vnet/vnet/nsh-gre/nsh_gre_packet.h

/*
 * 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 included_vnet_nsh_gre_packet_h
#define included_vnet_nsh_gre_packet_h

/*
 * NSH_GRE packet format from draft-quinn-sfc-nsh-03.txt
 *
 * NSH Base Header
 *  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
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |Ver|O|C|R|R|R|R|R|R|   Length  |    MD Type    | Next Protocol |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * 
 * 
 * Base Header Field Descriptions:
 * 
 * Version: The version field is used to ensure backward compatibility
 * going forward with future NSH updates.
 * 
 * O bit: Indicates that this packet is an operations and management
 * (OAM) packet.  SFF and SFs nodes MUST examine the payload and take
 * appropriate action (e.g. return status information).
 * 
 * OAM message specifics and handling details are outside the scope of
 * this document.
 * 
 * C bit: Indicates that a critical metadata TLV is present (see section
 * 7).  This bit acts as an indication for hardware implementers to
 * decide how to handle the presence of a critical TLV without
 * necessarily needing to parse all TLVs present.  The C bit MUST be set
 * to 1 if one or more critical TLVs are present.
 * 
 * All other flag fields are reserved.
 * 
 * Length: total length, in 4 byte words, of the NSH header, including
 * optional variable TLVs.  Length must be equal or greater than 6.
 * 
 * MD Type: indicates the format of NSH beyond the base header and the
 * type of metadata being carried.  This typing is used to describe the
 * use for the metadata.  A new registry will be requested from IANA for
 * the MD Type.  NSH defines one type, type = 0x1 which indicates that
 * the format of the header is as per this draft.
 * 
 * The format of the base header is invariant, and not described by MD
 * Type.
 * 
 * Next Protocol: indicates the protocol type of the original packet.  A
 * new IANA registry will be created for protocol type.
 * 
 * This draft defines the following Next Protocol values:
 * 
 * 0x1 : IPv4
 * 0x2 : IPv6
 * 0x3 : Ethernet
 */

typedef CLIB_PACKED(struct {
  u8 ver_o_c;
  u8 length;
  u8 md_type;
  u8 next_protocol;
  u32 spi_si;
  /* Context headers, always present */
  u32 c1; u32 c2; u32 c3; u32 c4;

  /* Optional variable length metadata */
  u32 tlvs[0];
}) nsh_header_t;

#define NSH_GRE_VERSION (0<<6)
#define NSH_GRE_O_BIT (1<<5)
#define NSH_GRE_C_BIT (1<<4)

/* Network byte order shift / mask */
#define NSH_GRE_SINDEX_MASK 0xFF
#define NSH_GRE_SPI_MASK (0x00FFFFFF)
#define NSH_GRE_SPI_SHIFT 8

#endif /* included_vnet_nsh_gre_packet_h */