omc_c_last1.c

本文是基于Linux的udp协议的简单网络编程。能实现简单的收发数据功能。

/*最终的程序，加上了‘把输出的内容写到文件’这一部分*/
#include<sys/types.h>
#include<sys/socket.h>
#include<stdio.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<string.h>
#include<netdb.h>

#define LOCAL_SERVER_PORT 8092
#define MAX_MSG 100

int main(int argc, char *argv[])
{
  int s, rc, i, n, j, k ;
  struct sockaddr_in cliAddr,remoAddr,recevAddr;
  char msg[MAX_MSG];
  char msg1[3];
  FILE *fp;
  int strlen=3;
 
  s=socket(AF_INET, SOCK_DGRAM, 0);
  if(s<0)
  {
    printf("%s:cannot open socket\n",argv[0]);
    exit(1);
  }

   remoAddr.sin_family=AF_INET;
   remoAddr.sin_port=htons(LOCAL_SERVER_PORT);
   remoAddr.sin_addr.s_addr=inet_addr("192.168.2.222");
   k=0x04;
   
   fp=fopen("res.txt","w+");
   if(fp==NULL)
   {
     printf("cannot open a file");
     exit(1);
   }

   for(i=0;i<5;i++)
   {
    memset(msg1,0,30);
    memcpy(msg1,&strlen,2);
    msg1[2]=k;
    k++;
  //printf("%02x\n%02x\n%02x\n",msg1[0],msg1[1],msg1[2]);
    rc=sendto(s, msg1,sizeof(msg1), 0,(struct sockaddr *) &remoAddr, sizeof(remoAddr));
    if(rc<0)
    {
      printf("%s: cannot send data %d \n",argv[0],i-1);
      close(s);
      exit(1);
    }

    memset(msg, 0x0, MAX_MSG);
    j=sizeof(cliAddr);
    n=recvfrom(s, msg, MAX_MSG, 0, (struct sockaddr *) &cliAddr, &j);
    if(n<0)
    {
      printf("%s cannot receive data\n",argv[0]);
      exit(1);
    }
    
    fwrite(msg,sizeof(char),100,fp);
    fputc('\n',fp);
//  printf("%s\n",msg);
  }
   fclose(fp);
   return 1;

}