6LoWPAN: add fragmentation support
This patch adds support for frame fragmentation.
Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 19d6aef..7d4cb58 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -113,6 +113,20 @@
struct list_head list;
};
+struct lowpan_fragment {
+ struct sk_buff *skb; /* skb to be assembled */
+ spinlock_t lock; /* concurency lock */
+ u16 length; /* length to be assemled */
+ u32 bytes_rcv; /* bytes received */
+ u16 tag; /* current fragment tag */
+ struct timer_list timer; /* assembling timer */
+ struct list_head list; /* fragments list */
+};
+
+static unsigned short fragment_tag;
+static LIST_HEAD(lowpan_fragments);
+spinlock_t flist_lock;
+
static inline struct
lowpan_dev_info *lowpan_dev_info(const struct net_device *dev)
{
@@ -244,6 +258,17 @@
return ret;
}
+static u16 lowpan_fetch_skb_u16(struct sk_buff *skb)
+{
+ u16 ret;
+
+ BUG_ON(!pskb_may_pull(skb, 2));
+
+ ret = skb->data[0] | (skb->data[1] << 8);
+ skb_pull(skb, 2);
+ return ret;
+}
+
static int lowpan_header_create(struct sk_buff *skb,
struct net_device *dev,
unsigned short type, const void *_daddr,
@@ -467,6 +492,7 @@
memcpy(&(sa.hwaddr), saddr, 8);
mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
+
return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,
type, (void *)&da, (void *)&sa, skb->len);
}
@@ -511,6 +537,21 @@
return stat;
}
+static void lowpan_fragment_timer_expired(unsigned long entry_addr)
+{
+ struct lowpan_fragment *entry = (struct lowpan_fragment *)entry_addr;
+
+ pr_debug("%s: timer expired for frame with tag %d\n", __func__,
+ entry->tag);
+
+ spin_lock(&flist_lock);
+ list_del(&entry->list);
+ spin_unlock(&flist_lock);
+
+ dev_kfree_skb(entry->skb);
+ kfree(entry);
+}
+
static int
lowpan_process_data(struct sk_buff *skb)
{
@@ -525,6 +566,107 @@
if (skb->len < 2)
goto drop;
iphc0 = lowpan_fetch_skb_u8(skb);
+
+ /* fragments assembling */
+ switch (iphc0 & LOWPAN_DISPATCH_MASK) {
+ case LOWPAN_DISPATCH_FRAG1:
+ case LOWPAN_DISPATCH_FRAGN:
+ {
+ struct lowpan_fragment *frame;
+ u8 len, offset;
+ u16 tag;
+ bool found = false;
+
+ len = lowpan_fetch_skb_u8(skb); /* frame length */
+ tag = lowpan_fetch_skb_u16(skb);
+
+ /*
+ * check if frame assembling with the same tag is
+ * already in progress
+ */
+ spin_lock(&flist_lock);
+
+ list_for_each_entry(frame, &lowpan_fragments, list)
+ if (frame->tag == tag) {
+ found = true;
+ break;
+ }
+
+ /* alloc new frame structure */
+ if (!found) {
+ frame = kzalloc(sizeof(struct lowpan_fragment),
+ GFP_ATOMIC);
+ if (!frame)
+ goto unlock_and_drop;
+
+ INIT_LIST_HEAD(&frame->list);
+
+ frame->length = (iphc0 & 7) | (len << 3);
+ frame->tag = tag;
+
+ /* allocate buffer for frame assembling */
+ frame->skb = alloc_skb(frame->length +
+ sizeof(struct ipv6hdr), GFP_ATOMIC);
+
+ if (!frame->skb) {
+ kfree(frame);
+ goto unlock_and_drop;
+ }
+
+ frame->skb->priority = skb->priority;
+ frame->skb->dev = skb->dev;
+
+ /* reserve headroom for uncompressed ipv6 header */
+ skb_reserve(frame->skb, sizeof(struct ipv6hdr));
+ skb_put(frame->skb, frame->length);
+
+ init_timer(&frame->timer);
+ /* time out is the same as for ipv6 - 60 sec */
+ frame->timer.expires = jiffies + LOWPAN_FRAG_TIMEOUT;
+ frame->timer.data = (unsigned long)frame;
+ frame->timer.function = lowpan_fragment_timer_expired;
+
+ add_timer(&frame->timer);
+
+ list_add_tail(&frame->list, &lowpan_fragments);
+ }
+
+ if ((iphc0 & LOWPAN_DISPATCH_MASK) == LOWPAN_DISPATCH_FRAG1)
+ goto unlock_and_drop;
+
+ offset = lowpan_fetch_skb_u8(skb); /* fetch offset */
+
+ /* if payload fits buffer, copy it */
+ if (likely((offset * 8 + skb->len) <= frame->length))
+ skb_copy_to_linear_data_offset(frame->skb, offset * 8,
+ skb->data, skb->len);
+ else
+ goto unlock_and_drop;
+
+ frame->bytes_rcv += skb->len;
+
+ /* frame assembling complete */
+ if ((frame->bytes_rcv == frame->length) &&
+ frame->timer.expires > jiffies) {
+ /* if timer haven't expired - first of all delete it */
+ del_timer(&frame->timer);
+ list_del(&frame->list);
+ spin_unlock(&flist_lock);
+
+ dev_kfree_skb(skb);
+ skb = frame->skb;
+ kfree(frame);
+ iphc0 = lowpan_fetch_skb_u8(skb);
+ break;
+ }
+ spin_unlock(&flist_lock);
+
+ return kfree_skb(skb), 0;
+ }
+ default:
+ break;
+ }
+
iphc1 = lowpan_fetch_skb_u8(skb);
_saddr = mac_cb(skb)->sa.hwaddr;
@@ -674,6 +816,9 @@
lowpan_raw_dump_table(__func__, "raw header dump", (u8 *)&hdr,
sizeof(hdr));
return lowpan_skb_deliver(skb, &hdr);
+
+unlock_and_drop:
+ spin_unlock(&flist_lock);
drop:
kfree_skb(skb);
return -EINVAL;
@@ -692,18 +837,118 @@
return 0;
}
+static int lowpan_get_mac_header_length(struct sk_buff *skb)
+{
+ /*
+ * Currently long addressing mode is supported only, so the overall
+ * header size is 21:
+ * FC SeqNum DPAN DA SA Sec
+ * 2 + 1 + 2 + 8 + 8 + 0 = 21
+ */
+ return 21;
+}
+
+static int
+lowpan_fragment_xmit(struct sk_buff *skb, u8 *head,
+ int mlen, int plen, int offset)
+{
+ struct sk_buff *frag;
+ int hlen, ret;
+
+ /* if payload length is zero, therefore it's a first fragment */
+ hlen = (plen == 0 ? LOWPAN_FRAG1_HEAD_SIZE : LOWPAN_FRAGN_HEAD_SIZE);
+
+ lowpan_raw_dump_inline(__func__, "6lowpan fragment header", head, hlen);
+
+ frag = dev_alloc_skb(hlen + mlen + plen + IEEE802154_MFR_SIZE);
+ if (!frag)
+ return -ENOMEM;
+
+ frag->priority = skb->priority;
+ frag->dev = skb->dev;
+
+ /* copy header, MFR and payload */
+ memcpy(skb_put(frag, mlen), skb->data, mlen);
+ memcpy(skb_put(frag, hlen), head, hlen);
+
+ if (plen)
+ skb_copy_from_linear_data_offset(skb, offset + mlen,
+ skb_put(frag, plen), plen);
+
+ lowpan_raw_dump_table(__func__, " raw fragment dump", frag->data,
+ frag->len);
+
+ ret = dev_queue_xmit(frag);
+
+ if (ret < 0)
+ dev_kfree_skb(frag);
+
+ return ret;
+}
+
+static int
+lowpan_skb_fragmentation(struct sk_buff *skb)
+{
+ int err, header_length, payload_length, tag, offset = 0;
+ u8 head[5];
+
+ header_length = lowpan_get_mac_header_length(skb);
+ payload_length = skb->len - header_length;
+ tag = fragment_tag++;
+
+ /* first fragment header */
+ head[0] = LOWPAN_DISPATCH_FRAG1 | (payload_length & 0x7);
+ head[1] = (payload_length >> 3) & 0xff;
+ head[2] = tag & 0xff;
+ head[3] = tag >> 8;
+
+ err = lowpan_fragment_xmit(skb, head, header_length, 0, 0);
+
+ /* next fragment header */
+ head[0] &= ~LOWPAN_DISPATCH_FRAG1;
+ head[0] |= LOWPAN_DISPATCH_FRAGN;
+
+ while ((payload_length - offset > 0) && (err >= 0)) {
+ int len = LOWPAN_FRAG_SIZE;
+
+ head[4] = offset / 8;
+
+ if (payload_length - offset < len)
+ len = payload_length - offset;
+
+ err = lowpan_fragment_xmit(skb, head, header_length,
+ len, offset);
+ offset += len;
+ }
+
+ return err;
+}
+
static netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *dev)
{
- int err = 0;
+ int err = -1;
pr_debug("(%s): package xmit\n", __func__);
skb->dev = lowpan_dev_info(dev)->real_dev;
if (skb->dev == NULL) {
pr_debug("(%s) ERROR: no real wpan device found\n", __func__);
- dev_kfree_skb(skb);
- } else
+ goto error;
+ }
+
+ if (skb->len <= IEEE802154_MTU) {
err = dev_queue_xmit(skb);
+ goto out;
+ }
+
+ pr_debug("(%s): frame is too big, fragmentation is needed\n",
+ __func__);
+ err = lowpan_skb_fragmentation(skb);
+error:
+ dev_kfree_skb(skb);
+out:
+ if (err < 0)
+ pr_debug("(%s): ERROR: xmit failed\n", __func__);
return (err < 0 ? NETDEV_TX_BUSY : NETDEV_TX_OK);
}
@@ -765,8 +1010,15 @@
goto drop;
/* check that it's our buffer */
- if ((skb->data[0] & 0xe0) == 0x60)
+ switch (skb->data[0] & 0xe0) {
+ case LOWPAN_DISPATCH_IPHC: /* ipv6 datagram */
+ case LOWPAN_DISPATCH_FRAG1: /* first fragment header */
+ case LOWPAN_DISPATCH_FRAGN: /* next fragments headers */
lowpan_process_data(skb);
+ break;
+ default:
+ break;
+ }
return NET_RX_SUCCESS;
