The patch adds stateful compression (context ids based compression) to
the 6lowpan module [RFC6282].
Stateful Compression users allocate context tables through the functions
in the context.c using public APIs declared in 6lowpan.h. The context.c
is extending the 6lowpan module and not created as a separate module.
A debugfs entry for maintaining the context tables is implemented
(/sys/kernel/debug/6lowpan/context).
Example usage of the 6lowpan debugfs interface:
echo "<CMD> <IFACE> <CID> <CID_PREFIX> <CID_PREFIX_LENGTH>
<COMPRESSION_ENABLE_FLAG>" > /sys/kernel/debug/6lowpan/context
Examples:
echo "add bt0 3 2001:db8:: 64 1" > /sys/kernel/debug/6lowpan/context
echo "remove bt0 3" > /sys/kernel/debug/6lowpan/context
cat /sys/kernel/debug/6lowpan/context
e.g.
Context table of interface bt0
CID Prefix Len CF
3 2001:db8:: 64 1
4 2001:db8::1 128 1
Signed-off-by: Lukasz Duda <lukasz.duda@xxxxxxxxxxxxx>
Signed-off-by: Glenn Ruben Bakke <glenn.ruben.bakke@xxxxxxxxxxxxx>
---
include/net/6lowpan.h | 35 ++++
net/6lowpan/Makefile | 2 +-
net/6lowpan/context.c | 551 ++++++++++++++++++++++++++++++++++++++++++++++++++
net/6lowpan/context.h | 7 +
4 files changed, 594 insertions(+), 1 deletion(-)
create mode 100644 net/6lowpan/context.c
create mode 100644 net/6lowpan/context.h
diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h
index 37ddbdf..ee3a455 100644
--- a/include/net/6lowpan.h
+++ b/include/net/6lowpan.h
@@ -199,6 +199,27 @@
extern struct dentry *lowpan_debugfs;
+struct lowpan_context_table {
+ struct list_head list;
+
+ /* Context entries */
+ struct net_device *netdev;
+ struct list_head context_entries;
+ atomic_t context_count;
+};
+
+struct lowpan_context_entry {
+ struct list_head list;
+ struct rcu_head rcu;
+ struct lowpan_context_table *ctx_table;
+
+ /* Context parameters */
+ u8 cid;
+ struct in6_addr prefix;
+ unsigned int prefix_len;
+ bool compression_flag;
+};
+
#ifdef DEBUG
/* print data in line */
static inline void raw_dump_inline(const char *caller, char *msg,
@@ -337,6 +358,9 @@ lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset)
if (!(iphc0 & 0x03))
ret++;
+ if (iphc1 & LOWPAN_IPHC_CID)
+ ret++;
+
ret += lowpan_addr_mode_size((iphc1 & LOWPAN_IPHC_SAM) >>
LOWPAN_IPHC_SAM_BIT);
@@ -374,6 +398,17 @@ lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset)
return skb->len + uncomp_header - ret;
}
+int lowpan_context_table_alloc(struct net_device *netdev);
+int lowpan_context_table_free(struct net_device *netdev);
+int lowpan_context_free_all(void);
+int lowpan_context_add(struct net_device *netdev,
+ struct lowpan_context_entry *entry);
+int lowpan_context_remove(struct lowpan_context_entry *entry);
+struct lowpan_context_entry *
+lowpan_context_decompress(struct net_device *netdev, u8 cid);
+struct lowpan_context_entry *
+lowpan_context_compress(struct net_device *netdev, struct in6_addr *addr);
+
int
lowpan_header_decompress(struct sk_buff *skb, struct net_device *dev,
const u8 *saddr, const u8 saddr_type,
diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile
index eb8baa7..bda5be0 100644
--- a/net/6lowpan/Makefile
+++ b/net/6lowpan/Makefile
@@ -1,6 +1,6 @@
obj-$(CONFIG_6LOWPAN) += 6lowpan.o
-6lowpan-y := iphc.o nhc.o
+6lowpan-y := iphc.o nhc.o context.o
#rfc6282 nhcs
obj-$(CONFIG_6LOWPAN_NHC_DEST) += nhc_dest.o
diff --git a/net/6lowpan/context.c b/net/6lowpan/context.c
new file mode 100644
index 0000000..00cd5af
--- /dev/null
+++ b/net/6lowpan/context.c
@@ -0,0 +1,551 @@
+/*
+ * Copyright (c) 2015 Nordic Semiconductor. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only 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.
+ */
+
+#include <linux/if_arp.h>
+#include <linux/netdevice.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/inet.h>
+#include <linux/atomic.h>
+
+#include <net/ipv6.h>
+#include <net/addrconf.h>
+#include <net/6lowpan.h>
+
+#define LOWPAN_DBG(fmt, ...) pr_debug(fmt "\n", ##__VA_ARGS__)
+
+#define LOWPAN_CONTEXT_TABLE_SIZE 16
+#define LOWPAN_CONTEXT_COMMAND_ADD "add"
+#define LOWPAN_CONTEXT_COMMAND_REMOVE "remove"
+
+#define CHECK_CID_RANGE(cid) ((cid) > 0 && (cid) < LOWPAN_CONTEXT_TABLE_SIZE)
+#define CHECK_PREFIX_RANGE(len) ((len) > 0 && (len) <= 128)
+
+static struct dentry *lowpan_context_debugfs;
+
+static LIST_HEAD(context_tables);
+static DEFINE_SPINLOCK(module_lock);
+
+static inline void entry_update(struct lowpan_context_entry *entry,
+ u8 cid,
+ struct in6_addr prefix,
+ unsigned int prefix_len,
+ bool compression_flag)
+{
+ /* Fill context entry. */
+ entry->cid = cid;
+ entry->compression_flag = compression_flag;
+ entry->prefix = prefix;
+ entry->prefix_len = prefix_len;
+}
+
+static inline void entry_free(struct lowpan_context_entry *entry)
+{
+ /* Increase number of available contexts. */
+ atomic_dec(&entry->ctx_table->context_count);
+
+ list_del_rcu(&entry->list);
+ kfree_rcu(entry, rcu);
+}
+
+static int entry_add(struct lowpan_context_table *ctx_table,
+ u8 cid,
+ struct in6_addr prefix,
+ unsigned int prefix_len,
+ bool compression_flag)
+{
+ struct lowpan_context_entry *new_entry = NULL;
+
+ new_entry = kzalloc(sizeof(*new_entry), GFP_ATOMIC);
+ if (!new_entry)
+ return -ENOMEM;
+
+ /* Fill context entry. */
+ new_entry->ctx_table = ctx_table;
+ entry_update(new_entry, cid, prefix, prefix_len, compression_flag);
+
+ INIT_LIST_HEAD(&new_entry->list);
+ list_add_rcu(&new_entry->list, &ctx_table->context_entries);
+
+ /* Increase number of available contexts. */
+ atomic_inc(&ctx_table->context_count);
+
+ return 0;
+}
+
+static void table_free(struct lowpan_context_table *ctx_table)
+{
+ struct lowpan_context_entry *entry = NULL;
+
+ rcu_read_lock();
+
+ /* Clear context table. */
+ if (atomic_read(&ctx_table->context_count)) {
+ list_for_each_entry_rcu(entry,
+ &ctx_table->context_entries,
+ list)
+ entry_free(entry);
+ }
+
+ rcu_read_unlock();
+
+ /* Remove context table. */
+ list_del(&ctx_table->list);
+ kfree(ctx_table);
+}
+
+static inline struct net_device *find_netdev(const char *name)
+{
+ struct net_device *netdev;
+
+ rcu_read_lock();
+ netdev = dev_get_by_name_rcu(&init_net, name);
+ rcu_read_unlock();
+
+ return netdev;
+}
+
+static struct lowpan_context_table *get_table(struct net_device *netdev)
+{
+ struct lowpan_context_table *entry;
+ struct lowpan_context_table *net_table = NULL;
+
+ spin_lock(&module_lock);
+
+ list_for_each_entry(entry, &context_tables, list) {
+ if (entry->netdev == netdev) {
+ /* Table has been found. */
+ net_table = entry;
+ break;
+ }
+ }
+
+ spin_unlock(&module_lock);
+
+ return net_table;
+}
+
+static struct lowpan_context_entry *
+get_ctx_by_cid(struct lowpan_context_table *table, u8 cid)
+{
+ struct lowpan_context_entry *entry;
+ struct lowpan_context_entry *context = NULL;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(entry, &table->context_entries, list) {
+ if (entry->cid == cid) {
+ /* Context entry has been found. */
+ context = entry;
+ break;
+ }
+ }
+
+ rcu_read_unlock();
+
+ return context;
+}
+
+static struct lowpan_context_entry *
+get_ctx_by_addr(struct lowpan_context_table *table, struct in6_addr *addr)
+{
+ struct lowpan_context_entry *entry;
+ struct lowpan_context_entry *best_match = NULL;
+ unsigned int compare_len;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(entry, &table->context_entries, list) {
+ if (!entry->compression_flag)
+ continue;
+
+ compare_len = entry->prefix_len >= 64 ? entry->prefix_len : 64;
+ if (ipv6_prefix_equal(addr, &entry->prefix, compare_len)) {
+ /* Valid context entry has been found. Check if prefix
+ * can cover more bytes than previous one.
+ */
+ if (!best_match ||
+ (best_match->prefix_len < entry->prefix_len))
+ best_match = entry;
+ }
+ }
+
+ rcu_read_unlock();
+
+ return best_match;
+}
+
+ssize_t lowpan_context_dbgfs_write(struct file *fp,
+ const char __user *user_buffer,
+ size_t count,
+ loff_t *position)
+{
+ char buf[128];
+ char str_operation[16];
+ char str_interface[16];
+ char str_ipv6addr[40];
+ size_t buf_size = min(count, sizeof(buf) - 1);
+ int n;
+ int ret;
+ u8 cid;
+ unsigned int prefix_length;
+ unsigned int c_flag;
+ struct in6_addr ctx_prefix;
+ struct net_device *netdev;
+ struct lowpan_context_table *ctx_table;
+ struct lowpan_context_entry *entry;
+
+ memset(&ctx_prefix, 0, sizeof(ctx_prefix));
+
+ if (copy_from_user(buf, user_buffer, buf_size))
+ return -EFAULT;
+
+ buf[buf_size] = '\0';
+
+ /* Parse input parameters. */
+ n = sscanf(buf, "%s %s %hhd %s %d %d",
+ str_operation, str_interface, &cid, str_ipv6addr,
+ &prefix_length, &c_flag);
+
+ netdev = find_netdev(str_interface);
+ /* Look up for net device. */
+ if (!netdev) {
+ LOWPAN_DBG("Cannot find given interface");
+ return -EINVAL;
+ }
+
+ if (!CHECK_CID_RANGE(cid)) {
+ LOWPAN_DBG("CID value is out of range");
+ return -EINVAL;
+ }
+
+ /* Get context table. */
+ ctx_table = get_table(netdev);
+
+ if (!ctx_table) {
+ LOWPAN_DBG("Cannot find context table for %s interface",
+ str_interface);
+ return -EINVAL;
+ }
+
+ entry = get_ctx_by_cid(ctx_table, cid);
+
+ /* Execute command. */
+ if (!memcmp(str_operation, LOWPAN_CONTEXT_COMMAND_ADD,
+ sizeof(LOWPAN_CONTEXT_COMMAND_ADD))) {
+ /* Parse IPv6 address. */
+ in6_pton(str_ipv6addr,
+ sizeof(str_ipv6addr),
+ ctx_prefix.s6_addr,
+ '\0',
+ NULL);
+
+ /* Check parameters. */
+ if (ipv6_addr_any(&ctx_prefix) ||
+ !CHECK_PREFIX_RANGE(prefix_length)) {
+ LOWPAN_DBG("Given parameters are not valid");
+ return -EINVAL;
+ }
+
+ LOWPAN_DBG("Got request: I:%s CID:%d Prefix:%pI6c/%d C:%d",
+ str_interface, cid, &ctx_prefix, prefix_length,
+ !!c_flag);
+
+ /* Check if entry for given CID already exists. */
+ if (entry) {
+ /* Just update parameters. */
+ rcu_read_lock();
+ entry_update(entry, cid, ctx_prefix, prefix_length,
+ !!c_flag);
+ rcu_read_unlock();
+ } else {
+ /* Create a new entry. */
+ ret = entry_add(ctx_table, cid, ctx_prefix,
+ prefix_length, !!c_flag);
+ if (ret < 0) {
+ LOWPAN_DBG("Cannot add context entry");
+ return ret;
+ }
+ }
+ } else if (memcmp(str_operation, LOWPAN_CONTEXT_COMMAND_REMOVE,
+ sizeof(LOWPAN_CONTEXT_COMMAND_REMOVE)) == 0) {
+ LOWPAN_DBG("Got new remove request: I:%s CID:%d",
+ str_interface, cid);
+
+ if (!entry) {
+ LOWPAN_DBG("Cannot find context entry");
+ return -EINVAL;
+ }
+
+ rcu_read_lock();
+ entry_free(entry);
+ rcu_read_unlock();
+ } else {
+ LOWPAN_DBG("Invalid command - Cannot process the request");
+ return -EINVAL;
+ }
+
+ return count;
+}
+
+static int lowpan_context_show(struct seq_file *f, void *ptr)
+{
+ struct lowpan_context_table *table;
+ struct lowpan_context_entry *entry;
+
+ list_for_each_entry(table, &context_tables, list) {
+ if (!atomic_read(&table->context_count))
+ break;
+
+ seq_printf(f, "Context table of interface %s\r\n\r\n",
+ table->netdev->name);
+ seq_printf(f, "%-3s %-39s %-3s %-3s \r\n",
+ "CID", "Prefix", "Len", "CF");
+
+ list_for_each_entry_rcu(entry, &table->context_entries, list)
+ seq_printf(f, "%-3d %-39pI6c %-3d %-3s \r\n",
+ entry->cid,
+ &entry->prefix,
+ entry->prefix_len,
+ entry->compression_flag ? "1" : "0");
+ seq_puts(f, "\r\n\r\n");
+ }
+
+ return 0;
+}
+
+int lowpan_context_dbgfs_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, lowpan_context_show, inode->i_private);
+}
+
+int lowpan_context_table_alloc(struct net_device *netdev)
+{
+ struct lowpan_context_table *ctx_table = NULL;
+
+ if (!netdev) {
+ LOWPAN_DBG("Network device has to be specified");
+ return -EPERM;
+ }
+
+ /* Look for context table. */
+ ctx_table = get_table(netdev);
+
+ if (ctx_table) {
+ LOWPAN_DBG("Context table already exists for interface %s %p",
+ netdev->name, ctx_table);
+ return -EEXIST;
+ }
+
+ ctx_table = kzalloc(sizeof(*ctx_table), GFP_ATOMIC);
+ if (!ctx_table)
+ return -ENOMEM;
+
+ /* Assign network device to context table. */
+ ctx_table->netdev = netdev;
+
+ /* Initialize contexts list. */
+ INIT_LIST_HEAD(&ctx_table->context_entries);
+
+ spin_lock(&module_lock);
+ INIT_LIST_HEAD(&ctx_table->list);
+ list_add_rcu(&ctx_table->list, &context_tables);
+ spin_unlock(&module_lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lowpan_context_table_alloc);
+
+int lowpan_context_table_free(struct net_device *netdev)
+{
+ struct lowpan_context_table *ctx_table = NULL;
+
+ if (!netdev) {
+ LOWPAN_DBG("Network device has to be specified");
+ return -EPERM;
+ }
+
+ /* Look for context table. */
+ ctx_table = get_table(netdev);
+ if (!ctx_table) {
+ LOWPAN_DBG("Cannot find context table for interface %s",
+ netdev->name);
+ return -ENOENT;
+ }
+
+ spin_lock(&module_lock);
+ table_free(ctx_table);
+ spin_unlock(&module_lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lowpan_context_table_free);
+
+int lowpan_context_add(struct net_device *netdev,
+ struct lowpan_context_entry *entry)
+{
+ int ret;
+ struct lowpan_context_table *ctx_table = NULL;
+ struct lowpan_context_entry *stored_entry = NULL;
+
+ if (!entry || !netdev) {
+ LOWPAN_DBG("Parameters are incorrect");
+ return -EPERM;
+ }
+
+ /* Get context table. */
+ ctx_table = get_table(netdev);
+ if (!ctx_table) {
+ LOWPAN_DBG("Cannot find context table for %s interface",
+ netdev->name);
+ return -EINVAL;
+ }
+
+ stored_entry = get_ctx_by_cid(ctx_table, entry->cid);
+
+ /* Check if entry for given CID already exists. */
+ if (entry) {
+ /* Just update parameters. */
+ rcu_read_lock();
+ entry_update(stored_entry, entry->cid, entry->prefix,
+ entry->prefix_len, entry->compression_flag);
+ rcu_read_unlock();
+ } else {
+ /* Create a new entry. */
+ ret = entry_add(ctx_table, entry->cid, entry->prefix,
+ entry->prefix_len, entry->compression_flag);
+
+ if (ret < 0) {
+ LOWPAN_DBG("Cannot add context entry");
+ return ret;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lowpan_context_add);
+
+int lowpan_context_remove(struct lowpan_context_entry *entry)
+{
+ if (!entry) {
+ LOWPAN_DBG("Given entry is NULL");
+ return -EPERM;
+ }
+
+ /* Free given entry. */
+ rcu_read_lock();
+ entry_free(entry);
+ rcu_read_unlock();
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lowpan_context_remove);
+
+struct lowpan_context_entry *
+lowpan_context_decompress(struct net_device *netdev, u8 cid)
+{
+ struct lowpan_context_table *ctx_table = NULL;
+ struct lowpan_context_entry *entry = NULL;
+
+ if (!netdev) {
+ LOWPAN_DBG("Network device has to be specified");
+ return NULL;
+ }
+
+ /* Get proper interface table. */
+ ctx_table = get_table(netdev);
+ if (!ctx_table) {
+ LOWPAN_DBG("Cannot find context table for interface %s",
+ netdev->name);
+ return NULL;
+ }
+
+ /* Search for given CID. */
+ entry = get_ctx_by_cid(ctx_table, cid);
+ if (!entry) {
+ LOWPAN_DBG("There is no context of id:%d for interface %s",
+ cid, netdev->name);
+ return NULL;
+ }
+
+ LOWPAN_DBG("Found context prefix for context of id:%d - %pI6c",
+ entry->cid, &entry->prefix);
+
+ return entry;
+}
+EXPORT_SYMBOL_GPL(lowpan_context_decompress);
+
+struct lowpan_context_entry *lowpan_context_compress(struct net_device *netdev,
+ struct in6_addr *addr)
+{
+ struct lowpan_context_table *ctx_table = NULL;
+ struct lowpan_context_entry *entry = NULL;
+
+ if (!netdev || !addr) {
+ LOWPAN_DBG("Network device and address has to be specified");
+ return NULL;
+ }
+
+ /* Get proper interface table. */
+ ctx_table = get_table(netdev);
+ if (!ctx_table) {
+ LOWPAN_DBG("Cannot find context table for interface %s",
+ netdev->name);
+ return NULL;
+ }
+
+ /* Search for given address. */
+ entry = get_ctx_by_addr(ctx_table, addr);
+ if (!entry) {
+ LOWPAN_DBG("No context for address %pI6c for interface %s",
+ addr, netdev->name);
+ return NULL;
+ }
+
+ LOWPAN_DBG("Found context of id:%d", entry->cid);
+
+ /* Return null in case no compression capability in found context */
+ return entry;
+}
+EXPORT_SYMBOL_GPL(lowpan_context_compress);
+
+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
+};
+
+void lowpan_context_init(void)
+{
+ lowpan_context_debugfs = debugfs_create_file("context", 0664,
+ lowpan_debugfs, NULL,
+ &lowpan_context_fops);
+}
+EXPORT_SYMBOL_GPL(lowpan_context_init);
+
+void lowpan_context_uninit(void)
+{
+ struct lowpan_context_table *entry = NULL;
+
+ spin_lock(&module_lock);
+
+ list_for_each_entry(entry, &context_tables, list)
+ table_free(entry);
+
+ spin_unlock(&module_lock);
+
+ debugfs_remove(lowpan_context_debugfs);
+}
+EXPORT_SYMBOL_GPL(lowpan_context_uninit);
diff --git a/net/6lowpan/context.h b/net/6lowpan/context.h
new file mode 100644
index 0000000..88303b5
--- /dev/null
+++ b/net/6lowpan/context.h
@@ -0,0 +1,7 @@
+#ifndef __6LOWPAN_CONTEXT_H
+#define __6LOWPAN_CONTEXT_H
+
+void lowpan_context_init(void);
+void lowpan_context_uninit(void);
+
+#endif /* __6LOWPAN_CONTEXT_H */
--
2.1.4
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