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Message-ID: <5661834E.9030306@osg.samsung.com>
Date: Fri, 4 Dec 2015 13:13:02 +0100
From: Stefan Schmidt <stefan@....samsung.com>
To: Alexander Aring <alex.aring@...il.com>
Cc: linux-wpan@...r.kernel.org, linux-bluetooth@...r.kernel.org,
netdev@...r.kernel.org, kernel@...gutronix.de, mcr@...delman.ca,
lukasz.duda@...dicsemi.no, martin.gergeleit@...rm.de
Subject: Re: [RFCv3 bluetooth-next 4/4] 6lowpan: iphc: add support for
stateful compression
Hello.
On 03/12/15 15:22, Alexander Aring wrote:
> Hi,
>
> On Wed, Dec 02, 2015 at 03:18:06PM +0100, Stefan Schmidt wrote:
>> Hello.
>>
>> A bit more review here. Still haven't tested the code.
>>
>> On 29/11/15 12:34, Alexander Aring wrote:
>>> This patch introduce support for IPHC stateful address compression. It
>>> will offer three debugfs per interface entries, which are:
>>>
>>> - dci_table: destination context indentifier table
>>> - sci_table: source context indentifier table
>>> - mcast_sci_table: multicast context identifier table
>>>
>>> Example to setup a context id:
>>>
>>> A "cat /sys/kernel/debug/6lowpan/lowpan0/dci_table" will display all
>>> contexts which are available. Example:
>>>
>>> ID ipv6-address/prefix-length enabled
>>> 0 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 1 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 2 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 3 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 4 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 5 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 6 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 7 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 8 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 9 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 10 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 11 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 12 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 13 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 14 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>> 15 0000:0000:0000:0000:0000:0000:0000:0000/0 0
>>>
>>> For setting a context e.g. context id 0, context 2001::, prefix-length
>>> 64.
>>>
>>> Hint: Simple copy one line and then maniuplate it.
>>>
>>> echo "0 2001:0000:0000:0000:0000:0000:0000:0000/64 1" >
>>> /sys/kernel/debug/6lowpan/lowpan0/dci_table
>>>
>>> The enabled column will display currently if the context is disabled(0) or
>>> enabled(1).
>>>
>>> On transmit side:
>>>
>>> The IPHC code will automatically search for a context which would be
>>> match for the address. Then it will be use the context with the
>>> best compression method. Means the longest prefix which match will be
>>> used.
>>>
>>> Example:
>>>
>>> 2001::/126 vs 2001::/127 - the 2001::/127 can be full compressed if the
>>> last bit of the address which has the prefix 2001::/127 is the same like
>>> the IID from the Encapsulating Header. A context ID can also be a
>>> 2001::1/128, which is then a full ipv6 address.
>>>
>>> On Receive side:
>>>
>>> If there is a context defined (when CID not available then it's the
>>> default context 0) then it will be used, if the header doesn't set
>>> SAC or DAC bit thens, it will be dropped.
>>>
>>> Signed-off-by: Alexander Aring <alex.aring@...il.com>
>>> ---
>>> include/net/6lowpan.h | 54 ++++++
>>> net/6lowpan/6lowpan_i.h | 3 +
>>> net/6lowpan/core.c | 17 +-
>>> net/6lowpan/debugfs.c | 113 ++++++++++++
>>> net/6lowpan/iphc.c | 479 ++++++++++++++++++++++++++++++++++++++++++------
>>> 5 files changed, 608 insertions(+), 58 deletions(-)
>>>
>>> diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h
>>> index 2f6a3f2..dec5427 100644
>>> --- a/include/net/6lowpan.h
>>> +++ b/include/net/6lowpan.h
>>> @@ -75,6 +75,8 @@
>>> #define LOWPAN_IPHC_MAX_HC_BUF_LEN (sizeof(struct ipv6hdr) + \
>>> LOWPAN_IPHC_MAX_HEADER_LEN + \
>>> LOWPAN_NHC_MAX_HDR_LEN)
>>> +/* SCI/DCI is 4 bit width, so we have maximum 16 entries */
>>> +#define LOWPAN_IPHC_CI_TABLE_SIZE (1 << 4)
>>> #define LOWPAN_DISPATCH_IPV6 0x41 /* 01000001 = 65 */
>>> #define LOWPAN_DISPATCH_IPHC 0x60 /* 011xxxxx = ... */
>>> @@ -98,9 +100,37 @@ enum lowpan_lltypes {
>>> LOWPAN_LLTYPE_IEEE802154,
>>> };
>>> +struct lowpan_iphc_ctx {
>>> + u8 id;
>>> + struct in6_addr addr;
>>> + u8 prefix_len;
>>> + bool enabled;
>>> +};
>>> +
>>> +struct lowpan_iphc_ctx_ops {
>>> + bool (*valid_prefix)(const struct lowpan_iphc_ctx *ctx);
>>> + int (*update)(struct lowpan_iphc_ctx *table,
>>> + const struct lowpan_iphc_ctx *ctx);
>>> + struct lowpan_iphc_ctx *(*get_by_id)(const struct net_device *dev,
>>> + struct lowpan_iphc_ctx *table,
>>> + u8 id);
>>> + struct lowpan_iphc_ctx *(*get_by_addr)(const struct net_device *dev,
>>> + struct lowpan_iphc_ctx *table,
>>> + const struct in6_addr *addr);
>>> +};
>>> +
>>> +struct lowpan_iphc_ctx_table {
>>> + spinlock_t lock;
>>> + const struct lowpan_iphc_ctx_ops *ops;
>>> + struct lowpan_iphc_ctx table[LOWPAN_IPHC_CI_TABLE_SIZE];
>>> +};
>>> +
>>> struct lowpan_priv {
>>> enum lowpan_lltypes lltype;
>>> struct dentry *iface_debugfs;
>>> + struct lowpan_iphc_ctx_table iphc_dci;
>>> + struct lowpan_iphc_ctx_table iphc_sci;
>>> + struct lowpan_iphc_ctx_table iphc_mcast_dci;
>>> /* must be last */
>>> u8 priv[0] __aligned(sizeof(void *));
>>> @@ -125,6 +155,30 @@ struct lowpan_802154_cb *lowpan_802154_cb(const struct sk_buff *skb)
>>> return (struct lowpan_802154_cb *)skb->cb;
>>> }
>>> +static inline int lowpan_ctx_update(struct lowpan_iphc_ctx_table *t,
>>> + const struct lowpan_iphc_ctx *ctx)
>>> +{
>>> + if (!t->ops->valid_prefix(ctx))
>>> + return -EINVAL;
>>> +
>>> + return t->ops->update(t->table, ctx);
>>> +}
>>> +
>>> +static inline struct lowpan_iphc_ctx *
>>> +lowpan_ctx_by_id(const struct net_device *dev, struct lowpan_iphc_ctx_table *t,
>>> + u8 id)
>>> +{
>>> + return t->ops->get_by_id(dev, t->table, id);
>>> +}
>>> +
>>> +static inline struct lowpan_iphc_ctx *
>>> +lowpan_ctx_by_addr(const struct net_device *dev,
>>> + struct lowpan_iphc_ctx_table *t,
>>> + const struct in6_addr *addr)
>>> +{
>>> + return t->ops->get_by_addr(dev, t->table, addr);
>>> +}
>>> +
>>> #ifdef DEBUG
>>> /* print data in line */
>>> static inline void raw_dump_inline(const char *caller, char *msg,
>>> diff --git a/net/6lowpan/6lowpan_i.h b/net/6lowpan/6lowpan_i.h
>>> index d16bb4b..2c275be 100644
>>> --- a/net/6lowpan/6lowpan_i.h
>>> +++ b/net/6lowpan/6lowpan_i.h
>>> @@ -3,6 +3,9 @@
>>> #include <linux/netdevice.h>
>>> +extern const struct lowpan_iphc_ctx_ops iphc_ctx_unicast_ops;
>>> +extern const struct lowpan_iphc_ctx_ops iphc_ctx_mcast_ops;
>>> +
>>> #ifdef CONFIG_6LOWPAN_DEBUGFS
>>> int lowpan_dev_debugfs_init(struct net_device *dev);
>>> void lowpan_dev_debugfs_exit(struct net_device *dev);
>>> diff --git a/net/6lowpan/core.c b/net/6lowpan/core.c
>>> index c7f06f5..f3dbd18 100644
>>> --- a/net/6lowpan/core.c
>>> +++ b/net/6lowpan/core.c
>>> @@ -20,7 +20,7 @@
>>> int lowpan_register_netdevice(struct net_device *dev,
>>> enum lowpan_lltypes lltype)
>>> {
>>> - int ret;
>>> + int i, ret;
>>> dev->addr_len = EUI64_ADDR_LEN;
>>> dev->type = ARPHRD_6LOWPAN;
>>> @@ -29,6 +29,21 @@ int lowpan_register_netdevice(struct net_device *dev,
>>> lowpan_priv(dev)->lltype = lltype;
>>> + spin_lock_init(&lowpan_priv(dev)->iphc_dci.lock);
>>> + lowpan_priv(dev)->iphc_dci.ops = &iphc_ctx_unicast_ops;
>>> +
>>> + spin_lock_init(&lowpan_priv(dev)->iphc_sci.lock);
>>> + lowpan_priv(dev)->iphc_sci.ops = &iphc_ctx_unicast_ops;
>>> +
>>> + spin_lock_init(&lowpan_priv(dev)->iphc_mcast_dci.lock);
>>> + lowpan_priv(dev)->iphc_mcast_dci.ops = &iphc_ctx_mcast_ops;
>>> +
>>> + for (i = 0; i < LOWPAN_IPHC_CI_TABLE_SIZE; i++) {
>>> + lowpan_priv(dev)->iphc_dci.table[i].id = i;
>>> + lowpan_priv(dev)->iphc_sci.table[i].id = i;
>>> + lowpan_priv(dev)->iphc_mcast_dci.table[i].id = i;
>>> + }
>>> +
>>> ret = lowpan_dev_debugfs_init(dev);
>>> if (ret < 0)
>>> return ret;
>>> diff --git a/net/6lowpan/debugfs.c b/net/6lowpan/debugfs.c
>>> index 88eef84..24f94ac 100644
>>> --- a/net/6lowpan/debugfs.c
>>> +++ b/net/6lowpan/debugfs.c
>>> @@ -16,19 +16,132 @@
>>> #include "6lowpan_i.h"
>>> +#define LOWPAN_DEBUGFS_CTX_NUM_ARGS 11
>>> +
>>> static struct dentry *lowpan_debugfs;
>>> +static int lowpan_context_show(struct seq_file *file, void *offset)
>>> +{
>>> + struct lowpan_iphc_ctx_table *t = file->private;
>>> + int i;
>>> +
>>> + seq_printf(file, "%-2s %-43s %s\n", "ID", "ipv6-address/prefix-length",
>>> + "enabled");
>>> +
>>> + spin_lock_bh(&t->lock);
>>> + for (i = 0; i < LOWPAN_IPHC_CI_TABLE_SIZE; i++) {
>>> + seq_printf(file,
>>> + "%-2d %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x/%-3d %d\n",
>>> + t->table[i].id,
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[0]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[1]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[2]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[3]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[4]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[5]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[6]),
>>> + be16_to_cpu(t->table[i].addr.s6_addr16[7]),
>>> + t->table[i].prefix_len, t->table[i].enabled);
>>> + }
>>> + spin_unlock_bh(&t->lock);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int lowpan_context_dbgfs_open(struct inode *inode, struct file *file)
>>> +{
>>> + return single_open(file, lowpan_context_show, inode->i_private);
>>> +}
>>> +
>>> +static ssize_t lowpan_context_dbgfs_write(struct file *fp,
>>> + const char __user *user_buf,
>>> + size_t count, loff_t *ppos)
>>> +{
>>> + char buf[128] = { };
>> Do we enforce the 128 char limit somewhere?
>>
>>> + struct seq_file *file = fp->private_data;
>>> + struct lowpan_iphc_ctx_table *t = file->private;
>>> + struct lowpan_iphc_ctx ctx;
>>> + int status = count, n, id, enabled, i, prefix_len, ret;
>>> + unsigned int addr[8];
>>> +
>>> + if (copy_from_user(&buf, user_buf, min_t(size_t, sizeof(buf) - 1,
>>> + count))) {
>> I see we do here, ok.
>>
>>> + status = -EFAULT;
>>> + goto out;
>>> + }
>>> +
>>> + n = sscanf(buf, "%d %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x/%d %d",
>>> + &id, &addr[0], &addr[1], &addr[2], &addr[3], &addr[4],
>>> + &addr[5], &addr[6], &addr[7], &prefix_len, &enabled);
>>> + if (n != LOWPAN_DEBUGFS_CTX_NUM_ARGS) {
>>> + status = -EIO;
>>> + goto out;
>>> + }
>>> +
>>> + if (id > LOWPAN_IPHC_CI_TABLE_SIZE - 1 ||
>>> + (enabled != 0 && enabled != 1) || prefix_len > 128) {
>> Hmm, if you would use a bool for enabled here instead of an int the check on
>> enabled would not be needed.
>>
> This is because sscanf format string excepts an int here to parsing the
> "%d" argument.
>
> I adapt the same mechanism here what we have for "bools" for nl802154.
>
> When I change it to bool, I will get:
>
> net/6lowpan/debugfs.c: In function 'lowpan_context_dbgfs_write':
> net/6lowpan/debugfs.c:76:6: warning: format '%d' expects argument of
> type 'int *', but argument 13 has type 'bool *' [-Wformat=]
> &addr[5], &addr[6], &addr[7], &prefix_len, &enabled);
Ah, right, scanf has no support for bool. :( Guess we keep it as int.
>
>>> + status = -EINVAL;
>>> + goto out;
>>> + }
>>> +
>>> + ctx.id = id;
>>> + ctx.enabled = enabled;
> conversion to bool is here, I could do "!!enabled" and remove the check
> above, but then is 1 <-> MAX_INT and -1 <-> MIN_INT also true.
Nah, leave it as is. I was under the impüression we could use scanf for
bool directly. That not being the case we can keep it as is.
>
>>> + ctx.prefix_len = prefix_len;
>>> +
>>> + for (i = 0; i < 8; i++)
>>> + ctx.addr.s6_addr16[i] = cpu_to_be16(addr[i] & 0xffff);
>>> +
>>> + spin_lock_bh(&t->lock);
>>> + ret = lowpan_ctx_update(t, &ctx);
>>> + if (ret < 0)
>>> + status = ret;
>>> + spin_unlock_bh(&t->lock);
>>> +
>>> +out:
>>> + return status;
>>> +}
>>> +
>>> +const struct file_operations lowpan_context_fops = {
>>> + .open = lowpan_context_dbgfs_open,
>>> + .read = seq_read,
>>> + .write = lowpan_context_dbgfs_write,
>>> + .llseek = seq_lseek,
>>> + .release = single_release,
>>> +};
>>> +
>>> int lowpan_dev_debugfs_init(struct net_device *dev)
>>> {
>>> struct lowpan_priv *lpriv = lowpan_priv(dev);
>>> + static struct dentry *dentry;
>>> /* creating the root */
>>> lpriv->iface_debugfs = debugfs_create_dir(dev->name, lowpan_debugfs);
>>> if (!lpriv->iface_debugfs)
>>> goto fail;
>>> + dentry = debugfs_create_file("dci_table", 0664, lpriv->iface_debugfs,
>> Any special reason you want the group have write permissions? I would expect
>> a 644 here. Same for the other two.
>>
> No, I will change it to 0644.
Great, thanks.
>
>>> + &lowpan_priv(dev)->iphc_dci,
>>> + &lowpan_context_fops);
>>> + if (!dentry)
>>> + goto remove_root;
>>> +
>>> + dentry = debugfs_create_file("sci_table", 0664, lpriv->iface_debugfs,
>>> + &lowpan_priv(dev)->iphc_sci,
>>> + &lowpan_context_fops);
>>> + if (!dentry)
>>> + goto remove_root;
>>> +
>>> + dentry = debugfs_create_file("mcast_dci_table", 0664,
>>> + lpriv->iface_debugfs,
>>> + &lowpan_priv(dev)->iphc_mcast_dci,
>>> + &lowpan_context_fops);
>>> + if (!dentry)
>>> + goto remove_root;
>>> +
>>> return 0;
>>> +remove_root:
>>> + lowpan_dev_debugfs_exit(dev);
>> Just to check here. This one is calling debugfs_remove_recursive(). This
>> will cleanup states where we might have been able to create dci_table and
>> sci_table but not mcast_dci_table, right?
> Yes, should. I will remove the whole interface related debugfs entry
> inclusive all sub-entries which was created under the interface related
> directory entry which is in this case sci/dci/mcast_dci tables.
OK
>>> fail:
>>> return -EINVAL;
>>> }
>>> diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
>>> index 346b5c1..2c5004b 100644
>>> --- a/net/6lowpan/iphc.c
>>> +++ b/net/6lowpan/iphc.c
>>> @@ -56,6 +56,7 @@
>>> /* special link-layer handling */
>>> #include <net/mac802154.h>
>>> +#include "6lowpan_i.h"
>>> #include "nhc.h"
>>> /* Values of fields within the IPHC encoding first byte */
>>> @@ -147,6 +148,9 @@
>>> (((a)->s6_addr16[6]) == 0) && \
>>> (((a)->s6_addr[14]) == 0))
>>> +#define LOWPAN_IPHC_CID_DCI(cid) (cid & 0x0f)
>>> +#define LOWPAN_IPHC_CID_SCI(cid) ((cid & 0xf0) >> 4)
>>> +
>>> static inline void iphc_uncompress_eui64_lladdr(struct in6_addr *ipaddr,
>>> const void *lladdr)
>>> {
>>> @@ -259,30 +263,59 @@ static int uncompress_addr(struct sk_buff *skb, const struct net_device *dev,
>>> /* 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,
>>> - u8 address_mode)
>>> +static int uncompress_ctx_addr(struct sk_buff *skb,
>>> + const struct net_device *dev,
>>> + const struct lowpan_iphc_ctx *ctx,
>>> + struct in6_addr *ipaddr, u8 address_mode,
>>> + const void *lladdr)
>>> {
>>> + bool fail;
>>> +
>>> switch (address_mode) {
>>> - case LOWPAN_IPHC_SAM_00:
>>> - /* unspec address ::
>>> + /* SAM and DAM are the same here */
>>> + case LOWPAN_IPHC_DAM_00:
>>> + fail = false;
>>> + /* SAM_00 -> unspec address ::
>>> * Do nothing, address is already ::
>>> + *
>>> + * DAM 00 -> reserved should never occur.
>>> */
>>> break;
>>> case LOWPAN_IPHC_SAM_01:
>>> - /* TODO */
>>> + case LOWPAN_IPHC_DAM_01:
>>> + fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
>>> + ipv6_addr_prefix_copy(ipaddr, &ctx->addr, ctx->prefix_len);
>>> + break;
>>> case LOWPAN_IPHC_SAM_10:
>>> - /* TODO */
>>> + case LOWPAN_IPHC_DAM_10:
>>> + ipaddr->s6_addr[11] = 0xFF;
>>> + ipaddr->s6_addr[12] = 0xFE;
>>> + fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
>>> + ipv6_addr_prefix_copy(ipaddr, &ctx->addr, ctx->prefix_len);
>>> + break;
>>> case LOWPAN_IPHC_SAM_11:
>>> - /* TODO */
>>> - netdev_warn(skb->dev, "SAM value 0x%x not supported\n",
>>> - address_mode);
>>> - return -EINVAL;
>>> + case LOWPAN_IPHC_DAM_11:
>>> + fail = false;
>>> + switch (lowpan_priv(dev)->lltype) {
>>> + case LOWPAN_LLTYPE_IEEE802154:
>>> + iphc_uncompress_802154_lladdr(ipaddr, lladdr);
>>> + break;
>>> + default:
>>> + iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
>>> + break;
>>> + }
>>> + ipv6_addr_prefix_copy(ipaddr, &ctx->addr, ctx->prefix_len);
>>> + break;
>>> default:
>>> pr_debug("Invalid sam 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 context based ipv6 src addr is",
>>> ipaddr->s6_addr, 16);
>>> @@ -346,6 +379,33 @@ static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
>>> return 0;
>>> }
>>> +static int lowpan_uncompress_multicast_ctx_daddr(struct sk_buff *skb,
>>> + struct lowpan_iphc_ctx *ctx,
>>> + struct in6_addr *ipaddr,
>>> + u8 address_mode)
>>> +{
>>> + struct in6_addr network_pfx = {};
>>> + bool fail;
>>> +
>>> + if (address_mode != LOWPAN_IPHC_DAM_00)
>>> + return -EINVAL;
>>> +
>>> + ipaddr->s6_addr[0] = 0xFF;
>>> + fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 2);
>>> + fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[12], 4);
>>> + /* take prefix_len and network prefix from the context */
>>> + ipaddr->s6_addr[3] = ctx->prefix_len;
>>> + /* get network prefix to copy into multicast address */
>>> + ipv6_addr_prefix(&network_pfx, &ctx->addr, ctx->prefix_len);
>>> + /* setting network prefix */
>>> + memcpy(&ipaddr->s6_addr[4], &network_pfx, 8);
>>> +
>>> + if (fail < 0)
>>> + return -EIO;
>>> +
>>> + 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)
>>> {
>>> @@ -459,7 +519,8 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
>>> const void *daddr, const void *saddr)
>>> {
>>> struct ipv6hdr hdr = {};
>>> - u8 iphc0, iphc1;
>>> + struct lowpan_iphc_ctx *ci;
>>> + u8 iphc0, iphc1, cid = 0;
>>> int err;
>>> raw_dump_table(__func__, "raw skb data dump uncompressed",
>>> @@ -469,12 +530,14 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
>>> lowpan_fetch_skb(skb, &iphc1, sizeof(iphc1)))
>>> return -EINVAL;
>>> - /* another if the CID flag is set */
>>> - if (iphc1 & LOWPAN_IPHC_CID)
>>> - return -ENOTSUPP;
>>> -
>>> hdr.version = 6;
>>> + /* default CID = 0, another if the CID flag is set */
>>> + if (iphc1 & LOWPAN_IPHC_CID) {
>>> + if (lowpan_fetch_skb(skb, &cid, sizeof(cid)))
>>> + return -EINVAL;
>>> + }
>>> +
>>> err = lowpan_iphc_tf_decompress(skb, &hdr,
>>> iphc0 & LOWPAN_IPHC_TF_MASK);
>>> if (err < 0)
>>> @@ -500,10 +563,18 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
>>> }
>>> if (iphc1 & LOWPAN_IPHC_SAC) {
>>> - /* Source address context based uncompression */
>>> + spin_lock_bh(&lowpan_priv(dev)->iphc_sci.lock);
>>> + ci = lowpan_ctx_by_id(dev, &lowpan_priv(dev)->iphc_sci,
>>> + LOWPAN_IPHC_CID_SCI(cid));
>>> + if (!ci) {
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_sci.lock);
>>> + return -EINVAL;
>>> + }
>>> +
>>> pr_debug("SAC bit is set. Handle context based source address.\n");
>>> - err = uncompress_context_based_src_addr(skb, &hdr.saddr,
>>> - iphc1 & LOWPAN_IPHC_SAM_MASK);
>>> + err = uncompress_ctx_addr(skb, dev, ci, &hdr.saddr,
>>> + iphc1 & LOWPAN_IPHC_SAM_MASK, saddr);
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_sci.lock);
>>> } else {
>>> /* Source address uncompression */
>>> pr_debug("source address stateless compression\n");
>>> @@ -515,27 +586,54 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
>>> if (err)
>>> return -EINVAL;
>>> - /* 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,
>>> - iphc1 & LOWPAN_IPHC_DAM_MASK);
>>> + switch (iphc1 & (LOWPAN_IPHC_M | LOWPAN_IPHC_DAC)) {
>>> + case LOWPAN_IPHC_M | LOWPAN_IPHC_DAC:
>>> + spin_lock_bh(&lowpan_priv(dev)->iphc_mcast_dci.lock);
>>> + ci = lowpan_ctx_by_id(dev, &lowpan_priv(dev)->iphc_mcast_dci,
>>> + LOWPAN_IPHC_CID_DCI(cid));
>>> + if (!ci) {
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_mcast_dci.lock);
>>> + return -EINVAL;
>>> + }
>>> - if (err)
>>> - return -EINVAL;
>>> + /* multicast with context */
>>> + pr_debug("dest: context-based mcast compression\n");
>>> + err = lowpan_uncompress_multicast_ctx_daddr(skb, ci,
>>> + &hdr.daddr,
>>> + iphc1 & LOWPAN_IPHC_DAM_MASK);
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_mcast_dci.lock);
>>> + break;
>>> + case LOWPAN_IPHC_M:
>>> + /* multicast */
>>> + err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
>>> + iphc1 & LOWPAN_IPHC_DAM_MASK);
>>> + break;
>>> + case LOWPAN_IPHC_DAC:
>>> + spin_lock_bh(&lowpan_priv(dev)->iphc_dci.lock);
>>> + ci = lowpan_ctx_by_id(dev, &lowpan_priv(dev)->iphc_dci,
>>> + LOWPAN_IPHC_CID_DCI(cid));
>>> + if (!ci) {
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_dci.lock);
>>> + return -EINVAL;
>>> }
>>> - } else {
>>> +
>>> + /* Destination address context based uncompression */
>>> + pr_debug("DAC bit is set. Handle context based destination address.\n");
>>> + err = uncompress_ctx_addr(skb, dev, ci, &hdr.daddr,
>>> + iphc1 & LOWPAN_IPHC_DAM_MASK, daddr);
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_dci.lock);
>>> + break;
>>> + default:
>>> err = uncompress_addr(skb, dev, &hdr.daddr,
>>> iphc1 & LOWPAN_IPHC_DAM_MASK, daddr);
>>> pr_debug("dest: stateless compression mode %d dest %pI6c\n",
>>> iphc1 & LOWPAN_IPHC_DAM_MASK, &hdr.daddr);
>>> - if (err)
>>> - return -EINVAL;
>>> + break;
>>> }
>>> + if (err)
>>> + return -EINVAL;
>>> +
>>> /* Next header data uncompression */
>>> if (iphc0 & LOWPAN_IPHC_NH) {
>>> err = lowpan_nhc_do_uncompression(skb, dev, &hdr);
>>> @@ -585,6 +683,60 @@ static const u8 lowpan_iphc_dam_to_sam_value[] = {
>>> [LOWPAN_IPHC_DAM_11] = LOWPAN_IPHC_SAM_11,
>>> };
>>> +static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct in6_addr *ipaddr,
>>> + const struct lowpan_iphc_ctx *ctx,
>>> + const unsigned char *lladdr, bool sam)
>>> +{
>>> + struct in6_addr tmp = {};
>>> + u8 dam;
>>> +
>>> + /* check for SAM/DAM = 11 */
>>> + memcpy(&tmp.s6_addr[8], lladdr, 8);
>>> + /* second bit-flip (Universe/Local)
>>> + * is done according RFC2464
>>> + */
>> Maybe put this comment on line. It should be short enough.
>>
> ok.
>
>>> + tmp.s6_addr[8] ^= 0x02;
>>> + /* context information are always used */
>>> + ipv6_addr_prefix_copy(&tmp, &ctx->addr, ctx->prefix_len);
>>> + if (ipv6_addr_equal(&tmp, ipaddr)) {
>>> + dam = LOWPAN_IPHC_DAM_11;
>>> + goto out;
>>> + }
>>> +
>>> + memset(&tmp, 0, sizeof(tmp));
>>> + /* check for SAM/DAM = 01 */
>>> + tmp.s6_addr[11] = 0xFF;
>>> + tmp.s6_addr[12] = 0xFE;
>>> + memcpy(&tmp.s6_addr[14], &ipaddr->s6_addr[14], 2);
>>> + /* context information are always used */
>>> + ipv6_addr_prefix_copy(&tmp, &ctx->addr, ctx->prefix_len);
>>> + if (ipv6_addr_equal(&tmp, ipaddr)) {
>>> + lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[14], 2);
>>> + dam = LOWPAN_IPHC_DAM_10;
>>> + goto out;
>>> + }
>>> +
>>> + memset(&tmp, 0, sizeof(tmp));
>>> + /* check for SAM/DAM = 10, should always match */
>>> + memcpy(&tmp.s6_addr[8], &ipaddr->s6_addr[8], 8);
>>> + /* context information are always used */
>>> + ipv6_addr_prefix_copy(&tmp, &ctx->addr, ctx->prefix_len);
>>> + if (ipv6_addr_equal(&tmp, ipaddr)) {
>>> + lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[8], 8);
>>> + dam = LOWPAN_IPHC_DAM_01;
>>> + goto out;
>>> + }
>>> +
>>> + WARN_ON_ONCE("context found but no address mode matched\n");
>>> + return -EINVAL;
>>> +out:
>>> +
>>> + if (sam)
>>> + return lowpan_iphc_dam_to_sam_value[dam];
>>> + else
>>> + return dam;
>>> +}
>>> +
>>> static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct in6_addr *ipaddr,
>>> const unsigned char *lladdr, bool sam)
>>> {
>>> @@ -708,6 +860,21 @@ static u8 lowpan_iphc_tf_compress(u8 **hc_ptr, const struct ipv6hdr *hdr)
>>> return val;
>>> }
>>> +static u8 lowpan_iphc_mcast_ctx_addr_compress(u8 **hc_ptr,
>>> + const struct lowpan_iphc_ctx *ctx,
>>> + const struct in6_addr *ipaddr)
>>> +{
>>> + u8 data[6];
>>> +
>>> + /* flags/scope, reserved (RIID) */
>>> + memcpy(data, &ipaddr->s6_addr[1], 2);
>>> + /* group ID */
>>> + memcpy(&data[1], &ipaddr->s6_addr[11], 4);
>>> + lowpan_push_hc_data(hc_ptr, data, 6);
>>> +
>>> + return LOWPAN_IPHC_DAM_00;
>>> +}
>>> +
>>> static u8 lowpan_iphc_mcast_addr_compress(u8 **hc_ptr,
>>> const struct in6_addr *ipaddr)
>>> {
>>> @@ -742,10 +909,11 @@ static u8 lowpan_iphc_mcast_addr_compress(u8 **hc_ptr,
>>> int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
>>> const void *daddr, const void *saddr)
>>> {
>>> - u8 iphc0, iphc1, *hc_ptr;
>>> + u8 iphc0, iphc1, *hc_ptr, cid = 0;
>>> struct ipv6hdr *hdr;
>>> u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
>>> - int ret, addr_type;
>>> + struct lowpan_iphc_ctx *dci, *sci, dci_entry, sci_entry;
>>> + int ret, ipv6_daddr_type, ipv6_saddr_type;
>>> if (skb->protocol != htons(ETH_P_IPV6))
>>> return -EINVAL;
>>> @@ -769,14 +937,47 @@ int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
>>> iphc0 = LOWPAN_DISPATCH_IPHC;
>>> iphc1 = 0;
>>> - /* TODO: context lookup */
>>> -
>>> raw_dump_inline(__func__, "saddr", saddr, EUI64_ADDR_LEN);
>>> raw_dump_inline(__func__, "daddr", daddr, EUI64_ADDR_LEN);
>>> raw_dump_table(__func__, "sending raw skb network uncompressed packet",
>>> skb->data, skb->len);
>>> + ipv6_daddr_type = ipv6_addr_type(&hdr->daddr);
>>> + if (ipv6_daddr_type & IPV6_ADDR_MULTICAST) {
>>> + spin_lock_bh(&lowpan_priv(dev)->iphc_mcast_dci.lock);
>>> + dci = lowpan_ctx_by_addr(dev, &lowpan_priv(dev)->iphc_mcast_dci,
>>> + &hdr->daddr);
>>> + if (dci) {
>>> + memcpy(&dci_entry, dci, sizeof(*dci));
>>> + cid |= dci->id;
>>> + }
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_mcast_dci.lock);
>>> + } else {
>>> + spin_lock_bh(&lowpan_priv(dev)->iphc_dci.lock);
>>> + dci = lowpan_ctx_by_addr(dev, &lowpan_priv(dev)->iphc_dci,
>>> + &hdr->daddr);
>>> + if (dci) {
>>> + memcpy(&dci_entry, dci, sizeof(*dci));
>>> + cid |= dci->id;
>>> + }
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_dci.lock);
>>> + }
>>> +
>>> + spin_lock_bh(&lowpan_priv(dev)->iphc_sci.lock);
>>> + sci = lowpan_ctx_by_addr(dev, &lowpan_priv(dev)->iphc_sci,
>>> + &hdr->saddr);
>>> + if (sci) {
>>> + memcpy(&sci_entry, sci, sizeof(*sci));
>>> + cid |= (sci->id << 4);
>>> + }
>>> + spin_unlock_bh(&lowpan_priv(dev)->iphc_sci.lock);
>>> +
>>> + if (sci || dci) {
>>> + iphc1 |= LOWPAN_IPHC_CID;
>>> + lowpan_push_hc_data(&hc_ptr, &cid, sizeof(cid));
>>> + }
>>> +
>>> /* Traffic Class, Flow Label compression */
>>> iphc0 |= lowpan_iphc_tf_compress(&hc_ptr, hdr);
>>> @@ -813,39 +1014,63 @@ int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
>>> sizeof(hdr->hop_limit));
>>> }
>>> - addr_type = ipv6_addr_type(&hdr->saddr);
>>> + ipv6_saddr_type = ipv6_addr_type(&hdr->saddr);
>>> /* source address compression */
>>> - if (addr_type == IPV6_ADDR_ANY) {
>>> + if (ipv6_saddr_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, &hdr->saddr,
>>> - saddr, true);
>>> - pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
>>> - &hdr->saddr, iphc1);
>>> + if (sci) {
>>> + iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, &hdr->saddr,
>>> + &sci_entry, saddr,
>>> + true);
>>> + iphc1 |= LOWPAN_IPHC_SAC;
>>> } else {
>>> - pr_debug("send the full source address\n");
>>> - lowpan_push_hc_data(&hc_ptr, hdr->saddr.s6_addr, 16);
>>> + if (ipv6_saddr_type & IPV6_ADDR_LINKLOCAL) {
>>> + iphc1 |= lowpan_compress_addr_64(&hc_ptr,
>>> + &hdr->saddr,
>>> + saddr, true);
>>> + 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) {
>>> + if (ipv6_daddr_type & IPV6_ADDR_MULTICAST) {
>>> pr_debug("destination address is multicast: ");
>>> - iphc1 |= LOWPAN_IPHC_M;
>>> - iphc1 |= lowpan_iphc_mcast_addr_compress(&hc_ptr, &hdr->daddr);
>>> + if (dci) {
>>> + iphc1 |= lowpan_iphc_mcast_ctx_addr_compress(&hc_ptr,
>>> + &dci_entry,
>>> + &hdr->daddr);
>>> + } else {
>>> + iphc1 |= LOWPAN_IPHC_M;
>>> + iphc1 |= lowpan_iphc_mcast_addr_compress(&hc_ptr,
>>> + &hdr->daddr);
>>> + }
>>> } else {
>>> - if (addr_type & IPV6_ADDR_LINKLOCAL) {
>>> - /* TODO: context lookup */
>>> - iphc1 |= lowpan_compress_addr_64(&hc_ptr, &hdr->daddr,
>>> - daddr, false);
>>> - pr_debug("dest address unicast link-local %pI6c "
>>> - "iphc1 0x%02x\n", &hdr->daddr, iphc1);
>>> + if (dci) {
>>> + iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, &hdr->daddr,
>>> + &dci_entry, daddr,
>>> + false);
>>> + iphc1 |= LOWPAN_IPHC_DAC;
>>> } else {
>>> - pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
>>> - lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
>>> + if (ipv6_daddr_type & IPV6_ADDR_LINKLOCAL) {
>>> + iphc1 |= lowpan_compress_addr_64(&hc_ptr,
>>> + &hdr->daddr,
>>> + daddr, false);
>>> + 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);
>>> + }
>>> }
>>> }
>>> @@ -871,3 +1096,143 @@ int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
>>> return 0;
>>> }
>>> EXPORT_SYMBOL_GPL(lowpan_header_compress);
>>> +
>>> +static bool lowpan_iphc_ctx_valid_prefix(const struct lowpan_iphc_ctx *ctx)
>>> +{
>>> + /* prefix which are smaller than 64 bits are not valid, users
>>> + * may mean than a prefix which is filled with zero until 64th bit.
>>> + * Refere rfc6282 "Any remaining bits are zero." The remaining bits
>>> + * in this case where are the prefix(< 64) ends until IID starts.
>>> + */
>>> + if (ctx->prefix_len < 64)
>>> + return false;
>>> +
>>> + return true;
>>> +}
>>> +
> I will remove this check, the prefix_len should be any length, from 0
> until 128. We need to care about the zero bits if prefix_len < 64 during
> lookup.
>
> I think a "valid" test would be to check on multicast address scope
> which should not a valid prefix for dci/sci table. There might be more
> addresses which should not valid here. At the moment I would say a
> multicast address should be invalid. I will add this as well.
>
>>> +static bool
>>> +lowpan_iphc_mcast_ctx_valid_prefix(const struct lowpan_iphc_ctx *ctx)
>>> +{
>>> + /* network prefix for multicast is at maximum 64 bits long */
>>> + if (ctx->prefix_len > 64)
>>> + return false;
>>> +
>>> + return true;
>>> +}
>>> +
>>> +static int lowpan_iphc_ctx_update(struct lowpan_iphc_ctx *table,
>>> + const struct lowpan_iphc_ctx *ctx)
>>> +{
>>> + int ret = 0, i;
>>> +
>>> + if (ctx->enabled) {
>>> + for (i = 0; i < LOWPAN_IPHC_CI_TABLE_SIZE; i++) {
>>> + if (ctx->prefix_len != table[i].prefix_len)
>>> + continue;
>>> +
>>> + if (ipv6_prefix_equal(&ctx->addr, &table[i].addr,
>>> + ctx->prefix_len)) {
>>> + if (table[i].enabled) {
>>> + ret = -EEXIST;
>>> + goto out;
>>> + }
>>> + }
>>> + }
>>> + }
>>> +
>>> + memcpy(&table[ctx->id], ctx, sizeof(*ctx));
>>> +
>>> +out:
>>> + return ret;
>>> +}
>>> +
>> In what cases should the update succeed? I'm wondering about some corner
>> cases here:
>>
>> o If the new ctx is disabled it would update the table on its cid no matter
>> what.
>> o If the new ctx is enabled we would update it only if we do not find the
>> same prefix in an enabled state already.
>>
>> To put it differently, the only case we do not update the table with the
>> context is if it already exists and is enabled. This is how you want it?
>>
> yes. If we don't check if it's enabled (inside the table), then we could
> not simple copy one line (by doing cat and echo) with a context which
> is disabled, then simple replace the disabled(0) to enabled(1). Then it
> would fail because the same prefix is already there, but when it's
> disabled then we ignore if the prefix is already exists. It will not
> used then anyway.
ok
regards
Stefan Schmidt
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