batman-adv: Add function to calculate crc32c for the skb payload
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>
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index dc33a0c..f65a222 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -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 @@
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;