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-rw-r--r--net/ethernet/eth.c27
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)
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
* @dev: receiving network device