er-coap: add client-side support for CoAP Observe

Client-side support for CoAP observe is not compiled by default. To enable it, the COAP_OBSERVE_CLIENT macro must be defined equal to 1.

apps/er-coap/Makefile.er-coap

@@ -1,4 +1,6 @@
-er-coap_src = er-coap.c er-coap-engine.c er-coap-transactions.c er-coap-observe.c er-coap-separate.c er-coap-res-well-known-core.c er-coap-block1.c
+er-coap_src = er-coap.c er-coap-engine.c er-coap-transactions.c      \
+  er-coap-observe.c er-coap-separate.c er-coap-res-well-known-core.c \
+  er-coap-block1.c er-coap-observe-client.c
 
 # Erbium will implement the REST Engine
 CFLAGS += -DREST=coap_rest_implementation

apps/er-coap/er-coap-engine.c

@@ -253,6 +253,16 @@ coap_receive(void)
         }
         /* if(ACKed transaction) */
         transaction = NULL;
+
+#if COAP_OBSERVE_CLIENT
+	/* if observe notification */
+        if((message->type == COAP_TYPE_CON || message->type == COAP_TYPE_NON)
+              && IS_OPTION(message, COAP_OPTION_OBSERVE)) {
+          PRINTF("Observe [%u]\n", message->observe);
+          coap_handle_notification(&UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport,
+              message);
+        }
+#endif /* COAP_OBSERVE_CLIENT */
       } /* request or response */
     } /* parsed correctly */
 

apps/er-coap/er-coap-engine.h

@@ -44,6 +44,7 @@
 #include "er-coap-transactions.h"
 #include "er-coap-observe.h"
 #include "er-coap-separate.h"
+#include "er-coap-observe-client.h"
 
 #define SERVER_LISTEN_PORT      UIP_HTONS(COAP_SERVER_PORT)
 

apps/er-coap/er-coap-observe-client.c

@@ -0,0 +1,342 @@
+/*
+ * Copyright (c) 2014, Daniele Alessandrelli.
+ * 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
+ *        Extension to Erbium for enabling CoAP observe clients
+ * \author
+ *        Daniele Alessandrelli <daniele.alessandrelli@gmail.com>
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "er-coap.h"
+#include "er-coap-observe-client.h"
+
+/* Compile this code only if client-side support for CoAP Observe is required */
+#if COAP_OBSERVE_CLIENT
+
+#define DEBUG 1
+#if DEBUG
+#define PRINTF(...) printf(__VA_ARGS__)
+#define PRINT6ADDR(addr) PRINTF("[%02x%02x:%02x%02x:%02x%02x:%02x%02x:" \
+                                "%02x%02x:%02x%02x:%02x%02x:%02x%02x]", \
+                                ((uint8_t *)addr)[0], ((uint8_t *)addr)[1], \
+                                ((uint8_t *)addr)[2], ((uint8_t *)addr)[3], \
+                                ((uint8_t *)addr)[4], ((uint8_t *)addr)[5], \
+                                ((uint8_t *)addr)[6], ((uint8_t *)addr)[7], \
+                                ((uint8_t *)addr)[8], ((uint8_t *)addr)[9], \
+                                ((uint8_t *)addr)[10], ((uint8_t *)addr)[11], \
+                                ((uint8_t *)addr)[12], ((uint8_t *)addr)[13], \
+                                ((uint8_t *)addr)[14], ((uint8_t *)addr)[15])
+#define PRINTLLADDR(lladdr) PRINTF("[%02x:%02x:%02x:%02x:%02x:%02x]", \
+                                   (lladdr)->addr[0], (lladdr)->addr[1], \
+                                   (lladdr)->addr[2], (lladdr)->addr[3], \
+                                   (lladdr)->addr[4], (lladdr)->addr[5])
+#else
+#define PRINTF(...)
+#define PRINT6ADDR(addr)
+#define PRINTLLADDR(addr)
+#endif
+
+MEMB(obs_subjects_memb, coap_observee_t, COAP_MAX_OBSERVEES);
+LIST(obs_subjects_list);
+
+/*----------------------------------------------------------------------------*/
+static size_t
+get_token(void *packet, const uint8_t **token)
+{
+  coap_packet_t *const coap_pkt = (coap_packet_t *)packet;
+
+  *token = coap_pkt->token;
+
+  return coap_pkt->token_len;
+}
+/*----------------------------------------------------------------------------*/
+static int
+set_token(void *packet, const uint8_t *token, size_t token_len)
+{
+  coap_packet_t *const coap_pkt = (coap_packet_t *)packet;
+
+  coap_pkt->token_len = MIN(COAP_TOKEN_LEN, token_len);
+  memcpy(coap_pkt->token, token, coap_pkt->token_len);
+
+  return coap_pkt->token_len;
+}
+/*----------------------------------------------------------------------------*/
+coap_observee_t *
+coap_obs_add_observee(uip_ipaddr_t *addr, uint16_t port,
+                      const uint8_t *token, size_t token_len, const char *url,
+                      notification_callback_t notification_callback,
+                      void *data)
+{
+  coap_observee_t *o;
+
+  /* Remove existing observe relationship, if any. */
+  coap_obs_remove_observee_by_url(addr, port, url);
+  o = memb_alloc(&obs_subjects_memb);
+  if(o) {
+    o->url = url;
+    uip_ipaddr_copy(&o->addr, addr);
+    o->port = port;
+    o->token_len = token_len;
+    memcpy(o->token, token, token_len);
+    /* o->last_mid = 0; */
+    o->notification_callback = notification_callback;
+    o->data = data;
+    /* stimer_set(&o->refresh_timer, COAP_OBSERVING_REFRESH_INTERVAL); */
+    PRINTF("Adding obs_subject for /%s [0x%02X%02X]\n", o->url, o->token[0],
+           o->token[1]);
+    list_add(obs_subjects_list, o);
+  }
+
+  return o;
+}
+/*----------------------------------------------------------------------------*/
+void
+coap_obs_remove_observee(coap_observee_t *o)
+{
+  PRINTF("Removing obs_subject for /%s [0x%02X%02X]\n", o->url, o->token[0],
+         o->token[1]);
+  memb_free(&obs_subjects_memb, o);
+  list_remove(obs_subjects_list, o);
+}
+/*----------------------------------------------------------------------------*/
+coap_observee_t *
+coap_get_obs_subject_by_token(const uint8_t *token, size_t token_len)
+{
+  coap_observee_t *obs = NULL;
+
+  for(obs = (coap_observee_t *)list_head(obs_subjects_list); obs;
+      obs = obs->next) {
+    PRINTF("Looking for token 0x%02X%02X\n", token[0], token[1]);
+    if(obs->token_len == token_len
+       && memcmp(obs->token, token, token_len) == 0) {
+      return obs;
+    }
+  }
+
+  return NULL;
+}
+/*----------------------------------------------------------------------------*/
+int
+coap_obs_remove_observee_by_token(uip_ipaddr_t *addr, uint16_t port,
+                                  uint8_t *token, size_t token_len)
+{
+  int removed = 0;
+  coap_observee_t *obs = NULL;
+
+  for(obs = (coap_observee_t *)list_head(obs_subjects_list); obs;
+      obs = obs->next) {
+    PRINTF("Remove check Token 0x%02X%02X\n", token[0], token[1]);
+    if(uip_ipaddr_cmp(&obs->addr, addr)
+       && obs->port == port
+       && obs->token_len == token_len
+       && memcmp(obs->token, token, token_len) == 0) {
+      coap_obs_remove_observee(obs);
+      removed++;
+    }
+  }
+  return removed;
+}
+/*----------------------------------------------------------------------------*/
+int
+coap_obs_remove_observee_by_url(uip_ipaddr_t *addr, uint16_t port,
+                                const char *url)
+{
+  int removed = 0;
+  coap_observee_t *obs = NULL;
+
+  for(obs = (coap_observee_t *)list_head(obs_subjects_list); obs;
+      obs = obs->next) {
+    PRINTF("Remove check URL %s\n", url);
+    if(uip_ipaddr_cmp(&obs->addr, addr)
+       && obs->port == port
+       && (obs->url == url || memcmp(obs->url, url, strlen(obs->url)) == 0)) {
+      coap_obs_remove_observee(obs);
+      removed++;
+    }
+  }
+  return removed;
+}
+/*----------------------------------------------------------------------------*/
+static void
+simple_reply(coap_message_type_t type, uip_ip6addr_t *addr, uint16_t port,
+             coap_packet_t *notification)
+{
+  static coap_packet_t response[1];
+  size_t len;
+
+  coap_init_message(response, type, NO_ERROR, notification->mid);
+  len = coap_serialize_message(response, uip_appdata);
+  coap_send_message(addr, port, uip_appdata, len);
+}
+/*----------------------------------------------------------------------------*/
+static coap_notification_flag_t
+classify_notification(void *response, int first)
+{
+  coap_packet_t *pkt;
+
+  pkt = (coap_packet_t *)response;
+  if(!pkt) {
+    PRINTF("no response\n");
+    return NO_REPLY_FROM_SERVER;
+  }
+  PRINTF("server replied\n");
+  if(!IS_RESPONSE_CODE_2_XX(pkt)) {
+    PRINTF("error response code\n");
+    return ERROR_RESPONSE_CODE;
+  }
+  if(!IS_OPTION(pkt, COAP_OPTION_OBSERVE)) {
+    PRINTF("server does not support observe\n");
+    return OBSERVE_NOT_SUPPORTED;
+  }
+  if(first) {
+    return OBSERVE_OK;
+  }
+  return NOTIFICATION_OK;
+}
+/*----------------------------------------------------------------------------*/
+void
+coap_handle_notification(uip_ipaddr_t *addr, uint16_t port,
+                         coap_packet_t *notification)
+{
+  coap_packet_t *pkt;
+  const uint8_t *token;
+  int token_len;
+  coap_observee_t *obs;
+  coap_notification_flag_t flag;
+  uint32_t observe;
+
+  PRINTF("coap_handle_notification()\n");
+  pkt = (coap_packet_t *)notification;
+  token_len = get_token(pkt, &token);
+  PRINTF("Getting token\n");
+  if(0 == token_len) {
+    PRINTF("Error while handling coap observe notification: "
+           "no token in message\n");
+    return;
+  }
+  PRINTF("Getting observee info\n");
+  obs = coap_get_obs_subject_by_token(token, token_len);
+  if(NULL == obs) {
+    PRINTF("Error while handling coap observe notification: "
+           "no matching token found\n");
+    simple_reply(COAP_TYPE_RST, addr, port, notification);
+    return;
+  }
+  if(notification->type == COAP_TYPE_CON) {
+    simple_reply(COAP_TYPE_ACK, addr, port, notification);
+  }
+  if(obs->notification_callback != NULL) {
+    flag = classify_notification(notification, 0);
+    /* TODO: the following mechanism for discarding duplicates is too trivial */
+    /* refer to Observe RFC for a better solution */
+    if(flag == NOTIFICATION_OK) {
+      coap_get_header_observe(notification, &observe);
+      if(observe == obs->last_observe) {
+        PRINTF("Discarding duplicate\n");
+        return;
+      }
+      obs->last_observe = observe;
+    }
+    obs->notification_callback(obs, notification, flag);
+  }
+}
+/*----------------------------------------------------------------------------*/
+static void
+handle_obs_registration_response(void *data, void *response)
+{
+  coap_observee_t *obs;
+  notification_callback_t notification_callback;
+  coap_notification_flag_t flag;
+
+  PRINTF("handle_obs_registration_response(): ");
+  obs = (coap_observee_t *)data;
+  notification_callback = obs->notification_callback;
+  flag = classify_notification(response, 1);
+  if(notification_callback) {
+    notification_callback(obs, response, flag);
+  }
+  if(flag != OBSERVE_OK) {
+    coap_obs_remove_observee(obs);
+  }
+}
+/*----------------------------------------------------------------------------*/
+uint8_t
+coap_generate_token(uint8_t **token_ptr)
+{
+  static uint8_t token = 0;
+
+  token++;
+  /* FIXME: we should check that this token is not already used */
+  *token_ptr = (uint8_t *)&token;
+  return sizeof(token);
+}
+/*----------------------------------------------------------------------------*/
+coap_observee_t *
+coap_obs_request_registration(uip_ipaddr_t *addr, uint16_t port, char *uri,
+                              notification_callback_t notification_callback,
+                              void *data)
+{
+  coap_packet_t request[1];
+  coap_transaction_t *t;
+  uint8_t *token;
+  uint8_t token_len;
+  coap_observee_t *obs;
+
+  obs = NULL;
+  coap_init_message(request, COAP_TYPE_CON, COAP_GET, coap_get_mid());
+  coap_set_header_uri_path(request, uri);
+  coap_set_header_observe(request, 0);
+  token_len = coap_generate_token(&token);
+  set_token(request, token, token_len);
+  t = coap_new_transaction(request->mid, addr, port);
+  if(t) {
+    obs = coap_obs_add_observee(addr, port, (uint8_t *)token, token_len, uri,
+                                notification_callback, data);
+    if(obs) {
+      t->callback = handle_obs_registration_response;
+      t->callback_data = obs;
+      t->packet_len = coap_serialize_message(request, t->packet);
+      coap_send_transaction(t);
+    } else {
+      PRINTF("Could not allocate obs_subject resource buffer");
+      coap_clear_transaction(t);
+    }
+  } else {
+    PRINTF("Could not allocate transaction buffer");
+  }
+  return obs;
+}
+#endif /* COAP_OBSERVE_CLIENT */

apps/er-coap/er-coap-observe-client.h

@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2014, Daniele Alessandrelli.
+ * 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
+ *        Extension to Erbium for enabling CoAP observe clients
+ * \author
+ *        Daniele Alessandrelli <daniele.alessandrelli@gmail.com>
+ */
+
+#ifndef COAP_OBSERVING_CLIENT_H_
+#define COAP_OBSERVING_CLIENT_H_
+
+#include "er-coap.h"
+#include "er-coap-transactions.h"
+
+#ifndef COAP_OBSERVE_CLIENT
+#define COAP_OBSERVE_CLIENT 0
+#endif
+
+#ifdef COAP_CONF_MAX_OBSERVEES
+#define COAP_MAX_OBSERVEES COAP_CONF_MAX_OBSERVEES
+#else
+#define COAP_MAX_OBSERVEES      4
+#endif /* COAP_CONF_MAX_OBSERVEES */
+
+#if COAP_MAX_OPEN_TRANSACTIONS < COAP_MAX_OBSERVEES
+#warning "COAP_MAX_OPEN_TRANSACTIONS smaller than COAP_MAX_OBSERVEES: " \
+  "this may be a problem"
+#endif
+
+#define IS_RESPONSE_CODE_2_XX(message) (64 < message->code \
+                                        && message->code < 128)
+
+/*----------------------------------------------------------------------------*/
+typedef enum {
+  OBSERVE_OK,
+  NOTIFICATION_OK,
+  OBSERVE_NOT_SUPPORTED,
+  ERROR_RESPONSE_CODE,
+  NO_REPLY_FROM_SERVER,
+} coap_notification_flag_t;
+
+/*----------------------------------------------------------------------------*/
+typedef struct coap_observee_s coap_observee_t;
+
+typedef void (*notification_callback_t)(coap_observee_t *subject,
+                                        void *notification,
+                                        coap_notification_flag_t);
+
+struct coap_observee_s {
+  coap_observee_t *next;        /* for LIST */
+  uip_ipaddr_t addr;
+  uint16_t port;
+  const char *url;
+  uint8_t token_len;
+  uint8_t token[COAP_TOKEN_LEN];
+  void *data;                   /* generic pointer for storing user data */
+  notification_callback_t notification_callback;
+  uint32_t last_observe;
+};
+
+/*----------------------------------------------------------------------------*/
+coap_observee_t *coap_obs_add_observee(uip_ipaddr_t *addr, uint16_t port,
+                                       const uint8_t *token, size_t token_len,
+                                       const char *url,
+                                       notification_callback_t
+                                       notification_callback, void *data);
+
+void coap_obs_remove_observee(coap_observee_t *o);
+
+coap_observee_t *coap_obs_get_observee_by_token(const uint8_t *token,
+                                                size_t token_len);
+
+int coap_obs_remove_observee_by_token(uip_ipaddr_t *addr, uint16_t port,
+                                      uint8_t *token, size_t token_len);
+
+int coap_obs_remove_observee_by_url(uip_ipaddr_t *addr, uint16_t port,
+                                    const char *url);
+
+void coap_handle_notification(uip_ipaddr_t *, uint16_t port,
+                              coap_packet_t *notification);
+
+coap_observee_t *coap_obs_request_registration(uip_ipaddr_t *addr,
+                                               uint16_t port, char *uri,
+                                               notification_callback_t
+                                               notification_callback,
+                                               void *data);
+/* TODO: this function may be moved to er-coap.c */
+uint8_t coap_generate_token(uint8_t **token_ptr);
+
+#endif /* COAP_OBSERVING_CLIENT_H_ */