结合之前在客户端code连接 [英] bind before connect at client code

问题描述

我有多个以太网的I / F。为eth0，eth1的，ETH2 ......我想连接到外部服务器，例如：1.2.3.4:80。

I have multiple ethernet I/Fs. eth0,eth1,eth2... and I want to connect to an external server, eg 1.2.3.4:80.

我的连接是正常的，但在某些特殊情况下我想连接为eth1，而不是eth0的。服务器的code盘我的接口的IP地址。我想，我需要先连接绑定。如果没有绑定（2）服务器总是得到文从eth0的

My connections are OK, but under some special circumstances I want to connect as eth1 and not eth0. the server's code checks the IP address of my interface. I think that I need to bind before connect. Without bind(2) the server always gets packets from eth0

我要寻找code，演示了这种行为。是否有人有一个链接到一个例子吗？

I am looking for code that demonstrates this behavior. Does anybody has a link to an example?

推荐答案

您不需要绑定（2）这一点。

什么你希望做的，是使用不同的网络接口的与你的插座。若要使用系统默认的网络接口，你需要使用 SO_BINDTODEVICE 与的setsockopt 沿套接字选项。要使用该接口，如eth1的例如，应指定为一个字符串 ifr_name 一个 的ifreq 结构这是场传递给的setsockopt 。要做到这一点，你需要包括＆LT;网/ if.h中方式＆gt; 头

What you're looking to do here is to use a different network interface with your socket. To use a network interface other than the system default, you need to use the SO_BINDTODEVICE socket option along with setsockopt. The interface you want to use, such as "eth1" for example, should be specified as a string in the ifr_name field of a ifreq struct which is to be passed to setsockopt. To do this, you need to include the <net/if.h> header.

基本上，类似如下（未经测试）code：

Basically, something like the following (untested) code:

int set_interface(int socket_fd, const char* interface_name)
{
    ifreq interface;
    memset(&interface, 0, sizeof(interface));
    strncpy(interface.ifr_name, interface_name, IFNAMSIZ);
    int res = setsockopt(socket_fd, SOL_SOCKET, SO_BINDTODEVICE, &ifreq, sizeof(ifreq));
    return res;
}

此外，请确保您检查返回code，万一的setsockopt 失败。

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