Use realIP

Code was copied from https://github.com/go-chi/chi/blob/master/middleware/realip.go

cmd/web/handlers.go

@@ -277,7 +277,7 @@ func (app *application) createVotesHandleKnownVotersElection(w http.ResponseWrit
 }
 
 func (app *application) createVotesHandleUnknownVotersElection(w http.ResponseWriter, r *http.Request, election *models.Election) (string, error) {
-	voterIdentity := r.RemoteAddr
+	voterIdentity := realIP(r)
 
 	voterExists, err := app.voters.Exists(voterIdentity, election.ID)
 	if err != nil {

cmd/web/helpers.go

@@ -5,7 +5,9 @@ import (
 	"code.dlmw.ch/dlmw/qv/internal/validator"
 	"encoding/json"
 	"io"
+	"net"
 	"net/http"
+	"strings"
 )
 
 func (app *application) serverError(w http.ResponseWriter, r *http.Request, err error) {
@@ -67,3 +69,23 @@ func (app *application) unmarshalRequest(r *http.Request, dst any) error {
 
 	return nil
 }
+
+func realIP(r *http.Request) string {
+	var ip string
+
+	if tcip := r.Header.Get(http.CanonicalHeaderKey("True-Client-IP")); tcip != "" {
+		ip = tcip
+	} else if xrip := r.Header.Get(http.CanonicalHeaderKey("X-Real-IP")); xrip != "" {
+		ip = xrip
+	} else if xff := r.Header.Get(http.CanonicalHeaderKey("X-Forwarded-For")); xff != "" {
+		i := strings.Index(xff, ",")
+		if i == -1 {
+			i = len(xff)
+		}
+		ip = xff[:i]
+	}
+	if ip == "" || net.ParseIP(ip) == nil {
+		return ""
+	}
+	return ip
+}

cmd/web/middleware.go

@@ -20,7 +20,7 @@ func (app *application) recoverPanic(next http.Handler) http.Handler {
 func (app *application) logRequest(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var (
-			ip     = r.RemoteAddr
+			ip     = realIP(r)
 			proto  = r.Proto
 			method = r.Method
 			uri    = r.URL.RequestURI()