20. Simple UDP Client-Server.txt

UDP SERVER

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<strings.h>

void error(char* msg)
{
  perror(msg);
  exit(0);
}

int main(int argc,char* argv[])
{
   int sockfd,n,portno,clilen;
   struct sockaddr_in seraddr,cliaddr;
   char buffer[256];

   if(argc<2)
   {
       printf("No port number given\n");
       exit(0);
   }

   portno=atoi(argv[1]);

   bzero(&seraddr,sizeof(seraddr));
   seraddr.sin_family=AF_INET;
   seraddr.sin_addr.s_addr=INADDR_ANY;
   seraddr.sin_port=htons(portno);

   sockfd=socket(AF_INET,SOCK_DGRAM,0);
   if(sockfd<0)
      error("Error in Creating socket");
   bind(sockfd,(struct sockaddr*)&seraddr,sizeof(seraddr));
clilen=sizeof(cliaddr);
  n=recvfrom(sockfd,buffer,256,0,(struct sockaddr*)&cliaddr,&clilen);
   if(n==0) error("Error in reading");
   buffer[n]='\0';
   printf("Message received from server - %s",buffer);
   close(sockfd);
 }
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UDP CLIENT

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<strings.h>
#include<string.h>

void error(char* msg)
{
  perror(msg);
  exit(0);
}

int main(int argc,char* argv[])
{
   int sockfd,n,portno;
   struct sockaddr_in seraddr;
   char buffer[256];

   if(argc<3)
   {
       printf("No IP address & Port No given\n");
       exit(0);
   }

   portno=atoi(argv[2]);

   bzero(&seraddr,sizeof(seraddr));
   seraddr.sin_family=AF_INET;
   inet_pton(AF_INET,argv[1],&seraddr.sin_addr);
   seraddr.sin_port=htons(portno);

   sockfd=socket(AF_INET,SOCK_DGRAM,0);
   if(sockfd<0)
      error("Error in Creating socket");
   bzero(buffer,256);
   printf("Enter message for client :");
   fgets(buffer,256,stdin);
   n=sendto(sockfd,buffer,strlen(buffer),0,(struct sockaddr*)&seraddr, sizeof(seraddr));
   if(n==0) error("Error in writing");
   printf("Message send to client - %s",buffer);
   close(sockfd);
 }