added pagination to the lookup query

backend/api.go

@@ -188,14 +188,32 @@ func apiLookupPrefixGlobal(req *http.Request, params httprouter.Params) (api.Res
 		return nil, err
 	}
 
+	// Get pagination params
+	limit, offset, err := validatePaginationParams(req, 100, 0)
+	if err != nil {
+		return nil, err
+	}
+
 	// Make response
 	t0 := time.Now()
 	routes := AliceRoutesStore.Lookup(prefix)
 
+	// Paginate result
+	totalRoutes := len(routes)
+	cap := offset + limit
+	if cap > totalRoutes {
+		cap = totalRoutes
+	}
+
 	queryDuration := time.Since(t0)
 	response := api.LookupResponseGlobal{
-		Routes: routes,
-		Time:   float64(queryDuration) / 1000.0 / 1000.0, // nano -> micro -> milli
+		Routes: routes[offset:cap],
+
+		TotalRoutes: totalRoutes,
+		Limit:       limit,
+		Offset:      offset,
+
+		Time: float64(queryDuration) / 1000.0 / 1000.0, // nano -> micro -> milli
 	}
 	return response, nil
 }

backend/api_validators.go

@@ -67,5 +67,24 @@ func validatePrefixQuery(value string) (string, error) {
 // Get pagination parameters: limit and offset
 // Refer to defaults if none are given.
 func validatePaginationParams(req *http.Request, limit, offset int) (int, int, error) {
+	query := req.URL.Query()
+	queryLimit, ok := query["limit"]
+	if ok {
+		limit, _ = strconv.Atoi(queryLimit[0])
+	}
+
+	queryOffset, ok := query["offset"]
+	if ok {
+		offset, _ = strconv.Atoi(queryOffset[0])
+	}
+
+	// Cap limit to [1, 1000]
+	if limit < 1 {
+		limit = 1
+	}
+	if limit > 1000 {
+		limit = 1000
+	}
+
 	return limit, offset, nil
 }