text: /*
   * netutils: ping implementation
   */
  
  #include "lwip/opt.h"
  
  #include "lwip/mem.h"
  #include "lwip/icmp.h"
  #include "lwip/netif.h"
  #include "lwip/sys.h"
  #include "lwip/sockets.h"
  #include "lwip/inet.h"
  #include "lwip/inet_chksum.h"
  #include "lwip/ip.h"
  #include <rthw.h>
  #include <rtthread.h>
  
  /**
   * PING_DEBUG: Enable debugging for PING.
   */
  #ifndef PING_DEBUG
  #define PING_DEBUG     LWIP_DBG_ON
  #endif
  
  /** ping receive timeout - in milliseconds */
  #define PING_RCV_TIMEO 1000
  /** ping delay - in milliseconds */
  #define PING_DELAY     100
  
  /** ping identifier - must fit on a u16_t */
  #ifndef PING_ID
  #define PING_ID        0xAFAF
  #endif
  
  /** ping additional data size to include in the packet */
  #ifndef PING_DATA_SIZE
  #define PING_DATA_SIZE 32
  #endif
  
  /* ping variables */
  static u16_t ping_seq_num;
  struct _ip_addr
  {
      rt_uint8_t addr0, addr1, addr2, addr3;
  };
  
  /** Prepare a echo ICMP request */
  static void ping_prepare_echo( struct icmp_echo_hdr *iecho, u16_t len)
  {
      size_t i;
      size_t data_len = len - sizeof(struct icmp_echo_hdr);
  
      ICMPH_TYPE_SET(iecho, ICMP_ECHO);
      ICMPH_CODE_SET(iecho, 0);
      iecho->chksum = 0;
      iecho->id     = PING_ID;
      iecho->seqno  = htons(++ping_seq_num);
  
      /* fill the additional data buffer with some data */
      for(i = 0; i < data_len; i++)
      {
          ((char*)iecho)[sizeof(struct icmp_echo_hdr) + i] = (char)i;
      }
  
      iecho->chksum = inet_chksum(iecho, len);
  }
  
  /* Ping using the socket ip */
  static err_t ping_send(int s, struct ip_addr *addr, int size)
  {
      int err;
      struct icmp_echo_hdr *iecho;
      struct sockaddr_in to;
      size_t ping_size = sizeof(struct icmp_echo_hdr) + size;
      LWIP_ASSERT("ping_size is too big", ping_size <= 0xffff);
  
      iecho = rt_malloc(ping_size);
      if (iecho == RT_NULL)
      {
          return ERR_MEM;
      }
  
      ping_prepare_echo(iecho, (u16_t)ping_size);
  
      to.sin_len = sizeof(to);
      to.sin_family = AF_INET;
      to.sin_addr.s_addr = addr->addr;
  
      err = lwip_sendto(s, iecho, ping_size, 0, (struct sockaddr*)&to, sizeof(to));
      rt_free(iecho);
  
      return (err ? ERR_OK : ERR_VAL);
  }
  
  static void ping_recv(int s)
  {
      char buf[64];
      int fromlen, len;
      struct sockaddr_in from;
      struct ip_hdr *iphdr;
      struct icmp_echo_hdr *iecho;
      struct _ip_addr *addr;
  
      while((len = lwip_recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr*)&from, (socklen_t*)&fromlen)) > 0)
      {
          if (len >= (sizeof(struct ip_hdr)+sizeof(struct icmp_echo_hdr)))
          {
              addr = (struct _ip_addr *)&(from.sin_addr);
              rt_kprintf("ping: recv %d.%d.%d.%d\n", addr->addr0, addr->addr1, addr->addr2, addr->addr3);
  
              iphdr = (struct ip_hdr *)buf;
              iecho = (struct icmp_echo_hdr *)(buf+(IPH_HL(iphdr) * 4));
              if ((iecho->id == PING_ID) && (iecho->seqno == htons(ping_seq_num)))
              {
                  return;
              }
              else
              {
                  rt_kprintf("ping: drop\n");
              }
          }
      }
  
      if (len <= 0)
      {
          rt_kprintf("ping: timeout\n");
      }
  }
  
  rt_err_t ping(char* target, rt_uint32_t time, rt_size_t size)
  {
      int s;
      int timeout = PING_RCV_TIMEO;
      struct ip_addr ping_target;
      rt_uint32_t send_time;
      struct _ip_addr
      {
          rt_uint8_t addr0, addr1, addr2, addr3;
      } *addr;
  
      send_time = 0;
  
      if(size == 0)
          size = PING_DATA_SIZE;
  
      if (inet_aton(target, (struct in_addr*)&ping_target) == 0) return -RT_ERROR;
      addr = (struct _ip_addr*)&ping_target;
  
      if ((s = lwip_socket(AF_INET, SOCK_RAW, IP_PROTO_ICMP)) < 0)
      {
          rt_kprintf("create socket failled\n");
          return -RT_ERROR;
      }
  
      lwip_setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
  
      while (1)
      {
          if (ping_send(s, &ping_target, size) == ERR_OK)
          {
              rt_kprintf("ping: send %d.%d.%d.%d\n", addr->addr0, addr->addr1, addr->addr2, addr->addr3);
              ping_recv(s);
          }
          else
          {
              rt_kprintf("ping: send %d.%d.%d.%d - error\n", addr->addr0, addr->addr1, addr->addr2, addr->addr3);
          }
  
          send_time ++;
          if (send_time >= time) break; /* send ping times reached, stop */
  
          rt_thread_delay(PING_DELAY); /* take a delay */
      }
  
      lwip_close(s);
  
      return RT_EOK;
  }
  #ifdef RT_USING_FINSH
  #include <finsh.h>
  MSH_CMD_EXPORT(ping, ping network host)
  #endif
  