netutils: add DHCP-provided NTP server for ntpc

include/netutils/dhcpc.h

@@ -55,6 +55,10 @@
 #  define CONFIG_NETDB_DNSSERVER_NAMESERVERS 1
 #endif
 
+#if !defined(CONFIG_NETUTILS_DHCPC_NTP_SERVERS)
+#  define CONFIG_NETUTILS_DHCPC_NTP_SERVERS 1
+#endif
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -66,6 +70,8 @@ struct dhcpc_state
   struct in_addr netmask;
   struct in_addr dnsaddr[CONFIG_NETDB_DNSSERVER_NAMESERVERS];
   uint8_t        num_dnsaddr;     /* Number of DNS addresses received */
+  struct in_addr ntpaddr[CONFIG_NETUTILS_DHCPC_NTP_SERVERS];
+  uint8_t        num_ntpaddr;     /* Number of NTP addresses received */
   struct in_addr default_router;
   uint32_t       lease_time;      /* Lease expires in this number of seconds */
   uint32_t       renewal_time;    /* Seconds to transition to RENEW state(T1) */

include/netutils/netlib.h

@@ -203,6 +203,11 @@ struct url_s
 };
 #endif
 
+#ifdef CONFIG_NETUTILS_DHCPC
+typedef CODE void (*netlib_dhcp_ntp_callback_t)
+  (FAR const char *ntp_server_list, FAR void *arg);
+#endif
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/
@@ -247,6 +252,44 @@ ssize_t netlib_get_devices(FAR struct netlib_device_s *devlist,
 bool netlib_ipv4addrconv(FAR const char *addrstr, FAR uint8_t *addr);
 bool netlib_ethaddrconv(FAR const char *hwstr, FAR uint8_t *hw);
 
+#ifdef CONFIG_NETUTILS_DHCPC
+/****************************************************************************
+ * Name: netlib_set_ntp_servers_from_dhcp
+ *
+ * Description:
+ *   Update the currently active DHCP option 42 NTP server list. The list
+ *   contains semicolon-separated hostnames or addresses. Passing NULL or
+ *   an empty string clears the DHCP-provided list.
+ *
+ ****************************************************************************/
+
+int netlib_set_ntp_servers_from_dhcp(FAR const char *ntp_server_list);
+
+/****************************************************************************
+ * Name: netlib_register_dhcp_ntp_callback
+ *
+ * Description:
+ *   Register a callback to receive DHCP option 42 NTP server list updates.
+ *   The current list, if any, is replayed immediately after registration.
+ *   Only one callback may be registered at a time.
+ *
+ ****************************************************************************/
+
+int netlib_register_dhcp_ntp_callback(netlib_dhcp_ntp_callback_t callback,
+                                      FAR void *arg);
+
+/****************************************************************************
+ * Name: netlib_unregister_dhcp_ntp_callback
+ *
+ * Description:
+ *   Unregister a previously registered DHCP option 42 NTP update callback.
+ *
+ ****************************************************************************/
+
+int netlib_unregister_dhcp_ntp_callback(netlib_dhcp_ntp_callback_t callback,
+                                        FAR void *arg);
+#endif
+
 #ifdef CONFIG_NET_ETHERNET
 /* Get and set IP/MAC addresses (Ethernet L2 only) */
 

netutils/dhcpc/dhcpc.c

@@ -91,6 +91,7 @@
 #define DHCP_OPTION_ROUTER      3
 #define DHCP_OPTION_DNS_SERVER  6
 #define DHCP_OPTION_HOST_NAME   12
+#define DHCP_OPTION_NTP_SERVER  42
 #define DHCP_OPTION_REQ_IPADDR  50
 #define DHCP_OPTION_LEASE_TIME  51
 #define DHCP_OPTION_MSG_TYPE    53
@@ -210,10 +211,11 @@ static FAR uint8_t *dhcpc_addclientid(FAR uint8_t *clientid,
 static FAR uint8_t *dhcpc_addreqoptions(FAR uint8_t *optptr)
 {
   *optptr++ = DHCP_OPTION_REQ_LIST;
-  *optptr++ = 3;
+  *optptr++ = 4;
   *optptr++ = DHCP_OPTION_SUBNET_MASK;
   *optptr++ = DHCP_OPTION_ROUTER;
   *optptr++ = DHCP_OPTION_DNS_SERVER;
+  *optptr++ = DHCP_OPTION_NTP_SERVER;
   return optptr;
 }
 
@@ -411,6 +413,39 @@ static uint8_t dhcpc_parseoptions(FAR struct dhcpc_state *presult,
               }
             break;
 
+          case DHCP_OPTION_NTP_SERVER:
+
+            /* Get the NTP server addresses in network order.
+             * DHCP option 42 can contain multiple IPv4 addresses,
+             * each 4 bytes long.
+             */
+
+            if (optptr + 2 <= end)
+              {
+                uint8_t optlen = *(optptr + 1);
+                uint8_t num_ntp = optlen / 4;
+                uint8_t i;
+
+                if (num_ntp > CONFIG_NETUTILS_DHCPC_NTP_SERVERS)
+                  {
+                    num_ntp = CONFIG_NETUTILS_DHCPC_NTP_SERVERS;
+                  }
+
+                presult->num_ntpaddr = 0;
+                for (i = 0; i < num_ntp && (optptr + 2 + i * 4 + 4) <= end;
+                     i++)
+                  {
+                    memcpy(&presult->ntpaddr[i].s_addr, optptr + 2 + i * 4,
+                           4);
+                    presult->num_ntpaddr++;
+                  }
+              }
+            else
+              {
+                nerr("Packet too short (NTP address missing)\n");
+              }
+            break;
+
           case DHCP_OPTION_MSG_TYPE:
 
             /* Get message type */
@@ -999,6 +1034,21 @@ int dhcpc_request(FAR void *handle, FAR struct dhcpc_state *presult)
         }
     }
 
+  /* Print all NTP servers received */
+
+  if (presult->num_ntpaddr > 0)
+    {
+      uint8_t i;
+      for (i = 0; i < presult->num_ntpaddr; i++)
+        {
+          ninfo("Got NTP server %d: %u.%u.%u.%u\n", i,
+                ip4_addr1(presult->ntpaddr[i].s_addr),
+                ip4_addr2(presult->ntpaddr[i].s_addr),
+                ip4_addr3(presult->ntpaddr[i].s_addr),
+                ip4_addr4(presult->ntpaddr[i].s_addr));
+        }
+    }
+
   ninfo("Got default router %u.%u.%u.%u\n",
         ip4_addr1(presult->default_router.s_addr),
         ip4_addr2(presult->default_router.s_addr),

netutils/netlib/CMakeLists.txt

@@ -57,6 +57,7 @@ if(CONFIG_NETUTILS_NETLIB)
     endif()
     if(CONFIG_NETUTILS_DHCPC)
       list(APPEND SRCS netlib_obtainipv4addr.c)
+      list(APPEND SRCS netlib_dhcp_ntp.c)
     endif()
   endif()
 

netutils/netlib/Makefile

@@ -57,6 +57,7 @@ CSRCS += netlib_iptables.c
 endif
 ifeq ($(CONFIG_NETUTILS_DHCPC),y)
 CSRCS += netlib_obtainipv4addr.c
+CSRCS += netlib_dhcp_ntp.c
 endif
 endif
 

netutils/netlib/netlib_dhcp_ntp.c

@@ -0,0 +1,182 @@
+/****************************************************************************
+ * apps/netutils/netlib/netlib_dhcp_ntp.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#ifdef CONFIG_NETUTILS_DHCPC
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "netutils/netlib.h"
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static pthread_mutex_t g_dhcp_ntp_lock = PTHREAD_MUTEX_INITIALIZER;
+static FAR char *g_dhcp_ntp_servers;
+static netlib_dhcp_ntp_callback_t g_dhcp_ntp_callback;
+static FAR void *g_dhcp_ntp_callback_arg;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static FAR char *netlib_dhcp_ntp_dup(FAR const char *ntp_server_list)
+{
+  if (ntp_server_list == NULL || ntp_server_list[0] == '\0')
+    {
+      return NULL;
+    }
+
+  return strdup(ntp_server_list);
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int netlib_set_ntp_servers_from_dhcp(FAR const char *ntp_server_list)
+{
+  FAR char *new_servers;
+  FAR char *notify_servers = NULL;
+  FAR char *old_servers;
+  netlib_dhcp_ntp_callback_t callback;
+  FAR void *arg;
+  int ret = OK;
+
+  new_servers = netlib_dhcp_ntp_dup(ntp_server_list);
+  if (ntp_server_list != NULL && ntp_server_list[0] != '\0' &&
+      new_servers == NULL)
+    {
+      return -ENOMEM;
+    }
+
+  pthread_mutex_lock(&g_dhcp_ntp_lock);
+
+  if ((g_dhcp_ntp_servers == NULL && new_servers == NULL) ||
+      (g_dhcp_ntp_servers != NULL && new_servers != NULL &&
+       strcmp(g_dhcp_ntp_servers, new_servers) == 0))
+    {
+      pthread_mutex_unlock(&g_dhcp_ntp_lock);
+      free(new_servers);
+      return OK;
+    }
+
+  callback = g_dhcp_ntp_callback;
+  arg = g_dhcp_ntp_callback_arg;
+
+  if (callback != NULL && new_servers != NULL)
+    {
+      notify_servers = strdup(new_servers);
+      if (notify_servers == NULL)
+        {
+          ret = -ENOMEM;
+          goto errout_with_lock;
+        }
+    }
+
+  old_servers = g_dhcp_ntp_servers;
+  g_dhcp_ntp_servers = new_servers;
+  pthread_mutex_unlock(&g_dhcp_ntp_lock);
+
+  free(old_servers);
+
+  if (callback != NULL)
+    {
+      callback(notify_servers, arg);
+    }
+
+  free(notify_servers);
+  return OK;
+
+errout_with_lock:
+  pthread_mutex_unlock(&g_dhcp_ntp_lock);
+  free(new_servers);
+  return ret;
+}
+
+int netlib_register_dhcp_ntp_callback(netlib_dhcp_ntp_callback_t callback,
+                                      FAR void *arg)
+{
+  FAR char *notify_servers = NULL;
+
+  if (callback == NULL)
+    {
+      return -EINVAL;
+    }
+
+  pthread_mutex_lock(&g_dhcp_ntp_lock);
+
+  if (g_dhcp_ntp_callback != NULL &&
+      (g_dhcp_ntp_callback != callback || g_dhcp_ntp_callback_arg != arg))
+    {
+      pthread_mutex_unlock(&g_dhcp_ntp_lock);
+      return -EBUSY;
+    }
+
+  if (g_dhcp_ntp_servers != NULL)
+    {
+      notify_servers = strdup(g_dhcp_ntp_servers);
+      if (notify_servers == NULL)
+        {
+          pthread_mutex_unlock(&g_dhcp_ntp_lock);
+          return -ENOMEM;
+        }
+    }
+
+  g_dhcp_ntp_callback = callback;
+  g_dhcp_ntp_callback_arg = arg;
+
+  pthread_mutex_unlock(&g_dhcp_ntp_lock);
+
+  callback(notify_servers, arg);
+  free(notify_servers);
+  return OK;
+}
+
+int netlib_unregister_dhcp_ntp_callback(netlib_dhcp_ntp_callback_t callback,
+                                        FAR void *arg)
+{
+  int ret = -ENOENT;
+
+  pthread_mutex_lock(&g_dhcp_ntp_lock);
+
+  if (g_dhcp_ntp_callback == callback && g_dhcp_ntp_callback_arg == arg)
+    {
+      g_dhcp_ntp_callback = NULL;
+      g_dhcp_ntp_callback_arg = NULL;
+      ret = OK;
+    }
+
+  pthread_mutex_unlock(&g_dhcp_ntp_lock);
+  return ret;
+}
+
+#endif /* CONFIG_NETUTILS_DHCPC */