UDP:为两个不同的多播流监听同一个端口 [英] UDP: Listening to the same port for two different multicast streams

问题描述

我需要使用同一个端口监听 2 个不同的多播组.Program A 将从 230.0.0.1 监听，Program B 从 230.0.0.2 监听.两个多播组都使用相同的 port 2000，我无法控制它.

I need to listen to 2 different multicast groups using the same port. Program A will listen from 230.0.0.1 and Program B from 230.0.0.2. Both multicast groups use the same port 2000 and I have no control over it.

当我运行我的程序时，我在每个程序中都接收到多播流，即在 230.0.0.1 和 230.0.0.2 上广播的数据包.我怀疑问题出在公共端口上.这是我用来订阅多播的代码:

When I run my programs I receive both multicast streams in each program, that is both the data packets broadcasted on 230.0.0.1 and 230.0.0.2. I suspect the problem is due to the common port. This is the code I am using to subscribe to the multicast:

if( (sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0 ) {
  perror("socket");
  return -1;
}

if( setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0 ) {
  perror("setsockopt SO_REUSEADDR");
  return -1;
}

memset(&in_addr, 0, sizeof(in_addr));
in_addr.sin_family = AF_INET;
in_addr.sin_addr.s_addr = htonl(INADDR_ANY);
in_addr.sin_port = htons(2000);
if( bind(sd, (struct sockaddr*)&in_addr, sizeof(in_addr)) < 0 ) {
  perror("bind");
  return -1;
}

memset(&req, 0, sizeof(req));
inet_aton(intfc_ip, &req.imr_interface);
inet_aton("230.0.0.1", &req.imr_multiaddr);
if( setsockopt(sd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &req, sizeof(req)) < 0 ) {
  perror("setsockopt IP_ADD_MEMBERSHIP");
  return -1;
}

recv()...

如何过滤每个节目中的特定多播组?

How can I filter a specific multicast group in each program?

推荐答案

如果你改变了

in_addr.sin_addr.s_addr = htonl(INADDR_ANY);

到

inet_aton(<your wanted IP address>, &in_addr.sin_addr.s_addr);

你可以取得更大的成功.

you could have more success.

(如果您更改程序以使用 getaddrinfo()，你让它永不过时.)

(And if you change your program to work with getaddrinfo(), you make it future-proof.)

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