udp协议编程举例

/******************************************************************************

 

 

********************************************************************************/
#include
#include
#include
#include
#include
#include
#include
#include

#define LOCAL_SERVER_PORT 1500
#define MAX_MSG 100

 

int main(int argc, char *argv[])
{
 int sd,rc,n,cliLen;
 struct sockaddr_in cliAddr,servAddr;
 char msg[MAX_MSG];
 
 sd = socket(AF_INET,SOCK_DGRAM,0);
 if(sd<0)
 {
  printf("%s:cannot open socket \n",argv[0]);
  exit(1);
 }
 
 serAddr.sin_family = AF_INET;
 serAddr.sin_addr.s_addr=htonl(INADDR_ANY);
 serAddr.sin_port =htons(LOCAL_SERVER_PORT);
 rc = bind(sd,(struct sockaddr *) &serAddr,sizeof(serAddr));
 
 if(rc<0)
 {
  printf("%s:cannot bind port number %d\n",argv[0],LOCAL_SERVER_PORT);
  exit(1);
 }
 printf("%s:waiting for data on port UDP%u\n",argv[0],LOCAL_SERVER_PORT);
 
 
 while(1)
 {
  memset(nsg,0x0,MAX_MSG);
  
  cliLen=sizeof(cliAddr);
  /*******receiving message*********/
  n=recvfrom(sd,msg,MAX_MSG,0,(struct sockaddr *)&cliAddr,&cliLen);
  if(n<0)
  {
   printf("%s:cannot receive data\n",argv[0]);
   continue;
  }
  /*******print the received message*********/
  
  printf("%s:from %s:UDP%u:%s\n",argv[0],inet_ntoa(cliAddr.sin_addr),ntohs(cliAddr.sin_port),msg);
  
 }
}

／＊＊＊＊＊＊＊＊＊＊＊＊Client******************/

/******************************************************************************

 

 

********************************************************************************/
#include
#include
#include
#include
#include
#include
#include
#include
#include

#define REMOTE_SERVER_PORT 1500
#define MAX_MSG 100

 

int main(int argc, char *argv[])
{
 int sd,rc,i;
 struct sockaddr_in cli_Addr,remote_Serv_Addr;
 struct hostent *h;
    if(argc<3)
    {
     printf("usage : %s....\n",argv[0]);
     exit(1);
    }
    h=gethostbyname(argv[1]);
 if(h==NULL)
 {
  printf("%s: unknown host '%s'\n",argv[0],argv[1]);
  exit(1);
 }
    printf("%s:sending data to '%s'(ip:%s)\n",argv[0],h->h_name,inet_ntoa(*(struct in_addr *)h->h_addr_list[0]));
 remote_Serv_Addr.sin_family =h->h_addrtype;
    memcpy((char *)&remote_Serv_Addr.sin_addr.s_addr,h->h_addr_list[0],h->h_length);
 remote_Serv_Addr.sin_port=htons(REMOTE_SERVER_PORT);

    sd = socket(AF_INET,SOCK_DGRAM,0);
 if(sd<0)
 {
  printf("%s:cannot open socket \n",argv[0]);
  exit(1);
 }
 
 cli_Addr.sin_family = AF_INET;
 cli_Addr.sin_addr.s_addr=htonl(INADDR_ANY);
 cli_Addr.sin_port =htons(0);
 rc = bind(sd,(struct sockaddr *) &cli_Addr,sizeof(cli_Addr));
 
 if(rc<0)
 {
  printf("%s:cannot bind port number %d\n",argv[0],LOCAL_SERVER_PORT);
  exit(1);
 }
 
 for(i=2;i {
  rc = sendto(sd,argv[i],strlen(argv[i]+1,0,(struct sockaddr *)&remote_Serv_Addr,sizeof(remote_Serv_Addr));
  if(rc<0)
  {
   printf("%s:cannot send data %d\n",argv[0],i-1);
   close(sd);
   exit(1);
  }
 }
}