Unix网络编程 高级IO套接字设置超时

标签：高级io套接字设置超时   unix网络编程   

　　上述这三个技术都适用于输入和输出操作(read、write，及其变体recv/send, readv/writev, recvfrom, sendto)。不过我们也期待可以用于connect的技术，因为TCP内置的connect超时相当长(典型值为75秒)，而我们在写服务器程序的时候，也不会希望一个连接的建立需要花费这么长时间。select可用来在connect上设置超时的先决条件是相应的套接字是非阻塞的，而那两个套接字选项对connect并不适用；同时也应当指出，前两个技术适用于任何描述符，而第三个技术仅仅适用于套接字描述符。

>>>>使用select对connect设置超时：

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/select.h>
#include <time.h>
#define PORT 9900
#define MAXDATASIZE 5000

int main(int argc, char **argv)
{
    int    sockfd, nbytes;
    char   buf[1024];
    struct hostent *he;
    struct sockaddr_in servaddr;

    if(argc != 2) {
        perror("Usage:client hostname\n");
        return 0;
    }
    if((he = gethostbyname(argv[1])) == NULL) {
        perror("gethostbyname");
        return 0;
    }
    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("create socket error");
        return 0;
    }
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(PORT);
    servaddr.sin_addr = *((struct in_addr *)he->h_addr);
    fcntl(sockfd, F_SETFL, O_NONBLOCK);
    timeval timeout = {3, 0};
    if(connect(sockfd, (SA*)&servaddr, sizeof(struct sockaddr)) == -1) {
        if(errno != EINPROGRESS) {
            close(sockfd);
            perror("connect error");
            return 0;
        }
    }
 
    fd_set readSet;
    FD_ZERO(&readSet);
    FD_ZERO(&writeSet);
    FD_SET(sockfd, &writeSet);
    int ret = select(sockfd+1, &readSet, &writeSet, NULL, &timeout);
    printf("%d", ret);    
}  

#include <unp.h>

static void connect_alarm(int);

int
connect_timeo(int sockfd, const SA* saptr, socklen_t salen, int nsec)
{
    Sigfunc* sigfunc;
    int      n;
    
    sigfunc = Signal(SIGALRM, connect_alarm);
    if(alarm(nsec) != 0) 
        err_msg("connect_timeo: alarm was already set");
    if((n = connect(sockfd, saptr, salen)) < 0) {
        close(sockfd);
        if(errno == EINTR)
            errno = ETIMEOUT;
    }
    alarm(0);     /* turn off the alarm */
    Signal(SIGALRM, sigfunc);   /* restore previous signal handler */
    
    return (n);
}

static void
connect_alarm(int signo)
{
    return ;   /* just interrupt the connect() */
}

#include <unp.h>

static void sig_alarm(int);

void
dig_cli(FILE* fp, int sockfd, const SA* pservaddr, socklen_t servlen)
{
    int  n;
    char sendline[MAXLINE], recvline[MAXLINE+1];
    
    Signal(SIGALRM, sig_alarm);
    
    while(Fgets(sendline, MAXLINE, fp) != NULL) {
        Sendto(sockfd, sendline, strlen(sendline), 0, preservaddr, serlen);
        alarm(5);   /* set TIMEOUT 5 seconds */
        if((n = recvfrom(sockfd, recvline, MAXLINE, 0, NULL, NULL)) < 0) {
            if(errno == EINTR)
                fprintf(stderr, "socket timeout\n");
            else 
                err_sys("recvfrome error");
        }else {
            alarm(0);  /* if success then turn off the alarm */
            recvline[n] = 0;  /* null terminate */
            Fputs(recvline, stdout);
        }
    }
}

static void
sig_alarm(int signo)
{
    return ;   /* just interrupt the recvfrom() */
}

#include <unp.h>

int
readable_timeo(int fd, int sec)
{
    fd_set   rset;
    struct   timeval tv;
    
    FD_ZERO(&rset);   /* reset the file discriptor set */
    FD_SET(fd, &rset);
    
    tv.tv_sec = sec;  /* set struct timeval */
    tv.tv_usec = 0;
    
    return (select(fd+1, &rset, NULL, NULL, &tv));
}

#include <unp.h>

void
dig_cli(FILE* fp, int sockfd, const SA* pservaddr, socklen_t servlen)
{
    int  n;
    char sendline[MAXLINE], recvline[MAXLINE+1];
    
    while(Fgets(sendline, MAXLINE, fp) != NULL) {
        Sendto(sockfd, sendline, strlen(sendline), 0, preservaddr, serlen);
        if(readable_timeo(sockfd, 5) == 0) {
            fprintf(stderr, "socket timeout\n");
        } else {
            n = recvfrom(sockfd, recvline, MAXLINE, 0, NULL, NULL);
            recvline[n] = 0;  /* null terminate */
            Fputs(recvline, stdout);
        }
    }
}

#include <unp.h>

void
dig_cli(FILE* fp, int sockfd, const SA* pservaddr, socklen_t servlen)
{
    int    n;
    char   sendline[MAXLINE], recvline[MAXLINE+1];
    struct timeval tv;
    
    tv.tv_sec = 5;
    tv.tv_usec = 0;
    Setsockopt(sockfd, SOL_SOCKET, &tv, sizeof(tv));
    
    while(Fgets(sendline, MAXLINE, fp) != NULL) {
            
        Sendto(sockfd, sendline, strlen(sendline), 0, preservaddr, serlen);
        
        n = recvfrom(sockfd, recvline, MAXLINE, 0, NULL, NULL);
        if(n < 0) {
            if(errno == EWOULDBLOCK) {
                fprintf(stderr, "socket timeout\n");
                continue;
            }else 
                err_sys("recvfrom error");
        }
            
        recvline[n] = 0;  /* null terminate */
        Fputs(recvline, stdout);
    }
}

Unix网络编程 高级IO套接字设置超时

标签：高级io套接字设置超时   unix网络编程   

原文地址：http://blog.csdn.net/keshacookie/article/details/41245161