Question

我在RedHat安装的Linux上运行了一个工作代码，内核 2.6.18-194.el5＃1 SMP x86_64 。

当我使用CentOS 6.3将代码移动到新安装的机器时，相同的代码以

失败

分配套接字选项时出错：域外的数字参数

后一台机器的内核版本是 2.6.32-279.el6.x86_64＃1 SMP

以下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;
    }

Answer 1

尝试使用

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

我看到一些实现不接受10 ^ 6以上的tv_usec。

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

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;

   / ... /    
}

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;

    /* ... */
}

现在我们已经足够了解git blame - ing :)这个变化是通过以下变更集引入的：

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，这一变化包含在2.6.22-rc3中。

Answer 2

不应该是

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

因为100万微秒== 1秒？

setsockopt（）出错：域外的数字参数

2 个答案: