我有一个简单的程序来检查端口是否打开,但我想缩短套接字连接的超时长度,因为默认值太长。但我不知道该怎么做。代码如下:
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int main(int argc, char **argv) {
u_short port; /* user specified port number */
char addr[1023]; /* will be a copy of the address entered by u */
struct sockaddr_in address; /* the libc network address data structure */
short int sock = -1; /* file descriptor for the network socket */
if (argc != 3) {
fprintf(stderr, "Usage %s <port_num> <address>", argv[0]);
return EXIT_FAILURE;
}
address.sin_addr.s_addr = inet_addr(argv[2]); /* assign the address */
address.sin_port = htons(atoi(argv[2])); /* translate int2port num */
sock = socket(AF_INET, SOCK_STREAM, 0);
if (connect(sock,(struct sockaddr *)&address,sizeof(address)) == 0) {
printf("%i is open\n", port);
}
close(sock);
return 0;
}
最佳答案
将套接字设置为非阻塞,并使用select()
(它需要一个超时参数)。如果非阻塞套接字正在尝试连接,则当 connect()
完成(成功或不成功)时,select()
将指示该套接字可写。然后,您使用 getsockopt()
确定 connect()
的结果:
int main(int argc, char **argv) {
u_short port; /* user specified port number */
char *addr; /* will be a pointer to the address */
struct sockaddr_in address; /* the libc network address data structure */
short int sock = -1; /* file descriptor for the network socket */
fd_set fdset;
struct timeval tv;
if (argc != 3) {
fprintf(stderr, "Usage %s <port_num> <address>\n", argv[0]);
return EXIT_FAILURE;
}
port = atoi(argv[1]);
addr = argv[2];
address.sin_family = AF_INET;
address.sin_addr.s_addr = inet_addr(addr); /* assign the address */
address.sin_port = htons(port); /* translate int2port num */
sock = socket(AF_INET, SOCK_STREAM, 0);
fcntl(sock, F_SETFL, O_NONBLOCK);
connect(sock, (struct sockaddr *)&address, sizeof(address));
FD_ZERO(&fdset);
FD_SET(sock, &fdset);
tv.tv_sec = 10; /* 10 second timeout */
tv.tv_usec = 0;
if (select(sock + 1, NULL, &fdset, NULL, &tv) == 1)
{
int so_error;
socklen_t len = sizeof so_error;
getsockopt(sock, SOL_SOCKET, SO_ERROR, &so_error, &len);
if (so_error == 0) {
printf("%s:%d is open\n", addr, port);
}
}
close(sock);
return 0;
}
关于C:socket连接超时,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58306145/