A significantly simpler API for sending UDP packets

core/net/simple-udp.c

@@ -0,0 +1,212 @@
+/**
+ * \addtogroup simple-udp
+ * @{
+ */
+
+
+/*
+ * Copyright (c) 2011, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * 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. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 Contiki operating system.
+ *
+ * \file
+ *         Header file for the simple-udp module.
+ * \author
+ *         Adam Dunkels <[email protected]>
+ *
+ */
+
+#include "simple-udp.h"
+#include "contiki-net.h"
+
+PROCESS(simple_udp_process, "Simple UDP process");
+static uint8_t started = 0;
+static uint8_t databuffer[UIP_BUFSIZE];
+
+#define UIP_IP_BUF   ((struct uip_udpip_hdr *)&uip_buf[UIP_LLH_LEN])
+
+/*---------------------------------------------------------------------------*/
+static void
+init_simple_udp(void)
+{
+  if(started == 0) {
+    process_start(&simple_udp_process, NULL);
+    started = 1;
+  }
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * \brief      Send a UDP packet
+ * \param c    A pointer to a struct simple_udp_connection
+ * \param data A pointer to the data to be sent
+ * \param datalen The length of the data
+ *
+ *             This function sends a UDP packet. The packet will be
+ *             sent to the IP address and with the UDP ports that were
+ *             specified when the connection wa registered with
+ *             simple_udp_register().
+ *
+ * \sa simple_udp_sendto()
+ */
+int
+simple_udp_send(struct simple_udp_connection *c,
+                const void *data, uint16_t datalen)
+{
+  if(c->udp_conn != NULL) {
+    uip_udp_packet_sendto(c->udp_conn, data, datalen,
+                          &c->remote_addr, UIP_HTONS(c->remote_port));
+  }
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * \brief      Send a UDP packet to a specified IP address
+ * \param c    A pointer to a struct simple_udp_connection
+ * \param data A pointer to the data to be sent
+ * \param datalen The length of the data
+ * \param to   The IP address of the receiver
+ *
+ *             This function sends a UDP packet to a specified IP
+ *             address. The packet will be sent with the UDP ports
+ *             that were specified when the connection wa registered
+ *             with simple_udp_register().
+ *
+ * \sa simple_udp_send()
+ */
+int
+simple_udp_sendto(struct simple_udp_connection *c,
+                  const void *data, uint16_t datalen,
+                  const uip_ipaddr_t *to)
+{
+  if(c->udp_conn != NULL) {
+    uip_udp_packet_sendto(c->udp_conn, data, datalen,
+                          to, UIP_HTONS(c->remote_port));
+  }
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * \brief      Register a UDP connection
+ * \param c    A pointer to a struct simple_udp_connection
+ * \param local_port The local UDP port in host byte order
+ * \param remote_addr The remote IP address
+ * \param remote_port The remote UDP port in host byte order
+ * \param receive_callback A pointer to a function to be called for incoming packets
+ * \retval 0   If no UDP connection could be allocated
+ * \retval 1   If the connection was successfully allocated
+ *
+ *             This function registers a UDP connection and attaches a
+ *             callback function to it. The callback function will be
+ *             called for incoming packets. The local UDP port can be
+ *             set to 0 to indicate that an ephemeral UDP port should
+ *             be allocated. The remote IP address can be NULL, to
+ *             indicate that packets from any IP address should be
+ *             accepted.
+ *
+ */
+int
+simple_udp_register(struct simple_udp_connection *c,
+                    uint16_t local_port,
+                    uip_ipaddr_t *remote_addr,
+                    uint16_t remote_port,
+                    simple_udp_callback receive_callback)
+{
+
+  init_simple_udp();
+
+  c->local_port = local_port;
+  c->remote_port = remote_port;
+  if(remote_addr != NULL) {
+    uip_ipaddr_copy(&c->remote_addr, remote_addr);
+  }
+  c->receive_callback = receive_callback;
+
+  PROCESS_CONTEXT_BEGIN(&simple_udp_process);
+  c->udp_conn = udp_new(remote_addr, UIP_HTONS(remote_port), c);
+  if(c->udp_conn != NULL) {
+    udp_bind(c->udp_conn, UIP_HTONS(local_port));
+  }
+  PROCESS_CONTEXT_END();
+
+  if(c->udp_conn == NULL) {
+    return 0;
+  }
+  return 1;
+}
+/*---------------------------------------------------------------------------*/
+PROCESS_THREAD(simple_udp_process, ev, data)
+{
+  struct simple_udp_connection *c;
+  PROCESS_BEGIN();
+
+  while(1) {
+    PROCESS_WAIT_EVENT();
+    if(ev == tcpip_event) {
+
+      /* An appstate pointer is passed to use from the IP stack
+         through the 'data' pointer. We registered this appstate when
+         we did the udp_new() call in simple_udp_register() as the
+         struct simple_udp_connection pointer. So we extract this
+         pointer and use it when calling the reception callback. */
+      c = (struct simple_udp_connection *)data;
+
+      /* Defensive coding: although the appstate *should* be non-null
+         here, we make sure to avoid the program crashing on us. */
+      if(c != NULL) {
+
+        /* If we were called because of incoming data, we should call
+           the reception callback. */
+        if(uip_newdata()) {
+          /* Copy the data from the uIP data buffer into our own
+             buffer to avoid the uIP buffer being messed with by the
+             callee. */
+          memcpy(databuffer, uip_appdata, uip_datalen());
+
+          /* Call the client process. We use the PROCESS_CONTEXT
+             mechanism to temporarily switch process context to the
+             client process. */
+          if(c->receive_callback != NULL) {
+            PROCESS_CONTEXT_BEGIN(c->client_process);
+            c->receive_callback(c,
+                                &(UIP_IP_BUF->srcipaddr),
+                                UIP_HTONS(UIP_IP_BUF->srcport),
+                                &(UIP_IP_BUF->destipaddr),
+                                UIP_HTONS(UIP_IP_BUF->destport),
+                                databuffer, uip_datalen());
+            PROCESS_CONTEXT_END();
+          }
+        }
+      }
+    }
+
+  }
+
+  PROCESS_END();
+}
+/*---------------------------------------------------------------------------*/
+/** @} */

core/net/simple-udp.h

@@ -0,0 +1,94 @@
+/**
+ * \addtogroup uip
+ * @{
+ */
+
+
+/**
+ * \defgroup simple-udp
+ *
+ * The default Contiki UDP API is difficult to use. The simple-udp
+ * module provides a significantly simpler API.
+ *
+ * @{
+ */
+
+/*
+ * Copyright (c) 2011, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * 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. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 Contiki operating system.
+ *
+ * \file
+ *         Header file for the simple-udp module.
+ * \author
+ *         Adam Dunkels <[email protected]>
+ *
+ */
+
+#ifndef SIMPLE_UDP_H
+#define SIMPLE_UDP_H
+
+#include "net/uip.h"
+
+struct simple_udp_connection;
+
+typedef void (* simple_udp_callback)(struct simple_udp_connection *c,
+                                     const uip_ipaddr_t *source_addr,
+                                     uint16_t source_port,
+                                     const uip_ipaddr_t *dest_addr,
+                                     uint16_t dest_port,
+                                     const uint8_t *data, uint16_t datalen);
+
+struct simple_udp_connection {
+  struct simple_udp_connection *next;
+  uip_ipaddr_t remote_addr;
+  uint16_t remote_port, local_port;
+  simple_udp_callback receive_callback;
+  struct uip_udp_conn *udp_conn;
+  struct process *client_process;
+};
+
+int simple_udp_register(struct simple_udp_connection *c,
+                        uint16_t local_port,
+                        uip_ipaddr_t *remote_addr,
+                        uint16_t remote_port,
+                        simple_udp_callback receive_callback);
+
+int simple_udp_send(struct simple_udp_connection *c,
+                    const void *data, uint16_t datalen);
+
+int simple_udp_sendto(struct simple_udp_connection *c,
+                      const void *data, uint16_t datalen,
+                      const uip_ipaddr_t *to);
+
+void simple_udp_init(void);
+
+#endif /* SIMPLE_UDP_H */
+
+/** @} */
+/** @} */