fix(claimsmanager): properly check index to avoid invalid data in Use…

…rClaims,UserLastEpochClaims

This change ensures that we correctly check for missing values in
keeper.(UserClaims, UserLastEpochClaims) because otherwise due
to the blind assumption that the key would always be well formed,
+1 and +1+1 were being added respectively which would mean that
the condition "idx >= 0" would ALWAYS pass and send over the wrong
data if the key happened to contain the address bytes.

Fixes quicksilver-zone#1217
Supersedes PR quicksilver-zone#1223

x/claimsmanager/keeper/grpc_query.go

@@ -68,10 +68,17 @@ func (k Keeper) UserClaims(c context.Context, q *types.QueryClaimsRequest) (*typ
 	addrBytes := []byte(q.Address)
 
 	k.IterateAllClaims(ctx, func(_ int64, key []byte, claim types.Claim) (stop bool) {
+		// The assumption is that IterateAllClaims returns non-empty keys.
 		// check for the presence of the addr bytes in the key.
-		// first prefix byte is 0x00; so cater for that! Then + 1 to skip the separator.
-		idx := bytes.Index(key[1:], []byte{0x00}) + 1 + 1
-		if idx >= 0 && bytes.Equal(key[idx:idx+len(addrBytes)], addrBytes) {
+		// first prefix byte is 0x00; so cater for that!
+		idx := bytes.Index(key[1:], []byte{0x00})
+		if idx < 0 {
+			return false
+		}
+
+		idx += 1 + 1 // add + 1 to skip the separator.
+
+		if bytes.Equal(key[idx:idx+len(addrBytes)], addrBytes) {
 			out = append(out, claim)
 		}
 		return false
@@ -86,9 +93,15 @@ func (k Keeper) UserLastEpochClaims(c context.Context, q *types.QueryClaimsReque
 	addrBytes := []byte(q.Address)
 	k.IterateAllLastEpochClaims(ctx, func(_ int64, key []byte, claim types.Claim) (stop bool) {
 		// check for the presence of the addr bytes in the key.
-		// First byte is 0x01 here, so no need to consider it; + 1 to skip the separator.
-		idx := bytes.Index(key, []byte{0x00}) + 1
-		if idx >= 0 && bytes.Equal(key[idx:idx+len(addrBytes)], addrBytes) {
+		idx := bytes.Index(key, []byte{0x00})
+		if idx < 0 {
+			return false
+		}
+
+		// First byte was 0x01, so no need to consider it; + 1 to skip the separator.
+		idx += 1
+
+		if bytes.Equal(key[idx:idx+len(addrBytes)], addrBytes) {
 			out = append(out, claim)
 		}
 		return false