4

我有一个工作代码在安装了内核2.6.18-194.el5 #1 SMP x86_64的 RedHat 上运行。

当我将代码移动到使用 CentOS 6.3 的新安装机器时，相同的代码失败了

分配套接字选项时出错：域外的数值参数

后者机器的内核版本是2.6.32-279.el6.x86_64 #1 SMP

下面分别是机器中工作和失败的代码。

    struct timeval          tv;

    tv.tv_sec       = 0;
    tv.tv_usec      = 1500000;

    if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(struct timeval)) != 0)
    {
            LM_ERR("Error assigning socket option: %s", strerror( errno ));
            return FALSE;
    }
4

2 回答 2

8

尝试使用

tv.tv_sec       = 1;
tv.tv_usec      = 500000;

我见过一些不接受tv_usec高于 10^6 的实现。

编辑：这个问题很有趣，可以稍微挖掘一下。在内核源代码中查找SO_RCVTIMEO，我在以下代码中找到了以下代码net/core/sock.c：

int sock_setsockopt(struct socket *sock, int level, int optname,
            char __user *optval, unsigned int optlen)
{

   / ... /    
   switch (optname) {

   / ... /    

   case SO_RCVTIMEO:
        ret = sock_set_timeout(&sk->sk_rcvtimeo, optval, optlen);
        break;

   / ... /    
}

该sock_set_timeout()函数的开头确实包含一些范围检查：

static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
{
    struct timeval tv;

    if (optlen < sizeof(tv))
        return -EINVAL;
    if (copy_from_user(&tv, optval, sizeof(tv)))
        return -EFAULT;
    if (tv.tv_usec < 0 || tv.tv_usec >= USEC_PER_SEC)
        return -EDOM;

    /* ... */
}

现在我们知道的足够多git blame-ing :) 更改是通过以下更改集引入的：

commit ba78073e6f70cd9c64a478a9bd901d7c8736cfbc 
Author: Vasily Averin <vvs@sw.ru> 
Date:   Thu May 24 16:58:54 2007 -0700

[NET]: "wrong timeout value" in sk_wait_data() v2

sys_setsockopt() do not check properly timeout values for 
SO_RCVTIMEO/SO_SNDTIMEO, for example it's possible to set negative timeout
values. POSIX do not defines behaviour for sys_setsockopt in case negative
timeouts, but requires that setsockopt() shall fail with -EDOM if the send and
receive timeout values are too big to fit into the timeout fields in the socket
structure. 
In current implementation negative timeout can lead to error messages like
"schedule_timeout: wrong timeout value".

Proposed patch:
- checks tv_usec and returns -EDOM if it is wrong
- do not allows to set negative timeout values (sets 0 instead) and outputs
  ratelimited information message about such attempts.

Signed-off-By: Vasily Averin <vvs@sw.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

我相信提交评论解释了一切。据我所知，此更改包含在 2.6.22-rc3 中。

于 2012-12-14T22:07:53.057 回答
4

那不应该是

tv.tv_sec   = 1;
tv.tv_usec  = 500000;

因为 100 万微秒 == 1 秒？

于 2012-12-14T22:06:23.620 回答