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@talebook
Created March 20, 2014 11:24
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完整示例代码,研究连接失败时poll()的返回值。
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <unistd.h>
#include <poll.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define ASYNC_CONTINUE() ( errno == EAGAIN || errno == EINTR || errno == EINPROGRESS)
int fcntl_enable(int sockfd, int feature)
{
int flags = fcntl(sockfd, F_GETFL, 0);
if ( flags < 0 )
{
return flags;
}
int ret = fcntl(sockfd, F_SETFL, flags | feature );
if ( ret < 0 )
{
return ret;
}
return 0;
}
int async_socket()
{
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if ( sockfd < 0 )
{
fprintf(stderr, "socket fail: %m");
return sockfd;
}
int ret = fcntl_enable(sockfd, O_NONBLOCK);
if ( ret < 0 )
{
fprintf(stderr, "fcntl enable nonblock fail: %m");
close(sockfd);
return ret;
}
return sockfd;
}
int async_connect(int sockfd, const char* host, short port)
{
struct sockaddr_in servaddr;
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(port);
inet_pton(AF_INET, host, &servaddr.sin_addr);
int ret = connect(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr));
if ( ret < 0 and not ASYNC_CONTINUE() )
{
fprintf(stderr, "connect to [%s:%d] fail: %m", host, port);
return ret;
}
return 0;
}
int async_net(const char* host, short port)
{
int sockfd = async_socket();
if ( sockfd < 0 )
{
return sockfd;
}
int ret =async_connect(sockfd, host, port);
if ( ret < 0 )
{
close(sockfd);
return ret;
}
return sockfd;
}
int connection_refused()
{
int sockfd = async_net("127.0.0.1", 11111);
struct pollfd pfd;
pfd.fd = sockfd;
pfd.events = POLLIN|POLLOUT;
int ready = poll(&pfd, 1, -1);
printf("ready=%d, POLLIN=%d, POLLOUT=%d, POLLERR=%d\n",
ready,
( pfd.revents&POLLIN ) != 0,
( pfd.revents&POLLOUT ) != 0,
( pfd.revents&POLLERR ) != 0);
int error;
socklen_t errlen = sizeof(error);
getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &errlen);
printf("error=%d, msg=%s\n",
error, strerror(error) );
return 0;
}
int main(int argc, const char *argv[])
{
connection_refused();
return 0;
}
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