在Linux内核中发送UDP数据包 [英] Sending UDP packet in Linux Kernel

问题描述

对于一个项目，我正在尝试从Linux内核空间发送UDP数据包.我目前正在将我的代码硬编码"到内核中(我知道这不是最好/最有效的方法)，但是我试图使一个简单的测试生效(发送"TEST").应该提到的是，我是内核黑客的新手-我对许多原理和技术的了解还不是那么丰富！

For a project, I'm trying to send UDP packets from Linux kernel-space. I'm currently 'hard-coding' my code into the kernel (which I appreciate isn't the best/neatest way) but I'm trying to get a simple test to work (sending "TEST"). It should be mentioned I'm a newbie to kernel hacking - I'm not that clued up on many principles and techniques!

每次我的代码运行时，系统都会挂起，并且我必须重新启动-没有鼠标/键盘响应，并且滚动键和大写锁定键指示灯一起闪烁-我不确定这是什么意思，但是我假设这是内核恐慌?

Every time my code gets run the system hangs and I have to reboot - no mouse/keyboard response and the scroll and caps lock key lights flash together - I'm not sure what this means, but I'm assuming it's a kernel panic?

对于此测试代码而言，repeat_send代码不是必需的，但是当它工作时，我想发送可能需要多次发送"的大型邮件-我不确定是否可能导致我的问题?

The repeat_send code is unnecessary for this test code, yet when it's working I want to send large messages that may require multiple 'send's - I'm not sure that if could be a cause of my issues?

这段代码被插入到linux-source/net/core/origin的neighbour.c中，因此使用NEIGH_PRINTK1，它只是将printk进行宏包装.

N.B. This code is being inserted into neighbour.c of linux-source/net/core/ origin, hence the use of NEIGH_PRINTK1, it's just a macro wrapper round printk.

我的头真的撞到了砖墙上，我看不到任何明显的东西，没有人能指出我正确的方向(或发现那个令人眼花obvious乱的错误！)?

I'm really banging my head against a brick wall here, I can't spot anything obvious, can anyone point me in the right direction (or spot that blindingly obvious error!)?

这是我到目前为止所拥有的:

Here's what I have so far:

void mymethod()
{
    struct socket sock;
    struct sockaddr_in addr_in;
    int ret_val;
    unsigned short port = htons(2048);
    unsigned int host = in_aton("192.168.1.254");
    unsigned int length = 5;
    char *buf = "TEST\0";
    struct msghdr msg;
    struct iovec iov;
    int len = 0, written = 0, left = length;
    mm_segment_t oldmm;

    NEIGH_PRINTK1("forwarding sk_buff at: %p.\n", skb);

    if ((ret_val = sock_create(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
        NEIGH_PRINTK1("Error during creation of socket; terminating. code: %d\n", ret_val);
        return;
    }

    memset(&addr_in, 0, sizeof(struct sockaddr_in));
    addr_in.sin_family=AF_INET;
    addr_in.sin_port = port;
    addr_in.sin_addr.s_addr = host;

    if((ret_val = sock.ops->bind(&sock, (struct sockaddr *)&addr_in, sizeof(struct sockaddr_in))) < 0) {
    NEIGH_PRINTK1("Error trying to bind socket. code: %d\n", ret_val);
    goto close;
    }

    memset(&msg, 0, sizeof(struct msghdr));
    msg.msg_flags = 0;
    msg.msg_name = &addr_in;
    msg.msg_namelen = sizeof(struct sockaddr_in);
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;
    msg.msg_control = NULL;
    msg.msg_controllen = 0;

repeat_send:
    msg.msg_iov->iov_len = left;
    msg.msg_iov->iov_base = (char *)buf + written;

    oldmm = get_fs(); 
    set_fs(KERNEL_DS);
    len = sock_sendmsg(&sock, &msg, left);
    set_fs(oldmm);

    if (len == -ERESTARTSYS)
        goto repeat_send;
    if (len > 0) {
        written += len;
        left -= len;
        if (left)
            goto repeat_send;
    }

close:
    sock_release(&sock);
}

任何帮助将不胜感激，谢谢！

Any help would be hugely appreciated, thanks!

推荐答案

您可能会发现使用 netconsole 的示例它被使用了.您正在使用的API更适合用于用户空间(您不必使用段描述符来发送网络数据！)

You may find it easier to use the netpoll API for UDP. Take a look at netconsole for an example of how it's used. The APIs you're using are more intended for userspace (you should never have to play with segment descriptors to send network data!)

这篇关于在Linux内核中发送UDP数据包的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！