From 58d1412f0df08a90cc4df9bb3e5fb8a550daf63e Mon Sep 17 00:00:00 2001
From: Vladimir Homutov <vl@nginx.com>
Date: Mon, 8 Jun 2020 11:40:34 +0300
Subject: Stream: fixed processing of zero length UDP packets (ticket #1982).

---
 src/os/unix/ngx_udp_sendmsg_chain.c | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'src/os/unix/ngx_udp_sendmsg_chain.c')

diff --git a/src/os/unix/ngx_udp_sendmsg_chain.c b/src/os/unix/ngx_udp_sendmsg_chain.c
index 5399c7916..3d1d6dde4 100644
--- a/src/os/unix/ngx_udp_sendmsg_chain.c
+++ b/src/os/unix/ngx_udp_sendmsg_chain.c
@@ -189,6 +189,13 @@ ngx_udp_output_chain_to_iovec(ngx_iovec_t *vec, ngx_chain_t *in, ngx_log_t *log)
         return cl;
     }
 
+    /* zero-sized datagram; pretend to have at least 1 iov */
+    if (n == 0) {
+        iov = &vec->iovs[n++];
+        iov->iov_base = NULL;
+        iov->iov_len = 0;
+    }
+
     vec->count = n;
     vec->size = total;
 
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