Help with sk_buff

cstrask · 11-23-2005, 09:55 PM

I am writing a custom network device driver. It is essentially IP over ppp. I am having difficulty
understanding how to properly form the link layer header. I need to makeup a fake/static link layer header b/c the real header is removed by the hardware.

My code is below any suggestions would be helpful. I am not sure what to do in dev->hard_header
and dev->rebuild_header.

Code:

void sonet_init(struct net_device *dev)
{
	struct sonet_priv *priv;
	//ether_setup(dev); /* assign some of the fields */
	dev->open                   = sonet_open;
	dev->stop                    = sonet_release;
	dev->set_config           = sonet_config;
	dev->hard_start_xmit  = sonet_tx;
	dev->do_ioctl               = sonet_ioctl;
	dev->get_stats            = sonet_stats;
	dev->change_mtu       = sonet_change_mtu;  
	dev->rebuild_header    = sonet_rebuild_header;
	dev->hard_header       = sonet_header;
	dev->tx_timeout         = sonet_tx_timeout;
	dev->watchdog_timeo = timeout;
	dev->type		       = ARPHRD_PPP;
	dev->hard_header_len = 2;
	dev->mtu		= 1500;
	dev->addr_len		= 1;
	dev->tx_queue_len	= 1000;	
	dev->flags           |= IFF_NOARP;
	dev->features        |= NETIF_F_NO_CSUM;
	dev->hard_header_cache = NULL;      /* Disable caching */
	priv = netdev_priv(dev);
	memset(priv, 0, sizeof(struct sonet_priv));
}
void sonet_rx(struct net_device *dev)
{
	printk(KERN_ALERT "SONET RX Function\n");
	//static packet used for debugging

       char data[] = {
              0x45, 0x00, 0x00, 0x54, 0xbc, 0xe7, 0x40, 0x00, 0x80, 0x01, 0xb9, 0x71, 0xc0, 0xa8,
              0x01, 0x02, 0xc0, 0xa8, 0x01, 0x01, 0x00, 0x00, 0x51, 0x96, 0xf7, 0x6b, 0x00, 0x04,   0xf8, 0xe9,
              0x80, 0x43, 0x44, 0xc9, 0x0e, 0x00, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 
              0x12, 0x13,0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 
              0x22, 0x23,  0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 
              0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37};
   
	int length = 84;

	struct sk_buff *skb;
	struct sonet_priv *priv = netdev_priv(dev);
	skb = dev_alloc_skb(length);
	memcpy(skb_put(skb, length), data, length);
	skb->dev = dev;

	//I am trying to set a static header
       skb->mac.raw = 0x00;
	skb->pkt_type=PACKET_OTHERHOST;
	skb->protocol=ETH_P_IP;
       skb->data = data;
	skb->ip_summed = CHECKSUM_UNNECESSARY; /* don't check it */
	priv->stats.rx_packets++;
	priv->stats.rx_bytes += length;
	netif_rx(skb);
}