userspace.c

NETLINK是LINUX环境下一种新型的用户空间与内核空间的交互方法

#include <pthread.h>
#include <stdio.h>
#include <sys/time.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/msg.h>
#include <sys/socket.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/socket.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>

#define DPI_NETLINK 21
#define CONTROL_MSG 0x10
#define DATA_MSG 0x11
	
struct _data_to_kernel
{
	unsigned char * pskb_ptr;
	char flag;
};
   

struct _data_from_kernel
{
	int skb_offset;		//数据包相对内存区域首地址的偏移
	int skb_len;			//数据包长度
	unsigned char * pskb_ptr;		//skb结构体的地址
 };


int main()
{

	//netlink's data
 	int sock_fd;
	struct sockaddr_nl src_addr, dest_addr;
  struct nlmsghdr *send_nlh = NULL;  //netlink header
  struct nlmsghdr *rev_nlh = NULL;   //netlink header
  struct iovec send_iov,rev_iov;  
  struct msghdr rev_msg,send_msg;

	struct _data_from_kernel paddr;    //defined in dpi_mem_pool.h
	struct _data_from_kernel data_from_kernel;
	struct _data_to_kernel data_to_kernel;			//defined in qos_pme.h

	int i;
	int fd;
	int ret1;


		
	//creat netlink socket
	sock_fd = socket(PF_NETLINK, SOCK_RAW, DPI_NETLINK);
	 //init_netlinksocket(sock_fd,src_addr,dest_addr,send_nlh,send_iov,send_msg,rev_nlh,rev_iov,rev_msg);

	//init socket src addr
  memset(&src_addr, 0, sizeof(src_addr));
  src_addr.nl_family = AF_NETLINK;
  src_addr.nl_pid = getpid( );   //self pid 
  src_addr.nl_groups = 0;  
  bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr));


	//fcntl(sock_fd, F_SETFL, O_NONBLOCK); //notice!
	
	//init socket dest addr
  memset(&dest_addr, 0, sizeof(dest_addr));
  dest_addr.nl_family = AF_NETLINK;
  dest_addr.nl_pid = 0;   //  To Linux Kernel 
  dest_addr.nl_groups = 0; //unicast 


  //init netlink head send_nlh
  send_nlh=(struct nlmsghdr *)malloc(NLMSG_SPACE(sizeof(data_to_kernel)));
  send_nlh->nlmsg_len = NLMSG_SPACE(sizeof(data_to_kernel));
  send_nlh->nlmsg_pid = getpid();  
  send_nlh->nlmsg_flags = 0;
  send_nlh->nlmsg_type =CONTROL_MSG; //NOTICE
        
  //init send_msg 
	memcpy(NLMSG_DATA(send_nlh), &data_to_kernel,sizeof(data_to_kernel));
	memset(&send_msg, 0, sizeof(send_msg));
	send_iov.iov_base = (void *)send_nlh; //NOTICE
  send_iov.iov_len = send_nlh->nlmsg_len;
  send_msg.msg_name = (void *)&dest_addr;
  send_msg.msg_namelen = sizeof(dest_addr);
  send_msg.msg_iov = &send_iov;
  send_msg.msg_iovlen = 1;

	//通知内核进程ID等，初始化netlink
	for(i=0;i<2;i++)
		sendmsg(sock_fd, &send_msg, 0);

	send_nlh->nlmsg_type =DATA_MSG;//NOTICE!

	//=============init netlink head rev_nlh ==============================================
  rev_nlh=(struct nlmsghdr *)malloc(NLMSG_SPACE(sizeof(struct _data_from_kernel)));
  rev_nlh->nlmsg_len = NLMSG_SPACE(sizeof(struct _data_from_kernel));
  rev_nlh->nlmsg_pid = getpid();  /* self pid */
  rev_nlh->nlmsg_flags = 0;
  rev_nlh->nlmsg_type = 0; //NOTICE
        
  //init rev_msg
  //memcpy(NLMSG_DATA(rev_nlh), &data_to_user,sizeof(data_to_user));
  //memset(&rev_msg, 0, sizeof(rev_msg));
  rev_iov.iov_base = (void *)rev_nlh; //NOTICE
	rev_iov.iov_len = rev_nlh->nlmsg_len;
	rev_msg.msg_name = (void *)&dest_addr;
	rev_msg.msg_namelen = sizeof(dest_addr);
	rev_msg.msg_iov = &rev_iov;
	rev_msg.msg_iovlen = 1;
	//rev_msg.msg_flags=MSG_DONTWAIT;

	
	
	while(1)
	{

		memset(rev_nlh, 0, NLMSG_SPACE(sizeof(struct _data_from_kernel)));
		//recvmsg(sock_fd, &rev_msg, O_NONBLOCK);
	  ret1=recvmsg(sock_fd, &rev_msg, 0);

		printf("!!!!!!receive a message !!!!!!\n");

	if(ret1>=0)
	{

    memcpy(&paddr,NLMSG_DATA(rev_nlh), sizeof(struct _data_from_kernel));

		data_to_kernel.pskb_ptr=paddr.pskb_ptr;
		data_to_kernel.flag=0x01;

		memcpy(NLMSG_DATA(send_nlh), &data_to_kernel,sizeof(struct _data_to_kernel));

		sendmsg(sock_fd, &send_msg, 0);

	 }//end if(ret1>=0)
 }//end while(1)

        return 0;
}