System.Net.IPAddress返回奇怪的地址 [英] System.Net.IPAddress returning weird addresses

问题描述

我正在编写一个(相当简单的:)网络应用程序，并使用localhost:27488(127.0.0.1:27488)对其进行测试.
我正在使用System.Net.Sockets.TcpClient进行连接，需要一个System.Net.IPAddress来指定主机...唯一的是，我不知道如何使用正确的IP地址初始化该类.我查看了MSDN文档，并说该地址需要Byte(4)或Int64(long).
当我像这样初始化IPAddress时，探查是:

I am writing a (rather simple :) networking application, and am testing it using localhost:27488 (127.0.0.1:27488).
I am using a System.Net.Sockets.TcpClient for the connection, which takes a System.Net.IPAddress to specify the host... the only thing is, I can't figure out how to initialize the class with the right IP address. I went over the MSDN docs and it says it takes either a Byte(4) or an Int64 (long) for the address.
The probelm is, when I initialize the IPAddress like this:

Dim ipAddr As New System.Net.IPAddress(127001)

它将地址返回为25.240.1.0.根据我对文档的了解，127001应该返回127.0.0.1 ...也许我在那儿错过了什么? http://msdn.microsoft.com/en-us/library/13180abx.aspx

it returns the address as 25.240.1.0. From what I understand from the docs, 127001 should return 127.0.0.1... Maybe I missed something there? http://msdn.microsoft.com/en-us/library/13180abx.aspx

推荐答案

简短的答案:请改用TcpClient.Connect(String，Int);它接受IPv4/IPv6地址或主机名/别名，因此您不仅限于IP连接.例如:

Short answer: use TcpClient.Connect( String, Int ) instead; it accepts an IPv4/IPv6 address or hostname/alias, so you are not limited to connecting by IP. e.g.:

Dim client As TcpClient
client.Connect( "localhost", 27488 )
client.Connect( "127.0.0.1", 27488 )

但是25.240.1.0是从哪里来的呢?请尝试以下操作:

But where did 25.240.1.0 come from? Try the following:

• 打开Calc，切换到Programmer视图，然后选择Dec
• 键入127001，然后切换到十六进制
• 写出结果，在左边加零以填充到4个字节/32位:0001F019
• 将该数字分成单个字节:00 01 F0 19
• 颠倒字节顺序:19 F0 01 00
• 将每个字节转换回十进制:25 240 1 0
• 带点:25.240.1.0

• Open Calc, switch to Programmer view, select Dec
• Type in 127001, then switch to Hex
• Write out the result, adding zeroes on the left to pad to 4 bytes/32 bits: 0001F019
• Separate that number into individual bytes: 00 01 F0 19
• Reverse the byte order: 19 F0 01 00
• Convert each byte back to decimal: 25 240 1 0
• With dots: 25.240.1.0

为什么要反转字节?您的处理器架构为低端字节序；数字以最低有效字节在前的形式表示在内存中. IPv4地址已标准化为big-endian格式(最高有效字节在前；也称为网络顺序). IPAddress( Int64 )构造函数正在反转字节，以从LE转换为BE.

Why reverse the bytes? Your processor architecture is little-endian; numbers are represented in memory with the least significant byte first. IPv4 addresses are standardized to big-endian format (most significant byte first; a.k.a. network order). The IPAddress( Int64 ) constructor is reversing the bytes to convert from LE to BE.

与上述步骤相反，在IPAddress( Int64 )构造函数中，回送的正确值应为&H0100007F(十六进制)或16777343(十进制).

Reversing the steps above, the correct value for loopback in the IPAddress( Int64 ) constructor would be &H0100007F (hex) or 16777343 (decimal).

IPAddress( Byte[4] )构造函数按网络顺序获取字节数组，因此将为New Byte() { 127, 0, 0, 1 }

The IPAddress( Byte[4] ) constructor takes the byte array in network order, so that would be New Byte() { 127, 0, 0, 1 }

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