ovn-northd.c

/*
 * 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 <getopt.h>
#include <stdlib.h>
#include <stdio.h>

#include "command-line.h"
#include "daemon.h"
#include "dirs.h"
#include "openvswitch/dynamic-string.h"
#include "fatal-signal.h"
#include "hash.h"
#include "hmap.h"
#include "json.h"
#include "ovn/lib/lex.h"
#include "ovn/lib/ovn-nb-idl.h"
#include "ovn/lib/ovn-sb-idl.h"
#include "ovn/lib/ovn-util.h"
#include "packets.h"
#include "poll-loop.h"
#include "smap.h"
#include "sset.h"
#include "stream.h"
#include "stream-ssl.h"
#include "unixctl.h"
#include "util.h"
#include "uuid.h"
#include "openvswitch/vlog.h"

VLOG_DEFINE_THIS_MODULE(ovn_northd);

static unixctl_cb_func ovn_northd_exit;

struct northd_context {
    struct ovsdb_idl *ovnnb_idl;
    struct ovsdb_idl *ovnsb_idl;
    struct ovsdb_idl_txn *ovnnb_txn;
    struct ovsdb_idl_txn *ovnsb_txn;
};

static const char *ovnnb_db;
static const char *ovnsb_db;

static const char *default_nb_db(void);
static const char *default_sb_db(void);

/* Pipeline stages. */

/* The two pipelines in an OVN logical flow table. */
enum ovn_pipeline {
    P_IN,                       /* Ingress pipeline. */
    P_OUT                       /* Egress pipeline. */
};

/* The two purposes for which ovn-northd uses OVN logical datapaths. */
enum ovn_datapath_type {
    DP_SWITCH,                  /* OVN logical switch. */
    DP_ROUTER                   /* OVN logical router. */
};

/* Returns an "enum ovn_stage" built from the arguments.
 *
 * (It's better to use ovn_stage_build() for type-safety reasons, but inline
 * functions can't be used in enums or switch cases.) */
#define OVN_STAGE_BUILD(DP_TYPE, PIPELINE, TABLE) \
    (((DP_TYPE) << 9) | ((PIPELINE) << 8) | (TABLE))

/* A stage within an OVN logical switch or router.
 *
 * An "enum ovn_stage" indicates whether the stage is part of a logical switch
 * or router, whether the stage is part of the ingress or egress pipeline, and
 * the table within that pipeline.  The first three components are combined to
 * form the stage's full name, e.g. S_SWITCH_IN_PORT_SEC_L2,
 * S_ROUTER_OUT_DELIVERY. */
enum ovn_stage {
#define PIPELINE_STAGES                                               \
    /* Logical switch ingress stages. */                              \
    PIPELINE_STAGE(SWITCH, IN,  PORT_SEC_L2,    0, "ls_in_port_sec_l2")     \
    PIPELINE_STAGE(SWITCH, IN,  PORT_SEC_IP,    1, "ls_in_port_sec_ip")     \
    PIPELINE_STAGE(SWITCH, IN,  PORT_SEC_ND,    2, "ls_in_port_sec_nd")     \
    PIPELINE_STAGE(SWITCH, IN,  PRE_ACL,        3, "ls_in_pre_acl")      \
    PIPELINE_STAGE(SWITCH, IN,  PRE_LB,         4, "ls_in_pre_lb")         \
    PIPELINE_STAGE(SWITCH, IN,  PRE_STATEFUL,   5, "ls_in_pre_stateful")    \
    PIPELINE_STAGE(SWITCH, IN,  ACL,            6, "ls_in_acl")          \
    PIPELINE_STAGE(SWITCH, IN,  LB,             7, "ls_in_lb")           \
    PIPELINE_STAGE(SWITCH, IN,  STATEFUL,       8, "ls_in_stateful")     \
    PIPELINE_STAGE(SWITCH, IN,  ARP_RSP,        9, "ls_in_arp_rsp")      \
    PIPELINE_STAGE(SWITCH, IN,  L2_LKUP,       10, "ls_in_l2_lkup")      \
                                                                      \
    /* Logical switch egress stages. */                               \
    PIPELINE_STAGE(SWITCH, OUT, PRE_LB,       0, "ls_out_pre_lb")     \
    PIPELINE_STAGE(SWITCH, OUT, PRE_ACL,      1, "ls_out_pre_acl")     \
    PIPELINE_STAGE(SWITCH, OUT, PRE_STATEFUL, 2, "ls_out_pre_stateful")  \
    PIPELINE_STAGE(SWITCH, OUT, LB,           3, "ls_out_lb")            \
    PIPELINE_STAGE(SWITCH, OUT, ACL,          4, "ls_out_acl")            \
    PIPELINE_STAGE(SWITCH, OUT, STATEFUL,     5, "ls_out_stateful")       \
    PIPELINE_STAGE(SWITCH, OUT, PORT_SEC_IP,  6, "ls_out_port_sec_ip")    \
    PIPELINE_STAGE(SWITCH, OUT, PORT_SEC_L2,  7, "ls_out_port_sec_l2")    \
                                                                      \
    /* Logical router ingress stages. */                              \
    PIPELINE_STAGE(ROUTER, IN,  ADMISSION,   0, "lr_in_admission")    \
    PIPELINE_STAGE(ROUTER, IN,  IP_INPUT,    1, "lr_in_ip_input")     \
    PIPELINE_STAGE(ROUTER, IN,  UNSNAT,      2, "lr_in_unsnat")       \
    PIPELINE_STAGE(ROUTER, IN,  DNAT,        3, "lr_in_dnat")         \
    PIPELINE_STAGE(ROUTER, IN,  IP_ROUTING,  4, "lr_in_ip_routing")   \
    PIPELINE_STAGE(ROUTER, IN,  ARP_RESOLVE, 5, "lr_in_arp_resolve")  \
    PIPELINE_STAGE(ROUTER, IN,  ARP_REQUEST, 6, "lr_in_arp_request")  \
                                                                      \
    /* Logical router egress stages. */                               \
    PIPELINE_STAGE(ROUTER, OUT, SNAT,      0, "lr_out_snat")          \
    PIPELINE_STAGE(ROUTER, OUT, DELIVERY,  1, "lr_out_delivery")

#define PIPELINE_STAGE(DP_TYPE, PIPELINE, STAGE, TABLE, NAME)   \
    S_##DP_TYPE##_##PIPELINE##_##STAGE                          \
        = OVN_STAGE_BUILD(DP_##DP_TYPE, P_##PIPELINE, TABLE),
    PIPELINE_STAGES
#undef PIPELINE_STAGE
};

/* Due to various hard-coded priorities need to implement ACLs, the
 * northbound database supports a smaller range of ACL priorities than
 * are available to logical flows.  This value is added to an ACL
 * priority to determine the ACL's logical flow priority. */
#define OVN_ACL_PRI_OFFSET 1000

/* Returns an "enum ovn_stage" built from the arguments. */
static enum ovn_stage
ovn_stage_build(enum ovn_datapath_type dp_type, enum ovn_pipeline pipeline,
                uint8_t table)
{
    return OVN_STAGE_BUILD(dp_type, pipeline, table);
}

/* Returns the pipeline to which 'stage' belongs. */
static enum ovn_pipeline
ovn_stage_get_pipeline(enum ovn_stage stage)
{
    return (stage >> 8) & 1;
}

/* Returns the table to which 'stage' belongs. */
static uint8_t
ovn_stage_get_table(enum ovn_stage stage)
{
    return stage & 0xff;
}

/* Returns a string name for 'stage'. */
static const char *
ovn_stage_to_str(enum ovn_stage stage)
{
    switch (stage) {
#define PIPELINE_STAGE(DP_TYPE, PIPELINE, STAGE, TABLE, NAME)       \
        case S_##DP_TYPE##_##PIPELINE##_##STAGE: return NAME;
    PIPELINE_STAGES
#undef PIPELINE_STAGE
        default: return "<unknown>";
    }
}

static void
usage(void)
{
    printf("\
%s: OVN northbound management daemon\n\
usage: %s [OPTIONS]\n\
\n\
Options:\n\
  --ovnnb-db=DATABASE       connect to ovn-nb database at DATABASE\n\
                            (default: %s)\n\
  --ovnsb-db=DATABASE       connect to ovn-sb database at DATABASE\n\
                            (default: %s)\n\
  -h, --help                display this help message\n\
  -o, --options             list available options\n\
  -V, --version             display version information\n\
", program_name, program_name, default_nb_db(), default_sb_db());
    daemon_usage();
    vlog_usage();
    stream_usage("database", true, true, false);
}

struct tnlid_node {
    struct hmap_node hmap_node;
    uint32_t tnlid;
};

static void
destroy_tnlids(struct hmap *tnlids)
{
    struct tnlid_node *node;
    HMAP_FOR_EACH_POP (node, hmap_node, tnlids) {
        free(node);
    }
    hmap_destroy(tnlids);
}

static void
add_tnlid(struct hmap *set, uint32_t tnlid)
{
    struct tnlid_node *node = xmalloc(sizeof *node);
    hmap_insert(set, &node->hmap_node, hash_int(tnlid, 0));
    node->tnlid = tnlid;
}

static bool
tnlid_in_use(const struct hmap *set, uint32_t tnlid)
{
    const struct tnlid_node *node;
    HMAP_FOR_EACH_IN_BUCKET (node, hmap_node, hash_int(tnlid, 0), set) {
        if (node->tnlid == tnlid) {
            return true;
        }
    }
    return false;
}

static uint32_t
allocate_tnlid(struct hmap *set, const char *name, uint32_t max,
               uint32_t *hint)
{
    for (uint32_t tnlid = *hint + 1; tnlid != *hint;
         tnlid = tnlid + 1 <= max ? tnlid + 1 : 1) {
        if (!tnlid_in_use(set, tnlid)) {
            add_tnlid(set, tnlid);
            *hint = tnlid;
            return tnlid;
        }
    }

    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
    VLOG_WARN_RL(&rl, "all %s tunnel ids exhausted", name);
    return 0;
}

/* The 'key' comes from nbs->header_.uuid or nbr->header_.uuid or
 * sb->external_ids:logical-switch. */
struct ovn_datapath {
    struct hmap_node key_node;  /* Index on 'key'. */
    struct uuid key;            /* (nbs/nbr)->header_.uuid. */

    const struct nbrec_logical_switch *nbs;  /* May be NULL. */
    const struct nbrec_logical_router *nbr;  /* May be NULL. */
    const struct sbrec_datapath_binding *sb; /* May be NULL. */

    struct ovs_list list;       /* In list of similar records. */

    /* Logical router data (digested from nbr). */
    const struct ovn_port *gateway_port;
    ovs_be32 gateway;

    /* Logical switch data. */
    struct ovn_port **router_ports;
    size_t n_router_ports;

    struct hmap port_tnlids;
    uint32_t port_key_hint;

    bool has_unknown;
};

static struct ovn_datapath *
ovn_datapath_create(struct hmap *datapaths, const struct uuid *key,
                    const struct nbrec_logical_switch *nbs,
                    const struct nbrec_logical_router *nbr,
                    const struct sbrec_datapath_binding *sb)
{
    struct ovn_datapath *od = xzalloc(sizeof *od);
    od->key = *key;
    od->sb = sb;
    od->nbs = nbs;
    od->nbr = nbr;
    hmap_init(&od->port_tnlids);
    od->port_key_hint = 0;
    hmap_insert(datapaths, &od->key_node, uuid_hash(&od->key));
    return od;
}

static void
ovn_datapath_destroy(struct hmap *datapaths, struct ovn_datapath *od)
{
    if (od) {
        /* Don't remove od->list.  It is used within build_datapaths() as a
         * private list and once we've exited that function it is not safe to
         * use it. */
        hmap_remove(datapaths, &od->key_node);
        destroy_tnlids(&od->port_tnlids);
        free(od->router_ports);
        free(od);
    }
}

static struct ovn_datapath *
ovn_datapath_find(struct hmap *datapaths, const struct uuid *uuid)
{
    struct ovn_datapath *od;

    HMAP_FOR_EACH_WITH_HASH (od, key_node, uuid_hash(uuid), datapaths) {
        if (uuid_equals(uuid, &od->key)) {
            return od;
        }
    }
    return NULL;
}

static struct ovn_datapath *
ovn_datapath_from_sbrec(struct hmap *datapaths,
                        const struct sbrec_datapath_binding *sb)
{
    struct uuid key;

    if (!smap_get_uuid(&sb->external_ids, "logical-switch", &key) &&
        !smap_get_uuid(&sb->external_ids, "logical-router", &key)) {
        return NULL;
    }
    return ovn_datapath_find(datapaths, &key);
}

static bool
lrouter_is_enabled(const struct nbrec_logical_router *lrouter)
{
    return !lrouter->enabled || *lrouter->enabled;
}

static void
join_datapaths(struct northd_context *ctx, struct hmap *datapaths,
               struct ovs_list *sb_only, struct ovs_list *nb_only,
               struct ovs_list *both)
{
    hmap_init(datapaths);
    ovs_list_init(sb_only);
    ovs_list_init(nb_only);
    ovs_list_init(both);

    const struct sbrec_datapath_binding *sb, *sb_next;
    SBREC_DATAPATH_BINDING_FOR_EACH_SAFE (sb, sb_next, ctx->ovnsb_idl) {
        struct uuid key;
        if (!smap_get_uuid(&sb->external_ids, "logical-switch", &key) &&
            !smap_get_uuid(&sb->external_ids, "logical-router", &key)) {
            ovsdb_idl_txn_add_comment(
                ctx->ovnsb_txn,
                "deleting Datapath_Binding "UUID_FMT" that lacks "
                "external-ids:logical-switch and "
                "external-ids:logical-router",
                UUID_ARGS(&sb->header_.uuid));
            sbrec_datapath_binding_delete(sb);
            continue;
        }

        if (ovn_datapath_find(datapaths, &key)) {
            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
            VLOG_INFO_RL(
                &rl, "deleting Datapath_Binding "UUID_FMT" with "
                "duplicate external-ids:logical-switch/router "UUID_FMT,
                UUID_ARGS(&sb->header_.uuid), UUID_ARGS(&key));
            sbrec_datapath_binding_delete(sb);
            continue;
        }

        struct ovn_datapath *od = ovn_datapath_create(datapaths, &key,
                                                      NULL, NULL, sb);
        ovs_list_push_back(sb_only, &od->list);
    }

    const struct nbrec_logical_switch *nbs;
    NBREC_LOGICAL_SWITCH_FOR_EACH (nbs, ctx->ovnnb_idl) {
        struct ovn_datapath *od = ovn_datapath_find(datapaths,
                                                    &nbs->header_.uuid);
        if (od) {
            od->nbs = nbs;
            ovs_list_remove(&od->list);
            ovs_list_push_back(both, &od->list);
        } else {
            od = ovn_datapath_create(datapaths, &nbs->header_.uuid,
                                     nbs, NULL, NULL);
            ovs_list_push_back(nb_only, &od->list);
        }
    }

    const struct nbrec_logical_router *nbr;
    NBREC_LOGICAL_ROUTER_FOR_EACH (nbr, ctx->ovnnb_idl) {
        if (!lrouter_is_enabled(nbr)) {
            continue;
        }

        struct ovn_datapath *od = ovn_datapath_find(datapaths,
                                                    &nbr->header_.uuid);
        if (od) {
            if (!od->nbs) {
                od->nbr = nbr;
                ovs_list_remove(&od->list);
                ovs_list_push_back(both, &od->list);
            } else {
                /* Can't happen! */
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl,
                             "duplicate UUID "UUID_FMT" in OVN_Northbound",
                             UUID_ARGS(&nbr->header_.uuid));
                continue;
            }
        } else {
            od = ovn_datapath_create(datapaths, &nbr->header_.uuid,
                                     NULL, nbr, NULL);
            ovs_list_push_back(nb_only, &od->list);
        }

        od->gateway = 0;
        if (nbr->default_gw) {
            ovs_be32 ip;
            if (!ip_parse(nbr->default_gw, &ip) || !ip) {
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad 'gateway' %s", nbr->default_gw);
            } else {
                od->gateway = ip;
            }
        }

        /* Set the gateway port to NULL.  If there is a gateway, it will get
         * filled in as we go through the ports later. */
        od->gateway_port = NULL;
    }
}

static uint32_t
ovn_datapath_allocate_key(struct hmap *dp_tnlids)
{
    static uint32_t hint;
    return allocate_tnlid(dp_tnlids, "datapath", (1u << 24) - 1, &hint);
}

/* Updates the southbound Datapath_Binding table so that it contains the
 * logical switches and routers specified by the northbound database.
 *
 * Initializes 'datapaths' to contain a "struct ovn_datapath" for every logical
 * switch and router. */
static void
build_datapaths(struct northd_context *ctx, struct hmap *datapaths)
{
    struct ovs_list sb_only, nb_only, both;

    join_datapaths(ctx, datapaths, &sb_only, &nb_only, &both);

    if (!ovs_list_is_empty(&nb_only)) {
        /* First index the in-use datapath tunnel IDs. */
        struct hmap dp_tnlids = HMAP_INITIALIZER(&dp_tnlids);
        struct ovn_datapath *od;
        LIST_FOR_EACH (od, list, &both) {
            add_tnlid(&dp_tnlids, od->sb->tunnel_key);
        }

        /* Add southbound record for each unmatched northbound record. */
        LIST_FOR_EACH (od, list, &nb_only) {
            uint16_t tunnel_key = ovn_datapath_allocate_key(&dp_tnlids);
            if (!tunnel_key) {
                break;
            }

            od->sb = sbrec_datapath_binding_insert(ctx->ovnsb_txn);

            char uuid_s[UUID_LEN + 1];
            sprintf(uuid_s, UUID_FMT, UUID_ARGS(&od->key));
            const char *key = od->nbs ? "logical-switch" : "logical-router";
            const struct smap id = SMAP_CONST1(&id, key, uuid_s);
            sbrec_datapath_binding_set_external_ids(od->sb, &id);

            sbrec_datapath_binding_set_tunnel_key(od->sb, tunnel_key);
        }
        destroy_tnlids(&dp_tnlids);
    }

    /* Delete southbound records without northbound matches. */
    struct ovn_datapath *od, *next;
    LIST_FOR_EACH_SAFE (od, next, list, &sb_only) {
        ovs_list_remove(&od->list);
        sbrec_datapath_binding_delete(od->sb);
        ovn_datapath_destroy(datapaths, od);
    }
}

struct ovn_port {
    struct hmap_node key_node;  /* Index on 'key'. */
    char *key;                  /* nbs->name, nbr->name, sb->logical_port. */
    char *json_key;             /* 'key', quoted for use in JSON. */

    const struct nbrec_logical_switch_port *nbs; /* May be NULL. */
    const struct nbrec_logical_router_port *nbr; /* May be NULL. */
    const struct sbrec_port_binding *sb;         /* May be NULL. */

    /* Logical router port data. */
    ovs_be32 ip, mask;          /* 192.168.10.123/24. */
    ovs_be32 network;           /* 192.168.10.0. */
    ovs_be32 bcast;             /* 192.168.10.255. */
    struct eth_addr mac;
    struct ovn_port *peer;

    struct ovn_datapath *od;

    struct ovs_list list;       /* In list of similar records. */
};

static struct ovn_port *
ovn_port_create(struct hmap *ports, const char *key,
                const struct nbrec_logical_switch_port *nbs,
                const struct nbrec_logical_router_port *nbr,
                const struct sbrec_port_binding *sb)
{
    struct ovn_port *op = xzalloc(sizeof *op);

    struct ds json_key = DS_EMPTY_INITIALIZER;
    json_string_escape(key, &json_key);
    op->json_key = ds_steal_cstr(&json_key);

    op->key = xstrdup(key);
    op->sb = sb;
    op->nbs = nbs;
    op->nbr = nbr;
    hmap_insert(ports, &op->key_node, hash_string(op->key, 0));
    return op;
}

static void
ovn_port_destroy(struct hmap *ports, struct ovn_port *port)
{
    if (port) {
        /* Don't remove port->list.  It is used within build_ports() as a
         * private list and once we've exited that function it is not safe to
         * use it. */
        hmap_remove(ports, &port->key_node);
        free(port->json_key);
        free(port->key);
        free(port);
    }
}

static struct ovn_port *
ovn_port_find(struct hmap *ports, const char *name)
{
    struct ovn_port *op;

    HMAP_FOR_EACH_WITH_HASH (op, key_node, hash_string(name, 0), ports) {
        if (!strcmp(op->key, name)) {
            return op;
        }
    }
    return NULL;
}

static uint32_t
ovn_port_allocate_key(struct ovn_datapath *od)
{
    return allocate_tnlid(&od->port_tnlids, "port",
                          (1u << 15) - 1, &od->port_key_hint);
}

static void
join_logical_ports(struct northd_context *ctx,
                   struct hmap *datapaths, struct hmap *ports,
                   struct ovs_list *sb_only, struct ovs_list *nb_only,
                   struct ovs_list *both)
{
    hmap_init(ports);
    ovs_list_init(sb_only);
    ovs_list_init(nb_only);
    ovs_list_init(both);

    const struct sbrec_port_binding *sb;
    SBREC_PORT_BINDING_FOR_EACH (sb, ctx->ovnsb_idl) {
        struct ovn_port *op = ovn_port_create(ports, sb->logical_port,
                                              NULL, NULL, sb);
        ovs_list_push_back(sb_only, &op->list);
    }

    struct ovn_datapath *od;
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (od->nbs) {
            for (size_t i = 0; i < od->nbs->n_ports; i++) {
                const struct nbrec_logical_switch_port *nbs = od->nbs->ports[i];
                struct ovn_port *op = ovn_port_find(ports, nbs->name);
                if (op) {
                    if (op->nbs || op->nbr) {
                        static struct vlog_rate_limit rl
                            = VLOG_RATE_LIMIT_INIT(5, 1);
                        VLOG_WARN_RL(&rl, "duplicate logical port %s",
                                     nbs->name);
                        continue;
                    }
                    op->nbs = nbs;
                    ovs_list_remove(&op->list);
                    ovs_list_push_back(both, &op->list);
                } else {
                    op = ovn_port_create(ports, nbs->name, nbs, NULL, NULL);
                    ovs_list_push_back(nb_only, &op->list);
                }

                op->od = od;
            }
        } else {
            for (size_t i = 0; i < od->nbr->n_ports; i++) {
                const struct nbrec_logical_router_port *nbr
                    = od->nbr->ports[i];

                struct eth_addr mac;
                if (!eth_addr_from_string(nbr->mac, &mac)) {
                    static struct vlog_rate_limit rl
                        = VLOG_RATE_LIMIT_INIT(5, 1);
                    VLOG_WARN_RL(&rl, "bad 'mac' %s", nbr->mac);
                    continue;
                }

                ovs_be32 ip, mask;
                char *error = ip_parse_masked(nbr->network, &ip, &mask);
                if (error || mask == OVS_BE32_MAX || !ip_is_cidr(mask)) {
                    static struct vlog_rate_limit rl
                        = VLOG_RATE_LIMIT_INIT(5, 1);
                    VLOG_WARN_RL(&rl, "bad 'network' %s", nbr->network);
                    free(error);
                    continue;
                }

                struct ovn_port *op = ovn_port_find(ports, nbr->name);
                if (op) {
                    if (op->nbs || op->nbr) {
                        static struct vlog_rate_limit rl
                            = VLOG_RATE_LIMIT_INIT(5, 1);
                        VLOG_WARN_RL(&rl, "duplicate logical router port %s",
                                     nbr->name);
                        continue;
                    }
                    op->nbr = nbr;
                    ovs_list_remove(&op->list);
                    ovs_list_push_back(both, &op->list);
                } else {
                    op = ovn_port_create(ports, nbr->name, NULL, nbr, NULL);
                    ovs_list_push_back(nb_only, &op->list);
                }

                op->ip = ip;
                op->mask = mask;
                op->network = ip & mask;
                op->bcast = ip | ~mask;
                op->mac = mac;

                op->od = od;

                /* If 'od' has a gateway and 'op' routes to it... */
                if (od->gateway && !((op->network ^ od->gateway) & op->mask)) {
                    /* ...and if 'op' is a longer match than the current
                     * choice... */
                    const struct ovn_port *gw = od->gateway_port;
                    int len = gw ? ip_count_cidr_bits(gw->mask) : 0;
                    if (ip_count_cidr_bits(op->mask) > len) {
                        /* ...then it's the default gateway port. */
                        od->gateway_port = op;
                    }
                }
            }
        }
    }

    /* Connect logical router ports, and logical switch ports of type "router",
     * to their peers. */
    struct ovn_port *op;
    HMAP_FOR_EACH (op, key_node, ports) {
        if (op->nbs && !strcmp(op->nbs->type, "router")) {
            const char *peer_name = smap_get(&op->nbs->options, "router-port");
            if (!peer_name) {
                continue;
            }

            struct ovn_port *peer = ovn_port_find(ports, peer_name);
            if (!peer || !peer->nbr) {
                continue;
            }

            peer->peer = op;
            op->peer = peer;
            op->od->router_ports = xrealloc(
                op->od->router_ports,
                sizeof *op->od->router_ports * (op->od->n_router_ports + 1));
            op->od->router_ports[op->od->n_router_ports++] = op;
        } else if (op->nbr && op->nbr->peer) {
            op->peer = ovn_port_find(ports, op->nbr->peer);
        }
    }
}

static void
ovn_port_update_sbrec(const struct ovn_port *op)
{
    sbrec_port_binding_set_datapath(op->sb, op->od->sb);
    if (op->nbr) {
        /* If the router is for l3 gateway, it resides on a chassis
         * and its port type is "gateway". */
        const char *chassis = smap_get(&op->od->nbr->options, "chassis");
        if (chassis) {
            sbrec_port_binding_set_type(op->sb, "gateway");
        } else {
            sbrec_port_binding_set_type(op->sb, "patch");
        }

        const char *peer = op->peer ? op->peer->key : "<error>";
        struct smap new;
        smap_init(&new);
        smap_add(&new, "peer", peer);
        if (chassis) {
            smap_add(&new, "gateway-chassis", chassis);
        }
        sbrec_port_binding_set_options(op->sb, &new);
        smap_destroy(&new);

        sbrec_port_binding_set_parent_port(op->sb, NULL);
        sbrec_port_binding_set_tag(op->sb, NULL, 0);
        sbrec_port_binding_set_mac(op->sb, NULL, 0);
    } else {
        if (strcmp(op->nbs->type, "router")) {
            sbrec_port_binding_set_type(op->sb, op->nbs->type);
            sbrec_port_binding_set_options(op->sb, &op->nbs->options);
        } else {
            const char *chassis = NULL;
            if (op->peer && op->peer->od && op->peer->od->nbr) {
                chassis = smap_get(&op->peer->od->nbr->options, "chassis");
            }

            /* A switch port connected to a gateway router is also of
             * type "gateway". */
            if (chassis) {
                sbrec_port_binding_set_type(op->sb, "gateway");
            } else {
                sbrec_port_binding_set_type(op->sb, "patch");
            }

            const char *router_port = smap_get(&op->nbs->options,
                                               "router-port");
            if (!router_port) {
                router_port = "<error>";
            }
            struct smap new;
            smap_init(&new);
            smap_add(&new, "peer", router_port);
            if (chassis) {
                smap_add(&new, "gateway-chassis", chassis);
            }
            sbrec_port_binding_set_options(op->sb, &new);
            smap_destroy(&new);
        }
        sbrec_port_binding_set_parent_port(op->sb, op->nbs->parent_name);
        sbrec_port_binding_set_tag(op->sb, op->nbs->tag, op->nbs->n_tag);
        sbrec_port_binding_set_mac(op->sb, (const char **) op->nbs->addresses,
                                   op->nbs->n_addresses);
    }
}

/* Updates the southbound Port_Binding table so that it contains the logical
 * switch ports specified by the northbound database.
 *
 * Initializes 'ports' to contain a "struct ovn_port" for every logical port,
 * using the "struct ovn_datapath"s in 'datapaths' to look up logical
 * datapaths. */
static void
build_ports(struct northd_context *ctx, struct hmap *datapaths,
            struct hmap *ports)
{
    struct ovs_list sb_only, nb_only, both;

    join_logical_ports(ctx, datapaths, ports, &sb_only, &nb_only, &both);

    /* For logical ports that are in both databases, update the southbound
     * record based on northbound data.  Also index the in-use tunnel_keys. */
    struct ovn_port *op, *next;
    LIST_FOR_EACH_SAFE (op, next, list, &both) {
        ovn_port_update_sbrec(op);

        add_tnlid(&op->od->port_tnlids, op->sb->tunnel_key);
        if (op->sb->tunnel_key > op->od->port_key_hint) {
            op->od->port_key_hint = op->sb->tunnel_key;
        }
    }

    /* Add southbound record for each unmatched northbound record. */
    LIST_FOR_EACH_SAFE (op, next, list, &nb_only) {
        uint16_t tunnel_key = ovn_port_allocate_key(op->od);
        if (!tunnel_key) {
            continue;
        }

        op->sb = sbrec_port_binding_insert(ctx->ovnsb_txn);
        ovn_port_update_sbrec(op);

        sbrec_port_binding_set_logical_port(op->sb, op->key);
        sbrec_port_binding_set_tunnel_key(op->sb, tunnel_key);
    }

    /* Delete southbound records without northbound matches. */
    LIST_FOR_EACH_SAFE(op, next, list, &sb_only) {
        ovs_list_remove(&op->list);
        sbrec_port_binding_delete(op->sb);
        ovn_port_destroy(ports, op);
    }
}

#define OVN_MIN_MULTICAST 32768
#define OVN_MAX_MULTICAST 65535

struct multicast_group {
    const char *name;
    uint16_t key;               /* OVN_MIN_MULTICAST...OVN_MAX_MULTICAST. */
};

#define MC_FLOOD "_MC_flood"
static const struct multicast_group mc_flood = { MC_FLOOD, 65535 };

#define MC_UNKNOWN "_MC_unknown"
static const struct multicast_group mc_unknown = { MC_UNKNOWN, 65534 };

static bool
multicast_group_equal(const struct multicast_group *a,
                      const struct multicast_group *b)
{
    return !strcmp(a->name, b->name) && a->key == b->key;
}

/* Multicast group entry. */
struct ovn_multicast {
    struct hmap_node hmap_node; /* Index on 'datapath' and 'key'. */
    struct ovn_datapath *datapath;
    const struct multicast_group *group;

    struct ovn_port **ports;
    size_t n_ports, allocated_ports;
};

static uint32_t
ovn_multicast_hash(const struct ovn_datapath *datapath,
                   const struct multicast_group *group)
{
    return hash_pointer(datapath, group->key);
}

static struct ovn_multicast *
ovn_multicast_find(struct hmap *mcgroups, struct ovn_datapath *datapath,
                   const struct multicast_group *group)
{
    struct ovn_multicast *mc;

    HMAP_FOR_EACH_WITH_HASH (mc, hmap_node,
                             ovn_multicast_hash(datapath, group), mcgroups) {
        if (mc->datapath == datapath
            && multicast_group_equal(mc->group, group)) {
            return mc;
        }
    }
    return NULL;
}

static void
ovn_multicast_add(struct hmap *mcgroups, const struct multicast_group *group,
                  struct ovn_port *port)
{
    struct ovn_datapath *od = port->od;
    struct ovn_multicast *mc = ovn_multicast_find(mcgroups, od, group);
    if (!mc) {
        mc = xmalloc(sizeof *mc);
        hmap_insert(mcgroups, &mc->hmap_node, ovn_multicast_hash(od, group));
        mc->datapath = od;
        mc->group = group;
        mc->n_ports = 0;
        mc->allocated_ports = 4;
        mc->ports = xmalloc(mc->allocated_ports * sizeof *mc->ports);
    }
    if (mc->n_ports >= mc->allocated_ports) {
        mc->ports = x2nrealloc(mc->ports, &mc->allocated_ports,
                               sizeof *mc->ports);
    }
    mc->ports[mc->n_ports++] = port;
}

static void
ovn_multicast_destroy(struct hmap *mcgroups, struct ovn_multicast *mc)
{
    if (mc) {
        hmap_remove(mcgroups, &mc->hmap_node);
        free(mc->ports);
        free(mc);
    }
}

static void
ovn_multicast_update_sbrec(const struct ovn_multicast *mc,
                           const struct sbrec_multicast_group *sb)
{
    struct sbrec_port_binding **ports = xmalloc(mc->n_ports * sizeof *ports);
    for (size_t i = 0; i < mc->n_ports; i++) {
        ports[i] = CONST_CAST(struct sbrec_port_binding *, mc->ports[i]->sb);
    }
    sbrec_multicast_group_set_ports(sb, ports, mc->n_ports);
    free(ports);
}

/* Logical flow generation.
 *
 * This code generates the Logical_Flow table in the southbound database, as a
 * function of most of the northbound database.
 */

struct ovn_lflow {
    struct hmap_node hmap_node;

    struct ovn_datapath *od;
    enum ovn_stage stage;
    uint16_t priority;
    char *match;
    char *actions;
};

static size_t
ovn_lflow_hash(const struct ovn_lflow *lflow)
{
    size_t hash = uuid_hash(&lflow->od->key);
    hash = hash_2words((lflow->stage << 16) | lflow->priority, hash);
    hash = hash_string(lflow->match, hash);
    return hash_string(lflow->actions, hash);
}

static bool
ovn_lflow_equal(const struct ovn_lflow *a, const struct ovn_lflow *b)
{
    return (a->od == b->od
            && a->stage == b->stage
            && a->priority == b->priority
            && !strcmp(a->match, b->match)
            && !strcmp(a->actions, b->actions));
}

static void
ovn_lflow_init(struct ovn_lflow *lflow, struct ovn_datapath *od,
              enum ovn_stage stage, uint16_t priority,
              char *match, char *actions)
{
    lflow->od = od;
    lflow->stage = stage;
    lflow->priority = priority;
    lflow->match = match;
    lflow->actions = actions;
}

/* Adds a row with the specified contents to the Logical_Flow table. */
static void
ovn_lflow_add(struct hmap *lflow_map, struct ovn_datapath *od,
              enum ovn_stage stage, uint16_t priority,
              const char *match, const char *actions)
{
    struct ovn_lflow *lflow = xmalloc(sizeof *lflow);
    ovn_lflow_init(lflow, od, stage, priority,
                   xstrdup(match), xstrdup(actions));
    hmap_insert(lflow_map, &lflow->hmap_node, ovn_lflow_hash(lflow));
}

static struct ovn_lflow *
ovn_lflow_find(struct hmap *lflows, struct ovn_datapath *od,
               enum ovn_stage stage, uint16_t priority,
               const char *match, const char *actions)
{
    struct ovn_lflow target;
    ovn_lflow_init(&target, od, stage, priority,
                   CONST_CAST(char *, match), CONST_CAST(char *, actions));

    struct ovn_lflow *lflow;
    HMAP_FOR_EACH_WITH_HASH (lflow, hmap_node, ovn_lflow_hash(&target),
                             lflows) {
        if (ovn_lflow_equal(lflow, &target)) {
            return lflow;
        }
    }
    return NULL;
}

static void
ovn_lflow_destroy(struct hmap *lflows, struct ovn_lflow *lflow)
{
    if (lflow) {
        hmap_remove(lflows, &lflow->hmap_node);
        free(lflow->match);
        free(lflow->actions);
        free(lflow);
    }
}

/* Appends port security constraints on L2 address field 'eth_addr_field'
 * (e.g. "eth.src" or "eth.dst") to 'match'.  'port_security', with
 * 'n_port_security' elements, is the collection of port_security constraints
 * from an OVN_NB Logical_Switch_Port row. */
static void
build_port_security_l2(const char *eth_addr_field,
                       char **port_security, size_t n_port_security,
                       struct ds *match)
{
    size_t base_len = match->length;
    ds_put_format(match, " && %s == {", eth_addr_field);

    size_t n = 0;
    for (size_t i = 0; i < n_port_security; i++) {
        struct eth_addr ea;

        if (eth_addr_from_string(port_security[i], &ea)) {
            ds_put_format(match, ETH_ADDR_FMT, ETH_ADDR_ARGS(ea));
            ds_put_char(match, ' ');
            n++;
        }
    }
    ds_chomp(match, ' ');
    ds_put_cstr(match, "}");

    if (!n) {
        match->length = base_len;
    }
}

static void
build_port_security_ipv6_nd_flow(
    struct ds *match, struct eth_addr ea, struct ipv6_netaddr *ipv6_addrs,
    int n_ipv6_addrs)
{
    ds_put_format(match, " && ip6 && nd && ((nd.sll == "ETH_ADDR_FMT" || "
                  "nd.sll == "ETH_ADDR_FMT") || ((nd.tll == "ETH_ADDR_FMT" || "
                  "nd.tll == "ETH_ADDR_FMT")", ETH_ADDR_ARGS(eth_addr_zero),
                  ETH_ADDR_ARGS(ea), ETH_ADDR_ARGS(eth_addr_zero),
                  ETH_ADDR_ARGS(ea));
    if (!n_ipv6_addrs) {
        ds_put_cstr(match, "))");
        return;
    }

    char ip6_str[INET6_ADDRSTRLEN + 1];
    struct in6_addr lla;
    in6_generate_lla(ea, &lla);
    memset(ip6_str, 0, sizeof(ip6_str));
    ipv6_string_mapped(ip6_str, &lla);
    ds_put_format(match, " && (nd.target == %s", ip6_str);

    for(int i = 0; i < n_ipv6_addrs; i++) {
        memset(ip6_str, 0, sizeof(ip6_str));
        ipv6_string_mapped(ip6_str, &ipv6_addrs[i].addr);
        ds_put_format(match, " || nd.target == %s", ip6_str);
    }

    ds_put_format(match, ")))");
}

static void
build_port_security_ipv6_flow(
    enum ovn_pipeline pipeline, struct ds *match, struct eth_addr ea,
    struct ipv6_netaddr *ipv6_addrs, int n_ipv6_addrs)
{
    char ip6_str[INET6_ADDRSTRLEN + 1];

    ds_put_format(match, " && %s == {",
                  pipeline == P_IN ? "ip6.src" : "ip6.dst");

    /* Allow link-local address. */
    struct in6_addr lla;
    in6_generate_lla(ea, &lla);
    ipv6_string_mapped(ip6_str, &lla);
    ds_put_format(match, "%s, ", ip6_str);

    /* Allow ip6.dst=ff00::/8 for multicast packets */
    if (pipeline == P_OUT) {
        ds_put_cstr(match, "ff00::/8, ");
    }
    for(int i = 0; i < n_ipv6_addrs; i++) {
        ipv6_string_mapped(ip6_str, &ipv6_addrs[i].addr);
        ds_put_format(match, "%s, ", ip6_str);
    }
    /* Replace ", " by "}". */
    ds_chomp(match, ' ');
    ds_chomp(match, ',');
    ds_put_cstr(match, "}");
}

/**
 * Build port security constraints on ARP and IPv6 ND fields
 * and add logical flows to S_SWITCH_IN_PORT_SEC_ND stage.
 *
 * For each port security of the logical port, following
 * logical flows are added
 *   - If the port security has no IP (both IPv4 and IPv6) or
 *     if it has IPv4 address(es)
 *      - Priority 90 flow to allow ARP packets for known MAC addresses
 *        in the eth.src and arp.spa fields. If the port security
 *        has IPv4 addresses, allow known IPv4 addresses in the arp.tpa field.
 *
 *   - If the port security has no IP (both IPv4 and IPv6) or
 *     if it has IPv6 address(es)
 *     - Priority 90 flow to allow IPv6 ND packets for known MAC addresses
 *       in the eth.src and nd.sll/nd.tll fields. If the port security
 *       has IPv6 addresses, allow known IPv6 addresses in the nd.target field
 *       for IPv6 Neighbor Advertisement packet.
 *
 *   - Priority 80 flow to drop ARP and IPv6 ND packets.
 */
static void
build_port_security_nd(struct ovn_port *op, struct hmap *lflows)
{
    for (size_t i = 0; i < op->nbs->n_port_security; i++) {
        struct lport_addresses ps;
        if (!extract_lsp_addresses(op->nbs->port_security[i], &ps, true)) {
            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
            VLOG_INFO_RL(&rl, "invalid syntax '%s' in port security. No MAC"
                         " address found", op->nbs->port_security[i]);
            continue;
        }

        bool no_ip = !(ps.n_ipv4_addrs || ps.n_ipv6_addrs);
        struct ds match = DS_EMPTY_INITIALIZER;

        if (ps.n_ipv4_addrs || no_ip) {
            ds_put_format(
                &match, "inport == %s && eth.src == "ETH_ADDR_FMT" && arp.sha == "
                ETH_ADDR_FMT, op->json_key, ETH_ADDR_ARGS(ps.ea),
                ETH_ADDR_ARGS(ps.ea));

            if (ps.n_ipv4_addrs) {
                ds_put_cstr(&match, " && (");
                for (size_t i = 0; i < ps.n_ipv4_addrs; i++) {
                    ds_put_cstr(&match, "arp.spa == ");
                    ovs_be32 mask = be32_prefix_mask(ps.ipv4_addrs[i].plen);
                    /* When the netmask is applied, if the host portion is
                     * non-zero, the host can only use the specified
                     * address in the arp.spa.  If zero, the host is allowed
                     * to use any address in the subnet. */
                    if (ps.ipv4_addrs[i].addr & ~mask) {
                        ds_put_format(&match, IP_FMT,
                                      IP_ARGS(ps.ipv4_addrs[i].addr));
                    } else {
                       ip_format_masked(ps.ipv4_addrs[i].addr & mask, mask,
                                        &match);
                    }
                    ds_put_cstr(&match, " || ");
                }
                ds_chomp(&match, ' ');
                ds_chomp(&match, '|');
                ds_chomp(&match, '|');
                ds_put_cstr(&match, ")");
            }
            ovn_lflow_add(lflows, op->od, S_SWITCH_IN_PORT_SEC_ND, 90,
                          ds_cstr(&match), "next;");
            ds_destroy(&match);
        }

        if (ps.n_ipv6_addrs || no_ip) {
            ds_init(&match);
            ds_put_format(&match, "inport == %s && eth.src == "ETH_ADDR_FMT,
                          op->json_key, ETH_ADDR_ARGS(ps.ea));
            build_port_security_ipv6_nd_flow(&match, ps.ea, ps.ipv6_addrs,
                                             ps.n_ipv6_addrs);
            ovn_lflow_add(lflows, op->od, S_SWITCH_IN_PORT_SEC_ND, 90,
                          ds_cstr(&match), "next;");
            ds_destroy(&match);
        }
        free(ps.ipv4_addrs);
        free(ps.ipv6_addrs);
    }

    char *match = xasprintf("inport == %s && (arp || nd)", op->json_key);
    ovn_lflow_add(lflows, op->od, S_SWITCH_IN_PORT_SEC_ND, 80,
                  match, "drop;");
    free(match);
}

/**
 * Build port security constraints on IPv4 and IPv6 src and dst fields
 * and add logical flows to S_SWITCH_(IN/OUT)_PORT_SEC_IP stage.
 *
 * For each port security of the logical port, following
 * logical flows are added
 *   - If the port security has IPv4 addresses,
 *     - Priority 90 flow to allow IPv4 packets for known IPv4 addresses
 *
 *   - If the port security has IPv6 addresses,
 *     - Priority 90 flow to allow IPv6 packets for known IPv6 addresses
 *
 *   - If the port security has IPv4 addresses or IPv6 addresses or both
 *     - Priority 80 flow to drop all IPv4 and IPv6 traffic
 */
static void
build_port_security_ip(enum ovn_pipeline pipeline, struct ovn_port *op,
                       struct hmap *lflows)
{
    char *port_direction;
    enum ovn_stage stage;
    if (pipeline == P_IN) {
        port_direction = "inport";
        stage = S_SWITCH_IN_PORT_SEC_IP;
    } else {
        port_direction = "outport";
        stage = S_SWITCH_OUT_PORT_SEC_IP;
    }

    for (size_t i = 0; i < op->nbs->n_port_security; i++) {
        struct lport_addresses ps;
        if (!extract_lsp_addresses(op->nbs->port_security[i], &ps, true)) {
            continue;
        }

        if (!(ps.n_ipv4_addrs || ps.n_ipv6_addrs)) {
            continue;
        }

        if (ps.n_ipv4_addrs) {
            struct ds match = DS_EMPTY_INITIALIZER;
            if (pipeline == P_IN) {
                /* Permit use of the unspecified address for DHCP discovery */
                struct ds dhcp_match = DS_EMPTY_INITIALIZER;
                ds_put_format(&dhcp_match, "inport == %s"
                              " && eth.src == "ETH_ADDR_FMT
                              " && ip4.src == 0.0.0.0"
                              " && ip4.dst == 255.255.255.255"
                              " && udp.src == 68 && udp.dst == 67", op->json_key,
                              ETH_ADDR_ARGS(ps.ea));
                ovn_lflow_add(lflows, op->od, stage, 90,
                              ds_cstr(&dhcp_match), "next;");
                ds_destroy(&dhcp_match);
                ds_put_format(&match, "inport == %s && eth.src == "ETH_ADDR_FMT
                              " && ip4.src == {", op->json_key,
                              ETH_ADDR_ARGS(ps.ea));
            } else {
                ds_put_format(&match, "outport == %s && eth.dst == "ETH_ADDR_FMT
                              " && ip4.dst == {255.255.255.255, 224.0.0.0/4, ",
                              op->json_key, ETH_ADDR_ARGS(ps.ea));
            }

            for (int i = 0; i < ps.n_ipv4_addrs; i++) {
                ovs_be32 mask = be32_prefix_mask(ps.ipv4_addrs[i].plen);
                /* When the netmask is applied, if the host portion is
                 * non-zero, the host can only use the specified
                 * address.  If zero, the host is allowed to use any
                 * address in the subnet.
                 * */
                if (ps.ipv4_addrs[i].addr & ~mask) {
                    ds_put_format(&match, IP_FMT,
                                  IP_ARGS(ps.ipv4_addrs[i].addr));
                    if (pipeline == P_OUT && ps.ipv4_addrs[i].plen != 32) {
                         /* Host is also allowed to receive packets to the
                         * broadcast address in the specified subnet.
                         */
                        ds_put_format(&match, ", "IP_FMT,
                                      IP_ARGS(ps.ipv4_addrs[i].addr | ~mask));
                    }
                } else {
                    /* host portion is zero */
                    ip_format_masked(ps.ipv4_addrs[i].addr & mask, mask,
                                     &match);
                }
                ds_put_cstr(&match, ", ");
            }

            /* Replace ", " by "}". */
            ds_chomp(&match, ' ');
            ds_chomp(&match, ',');
            ds_put_cstr(&match, "}");
            ovn_lflow_add(lflows, op->od, stage, 90, ds_cstr(&match), "next;");
            ds_destroy(&match);
            free(ps.ipv4_addrs);
        }

        if (ps.n_ipv6_addrs) {
            struct ds match = DS_EMPTY_INITIALIZER;
            if (pipeline == P_IN) {
                /* Permit use of unspecified address for duplicate address
                 * detection */
                struct ds dad_match = DS_EMPTY_INITIALIZER;
                ds_put_format(&dad_match, "inport == %s"
                              " && eth.src == "ETH_ADDR_FMT
                              " && ip6.src == ::"
                              " && ip6.dst == ff02::/16"
                              " && icmp6.type == {131, 135, 143}", op->json_key,
                              ETH_ADDR_ARGS(ps.ea));
                ovn_lflow_add(lflows, op->od, stage, 90,
                              ds_cstr(&dad_match), "next;");
                ds_destroy(&dad_match);
            }
            ds_put_format(&match, "%s == %s && %s == "ETH_ADDR_FMT"",
                          port_direction, op->json_key,
                          pipeline == P_IN ? "eth.src" : "eth.dst",
                          ETH_ADDR_ARGS(ps.ea));
            build_port_security_ipv6_flow(pipeline, &match, ps.ea,
                                          ps.ipv6_addrs, ps.n_ipv6_addrs);
            ovn_lflow_add(lflows, op->od, stage, 90,
                          ds_cstr(&match), "next;");
            ds_destroy(&match);
            free(ps.ipv6_addrs);
        }

        char *match = xasprintf(
            "%s == %s && %s == "ETH_ADDR_FMT" && ip", port_direction,
            op->json_key, pipeline == P_IN ? "eth.src" : "eth.dst",
            ETH_ADDR_ARGS(ps.ea));
        ovn_lflow_add(lflows, op->od, stage, 80, match, "drop;");
        free(match);
    }
}

static bool
lsp_is_enabled(const struct nbrec_logical_switch_port *lsp)
{
    return !lsp->enabled || *lsp->enabled;
}

static bool
lsp_is_up(const struct nbrec_logical_switch_port *lsp)
{
    return !lsp->up || *lsp->up;
}

static bool
has_stateful_acl(struct ovn_datapath *od)
{
    for (size_t i = 0; i < od->nbs->n_acls; i++) {
        struct nbrec_acl *acl = od->nbs->acls[i];
        if (!strcmp(acl->action, "allow-related")) {
            return true;
        }
    }

    return false;
}

static void
build_pre_acls(struct ovn_datapath *od, struct hmap *lflows,
               struct hmap *ports)
{
    bool has_stateful = has_stateful_acl(od);
    struct ovn_port *op;

    /* Ingress and Egress Pre-ACL Table (Priority 0): Packets are
     * allowed by default. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_ACL, 0, "1", "next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_ACL, 0, "1", "next;");

    /* If there are any stateful ACL rules in this dapapath, we must
     * send all IP packets through the conntrack action, which handles
     * defragmentation, in order to match L4 headers. */
    if (has_stateful) {
        HMAP_FOR_EACH (op, key_node, ports) {
            if (op->od == od && !strcmp(op->nbs->type, "router")) {
                /* Can't use ct() for router ports. Consider the
                 * following configuration: lp1(10.0.0.2) on
                 * hostA--ls1--lr0--ls2--lp2(10.0.1.2) on hostB, For a
                 * ping from lp1 to lp2, First, the response will go
                 * through ct() with a zone for lp2 in the ls2 ingress
                 * pipeline on hostB.  That ct zone knows about this
                 * connection. Next, it goes through ct() with the zone
                 * for the router port in the egress pipeline of ls2 on
                 * hostB.  This zone does not know about the connection,
                 * as the icmp request went through the logical router
                 * on hostA, not hostB. This would only work with
                 * distributed conntrack state across all chassis. */
                struct ds match_in = DS_EMPTY_INITIALIZER;
                struct ds match_out = DS_EMPTY_INITIALIZER;

                ds_put_format(&match_in, "ip && inport == %s", op->json_key);
                ds_put_format(&match_out, "ip && outport == %s", op->json_key);
                ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_ACL, 110,
                              ds_cstr(&match_in), "next;");
                ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_ACL, 110,
                              ds_cstr(&match_out), "next;");

                ds_destroy(&match_in);
                ds_destroy(&match_out);
            }
        }

        /* Ingress and Egress Pre-ACL Table (Priority 100).
         *
         * Regardless of whether the ACL is "from-lport" or "to-lport",
         * we need rules in both the ingress and egress table, because
         * the return traffic needs to be followed.
         *
         * 'reg0[0]' is set to let the pre-stateful table send
         * it to conntrack for tracking. */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_ACL, 100, "ip",
                      "reg0[0] = 1; next;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_ACL, 100, "ip",
                      "reg0[0] = 1; next;");
    }
}

static void
build_pre_lb(struct ovn_datapath *od, struct hmap *lflows)
{
    /* Allow all packets to go to next tables by default. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_LB, 0, "1", "next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_LB, 0, "1", "next;");

    const char *ip_address;
    struct sset all_ips = SSET_INITIALIZER(&all_ips);
    if (od->nbs->load_balancer) {
        struct nbrec_load_balancer *lb = od->nbs->load_balancer;
        struct smap *vips = &lb->vips;
        struct smap_node *node;
        bool vip_configured = false;

        SMAP_FOR_EACH (node, vips) {
            char *start, *next;
            vip_configured = true;

            /* node->key contains IP:port or just IP. */
            next = start = xstrdup(node->key);
            ip_address = strsep(&next, ":");
            if (!ip_address || !ip_address[0]) {
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad ip address for load balancer key %s",
                             node->key);
                free(start);
                continue;
            }

            ovs_be32 ip, mask;
            char *error = ip_parse_masked(ip_address, &ip, &mask);
            if (error || mask != OVS_BE32_MAX) {
                static struct vlog_rate_limit rl
                        = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad ip address for load balancer key %s",
                             node->key);
                free(start);
                free(error);
                continue;
            }

            if (!sset_contains(&all_ips, ip_address)) {
                sset_add(&all_ips, ip_address);
            }

            /* Ignore L4 port information in the key because fragmented packets
             * may not have L4 information.  The pre-stateful table will send
             * the packet through ct() action to de-fragment. In stateful
             * table, we will eventually look at L4 information. */

            free(start);
        }

        SSET_FOR_EACH(ip_address, &all_ips) {
            char *match = xasprintf("ip && ip4.dst == %s", ip_address);
            ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_LB,
                          100, match, "reg0[0] = 1; next;");
            free(match);
        }

        sset_destroy(&all_ips);

        if (vip_configured) {
            ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_LB,
                          100, "ip", "reg0[0] = 1; next;");
        }
    }
}

static void
build_pre_stateful(struct ovn_datapath *od, struct hmap *lflows)
{
    /* Ingress and Egress pre-stateful Table (Priority 0): Packets are
     * allowed by default. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_STATEFUL, 0, "1", "next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_STATEFUL, 0, "1", "next;");

    /* If reg0[0] is set as 1, then the packets should be sent to conntrack for
     * tracking. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_STATEFUL, 100, "reg0[0] == 1",
                  "ct_next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_STATEFUL, 100, "reg0[0] == 1",
                  "ct_next;");
}

static void
build_acls(struct ovn_datapath *od, struct hmap *lflows)
{
    bool has_stateful = has_stateful_acl(od);

    /* Ingress and Egress ACL Table (Priority 0): Packets are allowed by
     * default.  A related rule at priority 1 is added below if there
     * are any stateful ACLs in this datapath. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_ACL, 0, "1", "next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_ACL, 0, "1", "next;");

    if (has_stateful) {
        /* Ingress and Egress ACL Table (Priority 1).
         *
         * By default, traffic is allowed.  This is partially handled by
         * the Priority 0 ACL flows added earlier, but we also need to
         * commit IP flows.  This is because, while the initiater's
         * direction may not have any stateful rules, the server's may
         * and then its return traffic would not have an associated
         * conntrack entry and would return "+invalid". */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_ACL, 1, "ip",
                      "reg0[1] = 1; next;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_ACL, 1, "ip",
                      "reg0[1] = 1; next;");

        /* Ingress and Egress ACL Table (Priority 65535).
         *
         * Always drop traffic that's in an invalid state.  This is
         * enforced at a higher priority than ACLs can be defined. */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_ACL, UINT16_MAX,
                      "ct.inv", "drop;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_ACL, UINT16_MAX,
                      "ct.inv", "drop;");

        /* Ingress and Egress ACL Table (Priority 65535).
         *
         * Always allow traffic that is established to a committed
         * conntrack entry.  This is enforced at a higher priority than
         * ACLs can be defined. */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_ACL, UINT16_MAX,
                      "ct.est && !ct.rel && !ct.new && !ct.inv",
                      "next;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_ACL, UINT16_MAX,
                      "ct.est && !ct.rel && !ct.new && !ct.inv",
                      "next;");

        /* Ingress and Egress ACL Table (Priority 65535).
         *
         * Always allow traffic that is related to an existing conntrack
         * entry.  This is enforced at a higher priority than ACLs can
         * be defined.
         *
         * NOTE: This does not support related data sessions (eg,
         * a dynamically negotiated FTP data channel), but will allow
         * related traffic such as an ICMP Port Unreachable through
         * that's generated from a non-listening UDP port.  */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_ACL, UINT16_MAX,
                      "!ct.est && ct.rel && !ct.new && !ct.inv",
                      "next;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_ACL, UINT16_MAX,
                      "!ct.est && ct.rel && !ct.new && !ct.inv",
                      "next;");
    }

    /* Ingress or Egress ACL Table (Various priorities). */
    for (size_t i = 0; i < od->nbs->n_acls; i++) {
        struct nbrec_acl *acl = od->nbs->acls[i];
        bool ingress = !strcmp(acl->direction, "from-lport") ? true :false;
        enum ovn_stage stage = ingress ? S_SWITCH_IN_ACL : S_SWITCH_OUT_ACL;

        if (!strcmp(acl->action, "allow")) {
            /* If there are any stateful flows, we must even commit "allow"
             * actions.  This is because, while the initiater's
             * direction may not have any stateful rules, the server's
             * may and then its return traffic would not have an
             * associated conntrack entry and would return "+invalid". */
            const char *actions = has_stateful
                                    ? "reg0[1] = 1; next;" : "next;";
            ovn_lflow_add(lflows, od, stage,
                          acl->priority + OVN_ACL_PRI_OFFSET,
                          acl->match, actions);
        } else if (!strcmp(acl->action, "allow-related")) {
            struct ds match = DS_EMPTY_INITIALIZER;

            /* Commit the connection tracking entry, which allows all
             * other traffic related to this entry to flow due to the
             * 65535 priority flow defined earlier. */
            ds_put_format(&match, "ct.new && (%s)", acl->match);
            ovn_lflow_add(lflows, od, stage,
                          acl->priority + OVN_ACL_PRI_OFFSET,
                          ds_cstr(&match), "reg0[1] = 1; next;");

            ds_destroy(&match);
        } else if (!strcmp(acl->action, "drop")) {
            ovn_lflow_add(lflows, od, stage,
                          acl->priority + OVN_ACL_PRI_OFFSET,
                          acl->match, "drop;");
        } else if (!strcmp(acl->action, "reject")) {
            /* xxx Need to support "reject". */
            VLOG_INFO("reject is not a supported action");
            ovn_lflow_add(lflows, od, stage,
                          acl->priority + OVN_ACL_PRI_OFFSET,
                          acl->match, "drop;");
        }
    }
}

static void
build_lb(struct ovn_datapath *od, struct hmap *lflows)
{
    /* Ingress and Egress LB Table (Priority 0): Packets are allowed by
     * default.  */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_LB, 0, "1", "next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_LB, 0, "1", "next;");

    if (od->nbs->load_balancer) {
        /* Ingress and Egress LB Table (Priority 65535).
         *
         * Send established traffic through conntrack for just NAT. */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_LB, UINT16_MAX,
                      "ct.est && !ct.rel && !ct.new && !ct.inv",
                      "reg0[2] = 1; next;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_LB, UINT16_MAX,
                      "ct.est && !ct.rel && !ct.new && !ct.inv",
                      "reg0[2] = 1; next;");
    }
}

static void
build_stateful(struct ovn_datapath *od, struct hmap *lflows)
{
    /* Ingress and Egress stateful Table (Priority 0): Packets are
     * allowed by default. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_STATEFUL, 0, "1", "next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_STATEFUL, 0, "1", "next;");

    /* If reg0[1] is set as 1, then the packets should be committed to
     * conntrack. */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_STATEFUL, 100, "reg0[1] == 1",
                  "ct_commit; next;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_STATEFUL, 100, "reg0[1] == 1",
                  "ct_commit; next;");

    /* If reg0[2] is set as 1, then packets should just be sent through
     * nat (without committing). */
    ovn_lflow_add(lflows, od, S_SWITCH_IN_STATEFUL, 100, "reg0[2] == 1",
                  "ct_lb;");
    ovn_lflow_add(lflows, od, S_SWITCH_OUT_STATEFUL, 100, "reg0[2] == 1",
                  "ct_lb;");

    if (od->nbs->load_balancer) {
        struct nbrec_load_balancer *lb = od->nbs->load_balancer;
        struct smap *vips = &lb->vips;
        struct smap_node *node;

        SMAP_FOR_EACH (node, vips) {
            struct ds match = DS_EMPTY_INITIALIZER;
            int32_t port = 0;
            char *start, *next;

            /* node->key contains IP:port or just IP. */
            next = start = xstrdup(node->key);
            char *ip_address = strsep(&next, ":");
            if (!ip_address || !ip_address[0]) {
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad ip address for load balancer key %s",
                             node->key);
                free(start);
                continue;
            }

            ovs_be32 ip, mask;
            char *error = ip_parse_masked(ip_address, &ip, &mask);
            if (error || mask != OVS_BE32_MAX) {
                static struct vlog_rate_limit rl
                        = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad ip address for load balancer key %s",
                             node->key);
                free(start);
                free(error);
                continue;
            }

            if (next && next[0]) {
                if (!str_to_int(next, 0, &port) || port < 0 || port > 65535) {
                    static struct vlog_rate_limit rl
                          = VLOG_RATE_LIMIT_INIT(5, 1);
                    VLOG_WARN_RL(&rl, "bad ip port for load balancer key %s",
                                 node->key);
                    free(start);
                    continue;
                }
            }

            /* New connections in Ingress table. */
            char *action = xasprintf("ct_lb(\"%s\");", node->value);
            if (port) {
                if (lb->protocol && !strcmp(lb->protocol, "udp")) {
                    ds_put_format(&match, "ip && ip4.dst == %s"
                          "&& udp && udp.dst == %d", ip_address, port);
                } else {
                    ds_put_format(&match, "ip && ip4.dst == %s"
                          "&& tcp && tcp.dst == %d", ip_address, port);
                }
                ovn_lflow_add(lflows, od, S_SWITCH_IN_LB,
                              120, ds_cstr(&match), action);
            } else {
                ds_put_format(&match, "ip && ip4.dst == %s", ip_address);
                ovn_lflow_add(lflows, od, S_SWITCH_IN_LB,
                              110, ds_cstr(&match), action);
            }

            ds_destroy(&match);
            free(action);
            free(start);
       }
    }
}

static void
build_lswitch_flows(struct hmap *datapaths, struct hmap *ports,
                    struct hmap *lflows, struct hmap *mcgroups)
{
    /* This flow table structure is documented in ovn-northd(8), so please
     * update ovn-northd.8.xml if you change anything. */

    /* Build pre-ACL and ACL tables for both ingress and egress.
     * Ingress tables 3 and 4.  Egress tables 0 and 1. */
    struct ovn_datapath *od;
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        build_pre_acls(od, lflows, ports);
        build_pre_lb(od, lflows);
        build_pre_stateful(od, lflows);
        build_acls(od, lflows);
        build_lb(od, lflows);
        build_stateful(od, lflows);
    }

    /* Logical switch ingress table 0: Admission control framework (priority
     * 100). */
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        /* Logical VLANs not supported. */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_PORT_SEC_L2, 100, "vlan.present",
                      "drop;");

        /* Broadcast/multicast source address is invalid. */
        ovn_lflow_add(lflows, od, S_SWITCH_IN_PORT_SEC_L2, 100, "eth.src[40]",
                      "drop;");

        /* Port security flows have priority 50 (see below) and will continue
         * to the next table if packet source is acceptable. */
    }

    /* Logical switch ingress table 0: Ingress port security - L2
     *  (priority 50).
     *  Ingress table 1: Ingress port security - IP (priority 90 and 80)
     *  Ingress table 2: Ingress port security - ND (priority 90 and 80)
     */
    struct ovn_port *op;
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbs) {
            continue;
        }

        if (!lsp_is_enabled(op->nbs)) {
            /* Drop packets from disabled logical ports (since logical flow
             * tables are default-drop). */
            continue;
        }

        struct ds match = DS_EMPTY_INITIALIZER;
        ds_put_format(&match, "inport == %s", op->json_key);
        build_port_security_l2(
            "eth.src", op->nbs->port_security, op->nbs->n_port_security,
            &match);
        ovn_lflow_add(lflows, op->od, S_SWITCH_IN_PORT_SEC_L2, 50,
                      ds_cstr(&match), "next;");
        ds_destroy(&match);

        if (op->nbs->n_port_security) {
            build_port_security_ip(P_IN, op, lflows);
            build_port_security_nd(op, lflows);
        }
    }

    /* Ingress table 1 and 2: Port security - IP and ND, by default goto next.
     * (priority 0)*/
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        ovn_lflow_add(lflows, od, S_SWITCH_IN_PORT_SEC_ND, 0, "1", "next;");
        ovn_lflow_add(lflows, od, S_SWITCH_IN_PORT_SEC_IP, 0, "1", "next;");
    }

    /* Ingress table 3: ARP responder, skip requests coming from localnet ports.
     * (priority 100). */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbs) {
            continue;
        }

        if (!strcmp(op->nbs->type, "localnet")) {
            char *match = xasprintf("inport == %s", op->json_key);
            ovn_lflow_add(lflows, op->od, S_SWITCH_IN_ARP_RSP, 100,
                          match, "next;");
            free(match);
        }
    }

    /* Ingress table 5: ARP responder, reply for known IPs.
     * (priority 50). */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbs) {
            continue;
        }

        /*
         * Add ARP reply flows if either the
         *  - port is up or
         *  - port type is router
         */
        if (!lsp_is_up(op->nbs) && strcmp(op->nbs->type, "router")) {
            continue;
        }

        for (size_t i = 0; i < op->nbs->n_addresses; i++) {
            struct lport_addresses laddrs;
            if (!extract_lsp_addresses(op->nbs->addresses[i], &laddrs,
                                       false)) {
                continue;
            }
            for (size_t j = 0; j < laddrs.n_ipv4_addrs; j++) {
                char *match = xasprintf(
                    "arp.tpa == "IP_FMT" && arp.op == 1",
                    IP_ARGS(laddrs.ipv4_addrs[j].addr));
                char *actions = xasprintf(
                    "eth.dst = eth.src; "
                    "eth.src = "ETH_ADDR_FMT"; "
                    "arp.op = 2; /* ARP reply */ "
                    "arp.tha = arp.sha; "
                    "arp.sha = "ETH_ADDR_FMT"; "
                    "arp.tpa = arp.spa; "
                    "arp.spa = "IP_FMT"; "
                    "outport = inport; "
                    "inport = \"\"; /* Allow sending out inport. */ "
                    "output;",
                    ETH_ADDR_ARGS(laddrs.ea),
                    ETH_ADDR_ARGS(laddrs.ea),
                    IP_ARGS(laddrs.ipv4_addrs[j].addr));
                ovn_lflow_add(lflows, op->od, S_SWITCH_IN_ARP_RSP, 50,
                              match, actions);
                free(match);
                free(actions);
            }

            free(laddrs.ipv4_addrs);
        }
    }

    /* Ingress table 5: ARP responder, by default goto next.
     * (priority 0)*/
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        ovn_lflow_add(lflows, od, S_SWITCH_IN_ARP_RSP, 0, "1", "next;");
    }

    /* Ingress table 6: Destination lookup, broadcast and multicast handling
     * (priority 100). */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbs) {
            continue;
        }

        if (lsp_is_enabled(op->nbs)) {
            ovn_multicast_add(mcgroups, &mc_flood, op);
        }
    }
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        ovn_lflow_add(lflows, od, S_SWITCH_IN_L2_LKUP, 100, "eth.mcast",
                      "outport = \""MC_FLOOD"\"; output;");
    }

    /* Ingress table 6: Destination lookup, unicast handling (priority 50), */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbs) {
            continue;
        }

        for (size_t i = 0; i < op->nbs->n_addresses; i++) {
            struct eth_addr mac;

            if (eth_addr_from_string(op->nbs->addresses[i], &mac)) {
                struct ds match, actions;

                ds_init(&match);
                ds_put_format(&match, "eth.dst == "ETH_ADDR_FMT,
                              ETH_ADDR_ARGS(mac));

                ds_init(&actions);
                ds_put_format(&actions, "outport = %s; output;", op->json_key);
                ovn_lflow_add(lflows, op->od, S_SWITCH_IN_L2_LKUP, 50,
                              ds_cstr(&match), ds_cstr(&actions));
                ds_destroy(&actions);
                ds_destroy(&match);
            } else if (!strcmp(op->nbs->addresses[i], "unknown")) {
                if (lsp_is_enabled(op->nbs)) {
                    ovn_multicast_add(mcgroups, &mc_unknown, op);
                    op->od->has_unknown = true;
                }
            } else {
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);

                VLOG_INFO_RL(&rl,
                             "%s: invalid syntax '%s' in addresses column",
                             op->nbs->name, op->nbs->addresses[i]);
            }
        }
    }

    /* Ingress table 6: Destination lookup for unknown MACs (priority 0). */
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        if (od->has_unknown) {
            ovn_lflow_add(lflows, od, S_SWITCH_IN_L2_LKUP, 0, "1",
                          "outport = \""MC_UNKNOWN"\"; output;");
        }
    }

    /* Egress table 2: Egress port security - IP (priority 0)
     * port security L2 - multicast/broadcast (priority
     * 100). */
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbs) {
            continue;
        }

        ovn_lflow_add(lflows, od, S_SWITCH_OUT_PORT_SEC_IP, 0, "1", "next;");
        ovn_lflow_add(lflows, od, S_SWITCH_OUT_PORT_SEC_L2, 100, "eth.mcast",
                      "output;");
    }

    /* Egress table 2: Egress port security - IP (priorities 90 and 80)
     * if port security enabled.
     *
     * Egress table 3: Egress port security - L2 (priorities 50 and 150).
     *
     * Priority 50 rules implement port security for enabled logical port.
     *
     * Priority 150 rules drop packets to disabled logical ports, so that they
     * don't even receive multicast or broadcast packets. */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbs) {
            continue;
        }

        struct ds match = DS_EMPTY_INITIALIZER;
        ds_put_format(&match, "outport == %s", op->json_key);
        if (lsp_is_enabled(op->nbs)) {
            build_port_security_l2("eth.dst", op->nbs->port_security,
                                   op->nbs->n_port_security, &match);
            ovn_lflow_add(lflows, op->od, S_SWITCH_OUT_PORT_SEC_L2, 50,
                          ds_cstr(&match), "output;");
        } else {
            ovn_lflow_add(lflows, op->od, S_SWITCH_OUT_PORT_SEC_L2, 150,
                          ds_cstr(&match), "drop;");
        }

        ds_destroy(&match);

        if (op->nbs->n_port_security) {
            build_port_security_ip(P_OUT, op, lflows);
        }
    }
}

static bool
lrport_is_enabled(const struct nbrec_logical_router_port *lrport)
{
    return !lrport->enabled || *lrport->enabled;
}

static void
add_route(struct hmap *lflows, const struct ovn_port *op,
          ovs_be32 network, ovs_be32 mask, ovs_be32 gateway)
{
    char *match = xasprintf("ip4.dst == "IP_FMT"/"IP_FMT,
                            IP_ARGS(network), IP_ARGS(mask));

    struct ds actions = DS_EMPTY_INITIALIZER;
    ds_put_cstr(&actions, "ip.ttl--; reg0 = ");
    if (gateway) {
        ds_put_format(&actions, IP_FMT, IP_ARGS(gateway));
    } else {
        ds_put_cstr(&actions, "ip4.dst");
    }
    ds_put_format(&actions,
                  "; "
                  "reg1 = "IP_FMT"; "
                  "eth.src = "ETH_ADDR_FMT"; "
                  "outport = %s; "
                  "next;",
                  IP_ARGS(op->ip), ETH_ADDR_ARGS(op->mac), op->json_key);

    /* The priority here is calculated to implement longest-prefix-match
     * routing. */
    ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_ROUTING,
                  count_1bits(ntohl(mask)), match, ds_cstr(&actions));
    ds_destroy(&actions);
    free(match);
}

static void
build_static_route_flow(struct hmap *lflows, struct ovn_datapath *od,
                        struct hmap *ports,
                        const struct nbrec_logical_router_static_route *route)
{
    ovs_be32 prefix, next_hop, mask;

    /* Verify that next hop is an IP address with 32 bits mask. */
    char *error = ip_parse_masked(route->nexthop, &next_hop, &mask);
    if (error || mask != OVS_BE32_MAX) {
        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
        VLOG_WARN_RL(&rl, "bad next hop ip address %s", route->nexthop);
        free(error);
        return;
    }

    /* Verify that ip prefix is a valid CIDR address. */
    error = ip_parse_masked(route->ip_prefix, &prefix, &mask);
    if (error || !ip_is_cidr(mask)) {
        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
        VLOG_WARN_RL(&rl, "bad 'network' in static routes %s",
                     route->ip_prefix);
        free(error);
        return;
    }

    /* Find the outgoing port. */
    struct ovn_port *out_port = NULL;
    if (route->output_port) {
        out_port = ovn_port_find(ports, route->output_port);
        if (!out_port) {
            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
            VLOG_WARN_RL(&rl, "Bad out port %s for static route %s",
                         route->output_port, route->ip_prefix);
            return;
        }
    } else {
        /* output_port is not specified, find the
         * router port matching the next hop. */
        int i;
        for (i = 0; i < od->nbr->n_ports; i++) {
            struct nbrec_logical_router_port *lrp = od->nbr->ports[i];
            out_port = ovn_port_find(ports, lrp->name);
            if (!out_port) {
                /* This should not happen. */
                continue;
            }

            if (out_port->network
                && !((out_port->network ^ next_hop) & out_port->mask)) {
                /* There should be only 1 interface that matches the next hop.
                 * Otherwise, it's a configuration error, because subnets of
                 * router's interfaces should NOT overlap. */
                break;
            }
        }
        if (i == od->nbr->n_ports) {
            /* There is no matched out port. */
            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
            VLOG_WARN_RL(&rl, "No path for static route %s; next hop %s",
                         route->ip_prefix, route->nexthop);
            return;
        }
    }

    add_route(lflows, out_port, prefix, mask, next_hop);
}

static void
build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
                    struct hmap *lflows)
{
    /* This flow table structure is documented in ovn-northd(8), so please
     * update ovn-northd.8.xml if you change anything. */

    /* Logical router ingress table 0: Admission control framework. */
    struct ovn_datapath *od;
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbr) {
            continue;
        }

        /* Logical VLANs not supported.
         * Broadcast/multicast source address is invalid. */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_ADMISSION, 100,
                      "vlan.present || eth.src[40]", "drop;");
    }

    /* Logical router ingress table 0: match (priority 50). */
    struct ovn_port *op;
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbr) {
            continue;
        }

        if (!lrport_is_enabled(op->nbr)) {
            /* Drop packets from disabled logical ports (since logical flow
             * tables are default-drop). */
            continue;
        }

        char *match = xasprintf(
            "(eth.mcast || eth.dst == "ETH_ADDR_FMT") && inport == %s",
            ETH_ADDR_ARGS(op->mac), op->json_key);
        ovn_lflow_add(lflows, op->od, S_ROUTER_IN_ADMISSION, 50,
                      match, "next;");
        free(match);
    }

    /* Logical router ingress table 1: IP Input. */
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbr) {
            continue;
        }

        /* L3 admission control: drop multicast and broadcast source, localhost
         * source or destination, and zero network source or destination
         * (priority 100). */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_INPUT, 100,
                      "ip4.mcast || "
                      "ip4.src == 255.255.255.255 || "
                      "ip4.src == 127.0.0.0/8 || "
                      "ip4.dst == 127.0.0.0/8 || "
                      "ip4.src == 0.0.0.0/8 || "
                      "ip4.dst == 0.0.0.0/8",
                      "drop;");

        /* ARP reply handling.  Use ARP replies to populate the logical
         * router's ARP table. */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_INPUT, 90, "arp.op == 2",
                      "put_arp(inport, arp.spa, arp.sha);");

        /* Drop Ethernet local broadcast.  By definition this traffic should
         * not be forwarded.*/
        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_INPUT, 50,
                      "eth.bcast", "drop;");

        /* Drop IP multicast. */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_INPUT, 50,
                      "ip4.mcast", "drop;");

        /* TTL discard.
         *
         * XXX Need to send ICMP time exceeded if !ip.later_frag. */
        char *match = xasprintf("ip4 && ip.ttl == {0, 1}");
        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_INPUT, 30, match, "drop;");
        free(match);

        /* Pass other traffic not already handled to the next table for
         * routing. */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_INPUT, 0, "1", "next;");
    }

    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbr) {
            continue;
        }

        /* L3 admission control: drop packets that originate from an IP address
         * owned by the router or a broadcast address known to the router
         * (priority 100). */
        char *match = xasprintf("ip4.src == {"IP_FMT", "IP_FMT"}",
                                IP_ARGS(op->ip), IP_ARGS(op->bcast));
        ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 100,
                      match, "drop;");
        free(match);

        /* ICMP echo reply.  These flows reply to ICMP echo requests
         * received for the router's IP address. Since packets only
         * get here as part of the logical router datapath, the inport
         * (i.e. the incoming locally attached net) does not matter.
         * The ip.ttl also does not matter (RFC1812 section 4.2.2.9) */
        match = xasprintf(
            "(ip4.dst == "IP_FMT" || ip4.dst == "IP_FMT") && "
            "icmp4.type == 8 && icmp4.code == 0",
            IP_ARGS(op->ip), IP_ARGS(op->bcast));
        char *actions = xasprintf(
            "ip4.dst = ip4.src; "
            "ip4.src = "IP_FMT"; "
            "ip.ttl = 255; "
            "icmp4.type = 0; "
            "inport = \"\"; /* Allow sending out inport. */ "
            "next; ",
            IP_ARGS(op->ip));
        ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 90,
                      match, actions);
        free(match);
        free(actions);

        /* ARP reply.  These flows reply to ARP requests for the router's own
         * IP address. */
        match = xasprintf(
            "inport == %s && arp.tpa == "IP_FMT" && arp.op == 1",
            op->json_key, IP_ARGS(op->ip));
        actions = xasprintf(
            "eth.dst = eth.src; "
            "eth.src = "ETH_ADDR_FMT"; "
            "arp.op = 2; /* ARP reply */ "
            "arp.tha = arp.sha; "
            "arp.sha = "ETH_ADDR_FMT"; "
            "arp.tpa = arp.spa; "
            "arp.spa = "IP_FMT"; "
            "outport = %s; "
            "inport = \"\"; /* Allow sending out inport. */ "
            "output;",
            ETH_ADDR_ARGS(op->mac),
            ETH_ADDR_ARGS(op->mac),
            IP_ARGS(op->ip),
            op->json_key);
        ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 90,
                      match, actions);
        free(match);
        free(actions);

        /* ARP handling for external IP addresses.
         *
         * DNAT IP addresses are external IP addresses that need ARP
         * handling. */
        for (int i = 0; i < op->od->nbr->n_nat; i++) {
            const struct nbrec_nat *nat;

            nat = op->od->nbr->nat[i];

            if(!strcmp(nat->type, "snat")) {
                continue;
            }

            ovs_be32 ip;
            if (!ip_parse(nat->external_ip, &ip) || !ip) {
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad ip address %s in dnat configuration "
                             "for router %s", nat->external_ip, op->key);
                continue;
            }

            match = xasprintf(
                "inport == %s && arp.tpa == "IP_FMT" && arp.op == 1",
                op->json_key, IP_ARGS(ip));
            actions = xasprintf(
                "eth.dst = eth.src; "
                "eth.src = "ETH_ADDR_FMT"; "
                "arp.op = 2; /* ARP reply */ "
                "arp.tha = arp.sha; "
                "arp.sha = "ETH_ADDR_FMT"; "
                "arp.tpa = arp.spa; "
                "arp.spa = "IP_FMT"; "
                "outport = %s; "
                "inport = \"\"; /* Allow sending out inport. */ "
                "output;",
                ETH_ADDR_ARGS(op->mac),
                ETH_ADDR_ARGS(op->mac),
                IP_ARGS(ip),
                op->json_key);
            ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 90,
                          match, actions);
            free(match);
            free(actions);
        }

        /* Drop IP traffic to this router. */
        match = xasprintf("ip4.dst == "IP_FMT, IP_ARGS(op->ip));
        ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 60,
                      match, "drop;");
        free(match);

        /* When destination IP address is in the same subnet as the
         * router port, the packet may need to be eventually sent
         * back the same port. For cases like that, allow sending
         * out the inport. */
        match = xasprintf("ip4.dst == "IP_FMT"/"IP_FMT,
                          IP_ARGS(op->network), IP_ARGS(op->mask));
        ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 20,
                      match, "inport = \"\"; next;");
        free(match);
    }

    /* NAT in Gateway routers. */
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbr) {
            continue;
        }

        /* Packets are allowed by default. */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_UNSNAT, 0, "1", "next;");
        ovn_lflow_add(lflows, od, S_ROUTER_OUT_SNAT, 0, "1", "next;");
        ovn_lflow_add(lflows, od, S_ROUTER_IN_DNAT, 0, "1", "next;");

        /* NAT rules are only valid on Gateway routers. */
        if (!smap_get(&od->nbr->options, "chassis")) {
            continue;
        }

        for (int i = 0; i < od->nbr->n_nat; i++) {
            const struct nbrec_nat *nat;

            nat = od->nbr->nat[i];

            ovs_be32 ip, mask;

            char *error = ip_parse_masked(nat->external_ip, &ip, &mask);
            if (error || mask != OVS_BE32_MAX) {
                static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
                VLOG_WARN_RL(&rl, "bad external ip %s for nat",
                             nat->external_ip);
                free(error);
                continue;
            }

            /* Check the validity of nat->logical_ip. 'logical_ip' can
             * be a subnet when the type is "snat". */
            error = ip_parse_masked(nat->logical_ip, &ip, &mask);
            if (!strcmp(nat->type, "snat")) {
                if (error) {
                    static struct vlog_rate_limit rl =
                        VLOG_RATE_LIMIT_INIT(5, 1);
                    VLOG_WARN_RL(&rl, "bad ip network or ip %s for snat "
                                 "in router "UUID_FMT"",
                                 nat->logical_ip, UUID_ARGS(&od->key));
                    free(error);
                    continue;
                }
            } else {
                if (error || mask != OVS_BE32_MAX) {
                    static struct vlog_rate_limit rl =
                        VLOG_RATE_LIMIT_INIT(5, 1);
                    VLOG_WARN_RL(&rl, "bad ip %s for dnat in router "
                        ""UUID_FMT"", nat->logical_ip, UUID_ARGS(&od->key));
                    free(error);
                    continue;
                }
            }


            char *match, *actions;

            /* Ingress UNSNAT table: It is for already established connections'
             * reverse traffic. i.e., SNAT has already been done in egress
             * pipeline and now the packet has entered the ingress pipeline as
             * part of a reply. We undo the SNAT here.
             *
             * Undoing SNAT has to happen before DNAT processing.  This is
             * because when the packet was DNATed in ingress pipeline, it did
             * not know about the possibility of eventual additional SNAT in
             * egress pipeline. */
            if (!strcmp(nat->type, "snat")
                || !strcmp(nat->type, "dnat_and_snat")) {
                match = xasprintf("ip && ip4.dst == %s", nat->external_ip);
                ovn_lflow_add(lflows, od, S_ROUTER_IN_UNSNAT, 100,
                              match, "ct_snat; next;");
                free(match);
            }

            /* Ingress DNAT table: Packets enter the pipeline with destination
             * IP address that needs to be DNATted from a external IP address
             * to a logical IP address. */
            if (!strcmp(nat->type, "dnat")
                || !strcmp(nat->type, "dnat_and_snat")) {
                /* Packet when it goes from the initiator to destination.
                 * We need to zero the inport because the router can
                 * send the packet back through the same interface. */
                match = xasprintf("ip && ip4.dst == %s", nat->external_ip);
                actions = xasprintf("inport = \"\"; ct_dnat(%s);",
                                    nat->logical_ip);
                ovn_lflow_add(lflows, od, S_ROUTER_IN_DNAT, 100,
                           match, actions);
                free(match);
                free(actions);
            }

            /* Egress SNAT table: Packets enter the egress pipeline with
             * source ip address that needs to be SNATted to a external ip
             * address. */
            if (!strcmp(nat->type, "snat")
                || !strcmp(nat->type, "dnat_and_snat")) {
                match = xasprintf("ip && ip4.src == %s", nat->logical_ip);
                actions = xasprintf("ct_snat(%s);", nat->external_ip);

                /* The priority here is calculated such that the
                 * nat->logical_ip with the longest mask gets a higher
                 * priority. */
                ovn_lflow_add(lflows, od, S_ROUTER_OUT_SNAT,
                              count_1bits(ntohl(mask)) + 1, match, actions);
                free(match);
                free(actions);
            }
        }

        /* Re-circulate every packet through the DNAT zone.
        * This helps with two things.
        *
        * 1. Any packet that needs to be unDNATed in the reverse
        * direction gets unDNATed. Ideally this could be done in
        * the egress pipeline. But since the gateway router
        * does not have any feature that depends on the source
        * ip address being external IP address for IP routing,
        * we can do it here, saving a future re-circulation.
        *
        * 2. Any packet that was sent through SNAT zone in the
        * previous table automatically gets re-circulated to get
        * back the new destination IP address that is needed for
        * routing in the openflow pipeline. */
        ovn_lflow_add(lflows, od, S_ROUTER_IN_DNAT, 50,
                      "ip", "inport = \"\"; ct_dnat;");
    }

    /* Logical router ingress table 2: IP Routing.
     *
     * A packet that arrives at this table is an IP packet that should be
     * routed to the address in ip4.dst. This table sets outport to the correct
     * output port, eth.src to the output port's MAC address, and reg0 to the
     * next-hop IP address (leaving ip4.dst, the packet’s final destination,
     * unchanged), and advances to the next table for ARP resolution. */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbr) {
            continue;
        }

        add_route(lflows, op, op->network, op->mask, 0);
    }
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbr) {
            continue;
        }

        /* Convert the static routes to flows. */
        for (int i = 0; i < od->nbr->n_static_routes; i++) {
            const struct nbrec_logical_router_static_route *route;

            route = od->nbr->static_routes[i];
            build_static_route_flow(lflows, od, ports, route);
        }

        if (od->gateway && od->gateway_port) {
            add_route(lflows, od->gateway_port, 0, 0, od->gateway);
        }
    }
    /* XXX destination unreachable */

    /* Local router ingress table 3: ARP Resolution.
     *
     * Any packet that reaches this table is an IP packet whose next-hop IP
     * address is in reg0. (ip4.dst is the final destination.) This table
     * resolves the IP address in reg0 into an output port in outport and an
     * Ethernet address in eth.dst. */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (op->nbr) {
            /* This is a logical router port. If next-hop IP address in 'reg0'
             * matches ip address of this router port, then the packet is
             * intended to eventually be sent to this logical port. Set the
             * destination mac address using this port's mac address.
             *
             * The packet is still in peer's logical pipeline. So the match
             * should be on peer's outport. */
            if (op->nbr->peer) {
                struct ovn_port *peer = ovn_port_find(ports, op->nbr->peer);
                if (!peer) {
                    continue;
                }

                if (!peer->ip || !op->ip) {
                    continue;
                }
                char *match = xasprintf("outport == %s && reg0 == "IP_FMT,
                                        peer->json_key, IP_ARGS(op->ip));
                char *actions = xasprintf("eth.dst = "ETH_ADDR_FMT"; "
                                          "next;", ETH_ADDR_ARGS(op->mac));
                ovn_lflow_add(lflows, peer->od, S_ROUTER_IN_ARP_RESOLVE,
                              100, match, actions);
                free(actions);
                free(match);
            }
        } else if (op->od->n_router_ports && strcmp(op->nbs->type, "router")) {
            /* This is a logical switch port that backs a VM or a container.
             * Extract its addresses. For each of the address, go through all
             * the router ports attached to the switch (to which this port
             * connects) and if the address in question is reachable from the
             * router port, add an ARP entry in that router's pipeline. */

            for (size_t i = 0; i < op->nbs->n_addresses; i++) {
                struct lport_addresses laddrs;
                if (!extract_lsp_addresses(op->nbs->addresses[i], &laddrs,
                                           false)) {
                    continue;
                }

                for (size_t k = 0; k < laddrs.n_ipv4_addrs; k++) {
                    ovs_be32 ip = laddrs.ipv4_addrs[k].addr;
                    for (size_t j = 0; j < op->od->n_router_ports; j++) {
                        /* Get the Logical_Router_Port that the
                         * Logical_Switch_Port is connected to, as
                         * 'peer'. */
                        const char *peer_name = smap_get(
                            &op->od->router_ports[j]->nbs->options,
                            "router-port");
                        if (!peer_name) {
                            continue;
                        }

                        struct ovn_port *peer
                            = ovn_port_find(ports, peer_name);
                        if (!peer || !peer->nbr) {
                            continue;
                        }

                        /* Make sure that 'ip' is in 'peer''s network. */
                        if ((ip ^ peer->network) & peer->mask) {
                            continue;
                        }

                        char *match = xasprintf(
                            "outport == %s && reg0 == "IP_FMT,
                            peer->json_key, IP_ARGS(ip));
                        char *actions = xasprintf("eth.dst = "ETH_ADDR_FMT"; "
                                                  "next;",
                                                  ETH_ADDR_ARGS(laddrs.ea));
                        ovn_lflow_add(lflows, peer->od,
                                      S_ROUTER_IN_ARP_RESOLVE,
                                      100, match, actions);
                        free(actions);
                        free(match);
                        break;
                    }
                }

                free(laddrs.ipv4_addrs);
            }
        } else if (!strcmp(op->nbs->type, "router")) {
            /* This is a logical switch port that connects to a router. */

            /* The peer of this switch port is the router port for which
             * we need to add logical flows such that it can resolve
             * ARP entries for all the other router ports connected to
             * the switch in question. */

            const char *peer_name = smap_get(&op->nbs->options,
                                             "router-port");
            if (!peer_name) {
                continue;
            }

            struct ovn_port *peer = ovn_port_find(ports, peer_name);
            if (!peer || !peer->nbr || !peer->ip) {
                continue;
            }

            for (size_t j = 0; j < op->od->n_router_ports; j++) {
                const char *router_port_name = smap_get(
                                    &op->od->router_ports[j]->nbs->options,
                                    "router-port");
                struct ovn_port *router_port = ovn_port_find(ports,
                                                             router_port_name);
                if (!router_port || !router_port->nbr || !router_port->ip) {
                    continue;
                }

                /* Skip the router port under consideration. */
                if (router_port == peer) {
                   continue;
                }

                if (!router_port->ip) {
                    continue;
                }
                char *match = xasprintf("outport == %s && reg0 == "IP_FMT,
                                        peer->json_key,
                                        IP_ARGS(router_port->ip));
                char *actions = xasprintf("eth.dst = "ETH_ADDR_FMT"; next;",
                                          ETH_ADDR_ARGS(router_port->mac));
                ovn_lflow_add(lflows, peer->od, S_ROUTER_IN_ARP_RESOLVE,
                              100, match, actions);
                free(actions);
                free(match);
            }
        }
    }

    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbr) {
            continue;
        }

        ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_RESOLVE, 0, "1",
                      "get_arp(outport, reg0); next;");
    }

    /* Local router ingress table 4: ARP request.
     *
     * In the common case where the Ethernet destination has been resolved,
     * this table outputs the packet (priority 100).  Otherwise, it composes
     * and sends an ARP request (priority 0). */
    HMAP_FOR_EACH (od, key_node, datapaths) {
        if (!od->nbr) {
            continue;
        }

        ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_REQUEST, 100,
                      "eth.dst == 00:00:00:00:00:00",
                      "arp { "
                      "eth.dst = ff:ff:ff:ff:ff:ff; "
                      "arp.spa = reg1; "
                      "arp.op = 1; " /* ARP request */
                      "output; "
                      "};");
        ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_REQUEST, 0, "1", "output;");
    }

    /* Logical router egress table 1: Delivery (priority 100).
     *
     * Priority 100 rules deliver packets to enabled logical ports. */
    HMAP_FOR_EACH (op, key_node, ports) {
        if (!op->nbr) {
            continue;
        }

        if (!lrport_is_enabled(op->nbr)) {
            /* Drop packets to disabled logical ports (since logical flow
             * tables are default-drop). */
            continue;
        }

        char *match = xasprintf("outport == %s", op->json_key);
        ovn_lflow_add(lflows, op->od, S_ROUTER_OUT_DELIVERY, 100,
                      match, "output;");
        free(match);
    }
}

/* Updates the Logical_Flow and Multicast_Group tables in the OVN_SB database,
 * constructing their contents based on the OVN_NB database. */
static void
build_lflows(struct northd_context *ctx, struct hmap *datapaths,
             struct hmap *ports)
{
    struct hmap lflows = HMAP_INITIALIZER(&lflows);
    struct hmap mcgroups = HMAP_INITIALIZER(&mcgroups);

    build_lswitch_flows(datapaths, ports, &lflows, &mcgroups);
    build_lrouter_flows(datapaths, ports, &lflows);

    /* Push changes to the Logical_Flow table to database. */
    const struct sbrec_logical_flow *sbflow, *next_sbflow;
    SBREC_LOGICAL_FLOW_FOR_EACH_SAFE (sbflow, next_sbflow, ctx->ovnsb_idl) {
        struct ovn_datapath *od
            = ovn_datapath_from_sbrec(datapaths, sbflow->logical_datapath);
        if (!od) {
            sbrec_logical_flow_delete(sbflow);
            continue;
        }

        enum ovn_datapath_type dp_type = od->nbs ? DP_SWITCH : DP_ROUTER;
        enum ovn_pipeline pipeline
            = !strcmp(sbflow->pipeline, "ingress") ? P_IN : P_OUT;
        struct ovn_lflow *lflow = ovn_lflow_find(
            &lflows, od, ovn_stage_build(dp_type, pipeline, sbflow->table_id),
            sbflow->priority, sbflow->match, sbflow->actions);
        if (lflow) {
            ovn_lflow_destroy(&lflows, lflow);
        } else {
            sbrec_logical_flow_delete(sbflow);
        }
    }
    struct ovn_lflow *lflow, *next_lflow;
    HMAP_FOR_EACH_SAFE (lflow, next_lflow, hmap_node, &lflows) {
        enum ovn_pipeline pipeline = ovn_stage_get_pipeline(lflow->stage);
        uint8_t table = ovn_stage_get_table(lflow->stage);

        sbflow = sbrec_logical_flow_insert(ctx->ovnsb_txn);
        sbrec_logical_flow_set_logical_datapath(sbflow, lflow->od->sb);
        sbrec_logical_flow_set_pipeline(
            sbflow, pipeline == P_IN ? "ingress" : "egress");
        sbrec_logical_flow_set_table_id(sbflow, table);
        sbrec_logical_flow_set_priority(sbflow, lflow->priority);
        sbrec_logical_flow_set_match(sbflow, lflow->match);
        sbrec_logical_flow_set_actions(sbflow, lflow->actions);

        const struct smap ids = SMAP_CONST1(&ids, "stage-name",
                                            ovn_stage_to_str(lflow->stage));
        sbrec_logical_flow_set_external_ids(sbflow, &ids);

        ovn_lflow_destroy(&lflows, lflow);
    }
    hmap_destroy(&lflows);

    /* Push changes to the Multicast_Group table to database. */
    const struct sbrec_multicast_group *sbmc, *next_sbmc;
    SBREC_MULTICAST_GROUP_FOR_EACH_SAFE (sbmc, next_sbmc, ctx->ovnsb_idl) {
        struct ovn_datapath *od = ovn_datapath_from_sbrec(datapaths,
                                                          sbmc->datapath);
        if (!od) {
            sbrec_multicast_group_delete(sbmc);
            continue;
        }

        struct multicast_group group = { .name = sbmc->name,
                                         .key = sbmc->tunnel_key };
        struct ovn_multicast *mc = ovn_multicast_find(&mcgroups, od, &group);
        if (mc) {
            ovn_multicast_update_sbrec(mc, sbmc);
            ovn_multicast_destroy(&mcgroups, mc);
        } else {
            sbrec_multicast_group_delete(sbmc);
        }
    }
    struct ovn_multicast *mc, *next_mc;
    HMAP_FOR_EACH_SAFE (mc, next_mc, hmap_node, &mcgroups) {
        sbmc = sbrec_multicast_group_insert(ctx->ovnsb_txn);
        sbrec_multicast_group_set_datapath(sbmc, mc->datapath->sb);
        sbrec_multicast_group_set_name(sbmc, mc->group->name);
        sbrec_multicast_group_set_tunnel_key(sbmc, mc->group->key);
        ovn_multicast_update_sbrec(mc, sbmc);
        ovn_multicast_destroy(&mcgroups, mc);
    }
    hmap_destroy(&mcgroups);
}

static void
ovnnb_db_run(struct northd_context *ctx)
{
    if (!ctx->ovnsb_txn) {
        return;
    }
    struct hmap datapaths, ports;
    build_datapaths(ctx, &datapaths);
    build_ports(ctx, &datapaths, &ports);
    build_lflows(ctx, &datapaths, &ports);

    struct ovn_datapath *dp, *next_dp;
    HMAP_FOR_EACH_SAFE (dp, next_dp, key_node, &datapaths) {
        ovn_datapath_destroy(&datapaths, dp);
    }
    hmap_destroy(&datapaths);

    struct ovn_port *port, *next_port;
    HMAP_FOR_EACH_SAFE (port, next_port, key_node, &ports) {
        ovn_port_destroy(&ports, port);
    }
    hmap_destroy(&ports);
}

/*
 * The only change we get notified about is if the 'chassis' column of the
 * 'Port_Binding' table changes.  When this column is not empty, it means we
 * need to set the corresponding logical port as 'up' in the northbound DB.
 */
static void
ovnsb_db_run(struct northd_context *ctx)
{
    if (!ctx->ovnnb_txn) {
        return;
    }
    struct hmap lports_hmap;
    const struct sbrec_port_binding *sb;
    const struct nbrec_logical_switch_port *nb;

    struct lport_hash_node {
        struct hmap_node node;
        const struct nbrec_logical_switch_port *nb;
    } *hash_node;

    hmap_init(&lports_hmap);

    NBREC_LOGICAL_SWITCH_PORT_FOR_EACH(nb, ctx->ovnnb_idl) {
        hash_node = xzalloc(sizeof *hash_node);
        hash_node->nb = nb;
        hmap_insert(&lports_hmap, &hash_node->node, hash_string(nb->name, 0));
    }

    SBREC_PORT_BINDING_FOR_EACH(sb, ctx->ovnsb_idl) {
        nb = NULL;
        HMAP_FOR_EACH_WITH_HASH(hash_node, node,
                                hash_string(sb->logical_port, 0),
                                &lports_hmap) {
            if (!strcmp(sb->logical_port, hash_node->nb->name)) {
                nb = hash_node->nb;
                break;
            }
        }

        if (!nb) {
            /* The logical port doesn't exist for this port binding.  This can
             * happen under normal circumstances when ovn-northd hasn't gotten
             * around to pruning the Port_Binding yet. */
            continue;
        }

        if (sb->chassis && (!nb->up || !*nb->up)) {
            bool up = true;
            nbrec_logical_switch_port_set_up(nb, &up, 1);
        } else if (!sb->chassis && (!nb->up || *nb->up)) {
            bool up = false;
            nbrec_logical_switch_port_set_up(nb, &up, 1);
        }
    }

    HMAP_FOR_EACH_POP(hash_node, node, &lports_hmap) {
        free(hash_node);
    }
    hmap_destroy(&lports_hmap);
}


static char *default_nb_db_;

static const char *
default_nb_db(void)
{
    if (!default_nb_db_) {
        default_nb_db_ = xasprintf("unix:%s/ovnnb_db.sock", ovs_rundir());
    }
    return default_nb_db_;
}

static char *default_sb_db_;

static const char *
default_sb_db(void)
{
    if (!default_sb_db_) {
        default_sb_db_ = xasprintf("unix:%s/ovnsb_db.sock", ovs_rundir());
    }
    return default_sb_db_;
}

static void
parse_options(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
{
    enum {
        DAEMON_OPTION_ENUMS,
        VLOG_OPTION_ENUMS,
    };
    static const struct option long_options[] = {
        {"ovnsb-db", required_argument, NULL, 'd'},
        {"ovnnb-db", required_argument, NULL, 'D'},
        {"help", no_argument, NULL, 'h'},
        {"options", no_argument, NULL, 'o'},
        {"version", no_argument, NULL, 'V'},
        DAEMON_LONG_OPTIONS,
        VLOG_LONG_OPTIONS,
        STREAM_SSL_LONG_OPTIONS,
        {NULL, 0, NULL, 0},
    };
    char *short_options = ovs_cmdl_long_options_to_short_options(long_options);

    for (;;) {
        int c;

        c = getopt_long(argc, argv, short_options, long_options, NULL);
        if (c == -1) {
            break;
        }

        switch (c) {
        DAEMON_OPTION_HANDLERS;
        VLOG_OPTION_HANDLERS;
        STREAM_SSL_OPTION_HANDLERS;

        case 'd':
            ovnsb_db = optarg;
            break;

        case 'D':
            ovnnb_db = optarg;
            break;

        case 'h':
            usage();
            exit(EXIT_SUCCESS);

        case 'o':
            ovs_cmdl_print_options(long_options);
            exit(EXIT_SUCCESS);

        case 'V':
            ovs_print_version(0, 0);
            exit(EXIT_SUCCESS);

        default:
            break;
        }
    }

    if (!ovnsb_db) {
        ovnsb_db = default_sb_db();
    }

    if (!ovnnb_db) {
        ovnnb_db = default_nb_db();
    }

    free(short_options);
}

static void
add_column_noalert(struct ovsdb_idl *idl,
                   const struct ovsdb_idl_column *column)
{
    ovsdb_idl_add_column(idl, column);
    ovsdb_idl_omit_alert(idl, column);
}

int
main(int argc, char *argv[])
{
    int res = EXIT_SUCCESS;
    struct unixctl_server *unixctl;
    int retval;
    bool exiting;

    fatal_ignore_sigpipe();
    set_program_name(argv[0]);
    service_start(&argc, &argv);
    parse_options(argc, argv);

    daemonize_start(false);

    retval = unixctl_server_create(NULL, &unixctl);
    if (retval) {
        exit(EXIT_FAILURE);
    }
    unixctl_command_register("exit", "", 0, 0, ovn_northd_exit, &exiting);

    daemonize_complete();

    nbrec_init();
    sbrec_init();

    /* We want to detect all changes to the ovn-nb db. */
    struct ovsdb_idl_loop ovnnb_idl_loop = OVSDB_IDL_LOOP_INITIALIZER(
        ovsdb_idl_create(ovnnb_db, &nbrec_idl_class, true, true));

    struct ovsdb_idl_loop ovnsb_idl_loop = OVSDB_IDL_LOOP_INITIALIZER(
        ovsdb_idl_create(ovnsb_db, &sbrec_idl_class, false, true));

    ovsdb_idl_add_table(ovnsb_idl_loop.idl, &sbrec_table_logical_flow);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_logical_flow_col_logical_datapath);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_logical_flow_col_pipeline);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_logical_flow_col_table_id);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_logical_flow_col_priority);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_logical_flow_col_match);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_logical_flow_col_actions);

    ovsdb_idl_add_table(ovnsb_idl_loop.idl, &sbrec_table_multicast_group);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_multicast_group_col_datapath);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_multicast_group_col_tunnel_key);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_multicast_group_col_name);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_multicast_group_col_ports);

    ovsdb_idl_add_table(ovnsb_idl_loop.idl, &sbrec_table_datapath_binding);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_datapath_binding_col_tunnel_key);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_datapath_binding_col_external_ids);

    ovsdb_idl_add_table(ovnsb_idl_loop.idl, &sbrec_table_port_binding);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_port_binding_col_datapath);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_port_binding_col_logical_port);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_port_binding_col_tunnel_key);
    add_column_noalert(ovnsb_idl_loop.idl,
                       &sbrec_port_binding_col_parent_port);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_port_binding_col_tag);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_port_binding_col_type);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_port_binding_col_options);
    add_column_noalert(ovnsb_idl_loop.idl, &sbrec_port_binding_col_mac);
    ovsdb_idl_add_column(ovnsb_idl_loop.idl, &sbrec_port_binding_col_chassis);

    /* Main loop. */
    exiting = false;
    while (!exiting) {
        struct northd_context ctx = {
            .ovnnb_idl = ovnnb_idl_loop.idl,
            .ovnnb_txn = ovsdb_idl_loop_run(&ovnnb_idl_loop),
            .ovnsb_idl = ovnsb_idl_loop.idl,
            .ovnsb_txn = ovsdb_idl_loop_run(&ovnsb_idl_loop),
        };

        ovnnb_db_run(&ctx);
        ovnsb_db_run(&ctx);

        unixctl_server_run(unixctl);
        unixctl_server_wait(unixctl);
        if (exiting) {
            poll_immediate_wake();
        }
        ovsdb_idl_loop_commit_and_wait(&ovnnb_idl_loop);
        ovsdb_idl_loop_commit_and_wait(&ovnsb_idl_loop);

        poll_block();
        if (should_service_stop()) {
            exiting = true;
        }
    }

    unixctl_server_destroy(unixctl);
    ovsdb_idl_loop_destroy(&ovnnb_idl_loop);
    ovsdb_idl_loop_destroy(&ovnsb_idl_loop);
    service_stop();

    free(default_nb_db_);
    free(default_sb_db_);
    exit(res);
}

static void
ovn_northd_exit(struct unixctl_conn *conn, int argc OVS_UNUSED,
                const char *argv[] OVS_UNUSED, void *exiting_)
{
    bool *exiting = exiting_;
    *exiting = true;

    unixctl_command_reply(conn, NULL);
}