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+#ifndef included_vnet_sr_packet_h
+#define included_vnet_sr_packet_h
+
+#include <vnet/ip/ip.h>
+
+/*
+ * ipv6 segment-routing header format
+ *
+ * Copyright (c) 2013 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.
+ */
+
+/**
+ * @file
+ * @brief The Segment Routing Header (SRH).
+ *
+ * The Segment Routing Header (SRH) is defined in the diagram below.
+ *
+ *
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Next Header | Hdr Ext Len | Routing Type | Segments Left |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | First Segment | Flags | HMAC Key ID |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | Segment List[0] (128 bits ipv6 address) |
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | |
+ * ...
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | Segment List[n] (128 bits ipv6 address) |
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | Policy List[0] (optional) |
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | Policy List[1] (optional) |
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | Policy List[2] (optional) |
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * | |
+ * | |
+ * | HMAC (256 bits) |
+ * | (optional) |
+ * | |
+ * | |
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * where:
+ *
+ * o Next Header: 8-bit selector. Identifies the type of header
+ * immediately following the SRH.
+ *
+ * o Hdr Ext Len: 8-bit unsigned integer, is the length of the SRH
+ * header in 8-octet units, not including the first 8 octets.
+ *
+ * o Routing Type: TBD, to be assigned by IANA (suggested value: 4).
+ *
+ * o Segments Left. Defined in [RFC2460], it contains the index, in
+ * the Segment List, of the next segment to inspect. Segments Left
+ * is decremented at each segment and it is used as an index in the
+ * segment list.
+ *
+ * o First Segment: offset in the SRH, not including the first 8 octets
+ * and expressed in 16-octet units, pointing to the last element of
+ * the segment list, which is in fact the first segment of the
+ * segment routing path.
+ *
+ * o Flags: 16 bits of flags. Following flags are defined:
+ *
+ * 1
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |C|P|R|R| Policy Flags |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * C-flag: Clean-up flag. Set when the SRH has to be removed from
+ * the packet when packet reaches the last segment.
+ *
+ * P-flag: Protected flag. Set when the packet has been rerouted
+ * through FRR mechanism by a SR endpoint node. See Section 6.3
+ * for more details.
+ *
+ * R-flags. Reserved and for future use.
+ *
+ * Policy Flags. Define the type of the IPv6 addresses encoded
+ * into the Policy List (see below). The following have been
+ * defined:
+ *
+ * Bits 4-6: determine the type of the first element after the
+ * segment list.
+ *
+ * Bits 7-9: determine the type of the second element.
+ *
+ * Bits 10-12: determine the type of the third element.
+ *
+ * Bits 13-15: determine the type of the fourth element.
+ *
+ * The following values are used for the type:
+ *
+ * 0x0: Not present. If value is set to 0x0, it means the
+ * element represented by these bits is not present.
+ *
+ * 0x1: SR Ingress.
+ *
+ * 0x2: SR Egress.
+ *
+ * 0x3: Original Source Address.
+ *
+ * o HMAC Key ID and HMAC field, and their use are defined in
+ * [I-D.vyncke-6man-segment-routing-security].
+ *
+ * o Segment List[n]: 128 bit IPv6 addresses representing the nth
+ * segment in the Segment List. The Segment List is encoded starting
+ * from the last segment of the path. I.e., the first element of the
+ * segment list (Segment List [0]) contains the last segment of the
+ * path while the last segment of the Segment List (Segment List[n])
+ * contains the first segment of the path. The index contained in
+ * "Segments Left" identifies the current active segment.
+ *
+ * o Policy List. Optional addresses representing specific nodes in
+ * the SR path such as:
+ *
+ * SR Ingress: a 128 bit generic identifier representing the
+ * ingress in the SR domain (i.e.: it needs not to be a valid IPv6
+ * address).
+ *
+ * SR Egress: a 128 bit generic identifier representing the egress
+ * in the SR domain (i.e.: it needs not to be a valid IPv6
+ * address).
+ *
+ * Original Source Address: IPv6 address originally present in the
+ * SA field of the packet.
+ *
+ * The segments in the Policy List are encoded after the segment list
+ * and they are optional. If none are in the SRH, all bits of the
+ * Policy List Flags MUST be set to 0x0.
+ */
+
+#ifndef IPPROTO_IPV6_ROUTE
+#define IPPROTO_IPV6_ROUTE 43
+#endif
+
+#define ROUTING_HEADER_TYPE_SR 4
+/**
+ @brief SR header struct.
+*/
+typedef struct
+{
+ /** Protocol for next header. */
+ u8 protocol;
+
+ /**
+ * Length of routing header in 8 octet units,
+ * not including the first 8 octets
+ */
+ u8 length;
+
+ /** Type of routing header; type 4 = segement routing */
+ u8 type;
+
+ /** Next segment in the segment list */
+ u8 segments_left;
+
+ /**
+ * Policy list pointer: offset in the SRH of the policy
+ * list - in 16-octet units - not including the first 8 octets.
+ */
+ u8 first_segment;
+
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_CLEANUP (0x8000)
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_PROTECTED (0x4000)
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_RESERVED (0x3000)
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_PL_ELT_NOT_PRESENT (0x0)
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_PL_ELT_INGRESS_PE (0x1)
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_PL_ELT_EGRESS_PE (0x2)
+ /** Flag bits */
+#define IP6_SR_HEADER_FLAG_PL_ELT_ORIG_SRC_ADDR (0x3)
+ /** values 0x4 - 0x7 are reserved */
+ u16 flags;
+ u8 hmac_key;
+
+ /** The segment + policy list elts */
+ ip6_address_t segments[0];
+} __attribute__ ((packed)) ip6_sr_header_t;
+
+static inline int
+ip6_sr_policy_list_shift_from_index (int pl_index)
+{
+ return (-3 * pl_index) + 12;
+}
+
+/** pl_index is one-origined */
+static inline int
+ip6_sr_policy_list_flags (u16 flags_host_byte_order, int pl_index)
+{
+ int shift;
+
+ if (pl_index <= 0 || pl_index > 4)
+ return 0;
+
+ shift = (-3 * pl_index) + 12;
+ flags_host_byte_order >>= shift;
+
+ return (flags_host_byte_order & 7);
+}
+
+#endif /* included_vnet_sr_packet_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */