refactor: (x/feegrant) parsing keys (#11814)

## Description

ref: #11362



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

x/feegrant/keeper/keeper.go

@@ -322,9 +322,8 @@ func (k Keeper) RemoveExpiredAllowances(ctx sdk.Context) {
 
 	for ; iterator.Valid(); iterator.Next() {
 		store.Delete(iterator.Key())
-		expLen := len(sdk.FormatTimeBytes(ctx.BlockTime()))
 
-		// extract the fee allowance key by removing the allowance queue prefix length, expiration length from key.
-		store.Delete(append(feegrant.FeeAllowanceKeyPrefix, iterator.Key()[1+expLen:]...))
+		granter, grantee := feegrant.ParseAddressesFromFeeAllowanceQueueKey(iterator.Key())
+		store.Delete(feegrant.FeeAllowanceKey(granter, grantee))
 	}
 }

x/feegrant/key.go

@@ -5,7 +5,6 @@ import (
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/address"
-	"github.com/cosmos/cosmos-sdk/types/kv"
 )
 
 const (
@@ -67,17 +66,31 @@ func AllowanceByExpTimeKey(exp *time.Time) []byte {
 	return append(FeeAllowanceQueueKeyPrefix, sdk.FormatTimeBytes(*exp)...)
 }
 
-// ParseAddressesFromFeeAllowanceKey exrtacts and returns the granter, grantee from the given key.
+// ParseAddressesFromFeeAllowanceKey extracts and returns the granter, grantee from the given key.
 func ParseAddressesFromFeeAllowanceKey(key []byte) (granter, grantee sdk.AccAddress) {
+
 	// key is of format:
 	// 0x00<granteeAddressLen (1 Byte)><granteeAddress_Bytes><granterAddressLen (1 Byte)><granterAddress_Bytes>
-	kv.AssertKeyAtLeastLength(key, 2)
-	granteeAddrLen := key[1] // remove prefix key
-	kv.AssertKeyAtLeastLength(key, 2+int(granteeAddrLen))
-	grantee = sdk.AccAddress(key[2 : 2+int(granteeAddrLen)])
-	granterAddrLen := int(key[2+granteeAddrLen])
-	kv.AssertKeyAtLeastLength(key, 3+int(granteeAddrLen)+int(granterAddrLen))
-	granter = sdk.AccAddress(key[3+granterAddrLen : 3+int(granteeAddrLen)+int(granterAddrLen)])
+	granterAddrLen, granterAddrLenEndIndex := sdk.ParseLengthPrefixedBytes(key, 1, 1) // ignore key[0] since it is a prefix key
+	grantee, granterAddrEndIndex := sdk.ParseLengthPrefixedBytes(key, granterAddrLenEndIndex+1, int(granterAddrLen[0]))
+
+	granteeAddrLen, granteeAddrLenEndIndex := sdk.ParseLengthPrefixedBytes(key, granterAddrEndIndex+1, 1)
+	granter, _ = sdk.ParseLengthPrefixedBytes(key, granteeAddrLenEndIndex+1, int(granteeAddrLen[0]))
+
+	return granter, grantee
+}
+
+// ParseAddressesFromFeeAllowanceQueueKey extracts and returns the granter, grantee from the given key.
+func ParseAddressesFromFeeAllowanceQueueKey(key []byte) (granter, grantee sdk.AccAddress) {
+	var lenTime = len(sdk.FormatTimeBytes(time.Now()))
+
+	// key is of format:
+	// <0x01><expiration_bytes(fixed length)><granteeAddressLen (1 Byte)><granteeAddress_Bytes><granterAddressLen (1 Byte)><granterAddress_Bytes>
+	granterAddrLen, granterAddrLenEndIndex := sdk.ParseLengthPrefixedBytes(key, 1+lenTime, 1) // ignore key[0] since it is a prefix key
+	grantee, granterAddrEndIndex := sdk.ParseLengthPrefixedBytes(key, granterAddrLenEndIndex+1, int(granterAddrLen[0]))
+
+	granteeAddrLen, granteeAddrLenEndIndex := sdk.ParseLengthPrefixedBytes(key, granterAddrEndIndex+1, 1)
+	granter, _ = sdk.ParseLengthPrefixedBytes(key, granteeAddrLenEndIndex+1, int(granteeAddrLen[0]))
 
 	return granter, grantee
 }

x/feegrant/key_test.go

@@ -2,6 +2,7 @@ package feegrant_test
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 
@@ -23,3 +24,20 @@ func TestMarshalAndUnmarshalFeegrantKey(t *testing.T) {
 	require.Equal(t, granter, g1)
 	require.Equal(t, grantee, g2)
 }
+
+func TestMarshalAndUnmarshalFeegrantKeyQueueKey(t *testing.T) {
+	grantee, err := sdk.AccAddressFromBech32("cosmos1qk93t4j0yyzgqgt6k5qf8deh8fq6smpn3ntu3x")
+	require.NoError(t, err)
+	granter, err := sdk.AccAddressFromBech32("cosmos1p9qh4ldfd6n0qehujsal4k7g0e37kel90rc4ts")
+	require.NoError(t, err)
+
+	exp := time.Now()
+	expBytes := sdk.FormatTimeBytes(exp)
+
+	key := feegrant.FeeAllowancePrefixQueue(&exp, feegrant.FeeAllowanceKey(granter, grantee)[1:])
+	require.Len(t, key, len(grantee.Bytes())+len(granter.Bytes())+3+len(expBytes))
+
+	granter1, grantee1 := feegrant.ParseAddressesFromFeeAllowanceQueueKey(key)
+	require.Equal(t, granter, granter1)
+	require.Equal(t, grantee, grantee1)
+}