src/vnet/ip/ip6_packet.h - fdio/vpp - Gitiles

 /*
  * 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.
  */
 /*
  * ip6/packet.h: ip6 packet format
  *
  * Copyright (c) 2008 Eliot Dresselhaus
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
  *
  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */

 #ifndef included_ip6_packet_h
 #define included_ip6_packet_h

 #include <vnet/tcp/tcp_packet.h>
 #include <vnet/ip/ip4_packet.h>
 #include <stdbool.h>

 typedef union
 {
   u8 as_u8[16];
   u16 as_u16[8];
   u32 as_u32[4];
   u64 as_u64[2];
   u64x2 as_u128;
   uword as_uword[16 / sizeof (uword)];
 }
 __clib_packed ip6_address_t;

 STATIC_ASSERT_SIZEOF (ip6_address_t, 16);

 typedef struct
 {
   ip6_address_t addr, mask;
 } ip6_address_and_mask_t;

 /* Packed so that the mhash key doesn't include uninitialized pad bytes */
 typedef CLIB_PACKED (struct {
   /* IP address must be first for ip_interface_address_get_address() to work */
   ip6_address_t ip6_addr;
   u32 fib_index;
 }) ip6_address_fib_t;

 always_inline void
 ip6_addr_fib_init (ip6_address_fib_t * addr_fib,
 		   const ip6_address_t * address, u32 fib_index)
 {
   addr_fib->ip6_addr = *address;
   addr_fib->fib_index = fib_index;
 }

 /* Special addresses:
    unspecified		::/128
    loopback		::1/128
    global unicast       2000::/3
    unique local unicast fc00::/7
    link local unicast	fe80::/10
    multicast		ff00::/8
    ietf reserved	everything else. */

 #define foreach_ip6_multicast_address_scope	\
   _ (loopback, 0x1)				\
   _ (link_local, 0x2)				\
   _ (admin_local, 0x4)				\
   _ (site_local, 0x5)				\
   _ (organization_local, 0x8)			\
   _ (global, 0xe)

 #define foreach_ip6_multicast_link_local_group_id	\
   _ (all_hosts, 0x1)					\
   _ (all_routers, 0x2)					\
   _ (rip_routers, 0x9)					\
   _ (eigrp_routers, 0xa)				\
   _ (pim_routers, 0xd)                            \
  _ (mldv2_routers, 0x16)

 typedef enum
 {
 #define _(f,n) IP6_MULTICAST_SCOPE_##f = n,
   foreach_ip6_multicast_address_scope
 #undef _
 } ip6_multicast_address_scope_t;

 typedef enum
 {
 #define _(f,n) IP6_MULTICAST_GROUP_ID_##f = n,
   foreach_ip6_multicast_link_local_group_id
 #undef _
 } ip6_multicast_link_local_group_id_t;

 always_inline uword
 ip6_address_is_multicast (const ip6_address_t * a)
 {
   return a->as_u8[0] == 0xff;
 }

 always_inline void
 ip6_address_copy (ip6_address_t * dst, const ip6_address_t * src)
 {
   dst->as_u64[0] = src->as_u64[0];
   dst->as_u64[1] = src->as_u64[1];
 }

 always_inline void
 ip6_set_reserved_multicast_address (ip6_address_t * a,
 				    ip6_multicast_address_scope_t scope,
 				    u16 id)
 {
   a->as_u64[0] = a->as_u64[1] = 0;
   a->as_u16[0] = clib_host_to_net_u16 (0xff00 | scope);
   a->as_u16[7] = clib_host_to_net_u16 (id);
 }

 always_inline void
 ip6_set_solicited_node_multicast_address (ip6_address_t * a, u32 id)
 {
   /* 0xff02::1:ffXX:XXXX. */
   a->as_u64[0] = a->as_u64[1] = 0;
   a->as_u16[0] = clib_host_to_net_u16 (0xff02);
   a->as_u8[11] = 1;
   ASSERT ((id >> 24) == 0);
   id |= 0xff << 24;
   a->as_u32[3] = clib_host_to_net_u32 (id);
 }

 always_inline void
 ip6_multicast_ethernet_address (u8 * ethernet_address, u32 group_id)
 {
   ethernet_address[0] = 0x33;
   ethernet_address[1] = 0x33;
   ethernet_address[2] = ((group_id >> 24) & 0xff);
   ethernet_address[3] = ((group_id >> 16) & 0xff);
   ethernet_address[4] = ((group_id >> 8) & 0xff);
   ethernet_address[5] = ((group_id >> 0) & 0xff);
 }

 always_inline uword
 ip6_address_is_equal (const ip6_address_t * a, const ip6_address_t * b)
 {
   int i;
   for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
     if (a->as_uword[i] != b->as_uword[i])
       return 0;
   return 1;
 }

 always_inline uword
 ip6_address_is_equal_masked (const ip6_address_t * a,
 			     const ip6_address_t * b,
 			     const ip6_address_t * mask)
 {
   int i;
   for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
     {
       uword a_masked, b_masked;
       a_masked = a->as_uword[i] & mask->as_uword[i];
       b_masked = b->as_uword[i] & mask->as_uword[i];

       if (a_masked != b_masked)
 	return 0;
     }
   return 1;
 }

 always_inline void
 ip6_address_mask (ip6_address_t * a, const ip6_address_t * mask)
 {
   int i;
   for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
     a->as_uword[i] &= mask->as_uword[i];
 }

 always_inline void
 ip6_address_set_zero (ip6_address_t * a)
 {
   int i;
   for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
     a->as_uword[i] = 0;
 }

 always_inline void
 ip6_address_mask_from_width (ip6_address_t * a, u32 width)
 {
   int i, byte, bit, bitnum;
   ASSERT (width <= 128);
   clib_memset (a, 0, sizeof (a[0]));
   for (i = 0; i < width; i++)
     {
       bitnum = (7 - (i & 7));
       byte = i / 8;
       bit = 1 << bitnum;
       a->as_u8[byte] |= bit;
     }
 }

 always_inline uword
 ip6_address_is_zero (const ip6_address_t * a)
 {
   int i;
   for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
     if (a->as_uword[i] != 0)
       return 0;
   return 1;
 }

 /* Check for unspecified address ::0 */
 always_inline uword
 ip6_address_is_unspecified (const ip6_address_t * a)
 {
   return ip6_address_is_zero (a);
 }

 /* Check for loopback address ::1 */
 always_inline uword
 ip6_address_is_loopback (const ip6_address_t * a)
 {
   return (a->as_u64[0] == 0 &&
 	  a->as_u32[2] == 0 &&
 	  a->as_u16[6] == 0 && a->as_u8[14] == 0 && a->as_u8[15] == 1);
 }

 /* Check for link local unicast fe80::/10. */
 always_inline uword
 ip6_address_is_link_local_unicast (const ip6_address_t * a)
 {
   return a->as_u8[0] == 0xfe && (a->as_u8[1] & 0xc0) == 0x80;
 }

 /* Check for unique local unicast fc00::/7. */
 always_inline uword
 ip6_address_is_local_unicast (const ip6_address_t * a)
 {
   return (a->as_u8[0] & 0xfe) == 0xfc;
 }

 /* Check for unique global unicast 2000::/3. */
 always_inline uword
 ip6_address_is_global_unicast (const ip6_address_t * a)
 {
   return (a->as_u8[0] & 0xe0) == 0x20;
 }

 /* Check for solicited node multicast 0xff02::1:ff00:0/104 */
 always_inline uword
 ip6_is_solicited_node_multicast_address (const ip6_address_t * a)
 {
   return (a->as_u32[0] == clib_host_to_net_u32 (0xff020000)
 	  && a->as_u32[1] == 0
 	  && a->as_u32[2] == clib_host_to_net_u32 (1)
 	  && a->as_u8[12] == 0xff);
 }

 always_inline u32
 ip6_address_hash_to_u32 (const ip6_address_t * a)
 {
   return (a->as_u32[0] ^ a->as_u32[1] ^ a->as_u32[2] ^ a->as_u32[3]);
 }

 always_inline u64
 ip6_address_hash_to_u64 (const ip6_address_t * a)
 {
   return (a->as_u64[0] ^ a->as_u64[1]);
 }

 typedef struct
 {
   /* 4 bit version, 8 bit traffic class and 20 bit flow label. */
   u32 ip_version_traffic_class_and_flow_label;

   /* Total packet length not including this header (but including
      any extension headers if present). */
   u16 payload_length;

   /* Protocol for next header. */
   u8 protocol;

   /* Hop limit decremented by router at each hop. */
   u8 hop_limit;

   /* Source and destination address. */
   ip6_address_t src_address, dst_address;
 } ip6_header_t;

 #define IP6_PACKET_TC_MASK 0x0FF00000
 #define IP6_PACKET_DSCP_MASK 0x0FC00000
 #define IP6_PACKET_ECN_MASK 0x00300000
 #define IP6_PACKET_FL_MASK   0x000FFFFF

 always_inline ip_dscp_t
 ip6_traffic_class (const ip6_header_t * i)
 {
   return (i->ip_version_traffic_class_and_flow_label & IP6_PACKET_TC_MASK) >>
     20;
 }

 static_always_inline ip_dscp_t
 ip6_traffic_class_network_order (const ip6_header_t * ip6)
 {
   return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
 	  & IP6_PACKET_TC_MASK) >> 20;
 }

 static_always_inline ip_dscp_t
 ip6_dscp_network_order (const ip6_header_t * ip6)
 {
   return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
 	  & IP6_PACKET_DSCP_MASK) >> 22;
 }

 static_always_inline ip_ecn_t
 ip6_ecn_network_order (const ip6_header_t * ip6)
 {
   return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
 	  & IP6_PACKET_ECN_MASK) >> 20;
 }

 static_always_inline void
 ip6_set_traffic_class_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
 {
   u32 tmp =
     clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
   tmp &= 0xf00fffff;
   tmp |= (dscp << 20);
   ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
 }

 static_always_inline void
 ip6_set_dscp_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
 {
   u32 tmp =
     clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
   tmp &= 0xf03fffff;
   tmp |= (dscp << 22);
   ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
 }

 static_always_inline void
 ip6_set_ecn_network_order (ip6_header_t * ip6, ip_ecn_t ecn)
 {
   u32 tmp =
     clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
   tmp &= 0xffcfffff;
   tmp |= ((0x3 & ecn) << 20);
   ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
 }

 static_always_inline u32
 ip6_flow_label_network_order (const ip6_header_t *ip6)
 {
   u32 tmp =
     clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
   return (tmp & 0xfffff);
 }

 static_always_inline void
 ip6_set_flow_label_network_order (ip6_header_t *ip6, u32 flow_label)
 {
   u32 tmp =
     clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
   tmp &= 0xfff00000;
   tmp |= flow_label & 0x000fffff;
   ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
 }

 static_always_inline u32
 ip6_hop_limit_network_order (const ip6_header_t *ip6)
 {
   return (ip6->hop_limit);
 }

 static_always_inline void
 ip6_set_hop_limit_network_order (ip6_header_t *ip6, u8 hop_limit)
 {
   ip6->hop_limit = hop_limit;
 }

 always_inline void *
 ip6_next_header (ip6_header_t * i)
 {
   return (void *) (i + 1);
 }

 always_inline void
 ip6_copy_header (ip6_header_t * dst, const ip6_header_t * src)
 {
   dst->ip_version_traffic_class_and_flow_label =
     src->ip_version_traffic_class_and_flow_label;
   dst->payload_length = src->payload_length;
   dst->protocol = src->protocol;
   dst->hop_limit = src->hop_limit;

   dst->src_address.as_uword[0] = src->src_address.as_uword[0];
   dst->src_address.as_uword[1] = src->src_address.as_uword[1];
   dst->dst_address.as_uword[0] = src->dst_address.as_uword[0];
   dst->dst_address.as_uword[1] = src->dst_address.as_uword[1];
 }

 always_inline void
 ip6_tcp_reply_x1 (ip6_header_t * ip0, tcp_header_t * tcp0)
 {
   {
     ip6_address_t src0, dst0;

     src0 = ip0->src_address;
     dst0 = ip0->dst_address;
     ip0->src_address = dst0;
     ip0->dst_address = src0;
   }

   {
     u16 src0, dst0;

     src0 = tcp0->src;
     dst0 = tcp0->dst;
     tcp0->src = dst0;
     tcp0->dst = src0;
   }
 }

 always_inline void
 ip6_tcp_reply_x2 (ip6_header_t * ip0, ip6_header_t * ip1,
 		  tcp_header_t * tcp0, tcp_header_t * tcp1)
 {
   {
     ip6_address_t src0, dst0, src1, dst1;

     src0 = ip0->src_address;
     src1 = ip1->src_address;
     dst0 = ip0->dst_address;
     dst1 = ip1->dst_address;
     ip0->src_address = dst0;
     ip1->src_address = dst1;
     ip0->dst_address = src0;
     ip1->dst_address = src1;
   }

   {
     u16 src0, dst0, src1, dst1;

     src0 = tcp0->src;
     src1 = tcp1->src;
     dst0 = tcp0->dst;
     dst1 = tcp1->dst;
     tcp0->src = dst0;
     tcp1->src = dst1;
     tcp0->dst = src0;
     tcp1->dst = src1;
   }
 }

 typedef CLIB_PACKED (struct {
   u8 data;
 }) ip6_pad1_option_t;

 typedef CLIB_PACKED (struct {
   u8 type;
   u8 len;
   u8 data[0];
 }) ip6_padN_option_t;

 typedef CLIB_PACKED (struct {
 #define IP6_MLDP_ALERT_TYPE  0x5
   u8 type;
   u8 len;
   u16 value;
 }) ip6_router_alert_option_t;

 typedef CLIB_PACKED (struct {
   u8 next_hdr;
   /* Length of this header plus option data in 8 byte units. */
   u8 n_data_u64s;
 }) ip6_ext_header_t;

 #define foreach_ext_hdr_type \
   _(IP6_HOP_BY_HOP_OPTIONS) \
   _(IPV6_ROUTE) \
   _(IP6_DESTINATION_OPTIONS) \
   _(MOBILITY) \
   _(HIP) \
   _(SHIM6)

 always_inline u8
 ip6_ext_hdr (u8 nexthdr)
 {
 #ifdef CLIB_HAVE_VEC128
   static const u8x16 ext_hdr_types = {
 #define _(x) IP_PROTOCOL_##x,
     foreach_ext_hdr_type
 #undef _
   };

   return !u8x16_is_all_zero (ext_hdr_types == u8x16_splat (nexthdr));
 #else
   /*
    * find out if nexthdr is an extension header or a protocol
    */
   return 0
 #define _(x) || (nexthdr == IP_PROTOCOL_##x)
     foreach_ext_hdr_type;
 #undef _
 #endif
 }

 typedef CLIB_PACKED (struct {
   u8 next_hdr;
   /* Length of this header plus option data in 8 byte units. */
   u8 n_data_u64s;
   u8 data[0];
 }) ip6_hop_by_hop_ext_t;

 typedef CLIB_PACKED (struct {
   u8 next_hdr;
   u8 rsv;
   u16 fragment_offset_and_more;
   u32 identification;
 }) ip6_frag_hdr_t;

 #define ip6_frag_hdr_offset(hdr)                                              \
   (clib_net_to_host_u16 ((hdr)->fragment_offset_and_more) >> 3)

 #define ip6_frag_hdr_offset_bytes(hdr) (8 * ip6_frag_hdr_offset (hdr))

 #define ip6_frag_hdr_more(hdr)                                                \
   (clib_net_to_host_u16 ((hdr)->fragment_offset_and_more) & 0x1)

 #define ip6_frag_hdr_offset_and_more(offset, more)                            \
   clib_host_to_net_u16 (((offset) << 3) + !!(more))

 #define ip6_ext_header_len(p)  ((((ip6_ext_header_t *)(p))->n_data_u64s+1) << 3)
 #define ip6_ext_authhdr_len(p) ((((ip6_ext_header_t *)(p))->n_data_u64s+2) << 2)

 static inline int
 ip6_ext_header_len_s (ip_protocol_t nh, void *p)
 {
   if (ip6_ext_hdr (nh))
     return ip6_ext_header_len (p);
   switch (nh)
     {
     case IP_PROTOCOL_IPSEC_AH:
       return ip6_ext_authhdr_len (p);
     case IP_PROTOCOL_IPV6_FRAGMENTATION:
       return sizeof (ip6_frag_hdr_t);
     case IP_PROTOCOL_ICMP6:
       return 4;
     case IP_PROTOCOL_UDP:
       return 8;
     case IP_PROTOCOL_TCP:
       return 20;
     default: /* Caller is responsible for validating the length of terminating
 	     protocols */
 	     ;
     }
   return 0;
 }

 always_inline void *
 ip6_ext_next_header (ip6_ext_header_t * ext_hdr)
 {
   return (void *) ((u8 *) ext_hdr + ip6_ext_header_len (ext_hdr));
 }

 always_inline void *
 ip6_ext_next_header_offset (void *hdr, u16 offset)
 {
   return (hdr + offset);
 }

 always_inline int
 vlib_object_within_buffer_data (vlib_main_t * vm, vlib_buffer_t * b,
 				void *obj, size_t len)
 {
   u8 *o = obj;
   if (o < b->data ||
       o + len > b->data + vlib_buffer_get_default_data_size (vm))
     return 0;
   return 1;
 }

 /* Returns the number of bytes left in buffer from p. */
 static inline u32
 vlib_bytes_left_in_buffer (vlib_buffer_t *b, void *obj)
 {
   return b->current_length - (((u8 *) obj - b->data) - b->current_data);
 }

 always_inline void *
 ip6_ext_next_header_s (ip_protocol_t cur_nh, void *hdr, u32 max_offset,
 		       u32 *offset, int *res_nh, bool *last)
 {
   u16 hdrlen = 0;
   int new_nh = -1;
   void *res = 0;
   if (ip6_ext_hdr (cur_nh))
     {
       hdrlen = ip6_ext_header_len (hdr);
       new_nh = ((ip6_ext_header_t *) hdr)->next_hdr;
       res = hdr + hdrlen;
     }
   else if (cur_nh == IP_PROTOCOL_IPV6_FRAGMENTATION)
     {
       ip6_frag_hdr_t *frag_hdr = (ip6_frag_hdr_t *) hdr;
       if (ip6_frag_hdr_offset (frag_hdr) > 0)
 	*last = true;
       new_nh = frag_hdr->next_hdr;
       hdrlen = sizeof (ip6_frag_hdr_t);
       res = hdr + hdrlen;
     }
   else if (cur_nh == IP_PROTOCOL_IPSEC_AH)
     {
       new_nh = ((ip6_ext_header_t *) hdr)->next_hdr;
       hdrlen = ip6_ext_authhdr_len (hdr);
       res = hdr + hdrlen;
     }
   else
     {
       ;
     }

   if (res && (*offset + hdrlen) >= max_offset)
     {
       return 0;
     }
   *res_nh = new_nh;
   *offset += hdrlen;
   return res;
 }

 #define IP6_EXT_HDR_MAX	      (4)   /* Maximum number of headers */
 #define IP6_EXT_HDR_MAX_DEPTH (256) /* Maximum header depth */
 typedef struct
 {
   int length;
   struct
   {
     u16 protocol;
     u16 offset;
   } eh[IP6_EXT_HDR_MAX];
 } ip6_ext_hdr_chain_t;

 /*
  * Find ipv6 extension header within ipv6 header within
  * whichever is smallest of buffer or IP6_EXT_HDR_MAX_DEPTH.
  * The complete header chain must be in first buffer.
  *
  * The complete header chain (up to the terminating header) is
  * returned in res.
  * Returns the index of the find_hdr_type if > 0. Otherwise
  * it returns the index of the last header.
  */
 always_inline int
 ip6_ext_header_walk (vlib_buffer_t *b, ip6_header_t *ip, int find_hdr_type,
 		     ip6_ext_hdr_chain_t *res)
 {
   int i = 0;
   int found = -1;
   void *next_header = ip6_next_header (ip);
   int next_proto = ip->protocol;
   res->length = 0;
   u32 n_bytes_this_buffer =
     clib_min (vlib_bytes_left_in_buffer (b, ip), IP6_EXT_HDR_MAX_DEPTH);
   u32 max_offset = clib_min (n_bytes_this_buffer,
 			     sizeof (ip6_header_t) +
 			       clib_net_to_host_u16 (ip->payload_length));
   u32 offset = sizeof (ip6_header_t);
   if ((ip6_ext_header_len_s (ip->protocol, next_header) + offset) > max_offset)
     {
       return -1;
     }
   bool last = false;
   while (next_header)
     {
       /* Move on to next header */
       res->eh[i].offset = offset;
       res->eh[i].protocol = next_proto;
       if (next_proto == find_hdr_type)
 	found = i;
       i++;
       if (last)
 	break;
       if (i > IP6_EXT_HDR_MAX)
 	break;
       next_header = ip6_ext_next_header_s (next_proto, next_header, max_offset,
 					   &offset, &next_proto, &last);
     }
   res->length = i;
   if (find_hdr_type < 0)
     return i - 1;
   return found != -1 ? found : i - 1;
 }

 always_inline void *
 ip6_ext_header_find (vlib_main_t *vm, vlib_buffer_t *b, ip6_header_t *ip,
 		     int find_hdr_type, ip6_ext_header_t **prev_ext_header)
 {
   ip6_ext_hdr_chain_t hdr_chain;
   int res = ip6_ext_header_walk (b, ip, find_hdr_type, &hdr_chain);
   if (res < 0)
     return 0;

   if (prev_ext_header)
     {
       if (res > 0)
 	{
 	  *prev_ext_header =
 	    ip6_ext_next_header_offset (ip, hdr_chain.eh[res - 1].offset);
 	}
       else
 	{
 	  *prev_ext_header = 0;
 	}
     }
   if (find_hdr_type == hdr_chain.eh[res].protocol)
     return ip6_ext_next_header_offset (ip, hdr_chain.eh[res].offset);
   return 0;
 }

 #endif /* included_ip6_packet_h */

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* 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.
	*/
	/*
	* ip6/packet.h: ip6 packet format
	*
	* Copyright (c) 2008 Eliot Dresselhaus
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sublicense, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice shall be
	* included in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/

	#ifndef included_ip6_packet_h
	#define included_ip6_packet_h

	#include <vnet/tcp/tcp_packet.h>
	#include <vnet/ip/ip4_packet.h>
	#include <stdbool.h>

	typedef union
	{
	u8 as_u8[16];
	u16 as_u16[8];
	u32 as_u32[4];
	u64 as_u64[2];
	u64x2 as_u128;
	uword as_uword[16 / sizeof (uword)];
	}
	__clib_packed ip6_address_t;

	STATIC_ASSERT_SIZEOF (ip6_address_t, 16);

	typedef struct
	{
	ip6_address_t addr, mask;
	} ip6_address_and_mask_t;

	/* Packed so that the mhash key doesn't include uninitialized pad bytes */
	typedef CLIB_PACKED (struct {
	/* IP address must be first for ip_interface_address_get_address() to work */
	ip6_address_t ip6_addr;
	u32 fib_index;
	}) ip6_address_fib_t;

	always_inline void
	ip6_addr_fib_init (ip6_address_fib_t * addr_fib,
	const ip6_address_t * address, u32 fib_index)
	{
	addr_fib->ip6_addr = *address;
	addr_fib->fib_index = fib_index;
	}

	/* Special addresses:
	unspecified ::/128
	loopback ::1/128
	global unicast 2000::/3
	unique local unicast fc00::/7
	link local unicast fe80::/10
	multicast ff00::/8
	ietf reserved everything else. */

	#define foreach_ip6_multicast_address_scope \
	_ (loopback, 0x1) \
	_ (link_local, 0x2) \
	_ (admin_local, 0x4) \
	_ (site_local, 0x5) \
	_ (organization_local, 0x8) \
	_ (global, 0xe)

	#define foreach_ip6_multicast_link_local_group_id \
	_ (all_hosts, 0x1) \
	_ (all_routers, 0x2) \
	_ (rip_routers, 0x9) \
	_ (eigrp_routers, 0xa) \
	_ (pim_routers, 0xd) \
	_ (mldv2_routers, 0x16)

	typedef enum
	{
	#define _(f,n) IP6_MULTICAST_SCOPE_##f = n,
	foreach_ip6_multicast_address_scope
	#undef _
	} ip6_multicast_address_scope_t;

	typedef enum
	{
	#define _(f,n) IP6_MULTICAST_GROUP_ID_##f = n,
	foreach_ip6_multicast_link_local_group_id
	#undef _
	} ip6_multicast_link_local_group_id_t;

	always_inline uword
	ip6_address_is_multicast (const ip6_address_t * a)
	{
	return a->as_u8[0] == 0xff;
	}

	always_inline void
	ip6_address_copy (ip6_address_t * dst, const ip6_address_t * src)
	{
	dst->as_u64[0] = src->as_u64[0];
	dst->as_u64[1] = src->as_u64[1];
	}

	always_inline void
	ip6_set_reserved_multicast_address (ip6_address_t * a,
	ip6_multicast_address_scope_t scope,
	u16 id)
	{
	a->as_u64[0] = a->as_u64[1] = 0;
	a->as_u16[0] = clib_host_to_net_u16 (0xff00 \| scope);
	a->as_u16[7] = clib_host_to_net_u16 (id);
	}

	always_inline void
	ip6_set_solicited_node_multicast_address (ip6_address_t * a, u32 id)
	{
	/* 0xff02::1:ffXX:XXXX. */
	a->as_u64[0] = a->as_u64[1] = 0;
	a->as_u16[0] = clib_host_to_net_u16 (0xff02);
	a->as_u8[11] = 1;
	ASSERT ((id >> 24) == 0);
	id \|= 0xff << 24;
	a->as_u32[3] = clib_host_to_net_u32 (id);
	}

	always_inline void
	ip6_multicast_ethernet_address (u8 * ethernet_address, u32 group_id)
	{
	ethernet_address[0] = 0x33;
	ethernet_address[1] = 0x33;
	ethernet_address[2] = ((group_id >> 24) & 0xff);
	ethernet_address[3] = ((group_id >> 16) & 0xff);
	ethernet_address[4] = ((group_id >> 8) & 0xff);
	ethernet_address[5] = ((group_id >> 0) & 0xff);
	}

	always_inline uword
	ip6_address_is_equal (const ip6_address_t * a, const ip6_address_t * b)
	{
	int i;
	for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
	if (a->as_uword[i] != b->as_uword[i])
	return 0;
	return 1;
	}

	always_inline uword
	ip6_address_is_equal_masked (const ip6_address_t * a,
	const ip6_address_t * b,
	const ip6_address_t * mask)
	{
	int i;
	for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
	{
	uword a_masked, b_masked;
	a_masked = a->as_uword[i] & mask->as_uword[i];
	b_masked = b->as_uword[i] & mask->as_uword[i];

	if (a_masked != b_masked)
	return 0;
	}
	return 1;
	}

	always_inline void
	ip6_address_mask (ip6_address_t * a, const ip6_address_t * mask)
	{
	int i;
	for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
	a->as_uword[i] &= mask->as_uword[i];
	}

	always_inline void
	ip6_address_set_zero (ip6_address_t * a)
	{
	int i;
	for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
	a->as_uword[i] = 0;
	}

	always_inline void
	ip6_address_mask_from_width (ip6_address_t * a, u32 width)
	{
	int i, byte, bit, bitnum;
	ASSERT (width <= 128);
	clib_memset (a, 0, sizeof (a[0]));
	for (i = 0; i < width; i++)
	{
	bitnum = (7 - (i & 7));
	byte = i / 8;
	bit = 1 << bitnum;
	a->as_u8[byte] \|= bit;
	}
	}

	always_inline uword
	ip6_address_is_zero (const ip6_address_t * a)
	{
	int i;
	for (i = 0; i < ARRAY_LEN (a->as_uword); i++)
	if (a->as_uword[i] != 0)
	return 0;
	return 1;
	}

	/* Check for unspecified address ::0 */
	always_inline uword
	ip6_address_is_unspecified (const ip6_address_t * a)
	{
	return ip6_address_is_zero (a);
	}

	/* Check for loopback address ::1 */
	always_inline uword
	ip6_address_is_loopback (const ip6_address_t * a)
	{
	return (a->as_u64[0] == 0 &&
	a->as_u32[2] == 0 &&
	a->as_u16[6] == 0 && a->as_u8[14] == 0 && a->as_u8[15] == 1);
	}

	/* Check for link local unicast fe80::/10. */
	always_inline uword
	ip6_address_is_link_local_unicast (const ip6_address_t * a)
	{
	return a->as_u8[0] == 0xfe && (a->as_u8[1] & 0xc0) == 0x80;
	}

	/* Check for unique local unicast fc00::/7. */
	always_inline uword
	ip6_address_is_local_unicast (const ip6_address_t * a)
	{
	return (a->as_u8[0] & 0xfe) == 0xfc;
	}

	/* Check for unique global unicast 2000::/3. */
	always_inline uword
	ip6_address_is_global_unicast (const ip6_address_t * a)
	{
	return (a->as_u8[0] & 0xe0) == 0x20;
	}

	/* Check for solicited node multicast 0xff02::1:ff00:0/104 */
	always_inline uword
	ip6_is_solicited_node_multicast_address (const ip6_address_t * a)
	{
	return (a->as_u32[0] == clib_host_to_net_u32 (0xff020000)
	&& a->as_u32[1] == 0
	&& a->as_u32[2] == clib_host_to_net_u32 (1)
	&& a->as_u8[12] == 0xff);
	}

	always_inline u32
	ip6_address_hash_to_u32 (const ip6_address_t * a)
	{
	return (a->as_u32[0] ^ a->as_u32[1] ^ a->as_u32[2] ^ a->as_u32[3]);
	}

	always_inline u64
	ip6_address_hash_to_u64 (const ip6_address_t * a)
	{
	return (a->as_u64[0] ^ a->as_u64[1]);
	}

	typedef struct
	{
	/* 4 bit version, 8 bit traffic class and 20 bit flow label. */
	u32 ip_version_traffic_class_and_flow_label;

	/* Total packet length not including this header (but including
	any extension headers if present). */
	u16 payload_length;

	/* Protocol for next header. */
	u8 protocol;

	/* Hop limit decremented by router at each hop. */
	u8 hop_limit;

	/* Source and destination address. */
	ip6_address_t src_address, dst_address;
	} ip6_header_t;

	#define IP6_PACKET_TC_MASK 0x0FF00000
	#define IP6_PACKET_DSCP_MASK 0x0FC00000
	#define IP6_PACKET_ECN_MASK 0x00300000
	#define IP6_PACKET_FL_MASK 0x000FFFFF

	always_inline ip_dscp_t
	ip6_traffic_class (const ip6_header_t * i)
	{
	return (i->ip_version_traffic_class_and_flow_label & IP6_PACKET_TC_MASK) >>
	20;
	}

	static_always_inline ip_dscp_t
	ip6_traffic_class_network_order (const ip6_header_t * ip6)
	{
	return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
	& IP6_PACKET_TC_MASK) >> 20;
	}

	static_always_inline ip_dscp_t
	ip6_dscp_network_order (const ip6_header_t * ip6)
	{
	return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
	& IP6_PACKET_DSCP_MASK) >> 22;
	}

	static_always_inline ip_ecn_t
	ip6_ecn_network_order (const ip6_header_t * ip6)
	{
	return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
	& IP6_PACKET_ECN_MASK) >> 20;
	}

	static_always_inline void
	ip6_set_traffic_class_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
	{
	u32 tmp =
	clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
	tmp &= 0xf00fffff;
	tmp \|= (dscp << 20);
	ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
	}

	static_always_inline void
	ip6_set_dscp_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
	{
	u32 tmp =
	clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
	tmp &= 0xf03fffff;
	tmp \|= (dscp << 22);
	ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
	}

	static_always_inline void
	ip6_set_ecn_network_order (ip6_header_t * ip6, ip_ecn_t ecn)
	{
	u32 tmp =
	clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
	tmp &= 0xffcfffff;
	tmp \|= ((0x3 & ecn) << 20);
	ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
	}

	static_always_inline u32
	ip6_flow_label_network_order (const ip6_header_t *ip6)
	{
	u32 tmp =
	clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
	return (tmp & 0xfffff);
	}

	static_always_inline void
	ip6_set_flow_label_network_order (ip6_header_t *ip6, u32 flow_label)
	{
	u32 tmp =
	clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label);
	tmp &= 0xfff00000;
	tmp \|= flow_label & 0x000fffff;
	ip6->ip_version_traffic_class_and_flow_label = clib_host_to_net_u32 (tmp);
	}

	static_always_inline u32
	ip6_hop_limit_network_order (const ip6_header_t *ip6)
	{
	return (ip6->hop_limit);
	}

	static_always_inline void
	ip6_set_hop_limit_network_order (ip6_header_t *ip6, u8 hop_limit)
	{
	ip6->hop_limit = hop_limit;
	}

	always_inline void *
	ip6_next_header (ip6_header_t * i)
	{
	return (void *) (i + 1);
	}

	always_inline void
	ip6_copy_header (ip6_header_t * dst, const ip6_header_t * src)
	{
	dst->ip_version_traffic_class_and_flow_label =
	src->ip_version_traffic_class_and_flow_label;
	dst->payload_length = src->payload_length;
	dst->protocol = src->protocol;
	dst->hop_limit = src->hop_limit;

	dst->src_address.as_uword[0] = src->src_address.as_uword[0];
	dst->src_address.as_uword[1] = src->src_address.as_uword[1];
	dst->dst_address.as_uword[0] = src->dst_address.as_uword[0];
	dst->dst_address.as_uword[1] = src->dst_address.as_uword[1];
	}

	always_inline void
	ip6_tcp_reply_x1 (ip6_header_t * ip0, tcp_header_t * tcp0)
	{
	{
	ip6_address_t src0, dst0;

	src0 = ip0->src_address;
	dst0 = ip0->dst_address;
	ip0->src_address = dst0;
	ip0->dst_address = src0;
	}

	{
	u16 src0, dst0;

	src0 = tcp0->src;
	dst0 = tcp0->dst;
	tcp0->src = dst0;
	tcp0->dst = src0;
	}
	}

	always_inline void
	ip6_tcp_reply_x2 (ip6_header_t * ip0, ip6_header_t * ip1,
	tcp_header_t * tcp0, tcp_header_t * tcp1)
	{
	{
	ip6_address_t src0, dst0, src1, dst1;

	src0 = ip0->src_address;
	src1 = ip1->src_address;
	dst0 = ip0->dst_address;
	dst1 = ip1->dst_address;
	ip0->src_address = dst0;
	ip1->src_address = dst1;
	ip0->dst_address = src0;
	ip1->dst_address = src1;
	}

	{
	u16 src0, dst0, src1, dst1;

	src0 = tcp0->src;
	src1 = tcp1->src;
	dst0 = tcp0->dst;
	dst1 = tcp1->dst;
	tcp0->src = dst0;
	tcp1->src = dst1;
	tcp0->dst = src0;
	tcp1->dst = src1;
	}
	}

	typedef CLIB_PACKED (struct {
	u8 data;
	}) ip6_pad1_option_t;

	typedef CLIB_PACKED (struct {
	u8 type;
	u8 len;
	u8 data[0];
	}) ip6_padN_option_t;

	typedef CLIB_PACKED (struct {
	#define IP6_MLDP_ALERT_TYPE 0x5
	u8 type;
	u8 len;
	u16 value;
	}) ip6_router_alert_option_t;

	typedef CLIB_PACKED (struct {
	u8 next_hdr;
	/* Length of this header plus option data in 8 byte units. */
	u8 n_data_u64s;
	}) ip6_ext_header_t;

	#define foreach_ext_hdr_type \
	_(IP6_HOP_BY_HOP_OPTIONS) \
	_(IPV6_ROUTE) \
	_(IP6_DESTINATION_OPTIONS) \
	_(MOBILITY) \
	_(HIP) \
	_(SHIM6)

	always_inline u8
	ip6_ext_hdr (u8 nexthdr)
	{
	#ifdef CLIB_HAVE_VEC128
	static const u8x16 ext_hdr_types = {
	#define _(x) IP_PROTOCOL_##x,
	foreach_ext_hdr_type
	#undef _
	};

	return !u8x16_is_all_zero (ext_hdr_types == u8x16_splat (nexthdr));
	#else
	/*
	* find out if nexthdr is an extension header or a protocol
	*/
	return 0
	#define _(x) \|\| (nexthdr == IP_PROTOCOL_##x)
	foreach_ext_hdr_type;
	#undef _
	#endif
	}

	typedef CLIB_PACKED (struct {
	u8 next_hdr;
	/* Length of this header plus option data in 8 byte units. */
	u8 n_data_u64s;
	u8 data[0];
	}) ip6_hop_by_hop_ext_t;

	typedef CLIB_PACKED (struct {
	u8 next_hdr;
	u8 rsv;
	u16 fragment_offset_and_more;
	u32 identification;
	}) ip6_frag_hdr_t;

	#define ip6_frag_hdr_offset(hdr) \
	(clib_net_to_host_u16 ((hdr)->fragment_offset_and_more) >> 3)

	#define ip6_frag_hdr_offset_bytes(hdr) (8 * ip6_frag_hdr_offset (hdr))

	#define ip6_frag_hdr_more(hdr) \
	(clib_net_to_host_u16 ((hdr)->fragment_offset_and_more) & 0x1)

	#define ip6_frag_hdr_offset_and_more(offset, more) \
	clib_host_to_net_u16 (((offset) << 3) + !!(more))

	#define ip6_ext_header_len(p) ((((ip6_ext_header_t *)(p))->n_data_u64s+1) << 3)
	#define ip6_ext_authhdr_len(p) ((((ip6_ext_header_t *)(p))->n_data_u64s+2) << 2)

	static inline int
	ip6_ext_header_len_s (ip_protocol_t nh, void *p)
	{
	if (ip6_ext_hdr (nh))
	return ip6_ext_header_len (p);
	switch (nh)
	{
	case IP_PROTOCOL_IPSEC_AH:
	return ip6_ext_authhdr_len (p);
	case IP_PROTOCOL_IPV6_FRAGMENTATION:
	return sizeof (ip6_frag_hdr_t);
	case IP_PROTOCOL_ICMP6:
	return 4;
	case IP_PROTOCOL_UDP:
	return 8;
	case IP_PROTOCOL_TCP:
	return 20;
	default: /* Caller is responsible for validating the length of terminating
	protocols */
	;
	}
	return 0;
	}

	always_inline void *
	ip6_ext_next_header (ip6_ext_header_t * ext_hdr)
	{
	return (void ) ((u8 ) ext_hdr + ip6_ext_header_len (ext_hdr));
	}

	always_inline void *
	ip6_ext_next_header_offset (void *hdr, u16 offset)
	{
	return (hdr + offset);
	}

	always_inline int
	vlib_object_within_buffer_data (vlib_main_t * vm, vlib_buffer_t * b,
	void *obj, size_t len)
	{
	u8 *o = obj;
	if (o < b->data \|\|
	o + len > b->data + vlib_buffer_get_default_data_size (vm))
	return 0;
	return 1;
	}

	/* Returns the number of bytes left in buffer from p. */
	static inline u32
	vlib_bytes_left_in_buffer (vlib_buffer_t b, void obj)
	{
	return b->current_length - (((u8 *) obj - b->data) - b->current_data);
	}

	always_inline void *
	ip6_ext_next_header_s (ip_protocol_t cur_nh, void *hdr, u32 max_offset,
	u32 offset, int res_nh, bool *last)
	{
	u16 hdrlen = 0;
	int new_nh = -1;
	void *res = 0;
	if (ip6_ext_hdr (cur_nh))
	{
	hdrlen = ip6_ext_header_len (hdr);
	new_nh = ((ip6_ext_header_t *) hdr)->next_hdr;
	res = hdr + hdrlen;
	}
	else if (cur_nh == IP_PROTOCOL_IPV6_FRAGMENTATION)
	{
	ip6_frag_hdr_t frag_hdr = (ip6_frag_hdr_t ) hdr;
	if (ip6_frag_hdr_offset (frag_hdr) > 0)
	*last = true;
	new_nh = frag_hdr->next_hdr;
	hdrlen = sizeof (ip6_frag_hdr_t);
	res = hdr + hdrlen;
	}
	else if (cur_nh == IP_PROTOCOL_IPSEC_AH)
	{
	new_nh = ((ip6_ext_header_t *) hdr)->next_hdr;
	hdrlen = ip6_ext_authhdr_len (hdr);
	res = hdr + hdrlen;
	}
	else
	{
	;
	}

	if (res && (*offset + hdrlen) >= max_offset)
	{
	return 0;
	}
	*res_nh = new_nh;
	*offset += hdrlen;
	return res;
	}

	#define IP6_EXT_HDR_MAX (4) /* Maximum number of headers */
	#define IP6_EXT_HDR_MAX_DEPTH (256) /* Maximum header depth */
	typedef struct
	{
	int length;
	struct
	{
	u16 protocol;
	u16 offset;
	} eh[IP6_EXT_HDR_MAX];
	} ip6_ext_hdr_chain_t;

	/*
	* Find ipv6 extension header within ipv6 header within
	* whichever is smallest of buffer or IP6_EXT_HDR_MAX_DEPTH.
	* The complete header chain must be in first buffer.
	*
	* The complete header chain (up to the terminating header) is
	* returned in res.
	* Returns the index of the find_hdr_type if > 0. Otherwise
	* it returns the index of the last header.
	*/
	always_inline int
	ip6_ext_header_walk (vlib_buffer_t b, ip6_header_t ip, int find_hdr_type,
	ip6_ext_hdr_chain_t *res)
	{
	int i = 0;
	int found = -1;
	void *next_header = ip6_next_header (ip);
	int next_proto = ip->protocol;
	res->length = 0;
	u32 n_bytes_this_buffer =
	clib_min (vlib_bytes_left_in_buffer (b, ip), IP6_EXT_HDR_MAX_DEPTH);
	u32 max_offset = clib_min (n_bytes_this_buffer,
	sizeof (ip6_header_t) +
	clib_net_to_host_u16 (ip->payload_length));
	u32 offset = sizeof (ip6_header_t);
	if ((ip6_ext_header_len_s (ip->protocol, next_header) + offset) > max_offset)
	{
	return -1;
	}
	bool last = false;
	while (next_header)
	{
	/* Move on to next header */
	res->eh[i].offset = offset;
	res->eh[i].protocol = next_proto;
	if (next_proto == find_hdr_type)
	found = i;
	i++;
	if (last)
	break;
	if (i > IP6_EXT_HDR_MAX)
	break;
	next_header = ip6_ext_next_header_s (next_proto, next_header, max_offset,
	&offset, &next_proto, &last);
	}
	res->length = i;
	if (find_hdr_type < 0)
	return i - 1;
	return found != -1 ? found : i - 1;
	}

	always_inline void *
	ip6_ext_header_find (vlib_main_t vm, vlib_buffer_t b, ip6_header_t *ip,
	int find_hdr_type, ip6_ext_header_t **prev_ext_header)
	{
	ip6_ext_hdr_chain_t hdr_chain;
	int res = ip6_ext_header_walk (b, ip, find_hdr_type, &hdr_chain);
	if (res < 0)
	return 0;

	if (prev_ext_header)
	{
	if (res > 0)
	{
	*prev_ext_header =
	ip6_ext_next_header_offset (ip, hdr_chain.eh[res - 1].offset);
	}
	else
	{
	*prev_ext_header = 0;
	}
	}
	if (find_hdr_type == hdr_chain.eh[res].protocol)
	return ip6_ext_next_header_offset (ip, hdr_chain.eh[res].offset);
	return 0;
	}

	#endif /* included_ip6_packet_h */

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/