c++ - 通过 SOCKS 代理发送 UDP 数据包

Question

我正在构建一个简单的应用程序，它应该通过 socks4/5 代理发送 UDP 数据报包。我使用 UDP 方法，所以我不必保持连接打开。

然而，这并不像我想的那么容易。根据这个模式，我得出结论，如果不先与代理服务器建立 TCP 连接，我就无法通过代理发送 UDP 数据。

尽管如此，我找不到在 CPP 中建立此类连接的任何合适示例。如果有任何资源，我将不胜感激 :)

Answer 1

这是可能的。根据 wikipedia，您必须在客户端连接请求的字段 2 中指定值 0x03。 SOCKS5协议(protocol)的描述。

The client's connection request is
field 1: SOCKS version number, 1 byte (must be 0x05 for this version)
field 2: command code, 1 byte:
0x01 = establish a TCP/IP stream connection
0x02 = establish a TCP/IP port binding
0x03 = associate a UDP port
field 3: reserved, must be 0x00
field 4: address type, 1 byte:
0x01 = IPv4 address
0x03 = Domain name
0x04 = IPv6 address
field 5: destination address of
4 bytes for IPv4 address
1 byte of name length followed by the name for Domain name
16 bytes for IPv6 address
field 6: port number in a network byte order, 2 bytes

正如 Hasturkun 指出的那样

Your code doesn't work because you aren't sending a connection request at all. You must send a UDP ASSOCIATE request (on the TCP connection), and you need to use the port and address from the response to get your datagrams relayed.

你真的应该看看Socks5 RFC