如何设置 Winsock UDP 套接字?
我想创建一个只向客户端发送数据的 Winsock UDP 套接字.我希望内核为我选择一个可用的端口.另一方面，我想指出要使用哪个本地 IP，因为我正在运行一些网卡.
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.
我尝试过梳理套接字选项的迷宫，以及将套接字地址中的端口绑定设置为 0，但均无济于事.
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.
我的代码是 Win32 C++.
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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