From fa3ad468976c2c393355e0957a049ef686ed14fe Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Mon, 22 Jan 2018 18:46:58 -0600
Subject: [PATCH] net/udp:  In sendto(), return EHOSTUNREACH if if the network
 is down.

---
 net/udp/udp_psock_sendto_buffered.c   | 8 ++++++++
 net/udp/udp_psock_sendto_unbuffered.c | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/net/udp/udp_psock_sendto_buffered.c b/net/udp/udp_psock_sendto_buffered.c
index 3f5e5305b4..b9a8a89189 100644
--- a/net/udp/udp_psock_sendto_buffered.c
+++ b/net/udp/udp_psock_sendto_buffered.c
@@ -384,6 +384,14 @@ static int sendto_next_transfer(FAR struct socket *psock,
      return -ENETUNREACH;
    }
 
+  /* Make sure that the device is in the UP state */
+
+  if ((dev->d_flags & IFF_UP) == 0)
+    {
+      nwarn("WARNING: device is DOWN\n");
+      return -EHOSTUNREACH;
+    }
+
   /* If this is not the same device that we used in the last call to
    * udp_callback_alloc(), then we need to release and reallocate the old
    * callback instance.
diff --git a/net/udp/udp_psock_sendto_unbuffered.c b/net/udp/udp_psock_sendto_unbuffered.c
index 809ee2ce9e..7024d12baf 100644
--- a/net/udp/udp_psock_sendto_unbuffered.c
+++ b/net/udp/udp_psock_sendto_unbuffered.c
@@ -424,6 +424,15 @@ ssize_t psock_udp_sendto(FAR struct socket *psock, FAR const void *buf,
       goto errout_with_lock;
    }
 
+  /* Make sure that the device is in the UP state */
+
+  if ((dev->d_flags & IFF_UP) == 0)
+    {
+      nwarn("WARNING: device is DOWN\n");
+      ret = -EHOSTUNREACH;
+      goto errout_with_lock;
+    }
+
   /* Set up the callback in the connection */
 
   state.st_cb = udp_callback_alloc(dev, conn);