IPAddress从NSData使用Bonjour NSNetService在MonoTouch？

Question

我使用iOS上的Xamarin +iOS浏览网络上的web服务器，然后从网络中下载文件。

传递给“解决”事件处理程序的NSNetService包含作为NSData的地址。我找不到一种很好的方法将这个NSData转换成一个实际的IP地址，然后我可以从它构建一个网址，即http:// < IPAddress >/IPAddress/file.htm。

这是我的NSNetService.AddressResolved事件处理程序：

private void OnServiceResolved(object sender, EventArgs args)
{
        NSNetService service = (NSNetService)sender;
        // service.Port is valid.
        // service.HostName is valid.
        // but we want the IP addres, which is in service.Addresses.
        // None of the following four methods works quite right.
        IPAddress address = (IPAddress)service.Addresses [0]; // Cannot convert type NSData to IPAddress
        SocketAddress address2 = (SocketAddress)service.Addresses[0]; // Cannot convert NSData to SocketAddress. A binary copy might work?
        IPHostEntry entry = (IPHostEntry)service.Addresses [0]; // Cannot convert NSData to IPHostEntry
        IPHostEntry entry2 = Dns.GetHostByName (service.HostName); // This kinda works, but is dumb. Didn't we just resolve?
}

在解析事件中从NSNetService获取服务IP地址的正确方法是什么？

Answer 1

NSNetService.Addresses属性提供NSData实例，这些实例必须转换为IPAddress (或其他.NET类型)可以消化的内容。例如。

MemoryStream ms = new MemoryStream ();
(ns.Addresses [0] as NSData).AsStream ().CopyTo (ms);
IPAddress ip = new IPAddress (ms.ToArray ());

请注意，这可以返回IPv6地址(或IPAddress不接受的格式)。您可能需要迭代所有的Addresses以找到最好的一个。

我将考虑在Xamarin.iOS的未来版本中添加一种方便的方法。

更新

返回一个IPAddress的更完整的版本如下所示：

static IPAddress CreateFrom (NSData data)
{
    byte[] address = null;
    using (MemoryStream ms = new MemoryStream ()) {
        data.AsStream ().CopyTo (ms);
        address = ms.ToArray ();
    }
    SocketAddress sa = new SocketAddress (AddressFamily.InterNetwork, address.Length);
    // do not overwrite the AddressFamily we provided
    for (int i = 2; i < address.Length; i++)
        sa [i] = address [i];
    IPEndPoint ep = new IPEndPoint (IPAddress.Any, 0);
    return (ep.Create (sa) as IPEndPoint).Address;
}