selectclient.cc

// selectclient.c -- socket client using select()
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define MAXDATASIZE 1000 // max number of bytes we can get at once

int main(int argc, char *argv[])
{
    int sockfd, numbytes;
    char buf[MAXDATASIZE];
    struct addrinfo hints, *servinfo;
    int rv;
    char s[INET_ADDRSTRLEN];
    fd_set          master, read_fds;
    int             fd_max

    if (argc != 3)
    {
        fprintf(stderr, "usage: %s hostname portnum\n", argv[0]);
        exit(1);
    }
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    
    if ((rv = getaddrinfo(argv[1], argv[2], &hints, &servinfo)) != 0)
    {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }
    if ((sockfd = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol)) == -1)
    {
        perror("client: socket");
        return 2;
    }
    if (connect(sockfd, servinfo->ai_addr, servinfo->ai_addrlen) == -1)
    {
        close(sockfd);
        perror("client: connect");
        return 2;
    }
    inet_ntop(servinfo->ai_family, &((struct sockaddr_in *)servinfo->ai_addr) - > sin_addr, s, sizeof s);
    printf("client: connecting to %s\n", s);
    freeaddrinfo(servinfo); // all done with this structure


    if (send(sockfd, buf, strlen(buf), 0) == -1)
    {
        perror("send");
        close(sockfd);
        exit(1);
    }
    if ((numbytes = recv(sockfd, buf, sizeof buf, 0)) == -1)
    {
        perror("recv");
        close(sockfd);
        exit(1);
    }
    buf[numbytes] = '\0';
    printf("client: received '%s'\n", buf);
    close(sockfd);
    return 0;
}