Add header X-Forwarded-Port with placeholder {server_port} to preset proxy preset transparent

caddyhttp/proxy/upstream.go

@@ -448,6 +448,7 @@ func parseBlock(c *caddyfile.Dispenser, u *staticUpstream, hasSrv bool) error {
 		u.upstreamHeaders.Add("Host", "{host}")
 		u.upstreamHeaders.Add("X-Real-IP", "{remote}")
 		u.upstreamHeaders.Add("X-Forwarded-Proto", "{scheme}")
+		u.upstreamHeaders.Add("X-Forwarded-Port", "{server_port}")
 	case "websocket":
 		u.upstreamHeaders.Add("Connection", "{>Connection}")
 		u.upstreamHeaders.Add("Upgrade", "{>Upgrade}")

caddyhttp/proxy/upstream_test.go

@@ -321,6 +321,10 @@ func TestParseBlockTransparent(t *testing.T) {
 			if _, ok := headers["X-Forwarded-For"]; ok {
 				t.Errorf("Test %d: Found unexpected X-Forwarded-For header", i+1)
 			}
+
+			if _, ok := headers["X-Forwarded-Port"]; !ok {
+				t.Errorf("Test %d: Could not find the X-Forwarded-Port header", i+1)
+			}
 		}
 	}
 }