385

gistfile1.txt

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <string.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;
    char buffer[256];
    if (argc < 2) {
       fprintf(stderr,"%s portnumber \n", argv[0]);
       exit(0);
    }
    portno = atoi(argv[1]);
    printf("using port: %d", portno);  
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0){
        perror("ERROR opening socket");
        exit(-1);
    }
    server = gethostbyname("127.0.0.1");
    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
    memset( &serv_addr,0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) {
        perror("ERROR connecting");
        exit(-1);
    }
    n = write(sockfd,"hello",strlen("hello"));
    if (n < 0) {
         perror("ERROR writing to socket");
        exit(-1);
    }
    n = read(sockfd,buffer,255);
    if (n < 0) {
         perror("ERROR reading from socket");
        exit(-1);
    }
    printf("%s\n",buffer);
    close(sockfd);
    return 0;
}