fix(filters): fix context loss in httproutefilter processing

Signed-off-by: a.krudu <a.krudu@tbank.ru>

Author: a.krudu

internal/gatewayapi/filters.go

@@ -212,20 +212,28 @@ func (t *Translator) processURLRewriteFilter(
 		return
 	}
 
-	newURLRewrite := &ir.URLRewrite{}
-
 	if rewrite.Hostname != nil {
 		if err := t.validateHostname(string(*rewrite.Hostname)); err != nil {
 			updateRouteStatusForFilter(filterContext, err.Error())
 			return
 		}
 		redirectHost := string(*rewrite.Hostname)
-		newURLRewrite.Host = &ir.HTTPHostModifier{
-			Name: &redirectHost,
+		if filterContext.URLRewrite == nil {
+			filterContext.URLRewrite = &ir.URLRewrite{
+				Host: &ir.HTTPHostModifier{
+					Name: &redirectHost,
+				},
+			}
+		} else if filterContext.URLRewrite.Host == nil {
+			filterContext.URLRewrite.Host = &ir.HTTPHostModifier{
+				Name: &redirectHost,
+			}
 		}
 	}
 
 	if rewrite.Path != nil {
+		var pathModifier *ir.ExtendedHTTPPathModifier
+
 		switch rewrite.Path.Type {
 		case gwapiv1.FullPathHTTPPathModifier:
 			if rewrite.Path.ReplacePrefixMatch != nil {
@@ -241,7 +249,7 @@ func (t *Translator) processURLRewriteFilter(
 				return
 			}
 			if rewrite.Path.ReplaceFullPath != nil {
-				newURLRewrite.Path = &ir.ExtendedHTTPPathModifier{
+				pathModifier = &ir.ExtendedHTTPPathModifier{
 					HTTPPathModifier: ir.HTTPPathModifier{
 						FullReplace: rewrite.Path.ReplaceFullPath,
 					},
@@ -261,7 +269,7 @@ func (t *Translator) processURLRewriteFilter(
 				return
 			}
 			if rewrite.Path.ReplacePrefixMatch != nil {
-				newURLRewrite.Path = &ir.ExtendedHTTPPathModifier{
+				pathModifier = &ir.ExtendedHTTPPathModifier{
 					HTTPPathModifier: ir.HTTPPathModifier{
 						PrefixMatchReplace: rewrite.Path.ReplacePrefixMatch,
 					},
@@ -275,9 +283,14 @@ func (t *Translator) processURLRewriteFilter(
 					rewrite.Path.Type))
 			return
 		}
+		if filterContext.URLRewrite == nil {
+			filterContext.URLRewrite = &ir.URLRewrite{
+				Path: pathModifier,
+			}
+		} else if filterContext.URLRewrite.Path == nil {
+			filterContext.URLRewrite.Path = pathModifier
+		}
 	}
-
-	filterContext.URLRewrite = newURLRewrite
 }
 
 func (t *Translator) processRedirectFilter(

internal/gatewayapi/testdata/httproute-with-urlrewrite-filter-regex-match-replace-http.out.yaml

@@ -370,6 +370,12 @@ xdsIR:
         urlRewrite:
           host:
             name: rewrite.com
+          path:
+            fullReplace: null
+            prefixMatchReplace: null
+            regexMatchReplace:
+              pattern: .*
+              substitution: foo
       - destination:
           metadata:
             kind: HTTPRoute

internal/gatewayapi/testdata/httproute-with-urlrewrite-hostname-filter.out.yaml

@@ -333,6 +333,8 @@ xdsIR:
           name: ""
           prefix: /header-host-and-path
         urlRewrite:
+          host:
+            header: my-host
           path:
             fullReplace: null
             prefixMatchReplace: /rewrite