如何在Visual C++中,根据URL解析主机IP地址?
我不确定是否有一个特定的C++类来进行主机名查询,但是您可以始终使用纯C来完成这些任务。这是我的版本,可在Linux、Mac OS X和Windows上编译和运行。
#include <stdio.h>
#ifdef _WIN32
# include "winsock.h"
#else
# include <netdb.h>
# include <arpa/inet.h>
#endif
static void initialise(void)
{
#ifdef _WIN32
WSADATA data;
if (WSAStartup (MAKEWORD(1, 1), &data) != 0)
{
fputs ("Could not initialise Winsock.\n", stderr);
exit (1);
}
#endif
}
static void uninitialise (void)
{
#ifdef _WIN32
WSACleanup ();
#endif
}
int main (int argc, char *argv[])
{
struct hostent *he;
if (argc == 1)
return -1;
initialise();
he = gethostbyname (argv[1]);
if (he == NULL)
{
switch (h_errno)
{
case HOST_NOT_FOUND:
fputs ("The host was not found.\n", stderr);
break;
case NO_ADDRESS:
fputs ("The name is valid but it has no address.\n", stderr);
break;
case NO_RECOVERY:
fputs ("A non-recoverable name server error occurred.\n", stderr);
break;
case TRY_AGAIN:
fputs ("The name server is temporarily unavailable.", stderr);
break;
}
}
else
{
puts (inet_ntoa (*((struct in_addr *) he->h_addr_list[0])));
}
uninitialise ();
return he != NULL;
}
编译完成后,将主机名作为参数提供:
$ ./a.out stackoverflow.com
69.59.196.211
gethostbyname
已被getaddrinfo
取代。静态缓冲区?仅限IPv4?加入21世纪吧!:P - asveikau要在Windows下使用套接字函数,您需要首先调用 WSAStartup
,指定您想要的Winsock版本(对于您的目的,1.1将很好地工作)。然后,您可以调用gethostbyname
以获取主机的地址。完成后,应调用WSACleanup。将所有内容组合在一起,您将得到以下内容:
#include <windows.h>
#include <winsock.h>
#include <iostream>
#include <iterator>
#include <exception>
#include <algorithm>
#include <iomanip>
class use_WSA {
WSADATA d;
WORD ver;
public:
use_WSA() : ver(MAKEWORD(1,1)) {
if ((WSAStartup(ver, &d)!=0) || (ver != d.wVersion))
throw(std::runtime_error("Error starting Winsock"));
}
~use_WSA() { WSACleanup(); }
};
int main(int argc, char **argv) {
if ( argc < 2 ) {
std::cerr << "Usage: resolve <hostname>";
return EXIT_FAILURE;
}
try {
use_WSA x;
hostent *h = gethostbyname(argv[1]);
unsigned char *addr = reinterpret_cast<unsigned char *>(h->h_addr_list[0]);
std::copy(addr, addr+4, std::ostream_iterator<unsigned int>(std::cout, "."));
}
catch (std::exception const &exc) {
std::cerr << exc.what() << "\n";
return EXIT_FAILURE;
}
return 0;
}
操作简单:
在Linux系统上:
#include <stdio.h>
#include <netdb.h>
#include <arpa/inet.h>
int main()
{
struct hostent *he=gethostbyname("www.stackoverflow.com");
char *ip=inet_ntoa(*(struct in_addr*)he->h_addr_list[0]);
printf(ip);
}
#include <stdio.h>
#include <winsock.h>
int main()
{
WSADATA wsaData;
WSAStartup(MAKEWORD(2,2),&wsaData);
struct hostent *he=gethostbyname("www.stackoverflow.com");
char *ip=inet_ntoa(*(struct in_addr*)he->h_addr_list[0]);
printf(ip);
}
在Android上
#include <stdio.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/socket.h>
int main()
{
struct hostent *he=gethostbyname("www.stackoverflow.com");
char *ip=inet_ntoa(*(struct in_addr*)he->h_addr_list[0]);
printf(ip);
}
编译 Android 应用
在 arch-arm 上使用以下标志:-Wl,-s -lz -rdynamic -fPIE -pie
完成后,通过 adb 运行它。
adb push <binfile> /data/local/tmp
adb shell /data/local/tmp/<binfile>
struct hostent *he;
if ((he = gethostbyname("localhost") == NULL) {
// Handle error: Failed
}
IP地址将在he->h_addr
中。适用于Windows、Linux,很可能也适用于macOS。
解析URL以获取主机名。然后调用gethostbyname或平台上对应的API来获取IP地址。如果您正在解析HTTP头,请查找HostName标头以确定主机名。
gethostbyname
?