text: /*
   * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2017, 2019 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.
   */
  #include <config.h>
  #include <sys/types.h>
  #include "flow.h"
  #include <errno.h>
  #include <inttypes.h>
  #include <limits.h>
  #include <net/if.h>
  #include <netinet/in.h>
  #include <netinet/icmp6.h>
  #include <netinet/ip6.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  #include "byte-order.h"
  #include "colors.h"
  #include "coverage.h"
  #include "csum.h"
  #include "openvswitch/dynamic-string.h"
  #include "hash.h"
  #include "jhash.h"
  #include "openvswitch/match.h"
  #include "dp-packet.h"
  #include "openflow/openflow.h"
  #include "packets.h"
  #include "odp-util.h"
  #include "random.h"
  #include "unaligned.h"
  #include "util.h"
  #include "openvswitch/nsh.h"
  #include "ovs-router.h"
  #include "lib/netdev-provider.h"
  
  COVERAGE_DEFINE(flow_extract);
  COVERAGE_DEFINE(miniflow_malloc);
  
  /* U64 indices for segmented flow classification. */
  const uint8_t flow_segment_u64s[4] = {
      FLOW_SEGMENT_1_ENDS_AT / sizeof(uint64_t),
      FLOW_SEGMENT_2_ENDS_AT / sizeof(uint64_t),
      FLOW_SEGMENT_3_ENDS_AT / sizeof(uint64_t),
      FLOW_U64S
  };
  
  int flow_vlan_limit = FLOW_MAX_VLAN_HEADERS;
  
  /* Asserts that field 'f1' follows immediately after 'f0' in struct flow,
   * without any intervening padding. */
  #define ASSERT_SEQUENTIAL(f0, f1)                       \
      BUILD_ASSERT_DECL(offsetof(struct flow, f0)         \
                        + MEMBER_SIZEOF(struct flow, f0)  \
                        == offsetof(struct flow, f1))
  
  /* Asserts that fields 'f0' and 'f1' are in the same 32-bit aligned word within
   * struct flow. */
  #define ASSERT_SAME_WORD(f0, f1)                        \
      BUILD_ASSERT_DECL(offsetof(struct flow, f0) / 4     \
                        == offsetof(struct flow, f1) / 4)
  
  /* Asserts that 'f0' and 'f1' are both sequential and within the same 32-bit
   * aligned word in struct flow. */
  #define ASSERT_SEQUENTIAL_SAME_WORD(f0, f1)     \
      ASSERT_SEQUENTIAL(f0, f1);                  \
      ASSERT_SAME_WORD(f0, f1)
  
  /* miniflow_extract() assumes the following to be true to optimize the
   * extraction process. */
  ASSERT_SEQUENTIAL_SAME_WORD(nw_frag, nw_tos);
  ASSERT_SEQUENTIAL_SAME_WORD(nw_tos, nw_ttl);
  ASSERT_SEQUENTIAL_SAME_WORD(nw_ttl, nw_proto);
  
  /* TCP flags in the middle of a BE64, zeroes in the other half. */
  BUILD_ASSERT_DECL(offsetof(struct flow, tcp_flags) % 8 == 4);
  
  #if WORDS_BIGENDIAN
  #define TCP_FLAGS_BE32(tcp_ctl) ((OVS_FORCE ovs_be32)TCP_FLAGS_BE16(tcp_ctl) \
                                   << 16)
  #else
  #define TCP_FLAGS_BE32(tcp_ctl) ((OVS_FORCE ovs_be32)TCP_FLAGS_BE16(tcp_ctl))
  #endif
  
  ASSERT_SEQUENTIAL_SAME_WORD(tp_src, tp_dst);
  
  /* Removes 'size' bytes from the head end of '*datap', of size '*sizep', which
   * must contain at least 'size' bytes of data.  Returns the first byte of data
   * removed. */
  static inline const void *
  data_pull(const void **datap, size_t *sizep, size_t size)
  {
      const char *data = *datap;
      *datap = data + size;
      *sizep -= size;
      return data;
  }
  
  /* If '*datap' has at least 'size' bytes of data, removes that many bytes from
   * the head end of '*datap' and returns the first byte removed.  Otherwise,
   * returns a null pointer without modifying '*datap'. */
  static inline const void *
  data_try_pull(const void **datap, size_t *sizep, size_t size)
  {
      return OVS_LIKELY(*sizep >= size) ? data_pull(datap, sizep, size) : NULL;
  }
  
  /* Context for pushing data to a miniflow. */
  struct mf_ctx {
      struct flowmap map;
      uint64_t *data;
      uint64_t * const end;
  };
  
  /* miniflow_push_* macros allow filling in a miniflow data values in order.
   * Assertions are needed only when the layout of the struct flow is modified.
   * 'ofs' is a compile-time constant, which allows most of the code be optimized
   * away.  Some GCC versions gave warnings on ALWAYS_INLINE, so these are
   * defined as macros. */
  
  #if (FLOW_WC_SEQ != 41)
  #define MINIFLOW_ASSERT(X) ovs_assert(X)
  BUILD_MESSAGE("FLOW_WC_SEQ changed: miniflow_extract() will have runtime "
                 "assertions enabled. Consider updating FLOW_WC_SEQ after "
                 "testing")
  #else
  #define MINIFLOW_ASSERT(X)
  #endif
  
  /* True if 'IDX' and higher bits are not set. */
  #define ASSERT_FLOWMAP_NOT_SET(FM, IDX)                                 \
  {                                                                       \
      MINIFLOW_ASSERT(!((FM)->bits[(IDX) / MAP_T_BITS] &                  \
                        (MAP_MAX << ((IDX) % MAP_T_BITS))));              \
      for (size_t i = (IDX) / MAP_T_BITS + 1; i < FLOWMAP_UNITS; i++) {   \
          MINIFLOW_ASSERT(!(FM)->bits[i]);                                \
      }                                                                   \
  }
  
  #define miniflow_set_map(MF, OFS)            \
      {                                        \
      ASSERT_FLOWMAP_NOT_SET(&MF.map, (OFS));  \
      flowmap_set(&MF.map, (OFS), 1);          \
  }
  
  #define miniflow_assert_in_map(MF, OFS)              \
      MINIFLOW_ASSERT(flowmap_is_set(&MF.map, (OFS))); \
      ASSERT_FLOWMAP_NOT_SET(&MF.map, (OFS) + 1)
  
  #define miniflow_push_uint64_(MF, OFS, VALUE)              \
  {                                                          \
      MINIFLOW_ASSERT(MF.data < MF.end && (OFS) % 8 == 0);   \
      *MF.data++ = VALUE;                                    \
      miniflow_set_map(MF, OFS / 8);                         \
  }
  
  #define miniflow_push_be64_(MF, OFS, VALUE)                     \
      miniflow_push_uint64_(MF, OFS, (OVS_FORCE uint64_t)(VALUE))
  
  #define miniflow_push_uint32_(MF, OFS, VALUE)   \
      {                                           \
      MINIFLOW_ASSERT(MF.data < MF.end);          \
                                                  \
      if ((OFS) % 8 == 0) {                       \
          miniflow_set_map(MF, OFS / 8);          \
          *(uint32_t *)MF.data = VALUE;           \
      } else if ((OFS) % 8 == 4) {                \
          miniflow_assert_in_map(MF, OFS / 8);    \
          *((uint32_t *)MF.data + 1) = VALUE;     \
          MF.data++;                              \
      }                                           \
  }
  
  #define miniflow_push_be32_(MF, OFS, VALUE)                     \
      miniflow_push_uint32_(MF, OFS, (OVS_FORCE uint32_t)(VALUE))
  
  #define miniflow_push_uint16_(MF, OFS, VALUE)   \
  {                                               \
      MINIFLOW_ASSERT(MF.data < MF.end);          \
                                                  \
      if ((OFS) % 8 == 0) {                       \
          miniflow_set_map(MF, OFS / 8);          \
          *(uint16_t *)MF.data = VALUE;           \
      } else if ((OFS) % 8 == 2) {                \
          miniflow_assert_in_map(MF, OFS / 8);    \
          *((uint16_t *)MF.data + 1) = VALUE;     \
      } else if ((OFS) % 8 == 4) {                \
          miniflow_assert_in_map(MF, OFS / 8);    \
          *((uint16_t *)MF.data + 2) = VALUE;     \
      } else if ((OFS) % 8 == 6) {                \
          miniflow_assert_in_map(MF, OFS / 8);    \
          *((uint16_t *)MF.data + 3) = VALUE;     \
          MF.data++;                              \
      }                                           \
  }
  
  #define miniflow_push_uint8_(MF, OFS, VALUE)            \
  {                                                       \
      MINIFLOW_ASSERT(MF.data < MF.end);                  \
                                                          \
      if ((OFS) % 8 == 0) {                               \
          miniflow_set_map(MF, OFS / 8);                  \
          *(uint8_t *)MF.data = VALUE;                    \
      } else if ((OFS) % 8 == 7) {                        \
          miniflow_assert_in_map(MF, OFS / 8);            \
          *((uint8_t *)MF.data + 7) = VALUE;              \
          MF.data++;                                      \
      } else {                                            \
          miniflow_assert_in_map(MF, OFS / 8);            \
          *((uint8_t *)MF.data + ((OFS) % 8)) = VALUE;    \
      }                                                   \
  }
  
  #define miniflow_pad_to_64_(MF, OFS)                            \
  {                                                               \
      MINIFLOW_ASSERT((OFS) % 8 != 0);                            \
      miniflow_assert_in_map(MF, OFS / 8);                        \
                                                                  \
      memset((uint8_t *)MF.data + (OFS) % 8, 0, 8 - (OFS) % 8);   \
      MF.data++;                                                  \
  }
  
  #define miniflow_pad_from_64_(MF, OFS)                          \
  {                                                               \
      MINIFLOW_ASSERT(MF.data < MF.end);                          \
                                                                  \
      MINIFLOW_ASSERT((OFS) % 8 != 0);                            \
      miniflow_set_map(MF, OFS / 8);                              \
                                                                  \
      memset((uint8_t *)MF.data, 0, (OFS) % 8);                   \
  }
  
  #define miniflow_push_be16_(MF, OFS, VALUE)                     \
      miniflow_push_uint16_(MF, OFS, (OVS_FORCE uint16_t)VALUE);
  
  #define miniflow_push_be8_(MF, OFS, VALUE)                     \
      miniflow_push_uint8_(MF, OFS, (OVS_FORCE uint8_t)VALUE);
  
  #define miniflow_set_maps(MF, OFS, N_WORDS)                     \
  {                                                               \
      size_t ofs = (OFS);                                         \
      size_t n_words = (N_WORDS);                                 \
                                                                  \
      MINIFLOW_ASSERT(n_words && MF.data + n_words <= MF.end);    \
      ASSERT_FLOWMAP_NOT_SET(&MF.map, ofs);                       \
      flowmap_set(&MF.map, ofs, n_words);                         \
  }
  
  /* Data at 'valuep' may be unaligned. */
  #define miniflow_push_words_(MF, OFS, VALUEP, N_WORDS)          \
  {                                                               \
      MINIFLOW_ASSERT((OFS) % 8 == 0);                            \
      miniflow_set_maps(MF, (OFS) / 8, (N_WORDS));                \
      memcpy(MF.data, (VALUEP), (N_WORDS) * sizeof *MF.data);     \
      MF.data += (N_WORDS);                                       \
  }
  
  /* Push 32-bit words padded to 64-bits. */
  #define miniflow_push_words_32_(MF, OFS, VALUEP, N_WORDS)               \
  {                                                                       \
      miniflow_set_maps(MF, (OFS) / 8, DIV_ROUND_UP(N_WORDS, 2));         \
      memcpy(MF.data, (VALUEP), (N_WORDS) * sizeof(uint32_t));            \
      MF.data += DIV_ROUND_UP(N_WORDS, 2);                                \
      if ((N_WORDS) & 1) {                                                \
          *((uint32_t *)MF.data - 1) = 0;                                 \
      }                                                                   \
  }
  
  /* Data at 'valuep' may be unaligned. */
  /* MACs start 64-aligned, and must be followed by other data or padding. */
  #define miniflow_push_macs_(MF, OFS, VALUEP)                    \
  {                                                               \
      miniflow_set_maps(MF, (OFS) / 8, 2);                        \
      memcpy(MF.data, (VALUEP), 2 * ETH_ADDR_LEN);                \
      MF.data += 1;                   /* First word only. */      \
  }
  
  #define miniflow_push_uint32(MF, FIELD, VALUE)                      \
      miniflow_push_uint32_(MF, offsetof(struct flow, FIELD), VALUE)
  
  #define miniflow_push_be32(MF, FIELD, VALUE)                        \
      miniflow_push_be32_(MF, offsetof(struct flow, FIELD), VALUE)
  
  #define miniflow_push_uint16(MF, FIELD, VALUE)                      \
      miniflow_push_uint16_(MF, offsetof(struct flow, FIELD), VALUE)
  
  #define miniflow_push_be16(MF, FIELD, VALUE)                        \
      miniflow_push_be16_(MF, offsetof(struct flow, FIELD), VALUE)
  
  #define miniflow_push_uint8(MF, FIELD, VALUE)                      \
      miniflow_push_uint8_(MF, offsetof(struct flow, FIELD), VALUE)
  
  #define miniflow_pad_to_64(MF, FIELD)                       \
      miniflow_pad_to_64_(MF, OFFSETOFEND(struct flow, FIELD))
  
  #define miniflow_pad_from_64(MF, FIELD)                       \
      miniflow_pad_from_64_(MF, offsetof(struct flow, FIELD))
  
  #define miniflow_push_words(MF, FIELD, VALUEP, N_WORDS)                 \
      miniflow_push_words_(MF, offsetof(struct flow, FIELD), VALUEP, N_WORDS)
  
  #define miniflow_push_words_32(MF, FIELD, VALUEP, N_WORDS)              \
      miniflow_push_words_32_(MF, offsetof(struct flow, FIELD), VALUEP, N_WORDS)
  
  #define miniflow_push_macs(MF, FIELD, VALUEP)                       \
      miniflow_push_macs_(MF, offsetof(struct flow, FIELD), VALUEP)
  
  /* Return the pointer to the miniflow data when called BEFORE the corresponding
   * push. */
  #define miniflow_pointer(MF, FIELD)                                     \
      (void *)((uint8_t *)MF.data + ((offsetof(struct flow, FIELD)) % 8))
  
  /* Pulls the MPLS headers at '*datap' and returns the count of them. */
  static inline int
  parse_mpls(const void **datap, size_t *sizep)
  {
      const struct mpls_hdr *mh;
      int count = 0;
  
      while ((mh = data_try_pull(datap, sizep, sizeof *mh))) {
          count++;
          if (mh->mpls_lse.lo & htons(1 << MPLS_BOS_SHIFT)) {
              break;
          }
      }
      return MIN(count, FLOW_MAX_MPLS_LABELS);
  }
  
  /* passed vlan_hdrs arg must be at least size FLOW_MAX_VLAN_HEADERS. */
  static inline ALWAYS_INLINE size_t
  parse_vlan(const void **datap, size_t *sizep, union flow_vlan_hdr *vlan_hdrs)
  {
      const ovs_be16 *eth_type;
  
      data_pull(datap, sizep, ETH_ADDR_LEN * 2);
  
      eth_type = *datap;
  
      size_t n;
      for (n = 0; eth_type_vlan(*eth_type) && n < flow_vlan_limit; n++) {
          if (OVS_UNLIKELY(*sizep < sizeof(ovs_be32) + sizeof(ovs_be16))) {
              break;
          }
  
          memset(vlan_hdrs + n, 0, sizeof(union flow_vlan_hdr));
          const ovs_16aligned_be32 *qp = data_pull(datap, sizep, sizeof *qp);
          vlan_hdrs[n].qtag = get_16aligned_be32(qp);
          vlan_hdrs[n].tci |= htons(VLAN_CFI);
          eth_type = *datap;
      }
      return n;
  }
  
  static inline ALWAYS_INLINE ovs_be16
  parse_ethertype(const void **datap, size_t *sizep)
  {
      const struct llc_snap_header *llc;
      ovs_be16 proto;
  
      proto = *(ovs_be16 *) data_pull(datap, sizep, sizeof proto);
      if (OVS_LIKELY(ntohs(proto) >= ETH_TYPE_MIN)) {
          return proto;
      }
  
      if (OVS_UNLIKELY(*sizep < sizeof *llc)) {
          return htons(FLOW_DL_TYPE_NONE);
      }
  
      llc = *datap;
      if (OVS_UNLIKELY(llc->llc.llc_dsap != LLC_DSAP_SNAP
                       || llc->llc.llc_ssap != LLC_SSAP_SNAP
                       || llc->llc.llc_cntl != LLC_CNTL_SNAP
                       || memcmp(llc->snap.snap_org, SNAP_ORG_ETHERNET,
                                 sizeof llc->snap.snap_org))) {
          return htons(FLOW_DL_TYPE_NONE);
      }
  
      data_pull(datap, sizep, sizeof *llc);
  
      if (OVS_LIKELY(ntohs(llc->snap.snap_type) >= ETH_TYPE_MIN)) {
          return llc->snap.snap_type;
      }
  
      return htons(FLOW_DL_TYPE_NONE);
  }
  
  /* Returns 'true' if the packet is an ND packet. In that case the '*nd_target'
   * and 'arp_buf[]' are filled in.  If the packet is not an ND packet, 'false'
   * is returned and no values are filled in on '*nd_target' or 'arp_buf[]'. */
  static inline bool
  parse_icmpv6(const void **datap, size_t *sizep,
               const struct icmp6_data_header *icmp6,
               ovs_be32 *rso_flags, const struct in6_addr **nd_target,
               struct eth_addr arp_buf[2], uint8_t *opt_type)
  {
      if (icmp6->icmp6_base.icmp6_code != 0 ||
          (icmp6->icmp6_base.icmp6_type != ND_NEIGHBOR_SOLICIT &&
           icmp6->icmp6_base.icmp6_type != ND_NEIGHBOR_ADVERT)) {
          return false;
      }
  
      arp_buf[0] = eth_addr_zero;
      arp_buf[1] = eth_addr_zero;
      *opt_type = 0;
  
      *rso_flags = get_16aligned_be32(icmp6->icmp6_data.be32);
  
      *nd_target = data_try_pull(datap, sizep, sizeof **nd_target);
      if (OVS_UNLIKELY(!*nd_target)) {
          return true;
      }
  
      while (*sizep >= 8) {
          /* The minimum size of an option is 8 bytes, which also is
           * the size of Ethernet link-layer options. */
          const struct ovs_nd_lla_opt *lla_opt = *datap;
          int opt_len = lla_opt->len * ND_LLA_OPT_LEN;
  
          if (!opt_len || opt_len > *sizep) {
              return true;
          }
  
          /* Store the link layer address if the appropriate option is
           * provided.  It is considered an error if the same link
           * layer option is specified twice. */
          if (lla_opt->type == ND_OPT_SOURCE_LINKADDR && opt_len == 8) {
              if (OVS_LIKELY(eth_addr_is_zero(arp_buf[0]))) {
                  arp_buf[0] = lla_opt->mac;
                  /* We use only first option type present in ND packet. */
                  if (*opt_type == 0) {
                      *opt_type = lla_opt->type;
                  }
              } else {
                  goto invalid;
              }
          } else if (lla_opt->type == ND_OPT_TARGET_LINKADDR && opt_len == 8) {
              if (OVS_LIKELY(eth_addr_is_zero(arp_buf[1]))) {
                  arp_buf[1] = lla_opt->mac;
                  /* We use only first option type present in ND packet. */
                  if (*opt_type == 0) {
                      *opt_type = lla_opt->type;
                  }
              } else {
                  goto invalid;
              }
          }
  
          if (OVS_UNLIKELY(!data_try_pull(datap, sizep, opt_len))) {
              return true;
          }
      }
      return true;
  
  invalid:
      *nd_target = NULL;
      arp_buf[0] = eth_addr_zero;
      arp_buf[1] = eth_addr_zero;
      return true;
  }
  
  static inline bool
  parse_ipv6_ext_hdrs__(const void **datap, size_t *sizep, uint8_t *nw_proto,
                        uint8_t *nw_frag,
                        const struct ovs_16aligned_ip6_frag **frag_hdr)
  {
      *frag_hdr = NULL;
      while (1) {
          if (OVS_LIKELY((*nw_proto != IPPROTO_HOPOPTS)
                         && (*nw_proto != IPPROTO_ROUTING)
                         && (*nw_proto != IPPROTO_DSTOPTS)
                         && (*nw_proto != IPPROTO_AH)
                         && (*nw_proto != IPPROTO_FRAGMENT))) {
              /* It's either a terminal header (e.g., TCP, UDP) or one we
               * don't understand.  In either case, we're done with the
               * packet, so use it to fill in 'nw_proto'. */
              return true;
          }
  
          /* We only verify that at least 8 bytes of the next header are
           * available, but many of these headers are longer.  Ensure that
           * accesses within the extension header are within those first 8
           * bytes. All extension headers are required to be at least 8
           * bytes. */
          if (OVS_UNLIKELY(*sizep < 8)) {
              return false;
          }
  
          if ((*nw_proto == IPPROTO_HOPOPTS)
              || (*nw_proto == IPPROTO_ROUTING)
              || (*nw_proto == IPPROTO_DSTOPTS)) {
              /* These headers, while different, have the fields we care
               * about in the same location and with the same
               * interpretation. */
              const struct ip6_ext *ext_hdr = *datap;
              *nw_proto = ext_hdr->ip6e_nxt;
              if (OVS_UNLIKELY(!data_try_pull(datap, sizep,
                                              (ext_hdr->ip6e_len + 1) * 8))) {
                  return false;
              }
          } else if (*nw_proto == IPPROTO_AH) {
              /* A standard AH definition isn't available, but the fields
               * we care about are in the same location as the generic
               * option header--only the header length is calculated
               * differently. */
              const struct ip6_ext *ext_hdr = *datap;
              *nw_proto = ext_hdr->ip6e_nxt;
              if (OVS_UNLIKELY(!data_try_pull(datap, sizep,
                                              (ext_hdr->ip6e_len + 2) * 4))) {
                  return false;
              }
          } else if (*nw_proto == IPPROTO_FRAGMENT) {
              *frag_hdr = *datap;
  
              *nw_proto = (*frag_hdr)->ip6f_nxt;
              if (!data_try_pull(datap, sizep, sizeof **frag_hdr)) {
                  return false;
              }
  
              /* We only process the first fragment. */
              if ((*frag_hdr)->ip6f_offlg != htons(0)) {
                  *nw_frag = FLOW_NW_FRAG_ANY;
                  if (((*frag_hdr)->ip6f_offlg & IP6F_OFF_MASK) != htons(0)) {
                      *nw_frag |= FLOW_NW_FRAG_LATER;
                      *nw_proto = IPPROTO_FRAGMENT;
                      return true;
                  }
              }
          }
      }
  }
  
  /* Parses IPv6 extension headers until a terminal header (or header we
   * don't understand) is found.  'datap' points to the first extension
   * header and advances as parsing occurs; 'sizep' is the remaining size
   * and is decreased accordingly.  'nw_proto' starts as the first
   * extension header to process and is updated as the extension headers
   * are parsed.
   *
   * If a fragment header is found, '*frag_hdr' is set to the fragment
   * header and otherwise set to NULL.  If it is the first fragment,
   * extension header parsing otherwise continues as usual.  If it's not
   * the first fragment, 'nw_proto' is set to IPPROTO_FRAGMENT and 'nw_frag'
   * has FLOW_NW_FRAG_LATER set.  Both first and later fragments have
   * FLOW_NW_FRAG_ANY set in 'nw_frag'.
   *
   * A return value of false indicates that there was a problem parsing
   * the extension headers.*/
  bool
  parse_ipv6_ext_hdrs(const void **datap, size_t *sizep, uint8_t *nw_proto,
                      uint8_t *nw_frag,
                      const struct ovs_16aligned_ip6_frag **frag_hdr)
  {
      return parse_ipv6_ext_hdrs__(datap, sizep, nw_proto, nw_frag,
                                   frag_hdr);
  }
  
  bool
  parse_nsh(const void **datap, size_t *sizep, struct ovs_key_nsh *key)
  {
      const struct nsh_hdr *nsh = (const struct nsh_hdr *) *datap;
      uint8_t version, length, flags, ttl;
  
      /* Check if it is long enough for NSH header, doesn't support
       * MD type 2 yet
       */
      if (OVS_UNLIKELY(*sizep < NSH_BASE_HDR_LEN)) {
          return false;
      }
  
      version = nsh_get_ver(nsh);
      flags = nsh_get_flags(nsh);
      length = nsh_hdr_len(nsh);
      ttl = nsh_get_ttl(nsh);
  
      if (OVS_UNLIKELY(length > *sizep || version != 0)) {
          return false;
      }
  
      key->flags = flags;
      key->ttl = ttl;
      key->mdtype = nsh->md_type;
      key->np = nsh->next_proto;
      key->path_hdr = nsh_get_path_hdr(nsh);
  
      switch (key->mdtype) {
          case NSH_M_TYPE1:
              if (length != NSH_M_TYPE1_LEN) {
                  return false;
              }
              for (size_t i = 0; i < 4; i++) {
                  key->context[i] = get_16aligned_be32(&nsh->md1.context[i]);
              }
              break;
          case NSH_M_TYPE2:
              /* Don't support MD type 2 metedata parsing yet */
              if (length < NSH_BASE_HDR_LEN) {
                  return false;
              }
  
              memset(key->context, 0, sizeof(key->context));
              break;
          default:
              /* We don't parse other context headers yet. */
              memset(key->context, 0, sizeof(key->context));
              break;
      }
  
      data_pull(datap, sizep, length);
  
      return true;
  }
  
  /* This does the same thing as miniflow_extract() with a full-size 'flow' as
   * the destination. */
  void
  flow_extract(struct dp_packet *packet, struct flow *flow)
  {
      struct {
          struct miniflow mf;
          uint64_t buf[FLOW_U64S];
      } m;
  
      COVERAGE_INC(flow_extract);
  
      miniflow_extract(packet, &m.mf);
      miniflow_expand(&m.mf, flow);
  }
  
  static inline bool
  ipv4_sanity_check(const struct ip_header *nh, size_t size,
                    int *ip_lenp, uint16_t *tot_lenp)
  {
      int ip_len;
      uint16_t tot_len;
  
      if (OVS_UNLIKELY(size < IP_HEADER_LEN)) {
          return false;
      }
      ip_len = IP_IHL(nh->ip_ihl_ver) * 4;
  
      if (OVS_UNLIKELY(ip_len < IP_HEADER_LEN || size < ip_len)) {
          return false;
      }
  
      tot_len = ntohs(nh->ip_tot_len);
      if (OVS_UNLIKELY(tot_len > size || ip_len > tot_len ||
                  size - tot_len > UINT16_MAX)) {
          return false;
      }
  
      *ip_lenp = ip_len;
      *tot_lenp = tot_len;
  
      return true;
  }
  
  static inline uint8_t
  ipv4_get_nw_frag(const struct ip_header *nh)
  {
      uint8_t nw_frag = 0;
  
      if (OVS_UNLIKELY(IP_IS_FRAGMENT(nh->ip_frag_off))) {
          nw_frag = FLOW_NW_FRAG_ANY;
          if (nh->ip_frag_off & htons(IP_FRAG_OFF_MASK)) {
              nw_frag |= FLOW_NW_FRAG_LATER;
          }
      }
  
      return nw_frag;
  }
  
  static inline bool
  ipv6_sanity_check(const struct ovs_16aligned_ip6_hdr *nh, size_t size)
  {
      uint16_t plen;
  
      if (OVS_UNLIKELY(size < sizeof *nh)) {
          return false;
      }
  
      plen = ntohs(nh->ip6_plen);
      if (OVS_UNLIKELY(plen + IPV6_HEADER_LEN > size)) {
          return false;
      }
  
      if (OVS_UNLIKELY(size - (plen + IPV6_HEADER_LEN) > UINT16_MAX)) {
          return false;
      }
  
      return true;
  }
  
  /* Initializes 'dst' from 'packet' and 'md', taking the packet type into
   * account.  'dst' must have enough space for FLOW_U64S * 8 bytes.
   *
   * Initializes the layer offsets as follows:
   *
   *    - packet->l2_5_ofs to the
   *          * the start of the MPLS shim header. Can be zero, if the
   *            packet is of type (OFPHTN_ETHERTYPE, ETH_TYPE_MPLS).
   *          * UINT16_MAX when there is no MPLS shim header.
   *
   *    - packet->l3_ofs is set to
   *          * zero if the packet_type is in name space OFPHTN_ETHERTYPE
   *            and there is no MPLS shim header.
   *          * just past the Ethernet header, or just past the vlan_header if
   *            one is present, to the first byte of the payload of the
   *            Ethernet frame if the packet type is Ethernet and there is
   *            no MPLS shim header.
   *          * just past the MPLS label stack to the first byte of the MPLS
   *            payload if there is at least one MPLS shim header.
   *          * UINT16_MAX if the packet type is Ethernet and the frame is
   *            too short to contain an Ethernet header.
   *
   *    - packet->l4_ofs is set to just past the IPv4 or IPv6 header, if one is
   *      present and the packet has at least the content used for the fields
   *      of interest for the flow, otherwise UINT16_MAX.
   */
  void
  miniflow_extract(struct dp_packet *packet, struct miniflow *dst)
  {
      /* Add code to this function (or its callees) to extract new fields. */
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
  
      const struct pkt_metadata *md = &packet->md;
      const void *data = dp_packet_data(packet);
      size_t size = dp_packet_size(packet);
      ovs_be32 packet_type = packet->packet_type;
      uint64_t *values = miniflow_values(dst);
      struct mf_ctx mf = { FLOWMAP_EMPTY_INITIALIZER, values,
                           values + FLOW_U64S };
      const char *frame;
      ovs_be16 dl_type = OVS_BE16_MAX;
      uint8_t nw_frag, nw_tos, nw_ttl, nw_proto;
      uint8_t *ct_nw_proto_p = NULL;
      ovs_be16 ct_tp_src = 0, ct_tp_dst = 0;
  
      /* Metadata. */
      if (flow_tnl_dst_is_set(&md->tunnel)) {
          miniflow_push_words(mf, tunnel, &md->tunnel,
                              offsetof(struct flow_tnl, metadata) /
                              sizeof(uint64_t));
  
          if (!(md->tunnel.flags & FLOW_TNL_F_UDPIF)) {
              if (md->tunnel.metadata.present.map) {
                  miniflow_push_words(mf, tunnel.metadata, &md->tunnel.metadata,
                                      sizeof md->tunnel.metadata /
                                      sizeof(uint64_t));
              }
          } else {
              if (md->tunnel.metadata.present.len) {
                  miniflow_push_words(mf, tunnel.metadata.present,
                                      &md->tunnel.metadata.present, 1);
                  miniflow_push_words(mf, tunnel.metadata.opts.gnv,
                                      md->tunnel.metadata.opts.gnv,
                                      DIV_ROUND_UP(md->tunnel.metadata.present.len,
                                                   sizeof(uint64_t)));
              }
          }
      }
      if (md->skb_priority || md->pkt_mark) {
          miniflow_push_uint32(mf, skb_priority, md->skb_priority);
          miniflow_push_uint32(mf, pkt_mark, md->pkt_mark);
      }
      miniflow_push_uint32(mf, dp_hash, md->dp_hash);
      miniflow_push_uint32(mf, in_port, odp_to_u32(md->in_port.odp_port));
      if (md->ct_state) {
          miniflow_push_uint32(mf, recirc_id, md->recirc_id);
          miniflow_push_uint8(mf, ct_state, md->ct_state);
          ct_nw_proto_p = miniflow_pointer(mf, ct_nw_proto);
          miniflow_push_uint8(mf, ct_nw_proto, 0);
          miniflow_push_uint16(mf, ct_zone, md->ct_zone);
          miniflow_push_uint32(mf, ct_mark, md->ct_mark);
          miniflow_push_be32(mf, packet_type, packet_type);
          if (!ovs_u128_is_zero(md->ct_label)) {
              miniflow_push_words(mf, ct_label, &md->ct_label,
                                  sizeof md->ct_label / sizeof(uint64_t));
          }
      } else {
          if (md->recirc_id) {
              miniflow_push_uint32(mf, recirc_id, md->recirc_id);
              miniflow_pad_to_64(mf, recirc_id);
          }
          miniflow_pad_from_64(mf, packet_type);
          miniflow_push_be32(mf, packet_type, packet_type);
      }
  
      /* Initialize packet's layer pointer and offsets. */
      frame = data;
      dp_packet_reset_offsets(packet);
  
      if (packet_type == htonl(PT_ETH)) {
          /* Must have full Ethernet header to proceed. */
          if (OVS_UNLIKELY(size < sizeof(struct eth_header))) {
              goto out;
          } else {
              /* Link layer. */
              ASSERT_SEQUENTIAL(dl_dst, dl_src);
              miniflow_push_macs(mf, dl_dst, data);
  
              /* VLAN */
              union flow_vlan_hdr vlans[FLOW_MAX_VLAN_HEADERS];
              size_t num_vlans = parse_vlan(&data, &size, vlans);
  
              dl_type = parse_ethertype(&data, &size);
              miniflow_push_be16(mf, dl_type, dl_type);
              miniflow_pad_to_64(mf, dl_type);
              if (num_vlans > 0) {
                  miniflow_push_words_32(mf, vlans, vlans, num_vlans);
              }
  
          }
      } else {
          /* Take dl_type from packet_type. */
          dl_type = pt_ns_type_be(packet_type);
          miniflow_pad_from_64(mf, dl_type);
          miniflow_push_be16(mf, dl_type, dl_type);
          /* Do not push vlan_tci, pad instead */
          miniflow_pad_to_64(mf, dl_type);
      }
  
      /* Parse mpls. */
      if (OVS_UNLIKELY(eth_type_mpls(dl_type))) {
          int count;
          const void *mpls = data;
  
          packet->l2_5_ofs = (char *)data - frame;
          count = parse_mpls(&data, &size);
          miniflow_push_words_32(mf, mpls_lse, mpls, count);
      }
  
      /* Network layer. */
      packet->l3_ofs = (char *)data - frame;
  
      nw_frag = 0;
      if (OVS_LIKELY(dl_type == htons(ETH_TYPE_IP))) {
          const struct ip_header *nh = data;
          int ip_len;
          uint16_t tot_len;
  
          if (OVS_UNLIKELY(!ipv4_sanity_check(nh, size, &ip_len, &tot_len))) {
              goto out;
          }
          dp_packet_set_l2_pad_size(packet, size - tot_len);
          size = tot_len;   /* Never pull padding. */
  
          /* Push both source and destination address at once. */
          miniflow_push_words(mf, nw_src, &nh->ip_src, 1);
          if (ct_nw_proto_p && !md->ct_orig_tuple_ipv6) {
              *ct_nw_proto_p = md->ct_orig_tuple.ipv4.ipv4_proto;
              if (*ct_nw_proto_p) {
                  miniflow_push_words(mf, ct_nw_src,
                                      &md->ct_orig_tuple.ipv4.ipv4_src, 1);
                  ct_tp_src = md->ct_orig_tuple.ipv4.src_port;
                  ct_tp_dst = md->ct_orig_tuple.ipv4.dst_port;
              }
          }
  
          miniflow_push_be32(mf, ipv6_label, 0); /* Padding for IPv4. */
  
          nw_tos = nh->ip_tos;
          nw_ttl = nh->ip_ttl;
          nw_proto = nh->ip_proto;
          nw_frag = ipv4_get_nw_frag(nh);
          data_pull(&data, &size, ip_len);
      } else if (dl_type == htons(ETH_TYPE_IPV6)) {
          const struct ovs_16aligned_ip6_hdr *nh = data;
          ovs_be32 tc_flow;
          uint16_t plen;
  
          if (OVS_UNLIKELY(!ipv6_sanity_check(nh, size))) {
              goto out;
          }
          data_pull(&data, &size, sizeof *nh);
  
          plen = ntohs(nh->ip6_plen);
          dp_packet_set_l2_pad_size(packet, size - plen);
          size = plen;   /* Never pull padding. */
  
          miniflow_push_words(mf, ipv6_src, &nh->ip6_src,
                              sizeof nh->ip6_src / 8);
          miniflow_push_words(mf, ipv6_dst, &nh->ip6_dst,
                              sizeof nh->ip6_dst / 8);
          if (ct_nw_proto_p && md->ct_orig_tuple_ipv6) {
              *ct_nw_proto_p = md->ct_orig_tuple.ipv6.ipv6_proto;
              if (*ct_nw_proto_p) {
                  miniflow_push_words(mf, ct_ipv6_src,
                                      &md->ct_orig_tuple.ipv6.ipv6_src,
                                      2 *
                                      sizeof md->ct_orig_tuple.ipv6.ipv6_src / 8);
                  ct_tp_src = md->ct_orig_tuple.ipv6.src_port;
                  ct_tp_dst = md->ct_orig_tuple.ipv6.dst_port;
              }
          }
  
          tc_flow = get_16aligned_be32(&nh->ip6_flow);
          nw_tos = ntohl(tc_flow) >> 20;
          nw_ttl = nh->ip6_hlim;
          nw_proto = nh->ip6_nxt;
  
          const struct ovs_16aligned_ip6_frag *frag_hdr;
          if (!parse_ipv6_ext_hdrs__(&data, &size, &nw_proto, &nw_frag,
                                     &frag_hdr)) {
              goto out;
          }
  
          /* This needs to be after the parse_ipv6_ext_hdrs__() call because it
           * leaves the nw_frag word uninitialized. */
          ASSERT_SEQUENTIAL(ipv6_label, nw_frag);
          ovs_be32 label = tc_flow & htonl(IPV6_LABEL_MASK);
          miniflow_push_be32(mf, ipv6_label, label);
      } else {
          if (dl_type == htons(ETH_TYPE_ARP) ||
              dl_type == htons(ETH_TYPE_RARP)) {
              struct eth_addr arp_buf[2];
              const struct arp_eth_header *arp = (const struct arp_eth_header *)
                  data_try_pull(&data, &size, ARP_ETH_HEADER_LEN);
  
              if (OVS_LIKELY(arp) && OVS_LIKELY(arp->ar_hrd == htons(1))
                  && OVS_LIKELY(arp->ar_pro == htons(ETH_TYPE_IP))
                  && OVS_LIKELY(arp->ar_hln == ETH_ADDR_LEN)
                  && OVS_LIKELY(arp->ar_pln == 4)) {
                  miniflow_push_be32(mf, nw_src,
                                     get_16aligned_be32(&arp->ar_spa));
                  miniflow_push_be32(mf, nw_dst,
                                     get_16aligned_be32(&arp->ar_tpa));
  
                  /* We only match on the lower 8 bits of the opcode. */
                  if (OVS_LIKELY(ntohs(arp->ar_op) <= 0xff)) {
                      miniflow_push_be32(mf, ipv6_label, 0); /* Pad with ARP. */
                      miniflow_push_be32(mf, nw_frag, htonl(ntohs(arp->ar_op)));
                  }
  
                  /* Must be adjacent. */
                  ASSERT_SEQUENTIAL(arp_sha, arp_tha);
  
                  arp_buf[0] = arp->ar_sha;
                  arp_buf[1] = arp->ar_tha;
                  miniflow_push_macs(mf, arp_sha, arp_buf);
                  miniflow_pad_to_64(mf, arp_tha);
              }
          } else if (dl_type == htons(ETH_TYPE_NSH)) {
              struct ovs_key_nsh nsh;
  
              if (OVS_LIKELY(parse_nsh(&data, &size, &nsh))) {
                  miniflow_push_words(mf, nsh, &nsh,
                                      sizeof(struct ovs_key_nsh) /
                                      sizeof(uint64_t));
              }
          }
          goto out;
      }
  
      packet->l4_ofs = (char *)data - frame;
      miniflow_push_be32(mf, nw_frag,
                         bytes_to_be32(nw_frag, nw_tos, nw_ttl, nw_proto));
  
      if (OVS_LIKELY(!(nw_frag & FLOW_NW_FRAG_LATER))) {
          if (OVS_LIKELY(nw_proto == IPPROTO_TCP)) {
              if (OVS_LIKELY(size >= TCP_HEADER_LEN)) {
                  const struct tcp_header *tcp = data;
  
                  miniflow_push_be32(mf, arp_tha.ea[2], 0);
                  miniflow_push_be32(mf, tcp_flags,
                                     TCP_FLAGS_BE32(tcp->tcp_ctl));
                  miniflow_push_be16(mf, tp_src, tcp->tcp_src);
                  miniflow_push_be16(mf, tp_dst, tcp->tcp_dst);
                  miniflow_push_be16(mf, ct_tp_src, ct_tp_src);
                  miniflow_push_be16(mf, ct_tp_dst, ct_tp_dst);
              }
          } else if (OVS_LIKELY(nw_proto == IPPROTO_UDP)) {
              if (OVS_LIKELY(size >= UDP_HEADER_LEN)) {
                  const struct udp_header *udp = data;
  
                  miniflow_push_be16(mf, tp_src, udp->udp_src);
                  miniflow_push_be16(mf, tp_dst, udp->udp_dst);
                  miniflow_push_be16(mf, ct_tp_src, ct_tp_src);
                  miniflow_push_be16(mf, ct_tp_dst, ct_tp_dst);
              }
          } else if (OVS_LIKELY(nw_proto == IPPROTO_SCTP)) {
              if (OVS_LIKELY(size >= SCTP_HEADER_LEN)) {
                  const struct sctp_header *sctp = data;
  
                  miniflow_push_be16(mf, tp_src, sctp->sctp_src);
                  miniflow_push_be16(mf, tp_dst, sctp->sctp_dst);
                  miniflow_push_be16(mf, ct_tp_src, ct_tp_src);
                  miniflow_push_be16(mf, ct_tp_dst, ct_tp_dst);
              }
          } else if (OVS_LIKELY(nw_proto == IPPROTO_ICMP)) {
              if (OVS_LIKELY(size >= ICMP_HEADER_LEN)) {
                  const struct icmp_header *icmp = data;
  
                  miniflow_push_be16(mf, tp_src, htons(icmp->icmp_type));
                  miniflow_push_be16(mf, tp_dst, htons(icmp->icmp_code));
                  miniflow_push_be16(mf, ct_tp_src, ct_tp_src);
                  miniflow_push_be16(mf, ct_tp_dst, ct_tp_dst);
              }
          } else if (OVS_LIKELY(nw_proto == IPPROTO_IGMP)) {
              if (OVS_LIKELY(size >= IGMP_HEADER_LEN)) {
                  const struct igmp_header *igmp = data;
  
                  miniflow_push_be16(mf, tp_src, htons(igmp->igmp_type));
                  miniflow_push_be16(mf, tp_dst, htons(igmp->igmp_code));
                  miniflow_push_be16(mf, ct_tp_src, ct_tp_src);
                  miniflow_push_be16(mf, ct_tp_dst, ct_tp_dst);
                  miniflow_push_be32(mf, igmp_group_ip4,
                                     get_16aligned_be32(&igmp->group));
                  miniflow_pad_to_64(mf, igmp_group_ip4);
              }
          } else if (OVS_LIKELY(nw_proto == IPPROTO_ICMPV6)) {
              if (OVS_LIKELY(size >= sizeof(struct icmp6_data_header))) {
                  const struct in6_addr *nd_target;
                  struct eth_addr arp_buf[2];
                  /* This will populate whether we received Option 1
                   * or Option 2. */
                  uint8_t opt_type;
                  /* This holds the ND Reserved field. */
                  ovs_be32 rso_flags;
                  const struct icmp6_data_header *icmp6;
  
                  icmp6 = data_pull(&data, &size, sizeof *icmp6);
                  if (parse_icmpv6(&data, &size, icmp6,
                                   &rso_flags, &nd_target, arp_buf, &opt_type)) {
                      if (nd_target) {
                          miniflow_push_words(mf, nd_target, nd_target,
                                              sizeof *nd_target / sizeof(uint64_t));
                      }
                      miniflow_push_macs(mf, arp_sha, arp_buf);
                      /* Populate options field and set the padding
                       * accordingly. */
                      if (opt_type != 0) {
                          miniflow_push_be16(mf, tcp_flags, htons(opt_type));
                          /* Pad to align with 64 bits.
                           * This will zero out the pad3 field. */
                          miniflow_pad_to_64(mf, tcp_flags);
                      } else {
                          /* Pad to align with 64 bits.
                           * This will zero out the tcp_flags & pad3 field. */
                          miniflow_pad_to_64(mf, arp_tha);
                      }
                      miniflow_push_be16(mf, tp_src,
                                         htons(icmp6->icmp6_base.icmp6_type));
                      miniflow_push_be16(mf, tp_dst,
                                         htons(icmp6->icmp6_base.icmp6_code));
                      miniflow_pad_to_64(mf, tp_dst);
                      /* Fill ND reserved field. */
                      miniflow_push_be32(mf, igmp_group_ip4, rso_flags);
                      miniflow_pad_to_64(mf, igmp_group_ip4);
                  } else {
                      /* ICMPv6 but not ND. */
                      miniflow_push_be16(mf, tp_src,
                                         htons(icmp6->icmp6_base.icmp6_type));
                      miniflow_push_be16(mf, tp_dst,
                                         htons(icmp6->icmp6_base.icmp6_code));
                      miniflow_push_be16(mf, ct_tp_src, ct_tp_src);
                      miniflow_push_be16(mf, ct_tp_dst, ct_tp_dst);
                  }
              }
          }
      }
   out:
      dst->map = mf.map;
  }
  
  static ovs_be16
  parse_dl_type(const void **datap, size_t *sizep)
  {
      union flow_vlan_hdr vlans[FLOW_MAX_VLAN_HEADERS];
  
      parse_vlan(datap, sizep, vlans);
  
      return parse_ethertype(datap, sizep);
  }
  
  /* Parses and return the TCP flags in 'packet', converted to host byte order.
   * If 'packet' is not an Ethernet packet embedding TCP, returns 0.
   *
   * The caller must ensure that 'packet' is at least ETH_HEADER_LEN bytes
   * long.'*/
  uint16_t
  parse_tcp_flags(struct dp_packet *packet)
  {
      const void *data = dp_packet_data(packet);
      const char *frame = (const char *)data;
      size_t size = dp_packet_size(packet);
      ovs_be16 dl_type;
      uint8_t nw_frag = 0, nw_proto = 0;
  
      if (!dp_packet_is_eth(packet)) {
          return 0;
      }
  
      dp_packet_reset_offsets(packet);
  
      dl_type = parse_dl_type(&data, &size);
      if (OVS_UNLIKELY(eth_type_mpls(dl_type))) {
          packet->l2_5_ofs = (char *)data - frame;
      }
      if (OVS_LIKELY(dl_type == htons(ETH_TYPE_IP))) {
          const struct ip_header *nh = data;
          int ip_len;
          uint16_t tot_len;
  
          if (OVS_UNLIKELY(!ipv4_sanity_check(nh, size, &ip_len, &tot_len))) {
              return 0;
          }
          dp_packet_set_l2_pad_size(packet, size - tot_len);
          packet->l3_ofs = (uint16_t)((char *)nh - frame);
          nw_proto = nh->ip_proto;
          nw_frag = ipv4_get_nw_frag(nh);
  
          size = tot_len;   /* Never pull padding. */
          data_pull(&data, &size, ip_len);
      } else if (dl_type == htons(ETH_TYPE_IPV6)) {
          const struct ovs_16aligned_ip6_hdr *nh = data;
          uint16_t plen;
  
          if (OVS_UNLIKELY(!ipv6_sanity_check(nh, size))) {
              return 0;
          }
          packet->l3_ofs = (uint16_t)((char *)nh - frame);
          data_pull(&data, &size, sizeof *nh);
  
          plen = ntohs(nh->ip6_plen); /* Never pull padding. */
          dp_packet_set_l2_pad_size(packet, size - plen);
          size = plen;
          const struct ovs_16aligned_ip6_frag *frag_hdr;
          nw_proto = nh->ip6_nxt;
          if (!parse_ipv6_ext_hdrs__(&data, &size, &nw_proto, &nw_frag,
              &frag_hdr)) {
              return 0;
          }
      } else {
          return 0;
      }
  
      packet->l4_ofs = (uint16_t)((char *)data - frame);
      if (!(nw_frag & FLOW_NW_FRAG_LATER) && nw_proto == IPPROTO_TCP &&
          size >= TCP_HEADER_LEN) {
          const struct tcp_header *tcp = data;
  
          return TCP_FLAGS(tcp->tcp_ctl);
      }
  
      return 0;
  }
  
  /* For every bit of a field that is wildcarded in 'wildcards', sets the
   * corresponding bit in 'flow' to zero. */
  void
  flow_zero_wildcards(struct flow *flow, const struct flow_wildcards *wildcards)
  {
      uint64_t *flow_u64 = (uint64_t *) flow;
      const uint64_t *wc_u64 = (const uint64_t *) &wildcards->masks;
      size_t i;
  
      for (i = 0; i < FLOW_U64S; i++) {
          flow_u64[i] &= wc_u64[i];
      }
  }
  
  void
  flow_unwildcard_tp_ports(const struct flow *flow, struct flow_wildcards *wc)
  {
      if (flow->nw_proto != IPPROTO_ICMP) {
          memset(&wc->masks.tp_src, 0xff, sizeof wc->masks.tp_src);
          memset(&wc->masks.tp_dst, 0xff, sizeof wc->masks.tp_dst);
      } else {
          wc->masks.tp_src = htons(0xff);
          wc->masks.tp_dst = htons(0xff);
      }
  }
  
  /* Initializes 'flow_metadata' with the metadata found in 'flow'. */
  void
  flow_get_metadata(const struct flow *flow, struct match *flow_metadata)
  {
      int i;
  
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
  
      match_init_catchall(flow_metadata);
      if (flow->tunnel.tun_id != htonll(0)) {
          match_set_tun_id(flow_metadata, flow->tunnel.tun_id);
      }
      if (flow->tunnel.flags & FLOW_TNL_PUB_F_MASK) {
          match_set_tun_flags(flow_metadata,
                              flow->tunnel.flags & FLOW_TNL_PUB_F_MASK);
      }
      if (flow->tunnel.ip_src) {
          match_set_tun_src(flow_metadata, flow->tunnel.ip_src);
      }
      if (flow->tunnel.ip_dst) {
          match_set_tun_dst(flow_metadata, flow->tunnel.ip_dst);
      }
      if (ipv6_addr_is_set(&flow->tunnel.ipv6_src)) {
          match_set_tun_ipv6_src(flow_metadata, &flow->tunnel.ipv6_src);
      }
      if (ipv6_addr_is_set(&flow->tunnel.ipv6_dst)) {
          match_set_tun_ipv6_dst(flow_metadata, &flow->tunnel.ipv6_dst);
      }
      if (flow->tunnel.gbp_id != htons(0)) {
          match_set_tun_gbp_id(flow_metadata, flow->tunnel.gbp_id);
      }
      if (flow->tunnel.gbp_flags) {
          match_set_tun_gbp_flags(flow_metadata, flow->tunnel.gbp_flags);
      }
      if (flow->tunnel.erspan_ver) {
          match_set_tun_erspan_ver(flow_metadata, flow->tunnel.erspan_ver);
      }
      if (flow->tunnel.erspan_idx) {
          match_set_tun_erspan_idx(flow_metadata, flow->tunnel.erspan_idx);
      }
      if (flow->tunnel.erspan_dir) {
          match_set_tun_erspan_dir(flow_metadata, flow->tunnel.erspan_dir);
      }
      if (flow->tunnel.erspan_hwid) {
          match_set_tun_erspan_hwid(flow_metadata, flow->tunnel.erspan_hwid);
      }
      tun_metadata_get_fmd(&flow->tunnel, flow_metadata);
      if (flow->metadata != htonll(0)) {
          match_set_metadata(flow_metadata, flow->metadata);
      }
  
      for (i = 0; i < FLOW_N_REGS; i++) {
          if (flow->regs[i]) {
              match_set_reg(flow_metadata, i, flow->regs[i]);
          }
      }
  
      if (flow->pkt_mark != 0) {
          match_set_pkt_mark(flow_metadata, flow->pkt_mark);
      }
  
      match_set_in_port(flow_metadata, flow->in_port.ofp_port);
      if (flow->packet_type != htonl(PT_ETH)) {
          match_set_packet_type(flow_metadata, flow->packet_type);
      }
  
      if (flow->ct_state != 0) {
          match_set_ct_state(flow_metadata, flow->ct_state);
          /* Match dl_type since it is required for the later interpretation of
           * the conntrack metadata. */
          match_set_dl_type(flow_metadata, flow->dl_type);
          if (is_ct_valid(flow, NULL, NULL) && flow->ct_nw_proto != 0) {
              if (flow->dl_type == htons(ETH_TYPE_IP)) {
                  match_set_ct_nw_src(flow_metadata, flow->ct_nw_src);
                  match_set_ct_nw_dst(flow_metadata, flow->ct_nw_dst);
                  match_set_ct_nw_proto(flow_metadata, flow->ct_nw_proto);
                  match_set_ct_tp_src(flow_metadata, flow->ct_tp_src);
                  match_set_ct_tp_dst(flow_metadata, flow->ct_tp_dst);
              } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
                  match_set_ct_ipv6_src(flow_metadata, &flow->ct_ipv6_src);
                  match_set_ct_ipv6_dst(flow_metadata, &flow->ct_ipv6_dst);
                  match_set_ct_nw_proto(flow_metadata, flow->ct_nw_proto);
                  match_set_ct_tp_src(flow_metadata, flow->ct_tp_src);
                  match_set_ct_tp_dst(flow_metadata, flow->ct_tp_dst);
              }
          }
      }
      if (flow->ct_zone != 0) {
          match_set_ct_zone(flow_metadata, flow->ct_zone);
      }
      if (flow->ct_mark != 0) {
          match_set_ct_mark(flow_metadata, flow->ct_mark);
      }
      if (!ovs_u128_is_zero(flow->ct_label)) {
          match_set_ct_label(flow_metadata, flow->ct_label);
      }
  }
  
  const char *
  ct_state_to_string(uint32_t state)
  {
      switch (state) {
  #define CS_STATE(ENUM, INDEX, NAME) case CS_##ENUM: return NAME;
          CS_STATES
  #undef CS_STATE
      default:
          return NULL;
      }
  }
  
  uint32_t
  ct_state_from_string(const char *s)
  {
  #define CS_STATE(ENUM, INDEX, NAME) \
      if (!strcmp(s, NAME)) {         \
          return CS_##ENUM;           \
      }
      CS_STATES
  #undef CS_STATE
      return 0;
  }
  
  /* Parses conntrack state from 'state_str'.  If it is parsed successfully,
   * stores the parsed ct_state in 'ct_state', and returns true.  Otherwise,
   * returns false, and reports error message in 'ds'. */
  bool
  parse_ct_state(const char *state_str, uint32_t default_state,
                 uint32_t *ct_state, struct ds *ds)
  {
      uint32_t state = default_state;
      char *state_s = xstrdup(state_str);
      char *save_ptr = NULL;
  
      for (char *cs = strtok_r(state_s, ", ", &save_ptr); cs;
           cs = strtok_r(NULL, ", ", &save_ptr)) {
          uint32_t bit = ct_state_from_string(cs);
          if (!bit) {
              ds_put_format(ds, "%s: unknown connection tracking state flag",
                            cs);
              free(state_s);
              return false;
          }
          state |= bit;
      }
  
      *ct_state = state;
      free(state_s);
  
      return true;
  }
  
  /* Checks the given conntrack state 'state' according to the constraints
   * listed in ovs-fields (7).  Returns true if it is valid.  Otherwise, returns
   * false, and reports error in 'ds'. */
  bool
  validate_ct_state(uint32_t state, struct ds *ds)
  {
      bool valid_ct_state = true;
      struct ds d_str = DS_EMPTY_INITIALIZER;
  
      format_flags(&d_str, ct_state_to_string, state, '|');
  
      if (state && !(state & CS_TRACKED)) {
          ds_put_format(ds, "%s: invalid connection state: "
                        "If \"trk\" is unset, no other flags are set\n",
                        ds_cstr(&d_str));
          valid_ct_state = false;
      }
      if (state & CS_INVALID && state & ~(CS_TRACKED | CS_INVALID)) {
          ds_put_format(ds, "%s: invalid connection state: "
                        "when \"inv\" is set, only \"trk\" may also be set\n",
                        ds_cstr(&d_str));
          valid_ct_state = false;
      }
      if (state & CS_NEW && state & CS_ESTABLISHED) {
          ds_put_format(ds, "%s: invalid connection state: "
                        "\"new\" and \"est\" are mutually exclusive\n",
                        ds_cstr(&d_str));
          valid_ct_state = false;
      }
      if (state & CS_NEW && state & CS_REPLY_DIR) {
          ds_put_format(ds, "%s: invalid connection state: "
                        "\"new\" and \"rpy\" are mutually exclusive\n",
                        ds_cstr(&d_str));
          valid_ct_state = false;
      }
  
      ds_destroy(&d_str);
      return valid_ct_state;
  }
  
  /* Clears the fields in 'flow' associated with connection tracking. */
  void
  flow_clear_conntrack(struct flow *flow)
  {
      flow->ct_state = 0;
      flow->ct_zone = 0;
      flow->ct_mark = 0;
      flow->ct_label = OVS_U128_ZERO;
  
      flow->ct_nw_proto = 0;
      flow->ct_tp_src = 0;
      flow->ct_tp_dst = 0;
      if (flow->dl_type == htons(ETH_TYPE_IP)) {
          flow->ct_nw_src = 0;
          flow->ct_nw_dst = 0;
      } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
          memset(&flow->ct_ipv6_src, 0, sizeof flow->ct_ipv6_src);
          memset(&flow->ct_ipv6_dst, 0, sizeof flow->ct_ipv6_dst);
      }
  }
  
  char *
  flow_to_string(const struct flow *flow,
                 const struct ofputil_port_map *port_map)
  {
      struct ds ds = DS_EMPTY_INITIALIZER;
      flow_format(&ds, flow, port_map);
      return ds_cstr(&ds);
  }
  
  const char *
  flow_tun_flag_to_string(uint32_t flags)
  {
      switch (flags) {
      case FLOW_TNL_F_DONT_FRAGMENT:
          return "df";
      case FLOW_TNL_F_CSUM:
          return "csum";
      case FLOW_TNL_F_KEY:
          return "key";
      case FLOW_TNL_F_OAM:
          return "oam";
      default:
          return NULL;
      }
  }
  
  void
  format_flags(struct ds *ds, const char *(*bit_to_string)(uint32_t),
               uint32_t flags, char del)
  {
      uint32_t bad = 0;
  
      if (!flags) {
          ds_put_char(ds, '0');
          return;
      }
      while (flags) {
          uint32_t bit = rightmost_1bit(flags);
          const char *s;
  
          s = bit_to_string(bit);
          if (s) {
              ds_put_format(ds, "%s%c", s, del);
          } else {
              bad |= bit;
          }
  
          flags &= ~bit;
      }
  
      if (bad) {
          ds_put_format(ds, "0x%"PRIx32"%c", bad, del);
      }
      ds_chomp(ds, del);
  }
  
  void
  format_flags_masked(struct ds *ds, const char *name,
                      const char *(*bit_to_string)(uint32_t), uint32_t flags,
                      uint32_t mask, uint32_t max_mask)
  {
      if (name) {
          ds_put_format(ds, "%s%s=%s", colors.param, name, colors.end);
      }
  
      if (mask == max_mask) {
          format_flags(ds, bit_to_string, flags, '|');
          return;
      }
  
      if (!mask) {
          ds_put_cstr(ds, "0/0");
          return;
      }
  
      while (mask) {
          uint32_t bit = rightmost_1bit(mask);
          const char *s = bit_to_string(bit);
  
          ds_put_format(ds, "%s%s", (flags & bit) ? "+" : "-",
                        s ? s : "[Unknown]");
          mask &= ~bit;
      }
  }
  
  static void
  put_u16_masked(struct ds *s, uint16_t value, uint16_t mask)
  {
      if (!mask) {
          ds_put_char(s, '*');
      } else {
          if (value > 9) {
              ds_put_format(s, "0x%"PRIx16, value);
          } else {
              ds_put_format(s, "%"PRIu16, value);
          }
  
          if (mask != UINT16_MAX) {
              ds_put_format(s, "/0x%"PRIx16, mask);
          }
      }
  }
  
  void
  format_packet_type_masked(struct ds *s, ovs_be32 value, ovs_be32 mask)
  {
      if (value == htonl(PT_ETH) && mask == OVS_BE32_MAX) {
          ds_put_cstr(s, "eth");
      } else {
          ds_put_cstr(s, "packet_type=(");
          put_u16_masked(s, pt_ns(value), pt_ns(mask));
          ds_put_char(s, ',');
          put_u16_masked(s, pt_ns_type(value), pt_ns_type(mask));
          ds_put_char(s, ')');
      }
  }
  
  /* Scans a string 's' of flags to determine their numerical value and
   * returns the number of characters parsed using 'bit_to_string' to
   * lookup flag names. Scanning continues until the character 'end' is
   * reached.
   *
   * In the event of a failure, a negative error code will be returned. In
   * addition, if 'res_string' is non-NULL then a descriptive string will
   * be returned incorporating the identifying string 'field_name'. This
   * error string must be freed by the caller.
   *
   * Upon success, the flag values will be stored in 'res_flags' and
   * optionally 'res_mask', if it is non-NULL (if it is NULL then any masks
   * present in the original string will be considered an error). The
   * caller may restrict the acceptable set of values through the mask
   * 'allowed'. */
  int
  parse_flags(const char *s, const char *(*bit_to_string)(uint32_t),
              char end, const char *field_name, char **res_string,
              uint32_t *res_flags, uint32_t allowed, uint32_t *res_mask)
  {
      uint32_t result = 0;
      int n;
  
      /* Parse masked flags in numeric format? */
      if (res_mask && ovs_scan(s, "%"SCNi32"/%"SCNi32"%n",
                               res_flags, res_mask, &n) && n > 0) {
          if (*res_flags & ~allowed || *res_mask & ~allowed) {
              goto unknown;
          }
          return n;
      }
  
      n = 0;
  
      if (res_mask && (*s == '+' || *s == '-')) {
          uint32_t flags = 0, mask = 0;
  
          /* Parse masked flags. */
          while (s[0] != end) {
              bool set;
              uint32_t bit;
              size_t len;
  
              if (s[0] == '+') {
                  set = true;
              } else if (s[0] == '-') {
                  set = false;
              } else {
                  if (res_string) {
                      *res_string = xasprintf("%s: %s must be preceded by '+' "
                                              "(for SET) or '-' (NOT SET)", s,
                                              field_name);
                  }
                  return -EINVAL;
              }
              s++;
              n++;
  
              for (bit = 1; bit; bit <<= 1) {
                  const char *fname = bit_to_string(bit);
  
                  if (!fname) {
                      continue;
                  }
  
                  len = strlen(fname);
                  if (strncmp(s, fname, len) ||
                      (s[len] != '+' && s[len] != '-' && s[len] != end)) {
                      continue;
                  }
  
                  if (mask & bit) {
                      /* bit already set. */
                      if (res_string) {
                          *res_string = xasprintf("%s: Each %s flag can be "
                                                  "specified only once", s,
                                                  field_name);
                      }
                      return -EINVAL;
                  }
                  if (!(bit & allowed)) {
                      goto unknown;
                  }
                  if (set) {
                     flags |= bit;
                  }
                  mask |= bit;
                  break;
              }
  
              if (!bit) {
                  goto unknown;
              }
              s += len;
              n += len;
          }
  
          *res_flags = flags;
          *res_mask = mask;
          return n;
      }
  
      /* Parse unmasked flags.  If a flag is present, it is set, otherwise
       * it is not set. */
      while (s[n] != end) {
          unsigned long long int flags;
          uint32_t bit;
          int n0;
  
          if (ovs_scan(&s[n], "%lli%n", &flags, &n0)) {
              if (flags & ~allowed) {
                  goto unknown;
              }
              n += n0 + (s[n + n0] == '|');
              result |= flags;
              continue;
          }
  
          for (bit = 1; bit; bit <<= 1) {
              const char *name = bit_to_string(bit);
              size_t len;
  
              if (!name) {
                  continue;
              }
  
              len = strlen(name);
              if (!strncmp(s + n, name, len) &&
                  (s[n + len] == '|' || s[n + len] == end)) {
                  if (!(bit & allowed)) {
                      goto unknown;
                  }
                  result |= bit;
                  n += len + (s[n + len] == '|');
                  break;
              }
          }
  
          if (!bit) {
              goto unknown;
          }
      }
  
      *res_flags = result;
      if (res_mask) {
          *res_mask = UINT32_MAX;
      }
      if (res_string) {
          *res_string = NULL;
      }
      return n;
  
  unknown:
      if (res_string) {
          *res_string = xasprintf("%s: unknown %s flag(s)", s, field_name);
      }
      return -EINVAL;
  }
  
  void
  flow_format(struct ds *ds,
              const struct flow *flow, const struct ofputil_port_map *port_map)
  {
      struct match match;
      struct flow_wildcards *wc = &match.wc;
  
      match_wc_init(&match, flow);
  
      /* As this function is most often used for formatting a packet in a
       * packet-in message, skip formatting the packet context fields that are
       * all-zeroes to make the print-out easier on the eyes.  This means that a
       * missing context field implies a zero value for that field.  This is
       * similar to OpenFlow encoding of these fields, as the specification
       * states that all-zeroes context fields should not be encoded in the
       * packet-in messages. */
      if (!flow->in_port.ofp_port) {
          WC_UNMASK_FIELD(wc, in_port);
      }
      if (!flow->skb_priority) {
          WC_UNMASK_FIELD(wc, skb_priority);
      }
      if (!flow->pkt_mark) {
          WC_UNMASK_FIELD(wc, pkt_mark);
      }
      if (!flow->recirc_id) {
          WC_UNMASK_FIELD(wc, recirc_id);
      }
      if (!flow->dp_hash) {
          WC_UNMASK_FIELD(wc, dp_hash);
      }
      if (!flow->ct_state) {
          WC_UNMASK_FIELD(wc, ct_state);
      }
      if (!flow->ct_zone) {
          WC_UNMASK_FIELD(wc, ct_zone);
      }
      if (!flow->ct_mark) {
          WC_UNMASK_FIELD(wc, ct_mark);
      }
      if (ovs_u128_is_zero(flow->ct_label)) {
          WC_UNMASK_FIELD(wc, ct_label);
      }
      if (!is_ct_valid(flow, &match.wc, NULL) || !flow->ct_nw_proto) {
          WC_UNMASK_FIELD(wc, ct_nw_proto);
          WC_UNMASK_FIELD(wc, ct_tp_src);
          WC_UNMASK_FIELD(wc, ct_tp_dst);
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              WC_UNMASK_FIELD(wc, ct_nw_src);
              WC_UNMASK_FIELD(wc, ct_nw_dst);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              WC_UNMASK_FIELD(wc, ct_ipv6_src);
              WC_UNMASK_FIELD(wc, ct_ipv6_dst);
          }
      }
      for (int i = 0; i < FLOW_N_REGS; i++) {
          if (!flow->regs[i]) {
              WC_UNMASK_FIELD(wc, regs[i]);
          }
      }
      if (!flow->metadata) {
          WC_UNMASK_FIELD(wc, metadata);
      }
  
      match_format(&match, port_map, ds, OFP_DEFAULT_PRIORITY);
  }
  
  void
  flow_print(FILE *stream,
             const struct flow *flow, const struct ofputil_port_map *port_map)
  {
      char *s = flow_to_string(flow, port_map);
      fputs(s, stream);
      free(s);
  }
  
  /* flow_wildcards functions. */
  
  /* Initializes 'wc' as a set of wildcards that matches every packet. */
  void
  flow_wildcards_init_catchall(struct flow_wildcards *wc)
  {
      memset(&wc->masks, 0, sizeof wc->masks);
  }
  
  /* Converts a flow into flow wildcards.  It sets the wildcard masks based on
   * the packet headers extracted to 'flow'.  It will not set the mask for fields
   * that do not make sense for the packet type.  OpenFlow-only metadata is
   * wildcarded, but other metadata is unconditionally exact-matched. */
  void
  flow_wildcards_init_for_packet(struct flow_wildcards *wc,
                                 const struct flow *flow)
  {
      ovs_be16 dl_type = OVS_BE16_MAX;
  
      memset(&wc->masks, 0x0, sizeof wc->masks);
  
      /* Update this function whenever struct flow changes. */
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
  
      if (flow_tnl_dst_is_set(&flow->tunnel)) {
          if (flow->tunnel.flags & FLOW_TNL_F_KEY) {
              WC_MASK_FIELD(wc, tunnel.tun_id);
          }
          WC_MASK_FIELD(wc, tunnel.ip_src);
          WC_MASK_FIELD(wc, tunnel.ip_dst);
          WC_MASK_FIELD(wc, tunnel.ipv6_src);
          WC_MASK_FIELD(wc, tunnel.ipv6_dst);
          WC_MASK_FIELD(wc, tunnel.flags);
          WC_MASK_FIELD(wc, tunnel.ip_tos);
          WC_MASK_FIELD(wc, tunnel.ip_ttl);
          WC_MASK_FIELD(wc, tunnel.tp_src);
          WC_MASK_FIELD(wc, tunnel.tp_dst);
          WC_MASK_FIELD(wc, tunnel.gbp_id);
          WC_MASK_FIELD(wc, tunnel.gbp_flags);
          WC_MASK_FIELD(wc, tunnel.erspan_ver);
          WC_MASK_FIELD(wc, tunnel.erspan_idx);
          WC_MASK_FIELD(wc, tunnel.erspan_dir);
          WC_MASK_FIELD(wc, tunnel.erspan_hwid);
  
          if (!(flow->tunnel.flags & FLOW_TNL_F_UDPIF)) {
              if (flow->tunnel.metadata.present.map) {
                  wc->masks.tunnel.metadata.present.map =
                                                flow->tunnel.metadata.present.map;
                  WC_MASK_FIELD(wc, tunnel.metadata.opts.u8);
                  WC_MASK_FIELD(wc, tunnel.metadata.tab);
              }
          } else {
              WC_MASK_FIELD(wc, tunnel.metadata.present.len);
              memset(wc->masks.tunnel.metadata.opts.gnv, 0xff,
                     flow->tunnel.metadata.present.len);
          }
      } else if (flow->tunnel.tun_id) {
          WC_MASK_FIELD(wc, tunnel.tun_id);
      }
  
      /* metadata, regs, and conj_id wildcarded. */
  
      WC_MASK_FIELD(wc, skb_priority);
      WC_MASK_FIELD(wc, pkt_mark);
      WC_MASK_FIELD(wc, ct_state);
      WC_MASK_FIELD(wc, ct_zone);
      WC_MASK_FIELD(wc, ct_mark);
      WC_MASK_FIELD(wc, ct_label);
      WC_MASK_FIELD(wc, recirc_id);
      WC_MASK_FIELD(wc, dp_hash);
      WC_MASK_FIELD(wc, in_port);
  
      /* actset_output wildcarded. */
  
      WC_MASK_FIELD(wc, packet_type);
      if (flow->packet_type == htonl(PT_ETH)) {
          WC_MASK_FIELD(wc, dl_dst);
          WC_MASK_FIELD(wc, dl_src);
          WC_MASK_FIELD(wc, dl_type);
          /* No need to set mask of inner VLANs that don't exist. */
          for (int i = 0; i < FLOW_MAX_VLAN_HEADERS; i++) {
              /* Always show the first zero VLAN. */
              WC_MASK_FIELD(wc, vlans[i]);
              if (flow->vlans[i].tci == htons(0)) {
                  break;
              }
          }
          dl_type = flow->dl_type;
      } else {
          dl_type = pt_ns_type_be(flow->packet_type);
      }
  
      if (dl_type == htons(ETH_TYPE_IP)) {
          WC_MASK_FIELD(wc, nw_src);
          WC_MASK_FIELD(wc, nw_dst);
          WC_MASK_FIELD(wc, ct_nw_src);
          WC_MASK_FIELD(wc, ct_nw_dst);
      } else if (dl_type == htons(ETH_TYPE_IPV6)) {
          WC_MASK_FIELD(wc, ipv6_src);
          WC_MASK_FIELD(wc, ipv6_dst);
          WC_MASK_FIELD(wc, ipv6_label);
          if (is_nd(flow, wc)) {
              WC_MASK_FIELD(wc, arp_sha);
              WC_MASK_FIELD(wc, arp_tha);
              WC_MASK_FIELD(wc, nd_target);
          } else {
              WC_MASK_FIELD(wc, ct_ipv6_src);
              WC_MASK_FIELD(wc, ct_ipv6_dst);
          }
      } else if (dl_type == htons(ETH_TYPE_ARP) ||
                 dl_type == htons(ETH_TYPE_RARP)) {
          WC_MASK_FIELD(wc, nw_src);
          WC_MASK_FIELD(wc, nw_dst);
          WC_MASK_FIELD(wc, nw_proto);
          WC_MASK_FIELD(wc, arp_sha);
          WC_MASK_FIELD(wc, arp_tha);
          return;
      } else if (eth_type_mpls(dl_type)) {
          for (int i = 0; i < FLOW_MAX_MPLS_LABELS; i++) {
              WC_MASK_FIELD(wc, mpls_lse[i]);
              if (flow->mpls_lse[i] & htonl(MPLS_BOS_MASK)) {
                  break;
              }
          }
          return;
      } else if (flow->dl_type == htons(ETH_TYPE_NSH)) {
          WC_MASK_FIELD(wc, nsh.flags);
          WC_MASK_FIELD(wc, nsh.ttl);
          WC_MASK_FIELD(wc, nsh.mdtype);
          WC_MASK_FIELD(wc, nsh.np);
          WC_MASK_FIELD(wc, nsh.path_hdr);
          WC_MASK_FIELD(wc, nsh.context);
      } else {
          return; /* Unknown ethertype. */
      }
  
      /* IPv4 or IPv6. */
      WC_MASK_FIELD(wc, nw_frag);
      WC_MASK_FIELD(wc, nw_tos);
      WC_MASK_FIELD(wc, nw_ttl);
      WC_MASK_FIELD(wc, nw_proto);
      WC_MASK_FIELD(wc, ct_nw_proto);
      WC_MASK_FIELD(wc, ct_tp_src);
      WC_MASK_FIELD(wc, ct_tp_dst);
  
      /* No transport layer header in later fragments. */
      if (!(flow->nw_frag & FLOW_NW_FRAG_LATER) &&
          (flow->nw_proto == IPPROTO_ICMP ||
           flow->nw_proto == IPPROTO_ICMPV6 ||
           flow->nw_proto == IPPROTO_TCP ||
           flow->nw_proto == IPPROTO_UDP ||
           flow->nw_proto == IPPROTO_SCTP ||
           flow->nw_proto == IPPROTO_IGMP)) {
          WC_MASK_FIELD(wc, tp_src);
          WC_MASK_FIELD(wc, tp_dst);
  
          if (flow->nw_proto == IPPROTO_TCP) {
              WC_MASK_FIELD(wc, tcp_flags);
          } else if (flow->nw_proto == IPPROTO_IGMP) {
              WC_MASK_FIELD(wc, igmp_group_ip4);
          }
      }
  }
  
  /* Return a map of possible fields for a packet of the same type as 'flow'.
   * Including extra bits in the returned mask is not wrong, it is just less
   * optimal.
   *
   * This is a less precise version of flow_wildcards_init_for_packet() above. */
  void
  flow_wc_map(const struct flow *flow, struct flowmap *map)
  {
      /* Update this function whenever struct flow changes. */
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
  
      flowmap_init(map);
  
      if (flow_tnl_dst_is_set(&flow->tunnel)) {
          FLOWMAP_SET__(map, tunnel, offsetof(struct flow_tnl, metadata));
          if (!(flow->tunnel.flags & FLOW_TNL_F_UDPIF)) {
              if (flow->tunnel.metadata.present.map) {
                  FLOWMAP_SET(map, tunnel.metadata);
              }
          } else {
              FLOWMAP_SET(map, tunnel.metadata.present.len);
              FLOWMAP_SET__(map, tunnel.metadata.opts.gnv,
                            flow->tunnel.metadata.present.len);
          }
      }
  
      /* Metadata fields that can appear on packet input. */
      FLOWMAP_SET(map, skb_priority);
      FLOWMAP_SET(map, pkt_mark);
      FLOWMAP_SET(map, recirc_id);
      FLOWMAP_SET(map, dp_hash);
      FLOWMAP_SET(map, in_port);
      FLOWMAP_SET(map, dl_dst);
      FLOWMAP_SET(map, dl_src);
      FLOWMAP_SET(map, dl_type);
      FLOWMAP_SET(map, vlans);
      FLOWMAP_SET(map, ct_state);
      FLOWMAP_SET(map, ct_zone);
      FLOWMAP_SET(map, ct_mark);
      FLOWMAP_SET(map, ct_label);
      FLOWMAP_SET(map, packet_type);
  
      /* Ethertype-dependent fields. */
      if (OVS_LIKELY(flow->dl_type == htons(ETH_TYPE_IP))) {
          FLOWMAP_SET(map, nw_src);
          FLOWMAP_SET(map, nw_dst);
          FLOWMAP_SET(map, nw_proto);
          FLOWMAP_SET(map, nw_frag);
          FLOWMAP_SET(map, nw_tos);
          FLOWMAP_SET(map, nw_ttl);
          FLOWMAP_SET(map, tp_src);
          FLOWMAP_SET(map, tp_dst);
          FLOWMAP_SET(map, ct_nw_proto);
          FLOWMAP_SET(map, ct_nw_src);
          FLOWMAP_SET(map, ct_nw_dst);
          FLOWMAP_SET(map, ct_tp_src);
          FLOWMAP_SET(map, ct_tp_dst);
  
          if (OVS_UNLIKELY(flow->nw_proto == IPPROTO_IGMP)) {
              FLOWMAP_SET(map, igmp_group_ip4);
          } else {
              FLOWMAP_SET(map, tcp_flags);
          }
      } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
          FLOWMAP_SET(map, ipv6_src);
          FLOWMAP_SET(map, ipv6_dst);
          FLOWMAP_SET(map, ipv6_label);
          FLOWMAP_SET(map, nw_proto);
          FLOWMAP_SET(map, nw_frag);
          FLOWMAP_SET(map, nw_tos);
          FLOWMAP_SET(map, nw_ttl);
          FLOWMAP_SET(map, tp_src);
          FLOWMAP_SET(map, tp_dst);
  
          if (OVS_UNLIKELY(is_nd(flow, NULL))) {
              FLOWMAP_SET(map, nd_target);
              FLOWMAP_SET(map, arp_sha);
              FLOWMAP_SET(map, arp_tha);
              FLOWMAP_SET(map, tcp_flags);
              FLOWMAP_SET(map, igmp_group_ip4);
          } else {
              FLOWMAP_SET(map, ct_nw_proto);
              FLOWMAP_SET(map, ct_ipv6_src);
              FLOWMAP_SET(map, ct_ipv6_dst);
              FLOWMAP_SET(map, ct_tp_src);
              FLOWMAP_SET(map, ct_tp_dst);
              FLOWMAP_SET(map, tcp_flags);
          }
      } else if (eth_type_mpls(flow->dl_type)) {
          FLOWMAP_SET(map, mpls_lse);
      } else if (flow->dl_type == htons(ETH_TYPE_ARP) ||
                 flow->dl_type == htons(ETH_TYPE_RARP)) {
          FLOWMAP_SET(map, nw_src);
          FLOWMAP_SET(map, nw_dst);
          FLOWMAP_SET(map, nw_proto);
          FLOWMAP_SET(map, arp_sha);
          FLOWMAP_SET(map, arp_tha);
      } else if (flow->dl_type == htons(ETH_TYPE_NSH)) {
          FLOWMAP_SET(map, nsh.flags);
          FLOWMAP_SET(map, nsh.mdtype);
          FLOWMAP_SET(map, nsh.np);
          FLOWMAP_SET(map, nsh.path_hdr);
          FLOWMAP_SET(map, nsh.context);
      }
  }
  
  /* Clear the metadata and register wildcard masks. They are not packet
   * header fields. */
  void
  flow_wildcards_clear_non_packet_fields(struct flow_wildcards *wc)
  {
      /* Update this function whenever struct flow changes. */
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
  
      memset(&wc->masks.metadata, 0, sizeof wc->masks.metadata);
      memset(&wc->masks.regs, 0, sizeof wc->masks.regs);
      wc->masks.actset_output = 0;
      wc->masks.conj_id = 0;
  }
  
  /* Returns true if 'wc' matches every packet, false if 'wc' fixes any bits or
   * fields. */
  bool
  flow_wildcards_is_catchall(const struct flow_wildcards *wc)
  {
      const uint64_t *wc_u64 = (const uint64_t *) &wc->masks;
      size_t i;
  
      for (i = 0; i < FLOW_U64S; i++) {
          if (wc_u64[i]) {
              return false;
          }
      }
      return true;
  }
  
  /* Sets 'dst' as the bitwise AND of wildcards in 'src1' and 'src2'.
   * That is, a bit or a field is wildcarded in 'dst' if it is wildcarded
   * in 'src1' or 'src2' or both.  */
  void
  flow_wildcards_and(struct flow_wildcards *dst,
                     const struct flow_wildcards *src1,
                     const struct flow_wildcards *src2)
  {
      uint64_t *dst_u64 = (uint64_t *) &dst->masks;
      const uint64_t *src1_u64 = (const uint64_t *) &src1->masks;
      const uint64_t *src2_u64 = (const uint64_t *) &src2->masks;
      size_t i;
  
      for (i = 0; i < FLOW_U64S; i++) {
          dst_u64[i] = src1_u64[i] & src2_u64[i];
      }
  }
  
  /* Sets 'dst' as the bitwise OR of wildcards in 'src1' and 'src2'.  That
   * is, a bit or a field is wildcarded in 'dst' if it is neither
   * wildcarded in 'src1' nor 'src2'. */
  void
  flow_wildcards_or(struct flow_wildcards *dst,
                    const struct flow_wildcards *src1,
                    const struct flow_wildcards *src2)
  {
      uint64_t *dst_u64 = (uint64_t *) &dst->masks;
      const uint64_t *src1_u64 = (const uint64_t *) &src1->masks;
      const uint64_t *src2_u64 = (const uint64_t *) &src2->masks;
      size_t i;
  
      for (i = 0; i < FLOW_U64S; i++) {
          dst_u64[i] = src1_u64[i] | src2_u64[i];
      }
  }
  
  /* Returns a hash of the wildcards in 'wc'. */
  uint32_t
  flow_wildcards_hash(const struct flow_wildcards *wc, uint32_t basis)
  {
      return flow_hash(&wc->masks, basis);
  }
  
  /* Returns true if 'a' and 'b' represent the same wildcards, false if they are
   * different. */
  bool
  flow_wildcards_equal(const struct flow_wildcards *a,
                       const struct flow_wildcards *b)
  {
      return flow_equal(&a->masks, &b->masks);
  }
  
  /* Returns true if at least one bit or field is wildcarded in 'a' but not in
   * 'b', false otherwise. */
  bool
  flow_wildcards_has_extra(const struct flow_wildcards *a,
                           const struct flow_wildcards *b)
  {
      const uint64_t *a_u64 = (const uint64_t *) &a->masks;
      const uint64_t *b_u64 = (const uint64_t *) &b->masks;
      size_t i;
  
      for (i = 0; i < FLOW_U64S; i++) {
          if ((a_u64[i] & b_u64[i]) != b_u64[i]) {
              return true;
          }
      }
      return false;
  }
  
  /* Returns true if 'a' and 'b' are equal, except that 0-bits (wildcarded bits)
   * in 'wc' do not need to be equal in 'a' and 'b'. */
  bool
  flow_equal_except(const struct flow *a, const struct flow *b,
                    const struct flow_wildcards *wc)
  {
      const uint64_t *a_u64 = (const uint64_t *) a;
      const uint64_t *b_u64 = (const uint64_t *) b;
      const uint64_t *wc_u64 = (const uint64_t *) &wc->masks;
      size_t i;
  
      for (i = 0; i < FLOW_U64S; i++) {
          if ((a_u64[i] ^ b_u64[i]) & wc_u64[i]) {
              return false;
          }
      }
      return true;
  }
  
  /* Sets the wildcard mask for register 'idx' in 'wc' to 'mask'.
   * (A 0-bit indicates a wildcard bit.) */
  void
  flow_wildcards_set_reg_mask(struct flow_wildcards *wc, int idx, uint32_t mask)
  {
      wc->masks.regs[idx] = mask;
  }
  
  /* Sets the wildcard mask for register 'idx' in 'wc' to 'mask'.
   * (A 0-bit indicates a wildcard bit.) */
  void
  flow_wildcards_set_xreg_mask(struct flow_wildcards *wc, int idx, uint64_t mask)
  {
      flow_set_xreg(&wc->masks, idx, mask);
  }
  
  /* Sets the wildcard mask for register 'idx' in 'wc' to 'mask'.
   * (A 0-bit indicates a wildcard bit.) */
  void
  flow_wildcards_set_xxreg_mask(struct flow_wildcards *wc, int idx,
                                ovs_u128 mask)
  {
      flow_set_xxreg(&wc->masks, idx, mask);
  }
  
  /* Calculates the 5-tuple hash from the given miniflow.
   * This returns the same value as flow_hash_5tuple for the corresponding
   * flow. */
  uint32_t
  miniflow_hash_5tuple(const struct miniflow *flow, uint32_t basis)
  {
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
      uint32_t hash = basis;
  
      if (flow) {
          ovs_be16 dl_type = MINIFLOW_GET_BE16(flow, dl_type);
          uint8_t nw_proto;
  
          if (dl_type == htons(ETH_TYPE_IPV6)) {
              struct flowmap map = FLOWMAP_EMPTY_INITIALIZER;
              uint64_t value;
  
              FLOWMAP_SET(&map, ipv6_src);
              FLOWMAP_SET(&map, ipv6_dst);
  
              MINIFLOW_FOR_EACH_IN_FLOWMAP(value, flow, map) {
                  hash = hash_add64(hash, value);
              }
          } else if (dl_type == htons(ETH_TYPE_IP)
                     || dl_type == htons(ETH_TYPE_ARP)) {
              hash = hash_add(hash, MINIFLOW_GET_U32(flow, nw_src));
              hash = hash_add(hash, MINIFLOW_GET_U32(flow, nw_dst));
          } else {
              goto out;
          }
  
          nw_proto = MINIFLOW_GET_U8(flow, nw_proto);
          hash = hash_add(hash, nw_proto);
          if (nw_proto != IPPROTO_TCP && nw_proto != IPPROTO_UDP
              && nw_proto != IPPROTO_SCTP && nw_proto != IPPROTO_ICMP
              && nw_proto != IPPROTO_ICMPV6) {
              goto out;
          }
  
          /* Add both ports at once. */
          hash = hash_add(hash, (OVS_FORCE uint32_t) miniflow_get_ports(flow));
      }
  out:
      return hash_finish(hash, 42);
  }
  
  ASSERT_SEQUENTIAL_SAME_WORD(tp_src, tp_dst);
  ASSERT_SEQUENTIAL(ipv6_src, ipv6_dst);
  
  /* Calculates the 5-tuple hash from the given flow. */
  uint32_t
  flow_hash_5tuple(const struct flow *flow, uint32_t basis)
  {
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
      uint32_t hash = basis;
  
      if (flow) {
  
          if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              const uint64_t *flow_u64 = (const uint64_t *)flow;
              int ofs = offsetof(struct flow, ipv6_src) / 8;
              int end = ofs + 2 * sizeof flow->ipv6_src / 8;
  
              for (;ofs < end; ofs++) {
                  hash = hash_add64(hash, flow_u64[ofs]);
              }
          } else if (flow->dl_type == htons(ETH_TYPE_IP)
                     || flow->dl_type == htons(ETH_TYPE_ARP)) {
              hash = hash_add(hash, (OVS_FORCE uint32_t) flow->nw_src);
              hash = hash_add(hash, (OVS_FORCE uint32_t) flow->nw_dst);
          } else {
              goto out;
          }
  
          hash = hash_add(hash, flow->nw_proto);
          if (flow->nw_proto != IPPROTO_TCP && flow->nw_proto != IPPROTO_UDP
              && flow->nw_proto != IPPROTO_SCTP && flow->nw_proto != IPPROTO_ICMP
              && flow->nw_proto != IPPROTO_ICMPV6) {
              goto out;
          }
  
          /* Add both ports at once. */
          hash = hash_add(hash,
                          ((const uint32_t *)flow)[offsetof(struct flow, tp_src)
                                                   / sizeof(uint32_t)]);
      }
  out:
      return hash_finish(hash, 42); /* Arbitrary number. */
  }
  
  /* Hashes 'flow' based on its L2 through L4 protocol information. */
  uint32_t
  flow_hash_symmetric_l4(const struct flow *flow, uint32_t basis)
  {
      struct {
          union {
              ovs_be32 ipv4_addr;
              struct in6_addr ipv6_addr;
          };
          ovs_be16 eth_type;
          ovs_be16 vlan_tci;
          ovs_be16 tp_port;
          struct eth_addr eth_addr;
          uint8_t ip_proto;
      } fields;
  
      int i;
  
      memset(&fields, 0, sizeof fields);
      for (i = 0; i < ARRAY_SIZE(fields.eth_addr.be16); i++) {
          fields.eth_addr.be16[i] = flow->dl_src.be16[i] ^ flow->dl_dst.be16[i];
      }
      for (i = 0; i < FLOW_MAX_VLAN_HEADERS; i++) {
          fields.vlan_tci ^= flow->vlans[i].tci & htons(VLAN_VID_MASK);
      }
      fields.eth_type = flow->dl_type;
  
      /* UDP source and destination port are not taken into account because they
       * will not necessarily be symmetric in a bidirectional flow. */
      if (fields.eth_type == htons(ETH_TYPE_IP)) {
          fields.ipv4_addr = flow->nw_src ^ flow->nw_dst;
          fields.ip_proto = flow->nw_proto;
          if (fields.ip_proto == IPPROTO_TCP || fields.ip_proto == IPPROTO_SCTP) {
              fields.tp_port = flow->tp_src ^ flow->tp_dst;
          }
      } else if (fields.eth_type == htons(ETH_TYPE_IPV6)) {
          const uint8_t *a = &flow->ipv6_src.s6_addr[0];
          const uint8_t *b = &flow->ipv6_dst.s6_addr[0];
          uint8_t *ipv6_addr = &fields.ipv6_addr.s6_addr[0];
  
          for (i=0; i<16; i++) {
              ipv6_addr[i] = a[i] ^ b[i];
          }
          fields.ip_proto = flow->nw_proto;
          if (fields.ip_proto == IPPROTO_TCP || fields.ip_proto == IPPROTO_SCTP) {
              fields.tp_port = flow->tp_src ^ flow->tp_dst;
          }
      }
      return jhash_bytes(&fields, sizeof fields, basis);
  }
  
  /* Symmetrically Hashes non-IP 'flow' based on its L2 headers. */
  uint32_t
  flow_hash_symmetric_l2(const struct flow *flow, uint32_t basis)
  {
      union {
          struct {
              ovs_be16 eth_type;
              ovs_be16 vlan_tci;
              struct eth_addr eth_addr;
              ovs_be16 pad;
          };
          uint32_t word[3];
      } fields;
  
      uint32_t hash = basis;
      int i;
  
      if (flow->packet_type != htonl(PT_ETH)) {
          /* Cannot hash non-Ethernet flows */
          return 0;
      }
  
      for (i = 0; i < ARRAY_SIZE(fields.eth_addr.be16); i++) {
          fields.eth_addr.be16[i] =
                  flow->dl_src.be16[i] ^ flow->dl_dst.be16[i];
      }
      fields.vlan_tci = 0;
      for (i = 0; i < FLOW_MAX_VLAN_HEADERS; i++) {
          fields.vlan_tci ^= flow->vlans[i].tci & htons(VLAN_VID_MASK);
      }
      fields.eth_type = flow->dl_type;
      fields.pad = 0;
  
      hash = hash_add(hash, fields.word[0]);
      hash = hash_add(hash, fields.word[1]);
      hash = hash_add(hash, fields.word[2]);
      return hash_finish(hash, basis);
  }
  
  /* Hashes 'flow' based on its L3 through L4 protocol information */
  uint32_t
  flow_hash_symmetric_l3l4(const struct flow *flow, uint32_t basis,
                           bool inc_udp_ports)
  {
      uint32_t hash = basis;
  
      /* UDP source and destination port are also taken into account. */
      if (flow->dl_type == htons(ETH_TYPE_IP)) {
          hash = hash_add(hash,
                          (OVS_FORCE uint32_t) (flow->nw_src ^ flow->nw_dst));
      } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
          /* IPv6 addresses are 64-bit aligned inside struct flow. */
          const uint64_t *a = ALIGNED_CAST(uint64_t *, flow->ipv6_src.s6_addr);
          const uint64_t *b = ALIGNED_CAST(uint64_t *, flow->ipv6_dst.s6_addr);
  
          for (int i = 0; i < sizeof flow->ipv6_src / sizeof *a; i++) {
              hash = hash_add64(hash, a[i] ^ b[i]);
          }
      } else {
          /* Revert to hashing L2 headers */
          return flow_hash_symmetric_l2(flow, basis);
      }
      hash = hash_add(hash, flow->nw_proto);
      if (!(flow->nw_frag & FLOW_NW_FRAG_MASK)
          && (flow->nw_proto == IPPROTO_TCP || flow->nw_proto == IPPROTO_SCTP ||
              (inc_udp_ports && flow->nw_proto == IPPROTO_UDP))) {
          hash = hash_add(hash,
                          (OVS_FORCE uint16_t) (flow->tp_src ^ flow->tp_dst));
      }
  
      return hash_finish(hash, basis);
  }
  
  /* Hashes 'flow' based on its nw_dst and nw_src for multipath. */
  uint32_t
  flow_hash_symmetric_l3(const struct flow *flow, uint32_t basis)
  {
      struct {
          union {
              ovs_be32 ipv4_addr;
              struct in6_addr ipv6_addr;
          };
          ovs_be16 eth_type;
      } fields;
  
      int i;
  
      memset(&fields, 0, sizeof fields);
      fields.eth_type = flow->dl_type;
  
      if (fields.eth_type == htons(ETH_TYPE_IP)) {
          fields.ipv4_addr = flow->nw_src ^ flow->nw_dst;
      } else if (fields.eth_type == htons(ETH_TYPE_IPV6)) {
          const uint8_t *a = &flow->ipv6_src.s6_addr[0];
          const uint8_t *b = &flow->ipv6_dst.s6_addr[0];
          uint8_t *ipv6_addr = &fields.ipv6_addr.s6_addr[0];
  
          for (i = 0; i < 16; i++) {
              ipv6_addr[i] = a[i] ^ b[i];
          }
      }
      return jhash_bytes(&fields, sizeof fields, basis);
  }
  
  /* Initialize a flow with random fields that matter for nx_hash_fields. */
  void
  flow_random_hash_fields(struct flow *flow)
  {
      uint16_t rnd = random_uint16();
      int i;
  
      /* Initialize to all zeros. */
      memset(flow, 0, sizeof *flow);
  
      eth_addr_random(&flow->dl_src);
      eth_addr_random(&flow->dl_dst);
  
      for (i = 0; i < FLOW_MAX_VLAN_HEADERS; i++) {
          uint16_t vlan = random_uint16() & VLAN_VID_MASK;
          flow->vlans[i].tpid = htons(ETH_TYPE_VLAN_8021Q);
          flow->vlans[i].tci = htons(vlan | VLAN_CFI);
      }
  
      /* Make most of the random flows IPv4, some IPv6, and rest random. */
      flow->dl_type = rnd < 0x8000 ? htons(ETH_TYPE_IP) :
          rnd < 0xc000 ? htons(ETH_TYPE_IPV6) : (OVS_FORCE ovs_be16)rnd;
  
      if (dl_type_is_ip_any(flow->dl_type)) {
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              flow->nw_src = (OVS_FORCE ovs_be32)random_uint32();
              flow->nw_dst = (OVS_FORCE ovs_be32)random_uint32();
          } else {
              random_bytes(&flow->ipv6_src, sizeof flow->ipv6_src);
              random_bytes(&flow->ipv6_dst, sizeof flow->ipv6_dst);
          }
          /* Make most of IP flows TCP, some UDP or SCTP, and rest random. */
          rnd = random_uint16();
          flow->nw_proto = rnd < 0x8000 ? IPPROTO_TCP :
              rnd < 0xc000 ? IPPROTO_UDP :
              rnd < 0xd000 ? IPPROTO_SCTP : (uint8_t)rnd;
          if (flow->nw_proto == IPPROTO_TCP ||
              flow->nw_proto == IPPROTO_UDP ||
              flow->nw_proto == IPPROTO_SCTP) {
              flow->tp_src = (OVS_FORCE ovs_be16)random_uint16();
              flow->tp_dst = (OVS_FORCE ovs_be16)random_uint16();
          }
      }
  }
  
  /* Masks the fields in 'wc' that are used by the flow hash 'fields'. */
  void
  flow_mask_hash_fields(const struct flow *flow, struct flow_wildcards *wc,
                        enum nx_hash_fields fields)
  {
      int i;
      switch (fields) {
      case NX_HASH_FIELDS_ETH_SRC:
          memset(&wc->masks.dl_src, 0xff, sizeof wc->masks.dl_src);
          break;
  
      case NX_HASH_FIELDS_SYMMETRIC_L4:
          memset(&wc->masks.dl_src, 0xff, sizeof wc->masks.dl_src);
          memset(&wc->masks.dl_dst, 0xff, sizeof wc->masks.dl_dst);
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              memset(&wc->masks.nw_src, 0xff, sizeof wc->masks.nw_src);
              memset(&wc->masks.nw_dst, 0xff, sizeof wc->masks.nw_dst);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              memset(&wc->masks.ipv6_src, 0xff, sizeof wc->masks.ipv6_src);
              memset(&wc->masks.ipv6_dst, 0xff, sizeof wc->masks.ipv6_dst);
          }
          if (is_ip_any(flow)) {
              memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
              /* Unwildcard port only for non-UDP packets as udp port
               * numbers are not used in hash calculations.
               */
              if (flow->nw_proto != IPPROTO_UDP) {
                  flow_unwildcard_tp_ports(flow, wc);
              }
          }
          for (i = 0; i < FLOW_MAX_VLAN_HEADERS; i++) {
              wc->masks.vlans[i].tci |= htons(VLAN_VID_MASK | VLAN_CFI);
          }
          break;
      case NX_HASH_FIELDS_SYMMETRIC_L3L4_UDP:
          if (is_ip_any(flow) && flow->nw_proto == IPPROTO_UDP
              && !(flow->nw_frag & FLOW_NW_FRAG_MASK)) {
              memset(&wc->masks.tp_src, 0xff, sizeof wc->masks.tp_src);
              memset(&wc->masks.tp_dst, 0xff, sizeof wc->masks.tp_dst);
          }
          /* fall through */
      case NX_HASH_FIELDS_SYMMETRIC_L3L4:
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              memset(&wc->masks.nw_src, 0xff, sizeof wc->masks.nw_src);
              memset(&wc->masks.nw_dst, 0xff, sizeof wc->masks.nw_dst);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              memset(&wc->masks.ipv6_src, 0xff, sizeof wc->masks.ipv6_src);
              memset(&wc->masks.ipv6_dst, 0xff, sizeof wc->masks.ipv6_dst);
          } else {
              break; /* non-IP flow */
          }
          memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
          if ((flow->nw_proto == IPPROTO_TCP || flow->nw_proto == IPPROTO_SCTP)
               && !(flow->nw_frag & FLOW_NW_FRAG_MASK)) {
              memset(&wc->masks.tp_src, 0xff, sizeof wc->masks.tp_src);
              memset(&wc->masks.tp_dst, 0xff, sizeof wc->masks.tp_dst);
          }
          break;
  
      case NX_HASH_FIELDS_NW_SRC:
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              memset(&wc->masks.nw_src, 0xff, sizeof wc->masks.nw_src);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              memset(&wc->masks.ipv6_src, 0xff, sizeof wc->masks.ipv6_src);
          }
          break;
  
      case NX_HASH_FIELDS_NW_DST:
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              memset(&wc->masks.nw_dst, 0xff, sizeof wc->masks.nw_dst);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              memset(&wc->masks.ipv6_dst, 0xff, sizeof wc->masks.ipv6_dst);
          }
          break;
  
      case NX_HASH_FIELDS_SYMMETRIC_L3:
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              memset(&wc->masks.nw_src, 0xff, sizeof wc->masks.nw_src);
              memset(&wc->masks.nw_dst, 0xff, sizeof wc->masks.nw_dst);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              memset(&wc->masks.ipv6_src, 0xff, sizeof wc->masks.ipv6_src);
              memset(&wc->masks.ipv6_dst, 0xff, sizeof wc->masks.ipv6_dst);
          }
          break;
  
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Hashes the portions of 'flow' designated by 'fields'. */
  uint32_t
  flow_hash_fields(const struct flow *flow, enum nx_hash_fields fields,
                   uint16_t basis)
  {
      switch (fields) {
  
      case NX_HASH_FIELDS_ETH_SRC:
          return jhash_bytes(&flow->dl_src, sizeof flow->dl_src, basis);
  
      case NX_HASH_FIELDS_SYMMETRIC_L4:
          return flow_hash_symmetric_l4(flow, basis);
  
      case NX_HASH_FIELDS_SYMMETRIC_L3L4:
          return flow_hash_symmetric_l3l4(flow, basis, false);
  
      case NX_HASH_FIELDS_SYMMETRIC_L3L4_UDP:
          return flow_hash_symmetric_l3l4(flow, basis, true);
  
      case NX_HASH_FIELDS_NW_SRC:
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              return jhash_bytes(&flow->nw_src, sizeof flow->nw_src, basis);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              return jhash_bytes(&flow->ipv6_src, sizeof flow->ipv6_src, basis);
          } else {
              return basis;
          }
  
      case NX_HASH_FIELDS_NW_DST:
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              return jhash_bytes(&flow->nw_dst, sizeof flow->nw_dst, basis);
          } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              return jhash_bytes(&flow->ipv6_dst, sizeof flow->ipv6_dst, basis);
          } else {
              return basis;
          }
  
      case NX_HASH_FIELDS_SYMMETRIC_L3:
          return flow_hash_symmetric_l3(flow, basis);
      }
  
      OVS_NOT_REACHED();
  }
  
  /* Returns a string representation of 'fields'. */
  const char *
  flow_hash_fields_to_str(enum nx_hash_fields fields)
  {
      switch (fields) {
      case NX_HASH_FIELDS_ETH_SRC: return "eth_src";
      case NX_HASH_FIELDS_SYMMETRIC_L4: return "symmetric_l4";
      case NX_HASH_FIELDS_SYMMETRIC_L3L4: return "symmetric_l3l4";
      case NX_HASH_FIELDS_SYMMETRIC_L3L4_UDP: return "symmetric_l3l4+udp";
      case NX_HASH_FIELDS_NW_SRC: return "nw_src";
      case NX_HASH_FIELDS_NW_DST: return "nw_dst";
      case NX_HASH_FIELDS_SYMMETRIC_L3: return "symmetric_l3";
      default: return "<unknown>";
      }
  }
  
  /* Returns true if the value of 'fields' is supported. Otherwise false. */
  bool
  flow_hash_fields_valid(enum nx_hash_fields fields)
  {
      return fields == NX_HASH_FIELDS_ETH_SRC
          || fields == NX_HASH_FIELDS_SYMMETRIC_L4
          || fields == NX_HASH_FIELDS_SYMMETRIC_L3L4
          || fields == NX_HASH_FIELDS_SYMMETRIC_L3L4_UDP
          || fields == NX_HASH_FIELDS_NW_SRC
          || fields == NX_HASH_FIELDS_NW_DST
          || fields == NX_HASH_FIELDS_SYMMETRIC_L3;
  }
  
  /* Returns a hash value for the bits of 'flow' that are active based on
   * 'wc', given 'basis'. */
  uint32_t
  flow_hash_in_wildcards(const struct flow *flow,
                         const struct flow_wildcards *wc, uint32_t basis)
  {
      const uint64_t *wc_u64 = (const uint64_t *) &wc->masks;
      const uint64_t *flow_u64 = (const uint64_t *) flow;
      uint32_t hash;
      size_t i;
  
      hash = basis;
      for (i = 0; i < FLOW_U64S; i++) {
          hash = hash_add64(hash, flow_u64[i] & wc_u64[i]);
      }
      return hash_finish(hash, 8 * FLOW_U64S);
  }
  
  /* Sets the VLAN VID that 'flow' matches to 'vid', which is interpreted as an
   * OpenFlow 1.0 "dl_vlan" value:
   *
   *      - If it is in the range 0...4095, 'flow->vlans[0].tci' is set to match
   *        that VLAN.  Any existing PCP match is unchanged (it becomes 0 if
   *        'flow' previously matched packets without a VLAN header).
   *
   *      - If it is OFP_VLAN_NONE, 'flow->vlan_tci' is set to match a packet
   *        without a VLAN tag.
   *
   *      - Other values of 'vid' should not be used. */
  void
  flow_set_dl_vlan(struct flow *flow, ovs_be16 vid, int id)
  {
      if (vid == htons(OFP10_VLAN_NONE)) {
          flow->vlans[id].tci = htons(0);
      } else {
          vid &= htons(VLAN_VID_MASK);
          flow->vlans[id].tci &= ~htons(VLAN_VID_MASK);
          flow->vlans[id].tci |= htons(VLAN_CFI) | vid;
      }
  }
  
  /* Sets the VLAN header TPID, which must be either ETH_TYPE_VLAN_8021Q or
   * ETH_TYPE_VLAN_8021AD. */
  void
  flow_fix_vlan_tpid(struct flow *flow)
  {
      if (flow->vlans[0].tpid == htons(0) && flow->vlans[0].tci != 0) {
          flow->vlans[0].tpid = htons(ETH_TYPE_VLAN_8021Q);
      }
  }
  
  /* Sets the VLAN VID that 'flow' matches to 'vid', which is interpreted as an
   * OpenFlow 1.2 "vlan_vid" value, that is, the low 13 bits of 'vlan_tci' (VID
   * plus CFI). */
  void
  flow_set_vlan_vid(struct flow *flow, ovs_be16 vid)
  {
      ovs_be16 mask = htons(VLAN_VID_MASK | VLAN_CFI);
      flow->vlans[0].tci &= ~mask;
      flow->vlans[0].tci |= vid & mask;
  }
  
  /* Sets the VLAN PCP that 'flow' matches to 'pcp', which should be in the
   * range 0...7.
   *
   * This function has no effect on the VLAN ID that 'flow' matches.
   *
   * After calling this function, 'flow' will not match packets without a VLAN
   * header. */
  void
  flow_set_vlan_pcp(struct flow *flow, uint8_t pcp, int id)
  {
      pcp &= 0x07;
      flow->vlans[id].tci &= ~htons(VLAN_PCP_MASK);
      flow->vlans[id].tci |= htons((pcp << VLAN_PCP_SHIFT) | VLAN_CFI);
  }
  
  /* Counts the number of VLAN headers. */
  int
  flow_count_vlan_headers(const struct flow *flow)
  {
      int i;
  
      for (i = 0; i < FLOW_MAX_VLAN_HEADERS; i++) {
          if (!(flow->vlans[i].tci & htons(VLAN_CFI))) {
              break;
          }
      }
      return i;
  }
  
  /* Given '*p_an' and '*p_bn' pointing to one past the last VLAN header of
   * 'a' and 'b' respectively, skip common VLANs so that they point to the
   * first different VLAN counting from bottom. */
  void
  flow_skip_common_vlan_headers(const struct flow *a, int *p_an,
                                const struct flow *b, int *p_bn)
  {
      int an = *p_an, bn = *p_bn;
  
      for (an--, bn--; an >= 0 && bn >= 0; an--, bn--) {
          if (a->vlans[an].qtag != b->vlans[bn].qtag) {
              break;
          }
      }
      *p_an = an;
      *p_bn = bn;
  }
  
  void
  flow_pop_vlan(struct flow *flow, struct flow_wildcards *wc)
  {
      int n = flow_count_vlan_headers(flow);
      if (n > 1) {
          if (wc) {
              memset(&wc->masks.vlans[1], 0xff,
                     sizeof(union flow_vlan_hdr) * (n - 1));
          }
          memmove(&flow->vlans[0], &flow->vlans[1],
                  sizeof(union flow_vlan_hdr) * (n - 1));
      }
      if (n > 0) {
          memset(&flow->vlans[n - 1], 0, sizeof(union flow_vlan_hdr));
      }
  }
  
  void
  flow_push_vlan_uninit(struct flow *flow, struct flow_wildcards *wc)
  {
      if (wc) {
          int n = flow_count_vlan_headers(flow);
          if (n) {
              memset(wc->masks.vlans, 0xff, sizeof(union flow_vlan_hdr) * n);
          }
      }
      memmove(&flow->vlans[1], &flow->vlans[0],
              sizeof(union flow_vlan_hdr) * (FLOW_MAX_VLAN_HEADERS - 1));
      memset(&flow->vlans[0], 0, sizeof(union flow_vlan_hdr));
  }
  
  /* Returns the number of MPLS LSEs present in 'flow'
   *
   * Returns 0 if the 'dl_type' of 'flow' is not an MPLS ethernet type.
   * Otherwise traverses 'flow''s MPLS label stack stopping at the
   * first entry that has the BoS bit set. If no such entry exists then
   * the maximum number of LSEs that can be stored in 'flow' is returned.
   */
  int
  flow_count_mpls_labels(const struct flow *flow, struct flow_wildcards *wc)
  {
      /* dl_type is always masked. */
      if (eth_type_mpls(flow->dl_type)) {
          int i;
          int cnt;
  
          cnt = 0;
          for (i = 0; i < FLOW_MAX_MPLS_LABELS; i++) {
              if (wc) {
                  wc->masks.mpls_lse[i] |= htonl(MPLS_BOS_MASK);
              }
              if (flow->mpls_lse[i] & htonl(MPLS_BOS_MASK)) {
                  return i + 1;
              }
              if (flow->mpls_lse[i]) {
                  cnt++;
              }
          }
          return cnt;
      } else {
          return 0;
      }
  }
  
  /* Returns the number consecutive of MPLS LSEs, starting at the
   * innermost LSE, that are common in 'a' and 'b'.
   *
   * 'an' must be flow_count_mpls_labels(a).
   * 'bn' must be flow_count_mpls_labels(b).
   */
  int
  flow_count_common_mpls_labels(const struct flow *a, int an,
                                const struct flow *b, int bn,
                                struct flow_wildcards *wc)
  {
      int min_n = MIN(an, bn);
      if (min_n == 0) {
          return 0;
      } else {
          int common_n = 0;
          int a_last = an - 1;
          int b_last = bn - 1;
          int i;
  
          for (i = 0; i < min_n; i++) {
              if (wc) {
                  wc->masks.mpls_lse[a_last - i] = OVS_BE32_MAX;
                  wc->masks.mpls_lse[b_last - i] = OVS_BE32_MAX;
              }
              if (a->mpls_lse[a_last - i] != b->mpls_lse[b_last - i]) {
                  break;
              } else {
                  common_n++;
              }
          }
  
          return common_n;
      }
  }
  
  /* Adds a new outermost MPLS label to 'flow' and changes 'flow''s Ethernet type
   * to 'mpls_eth_type', which must be an MPLS Ethertype.
   *
   * If the new label is the first MPLS label in 'flow', it is generated as;
   *
   *     - label: 2, if 'flow' is IPv6, otherwise 0.
   *
   *     - TTL: IPv4 or IPv6 TTL, if present and nonzero, otherwise 64.
   *
   *     - TC: IPv4 or IPv6 TOS, if present, otherwise 0.
   *
   *     - BoS: 1.
   *
   * If the new label is the second or later label MPLS label in 'flow', it is
   * generated as;
   *
   *     - label: Copied from outer label.
   *
   *     - TTL: Copied from outer label.
   *
   *     - TC: Copied from outer label.
   *
   *     - BoS: 0.
   *
   * 'n' must be flow_count_mpls_labels(flow).  'n' must be less than
   * FLOW_MAX_MPLS_LABELS (because otherwise flow->mpls_lse[] would overflow).
   */
  void
  flow_push_mpls(struct flow *flow, int n, ovs_be16 mpls_eth_type,
                 struct flow_wildcards *wc, bool clear_flow_L3)
  {
      ovs_assert(eth_type_mpls(mpls_eth_type));
      ovs_assert(n < FLOW_MAX_MPLS_LABELS);
  
      if (n) {
          int i;
  
          if (wc) {
              memset(&wc->masks.mpls_lse, 0xff, sizeof *wc->masks.mpls_lse * n);
          }
          for (i = n; i >= 1; i--) {
              flow->mpls_lse[i] = flow->mpls_lse[i - 1];
          }
          flow->mpls_lse[0] = (flow->mpls_lse[1] & htonl(~MPLS_BOS_MASK));
      } else {
          int label = 0;          /* IPv4 Explicit Null. */
          int tc = 0;
          int ttl = 64;
  
          if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
              label = 2;
          }
  
          if (is_ip_any(flow)) {
              tc = (flow->nw_tos & IP_DSCP_MASK) >> 2;
              if (wc) {
                  wc->masks.nw_tos |= IP_DSCP_MASK;
                  wc->masks.nw_ttl = 0xff;
              }
  
              if (flow->nw_ttl) {
                  ttl = flow->nw_ttl;
              }
          }
  
          flow->mpls_lse[0] = set_mpls_lse_values(ttl, tc, 1, htonl(label));
  
          if (clear_flow_L3) {
              /* Clear all L3 and L4 fields and dp_hash. */
              BUILD_ASSERT(FLOW_WC_SEQ == 41);
              memset((char *) flow + FLOW_SEGMENT_2_ENDS_AT, 0,
                     sizeof(struct flow) - FLOW_SEGMENT_2_ENDS_AT);
              flow->dp_hash = 0;
          }
      }
      flow->dl_type = mpls_eth_type;
  }
  
  /* Tries to remove the outermost MPLS label from 'flow'.  Returns true if
   * successful, false otherwise.  On success, sets 'flow''s Ethernet type to
   * 'eth_type'.
   *
   * 'n' must be flow_count_mpls_labels(flow). */
  bool
  flow_pop_mpls(struct flow *flow, int n, ovs_be16 eth_type,
                struct flow_wildcards *wc)
  {
      int i;
  
      if (n == 0) {
          /* Nothing to pop. */
          return false;
      } else if (n == FLOW_MAX_MPLS_LABELS) {
          if (wc) {
              wc->masks.mpls_lse[n - 1] |= htonl(MPLS_BOS_MASK);
          }
          if (!(flow->mpls_lse[n - 1] & htonl(MPLS_BOS_MASK))) {
              /* Can't pop because don't know what to fill in mpls_lse[n - 1]. */
              return false;
          }
      }
  
      if (wc) {
          memset(&wc->masks.mpls_lse[1], 0xff,
                 sizeof *wc->masks.mpls_lse * (n - 1));
      }
      for (i = 1; i < n; i++) {
          flow->mpls_lse[i - 1] = flow->mpls_lse[i];
      }
      flow->mpls_lse[n - 1] = 0;
      flow->dl_type = eth_type;
      return true;
  }
  
  /* Sets the MPLS Label that 'flow' matches to 'label', which is interpreted
   * as an OpenFlow 1.1 "mpls_label" value. */
  void
  flow_set_mpls_label(struct flow *flow, int idx, ovs_be32 label)
  {
      set_mpls_lse_label(&flow->mpls_lse[idx], label);
  }
  
  /* Sets the MPLS TTL that 'flow' matches to 'ttl', which should be in the
   * range 0...255. */
  void
  flow_set_mpls_ttl(struct flow *flow, int idx, uint8_t ttl)
  {
      set_mpls_lse_ttl(&flow->mpls_lse[idx], ttl);
  }
  
  /* Sets the MPLS TC that 'flow' matches to 'tc', which should be in the
   * range 0...7. */
  void
  flow_set_mpls_tc(struct flow *flow, int idx, uint8_t tc)
  {
      set_mpls_lse_tc(&flow->mpls_lse[idx], tc);
  }
  
  /* Sets the MPLS BOS bit that 'flow' matches to which should be 0 or 1. */
  void
  flow_set_mpls_bos(struct flow *flow, int idx, uint8_t bos)
  {
      set_mpls_lse_bos(&flow->mpls_lse[idx], bos);
  }
  
  /* Sets the entire MPLS LSE. */
  void
  flow_set_mpls_lse(struct flow *flow, int idx, ovs_be32 lse)
  {
      flow->mpls_lse[idx] = lse;
  }
  
  static void
  flow_compose_l7(struct dp_packet *p, const void *l7, size_t l7_len)
  {
      if (l7_len) {
          if (l7) {
              dp_packet_put(p, l7, l7_len);
          } else {
              uint8_t *payload = dp_packet_put_uninit(p, l7_len);
              for (size_t i = 0; i < l7_len; i++) {
                  payload[i] = i;
              }
          }
      }
  }
  
  static size_t
  flow_compose_l4(struct dp_packet *p, const struct flow *flow,
                  const void *l7, size_t l7_len)
  {
      size_t orig_len = dp_packet_size(p);
  
      if (!(flow->nw_frag & FLOW_NW_FRAG_ANY)
          || !(flow->nw_frag & FLOW_NW_FRAG_LATER)) {
          if (flow->nw_proto == IPPROTO_TCP) {
              struct tcp_header *tcp = dp_packet_put_zeros(p, sizeof *tcp);
              tcp->tcp_src = flow->tp_src;
              tcp->tcp_dst = flow->tp_dst;
              tcp->tcp_ctl = TCP_CTL(ntohs(flow->tcp_flags), 5);
              if (!(flow->tcp_flags & htons(TCP_SYN | TCP_FIN | TCP_RST))) {
                  flow_compose_l7(p, l7, l7_len);
              }
          } else if (flow->nw_proto == IPPROTO_UDP) {
              struct udp_header *udp = dp_packet_put_zeros(p, sizeof *udp);
              udp->udp_src = flow->tp_src;
              udp->udp_dst = flow->tp_dst;
              udp->udp_len = htons(sizeof *udp + l7_len);
              flow_compose_l7(p, l7, l7_len);
          } else if (flow->nw_proto == IPPROTO_SCTP) {
              struct sctp_header *sctp = dp_packet_put_zeros(p, sizeof *sctp);
              sctp->sctp_src = flow->tp_src;
              sctp->sctp_dst = flow->tp_dst;
              /* XXX Someone should figure out what L7 data to include. */
          } else if (flow->nw_proto == IPPROTO_ICMP) {
              struct icmp_header *icmp = dp_packet_put_zeros(p, sizeof *icmp);
              icmp->icmp_type = ntohs(flow->tp_src);
              icmp->icmp_code = ntohs(flow->tp_dst);
              if ((icmp->icmp_type == ICMP4_ECHO_REQUEST ||
                   icmp->icmp_type == ICMP4_ECHO_REPLY)
                  && icmp->icmp_code == 0) {
                  flow_compose_l7(p, l7, l7_len);
              } else {
                  /* XXX Add inner IP packet for e.g. destination unreachable? */
              }
          } else if (flow->nw_proto == IPPROTO_IGMP) {
              struct igmp_header *igmp = dp_packet_put_zeros(p, sizeof *igmp);
              igmp->igmp_type = ntohs(flow->tp_src);
              igmp->igmp_code = ntohs(flow->tp_dst);
              put_16aligned_be32(&igmp->group, flow->igmp_group_ip4);
          } else if (flow->nw_proto == IPPROTO_ICMPV6) {
              struct icmp6_data_header *icmp6;
  
              icmp6 = dp_packet_put_zeros(p, sizeof *icmp6);
              icmp6->icmp6_base.icmp6_type = ntohs(flow->tp_src);
              icmp6->icmp6_base.icmp6_code = ntohs(flow->tp_dst);
              put_16aligned_be32(icmp6->icmp6_data.be32, flow->igmp_group_ip4);
  
              if (icmp6->icmp6_base.icmp6_code == 0 &&
                  (icmp6->icmp6_base.icmp6_type == ND_NEIGHBOR_SOLICIT ||
                   icmp6->icmp6_base.icmp6_type == ND_NEIGHBOR_ADVERT)) {
                  struct in6_addr *nd_target;
                  struct ovs_nd_lla_opt *lla_opt;
  
                  nd_target = dp_packet_put_zeros(p, sizeof *nd_target);
                  *nd_target = flow->nd_target;
  
                  if (!eth_addr_is_zero(flow->arp_sha)) {
                      lla_opt = dp_packet_put_zeros(p, 8);
                      lla_opt->len = 1;
                      lla_opt->type = ND_OPT_SOURCE_LINKADDR;
                      lla_opt->mac = flow->arp_sha;
                  }
                  if (!eth_addr_is_zero(flow->arp_tha)) {
                      lla_opt = dp_packet_put_zeros(p, 8);
                      lla_opt->len = 1;
                      lla_opt->type = ND_OPT_TARGET_LINKADDR;
                      lla_opt->mac = flow->arp_tha;
                  }
              } else if (icmp6->icmp6_base.icmp6_code == 0 &&
                         (icmp6->icmp6_base.icmp6_type == ICMP6_ECHO_REQUEST ||
                          icmp6->icmp6_base.icmp6_type == ICMP6_ECHO_REPLY)) {
                  flow_compose_l7(p, l7, l7_len);
              } else {
                  /* XXX Add inner IP packet for e.g. destination unreachable? */
              }
          }
      }
  
      return dp_packet_size(p) - orig_len;
  }
  
  static void
  flow_compose_l4_csum(struct dp_packet *p, const struct flow *flow,
                       uint32_t pseudo_hdr_csum)
  {
      size_t l4_len = (char *) dp_packet_tail(p) - (char *) dp_packet_l4(p);
  
      if (!(flow->nw_frag & FLOW_NW_FRAG_ANY)
          || !(flow->nw_frag & FLOW_NW_FRAG_LATER)) {
          if (flow->nw_proto == IPPROTO_TCP) {
              struct tcp_header *tcp = dp_packet_l4(p);
  
              tcp->tcp_csum = 0;
              tcp->tcp_csum = csum_finish(csum_continue(pseudo_hdr_csum,
                                                        tcp, l4_len));
          } else if (flow->nw_proto == IPPROTO_UDP) {
              struct udp_header *udp = dp_packet_l4(p);
  
              udp->udp_csum = 0;
              udp->udp_csum = csum_finish(csum_continue(pseudo_hdr_csum,
                                                        udp, l4_len));
              if (!udp->udp_csum) {
                  udp->udp_csum = htons(0xffff);
              }
          } else if (flow->nw_proto == IPPROTO_ICMP) {
              struct icmp_header *icmp = dp_packet_l4(p);
  
              icmp->icmp_csum = 0;
              icmp->icmp_csum = csum(icmp, l4_len);
          } else if (flow->nw_proto == IPPROTO_IGMP) {
              struct igmp_header *igmp = dp_packet_l4(p);
  
              igmp->igmp_csum = 0;
              igmp->igmp_csum = csum(igmp, l4_len);
          } else if (flow->nw_proto == IPPROTO_ICMPV6) {
              struct icmp6_data_header *icmp6 = dp_packet_l4(p);
  
              icmp6->icmp6_base.icmp6_cksum = 0;
              icmp6->icmp6_base.icmp6_cksum =
                  csum_finish(csum_continue(pseudo_hdr_csum, icmp6, l4_len));
          }
      }
  }
  
  /* Increase the size of packet composed by 'flow_compose_minimal'
   * up to 'size' bytes.  Fixes all the required packet headers like
   * ip/udp lengths and l3/l4 checksums.
   *
   * 'size' needs to be larger then the current packet size.  */
  void
  packet_expand(struct dp_packet *p, const struct flow *flow, size_t size)
  {
      size_t extra_size;
  
      ovs_assert(size > dp_packet_size(p));
  
      extra_size = size - dp_packet_size(p);
      dp_packet_put_zeros(p, extra_size);
  
      if (flow->dl_type == htons(FLOW_DL_TYPE_NONE)) {
          struct eth_header *eth = dp_packet_eth(p);
  
          eth->eth_type = htons(dp_packet_size(p));
      } else if (dl_type_is_ip_any(flow->dl_type)) {
          uint32_t pseudo_hdr_csum;
          size_t l4_len = (char *) dp_packet_tail(p) - (char *) dp_packet_l4(p);
  
          if (flow->dl_type == htons(ETH_TYPE_IP)) {
              struct ip_header *ip = dp_packet_l3(p);
  
              ip->ip_tot_len = htons(p->l4_ofs - p->l3_ofs + l4_len);
              ip->ip_csum = 0;
              ip->ip_csum = csum(ip, sizeof *ip);
  
              pseudo_hdr_csum = packet_csum_pseudoheader(ip);
          } else { /* ETH_TYPE_IPV6 */
              struct ovs_16aligned_ip6_hdr *nh = dp_packet_l3(p);
  
              nh->ip6_plen = htons(l4_len);
              pseudo_hdr_csum = packet_csum_pseudoheader6(nh);
          }
  
          if ((!(flow->nw_frag & FLOW_NW_FRAG_ANY)
               || !(flow->nw_frag & FLOW_NW_FRAG_LATER))
              && flow->nw_proto == IPPROTO_UDP) {
              struct udp_header *udp = dp_packet_l4(p);
  
              udp->udp_len = htons(l4_len + extra_size);
          }
          flow_compose_l4_csum(p, flow, pseudo_hdr_csum);
      }
  }
  
  /* Puts into 'p' a packet that flow_extract() would parse as having the given
   * 'flow'.
   *
   * (This is useful only for testing, obviously, and the packet isn't really
   * valid.  Lots of fields are just zeroed.)
   *
   * For packets whose protocols can encapsulate arbitrary L7 payloads, 'l7' and
   * 'l7_len' determine that payload:
   *
   *    - If 'l7_len' is zero, no payload is included.
   *
   *    - If 'l7_len' is nonzero and 'l7' is null, an arbitrary payload 'l7_len'
   *      bytes long is included.
   *
   *    - If 'l7_len' is nonzero and 'l7' is nonnull, the payload is copied
   *      from 'l7'. */
  void
  flow_compose(struct dp_packet *p, const struct flow *flow,
               const void *l7, size_t l7_len)
  {
      /* Add code to this function (or its callees) for emitting new fields or
       * protocols.  (This isn't essential, so it can be skipped for initial
       * testing.) */
      BUILD_ASSERT_DECL(FLOW_WC_SEQ == 41);
  
      uint32_t pseudo_hdr_csum;
      size_t l4_len;
  
      /* eth_compose() sets l3 pointer and makes sure it is 32-bit aligned. */
      eth_compose(p, flow->dl_dst, flow->dl_src, ntohs(flow->dl_type), 0);
      if (flow->dl_type == htons(FLOW_DL_TYPE_NONE)) {
          struct eth_header *eth = dp_packet_eth(p);
          eth->eth_type = htons(dp_packet_size(p));
          return;
      }
  
      for (int encaps = FLOW_MAX_VLAN_HEADERS - 1; encaps >= 0; encaps--) {
          if (flow->vlans[encaps].tci & htons(VLAN_CFI)) {
              eth_push_vlan(p, flow->vlans[encaps].tpid,
                            flow->vlans[encaps].tci);
          }
      }
  
      if (flow->dl_type == htons(ETH_TYPE_IP)) {
          struct ip_header *ip;
  
          ip = dp_packet_put_zeros(p, sizeof *ip);
          ip->ip_ihl_ver = IP_IHL_VER(5, 4);
          ip->ip_tos = flow->nw_tos;
          ip->ip_ttl = flow->nw_ttl;
          ip->ip_proto = flow->nw_proto;
          put_16aligned_be32(&ip->ip_src, flow->nw_src);
          put_16aligned_be32(&ip->ip_dst, flow->nw_dst);
  
          if (flow->nw_frag & FLOW_NW_FRAG_ANY) {
              ip->ip_frag_off |= htons(IP_MORE_FRAGMENTS);
              if (flow->nw_frag & FLOW_NW_FRAG_LATER) {
                  ip->ip_frag_off |= htons(100);
              }
          }
  
          dp_packet_set_l4(p, dp_packet_tail(p));
  
          l4_len = flow_compose_l4(p, flow, l7, l7_len);
  
          ip = dp_packet_l3(p);
          ip->ip_tot_len = htons(p->l4_ofs - p->l3_ofs + l4_len);
          /* Checksum has already been zeroed by put_zeros call. */
          ip->ip_csum = csum(ip, sizeof *ip);
  
          pseudo_hdr_csum = packet_csum_pseudoheader(ip);
          flow_compose_l4_csum(p, flow, pseudo_hdr_csum);
      } else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
          struct ovs_16aligned_ip6_hdr *nh;
  
          nh = dp_packet_put_zeros(p, sizeof *nh);
          put_16aligned_be32(&nh->ip6_flow, htonl(6 << 28) |
                             htonl(flow->nw_tos << 20) | flow->ipv6_label);
          nh->ip6_hlim = flow->nw_ttl;
          nh->ip6_nxt = flow->nw_proto;
  
          memcpy(&nh->ip6_src, &flow->ipv6_src, sizeof(nh->ip6_src));
          memcpy(&nh->ip6_dst, &flow->ipv6_dst, sizeof(nh->ip6_dst));
  
          dp_packet_set_l4(p, dp_packet_tail(p));
  
          l4_len = flow_compose_l4(p, flow, l7, l7_len);
  
          nh = dp_packet_l3(p);
          nh->ip6_plen = htons(l4_len);
  
          pseudo_hdr_csum = packet_csum_pseudoheader6(nh);
          flow_compose_l4_csum(p, flow, pseudo_hdr_csum);
      } else if (flow->dl_type == htons(ETH_TYPE_ARP) ||
                 flow->dl_type == htons(ETH_TYPE_RARP)) {
          struct arp_eth_header *arp;
  
          arp = dp_packet_put_zeros(p, sizeof *arp);
          dp_packet_set_l3(p, arp);
          arp->ar_hrd = htons(1);
          arp->ar_pro = htons(ETH_TYPE_IP);
          arp->ar_hln = ETH_ADDR_LEN;
          arp->ar_pln = 4;
          arp->ar_op = htons(flow->nw_proto);
  
          if (flow->nw_proto == ARP_OP_REQUEST ||
              flow->nw_proto == ARP_OP_REPLY) {
              put_16aligned_be32(&arp->ar_spa, flow->nw_src);
              put_16aligned_be32(&arp->ar_tpa, flow->nw_dst);
              arp->ar_sha = flow->arp_sha;
              arp->ar_tha = flow->arp_tha;
          }
      }
  
      if (eth_type_mpls(flow->dl_type)) {
          int n;
  
          p->l2_5_ofs = p->l3_ofs;
          for (n = 1; n < FLOW_MAX_MPLS_LABELS; n++) {
              if (flow->mpls_lse[n - 1] & htonl(MPLS_BOS_MASK)) {
                  break;
              }
          }
          while (n > 0) {
              push_mpls(p, flow->dl_type, flow->mpls_lse[--n]);
          }
      }
  }
  
  /* Compressed flow. */
  
  /* Completes an initialization of 'dst' as a miniflow copy of 'src' begun by
   * the caller.  The caller must have already computed 'dst->map' properly to
   * indicate the significant uint64_t elements of 'src'.
   *
   * Normally the significant elements are the ones that are non-zero.  However,
   * when a miniflow is initialized from a (mini)mask, the values can be zeroes,
   * so that the flow and mask always have the same maps. */
  void
  miniflow_init(struct miniflow *dst, const struct flow *src)
  {
      uint64_t *dst_u64 = miniflow_values(dst);
      size_t idx;
  
      FLOWMAP_FOR_EACH_INDEX(idx, dst->map) {
          *dst_u64++ = flow_u64_value(src, idx);
      }
  }
  
  /* Initialize the maps of 'flow' from 'src'. */
  void
  miniflow_map_init(struct miniflow *flow, const struct flow *src)
  {
      /* Initialize map, counting the number of nonzero elements. */
      flowmap_init(&flow->map);
      for (size_t i = 0; i < FLOW_U64S; i++) {
          if (flow_u64_value(src, i)) {
              flowmap_set(&flow->map, i, 1);
          }
      }
  }
  
  /* Allocates 'n' count of miniflows, consecutive in memory, initializing the
   * map of each from 'src'.
   * Returns the size of the miniflow data. */
  size_t
  miniflow_alloc(struct miniflow *dsts[], size_t n, const struct miniflow *src)
  {
      size_t n_values = miniflow_n_values(src);
      size_t data_size = MINIFLOW_VALUES_SIZE(n_values);
      struct miniflow *dst = xmalloc(n * (sizeof *src + data_size));
      size_t i;
  
      COVERAGE_INC(miniflow_malloc);
  
      for (i = 0; i < n; i++) {
          *dst = *src;   /* Copy maps. */
          dsts[i] = dst;
          dst += 1;      /* Just past the maps. */
          dst = (struct miniflow *)((uint64_t *)dst + n_values); /* Skip data. */
      }
      return data_size;
  }
  
  /* Returns a miniflow copy of 'src'.  The caller must eventually free() the
   * returned miniflow. */
  struct miniflow *
  miniflow_create(const struct flow *src)
  {
      struct miniflow tmp;
      struct miniflow *dst;
  
      miniflow_map_init(&tmp, src);
  
      miniflow_alloc(&dst, 1, &tmp);
      miniflow_init(dst, src);
      return dst;
  }
  
  /* Initializes 'dst' as a copy of 'src'.  The caller must have allocated
   * 'dst' to have inline space for 'n_values' data in 'src'. */
  void
  miniflow_clone(struct miniflow *dst, const struct miniflow *src,
                 size_t n_values)
  {
      *dst = *src;   /* Copy maps. */
      memcpy(miniflow_values(dst), miniflow_get_values(src),
             MINIFLOW_VALUES_SIZE(n_values));
  }
  
  /* Initializes 'dst' as a copy of 'src'. */
  void
  miniflow_expand(const struct miniflow *src, struct flow *dst)
  {
      memset(dst, 0, sizeof *dst);
      flow_union_with_miniflow(dst, src);
  }
  
  /* Returns true if 'a' and 'b' are equal miniflows, false otherwise. */
  bool
  miniflow_equal(const struct miniflow *a, const struct miniflow *b)
  {
      const uint64_t *ap = miniflow_get_values(a);
      const uint64_t *bp = miniflow_get_values(b);
  
      /* This is mostly called after a matching hash, so it is highly likely that
       * the maps are equal as well. */
      if (OVS_LIKELY(flowmap_equal(a->map, b->map))) {
          return !memcmp(ap, bp, miniflow_n_values(a) * sizeof *ap);
      } else {
          size_t idx;
  
          FLOWMAP_FOR_EACH_INDEX (idx, flowmap_or(a->map, b->map)) {
              if ((flowmap_is_set(&a->map, idx) ? *ap++ : 0)
                  != (flowmap_is_set(&b->map, idx) ? *bp++ : 0)) {
                  return false;
              }
          }
      }
  
      return true;
  }
  
  /* Returns false if 'a' and 'b' differ at the places where there are 1-bits
   * in 'mask', true otherwise. */
  bool
  miniflow_equal_in_minimask(const struct miniflow *a, const struct miniflow *b,
                             const struct minimask *mask)
  {
      const uint64_t *p = miniflow_get_values(&mask->masks);
      size_t idx;
  
      FLOWMAP_FOR_EACH_INDEX(idx, mask->masks.map) {
          if ((miniflow_get(a, idx) ^ miniflow_get(b, idx)) & *p++) {
              return false;
          }
      }
  
      return true;
  }
  
  /* Returns true if 'a' and 'b' are equal at the places where there are 1-bits
   * in 'mask', false if they differ. */
  bool
  miniflow_equal_flow_in_minimask(const struct miniflow *a, const struct flow *b,
                                  const struct minimask *mask)
  {
      const uint64_t *p = miniflow_get_values(&mask->masks);
      size_t idx;
  
      FLOWMAP_FOR_EACH_INDEX(idx, mask->masks.map) {
          if ((miniflow_get(a, idx) ^ flow_u64_value(b, idx)) & *p++) {
              return false;
          }
      }
  
      return true;
  }
  
  
  void
  minimask_init(struct minimask *mask, const struct flow_wildcards *wc)
  {
      miniflow_init(&mask->masks, &wc->masks);
  }
  
  /* Returns a minimask copy of 'wc'.  The caller must eventually free the
   * returned minimask with free(). */
  struct minimask *
  minimask_create(const struct flow_wildcards *wc)
  {
      return (struct minimask *)miniflow_create(&wc->masks);
  }
  
  /* Initializes 'dst_' as the bit-wise "and" of 'a_' and 'b_'.
   *
   * The caller must provide room for FLOW_U64S "uint64_t"s in 'storage', which
   * must follow '*dst_' in memory, for use by 'dst_'.  The caller must *not*
   * free 'dst_' free(). */
  void
  minimask_combine(struct minimask *dst_,
                   const struct minimask *a_, const struct minimask *b_,
                   uint64_t storage[FLOW_U64S])
  {
      struct miniflow *dst = &dst_->masks;
      uint64_t *dst_values = storage;
      const struct miniflow *a = &a_->masks;
      const struct miniflow *b = &b_->masks;
      size_t idx;
  
      flowmap_init(&dst->map);
  
      FLOWMAP_FOR_EACH_INDEX(idx, flowmap_and(a->map, b->map)) {
          /* Both 'a' and 'b' have non-zero data at 'idx'. */
          uint64_t mask = *miniflow_get__(a, idx) & *miniflow_get__(b, idx);
  
          if (mask) {
              flowmap_set(&dst->map, idx, 1);
              *dst_values++ = mask;
          }
      }
  }
  
  /* Initializes 'wc' as a copy of 'mask'. */
  void
  minimask_expand(const struct minimask *mask, struct flow_wildcards *wc)
  {
      miniflow_expand(&mask->masks, &wc->masks);
  }
  
  /* Returns true if 'a' and 'b' are the same flow mask, false otherwise.
   * Minimasks may not have zero data values, so for the minimasks to be the
   * same, they need to have the same map and the same data values. */
  bool
  minimask_equal(const struct minimask *a, const struct minimask *b)
  {
      /* At first glance, it might seem that this can be reasonably optimized
       * into a single memcmp() for the total size of the region.  Such an
       * optimization will work OK with most implementations of memcmp() that
       * proceed from the start of the regions to be compared to the end in
       * reasonably sized chunks.  However, memcmp() is not required to be
       * implemented that way, and an implementation that, for example, compares
       * all of the bytes in both regions without early exit when it finds a
       * difference, or one that compares, say, 64 bytes at a time, could access
       * an unmapped region of memory if minimasks 'a' and 'b' have different
       * lengths.  By first checking that the maps are the same with the first
       * memcmp(), we verify that 'a' and 'b' have the same length and therefore
       * ensure that the second memcmp() is safe. */
      return (!memcmp(a, b, sizeof *a)
              && !memcmp(a + 1, b + 1,
                         MINIFLOW_VALUES_SIZE(miniflow_n_values(&a->masks))));
  }
  
  /* Returns true if at least one bit matched by 'b' is wildcarded by 'a',
   * false otherwise. */
  bool
  minimask_has_extra(const struct minimask *a, const struct minimask *b)
  {
      const uint64_t *bp = miniflow_get_values(&b->masks);
      size_t idx;
  
      FLOWMAP_FOR_EACH_INDEX(idx, b->masks.map) {
          uint64_t b_u64 = *bp++;
  
          /* 'b_u64' is non-zero, check if the data in 'a' is either zero
           * or misses some of the bits in 'b_u64'. */
          if (!MINIFLOW_IN_MAP(&a->masks, idx)
              || ((*miniflow_get__(&a->masks, idx) & b_u64) != b_u64)) {
              return true; /* 'a' wildcards some bits 'b' doesn't. */
          }
      }
  
      return false;
  }
  
  void
  flow_limit_vlans(int vlan_limit)
  {
      if (vlan_limit <= 0) {
          flow_vlan_limit = FLOW_MAX_VLAN_HEADERS;
      } else {
          flow_vlan_limit = MIN(vlan_limit, FLOW_MAX_VLAN_HEADERS);
      }
  }
  
  struct netdev *
  flow_get_tunnel_netdev(struct flow_tnl *tunnel)
  {
      char iface[IFNAMSIZ];
      struct in6_addr ip6;
      struct in6_addr gw;
  
      if (tunnel->ip_src) {
          in6_addr_set_mapped_ipv4(&ip6, tunnel->ip_src);
      } else if (ipv6_addr_is_set(&tunnel->ipv6_src)) {
          ip6 = tunnel->ipv6_src;
      } else {
          return NULL;
      }
  
      if (!ovs_router_lookup(0, &ip6, iface, NULL, &gw)) {
          return NULL;
      }
  
      return netdev_from_name(iface);
  }
  