Noblocking.cpp

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <errno.h>
#include <netdb.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

#define SERVPORT 80
#define MAXDATASIZE 100

int main(int argc, char *argv[])
{
    int sockfd, recvbytes;
    char rcv_buf[MAXDATASIZE]; /*./client 127.0.0.1 hello */
    char snd_buf[MAXDATASIZE];
    struct hostent *host; 
    
    /* struct hostent
    * {
    * char *h_name; // general hostname
    * char **h_aliases; // hostname's alias
    * int h_addrtype; // AF_INET
    * int h_length; 
    * char **h_addr_list;
    * };
    */

    struct sockaddr_in server_addr;
    int flags;
    int addr_len; 

    if (argc < 3)
    {
        printf("Usage:%s [ip address] [any string]\n", argv[0]);
        return 1;
    } 

    *snd_buf = '\0';
    strcat(snd_buf, argv[2]); 

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        perror("socket:");
        exit(1);
    }
 
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVPORT);
    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);
    memset(&(server_addr.sin_zero), 0, 8);
    addr_len = sizeof(struct sockaddr_in); 

    /* Setting socket to nonblock */
    flags = fcntl(sockfd, F_GETFL, 0);
    fcntl(sockfd, flags|O_NONBLOCK); 

    /* create the connection by socket 
    * means that connect "sockfd" to "server_addr"
    * 同步阻塞模式  
    */
    if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1)
    {
        perror("connect");
        exit(1);
    } 

    /* 同步非阻塞模式 */
    while (send(sockfd, snd_buf, sizeof(snd_buf), MSG_DONTWAIT) == -1)
    {
        sleep(10);
        printf("sleep\n");
    }
    printf("send:%s\n", snd_buf);

    /* 同步非阻塞模式 */
    while ((recvbytes = recv(sockfd, rcv_buf, MAXDATASIZE, MSG_DONTWAIT)) == -1)
    {
        sleep(10);
        printf("sleep\n");
    } 

    rcv_buf[recvbytes] = '\0';
    printf("recv:%s\n", rcv_buf); 

    close(sockfd);
    return 0;
}