#include  <Source/os.h>                                         /* OS header.                                           */
 
#include  <IP/IPv4/net_ipv4.h>
#include  <Source/net_type.h>
#include  <Source/net_ip.h>
#include  <Source/dhcp-c.h>
 
CPU_BOOLEAN  AppDHCPc_Init (NET_IF_NBR      if_nbr,
                            NET_IPv4_ADDR  *p_addr_cfgd,
                            NET_IPv4_ADDR  *p_addr_dns)
{
    DHCPc_STATUS      status;
    CPU_BOOLEAN       done;
    DHCPc_OPT_CODE    req_param[DHCPc_CFG_PARAM_REQ_TBL_SIZE];
    CPU_INT08U        req_param_qty;
    NET_IPv4_ADDR     addr_tbl[NET_IPv4_CFG_IF_MAX_NBR_ADDR];
    NET_IP_ADDRS_QTY  addr_ip_tbl_qty;
    CPU_INT16U        size;
    OS_ERR            err_os;
    NET_ERR           err_net;
    DHCPc_ERR         err;

                                                                /* --------------- INITIALIZE uC/DHCPc ---------------- */
    err = DHCPc_Init();                                         /* See Note #1.                                         */
    if (err != DHCPc_ERR_NONE) {
        return (DEF_FAIL);
    }

                                                                /* ---------- CFG DHCPC PARAMETER REQUESTED ----------- */
    req_param[0]   = DHCP_OPT_DOMAIN_NAME_SERVER;               /* Obtain DNS address. See Note #2                      */
    req_param_qty  = 1u;                                        /* 1 parameter requested.                               */

                                                                /* ----------- START DHCPC ON THE INTERFACE ----------- */
    DHCPc_Start(if_nbr, req_param, req_param_qty, &err);        /* See Note #3.                                         */
    if (err != DHCPc_ERR_NONE) {
        return (DEF_FAIL);
    }

                                                                /* ------- WAIT UNTIL THE PROCESS IS COMPLETED -------- */
    done = DEF_NO;
    while (done == DEF_NO) {
        OSTimeDlyHMSM(0, 0, 0, 200, OS_OPT_TIME_DLY, &err_os);  /* TODO change following OS API. See Note #4.           */
        status = DHCPc_ChkStatus(if_nbr, &err);                 /* Check DHCP status. See Note #5.                      */
        switch (status) {
            case DHCP_STATUS_CFG_IN_PROGRESS:                   /* See Note 5a.                                         */
                 break;

            case DHCP_STATUS_CFGD:                              /* See Note 5b.                                         */
            case DHCP_STATUS_CFGD_NO_TMR:                       /* See Note 5c.                                         */
                 size = sizeof(NET_IPv4_ADDR);                  /* An address has been configured.                      */
                 DHCPc_GetOptVal(             if_nbr,           /* Get DNS address obtained by the DHCPc. See Note #6.  */
                                              DHCP_OPT_DOMAIN_NAME_SERVER,
                                (CPU_INT08U *)p_addr_dns,
                                             &size,
                                             &err);
                 /* Break intentionally omitted. */

            case DHCP_STATUS_CFGD_LOCAL_LINK:                   /* See Note 5d.                                         */
                 done = DEF_YES;
                 addr_ip_tbl_qty = sizeof(addr_tbl) / sizeof(NET_IPv4_ADDR);
                (void)NetIPv4_GetAddrHost(if_nbr,               /* See Note #7. Get current address configured.         */
                                         &addr_tbl[0],
                                         &addr_ip_tbl_qty,
                                         &err_net);
                 if (err_net != NET_IPv4_ERR_NONE) {
                     return (DEF_FAIL);
                 }
                *p_addr_cfgd = addr_tbl[0];
                 break;

            case DHCP_STATUS_FAIL:                              /* See Note #5e. No address has been configured.        */
                 DHCPc_Stop(if_nbr, &err);
                 return (DEF_FAIL);

            default:
                 break;
        }
    }
    return (DEF_OK);
}

1. Prior to any call to DHCPc, the module must be initialized. If the process is successful, the DHCP client’s tasks are started, and its various data structures are initialized.
    

2. It is possible to request additional parameters from the DHCP server by setting a DHCPc options table, which must be passed to start function. Note that the server will not necessarily transmit those parameters.
    

3. Start the DHCP management of the interfaces. Note that the interface is not configured yet upon returning from this function.
    

4. An OS time delay must be applied between each call to DHCP to allow other task to run.
    

5. Once the DHCP management of an interface has been started, the application may want to check the status of the lease negotiation in order to determine whether or not the interface has been properly configured:
    

   1. Status DHCP_STATUS_CFG_IN_PROGRESS means that the negotiation is still underway.
      
      

   2. Status DHCP_STATUS_CFGD indicates that the DHCP negotiation is done and that the interface is properly configured.

   3. Status DHCP_STATUS_CFGD_NO_TMR specifies that the DHCP negotiation is done and that the interface is properly configured, but no timer has been set for renewing the lease. The effect of this is that the lease is going to be permanent, even though the server might have set a time limit for it.

   4. Status DHCP_STATUS_CFGD_LOCAL_LINK means that the DHCP negotiation was not successful, and that a link-local address has been attributed to the interface. It is important to note that the DHCP client will not try to negotiate a lease with a server at this point.

   5. Status DHCP_STATUS_FAIL denotes a negotiation error. At this point, the application should call the DHCPc_Stop() function and decide what to do next.
       

6. Once the DHCP negotiation is completed successfully, it is possible to retrieve the parameters requested during the start. If the function returns an error an invalid value, it means that the server might have not transmitted the requested parameters.
    

7. It is possible to retrieve the address configured by the DHCP client by calling the appropriate TCP/IP stack API.