Program For Implementing the TCP client and Server

     C program to implemet TCP Server

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <string.h>
int main(void)
{
    int s, len;
    char buf[BUFSIZ];
    struct sockaddr_in remote_addr;
    memset(&remote_addr, 0, sizeof(remote_addr));
    remote_addr.sin_family = AF_INET;
    remote_addr.sin_addr.s_addr = inet_addr(“127.0.0.1″);
    remote_addr.sin_port = htons(8000);
    if( (s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        printf(“Error\n”);
        return -1;
    }
    if( connect(s, (struct sockaddr*)&remote_addr, sizeof(struct sockaddr)) < 0 )
    {
        printf(“Error\n”);
        return -1;
    }
    printf(“Connection established\n”);
    len = recv(s, buf, BUFSIZ, 0);
    buf[len] = ”;
    printf(“%s\n”, buf);
    while(1)
    {
        printf(“Enter text: “);
        scanf(“%s%”, buf);
        if( !strcmp(buf, “quit”) )
        break;
        len = send(s, buf, strlen(buf), 0);
        len = recv(s, buf, BUFSIZ, 0);
        buf[len] = ”;
        printf(“From server: %s\n”, buf);
    }
    close(s);
    return 0;
}


/*  C program to implemet TCP Client*/

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <string.h>
 
int main(void)
{
        char buf[BUFSIZ], ubuf[BUFSIZ];
        int s, fd, len;
        int sin_size;
        struct sockaddr_in my_addr;
        struct sockaddr_in remote_addr;
 
        memset(&my_addr, 0, sizeof(my_addr));
        my_addr.sin_family = AF_INET;
        my_addr.sin_addr.s_addr = INADDR_ANY;
        my_addr.sin_port = htons(8000);
 
        if( (s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        {
               printf("Error\n");
               return -1;
        }
 
        if( bind(s, (struct sockaddr*)&my_addr, sizeof(struct sockaddr))  < 0)
        {
               printf("Error\n");
               return -1;
        }
 
        listen(s, 6);
 
        sin_size = sizeof(struct sockaddr_in);
        if( (fd = accept(s, (struct sockaddr*)&remote_addr, &sin_size)) < 0 )
        {
               buf[len] = '';
               buf[0] = toupper(buf[0]);
               send(fd, buf, len, 0);
        }
 
        close(fd);
        close(s);
        return 0;
}