#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netdb.h>
#include <errno.h>
#include <unistd.h>
#include <arpa/inet.h>
void safe_close(int &sock);
int main(int argc, char *argv[]) {
int sockfd = 0, n = 0;
socklen_t len = 0;
char host[512] = {0};
char buf[1024] = {0};
struct hostent *server;
struct sockaddr_in serv_addr, loc_addr;
if (argc < 2) {
printf(“please input host name\n”);
exit(-1);
}
strncpy(host, argv[1], sizeof(host));
server = gethostbyname(host);// 判断输入的域名是否正确
if (null == server) {
printf(“find host: %s failed.\n”, host);
exit(-1);
}
if (-1 == (sockfd = socket(af_inet, sock_stream, 0))) {// 创建socket
memset(buf, 0, sizeof(buf));
snprintf(buf, sizeof(buf), “new socket failed. errno: %d, error: %s”, errno, strerror(errno));
perror(buf);
exit(-1);
}
memset(&serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family = af_inet;
serv_addr.sin_port = htons(80);// http标准端口号
memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);
if (-1 == inet_pton(af_inet, host, &serv_addr.sin_addr)) {
memset(buf, 0, sizeof(buf));
snprintf(buf, sizeof(buf), “inet_pton failed. errno: %d, error: %s”, errno, strerror(errno));
perror(buf);
exit(-1);
}
if (-1 == connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr))) {// 连接socket
memset(buf, 0, sizeof(buf));
snprintf(buf, sizeof(buf), “connect socket failed. errno: %d, error: %s”, errno, strerror(errno));
perror(buf);
exit(-1);
}
printf(“connect to %s success.\n”, host);
len = sizeof(sizeof(loc_addr));
memset(&loc_addr, 0, len);
if (-1 == getsockname(sockfd, (struct sockaddr *)&loc_addr, &len)) {// 获取socket绑定的本地address信息
memset(buf, 0, sizeof(buf));
snprintf(buf, sizeof(buf), “get socket name failed. errno: %d, error: %s”, errno, strerror(errno));
perror(buf);
safe_close(sockfd);
exit(-1);
}
if (loc_addr.sin_family == af_inet) {// 打印信息
printf(“local port: %u\n”, ntohs(loc_addr.sin_port));
}
safe_close(sockfd);
return 0;
}
void safe_close(int &sock) {
if (-1 != sock) {
shutdown(sock, shut_rdwr);
sock = -1;
}
}