client server communication using UDP socket programming

http://cjuschools.blogspot.in/

/*udp server.c*/

#include<unistd.h>
#include<sys/socket.h>
#include<stdio.h>
#include<string.h>
#include<netinet/in.h>
#include<sys/types.h>

#include<errno.h>
#define MAXLINE 5555
void main(int argc,char *argv[])
{
  int sockfd,n;
  unsigned short port;
  socklen_t len;
   char mesg[1024];
   struct sockaddr_in servaddr,cliaddr;
   port=(unsigned short)atoi(argv[1]);
   if((sockfd=socket(AF_INET,SOCK_DGRAM,0))<0)
   printf("error in socket creation");
   bzero(&servaddr,sizeof(servaddr));
   servaddr.sin_family=AF_INET;
   servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
   servaddr.sin_port=htons(port);
   len=sizeof(servaddr);
   if(bind(sockfd,(struct sockaddr *)&servaddr,len)<0)
   perror("\nbind");

  for(;;)
   {
   len=sizeof(cliaddr);
     n=recvfrom(sockfd,&mesg,MAXLINE,0,(struct sockaddr *)&cliaddr,&len);
     sendto(sockfd,&mesg,n,0,(struct sockaddr *)&cliaddr,len);
}
 
}


output:
/home/anil/~ cc udpserver.c
/home/anil/~ ./a.out 4455 
-

/*open another new terminal for udp client program*/
                  /*udpclient.c*/

#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#include<errno.h>
#define MAXLINE 5566

void main(int argc,char **argv[])
{

  int sockfd,n,len;
   char mesg[1024];
   unsigned short port;
  char sendline[MAXLINE],recvline[MAXLINE];
   struct sockaddr_in servaddr;
   if((sockfd=socket(AF_INET,SOCK_DGRAM,0))<0)
   {
     perror("socket");
   }
   bzero(&servaddr,sizeof(servaddr));
   servaddr.sin_family=AF_INET;
   port=(unsigned short)atoi(argv[1]);

   servaddr.sin_port=htons(port);
   if((inet_pton(AF_INET,argv[2],&servaddr.sin_addr))<0)
   {
    perror("inet_pton");
   }
   len=sizeof(servaddr);
  while(fgets(sendline,MAXLINE,stdin)!=NULL)
  {
 
    sendto(sockfd,&sendline,strlen(sendline),0,(struct sockaddr *)&servaddr,len);
   n=recvfrom(sockfd,&recvline,MAXLINE,0,(struct sockaddr *)&servaddr,&len);
   recvline[n]=0;

    printf("\n %s",recvline);
  }
}

output:

/home/anil/~ cc udpclient.c
/home/anil/~ ./a.out 4455 127.0.0.1

hi

hi

hello

hello



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