我编写了一个程序,将特定接口(interface)(例如 eth0
或 eth1
)的 MTU 大小设置为 1100。请求消息是从用户空间发送的通过 NETLINK_ROUTE
选项的 Netlink 套接字。
消息已从用户空间成功发送,但是当我验证 ifconfig eth0
时,MTU 大小仍然显示旧值 (1500)。我验证正确吗?我如何知道内核是否正确设置了 MTU 大小?请在下面找到我的程序,如果我错了,请纠正我。
#include <stdio.h>
#include <stdlib.h>
#include <net/if.h>
#include <string.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <stdbool.h>
struct {
struct nlmsghdr nh;
struct ifinfomsg ifinfo;
char data[100];
}req;
int ret;
struct rtattr *rta;
/* MTU Set */
unsigned int mtu = 1100;
/* rtNetlinkSockFd */
int rtNetlinkSockFd = -1;
int main()
{
int ret;
rtNetlinkSockFd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
if(rtNetlinkSockFd < 0)
{
printf("Creation of NetLink Socket is failed \n");
return -1;
}
/* Memset the Requested Structure */
memset( &req, 0x00, sizeof(req));
/* Populate the Netlink Header Fields */
req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
/* Link Layer: RTM_NEWLINK, RTM_DELLINK, RTM_GETLINK, RTM_SETLINK */
req.nh.nlmsg_type = RTM_SETLINK;
/* NLM_F_REQUEST Must be set on all request messages. */
req.nh.nlmsg_flags = NLM_F_REQUEST;
req.nh.nlmsg_seq = 0;
req.nh.nlmsg_pid = 0; //getpid();
/* Populate the Ifinfo Structure Attributes */
req.ifinfo.ifi_family = AF_UNSPEC;
/* Give the Interface Name and get the Index */
req.ifinfo.ifi_index = if_nametoindex("eth0");
printf(" The NetLink Ifi_index :%d\n", req.ifinfo.ifi_index);
/* ifi_change is reserved for future use and
* should be always set to 0xFFFFFFFF. */
req.ifinfo.ifi_change = 0xFFFFFFFF;
req.ifinfo.ifi_type = 0;
req.ifinfo.ifi_flags = 0;
/* RTA is Pointed to (req+32) it means points to the DATA */
rta = (struct rtattr *)(((char *) &req) + NLMSG_ALIGN(req.nh.nlmsg_len));
/* IFLA_MTU unsigned int MTU of the device. */
rta->rta_type = IFLA_MTU;
/* Len Attribute */
rta->rta_len = sizeof(unsigned int);
req.nh.nlmsg_len = NLMSG_ALIGN(req.nh.nlmsg_len) + RTA_LENGTH(sizeof(mtu));
memcpy(RTA_DATA(rta), &mtu, sizeof(mtu));
ret = send(rtNetlinkSockFd, &req, req.nh.nlmsg_len, 0);
if (ret < 0)
{
printf( "netlink: Sending failed: (assume operstate is not supported)");
}
else
{
printf( "netlink: Sent successfully");
}
return 0;
}
最佳答案
我认为你需要写:
rta->rta_len = RTA_LENGTH(sizeof(unsigned int));
而不是:
rta->rta_len = sizeof(unsigned int);
关于c - 我无法通过 NETLINK_ROUTE 选项通过 Netlink 套接字设置特定接口(interface)(eth0 或 eth1)的 MTU 大小,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12732169/