/**
 * @file
 * Ping sender module
 *
 */

/*
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 lwIP TCP/IP stack.
 * 
 */

/** 
 * This is an example of a "ping" sender (with raw API and socket API).
 * It can be used as a start point to maintain opened a network connection, or
 * like a network "watchdog" for your device.
 *
 */

#include "lwip/opt.h"

#if LWIP_RAW && LWIP_ICMP /* don't build if not configured for use in lwipopts.h */

#include "lwip/mem.h"
#include "lwip/raw.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"

/**
 * PING_DEBUG: Enable debugging for PING.
 */
#ifndef PING_DEBUG
#define PING_DEBUG     LWIP_DBG_ON
#endif

/** ping target - should be a "struct ip_addr" */
#ifndef PING_TARGET
#define PING_TARGET   (netif_default?netif_default->gw:ip_addr_any)
#endif

/** ping receive timeout - in milliseconds */
#ifndef PING_RCV_TIMEO
#define PING_RCV_TIMEO 1000
#endif

/** ping delay - in milliseconds */
#ifndef PING_DELAY
#define PING_DELAY     1000
#endif

/** 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 result action - no default action */
#ifndef PING_RESULT
#define PING_RESULT(ping_ok)
#endif

/* ping variables */
static u16_t ping_seq_num;
static u32_t ping_time;

#if NO_SYS
/* port-defined functions used for timer execution */
void sys_msleep(u32_t ms);
u32_t sys_now();
#endif /* NO_SYS */

/** Prepare a echo ICMP request */
static void
ping_prepare_echo( struct icmp_echo_hdr *iecho, u16_t len)
{
  int i;

  ICMPH_TYPE_SET(iecho,ICMP_ECHO);
  ICMPH_CODE_SET(iecho, 0);
  iecho->chksum = 0;
  iecho->id     = PING_ID;
  iecho->seqno  = htons(++ping_seq_num);
  iecho->chksum = inet_chksum(iecho, len);

  /* fill the additional data buffer with some data */
  for(i = 0; i < PING_DATA_SIZE; i++) {
    ((char*)iecho)[sizeof(struct icmp_echo_hdr) + i] = i;
  }
}

#if LWIP_SOCKET

/* Ping using the socket ip */
static void
ping_send(int s, struct ip_addr *addr)
{
  struct icmp_echo_hdr *iecho;
  struct sockaddr_in to;
  size_t ping_size = sizeof(struct icmp_echo_hdr) + PING_DATA_SIZE;

  if (!(iecho = mem_malloc(ping_size))) {
    return;
  }

  ping_prepare_echo(iecho, ping_size);

  to.sin_len = sizeof(to);
  to.sin_family = AF_INET;
  to.sin_addr.s_addr = addr->addr;

  lwip_sendto(s, iecho, ping_size, 0, (struct sockaddr*)&to, sizeof(to));

  mem_free(iecho);
}

static void
ping_recv(int s)
{
  char buf[64];
  int fromlen, len;
  struct sockaddr_in from;
  struct icmp_echo_hdr *iecho;

  while((len = lwip_recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr*)&from, &fromlen)) > 0) {
    if (len >= sizeof(struct icmp_echo_hdr)) {
      LWIP_DEBUGF( PING_DEBUG, ("ping: recv "));
      ip_addr_debug_print(PING_DEBUG, (struct ip_addr *)&(from.sin_addr));
      LWIP_DEBUGF( PING_DEBUG, (" %lu ms\n", (sys_now()-ping_time)));

      iecho = (struct icmp_echo_hdr *)buf;
      if ((iecho->id == PING_ID) && (iecho->seqno == htons(ping_seq_num))) {
        /* do some ping result processing */
        PING_RESULT(1);
        return;
      }
    }
  }

  /* do some ping result processing */
  PING_RESULT(0);
}

static void
ping_thread(void *arg)
{
  int s;
  int timeout = PING_RCV_TIMEO;
  struct ip_addr ping_target = PING_TARGET;

  if ((s = lwip_socket(AF_INET, SOCK_RAW, IP_PROTO_ICMP)) < 0) {
    return;
  }

  lwip_setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));

  while (1) {
    LWIP_DEBUGF( PING_DEBUG, ("ping: send "));
    ip_addr_debug_print(PING_DEBUG, &ping_target);
    LWIP_DEBUGF( PING_DEBUG, ("\n"));

    ping_send(s, &ping_target);
    ping_time = sys_now();
    ping_recv(s);
    sys_msleep(PING_DELAY);
  }
}

#else /* LWIP_SOCKET */

/* Ping using the raw ip */
static u8_t
ping_recv(void *arg, struct raw_pcb *pcb, struct pbuf *p, struct ip_addr *addr)
{
  struct icmp_echo_hdr *iecho;

  if (pbuf_header( p, -PBUF_IP_HLEN)==0) {
    iecho = p->payload;

    if ((iecho->id == PING_ID) && (iecho->seqno == htons(ping_seq_num))) {
      LWIP_DEBUGF( PING_DEBUG, ("ping: recv "));
      ip_addr_debug_print(PING_DEBUG, addr);
      LWIP_DEBUGF( PING_DEBUG, (" %lu ms\n", (sys_now()-ping_time)));

      /* do some ping result processing */
      PING_RESULT(1);
    }
  }

  return 1; /* eat the event */
}

static void
ping_send(struct raw_pcb *raw, struct ip_addr *addr)
{
  struct pbuf *p;
  struct icmp_echo_hdr *iecho;
  size_t ping_size = sizeof(struct icmp_echo_hdr) + PING_DATA_SIZE;

  if (!(p = pbuf_alloc(PBUF_IP, ping_size, PBUF_RAM))) {
    return;
  }
  if ((p->len == p->tot_len) && (p->next == NULL)) {
    iecho = p->payload;

    ping_prepare_echo(iecho, ping_size);

    raw_sendto(raw, p, addr);
    ping_time = sys_now();
  }
  pbuf_free(p);
}

static void
ping_timeout(void *arg)
{
  struct raw_pcb *pcb = (struct raw_pcb*)arg;
  struct ip_addr ping_target = PING_TARGET;
  
  LWIP_ASSERT("ping_timeout: no pcb given!", pcb != NULL);

  LWIP_DEBUGF( PING_DEBUG, ("ping: send "));
  ip_addr_debug_print(PING_DEBUG, &ping_target);
  LWIP_DEBUGF( PING_DEBUG, ("\n"));

  ping_send(pcb, &ping_target);

  sys_timeout(PING_DELAY, ping_timeout, pcb);
}

static void
ping_raw_init(void)
{
  struct raw_pcb *pcb;

  if (!(pcb = raw_new(IP_PROTO_ICMP))) {
    return;
  }

  raw_recv(pcb, ping_recv, NULL);
  raw_bind(pcb, IP_ADDR_ANY);
  sys_timeout(PING_DELAY, ping_timeout, pcb);
}

#endif /* LWIP_SOCKET */

void
ping_init(void)
{
#if LWIP_SOCKET
  sys_thread_new("ping_thread", ping_thread, NULL, DEFAULT_THREAD_STACKSIZE, DEFAULT_THREAD_PRIO);
#else /* LWIP_SOCKET */
  ping_raw_init();
#endif /* LWIP_SOCKET */
}

#endif /* LWIP_RAW && LWIP_ICMP */