gre: Move utility functions to common headers

[cascardo/linux.git] / net / ipv4 / gre_demux.c

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index d9c552a..3716748 100644 (file)
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -60,6 +60,70 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version)
 }
 EXPORT_SYMBOL_GPL(gre_del_protocol);
 
+int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
+                    bool *csum_err, int *ret_hdr_len)
+{
+       const struct gre_base_hdr *greh;
+       __be32 *options;
+       int hdr_len;
+
+       if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
+               return -EINVAL;
+
+       greh = (struct gre_base_hdr *)skb_transport_header(skb);
+       if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
+               return -EINVAL;
+
+       tpi->flags = gre_flags_to_tnl_flags(greh->flags);
+       hdr_len = gre_calc_hlen(tpi->flags);
+
+       if (!pskb_may_pull(skb, hdr_len))
+               return -EINVAL;
+
+       greh = (struct gre_base_hdr *)skb_transport_header(skb);
+       tpi->proto = greh->protocol;
+
+       options = (__be32 *)(greh + 1);
+       if (greh->flags & GRE_CSUM) {
+               if (skb_checksum_simple_validate(skb)) {
+                       *csum_err = true;
+                       return -EINVAL;
+               }
+
+               skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
+                                        null_compute_pseudo);
+               options++;
+       }
+
+       if (greh->flags & GRE_KEY) {
+               tpi->key = *options;
+               options++;
+       } else {
+               tpi->key = 0;
+       }
+       if (unlikely(greh->flags & GRE_SEQ)) {
+               tpi->seq = *options;
+               options++;
+       } else {
+               tpi->seq = 0;
+       }
+       /* WCCP version 1 and 2 protocol decoding.
+        * - Change protocol to IP
+        * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
+        */
+       if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
+               tpi->proto = htons(ETH_P_IP);
+               if ((*(u8 *)options & 0xF0) != 0x40) {
+                       hdr_len += 4;
+                       if (!pskb_may_pull(skb, hdr_len))
+                               return -EINVAL;
+               }
+       }
+       *ret_hdr_len = hdr_len;
+       return 0;
+}
+EXPORT_SYMBOL(gre_parse_header);
+
 static int gre_rcv(struct sk_buff *skb)
 {
        const struct gre_protocol *proto;