CLIENT SERVER COMMUNICATION USING TCP SOCKET

Client server system that uses the socket interface to send messages over TCP connection

ALGORITHM:

SERVER

· Start the program.

· Inside the main function, create an instance of server.

· Create a socket using socket function. Pass the domain AF_INET to indicate IPV4 protocol and the type as SOCK_STREAM to indicate stream socket. On success, the socket function returns a small non-negative int value called socket descriptor that is stored on integer variable.

· Set the values of address structure as zero using bzero(). Initialize family as AF_INET, the IP address using htonl() function and port using htons(). Use bind() function to bind the socket to server address.

· Use the listen() function to define how many connections can be pending on socket.

· Use the accept() function which is called by a TCP server to return the next completed connection from the front of completed connection queue. The client address and address returns the protocol address of the connected peer processes.

· Issue a write protocol to send the message to the client.

CLIENT

· Check if the number of arguments is equal to 3.

· Create a socket using socket function with family as AF_INET and type as SOCK_STREAM.

· Set the values of address structure as zero using bzero().

· Initialize family as AF_INET and the port number that is passed as an argument.

· Use the connect() function to set up connection with server. The address parameter refers to the remote address.

· Obtain the message entered by the user with the help of scanf() function. Write this using write() function.

· Read() function is then used to read the message from the server and print it.

· Stop the program.



PROGRAM:

SERVER

#include<stdio.h>

#include<sys/socket.h>

#include<netinet/in.h>

#include<stdlib.h>

#include<unistd.h>

#include<netdb.h>

#include<string.h>

#include<arpa/inet.h>

#include<sys/types.h>

int main()

{

int socketmain,socketclient,child,port=5050,len=81;

struct sockaddr_in serv,clientaddr;

socklen_t clientlen;

if((socketmain=socket(AF_INET, SOCK_STREAM,0))<0)

{

printf("Server cannot open socket \n");

exit(0);

}

bzero(&serv,sizeof(serv));

serv.sin_family=AF_INET;

serv.sin_addr.s_addr=htonl(INADDR_ANY);

serv.sin_port=htons(port);

if((bind(socketmain,(struct sockaddr*)&serv, sizeof(serv)))<0)

{

printf("Server bind failed \n");

exit(1);

}

listen(socketmain,5);

if((socketclient=accept(socketmain, (struct sockaddr *)&clientaddr, &clientlen))<0)

{

printf("Client is bad \n");

exit(0);

}

char buf[len];

bzero(buf,len);

int n=read(socketclient,buf,100);

printf("Message is %s \n",buf);

strcpy(buf,"bye");

write(socketclient,buf,100);

}















CLIENT

#include<stdio.h>

#include<sys/socket.h>

#include<netinet/in.h>

#include<stdlib.h>

#include<unistd.h>

#include<netdb.h>

#include<string.h>

#include<arpa/inet.h>

#include<sys/types.h>

int main(int argc,char **argv)

{

int sockfd,n,port=4500;

struct sockaddr_in serv;

char buf[100],msg[100];

if(argc!=3)

{

printf("Invalid format");

exit(0);

}

if((sockfd=socket(AF_INET,SOCK_STREAM,0))<0)

{

printf("\n Socket cannot be opened");

exit(0);

}

bzero(&serv, sizeof(serv));

serv.sin_family=AF_INET;

serv.sin_port=htons(atoi(argv[2]));

if(connect(sockfd,(struct sockaddr*)&serv,sizeof(serv))<0)

{

printf("\n Connection failed");

exit(0);

}

printf("Connected \n");

printf("Enter message to server");

scanf("%s",buf);

write(sockfd,buf,100);

n=read(sockfd,msg,100);

printf("Server message is %s \n",msg);

}






OUTPUT:

./server

Message is hi

bye

./client 127.0.0.1 5050

Connected

Enter message to server hi

Server message is bye