice, 
                                                                 this.state.signature
                                                                 ]);
+
+            const accounts = await web3.eth.getAccounts();
+
             const sendOptions = {
                 ttl: 1000, 
                 sig: kid,
@@ -126,6 +129,7 @@ class TransferSNT extends Component {
                 symKeyID: skid,
                 payload: web3.utils.toHex({
                     'address': SNTController.options.address,
+                    'wallet': accounts[2],
                     'encodedFunctionCall': funCall
                 })
             };