/** @file */#ifndef __LWIP_DHCP_H__#define __LWIP_DHCP_H__#include "lwip/opt.h"#include "lwip/netif.h"#include "lwip/udp.h"/** period (in seconds) of the application calling dhcp_coarse_tmr() */#define DHCP_COARSE_TIMER_SECS 60 /** period (in milliseconds) of the application calling dhcp_fine_tmr() */#define DHCP_FINE_TIMER_MSECS 500 struct dhcp{  /** current DHCP state machine state */  u8_t state;  /** retries of current request */  u8_t tries;  /** transaction identifier of last sent request */   u32_t xid;  /** our connection to the DHCP server */   struct udp_pcb *pcb;  /** (first) pbuf of incoming msg */  struct pbuf *p;  /** incoming msg */  struct dhcp_msg *msg_in;  /** incoming msg options */  struct dhcp_msg *options_in;   /** ingoing msg options length */  u16_t options_in_len;  struct pbuf *p_out; /* pbuf of outcoming msg */  struct dhcp_msg *msg_out; /* outgoing msg */  u16_t options_out_len; /* outgoing msg options length */  u16_t request_timeout; /* #ticks with period DHCP_FINE_TIMER_SECS for request timeout */  u16_t t1_timeout;  /* #ticks with period DHCP_COARSE_TIMER_SECS for renewal time */  u16_t t2_timeout;  /* #ticks with period DHCP_COARSE_TIMER_SECS for rebind time */  struct ip_addr server_ip_addr; /* dhcp server address that offered this lease */  struct ip_addr offered_ip_addr;  struct ip_addr offered_sn_mask;  struct ip_addr offered_gw_addr;  struct ip_addr offered_bc_addr;  u32_t offered_t0_lease; /* lease period (in seconds) */  u32_t offered_t1_renew; /* recommended renew time (usually 50% of lease period) */  u32_t offered_t2_rebind; /* recommended rebind time (usually 66% of lease period)  *//** Patch #1308 *  TODO: See dhcp.c "TODO"s */#if 0  struct ip_addr offered_si_addr;  u8_t *boot_file_name;#endif};/* MUST be compiled with "pack structs" or equivalent! */#ifdef PACK_STRUCT_USE_INCLUDES#  include "arch/bpstruct.h"#endifPACK_STRUCT_BEGIN/** minimum set of fields of any DHCP message */struct dhcp_msg{  PACK_STRUCT_FIELD(u8_t op);  PACK_STRUCT_FIELD(u8_t htype);  PACK_STRUCT_FIELD(u8_t hlen);  PACK_STRUCT_FIELD(u8_t hops);  PACK_STRUCT_FIELD(u32_t xid);  PACK_STRUCT_FIELD(u16_t secs);  PACK_STRUCT_FIELD(u16_t flags);  PACK_STRUCT_FIELD(u32_t ciaddr);  PACK_STRUCT_FIELD(u32_t yiaddr);  PACK_STRUCT_FIELD(u32_t siaddr);  PACK_STRUCT_FIELD(u32_t giaddr);#define DHCP_CHADDR_LEN 16U  PACK_STRUCT_FIELD(u8_t chaddr[DHCP_CHADDR_LEN]);#define DHCP_SNAME_LEN 64U  PACK_STRUCT_FIELD(u8_t sname[DHCP_SNAME_LEN]);#define DHCP_FILE_LEN 128U  PACK_STRUCT_FIELD(u8_t file[DHCP_FILE_LEN]);  PACK_STRUCT_FIELD(u32_t cookie);#define DHCP_MIN_OPTIONS_LEN 68U/** allow this to be configured in lwipopts.h, but not too small */#if ((!defined(DHCP_OPTIONS_LEN)) || (DHCP_OPTIONS_LEN < DHCP_MIN_OPTIONS_LEN))/** set this to be sufficient for your options in outgoing DHCP msgs */#  define DHCP_OPTIONS_LEN DHCP_MIN_OPTIONS_LEN#endif  PACK_STRUCT_FIELD(u8_t options[DHCP_OPTIONS_LEN]);} PACK_STRUCT_STRUCT;PACK_STRUCT_END#ifdef PACK_STRUCT_USE_INCLUDES#  include "arch/epstruct.h"#endif/** start DHCP configuration */err_t dhcp_start(struct netif *netif);/** stop DHCP configuration */void dhcp_stop(struct netif *netif);/** enforce lease renewal */err_t dhcp_renew(struct netif *netif);/** inform server of our IP address */void dhcp_inform(struct netif *netif);/** if enabled, check whether the offered IP address is not in use, using ARP */#if DHCP_DOES_ARP_CHECKvoid dhcp_arp_reply(struct netif *netif, struct ip_addr *addr);#endif/** to be called every minute */void dhcp_coarse_tmr(void);/** to be called every half second */void dhcp_fine_tmr(void); /** DHCP message item offsets and length */#define DHCP_MSG_OFS (UDP_DATA_OFS)    #define DHCP_OP_OFS (DHCP_MSG_OFS + 0)  #define DHCP_HTYPE_OFS (DHCP_MSG_OFS + 1)  #define DHCP_HLEN_OFS (DHCP_MSG_OFS + 2)  #define DHCP_HOPS_OFS (DHCP_MSG_OFS + 3)  #define DHCP_XID_OFS (DHCP_MSG_OFS + 4)  #define DHCP_SECS_OFS (DHCP_MSG_OFS + 8)  #define DHCP_FLAGS_OFS (DHCP_MSG_OFS + 10)  #define DHCP_CIADDR_OFS (DHCP_MSG_OFS + 12)  #define DHCP_YIADDR_OFS (DHCP_MSG_OFS + 16)  #define DHCP_SIADDR_OFS (DHCP_MSG_OFS + 20)  #define DHCP_GIADDR_OFS (DHCP_MSG_OFS + 24)  #define DHCP_CHADDR_OFS (DHCP_MSG_OFS + 28)  #define DHCP_SNAME_OFS (DHCP_MSG_OFS + 44)  #define DHCP_FILE_OFS (DHCP_MSG_OFS + 108)#define DHCP_MSG_LEN 236#define DHCP_COOKIE_OFS (DHCP_MSG_OFS + DHCP_MSG_LEN)#define DHCP_OPTIONS_OFS (DHCP_MSG_OFS + DHCP_MSG_LEN + 4)#define DHCP_CLIENT_PORT 68  #define DHCP_SERVER_PORT 67/** DHCP client states */#define DHCP_REQUESTING 1#define DHCP_INIT 2#define DHCP_REBOOTING 3#define DHCP_REBINDING 4#define DHCP_RENEWING 5#define DHCP_SELECTING 6#define DHCP_INFORMING 7#define DHCP_CHECKING 8#define DHCP_PERMANENT 9#define DHCP_BOUND 10/** not yet implemented #define DHCP_RELEASING 11 */#define DHCP_BACKING_OFF 12#define DHCP_OFF 13 #define DHCP_BOOTREQUEST 1#define DHCP_BOOTREPLY 2#define DHCP_DISCOVER 1#define DHCP_OFFER 2#define DHCP_REQUEST 3#define DHCP_DECLINE 4#define DHCP_ACK 5#define DHCP_NAK 6#define DHCP_RELEASE 7#define DHCP_INFORM 8#define DHCP_HTYPE_ETH 1#define DHCP_HLEN_ETH 6#define DHCP_BROADCAST_FLAG 15#define DHCP_BROADCAST_MASK (1 << DHCP_FLAG_BROADCAST)/** BootP options */#define DHCP_OPTION_PAD 0#define DHCP_OPTION_SUBNET_MASK 1 /* RFC 2132 3.3 */#define DHCP_OPTION_ROUTER 3 #define DHCP_OPTION_HOSTNAME 12#define DHCP_OPTION_IP_TTL 23#define DHCP_OPTION_MTU 26#define DHCP_OPTION_BROADCAST 28#define DHCP_OPTION_TCP_TTL 37#define DHCP_OPTION_END 255/** DHCP options */#define DHCP_OPTION_REQUESTED_IP 50 /* RFC 2132 9.1, requested IP address */#define DHCP_OPTION_LEASE_TIME 51 /* RFC 2132 9.2, time in seconds, in 4 bytes */#define DHCP_OPTION_OVERLOAD 52 /* RFC2132 9.3, use file and/or sname field for options */#define DHCP_OPTION_MESSAGE_TYPE 53 /* RFC 2132 9.6, important for DHCP */#define DHCP_OPTION_MESSAGE_TYPE_LEN 1#define DHCP_OPTION_SERVER_ID 54 /* RFC 2132 9.7, server IP address */#define DHCP_OPTION_PARAMETER_REQUEST_LIST 55 /* RFC 2132 9.8, requested option types */#define DHCP_OPTION_MAX_MSG_SIZE 57 /* RFC 2132 9.10, message size accepted >= 576 */#define DHCP_OPTION_MAX_MSG_SIZE_LEN 2#define DHCP_OPTION_T1 58 /* T1 renewal time */#define DHCP_OPTION_T2 59 /* T2 rebinding time */#define DHCP_OPTION_CLIENT_ID 61#define DHCP_OPTION_TFTP_SERVERNAME 66#define DHCP_OPTION_BOOTFILE 67/** possible combinations of overloading the file and sname fields with options */#define DHCP_OVERLOAD_NONE 0#define DHCP_OVERLOAD_FILE 1#define DHCP_OVERLOAD_SNAME  2#define DHCP_OVERLOAD_SNAME_FILE 3#endif /*__LWIP_DHCP_H__*/