Add conditional check for split (#55)

Add conditional checks for splicing string, so that accessing them out of bounds due to edge case doesn't lead to crash

Author: zbud-msft

gnmi_server/server_test.go

@@ -1099,6 +1099,12 @@ func runGnmiTestGet(t *testing.T, namespace string) {
 			valTest:     true,
 			wantRetCode: codes.OK,
 			wantRespVal: []byte(`{"test_field": "test_value"}`),
+		}, {
+			desc:       "Invalid DBKey of length 1",
+			pathTarget: stateDBPath,
+			textPbPath: ``,
+			valTest:     true,
+			wantRetCode: codes.NotFound,
 		},
 
 		// Happy path

sonic_data_client/db_client.go

@@ -547,7 +547,9 @@ func populateDbtablePath(prefix, path *gnmipb.Path, pathG2S *map[*gnmipb.Path][]
 	}
 	tblPath.dbNamespace = dbNamespace
 	tblPath.dbName = targetDbName
-	tblPath.tableName = stringSlice[1]
+	if len(stringSlice) > 1 {
+		tblPath.tableName = stringSlice[1]
+	}
 	tblPath.delimitor = separator
 
 	var mappedKey string
@@ -717,6 +719,9 @@ func tableData2Msi(tblPath *tablePath, useKey bool, op *string, msi *map[string]
 			var key string
 			// Split dbkey string into two parts and second part is key in table
 			keys := strings.SplitN(dbkey, tblPath.delimitor, 2)
+			if len(keys) < 2 {
+				return fmt.Errorf("dbkey: %s, failed split from delimitor %v", dbkey, tblPath.delimitor)
+			}
 			key = keys[1]
 			err = makeJSON_redis(msi, &key, op, fv)
 		}