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+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __MPLS_LOOKUP_H__
+#define __MPLS_LOOKUP_H__
+
+#include <vnet/mpls/mpls.h>
+#include <vnet/ip/ip.h>
+
+/**
+ * The arc/edge from the MPLS lookup node to the MPLS replicate node
+ */
+u32 mpls_lookup_to_replicate_edge;
+
+/*
+ * Compute flow hash.
+ * We'll use it to select which adjacency to use for this flow. And other things.
+ */
+always_inline u32
+mpls_compute_flow_hash (const mpls_unicast_header_t * hdr,
+ flow_hash_config_t flow_hash_config)
+{
+ /*
+ * We need to byte swap so we use the numerical value. i.e. an odd label
+ * leads to an odd bucket. as opposed to a label above and below value X.
+ */
+ u8 next_label_is_entropy;
+ mpls_label_t ho_label;
+ u32 hash, value;
+
+ ho_label = clib_net_to_host_u32(hdr->label_exp_s_ttl);
+ hash = vnet_mpls_uc_get_label(ho_label);
+ next_label_is_entropy = 0;
+
+ while (MPLS_EOS != vnet_mpls_uc_get_s(ho_label))
+ {
+ hdr++;
+ ho_label = clib_net_to_host_u32(hdr->label_exp_s_ttl);
+ value = vnet_mpls_uc_get_label(ho_label);
+
+ if (1 == next_label_is_entropy)
+ {
+ /*
+ * The label is an entropy value, use it alone as the hash
+ */
+ return (ho_label);
+ }
+ if (MPLS_IETF_ENTROPY_LABEL == value)
+ {
+ /*
+ * we've met a label in the stack indicating that tha next
+ * label is an entropy value
+ */
+ next_label_is_entropy = 1;
+ }
+ else
+ {
+ /*
+ * XOR the label values in the stack together to
+ * build up the hash value
+ */
+ hash ^= value;
+ }
+ }
+
+ /*
+ * check the top nibble for v4 and v6
+ */
+ hdr++;
+
+ switch (((u8*)hdr)[0] >> 4)
+ {
+ case 4:
+ /* incorporate the v4 flow-hash */
+ hash ^= ip4_compute_flow_hash ((const ip4_header_t *)hdr,
+ IP_FLOW_HASH_DEFAULT);
+ break;
+ case 6:
+ /* incorporate the v6 flow-hash */
+ hash ^= ip6_compute_flow_hash ((const ip6_header_t *)hdr,
+ IP_FLOW_HASH_DEFAULT);
+ break;
+ default:
+ break;
+ }
+
+ return (hash);
+}
+
+#endif /* __MPLS_LOOKUP_H__ */