feat: add option to log the n most active IPs each hour (#496)

Reviewed-on: https://codeberg.org/Codeberg/pages-server/pulls/496
Co-authored-by: crapStone <me@crapstone.dev>
Co-committed-by: crapStone <me@crapstone.dev>

server/handler/handler.go

@@ -1,8 +1,10 @@
 package handler
 
 import (
+	"net"
 	"net/http"
 	"strings"
+	"sync"
 
 	"github.com/rs/zerolog/log"
 
@@ -24,10 +26,28 @@ func Handler(
 	cfg config.ServerConfig,
 	giteaClient *gitea.Client,
 	canonicalDomainCache, redirectsCache cache.ICache,
+	mostActiveIpMap *sync.Map,
 ) http.HandlerFunc {
 	return func(w http.ResponseWriter, req *http.Request) {
 		ctx := context.New(w, req)
 		log := log.With().Str("ReqId", ctx.ReqId).Strs("Handler", []string{req.Host, req.RequestURI}).Logger()
+
+		if cfg.LogMostActiveIps {
+			ip, _, err := net.SplitHostPort(req.RemoteAddr)
+			if err != nil {
+				log.Warn().Err(err).Msg("Failed to get IP address. Using complete remoteAddr string")
+
+				ip = req.RemoteAddr
+			}
+
+			success := false
+			for !success {
+				value, _ := mostActiveIpMap.LoadOrStore(ip, uint(0))
+				count := value.(uint)
+				success = mostActiveIpMap.CompareAndSwap(ip, count, count+1)
+			}
+		}
+
 		log.Debug().Msg("\n----------------------------------------------------------")
 
 		ctx.RespWriter.Header().Set("Server", "pages-server")