apps: udpecho_raw: add UDP echo server for raw API

Introduce a UDP echo that works on the lwIP raw API. Based on code
by Iwan Budi Kusnanto and Juri Haberland:

 - https://gist.github.com/iwanbk/1399729
 - https://lists.gnu.org/archive/html/lwip-users/2007-06/msg00078.html

Signed-off-by: Stephan Linz <linz@li-pro.net>

apps/udpecho_raw/udpecho_raw.c

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2016 Stephan Linz <linz@li-pro.net>, Li-Pro.Net
+ * All rights reserved.
+ *
+ * Based on examples provided by
+ * Iwan Budi Kusnanto <ibk@labhijau.net> (https://gist.github.com/iwanbk/1399729)
+ * Juri Haberland <juri@sapienti-sat.org> (https://lists.gnu.org/archive/html/lwip-users/2007-06/msg00078.html)
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of and a contribution to the lwIP TCP/IP stack.
+ *
+ * Credits go to Adam Dunkels (and the current maintainers) of this software.
+ *
+ * Stephan Linz rewrote this file to get a basic echo example.
+ */
+
+/**
+ * @file
+ * UDP echo server example using raw API.
+ *
+ * Echos all bytes sent by connecting client,
+ * and passively closes when client is done.
+ *
+ */
+
+
+#include "lwip/opt.h"
+#include "lwip/debug.h"
+#include "lwip/stats.h"
+#include "lwip/udp.h"
+#include "udpecho_raw.h"
+
+#if LWIP_UDP
+
+static struct udp_pcb *udpecho_raw_pcb;
+
+void udpecho_raw_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p,
+                      const ip_addr_t *addr, u16_t port);
+
+void
+udpecho_raw_init(void)
+{
+  udpecho_raw_pcb = udp_new();
+  if (udpecho_raw_pcb != NULL)
+  {
+    err_t err;
+
+    err = udp_bind(udpecho_raw_pcb, IP_ADDR_ANY, 7);
+    if (err == ERR_OK)
+    {
+      udp_recv(udpecho_raw_pcb, udpecho_raw_recv, NULL);
+    }
+    else
+    {
+      /* abort? output diagnostic? */
+    }
+  }
+  else
+  {
+    /* abort? output diagnostic? */
+  }
+}
+
+
+void
+udpecho_raw_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p,
+                 const ip_addr_t *addr, u16_t port)
+{
+  LWIP_UNUSED_ARG(arg);
+  if (p != NULL) {
+    /* send received packet back to sender */
+    udp_sendto(upcb, p, addr, port);
+    /* free the pbuf */
+    pbuf_free(p);
+  }
+}
+
+#endif /* LWIP_UDP */

apps/udpecho_raw/udpecho_raw.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2016 Stephan Linz <linz@li-pro.net>, Li-Pro.Net
+ * All rights reserved.
+ *
+ * Based on examples provided by
+ * Iwan Budi Kusnanto <ibk@labhijau.net> (https://gist.github.com/iwanbk/1399729)
+ * Juri Haberland <juri@sapienti-sat.org> (https://lists.gnu.org/archive/html/lwip-users/2007-06/msg00078.html)
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ *
+ */
+#ifndef LWIP_UDPECHO_RAW_H
+#define LWIP_UDPECHO_RAW_H
+
+void udpecho_raw_init(void);
+
+#endif /* LWIP_UDPECHO_RAW_H */

ports/Filelists.mk

@@ -34,6 +34,7 @@ CONTRIBAPPFILES=$(CONTRIBDIR)/apps/httpserver/httpserver-netconn.c \
 	$(CONTRIBDIR)/apps/udpecho/udpecho.c \
 	$(CONTRIBDIR)/apps/tcpecho/tcpecho.c \
 	$(CONTRIBDIR)/apps/shell/shell.c \
+	$(CONTRIBDIR)/apps/udpecho_raw/udpecho_raw.c \
 	$(CONTRIBDIR)/apps/tcpecho_raw/tcpecho_raw.c \
 	$(CONTRIBDIR)/apps/netio/netio.c \
 	$(CONTRIBDIR)/apps/ping/ping.c \