LWIP 客户端 DHCP

LWIP 要实现DHCP功能步骤：

1）打开DHCP开关：   #define LWIP_DHCP               1

2）调用函数 dhcp_start(struct netif *netif)

3）检测是否接收到服务器分配的IP

uint8_t check_DHCP_success(struct netif *netif)
{
if(netif->dhcp->offered_ip_addr.addr!=0&&netif->dhcp->offered_sn_mask.addr!=0&&netif->dhcp->offered_gw_addr.addr!=0&&netif->dhcp->server_ip_addr.addr!=0)
                {
 
             

IP4_ADDR(&ipaddr，(netif->dhcp->offered_ip_addr.addr&0x000000ff), (netif->dhcp->offered_ip_addr.addr&0x0000ff00)>>8, (netif->dhcp->offered_ip_addr.addr&0x00ff0000)>>16, (netif->dhcp->offered_ip_addr.addr&0xff000000)>>24）;

IP4_ADDR(&gw, (netif->dhcp->offered_gw_addr.addr&0x000000ff), (netif->dhcp->offered_gw_addr.addr&0x0000ff00)>>8, (netif->dhcp->offered_gw_addr.addr&0x00ff0000)>>16, (netif->dhcp->offered_gw_addr.addr&0xff000000)>>24);

                 IP4_ADDR(&netmask,  (netif->dhcp->offered_sn_mask.addr&0x000000ff), (netif->dhcp->offered_sn_mask.addr&0x0000ff00)>>8, (netif->dhcp->offered_sn_mask.addr&0x00ff0000)>>16, (netif->dhcp->offered_sn_mask.addr&0xff000000)>>24);
                                        
                
               IP4_ADDR(&addrCmdRecv, (netif->dhcp->server_ip_addr.addr&0x000000ff), (netif->dhcp->server_ip_addr.addr&0x0000ff00)>>8, (netif->dhcp->server_ip_addr.addr&0x00ff0000)>>16, (netif->dhcp->server_ip_addr.addr&0xff000000)>>24);
                
         
                         
                    netif_set_addr(netif,&ipaddr, &netmask, &gw);
              netif_set_default(netif);
          netif_set_up(netif);

   
          return 1;

      }
                
            else
                
            
            return 0;

}

注：由于DHCP采用的是UDP和服务器进行通信，所以有可能需要多次调用函数 dhcp_start(struct netif *netif)