path: root/net/ethernet
diff options
authorAlexander Duyck <alexander.h.duyck@intel.com>2014-09-05 19:20:26 -0400
committerDavid S. Miller <davem@davemloft.net>2014-09-05 17:47:02 -0700
commit56193d1bce2b2759cb4bdcc00cd05544894a0c90 (patch)
tree621b2ce35961049dd263c2f83aee3d9ec39ac686 /net/ethernet
parent2c048e646212f9880e6f201771a30daa963d7f8b (diff)
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 <alexander.h.duyck@intel.com> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ethernet')
1 files changed, 27 insertions, 0 deletions
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
@@ -146,6 +146,33 @@ int eth_rebuild_header(struct sk_buff *skb)
+ * 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);
* eth_type_trans - determine the packet's protocol ID.
* @skb: received socket data
* @dev: receiving network device

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