sntp.c

NXPl788上lwip的无操作系统移植,基于Embest开发板

 * to the SNTPv4 RFC, especially regarding server load and error procesing.
 */
static void
sntp_request(void *arg)
{
  int                sock;
  struct sockaddr_in local;
  struct sockaddr_in to;
  int                tolen;
  int                size;
  int                timeout;
  struct sntp_msg    sntpmsg;
  ip_addr_t          sntp_server_address;

  LWIP_UNUSED_ARG(arg);

  /* if we got a valid SNTP server address... */
  if (ipaddr_aton(SNTP_SERVER_ADDRESS, &sntp_server_address)) {
    /* create new socket */
    sock = lwip_socket(AF_INET, SOCK_DGRAM, 0);
    if (sock >= 0) {
      /* prepare local address */
      memset(&local, 0, sizeof(local));
      local.sin_family      = AF_INET;
      local.sin_port        = PP_HTONS(INADDR_ANY);
      local.sin_addr.s_addr = PP_HTONL(INADDR_ANY);

      /* bind to local address */
      if (lwip_bind(sock, (struct sockaddr *)&local, sizeof(local)) == 0) {
        /* set recv timeout */
        timeout = SNTP_RECV_TIMEOUT;
        lwip_setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(timeout));

        /* prepare SNTP request */
        sntp_initialize_request(&sntpmsg);

        /* prepare SNTP server address */
        memset(&to, 0, sizeof(to));
        to.sin_family      = AF_INET;
        to.sin_port        = PP_HTONS(SNTP_PORT);
        inet_addr_from_ipaddr(&to.sin_addr, &sntp_server_address);
    
        /* send SNTP request to server */
        if (lwip_sendto(sock, &sntpmsg, SNTP_MSG_LEN, 0, (struct sockaddr *)&to, sizeof(to)) >= 0) {
          /* receive SNTP server response */
          tolen = sizeof(to);
          size  = lwip_recvfrom(sock, &sntpmsg, SNTP_MSG_LEN, 0, (struct sockaddr *)&to, (socklen_t *)&tolen);
          /* if the response size is good */
          if (size == SNTP_MSG_LEN) {
            /* if this is a SNTP response... */
            if (((sntpmsg.li_vn_mode & SNTP_MODE_MASK) == SNTP_MODE_SERVER) ||
                ((sntpmsg.li_vn_mode & SNTP_MODE_MASK) == SNTP_MODE_BROADCAST)) {
              /* do time processing */
              sntp_process(sntpmsg.receive_timestamp);
            } else {
              LWIP_DEBUGF( SNTP_DEBUG_WARN, ("sntp_request: not response frame code\n"));
            }
          }
        } else {
          LWIP_DEBUGF( SNTP_DEBUG_WARN, ("sntp_request: not sendto==%i\n", errno));
        }
      }
      /* close the socket */
      closesocket(sock);
    }
  }
}

/**
 * SNTP thread
 */
static void
sntp_thread(void *arg)
{
  LWIP_UNUSED_ARG(arg);
  while(1) {
    sntp_request(NULL);
    sys_msleep(SNTP_UPDATE_DELAY);
  }
}

/**
 * Initialize this module when using sockets
 */
void
sntp_init(void)
{
  sys_thread_new("sntp_thread", sntp_thread, NULL, DEFAULT_THREAD_STACKSIZE, DEFAULT_THREAD_PRIO);
}

#else /* SNTP_SOCKET */

/**
 * Retry: send a new request (and increase retry timeout).
 *
 * @param arg is unused (only necessary to conform to sys_timeout)
 */
static void
sntp_retry(void* arg)
{
  LWIP_UNUSED_ARG(arg);

  LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_retry: Next request will be sent in %"U32_F" ms\n",
    sntp_retry_timeout));

  /* set up a timer to send a retry and increase the retry delay */
  sys_timeout(sntp_retry_timeout, sntp_request, NULL);

#if SNTP_RETRY_TIMEOUT_EXP
  {
    u32_t new_retry_timeout;
    /* increase the timeout for next retry */
    new_retry_timeout = sntp_retry_timeout << 1;
    /* limit to maximum timeout and prevent overflow */
    if ((new_retry_timeout <= SNTP_RETRY_TIMEOUT_MAX) &&
        (new_retry_timeout > sntp_retry_timeout)) {
      sntp_retry_timeout = new_retry_timeout;
    }
  }
#endif /* SNTP_RETRY_TIMEOUT_EXP */
}

#if SNTP_SUPPORT_MULTIPLE_SERVERS
/**
 * If Kiss-of-Death is received (or another packet parsing error),
 * try the next server or retry the current server and increase the retry
 * timeout if only one server is available.
 *
 * @param arg is unused (only necessary to conform to sys_timeout)
 */
static void
sntp_try_next_server(void* arg)
{
  LWIP_UNUSED_ARG(arg);

  if (sntp_num_servers > 1) {
    /* new server: reset retry timeout */
    SNTP_RESET_RETRY_TIMEOUT();
    sntp_current_server++;
    if (sntp_current_server >= sntp_num_servers) {
      sntp_current_server = 0;
    }
    LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_try_next_server: Sending request to server %"U16_F"\n",
      (u16_t)sntp_current_server));
    /* instantly send a request to the next server */
    sntp_request(NULL);
  } else {
    sntp_retry(NULL);
  }
}
#else /* SNTP_SUPPORT_MULTIPLE_SERVERS */
/* Always retry on error if only one server is supported */
#define sntp_try_next_server    sntp_retry
#endif /* SNTP_SUPPORT_MULTIPLE_SERVERS */

/** UDP recv callback for the sntp pcb */
static void
sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, ip_addr_t *addr, u16_t port)
{
  u8_t mode;
  u8_t stratum;
  u32_t receive_timestamp[SNTP_RECEIVE_TIME_SIZE];
  err_t err;

  LWIP_UNUSED_ARG(arg);
  LWIP_UNUSED_ARG(pcb);

  /* packet received: stop retry timeout  */
  sys_untimeout(sntp_try_next_server, NULL);
  sys_untimeout(sntp_request, NULL);

  err = ERR_ARG;
#if SNTP_CHECK_RESPONSE >= 1
  /* check server address and port */
  if (ip_addr_cmp(addr, &sntp_last_server_address) &&
    (port == SNTP_PORT))
#else /* SNTP_CHECK_RESPONSE >= 1 */
  LWIP_UNUSED_ARG(addr);
  LWIP_UNUSED_ARG(port);
#endif /* SNTP_CHECK_RESPONSE >= 1 */
  {
    /* process the response */
    if (p->tot_len == SNTP_MSG_LEN) {
      pbuf_copy_partial(p, &mode, 1, SNTP_OFFSET_LI_VN_MODE);
      mode &= SNTP_MODE_MASK;
      /* if this is a SNTP response... */
      if ((mode == SNTP_MODE_SERVER) ||
          (mode == SNTP_MODE_BROADCAST)) {
        pbuf_copy_partial(p, &stratum, 1, SNTP_OFFSET_STRATUM);
        if (stratum == SNTP_STRATUM_KOD) {
          /* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
          err = SNTP_ERR_KOD;
          LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Received Kiss-of-Death\n"));
        } else {
#if SNTP_CHECK_RESPONSE >= 2
          /* check originate_timetamp against sntp_last_timestamp_sent */
          u32_t originate_timestamp[2];
          pbuf_copy_partial(p, &originate_timestamp, 8, SNTP_OFFSET_ORIGINATE_TIME);
          if ((originate_timestamp[0] != sntp_last_timestamp_sent[0]) ||
              (originate_timestamp[1] != sntp_last_timestamp_sent[1]))
          {
            LWIP_DEBUGF(SNTP_DEBUG_WARN, ("sntp_recv: Invalid originate timestamp in response\n"));
          } else
#endif /* SNTP_CHECK_RESPONSE >= 2 */
          /* @todo: add code for SNTP_CHECK_RESPONSE >= 3 and >= 4 here */
          {
            /* correct answer */
            err = ERR_OK;
            pbuf_copy_partial(p, &receive_timestamp, SNTP_RECEIVE_TIME_SIZE * 4, SNTP_OFFSET_RECEIVE_TIME);
          }
        }
      } else {
        LWIP_DEBUGF(SNTP_DEBUG_WARN, ("sntp_recv: Invalid mode in response: %"U16_F"\n", (u16_t)mode));
      }
    } else {
      LWIP_DEBUGF(SNTP_DEBUG_WARN, ("sntp_recv: Invalid packet length: %"U16_F"\n", p->tot_len));
    }
  }
  pbuf_free(p);
  if (err == ERR_OK) {
    /* Correct response, reset retry timeout */
    SNTP_RESET_RETRY_TIMEOUT();

    sntp_process(receive_timestamp);

    /* Set up timeout for next request */
    sys_timeout((u32_t)SNTP_UPDATE_DELAY, sntp_request, NULL);
    LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Scheduled next time request: %"U32_F" ms\n",
      (u32_t)SNTP_UPDATE_DELAY));
  } else if (err == SNTP_ERR_KOD) {
    /* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
    sntp_try_next_server(NULL);
  } else {
    /* another error, try the same server again */
    sntp_retry(NULL);
  }
}

/** Actually send an sntp request to a server.
 *
 * @param server_addr resolved IP address of the SNTP server
 */
static void
sntp_send_request(ip_addr_t *server_addr)
{
  struct pbuf* p;
  p = pbuf_alloc(PBUF_TRANSPORT, SNTP_MSG_LEN, PBUF_RAM);
  if (p != NULL) {
    struct sntp_msg *sntpmsg = (struct sntp_msg *)p->payload;
    LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_send_request: Sending request to server\n"));
    /* initialize request message */
    sntp_initialize_request(sntpmsg);
    /* send request */
    udp_sendto(sntp_pcb, p, server_addr, SNTP_PORT);
    /* set up receive timeout: try next server or retry on timeout */
    sys_timeout((u32_t)SNTP_RECV_TIMEOUT, sntp_try_next_server, NULL);
#if SNTP_CHECK_RESPONSE >= 1
    /* save server address to verify it in sntp_recv */ 
    ip_addr_set(&sntp_last_server_address, server_addr);
#endif /* SNTP_CHECK_RESPONSE >= 1 */
  } else {
    LWIP_DEBUGF(SNTP_DEBUG_SERIOUS, ("sntp_send_request: Out of memory, trying again in %"U32_F" ms\n",
      (u32_t)SNTP_RETRY_TIMEOUT));
    /* out of memory: set up a timer to send a retry */
    sys_timeout((u32_t)SNTP_RETRY_TIMEOUT, sntp_request, NULL);
  }
}

#if SNTP_SERVER_DNS
/**
 * DNS found callback when using DNS names as server address.
 */
static void
sntp_dns_found(const char* hostname, ip_addr_t *ipaddr, void *arg)
{
  LWIP_UNUSED_ARG(hostname);
  LWIP_UNUSED_ARG(arg);

  if (ipaddr != NULL) {
    /* Address resolved, send request */
    LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_dns_found: Server address resolved, sending request\n"));
    sntp_send_request(ipaddr);
  } else {
    /* DNS resolving failed -> try another server */
    LWIP_DEBUGF(SNTP_DEBUG_WARN_STATE, ("sntp_dns_found: Failed to resolve server address resolved, trying next server\n"));
    sntp_try_next_server(NULL);
  }
}
#endif /* SNTP_SERVER_DNS */

/**
 * Send out an sntp request via raw API.
 *
 * @param arg is unused (only necessary to conform to sys_timeout)
 */
static void
sntp_request(void *arg)
{
  ip_addr_t sntp_server_address;
  err_t err;

  LWIP_UNUSED_ARG(arg);

  /* initialize SNTP server address */
#if SNTP_SERVER_DNS
  err = dns_gethostbyname(sntp_server_addresses[sntp_current_server], &sntp_server_address,
    sntp_dns_found, NULL);
  if (err == ERR_INPROGRESS) {
    /* DNS request sent, wait for sntp_dns_found being called */
    LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_request: Waiting for server address to be resolved.\n"));
    return;
  }
#else /* SNTP_SERVER_DNS */
  err = ipaddr_aton(sntp_server_addresses[sntp_current_server], &sntp_server_address)
    ? ERR_OK : ERR_ARG;

#endif /* SNTP_SERVER_DNS */

  if (err == ERR_OK) {
    sntp_send_request(&sntp_server_address);
  } else {
    /* address conversion failed, try another server */
    LWIP_DEBUGF(SNTP_DEBUG_WARN_STATE, ("sntp_request: Invalid server address, trying next server.\n"));
    sys_timeout((u32_t)SNTP_RETRY_TIMEOUT, sntp_try_next_server, NULL);
  }
}

/**
 * Initialize this module when using raw API.
 * Send out request instantly or after SNTP_STARTUP_DELAY.
 */
void
sntp_init(void)
{
  SNTP_RESET_RETRY_TIMEOUT();
  sntp_pcb = udp_new();
  LWIP_ASSERT("Failed to allocate udp pcb for sntp client", sntp_pcb != NULL);
  if (sntp_pcb != NULL) {
    udp_recv(sntp_pcb, sntp_recv, NULL);
#if SNTP_STARTUP_DELAY
    sys_timeout((u32_t)SNTP_STARTUP_DELAY, sntp_request, NULL);
#else
    sntp_request(NULL);
#endif
  }
}

#endif /* SNTP_SOCKET */

#endif /* LWIP_UDP */