Signed-off-by: Sven Eckelmann sven@narfation.org --- main.c | 34 ++++++++++++++++++++++++++++++++++ main.h | 1 + 2 files changed, 35 insertions(+)

diff --git a/main.c b/main.c index 70797de..122c675 100644 --- a/main.c +++ b/main.c @@ -33,6 +33,7 @@ #include "vis.h" #include "hash.h" #include "bat_algo.h" +#include <linux/crc32c.h>

/* List manipulations on hardif_list have to be rtnl_lock()'ed, @@ -432,6 +433,39 @@ int batadv_compat_seq_print_text(struct seq_file *seq, void *offset) return 0; }

+/** + * batadv_crc32 - calculate CRC32 of the whole packet and skip bytes in 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 the point in the skb head buffer and not to + * a fragment. + */ +__be32 batadv_crc32(const struct sk_buff *skb, u8 *payload_ptr) +{ + u32 crc = 0; + struct sk_buff *iter; + size_t skip_len, read_len; + const skb_frag_t *f; + int i; + + skip_len = payload_ptr - skb->data; + read_len = skb_headlen(skb) - skip_len; + if (read_len) + crc = crc32c(crc, payload_ptr, read_len); + + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + f = &skb_shinfo(skb)->frags[i]; + crc = crc32c(crc, skb_frag_address(f), skb_frag_size(f)); + } + + skb_walk_frags(skb, iter) + crc = crc32c(crc, iter->data, skb_headlen(iter)); + + return htonl(crc); +} + static int batadv_param_set_ra(const char *val, const struct kernel_param *kp) { struct batadv_algo_ops *bat_algo_ops; diff --git a/main.h b/main.h index 2dfcf8c..bb0a710 100644 --- a/main.h +++ b/main.h @@ -177,6 +177,7 @@ 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); int batadv_compat_seq_print_text(struct seq_file *seq, void *offset); +__be32 batadv_crc32(const struct sk_buff *skb, u8 *payload_ptr);

/** * enum batadv_dbg_level - available log levels