#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/uaccess.h> 
#include <linux/sysctl.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/inet.h>

#include "dpi_trie_cache.h"

/*
 *	三元组超时时间设置为300s
 */
int dpi_cache_node_timeout = 300;


#define IPV4_ADDR (1)
#define IPV6_ADDR (2)

/*
 *	初始化cache链表
 */
#define TRIPLE_CAHCE_HASH_SIZE (2048)
struct list_head dpi_cache_head[TRIPLE_CAHCE_HASH_SIZE] = {0};

typedef struct pkt_info{
    unsigned int srcip;
    unsigned short sport;
    unsigned int dstip;
    unsigned short port;
    unsigned short proto;
}pkt_info_t;

#define POLY 0x01101 // CRC20生成多项式x^20+x^12+x^8+1即:01101 CRC32:04C11DB7L
static unsigned int crc_table[256] = {0};

unsigned int get_sum_poly(unsigned char data)
{
    unsigned int sum_poly = data;
    int j;
    sum_poly <<= 24;
    for(j = 0; j < 8; j++)
    {
        int hi = sum_poly&0x80000000; // 取得reg的最高位
        sum_poly <<= 1;
        if(hi) sum_poly = sum_poly^POLY;
    }
    return sum_poly;
}

void create_crc_table(void)  //在使用CRC20_key函数应该先建立crc表
{
    int i;
    for(i = 0; i < 256; i++)
    {
    	crc_table[i] = get_sum_poly(i&0xFF);
    }
}

unsigned int CRC20_key(unsigned char* data, int len)
{
    int i;
    unsigned int reg = 0xFFFFFFFF;// 0xFFFFFFFF，见后面解释
    for(i = 0; i < len; i++)
    {
        reg = (reg<<8) ^ crc_table[((reg>>24)&0xFF) ^ data[i]];
    }
    return (reg&0XFFFFF);//得到的reg取后20作为key值
}

/*
 * 初始化dpi三元组hash链表
 */
void dpi_cache_list_init(void)
{
	int i = 0;
	for (i = 0; i < TRIPLE_CAHCE_HASH_SIZE; i++){
		INIT_LIST_HEAD(&dpi_cache_head[i]);
	}
	
	return;
}

/*
 * 三元组hash值计算
 */
int dpi_cache_node_hash(struct dpi_cache_node node)
{
	pkt_info_t info;
	info.port = node.port;
	info.sport = 0;
	info.srcip = 0;
	info.proto = node.proto;
	if (node.ipv4 == true ) {
		info.dstip = node.ip.ip4.s_addr;
	} else {
		int i = 0;
		int dip = 0;
		for (i = 0; i < 4; ++i) {
			dip ^=  node.ip.ip6.s6_addr32[i];
		}
		info.dstip = dip;
	}
	
	return CRC20_key((unsigned char *)&info, sizeof(pkt_info_t))&(TRIPLE_CAHCE_HASH_SIZE - 1);
}


/*
 *   src 和dst比较，并更新dst的appid,update_appid=true,update
*/
bool dpi_cache_node_compare(struct dpi_cache_node src,struct dpi_cache_node dst,bool update_appid)
{
	if (src.port != dst.port){
		return false;
	}

	if (src.proto != dst.proto){
		return false;
	}

	if(src.ipv4 == true){
		if(src.ip.ip4.s_addr != dst.ip.ip4.s_addr){
			return false;
		}
	}else{
		int i = 0;
		for (i = 0; i < 4; i++){
			if (src.ip.ip6.s6_addr32[i] != dst.ip.ip6.s6_addr32[i]){
				return  false;
			}
		}

	}

	if (update_appid){
			if(src.appid != -1)
				dst.appid = src.appid;
			dst.uptime = get_jiffies_64();
	}
	
	return true;
}


/*
 *遍历hash链表，查找node
 */
bool dpi_cache_node_search(struct dpi_cache_node node,int flag)
{
	struct list_head * pList = NULL;
	int hash  = dpi_cache_node_hash(node);
	list_for_each(pList,&dpi_cache_head[hash]){
		struct dpi_cache_node *pNode = list_entry(pList,struct dpi_cache_node,list);
		if (dpi_cache_node_compare(node,*pNode,flag)){
			return true;
		}
	}
	
	return false;
}


/*
 *  DPI 信息记录，外部接口调用
*/
bool dpi_cache_node_add(struct dpi_cache_node node)
{
	int hash = 0;
	struct dpi_cache_node *pNode =NULL;

	if (dpi_cache_node_search(node,true)) {
		return true;
	}
		
	pNode = kmalloc(sizeof(struct dpi_cache_node), GFP_KERNEL);
	if (NULL == pNode) {
		return false;
	}
	
	hash = dpi_cache_node_hash(node);
	memcpy((char*)pNode,(char*)&node,sizeof(node));
	pNode->uptime = get_jiffies_64();
	//printk("%s,%d,%d,%d,%d\n",__FUNCTION__,__LINE__,pNode->proto,pNode->port,pNode->ipv4);
	list_add_tail(&pNode->list,&dpi_cache_head[hash]);
	return true;
}


/*
 * 释放hash链表上所有node节点
*/
void dpi_cache_list_release(void)
{
	int i = 0;
	for (i = 0; i < TRIPLE_CAHCE_HASH_SIZE; i++){
		while(!list_empty(&dpi_cache_head[i]))
		{
			list_del(dpi_cache_head[i].next);
		}
	}
}

/*
 *定时器超时，删除超时的节点
 */
void dpi_cache_node_timeout_func(void)
{
	struct list_head * pList = NULL;
	struct list_head * n = NULL;
	struct dpi_cache_node *pNode = NULL;
	
	int i = 0;
	
	for (i = 0; i < TRIPLE_CAHCE_HASH_SIZE; i++){
		list_for_each_safe(pList,(n),&dpi_cache_head[i]){
			pNode = list_entry(pList,struct dpi_cache_node,list);
			//printk("%s,%d,%d\n",__FUNCTION__,__LINE__,pNode->port);
			if(pNode&&
				(get_jiffies_64() - pNode->uptime >= dpi_cache_node_timeout)){
				list_del(&pNode->list);
			}
		}
	}
}

/*
 *  定时器操作
 */
struct timer_list gTimer;
void dpi_cache_timer_handler(unsigned long data) {
    //printk(KERN_INFO"timer pending:%d\n", timer_pending(&gTimer));
	dpi_cache_node_timeout_func();
    mod_timer(&gTimer, jiffies+msecs_to_jiffies(dpi_cache_node_timeout*1000));
}

int dpi_cache_timer_init(void) {
    printk(KERN_INFO"%s jiffies:%ld\n", __func__, jiffies);
    printk(KERN_INFO"ji:%d,HZ:%d\n", jiffies_to_msecs(250), HZ);
	init_timer(&gTimer);
    gTimer.expires = jiffies + dpi_cache_node_timeout*HZ;
	gTimer.function = dpi_cache_timer_handler;
    add_timer(&gTimer);
    printk(KERN_INFO"timer pending:%d\n", timer_pending(&gTimer));
    return 0;
}
#if 0
void test_func(void)
{
	struct dpi_cache_node node1,node2,node3;
	node1.proto = 17;
	in4_pton("192.168.1.1", strlen("192.168.1.1"),  (u8*)&node1.ip.ip4, -1, NULL);
	node1.port = 200;
	node1.ipv4 = true;
	dpi_cache_node_add(node1);
	
	node2.proto = 17;
	in4_pton("192.168.2.1", strlen("192.168.1.1"),  (u8*)&node2.ip.ip4, -1, NULL);
	node2.port = 200;
	node2.ipv4 = true;
	dpi_cache_node_add(node2);
	
	node3.proto = 17;
	in6_pton("2a01:198:603:0:396e:4789:8e99:890f", strlen("2a01:198:603:0:396e:4789:8e99:890f"), (u8*)&node3.ip.ip6, -1, NULL);
	node3.port = 200;
	node3.ipv4 = false;
	dpi_cache_node_add(node3);
	
	return;
}

#endif
void dpi_cache_timer_exit(void) {
    printk(KERN_INFO"%s jiffies:%ld\n", __func__, jiffies);
    del_timer(&gTimer);
}

EXPORT_SYMBOL_GPL(dpi_cache_node_add);
static int __init dpi_cahce_module_init(void)
{
	create_crc_table();
	dpi_cache_list_init();
	dpi_cache_timer_init();
	
	//test_func();
	return 0;
}

static void __exit dpi_cache_module_exit(void)
{
	dpi_cache_timer_exit();
	dpi_cache_list_release();
}



module_init(dpi_cahce_module_init);
module_exit(dpi_cache_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("rpdb process module");
MODULE_AUTHOR("wuhuanzheng");