rt_wmp.c

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#include "rt_wmp.h"

#define WMP_PROTO 0x6969
//#define MAC80211

/* Queue for RT-WMP packet reception */
static struct net_device * net_dev;
struct ieee80211_sub_if_data *sdata;
static int initialized = 0, promisc = 0;

static struct rx_queue {
   struct sk_buff *skb;
   struct semaphore rx_sem;
   spinlock_t spin;
} rx_rtwmp_queue;

static unsigned char ethernet_frame[2500];
static struct ethhdr *ethernet_header;
static unsigned char dst_mac[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
static unsigned char src_mac[ETH_ALEN] = { 0xea, 0x1e, 0x1e, 0xe1, 0x00, 0x00 };



/* Initialization of the reception semaphore and queue for RT-WMP */
static void init_rx_queue(struct rx_queue *q) {
   sema_init(&q->rx_sem, 0);
   spin_lock_init(&q->spin);
   q->skb=NULL;
}

/* Free the remaining SKBs in the reception queue */
static void purge_rx_queue(struct rx_queue *q) {
   if(q->skb!=NULL)
      dev_kfree_skb_any(q->skb);
}

static void enqueue_rx_queue(struct rx_queue *q, struct sk_buff *skb) {
   unsigned long flags;
   spin_lock_irqsave(&q->spin, flags);
   if(q->skb == NULL){  // No hay elemento
      q->skb = skb;
      up(&q->rx_sem);
   } else {
      dev_kfree_skb_any(q->skb);
      q->skb = skb;
   }
   spin_unlock_irqrestore(&q->spin, flags);
}

static struct sk_buff *dequeue_rx_queue(struct rx_queue *q, long timeout) {
   unsigned long flags;
   struct sk_buff *skb = NULL;
   if (timeout == 0) {
      if (0==down_interruptible(&q->rx_sem)) {
         spin_lock_irqsave(&q->spin, flags);
         skb = q->skb;
         q->skb = NULL;
         while(!down_trylock(&q->rx_sem));
         spin_unlock_irqrestore(&q->spin, flags);
      }
   } else if (0==down_timeout(&q->rx_sem, msecs_to_jiffies(timeout))) {
      spin_lock_irqsave(&q->spin, flags);
      skb = q->skb;
      q->skb = NULL;
      while(!down_trylock(&q->rx_sem)){
          printk(KERN_ERR "Spinning\n");
      }
      spin_unlock_irqrestore(&q->spin, flags);
   }

   return skb;
}

int rt_wmp_is_active(){
        return initialized;
}

int rt_wmp_netif_receive_skb(struct sk_buff *skb, int signal){
        int proto;
        if (!initialized){
#ifdef MAC80211
                dev_kfree_skb(skb);
#else
                netif_rx(skb);
#endif
        }else{

#ifdef MAC80211
                unsigned short * protocol;
                struct ieee80211_radiotap_header * rth = (struct ieee80211_radiotap_header *) skb->data;
//              struct ieee80211_hdr * hdr =  (struct ieee80211_hdr *) (skb->data + rth->it_len);
                protocol = (unsigned short *) (skb->data + rth->it_len + sizeof(struct ieee80211_hdr));
                proto = *protocol;
#else
                proto = skb->protocol;
                skb->data[0] = 98 + (signed char) signal;
#endif


                if (promisc){
                        enqueue_rx_queue(&rx_rtwmp_queue, skb);
                }else{
                        if (proto == 0x6969) {
                                enqueue_rx_queue(&rx_rtwmp_queue, skb);
                        }
                }
        }

        return 1;
}

int ieee80211_rtwmp_timed_receive_raw(struct sk_buff **skb, unsigned int ms){
        struct sk_buff * k = dequeue_rx_queue(&rx_rtwmp_queue, ms);
        *skb=k;
        return (k!=NULL);
}

void ieee80211_rtwmp_finish(void){
        purge_rx_queue(&rx_rtwmp_queue);
        initialized = 0;
        printk(KERN_INFO "MAC80211-RT-WMP closed\n");
}


int ieee80211_rtwmp_send(char * f, int size) {
        int ret;
        struct sk_buff *skb;

        skb = alloc_skb(size + ETH_HLEN, GFP_ATOMIC);

        if (skb == NULL) {
                printk(KERN_ERR "Error: Unable to allocate skb (llsend) \n");
                return -ENOBUFS;
        }

        /* Copy the message into the ethernet frame */
        memcpy(ethernet_frame + ETH_HLEN, f, size);

        /* Copy the ethernet frame into the skb */
        memcpy(skb_put(skb, size + ETH_HLEN), ethernet_frame, size + ETH_HLEN);

        skb->protocol = WMP_PROTO;
        skb->dev = net_dev;

        ret = net_dev->netdev_ops->ndo_start_xmit(skb, net_dev);
        if (ret != 0) {
                kfree_skb(skb);
                return 0;
        }
        return 1;
}

#ifdef MAC80211
static void parse_radiotap(struct ieee80211_radiotap_header * buf, int * rate, char * rssi, char * noise) {
        int pkt_rate_100kHz = 0, antenna = 0, pwr = 0;
        char rssi_dbm = 0, noise_dbm = 0;
        struct ieee80211_radiotap_iterator iterator;
        int ret = ieee80211_radiotap_iterator_init(&iterator, buf, buf->it_len,0);

        while (!ret) {

                ret = ieee80211_radiotap_iterator_next(&iterator);

                if (ret)
                        continue;

                /* see if this argument is something we can use */

                switch (iterator.this_arg_index) {
                /*
                 * You must take care when dereferencing iterator.this_arg
                 * for multibyte types... the pointer is not aligned.  Use
                 * get_unaligned((type *)iterator.this_arg) to dereference
                 * iterator.this_arg for type "type" safely on all arches.
                 */
                case IEEE80211_RADIOTAP_RATE:
                        /* radiotap "rate" u8 is in
                         * 500kbps units, eg, 0x02=1Mbps
                         */
                        pkt_rate_100kHz = (*iterator.this_arg) * 5;
                        break;
                case IEEE80211_RADIOTAP_DBM_ANTSIGNAL:
                        rssi_dbm = (*iterator.this_arg);
                        break;
                case IEEE80211_RADIOTAP_ANTENNA:
                        /* radiotap uses 0 for 1st ant */
                        antenna = (*iterator.this_arg);
                        break;

                case IEEE80211_RADIOTAP_DBM_TX_POWER:
                        pwr = *iterator.this_arg;
                        break;
                case IEEE80211_RADIOTAP_DB_ANTNOISE:
                        noise_dbm = *iterator.this_arg;
                        break;
                default:
                        break;
                }
        } /* while more rt headers */
        *noise = noise_dbm;
        *rssi = rssi_dbm;
        *rate = pkt_rate_100kHz;
}
#endif

int ieee80211_rtwmp_timed_receive(char * buff, rxInfo * ret, int ms){
        unsigned int pad = 0;
        struct sk_buff * skb = dequeue_rx_queue(&rx_rtwmp_queue, ms);
        if (skb!=NULL){

#ifdef MAC80211
                int rate = 0, llc_size = 2;
                char rssi, noise;
                struct ieee80211_radiotap_header * rth = (struct ieee80211_radiotap_header *) skb->data;
                pad = rth->it_len + sizeof(struct ieee80211_hdr) + llc_size;
                parse_radiotap(rth, &rate, &rssi, &noise);
                ret->proto = (*((unsigned short *) (skb->data + rth->it_len + sizeof(struct ieee80211_hdr))));
                ret->rate = rate;
                ret->rssi = rssi;
                ret->noise = noise;
                ret->has_lq = 1;
#else
                ret->has_lq = 0 ;
                ret->proto = skb->protocol;
#endif


                ret->size = skb->len-pad;
                ret->error = 0;
                memcpy(buff, skb->data + pad, ret->size);
//              printk(KERN_INFO "Dequeuo %d size:%d \n",ret->proto, ret->size);

                return 1;
        }else{
                ret->error = 1;
                return 0;
        }
}

int ieee80211_rtwmp_init(char * net_dev_name){
        int found = 0;
        net_dev = first_net_device(&init_net);
        while (net_dev) {
                net_dev = next_net_device(net_dev);
                if (strstr(net_dev->name, net_dev_name) != NULL) {
                        found = 1;
                        break;
                }
        }
        if (!found){
                printk(KERN_INFO "Error: unable to find net_device %s\n",net_dev_name);
                return 0;
        }

        /* Build the ethernet header used for tx */
        ethernet_header = (struct ethhdr *) ethernet_frame;
        memcpy(ethernet_header->h_source, src_mac, ETH_ALEN);
        memcpy(ethernet_header->h_dest, dst_mac, ETH_ALEN);
        ethernet_header->h_proto = htons(WMP_PROTO);

        init_rx_queue(&rx_rtwmp_queue);

        printk(KERN_INFO "Found net_device %s",net_dev->name);
        printk(KERN_INFO "MAC80211-RT-WMP initialized successfully\n");
        initialized = 1;
        return 1;

}



void ieee80211_rtwmp_set_promisc(int _promisc){
        promisc = _promisc;
}


EXPORT_SYMBOL(ieee80211_rtwmp_init);
EXPORT_SYMBOL(ieee80211_rtwmp_timed_receive);
EXPORT_SYMBOL(ieee80211_rtwmp_timed_receive_raw);
EXPORT_SYMBOL(ieee80211_rtwmp_finish);
EXPORT_SYMBOL(ieee80211_rtwmp_send);
EXPORT_SYMBOL(ieee80211_rtwmp_set_promisc);