嵌入式 tcp或者udp发包协议使用结构体注意事项

注意：

1、使用结构体的时候，但一个成员是48字节，但是只用了32字节的时候在发送的字节里面是按照48发送而不是32！

 

/**
  recv broadcast run in the 3518c board
 **/

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <linux/in.h>
#include <stdlib.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <sys/ioctl.h>
 
 
#ifdef SOLARIS
#include <sys/sockio.h>
#endif

#define  PORT        18600
#define  CMD_HEAD_SIZE      12
#define  MAXINTERFACES       16
#define  MAX_LENGHT_16      16
#define  MAX_LENGHT_32      32
#define  MAX_LENGHT_128      128
#define  MAX_PAYLOAD_LEN     1400

#define  NET_LOOP_NAME      "lo"
#define  NET_ETHERNET_NAME     "eth"
#define  NET_WRILESS_NAME_RA   "ra"
#define  NET_WRILESS_NAME_WLAN    "wlan"

//#define JOSEPH_BROADCAST_ARM
//  common head  of search tool and ipnc

typedef struct commandHead
{
 int nEvent;
 int nPayloadLen;
 int nResved1;
 unsigned char ucPayload[MAX_PAYLOAD_LEN];
}commandHead;

// ipnc info
typedef struct ipncInfo
{
 char sIpncID[MAX_LENGHT_16];
 char mac[MAX_LENGHT_32];
 char sIP[MAX_LENGHT_16];
 char sVer[MAX_LENGHT_128];
}joseph_ipncInfo;

// event define
// search ipnc req
#define  JOSOPH_SEARCH_IPNC_REQ        0x00000001

// search  ack from ipnc
// payload: ipncInfo
#define  JOSOPH_SEARCH_IPNC_ACK        0x00000002

joseph_ipncInfo joseph_ipnc_info_net_device;

int get_device_mac_ip (argc, argv)
register int argc;
register char *argv[];
{
 register int fd, intrface, retn = 0;
 struct ifreq buf[MAXINTERFACES];
 struct arpreq arp;
 struct ifconf ifc;
 
 memset(&joseph_ipnc_info_net_device,0,sizeof(joseph_ipncInfo));
 
 if ((fd = socket (AF_INET, SOCK_DGRAM, 0)) >= 0)
 {
  ifc.ifc_len = sizeof buf;
  ifc.ifc_buf = (caddr_t) buf;
  
  if (!ioctl (fd, SIOCGIFCONF, (char *) &ifc))
  {
   /*set SIOCGIFCONF to get the info of net interface*/
   intrface = ifc.ifc_len / sizeof (struct ifreq);
   printf("Interface num is : Intrface = %d \n",intrface);
  
   /*get the ip and port of device depend on the value of interface*/
   while (intrface-- > 0)
   {
    /*get the name of net device*/
    printf ("net device %s\n", buf[intrface].ifr_name);

    /*Judge card type of net device*/
    if (!(ioctl (fd, SIOCGIFFLAGS, (char *) &buf[intrface])))
    {
     /*judge the misc mode of net device*/
     if (buf[intrface].ifr_flags & IFF_PROMISC)
     {
      puts ("the interface is PROMISC");
      retn++;
     }
    }

    /*judge the status of net device*/
    if (buf[intrface].ifr_flags & IFF_UP)
    {
     puts("the interface status is UP");
#ifdef JOSEPH_BROADCAST_ARM
     if((strstr(buf[intrface].ifr_name,NET_ETHERNET_NAME)) || ((strstr(buf[
intrface].ifr_name,NET_LOOP_NAME))))
#else     
     if((strstr(buf[intrface].ifr_name,NET_LOOP_NAME)))
#endif
     {
      continue;
     }

    }
    else
    {
     puts("the interface status is DOWN");
     break;
    }  
    
    /*get the ip of current net device*/
    if (!(ioctl (fd, SIOCGIFADDR, (char *) &buf[intrface])))
    {
     puts ("IP address is:");
     printf("%s",(char *)inet_ntoa((struct in_addr)((struct sockaddr_in*)(&buf
[intrface].ifr_addr))->sin_addr));
     sprintf(joseph_ipnc_info_net_device.sIP,"%s",(char *)inet_ntoa((struct
in_addr)((struct sockaddr_in*)(&buf[intrface].ifr_addr))->sin_addr));
     puts("");
    }

    /*get the mac of current net device*/
    if (!(ioctl (fd, SIOCGIFHWADDR, (char *) &buf[intrface])))
    {
     puts ("HW address is:");                
     printf("%02x:%02x:%02x:%02x:%02x:%02x\n",
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[0],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[1],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[2],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[3],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[4],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[5]);
     sprintf(joseph_ipnc_info_net_device.mac,"%02x:%02x:%02x:%02x:%02x:%02x",
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[0],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[1],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[2],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[3],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[4],
       (unsigned char)buf[intrface].ifr_hwaddr.sa_data[5]);
     puts("");
    }

   }
  }
 }
 else
  perror ("cpm: socket");   
 close (fd);
 return retn;
}

int joseph_fill_broadcas_pack(void)
{
 send_true_size = 0;
 
 /* get the info of net device*/
 get_device_mac_ip(); 

 strcpy(joseph_ipnc_info_net_device.sIpncID , "C0123456789");
 strcpy(joseph_ipnc_info_net_device.sVer , "V2.00.002 Build time 2014-04-29");
 printf("The Ip of broadcast server is : %s ,The size is %d\n",
joseph_ipnc_info_net_device.sIP,strlen(joseph_ipnc_info_net_device.sIP));

 printf("The Mac of joseph ipnc is : %s ,The size is %d\n",
joseph_ipnc_info_net_device.mac,strlen(joseph_ipnc_info_net_device.mac));

 printf("The Id of joseph ipnc  is : %s ,The size is %d\n",
joseph_ipnc_info_net_device.sIpncID,strlen(joseph_ipnc_info_net_device.sIpncID
));

 printf("The Bersion of joseph ipnc is : %s ,The size is %d\n",
joseph_ipnc_info_net_device.sVer,strlen(joseph_ipnc_info_net_device.sVer));
 
 printf("The listen port is is : %d  \n",PORT );

 return 0;
}

int main(int argc,char*argv[]){
 int ret=-1;
 int sock;

 /*addr of server*/
 struct sockaddr_in server_addr;
 /*addr of client*/
 struct sockaddr_in from_addr;
 commandHead broadcast_ack_buf_recv;
 commandHead broadcast_ack_buf_send;
 int from_len=sizeof(struct sockaddr_in);
 int count=-1;
 fd_set readfd;
 char buffer[MAX_PAYLOAD_LEN];
 struct timeval timeout;
 timeout.tv_sec=2;
 timeout.tv_usec=0;

 
 sock=socket(AF_INET,SOCK_DGRAM,0);
 if(sock<0){
  return;
 }

 memset((void*)&server_addr,0,sizeof(struct sockaddr_in));
 server_addr.sin_family=AF_INET;
 server_addr.sin_addr.s_addr=htons(INADDR_ANY);
 server_addr.sin_port=htons(PORT);
 
 /*bind the content of server to socket*/
 ret=bind(sock,(struct sockaddr*)&server_addr,sizeof(server_addr));
 if(ret<0){
  return;
 }
 
 joseph_fill_broadcas_pack();
 
 
 while(1){
  printf("=============================Recv Broadcast========================
===========\n");

  timeout.tv_sec=2;
  timeout.tv_usec=0;

  FD_ZERO(&readfd);
  FD_SET(sock,&readfd);
  ret=select(sock+1,&readfd,NULL,NULL,&timeout);
  
  printf("ret=%d\n",ret);
  
  switch(ret){
   case -1:
    break;
   case 0:
    printf("timeout\n");
    break;
   default:
    if(FD_ISSET(sock,&readfd)){
     
     /*from_addr is client info of net*/
     count=recvfrom(sock,&broadcast_ack_buf_recv,MAX_PAYLOAD_LEN,0,(struct
sockaddr*)&from_addr,&from_len);
     broadcast_ack_buf_recv.nEvent = ntohl(broadcast_ack_buf_recv.nEvent);
     
     if(broadcast_ack_buf_recv.nEvent == JOSOPH_SEARCH_IPNC_REQ){
      
      broadcast_ack_buf_send.nEvent = htonl(JOSOPH_SEARCH_IPNC_ACK);
      broadcast_ack_buf_send.nPayloadLen = htonl(sizeof(joseph_ipncInfo));
      
      /*analysis the ip and port of client*/
      printf("Client IP is %s\n",(char *)inet_ntoa(from_addr.sin_addr));
      printf("Client Send Port:%d\n",ntohs(from_addr.sin_port));
      memset(&broadcast_ack_buf_send.ucPayload,0,MAX_PAYLOAD_LEN);
      memcpy(&broadcast_ack_buf_send.ucPayload,&joseph_ipnc_info_net_device,
sizeof(joseph_ipncInfo));
      count=sendto(sock,&broadcast_ack_buf_send,(CMD_HEAD_SIZE+sizeof(
joseph_ipncInfo)),0,(struct sockaddr*)&from_addr,from_len);

      printf("The value of count is %d\n",count);

      if(count < 0)
      {
       printf("The value of count is %d\n",count);
      }
     }
     
    }
    break;
  }
 }

 close(sock);
 return;
}