From 56193d1bce2b2759cb4bdcc00cd05544894a0c90 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Fri, 5 Sep 2014 19:20:26 -0400 Subject: net: Add function for parsing the header length out of linear ethernet frames This patch updates some of the flow_dissector api so that it can be used to parse the length of ethernet buffers stored in fragments. Most of the changes needed were to __skb_get_poff as it needed to be updated to support sending a linear buffer instead of a skb. I have split __skb_get_poff into two functions, the first is skb_get_poff and it retains the functionality of the original __skb_get_poff. The other function is __skb_get_poff which now works much like __skb_flow_dissect in relation to skb_flow_dissect in that it provides the same functionality but works with just a data buffer and hlen instead of needing an skb. Signed-off-by: Alexander Duyck Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- net/ethernet/eth.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'net/ethernet') diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index 5cebca134585..33a140e15834 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -145,6 +145,33 @@ int eth_rebuild_header(struct sk_buff *skb) } EXPORT_SYMBOL(eth_rebuild_header); +/** + * eth_get_headlen - determine the the length of header for an ethernet frame + * @data: pointer to start of frame + * @len: total length of frame + * + * Make a best effort attempt to pull the length for all of the headers for + * a given frame in a linear buffer. + */ +u32 eth_get_headlen(void *data, unsigned int len) +{ + const struct ethhdr *eth = (const struct ethhdr *)data; + struct flow_keys keys; + + /* this should never happen, but better safe than sorry */ + if (len < sizeof(*eth)) + return len; + + /* parse any remaining L2/L3 headers, check for L4 */ + if (!__skb_flow_dissect(NULL, &keys, data, + eth->h_proto, sizeof(*eth), len)) + return max_t(u32, keys.thoff, sizeof(*eth)); + + /* parse for any L4 headers */ + return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len); +} +EXPORT_SYMBOL(eth_get_headlen); + /** * eth_type_trans - determine the packet's protocol ID. * @skb: received socket data -- cgit v1.2.3-59-g8ed1b