iphone - 地址可达性 - 服务器和端口 - iOS 5

Question

我正在尝试检查服务器是在线还是离线:我遇到的问题是它在连接时有一个端口

我目前的代码:

struct sockaddr_in address;
address.sin_len = sizeof(address);
address.sin_family = AF_INET;
address.sin_port = htons(25667);
address.sin_addr.s_addr = inet_addr("fr7.mooshroom.net");

Reachability *reachability = [Reachability reachabilityWithAddress:&address];

请让我知道我做错了什么。并且请不要将我链接到其他问题，我已经搜索过但没有一个有我要找的东西。

Answer 1

inet_addr() 函数基本上不会为您做域名解析。您需要向其传递一个 IP 地址(例如 127.0.0.1)。

要将 DNS 名称解析为 IP 地址，您需要查看标准的 gethostbyname() 函数。

澄清一下:

struct hostent *host = gethostbyname("fr7.mooshroom.net");
if (host) {
    struct in_addr in;
    NSLog(@"HOST: %s" , host->h_name);
    while (*host->h_addr_list)
    {
        bcopy(*host->h_addr_list++, (char *) &in, sizeof(in));
        NSLog(@"IP: %s", inet_ntoa(in));
    }
}

现在，说了这么多，您确定这会如您所愿吗？ SCNetworkReachabilityRef 的文档建议不要:

http://developer.apple.com/library/ios/#documentation/SystemConfiguration/Reference/SCNetworkReachabilityRef/Reference/reference.html

"A remote host is considered reachable when a data packet, sent by an application into the network stack, can leave the local device. Reachability does not guarantee that the data packet will actually be received by the host."