From 1d94442546abc0eb2c051e48e64d0e2b93e3f0cd Mon Sep 17 00:00:00 2001
From: Max Lv <max.c.lv@gmail.com>
Date: Fri, 12 Jan 2018 10:15:24 +0800
Subject: [PATCH] Refine udp header checking

---
 src/udprelay.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/udprelay.c b/src/udprelay.c
index 805be332..09c27384 100644
--- a/src/udprelay.c
+++ b/src/udprelay.c
@@ -732,6 +732,12 @@ remote_recv_cb(EV_P_ ev_io *w, int revents)
         goto CLEAN_UP;
     }
 
+    if (remote_ctx->addr_header_len != len
+        || memcmp(buf->data, remote_ctx->addr_header, len) != 0) {
+        LOGI("[udp] mismatched header");
+        goto CLEAN_UP;
+    }
+
     // server may return using a different address type other than the type we
     // have used during sending
 #if defined(MODULE_TUNNEL) || defined(MODULE_REDIR)