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batman-adv: Add function to calculate crc32c for the skb payload

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Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
This commit is contained in:
Sven Eckelmann 2012-10-17 21:10:39 +02:00 committed by Antonio Quartulli
parent 60d8cce7c5
commit 95a066d82c
3 changed files with 36 additions and 0 deletions
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1
net/batman-adv/Kconfig
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@ -6,6 +6,7 @@ config BATMAN_ADV
tristate "B.A.T.M.A.N. Advanced Meshing Protocol"
depends on NET
select CRC16
select LIBCRC32C
default n
help
B.A.T.M.A.N. (better approach to mobile ad-hoc networking) is

34
net/batman-adv/main.c
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@ -17,6 +17,8 @@
* 02110-1301, USA
*/
#include <linux/crc32c.h>
#include <linux/highmem.h>
#include "main.h"
#include "sysfs.h"
#include "debugfs.h"
@ -420,6 +422,38 @@ int batadv_algo_seq_print_text(struct seq_file *seq, void *offset)
return 0;
}
/**
* batadv_skb_crc32 - calculate CRC32 of the whole packet and skip bytes in
* the header
* @skb: skb pointing to fragmented socket buffers
* @payload_ptr: Pointer to position inside the head buffer of the skb
* marking the start of the data to be CRC'ed
*
* payload_ptr must always point to an address in the skb head buffer and not to
* a fragment.
*/
__be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr)
{
u32 crc = 0;
unsigned int from;
unsigned int to = skb->len;
struct skb_seq_state st;
const u8 *data;
unsigned int len;
unsigned int consumed = 0;
from = (unsigned int)(payload_ptr - skb->data);
skb_prepare_seq_read(skb, from, to, &st);
while ((len = skb_seq_read(consumed, &data, &st)) != 0) {
crc = crc32c(crc, data, len);
consumed += len;
}
skb_abort_seq_read(&st);
return htonl(crc);
}
static int batadv_param_set_ra(const char *val, const struct kernel_param *kp)
{
struct batadv_algo_ops *bat_algo_ops;

1
net/batman-adv/main.h
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@ -174,6 +174,7 @@ void batadv_recv_handler_unregister(uint8_t packet_type);
int batadv_algo_register(struct batadv_algo_ops *bat_algo_ops);
int batadv_algo_select(struct batadv_priv *bat_priv, char *name);
int batadv_algo_seq_print_text(struct seq_file *seq, void *offset);
__be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr);
/**
* enum batadv_dbg_level - available log levels