6lowpan: rework tc and flow label handling
This patch reworks the handling of compression/decompression of traffic class and flow label handling. The current method is hard to understand, also doesn't checks if we can read the buffer from skb length. I tried to put the shifting operations into static inline functions and comment each steps which I did there to make it hopefully somewhat more readable. The big mess to deal with that is the that the ipv6 header bring the order "DSCP + ECN" but iphc uses "ECN + DSCP". Additional the DCSP + ECN bits are splitted in ipv6_hdr inside the priority and flow_lbl[0] fields. I tested these compressions by using fakelb 802.15.4 driver and manipulate the tc and flow label fields manually in function "__ip6_local_out" before the skb will be send to lower layers. Then I looked up the tc and flow label fields in wireshark on a wpan and lowpan interface. Signed-off-by: Alexander Aring <alex.aring@gmail.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Alexander Aring
Marcel Holtmann
parent
c8a3e7eb98
commit
b5af9bdbfe
|
|
@ -346,6 +346,108 @@ static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
|
||||||
return 0;
|
return 0;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
/* get the ecn values from iphc tf format and set it to ipv6hdr */
|
||||||
|
static inline void lowpan_iphc_tf_set_ecn(struct ipv6hdr *hdr, const u8 *tf)
|
||||||
|
{
|
||||||
|
/* get the two higher bits which is ecn */
|
||||||
|
u8 ecn = tf[0] & 0xc0;
|
||||||
|
|
||||||
|
/* ECN takes 0x30 in hdr->flow_lbl[0] */
|
||||||
|
hdr->flow_lbl[0] |= (ecn >> 2);
|
||||||
|
}
|
||||||
|
|
||||||
|
/* get the dscp values from iphc tf format and set it to ipv6hdr */
|
||||||
|
static inline void lowpan_iphc_tf_set_dscp(struct ipv6hdr *hdr, const u8 *tf)
|
||||||
|
{
|
||||||
|
/* DSCP is at place after ECN */
|
||||||
|
u8 dscp = tf[0] & 0x3f;
|
||||||
|
|
||||||
|
/* The four highest bits need to be set at hdr->priority */
|
||||||
|
hdr->priority |= ((dscp & 0x3c) >> 2);
|
||||||
|
/* The two lower bits is part of hdr->flow_lbl[0] */
|
||||||
|
hdr->flow_lbl[0] |= ((dscp & 0x03) << 6);
|
||||||
|
}
|
||||||
|
|
||||||
|
/* get the flow label values from iphc tf format and set it to ipv6hdr */
|
||||||
|
static inline void lowpan_iphc_tf_set_lbl(struct ipv6hdr *hdr, const u8 *lbl)
|
||||||
|
{
|
||||||
|
/* flow label is always some array started with lower nibble of
|
||||||
|
* flow_lbl[0] and followed with two bytes afterwards. Inside inline
|
||||||
|
* data the flow_lbl position can be different, which will be handled
|
||||||
|
* by lbl pointer. E.g. case "01" vs "00" the traffic class is 8 bit
|
||||||
|
* shifted, the different lbl pointer will handle that.
|
||||||
|
*
|
||||||
|
* The flow label will started at lower nibble of flow_lbl[0], the
|
||||||
|
* higher nibbles are part of DSCP + ECN.
|
||||||
|
*/
|
||||||
|
hdr->flow_lbl[0] |= lbl[0] & 0x0f;
|
||||||
|
memcpy(&hdr->flow_lbl[1], &lbl[1], 2);
|
||||||
|
}
|
||||||
|
|
||||||
|
/* lowpan_iphc_tf_decompress - decompress the traffic class.
|
||||||
|
* This function will return zero on success, a value lower than zero if
|
||||||
|
* failed.
|
||||||
|
*/
|
||||||
|
static int lowpan_iphc_tf_decompress(struct sk_buff *skb, struct ipv6hdr *hdr,
|
||||||
|
u8 val)
|
||||||
|
{
|
||||||
|
u8 tf[4];
|
||||||
|
|
||||||
|
/* Traffic Class and Flow Label */
|
||||||
|
switch (val) {
|
||||||
|
case LOWPAN_IPHC_TF_00:
|
||||||
|
/* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes) */
|
||||||
|
if (lowpan_fetch_skb(skb, tf, 4))
|
||||||
|
return -EINVAL;
|
||||||
|
|
||||||
|
/* 1 2 3
|
||||||
|
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
* |ECN| DSCP | rsv | Flow Label |
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
*/
|
||||||
|
lowpan_iphc_tf_set_ecn(hdr, tf);
|
||||||
|
lowpan_iphc_tf_set_dscp(hdr, tf);
|
||||||
|
lowpan_iphc_tf_set_lbl(hdr, &tf[1]);
|
||||||
|
break;
|
||||||
|
case LOWPAN_IPHC_TF_01:
|
||||||
|
/* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided. */
|
||||||
|
if (lowpan_fetch_skb(skb, tf, 3))
|
||||||
|
return -EINVAL;
|
||||||
|
|
||||||
|
/* 1 2
|
||||||
|
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
* |ECN|rsv| Flow Label |
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
*/
|
||||||
|
lowpan_iphc_tf_set_ecn(hdr, tf);
|
||||||
|
lowpan_iphc_tf_set_lbl(hdr, &tf[0]);
|
||||||
|
break;
|
||||||
|
case LOWPAN_IPHC_TF_10:
|
||||||
|
/* ECN + DSCP (1 byte), Flow Label is elided. */
|
||||||
|
if (lowpan_fetch_skb(skb, tf, 1))
|
||||||
|
return -EINVAL;
|
||||||
|
|
||||||
|
/* 0 1 2 3 4 5 6 7
|
||||||
|
* +-+-+-+-+-+-+-+-+
|
||||||
|
* |ECN| DSCP |
|
||||||
|
* +-+-+-+-+-+-+-+-+
|
||||||
|
*/
|
||||||
|
lowpan_iphc_tf_set_ecn(hdr, tf);
|
||||||
|
lowpan_iphc_tf_set_dscp(hdr, tf);
|
||||||
|
break;
|
||||||
|
case LOWPAN_IPHC_TF_11:
|
||||||
|
/* Traffic Class and Flow Label are elided */
|
||||||
|
break;
|
||||||
|
default:
|
||||||
|
WARN_ON_ONCE(1);
|
||||||
|
return -EINVAL;
|
||||||
|
}
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
/* TTL uncompression values */
|
/* TTL uncompression values */
|
||||||
static const u8 lowpan_ttl_values[] = {
|
static const u8 lowpan_ttl_values[] = {
|
||||||
[LOWPAN_IPHC_HLIM_01] = 1,
|
[LOWPAN_IPHC_HLIM_01] = 1,
|
||||||
|
|
@ -357,7 +459,7 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
|
||||||
const void *daddr, const void *saddr)
|
const void *daddr, const void *saddr)
|
||||||
{
|
{
|
||||||
struct ipv6hdr hdr = {};
|
struct ipv6hdr hdr = {};
|
||||||
u8 iphc0, iphc1, tmp = 0;
|
u8 iphc0, iphc1;
|
||||||
int err;
|
int err;
|
||||||
|
|
||||||
raw_dump_table(__func__, "raw skb data dump uncompressed",
|
raw_dump_table(__func__, "raw skb data dump uncompressed",
|
||||||
|
|
@ -373,49 +475,10 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
|
||||||
|
|
||||||
hdr.version = 6;
|
hdr.version = 6;
|
||||||
|
|
||||||
/* Traffic Class and Flow Label */
|
err = lowpan_iphc_tf_decompress(skb, &hdr,
|
||||||
switch (iphc0 & LOWPAN_IPHC_TF_MASK) {
|
iphc0 & LOWPAN_IPHC_TF_MASK);
|
||||||
/* Traffic Class and FLow Label carried in-line
|
if (err < 0)
|
||||||
* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
|
return err;
|
||||||
*/
|
|
||||||
case LOWPAN_IPHC_TF_00:
|
|
||||||
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
|
|
||||||
return -EINVAL;
|
|
||||||
|
|
||||||
memcpy(&hdr.flow_lbl, &skb->data[0], 3);
|
|
||||||
skb_pull(skb, 3);
|
|
||||||
hdr.priority = ((tmp >> 2) & 0x0f);
|
|
||||||
hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
|
|
||||||
(hdr.flow_lbl[0] & 0x0f);
|
|
||||||
break;
|
|
||||||
/* Flow Label carried in-line
|
|
||||||
* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
|
|
||||||
*/
|
|
||||||
case LOWPAN_IPHC_TF_01:
|
|
||||||
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
|
|
||||||
return -EINVAL;
|
|
||||||
|
|
||||||
hdr.flow_lbl[0] = (tmp & 0x0F) | ((tmp >> 2) & 0x30);
|
|
||||||
memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
|
|
||||||
skb_pull(skb, 2);
|
|
||||||
break;
|
|
||||||
/* Traffic class carried in-line
|
|
||||||
* ECN + DSCP (1 byte), Flow Label is elided
|
|
||||||
*/
|
|
||||||
case LOWPAN_IPHC_TF_10:
|
|
||||||
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
|
|
||||||
return -EINVAL;
|
|
||||||
|
|
||||||
hdr.priority = ((tmp >> 2) & 0x0f);
|
|
||||||
hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
|
|
||||||
break;
|
|
||||||
/* Traffic Class and Flow Label are elided */
|
|
||||||
case LOWPAN_IPHC_TF_11:
|
|
||||||
break;
|
|
||||||
default:
|
|
||||||
WARN_ON_ONCE(1);
|
|
||||||
break;
|
|
||||||
}
|
|
||||||
|
|
||||||
/* Next Header */
|
/* Next Header */
|
||||||
if (!(iphc0 & LOWPAN_IPHC_NH)) {
|
if (!(iphc0 & LOWPAN_IPHC_NH)) {
|
||||||
|
|
@ -550,10 +613,105 @@ static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct in6_addr *ipaddr,
|
||||||
return dam;
|
return dam;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
/* lowpan_iphc_get_tc - get the ECN + DCSP fields in hc format */
|
||||||
|
static inline u8 lowpan_iphc_get_tc(const struct ipv6hdr *hdr)
|
||||||
|
{
|
||||||
|
u8 dscp, ecn;
|
||||||
|
|
||||||
|
/* hdr->priority contains the higher bits of dscp, lower are part of
|
||||||
|
* flow_lbl[0]. Note ECN, DCSP is swapped in ipv6 hdr.
|
||||||
|
*/
|
||||||
|
dscp = (hdr->priority << 2) | ((hdr->flow_lbl[0] & 0xc0) >> 6);
|
||||||
|
/* ECN is at the two lower bits from first nibble of flow_lbl[0] */
|
||||||
|
ecn = (hdr->flow_lbl[0] & 0x30);
|
||||||
|
/* for pretty debug output, also shift ecn to get the ecn value */
|
||||||
|
pr_debug("ecn 0x%02x dscp 0x%02x\n", ecn >> 4, dscp);
|
||||||
|
/* ECN is at 0x30 now, shift it to have ECN + DCSP */
|
||||||
|
return (ecn << 2) | dscp;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* lowpan_iphc_is_flow_lbl_zero - check if flow label is zero */
|
||||||
|
static inline bool lowpan_iphc_is_flow_lbl_zero(const struct ipv6hdr *hdr)
|
||||||
|
{
|
||||||
|
return ((!(hdr->flow_lbl[0] & 0x0f)) &&
|
||||||
|
!hdr->flow_lbl[1] && !hdr->flow_lbl[2]);
|
||||||
|
}
|
||||||
|
|
||||||
|
/* lowpan_iphc_tf_compress - compress the traffic class which is set by
|
||||||
|
* ipv6hdr. Return the corresponding format identifier which is used.
|
||||||
|
*/
|
||||||
|
static u8 lowpan_iphc_tf_compress(u8 **hc_ptr, const struct ipv6hdr *hdr)
|
||||||
|
{
|
||||||
|
/* get ecn dscp data in a byteformat as: ECN(hi) + DSCP(lo) */
|
||||||
|
u8 tc = lowpan_iphc_get_tc(hdr), tf[4], val;
|
||||||
|
|
||||||
|
/* printout the traffic class in hc format */
|
||||||
|
pr_debug("tc 0x%02x\n", tc);
|
||||||
|
|
||||||
|
if (lowpan_iphc_is_flow_lbl_zero(hdr)) {
|
||||||
|
if (!tc) {
|
||||||
|
/* 11: Traffic Class and Flow Label are elided. */
|
||||||
|
val = LOWPAN_IPHC_TF_11;
|
||||||
|
} else {
|
||||||
|
/* 10: ECN + DSCP (1 byte), Flow Label is elided.
|
||||||
|
*
|
||||||
|
* 0 1 2 3 4 5 6 7
|
||||||
|
* +-+-+-+-+-+-+-+-+
|
||||||
|
* |ECN| DSCP |
|
||||||
|
* +-+-+-+-+-+-+-+-+
|
||||||
|
*/
|
||||||
|
lowpan_push_hc_data(hc_ptr, &tc, sizeof(tc));
|
||||||
|
val = LOWPAN_IPHC_TF_10;
|
||||||
|
}
|
||||||
|
} else {
|
||||||
|
/* check if dscp is zero, it's after the first two bit */
|
||||||
|
if (!(tc & 0x3f)) {
|
||||||
|
/* 01: ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
|
||||||
|
*
|
||||||
|
* 1 2
|
||||||
|
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
* |ECN|rsv| Flow Label |
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
*/
|
||||||
|
memcpy(&tf[0], &hdr->flow_lbl[0], 3);
|
||||||
|
/* zero the highest 4-bits, contains DCSP + ECN */
|
||||||
|
tf[0] &= ~0xf0;
|
||||||
|
/* set ECN */
|
||||||
|
tf[0] |= (tc & 0xc0);
|
||||||
|
|
||||||
|
lowpan_push_hc_data(hc_ptr, tf, 3);
|
||||||
|
val = LOWPAN_IPHC_TF_01;
|
||||||
|
} else {
|
||||||
|
/* 00: ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
|
||||||
|
*
|
||||||
|
* 1 2 3
|
||||||
|
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
* |ECN| DSCP | rsv | Flow Label |
|
||||||
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||||
|
*/
|
||||||
|
memcpy(&tf[0], &tc, sizeof(tc));
|
||||||
|
/* highest nibble of flow_lbl[0] is part of DSCP + ECN
|
||||||
|
* which will be the 4-bit pad and will be filled with
|
||||||
|
* zeros afterwards.
|
||||||
|
*/
|
||||||
|
memcpy(&tf[1], &hdr->flow_lbl[0], 3);
|
||||||
|
/* zero the 4-bit pad, which is reserved */
|
||||||
|
tf[1] &= ~0xf0;
|
||||||
|
|
||||||
|
lowpan_push_hc_data(hc_ptr, tf, 4);
|
||||||
|
val = LOWPAN_IPHC_TF_00;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
return val;
|
||||||
|
}
|
||||||
|
|
||||||
int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
|
int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
|
||||||
const void *daddr, const void *saddr)
|
const void *daddr, const void *saddr)
|
||||||
{
|
{
|
||||||
u8 tmp, iphc0, iphc1, *hc_ptr;
|
u8 iphc0, iphc1, *hc_ptr;
|
||||||
struct ipv6hdr *hdr;
|
struct ipv6hdr *hdr;
|
||||||
u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
|
u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
|
||||||
int ret, addr_type;
|
int ret, addr_type;
|
||||||
|
|
@ -588,46 +746,8 @@ int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
|
||||||
raw_dump_table(__func__, "sending raw skb network uncompressed packet",
|
raw_dump_table(__func__, "sending raw skb network uncompressed packet",
|
||||||
skb->data, skb->len);
|
skb->data, skb->len);
|
||||||
|
|
||||||
/* Traffic class, flow label
|
/* Traffic Class, Flow Label compression */
|
||||||
* If flow label is 0, compress it. If traffic class is 0, compress it
|
iphc0 |= lowpan_iphc_tf_compress(&hc_ptr, hdr);
|
||||||
* We have to process both in the same time as the offset of traffic
|
|
||||||
* class depends on the presence of version and flow label
|
|
||||||
*/
|
|
||||||
|
|
||||||
/* hc format of TC is ECN | DSCP , original one is DSCP | ECN */
|
|
||||||
tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
|
|
||||||
tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
|
|
||||||
|
|
||||||
if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
|
|
||||||
(hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
|
|
||||||
/* flow label can be compressed */
|
|
||||||
iphc0 |= LOWPAN_IPHC_TF_10;
|
|
||||||
if ((hdr->priority == 0) &&
|
|
||||||
((hdr->flow_lbl[0] & 0xF0) == 0)) {
|
|
||||||
/* compress (elide) all */
|
|
||||||
iphc0 |= LOWPAN_IPHC_TF_11;
|
|
||||||
} else {
|
|
||||||
/* compress only the flow label */
|
|
||||||
*hc_ptr = tmp;
|
|
||||||
hc_ptr += 1;
|
|
||||||
}
|
|
||||||
} else {
|
|
||||||
/* Flow label cannot be compressed */
|
|
||||||
if ((hdr->priority == 0) &&
|
|
||||||
((hdr->flow_lbl[0] & 0xF0) == 0)) {
|
|
||||||
/* compress only traffic class */
|
|
||||||
iphc0 |= LOWPAN_IPHC_TF_01;
|
|
||||||
*hc_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
|
|
||||||
memcpy(hc_ptr + 1, &hdr->flow_lbl[1], 2);
|
|
||||||
hc_ptr += 3;
|
|
||||||
} else {
|
|
||||||
/* compress nothing */
|
|
||||||
memcpy(hc_ptr, hdr, 4);
|
|
||||||
/* replace the top byte with new ECN | DSCP format */
|
|
||||||
*hc_ptr = tmp;
|
|
||||||
hc_ptr += 4;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
/* NOTE: payload length is always compressed */
|
/* NOTE: payload length is always compressed */
|
||||||
|
|
||||||
|
|
|
||||||
Loading…
Reference in New Issue