program using select

["Lakshmi Gopinath" <lakbala@xxxxxxxx>]

/* MULTIPLEXING SOCKETS USING SELECT */ 

#include<stdlib.h>
#include<netinet/in.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<sys/select.h>
#include<sys/time.h>
#define max(a,b) ((a) > (b) ? (a) : (b))
#define PORTA 8000
#define PORTB 6000

struct sockaddr_in  serv_addr1,serv_addr2,client;
int main()
{
  int sockfd1,sockfd2,count=0,length=0,maxfd1;
  char buff1[128],buff2[128];
  fd_set set;
  struct timeval time;
  socklen_t addrlen=sizeof(client);
  FD_ZERO(&set);
  time.tv_sec = 5;
  time.tv_usec = 0;
  printf("reciever running\n");
  serv_addr1.sin_family=AF_INET;
  serv_addr1.sin_addr.s_addr=inet_addr("127.0.0.1");
  serv_addr1.sin_port=htons(PORTA);
  if((sockfd1=socket(AF_INET,SOCK_DGRAM,0))<0)
     write("I/O socket error/n");
  if((bind(sockfd1,(struct sockaddr *)&serv_addr1,sizeof(serv_addr1)))<0)
    printf("bind error/n");
  
   serv_addr2.sin_family=AF_INET;
  serv_addr2.sin_addr.s_addr=inet_addr("127.0.0.1");
  serv_addr2.sin_port=htons(PORTB);
  if((sockfd2=socket(AF_INET,SOCK_DGRAM,0))<0)
     write("I/O socket error/n");
  if((bind(sockfd2,(struct sockaddr *)&serv_addr2,sizeof(serv_addr2)))<0)
    printf("bind error/n");

  for(;;)
   {
      FD_SET(sockfd1,&set);
      FD_SET(sockfd2,&set);
      maxfd1 = max(sockfd1,sockfd2) + 1;
      select(maxfd1,&set,&set,NULL,&time);
      if(FD_ISSET(sockfd1,&set))
       {
         count = recvfrom(sockfd1,(char *)buff1,sizeof(buff1),0,
         (struct sockaddr *)&client,&addrlen);
         printf("\n %s ",buff1);
       }
       if(FD_ISSET(sockfd2,&set))
       {
         count = recvfrom(sockfd2,(char *)buff2,sizeof(buff2),0,
         (struct sockaddr *)&client,&addrlen);
         printf("\n %s ",buff2);
        }
 
   }
}