From 980ef8f9dc49a61879be6d218700248f96391561 Mon Sep 17 00:00:00 2001
From: Emil Ljungdahl <111423223+pando-emil@users.noreply.github.com>
Date: Mon, 9 Jan 2023 05:42:16 +0100
Subject: [PATCH] Implement non-blocking recvfrom on Windows (#1124)

This pull request is a split of PR #1061

As @KangLin pointed out in the original PR those sockets should ideally
be permanently non-blocking for performance reasons, but they are NOT at
the moment.
Someone with more knowledge about the code in dtls_listener.c should
probably have a look if it would be feasible to change the sockets to
non-blocking already at creation, similar to what is done in
udpserver.c...
---
 src/apps/relay/dtls_listener.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/apps/relay/dtls_listener.c b/src/apps/relay/dtls_listener.c
index 21bc81a..5a9005b 100644
--- a/src/apps/relay/dtls_listener.c
+++ b/src/apps/relay/dtls_listener.c
@@ -621,8 +621,9 @@ start_udp_cycle:
 
   ssize_t bsize = 0;
 #if defined(WINDOWS)
-  // TODO: implement it!!!
   int flags = 0;
+  u_long iMode = 1;
+  ioctlsocket(fd, FIONBIO, &iMode);
 #else
   int flags = MSG_DONTWAIT;
 #endif
@@ -633,6 +634,11 @@ start_udp_cycle:
   int conn_reset = is_connreset();
   int to_block = would_block();
 
+#if defined(WINDOWS)
+  iMode = 0;
+  ioctlsocket(fd, FIONBIO, &iMode);
+#endif
+
   if (bsize < 0) {
 
     if (to_block) {
@@ -645,8 +651,9 @@ start_udp_cycle:
 #if defined(MSG_ERRQUEUE)
 
 #if defined(WINDOWS)
-    // TODO: implement it!!!
     int eflags = MSG_ERRQUEUE;
+    iMode = 1;
+    ioctlsocket(fd, FIONBIO, &iMode);
 #else
     // Linux
     int eflags = MSG_ERRQUEUE | MSG_DONTWAIT;
@@ -668,6 +675,11 @@ start_udp_cycle:
     conn_reset = is_connreset();
     to_block = would_block();
 
+#if defined(WINDOWS)
+    iMode = 0;
+    ioctlsocket(fd, FIONBIO, &iMode);
+#endif
+
 #endif
 
     if (conn_reset) {