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6lowpan: add uncompress header size function 

This patch add a lookup function for uncompressed 6LoWPAN header
size. This is needed to estimate the real size after uncompress the
6LoWPAN header.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Aring 2014-02-28 07:32:44 +01:00 committed by David S. Miller
parent 89745c9c41
commit 349aa7bc29
1 changed files with 113 additions and 0 deletions
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113
net/ieee802154/6lowpan.h
View File

@ -306,6 +306,119 @@ static inline void lowpan_push_hc_data(u8 **hc_ptr, const void *data,
*hc_ptr += len;
}
static inline u8 lowpan_addr_mode_size(const u8 addr_mode)
{
static const u8 addr_sizes[] = {
[LOWPAN_IPHC_ADDR_00] = 16,
[LOWPAN_IPHC_ADDR_01] = 8,
[LOWPAN_IPHC_ADDR_02] = 2,
[LOWPAN_IPHC_ADDR_03] = 0,
};
return addr_sizes[addr_mode];
}
static inline u8 lowpan_next_hdr_size(const u8 h_enc, u16 *uncomp_header)
{
u8 ret = 1;
if ((h_enc & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
*uncomp_header += sizeof(struct udphdr);
switch (h_enc & LOWPAN_NHC_UDP_CS_P_11) {
case LOWPAN_NHC_UDP_CS_P_00:
ret += 4;
break;
case LOWPAN_NHC_UDP_CS_P_01:
case LOWPAN_NHC_UDP_CS_P_10:
ret += 3;
break;
case LOWPAN_NHC_UDP_CS_P_11:
ret++;
break;
default:
break;
}
if (!(h_enc & LOWPAN_NHC_UDP_CS_C))
ret += 2;
}
return ret;
}
/**
* lowpan_uncompress_size - returns skb->len size with uncompressed header
* @skb: sk_buff with 6lowpan header inside
* @datagram_offset: optional to get the datagram_offset value
*
* Returns the skb->len with uncompressed header
*/
static inline u16
lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset)
{
u16 ret = 2, uncomp_header = sizeof(struct ipv6hdr);
u8 iphc0, iphc1, h_enc;
iphc0 = skb_network_header(skb)[0];
iphc1 = skb_network_header(skb)[1];
switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
case 0:
ret += 4;
break;
case 1:
ret += 3;
break;
case 2:
ret++;
break;
default:
break;
}
if (!(iphc0 & LOWPAN_IPHC_NH_C))
ret++;
if (!(iphc0 & 0x03))
ret++;
ret += lowpan_addr_mode_size((iphc1 & LOWPAN_IPHC_SAM) >>
LOWPAN_IPHC_SAM_BIT);
if (iphc1 & LOWPAN_IPHC_M) {
switch ((iphc1 & LOWPAN_IPHC_DAM_11) >>
LOWPAN_IPHC_DAM_BIT) {
case LOWPAN_IPHC_DAM_00:
ret += 16;
break;
case LOWPAN_IPHC_DAM_01:
ret += 6;
break;
case LOWPAN_IPHC_DAM_10:
ret += 4;
break;
case LOWPAN_IPHC_DAM_11:
ret++;
break;
default:
break;
}
} else {
ret += lowpan_addr_mode_size((iphc1 & LOWPAN_IPHC_DAM_11) >>
LOWPAN_IPHC_DAM_BIT);
}
if (iphc0 & LOWPAN_IPHC_NH_C) {
h_enc = skb_network_header(skb)[ret];
ret += lowpan_next_hdr_size(h_enc, &uncomp_header);
}
if (dgram_offset)
*dgram_offset = uncomp_header;
return skb->len + uncomp_header - ret;
}
typedef int (*skb_delivery_cb)(struct sk_buff *skb, struct net_device *dev);
int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,