Try new IP checker

cadence/server/db_redis.go

@@ -5,6 +5,7 @@ package main
 
 import (
 	"context"
+	"net"
 	"net/http"
 	"time"
 
@@ -28,8 +29,12 @@ func redisInit() {
 
 func rateLimit(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		ip := r.RemoteAddr
-		_, err := dbr.RateLimit.Get(ctx, ip).Result()
+		ip, err := checkIP(r)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError) // 500 Internal Server Error
+			return
+		}
+		_, err = dbr.RateLimit.Get(ctx, ip).Result()
 		if err != nil {
 			if err == redis.Nil {
 				// redis.Nil means the IP is not in the database.
@@ -47,3 +52,16 @@ func rateLimit(next http.Handler) http.Handler {
 		}
 	})
 }
+
+func checkIP(r *http.Request) (ip string, err error) {
+	// We look at the remote address and check the IP.
+	// If for some reason no remote IP is there, we error to reject.
+	if r.RemoteAddr != "" {
+		ip, _, err := net.SplitHostPort(r.RemoteAddr)
+		if err != nil || ip == "" {
+			return "", err
+		}
+		return ip, nil
+	}
+	return "", err
+}