/* libdhcp/dhcp.c - A DHCP client
 *
 * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
 * SPDX-Licence-Identifier: AGPL-3.0-or-later
 *
 * -----------------------------------------------------------------------------
 * https://github.com/Wiznet/ioLibrary_Driver/blob/b981401e7f3d07015619adf44c13998e13e777f9/Internet/DHCP/dhcp.c
 *
 * Copyright (c)  2013, WIZnet Co., LTD.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the <ORGANIZATION> 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 COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
 *
 * SPDX-Licence-Identifier: BSD-3-Clause
 *
 * -----------------------------------------------------------------------------
 * https://github.com/Wiznet/ioLibrary_Driver/blob/b981401e7f3d07015619adf44c13998e13e777f9/license.txt
 *
 * Copyright (c) 2014 WIZnet Co.,Ltd.
 * Copyright (c) WIZnet ioLibrary Project.
 * All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * SPDX-Licence-Identifier: MIT
 */

#include <string.h>

#include <libmisc/endian.h>
#include <libdhcp/dhcp.h>

/* If you want to display debug & processing message, Define _DHCP_DEBUG_ in dhcp.h */

#ifdef _DHCP_DEBUG_
#	include <stdio.h>
#	define debugf(fmt, ...) printf("> " fmt "\n" __VA_OPT__(,) __VA_ARGS__)
#else
#	define debugf(fmt, ...) ((void)0)
#endif

/* DHCP state machine. */
#define STATE_DHCP_INIT          0        ///< Initialize
#define STATE_DHCP_DISCOVER      1        ///< send DISCOVER and wait OFFER
#define STATE_DHCP_REQUEST       2        ///< send REQEUST and wait ACK or NACK
#define STATE_DHCP_LEASED        3        ///< ReceiveD ACK and IP leased
#define STATE_DHCP_REREQUEST     4        ///< send REQUEST for maintaining leased IP
#define STATE_DHCP_RELEASE       5        ///< No use
#define STATE_DHCP_STOP          6        ///< Stop processing DHCP

#define DHCP_FLAGSBROADCAST      0x8000   ///< The broadcast value of flags in @ref RIP_MSG
#define DHCP_FLAGSUNICAST        0x0000   ///< The unicast   value of flags in @ref RIP_MSG


/**
 * https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml#message-type-53
 */
#define DHCP_MSGTYP_DISCOVER     1
#define DHCP_MSGTYP_OFFER        2
#define DHCP_MSGTYP_REQUEST      3
#define DHCP_MSGTYP_DECLINE      4
#define DHCP_MSGTYP_ACK          5
#define DHCP_MSGTYP_NAK          6
#define DHCP_MSGTYP_RELEASE      7
#define DHCP_MSGTYP_INFORM       8


#define DHCP_HOPS                0        ///< Used in hops of @ref RIP_MSG
#define DHCP_SECS                0        ///< Used in secs of @ref RIP_MSG

#define INFINITE_LEASETIME       0xffffffff	///< Infinite lease time

#ifndef CONFIG_DHCP_OPT_SIZE
#	define CONFIG_DHCP_OPT_SIZE                 312
#endif

/**
 * https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml
 */
#define DHCP_OPT_PAD               ((uint8_t)  0) /* RFC2132: length: 0; meaning: None */
#define DHCP_OPT_SUBNET_MASK       ((uint8_t)  1) /* RFC2132: length: 4; meaning: Subnet Mask Value */
#define DHCP_OPT_TIME_OFFSET       ((uint8_t)  2) /* RFC2132: length: 4; meaning: Time Offset in Seconds from UTC (note: deprecated by 100 and 101 */
#define DHCP_OPT_ROUTER            ((uint8_t)  3) /* RFC2132: length: N; meaning: N/4 Router addresses */
#define DHCP_OPT_TIME_SERVER       ((uint8_t)  4) /* RFC2132: length: N; meaning: N/4 Timeserver addresses */
#define DHCP_OPT_NAME_SERVER       ((uint8_t)  5) /* RFC2132: length: N; meaning: N/4 IEN-116 Server addresses */
#define DHCP_OPT_DOMAIN_SERVER     ((uint8_t)  6) /* RFC2132: length: N; meaning: N/4 DNS Server addresses */
#define DHCP_OPT_LOG_SERVER        ((uint8_t)  7) /* RFC2132: length: N; meaning: N/4 Logging Server addresses */
#define DHCP_OPT_QUOTES_SERVER     ((uint8_t)  8) /* RFC2132: length: N; meaning: N/4 Quotes Server addresses */
#define DHCP_OPT_LPR_SERVER        ((uint8_t)  9) /* RFC2132: length: N; meaning: N/4 Printer Server addresses */
#define DHCP_OPT_IMPRESS_SERVER    ((uint8_t) 10) /* RFC2132: length: N; meaning: N/4 Impress Server addresses */
#define DHCP_OPT_RLP_SERVER        ((uint8_t) 11) /* RFC2132: length: N; meaning: N/4 RLP Server addresses */
#define DHCP_OPT_HOSTNAME          ((uint8_t) 12) /* RFC2132: length: N; meaning: Hostname string */
#define DHCP_OPT_BOOT_FILE_SIZE    ((uint8_t) 13) /* RFC2132: length: 2; meaning: Size of boot file in 512 byte chunks */
#define DHCP_OPT_MERIT_DUMP_FILE   ((uint8_t) 14) /* RFC2132: length: N; meaning: Client to dump and name the file to dump it to */
#define DHCP_OPT_DOMAIN_NAME       ((uint8_t) 15) /* RFC2132: length: N; meaning: The DNS domain name of the client */
#define DHCP_OPT_SWAP_SERVER       ((uint8_t) 16) /* RFC2132: length: N; meaning: Swap Server address */
#define DHCP_OPT_ROOT_PATH         ((uint8_t) 17) /* RFC2132: length: N; meaning: Path name for root disk */
#define DHCP_OPT_EXTENSION_FILE    ((uint8_t) 18) /* RFC2132: length: N; meaning: Path name for more BOOTP info */
#define DHCP_OPT_FORWARD_ONOFF     ((uint8_t) 19) /* RFC2132: length: 1; meaning: Enable/Disable IP Forwarding */
#define DHCP_OPT_SRCRTE_ONOFF      ((uint8_t) 20) /* RFC2132: length: 1; meaning: Enable/Disable Source Routing */
#define DHCP_OPT_POLICY_FILTER     ((uint8_t) 21) /* RFC2132: length: N; meaning: Routing Policy Filters */
#define DHCP_OPT_MAX_DG_ASSEMBLY   ((uint8_t) 22) /* RFC2132: length: 2; meaning: Max Datagram Reassembly Size */
#define DHCP_OPT_DEFAULT_IP_TTL    ((uint8_t) 23) /* RFC2132: length: 1; meaning: Default IP Time to Live */
#define DHCP_OPT_MTU_TIMEOUT       ((uint8_t) 24) /* RFC2132: length: 4; meaning: Path MTU Aging Timeout */
#define DHCP_OPT_MTU_PLATEAU       ((uint8_t) 25) /* RFC2132: length: N; meaning: Path MTU Plateau Table */
#define DHCP_OPT_MTU_INTERFACE     ((uint8_t) 26) /* RFC2132: length: 2; meaning: Interface MTU Size */
#define DHCP_OPT_MTU_SUBNET        ((uint8_t) 27) /* RFC2132: length: 1; meaning: All Subnets are Local */
#define DHCP_OPT_BROADCAST_ADDRESS ((uint8_t) 28) /* RFC2132: length: 4; meaning: Broadcast Address */
#define DHCP_OPT_MASK_DISCOVERY    ((uint8_t) 29) /* RFC2132: length: 1; meaning: Perform Mask Discovery */
#define DHCP_OPT_MASK_SUPPLIER     ((uint8_t) 30) /* RFC2132: length: 1; meaning: Provide Mask to Others */
#define DHCP_OPT_ROUTER_DISCOVERY  ((uint8_t) 31) /* RFC2132: length: 1; meaning: Perform Router Discovery */
#define DHCP_OPT_ROUTER_REQUEST    ((uint8_t) 32) /* RFC2132: length: 4; meaning: Router Solicitation Address */
#define DHCP_OPT_STATIC_ROUTE      ((uint8_t) 33) /* RFC2132: length: N; meaning: Static Routing Table */
#define DHCP_OPT_TRAILERS          ((uint8_t) 34) /* RFC2132: length: 1; meaning: Trailer Encapsulation */
#define DHCP_OPT_ARP_TIMEOUT       ((uint8_t) 35) /* RFC2132: length: 4; meaning: ARP Cache Timeout */
#define DHCP_OPT_ETHERNET          ((uint8_t) 36) /* RFC2132: length: 1; meaning: Ethernet Encapsulation */
#define DHCP_OPT_DEFAULT_TCP_TTL   ((uint8_t) 37) /* RFC2132: length: 1; meaning: Default TCP Time to Live */
#define DHCP_OPT_KEEPALIVE_TIME    ((uint8_t) 38) /* RFC2132: length: 4; meaning: TCP Keepalive Interval */
#define DHCP_OPT_KEEPALIVE_DATA    ((uint8_t) 39) /* RFC2132: length: 1; meaning: TCP Keepalive Garbage */
#define DHCP_OPT_NIS_DOMAIN        ((uint8_t) 40) /* RFC2132: length: N; meaning: NIS Domain Name */
#define DHCP_OPT_NIS_SERVERS       ((uint8_t) 41) /* RFC2132: length: N; meaning: NIS Server Addresses */
#define DHCP_OPT_NTP_SERVERS       ((uint8_t) 42) /* RFC2132: length: N; meaning: NTP Server Addresses */
#define DHCP_OPT_VENDOR_SPECIFIC   ((uint8_t) 43) /* RFC2132: length: N; meaning: Vendor Specific Information */
#define DHCP_OPT_NETBIOS_NAME_SRV  ((uint8_t) 44) /* RFC2132: length: N; meaning: NETBIOS Name Servers */
#define DHCP_OPT_NETBIOS_DIST_SRV  ((uint8_t) 45) /* RFC2132: length: N; meaning: NETBIOS Datagram Distribution */
#define DHCP_OPT_NETBIOS_NODE_TYPE ((uint8_t) 46) /* RFC2132: length: 1; meaning: NETBIOS Node Type */
#define DHCP_OPT_NETBIOS_SCOPE     ((uint8_t) 47) /* RFC2132: length: N; meaning: NETBIOS Scope */
#define DHCP_OPT_X_WINDOW_FONT     ((uint8_t) 48) /* RFC2132: length: N; meaning: X Window Font Server */
#define DHCP_OPT_X_WINDOW_MANAGER  ((uint8_t) 49) /* RFC2132: length: N; meaning: X Window Display Manager */
#define DHCP_OPT_ADDRESS_REQUEST   ((uint8_t) 50) /* RFC2132: length: 4; meaning: Requested IP Address */
#define DHCP_OPT_ADDRESS_TIME      ((uint8_t) 51) /* RFC2132: length: 4; meaning: IP Address Lease Time */
#define DHCP_OPT_OVERLOAD          ((uint8_t) 52) /* RFC2132: length: 1; meaning: Overload "sname" or "file */
#define DHCP_OPT_DHCP_MSG_TYPE     ((uint8_t) 53) /* RFC2132: length: 1; meaning: DHCP Message Type */
#define DHCP_OPT_DHCP_SERVER_ID    ((uint8_t) 54) /* RFC2132: length: 4; meaning: DHCP Server Identification */
#define DHCP_OPT_PARAMETER_LIST    ((uint8_t) 55) /* RFC2132: length: N; meaning: Parameter Request List */
#define DHCP_OPT_DHCP_MESSAGE      ((uint8_t) 56) /* RFC2132: length: N; meaning: DHCP Error Message */
#define DHCP_OPT_DHCP_MAX_MSG_SIZE ((uint8_t) 57) /* RFC2132: length: 2; meaning: DHCP Maximum Message Size */
#define DHCP_OPT_RENEWAL_TIME      ((uint8_t) 58) /* RFC2132: length: 4; meaning: DHCP Renewal (T1) Time */
#define DHCP_OPT_REBINDING_TIME    ((uint8_t) 59) /* RFC2132: length: 4; meaning: DHCP Rebinding (T2) Time */
#define DHCP_OPT_CLASS_ID          ((uint8_t) 60) /* RFC2132: length: N; meaning: Class Identifier */
#define DHCP_OPT_CLIENT_ID         ((uint8_t) 61) /* RFC2132: length: N; meaning: Client Identifier */
#define DHCP_OPT_END               ((uint8_t)255) /* RFC2132: length: 0; meaning: None */

/**
 * DHCP message.  See RFC 2131, figure 1 (page 9).
 */
struct dhcp_msg {
	uint8_t                 op;         /* DHCP_OP_{x} */
	uint8_t                 htype;      /* DHCP_HTYPE_{x} */
	uint8_t                 hlen;       /* length of ->chaddr (`sizeof(struct net_eth_addr)`) */
	uint8_t                 hops;       /* DHCP_HOPS */

	uint32be_t              xid;        /* `global_xid`; this increase one every DHCP transaction */

	uint16be_t              secs;       /* DHCP_SECS */
	uint16be_t              flags;      /* DHCP_FLAGSBROADCAST or @ref DHCP_FLAGSUNICAST */

	struct net_ip4_addr     ciaddr;     /* Request IP to DHCP sever */
	struct net_ip4_addr     yiaddr;     /* Offered IP from DHCP server */
	struct net_ip4_addr     siaddr;     /* next-server IP address (not used) */
	struct net_ip4_addr     giaddr;     /* relay-agent IP address (not used) */
	uint8_t                 chaddr[16]; /* client hardware (MAC) address */
	uint8_t                 sname[64];  /* server name (not used) */
	uint8_t                 file[128];  /* boot file name (not used) */

	uint8_t                 options[CONFIG_DHCP_OPT_SIZE];
};
static_assert(offsetof(struct dhcp_msg, options) == 236);
#define DHCP_MSG_BASE_SIZE offsetof(struct dhcp_msg, options)

/* DHCP message OP code; RFC 2131 page 10*/
#define DHCP_OP_BOOTREQUEST         1
#define DHCP_OP_BOOTREPLY           2

/* DHCP hardware type;
 * https://www.iana.org/assignments/arp-parameters/arp-parameters.xhtml#arp-parameters-2 */
#define DHCP_HTYPE_ETHERNET         1

uint8_t DHCP_SIP[4];                      // DHCP Server IP address
uint8_t DHCP_REAL_SIP[4];                 // For extract my DHCP server in a few DHCP server


// Network information from DHCP Server
struct net_ip4_addr OLD_allocated_ip   = {0};    // Previous IP address
struct dhcp_lease global_lease = {
	.lifetime = INFINITE_LEASETIME,
};

int8_t   dhcp_state        = STATE_DHCP_INIT;   // DHCP state
int8_t   dhcp_retry_count  = 0;

volatile uint32_t dhcp_tick_1s      = 0;                 // unit 1 second
uint32_t dhcp_tick_next    			= DHCP_WAIT_TIME ;

uint32_t global_xid;      // Any number

struct dhcp_msg* pDHCPMSG;      // Buffer pointer for DHCP processing

char global_hostname[64];

struct net_eth_addr global_eth_addr; // DHCP Client MAC address.

/* IP conflict check by sending ARP-request to leased IP and wait ARP-response. */
int8_t   check_DHCP_leasedIP(void);

/* check the timeout in DHCP process */
uint8_t  check_DHCP_timeout(void);

/* Initialize to timeout process.  */
void     reset_DHCP_timeout(void);

/* Parse message as OFFER and ACK and NACK from DHCP server.*/
int8_t   parseDHCPCMSG(void);

/* make the common DHCP message */
void dhcp_msg_init(struct dhcp_msg *msg, size_t *optlen) {
	msg->op     = DHCP_OP_BOOTREQUEST;
	msg->htype  = DHCP_HTYPE_ETHERNET;
	msg->hlen   = sizeof(global_eth_addr);
	msg->hops   = DHCP_HOPS;
	msg->xid    = uint32be_marshal(global_xid);
	msg->secs   = uint16be_marshal(DHCP_SECS);
	msg->flags  = uint16be_marshal(DHCP_FLAGSBROADCAST);
	msg->ciaddr = (struct net_ip4_addr){0};
	msg->yiaddr = (struct net_ip4_addr){0};
	msg->siaddr = (struct net_ip4_addr){0};
	msg->siaddr = (struct net_ip4_addr){0};
	msg->giaddr = (struct net_ip4_addr){0};

	memset(msg->chaddr, 0, sizeof(msg->chaddr));
	memcpy(msg->chaddr, global_eth_addr.octets, sizeof(global_eth_addr));

	memset(msg->sname, 0, sizeof(msg->sname));
	memset(msg->file, 0, sizeof(msg->file));

	*optlen = 0;
	uint32be_encode(&msg->options[*optlen], MAGIC_COOKIE); *optlen += 4;
}

/* SEND DHCP DISCOVER */
void send_DHCP_DISCOVER(implements_net_udpsock *sock) {
	size_t k;

	dhcp_msg_init(pDHCPMSG, &k);
	DHCP_SIP[0]=0;
	DHCP_SIP[1]=0;
	DHCP_SIP[2]=0;
	DHCP_SIP[3]=0;
	DHCP_REAL_SIP[0]=0;
	DHCP_REAL_SIP[1]=0;
	DHCP_REAL_SIP[2]=0;
	DHCP_REAL_SIP[3]=0;

	/* Message type.  */
	pDHCPMSG->options[k++] = DHCP_OPT_DHCP_MSG_TYPE;
	pDHCPMSG->options[k++] = 1;
	pDHCPMSG->options[k++] = DHCP_MSGTYP_DISCOVER;

	/* Our Client ID.  */
	pDHCPMSG->options[k++] = DHCP_OPT_CLIENT_ID;
	pDHCPMSG->options[k++] = 1+sizeof(global_eth_addr);
	pDHCPMSG->options[k++] = DHCP_HTYPE_ETHERNET;
	memcpy(&pDHCPMSG->options[k], global_eth_addr.octets, sizeof(global_eth_addr));
	k += sizeof(global_eth_addr);

	/* Our requested hostname.  */
	pDHCPMSG->options[k++] = DHCP_OPT_HOSTNAME;
	pDHCPMSG->options[k++] = strlen(global_hostname);
	strcpy((char *)&pDHCPMSG->options[k], global_hostname);
	k += strlen(global_hostname);

	/* Which parameters we want back.  */
	pDHCPMSG->options[k++] = DHCP_OPT_PARAMETER_LIST;
	pDHCPMSG->options[k++] = 6;
	pDHCPMSG->options[k++] = DHCP_OPT_SUBNET_MASK;
	pDHCPMSG->options[k++] = DHCP_OPT_ROUTER;
	pDHCPMSG->options[k++] = DHCP_OPT_DOMAIN_SERVER;
	pDHCPMSG->options[k++] = DHCP_OPT_DOMAIN_NAME;
	pDHCPMSG->options[k++] = DHCP_OPT_RENEWAL_TIME;
	pDHCPMSG->options[k++] = DHCP_OPT_REBINDING_TIME;

	/* End.  */
	pDHCPMSG->options[k++] = DHCP_OPT_END;

	debugf("> Send DHCP_DISCOVER");
	sendto(sock, pDHCPMSG, DHCP_MSG_BASE_SIZE + k, net_ip4_broadcast_addr, DHCP_SERVER_PORT);
}

/* SEND DHCP REQUEST */
void send_DHCP_REQUEST(implements_net_udpsock *sock) {
	int i;
	struct net_ip4_addr ip;
	size_t k = 0;

	dhcp_msg_init(pDHCPMSG, &k);

	if(dhcp_state == STATE_DHCP_LEASED || dhcp_state == STATE_DHCP_REREQUEST) {
		pDHCPMSG->flags = uint16be_marshal(DHCP_FLAGSUNICAST);
		pDHCPMSG->ciaddr = global_lease.addr;
		ip = DHCP_SIP;
	} else {
		ip = net_ip4_broadcast_addr;
	}

	/* Message type.  */
	pDHCPMSG->options[k++] = DHCP_OPT_DHCP_MSG_TYPE;
	pDHCPMSG->options[k++] = 1;
	pDHCPMSG->options[k++] = DHCP_REQUEST;

	/* Our Client ID.  */
	pDHCPMSG->options[k++] = DHCP_OPT_CLIENT_ID;
	pDHCPMSG->options[k++] = 1+sizeof(global_eth_addr);
	pDHCPMSG->options[k++] = DHCP_HTYPE_ETHERNET;
	memcpy(&pDHCPMSG->options[k], global_eth_addr.octets, sizeof(global_eth_addr));
	k += sizeof(global_eth_addr);

	if(ip.octets[3] == 255) { // if(dchp_state == STATE_DHCP_LEASED || dchp_state == DHCP_REREQUEST_STATE)
		pDHCPMSG->options[k++] = dhcpRequestedIPaddr;
		pDHCPMSG->options[k++] = 0x04;
		pDHCPMSG->options[k++] = global_lease.addr.octets[0];
		pDHCPMSG->options[k++] = global_lease.addr.octets[1];
		pDHCPMSG->options[k++] = global_lease.addr.octets[2];
		pDHCPMSG->options[k++] = global_lease.addr.octets[3];

		pDHCPMSG->options[k++] = dhcpServerIdentifier;
		pDHCPMSG->options[k++] = 0x04;
		pDHCPMSG->options[k++] = DHCP_SIP[0];
		pDHCPMSG->options[k++] = DHCP_SIP[1];
		pDHCPMSG->options[k++] = DHCP_SIP[2];
		pDHCPMSG->options[k++] = DHCP_SIP[3];
	}

	// host name
	pDHCPMSG->options[k++] = hostName;
	pDHCPMSG->options[k++] = 0; // length of hostname
	for(i = 0 ; HOST_NAME[i] != 0; i++)
		pDHCPMSG->options[k++] = HOST_NAME[i];
	pDHCPMSG->options[k++] = hexdig(global_eth_addr[3] >> 4);
	pDHCPMSG->options[k++] = hexdig(global_eth_addr[3]);
	pDHCPMSG->options[k++] = hexdig(global_eth_addr[4] >> 4);
	pDHCPMSG->options[k++] = hexdig(global_eth_addr[4]);
	pDHCPMSG->options[k++] = hexdig(global_eth_addr[5] >> 4);
	pDHCPMSG->options[k++] = hexdig(global_eth_addr[5]);
	pDHCPMSG->options[k - (i+6+1)] = i+6; // length of hostname

	pDHCPMSG->options[k++] = dhcpParamRequest;
	pDHCPMSG->options[k++] = 0x08;
	pDHCPMSG->options[k++] = DHCP_OPT_SUBNET_MASK;
	pDHCPMSG->options[k++] = DHCP_OPT_ROUTER;
	pDHCPMSG->options[k++] = DHCP_OPT_DOMAIN_SERVER;
	pDHCPMSG->options[k++] = domainName;
	pDHCPMSG->options[k++] = dhcpT1value;
	pDHCPMSG->options[k++] = dhcpT2value;
	pDHCPMSG->options[k++] = performRouterDiscovery;
	pDHCPMSG->options[k++] = staticRoute;
	pDHCPMSG->options[k++] = DHCP_OPT_END;

	debugf("> Send DHCP_REQUEST");

	sendto(sock, pDHCPMSG, DHCP_MSG_BASE_SIZE + k, ip, DHCP_SERVER_PORT);
}

/* SEND DHCP DHCPDECLINE */
void send_DHCP_DECLINE(implements_net_udpsock *sock) {
	int i;
	struct net_ip4_addr ip;
	uint16_t k = 0;

	makeDHCPMSG();

	k = 4;      // because MAGIC_COOKIE already made by makeDHCPMSG()

	*((uint8_t*)(&pDHCPMSG->flags))   = ((DHCP_FLAGSUNICAST & 0xFF00)>> 8);
	*((uint8_t*)(&pDHCPMSG->flags)+1) = (DHCP_FLAGSUNICAST & 0x00FF);

	// Option Request Param.
	pDHCPMSG->options[k++] = DHCP_OPT_DHCP_MSG_TYPE;
	pDHCPMSG->options[k++] = 0x01;
	pDHCPMSG->options[k++] = DHCP_DECLINE;

	/* Our Client ID.  */
	pDHCPMSG->options[k++] = DHCP_OPT_CLIENT_ID;
	pDHCPMSG->options[k++] = 1+sizeof(global_eth_addr);
	pDHCPMSG->options[k++] = DHCP_HTYPE_ETHERNET;
	memcpy(&pDHCPMSG->options[k], global_eth_addr.octets, sizeof(global_eth_addr));
	k += sizeof(global_eth_addr);

	pDHCPMSG->options[k++] = dhcpRequestedIPaddr;
	pDHCPMSG->options[k++] = 0x04;
	pDHCPMSG->options[k++] = global_lease.addr.octets[0];
	pDHCPMSG->options[k++] = global_lease.addr.octets[1];
	pDHCPMSG->options[k++] = global_lease.addr.octets[2];
	pDHCPMSG->options[k++] = global_lease.addr.octets[3];

	pDHCPMSG->options[k++] = dhcpServerIdentifier;
	pDHCPMSG->options[k++] = 0x04;
	pDHCPMSG->options[k++] = DHCP_SIP[0];
	pDHCPMSG->options[k++] = DHCP_SIP[1];
	pDHCPMSG->options[k++] = DHCP_SIP[2];
	pDHCPMSG->options[k++] = DHCP_SIP[3];

	pDHCPMSG->options[k++] = DHCP_OPT_END;

	for (i = k; i < options_SIZE; i++)
		pDHCPMSG->options[i] = 0;

	//send broadcasting packet
	ip.octets[0] = 0xFF;
	ip.octets[1] = 0xFF;
	ip.octets[2] = 0xFF;
	ip.octets[3] = 0xFF;

	debugf("> Send DHCP_DECLINE");

	sendto(sock, pDHCPMSG, RIP_MSG_SIZE, ip, DHCP_SERVER_PORT);
}

/* PARSE REPLY pDHCPMSG */
int8_t parseDHCPMSG(implements_net_udpsock *sock) {
	struct net_ip4_addr srv_addr;
	uint16_t  srv_port;
	size_t len;

	uint8_t * p;
	uint8_t * e;
	uint8_t type = 0;
	uint8_t opt_len;

	len = recvfrom(sock, pDHCPMSG, len, &srv_addr, &srv_port);
	debugf("DHCP message : %d.%d.%d.%d(%d) %d received.",
	       srv_addr.octets[0], srv_addr.octets[1], srv_addr.octets[2], srv_addr.octets[3], srv_port, len);
	if (srv_port == DHCP_SERVER_PORT) {
		// compare mac address
		if ( (pDHCPMSG->chaddr[0] != global_eth_addr[0]) || (pDHCPMSG->chaddr[1] != global_eth_addr[1]) ||
		     (pDHCPMSG->chaddr[2] != global_eth_addr[2]) || (pDHCPMSG->chaddr[3] != global_eth_addr[3]) ||
		     (pDHCPMSG->chaddr[4] != global_eth_addr[4]) || (pDHCPMSG->chaddr[5] != global_eth_addr[5]) ) {
			debugf("No My DHCP Message. This message is ignored.");
			return 0;
		}
		//compare DHCP server ip address
		if ((DHCP_SIP[0]!=0) || (DHCP_SIP[1]!=0) || (DHCP_SIP[2]!=0) || (DHCP_SIP[3]!=0)) {
			if ( ((srv_addr.octets[0]!=DHCP_SIP[0])|| (srv_addr.octets[1]!=DHCP_SIP[1])|| (srv_addr.octets[2]!=DHCP_SIP[2])|| (srv_addr.octets[3]!=DHCP_SIP[3])) &&
			     ((srv_addr.octets[0]!=DHCP_REAL_SIP[0])|| (srv_addr.octets[1]!=DHCP_REAL_SIP[1])|| (srv_addr.octets[2]!=DHCP_REAL_SIP[2])|| (srv_addr.octets[3]!=DHCP_REAL_SIP[3]))  ) {
				debugf("Another DHCP sever send a response message. This is ignored.");
				return 0;
			}
		}
		p = (uint8_t *)(&pDHCPMSG->op);
		p = p + 240;      // 240 = sizeof(RIP_MSG) + MAGIC_COOKIE size in RIP_MSG.opt - sizeof(RIP_MSG.opt)
		e = p + (len - 240);

		while ( p < e ) {
			switch ( *p ) {
			case DHCP_OPT_END :
				p = e;   // for break while(p < e)
				break;
			case DHCP_OPT_PAD :
				p++;
				break;
			case DHCP_OPT_DHCP_MSG_TYPE :
				p++;
				p++;
				type = *p++;
				break;
			case DHCP_OPT_SUBNET_MASK :
				p++;
				p++;
				global_lease.subnet_mask.octets[0] = *p++;
				global_lease.subnet_mask.octets[1] = *p++;
				global_lease.subnet_mask.octets[2] = *p++;
				global_lease.subnet_mask.octets[3] = *p++;
				break;
			case DHCP_OPT_ROUTER :
				p++;
				opt_len = *p++;
				global_lease.gateway.octets[0] = *p++;
				global_lease.gateway.octets[1] = *p++;
				global_lease.gateway.octets[2] = *p++;
				global_lease.gateway.octets[3] = *p++;
				p = p + (opt_len - 4);
				break;
			case DHCP_OPT_DOMAIN_SERVER :
				p++;
				opt_len = *p++;
				global_lease.dns.octets[0] = *p++;
				global_lease.dns.octets[1] = *p++;
				global_lease.dns.octets[2] = *p++;
				global_lease.dns.octets[3] = *p++;
				p = p + (opt_len - 4);
				break;
			case dhcpIPaddrLeaseTime :
				p++;
				opt_len = *p++;
				global_lease.lifetime  = *p++;
				global_lease.lifetime  = (global_lease.lifetime << 8) + *p++;
				global_lease.lifetime  = (global_lease.lifetime << 8) + *p++;
				global_lease.lifetime  = (global_lease.lifetime << 8) + *p++;
#ifdef _DHCP_DEBUG_
				global_lease.lifetime = 10;
#endif
				break;
			case dhcpServerIdentifier :
				p++;
				opt_len = *p++;
				DHCP_SIP[0] = *p++;
				DHCP_SIP[1] = *p++;
				DHCP_SIP[2] = *p++;
				DHCP_SIP[3] = *p++;
				DHCP_REAL_SIP[0]=srv_addr.octets[0];
				DHCP_REAL_SIP[1]=srv_addr.octets[1];
				DHCP_REAL_SIP[2]=srv_addr.octets[2];
				DHCP_REAL_SIP[3]=srv_addr.octets[3];
				break;
			default :
				p++;
				opt_len = *p++;
				p += opt_len;
				break;
			} // switch
		} // while
	} // if
	return	type;
}

uint8_t DHCP_run(implements_net_udpsock *sock, dhcp_callback_t cb) {
	uint8_t  type;
	uint8_t  ret;

	if(dhcp_state == STATE_DHCP_STOP)
		return DHCP_STOPPED;

	if(getSn_SR(sock) != SOCK_UDP)
		socket(sock, Sn_MR_UDP, DHCP_CLIENT_PORT, 0x00);

	ret = DHCP_RUNNING;
	type = parseDHCPMSG();

	switch ( dhcp_state ) {
	case STATE_DHCP_INIT     :
		global_lease.addr.octets[0] = 0;
		global_lease.addr.octets[1] = 0;
		global_lease.addr.octets[2] = 0;
		global_lease.addr.octets[3] = 0;
		send_DHCP_DISCOVER();
		dhcp_state = STATE_DHCP_DISCOVER;
		break;
	case STATE_DHCP_DISCOVER :
		if (type == DHCP_OFFER){
			debugf("> Receive DHCP_OFFER");
			global_lease.addr.octets[0] = pDHCPMSG->yiaddr[0];
			global_lease.addr.octets[1] = pDHCPMSG->yiaddr[1];
			global_lease.addr.octets[2] = pDHCPMSG->yiaddr[2];
			global_lease.addr.octets[3] = pDHCPMSG->yiaddr[3];

			send_DHCP_REQUEST();
			dhcp_state = STATE_DHCP_REQUEST;
		} else
			ret = check_DHCP_timeout();
		break;

	case STATE_DHCP_REQUEST :
		if (type == DHCP_ACK) {
			debugf("> Receive DHCP_ACK");
			if (check_DHCP_leasedIP()) {
				// Network info assignment from DHCP
				cb(DHCP_ASSIGN, global_lease);
				reset_DHCP_timeout();

				dhcp_state = STATE_DHCP_LEASED;
			} else {
				// IP address conflict occurred
				reset_DHCP_timeout();
				cb(DHCP_CONFLICT, global_lease);
				dhcp_state = STATE_DHCP_INIT;
			}
		} else if (type == DHCP_NAK) {
			debugf("> Receive DHCP_NACK");

			reset_DHCP_timeout();

			dhcp_state = STATE_DHCP_DISCOVER;
		} else
			ret = check_DHCP_timeout();
		break;

	case STATE_DHCP_LEASED :
		ret = DHCP_IP_LEASED;
		if ((global_lease.lifetime != INFINITE_LEASETIME) && ((global_lease.lifetime/2) < dhcp_tick_1s)) {
			debugf("> Maintains the IP address");

			type = 0;
			OLD_allocated_ip[0] = global_lease.addr.octets[0];
			OLD_allocated_ip[1] = global_lease.addr.octets[1];
			OLD_allocated_ip[2] = global_lease.addr.octets[2];
			OLD_allocated_ip[3] = global_lease.addr.octets[3];

			global_xid++;

			send_DHCP_REQUEST();

			reset_DHCP_timeout();

			dhcp_state = STATE_DHCP_REREQUEST;
		}
		break;

	case STATE_DHCP_REREQUEST :
		ret = DHCP_IP_LEASED;
		if (type == DHCP_ACK) {
			dhcp_retry_count = 0;
			if (OLD_allocated_ip[0] != global_lease.addr.octets[0] ||
			    OLD_allocated_ip[1] != global_lease.addr.octets[1] ||
			    OLD_allocated_ip[2] != global_lease.addr.octets[2] ||
			    OLD_allocated_ip[3] != global_lease.addr.octets[3]) {
				ret = DHCP_IP_CHANGED;
				cb(DHCP_UPDATE, global_lease);
				debugf(">IP changed.");
			} else {
				debugf(">IP is continued.");
			}
			reset_DHCP_timeout();
			dhcp_state = STATE_DHCP_LEASED;
		} else if (type == DHCP_NAK) {
			debugf("> Receive DHCP_NACK, Failed to maintain ip");
			reset_DHCP_timeout();

			dhcp_state = STATE_DHCP_DISCOVER;
		} else
			ret = check_DHCP_timeout();
		break;
	default :
		break;
	}

	return ret;
}

void    DHCP_stop(void) {
	close(DHCP_SOCKET);
	dhcp_state = STATE_DHCP_STOP;
}

uint8_t check_DHCP_timeout(void) {
	uint8_t ret = DHCP_RUNNING;

	if (dhcp_retry_count < MAX_DHCP_RETRY) {
		if (dhcp_tick_next < dhcp_tick_1s) {

			switch ( dhcp_state ) {
			case STATE_DHCP_DISCOVER :
				//debugf("<<timeout>> state : STATE_DHCP_DISCOVER");
				send_DHCP_DISCOVER();
				break;

			case STATE_DHCP_REQUEST :
				//debugf("<<timeout>> state : STATE_DHCP_REQUEST");

				send_DHCP_REQUEST();
				break;

			case STATE_DHCP_REREQUEST :
				//debugf("<<timeout>> state : STATE_DHCP_REREQUEST");

				send_DHCP_REQUEST();
				break;

			default :
				break;
			}

			dhcp_tick_1s = 0;
			dhcp_tick_next = dhcp_tick_1s + DHCP_WAIT_TIME;
			dhcp_retry_count++;
		}
	} else { // timeout occurred

		switch(dhcp_state) {
		case STATE_DHCP_DISCOVER:
			dhcp_state = STATE_DHCP_INIT;
			ret = DHCP_FAILED;
			break;
		case STATE_DHCP_REQUEST:
		case STATE_DHCP_REREQUEST:
			send_DHCP_DISCOVER();
			dhcp_state = STATE_DHCP_DISCOVER;
			break;
		default :
			break;
		}
		reset_DHCP_timeout();
	}
	return ret;
}

int8_t check_DHCP_leasedIP(void) {
	uint8_t tmp;
	int32_t ret;

	//WIZchip RCR value changed for ARP Timeout count control
	tmp = getRCR();
	setRCR(0x03);

	// IP conflict detection : ARP request - ARP reply
	// Broadcasting ARP Request for check the IP conflict using UDP sendto() function
	ret = sendto(DHCP_SOCKET, "CHECK_IP_CONFLICT", 17, global_lease.addr, 5000);

	// RCR value restore
	setRCR(tmp);

	if(ret == SOCKERR_TIMEOUT) {
		// UDP send Timeout occurred : allocated IP address is unique, DHCP Success

		debugf("\r\n> Check leased IP - OK");

		return 1;
	} else {
		// Received ARP reply or etc : IP address conflict occur, DHCP Failed
		send_DHCP_DECLINE();

		ret = dhcp_tick_1s;
		while((dhcp_tick_1s - ret) < 2) ;   // wait for 1s over; wait to complete to send DECLINE message;

		return 0;
	}
}

void DHCP_init(uint8_t s, uint8_t * buf) {
	uint8_t zeroip[4] = {0,0,0,0};
	getSHAR(global_eth_addr);
	if ((global_eth_addr[0] | global_eth_addr[1]  | global_eth_addr[2] | global_eth_addr[3] | global_eth_addr[4] | global_eth_addr[5]) == 0x00) {
		// assigning temporary mac address, you should be set SHAR before call this function.
		global_eth_addr[0] = 0x00;
		global_eth_addr[1] = 0x08;
		global_eth_addr[2] = 0xdc;
		global_eth_addr[3] = 0x00;
		global_eth_addr[4] = 0x00;
		global_eth_addr[5] = 0x00;
		setSHAR(global_eth_addr);
	}

	global_hostname[0]  = "W";
	global_hostname[1]  = "I";
	global_hostname[2]  = "Z";
	global_hostname[3]  = "n";
	global_hostname[4]  = "e";
	global_hostname[5]  = "t";
	global_hostname[6]  = "0123456789ABCDEF"[(global_eth_addr.octets[3] >> 4)&0xF];
	global_hostname[7]  = "0123456789ABCDEF"[(global_eth_addr.octets[3] >> 0)&0xF];
	global_hostname[8]  = "0123456789ABCDEF"[(global_eth_addr.octets[4] >> 4)&0xF];
	global_hostname[9]  = "0123456789ABCDEF"[(global_eth_addr.octets[4] >> 0)&0xF];
	global_hostname[10] = "0123456789ABCDEF"[(global_eth_addr.octets[5] >> 4)&0xF];
	global_hostname[11] = "0123456789ABCDEF"[(global_eth_addr.octets[5] >> 0)&0xF];
	global_hostname[12] = '\0';

	DHCP_SOCKET = s; // SOCK_DHCP
	pDHCPMSG = (RIP_MSG*)buf;
	global_xid = 0x12345678;
	{
		global_xid += global_eth_addr[3];
		global_xid += global_eth_addr[4];
		global_xid += global_eth_addr[5];
		global_xid += (global_eth_addr[3] ^ global_eth_addr[4] ^ global_eth_addr[5]);
	}
	// WIZchip Netinfo Clear
	setSIPR(zeroip);
	setGAR(zeroip);

	reset_DHCP_timeout();
	dhcp_state = STATE_DHCP_INIT;
}

/* Reset the DHCP timeout count and retry count. */
void reset_DHCP_timeout(void) {
	dhcp_tick_1s = 0;
	dhcp_tick_next = DHCP_WAIT_TIME;
	dhcp_retry_count = 0;
}

void DHCP_time_handler(void) {
	dhcp_tick_1s++;
}