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;

}