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 2011-11-10 07:38:38 +00:00 committed by David S. Miller
parent 2a24444f8f
commit 719269afbc
3 changed files with 280 additions and 4 deletions

View File

@ -21,11 +21,14 @@
* Maxim Gorbachyov <maxim.gorbachev@siemens.com>
* Maxim Osipov <maxim.osipov@siemens.com>
* Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
* Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
*/
#ifndef NET_IEEE802154_H
#define NET_IEEE802154_H
#define IEEE802154_MTU 127
#define IEEE802154_FC_TYPE_BEACON 0x0 /* Frame is beacon */
#define IEEE802154_FC_TYPE_DATA 0x1 /* Frame is data */
#define IEEE802154_FC_TYPE_ACK 0x2 /* Frame is acknowledgment */
@ -56,6 +59,9 @@
(((x) & IEEE802154_FC_DAMODE_MASK) >> IEEE802154_FC_DAMODE_SHIFT)
/* MAC footer size */
#define IEEE802154_MFR_SIZE 2 /* 2 octets */
/* MAC's Command Frames Identifiers */
#define IEEE802154_CMD_ASSOCIATION_REQ 0x01
#define IEEE802154_CMD_ASSOCIATION_RESP 0x02

View File

@ -113,6 +113,20 @@ struct lowpan_dev_record {
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 @@ static u8 lowpan_fetch_skb_u8(struct sk_buff *skb)
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 @@ static int lowpan_header_create(struct sk_buff *skb,
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 @@ static int lowpan_skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr)
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 @@ lowpan_process_data(struct sk_buff *skb)
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_process_data(struct sk_buff *skb)
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 @@ static int lowpan_set_address(struct net_device *dev, void *p)
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 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
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;

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@ -159,6 +159,24 @@
#define LOWPAN_DISPATCH_FRAG1 0xc0 /* 11000xxx */
#define LOWPAN_DISPATCH_FRAGN 0xe0 /* 11100xxx */
#define LOWPAN_DISPATCH_MASK 0xf8 /* 11111000 */
#define LOWPAN_FRAG_TIMEOUT (HZ * 60) /* time-out 60 sec */
#define LOWPAN_FRAG1_HEAD_SIZE 0x4
#define LOWPAN_FRAGN_HEAD_SIZE 0x5
/*
* According IEEE802.15.4 standard:
* - MTU is 127 octets
* - maximum MHR size is 37 octets
* - MFR size is 2 octets
*
* so minimal payload size that we may guarantee is:
* MTU - MHR - MFR = 88 octets
*/
#define LOWPAN_FRAG_SIZE 88
/*
* Values of fields within the IPHC encoding first byte
* (C stands for compressed and I for inline)