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linux/net/6lowpan/iphc.c

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/*
* Copyright 2011, Siemens AG
* written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
*/
/* Based on patches from Jon Smirl <jonsmirl@gmail.com>
* Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* Jon's code is based on 6lowpan implementation for Contiki which is:
* Copyright (c) 2008, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <linux/bitops.h>
#include <linux/if_arp.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <net/6lowpan.h>
#include <net/ipv6.h>
#include <net/af_ieee802154.h>
/* Uncompress address function for source and
* destination address(non-multicast).
*
* address_mode is sam value or dam value.
*/
static int uncompress_addr(struct sk_buff *skb,
struct in6_addr *ipaddr, const u8 address_mode,
const u8 *lladdr, const u8 addr_type,
const u8 addr_len)
{
bool fail;
switch (address_mode) {
case LOWPAN_IPHC_ADDR_00:
/* for global link addresses */
fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
break;
case LOWPAN_IPHC_ADDR_01:
/* fe:80::XXXX:XXXX:XXXX:XXXX */
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
break;
case LOWPAN_IPHC_ADDR_02:
/* fe:80::ff:fe00:XXXX */
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
ipaddr->s6_addr[11] = 0xFF;
ipaddr->s6_addr[12] = 0xFE;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
break;
case LOWPAN_IPHC_ADDR_03:
fail = false;
switch (addr_type) {
case IEEE802154_ADDR_LONG:
/* fe:80::XXXX:XXXX:XXXX:XXXX
* \_________________/
* hwaddr
*/
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
/* second bit-flip (Universe/Local)
* is done according RFC2464
*/
ipaddr->s6_addr[8] ^= 0x02;
break;
case IEEE802154_ADDR_SHORT:
/* fe:80::ff:fe00:XXXX
* \__/
* short_addr
*
* Universe/Local bit is zero.
*/
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
ipaddr->s6_addr[11] = 0xFF;
ipaddr->s6_addr[12] = 0xFE;
ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
break;
default:
pr_debug("Invalid addr_type set\n");
return -EINVAL;
}
break;
default:
pr_debug("Invalid address mode value: 0x%x\n", address_mode);
return -EINVAL;
}
if (fail) {
pr_debug("Failed to fetch skb data\n");
return -EIO;
}
raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
ipaddr->s6_addr, 16);
return 0;
}
/* Uncompress address function for source context
* based address(non-multicast).
*/
static int uncompress_context_based_src_addr(struct sk_buff *skb,
struct in6_addr *ipaddr,
const u8 sam)
{
switch (sam) {
case LOWPAN_IPHC_ADDR_00:
/* unspec address ::
* Do nothing, address is already ::
*/
break;
case LOWPAN_IPHC_ADDR_01:
/* TODO */
case LOWPAN_IPHC_ADDR_02:
/* TODO */
case LOWPAN_IPHC_ADDR_03:
/* TODO */
netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
return -EINVAL;
default:
pr_debug("Invalid sam value: 0x%x\n", sam);
return -EINVAL;
}
raw_dump_inline(NULL,
"Reconstructed context based ipv6 src addr is",
ipaddr->s6_addr, 16);
return 0;
}
static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
struct net_device *dev, skb_delivery_cb deliver_skb)
{
struct sk_buff *new;
int stat;
new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
GFP_ATOMIC);
kfree_skb(skb);
if (!new)
return -ENOMEM;
skb_push(new, sizeof(struct ipv6hdr));
skb_reset_network_header(new);
skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
new->protocol = htons(ETH_P_IPV6);
new->pkt_type = PACKET_HOST;
new->dev = dev;
raw_dump_table(__func__, "raw skb data dump before receiving",
new->data, new->len);
stat = deliver_skb(new, dev);
kfree_skb(new);
return stat;
}
/* Uncompress function for multicast destination address,
* when M bit is set.
*/
static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
struct in6_addr *ipaddr,
const u8 dam)
{
bool fail;
switch (dam) {
case LOWPAN_IPHC_DAM_00:
/* 00: 128 bits. The full address
* is carried in-line.
*/
fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
break;
case LOWPAN_IPHC_DAM_01:
/* 01: 48 bits. The address takes
* the form ffXX::00XX:XXXX:XXXX.
*/
ipaddr->s6_addr[0] = 0xFF;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
break;
case LOWPAN_IPHC_DAM_10:
/* 10: 32 bits. The address takes
* the form ffXX::00XX:XXXX.
*/
ipaddr->s6_addr[0] = 0xFF;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
break;
case LOWPAN_IPHC_DAM_11:
/* 11: 8 bits. The address takes
* the form ff02::00XX.
*/
ipaddr->s6_addr[0] = 0xFF;
ipaddr->s6_addr[1] = 0x02;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
break;
default:
pr_debug("DAM value has a wrong value: 0x%x\n", dam);
return -EINVAL;
}
if (fail) {
pr_debug("Failed to fetch skb data\n");
return -EIO;
}
raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
ipaddr->s6_addr, 16);
return 0;
}
static int uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
{
bool fail;
u8 tmp = 0, val = 0;
fail = lowpan_fetch_skb(skb, &tmp, sizeof(tmp));
if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
pr_debug("UDP header uncompression\n");
switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
case LOWPAN_NHC_UDP_CS_P_00:
fail |= lowpan_fetch_skb(skb, &uh->source,
sizeof(uh->source));
fail |= lowpan_fetch_skb(skb, &uh->dest,
sizeof(uh->dest));
break;
case LOWPAN_NHC_UDP_CS_P_01:
fail |= lowpan_fetch_skb(skb, &uh->source,
sizeof(uh->source));
fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
uh->dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
break;
case LOWPAN_NHC_UDP_CS_P_10:
fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
uh->source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
fail |= lowpan_fetch_skb(skb, &uh->dest,
sizeof(uh->dest));
break;
case LOWPAN_NHC_UDP_CS_P_11:
fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
uh->source = htons(LOWPAN_NHC_UDP_4BIT_PORT +
(val >> 4));
uh->dest = htons(LOWPAN_NHC_UDP_4BIT_PORT +
(val & 0x0f));
break;
default:
pr_debug("ERROR: unknown UDP format\n");
goto err;
}
pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
ntohs(uh->source), ntohs(uh->dest));
/* checksum */
if (tmp & LOWPAN_NHC_UDP_CS_C) {
pr_debug_ratelimited("checksum elided currently not supported\n");
goto err;
} else {
fail |= lowpan_fetch_skb(skb, &uh->check,
sizeof(uh->check));
}
/* UDP length needs to be infered from the lower layers
* here, we obtain the hint from the remaining size of the
* frame
*/
uh->len = htons(skb->len + sizeof(struct udphdr));
pr_debug("uncompressed UDP length: src = %d", ntohs(uh->len));
} else {
pr_debug("ERROR: unsupported NH format\n");
goto err;
}
if (fail)
goto err;
return 0;
err:
return -EINVAL;
}
/* TTL uncompression values */
static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
const u8 *saddr, const u8 saddr_type, const u8 saddr_len,
const u8 *daddr, const u8 daddr_type, const u8 daddr_len,
u8 iphc0, u8 iphc1, skb_delivery_cb deliver_skb)
{
struct ipv6hdr hdr = {};
u8 tmp, num_context = 0;
int err;
raw_dump_table(__func__, "raw skb data dump uncompressed",
skb->data, skb->len);
/* another if the CID flag is set */
if (iphc1 & LOWPAN_IPHC_CID) {
pr_debug("CID flag is set, increase header with one\n");
if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context)))
goto drop;
}
hdr.version = 6;
/* Traffic Class and Flow Label */
switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
/* Traffic Class and FLow Label carried in-line
* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
*/
case 0: /* 00b */
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
goto drop;
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;
/* Traffic class carried in-line
* ECN + DSCP (1 byte), Flow Label is elided
*/
case 2: /* 10b */
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
goto drop;
hdr.priority = ((tmp >> 2) & 0x0f);
hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
break;
/* Flow Label carried in-line
* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
*/
case 1: /* 01b */
if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
goto drop;
hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
skb_pull(skb, 2);
break;
/* Traffic Class and Flow Label are elided */
case 3: /* 11b */
break;
default:
break;
}
/* Next Header */
if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
/* Next header is carried inline */
if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
goto drop;
pr_debug("NH flag is set, next header carried inline: %02x\n",
hdr.nexthdr);
}
/* Hop Limit */
if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I) {
hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
} else {
if (lowpan_fetch_skb(skb, &hdr.hop_limit,
sizeof(hdr.hop_limit)))
goto drop;
}
/* Extract SAM to the tmp variable */
tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
if (iphc1 & LOWPAN_IPHC_SAC) {
/* Source address context based uncompression */
pr_debug("SAC bit is set. Handle context based source address.\n");
err = uncompress_context_based_src_addr(skb, &hdr.saddr, tmp);
} else {
/* Source address uncompression */
pr_debug("source address stateless compression\n");
err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
saddr_type, saddr_len);
}
/* Check on error of previous branch */
if (err)
goto drop;
/* Extract DAM to the tmp variable */
tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
/* check for Multicast Compression */
if (iphc1 & LOWPAN_IPHC_M) {
if (iphc1 & LOWPAN_IPHC_DAC) {
pr_debug("dest: context-based mcast compression\n");
/* TODO: implement this */
} else {
err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
tmp);
if (err)
goto drop;
}
} else {
err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
daddr_type, daddr_len);
pr_debug("dest: stateless compression mode %d dest %pI6c\n",
tmp, &hdr.daddr);
if (err)
goto drop;
}
/* UDP data uncompression */
if (iphc0 & LOWPAN_IPHC_NH_C) {
struct udphdr uh;
struct sk_buff *new;
if (uncompress_udp_header(skb, &uh))
goto drop;
/* replace the compressed UDP head by the uncompressed UDP
* header
*/
new = skb_copy_expand(skb, sizeof(struct udphdr),
skb_tailroom(skb), GFP_ATOMIC);
kfree_skb(skb);
if (!new)
return -ENOMEM;
skb = new;
skb_push(skb, sizeof(struct udphdr));
skb_reset_transport_header(skb);
skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
raw_dump_table(__func__, "raw UDP header dump",
(u8 *)&uh, sizeof(uh));
hdr.nexthdr = UIP_PROTO_UDP;
}
hdr.payload_len = htons(skb->len);
pr_debug("skb headroom size = %d, data length = %d\n",
skb_headroom(skb), skb->len);
pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength = %d\n\t"
"nexthdr = 0x%02x\n\thop_lim = %d\n\tdest = %pI6c\n",
hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
hdr.hop_limit, &hdr.daddr);
raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
return skb_deliver(skb, &hdr, dev, deliver_skb);
drop:
kfree_skb(skb);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(lowpan_process_data);
static u8 lowpan_compress_addr_64(u8 **hc_ptr, u8 shift,
const struct in6_addr *ipaddr,
const unsigned char *lladdr)
{
u8 val = 0;
if (is_addr_mac_addr_based(ipaddr, lladdr)) {
val = 3; /* 0-bits */
pr_debug("address compression 0 bits\n");
} else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
/* compress IID to 16 bits xxxx::XXXX */
lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
val = 2; /* 16-bits */
raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
*hc_ptr - 2, 2);
} else {
/* do not compress IID => xxxx::IID */
lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
val = 1; /* 64-bits */
raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
*hc_ptr - 8, 8);
}
return rol8(val, shift);
}
static void compress_udp_header(u8 **hc_ptr, struct sk_buff *skb)
{
struct udphdr *uh = udp_hdr(skb);
u8 tmp;
if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
LOWPAN_NHC_UDP_4BIT_PORT) &&
((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
LOWPAN_NHC_UDP_4BIT_PORT)) {
pr_debug("UDP header: both ports compression to 4 bits\n");
/* compression value */
tmp = LOWPAN_NHC_UDP_CS_P_11;
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
/* source and destination port */
tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
} else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
LOWPAN_NHC_UDP_8BIT_PORT) {
pr_debug("UDP header: remove 8 bits of dest\n");
/* compression value */
tmp = LOWPAN_NHC_UDP_CS_P_01;
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
/* source port */
lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
/* destination port */
tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
} else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
LOWPAN_NHC_UDP_8BIT_PORT) {
pr_debug("UDP header: remove 8 bits of source\n");
/* compression value */
tmp = LOWPAN_NHC_UDP_CS_P_10;
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
/* source port */
tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
/* destination port */
lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
} else {
pr_debug("UDP header: can't compress\n");
/* compression value */
tmp = LOWPAN_NHC_UDP_CS_P_00;
lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
/* source port */
lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
/* destination port */
lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
}
/* checksum is always inline */
lowpan_push_hc_data(hc_ptr, &uh->check, sizeof(uh->check));
/* skip the UDP header */
skb_pull(skb, sizeof(struct udphdr));
}
int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
unsigned short type, const void *_daddr,
const void *_saddr, unsigned int len)
{
u8 tmp, iphc0, iphc1, *hc_ptr;
struct ipv6hdr *hdr;
u8 head[100] = {};
int addr_type;
if (type != ETH_P_IPV6)
return -EINVAL;
hdr = ipv6_hdr(skb);
hc_ptr = head + 2;
pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength = %d\n"
"\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest = %pI6c\n",
hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
hdr->hop_limit, &hdr->daddr);
raw_dump_table(__func__, "raw skb network header dump",
skb_network_header(skb), sizeof(struct ipv6hdr));
/* As we copy some bit-length fields, in the IPHC encoding bytes,
* we sometimes use |=
* If the field is 0, and the current bit value in memory is 1,
* this does not work. We therefore reset the IPHC encoding here
*/
iphc0 = LOWPAN_DISPATCH_IPHC;
iphc1 = 0;
/* TODO: context lookup */
raw_dump_inline(__func__, "saddr",
(unsigned char *)_saddr, IEEE802154_ADDR_LEN);
raw_dump_inline(__func__, "daddr",
(unsigned char *)_daddr, IEEE802154_ADDR_LEN);
raw_dump_table(__func__, "sending raw skb network uncompressed packet",
skb->data, skb->len);
/* Traffic class, flow label
* If flow label is 0, compress it. If traffic class is 0, compress it
* 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_FL_C;
if ((hdr->priority == 0) &&
((hdr->flow_lbl[0] & 0xF0) == 0)) {
/* compress (elide) all */
iphc0 |= LOWPAN_IPHC_TC_C;
} 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_TC_C;
*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 */
/* Next Header is compress if UDP */
if (hdr->nexthdr == UIP_PROTO_UDP)
iphc0 |= LOWPAN_IPHC_NH_C;
if ((iphc0 & LOWPAN_IPHC_NH_C) == 0)
lowpan_push_hc_data(&hc_ptr, &hdr->nexthdr,
sizeof(hdr->nexthdr));
/* Hop limit
* if 1: compress, encoding is 01
* if 64: compress, encoding is 10
* if 255: compress, encoding is 11
* else do not compress
*/
switch (hdr->hop_limit) {
case 1:
iphc0 |= LOWPAN_IPHC_TTL_1;
break;
case 64:
iphc0 |= LOWPAN_IPHC_TTL_64;
break;
case 255:
iphc0 |= LOWPAN_IPHC_TTL_255;
break;
default:
lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
sizeof(hdr->hop_limit));
}
addr_type = ipv6_addr_type(&hdr->saddr);
/* source address compression */
if (addr_type == IPV6_ADDR_ANY) {
pr_debug("source address is unspecified, setting SAC\n");
iphc1 |= LOWPAN_IPHC_SAC;
} else {
if (addr_type & IPV6_ADDR_LINKLOCAL) {
iphc1 |= lowpan_compress_addr_64(&hc_ptr,
LOWPAN_IPHC_SAM_BIT,
&hdr->saddr, _saddr);
pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
&hdr->saddr, iphc1);
} else {
pr_debug("send the full source address\n");
lowpan_push_hc_data(&hc_ptr, hdr->saddr.s6_addr, 16);
}
}
addr_type = ipv6_addr_type(&hdr->daddr);
/* destination address compression */
if (addr_type & IPV6_ADDR_MULTICAST) {
pr_debug("destination address is multicast: ");
iphc1 |= LOWPAN_IPHC_M;
if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
pr_debug("compressed to 1 octet\n");
iphc1 |= LOWPAN_IPHC_DAM_11;
/* use last byte */
lowpan_push_hc_data(&hc_ptr,
&hdr->daddr.s6_addr[15], 1);
} else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
pr_debug("compressed to 4 octets\n");
iphc1 |= LOWPAN_IPHC_DAM_10;
/* second byte + the last three */
lowpan_push_hc_data(&hc_ptr,
&hdr->daddr.s6_addr[1], 1);
lowpan_push_hc_data(&hc_ptr,
&hdr->daddr.s6_addr[13], 3);
} else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
pr_debug("compressed to 6 octets\n");
iphc1 |= LOWPAN_IPHC_DAM_01;
/* second byte + the last five */
lowpan_push_hc_data(&hc_ptr,
&hdr->daddr.s6_addr[1], 1);
lowpan_push_hc_data(&hc_ptr,
&hdr->daddr.s6_addr[11], 5);
} else {
pr_debug("using full address\n");
iphc1 |= LOWPAN_IPHC_DAM_00;
lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
}
} else {
if (addr_type & IPV6_ADDR_LINKLOCAL) {
/* TODO: context lookup */
iphc1 |= lowpan_compress_addr_64(&hc_ptr,
LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
pr_debug("dest address unicast link-local %pI6c "
"iphc1 0x%02x\n", &hdr->daddr, iphc1);
} else {
pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
}
}
/* UDP header compression */
if (hdr->nexthdr == UIP_PROTO_UDP)
compress_udp_header(&hc_ptr, skb);
head[0] = iphc0;
head[1] = iphc1;
skb_pull(skb, sizeof(struct ipv6hdr));
skb_reset_transport_header(skb);
memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
skb_reset_network_header(skb);
pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
raw_dump_table(__func__, "raw skb data dump compressed",
skb->data, skb->len);
return 0;
}
EXPORT_SYMBOL_GPL(lowpan_header_compress);
MODULE_LICENSE("GPL");
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