C++ dev_hard_header函数代码示例

int dsr_hw_header_create(struct dsr_pkt *dp, struct sk_buff *skb)
{

	struct sockaddr broadcast =
	    { AF_UNSPEC, {0xff, 0xff, 0xff, 0xff, 0xff, 0xff} };
	struct neighbor_info neigh_info;

	if (dp->dst.s_addr == DSR_BROADCAST)
		memcpy(neigh_info.hw_addr.sa_data, broadcast.sa_data, ETH_ALEN);
	else {
		/* Get hardware destination address */
		if (neigh_tbl_query(dp->nxt_hop, &neigh_info) < 0) {
			DEBUG
			    ("Could not get hardware address for next hop %s\n",
			     print_ip(dp->nxt_hop));
			return -1;
		}
	}

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
	if (skb->dev->hard_header) {
		skb->dev->hard_header(skb, skb->dev, ETH_P_IP,
				      neigh_info.hw_addr.sa_data, 0, skb->len);
	} else {
		DEBUG("Missing hard_header\n");
		return -1;
	}
#else
	dev_hard_header(skb, skb->dev, ETH_P_IP,
			neigh_info.hw_addr.sa_data, 0, skb->len);	
#endif
	return 0;
}

/* DOWNSTACK: MASTER FUNCTION CALLED BY L3
 * analagous to ip_output and ip_finish_output{2}
 * they then call the equivalent of neigh_connected_output
 * A LOT of arp shit happens here too!
 * for reference: Figure 27.13
 */
int mhost_finish_output(struct sk_buff *skb, struct net_device *dev, const void *daddr)
{
    int err = 0;
    
    // printk(KERN_INFO "mhost_finish_output called\n");
    
    /* set device-specific header here... */
    skb->protocol = htons(ETH_P_MHOST);
    skb->dev = dev;
    err = dev_hard_header(skb, dev, ntohs(skb->protocol),
                          daddr, NULL, skb->len);
    
    /* ...and ship off to the device driver! */
    if (err >= 0) {
        err = dev_queue_xmit(skb);
        if (err < 0) {
            printk(KERN_INFO "error: dev_queue_xmit!\n");
        }
    }
    else {
        printk(KERN_INFO "error: dev_hard_header returned %d\n", err);
        err = -EINVAL;
        kfree_skb(skb);
    }
    return err;
}

/**
 * tipc_l2_send_msg - send a TIPC packet out over an L2 interface
 * @buf: the packet to be sent
 * @b_ptr: the bearer through which the packet is to be sent
 * @dest: peer destination address
 */
int tipc_l2_send_msg(struct sk_buff *buf, struct tipc_bearer *b,
		     struct tipc_media_addr *dest)
{
	struct sk_buff *clone;
	struct net_device *dev;
	int delta;

	dev = (struct net_device *)rcu_dereference_rtnl(b->media_ptr);
	if (!dev)
		return 0;

	clone = skb_clone(buf, GFP_ATOMIC);
	if (!clone)
		return 0;

	delta = dev->hard_header_len - skb_headroom(buf);
	if ((delta > 0) &&
	    pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
		kfree_skb(clone);
		return 0;
	}

	skb_reset_network_header(clone);
	clone->dev = dev;
	clone->protocol = htons(ETH_P_TIPC);
	dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,
			dev->dev_addr, clone->len);
	dev_queue_xmit(clone);
	return 0;
}

/**
 * tipc_l2_send_msg - send a TIPC packet out over an L2 interface
 * @skb: the packet to be sent
 * @b: the bearer through which the packet is to be sent
 * @dest: peer destination address
 */
int tipc_l2_send_msg(struct net *net, struct sk_buff *skb,
		     struct tipc_bearer *b, struct tipc_media_addr *dest)
{
	struct net_device *dev;
	int delta;
	void *tipc_ptr;

	dev = (struct net_device *)rcu_dereference_rtnl(b->media_ptr);
	if (!dev)
		return 0;

	/* Send RESET message even if bearer is detached from device */
	tipc_ptr = rcu_dereference_rtnl(dev->tipc_ptr);
	if (unlikely(!tipc_ptr && !msg_is_reset(buf_msg(skb))))
		goto drop;

	delta = dev->hard_header_len - skb_headroom(skb);
	if ((delta > 0) &&
	    pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC))
		goto drop;

	skb_reset_network_header(skb);
	skb->dev = dev;
	skb->protocol = htons(ETH_P_TIPC);
	dev_hard_header(skb, dev, ETH_P_TIPC, dest->value,
			dev->dev_addr, skb->len);
	dev_queue_xmit(skb);
	return 0;
drop:
	kfree_skb(skb);
	return 0;
}

/**
 * send_msg - send a TIPC message out over an InfiniBand interface
 */
static int send_msg(struct sk_buff *buf, struct tipc_bearer *tb_ptr,
                    struct tipc_media_addr *dest)
{
    struct sk_buff *clone;
    struct net_device *dev;
    int delta;

    clone = skb_clone(buf, GFP_ATOMIC);
    if (!clone)
        return 0;

    dev = ((struct ib_bearer *)(tb_ptr->usr_handle))->dev;
    delta = dev->hard_header_len - skb_headroom(buf);

    if ((delta > 0) &&
            pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
        kfree_skb(clone);
        return 0;
    }

    skb_reset_network_header(clone);
    clone->dev = dev;
    clone->protocol = htons(ETH_P_TIPC);
    dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,
                    dev->dev_addr, clone->len);
    dev_queue_xmit(clone);
    return 0;
}

static int p8023_request(struct datalink_proto *dl,
			 struct sk_buff *skb, unsigned char *dest_node)
{
	struct net_device *dev = skb->dev;

	dev_hard_header(skb, dev, ETH_P_802_3, dest_node, NULL, skb->len);
	return dev_queue_xmit(skb);
}

/*
 * Prepends an ISI header and sends a datagram.
 */
static int pn_send(struct sk_buff *skb, struct net_device *dev,
                   u16 dst, u16 src, u8 res, u8 irq)
{
    struct phonethdr *ph;
    int err;

    if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
            skb->len + sizeof(struct phonethdr) > dev->mtu) {
        err = -EMSGSIZE;
        goto drop;
    }

    /* Broadcast sending is not implemented */
    if (pn_addr(dst) == PNADDR_BROADCAST) {
        err = -EOPNOTSUPP;
        goto drop;
    }

    skb_reset_transport_header(skb);
    WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
    skb_push(skb, sizeof(struct phonethdr));
    skb_reset_network_header(skb);
    ph = pn_hdr(skb);
    ph->pn_rdev = pn_dev(dst);
    ph->pn_sdev = pn_dev(src);
    ph->pn_res = res;
    ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
    ph->pn_robj = pn_obj(dst);
    ph->pn_sobj = pn_obj(src);

    skb->protocol = htons(ETH_P_PHONET);
    skb->priority = 0;
    skb->dev = dev;

    if (pn_addr(src) == pn_addr(dst)) {
        skb_reset_mac_header(skb);
        skb->pkt_type = PACKET_LOOPBACK;
        skb_orphan(skb);
        if (irq)
            netif_rx(skb);
        else
            netif_rx_ni(skb);
        err = 0;
    } else {
        err = dev_hard_header(skb, dev, ntohs(skb->protocol),
                              NULL, NULL, skb->len);
        if (err < 0) {
            err = -EHOSTUNREACH;
            goto drop;
        }
        err = dev_queue_xmit(skb);
    }

    return err;
drop:
    kfree_skb(skb);
    return err;
}

static int pEII_request(struct datalink_proto *dl,
			struct sk_buff *skb, unsigned char *dest_node)
{
	struct net_device *dev = skb->dev;

	skb->protocol = htons(ETH_P_IPX);
	dev_hard_header(skb, dev, ETH_P_IPX, dest_node, NULL, skb->len);
	return dev_queue_xmit(skb);
}

static void send_hsr_supervision_frame(struct net_device *hsr_dev, u8 type)
{
	struct hsr_priv *hsr_priv;
	struct sk_buff *skb;
	int hlen, tlen;
	struct hsr_sup_tag *hsr_stag;
	struct hsr_sup_payload *hsr_sp;
	unsigned long irqflags;

	hlen = LL_RESERVED_SPACE(hsr_dev);
	tlen = hsr_dev->needed_tailroom;
	skb = alloc_skb(hsr_pad(sizeof(struct hsr_sup_payload)) + hlen + tlen,
			GFP_ATOMIC);

	if (skb == NULL)
		return;

	hsr_priv = netdev_priv(hsr_dev);

	skb_reserve(skb, hlen);

	skb->dev = hsr_dev;
	skb->protocol = htons(ETH_P_PRP);
	skb->priority = TC_PRIO_CONTROL;

	if (dev_hard_header(skb, skb->dev, ETH_P_PRP,
			    hsr_priv->sup_multicast_addr,
			    skb->dev->dev_addr, skb->len) < 0)
		goto out;

	skb_pull(skb, sizeof(struct ethhdr));
	hsr_stag = (typeof(hsr_stag)) skb->data;

	set_hsr_stag_path(hsr_stag, 0xf);
	set_hsr_stag_HSR_Ver(hsr_stag, 0);

	spin_lock_irqsave(&hsr_priv->seqnr_lock, irqflags);
	hsr_stag->sequence_nr = htons(hsr_priv->sequence_nr);
	hsr_priv->sequence_nr++;
	spin_unlock_irqrestore(&hsr_priv->seqnr_lock, irqflags);

	hsr_stag->HSR_TLV_Type = type;
	hsr_stag->HSR_TLV_Length = 12;

	skb_push(skb, sizeof(struct ethhdr));

	/* Payload: MacAddressA */
	hsr_sp = (typeof(hsr_sp)) skb_put(skb, sizeof(*hsr_sp));
	ether_addr_copy(hsr_sp->MacAddressA, hsr_dev->dev_addr);

	dev_queue_xmit(skb);
	return;

out:
	kfree_skb(skb);
}

int virt_send_ack(struct virt_priv *virt, struct device_node *slave, 
        struct remote_link *link)
{
    struct sk_buff *skb;
    struct net_device *dev = slave->dev;
    struct tunhdr *tunhdr;
    struct pathinfo *path;
    __be16 sport;

    unsigned alloc_size = sizeof(struct tunhdr) + sizeof(struct udphdr) +
        sizeof(struct iphdr) + LL_RESERVED_SPACE(dev);

    path = lookup_pathinfo(&virt->network, slave, link);
    if(!path)
        return -EINVAL;

    skb = alloc_skb(alloc_size, GFP_ATOMIC);
    if(!skb) {
        virt_path_put(path);
        return -ENOMEM;
    }

    skb_reserve(skb, alloc_size);

    tunhdr = virt_build_tunhdr(skb, NULL, NULL);
    virt_finish_tunhdr(tunhdr, path, NULL, link->node);

    /* TODO: We may want to split traffic among different ports, which
     * may change how we send ACKs.  For now, everything uses the same
     * source port. */
    sport = htons(virt_tunnel_source_port());
    virt_build_udp_header(skb, sport, link->rif.data_port);
    virt_build_ip_header(skb, slave->lif.ip4, link->rif.ip4);

    skb->dev = dev;
    skb->protocol = htons(ETH_P_IP);

    dev_hard_header(skb, dev, ETH_P_IP, slave->next_hop_addr, dev->dev_addr, skb->len);
    skb_reset_mac_header(skb);

    /* Update link statistics -- these may not be accurate if the packet gets
     * dropped after dev_queue_xmit. */
    slave->stats.tx_packets++;
    slave->stats.tx_bytes += skb->len;

    /* Update device statistics. */
    virt->stats.tx_packets++;
    virt->stats.tx_bytes += skb->len;

    /* Decrement refcnt. */
    virt_path_put(path);

    dev_queue_xmit(skb);

    return 0;
}

static int vlan_passthru_hard_header(struct sk_buff *skb, struct net_device *dev,
				     unsigned short type,
				     const void *daddr, const void *saddr,
				     unsigned int len)
{
	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
	struct net_device *real_dev = vlan->real_dev;

	return dev_hard_header(skb, real_dev, type, daddr, saddr, len);
}

static void netpoll_wrapper_send_arp_reply(struct netpoll_wrapper *pWrapper, struct queued_arp_reply *reply)
{
	int hlen, tlen;
	struct arphdr *arp;
	struct sk_buff *send_skb;
	unsigned char *arp_ptr;
	int size = arp_hdr_len(pWrapper->pDeviceWithHandler);
	hlen = LL_RESERVED_SPACE(pWrapper->pDeviceWithHandler);
	tlen = pWrapper->pDeviceWithHandler->needed_tailroom;
	send_skb = alloc_skb(size + hlen + tlen, GFP_ATOMIC);

	if (!send_skb)
		return;

	skb_reserve(send_skb, hlen);
	skb_reset_network_header(send_skb);
	arp = (struct arphdr *) skb_put(send_skb, size);
	send_skb->dev = pWrapper->pDeviceWithHandler;
	send_skb->protocol = htons(ETH_P_ARP);

	/* Fill the device header for the ARP frame */
	if (dev_hard_header(send_skb, pWrapper->pDeviceWithHandler, ETH_P_ARP,
		reply->remote_mac, pWrapper->pDeviceWithHandler->dev_addr,
		send_skb->len) < 0) 
	{
		kfree_skb(send_skb);
		return;
	}

	/*
	* Fill out the arp protocol part.
	*
	* we only support ethernet device type,
	* which (according to RFC 1390) should
	* always equal 1 (Ethernet).
	*/

	arp->ar_hrd = htons(pWrapper->pDeviceWithHandler->type);
	arp->ar_pro = htons(ETH_P_IP);
	arp->ar_hln = pWrapper->pDeviceWithHandler->addr_len;
	arp->ar_pln = 4;
	arp->ar_op = htons(ARPOP_REPLY);

	arp_ptr = (unsigned char *)(arp + 1);
	memcpy(arp_ptr, pWrapper->pDeviceWithHandler->dev_addr, pWrapper->pDeviceWithHandler->addr_len);
	arp_ptr += pWrapper->pDeviceWithHandler->addr_len;
	memcpy(arp_ptr, &reply->local_ip, 4);
	arp_ptr += 4;
	memcpy(arp_ptr, reply->remote_mac, pWrapper->pDeviceWithHandler->addr_len);
	arp_ptr += pWrapper->pDeviceWithHandler->addr_len;
	memcpy(arp_ptr, &reply->remote_ip, 4);

	netpoll_send_skb(&pWrapper->netpoll_obj, send_skb);
}

static int vlan_passthru_hard_header(struct sk_buff *skb, struct net_device *dev,
				     unsigned short type,
				     const void *daddr, const void *saddr,
				     unsigned int len)
{
	struct net_device *real_dev = vlan_dev_info(dev)->real_dev;

	if (saddr == NULL)
		saddr = dev->dev_addr;

	return dev_hard_header(skb, real_dev, type, daddr, saddr, len);
}

static int ztdeth_transmit(void *pvt, unsigned char *msg, int msglen)
{
	struct ztdeth *z;
	struct sk_buff *skb;
	struct ztdeth_header *zh;
	unsigned long flags;
	struct net_device *dev;
	unsigned char addr[ETH_ALEN];
	unsigned short subaddr; /* Network byte order */

	spin_lock_irqsave(&zlock, flags);
	z = pvt;
	if (z->dev) {
		/* Copy fields to local variables to remove spinlock ASAP */
		dev = z->dev;
		memcpy(addr, z->addr, sizeof(z->addr));
		subaddr = z->subaddr;
		spin_unlock_irqrestore(&zlock, flags);
		skb = dev_alloc_skb(msglen + dev->hard_header_len + sizeof(struct ztdeth_header) + 32);
		if (skb) {
			/* Reserve header space */
			skb_reserve(skb, dev->hard_header_len + sizeof(struct ztdeth_header));

			/* Copy message body */
			memcpy(skb_put(skb, msglen), msg, msglen);

			/* Throw on header */
			zh = (struct ztdeth_header *)skb_push(skb, sizeof(struct ztdeth_header));
			zh->subaddr = subaddr;

			/* Setup protocol and such */
			skb->protocol = __constant_htons(ETH_P_DAHDI_DETH);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
			skb_set_network_header(skb, 0);
#else
			skb->nh.raw = skb->data;
#endif
			skb->dev = dev;
#if  LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
			dev_hard_header(skb, dev, ETH_P_DAHDI_DETH, addr, dev->dev_addr, skb->len);
#else
			if (dev->hard_header)
				dev->hard_header(skb, dev, ETH_P_DAHDI_DETH, addr, dev->dev_addr, skb->len);
#endif
			skb_queue_tail(&skbs, skb);
		}
	}
	else
		spin_unlock_irqrestore(&zlock, flags);
	return 0;
}

int goose_trans_skb(struct net_device *dev, unsigned char *daddr,
					struct sk_buff *__skb, int reliablity)
{
	struct sk_buff *skb = __skb;
	unsigned int skb_pull_len = NLMSG_LENGTH(0) + sizeof(struct nl_data_header);

	if (unlikely((dev == NULL) || (!tran_active)))
		goto goose_trans_skb_fail;
	
	/* We use existing skb to form a new one:
	 *
	 * skb:
	 * old skb->data                      new skb->data
	 *   |                                  |
	 * -----------------------------------------------------------
	 *   | NLMSG_LENGTH(0) | nl_data_header | goose header | APDU
	 * -----------------------------------------------------------
	 *   | <==      skb_pull_len        ==> |
	 * 
	 */		
	skb_pull(skb, skb_pull_len);
	skb_reset_network_header(skb);

	/* But after pulling, if we have still no enough space for link-layer header,
	   we have to reconstruct a new skb */
	if ((skb->head - skb->network_header) < LL_RESERVED_SPACE(dev)) {
		skb = skb_copy_expand(__skb, LL_RESERVED_SPACE(dev), 16, GFP_ATOMIC);
		kfree_skb(__skb);
	}

	/* Specify protocol type and frame information */
	skb->dev = dev;
	skb->protocol = ETH_P_GOOSE;
	skb->pkt_type = PACKET_OUTGOING;
	skb->csum = 0;
	skb->ip_summed = 0;

	/* Set the highest priority */
	skb->priority = 0;
	
	if (unlikely(dev_hard_header(skb, dev, ETH_P_GOOSE, daddr, dev->dev_addr, skb->len) < 0))
		goto goose_trans_skb_fail;

	/* If the message should be transmitted by GOOSE Enhanced Retransmission Mechanism,
	   call goose_enhan_retrans, otherwise transmit it directly.*/
	return reliablity ? goose_enhan_retrans(skb):dev_queue_xmit(skb);
	
goose_trans_skb_fail:
	kfree_skb(skb);
	return -1;
}