From 75d0db5f74bb50c1e8d3b51256a9a56be0d3278d Mon Sep 17 00:00:00 2001
From: Daniel Wagner <wagi@monom.org>
Date: Sun, 16 Jan 2022 15:04:23 +0100
Subject: [PATCH 2/4] dnsproxy: Update TCP length header

Patch provided by Matthias Gerstner.
---
 src/dnsproxy.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/dnsproxy.c b/src/dnsproxy.c
index cd570d68c8b3..c027bcb972c4 100644
--- a/src/dnsproxy.c
+++ b/src/dnsproxy.c
@@ -2188,6 +2188,9 @@ static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol,
 			err = sendto(sk, req->resp, req->resplen, 0,
 				&req->sa, req->sa_len);
 	} else {
+		uint16_t tcp_len = htons(req->resplen - 2);
+		/* correct TCP message length */
+		memcpy(req->resp, &tcp_len, sizeof(tcp_len));
 		sk = req->client_sk;
 		err = send(sk, req->resp, req->resplen, MSG_NOSIGNAL);
 	}
-- 
2.34.1