feat: Enhance host extraction from headers (#2292)

- Refactor SUBController subs and subJsons methods to extract host from X-Forwarded-Host header, falling back to X-Real-IP header and then to the request host if unavailable.
- Update html function to extract host from X-Forwarded-Host header, falling back to X-Real-IP header and then to the request host if unavailable.
- Update DomainValidatorMiddleware to first attempt to extract host from X-Forwarded-Host header, falling back to X-Real-IP header and then to the request host.

Fixes: #2284

Signed-off-by: Ahmad Thoriq Najahi <najahi@zephyrus.id>

sub/subController.go

@@ -54,7 +54,18 @@ func (a *SUBController) initRouter(g *gin.RouterGroup) {
 
 func (a *SUBController) subs(c *gin.Context) {
 	subId := c.Param("subid")
-	host, _, _ := net.SplitHostPort(c.Request.Host)
+	host := c.GetHeader("X-Forwarded-Host")
+	if host == "" {
+		host = c.GetHeader("X-Real-IP")
+	}
+	if host == "" {
+		var err error
+		host, _, err = net.SplitHostPort(c.Request.Host)
+		if err != nil {
+			host = c.Request.Host
+		}
+	}
+	host = host
 	subs, header, err := a.subService.GetSubs(subId, host)
 	if err != nil || len(subs) == 0 {
 		c.String(400, "Error!")
@@ -79,7 +90,18 @@ func (a *SUBController) subs(c *gin.Context) {
 
 func (a *SUBController) subJsons(c *gin.Context) {
 	subId := c.Param("subid")
-	host, _, _ := net.SplitHostPort(c.Request.Host)
+	host := c.GetHeader("X-Forwarded-Host")
+	if host == "" {
+		host = c.GetHeader("X-Real-IP")
+	}
+	if host == "" {
+		var err error
+		host, _, err = net.SplitHostPort(c.Request.Host)
+		if err != nil {
+			host = c.Request.Host
+		}
+	}
+	host = host
 	jsonSub, header, err := a.subJsonService.GetJson(subId, host)
 	if err != nil || len(jsonSub) == 0 {
 		c.String(400, "Error!")