// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed 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.
//#include "esp_common.h"
#include <stdlib.h>
#include <string.h>
#include "lwip/inet.h"
#include "lwip/err.h"
#include "lwip/pbuf.h"
#include "lwip/udp.h"
#include "lwip/mem.h"
#include "lwip/ip_addr.h"
#include "tcpip_adapter.h"

#include "apps/dhcpserver.h"
#include "apps/dhcpserver_options.h"

#if ESP_DHCP

#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 DHCPS_SERVER_PORT  67
#define DHCPS_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_INTERFACE_MTU 26
#define DHCP_OPTION_PERFORM_ROUTER_DISCOVERY 31
#define DHCP_OPTION_BROADCAST_ADDRESS 28
#define DHCP_OPTION_REQ_LIST     55
#define DHCP_OPTION_END         255

//#define USE_CLASS_B_NET 1
#define DHCPS_DEBUG          0
#define DHCPS_LOG printf

#define MAX_STATION_NUM CONFIG_LWIP_DHCPS_MAX_STATION_NUM

#define DHCPS_STATE_OFFER 1
#define DHCPS_STATE_DECLINE 2
#define DHCPS_STATE_ACK 3
#define DHCPS_STATE_NAK 4
#define DHCPS_STATE_IDLE 5
#define DHCPS_STATE_RELEASE 6

typedef struct _list_node {
	void *pnode;
	struct _list_node *pnext;
} list_node;

////////////////////////////////////////////////////////////////////////////////////

static const u32_t magic_cookie  = 0x63538263;

static struct udp_pcb *pcb_dhcps = NULL;
static ip4_addr_t  broadcast_dhcps;
static ip4_addr_t server_address;
static ip4_addr_t dns_server = {0};
static ip4_addr_t client_address;        //added
static ip4_addr_t client_address_plus;

static list_node *plist = NULL;
static bool renew = false;

static dhcps_lease_t dhcps_poll;
static dhcps_time_t dhcps_lease_time = DHCPS_LEASE_TIME_DEF;  //minute
static dhcps_offer_t dhcps_offer = 0xFF;
static dhcps_offer_t dhcps_dns = 0x00;
static dhcps_cb_t dhcps_cb;

/******************************************************************************
 * FunctionName : dhcps_option_info
 * Description  : get the DHCP message option info
 * Parameters   : op_id -- DHCP message option id
 *                opt_len -- DHCP message option length
 * Returns      : DHCP message option addr
*******************************************************************************/
void *dhcps_option_info(u8_t op_id, u32_t opt_len)
{
    void *option_arg = NULL;

    switch (op_id) {
        case IP_ADDRESS_LEASE_TIME:
            if (opt_len == sizeof(dhcps_time_t)) {
                option_arg = &dhcps_lease_time;
            }

            break;

        case REQUESTED_IP_ADDRESS:
            if (opt_len == sizeof(dhcps_lease_t)) {
                option_arg = &dhcps_poll;
            }

            break;

        case ROUTER_SOLICITATION_ADDRESS:
            if (opt_len == sizeof(dhcps_offer_t)) {
                option_arg = &dhcps_offer;
            }

            break;

        case DOMAIN_NAME_SERVER:
            if (opt_len == sizeof(dhcps_offer_t)) {
                option_arg = &dhcps_dns;
            }

            break;

        default:
            break;
    }

    return option_arg;
}

/******************************************************************************
 * FunctionName : dhcps_set_option_info
 * Description  : set the DHCP message option info
 * Parameters   : op_id -- DHCP message option id
 *                opt_info -- DHCP message option info
 *                opt_len -- DHCP message option length
 * Returns      : none
*******************************************************************************/
void dhcps_set_option_info(u8_t op_id, void *opt_info, u32_t opt_len)
{
    if (opt_info == NULL) {
        return;
    }
    switch (op_id) {
        case IP_ADDRESS_LEASE_TIME:
            if (opt_len == sizeof(dhcps_time_t)) {
                dhcps_lease_time = *(dhcps_time_t *)opt_info;
            }

            break;

        case REQUESTED_IP_ADDRESS:
            if (opt_len == sizeof(dhcps_lease_t)) {
                dhcps_poll = *(dhcps_lease_t *)opt_info;
            }

            break;

        case ROUTER_SOLICITATION_ADDRESS:
            if (opt_len == sizeof(dhcps_offer_t)) {
                dhcps_offer = *(dhcps_offer_t *)opt_info;
            }

            break;

        case DOMAIN_NAME_SERVER:
            if (opt_len == sizeof(dhcps_offer_t)) {
                dhcps_dns = *(dhcps_offer_t *)opt_info;
            }
            break;

        default:
            break;
    }
    return;
}

/******************************************************************************
 * FunctionName : node_insert_to_list
 * Description  : insert the node to the list
 * Parameters   : phead -- the head node of the list
 *                pinsert -- the insert node of the list
 * Returns      : none
*******************************************************************************/
static void node_insert_to_list(list_node **phead, list_node *pinsert)
{
    list_node *plist = NULL;
    struct dhcps_pool *pdhcps_pool = NULL;
    struct dhcps_pool *pdhcps_node = NULL;

    if (*phead == NULL) {
        *phead = pinsert;
    } else {
        plist = *phead;
        pdhcps_node = pinsert->pnode;
        pdhcps_pool = plist->pnode;

        if (pdhcps_node->ip.addr < pdhcps_pool->ip.addr) {
            pinsert->pnext = plist;
            *phead = pinsert;
        } else {
            while (plist->pnext != NULL) {
                pdhcps_pool = plist->pnext->pnode;

                if (pdhcps_node->ip.addr < pdhcps_pool->ip.addr) {
                    pinsert->pnext = plist->pnext;
                    plist->pnext = pinsert;
                    break;
                }

                plist = plist->pnext;
            }

            if (plist->pnext == NULL) {
                plist->pnext = pinsert;
            }
        }
    }

//	pinsert->pnext = NULL;
}

/******************************************************************************
 * FunctionName : node_delete_from_list
 * Description  : remove the node from list
 * Parameters   : phead -- the head node of the list
 *                pdelete -- the remove node of the list
 * Returns      : none
*******************************************************************************/
void node_remove_from_list(list_node **phead, list_node *pdelete)
{
    list_node *plist = NULL;

    plist = *phead;

    if (plist == NULL) {
        *phead = NULL;
    } else {
        if (plist == pdelete) {
            *phead = plist->pnext;
            pdelete->pnext = NULL;
        } else {
            while (plist != NULL) {
                if (plist->pnext == pdelete) {
                    plist->pnext = pdelete->pnext;
                    pdelete->pnext = NULL;
                }

                plist = plist->pnext;
            }
        }
    }
}

/******************************************************************************
 * FunctionName : add_msg_type
 * Description  : add TYPE option of DHCP message
 * Parameters   : optptr -- the addr of DHCP message option
 * Returns      : the addr of DHCP message option
*******************************************************************************/
static u8_t *add_msg_type(u8_t *optptr, u8_t type)
{
    *optptr++ = DHCP_OPTION_MSG_TYPE;
    *optptr++ = 1;
    *optptr++ = type;
    return optptr;
}

/******************************************************************************
 * FunctionName : add_offer_options
 * Description  : add OFFER option of DHCP message
 * Parameters   : optptr -- the addr of DHCP message option
 * Returns      : the addr of DHCP message option
*******************************************************************************/
static u8_t *add_offer_options(u8_t *optptr)
{
    ip4_addr_t ipadd;

    ipadd.addr = *((u32_t *) &server_address);

#ifdef USE_CLASS_B_NET
    *optptr++ = DHCP_OPTION_SUBNET_MASK;
    *optptr++ = 4;  //length
    *optptr++ = 255;
    *optptr++ = 240;
    *optptr++ = 0;
    *optptr++ = 0;
#else
    *optptr++ = DHCP_OPTION_SUBNET_MASK;
    *optptr++ = 4;
    *optptr++ = 255;
    *optptr++ = 255;
    *optptr++ = 255;
    *optptr++ = 0;
#endif

    *optptr++ = DHCP_OPTION_LEASE_TIME;
    *optptr++ = 4;
    *optptr++ = ((dhcps_lease_time * DHCPS_LEASE_UNIT) >> 24) & 0xFF;
    *optptr++ = ((dhcps_lease_time * DHCPS_LEASE_UNIT) >> 16) & 0xFF;
    *optptr++ = ((dhcps_lease_time * DHCPS_LEASE_UNIT) >> 8) & 0xFF;
    *optptr++ = ((dhcps_lease_time * DHCPS_LEASE_UNIT) >> 0) & 0xFF;

    *optptr++ = DHCP_OPTION_SERVER_ID;
    *optptr++ = 4;
    *optptr++ = ip4_addr1(&ipadd);
    *optptr++ = ip4_addr2(&ipadd);
    *optptr++ = ip4_addr3(&ipadd);
    *optptr++ = ip4_addr4(&ipadd);

    if (dhcps_router_enabled(dhcps_offer)) {
        tcpip_adapter_ip_info_t if_ip;
        //bzero(&if_ip, sizeof(struct ip_info));
        memset(&if_ip , 0x00, sizeof(tcpip_adapter_ip_info_t));

        tcpip_adapter_get_ip_info(ESP_IF_WIFI_AP, &if_ip);

        if (!ip4_addr_isany_val(if_ip.gw)) {
            *optptr++ = DHCP_OPTION_ROUTER;
            *optptr++ = 4;
            *optptr++ = ip4_addr1(&if_ip.gw);
            *optptr++ = ip4_addr2(&if_ip.gw);
            *optptr++ = ip4_addr3(&if_ip.gw);
            *optptr++ = ip4_addr4(&if_ip.gw);
        }
    }

    *optptr++ = DHCP_OPTION_DNS_SERVER;
    *optptr++ = 4;
    if (dhcps_dns_enabled(dhcps_dns)) {
        *optptr++ = ip4_addr1(&dns_server);
        *optptr++ = ip4_addr2(&dns_server);
        *optptr++ = ip4_addr3(&dns_server);
        *optptr++ = ip4_addr4(&dns_server);
    }else {
        *optptr++ = ip4_addr1(&ipadd);
        *optptr++ = ip4_addr2(&ipadd);
        *optptr++ = ip4_addr3(&ipadd);
        *optptr++ = ip4_addr4(&ipadd);
    }

#ifdef CLASS_B_NET
    *optptr++ = DHCP_OPTION_BROADCAST_ADDRESS;
    *optptr++ = 4;
    *optptr++ = ip4_addr1(&ipadd);
    *optptr++ = 255;
    *optptr++ = 255;
    *optptr++ = 255;
#else
    *optptr++ = DHCP_OPTION_BROADCAST_ADDRESS;
    *optptr++ = 4;
    *optptr++ = ip4_addr1(&ipadd);
    *optptr++ = ip4_addr2(&ipadd);
    *optptr++ = ip4_addr3(&ipadd);
    *optptr++ = 255;
#endif

    *optptr++ = DHCP_OPTION_INTERFACE_MTU;
    *optptr++ = 2;
    *optptr++ = 0x05;
    *optptr++ = 0xdc;

    *optptr++ = DHCP_OPTION_PERFORM_ROUTER_DISCOVERY;
    *optptr++ = 1;
    *optptr++ = 0x00;

    *optptr++ = 43;
    *optptr++ = 6;

    *optptr++ = 0x01;
    *optptr++ = 4;
    *optptr++ = 0x00;
    *optptr++ = 0x00;
    *optptr++ = 0x00;
    *optptr++ = 0x02;

    return optptr;
}

/******************************************************************************
 * FunctionName : add_end
 * Description  : add end option of DHCP message
 * Parameters   : optptr -- the addr of DHCP message option
 * Returns      : the addr of DHCP message option
*******************************************************************************/
static u8_t *add_end(u8_t *optptr)
{
    *optptr++ = DHCP_OPTION_END;
    return optptr;
}

/******************************************************************************
 * FunctionName : create_msg
 * Description  : create response message
 * Parameters   : m -- DHCP message info
 * Returns      : none
*******************************************************************************/
static void create_msg(struct dhcps_msg *m)
{
    ip4_addr_t client;


    client.addr = *((uint32_t *) &client_address);

    m->op = DHCP_REPLY;

    m->htype = DHCP_HTYPE_ETHERNET;

    m->hlen = 6;

    m->hops = 0;
//        os_memcpy((char *) xid, (char *) m->xid, sizeof(m->xid));
    m->secs = 0;
    m->flags = htons(BOOTP_BROADCAST);

    memcpy((char *) m->yiaddr, (char *) &client.addr, sizeof(m->yiaddr));

    memset((char *) m->ciaddr, 0, sizeof(m->ciaddr));

    memset((char *) m->siaddr, 0, sizeof(m->siaddr));

    memset((char *) m->giaddr, 0, sizeof(m->giaddr));

    memset((char *) m->sname, 0, sizeof(m->sname));

    memset((char *) m->file, 0, sizeof(m->file));

    memset((char *) m->options, 0, sizeof(m->options));

    u32_t magic_cookie_temp = magic_cookie;

    memcpy((char *) m->options, &magic_cookie_temp, sizeof(magic_cookie_temp));
}

struct pbuf * dhcps_pbuf_alloc(u16_t len)
{
    u16_t mlen = sizeof(struct dhcps_msg);

    if (len > mlen) {
#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: len=%d mlen=%d", len, mlen);
#endif
        mlen = len;
    }

    return pbuf_alloc(PBUF_TRANSPORT, mlen, PBUF_RAM);
}

/******************************************************************************
 * FunctionName : send_offer
 * Description  : DHCP message OFFER Response
 * Parameters   : m -- DHCP message info
 * Returns      : none
*******************************************************************************/
static void send_offer(struct dhcps_msg *m, u16_t len)
{
    u8_t *end;
    struct pbuf *p, *q;
    u8_t *data;
    u16_t cnt = 0;
    u16_t i;
    err_t SendOffer_err_t;
    create_msg(m);

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

    p = dhcps_pbuf_alloc(len);
#if DHCPS_DEBUG
    DHCPS_LOG("udhcp: send_offer>>p->ref = %d\n", p->ref);
#endif

    if (p != NULL) {

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: send_offer>>pbuf_alloc succeed\n");
        DHCPS_LOG("dhcps: send_offer>>p->tot_len = %d\n", p->tot_len);
        DHCPS_LOG("dhcps: send_offer>>p->len = %d\n", p->len);
#endif
        q = p;

        while (q != NULL) {
            data = (u8_t *)q->payload;

            for (i = 0; i < q->len; i++) {
                data[i] = ((u8_t *) m)[cnt++];
#if DHCPS_DEBUG
                DHCPS_LOG("%02x ", data[i]);

                if ((i + 1) % 16 == 0) {
                    DHCPS_LOG("\n");
                }

#endif
            }

            q = q->next;
        }
    } else {

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: send_offer>>pbuf_alloc failed\n");
#endif
        return;
    }

    ip_addr_t ip_temp = IPADDR4_INIT(0x0);
    ip4_addr_set(ip_2_ip4(&ip_temp), &broadcast_dhcps);
    SendOffer_err_t = udp_sendto(pcb_dhcps, p, &ip_temp, DHCPS_CLIENT_PORT);
#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: send_offer>>udp_sendto result %x\n", SendOffer_err_t);
#endif

    if (p->ref != 0) {
#if DHCPS_DEBUG
        DHCPS_LOG("udhcp: send_offer>>free pbuf\n");
#endif
        pbuf_free(p);
    }
}

/******************************************************************************
 * FunctionName : send_nak
 * Description  : DHCP message NACK Response
 * Parameters   : m -- DHCP message info
 * Returns      : none
*******************************************************************************/
static void send_nak(struct dhcps_msg *m, u16_t len)
{
    u8_t *end;
    struct pbuf *p, *q;
    u8_t *data;
    u16_t cnt = 0;
    u16_t i;
    err_t SendNak_err_t;
    create_msg(m);

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

    p = dhcps_pbuf_alloc(len);
#if DHCPS_DEBUG
    DHCPS_LOG("udhcp: send_nak>>p->ref = %d\n", p->ref);
#endif

    if (p != NULL) {

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: send_nak>>pbuf_alloc succeed\n");
        DHCPS_LOG("dhcps: send_nak>>p->tot_len = %d\n", p->tot_len);
        DHCPS_LOG("dhcps: send_nak>>p->len = %d\n", p->len);
#endif
        q = p;

        while (q != NULL) {
            data = (u8_t *)q->payload;

            for (i = 0; i < q->len; i++) {
                data[i] = ((u8_t *) m)[cnt++];
#if DHCPS_DEBUG
                DHCPS_LOG("%02x ", data[i]);

                if ((i + 1) % 16 == 0) {
                    DHCPS_LOG("\n");
                }

#endif
            }

            q = q->next;
        }
    } else {

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: send_nak>>pbuf_alloc failed\n");
#endif
        return;
    }

    ip_addr_t ip_temp = IPADDR4_INIT(0x0);
    ip4_addr_set(ip_2_ip4(&ip_temp), &broadcast_dhcps);
    SendNak_err_t = udp_sendto(pcb_dhcps, p, &ip_temp, DHCPS_CLIENT_PORT);
#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: send_nak>>udp_sendto result %x\n", SendNak_err_t);
#endif

    if (p->ref != 0) {
#if DHCPS_DEBUG
        DHCPS_LOG("udhcp: send_nak>>free pbuf\n");
#endif
        pbuf_free(p);
    }
}

/******************************************************************************
 * FunctionName : send_ack
 * Description  : DHCP message ACK Response
 * Parameters   : m -- DHCP message info
 * Returns      : none
*******************************************************************************/
static void send_ack(struct dhcps_msg *m, u16_t len)
{
    u8_t *end;
    struct pbuf *p, *q;
    u8_t *data;
    u16_t cnt = 0;
    u16_t i;
    err_t SendAck_err_t;
    create_msg(m);

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

    p = dhcps_pbuf_alloc(len);
#if DHCPS_DEBUG
    DHCPS_LOG("udhcp: send_ack>>p->ref = %d\n", p->ref);
#endif

    if (p != NULL) {

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: send_ack>>pbuf_alloc succeed\n");
        DHCPS_LOG("dhcps: send_ack>>p->tot_len = %d\n", p->tot_len);
        DHCPS_LOG("dhcps: send_ack>>p->len = %d\n", p->len);
#endif
        q = p;

        while (q != NULL) {
            data = (u8_t *)q->payload;

            for (i = 0; i < q->len; i++) {
                data[i] = ((u8_t *) m)[cnt++];
#if DHCPS_DEBUG
                DHCPS_LOG("%02x ", data[i]);

                if ((i + 1) % 16 == 0) {
                    DHCPS_LOG("\n");
                }

#endif
            }

            q = q->next;
        }
    } else {

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: send_ack>>pbuf_alloc failed\n");
#endif
        return;
    }

    ip_addr_t ip_temp = IPADDR4_INIT(0x0);
    ip4_addr_set(ip_2_ip4(&ip_temp), &broadcast_dhcps);
    SendAck_err_t = udp_sendto(pcb_dhcps, p, &ip_temp, DHCPS_CLIENT_PORT);
#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: send_ack>>udp_sendto result %x\n", SendAck_err_t);
#endif

    if (SendAck_err_t == ERR_OK) {
        dhcps_cb(m->yiaddr);
    }

    if (p->ref != 0) {
#if DHCPS_DEBUG
        DHCPS_LOG("udhcp: send_ack>>free pbuf\n");
#endif
        pbuf_free(p);
    }
}

/******************************************************************************
 * FunctionName : parse_options
 * Description  : parse DHCP message options
 * Parameters   : optptr -- DHCP message option info
 *                len -- DHCP message option length
 * Returns      : none
*******************************************************************************/
static u8_t parse_options(u8_t *optptr, s16_t len)
{
    ip4_addr_t client;
    bool is_dhcp_parse_end = false;
    struct dhcps_state s;

    client.addr = *((uint32_t *) &client_address);

    u8_t *end = optptr + len;
    u16_t type = 0;

    s.state = DHCPS_STATE_IDLE;

    while (optptr < end) {
#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: (s16_t)*optptr = %d\n", (s16_t)*optptr);
#endif

        switch ((s16_t) *optptr) {

            case DHCP_OPTION_MSG_TYPE:	//53
                type = *(optptr + 2);
                break;

            case DHCP_OPTION_REQ_IPADDR://50
                if (memcmp((char *) &client.addr, (char *) optptr + 2, 4) == 0) {
#if DHCPS_DEBUG
                    DHCPS_LOG("dhcps: DHCP_OPTION_REQ_IPADDR = 0 ok\n");
#endif
                    s.state = DHCPS_STATE_ACK;
                } else {
#if DHCPS_DEBUG
                    DHCPS_LOG("dhcps: DHCP_OPTION_REQ_IPADDR != 0 err\n");
#endif
                    s.state = DHCPS_STATE_NAK;
                }

                break;

            case DHCP_OPTION_END: {
                is_dhcp_parse_end = true;
            }
            break;
        }

        if (is_dhcp_parse_end) {
            break;
        }

        optptr += optptr[1] + 2;
    }

    switch (type) {

        case DHCPDISCOVER://1
            s.state = DHCPS_STATE_OFFER;
#if DHCPS_DEBUG
            DHCPS_LOG("dhcps: DHCPD_STATE_OFFER\n");
#endif
            break;

        case DHCPREQUEST://3
            if (!(s.state == DHCPS_STATE_ACK || s.state == DHCPS_STATE_NAK)) {
                if (renew == true) {
                    s.state = DHCPS_STATE_ACK;
                } else {
                    s.state = DHCPS_STATE_NAK;
                }

#if DHCPS_DEBUG
                DHCPS_LOG("dhcps: DHCPD_STATE_NAK\n");
#endif
            }

            break;

        case DHCPDECLINE://4
            s.state = DHCPS_STATE_IDLE;
#if DHCPS_DEBUG
            DHCPS_LOG("dhcps: DHCPD_STATE_IDLE\n");
#endif
            break;

        case DHCPRELEASE://7
            s.state = DHCPS_STATE_RELEASE;
#if DHCPS_DEBUG
            DHCPS_LOG("dhcps: DHCPD_STATE_IDLE\n");
#endif
            break;
    }

#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: return s.state = %d\n", s.state);
#endif
    return s.state;
}

/******************************************************************************
 * FunctionName : parse_msg
 * Description  : parse DHCP message from netif
 * Parameters   : m -- DHCP message info
 *                len -- DHCP message length
 * Returns      : DHCP message type
*******************************************************************************/
static s16_t parse_msg(struct dhcps_msg *m, u16_t len)
{
    u32_t lease_timer = (dhcps_lease_time * DHCPS_LEASE_UNIT)/DHCPS_COARSE_TIMER_SECS;

    if (memcmp((char *)m->options, &magic_cookie, sizeof(magic_cookie)) == 0) {
#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: len = %d\n", len);
#endif
        ip4_addr_t addr_tmp;

        struct dhcps_pool *pdhcps_pool = NULL;
        list_node *pnode = NULL;
        list_node *pback_node = NULL;
        ip4_addr_t first_address;
        bool flag = false;

        first_address.addr = dhcps_poll.start_ip.addr;
        client_address.addr = client_address_plus.addr;
        renew = false;

        if (plist != NULL) {
            for (pback_node = plist; pback_node != NULL; pback_node = pback_node->pnext) {
                pdhcps_pool = pback_node->pnode;

                if (memcmp(pdhcps_pool->mac, m->chaddr, sizeof(pdhcps_pool->mac)) == 0) {
                    if (memcmp(&pdhcps_pool->ip.addr, m->ciaddr, sizeof(pdhcps_pool->ip.addr)) == 0) {
                        renew = true;
                    }

                    client_address.addr = pdhcps_pool->ip.addr;
                    pdhcps_pool->lease_timer = lease_timer;
                    pnode = pback_node;
                    goto POOL_CHECK;
                } else if (pdhcps_pool->ip.addr == client_address_plus.addr) {
                    addr_tmp.addr = htonl(client_address_plus.addr);
                    addr_tmp.addr++;
                    client_address_plus.addr = htonl(addr_tmp.addr);
                    client_address.addr = client_address_plus.addr;
                }

                if (flag == false) { // search the fisrt unused ip
                    if (first_address.addr < pdhcps_pool->ip.addr) {
                        flag = true;
                    } else {
                        addr_tmp.addr = htonl(first_address.addr);
                        addr_tmp.addr++;
                        first_address.addr = htonl(addr_tmp.addr);
                    }
                }
            }
        } else {
            client_address.addr = dhcps_poll.start_ip.addr;
        }

        if (client_address_plus.addr > dhcps_poll.end_ip.addr) {
            client_address.addr = first_address.addr;
        }

        if (client_address.addr > dhcps_poll.end_ip.addr) {
            client_address_plus.addr = dhcps_poll.start_ip.addr;
            pdhcps_pool = NULL;
            pnode = NULL;
        } else {
            pdhcps_pool = (struct dhcps_pool *)mem_malloc(sizeof(struct dhcps_pool));
            memset(pdhcps_pool , 0x00 , sizeof(struct dhcps_pool));

            pdhcps_pool->ip.addr = client_address.addr;
            memcpy(pdhcps_pool->mac, m->chaddr, sizeof(pdhcps_pool->mac));
            pdhcps_pool->lease_timer = lease_timer;
            pnode = (list_node *)mem_malloc(sizeof(list_node));
            memset(pnode , 0x00 , sizeof(list_node));

            pnode->pnode = pdhcps_pool;
            pnode->pnext = NULL;
            node_insert_to_list(&plist, pnode);

            if (client_address.addr == dhcps_poll.end_ip.addr) {
                client_address_plus.addr = dhcps_poll.start_ip.addr;
            } else {
                addr_tmp.addr = htonl(client_address.addr);
                addr_tmp.addr++;
                client_address_plus.addr = htonl(addr_tmp.addr);
            }
        }

POOL_CHECK:

        if ((client_address.addr > dhcps_poll.end_ip.addr) || (ip4_addr_isany(&client_address))) {
            if (pnode != NULL) {
                node_remove_from_list(&plist, pnode);
                free(pnode);
                pnode = NULL;
            }

            if (pdhcps_pool != NULL) {
                free(pdhcps_pool);
                pdhcps_pool = NULL;
            }

            return 4;
        }

        s16_t ret = parse_options(&m->options[4], len);;

        if (ret == DHCPS_STATE_RELEASE) {
            if (pnode != NULL) {
                node_remove_from_list(&plist, pnode);
                free(pnode);
                pnode = NULL;
            }

            if (pdhcps_pool != NULL) {
                free(pdhcps_pool);
                pdhcps_pool = NULL;
            }

            memset(&client_address, 0x0, sizeof(client_address));
        }

#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: xid changed\n");
        DHCPS_LOG("dhcps: client_address.addr = %x\n", client_address.addr);
#endif
        return ret;
    }

    return 0;
}

/******************************************************************************
 * FunctionName : handle_dhcp
 * Description  : If an incoming DHCP message is in response to us, then trigger the state machine
 * Parameters   : arg -- arg user supplied argument (udp_pcb.recv_arg)
 * 				  pcb -- the udp_pcb which received data
 * 			      p -- the packet buffer that was received
 * 				  addr -- the remote IP address from which the packet was received
 * 				  port -- the remote port from which the packet was received
 * Returns      : none
*******************************************************************************/
static void handle_dhcp(void *arg,
                        struct udp_pcb *pcb,
                        struct pbuf *p,
                        const ip_addr_t *addr,
                        u16_t port)
{
    struct dhcps_msg *pmsg_dhcps = NULL;
    s16_t tlen, malloc_len;
    u16_t i;
    u16_t dhcps_msg_cnt = 0;
    u8_t *p_dhcps_msg = NULL;
    u8_t *data;

#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: handle_dhcp-> receive a packet\n");
#endif

    if (p == NULL) {
        return;
    }

    malloc_len = sizeof(struct dhcps_msg);
#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: handle_dhcp malloc_len=%d rx_len=%d", malloc_len, p->tot_len);
#endif
    if (malloc_len < p->tot_len) {
        malloc_len = p->tot_len;
    }

    pmsg_dhcps = (struct dhcps_msg *)mem_malloc(malloc_len);
    if (NULL == pmsg_dhcps) {
        pbuf_free(p);
        return;
    }

    memset(pmsg_dhcps , 0x00 , malloc_len);
    p_dhcps_msg = (u8_t *)pmsg_dhcps;
    tlen = p->tot_len;
    data = p->payload;

#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: handle_dhcp-> p->tot_len = %d\n", tlen);
    DHCPS_LOG("dhcps: handle_dhcp-> p->len = %d\n", p->len);
#endif

    for (i = 0; i < p->len; i++) {
        p_dhcps_msg[dhcps_msg_cnt++] = data[i];
#if DHCPS_DEBUG
        DHCPS_LOG("%02x ", data[i]);

        if ((i + 1) % 16 == 0) {
            DHCPS_LOG("\n");
        }

#endif
    }

    if (p->next != NULL) {
#if DHCPS_DEBUG
        DHCPS_LOG("dhcps: handle_dhcp-> p->next != NULL\n");
        DHCPS_LOG("dhcps: handle_dhcp-> p->next->tot_len = %d\n", p->next->tot_len);
        DHCPS_LOG("dhcps: handle_dhcp-> p->next->len = %d\n", p->next->len);
#endif

        data = p->next->payload;

        for (i = 0; i < p->next->len; i++) {
            p_dhcps_msg[dhcps_msg_cnt++] = data[i];
#if DHCPS_DEBUG
            DHCPS_LOG("%02x ", data[i]);

            if ((i + 1) % 16 == 0) {
                DHCPS_LOG("\n");
            }

#endif
        }
    }

#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: handle_dhcp-> parse_msg(p)\n");
#endif

    switch (parse_msg(pmsg_dhcps, tlen - 240)) {
        case DHCPS_STATE_OFFER://1
#if DHCPS_DEBUG
            DHCPS_LOG("dhcps: handle_dhcp-> DHCPD_STATE_OFFER\n");
#endif
            send_offer(pmsg_dhcps, malloc_len);
            break;

        case DHCPS_STATE_ACK://3
#if DHCPS_DEBUG
            DHCPS_LOG("dhcps: handle_dhcp-> DHCPD_STATE_ACK\n");
#endif
            send_ack(pmsg_dhcps, malloc_len);
            break;

        case DHCPS_STATE_NAK://4
#if DHCPS_DEBUG
            DHCPS_LOG("dhcps: handle_dhcp-> DHCPD_STATE_NAK\n");
#endif
            send_nak(pmsg_dhcps, malloc_len);
            break;

        default :
            break;
    }

#if DHCPS_DEBUG
    DHCPS_LOG("dhcps: handle_dhcp-> pbuf_free(p)\n");
#endif
    pbuf_free(p);
    free(pmsg_dhcps);
    pmsg_dhcps = NULL;
}

/******************************************************************************
 * FunctionName : dhcps_poll_set
 * Description  : set ip poll from start to end for station
 * Parameters   : ip -- The current ip addr
 * Returns      : none
*******************************************************************************/
static void dhcps_poll_set(u32_t ip)
{
    u32_t softap_ip = 0, local_ip = 0;
    u32_t start_ip = 0;
    u32_t end_ip = 0;

    if (dhcps_poll.enable == true) {
        softap_ip = htonl(ip);
        start_ip = htonl(dhcps_poll.start_ip.addr);
        end_ip = htonl(dhcps_poll.end_ip.addr);

        /*config ip information can't contain local ip*/
        if ((start_ip <= softap_ip) && (softap_ip <= end_ip)) {
            dhcps_poll.enable = false;
        } else {
            /*config ip information must be in the same segment as the local ip*/
            softap_ip >>= 8;

            if (((start_ip >> 8 != softap_ip) || (end_ip >> 8 != softap_ip))
                    || (end_ip - start_ip > DHCPS_MAX_LEASE)) {
                dhcps_poll.enable = false;
            }
        }
    }

    if (dhcps_poll.enable == false) {
        local_ip = softap_ip = htonl(ip);
        softap_ip &= 0xFFFFFF00;
        local_ip &= 0xFF;

        if (local_ip >= 0x80) {
            local_ip -= DHCPS_MAX_LEASE;
        } else {
            local_ip ++;
        }

        bzero(&dhcps_poll, sizeof(dhcps_poll));
        dhcps_poll.start_ip.addr = softap_ip | local_ip;
        dhcps_poll.end_ip.addr = softap_ip | (local_ip + DHCPS_MAX_LEASE - 1);
        dhcps_poll.start_ip.addr = htonl(dhcps_poll.start_ip.addr);
        dhcps_poll.end_ip.addr = htonl(dhcps_poll.end_ip.addr);
    }

}


/******************************************************************************
 * FunctionName : dhcps_set_new_lease_cb
 * Description  : set callback for dhcp server when it assign an IP 
 *                to the connected dhcp client
 * Parameters   : cb -- callback for dhcp server
 * Returns      : none
*******************************************************************************/
void dhcps_set_new_lease_cb(dhcps_cb_t cb)
{
    dhcps_cb = cb;
}

/******************************************************************************
 * FunctionName : dhcps_start
 * Description  : start dhcp server function
 * Parameters   : netif -- The current netif addr
 *              : info  -- The current ip info
 * Returns      : none
*******************************************************************************/
void dhcps_start(struct netif *netif, ip4_addr_t ip)
{
    struct netif *apnetif = netif;

    if (apnetif->dhcps_pcb != NULL) {
        udp_remove(apnetif->dhcps_pcb);
    }

    pcb_dhcps = udp_new();

    if (pcb_dhcps == NULL || ip4_addr_isany_val(ip)) {
        printf("dhcps_start(): could not obtain pcb\n");
    }

    apnetif->dhcps_pcb = pcb_dhcps;

    IP4_ADDR(&broadcast_dhcps, 255, 255, 255, 255);

    server_address.addr = ip.addr;
    dhcps_poll_set(server_address.addr);

    client_address_plus.addr = dhcps_poll.start_ip.addr;

    udp_bind(pcb_dhcps, &netif->ip_addr, DHCPS_SERVER_PORT);
    udp_recv(pcb_dhcps, handle_dhcp, NULL);
#if DHCPS_DEBUG
    DHCPS_LOG("dhcps:dhcps_start->udp_recv function Set a receive callback handle_dhcp for UDP_PCB pcb_dhcps\n");
#endif

}

/******************************************************************************
 * FunctionName : dhcps_stop
 * Description  : stop dhcp server function
 * Parameters   : netif -- The current netif addr
 * Returns      : none
*******************************************************************************/
void dhcps_stop(struct netif *netif)
{
    struct netif *apnetif = netif;

    if (apnetif == NULL) {
        printf("dhcps_stop: apnetif == NULL\n");
        return;
    }

    if (apnetif->dhcps_pcb != NULL) {
        udp_disconnect(apnetif->dhcps_pcb);
        udp_remove(apnetif->dhcps_pcb);
        apnetif->dhcps_pcb = NULL;
    }

    list_node *pnode = NULL;
    list_node *pback_node = NULL;
    pnode = plist;

    while (pnode != NULL) {
        pback_node = pnode;
        pnode = pback_node->pnext;
        node_remove_from_list(&plist, pback_node);
        free(pback_node->pnode);
        pback_node->pnode = NULL;
        free(pback_node);
        pback_node = NULL;
    }
}

/******************************************************************************
 * FunctionName : kill_oldest_dhcps_pool
 * Description  : remove the oldest node from list
 * Parameters   : none
 * Returns      : none
*******************************************************************************/
static void kill_oldest_dhcps_pool(void)
{
    list_node *pre = NULL, *p = NULL;
    list_node *minpre = NULL, *minp = NULL;
    struct dhcps_pool *pdhcps_pool = NULL, *pmin_pool = NULL;
    pre = plist;
    p = pre->pnext;
    minpre = pre;
    minp = p;

    while (p != NULL) {
        pdhcps_pool = p->pnode;
        pmin_pool = minp->pnode;

        if (pdhcps_pool->lease_timer < pmin_pool->lease_timer) {
            minp = p;
            minpre = pre;
        }

        pre = p;
        p = p->pnext;
    }

    minpre->pnext = minp->pnext;
    free(minp->pnode);
    minp->pnode = NULL;
    free(minp);
    minp = NULL;
}

/******************************************************************************
 * FunctionName : dhcps_coarse_tmr
 * Description  : the lease time count
 * Parameters   : none
 * Returns      : none
*******************************************************************************/
void dhcps_coarse_tmr(void)
{
    u8_t num_dhcps_pool = 0;
    list_node *pback_node = NULL;
    list_node *pnode = NULL;
    struct dhcps_pool *pdhcps_pool = NULL;
    pnode = plist;

    while (pnode != NULL) {
        pdhcps_pool = pnode->pnode;
        pdhcps_pool->lease_timer --;

        if (pdhcps_pool->lease_timer == 0) {
            pback_node = pnode;
            pnode = pback_node->pnext;
            node_remove_from_list(&plist, pback_node);
            free(pback_node->pnode);
            pback_node->pnode = NULL;
            free(pback_node);
            pback_node = NULL;
        } else {
            pnode = pnode ->pnext;
            num_dhcps_pool ++;
        }
    }

    if (num_dhcps_pool > MAX_STATION_NUM) {
        kill_oldest_dhcps_pool();
    }
}

/******************************************************************************
 * FunctionName : dhcp_search_ip_on_mac
 * Description  : Search ip address based on mac address
 * Parameters   : mac -- The MAC addr
 *				  ip  -- The IP info
 * Returns      : true or false
*******************************************************************************/
bool dhcp_search_ip_on_mac(u8_t *mac, ip4_addr_t *ip)
{
    struct dhcps_pool *pdhcps_pool = NULL;
    list_node *pback_node = NULL;
    bool ret = false;

    for (pback_node = plist; pback_node != NULL; pback_node = pback_node->pnext) {
        pdhcps_pool = pback_node->pnode;

        if (memcmp(pdhcps_pool->mac, mac, sizeof(pdhcps_pool->mac)) == 0) {
            memcpy(&ip->addr, &pdhcps_pool->ip.addr, sizeof(pdhcps_pool->ip.addr));
            ret = true;
            break;
        }
    }

    return ret;
}

/******************************************************************************
 * FunctionName : dhcps_dns_setserver
 * Description  : set DNS server address for dhcpserver
 * Parameters   : dnsserver -- The DNS server address
 * Returns      : none
*******************************************************************************/
void
dhcps_dns_setserver(const ip_addr_t *dnsserver)
{
    if (dnsserver != NULL) {
        dns_server = *(ip_2_ip4(dnsserver));
    } else {
        dns_server = *(ip_2_ip4(IP_ADDR_ANY));
    } 
}

/******************************************************************************
 * FunctionName : dhcps_dns_getserver
 * Description  : get DNS server address for dhcpserver
 * Parameters   : none
 * Returns      : ip4_addr_t
*******************************************************************************/
ip4_addr_t 
dhcps_dns_getserver()
{
    return dns_server;
}
#endif