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>
This commit is contained in:
alex.bluesman.smirnov@gmail.com
David S. Miller
parent
2a24444f8f
commit
719269afbc
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@ -21,11 +21,14 @@
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* Maxim Gorbachyov <maxim.gorbachev@siemens.com>
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* Maxim Osipov <maxim.osipov@siemens.com>
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* Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
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* Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
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*/
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#ifndef NET_IEEE802154_H
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#define NET_IEEE802154_H
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#define IEEE802154_MTU 127
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#define IEEE802154_FC_TYPE_BEACON 0x0 /* Frame is beacon */
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#define IEEE802154_FC_TYPE_DATA 0x1 /* Frame is data */
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#define IEEE802154_FC_TYPE_ACK 0x2 /* Frame is acknowledgment */
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@ -56,6 +59,9 @@
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(((x) & IEEE802154_FC_DAMODE_MASK) >> IEEE802154_FC_DAMODE_SHIFT)
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/* MAC footer size */
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#define IEEE802154_MFR_SIZE 2 /* 2 octets */
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/* MAC's Command Frames Identifiers */
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#define IEEE802154_CMD_ASSOCIATION_REQ 0x01
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#define IEEE802154_CMD_ASSOCIATION_RESP 0x02
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@ -113,6 +113,20 @@ struct lowpan_dev_record {
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struct list_head list;
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};
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struct lowpan_fragment {
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struct sk_buff *skb; /* skb to be assembled */
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spinlock_t lock; /* concurency lock */
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u16 length; /* length to be assemled */
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u32 bytes_rcv; /* bytes received */
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u16 tag; /* current fragment tag */
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struct timer_list timer; /* assembling timer */
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struct list_head list; /* fragments list */
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};
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static unsigned short fragment_tag;
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static LIST_HEAD(lowpan_fragments);
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spinlock_t flist_lock;
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static inline struct
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lowpan_dev_info *lowpan_dev_info(const struct net_device *dev)
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{
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@ -244,6 +258,17 @@ static u8 lowpan_fetch_skb_u8(struct sk_buff *skb)
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return ret;
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}
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static u16 lowpan_fetch_skb_u16(struct sk_buff *skb)
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{
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u16 ret;
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BUG_ON(!pskb_may_pull(skb, 2));
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ret = skb->data[0] | (skb->data[1] << 8);
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skb_pull(skb, 2);
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return ret;
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}
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static int lowpan_header_create(struct sk_buff *skb,
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struct net_device *dev,
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unsigned short type, const void *_daddr,
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@ -467,6 +492,7 @@ static int lowpan_header_create(struct sk_buff *skb,
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memcpy(&(sa.hwaddr), saddr, 8);
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mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
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return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,
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type, (void *)&da, (void *)&sa, skb->len);
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}
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@ -511,6 +537,21 @@ static int lowpan_skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr)
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return stat;
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}
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static void lowpan_fragment_timer_expired(unsigned long entry_addr)
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{
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struct lowpan_fragment *entry = (struct lowpan_fragment *)entry_addr;
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pr_debug("%s: timer expired for frame with tag %d\n", __func__,
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entry->tag);
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spin_lock(&flist_lock);
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list_del(&entry->list);
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spin_unlock(&flist_lock);
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dev_kfree_skb(entry->skb);
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kfree(entry);
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}
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static int
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lowpan_process_data(struct sk_buff *skb)
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{
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@ -525,6 +566,107 @@ lowpan_process_data(struct sk_buff *skb)
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if (skb->len < 2)
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goto drop;
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iphc0 = lowpan_fetch_skb_u8(skb);
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/* fragments assembling */
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switch (iphc0 & LOWPAN_DISPATCH_MASK) {
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case LOWPAN_DISPATCH_FRAG1:
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case LOWPAN_DISPATCH_FRAGN:
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{
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struct lowpan_fragment *frame;
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u8 len, offset;
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u16 tag;
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bool found = false;
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len = lowpan_fetch_skb_u8(skb); /* frame length */
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tag = lowpan_fetch_skb_u16(skb);
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/*
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* check if frame assembling with the same tag is
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* already in progress
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*/
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spin_lock(&flist_lock);
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list_for_each_entry(frame, &lowpan_fragments, list)
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if (frame->tag == tag) {
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found = true;
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break;
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}
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/* alloc new frame structure */
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if (!found) {
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frame = kzalloc(sizeof(struct lowpan_fragment),
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GFP_ATOMIC);
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if (!frame)
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goto unlock_and_drop;
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INIT_LIST_HEAD(&frame->list);
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frame->length = (iphc0 & 7) | (len << 3);
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frame->tag = tag;
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/* allocate buffer for frame assembling */
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frame->skb = alloc_skb(frame->length +
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sizeof(struct ipv6hdr), GFP_ATOMIC);
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if (!frame->skb) {
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kfree(frame);
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goto unlock_and_drop;
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}
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frame->skb->priority = skb->priority;
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frame->skb->dev = skb->dev;
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/* reserve headroom for uncompressed ipv6 header */
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skb_reserve(frame->skb, sizeof(struct ipv6hdr));
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skb_put(frame->skb, frame->length);
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init_timer(&frame->timer);
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/* time out is the same as for ipv6 - 60 sec */
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frame->timer.expires = jiffies + LOWPAN_FRAG_TIMEOUT;
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frame->timer.data = (unsigned long)frame;
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frame->timer.function = lowpan_fragment_timer_expired;
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add_timer(&frame->timer);
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list_add_tail(&frame->list, &lowpan_fragments);
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}
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if ((iphc0 & LOWPAN_DISPATCH_MASK) == LOWPAN_DISPATCH_FRAG1)
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goto unlock_and_drop;
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offset = lowpan_fetch_skb_u8(skb); /* fetch offset */
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/* if payload fits buffer, copy it */
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if (likely((offset * 8 + skb->len) <= frame->length))
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skb_copy_to_linear_data_offset(frame->skb, offset * 8,
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skb->data, skb->len);
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else
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goto unlock_and_drop;
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frame->bytes_rcv += skb->len;
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/* frame assembling complete */
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if ((frame->bytes_rcv == frame->length) &&
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frame->timer.expires > jiffies) {
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/* if timer haven't expired - first of all delete it */
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del_timer(&frame->timer);
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list_del(&frame->list);
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spin_unlock(&flist_lock);
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dev_kfree_skb(skb);
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skb = frame->skb;
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kfree(frame);
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iphc0 = lowpan_fetch_skb_u8(skb);
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break;
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}
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spin_unlock(&flist_lock);
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return kfree_skb(skb), 0;
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}
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default:
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break;
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}
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iphc1 = lowpan_fetch_skb_u8(skb);
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_saddr = mac_cb(skb)->sa.hwaddr;
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@ -674,6 +816,9 @@ lowpan_process_data(struct sk_buff *skb)
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lowpan_raw_dump_table(__func__, "raw header dump", (u8 *)&hdr,
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sizeof(hdr));
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return lowpan_skb_deliver(skb, &hdr);
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unlock_and_drop:
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spin_unlock(&flist_lock);
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drop:
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kfree_skb(skb);
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return -EINVAL;
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@ -692,18 +837,118 @@ static int lowpan_set_address(struct net_device *dev, void *p)
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return 0;
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}
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static int lowpan_get_mac_header_length(struct sk_buff *skb)
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{
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/*
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* Currently long addressing mode is supported only, so the overall
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* header size is 21:
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* FC SeqNum DPAN DA SA Sec
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* 2 + 1 + 2 + 8 + 8 + 0 = 21
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*/
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return 21;
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}
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static int
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lowpan_fragment_xmit(struct sk_buff *skb, u8 *head,
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int mlen, int plen, int offset)
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{
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struct sk_buff *frag;
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int hlen, ret;
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/* if payload length is zero, therefore it's a first fragment */
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hlen = (plen == 0 ? LOWPAN_FRAG1_HEAD_SIZE : LOWPAN_FRAGN_HEAD_SIZE);
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lowpan_raw_dump_inline(__func__, "6lowpan fragment header", head, hlen);
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frag = dev_alloc_skb(hlen + mlen + plen + IEEE802154_MFR_SIZE);
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if (!frag)
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return -ENOMEM;
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frag->priority = skb->priority;
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frag->dev = skb->dev;
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/* copy header, MFR and payload */
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memcpy(skb_put(frag, mlen), skb->data, mlen);
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memcpy(skb_put(frag, hlen), head, hlen);
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if (plen)
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skb_copy_from_linear_data_offset(skb, offset + mlen,
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skb_put(frag, plen), plen);
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lowpan_raw_dump_table(__func__, " raw fragment dump", frag->data,
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frag->len);
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ret = dev_queue_xmit(frag);
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if (ret < 0)
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dev_kfree_skb(frag);
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return ret;
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}
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static int
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lowpan_skb_fragmentation(struct sk_buff *skb)
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{
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int err, header_length, payload_length, tag, offset = 0;
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u8 head[5];
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header_length = lowpan_get_mac_header_length(skb);
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payload_length = skb->len - header_length;
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tag = fragment_tag++;
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/* first fragment header */
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head[0] = LOWPAN_DISPATCH_FRAG1 | (payload_length & 0x7);
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head[1] = (payload_length >> 3) & 0xff;
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head[2] = tag & 0xff;
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head[3] = tag >> 8;
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err = lowpan_fragment_xmit(skb, head, header_length, 0, 0);
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/* next fragment header */
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head[0] &= ~LOWPAN_DISPATCH_FRAG1;
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head[0] |= LOWPAN_DISPATCH_FRAGN;
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while ((payload_length - offset > 0) && (err >= 0)) {
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int len = LOWPAN_FRAG_SIZE;
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head[4] = offset / 8;
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if (payload_length - offset < len)
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len = payload_length - offset;
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err = lowpan_fragment_xmit(skb, head, header_length,
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len, offset);
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offset += len;
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}
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return err;
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}
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static netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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int err = 0;
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int err = -1;
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pr_debug("(%s): package xmit\n", __func__);
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skb->dev = lowpan_dev_info(dev)->real_dev;
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if (skb->dev == NULL) {
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pr_debug("(%s) ERROR: no real wpan device found\n", __func__);
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dev_kfree_skb(skb);
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} else
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goto error;
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}
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if (skb->len <= IEEE802154_MTU) {
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err = dev_queue_xmit(skb);
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goto out;
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}
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pr_debug("(%s): frame is too big, fragmentation is needed\n",
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__func__);
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err = lowpan_skb_fragmentation(skb);
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error:
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dev_kfree_skb(skb);
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out:
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if (err < 0)
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pr_debug("(%s): ERROR: xmit failed\n", __func__);
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return (err < 0 ? NETDEV_TX_BUSY : NETDEV_TX_OK);
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}
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@ -765,8 +1010,15 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
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goto drop;
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/* check that it's our buffer */
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if ((skb->data[0] & 0xe0) == 0x60)
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switch (skb->data[0] & 0xe0) {
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case LOWPAN_DISPATCH_IPHC: /* ipv6 datagram */
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case LOWPAN_DISPATCH_FRAG1: /* first fragment header */
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case LOWPAN_DISPATCH_FRAGN: /* next fragments headers */
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lowpan_process_data(skb);
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break;
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default:
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break;
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}
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return NET_RX_SUCCESS;
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@ -159,6 +159,24 @@
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#define LOWPAN_DISPATCH_FRAG1 0xc0 /* 11000xxx */
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#define LOWPAN_DISPATCH_FRAGN 0xe0 /* 11100xxx */
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#define LOWPAN_DISPATCH_MASK 0xf8 /* 11111000 */
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#define LOWPAN_FRAG_TIMEOUT (HZ * 60) /* time-out 60 sec */
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#define LOWPAN_FRAG1_HEAD_SIZE 0x4
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#define LOWPAN_FRAGN_HEAD_SIZE 0x5
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/*
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* According IEEE802.15.4 standard:
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* - MTU is 127 octets
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* - maximum MHR size is 37 octets
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* - MFR size is 2 octets
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*
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* so minimal payload size that we may guarantee is:
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* MTU - MHR - MFR = 88 octets
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*/
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#define LOWPAN_FRAG_SIZE 88
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/*
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* Values of fields within the IPHC encoding first byte
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* (C stands for compressed and I for inline)
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