如何设置Winsock UDP套接字？

问题描述

我想创建一个只发送数据到客户端的Winsock UDP套接字。我想要内核为我选择一个可用的端口。另一方面，我想指出使用哪个本地IP，因为我运行几个nics。

I want to create a Winsock UDP socket that only sends data to a client. I want the kernel to choose an available port for me. On the other hand, I want to indicate which local IP to use, since I'm running a few nics.

我试过梳理通过迷宫的套接字选项，以及绑定与套接字地址设置为0的端口无效。

I've tried combing through the maze of socket options, as well as binding with the port in the socket address set to 0 to no avail.

我的代码在Win32 C ++中。

My code is in Win32 C++.

推荐答案

请原谅缺少错误检查：

char pkt[...];
size_t pkt_length = ...;
sockaddr_in dest;
sockaddr_in local;
WSAData data;
WSAStartup( MAKEWORD( 2, 2 ), &data );

local.sin_family = AF_INET;
local.sin_addr.s_addr = inet_addr( <source IP address> );
local.sin_port = 0; // choose any

dest.sin_family = AF_INET;
dest.sin_addr.s_addr = inet_addr( <destination IP address> );
dest.sin_port = htons( <destination port number> );

// create the socket
SOCKET s = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
// bind to the local address
bind( s, (sockaddr *)&local, sizeof(local) );
// send the pkt
int ret = sendto( s, pkt, pkt_length, 0, (sockaddr *)&dest, sizeof(dest) );

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