Adds sub-account support for escrows (#149)

* Coins are now holded by sub-accounts and not by the escrow module

* Use cosmos-sdk v0.44 function Module() to generate unique addresses for each escrow, closes #99

x/escrow/keeper/escrow.go

@@ -199,7 +199,8 @@ func (k Keeper) TransferToEscrow(
 	}
 
 	// Send the price to the module
-	err = k.bankKeeper.SendCoinsFromAccountToModule(ctx, buyer, types.ModuleName, escrow.Price)
+
+	err = k.transferCoinsToEscrow(ctx, buyer, escrow.Id, escrow.Price)
 	if err != nil {
 		return sdkerrors.Wrap(err, "Cannot send the coins to the escrow")
 	}
@@ -232,11 +233,11 @@ func (k Keeper) doSwap(ctx sdk.Context, escrow types.Escrow, buyer, seller sdk.A
 	brokerCoins, _ := sdk.NewDecCoinsFromCoins(escrow.Price...).MulDec(escrow.BrokerCommission).TruncateDecimal()
 	sellerCoins := escrow.Price.Sub(brokerCoins)
 
-	err = k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, broker, brokerCoins)
+	err = k.transferCoinsFromEscrow(ctx, escrow.Id, broker, brokerCoins)
 	if err != nil {
 		return sdkerrors.Wrap(err, "Cannot send the coins to the broker")
 	}
-	err = k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, seller, sellerCoins)
+	err = k.transferCoinsFromEscrow(ctx, escrow.Id, seller, sellerCoins)
 	if err != nil {
 		return sdkerrors.Wrap(err, "Cannot send the coins to the seller")
 	}
@@ -300,6 +301,26 @@ func (k Keeper) doObjectTransfer(ctx sdk.Context, from, to sdk.AccAddress, objec
 	return err
 }
 
+// transferCoinsFromAccountToAccountThroughModule sends coins from an account to another through the escrow module.
+// It is intended to use between a module sub-account and a regular only.
+func (k Keeper) transferCoinsFromAccountToAccountThroughModule(ctx sdk.Context, from sdk.AccAddress, to sdk.AccAddress, coins sdk.Coins) error {
+	err := k.bankKeeper.SendCoinsFromAccountToModule(ctx, from, types.ModuleName, coins)
+	if err != nil {
+		return err
+	}
+	return k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, to, coins)
+}
+
+// transferCoinsToEscrow transfers coins from an account to an escrow account
+func (k Keeper) transferCoinsToEscrow(ctx sdk.Context, from sdk.AccAddress, toEscrowId string, coins sdk.Coins) error {
+	return k.transferCoinsFromAccountToAccountThroughModule(ctx, from, k.GetEscrowAddress(toEscrowId), coins)
+}
+
+// transferCoinsFromEscrow transfers coins from an escrow account to an account
+func (k Keeper) transferCoinsFromEscrow(ctx sdk.Context, fromEscrowId string, to sdk.AccAddress, coins sdk.Coins) error {
+	return k.transferCoinsFromAccountToAccountThroughModule(ctx, k.GetEscrowAddress(fromEscrowId), to, coins)
+}
+
 func (k Keeper) addEscrowToDeadlineStore(ctx sdk.Context, escrow types.Escrow) {
 	k.getDeadlineStore(ctx).Set(types.GetDeadlineKey(escrow.Deadline, escrow.Id), types.GetEscrowKey(escrow.Id))
 }

x/escrow/keeper/keeper.go

@@ -3,6 +3,7 @@ package keeper
 import (
 	"encoding/hex"
 	"fmt"
+	"github.com/cosmos/cosmos-sdk/types/address"
 	"time"
 
 	"github.com/cosmos/cosmos-sdk/store"
@@ -86,10 +87,7 @@ func (k Keeper) Logger(ctx sdk.Context) log.Logger {
 
 // GetEscrowAddress returns the address of the escrow account
 func (k Keeper) GetEscrowAddress(id string) sdk.AccAddress {
-	//TODO: use the changes introduced by https://github.com/cosmos/cosmos-sdk/pull/9088 in v0.43 to effectively have one account per escrow
-	return k.accountKeeper.GetModuleAddress(types.ModuleName)
-	// We could use this instead, but it is not optimal and increases probability of collision
-	// return k.accountKeeper.GetModuleAddress(types.ModuleName + id)
+	return address.Module(types.ModuleName, []byte(id))
 }
 
 func (k Keeper) ImportNextID(ctx sdk.Context, nextID uint64) {