server: Fail early for non-existent service name

main.go

@@ -10,5 +10,9 @@ func main() {
 		panic(err)
 	}
 	go checkLoop(cfg.Targets)
-	server.StartServer(cfg.Port)
+	validServices := make([]string, 0, len(cfg.Targets))
+	for _, v := range cfg.Targets {
+		validServices = append(validServices, v.ServiceName)
+	}
+	server.StartServer(cfg.Port, validServices)
 }

server/api.go

@@ -38,6 +38,10 @@ func dayHistory(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 	service_name := keys[0]
+	if !validTarget[service_name] {
+		http.Error(w, "Invalid `service_name` requested", http.StatusBadRequest)
+		return
+	}
 	keys, ok = req.URL.Query()["interval"]
 	var interval = 5
 	if len(keys) >= 2 {
@@ -89,6 +93,10 @@ func history(w http.ResponseWriter, req *http.Request, dayCount int) {
 		http.Error(w, "Only one `service_name` allowed", http.StatusBadRequest)
 		return
 	}
+	if !validTarget[keys[0]] {
+		http.Error(w, "Invalid `service_name` requested", http.StatusBadRequest)
+		return
+	}
 	entries := getHistoryDay(keys[0], dayCount)
 	writeJSON(w, entries)
 }

server/data.go

@@ -21,10 +21,12 @@ func getStatus() map[string]db.PingEntry {
 func getHistoryDay(serviceName string, dayCount int) []stat {
 	currentDay := today()
 	result := make([]stat, 0)
-	for i := -dayCount + 1; i <= 0; i++ {
+	for i := 0; i >= -dayCount+1; i-- {
 		dayData := getDay(serviceName, currentDay.AddDate(0, 0, i))
 		if dayData.SampleCount > 0 {
 			result = append(result, dayData)
+		} else {
+			break
 		}
 	}
 	return result

server/server.go

@@ -6,6 +6,10 @@ import (
 	"strconv"
 )
 
+var (
+	validTarget = make(map[string]bool)
+)
+
 func apiEndpoints() {
 	http.HandleFunc("/api/latest", allStatus)
 	http.HandleFunc("/api/history/day", dayHistory)
@@ -14,7 +18,10 @@ func apiEndpoints() {
 	http.HandleFunc("/api/history/year", yearHistory)
 }
 
-func StartServer(port int) {
+func StartServer(port int, validTargets []string) {
+	for _, v := range validTargets {
+		validTarget[v] = true
+	}
 	apiEndpoints()
 	err := http.ListenAndServe(":"+strconv.Itoa(port), nil)
 	if err != nil {