/*
 * Copyright (c) 2005, Swedish Institute of Computer Science
 * 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 uIP TCP/IP stack
 *
 * @(#)$Id: dhcpc.c 125 2015-07-23 06:21:02Z coas-nagasima $
 */

#include <stdio.h>
#include <string.h>

#include "uip.h"
#include "dhcpc.h"
#include "timer.h"
#include "pt.h"

#define STATE_INITIAL         0
#define STATE_REQUEST         1
#define STATE_SENDING         2
#define STATE_OFFER_RECEIVED  3
#define STATE_CONFIG_RECEIVED 4

#ifdef __RX
#pragma pack
#elif _MSC_VER
#pragma pack(push, 1)
#endif

struct dhcp_msg {
  u8_t op, htype, hlen, hops;
  u8_t xid[4];
  u16_t secs, flags;
  u8_t ciaddr[4];
  u8_t yiaddr[4];
  u8_t siaddr[4];
  u8_t giaddr[4];
  u8_t chaddr[16];
#ifndef UIP_CONF_DHCP_LIGHT
  u8_t sname[64];
  u8_t file[128];
#endif
  u8_t options[312];
};

#ifdef __RX
#pragma unpack
#elif _MSC_VER
#pragma pack(pop)
#endif

#define BOOTP_BROADCAST 0x8000

#define DHCP_REQUEST        1
#define DHCP_REPLY          2
#define DHCP_HTYPE_ETHERNET 1
#define DHCP_HLEN_ETHERNET  6
#define DHCP_MSG_LEN      236

#define DHCPC_SERVER_PORT  67
#define DHCPC_CLIENT_PORT  68

#define DHCPDISCOVER  1
#define DHCPOFFER     2
#define DHCPREQUEST   3
#define DHCPDECLINE   4
#define DHCPACK       5
#define DHCPNAK       6
#define DHCPRELEASE   7

#define DHCP_OPTION_SUBNET_MASK   1
#define DHCP_OPTION_ROUTER        3
#define DHCP_OPTION_DNS_SERVER    6
#define DHCP_OPTION_REQ_IPADDR   50
#define DHCP_OPTION_LEASE_TIME   51
#define DHCP_OPTION_MSG_TYPE     53
#define DHCP_OPTION_SERVER_ID    54
#define DHCP_OPTION_REQ_LIST     55
#define DHCP_OPTION_END         255

static const u8_t xid[4] = {0xad, 0xde, 0x12, 0x23};
static const u8_t magic_cookie[4] = {99, 130, 83, 99};
/*---------------------------------------------------------------------------*/
static u8_t *
add_msg_type(u8_t *optptr, u8_t type)
{
  *optptr++ = DHCP_OPTION_MSG_TYPE;
  *optptr++ = 1;
  *optptr++ = type;
  return optptr;
}
/*---------------------------------------------------------------------------*/
static u8_t *
add_server_id(struct dhcpc_state *s, u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_SERVER_ID;
  *optptr++ = 4;
  memcpy(optptr, s->serverid, 4);
  return optptr + 4;
}
/*---------------------------------------------------------------------------*/
static u8_t *
add_req_ipaddr(struct dhcpc_state *s, u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_REQ_IPADDR;
  *optptr++ = 4;
  memcpy(optptr, s->ipaddr, 4);
  return optptr + 4;
}
/*---------------------------------------------------------------------------*/
static u8_t *
add_req_options(u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_REQ_LIST;
  *optptr++ = 3;
  *optptr++ = DHCP_OPTION_SUBNET_MASK;
  *optptr++ = DHCP_OPTION_ROUTER;
  *optptr++ = DHCP_OPTION_DNS_SERVER;
  return optptr;
}
/*---------------------------------------------------------------------------*/
static u8_t *
add_end(u8_t *optptr)
{
  *optptr++ = DHCP_OPTION_END;
  return optptr;
}
/*---------------------------------------------------------------------------*/
static void
create_msg(struct dhcpc_state *s, struct dhcp_msg *m)
{
  m->op = DHCP_REQUEST;
  m->htype = DHCP_HTYPE_ETHERNET;
  m->hlen = s->mac_len;
  m->hops = 0;
  memcpy(m->xid, xid, sizeof(m->xid));
  m->secs = 0;
  m->flags = HTONS(BOOTP_BROADCAST); /*  Broadcast bit. */
  /*  uip_ipaddr_copy(m->ciaddr, uip_hostaddr);*/
  memcpy(m->ciaddr, uip_hostaddr, sizeof(m->ciaddr));
  memset(m->yiaddr, 0, sizeof(m->yiaddr));
  memset(m->siaddr, 0, sizeof(m->siaddr));
  memset(m->giaddr, 0, sizeof(m->giaddr));
  memcpy(m->chaddr, s->mac_addr, s->mac_len);
  memset(&m->chaddr[s->mac_len], 0, sizeof(m->chaddr) - s->mac_len);
#ifndef UIP_CONF_DHCP_LIGHT
  memset(m->sname, 0, sizeof(m->sname));
  memset(m->file, 0, sizeof(m->file));
#endif

  memcpy(m->options, magic_cookie, sizeof(magic_cookie));
}
/*---------------------------------------------------------------------------*/
static void
send_discover(struct dhcpc_state *s)
{
  u8_t *end;
  struct dhcp_msg *m = (struct dhcp_msg *)uip_appdata;

  create_msg(s, m);

  end = add_msg_type(&m->options[4], DHCPDISCOVER);
  end = add_req_options(end);
  end = add_end(end);

  uip_send(uip_appdata, end - (u8_t *)uip_appdata);
}
/*---------------------------------------------------------------------------*/
static void
send_request(struct dhcpc_state *s)
{
  u8_t *end;
  struct dhcp_msg *m = (struct dhcp_msg *)uip_appdata;

  create_msg(s, m);

  end = add_msg_type(&m->options[4], DHCPREQUEST);
  end = add_server_id(s, end);
  end = add_req_ipaddr(s, end);
  end = add_end(end);

  uip_send(uip_appdata, end - (u8_t *)uip_appdata);
}
/*---------------------------------------------------------------------------*/
static u8_t
parse_options(struct dhcpc_state *s, u8_t *optptr, int len)
{
  u8_t *end = optptr + len;
  u8_t type = 0;

  while(optptr < end) {
    switch(*optptr) {
    case DHCP_OPTION_SUBNET_MASK:
      memcpy(s->netmask, optptr + 2, 4);
      break;
    case DHCP_OPTION_ROUTER:
      memcpy(s->default_router, optptr + 2, 4);
      break;
    case DHCP_OPTION_DNS_SERVER:
      memcpy(s->dnsaddr, optptr + 2, 4);
      break;
    case DHCP_OPTION_MSG_TYPE:
      type = *(optptr + 2);
      break;
    case DHCP_OPTION_SERVER_ID:
      memcpy(s->serverid, optptr + 2, 4);
      break;
    case DHCP_OPTION_LEASE_TIME:
      memcpy(s->lease_time, optptr + 2, 4);
      break;
    case DHCP_OPTION_END:
      return type;
    }

    optptr += optptr[1] + 2;
  }
  return type;
}
/*---------------------------------------------------------------------------*/
static u8_t
parse_msg(struct dhcpc_state *s)
{
  struct dhcp_msg *m = (struct dhcp_msg *)uip_appdata;

  if(m->op == DHCP_REPLY &&
    memcmp(m->xid, xid, sizeof(xid)) == 0 &&
    memcmp(m->chaddr, s->mac_addr, s->mac_len) == 0) {
    memcpy(s->ipaddr, m->yiaddr, 4);
    return parse_options(s, &m->options[4], uip_datalen());
  }
  return 0;
}
/*---------------------------------------------------------------------------*/
static
PT_THREAD(handle_dhcp(struct dhcpc_state *s))
{
  int ret;
  PT_BEGIN(&s->pt);

  if(s->state != STATE_REQUEST)
    PT_YIELD(&s->pt);

  /* try_again:*/
  s->state = STATE_SENDING;
  s->ticks = 5 * CLOCK_SECOND;

  do {
    printf("send_discover(%d)\n", s->timer);
    send_discover(s);
    timer_set(&s->timer, s->ticks);

    PT_WAIT_UNTIL(&s->pt, (ret = uip_newdata() ? 1 : (timer_expired(&s->timer) ? 2 : 0)) != 0);

    if((ret == 1) && parse_msg(s) == DHCPOFFER) {
      s->state = STATE_OFFER_RECEIVED;
      break;
    }
    if(ret != 2)
      continue;

    if(s->ticks < CLOCK_SECOND * 60) {
      s->ticks += CLOCK_SECOND;
    }
    timer_set(&s->timer, s->ticks);
  } while(s->state != STATE_OFFER_RECEIVED);

  s->ticks = CLOCK_SECOND;

  PT_YIELD(&s->pt);

  do {
    printf("send_request(%d)\n", s->timer);
    send_request(s);
    timer_set(&s->timer, s->ticks);

    PT_WAIT_UNTIL(&s->pt, (ret = uip_newdata() ? 1 : (timer_expired(&s->timer) ? 2 : 0)) != 0);

    if((ret == 1) && parse_msg(s) == DHCPACK) {
      s->state = STATE_CONFIG_RECEIVED;
      break;
    }
    if(ret != 2)
      continue;

    if(s->ticks <= CLOCK_SECOND * 60) {
      s->ticks += CLOCK_SECOND;
      timer_set(&s->timer, s->ticks);
    } else {
      PT_RESTART(&s->pt);
    }
  } while(s->state != STATE_CONFIG_RECEIVED);

#if 0
  printf("Got IP address %d.%d.%d.%d\n",
         uip_ipaddr1(s->ipaddr), uip_ipaddr2(s->ipaddr),
         uip_ipaddr3(s->ipaddr), uip_ipaddr4(s->ipaddr));
  printf("Got netmask %d.%d.%d.%d\n",
         uip_ipaddr1(s->netmask), uip_ipaddr2(s->netmask),
         uip_ipaddr3(s->netmask), uip_ipaddr4(s->netmask));
  printf("Got DNS server %d.%d.%d.%d\n",
         uip_ipaddr1(s->dnsaddr), uip_ipaddr2(s->dnsaddr),
         uip_ipaddr3(s->dnsaddr), uip_ipaddr4(s->dnsaddr));
  printf("Got default router %d.%d.%d.%d\n",
         uip_ipaddr1(s->default_router), uip_ipaddr2(s->default_router),
         uip_ipaddr3(s->default_router), uip_ipaddr4(s->default_router));
  printf("Lease expires in %ld seconds\n",
         ntohs(s->lease_time[0])*65536ul + ntohs(s->lease_time[1]));
#endif

  dhcpc_configured(s);

  /*  timer_stop(&s->timer);*/

  /*
   * PT_END restarts the thread so we do this instead. Eventually we
   * should reacquire expired leases here.
   */
  while(1) {
    PT_YIELD(&s->pt);
    if(s->state == STATE_INITIAL)
      PT_RESTART(&s->pt);
  }

  PT_END(&s->pt);
}
/*---------------------------------------------------------------------------*/
struct dhcpc_state *
dhcpc_init(const void *mac_addr, int mac_len)
{
  struct uip_udp_conn *conn;
  struct dhcpc_state *s;
  uip_ipaddr_t addr;

  uip_ipaddr(addr, 255,255,255,255);
  conn = uip_udp_new(&addr, HTONS(DHCPC_SERVER_PORT));
  if(conn != NULL) {
    s = &conn->appstate.parblk.dhcpc;
    s->conn = conn;
    s->mac_addr = mac_addr;
    s->mac_len  = mac_len;

    s->state = STATE_INITIAL;
    s->conn->appstate.udp_callback = dhcpc_appcall;

    uip_udp_bind(conn, HTONS(DHCPC_CLIENT_PORT));

    PT_INIT(&s->pt);

    return s;
  }

  return NULL;
}
/*---------------------------------------------------------------------------*/
void
dhcpc_appcall(struct uip_udp_conn *uip_udp_conn, int fncd, void *p_parblk)
{
  handle_dhcp((struct dhcpc_state *)p_parblk);
}
/*---------------------------------------------------------------------------*/
void
dhcpc_request(struct dhcpc_state *s)
{
  u16_t ipaddr[2];

  s->state = STATE_REQUEST;
  uip_ipaddr(ipaddr, 0,0,0,0);
  uip_sethostaddr(ipaddr);
  uip_udp_conn = s->conn;
  uip_process(UIP_UDP_TIMER);
}
/*---------------------------------------------------------------------------*/