text: /*
   * Copyright (c) 2011, 2012, 2013, 2014 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 "meta-flow.h"
  
  #include <errno.h>
  #include <limits.h>
  #include <netinet/icmp6.h>
  #include <netinet/ip6.h>
  
  #include "classifier.h"
  #include "dynamic-string.h"
  #include "ofp-errors.h"
  #include "ofp-util.h"
  #include "ovs-thread.h"
  #include "packets.h"
  #include "random.h"
  #include "shash.h"
  #include "socket-util.h"
  #include "unaligned.h"
  #include "vlog.h"
  
  VLOG_DEFINE_THIS_MODULE(meta_flow);
  
  #define FLOW_U32OFS(FIELD)                                              \
      offsetof(struct flow, FIELD) % 4 ? -1 : offsetof(struct flow, FIELD) / 4
  
  #define MF_FIELD_SIZES(MEMBER)                  \
      sizeof ((union mf_value *)0)->MEMBER,       \
      8 * sizeof ((union mf_value *)0)->MEMBER
  
  extern const struct mf_field mf_fields[MFF_N_IDS]; /* Silence a warning. */
  
  const struct mf_field mf_fields[MFF_N_IDS] = {
      /* ## -------- ## */
      /* ## metadata ## */
      /* ## -------- ## */
  
      {
          MFF_DP_HASH, "dp_hash", NULL,
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_HEXADECIMAL,
          MFP_NONE,
          false,
          NXM_NX_DP_HASH, "NXM_NX_DP_HASH",
          NXM_NX_DP_HASH, "NXM_NX_DP_HASH", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_RECIRC_ID, "recirc_id", NULL,
          MF_FIELD_SIZES(be32),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_NONE,
          false,
          NXM_NX_RECIRC_ID, "NXM_NX_RECIRC_ID",
          NXM_NX_RECIRC_ID, "NXM_NX_RECIRC_ID", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_TUN_ID, "tun_id", "tunnel_id",
          MF_FIELD_SIZES(be64),
          MFM_FULLY,
          MFS_HEXADECIMAL,
          MFP_NONE,
          true,
          NXM_NX_TUN_ID, "NXM_NX_TUN_ID",
          OXM_OF_TUNNEL_ID, "OXM_OF_TUNNEL_ID", OFP13_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          FLOW_U32OFS(tunnel.tun_id),
      }, {
          MFF_TUN_SRC, "tun_src", NULL,
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_IPV4,
          MFP_NONE,
          true,
          NXM_NX_TUN_IPV4_SRC, "NXM_NX_TUN_IPV4_SRC",
          NXM_NX_TUN_IPV4_SRC, "NXM_NX_TUN_IPV4_SRC", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          FLOW_U32OFS(tunnel.ip_src),
      }, {
          MFF_TUN_DST, "tun_dst", NULL,
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_IPV4,
          MFP_NONE,
          true,
          NXM_NX_TUN_IPV4_DST, "NXM_NX_TUN_IPV4_DST",
          NXM_NX_TUN_IPV4_DST, "NXM_NX_TUN_IPV4_DST", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          FLOW_U32OFS(tunnel.ip_dst),
      }, {
          MFF_TUN_FLAGS, "tun_flags", NULL,
          MF_FIELD_SIZES(be16),
          MFM_NONE,
          MFS_TNL_FLAGS,
          MFP_NONE,
          false,
          0, NULL,
          0, NULL, 0,
          OFPUTIL_P_NONE,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_TUN_TTL, "tun_ttl", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_NONE,
          false,
          0, NULL,
          0, NULL, 0,
          OFPUTIL_P_NONE,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_TUN_TOS, "tun_tos", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_NONE,
          false,
          0, NULL,
          0, NULL, 0,
          OFPUTIL_P_NONE,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_METADATA, "metadata", NULL,
          MF_FIELD_SIZES(be64),
          MFM_FULLY,
          MFS_HEXADECIMAL,
          MFP_NONE,
          true,
          OXM_OF_METADATA, "OXM_OF_METADATA",
          OXM_OF_METADATA, "OXM_OF_METADATA", OFP12_VERSION,
          OFPUTIL_P_NXM_OF11_UP,
          OFPUTIL_P_NXM_OF11_UP,
          -1,
      }, {
          MFF_IN_PORT, "in_port", NULL,
          MF_FIELD_SIZES(be16),
          MFM_NONE,
          MFS_OFP_PORT,
          MFP_NONE,
          true,
          NXM_OF_IN_PORT, "NXM_OF_IN_PORT",
          NXM_OF_IN_PORT, "NXM_OF_IN_PORT", 0,
          OFPUTIL_P_ANY,   /* OF11+ via mapping to 32 bits. */
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_IN_PORT_OXM, "in_port_oxm", NULL,
          MF_FIELD_SIZES(be32),
          MFM_NONE,
          MFS_OFP_PORT_OXM,
          MFP_NONE,
          true,
          OXM_OF_IN_PORT, "OXM_OF_IN_PORT",
          OXM_OF_IN_PORT, "OXM_OF_IN_PORT", OFP12_VERSION,
          OFPUTIL_P_OF11_UP,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_SKB_PRIORITY, "skb_priority", NULL,
          MF_FIELD_SIZES(be32),
          MFM_NONE,
          MFS_HEXADECIMAL,
          MFP_NONE,
          false,
          0, NULL,
          0, NULL, 0,
          OFPUTIL_P_NONE,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_PKT_MARK, "pkt_mark", NULL,
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_HEXADECIMAL,
          MFP_NONE,
          true,
          NXM_NX_PKT_MARK, "NXM_NX_PKT_MARK",
          NXM_NX_PKT_MARK, "NXM_NX_PKT_MARK", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
  #define REGISTER(IDX)                           \
      {                                           \
          MFF_REG##IDX, "reg" #IDX, NULL,         \
          MF_FIELD_SIZES(be32),                   \
          MFM_FULLY,                              \
          MFS_HEXADECIMAL,                        \
          MFP_NONE,                               \
          true,                                   \
          NXM_NX_REG(IDX), "NXM_NX_REG" #IDX,     \
          NXM_NX_REG(IDX), "NXM_NX_REG" #IDX, 0,  \
          OFPUTIL_P_NXM_OXM_ANY,                  \
          OFPUTIL_P_NXM_OXM_ANY,                  \
          -1,                                     \
      }
  #if FLOW_N_REGS == 8
      REGISTER(0),
      REGISTER(1),
      REGISTER(2),
      REGISTER(3),
      REGISTER(4),
      REGISTER(5),
      REGISTER(6),
      REGISTER(7),
  #else
  #error "Need to update mf_fields[] to match FLOW_N_REGS"
  #endif
  
  #define XREGISTER(IDX)                                              \
      {                                                               \
          MFF_XREG##IDX, "xreg" #IDX, NULL,                           \
          MF_FIELD_SIZES(be64),                                       \
          MFM_FULLY,                                                  \
          MFS_HEXADECIMAL,                                            \
          MFP_NONE,                                                   \
          true,                                                       \
          OXM_OF_PKT_REG(IDX), "OXM_OF_PKT_REG" #IDX,                 \
          OXM_OF_PKT_REG(IDX), "OXM_OF_PKT_REG" #IDX, OFP15_VERSION,  \
          OFPUTIL_P_NXM_OXM_ANY,                                      \
          OFPUTIL_P_NXM_OXM_ANY,                                      \
          -1,                                                         \
      }
  #if FLOW_N_XREGS == 4
      XREGISTER(0),
      XREGISTER(1),
      XREGISTER(2),
      XREGISTER(3),
  #else
  #error "Need to update mf_fields[] to match FLOW_N_XREGS"
  #endif
  
      /* ## -- ## */
      /* ## L2 ## */
      /* ## -- ## */
  
      {
          MFF_ETH_SRC, "eth_src", "dl_src",
          MF_FIELD_SIZES(mac),
          MFM_FULLY,
          MFS_ETHERNET,
          MFP_NONE,
          true,
          NXM_OF_ETH_SRC, "NXM_OF_ETH_SRC",
          OXM_OF_ETH_SRC, "OXM_OF_ETH_SRC", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OF11_UP,   /* Bitwise masking only with NXM and OF11+! */
          -1,
      }, {
          MFF_ETH_DST, "eth_dst", "dl_dst",
          MF_FIELD_SIZES(mac),
          MFM_FULLY,
          MFS_ETHERNET,
          MFP_NONE,
          true,
          NXM_OF_ETH_DST, "NXM_OF_ETH_DST",
          OXM_OF_ETH_DST, "OXM_OF_ETH_DST", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OF11_UP,   /* Bitwise masking only with NXM and OF11+! */
          -1,
      }, {
          MFF_ETH_TYPE, "eth_type", "dl_type",
          MF_FIELD_SIZES(be16),
          MFM_NONE,
          MFS_HEXADECIMAL,
          MFP_NONE,
          false,
          NXM_OF_ETH_TYPE, "NXM_OF_ETH_TYPE",
          OXM_OF_ETH_TYPE, "OXM_OF_ETH_TYPE", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NONE,
          -1,
      },
  
      {
          MFF_VLAN_TCI, "vlan_tci", NULL,
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_HEXADECIMAL,
          MFP_NONE,
          true,
          NXM_OF_VLAN_TCI, "NXM_OF_VLAN_TCI",
          NXM_OF_VLAN_TCI, "NXM_OF_VLAN_TCI", 0,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_DL_VLAN, "dl_vlan", NULL,
          sizeof(ovs_be16), 12,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_NONE,
          true,
          0, NULL,
          0, NULL, 0,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_VLAN_VID, "vlan_vid", NULL,
          sizeof(ovs_be16), 12,
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_NONE,
          true,
          OXM_OF_VLAN_VID, "OXM_OF_VLAN_VID",
          OXM_OF_VLAN_VID, "OXM_OF_VLAN_VID", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_DL_VLAN_PCP, "dl_vlan_pcp", NULL,
          1, 3,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_NONE,
          true,
          0, NULL,
          0, NULL, 0,
          OFPUTIL_P_ANY,   /* Will be mapped to NXM and OXM. */
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_VLAN_PCP, "vlan_pcp", NULL,
          1, 3,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_VLAN_VID,
          true,
          OXM_OF_VLAN_PCP, "OXM_OF_VLAN_PCP",
          OXM_OF_VLAN_PCP, "OXM_OF_VLAN_PCP", OFP12_VERSION,
          OFPUTIL_P_ANY,   /* Will be mapped to OF10 and NXM. */
          OFPUTIL_P_NONE,
          -1,
      },
  
      /* ## ---- ## */
      /* ## L2.5 ## */
      /* ## ---- ## */
      {
          MFF_MPLS_LABEL, "mpls_label", NULL,
          4, 20,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_MPLS,
          true,
          OXM_OF_MPLS_LABEL, "OXM_OF_MPLS_LABEL",
          OXM_OF_MPLS_LABEL, "OXM_OF_MPLS_LABEL", OFP12_VERSION,
          OFPUTIL_P_NXM_OF11_UP,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_MPLS_TC, "mpls_tc", NULL,
          1, 3,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_MPLS,
          true,
          OXM_OF_MPLS_TC, "OXM_OF_MPLS_TC",
          OXM_OF_MPLS_TC, "OXM_OF_MPLS_TC", OFP12_VERSION,
          OFPUTIL_P_NXM_OF11_UP,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_MPLS_BOS, "mpls_bos", NULL,
          1, 1,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_MPLS,
          false,
          OXM_OF_MPLS_BOS, "OXM_OF_MPLS_BOS",
          OXM_OF_MPLS_BOS, "OXM_OF_MPLS_BOS", OFP13_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NONE,
          -1,
      },
  
      /* ## -- ## */
      /* ## L3 ## */
      /* ## -- ## */
  
      {
          MFF_IPV4_SRC, "ip_src", "nw_src",
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_IPV4,
          MFP_IPV4,
          true,
          NXM_OF_IP_SRC, "NXM_OF_IP_SRC",
          OXM_OF_IPV4_SRC, "OXM_OF_IPV4_SRC", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OF11_UP,
          FLOW_U32OFS(nw_src),
      }, {
          MFF_IPV4_DST, "ip_dst", "nw_dst",
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_IPV4,
          MFP_IPV4,
          true,
          NXM_OF_IP_DST, "NXM_OF_IP_DST",
          OXM_OF_IPV4_DST, "OXM_OF_IPV4_DST", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OF11_UP,
          FLOW_U32OFS(nw_dst),
      },
  
      {
          MFF_IPV6_SRC, "ipv6_src", NULL,
          MF_FIELD_SIZES(ipv6),
          MFM_FULLY,
          MFS_IPV6,
          MFP_IPV6,
          true,
          NXM_NX_IPV6_SRC, "NXM_NX_IPV6_SRC",
          OXM_OF_IPV6_SRC, "OXM_OF_IPV6_SRC", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          FLOW_U32OFS(ipv6_src),
      }, {
          MFF_IPV6_DST, "ipv6_dst", NULL,
          MF_FIELD_SIZES(ipv6),
          MFM_FULLY,
          MFS_IPV6,
          MFP_IPV6,
          true,
          NXM_NX_IPV6_DST, "NXM_NX_IPV6_DST",
          OXM_OF_IPV6_DST, "OXM_OF_IPV6_DST", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          FLOW_U32OFS(ipv6_dst),
      },
      {
          MFF_IPV6_LABEL, "ipv6_label", NULL,
          4, 20,
          MFM_FULLY,
          MFS_HEXADECIMAL,
          MFP_IPV6,
          false,
          NXM_NX_IPV6_LABEL, "NXM_NX_IPV6_LABEL",
          OXM_OF_IPV6_FLABEL, "OXM_OF_IPV6_FLABEL", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
      {
          MFF_IP_PROTO, "nw_proto", "ip_proto",
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_IP_ANY,
          false,
          NXM_OF_IP_PROTO, "NXM_OF_IP_PROTO",
          OXM_OF_IP_PROTO, "OXM_OF_IP_PROTO", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_IP_DSCP, "nw_tos", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_IP_ANY,
          true,
          NXM_OF_IP_TOS, "NXM_OF_IP_TOS",
          NXM_OF_IP_TOS, "NXM_OF_IP_TOS", 0,
          OFPUTIL_P_ANY,   /* Will be shifted for OXM. */
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_IP_DSCP_SHIFTED, "ip_dscp", NULL,
          1, 6,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_IP_ANY,
          true,
          OXM_OF_IP_DSCP, "OXM_OF_IP_DSCP",
          OXM_OF_IP_DSCP, "OXM_OF_IP_DSCP", OFP12_VERSION,
          OFPUTIL_P_ANY,   /* Will be shifted for non-OXM. */
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_IP_ECN, "nw_ecn", "ip_ecn",
          1, 2,
          MFM_NONE,
          MFS_DECIMAL,
          MFP_IP_ANY,
          true,
          NXM_NX_IP_ECN, "NXM_NX_IP_ECN",
          OXM_OF_IP_ECN, "OXM_OF_IP_ECN", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_IP_TTL, "nw_ttl", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_IP_ANY,
          true,
          NXM_NX_IP_TTL, "NXM_NX_IP_TTL",
          NXM_NX_IP_TTL, "NXM_NX_IP_TTL", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_IP_FRAG, "ip_frag", NULL,
          1, 2,
          MFM_FULLY,
          MFS_FRAG,
          MFP_IP_ANY,
          false,
          NXM_NX_IP_FRAG, "NXM_NX_IP_FRAG",
          NXM_NX_IP_FRAG, "NXM_NX_IP_FRAG", 0,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
      {
          MFF_ARP_OP, "arp_op", NULL,
          MF_FIELD_SIZES(be16),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_ARP,
          true,
          NXM_OF_ARP_OP, "NXM_OF_ARP_OP",
          OXM_OF_ARP_OP, "OXM_OF_ARP_OP", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_ARP_SPA, "arp_spa", NULL,
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_IPV4,
          MFP_ARP,
          true,
          NXM_OF_ARP_SPA, "NXM_OF_ARP_SPA",
          OXM_OF_ARP_SPA, "OXM_OF_ARP_SPA", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OF11_UP,
          -1,
      }, {
          MFF_ARP_TPA, "arp_tpa", NULL,
          MF_FIELD_SIZES(be32),
          MFM_FULLY,
          MFS_IPV4,
          MFP_ARP,
          true,
          NXM_OF_ARP_TPA, "NXM_OF_ARP_TPA",
          OXM_OF_ARP_TPA, "OXM_OF_ARP_TPA", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OF11_UP,
          -1,
      }, {
          MFF_ARP_SHA, "arp_sha", NULL,
          MF_FIELD_SIZES(mac),
          MFM_FULLY,
          MFS_ETHERNET,
          MFP_ARP,
          true,
          NXM_NX_ARP_SHA, "NXM_NX_ARP_SHA",
          OXM_OF_ARP_SHA, "OXM_OF_ARP_SHA", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_ARP_THA, "arp_tha", NULL,
          MF_FIELD_SIZES(mac),
          MFM_FULLY,
          MFS_ETHERNET,
          MFP_ARP,
          true,
          NXM_NX_ARP_THA, "NXM_NX_ARP_THA",
          OXM_OF_ARP_THA, "OXM_OF_ARP_THA", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
      /* ## -- ## */
      /* ## L4 ## */
      /* ## -- ## */
  
      {
          MFF_TCP_SRC, "tcp_src", "tp_src",
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_TCP,
          true,
          NXM_OF_TCP_SRC, "NXM_OF_TCP_SRC",
          OXM_OF_TCP_SRC, "OXM_OF_TCP_SRC", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_TCP_DST, "tcp_dst", "tp_dst",
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_TCP,
          true,
          NXM_OF_TCP_DST, "NXM_OF_TCP_DST",
          OXM_OF_TCP_DST, "OXM_OF_TCP_DST", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_TCP_FLAGS, "tcp_flags", NULL,
          2, 12,
          MFM_FULLY,
          MFS_TCP_FLAGS,
          MFP_TCP,
          false,
          NXM_NX_TCP_FLAGS, "NXM_NX_TCP_FLAGS",
          OXM_OF_TCP_FLAGS, "OXM_OF_TCP_FLAGS", OFP15_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
      {
          MFF_UDP_SRC, "udp_src", NULL,
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_UDP,
          true,
          NXM_OF_UDP_SRC, "NXM_OF_UDP_SRC",
          OXM_OF_UDP_SRC, "OXM_OF_UDP_SRC", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_UDP_DST, "udp_dst", NULL,
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_UDP,
          true,
          NXM_OF_UDP_DST, "NXM_OF_UDP_DST",
          OXM_OF_UDP_DST, "OXM_OF_UDP_DST", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
      {
          MFF_SCTP_SRC, "sctp_src", NULL,
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_SCTP,
          true,
          OXM_OF_SCTP_SRC, "OXM_OF_SCTP_SRC",
          OXM_OF_SCTP_SRC, "OXM_OF_SCTP_SRC", OFP12_VERSION,
          OFPUTIL_P_NXM_OF11_UP,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_SCTP_DST, "sctp_dst", NULL,
          MF_FIELD_SIZES(be16),
          MFM_FULLY,
          MFS_DECIMAL,
          MFP_SCTP,
          true,
          OXM_OF_SCTP_DST, "OXM_OF_SCTP_DST",
          OXM_OF_SCTP_DST, "OXM_OF_SCTP_DST", OFP12_VERSION,
          OFPUTIL_P_NXM_OF11_UP,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      },
  
      {
          MFF_ICMPV4_TYPE, "icmp_type", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_ICMPV4,
          false,
          NXM_OF_ICMP_TYPE, "NXM_OF_ICMP_TYPE",
          OXM_OF_ICMPV4_TYPE, "OXM_OF_ICMPV4_TYPE", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_ICMPV4_CODE, "icmp_code", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_ICMPV4,
          false,
          NXM_OF_ICMP_CODE, "NXM_OF_ICMP_CODE",
          OXM_OF_ICMPV4_CODE, "OXM_OF_ICMPV4_CODE", OFP12_VERSION,
          OFPUTIL_P_ANY,
          OFPUTIL_P_NONE,
          -1,
      },
  
      {
          MFF_ICMPV6_TYPE, "icmpv6_type", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_ICMPV6,
          false,
          NXM_NX_ICMPV6_TYPE, "NXM_NX_ICMPV6_TYPE",
          OXM_OF_ICMPV6_TYPE, "OXM_OF_ICMPV6_TYPE", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NONE,
          -1,
      }, {
          MFF_ICMPV6_CODE, "icmpv6_code", NULL,
          MF_FIELD_SIZES(u8),
          MFM_NONE,
          MFS_DECIMAL,
          MFP_ICMPV6,
          false,
          NXM_NX_ICMPV6_CODE, "NXM_NX_ICMPV6_CODE",
          OXM_OF_ICMPV6_CODE, "OXM_OF_ICMPV6_CODE", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NONE,
          -1,
      },
  
      /* ## ---- ## */
      /* ## L"5" ## */
      /* ## ---- ## */
  
      {
          MFF_ND_TARGET, "nd_target", NULL,
          MF_FIELD_SIZES(ipv6),
          MFM_FULLY,
          MFS_IPV6,
          MFP_ND,
          false,
          NXM_NX_ND_TARGET, "NXM_NX_ND_TARGET",
          OXM_OF_IPV6_ND_TARGET, "OXM_OF_IPV6_ND_TARGET", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_ND_SLL, "nd_sll", NULL,
          MF_FIELD_SIZES(mac),
          MFM_FULLY,
          MFS_ETHERNET,
          MFP_ND_SOLICIT,
          false,
          NXM_NX_ND_SLL, "NXM_NX_ND_SLL",
          OXM_OF_IPV6_ND_SLL, "OXM_OF_IPV6_ND_SLL", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }, {
          MFF_ND_TLL, "nd_tll", NULL,
          MF_FIELD_SIZES(mac),
          MFM_FULLY,
          MFS_ETHERNET,
          MFP_ND_ADVERT,
          false,
          NXM_NX_ND_TLL, "NXM_NX_ND_TLL",
          OXM_OF_IPV6_ND_TLL, "OXM_OF_IPV6_ND_TLL", OFP12_VERSION,
          OFPUTIL_P_NXM_OXM_ANY,
          OFPUTIL_P_NXM_OXM_ANY,
          -1,
      }
  };
  
  /* Maps an NXM or OXM header value to an mf_field. */
  struct nxm_field {
      struct hmap_node hmap_node; /* In 'all_fields' hmap. */
      uint32_t header;            /* NXM or OXM header value. */
      const struct mf_field *mf;
  };
  
  /* Contains 'struct nxm_field's. */
  static struct hmap all_fields;
  
  /* Maps from an mf_field's 'name' or 'extra_name' to the mf_field. */
  static struct shash mf_by_name;
  
  /* Rate limit for parse errors.  These always indicate a bug in an OpenFlow
   * controller and so there's not much point in showing a lot of them. */
  static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  
  const struct mf_field *mf_from_nxm_header__(uint32_t header);
  static void nxm_init(void);
  
  /* Returns the field with the given 'name', or a null pointer if no field has
   * that name. */
  const struct mf_field *
  mf_from_name(const char *name)
  {
      nxm_init();
      return shash_find_data(&mf_by_name, name);
  }
  
  static void
  add_nxm_field(uint32_t header, const struct mf_field *mf)
  {
      struct nxm_field *f;
  
      f = xmalloc(sizeof *f);
      hmap_insert(&all_fields, &f->hmap_node, hash_int(header, 0));
      f->header = header;
      f->mf = mf;
  }
  
  static void
  nxm_init_add_field(const struct mf_field *mf, uint32_t header)
  {
      if (header) {
          ovs_assert(!mf_from_nxm_header__(header));
          add_nxm_field(header, mf);
          if (mf->maskable != MFM_NONE) {
              add_nxm_field(NXM_MAKE_WILD_HEADER(header), mf);
          }
      }
  }
  
  static void
  nxm_do_init(void)
  {
      int i;
  
      hmap_init(&all_fields);
      shash_init(&mf_by_name);
      for (i = 0; i < MFF_N_IDS; i++) {
          const struct mf_field *mf = &mf_fields[i];
  
          ovs_assert(mf->id == i); /* Fields must be in the enum order. */
  
          nxm_init_add_field(mf, mf->nxm_header);
          if (mf->oxm_header != mf->nxm_header) {
              nxm_init_add_field(mf, mf->oxm_header);
          }
  
          shash_add_once(&mf_by_name, mf->name, mf);
          if (mf->extra_name) {
              shash_add_once(&mf_by_name, mf->extra_name, mf);
          }
      }
  }
  
  static void
  nxm_init(void)
  {
      static pthread_once_t once = PTHREAD_ONCE_INIT;
      pthread_once(&once, nxm_do_init);
  }
  
  const struct mf_field *
  mf_from_nxm_header(uint32_t header)
  {
      nxm_init();
      return mf_from_nxm_header__(header);
  }
  
  const struct mf_field *
  mf_from_nxm_header__(uint32_t header)
  {
      const struct nxm_field *f;
  
      HMAP_FOR_EACH_IN_BUCKET (f, hmap_node, hash_int(header, 0), &all_fields) {
          if (f->header == header) {
              return f->mf;
          }
      }
  
      return NULL;
  }
  
  uint32_t
  mf_oxm_header(enum mf_field_id id, enum ofp_version oxm_version)
  {
      const struct mf_field *field = mf_from_id(id);
  
      return (oxm_version >= field->oxm_version
              ? field->oxm_header
              : field->nxm_header);
  }
  
  /* Returns true if 'wc' wildcards all the bits in field 'mf', false if 'wc'
   * specifies at least one bit in the field.
   *
   * The caller is responsible for ensuring that 'wc' corresponds to a flow that
   * meets 'mf''s prerequisites. */
  bool
  mf_is_all_wild(const struct mf_field *mf, const struct flow_wildcards *wc)
  {
      switch (mf->id) {
      case MFF_DP_HASH:
          return !wc->masks.dp_hash;
      case MFF_RECIRC_ID:
          return !wc->masks.recirc_id;
      case MFF_TUN_SRC:
          return !wc->masks.tunnel.ip_src;
      case MFF_TUN_DST:
          return !wc->masks.tunnel.ip_dst;
      case MFF_TUN_ID:
      case MFF_TUN_TOS:
      case MFF_TUN_TTL:
      case MFF_TUN_FLAGS:
          return !wc->masks.tunnel.tun_id;
      case MFF_METADATA:
          return !wc->masks.metadata;
      case MFF_IN_PORT:
      case MFF_IN_PORT_OXM:
          return !wc->masks.in_port.ofp_port;
      case MFF_SKB_PRIORITY:
          return !wc->masks.skb_priority;
      case MFF_PKT_MARK:
          return !wc->masks.pkt_mark;
      CASE_MFF_REGS:
          return !wc->masks.regs[mf->id - MFF_REG0];
      CASE_MFF_XREGS:
          return !flow_get_xreg(&wc->masks, mf->id - MFF_XREG0);
  
      case MFF_ETH_SRC:
          return eth_addr_is_zero(wc->masks.dl_src);
      case MFF_ETH_DST:
          return eth_addr_is_zero(wc->masks.dl_dst);
      case MFF_ETH_TYPE:
          return !wc->masks.dl_type;
  
      case MFF_ARP_SHA:
      case MFF_ND_SLL:
          return eth_addr_is_zero(wc->masks.arp_sha);
  
      case MFF_ARP_THA:
      case MFF_ND_TLL:
          return eth_addr_is_zero(wc->masks.arp_tha);
  
      case MFF_VLAN_TCI:
          return !wc->masks.vlan_tci;
      case MFF_DL_VLAN:
          return !(wc->masks.vlan_tci & htons(VLAN_VID_MASK));
      case MFF_VLAN_VID:
          return !(wc->masks.vlan_tci & htons(VLAN_VID_MASK | VLAN_CFI));
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
          return !(wc->masks.vlan_tci & htons(VLAN_PCP_MASK));
  
      case MFF_MPLS_LABEL:
          return !(wc->masks.mpls_lse[0] & htonl(MPLS_LABEL_MASK));
      case MFF_MPLS_TC:
          return !(wc->masks.mpls_lse[1] & htonl(MPLS_TC_MASK));
      case MFF_MPLS_BOS:
          return !(wc->masks.mpls_lse[2] & htonl(MPLS_BOS_MASK));
  
      case MFF_IPV4_SRC:
          return !wc->masks.nw_src;
      case MFF_IPV4_DST:
          return !wc->masks.nw_dst;
  
      case MFF_IPV6_SRC:
          return ipv6_mask_is_any(&wc->masks.ipv6_src);
      case MFF_IPV6_DST:
          return ipv6_mask_is_any(&wc->masks.ipv6_dst);
  
      case MFF_IPV6_LABEL:
          return !wc->masks.ipv6_label;
  
      case MFF_IP_PROTO:
          return !wc->masks.nw_proto;
      case MFF_IP_DSCP:
      case MFF_IP_DSCP_SHIFTED:
          return !(wc->masks.nw_tos & IP_DSCP_MASK);
      case MFF_IP_ECN:
          return !(wc->masks.nw_tos & IP_ECN_MASK);
      case MFF_IP_TTL:
          return !wc->masks.nw_ttl;
  
      case MFF_ND_TARGET:
          return ipv6_mask_is_any(&wc->masks.nd_target);
  
      case MFF_IP_FRAG:
          return !(wc->masks.nw_frag & FLOW_NW_FRAG_MASK);
  
      case MFF_ARP_OP:
          return !wc->masks.nw_proto;
      case MFF_ARP_SPA:
          return !wc->masks.nw_src;
      case MFF_ARP_TPA:
          return !wc->masks.nw_dst;
  
      case MFF_TCP_SRC:
      case MFF_UDP_SRC:
      case MFF_SCTP_SRC:
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV6_TYPE:
          return !wc->masks.tp_src;
      case MFF_TCP_DST:
      case MFF_UDP_DST:
      case MFF_SCTP_DST:
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_CODE:
          return !wc->masks.tp_dst;
      case MFF_TCP_FLAGS:
          return !wc->masks.tcp_flags;
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Initializes 'mask' with the wildcard bit pattern for field 'mf' within 'wc'.
   * Each bit in 'mask' will be set to 1 if the bit is significant for matching
   * purposes, or to 0 if it is wildcarded.
   *
   * The caller is responsible for ensuring that 'wc' corresponds to a flow that
   * meets 'mf''s prerequisites. */
  void
  mf_get_mask(const struct mf_field *mf, const struct flow_wildcards *wc,
              union mf_value *mask)
  {
      mf_get_value(mf, &wc->masks, mask);
  }
  
  /* Tests whether 'mask' is a valid wildcard bit pattern for 'mf'.  Returns true
   * if the mask is valid, false otherwise. */
  bool
  mf_is_mask_valid(const struct mf_field *mf, const union mf_value *mask)
  {
      switch (mf->maskable) {
      case MFM_NONE:
          return (is_all_zeros((const uint8_t *) mask, mf->n_bytes) ||
                  is_all_ones((const uint8_t *) mask, mf->n_bytes));
  
      case MFM_FULLY:
          return true;
      }
  
      OVS_NOT_REACHED();
  }
  
  /* Returns true if 'flow' meets the prerequisites for 'mf', false otherwise. */
  bool
  mf_are_prereqs_ok(const struct mf_field *mf, const struct flow *flow)
  {
      switch (mf->prereqs) {
      case MFP_NONE:
          return true;
  
      case MFP_ARP:
        return (flow->dl_type == htons(ETH_TYPE_ARP) ||
                flow->dl_type == htons(ETH_TYPE_RARP));
      case MFP_IPV4:
          return flow->dl_type == htons(ETH_TYPE_IP);
      case MFP_IPV6:
          return flow->dl_type == htons(ETH_TYPE_IPV6);
      case MFP_VLAN_VID:
          return (flow->vlan_tci & htons(VLAN_CFI)) != 0;
      case MFP_MPLS:
          return eth_type_mpls(flow->dl_type);
      case MFP_IP_ANY:
          return is_ip_any(flow);
  
      case MFP_TCP:
          return is_ip_any(flow) && flow->nw_proto == IPPROTO_TCP;
      case MFP_UDP:
          return is_ip_any(flow) && flow->nw_proto == IPPROTO_UDP;
      case MFP_SCTP:
          return is_ip_any(flow) && flow->nw_proto == IPPROTO_SCTP;
      case MFP_ICMPV4:
          return is_icmpv4(flow);
      case MFP_ICMPV6:
          return is_icmpv6(flow);
  
      case MFP_ND:
          return (is_icmpv6(flow)
                  && flow->tp_dst == htons(0)
                  && (flow->tp_src == htons(ND_NEIGHBOR_SOLICIT) ||
                      flow->tp_src == htons(ND_NEIGHBOR_ADVERT)));
      case MFP_ND_SOLICIT:
          return (is_icmpv6(flow)
                  && flow->tp_dst == htons(0)
                  && (flow->tp_src == htons(ND_NEIGHBOR_SOLICIT)));
      case MFP_ND_ADVERT:
          return (is_icmpv6(flow)
                  && flow->tp_dst == htons(0)
                  && (flow->tp_src == htons(ND_NEIGHBOR_ADVERT)));
      }
  
      OVS_NOT_REACHED();
  }
  
  /* Set field and it's prerequisities in the mask.
   * This is only ever called for writeable 'mf's, but we do not make the
   * distinction here. */
  void
  mf_mask_field_and_prereqs(const struct mf_field *mf, struct flow *mask)
  {
      static const union mf_value exact_match_mask = MF_EXACT_MASK_INITIALIZER;
  
      mf_set_flow_value(mf, &exact_match_mask, mask);
  
      switch (mf->prereqs) {
      case MFP_ND:
      case MFP_ND_SOLICIT:
      case MFP_ND_ADVERT:
          mask->tp_src = OVS_BE16_MAX;
          mask->tp_dst = OVS_BE16_MAX;
          /* Fall through. */
      case MFP_TCP:
      case MFP_UDP:
      case MFP_SCTP:
      case MFP_ICMPV4:
      case MFP_ICMPV6:
          mask->nw_proto = 0xff;
          /* Fall through. */
      case MFP_ARP:
      case MFP_IPV4:
      case MFP_IPV6:
      case MFP_MPLS:
      case MFP_IP_ANY:
          mask->dl_type = OVS_BE16_MAX;
          break;
      case MFP_VLAN_VID:
          mask->vlan_tci |= htons(VLAN_CFI);
          break;
      case MFP_NONE:
          break;
      }
  }
  
  
  /* Returns true if 'value' may be a valid value *as part of a masked match*,
   * false otherwise.
   *
   * A value is not rejected just because it is not valid for the field in
   * question, but only if it doesn't make sense to test the bits in question at
   * all.  For example, the MFF_VLAN_TCI field will never have a nonzero value
   * without the VLAN_CFI bit being set, but we can't reject those values because
   * it is still legitimate to test just for those bits (see the documentation
   * for NXM_OF_VLAN_TCI in nicira-ext.h).  On the other hand, there is never a
   * reason to set the low bit of MFF_IP_DSCP to 1, so we reject that. */
  bool
  mf_is_value_valid(const struct mf_field *mf, const union mf_value *value)
  {
      switch (mf->id) {
      case MFF_DP_HASH:
      case MFF_RECIRC_ID:
      case MFF_TUN_ID:
      case MFF_TUN_SRC:
      case MFF_TUN_DST:
      case MFF_TUN_TOS:
      case MFF_TUN_TTL:
      case MFF_TUN_FLAGS:
      case MFF_METADATA:
      case MFF_IN_PORT:
      case MFF_SKB_PRIORITY:
      case MFF_PKT_MARK:
      CASE_MFF_REGS:
      CASE_MFF_XREGS:
      case MFF_ETH_SRC:
      case MFF_ETH_DST:
      case MFF_ETH_TYPE:
      case MFF_VLAN_TCI:
      case MFF_IPV4_SRC:
      case MFF_IPV4_DST:
      case MFF_IPV6_SRC:
      case MFF_IPV6_DST:
      case MFF_IP_PROTO:
      case MFF_IP_TTL:
      case MFF_ARP_SPA:
      case MFF_ARP_TPA:
      case MFF_ARP_SHA:
      case MFF_ARP_THA:
      case MFF_TCP_SRC:
      case MFF_TCP_DST:
      case MFF_UDP_SRC:
      case MFF_UDP_DST:
      case MFF_SCTP_SRC:
      case MFF_SCTP_DST:
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_TYPE:
      case MFF_ICMPV6_CODE:
      case MFF_ND_TARGET:
      case MFF_ND_SLL:
      case MFF_ND_TLL:
          return true;
  
      case MFF_IN_PORT_OXM: {
          ofp_port_t port;
          return !ofputil_port_from_ofp11(value->be32, &port);
      }
  
      case MFF_IP_DSCP:
          return !(value->u8 & ~IP_DSCP_MASK);
      case MFF_IP_DSCP_SHIFTED:
          return !(value->u8 & (~IP_DSCP_MASK >> 2));
      case MFF_IP_ECN:
          return !(value->u8 & ~IP_ECN_MASK);
      case MFF_IP_FRAG:
          return !(value->u8 & ~FLOW_NW_FRAG_MASK);
      case MFF_TCP_FLAGS:
          return !(value->be16 & ~htons(0x0fff));
  
      case MFF_ARP_OP:
          return !(value->be16 & htons(0xff00));
  
      case MFF_DL_VLAN:
          return !(value->be16 & htons(VLAN_CFI | VLAN_PCP_MASK));
      case MFF_VLAN_VID:
          return !(value->be16 & htons(VLAN_PCP_MASK));
  
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
          return !(value->u8 & ~(VLAN_PCP_MASK >> VLAN_PCP_SHIFT));
  
      case MFF_IPV6_LABEL:
          return !(value->be32 & ~htonl(IPV6_LABEL_MASK));
  
      case MFF_MPLS_LABEL:
          return !(value->be32 & ~htonl(MPLS_LABEL_MASK >> MPLS_LABEL_SHIFT));
  
      case MFF_MPLS_TC:
          return !(value->u8 & ~(MPLS_TC_MASK >> MPLS_TC_SHIFT));
  
      case MFF_MPLS_BOS:
          return !(value->u8 & ~(MPLS_BOS_MASK >> MPLS_BOS_SHIFT));
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Copies the value of field 'mf' from 'flow' into 'value'.  The caller is
   * responsible for ensuring that 'flow' meets 'mf''s prerequisites. */
  void
  mf_get_value(const struct mf_field *mf, const struct flow *flow,
               union mf_value *value)
  {
      switch (mf->id) {
      case MFF_DP_HASH:
          value->be32 = htonl(flow->dp_hash);
          break;
      case MFF_RECIRC_ID:
          value->be32 = htonl(flow->recirc_id);
          break;
      case MFF_TUN_ID:
          value->be64 = flow->tunnel.tun_id;
          break;
      case MFF_TUN_SRC:
          value->be32 = flow->tunnel.ip_src;
          break;
      case MFF_TUN_DST:
          value->be32 = flow->tunnel.ip_dst;
          break;
      case MFF_TUN_FLAGS:
          value->be16 = htons(flow->tunnel.flags);
          break;
      case MFF_TUN_TTL:
          value->u8 = flow->tunnel.ip_ttl;
          break;
      case MFF_TUN_TOS:
          value->u8 = flow->tunnel.ip_tos;
          break;
  
      case MFF_METADATA:
          value->be64 = flow->metadata;
          break;
  
      case MFF_IN_PORT:
          value->be16 = htons(ofp_to_u16(flow->in_port.ofp_port));
          break;
      case MFF_IN_PORT_OXM:
          value->be32 = ofputil_port_to_ofp11(flow->in_port.ofp_port);
          break;
  
      case MFF_SKB_PRIORITY:
          value->be32 = htonl(flow->skb_priority);
          break;
  
      case MFF_PKT_MARK:
          value->be32 = htonl(flow->pkt_mark);
          break;
  
      CASE_MFF_REGS:
          value->be32 = htonl(flow->regs[mf->id - MFF_REG0]);
          break;
  
      CASE_MFF_XREGS:
          value->be64 = htonll(flow_get_xreg(flow, mf->id - MFF_XREG0));
          break;
  
      case MFF_ETH_SRC:
          memcpy(value->mac, flow->dl_src, ETH_ADDR_LEN);
          break;
  
      case MFF_ETH_DST:
          memcpy(value->mac, flow->dl_dst, ETH_ADDR_LEN);
          break;
  
      case MFF_ETH_TYPE:
          value->be16 = flow->dl_type;
          break;
  
      case MFF_VLAN_TCI:
          value->be16 = flow->vlan_tci;
          break;
  
      case MFF_DL_VLAN:
          value->be16 = flow->vlan_tci & htons(VLAN_VID_MASK);
          break;
      case MFF_VLAN_VID:
          value->be16 = flow->vlan_tci & htons(VLAN_VID_MASK | VLAN_CFI);
          break;
  
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
          value->u8 = vlan_tci_to_pcp(flow->vlan_tci);
          break;
  
      case MFF_MPLS_LABEL:
          value->be32 = htonl(mpls_lse_to_label(flow->mpls_lse[0]));
          break;
  
      case MFF_MPLS_TC:
          value->u8 = mpls_lse_to_tc(flow->mpls_lse[0]);
          break;
  
      case MFF_MPLS_BOS:
          value->u8 = mpls_lse_to_bos(flow->mpls_lse[0]);
          break;
  
      case MFF_IPV4_SRC:
          value->be32 = flow->nw_src;
          break;
  
      case MFF_IPV4_DST:
          value->be32 = flow->nw_dst;
          break;
  
      case MFF_IPV6_SRC:
          value->ipv6 = flow->ipv6_src;
          break;
  
      case MFF_IPV6_DST:
          value->ipv6 = flow->ipv6_dst;
          break;
  
      case MFF_IPV6_LABEL:
          value->be32 = flow->ipv6_label;
          break;
  
      case MFF_IP_PROTO:
          value->u8 = flow->nw_proto;
          break;
  
      case MFF_IP_DSCP:
          value->u8 = flow->nw_tos & IP_DSCP_MASK;
          break;
  
      case MFF_IP_DSCP_SHIFTED:
          value->u8 = flow->nw_tos >> 2;
          break;
  
      case MFF_IP_ECN:
          value->u8 = flow->nw_tos & IP_ECN_MASK;
          break;
  
      case MFF_IP_TTL:
          value->u8 = flow->nw_ttl;
          break;
  
      case MFF_IP_FRAG:
          value->u8 = flow->nw_frag;
          break;
  
      case MFF_ARP_OP:
          value->be16 = htons(flow->nw_proto);
          break;
  
      case MFF_ARP_SPA:
          value->be32 = flow->nw_src;
          break;
  
      case MFF_ARP_TPA:
          value->be32 = flow->nw_dst;
          break;
  
      case MFF_ARP_SHA:
      case MFF_ND_SLL:
          memcpy(value->mac, flow->arp_sha, ETH_ADDR_LEN);
          break;
  
      case MFF_ARP_THA:
      case MFF_ND_TLL:
          memcpy(value->mac, flow->arp_tha, ETH_ADDR_LEN);
          break;
  
      case MFF_TCP_SRC:
      case MFF_UDP_SRC:
      case MFF_SCTP_SRC:
          value->be16 = flow->tp_src;
          break;
  
      case MFF_TCP_DST:
      case MFF_UDP_DST:
      case MFF_SCTP_DST:
          value->be16 = flow->tp_dst;
          break;
  
      case MFF_TCP_FLAGS:
          value->be16 = flow->tcp_flags;
          break;
  
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV6_TYPE:
          value->u8 = ntohs(flow->tp_src);
          break;
  
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_CODE:
          value->u8 = ntohs(flow->tp_dst);
          break;
  
      case MFF_ND_TARGET:
          value->ipv6 = flow->nd_target;
          break;
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Makes 'match' match field 'mf' exactly, with the value matched taken from
   * 'value'.  The caller is responsible for ensuring that 'match' meets 'mf''s
   * prerequisites. */
  void
  mf_set_value(const struct mf_field *mf,
               const union mf_value *value, struct match *match)
  {
      switch (mf->id) {
      case MFF_DP_HASH:
          match_set_dp_hash(match, ntohl(value->be32));
          break;
      case MFF_RECIRC_ID:
          match_set_recirc_id(match, ntohl(value->be32));
          break;
      case MFF_TUN_ID:
          match_set_tun_id(match, value->be64);
          break;
      case MFF_TUN_SRC:
          match_set_tun_src(match, value->be32);
          break;
      case MFF_TUN_DST:
          match_set_tun_dst(match, value->be32);
          break;
      case MFF_TUN_FLAGS:
          match_set_tun_flags(match, ntohs(value->be16));
          break;
      case MFF_TUN_TOS:
          match_set_tun_tos(match, value->u8);
          break;
      case MFF_TUN_TTL:
          match_set_tun_ttl(match, value->u8);
          break;
  
      case MFF_METADATA:
          match_set_metadata(match, value->be64);
          break;
  
      case MFF_IN_PORT:
          match_set_in_port(match, u16_to_ofp(ntohs(value->be16)));
          break;
  
      case MFF_IN_PORT_OXM: {
          ofp_port_t port;
          ofputil_port_from_ofp11(value->be32, &port);
          match_set_in_port(match, port);
          break;
      }
  
      case MFF_SKB_PRIORITY:
          match_set_skb_priority(match, ntohl(value->be32));
          break;
  
      case MFF_PKT_MARK:
          match_set_pkt_mark(match, ntohl(value->be32));
          break;
  
      CASE_MFF_REGS:
          match_set_reg(match, mf->id - MFF_REG0, ntohl(value->be32));
          break;
  
      CASE_MFF_XREGS:
          match_set_xreg(match, mf->id - MFF_XREG0, ntohll(value->be64));
          break;
  
      case MFF_ETH_SRC:
          match_set_dl_src(match, value->mac);
          break;
  
      case MFF_ETH_DST:
          match_set_dl_dst(match, value->mac);
          break;
  
      case MFF_ETH_TYPE:
          match_set_dl_type(match, value->be16);
          break;
  
      case MFF_VLAN_TCI:
          match_set_dl_tci(match, value->be16);
          break;
  
      case MFF_DL_VLAN:
          match_set_dl_vlan(match, value->be16);
          break;
      case MFF_VLAN_VID:
          match_set_vlan_vid(match, value->be16);
          break;
  
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
          match_set_dl_vlan_pcp(match, value->u8);
          break;
  
      case MFF_MPLS_LABEL:
          match_set_mpls_label(match, 0, value->be32);
          break;
  
      case MFF_MPLS_TC:
          match_set_mpls_tc(match, 0, value->u8);
          break;
  
      case MFF_MPLS_BOS:
          match_set_mpls_bos(match, 0, value->u8);
          break;
  
      case MFF_IPV4_SRC:
          match_set_nw_src(match, value->be32);
          break;
  
      case MFF_IPV4_DST:
          match_set_nw_dst(match, value->be32);
          break;
  
      case MFF_IPV6_SRC:
          match_set_ipv6_src(match, &value->ipv6);
          break;
  
      case MFF_IPV6_DST:
          match_set_ipv6_dst(match, &value->ipv6);
          break;
  
      case MFF_IPV6_LABEL:
          match_set_ipv6_label(match, value->be32);
          break;
  
      case MFF_IP_PROTO:
          match_set_nw_proto(match, value->u8);
          break;
  
      case MFF_IP_DSCP:
          match_set_nw_dscp(match, value->u8);
          break;
  
      case MFF_IP_DSCP_SHIFTED:
          match_set_nw_dscp(match, value->u8 << 2);
          break;
  
      case MFF_IP_ECN:
          match_set_nw_ecn(match, value->u8);
          break;
  
      case MFF_IP_TTL:
          match_set_nw_ttl(match, value->u8);
          break;
  
      case MFF_IP_FRAG:
          match_set_nw_frag(match, value->u8);
          break;
  
      case MFF_ARP_OP:
          match_set_nw_proto(match, ntohs(value->be16));
          break;
  
      case MFF_ARP_SPA:
          match_set_nw_src(match, value->be32);
          break;
  
      case MFF_ARP_TPA:
          match_set_nw_dst(match, value->be32);
          break;
  
      case MFF_ARP_SHA:
      case MFF_ND_SLL:
          match_set_arp_sha(match, value->mac);
          break;
  
      case MFF_ARP_THA:
      case MFF_ND_TLL:
          match_set_arp_tha(match, value->mac);
          break;
  
      case MFF_TCP_SRC:
      case MFF_UDP_SRC:
      case MFF_SCTP_SRC:
          match_set_tp_src(match, value->be16);
          break;
  
      case MFF_TCP_DST:
      case MFF_UDP_DST:
      case MFF_SCTP_DST:
          match_set_tp_dst(match, value->be16);
          break;
  
      case MFF_TCP_FLAGS:
          match_set_tcp_flags(match, value->be16);
          break;
  
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV6_TYPE:
          match_set_icmp_type(match, value->u8);
          break;
  
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_CODE:
          match_set_icmp_code(match, value->u8);
          break;
  
      case MFF_ND_TARGET:
          match_set_nd_target(match, &value->ipv6);
          break;
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Unwildcard 'mask' member field described by 'mf'.  The caller is
   * responsible for ensuring that 'mask' meets 'mf''s prerequisites. */
  void
  mf_mask_field(const struct mf_field *mf, struct flow *mask)
  {
      static const union mf_value exact_match_mask = MF_EXACT_MASK_INITIALIZER;
  
      /* For MFF_DL_VLAN, we cannot send a all 1's to flow_set_dl_vlan()
       * as that will be considered as OFP10_VLAN_NONE. So consider it as a
       * special case. For the rest, calling mf_set_flow_value() is good
       * enough. */
      if (mf->id == MFF_DL_VLAN) {
          flow_set_dl_vlan(mask, htons(VLAN_VID_MASK));
      } else {
          mf_set_flow_value(mf, &exact_match_mask, mask);
      }
  }
  
  /* Sets 'flow' member field described by 'mf' to 'value'.  The caller is
   * responsible for ensuring that 'flow' meets 'mf''s prerequisites.*/
  void
  mf_set_flow_value(const struct mf_field *mf,
                    const union mf_value *value, struct flow *flow)
  {
      switch (mf->id) {
      case MFF_DP_HASH:
          flow->dp_hash = ntohl(value->be32);
          break;
      case MFF_RECIRC_ID:
          flow->recirc_id = ntohl(value->be32);
          break;
      case MFF_TUN_ID:
          flow->tunnel.tun_id = value->be64;
          break;
      case MFF_TUN_SRC:
          flow->tunnel.ip_src = value->be32;
          break;
      case MFF_TUN_DST:
          flow->tunnel.ip_dst = value->be32;
          break;
      case MFF_TUN_FLAGS:
          flow->tunnel.flags = ntohs(value->be16);
          break;
      case MFF_TUN_TOS:
          flow->tunnel.ip_tos = value->u8;
          break;
      case MFF_TUN_TTL:
          flow->tunnel.ip_ttl = value->u8;
          break;
  
      case MFF_METADATA:
          flow->metadata = value->be64;
          break;
  
      case MFF_IN_PORT:
          flow->in_port.ofp_port = u16_to_ofp(ntohs(value->be16));
          break;
  
      case MFF_IN_PORT_OXM: {
          ofp_port_t port;
          ofputil_port_from_ofp11(value->be32, &port);
          flow->in_port.ofp_port = port;
          break;
      }
  
      case MFF_SKB_PRIORITY:
          flow->skb_priority = ntohl(value->be32);
          break;
  
      case MFF_PKT_MARK:
          flow->pkt_mark = ntohl(value->be32);
          break;
  
      CASE_MFF_REGS:
          flow->regs[mf->id - MFF_REG0] = ntohl(value->be32);
          break;
  
      CASE_MFF_XREGS:
          flow_set_xreg(flow, mf->id - MFF_XREG0, ntohll(value->be64));
          break;
  
      case MFF_ETH_SRC:
          memcpy(flow->dl_src, value->mac, ETH_ADDR_LEN);
          break;
  
      case MFF_ETH_DST:
          memcpy(flow->dl_dst, value->mac, ETH_ADDR_LEN);
          break;
  
      case MFF_ETH_TYPE:
          flow->dl_type = value->be16;
          break;
  
      case MFF_VLAN_TCI:
          flow->vlan_tci = value->be16;
          break;
  
      case MFF_DL_VLAN:
          flow_set_dl_vlan(flow, value->be16);
          break;
      case MFF_VLAN_VID:
          flow_set_vlan_vid(flow, value->be16);
          break;
  
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
          flow_set_vlan_pcp(flow, value->u8);
          break;
  
      case MFF_MPLS_LABEL:
          flow_set_mpls_label(flow, 0, value->be32);
          break;
  
      case MFF_MPLS_TC:
          flow_set_mpls_tc(flow, 0, value->u8);
          break;
  
      case MFF_MPLS_BOS:
          flow_set_mpls_bos(flow, 0, value->u8);
          break;
  
      case MFF_IPV4_SRC:
          flow->nw_src = value->be32;
          break;
  
      case MFF_IPV4_DST:
          flow->nw_dst = value->be32;
          break;
  
      case MFF_IPV6_SRC:
          flow->ipv6_src = value->ipv6;
          break;
  
      case MFF_IPV6_DST:
          flow->ipv6_dst = value->ipv6;
          break;
  
      case MFF_IPV6_LABEL:
          flow->ipv6_label = value->be32 & ~htonl(IPV6_LABEL_MASK);
          break;
  
      case MFF_IP_PROTO:
          flow->nw_proto = value->u8;
          break;
  
      case MFF_IP_DSCP:
          flow->nw_tos &= ~IP_DSCP_MASK;
          flow->nw_tos |= value->u8 & IP_DSCP_MASK;
          break;
  
      case MFF_IP_DSCP_SHIFTED:
          flow->nw_tos &= ~IP_DSCP_MASK;
          flow->nw_tos |= value->u8 << 2;
          break;
  
      case MFF_IP_ECN:
          flow->nw_tos &= ~IP_ECN_MASK;
          flow->nw_tos |= value->u8 & IP_ECN_MASK;
          break;
  
      case MFF_IP_TTL:
          flow->nw_ttl = value->u8;
          break;
  
      case MFF_IP_FRAG:
          flow->nw_frag = value->u8 & FLOW_NW_FRAG_MASK;
          break;
  
      case MFF_ARP_OP:
          flow->nw_proto = ntohs(value->be16);
          break;
  
      case MFF_ARP_SPA:
          flow->nw_src = value->be32;
          break;
  
      case MFF_ARP_TPA:
          flow->nw_dst = value->be32;
          break;
  
      case MFF_ARP_SHA:
      case MFF_ND_SLL:
          memcpy(flow->arp_sha, value->mac, ETH_ADDR_LEN);
          break;
  
      case MFF_ARP_THA:
      case MFF_ND_TLL:
          memcpy(flow->arp_tha, value->mac, ETH_ADDR_LEN);
          break;
  
      case MFF_TCP_SRC:
      case MFF_UDP_SRC:
      case MFF_SCTP_SRC:
          flow->tp_src = value->be16;
          break;
  
      case MFF_TCP_DST:
      case MFF_UDP_DST:
      case MFF_SCTP_DST:
          flow->tp_dst = value->be16;
          break;
  
      case MFF_TCP_FLAGS:
          flow->tcp_flags = value->be16;
          break;
  
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV6_TYPE:
          flow->tp_src = htons(value->u8);
          break;
  
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_CODE:
          flow->tp_dst = htons(value->u8);
          break;
  
      case MFF_ND_TARGET:
          flow->nd_target = value->ipv6;
          break;
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Returns true if 'mf' has a zero value in 'flow', false if it is nonzero.
   *
   * The caller is responsible for ensuring that 'flow' meets 'mf''s
   * prerequisites. */
  bool
  mf_is_zero(const struct mf_field *mf, const struct flow *flow)
  {
      union mf_value value;
  
      mf_get_value(mf, flow, &value);
      return is_all_zeros((const uint8_t *) &value, mf->n_bytes);
  }
  
  /* Makes 'match' wildcard field 'mf'.
   *
   * The caller is responsible for ensuring that 'match' meets 'mf''s
   * prerequisites. */
  void
  mf_set_wild(const struct mf_field *mf, struct match *match)
  {
      switch (mf->id) {
      case MFF_DP_HASH:
          match->flow.dp_hash = 0;
          match->wc.masks.dp_hash = 0;
          break;
      case MFF_RECIRC_ID:
          match->flow.recirc_id = 0;
          match->wc.masks.recirc_id = 0;
          break;
      case MFF_TUN_ID:
          match_set_tun_id_masked(match, htonll(0), htonll(0));
          break;
      case MFF_TUN_SRC:
          match_set_tun_src_masked(match, htonl(0), htonl(0));
          break;
      case MFF_TUN_DST:
          match_set_tun_dst_masked(match, htonl(0), htonl(0));
          break;
      case MFF_TUN_FLAGS:
          match_set_tun_flags_masked(match, 0, 0);
          break;
      case MFF_TUN_TOS:
          match_set_tun_tos_masked(match, 0, 0);
          break;
      case MFF_TUN_TTL:
          match_set_tun_ttl_masked(match, 0, 0);
          break;
  
      case MFF_METADATA:
          match_set_metadata_masked(match, htonll(0), htonll(0));
          break;
  
      case MFF_IN_PORT:
      case MFF_IN_PORT_OXM:
          match->flow.in_port.ofp_port = 0;
          match->wc.masks.in_port.ofp_port = 0;
          break;
  
      case MFF_SKB_PRIORITY:
          match->flow.skb_priority = 0;
          match->wc.masks.skb_priority = 0;
          break;
  
      case MFF_PKT_MARK:
          match->flow.pkt_mark = 0;
          match->wc.masks.pkt_mark = 0;
          break;
  
      CASE_MFF_REGS:
          match_set_reg_masked(match, mf->id - MFF_REG0, 0, 0);
          break;
  
      CASE_MFF_XREGS:
          match_set_xreg_masked(match, mf->id - MFF_XREG0, 0, 0);
          break;
  
      case MFF_ETH_SRC:
          memset(match->flow.dl_src, 0, ETH_ADDR_LEN);
          memset(match->wc.masks.dl_src, 0, ETH_ADDR_LEN);
          break;
  
      case MFF_ETH_DST:
          memset(match->flow.dl_dst, 0, ETH_ADDR_LEN);
          memset(match->wc.masks.dl_dst, 0, ETH_ADDR_LEN);
          break;
  
      case MFF_ETH_TYPE:
          match->flow.dl_type = htons(0);
          match->wc.masks.dl_type = htons(0);
          break;
  
      case MFF_VLAN_TCI:
          match_set_dl_tci_masked(match, htons(0), htons(0));
          break;
  
      case MFF_DL_VLAN:
      case MFF_VLAN_VID:
          match_set_any_vid(match);
          break;
  
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
          match_set_any_pcp(match);
          break;
  
      case MFF_MPLS_LABEL:
          match_set_any_mpls_label(match, 0);
          break;
  
      case MFF_MPLS_TC:
          match_set_any_mpls_tc(match, 0);
          break;
  
      case MFF_MPLS_BOS:
          match_set_any_mpls_bos(match, 0);
          break;
  
      case MFF_IPV4_SRC:
      case MFF_ARP_SPA:
          match_set_nw_src_masked(match, htonl(0), htonl(0));
          break;
  
      case MFF_IPV4_DST:
      case MFF_ARP_TPA:
          match_set_nw_dst_masked(match, htonl(0), htonl(0));
          break;
  
      case MFF_IPV6_SRC:
          memset(&match->wc.masks.ipv6_src, 0, sizeof match->wc.masks.ipv6_src);
          memset(&match->flow.ipv6_src, 0, sizeof match->flow.ipv6_src);
          break;
  
      case MFF_IPV6_DST:
          memset(&match->wc.masks.ipv6_dst, 0, sizeof match->wc.masks.ipv6_dst);
          memset(&match->flow.ipv6_dst, 0, sizeof match->flow.ipv6_dst);
          break;
  
      case MFF_IPV6_LABEL:
          match->wc.masks.ipv6_label = htonl(0);
          match->flow.ipv6_label = htonl(0);
          break;
  
      case MFF_IP_PROTO:
          match->wc.masks.nw_proto = 0;
          match->flow.nw_proto = 0;
          break;
  
      case MFF_IP_DSCP:
      case MFF_IP_DSCP_SHIFTED:
          match->wc.masks.nw_tos &= ~IP_DSCP_MASK;
          match->flow.nw_tos &= ~IP_DSCP_MASK;
          break;
  
      case MFF_IP_ECN:
          match->wc.masks.nw_tos &= ~IP_ECN_MASK;
          match->flow.nw_tos &= ~IP_ECN_MASK;
          break;
  
      case MFF_IP_TTL:
          match->wc.masks.nw_ttl = 0;
          match->flow.nw_ttl = 0;
          break;
  
      case MFF_IP_FRAG:
          match->wc.masks.nw_frag |= FLOW_NW_FRAG_MASK;
          match->flow.nw_frag &= ~FLOW_NW_FRAG_MASK;
          break;
  
      case MFF_ARP_OP:
          match->wc.masks.nw_proto = 0;
          match->flow.nw_proto = 0;
          break;
  
      case MFF_ARP_SHA:
      case MFF_ND_SLL:
          memset(match->flow.arp_sha, 0, ETH_ADDR_LEN);
          memset(match->wc.masks.arp_sha, 0, ETH_ADDR_LEN);
          break;
  
      case MFF_ARP_THA:
      case MFF_ND_TLL:
          memset(match->flow.arp_tha, 0, ETH_ADDR_LEN);
          memset(match->wc.masks.arp_tha, 0, ETH_ADDR_LEN);
          break;
  
      case MFF_TCP_SRC:
      case MFF_UDP_SRC:
      case MFF_SCTP_SRC:
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV6_TYPE:
          match->wc.masks.tp_src = htons(0);
          match->flow.tp_src = htons(0);
          break;
  
      case MFF_TCP_DST:
      case MFF_UDP_DST:
      case MFF_SCTP_DST:
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_CODE:
          match->wc.masks.tp_dst = htons(0);
          match->flow.tp_dst = htons(0);
          break;
  
      case MFF_TCP_FLAGS:
          match->wc.masks.tcp_flags = htons(0);
          match->flow.tcp_flags = htons(0);
          break;
  
      case MFF_ND_TARGET:
          memset(&match->wc.masks.nd_target, 0,
                 sizeof match->wc.masks.nd_target);
          memset(&match->flow.nd_target, 0, sizeof match->flow.nd_target);
          break;
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Makes 'match' match field 'mf' with the specified 'value' and 'mask'.
   * 'value' specifies a value to match and 'mask' specifies a wildcard pattern,
   * with a 1-bit indicating that the corresponding value bit must match and a
   * 0-bit indicating a don't-care.
   *
   * If 'mask' is NULL or points to all-1-bits, then this call is equivalent to
   * mf_set_value(mf, value, match).  If 'mask' points to all-0-bits, then this
   * call is equivalent to mf_set_wild(mf, match).
   *
   * 'mask' must be a valid mask for 'mf' (see mf_is_mask_valid()).  The caller
   * is responsible for ensuring that 'match' meets 'mf''s prerequisites. */
  enum ofputil_protocol
  mf_set(const struct mf_field *mf,
         const union mf_value *value, const union mf_value *mask,
         struct match *match)
  {
      if (!mask || is_all_ones((const uint8_t *) mask, mf->n_bytes)) {
          mf_set_value(mf, value, match);
          return mf->usable_protocols;
      } else if (is_all_zeros((const uint8_t *) mask, mf->n_bytes)) {
          mf_set_wild(mf, match);
          return OFPUTIL_P_ANY;
      }
  
      switch (mf->id) {
      case MFF_RECIRC_ID:
      case MFF_IN_PORT:
      case MFF_IN_PORT_OXM:
      case MFF_SKB_PRIORITY:
      case MFF_ETH_TYPE:
      case MFF_DL_VLAN:
      case MFF_DL_VLAN_PCP:
      case MFF_VLAN_PCP:
      case MFF_MPLS_LABEL:
      case MFF_MPLS_TC:
      case MFF_MPLS_BOS:
      case MFF_IP_PROTO:
      case MFF_IP_TTL:
      case MFF_IP_DSCP:
      case MFF_IP_DSCP_SHIFTED:
      case MFF_IP_ECN:
      case MFF_ARP_OP:
      case MFF_ICMPV4_TYPE:
      case MFF_ICMPV4_CODE:
      case MFF_ICMPV6_TYPE:
      case MFF_ICMPV6_CODE:
          return OFPUTIL_P_NONE;
  
      case MFF_DP_HASH:
          match_set_dp_hash_masked(match, ntohl(value->be32), ntohl(mask->be32));
          break;
      case MFF_TUN_ID:
          match_set_tun_id_masked(match, value->be64, mask->be64);
          break;
      case MFF_TUN_SRC:
          match_set_tun_src_masked(match, value->be32, mask->be32);
          break;
      case MFF_TUN_DST:
          match_set_tun_dst_masked(match, value->be32, mask->be32);
          break;
      case MFF_TUN_FLAGS:
          match_set_tun_flags_masked(match, ntohs(value->be16), ntohs(mask->be16));
          break;
      case MFF_TUN_TTL:
          match_set_tun_ttl_masked(match, value->u8, mask->u8);
          break;
      case MFF_TUN_TOS:
          match_set_tun_tos_masked(match, value->u8, mask->u8);
          break;
  
      case MFF_METADATA:
          match_set_metadata_masked(match, value->be64, mask->be64);
          break;
  
      CASE_MFF_REGS:
          match_set_reg_masked(match, mf->id - MFF_REG0,
                               ntohl(value->be32), ntohl(mask->be32));
          break;
  
      CASE_MFF_XREGS:
          match_set_xreg_masked(match, mf->id - MFF_XREG0,
                                ntohll(value->be64), ntohll(mask->be64));
          break;
  
      case MFF_PKT_MARK:
          match_set_pkt_mark_masked(match, ntohl(value->be32),
                                    ntohl(mask->be32));
          break;
  
      case MFF_ETH_DST:
          match_set_dl_dst_masked(match, value->mac, mask->mac);
          break;
  
      case MFF_ETH_SRC:
          match_set_dl_src_masked(match, value->mac, mask->mac);
          break;
  
      case MFF_ARP_SHA:
      case MFF_ND_SLL:
          match_set_arp_sha_masked(match, value->mac, mask->mac);
          break;
  
      case MFF_ARP_THA:
      case MFF_ND_TLL:
          match_set_arp_tha_masked(match, value->mac, mask->mac);
          break;
  
      case MFF_VLAN_TCI:
          match_set_dl_tci_masked(match, value->be16, mask->be16);
          break;
  
      case MFF_VLAN_VID:
          match_set_vlan_vid_masked(match, value->be16, mask->be16);
          break;
  
      case MFF_IPV4_SRC:
          match_set_nw_src_masked(match, value->be32, mask->be32);
          goto cidr_check;
  
      case MFF_IPV4_DST:
          match_set_nw_dst_masked(match, value->be32, mask->be32);
          goto cidr_check;
  
      case MFF_IPV6_SRC:
          match_set_ipv6_src_masked(match, &value->ipv6, &mask->ipv6);
          break;
  
      case MFF_IPV6_DST:
          match_set_ipv6_dst_masked(match, &value->ipv6, &mask->ipv6);
          break;
  
      case MFF_IPV6_LABEL:
          if ((mask->be32 & htonl(IPV6_LABEL_MASK)) == htonl(IPV6_LABEL_MASK)) {
              mf_set_value(mf, value, match);
          } else {
              match_set_ipv6_label_masked(match, value->be32, mask->be32);
          }
          break;
  
      case MFF_ND_TARGET:
          match_set_nd_target_masked(match, &value->ipv6, &mask->ipv6);
          break;
  
      case MFF_IP_FRAG:
          match_set_nw_frag_masked(match, value->u8, mask->u8);
          break;
  
      case MFF_ARP_SPA:
          match_set_nw_src_masked(match, value->be32, mask->be32);
          goto cidr_check;
  
      case MFF_ARP_TPA:
          match_set_nw_dst_masked(match, value->be32, mask->be32);
          goto cidr_check;
  
      case MFF_TCP_SRC:
      case MFF_UDP_SRC:
      case MFF_SCTP_SRC:
          match_set_tp_src_masked(match, value->be16, mask->be16);
          break;
  
      case MFF_TCP_DST:
      case MFF_UDP_DST:
      case MFF_SCTP_DST:
          match_set_tp_dst_masked(match, value->be16, mask->be16);
          break;
  
      case MFF_TCP_FLAGS:
          match_set_tcp_flags_masked(match, value->be16, mask->be16);
          break;
  
      case MFF_N_IDS:
      default:
          OVS_NOT_REACHED();
      }
  
      return mf->usable_protocols_bitwise;
  
  cidr_check:
      return ip_is_cidr(mask->be32) ? mf->usable_protocols :
              mf->usable_protocols_bitwise;
  }
  
  static enum ofperr
  mf_check__(const struct mf_subfield *sf, const struct flow *flow,
             const char *type)
  {
      if (!sf->field) {
          VLOG_WARN_RL(&rl, "unknown %s field", type);
          return OFPERR_OFPBAC_BAD_SET_TYPE;
      } else if (!sf->n_bits) {
          VLOG_WARN_RL(&rl, "zero bit %s field %s", type, sf->field->name);
          return OFPERR_OFPBAC_BAD_SET_LEN;
      } else if (sf->ofs >= sf->field->n_bits) {
          VLOG_WARN_RL(&rl, "bit offset %d exceeds %d-bit width of %s field %s",
                       sf->ofs, sf->field->n_bits, type, sf->field->name);
          return OFPERR_OFPBAC_BAD_SET_LEN;
      } else if (sf->ofs + sf->n_bits > sf->field->n_bits) {
          VLOG_WARN_RL(&rl, "bit offset %d and width %d exceeds %d-bit width "
                       "of %s field %s", sf->ofs, sf->n_bits,
                       sf->field->n_bits, type, sf->field->name);
          return OFPERR_OFPBAC_BAD_SET_LEN;
      } else if (flow && !mf_are_prereqs_ok(sf->field, flow)) {
          VLOG_WARN_RL(&rl, "%s field %s lacks correct prerequisites",
                       type, sf->field->name);
          return OFPERR_OFPBAC_MATCH_INCONSISTENT;
      } else {
          return 0;
      }
  }
  
  /* Checks whether 'sf' is valid for reading a subfield out of 'flow'.  Returns
   * 0 if so, otherwise an OpenFlow error code (e.g. as returned by
   * ofp_mkerr()).  */
  enum ofperr
  mf_check_src(const struct mf_subfield *sf, const struct flow *flow)
  {
      return mf_check__(sf, flow, "source");
  }
  
  /* Checks whether 'sf' is valid for writing a subfield into 'flow'.  Returns 0
   * if so, otherwise an OpenFlow error code (e.g. as returned by
   * ofp_mkerr()). */
  enum ofperr
  mf_check_dst(const struct mf_subfield *sf, const struct flow *flow)
  {
      int error = mf_check__(sf, flow, "destination");
      if (!error && !sf->field->writable) {
          VLOG_WARN_RL(&rl, "destination field %s is not writable",
                       sf->field->name);
          return OFPERR_OFPBAC_BAD_SET_ARGUMENT;
      }
      return error;
  }
  
  /* Copies the value and wildcard bit pattern for 'mf' from 'match' into the
   * 'value' and 'mask', respectively. */
  void
  mf_get(const struct mf_field *mf, const struct match *match,
         union mf_value *value, union mf_value *mask)
  {
      mf_get_value(mf, &match->flow, value);
      mf_get_mask(mf, &match->wc, mask);
  }
  
  static char *
  mf_from_integer_string(const struct mf_field *mf, const char *s,
                         uint8_t *valuep, uint8_t *maskp)
  {
      unsigned long long int integer, mask;
      char *tail;
      int i;
  
      errno = 0;
      integer = strtoull(s, &tail, 0);
      if (errno || (*tail != '\0' && *tail != '/')) {
          goto syntax_error;
      }
  
      if (*tail == '/') {
          mask = strtoull(tail + 1, &tail, 0);
          if (errno || *tail != '\0') {
              goto syntax_error;
          }
      } else {
          mask = ULLONG_MAX;
      }
  
      for (i = mf->n_bytes - 1; i >= 0; i--) {
          valuep[i] = integer;
          maskp[i] = mask;
          integer >>= 8;
          mask >>= 8;
      }
      if (integer) {
          return xasprintf("%s: value too large for %u-byte field %s",
                           s, mf->n_bytes, mf->name);
      }
      return NULL;
  
  syntax_error:
      return xasprintf("%s: bad syntax for %s", s, mf->name);
  }
  
  static char *
  mf_from_ethernet_string(const struct mf_field *mf, const char *s,
                          uint8_t mac[ETH_ADDR_LEN],
                          uint8_t mask[ETH_ADDR_LEN])
  {
      int n;
  
      ovs_assert(mf->n_bytes == ETH_ADDR_LEN);
  
      n = -1;
      if (ovs_scan(s, ETH_ADDR_SCAN_FMT"%n", ETH_ADDR_SCAN_ARGS(mac), &n)
          && n == strlen(s)) {
          memset(mask, 0xff, ETH_ADDR_LEN);
          return NULL;
      }
  
      n = -1;
      if (ovs_scan(s, ETH_ADDR_SCAN_FMT"/"ETH_ADDR_SCAN_FMT"%n",
                   ETH_ADDR_SCAN_ARGS(mac), ETH_ADDR_SCAN_ARGS(mask), &n)
          && n == strlen(s)) {
          return NULL;
      }
  
      return xasprintf("%s: invalid Ethernet address", s);
  }
  
  static char *
  mf_from_ipv4_string(const struct mf_field *mf, const char *s,
                      ovs_be32 *ip, ovs_be32 *mask)
  {
      int prefix;
  
      ovs_assert(mf->n_bytes == sizeof *ip);
  
      if (ovs_scan(s, IP_SCAN_FMT"/"IP_SCAN_FMT,
                   IP_SCAN_ARGS(ip), IP_SCAN_ARGS(mask))) {
          /* OK. */
      } else if (ovs_scan(s, IP_SCAN_FMT"/%d", IP_SCAN_ARGS(ip), &prefix)) {
          if (prefix <= 0 || prefix > 32) {
              return xasprintf("%s: network prefix bits not between 1 and "
                               "32", s);
          } else if (prefix == 32) {
              *mask = OVS_BE32_MAX;
          } else {
              *mask = htonl(((1u << prefix) - 1) << (32 - prefix));
          }
      } else if (ovs_scan(s, IP_SCAN_FMT, IP_SCAN_ARGS(ip))) {
          *mask = OVS_BE32_MAX;
      } else {
          return xasprintf("%s: invalid IP address", s);
      }
      return NULL;
  }
  
  static char *
  mf_from_ipv6_string(const struct mf_field *mf, const char *s,
                      struct in6_addr *value, struct in6_addr *mask)
  {
      char *str = xstrdup(s);
      char *save_ptr = NULL;
      const char *name, *netmask;
      int retval;
  
      ovs_assert(mf->n_bytes == sizeof *value);
  
      name = strtok_r(str, "/", &save_ptr);
      retval = name ? lookup_ipv6(name, value) : EINVAL;
      if (retval) {
          char *err;
  
          err = xasprintf("%s: could not convert to IPv6 address", str);
          free(str);
  
          return err;
      }
  
      netmask = strtok_r(NULL, "/", &save_ptr);
      if (netmask) {
          if (inet_pton(AF_INET6, netmask, mask) != 1) {
              int prefix = atoi(netmask);
              if (prefix <= 0 || prefix > 128) {
                  free(str);
                  return xasprintf("%s: prefix bits not between 1 and 128", s);
              } else {
                  *mask = ipv6_create_mask(prefix);
              }
          }
      } else {
          *mask = in6addr_exact;
      }
      free(str);
  
      return NULL;
  }
  
  static char *
  mf_from_ofp_port_string(const struct mf_field *mf, const char *s,
                          ovs_be16 *valuep, ovs_be16 *maskp)
  {
      ofp_port_t port;
  
      ovs_assert(mf->n_bytes == sizeof(ovs_be16));
  
      if (ofputil_port_from_string(s, &port)) {
          *valuep = htons(ofp_to_u16(port));
          *maskp = OVS_BE16_MAX;
          return NULL;
      }
      return xasprintf("%s: port value out of range for %s", s, mf->name);
  }
  
  static char *
  mf_from_ofp_port_string32(const struct mf_field *mf, const char *s,
                            ovs_be32 *valuep, ovs_be32 *maskp)
  {
      ofp_port_t port;
  
      ovs_assert(mf->n_bytes == sizeof(ovs_be32));
      if (ofputil_port_from_string(s, &port)) {
          *valuep = ofputil_port_to_ofp11(port);
          *maskp = OVS_BE32_MAX;
          return NULL;
      }
      return xasprintf("%s: port value out of range for %s", s, mf->name);
  }
  
  struct frag_handling {
      const char *name;
      uint8_t mask;
      uint8_t value;
  };
  
  static const struct frag_handling all_frags[] = {
  #define A FLOW_NW_FRAG_ANY
  #define L FLOW_NW_FRAG_LATER
      /* name               mask  value */
  
      { "no",               A|L,  0     },
      { "first",            A|L,  A     },
      { "later",            A|L,  A|L   },
  
      { "no",               A,    0     },
      { "yes",              A,    A     },
  
      { "not_later",        L,    0     },
      { "later",            L,    L     },
  #undef A
  #undef L
  };
  
  static char *
  mf_from_frag_string(const char *s, uint8_t *valuep, uint8_t *maskp)
  {
      const struct frag_handling *h;
  
      for (h = all_frags; h < &all_frags[ARRAY_SIZE(all_frags)]; h++) {
          if (!strcasecmp(s, h->name)) {
              /* We force the upper bits of the mask on to make mf_parse_value()
               * happy (otherwise it will never think it's an exact match.) */
              *maskp = h->mask | ~FLOW_NW_FRAG_MASK;
              *valuep = h->value;
              return NULL;
          }
      }
  
      return xasprintf("%s: unknown fragment type (valid types are \"no\", "
                       "\"yes\", \"first\", \"later\", \"not_first\"", s);
  }
  
  static int
  parse_flow_tun_flags(const char *s_, const char *(*bit_to_string)(uint32_t),
                       ovs_be16 *res)
  {
      uint32_t result = 0;
      char *save_ptr = NULL;
      char *name;
      int rc = 0;
      char *s = xstrdup(s_);
  
      for (name = strtok_r((char *)s, " |", &save_ptr); name;
           name = strtok_r(NULL, " |", &save_ptr)) {
          int name_len;
          unsigned long long int flags;
          uint32_t bit;
  
          if (ovs_scan(name, "%lli", &flags)) {
              result |= flags;
              continue;
          }
          name_len = strlen(name);
          for (bit = 1; bit; bit <<= 1) {
              const char *fname = bit_to_string(bit);
              size_t len;
  
              if (!fname) {
                  continue;
              }
  
              len = strlen(fname);
              if (len != name_len) {
                  continue;
              }
              if (!strncmp(name, fname, len)) {
                  result |= bit;
                  break;
              }
          }
  
          if (!bit) {
              rc = -ENOENT;
              goto out;
          }
      }
  
      *res = htons(result);
  out:
      free(s);
      return rc;
  }
  
  static char *
  mf_from_tun_flags_string(const char *s, ovs_be16 *valuep, ovs_be16 *maskp)
  {
      if (!parse_flow_tun_flags(s, flow_tun_flag_to_string, valuep)) {
          *maskp = OVS_BE16_MAX;
          return NULL;
      }
  
      return xasprintf("%s: unknown tunnel flags (valid flags are \"df\", "
                       "\"csum\", \"key\")", s);
  }
  
  static char *
  mf_from_tcp_flags_string(const char *s, ovs_be16 *flagsp, ovs_be16 *maskp)
  {
      uint16_t flags = 0;
      uint16_t mask = 0;
      uint16_t bit;
      int n;
  
      if (ovs_scan(s, "%"SCNi16"/%"SCNi16"%n", &flags, &mask, &n) && !s[n]) {
          *flagsp = htons(flags);
          *maskp = htons(mask);
          return NULL;
      }
      if (ovs_scan(s, "%"SCNi16"%n", &flags, &n) && !s[n]) {
          *flagsp = htons(flags);
          *maskp = OVS_BE16_MAX;
          return NULL;
      }
  
      while (*s != '\0') {
          bool set;
          int name_len;
  
          switch (*s) {
          case '+':
              set = true;
              break;
          case '-':
              set = false;
              break;
          default:
              return xasprintf("%s: TCP flag must be preceded by '+' (for SET) "
                               "or '-' (NOT SET)", s);
          }
          s++;
  
          name_len = strcspn(s,"+-");
  
          for (bit = 1; bit; bit <<= 1) {
              const char *fname = packet_tcp_flag_to_string(bit);
              size_t len;
  
              if (!fname) {
                  continue;
              }
  
              len = strlen(fname);
              if (len != name_len) {
                  continue;
              }
              if (!strncmp(s, fname, len)) {
                  if (mask & bit) {
                      return xasprintf("%s: Each TCP flag can be specified only "
                                       "once", s);
                  }
                  if (set) {
                      flags |= bit;
                  }
                  mask |= bit;
                  break;
              }
          }
  
          if (!bit) {
              return xasprintf("%s: unknown TCP flag(s)", s);
          }
          s += name_len;
      }
  
      *flagsp = htons(flags);
      *maskp = htons(mask);
      return NULL;
  }
  
  
  /* Parses 's', a string value for field 'mf', into 'value' and 'mask'.  Returns
   * NULL if successful, otherwise a malloc()'d string describing the error. */
  char *
  mf_parse(const struct mf_field *mf, const char *s,
           union mf_value *value, union mf_value *mask)
  {
      char *error;
  
      if (!strcmp(s, "*")) {
          memset(value, 0, mf->n_bytes);
          memset(mask, 0, mf->n_bytes);
          return NULL;
      }
  
      switch (mf->string) {
      case MFS_DECIMAL:
      case MFS_HEXADECIMAL:
          error = mf_from_integer_string(mf, s,
                                         (uint8_t *) value, (uint8_t *) mask);
          break;
  
      case MFS_ETHERNET:
          error = mf_from_ethernet_string(mf, s, value->mac, mask->mac);
          break;
  
      case MFS_IPV4:
          error = mf_from_ipv4_string(mf, s, &value->be32, &mask->be32);
          break;
  
      case MFS_IPV6:
          error = mf_from_ipv6_string(mf, s, &value->ipv6, &mask->ipv6);
          break;
  
      case MFS_OFP_PORT:
          error = mf_from_ofp_port_string(mf, s, &value->be16, &mask->be16);
          break;
  
      case MFS_OFP_PORT_OXM:
          error = mf_from_ofp_port_string32(mf, s, &value->be32, &mask->be32);
          break;
  
      case MFS_FRAG:
          error = mf_from_frag_string(s, &value->u8, &mask->u8);
          break;
  
      case MFS_TNL_FLAGS:
          ovs_assert(mf->n_bytes == sizeof(ovs_be16));
          error = mf_from_tun_flags_string(s, &value->be16, &mask->be16);
          break;
  
      case MFS_TCP_FLAGS:
          ovs_assert(mf->n_bytes == sizeof(ovs_be16));
          error = mf_from_tcp_flags_string(s, &value->be16, &mask->be16);
          break;
  
      default:
          OVS_NOT_REACHED();
      }
  
      if (!error && !mf_is_mask_valid(mf, mask)) {
          error = xasprintf("%s: invalid mask for field %s", s, mf->name);
      }
      return error;
  }
  
  /* Parses 's', a string value for field 'mf', into 'value'.  Returns NULL if
   * successful, otherwise a malloc()'d string describing the error. */
  char *
  mf_parse_value(const struct mf_field *mf, const char *s, union mf_value *value)
  {
      union mf_value mask;
      char *error;
  
      error = mf_parse(mf, s, value, &mask);
      if (error) {
          return error;
      }
  
      if (!is_all_ones((const uint8_t *) &mask, mf->n_bytes)) {
          return xasprintf("%s: wildcards not allowed here", s);
      }
      return NULL;
  }
  
  static void
  mf_format_integer_string(const struct mf_field *mf, const uint8_t *valuep,
                           const uint8_t *maskp, struct ds *s)
  {
      unsigned long long int integer;
      int i;
  
      ovs_assert(mf->n_bytes <= 8);
  
      integer = 0;
      for (i = 0; i < mf->n_bytes; i++) {
          integer = (integer << 8) | valuep[i];
      }
      if (mf->string == MFS_HEXADECIMAL) {
          ds_put_format(s, "%#llx", integer);
      } else {
          ds_put_format(s, "%lld", integer);
      }
  
      if (maskp) {
          unsigned long long int mask;
  
          mask = 0;
          for (i = 0; i < mf->n_bytes; i++) {
              mask = (mask << 8) | maskp[i];
          }
  
          /* I guess we could write the mask in decimal for MFS_DECIMAL but I'm
           * not sure that that a bit-mask written in decimal is ever easier to
           * understand than the same bit-mask written in hexadecimal. */
          ds_put_format(s, "/%#llx", mask);
      }
  }
  
  static void
  mf_format_frag_string(uint8_t value, uint8_t mask, struct ds *s)
  {
      const struct frag_handling *h;
  
      mask &= FLOW_NW_FRAG_MASK;
      value &= mask;
  
      for (h = all_frags; h < &all_frags[ARRAY_SIZE(all_frags)]; h++) {
          if (value == h->value && mask == h->mask) {
              ds_put_cstr(s, h->name);
              return;
          }
      }
      ds_put_cstr(s, "<error>");
  }
  
  static void
  mf_format_tnl_flags_string(const ovs_be16 *valuep, struct ds *s)
  {
      format_flags(s, flow_tun_flag_to_string, ntohs(*valuep), '|');
  }
  
  static void
  mf_format_tcp_flags_string(ovs_be16 value, ovs_be16 mask, struct ds *s)
  {
      format_flags_masked(s, NULL, packet_tcp_flag_to_string, ntohs(value),
                          TCP_FLAGS(mask));
  }
  
  /* Appends to 's' a string representation of field 'mf' whose value is in
   * 'value' and 'mask'.  'mask' may be NULL to indicate an exact match. */
  void
  mf_format(const struct mf_field *mf,
            const union mf_value *value, const union mf_value *mask,
            struct ds *s)
  {
      if (mask) {
          if (is_all_zeros((const uint8_t *) mask, mf->n_bytes)) {
              ds_put_cstr(s, "ANY");
              return;
          } else if (is_all_ones((const uint8_t *) mask, mf->n_bytes)) {
              mask = NULL;
          }
      }
  
      switch (mf->string) {
      case MFS_OFP_PORT_OXM:
          if (!mask) {
              ofp_port_t port;
              ofputil_port_from_ofp11(value->be32, &port);
              ofputil_format_port(port, s);
              break;
          }
          /* fall through */
      case MFS_OFP_PORT:
          if (!mask) {
              ofputil_format_port(u16_to_ofp(ntohs(value->be16)), s);
              break;
          }
          /* fall through */
      case MFS_DECIMAL:
      case MFS_HEXADECIMAL:
          mf_format_integer_string(mf, (uint8_t *) value, (uint8_t *) mask, s);
          break;
  
      case MFS_ETHERNET:
          eth_format_masked(value->mac, mask->mac, s);
          break;
  
      case MFS_IPV4:
          ip_format_masked(value->be32, mask ? mask->be32 : OVS_BE32_MAX, s);
          break;
  
      case MFS_IPV6:
          print_ipv6_masked(s, &value->ipv6, mask ? &mask->ipv6 : NULL);
          break;
  
      case MFS_FRAG:
          mf_format_frag_string(value->u8, mask ? mask->u8 : UINT8_MAX, s);
          break;
  
      case MFS_TNL_FLAGS:
          mf_format_tnl_flags_string(&value->be16, s);
          break;
  
      case MFS_TCP_FLAGS:
          mf_format_tcp_flags_string(value->be16,
                                     mask ? mask->be16 : OVS_BE16_MAX, s);
          break;
  
      default:
          OVS_NOT_REACHED();
      }
  }
  
  /* Makes subfield 'sf' within 'flow' exactly match the 'sf->n_bits'
   * least-significant bits in 'x'.
   */
  void
  mf_write_subfield_flow(const struct mf_subfield *sf,
                         const union mf_subvalue *x, struct flow *flow)
  {
      const struct mf_field *field = sf->field;
      union mf_value value;
  
      mf_get_value(field, flow, &value);
      bitwise_copy(x, sizeof *x, 0, &value, field->n_bytes,
                   sf->ofs, sf->n_bits);
      mf_set_flow_value(field, &value, flow);
  }
  
  /* Makes subfield 'sf' within 'match' exactly match the 'sf->n_bits'
   * least-significant bits in 'x'.
   */
  void
  mf_write_subfield(const struct mf_subfield *sf, const union mf_subvalue *x,
                    struct match *match)
  {
      const struct mf_field *field = sf->field;
      union mf_value value, mask;
  
      mf_get(field, match, &value, &mask);
      bitwise_copy(x, sizeof *x, 0, &value, field->n_bytes, sf->ofs, sf->n_bits);
      bitwise_one (                 &mask,  field->n_bytes, sf->ofs, sf->n_bits);
      mf_set(field, &value, &mask, match);
  }
  
  /* Initializes 'x' to the value of 'sf' within 'flow'.  'sf' must be valid for
   * reading 'flow', e.g. as checked by mf_check_src(). */
  void
  mf_read_subfield(const struct mf_subfield *sf, const struct flow *flow,
                   union mf_subvalue *x)
  {
      union mf_value value;
  
      mf_get_value(sf->field, flow, &value);
  
      memset(x, 0, sizeof *x);
      bitwise_copy(&value, sf->field->n_bytes, sf->ofs,
                   x, sizeof *x, 0,
                   sf->n_bits);
  }
  
  /* Returns the value of 'sf' within 'flow'.  'sf' must be valid for reading
   * 'flow', e.g. as checked by mf_check_src() and sf->n_bits must be 64 or
   * less. */
  uint64_t
  mf_get_subfield(const struct mf_subfield *sf, const struct flow *flow)
  {
      union mf_value value;
  
      mf_get_value(sf->field, flow, &value);
      return bitwise_get(&value, sf->field->n_bytes, sf->ofs, sf->n_bits);
  }
  
  /* Formats 'sf' into 's' in a format normally acceptable to
   * mf_parse_subfield().  (It won't be acceptable if sf->field is NULL or if
   * sf->field has no NXM name.) */
  void
  mf_format_subfield(const struct mf_subfield *sf, struct ds *s)
  {
      if (!sf->field) {
          ds_put_cstr(s, "<unknown>");
      } else if (sf->field->nxm_name) {
          ds_put_cstr(s, sf->field->nxm_name);
      } else if (sf->field->nxm_header) {
          uint32_t header = sf->field->nxm_header;
          ds_put_format(s, "%d:%d", NXM_VENDOR(header), NXM_FIELD(header));
      } else {
          ds_put_cstr(s, sf->field->name);
      }
  
      if (sf->field && sf->ofs == 0 && sf->n_bits == sf->field->n_bits) {
          ds_put_cstr(s, "[]");
      } else if (sf->n_bits == 1) {
          ds_put_format(s, "[%d]", sf->ofs);
      } else {
          ds_put_format(s, "[%d..%d]", sf->ofs, sf->ofs + sf->n_bits - 1);
      }
  }
  
  static const struct mf_field *
  mf_parse_subfield_name(const char *name, int name_len, bool *wild)
  {
      int i;
  
      *wild = name_len > 2 && !memcmp(&name[name_len - 2], "_W", 2);
      if (*wild) {
          name_len -= 2;
      }
  
      for (i = 0; i < MFF_N_IDS; i++) {
          const struct mf_field *mf = mf_from_id(i);
  
          if (mf->nxm_name
              && !strncmp(mf->nxm_name, name, name_len)
              && mf->nxm_name[name_len] == '\0') {
              return mf;
          }
          if (mf->oxm_name
              && !strncmp(mf->oxm_name, name, name_len)
              && mf->oxm_name[name_len] == '\0') {
              return mf;
          }
      }
  
      return NULL;
  }
  
  /* Parses a subfield from the beginning of '*sp' into 'sf'.  If successful,
   * returns NULL and advances '*sp' to the first byte following the parsed
   * string.  On failure, returns a malloc()'d error message, does not modify
   * '*sp', and does not properly initialize 'sf'.
   *
   * The syntax parsed from '*sp' takes the form "header[start..end]" where
   * 'header' is the name of an NXM field and 'start' and 'end' are (inclusive)
   * bit indexes.  "..end" may be omitted to indicate a single bit.  "start..end"
   * may both be omitted (the [] are still required) to indicate an entire
   * field. */
  char * WARN_UNUSED_RESULT
  mf_parse_subfield__(struct mf_subfield *sf, const char **sp)
  {
      const struct mf_field *field;
      const char *name;
      int start, end;
      const char *s;
      int name_len;
      bool wild;
  
      s = *sp;
      name = s;
      name_len = strcspn(s, "[");
      if (s[name_len] != '[') {
          return xasprintf("%s: missing [ looking for field name", *sp);
      }
  
      field = mf_parse_subfield_name(name, name_len, &wild);
      if (!field) {
          return xasprintf("%s: unknown field `%.*s'", *sp, name_len, s);
      }
  
      s += name_len;
      if (ovs_scan(s, "[%d..%d]", &start, &end)) {
          /* Nothing to do. */
      } else if (ovs_scan(s, "[%d]", &start)) {
          end = start;
      } else if (!strncmp(s, "[]", 2)) {
          start = 0;
          end = field->n_bits - 1;
      } else {
          return xasprintf("%s: syntax error expecting [] or [<bit>] or "
                           "[<start>..<end>]", *sp);
      }
      s = strchr(s, ']') + 1;
  
      if (start > end) {
          return xasprintf("%s: starting bit %d is after ending bit %d",
                           *sp, start, end);
      } else if (start >= field->n_bits) {
          return xasprintf("%s: starting bit %d is not valid because field is "
                           "only %d bits wide", *sp, start, field->n_bits);
      } else if (end >= field->n_bits){
          return xasprintf("%s: ending bit %d is not valid because field is "
                           "only %d bits wide", *sp, end, field->n_bits);
      }
  
      sf->field = field;
      sf->ofs = start;
      sf->n_bits = end - start + 1;
  
      *sp = s;
      return NULL;
  }
  
  /* Parses a subfield from the entirety of 's' into 'sf'.  Returns NULL if
   * successful, otherwise a malloc()'d string describing the error.  The caller
   * is responsible for freeing the returned string.
   *
   * The syntax parsed from 's' takes the form "header[start..end]" where
   * 'header' is the name of an NXM field and 'start' and 'end' are (inclusive)
   * bit indexes.  "..end" may be omitted to indicate a single bit.  "start..end"
   * may both be omitted (the [] are still required) to indicate an entire
   * field.  */
  char * WARN_UNUSED_RESULT
  mf_parse_subfield(struct mf_subfield *sf, const char *s)
  {
      char *error = mf_parse_subfield__(sf, &s);
      if (!error && s[0]) {
          error = xstrdup("unexpected input following field syntax");
      }
      return error;
  }
  
  void
  mf_format_subvalue(const union mf_subvalue *subvalue, struct ds *s)
  {
      int i;
  
      for (i = 0; i < ARRAY_SIZE(subvalue->u8); i++) {
          if (subvalue->u8[i]) {
              ds_put_format(s, "0x%"PRIx8, subvalue->u8[i]);
              for (i++; i < ARRAY_SIZE(subvalue->u8); i++) {
                  ds_put_format(s, "%02"PRIx8, subvalue->u8[i]);
              }
              return;
          }
      }
      ds_put_char(s, '0');
  }
  