text: /*
   * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   *
   * 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 PACKETS_H
  #define PACKETS_H 1
  
  #include <inttypes.h>
  #include <sys/types.h>
  #include <netinet/in.h>
  #include <stdint.h>
  #include <string.h>
  #include "compiler.h"
  #include "flow.h"
  #include "openvswitch/types.h"
  #include "random.h"
  #include "util.h"
  
  struct ofpbuf;
  struct ds;
  
  bool dpid_from_string(const char *s, uint64_t *dpidp);
  
  #define ETH_ADDR_LEN           6
  
  static const uint8_t eth_addr_broadcast[ETH_ADDR_LEN] OVS_UNUSED
      = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  
  static const uint8_t eth_addr_stp[ETH_ADDR_LEN] OVS_UNUSED
      = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x00 };
  
  static const uint8_t eth_addr_lacp[ETH_ADDR_LEN] OVS_UNUSED
      = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x02 };
  
  static const uint8_t eth_addr_bfd[ETH_ADDR_LEN] OVS_UNUSED
      = { 0x00, 0x23, 0x20, 0x00, 0x00, 0x01 };
  
  static inline bool eth_addr_is_broadcast(const uint8_t ea[6])
  {
      return (ea[0] & ea[1] & ea[2] & ea[3] & ea[4] & ea[5]) == 0xff;
  }
  
  static inline bool eth_addr_is_multicast(const uint8_t ea[6])
  {
      return ea[0] & 1;
  }
  static inline bool eth_addr_is_local(const uint8_t ea[6])
  {
      /* Local if it is either a locally administered address or a Nicira random
       * address. */
      return ea[0] & 2
         || (ea[0] == 0x00 && ea[1] == 0x23 && ea[2] == 0x20 && ea[3] & 0x80);
  }
  static inline bool eth_addr_is_zero(const uint8_t ea[6])
  {
      return !(ea[0] | ea[1] | ea[2] | ea[3] | ea[4] | ea[5]);
  }
  
  static inline int eth_mask_is_exact(const uint8_t ea[ETH_ADDR_LEN])
  {
      return (ea[0] & ea[1] & ea[2] & ea[3] & ea[4] & ea[5]) == 0xff;
  }
  
  static inline int eth_addr_compare_3way(const uint8_t a[ETH_ADDR_LEN],
                                          const uint8_t b[ETH_ADDR_LEN])
  {
      return memcmp(a, b, ETH_ADDR_LEN);
  }
  static inline bool eth_addr_equals(const uint8_t a[ETH_ADDR_LEN],
                                     const uint8_t b[ETH_ADDR_LEN])
  {
      return !eth_addr_compare_3way(a, b);
  }
  static inline bool eth_addr_equal_except(const uint8_t a[ETH_ADDR_LEN],
                                      const uint8_t b[ETH_ADDR_LEN],
                                      const uint8_t mask[ETH_ADDR_LEN])
  {
      return !(((a[0] ^ b[0]) & mask[0])
               || ((a[1] ^ b[1]) & mask[1])
               || ((a[2] ^ b[2]) & mask[2])
               || ((a[3] ^ b[3]) & mask[3])
               || ((a[4] ^ b[4]) & mask[4])
               || ((a[5] ^ b[5]) & mask[5]));
  }
  static inline uint64_t eth_addr_to_uint64(const uint8_t ea[ETH_ADDR_LEN])
  {
      return (((uint64_t) ea[0] << 40)
              | ((uint64_t) ea[1] << 32)
              | ((uint64_t) ea[2] << 24)
              | ((uint64_t) ea[3] << 16)
              | ((uint64_t) ea[4] << 8)
              | ea[5]);
  }
  static inline void eth_addr_from_uint64(uint64_t x, uint8_t ea[ETH_ADDR_LEN])
  {
      ea[0] = x >> 40;
      ea[1] = x >> 32;
      ea[2] = x >> 24;
      ea[3] = x >> 16;
      ea[4] = x >> 8;
      ea[5] = x;
  }
  static inline void eth_addr_mark_random(uint8_t ea[ETH_ADDR_LEN])
  {
      ea[0] &= ~1;                /* Unicast. */
      ea[0] |= 2;                 /* Private. */
  }
  static inline void eth_addr_random(uint8_t ea[ETH_ADDR_LEN])
  {
      random_bytes(ea, ETH_ADDR_LEN);
      eth_addr_mark_random(ea);
  }
  static inline void eth_addr_nicira_random(uint8_t ea[ETH_ADDR_LEN])
  {
      eth_addr_random(ea);
  
      /* Set the OUI to the Nicira one. */
      ea[0] = 0x00;
      ea[1] = 0x23;
      ea[2] = 0x20;
  
      /* Set the top bit to indicate random Nicira address. */
      ea[3] |= 0x80;
  }
  
  bool eth_addr_is_reserved(const uint8_t ea[ETH_ADDR_LEN]);
  bool eth_addr_from_string(const char *, uint8_t ea[ETH_ADDR_LEN]);
  
  void compose_rarp(struct ofpbuf *, const uint8_t eth_src[ETH_ADDR_LEN]);
  
  void eth_push_vlan(struct ofpbuf *, ovs_be16 tci);
  void eth_pop_vlan(struct ofpbuf *);
  
  uint16_t eth_mpls_depth(const struct ofpbuf *packet);
  
  void set_ethertype(struct ofpbuf *packet, ovs_be16 eth_type);
  
  const char *eth_from_hex(const char *hex, struct ofpbuf **packetp);
  void eth_format_masked(const uint8_t eth[ETH_ADDR_LEN],
                         const uint8_t mask[ETH_ADDR_LEN], struct ds *s);
  void eth_addr_bitand(const uint8_t src[ETH_ADDR_LEN],
                       const uint8_t mask[ETH_ADDR_LEN],
                       uint8_t dst[ETH_ADDR_LEN]);
  
  void set_mpls_lse(struct ofpbuf *, ovs_be32 label);
  void push_mpls(struct ofpbuf *packet, ovs_be16 ethtype, ovs_be32 lse);
  void pop_mpls(struct ofpbuf *, ovs_be16 ethtype);
  
  void set_mpls_lse_ttl(ovs_be32 *lse, uint8_t ttl);
  void set_mpls_lse_tc(ovs_be32 *lse, uint8_t tc);
  void set_mpls_lse_label(ovs_be32 *lse, ovs_be32 label);
  void set_mpls_lse_bos(ovs_be32 *lse, uint8_t bos);
  ovs_be32 set_mpls_lse_values(uint8_t ttl, uint8_t tc, uint8_t bos,
                               ovs_be32 label);
  
  /* Example:
   *
   * uint8_t mac[ETH_ADDR_LEN];
   *    [...]
   * printf("The Ethernet address is "ETH_ADDR_FMT"\n", ETH_ADDR_ARGS(mac));
   *
   */
  #define ETH_ADDR_FMT                                                    \
      "%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8
  #define ETH_ADDR_ARGS(ea)                                   \
      (ea)[0], (ea)[1], (ea)[2], (ea)[3], (ea)[4], (ea)[5]
  
  /* Example:
   *
   * char *string = "1 00:11:22:33:44:55 2";
   * uint8_t mac[ETH_ADDR_LEN];
   * int a, b;
   *
   * if (sscanf(string, "%d"ETH_ADDR_SCAN_FMT"%d",
   *     &a, ETH_ADDR_SCAN_ARGS(mac), &b) == 1 + ETH_ADDR_SCAN_COUNT + 1) {
   *     ...
   * }
   */
  #define ETH_ADDR_SCAN_FMT "%"SCNx8":%"SCNx8":%"SCNx8":%"SCNx8":%"SCNx8":%"SCNx8
  #define ETH_ADDR_SCAN_ARGS(ea) \
          &(ea)[0], &(ea)[1], &(ea)[2], &(ea)[3], &(ea)[4], &(ea)[5]
  #define ETH_ADDR_SCAN_COUNT 6
  
  #define ETH_TYPE_IP            0x0800
  #define ETH_TYPE_ARP           0x0806
  #define ETH_TYPE_VLAN_8021Q    0x8100
  #define ETH_TYPE_VLAN          ETH_TYPE_VLAN_8021Q
  #define ETH_TYPE_VLAN_8021AD   0x88a8
  #define ETH_TYPE_IPV6          0x86dd
  #define ETH_TYPE_LACP          0x8809
  #define ETH_TYPE_RARP          0x8035
  #define ETH_TYPE_MPLS          0x8847
  #define ETH_TYPE_MPLS_MCAST    0x8848
  
  static inline bool eth_type_mpls(ovs_be16 eth_type)
  {
      return eth_type == htons(ETH_TYPE_MPLS) ||
          eth_type == htons(ETH_TYPE_MPLS_MCAST);
  }
  
  /* Minimum value for an Ethernet type.  Values below this are IEEE 802.2 frame
   * lengths. */
  #define ETH_TYPE_MIN           0x600
  
  #define ETH_HEADER_LEN 14
  #define ETH_PAYLOAD_MIN 46
  #define ETH_PAYLOAD_MAX 1500
  #define ETH_TOTAL_MIN (ETH_HEADER_LEN + ETH_PAYLOAD_MIN)
  #define ETH_TOTAL_MAX (ETH_HEADER_LEN + ETH_PAYLOAD_MAX)
  #define ETH_VLAN_TOTAL_MAX (ETH_HEADER_LEN + VLAN_HEADER_LEN + ETH_PAYLOAD_MAX)
  OVS_PACKED(
  struct eth_header {
      uint8_t eth_dst[ETH_ADDR_LEN];
      uint8_t eth_src[ETH_ADDR_LEN];
      ovs_be16 eth_type;
  });
  BUILD_ASSERT_DECL(ETH_HEADER_LEN == sizeof(struct eth_header));
  
  #define LLC_DSAP_SNAP 0xaa
  #define LLC_SSAP_SNAP 0xaa
  #define LLC_CNTL_SNAP 3
  
  #define LLC_HEADER_LEN 3
  OVS_PACKED(
  struct llc_header {
      uint8_t llc_dsap;
      uint8_t llc_ssap;
      uint8_t llc_cntl;
  });
  BUILD_ASSERT_DECL(LLC_HEADER_LEN == sizeof(struct llc_header));
  
  #define SNAP_ORG_ETHERNET "\0\0" /* The compiler adds a null byte, so
                                      sizeof(SNAP_ORG_ETHERNET) == 3. */
  #define SNAP_HEADER_LEN 5
  OVS_PACKED(
  struct snap_header {
      uint8_t snap_org[3];
      ovs_be16 snap_type;
  });
  BUILD_ASSERT_DECL(SNAP_HEADER_LEN == sizeof(struct snap_header));
  
  #define LLC_SNAP_HEADER_LEN (LLC_HEADER_LEN + SNAP_HEADER_LEN)
  OVS_PACKED(
  struct llc_snap_header {
      struct llc_header llc;
      struct snap_header snap;
  });
  BUILD_ASSERT_DECL(LLC_SNAP_HEADER_LEN == sizeof(struct llc_snap_header));
  
  #define VLAN_VID_MASK 0x0fff
  #define VLAN_VID_SHIFT 0
  
  #define VLAN_PCP_MASK 0xe000
  #define VLAN_PCP_SHIFT 13
  
  #define VLAN_CFI 0x1000
  #define VLAN_CFI_SHIFT 12
  
  /* Given the vlan_tci field from an 802.1Q header, in network byte order,
   * returns the VLAN ID in host byte order. */
  static inline uint16_t
  vlan_tci_to_vid(ovs_be16 vlan_tci)
  {
      return (ntohs(vlan_tci) & VLAN_VID_MASK) >> VLAN_VID_SHIFT;
  }
  
  /* Given the vlan_tci field from an 802.1Q header, in network byte order,
   * returns the priority code point (PCP) in host byte order. */
  static inline int
  vlan_tci_to_pcp(ovs_be16 vlan_tci)
  {
      return (ntohs(vlan_tci) & VLAN_PCP_MASK) >> VLAN_PCP_SHIFT;
  }
  
  /* Given the vlan_tci field from an 802.1Q header, in network byte order,
   * returns the Canonical Format Indicator (CFI). */
  static inline int
  vlan_tci_to_cfi(ovs_be16 vlan_tci)
  {
      return (vlan_tci & htons(VLAN_CFI)) != 0;
  }
  
  #define VLAN_HEADER_LEN 4
  struct vlan_header {
      ovs_be16 vlan_tci;          /* Lowest 12 bits are VLAN ID. */
      ovs_be16 vlan_next_type;
  };
  BUILD_ASSERT_DECL(VLAN_HEADER_LEN == sizeof(struct vlan_header));
  
  #define VLAN_ETH_HEADER_LEN (ETH_HEADER_LEN + VLAN_HEADER_LEN)
  OVS_PACKED(
  struct vlan_eth_header {
      uint8_t veth_dst[ETH_ADDR_LEN];
      uint8_t veth_src[ETH_ADDR_LEN];
      ovs_be16 veth_type;         /* Always htons(ETH_TYPE_VLAN). */
      ovs_be16 veth_tci;          /* Lowest 12 bits are VLAN ID. */
      ovs_be16 veth_next_type;
  });
  BUILD_ASSERT_DECL(VLAN_ETH_HEADER_LEN == sizeof(struct vlan_eth_header));
  
  /* MPLS related definitions */
  #define MPLS_TTL_MASK       0x000000ff
  #define MPLS_TTL_SHIFT      0
  
  #define MPLS_BOS_MASK       0x00000100
  #define MPLS_BOS_SHIFT      8
  
  #define MPLS_TC_MASK        0x00000e00
  #define MPLS_TC_SHIFT       9
  
  #define MPLS_LABEL_MASK     0xfffff000
  #define MPLS_LABEL_SHIFT    12
  
  #define MPLS_HLEN           4
  
  struct mpls_hdr {
      ovs_be32 mpls_lse;
  };
  BUILD_ASSERT_DECL(MPLS_HLEN == sizeof(struct mpls_hdr));
  
  /* Given a mpls label stack entry in network byte order
   * return mpls label in host byte order */
  static inline uint32_t
  mpls_lse_to_label(ovs_be32 mpls_lse)
  {
      return (ntohl(mpls_lse) & MPLS_LABEL_MASK) >> MPLS_LABEL_SHIFT;
  }
  
  /* Given a mpls label stack entry in network byte order
   * return mpls tc */
  static inline uint8_t
  mpls_lse_to_tc(ovs_be32 mpls_lse)
  {
      return (ntohl(mpls_lse) & MPLS_TC_MASK) >> MPLS_TC_SHIFT;
  }
  
  /* Given a mpls label stack entry in network byte order
   * return mpls ttl */
  static inline uint8_t
  mpls_lse_to_ttl(ovs_be32 mpls_lse)
  {
      return (ntohl(mpls_lse) & MPLS_TTL_MASK) >> MPLS_TTL_SHIFT;
  }
  
  /* Set TTL in mpls lse. */
  static inline void
  flow_set_mpls_lse_ttl(ovs_be32 *mpls_lse, uint8_t ttl)
  {
      *mpls_lse &= ~htonl(MPLS_TTL_MASK);
      *mpls_lse |= htonl(ttl << MPLS_TTL_SHIFT);
  }
  
  /* Given a mpls label stack entry in network byte order
   * return mpls BoS bit  */
  static inline uint8_t
  mpls_lse_to_bos(ovs_be32 mpls_lse)
  {
      return (mpls_lse & htonl(MPLS_BOS_MASK)) != 0;
  }
  
  #define IP_FMT "%"PRIu32".%"PRIu32".%"PRIu32".%"PRIu32
  #define IP_ARGS(ip)                             \
      ntohl(ip) >> 24,                            \
      (ntohl(ip) >> 16) & 0xff,                   \
      (ntohl(ip) >> 8) & 0xff,                    \
      ntohl(ip) & 0xff
  
  /* Example:
   *
   * char *string = "1 33.44.55.66 2";
   * ovs_be32 ip;
   * int a, b;
   *
   * if (sscanf(string, "%d"IP_SCAN_FMT"%d",
   *     &a, IP_SCAN_ARGS(&ip), &b) == 1 + IP_SCAN_COUNT + 1) {
   *     ...
   * }
   */
  #define IP_SCAN_FMT "%"SCNu8".%"SCNu8".%"SCNu8".%"SCNu8
  #define IP_SCAN_ARGS(ip)                                    \
          ((void) (ovs_be32) *(ip), &((uint8_t *) ip)[0]),    \
          &((uint8_t *) ip)[1],                               \
          &((uint8_t *) ip)[2],                               \
          &((uint8_t *) ip)[3]
  #define IP_SCAN_COUNT 4
  
  /* Returns true if 'netmask' is a CIDR netmask, that is, if it consists of N
   * high-order 1-bits and 32-N low-order 0-bits. */
  static inline bool
  ip_is_cidr(ovs_be32 netmask)
  {
      uint32_t x = ~ntohl(netmask);
      return !(x & (x + 1));
  }
  static inline bool
  ip_is_multicast(ovs_be32 ip)
  {
      return (ip & htonl(0xf0000000)) == htonl(0xe0000000);
  }
  int ip_count_cidr_bits(ovs_be32 netmask);
  void ip_format_masked(ovs_be32 ip, ovs_be32 mask, struct ds *);
  
  #define IP_VER(ip_ihl_ver) ((ip_ihl_ver) >> 4)
  #define IP_IHL(ip_ihl_ver) ((ip_ihl_ver) & 15)
  #define IP_IHL_VER(ihl, ver) (((ver) << 4) | (ihl))
  
  #ifndef IPPROTO_SCTP
  #define IPPROTO_SCTP 132
  #endif
  
  /* TOS fields. */
  #define IP_ECN_NOT_ECT 0x0
  #define IP_ECN_ECT_1 0x01
  #define IP_ECN_ECT_0 0x02
  #define IP_ECN_CE 0x03
  #define IP_ECN_MASK 0x03
  #define IP_DSCP_MASK 0xfc
  
  #define IP_VERSION 4
  
  #define IP_DONT_FRAGMENT  0x4000 /* Don't fragment. */
  #define IP_MORE_FRAGMENTS 0x2000 /* More fragments. */
  #define IP_FRAG_OFF_MASK  0x1fff /* Fragment offset. */
  #define IP_IS_FRAGMENT(ip_frag_off) \
          ((ip_frag_off) & htons(IP_MORE_FRAGMENTS | IP_FRAG_OFF_MASK))
  
  #define IP_HEADER_LEN 20
  struct ip_header {
      uint8_t ip_ihl_ver;
      uint8_t ip_tos;
      ovs_be16 ip_tot_len;
      ovs_be16 ip_id;
      ovs_be16 ip_frag_off;
      uint8_t ip_ttl;
      uint8_t ip_proto;
      ovs_be16 ip_csum;
      ovs_16aligned_be32 ip_src;
      ovs_16aligned_be32 ip_dst;
  };
  BUILD_ASSERT_DECL(IP_HEADER_LEN == sizeof(struct ip_header));
  
  #define ICMP_HEADER_LEN 8
  struct icmp_header {
      uint8_t icmp_type;
      uint8_t icmp_code;
      ovs_be16 icmp_csum;
      union {
          struct {
              ovs_be16 id;
              ovs_be16 seq;
          } echo;
          struct {
              ovs_be16 empty;
              ovs_be16 mtu;
          } frag;
          ovs_16aligned_be32 gateway;
      } icmp_fields;
      uint8_t icmp_data[0];
  };
  BUILD_ASSERT_DECL(ICMP_HEADER_LEN == sizeof(struct icmp_header));
  
  #define SCTP_HEADER_LEN 12
  struct sctp_header {
      ovs_be16 sctp_src;
      ovs_be16 sctp_dst;
      ovs_be32 sctp_vtag;
      ovs_be32 sctp_csum;
  };
  BUILD_ASSERT_DECL(SCTP_HEADER_LEN == sizeof(struct sctp_header));
  
  #define UDP_HEADER_LEN 8
  struct udp_header {
      ovs_be16 udp_src;
      ovs_be16 udp_dst;
      ovs_be16 udp_len;
      ovs_be16 udp_csum;
  };
  BUILD_ASSERT_DECL(UDP_HEADER_LEN == sizeof(struct udp_header));
  
  #define TCP_FIN 0x01
  #define TCP_SYN 0x02
  #define TCP_RST 0x04
  #define TCP_PSH 0x08
  #define TCP_ACK 0x10
  #define TCP_URG 0x20
  
  #define TCP_CTL(flags, offset) (htons((flags) | ((offset) << 12)))
  #define TCP_FLAGS(tcp_ctl) (ntohs(tcp_ctl) & 0x003f)
  #define TCP_OFFSET(tcp_ctl) (ntohs(tcp_ctl) >> 12)
  
  #define TCP_HEADER_LEN 20
  struct tcp_header {
      ovs_be16 tcp_src;
      ovs_be16 tcp_dst;
      ovs_16aligned_be32 tcp_seq;
      ovs_16aligned_be32 tcp_ack;
      ovs_be16 tcp_ctl;
      ovs_be16 tcp_winsz;
      ovs_be16 tcp_csum;
      ovs_be16 tcp_urg;
  };
  BUILD_ASSERT_DECL(TCP_HEADER_LEN == sizeof(struct tcp_header));
  
  #define ARP_HRD_ETHERNET 1
  #define ARP_PRO_IP 0x0800
  #define ARP_OP_REQUEST 1
  #define ARP_OP_REPLY 2
  #define ARP_OP_RARP 3
  
  #define ARP_ETH_HEADER_LEN 28
  struct arp_eth_header {
      /* Generic members. */
      ovs_be16 ar_hrd;           /* Hardware type. */
      ovs_be16 ar_pro;           /* Protocol type. */
      uint8_t ar_hln;            /* Hardware address length. */
      uint8_t ar_pln;            /* Protocol address length. */
      ovs_be16 ar_op;            /* Opcode. */
  
      /* Ethernet+IPv4 specific members. */
      uint8_t ar_sha[ETH_ADDR_LEN]; /* Sender hardware address. */
      ovs_16aligned_be32 ar_spa;           /* Sender protocol address. */
      uint8_t ar_tha[ETH_ADDR_LEN]; /* Target hardware address. */
      ovs_16aligned_be32 ar_tpa;           /* Target protocol address. */
  };
  BUILD_ASSERT_DECL(ARP_ETH_HEADER_LEN == sizeof(struct arp_eth_header));
  
  /* Like struct in6_addr, but whereas that struct requires 32-bit alignment on
   * most implementations, this one only requires 16-bit alignment. */
  union ovs_16aligned_in6_addr {
      ovs_be16 be16[8];
      ovs_16aligned_be32 be32[4];
  };
  
  /* Like struct in6_hdr, but whereas that struct requires 32-bit alignment, this
   * one only requires 16-bit alignment. */
  struct ovs_16aligned_ip6_hdr {
      union {
          struct ovs_16aligned_ip6_hdrctl {
              ovs_16aligned_be32 ip6_un1_flow;
              ovs_be16 ip6_un1_plen;
              uint8_t ip6_un1_nxt;
              uint8_t ip6_un1_hlim;
          } ip6_un1;
          uint8_t ip6_un2_vfc;
      } ip6_ctlun;
      union ovs_16aligned_in6_addr ip6_src;
      union ovs_16aligned_in6_addr ip6_dst;
  };
  
  /* Like struct in6_frag, but whereas that struct requires 32-bit alignment,
   * this one only requires 16-bit alignment. */
  struct ovs_16aligned_ip6_frag {
      uint8_t ip6f_nxt;
      uint8_t ip6f_reserved;
      ovs_be16 ip6f_offlg;
      ovs_16aligned_be32 ip6f_ident;
  };
  
  /* The IPv6 flow label is in the lower 20 bits of the first 32-bit word. */
  #define IPV6_LABEL_MASK 0x000fffff
  
  /* Example:
   *
   * char *string = "1 ::1 2";
   * char ipv6_s[IPV6_SCAN_LEN + 1];
   * struct in6_addr ipv6;
   *
   * if (sscanf(string, "%d"IPV6_SCAN_FMT"%d", &a, ipv6_s, &b) == 3
   *     && inet_pton(AF_INET6, ipv6_s, &ipv6) == 1) {
   *     ...
   * }
   */
  #define IPV6_SCAN_FMT "%46[0123456789abcdefABCDEF:.]"
  #define IPV6_SCAN_LEN 46
  
  extern const struct in6_addr in6addr_exact;
  #define IN6ADDR_EXACT_INIT { { { 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff, \
                                   0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff } } }
  
  static inline bool ipv6_addr_equals(const struct in6_addr *a,
                                      const struct in6_addr *b)
  {
  #ifdef IN6_ARE_ADDR_EQUAL
      return IN6_ARE_ADDR_EQUAL(a, b);
  #else
      return !memcmp(a, b, sizeof(*a));
  #endif
  }
  
  static inline bool ipv6_mask_is_any(const struct in6_addr *mask) {
      return ipv6_addr_equals(mask, &in6addr_any);
  }
  
  static inline bool ipv6_mask_is_exact(const struct in6_addr *mask) {
      return ipv6_addr_equals(mask, &in6addr_exact);
  }
  
  static inline bool dl_type_is_ip_any(ovs_be16 dl_type)
  {
      return dl_type == htons(ETH_TYPE_IP)
          || dl_type == htons(ETH_TYPE_IPV6);
  }
  
  static inline bool is_ip_any(const struct flow *flow)
  {
      return dl_type_is_ip_any(flow->dl_type);
  }
  
  void format_ipv6_addr(char *addr_str, const struct in6_addr *addr);
  void print_ipv6_addr(struct ds *string, const struct in6_addr *addr);
  void print_ipv6_masked(struct ds *string, const struct in6_addr *addr,
                         const struct in6_addr *mask);
  struct in6_addr ipv6_addr_bitand(const struct in6_addr *src,
                                   const struct in6_addr *mask);
  struct in6_addr ipv6_create_mask(int mask);
  int ipv6_count_cidr_bits(const struct in6_addr *netmask);
  bool ipv6_is_cidr(const struct in6_addr *netmask);
  
  void *eth_compose(struct ofpbuf *, const uint8_t eth_dst[ETH_ADDR_LEN],
                    const uint8_t eth_src[ETH_ADDR_LEN], uint16_t eth_type,
                    size_t size);
  void *snap_compose(struct ofpbuf *, const uint8_t eth_dst[ETH_ADDR_LEN],
                     const uint8_t eth_src[ETH_ADDR_LEN],
                     unsigned int oui, uint16_t snap_type, size_t size);
  void packet_set_ipv4(struct ofpbuf *, ovs_be32 src, ovs_be32 dst, uint8_t tos,
                       uint8_t ttl);
  void packet_set_ipv6(struct ofpbuf *, uint8_t proto, const ovs_be32 src[4],
                       const ovs_be32 dst[4], uint8_t tc,
                       ovs_be32 fl, uint8_t hlmit);
  void packet_set_tcp_port(struct ofpbuf *, ovs_be16 src, ovs_be16 dst);
  void packet_set_udp_port(struct ofpbuf *, ovs_be16 src, ovs_be16 dst);
  void packet_set_sctp_port(struct ofpbuf *, ovs_be16 src, ovs_be16 dst);
  
  uint8_t packet_get_tcp_flags(const struct ofpbuf *, const struct flow *);
  void packet_format_tcp_flags(struct ds *, uint8_t);
  
  #endif /* packets.h */
  