#include <linux/module.h>
#include <net/netlink.h>

#include "trace_def.h"
#include "../netlink_api/libnetlink_k.h"
#include "trace_msg.h"
#include "commuapinl.h"


static int trace_rcv_policy(struct sk_buff *skb, struct nlmsghdr *nlh)
{   
    trace_ret_t ret = TRACE_FAILURE;
    trace_hdr_t *hdr;
    void *buf;
    int len;
    struct sk_buff *reply_skb;
    struct nlmsghdr *reply_hdr;
    void *reply_data;
    trace_reply_t *reply;
    int reply_ret;
    trace_policy_t *policy;
        
    printk(KERN_DEBUG"Trace recv policy");
    switch (nlh->nlmsg_type) {
        case TRACE_MSG_POLICY_REQ:
            buf = nlmsg_data(nlh);
            if (buf == NULL) {                
                printk(KERN_ERR"Receiving data is null");
                break;
            }
            len = nlmsg_len((const struct nlmsghdr *)nlh);
            printk(KERN_DEBUG"Receive data of trace is len:%d", len);
            if (len < TRACE_REQ_SZ) {
                printk(KERN_WARNING"Receiving data length:%d is less than length:%ld is needed", len, TRACE_REQ_SZ);
            }

            hdr = (trace_hdr_t *)buf;
            policy = (trace_policy_t *)(buf + 1);

            ret = TRACE_SUCCESS;
            break;
        default:            
            printk(KERN_WARNING"Unknow msg type:%u", nlh->nlmsg_type);
            return 1;
            break;
    }

    if (ret == TRACE_FAILURE) {
        return 1;
    }

    if (hdr->is_reply == REPLY_OP_NO_NEED) {
        return 0;
    }

    reply_skb = nlmsg_new(TRACE_REPLY_SZ, GFP_KERNEL);
    if (reply_skb == NULL) {        
        printk(KERN_ERR"Allocating skb memory is failure");
        goto FAIL;
    }
    reply_hdr = nlmsg_put(reply_skb, 0, 0, TRACE_MSG_POLICY_REPLY, TRACE_REPLY_SZ, 0);
    if (reply_hdr == NULL) {
        printk(KERN_ERR"Putting length of reply is failure");
        goto FAIL;
    }
    reply_data = nlmsg_data(reply_hdr);
    if (reply_data == NULL) {
        printk(KERN_ERR"Reply data is null");
        goto FAIL;
    }
    reply = (trace_reply_t *)reply_data;
    memcpy(&reply->hdr, hdr, sizeof(*hdr));
    reply->result = ret;

    reply_ret = commnl_unicast(NULL, reply_skb, nlh->nlmsg_pid);
    if (reply_ret != 0) {
        printk(KERN_ERR"Reply message is failure");
        goto FAIL;
    }

    nlmsg_free(reply_skb);
    return 0;

FAIL:    
    if (reply_skb != NULL) {  
        nlmsg_free(reply_skb);
    }

    return 1;
}

static int __init trace_init(void)
{
    printk(KERN_INFO"Trace is initiating");
    cfg_msgtype_register(TRACE_CFG_POLICY, trace_rcv_policy, NULL, NULL);
    printk(KERN_INFO"Trace is initiated");
    return 0;
}

static void __exit trace_exit(void)
{
    cfg_msgtype_unregister(TRACE_CFG_POLICY);

}

module_init(trace_init);
module_exit(trace_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Trace process module");
MODULE_AUTHOR("zhangtao");