TCP/IP Client

// TCP/IP CLIENT
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

int main(int argc, char *argv[])
{
    int sockfd, port, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;
    char buffer[256];

    if(argc < 2){
        fprintf(stderr, "usage %s hostname port\n", argv[0]);
        return -1;
    }

    port = atoi(argv[2]);

    sockfd = socket(AF_INET, SOCK_STREAM, 0); // socket()
    if(sockfd < 0){
        puts("[-] Error: opening socket");
        return -1;
    }

    server = gethostbyname(argv[1]);
    if(server == NULL){
        puts("[-] Error: No such host");
        return -1;
    }

    memset((char*) &serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;

    memcpy((char*)&serv_addr.sin_addr.s_addr, (char*)server->h_addr, server->h_length);
    serv_addr.sin_port = htons(port);

    if(connect(sockfd, &serv_addr, sizeof(serv_addr)) < 0){ // connect()
        puts("[-] Error: Connect");
        return -1;
    }

    printf("Enter the message: ");
    memset(buffer, 0, 256);
    fgets(buffer, 255, stdin);

    n = write(sockfd, buffer, strlen(buffer)); // write()
    if(n < 0){
        puts("[-] Error: Write");
        return -1;
    }

    printf("%s\n", buffer);

    if(shutdown(sockfd, 2) < 0){ //close()
        puts("[-] Error: Close");
        return -1;
    }

    return 0;
}