如何忽略自己的广播 udp 数据包 [英] How to ignore your own broadcast udp packets

问题描述

对于以下我假设有一张网卡.

For the following I'm assuming one network card.

我的程序中有一个组件，旨在让子网中的其他人知道它的存在.为此，我实现了一个解决方案，每当程序启动时(以及之后定期)，它都会向 INADDR_BROADCAST 发送广播 - 侦听所需端口的任何人都会记住它来自哪里以备后用.

I have a component of my program which is designed to let others in the subnet know of its existence. For this, I've implemented a solution where whenever the program starts up (and periodically afterwards) it sends a broadcast to INADDR_BROADCAST - whoever listens on the required port will remember where it came from for later use.

问题在于我不想记住我自己的广播.我认为理论上这很容易做到 - 只需找出本地 ip 并与您在 recvfrom 中获得的内容进行比较.

The problem with this is that I don't want to remember my own broadcasts. I thought that in theory this would be easy to do - simply find out the local ip and compare to what you get in recvfrom.

但是，我发现获取本地 IP 很困难:getaddrinfo with NULL 返回 127.0.0.1, getaddrinfo 与主机名返回公共 IP.任何人都可以指出我找到实际子网ip的方向吗?我想我一定在这里遗漏了一些非常明显的东西，但好吧......我仍然错过它:)

However, I've found it difficult to get the local IP: getaddrinfo with NULL returns 127.0.0.1, getaddrinfo with the hostname returns the public ip. Can anyone point me in the direction of finding the actual subnet ip ? I think I must be missing something very obvious here but well... I'm still missing it :)

注意:我已经阅读了关于广播的其他 SO 问题，特别是这个问题:UDP-在所有接口上广播，但我还没有解决多接口问题.

Note: I've read other SO questions on broadcasts, in particular this one: UDP-Broadcast on all interfaces but I haven't gotten round to the multiple interface issue yet.

推荐答案

好吧，在启动时，您可以使用随机(但跟踪)值广播不同的消息，然后等待该消息，以发现您自己的地址，从那时起开启，您可以发送普通消息，忽略您的消息来源.

Well at start-up you could broadcast a different message with random (but tracked) value, then wait for that message, to discover your own address, from then on, you can send normal messages, ignoring your sourced messages.

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