Momentum-Apps/lib/ioLibrary_Driver/Internet/DHCP/dhcp.c

//*****************************************************************************
//
//! \file dhcp.c
//! \brief DHCP APIs implement file.
//! \details Processing DHCP protocol as DISCOVER, OFFER, REQUEST, ACK, NACK and DECLINE.
//! \version 1.1.1
//! \date 2019/10/08
//! \par  Revision history
//!       <2019/10/08> compare DHCP server ip address
//!       <2013/11/18> 1st Release
//!       <2012/12/20> V1.1.0
//!         1. Optimize code
//!         2. Add reg_dhcp_cbfunc()
//!         3. Add DHCP_stop()
//!         4. Integrate check_DHCP_state() & DHCP_run() to DHCP_run()
//!         5. Don't care system endian
//!         6. Add comments
//!       <2012/12/26> V1.1.1
//!         1. Modify variable declaration: dhcp_tick_1s is declared volatile for code optimization
//! \author Eric Jung & MidnightCow
//! \copyright
//!
//! 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.
//
//*****************************************************************************

#include "socket.h"
#include "dhcp.h"

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

#ifdef _DHCP_DEBUG_
#include <stdio.h>
#endif

#define _DHCP_DEBUG_

/* 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

/* DHCP message OP code */
#define DHCP_BOOTREQUEST 1 ///< Request Message used in op of @ref RIP_MSG
#define DHCP_BOOTREPLY 2 ///< Reply Message used i op of @ref RIP_MSG

/* DHCP message type */
#define DHCP_DISCOVER 1 ///< DISCOVER message in OPT of @ref RIP_MSG
#define DHCP_OFFER 2 ///< OFFER message in OPT of @ref RIP_MSG
#define DHCP_REQUEST 3 ///< REQUEST message in OPT of @ref RIP_MSG
#define DHCP_DECLINE 4 ///< DECLINE message in OPT of @ref RIP_MSG
#define DHCP_ACK 5 ///< ACK message in OPT of @ref RIP_MSG
#define DHCP_NAK 6 ///< NACK message in OPT of @ref RIP_MSG
#define DHCP_RELEASE 7 ///< RELEASE message in OPT of @ref RIP_MSG. No use
#define DHCP_INFORM 8 ///< INFORM message in OPT of @ref RIP_MSG. No use

#define DHCP_HTYPE10MB 1 ///< Used in type of @ref RIP_MSG
#define DHCP_HTYPE100MB 2 ///< Used in type of @ref RIP_MSG

#define DHCP_HLENETHERNET 6 ///< Used in hlen of @ref RIP_MSG
#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

#define OPT_SIZE 312 /// Max OPT size of @ref RIP_MSG
#define RIP_MSG_SIZE (236 + OPT_SIZE) /// Max size of @ref RIP_MSG

/* 
 * @brief DHCP option and value (cf. RFC1533)
 */
enum {
    padOption = 0,
    subnetMask = 1,
    timerOffset = 2,
    routersOnSubnet = 3,
    timeServer = 4,
    nameServer = 5,
    dns = 6,
    logServer = 7,
    cookieServer = 8,
    lprServer = 9,
    impressServer = 10,
    resourceLocationServer = 11,
    hostName = 12,
    bootFileSize = 13,
    meritDumpFile = 14,
    domainName = 15,
    swapServer = 16,
    rootPath = 17,
    extentionsPath = 18,
    IPforwarding = 19,
    nonLocalSourceRouting = 20,
    policyFilter = 21,
    maxDgramReasmSize = 22,
    defaultIPTTL = 23,
    pathMTUagingTimeout = 24,
    pathMTUplateauTable = 25,
    ifMTU = 26,
    allSubnetsLocal = 27,
    broadcastAddr = 28,
    performMaskDiscovery = 29,
    maskSupplier = 30,
    performRouterDiscovery = 31,
    routerSolicitationAddr = 32,
    staticRoute = 33,
    trailerEncapsulation = 34,
    arpCacheTimeout = 35,
    ethernetEncapsulation = 36,
    tcpDefaultTTL = 37,
    tcpKeepaliveInterval = 38,
    tcpKeepaliveGarbage = 39,
    nisDomainName = 40,
    nisServers = 41,
    ntpServers = 42,
    vendorSpecificInfo = 43,
    netBIOSnameServer = 44,
    netBIOSdgramDistServer = 45,
    netBIOSnodeType = 46,
    netBIOSscope = 47,
    xFontServer = 48,
    xDisplayManager = 49,
    dhcpRequestedIPaddr = 50,
    dhcpIPaddrLeaseTime = 51,
    dhcpOptionOverload = 52,
    dhcpMessageType = 53,
    dhcpServerIdentifier = 54,
    dhcpParamRequest = 55,
    dhcpMsg = 56,
    dhcpMaxMsgSize = 57,
    dhcpT1value = 58,
    dhcpT2value = 59,
    dhcpClassIdentifier = 60,
    dhcpClientIdentifier = 61,
    endOption = 255
};

/*
 * @brief DHCP message format
 */
typedef struct {
    uint8_t op; ///< @ref DHCP_BOOTREQUEST or @ref DHCP_BOOTREPLY
    uint8_t htype; ///< @ref DHCP_HTYPE10MB or @ref DHCP_HTYPE100MB
    uint8_t hlen; ///< @ref DHCP_HLENETHERNET
    uint8_t hops; ///< @ref DHCP_HOPS
    uint32_t xid; ///< @ref DHCP_XID  This increase one every DHCP transaction.
    uint16_t secs; ///< @ref DHCP_SECS
    uint16_t flags; ///< @ref DHCP_FLAGSBROADCAST or @ref DHCP_FLAGSUNICAST
    uint8_t ciaddr[4]; ///< @ref Request IP to DHCP sever
    uint8_t yiaddr[4]; ///< @ref Offered IP from DHCP server
    uint8_t siaddr[4]; ///< No use
    uint8_t giaddr[4]; ///< No use
    uint8_t chaddr[16]; ///< DHCP client 6bytes MAC address. Others is filled to zero
    uint8_t sname[64]; ///< No use
    uint8_t file[128]; ///< No use
    uint8_t OPT[OPT_SIZE]; ///< Option
} RIP_MSG;

uint8_t DHCP_SOCKET; // Socket number for DHCP

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
uint8_t OLD_allocated_ip[4] = {
    0,
}; // Previous IP address
uint8_t DHCP_allocated_ip[4] = {
    0,
}; // IP address from DHCP
uint8_t DHCP_allocated_gw[4] = {
    0,
}; // Gateway address from DHCP
uint8_t DHCP_allocated_sn[4] = {
    0,
}; // Subnet mask from DHCP
uint8_t DHCP_allocated_dns[4] = {
    0,
}; // DNS address from DHCP

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

uint32_t dhcp_lease_time = INFINITE_LEASETIME;
volatile int32_t dhcp_tick_1s = 0; // unit 1 second
uint32_t dhcp_tick_next = DHCP_WAIT_TIME;

uint32_t DHCP_XID; // Any number

RIP_MSG* pDHCPMSG; // Buffer pointer for DHCP processing

uint8_t HOST_NAME[] = DCHP_HOST_NAME;

uint8_t DHCP_CHADDR[6]; // DHCP Client MAC address.

/* The default callback function */
void default_ip_assign(void);
void default_ip_update(void);
void default_ip_conflict(void);

/* Callback handler */
void (*dhcp_ip_assign)(void) =
    default_ip_assign; /* handler to be called when the IP address from DHCP server is first assigned */
void (*dhcp_ip_update)(void) =
    default_ip_update; /* handler to be called when the IP address from DHCP server is updated */
void (*dhcp_ip_conflict)(void) =
    default_ip_conflict; /* handler to be called when the IP address from DHCP server is conflict */

void reg_dhcp_cbfunc(void (*ip_assign)(void), void (*ip_update)(void), void (*ip_conflict)(void));

char NibbleToHex(uint8_t nibble);

/* send DISCOVER message to DHCP server */
void send_DHCP_DISCOVER(void);

/* send REQEUST message to DHCP server */
void send_DHCP_REQUEST(void);

/* send DECLINE message to DHCP server */
void send_DHCP_DECLINE(void);

/* 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);

/* The default handler of ip assign first */
void default_ip_assign(void) {
    setSIPR(DHCP_allocated_ip);
    setSUBR(DHCP_allocated_sn);
    setGAR(DHCP_allocated_gw);
}

/* The default handler of ip changed */
void default_ip_update(void) {
    /* WIZchip Software Reset */
    setMR(MR_RST);
    getMR(); // for delay
    default_ip_assign();
    setSHAR(DHCP_CHADDR);
}

/* The default handler of ip changed */
void default_ip_conflict(void) {
    // WIZchip Software Reset
    setMR(MR_RST);
    getMR(); // for delay
    setSHAR(DHCP_CHADDR);
}

/* register the call back func. */
void reg_dhcp_cbfunc(void (*ip_assign)(void), void (*ip_update)(void), void (*ip_conflict)(void)) {
    dhcp_ip_assign = default_ip_assign;
    dhcp_ip_update = default_ip_update;
    dhcp_ip_conflict = default_ip_conflict;
    if(ip_assign) dhcp_ip_assign = ip_assign;
    if(ip_update) dhcp_ip_update = ip_update;
    if(ip_conflict) dhcp_ip_conflict = ip_conflict;
}

/* make the common DHCP message */
void makeDHCPMSG(void) {
    uint8_t bk_mac[6];
    uint8_t* ptmp;
    uint8_t i;
    getSHAR(bk_mac);
    pDHCPMSG->op = DHCP_BOOTREQUEST;
    pDHCPMSG->htype = DHCP_HTYPE10MB;
    pDHCPMSG->hlen = DHCP_HLENETHERNET;
    pDHCPMSG->hops = DHCP_HOPS;
    ptmp = (uint8_t*)(&pDHCPMSG->xid);
    *(ptmp + 0) = (uint8_t)((DHCP_XID & 0xFF000000) >> 24);
    *(ptmp + 1) = (uint8_t)((DHCP_XID & 0x00FF0000) >> 16);
    *(ptmp + 2) = (uint8_t)((DHCP_XID & 0x0000FF00) >> 8);
    *(ptmp + 3) = (uint8_t)((DHCP_XID & 0x000000FF) >> 0);
    pDHCPMSG->secs = DHCP_SECS;
    ptmp = (uint8_t*)(&pDHCPMSG->flags);
    *(ptmp + 0) = (uint8_t)((DHCP_FLAGSBROADCAST & 0xFF00) >> 8);
    *(ptmp + 1) = (uint8_t)((DHCP_FLAGSBROADCAST & 0x00FF) >> 0);

    pDHCPMSG->ciaddr[0] = 0;
    pDHCPMSG->ciaddr[1] = 0;
    pDHCPMSG->ciaddr[2] = 0;
    pDHCPMSG->ciaddr[3] = 0;

    pDHCPMSG->yiaddr[0] = 0;
    pDHCPMSG->yiaddr[1] = 0;
    pDHCPMSG->yiaddr[2] = 0;
    pDHCPMSG->yiaddr[3] = 0;

    pDHCPMSG->siaddr[0] = 0;
    pDHCPMSG->siaddr[1] = 0;
    pDHCPMSG->siaddr[2] = 0;
    pDHCPMSG->siaddr[3] = 0;

    pDHCPMSG->giaddr[0] = 0;
    pDHCPMSG->giaddr[1] = 0;
    pDHCPMSG->giaddr[2] = 0;
    pDHCPMSG->giaddr[3] = 0;

    pDHCPMSG->chaddr[0] = DHCP_CHADDR[0];
    pDHCPMSG->chaddr[1] = DHCP_CHADDR[1];
    pDHCPMSG->chaddr[2] = DHCP_CHADDR[2];
    pDHCPMSG->chaddr[3] = DHCP_CHADDR[3];
    pDHCPMSG->chaddr[4] = DHCP_CHADDR[4];
    pDHCPMSG->chaddr[5] = DHCP_CHADDR[5];

    for(i = 6; i < 16; i++) pDHCPMSG->chaddr[i] = 0;
    for(i = 0; i < 64; i++) pDHCPMSG->sname[i] = 0;
    for(i = 0; i < 128; i++) pDHCPMSG->file[i] = 0;

    // MAGIC_COOKIE
    pDHCPMSG->OPT[0] = (uint8_t)((MAGIC_COOKIE & 0xFF000000) >> 24);
    pDHCPMSG->OPT[1] = (uint8_t)((MAGIC_COOKIE & 0x00FF0000) >> 16);
    pDHCPMSG->OPT[2] = (uint8_t)((MAGIC_COOKIE & 0x0000FF00) >> 8);
    pDHCPMSG->OPT[3] = (uint8_t)(MAGIC_COOKIE & 0x000000FF) >> 0;
}

/* SEND DHCP DISCOVER */
void send_DHCP_DISCOVER(void) {
    uint16_t i;
    uint8_t ip[4];
    uint16_t k = 0;

    makeDHCPMSG();
    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;

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

    // Option Request Param
    pDHCPMSG->OPT[k++] = dhcpMessageType;
    pDHCPMSG->OPT[k++] = 0x01;
    pDHCPMSG->OPT[k++] = DHCP_DISCOVER;

    // Client identifier
    pDHCPMSG->OPT[k++] = dhcpClientIdentifier;
    pDHCPMSG->OPT[k++] = 0x07;
    pDHCPMSG->OPT[k++] = 0x01;
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[0];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[1];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[2];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[3];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[4];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[5];

    // host name
    pDHCPMSG->OPT[k++] = hostName;
    pDHCPMSG->OPT[k++] = 0; // fill zero length of hostname
    for(i = 0; HOST_NAME[i] != 0; i++) pDHCPMSG->OPT[k++] = HOST_NAME[i];
    pDHCPMSG->OPT[k++] = NibbleToHex(DHCP_CHADDR[3] >> 4);
    pDHCPMSG->OPT[k++] = NibbleToHex(DHCP_CHADDR[3]);
    pDHCPMSG->OPT[k++] = NibbleToHex(DHCP_CHADDR[4] >> 4);
    pDHCPMSG->OPT[k++] = NibbleToHex(DHCP_CHADDR[4]);
    pDHCPMSG->OPT[k++] = NibbleToHex(DHCP_CHADDR[5] >> 4);
    pDHCPMSG->OPT[k++] = NibbleToHex(DHCP_CHADDR[5]);
    pDHCPMSG->OPT[k - (i + 6 + 1)] = i + 6; // length of hostname

    pDHCPMSG->OPT[k++] = dhcpParamRequest;
    pDHCPMSG->OPT[k++] = 0x06; // length of request
    pDHCPMSG->OPT[k++] = subnetMask;
    pDHCPMSG->OPT[k++] = routersOnSubnet;
    pDHCPMSG->OPT[k++] = dns;
    pDHCPMSG->OPT[k++] = domainName;
    pDHCPMSG->OPT[k++] = dhcpT1value;
    pDHCPMSG->OPT[k++] = dhcpT2value;
    pDHCPMSG->OPT[k++] = endOption;

    for(i = k; i < OPT_SIZE; i++) pDHCPMSG->OPT[i] = 0;

    // send broadcasting packet
    ip[0] = 255;
    ip[1] = 255;
    ip[2] = 255;
    ip[3] = 255;

#ifdef _DHCP_DEBUG_
    eth_printf("> Send DHCP_DISCOVER");
#endif
    sendto(DHCP_SOCKET, (uint8_t*)pDHCPMSG, RIP_MSG_SIZE, ip, DHCP_SERVER_PORT);
}

/* SEND DHCP REQUEST */
void send_DHCP_REQUEST(void) {
    int i;
    uint8_t ip[4];
    uint16_t k = 0;

    makeDHCPMSG();

    if(dhcp_state == STATE_DHCP_LEASED || dhcp_state == STATE_DHCP_REREQUEST) {
        *((uint8_t*)(&pDHCPMSG->flags)) = ((DHCP_FLAGSUNICAST & 0xFF00) >> 8);
        *((uint8_t*)(&pDHCPMSG->flags) + 1) = (DHCP_FLAGSUNICAST & 0x00FF);
        pDHCPMSG->ciaddr[0] = DHCP_allocated_ip[0];
        pDHCPMSG->ciaddr[1] = DHCP_allocated_ip[1];
        pDHCPMSG->ciaddr[2] = DHCP_allocated_ip[2];
        pDHCPMSG->ciaddr[3] = DHCP_allocated_ip[3];
        ip[0] = DHCP_SIP[0];
        ip[1] = DHCP_SIP[1];
        ip[2] = DHCP_SIP[2];
        ip[3] = DHCP_SIP[3];
    } else {
        ip[0] = 255;
        ip[1] = 255;
        ip[2] = 255;
        ip[3] = 255;
    }

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

    // Option Request Param.
    pDHCPMSG->OPT[k++] = dhcpMessageType;
    pDHCPMSG->OPT[k++] = 0x01;
    pDHCPMSG->OPT[k++] = DHCP_REQUEST;

    pDHCPMSG->OPT[k++] = dhcpClientIdentifier;
    pDHCPMSG->OPT[k++] = 0x07;
    pDHCPMSG->OPT[k++] = 0x01;
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[0];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[1];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[2];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[3];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[4];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[5];

    if(ip[3] == 255) // if(dchp_state == STATE_DHCP_LEASED || dchp_state == DHCP_REREQUEST_STATE)
    {
        pDHCPMSG->OPT[k++] = dhcpRequestedIPaddr;
        pDHCPMSG->OPT[k++] = 0x04;
        pDHCPMSG->OPT[k++] = DHCP_allocated_ip[0];
        pDHCPMSG->OPT[k++] = DHCP_allocated_ip[1];
        pDHCPMSG->OPT[k++] = DHCP_allocated_ip[2];
        pDHCPMSG->OPT[k++] = DHCP_allocated_ip[3];

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

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

    pDHCPMSG->OPT[k++] = dhcpParamRequest;
    pDHCPMSG->OPT[k++] = 0x08;
    pDHCPMSG->OPT[k++] = subnetMask;
    pDHCPMSG->OPT[k++] = routersOnSubnet;
    pDHCPMSG->OPT[k++] = dns;
    pDHCPMSG->OPT[k++] = domainName;
    pDHCPMSG->OPT[k++] = dhcpT1value;
    pDHCPMSG->OPT[k++] = dhcpT2value;
    pDHCPMSG->OPT[k++] = performRouterDiscovery;
    pDHCPMSG->OPT[k++] = staticRoute;
    pDHCPMSG->OPT[k++] = endOption;

    for(i = k; i < OPT_SIZE; i++) pDHCPMSG->OPT[i] = 0;

#ifdef _DHCP_DEBUG_
    eth_printf("> Send DHCP_REQUEST");
#endif

    sendto(DHCP_SOCKET, (uint8_t*)pDHCPMSG, RIP_MSG_SIZE, ip, DHCP_SERVER_PORT);
}

/* SEND DHCP DHCPDECLINE */
void send_DHCP_DECLINE(void) {
    int i;
    uint8_t ip[4];
    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->OPT[k++] = dhcpMessageType;
    pDHCPMSG->OPT[k++] = 0x01;
    pDHCPMSG->OPT[k++] = DHCP_DECLINE;

    pDHCPMSG->OPT[k++] = dhcpClientIdentifier;
    pDHCPMSG->OPT[k++] = 0x07;
    pDHCPMSG->OPT[k++] = 0x01;
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[0];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[1];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[2];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[3];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[4];
    pDHCPMSG->OPT[k++] = DHCP_CHADDR[5];

    pDHCPMSG->OPT[k++] = dhcpRequestedIPaddr;
    pDHCPMSG->OPT[k++] = 0x04;
    pDHCPMSG->OPT[k++] = DHCP_allocated_ip[0];
    pDHCPMSG->OPT[k++] = DHCP_allocated_ip[1];
    pDHCPMSG->OPT[k++] = DHCP_allocated_ip[2];
    pDHCPMSG->OPT[k++] = DHCP_allocated_ip[3];

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

    pDHCPMSG->OPT[k++] = endOption;

    for(i = k; i < OPT_SIZE; i++) pDHCPMSG->OPT[i] = 0;

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

#ifdef _DHCP_DEBUG_
    eth_printf("\r\n> Send DHCP_DECLINE");
#endif

    sendto(DHCP_SOCKET, (uint8_t*)pDHCPMSG, RIP_MSG_SIZE, ip, DHCP_SERVER_PORT);
}

/* PARSE REPLY pDHCPMSG */
int8_t parseDHCPMSG(void) {
    uint8_t svr_addr[6];
    uint16_t svr_port;
    uint16_t len;

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

    if((len = getSn_RX_RSR(DHCP_SOCKET)) > 0) {
        len = recvfrom(DHCP_SOCKET, (uint8_t*)pDHCPMSG, len, svr_addr, &svr_port);
#ifdef _DHCP_DEBUG_
        eth_printf(
            "DHCP message : %d.%d.%d.%d(%d) %d received.",
            svr_addr[0],
            svr_addr[1],
            svr_addr[2],
            svr_addr[3],
            svr_port,
            len);
#endif
    } else
        return 0;

    if(svr_port == DHCP_SERVER_PORT) {
        // compare mac address
        if((pDHCPMSG->chaddr[0] != DHCP_CHADDR[0]) || (pDHCPMSG->chaddr[1] != DHCP_CHADDR[1]) ||
           (pDHCPMSG->chaddr[2] != DHCP_CHADDR[2]) || (pDHCPMSG->chaddr[3] != DHCP_CHADDR[3]) ||
           (pDHCPMSG->chaddr[4] != DHCP_CHADDR[4]) || (pDHCPMSG->chaddr[5] != DHCP_CHADDR[5])) {
#ifdef _DHCP_DEBUG_
            eth_printf("No My DHCP Message. This message is ignored.");
#endif
            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(((svr_addr[0] != DHCP_SIP[0]) || (svr_addr[1] != DHCP_SIP[1]) ||
                (svr_addr[2] != DHCP_SIP[2]) || (svr_addr[3] != DHCP_SIP[3])) &&
               ((svr_addr[0] != DHCP_REAL_SIP[0]) || (svr_addr[1] != DHCP_REAL_SIP[1]) ||
                (svr_addr[2] != DHCP_REAL_SIP[2]) || (svr_addr[3] != DHCP_REAL_SIP[3]))) {
#ifdef _DHCP_DEBUG_
                eth_printf("Another DHCP sever send a response message. This is ignored.");
#endif
                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 endOption:
                p = e; // for break while(p < e)
                break;
            case padOption:
                p++;
                break;
            case dhcpMessageType:
                p++;
                p++;
                type = *p++;
                break;
            case subnetMask:
                p++;
                p++;
                DHCP_allocated_sn[0] = *p++;
                DHCP_allocated_sn[1] = *p++;
                DHCP_allocated_sn[2] = *p++;
                DHCP_allocated_sn[3] = *p++;
                break;
            case routersOnSubnet:
                p++;
                opt_len = *p++;
                DHCP_allocated_gw[0] = *p++;
                DHCP_allocated_gw[1] = *p++;
                DHCP_allocated_gw[2] = *p++;
                DHCP_allocated_gw[3] = *p++;
                p = p + (opt_len - 4);
                break;
            case dns:
                p++;
                opt_len = *p++;
                DHCP_allocated_dns[0] = *p++;
                DHCP_allocated_dns[1] = *p++;
                DHCP_allocated_dns[2] = *p++;
                DHCP_allocated_dns[3] = *p++;
                p = p + (opt_len - 4);
                break;
            case dhcpIPaddrLeaseTime:
                p++;
                opt_len = *p++;
                dhcp_lease_time = *p++;
                dhcp_lease_time = (dhcp_lease_time << 8) + *p++;
                dhcp_lease_time = (dhcp_lease_time << 8) + *p++;
                dhcp_lease_time = (dhcp_lease_time << 8) + *p++;
#ifdef _DHCP_DEBUG_
                dhcp_lease_time = 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] = svr_addr[0];
                DHCP_REAL_SIP[1] = svr_addr[1];
                DHCP_REAL_SIP[2] = svr_addr[2];
                DHCP_REAL_SIP[3] = svr_addr[3];
                break;
            default:
                p++;
                opt_len = *p++;
                p += opt_len;
                break;
            } // switch
        } // while
    } // if
    return type;
}

uint8_t DHCP_run(void) {
    uint8_t type;
    uint8_t ret;

    if(dhcp_state == STATE_DHCP_STOP) return DHCP_STOPPED;

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

    ret = DHCP_RUNNING;
    type = parseDHCPMSG();

    switch(dhcp_state) {
    case STATE_DHCP_INIT:
        DHCP_allocated_ip[0] = 0;
        DHCP_allocated_ip[1] = 0;
        DHCP_allocated_ip[2] = 0;
        DHCP_allocated_ip[3] = 0;
        send_DHCP_DISCOVER();
        dhcp_state = STATE_DHCP_DISCOVER;
        break;
    case STATE_DHCP_DISCOVER:
        if(type == DHCP_OFFER) {
#ifdef _DHCP_DEBUG_
            eth_printf("> Receive DHCP_OFFER");
#endif
            DHCP_allocated_ip[0] = pDHCPMSG->yiaddr[0];
            DHCP_allocated_ip[1] = pDHCPMSG->yiaddr[1];
            DHCP_allocated_ip[2] = pDHCPMSG->yiaddr[2];
            DHCP_allocated_ip[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) {
#ifdef _DHCP_DEBUG_
            eth_printf("> Receive DHCP_ACK");
#endif
            if(check_DHCP_leasedIP()) {
                // Network info assignment from DHCP
                dhcp_ip_assign();
                reset_DHCP_timeout();
                dhcp_state = STATE_DHCP_LEASED;
            } else {
                // IP address conflict occurred
                reset_DHCP_timeout();
                dhcp_ip_conflict();
                dhcp_state = STATE_DHCP_INIT;
            }
        } else if(type == DHCP_NAK) {
#ifdef _DHCP_DEBUG_
            eth_printf("> Receive DHCP_NACK");
#endif
            reset_DHCP_timeout();
            dhcp_state = STATE_DHCP_DISCOVER;
        } else {
            ret = check_DHCP_timeout();
        }
        break;
    case STATE_DHCP_LEASED:
        ret = DHCP_IP_LEASED;
        if((dhcp_lease_time != INFINITE_LEASETIME) && ((dhcp_lease_time / 2) < dhcp_tick_1s)) {
#ifdef _DHCP_DEBUG_
            eth_printf("> Maintains the IP address ");
#endif
            type = 0;
            OLD_allocated_ip[0] = DHCP_allocated_ip[0];
            OLD_allocated_ip[1] = DHCP_allocated_ip[1];
            OLD_allocated_ip[2] = DHCP_allocated_ip[2];
            OLD_allocated_ip[3] = DHCP_allocated_ip[3];
            DHCP_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] != DHCP_allocated_ip[0] ||
               OLD_allocated_ip[1] != DHCP_allocated_ip[1] ||
               OLD_allocated_ip[2] != DHCP_allocated_ip[2] ||
               OLD_allocated_ip[3] != DHCP_allocated_ip[3]) {
                ret = DHCP_IP_CHANGED;
                dhcp_ip_update();
#ifdef _DHCP_DEBUG_
                eth_printf(">IP changed.");
#endif
            }
#ifdef _DHCP_DEBUG_
            else
                eth_printf(">IP is continued.");
#endif
            reset_DHCP_timeout();
            dhcp_state = STATE_DHCP_LEASED;
        } else if(type == DHCP_NAK) {
#ifdef _DHCP_DEBUG_
            eth_printf("> Receive DHCP_NACK, Failed to maintain ip");
#endif
            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:
                //					eth_printf("<<timeout>> state : STATE_DHCP_DISCOVER");
                send_DHCP_DISCOVER();
                break;

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

                send_DHCP_REQUEST();
                break;

            case STATE_DHCP_REREQUEST:
                //					eth_printf("<<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, (uint8_t*)"CHECK_IP_CONFLICT", 17, DHCP_allocated_ip, 5000);

    // RCR value restore
    setRCR(tmp);

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

#ifdef _DHCP_DEBUG_
        eth_printf("\r\n> Check leased IP - OK");
#endif

        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(DHCP_CHADDR);
    if((DHCP_CHADDR[0] | DHCP_CHADDR[1] | DHCP_CHADDR[2] | DHCP_CHADDR[3] | DHCP_CHADDR[4] |
        DHCP_CHADDR[5]) == 0x00) {
        // assigning temporary mac address, you should be set SHAR before call this function.
        DHCP_CHADDR[0] = 0x00;
        DHCP_CHADDR[1] = 0x08;
        DHCP_CHADDR[2] = 0xdc;
        DHCP_CHADDR[3] = 0x00;
        DHCP_CHADDR[4] = 0x00;
        DHCP_CHADDR[5] = 0x00;
        setSHAR(DHCP_CHADDR);
    }

    DHCP_SOCKET = s; // SOCK_DHCP
    pDHCPMSG = (RIP_MSG*)buf;
    DHCP_XID = 0x12345678;
    {
        DHCP_XID += DHCP_CHADDR[3];
        DHCP_XID += DHCP_CHADDR[4];
        DHCP_XID += DHCP_CHADDR[5];
        DHCP_XID += (DHCP_CHADDR[3] ^ DHCP_CHADDR[4] ^ DHCP_CHADDR[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++;
}

void getIPfromDHCP(uint8_t* ip) {
    ip[0] = DHCP_allocated_ip[0];
    ip[1] = DHCP_allocated_ip[1];
    ip[2] = DHCP_allocated_ip[2];
    ip[3] = DHCP_allocated_ip[3];
}

void getGWfromDHCP(uint8_t* ip) {
    ip[0] = DHCP_allocated_gw[0];
    ip[1] = DHCP_allocated_gw[1];
    ip[2] = DHCP_allocated_gw[2];
    ip[3] = DHCP_allocated_gw[3];
}

void getSNfromDHCP(uint8_t* ip) {
    ip[0] = DHCP_allocated_sn[0];
    ip[1] = DHCP_allocated_sn[1];
    ip[2] = DHCP_allocated_sn[2];
    ip[3] = DHCP_allocated_sn[3];
}

void getDNSfromDHCP(uint8_t* ip) {
    ip[0] = DHCP_allocated_dns[0];
    ip[1] = DHCP_allocated_dns[1];
    ip[2] = DHCP_allocated_dns[2];
    ip[3] = DHCP_allocated_dns[3];
}

uint32_t getDHCPLeasetime(void) {
    return dhcp_lease_time;
}

char NibbleToHex(uint8_t nibble) {
    nibble &= 0x0F;
    if(nibble <= 9)
        return nibble + '0';
    else
        return nibble + ('A' - 0x0A);
}