/*
 * Copyright (c) 2009, 2010 Nicira Networks.
 * Copyright (c) 2010 Jean Tourrilhes - HP-Labs.
 *
 * 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 "ofproto.h"
#include <errno.h>
#include <inttypes.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stdlib.h>
#include "classifier.h"
#include "coverage.h"
#include "discovery.h"
#include "dynamic-string.h"
#include "fail-open.h"
#include "hash.h"
#include "hmap.h"
#include "in-band.h"
#include "mac-learning.h"
#include "netdev.h"
#include "netflow.h"
#include "ofp-print.h"
#include "ofp-util.h"
#include "ofproto-sflow.h"
#include "ofpbuf.h"
#include "openflow/nicira-ext.h"
#include "openflow/openflow.h"
#include "openvswitch/xflow.h"
#include "packets.h"
#include "pinsched.h"
#include "pktbuf.h"
#include "poll-loop.h"
#include "rconn.h"
#include "shash.h"
#include "status.h"
#include "stream-ssl.h"
#include "svec.h"
#include "tag.h"
#include "timeval.h"
#include "unixctl.h"
#include "vconn.h"
#include "vlog.h"
#include "wdp.h"
#include "xfif.h"
#include "xtoxll.h"

VLOG_DEFINE_THIS_MODULE(ofproto)

#include "sflow_api.h"

struct ofproto_rule {
    uint64_t flow_cookie;       /* Controller-issued identifier.
                                   (Kept in network-byte order.) */
    bool send_flow_removed;     /* Send a flow removed message? */
    tag_type tags;              /* Tags (set only by hooks). */
};

static struct ofproto_rule *
ofproto_rule_cast(const struct wdp_rule *wdp_rule)
{
    return wdp_rule->client_data;
}

static void
ofproto_rule_init(struct wdp_rule *wdp_rule)
{
    wdp_rule->client_data = xzalloc(sizeof(struct ofproto_rule));
}

static inline bool
rule_is_hidden(const struct wdp_rule *rule)
{
    /* Rules with priority higher than UINT16_MAX are set up by ofproto itself
     * (e.g. by in-band control) and are intentionally hidden from the
     * controller. */
    if (rule->cr.flow.priority > UINT16_MAX) {
        return true;
    }

    return false;
}

static int delete_flow(struct ofproto *, struct wdp_rule *, uint8_t reason);

/* ofproto supports two kinds of OpenFlow connections:
 *
 *   - "Primary" connections to ordinary OpenFlow controllers.  ofproto
 *     maintains persistent connections to these controllers and by default
 *     sends them asynchronous messages such as packet-ins.
 *
 *   - "Service" connections, e.g. from ovs-ofctl.  When these connections
 *     drop, it is the other side's responsibility to reconnect them if
 *     necessary.  ofproto does not send them asynchronous messages by default.
 *
 * Currently, active (tcp, ssl, unix) connections are always "primary"
 * connections and passive (ptcp, pssl, punix) connections are always "service"
 * connections.  There is no inherent reason for this, but it reflects the
 * common case.
 */
enum ofconn_type {
    OFCONN_PRIMARY,             /* An ordinary OpenFlow controller. */
    OFCONN_SERVICE              /* A service connection, e.g. "ovs-ofctl". */
};

/* A listener for incoming OpenFlow "service" connections. */
struct ofservice {
    struct hmap_node node;      /* In struct ofproto's "services" hmap. */
    struct pvconn *pvconn;      /* OpenFlow connection listener. */

    /* These are not used by ofservice directly.  They are settings for
     * accepted "struct ofconn"s from the pvconn. */
    int probe_interval;         /* Max idle time before probing, in seconds. */
    int rate_limit;             /* Max packet-in rate in packets per second. */
    int burst_limit;            /* Limit on accumulating packet credits. */
};

static struct ofservice *ofservice_lookup(struct ofproto *,
                                          const char *target);
static int ofservice_create(struct ofproto *,
                            const struct ofproto_controller *);
static void ofservice_reconfigure(struct ofservice *,
                                  const struct ofproto_controller *);
static void ofservice_destroy(struct ofproto *, struct ofservice *);

/* An OpenFlow connection. */
struct ofconn {
    struct ofproto *ofproto;    /* The ofproto that owns this connection. */
    struct list node;           /* In struct ofproto's "all_conns" list. */
    struct rconn *rconn;        /* OpenFlow connection. */
    enum ofconn_type type;      /* Type. */
    bool flow_mod_table_id;     /* NXT_FLOW_MOD_TABLE_ID enabled? */

    /* OFPT_PACKET_IN related data. */
    struct rconn_packet_counter *packet_in_counter; /* # queued on 'rconn'. */
    struct pinsched *schedulers[2]; /* Indexed by reason code; see below. */
    struct pktbuf *pktbuf;         /* OpenFlow packet buffers. */
    int miss_send_len;             /* Bytes to send of buffered packets. */

    /* Number of OpenFlow messages queued on 'rconn' as replies to OpenFlow
     * requests, and the maximum number before we stop reading OpenFlow
     * requests.  */
#define OFCONN_REPLY_MAX 100
    struct rconn_packet_counter *reply_counter;

    /* type == OFCONN_PRIMARY only. */
    enum nx_role role;           /* Role. */
    struct hmap_node hmap_node;  /* In struct ofproto's "controllers" map. */
    struct discovery *discovery; /* Controller discovery object, if enabled. */
    struct status_category *ss;  /* Switch status category. */
    enum ofproto_band band;      /* In-band or out-of-band? */
};

/* We use OFPR_NO_MATCH and OFPR_ACTION as indexes into struct ofconn's
 * "schedulers" array.  Their values are 0 and 1, and their meanings and values
 * coincide with WDP_CHAN_MISS and WDP_CHAN_ACTION, so this is convenient.  In
 * case anything ever changes, check their values here.  */
#define N_SCHEDULERS 2
BUILD_ASSERT_DECL(OFPR_NO_MATCH == 0);
BUILD_ASSERT_DECL(OFPR_NO_MATCH == WDP_CHAN_MISS);
BUILD_ASSERT_DECL(OFPR_ACTION == 1);
BUILD_ASSERT_DECL(OFPR_ACTION == WDP_CHAN_ACTION);

static struct ofconn *ofconn_create(struct ofproto *, struct rconn *,
                                    enum ofconn_type);
static void ofconn_destroy(struct ofconn *);
static void ofconn_run(struct ofconn *, struct ofproto *);
static void ofconn_wait(struct ofconn *);
static bool ofconn_receives_async_msgs(const struct ofconn *);
static char *ofconn_make_name(const struct ofproto *, const char *target);
static void ofconn_set_rate_limit(struct ofconn *, int rate, int burst);

static void queue_tx(struct ofpbuf *msg, const struct ofconn *ofconn,
                     struct rconn_packet_counter *counter);

static void send_packet_in(struct ofproto *, struct wdp_packet *);
static void do_send_packet_in(struct wdp_packet *, void *ofconn);

struct ofproto {
    /* Settings. */
    uint64_t datapath_id;       /* Datapath ID. */
    uint64_t fallback_dpid;     /* Datapath ID if no better choice found. */
    char *mfr_desc;             /* Manufacturer. */
    char *hw_desc;              /* Hardware. */
    char *sw_desc;              /* Software version. */
    char *serial_desc;          /* Serial number. */
    char *dp_desc;              /* Datapath description. */

    /* Datapath. */
    struct wdp *wdp;
    uint32_t max_ports;

    /* Configuration. */
    struct switch_status *switch_status;
    struct fail_open *fail_open;
    struct netflow *netflow;
    struct ofproto_sflow *sflow;
    bool tun_id_from_cookie;    /* NXT_TUN_ID_FROM_COOKIE enabled? */

    /* In-band control. */
    struct in_band *in_band;
    long long int next_in_band_update;
    struct sockaddr_in *extra_in_band_remotes;
    size_t n_extra_remotes;

    /* OpenFlow connections. */
    struct hmap controllers;   /* Controller "struct ofconn"s. */
    struct list all_conns;     /* Contains "struct ofconn"s. */
    enum ofproto_fail_mode fail_mode;

    /* OpenFlow listeners. */
    struct hmap services;       /* Contains "struct ofservice"s. */
    struct pvconn **snoops;
    size_t n_snoops;
};

static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);

static uint64_t pick_datapath_id(const struct ofproto *);
static uint64_t pick_fallback_dpid(void);

static void handle_wdp_packet(struct ofproto *, struct wdp_packet *);

static void handle_openflow(struct ofconn *, struct ofproto *,
                            struct ofpbuf *);

int
ofproto_create(const char *datapath, const char *datapath_type,
               const struct ofhooks *ofhooks, void *aux,
               struct ofproto **ofprotop)
{
    struct wdp_stats stats;
    struct ofproto *p;
    struct wdp *wdp;
    int error;

    *ofprotop = NULL;

    /* Connect to datapath and start listening for messages. */
    error = wdp_open(datapath, datapath_type, &wdp);
    if (error) {
        VLOG_ERR("failed to open datapath %s: %s", datapath, strerror(error));
        return error;
    }
    error = wdp_get_wdp_stats(wdp, &stats);
    if (error) {
        VLOG_ERR("failed to obtain stats for datapath %s: %s",
                 datapath, strerror(error));
        wdp_close(wdp);
        return error;
    }
    error = wdp_recv_set_mask(wdp, ((1 << WDP_CHAN_MISS)
                                    | (1 << WDP_CHAN_ACTION)
                                    | (1 << WDP_CHAN_SFLOW)));
    if (error) {
        VLOG_ERR("failed to listen on datapath %s: %s",
                 datapath, strerror(error));
        wdp_close(wdp);
        return error;
    }
    wdp_flow_flush(wdp);
    wdp_recv_purge(wdp);
    wdp_set_ofhooks(wdp, ofhooks, aux);

    /* Initialize settings. */
    p = xzalloc(sizeof *p);
    p->fallback_dpid = pick_fallback_dpid();
    p->datapath_id = p->fallback_dpid;
    p->mfr_desc = xstrdup(DEFAULT_MFR_DESC);
    p->hw_desc = xstrdup(DEFAULT_HW_DESC);
    p->sw_desc = xstrdup(DEFAULT_SW_DESC);
    p->serial_desc = xstrdup(DEFAULT_SERIAL_DESC);
    p->dp_desc = xstrdup(DEFAULT_DP_DESC);

    /* Initialize datapath. */
    p->wdp = wdp;
    p->max_ports = stats.max_ports;

    /* Initialize submodules. */
    p->switch_status = switch_status_create(p);
    p->in_band = NULL;
    p->fail_open = NULL;
    p->netflow = NULL;
    p->sflow = NULL;

    /* Initialize OpenFlow connections. */
    list_init(&p->all_conns);
    hmap_init(&p->controllers);
    hmap_init(&p->services);
    p->snoops = NULL;
    p->n_snoops = 0;

    /* Pick final datapath ID. */
    p->datapath_id = pick_datapath_id(p);
    VLOG_INFO("using datapath ID %016"PRIx64, p->datapath_id);

    *ofprotop = p;
    return 0;
}

void
ofproto_set_datapath_id(struct ofproto *p, uint64_t datapath_id)
{
    uint64_t old_dpid = p->datapath_id;
    p->datapath_id = datapath_id ? datapath_id : pick_datapath_id(p);
    if (p->datapath_id != old_dpid) {
        VLOG_INFO("datapath ID changed to %016"PRIx64, p->datapath_id);

        /* Force all active connections to reconnect, since there is no way to
         * notify a controller that the datapath ID has changed. */
        ofproto_reconnect_controllers(p);
    }
}

static bool
is_discovery_controller(const struct ofproto_controller *c)
{
    return !strcmp(c->target, "discover");
}

static bool
is_in_band_controller(const struct ofproto_controller *c)
{
    return is_discovery_controller(c) || c->band == OFPROTO_IN_BAND;
}

/* Creates a new controller in 'ofproto'.  Some of the settings are initially
 * drawn from 'c', but update_controller() needs to be called later to finish
 * the new ofconn's configuration. */
static void
add_controller(struct ofproto *ofproto, const struct ofproto_controller *c)
{
    struct discovery *discovery;
    struct ofconn *ofconn;

    if (is_discovery_controller(c)) {
        int error = discovery_create(c->accept_re, c->update_resolv_conf,
                                     ofproto->wdp, ofproto->switch_status,
                                     &discovery);
        if (error) {
            return;
        }
    } else {
        discovery = NULL;
    }

    ofconn = ofconn_create(ofproto, rconn_create(5, 8), OFCONN_PRIMARY);
    ofconn->pktbuf = pktbuf_create();
    ofconn->miss_send_len = OFP_DEFAULT_MISS_SEND_LEN;
    if (discovery) {
        ofconn->discovery = discovery;
    } else {
        char *name = ofconn_make_name(ofproto, c->target);
        rconn_connect(ofconn->rconn, c->target, name);
        free(name);
    }
    hmap_insert(&ofproto->controllers, &ofconn->hmap_node,
                hash_string(c->target, 0));
}

/* Reconfigures 'ofconn' to match 'c'.  This function cannot update an ofconn's
 * target or turn discovery on or off (these are done by creating new ofconns
 * and deleting old ones), but it can update the rest of an ofconn's
 * settings. */
static void
update_controller(struct ofconn *ofconn, const struct ofproto_controller *c)
{
    int probe_interval;

    ofconn->band = (is_in_band_controller(c)
                    ? OFPROTO_IN_BAND : OFPROTO_OUT_OF_BAND);

    rconn_set_max_backoff(ofconn->rconn, c->max_backoff);

    probe_interval = c->probe_interval ? MAX(c->probe_interval, 5) : 0;
    rconn_set_probe_interval(ofconn->rconn, probe_interval);

    if (ofconn->discovery) {
        discovery_set_update_resolv_conf(ofconn->discovery,
                                         c->update_resolv_conf);
        discovery_set_accept_controller_re(ofconn->discovery, c->accept_re);
    }

    ofconn_set_rate_limit(ofconn, c->rate_limit, c->burst_limit);
}

static const char *
ofconn_get_target(const struct ofconn *ofconn)
{
    return ofconn->discovery ? "discover" : rconn_get_target(ofconn->rconn);
}

static struct ofconn *
find_controller_by_target(struct ofproto *ofproto, const char *target)
{
    struct ofconn *ofconn;

    HMAP_FOR_EACH_WITH_HASH (ofconn, hmap_node,
                             hash_string(target, 0), &ofproto->controllers) {
        if (!strcmp(ofconn_get_target(ofconn), target)) {
            return ofconn;
        }
    }
    return NULL;
}

static void
update_in_band_remotes(struct ofproto *ofproto)
{
    const struct ofconn *ofconn;
    struct sockaddr_in *addrs;
    size_t max_addrs, n_addrs;
    bool discovery;
    size_t i;

    /* Allocate enough memory for as many remotes as we could possibly have. */
    max_addrs = ofproto->n_extra_remotes + hmap_count(&ofproto->controllers);
    addrs = xmalloc(max_addrs * sizeof *addrs);
    n_addrs = 0;

    /* Add all the remotes. */
    discovery = false;
    HMAP_FOR_EACH (ofconn, hmap_node, &ofproto->controllers) {
        struct sockaddr_in *sin = &addrs[n_addrs];

        if (ofconn->band == OFPROTO_OUT_OF_BAND) {
            continue;
        }

        sin->sin_addr.s_addr = rconn_get_remote_ip(ofconn->rconn);
        if (sin->sin_addr.s_addr) {
            sin->sin_port = rconn_get_remote_port(ofconn->rconn);
            n_addrs++;
        }
        if (ofconn->discovery) {
            discovery = true;
        }
    }
    for (i = 0; i < ofproto->n_extra_remotes; i++) {
        addrs[n_addrs++] = ofproto->extra_in_band_remotes[i];
    }

    /* Create or update or destroy in-band.
     *
     * Ordinarily we only enable in-band if there's at least one remote
     * address, but discovery needs the in-band rules for DHCP to be installed
     * even before we know any remote addresses. */
    if (n_addrs || discovery) {
        if (!ofproto->in_band) {
            in_band_create(ofproto, ofproto->wdp, ofproto->switch_status,
                           &ofproto->in_band);
        }
        if (ofproto->in_band) {
            in_band_set_remotes(ofproto->in_band, addrs, n_addrs);
        }
        ofproto->next_in_band_update = time_msec() + 1000;
    } else {
        in_band_destroy(ofproto->in_band);
        ofproto->in_band = NULL;
    }

    /* Clean up. */
    free(addrs);
}

static void
update_fail_open(struct ofproto *p)
{
    struct ofconn *ofconn;

    if (!hmap_is_empty(&p->controllers)
            && p->fail_mode == OFPROTO_FAIL_STANDALONE) {
        struct rconn **rconns;
        size_t n;

        if (!p->fail_open) {
            p->fail_open = fail_open_create(p, p->switch_status);
        }

        n = 0;
        rconns = xmalloc(hmap_count(&p->controllers) * sizeof *rconns);
        HMAP_FOR_EACH (ofconn, hmap_node, &p->controllers) {
            rconns[n++] = ofconn->rconn;
        }

        fail_open_set_controllers(p->fail_open, rconns, n);
        /* p->fail_open takes ownership of 'rconns'. */
    } else {
        fail_open_destroy(p->fail_open);
        p->fail_open = NULL;
    }
}

void
ofproto_set_controllers(struct ofproto *p,
                        const struct ofproto_controller *controllers,
                        size_t n_controllers)
{
    struct shash new_controllers;
    struct ofconn *ofconn, *next_ofconn;
    struct ofservice *ofservice, *next_ofservice;
    bool ss_exists;
    size_t i;

    /* Create newly configured controllers and services.
     * Create a name to ofproto_controller mapping in 'new_controllers'. */
    shash_init(&new_controllers);
    for (i = 0; i < n_controllers; i++) {
        const struct ofproto_controller *c = &controllers[i];

        if (!vconn_verify_name(c->target) || !strcmp(c->target, "discover")) {
            if (!find_controller_by_target(p, c->target)) {
                add_controller(p, c);
            }
        } else if (!pvconn_verify_name(c->target)) {
            if (!ofservice_lookup(p, c->target) && ofservice_create(p, c)) {
                continue;
            }
        } else {
            VLOG_WARN_RL(&rl, "%s: unsupported controller \"%s\"",
                         wdp_name(p->wdp), c->target);
            continue;
        }

        shash_add_once(&new_controllers, c->target, &controllers[i]);
    }

    /* Delete controllers that are no longer configured.
     * Update configuration of all now-existing controllers. */
    ss_exists = false;
    HMAP_FOR_EACH_SAFE (ofconn, next_ofconn, hmap_node, &p->controllers) {
        struct ofproto_controller *c;

        c = shash_find_data(&new_controllers, ofconn_get_target(ofconn));
        if (!c) {
            ofconn_destroy(ofconn);
        } else {
            update_controller(ofconn, c);
            if (ofconn->ss) {
                ss_exists = true;
            }
        }
    }

    /* Delete services that are no longer configured.
     * Update configuration of all now-existing services. */
    HMAP_FOR_EACH_SAFE (ofservice, next_ofservice, node, &p->services) {
        struct ofproto_controller *c;

        c = shash_find_data(&new_controllers,
                            pvconn_get_name(ofservice->pvconn));
        if (!c) {
            ofservice_destroy(p, ofservice);
        } else {
            ofservice_reconfigure(ofservice, c);
        }
    }

    shash_destroy(&new_controllers);

    update_in_band_remotes(p);
    update_fail_open(p);

    if (!hmap_is_empty(&p->controllers) && !ss_exists) {
        ofconn = CONTAINER_OF(hmap_first(&p->controllers),
                              struct ofconn, hmap_node);
        ofconn->ss = switch_status_register(p->switch_status, "remote",
                                            rconn_status_cb, ofconn->rconn);
    }
}

void
ofproto_set_fail_mode(struct ofproto *p, enum ofproto_fail_mode fail_mode)
{
    p->fail_mode = fail_mode;
    update_fail_open(p);
}

/* Drops the connections between 'ofproto' and all of its controllers, forcing
 * them to reconnect. */
void
ofproto_reconnect_controllers(struct ofproto *ofproto)
{
    struct ofconn *ofconn;

    LIST_FOR_EACH (ofconn, node, &ofproto->all_conns) {
        rconn_reconnect(ofconn->rconn);
    }
}

static bool
any_extras_changed(const struct ofproto *ofproto,
                   const struct sockaddr_in *extras, size_t n)
{
    size_t i;

    if (n != ofproto->n_extra_remotes) {
        return true;
    }

    for (i = 0; i < n; i++) {
        const struct sockaddr_in *old = &ofproto->extra_in_band_remotes[i];
        const struct sockaddr_in *new = &extras[i];

        if (old->sin_addr.s_addr != new->sin_addr.s_addr ||
            old->sin_port != new->sin_port) {
            return true;
        }
    }

    return false;
}

/* Sets the 'n' TCP port addresses in 'extras' as ones to which 'ofproto''s
 * in-band control should guarantee access, in the same way that in-band
 * control guarantees access to OpenFlow controllers. */
void
ofproto_set_extra_in_band_remotes(struct ofproto *ofproto,
                                  const struct sockaddr_in *extras, size_t n)
{
    if (!any_extras_changed(ofproto, extras, n)) {
        return;
    }

    free(ofproto->extra_in_band_remotes);
    ofproto->n_extra_remotes = n;
    ofproto->extra_in_band_remotes = xmemdup(extras, n * sizeof *extras);

    update_in_band_remotes(ofproto);
}

void
ofproto_set_desc(struct ofproto *p,
                 const char *mfr_desc, const char *hw_desc,
                 const char *sw_desc, const char *serial_desc,
                 const char *dp_desc)
{
    struct ofp_desc_stats *ods;

    if (mfr_desc) {
        if (strlen(mfr_desc) >= sizeof ods->mfr_desc) {
            VLOG_WARN("truncating mfr_desc, must be less than %zu characters",
                    sizeof ods->mfr_desc);
        }
        free(p->mfr_desc);
        p->mfr_desc = xstrdup(mfr_desc);
    }
    if (hw_desc) {
        if (strlen(hw_desc) >= sizeof ods->hw_desc) {
            VLOG_WARN("truncating hw_desc, must be less than %zu characters",
                    sizeof ods->hw_desc);
        }
        free(p->hw_desc);
        p->hw_desc = xstrdup(hw_desc);
    }
    if (sw_desc) {
        if (strlen(sw_desc) >= sizeof ods->sw_desc) {
            VLOG_WARN("truncating sw_desc, must be less than %zu characters",
                    sizeof ods->sw_desc);
        }
        free(p->sw_desc);
        p->sw_desc = xstrdup(sw_desc);
    }
    if (serial_desc) {
        if (strlen(serial_desc) >= sizeof ods->serial_num) {
            VLOG_WARN("truncating serial_desc, must be less than %zu "
                    "characters",
                    sizeof ods->serial_num);
        }
        free(p->serial_desc);
        p->serial_desc = xstrdup(serial_desc);
    }
    if (dp_desc) {
        if (strlen(dp_desc) >= sizeof ods->dp_desc) {
            VLOG_WARN("truncating dp_desc, must be less than %zu characters",
                    sizeof ods->dp_desc);
        }
        free(p->dp_desc);
        p->dp_desc = xstrdup(dp_desc);
    }
}

static int
set_pvconns(struct pvconn ***pvconnsp, size_t *n_pvconnsp,
            const struct svec *svec)
{
    struct pvconn **pvconns = *pvconnsp;
    size_t n_pvconns = *n_pvconnsp;
    int retval = 0;
    size_t i;

    for (i = 0; i < n_pvconns; i++) {
        pvconn_close(pvconns[i]);
    }
    free(pvconns);

    pvconns = xmalloc(svec->n * sizeof *pvconns);
    n_pvconns = 0;
    for (i = 0; i < svec->n; i++) {
        const char *name = svec->names[i];
        struct pvconn *pvconn;
        int error;

        error = pvconn_open(name, &pvconn);
        if (!error) {
            pvconns[n_pvconns++] = pvconn;
        } else {
            VLOG_ERR("failed to listen on %s: %s", name, strerror(error));
            if (!retval) {
                retval = error;
            }
        }
    }

    *pvconnsp = pvconns;
    *n_pvconnsp = n_pvconns;

    return retval;
}

int
ofproto_set_snoops(struct ofproto *ofproto, const struct svec *snoops)
{
    return set_pvconns(&ofproto->snoops, &ofproto->n_snoops, snoops);
}

int
ofproto_set_netflow(struct ofproto *ofproto,
                    const struct netflow_options *nf_options)
{
    if (nf_options && nf_options->collectors.n) {
        if (!ofproto->netflow) {
            ofproto->netflow = netflow_create();
        }
        return netflow_set_options(ofproto->netflow, nf_options);
    } else {
        netflow_destroy(ofproto->netflow);
        ofproto->netflow = NULL;
        return 0;
    }
}

void
ofproto_set_sflow(struct ofproto *ofproto,
                  const struct ofproto_sflow_options *oso)
{
    struct ofproto_sflow *os = ofproto->sflow;
    if (oso) {
        if (!os) {
            os = ofproto->sflow = ofproto_sflow_create(ofproto->wdp);
            /* XXX ofport */
        }
        ofproto_sflow_set_options(os, oso);
    } else {
        ofproto_sflow_destroy(os);
        ofproto->sflow = NULL;
    }
}

uint64_t
ofproto_get_datapath_id(const struct ofproto *ofproto)
{
    return ofproto->datapath_id;
}

bool
ofproto_has_primary_controller(const struct ofproto *ofproto)
{
    return !hmap_is_empty(&ofproto->controllers);
}

enum ofproto_fail_mode
ofproto_get_fail_mode(const struct ofproto *p)
{
    return p->fail_mode;
}

void
ofproto_get_snoops(const struct ofproto *ofproto, struct svec *snoops)
{
    size_t i;

    for (i = 0; i < ofproto->n_snoops; i++) {
        svec_add(snoops, pvconn_get_name(ofproto->snoops[i]));
    }
}

void
ofproto_destroy(struct ofproto *p)
{
    struct ofservice *ofservice, *next_ofservice;
    struct ofconn *ofconn, *next_ofconn;
    size_t i;

    if (!p) {
        return;
    }

    /* Destroy fail-open and in-band early, since they touch the classifier. */
    fail_open_destroy(p->fail_open);
    p->fail_open = NULL;

    in_band_destroy(p->in_band);
    p->in_band = NULL;
    free(p->extra_in_band_remotes);

    ofproto_flush_flows(p);

    LIST_FOR_EACH_SAFE (ofconn, next_ofconn, node, &p->all_conns) {
        ofconn_destroy(ofconn);
    }
    hmap_destroy(&p->controllers);

    wdp_close(p->wdp);

    switch_status_destroy(p->switch_status);
    netflow_destroy(p->netflow);
    ofproto_sflow_destroy(p->sflow);

    HMAP_FOR_EACH_SAFE (ofservice, next_ofservice, node, &p->services) {
        ofservice_destroy(p, ofservice);
    }
    hmap_destroy(&p->services);

    for (i = 0; i < p->n_snoops; i++) {
        pvconn_close(p->snoops[i]);
    }
    free(p->snoops);

    free(p->mfr_desc);
    free(p->hw_desc);
    free(p->sw_desc);
    free(p->serial_desc);
    free(p->dp_desc);

    free(p);
}

int
ofproto_run(struct ofproto *p)
{
    int error = ofproto_run1(p);
    if (!error) {
        error = ofproto_run2(p, false);
    }
    return error;
}

/* Returns a "preference level" for snooping 'ofconn'.  A higher return value
 * means that 'ofconn' is more interesting for monitoring than a lower return
 * value. */
static int
snoop_preference(const struct ofconn *ofconn)
{
    switch (ofconn->role) {
    case NX_ROLE_MASTER:
        return 3;
    case NX_ROLE_OTHER:
        return 2;
    case NX_ROLE_SLAVE:
        return 1;
    default:
        /* Shouldn't happen. */
        return 0;
    }
}

/* One of ofproto's "snoop" pvconns has accepted a new connection on 'vconn'.
 * Connects this vconn to a controller. */
static void
add_snooper(struct ofproto *ofproto, struct vconn *vconn)
{
    struct ofconn *ofconn, *best;

    /* Pick a controller for monitoring. */
    best = NULL;
    LIST_FOR_EACH (ofconn, node, &ofproto->all_conns) {
        if (ofconn->type == OFCONN_PRIMARY
            && (!best || snoop_preference(ofconn) > snoop_preference(best))) {
            best = ofconn;
        }
    }

    if (best) {
        rconn_add_monitor(best->rconn, vconn);
    } else {
        VLOG_INFO_RL(&rl, "no controller connection to snoop");
        vconn_close(vconn);
    }
}

static void
ofproto_port_poll_cb(const struct ofp_phy_port *opp, uint8_t reason,
                     void *ofproto_)
{
    /* XXX Should limit the number of queued port status change messages. */
    struct ofproto *ofproto = ofproto_;
    struct ofconn *ofconn;

    LIST_FOR_EACH (ofconn, node, &ofproto->all_conns) {
        struct ofp_port_status *ops;
        struct ofpbuf *b;

        if (!ofconn_receives_async_msgs(ofconn)) {
            continue;
        }

        ops = make_openflow_xid(sizeof *ops, OFPT_PORT_STATUS, 0, &b);
        ops->reason = reason;
        ops->desc = *opp;
        hton_ofp_phy_port(&ops->desc);
        queue_tx(b, ofconn, NULL);
    }
}

int
ofproto_run1(struct ofproto *p)
{
    struct ofconn *ofconn, *next_ofconn;
    struct ofservice *ofservice;
    int i;

    for (i = 0; i < 50; i++) {
        struct wdp_packet packet;
        int error;

        error = wdp_recv(p->wdp, &packet);
        if (error) {
            if (error == ENODEV) {
                /* Someone destroyed the datapath behind our back.  The caller
                 * better destroy us and give up, because we're just going to
                 * spin from here on out. */
                static struct vlog_rate_limit rl2 = VLOG_RATE_LIMIT_INIT(1, 5);
                VLOG_ERR_RL(&rl2, "%s: datapath was destroyed externally",
                            wdp_name(p->wdp));
                return ENODEV;
            }
            break;
        }

        handle_wdp_packet(p, xmemdup(&packet, sizeof packet));
    }

    wdp_port_poll(p->wdp, ofproto_port_poll_cb, p);

    if (p->in_band) {
        if (time_msec() >= p->next_in_band_update) {
            update_in_band_remotes(p);
        }
        in_band_run(p->in_band);
    }

    LIST_FOR_EACH_SAFE (ofconn, next_ofconn, node, &p->all_conns) {
        ofconn_run(ofconn, p);
    }

    /* Fail-open maintenance.  Do this after processing the ofconns since
     * fail-open checks the status of the controller rconn. */
    if (p->fail_open) {
        fail_open_run(p->fail_open);
    }

    HMAP_FOR_EACH (ofservice, node, &p->services) {
        struct vconn *vconn;
        int retval;

        retval = pvconn_accept(ofservice->pvconn, OFP_VERSION, &vconn);
        if (!retval) {
            struct rconn *rconn;
            char *name;

            rconn = rconn_create(ofservice->probe_interval, 0);
            name = ofconn_make_name(p, vconn_get_name(vconn));
            rconn_connect_unreliably(rconn, vconn, name);
            free(name);

            ofconn = ofconn_create(p, rconn, OFCONN_SERVICE);
            ofconn_set_rate_limit(ofconn, ofservice->rate_limit,
                                  ofservice->burst_limit);
        } else if (retval != EAGAIN) {
            VLOG_WARN_RL(&rl, "accept failed (%s)", strerror(retval));
        }
    }

    for (i = 0; i < p->n_snoops; i++) {
        struct vconn *vconn;
        int retval;

        retval = pvconn_accept(p->snoops[i], OFP_VERSION, &vconn);
        if (!retval) {
            add_snooper(p, vconn);
        } else if (retval != EAGAIN) {
            VLOG_WARN_RL(&rl, "accept failed (%s)", strerror(retval));
        }
    }

    if (p->netflow) {
        netflow_run(p->netflow);
    }
    if (p->sflow) {
        ofproto_sflow_run(p->sflow);
    }

    return 0;
}

int
ofproto_run2(struct ofproto *p OVS_UNUSED, bool revalidate_all OVS_UNUSED)
{
    return 0;
}

void
ofproto_wait(struct ofproto *p)
{
    struct ofservice *ofservice;
    struct ofconn *ofconn;
    size_t i;

    wdp_recv_wait(p->wdp);
    wdp_port_poll_wait(p->wdp);
    LIST_FOR_EACH (ofconn, node, &p->all_conns) {
        ofconn_wait(ofconn);
    }
    if (p->in_band) {
        poll_timer_wait_until(p->next_in_band_update);
        in_band_wait(p->in_band);
    }
    if (p->fail_open) {
        fail_open_wait(p->fail_open);
    }
    if (p->sflow) {
        ofproto_sflow_wait(p->sflow);
    }
    HMAP_FOR_EACH (ofservice, node, &p->services) {
        pvconn_wait(ofservice->pvconn);
    }
    for (i = 0; i < p->n_snoops; i++) {
        pvconn_wait(p->snoops[i]);
    }
}

void
ofproto_revalidate(struct ofproto *ofproto, tag_type tag)
{
    wdp_revalidate(ofproto->wdp, tag);
}

void
ofproto_revalidate_all(struct ofproto *ofproto)
{
    wdp_revalidate_all(ofproto->wdp);
}

bool
ofproto_is_alive(const struct ofproto *p)
{
    return !hmap_is_empty(&p->controllers);
}

int
ofproto_send_packet(struct ofproto *p, const flow_t *flow,
                    const union ofp_action *actions, size_t n_actions,
                    const struct ofpbuf *packet)
{
    /* XXX Should we translate the wdp_execute() errno value into an OpenFlow
     * error code? */
    wdp_execute(p->wdp, flow->in_port, actions, n_actions, packet);
    return 0;
}

/* Intended for used by ofproto clients and ofproto submodules to add flows to
 * the flow table. */
void
ofproto_add_flow(struct ofproto *p, const flow_t *flow,
                 const union ofp_action *actions, size_t n_actions,
                 int idle_timeout)
{
    struct wdp_flow_put put;
    struct wdp_rule *rule;

    put.flags = WDP_PUT_CREATE | WDP_PUT_MODIFY | WDP_PUT_ALL;
    put.flow = flow;
    put.actions = actions;
    put.n_actions = n_actions;
    put.idle_timeout = idle_timeout;
    put.hard_timeout = 0;
    put.ofp_table_id = 0xff;
    put.cookie = htonll(0);
    put.xid = htonl(0);

    if (!wdp_flow_put(p->wdp, &put, NULL, &rule)) {
        ofproto_rule_init(rule);
    }
}

/* Intended for used by ofproto clients and ofproto submodules to delete flows
 * that they earlier added to the flow table. */
void
ofproto_delete_flow(struct ofproto *ofproto, const flow_t *flow)
{
    struct wdp_rule *rule = wdp_flow_get(ofproto->wdp, flow, UINT_MAX);
    if (rule) {
        delete_flow(ofproto, rule, OFPRR_DELETE);
    }
}

void
ofproto_flush_flows(struct ofproto *ofproto)
{
    COVERAGE_INC(ofproto_flush);
    wdp_flow_flush(ofproto->wdp);
    if (ofproto->in_band) {
        in_band_flushed(ofproto->in_band);
    }
    if (ofproto->fail_open) {
        fail_open_flushed(ofproto->fail_open);
    }
}

static struct ofconn *
ofconn_create(struct ofproto *p, struct rconn *rconn, enum ofconn_type type)
{
    struct ofconn *ofconn = xzalloc(sizeof *ofconn);
    ofconn->ofproto = p;
    list_push_back(&p->all_conns, &ofconn->node);
    ofconn->rconn = rconn;
    ofconn->type = type;
    ofconn->role = NX_ROLE_OTHER;
    ofconn->packet_in_counter = rconn_packet_counter_create ();
    ofconn->pktbuf = NULL;
    ofconn->miss_send_len = 0;
    ofconn->reply_counter = rconn_packet_counter_create ();
    return ofconn;
}

static void
ofconn_destroy(struct ofconn *ofconn)
{
    if (ofconn->type == OFCONN_PRIMARY) {
        hmap_remove(&ofconn->ofproto->controllers, &ofconn->hmap_node);
    }
    discovery_destroy(ofconn->discovery);

    list_remove(&ofconn->node);
    switch_status_unregister(ofconn->ss);
    rconn_destroy(ofconn->rconn);
    rconn_packet_counter_destroy(ofconn->packet_in_counter);
    rconn_packet_counter_destroy(ofconn->reply_counter);
    pktbuf_destroy(ofconn->pktbuf);
    free(ofconn);
}

static void
ofconn_run(struct ofconn *ofconn, struct ofproto *p)
{
    int iteration;
    size_t i;

    if (ofconn->discovery) {
        char *controller_name;
        if (rconn_is_connectivity_questionable(ofconn->rconn)) {
            discovery_question_connectivity(ofconn->discovery);
        }
        if (discovery_run(ofconn->discovery, &controller_name)) {
            if (controller_name) {
                char *ofconn_name = ofconn_make_name(p, controller_name);
                rconn_connect(ofconn->rconn, controller_name, ofconn_name);
                free(ofconn_name);
            } else {
                rconn_disconnect(ofconn->rconn);
            }
        }
    }

    for (i = 0; i < N_SCHEDULERS; i++) {
        pinsched_run(ofconn->schedulers[i], do_send_packet_in, ofconn);
    }

    rconn_run(ofconn->rconn);

    if (rconn_packet_counter_read (ofconn->reply_counter) < OFCONN_REPLY_MAX) {
        /* Limit the number of iterations to prevent other tasks from
         * starving. */
        for (iteration = 0; iteration < 50; iteration++) {
            struct ofpbuf *of_msg = rconn_recv(ofconn->rconn);
            if (!of_msg) {
                break;
            }
            if (p->fail_open) {
                fail_open_maybe_recover(p->fail_open);
            }
            handle_openflow(ofconn, p, of_msg);
            ofpbuf_delete(of_msg);
        }
    }

    if (!ofconn->discovery && !rconn_is_alive(ofconn->rconn)) {
        ofconn_destroy(ofconn);
    }
}

static void
ofconn_wait(struct ofconn *ofconn)
{
    int i;

    if (ofconn->discovery) {
        discovery_wait(ofconn->discovery);
    }
    for (i = 0; i < N_SCHEDULERS; i++) {
        pinsched_wait(ofconn->schedulers[i]);
    }
    rconn_run_wait(ofconn->rconn);
    if (rconn_packet_counter_read (ofconn->reply_counter) < OFCONN_REPLY_MAX) {
        rconn_recv_wait(ofconn->rconn);
    } else {
        COVERAGE_INC(ofproto_ofconn_stuck);
    }
}

/* Returns true if 'ofconn' should receive asynchronous messages. */
static bool
ofconn_receives_async_msgs(const struct ofconn *ofconn)
{
    if (ofconn->type == OFCONN_PRIMARY) {
        /* Primary controllers always get asynchronous messages unless they
         * have configured themselves as "slaves".  */
        return ofconn->role != NX_ROLE_SLAVE;
    } else {
        /* Service connections don't get asynchronous messages unless they have
         * explicitly asked for them by setting a nonzero miss send length. */
        return ofconn->miss_send_len > 0;
    }
}

/* Returns a human-readable name for an OpenFlow connection between 'ofproto'
 * and 'target', suitable for use in log messages for identifying the
 * connection.
 *
 * The name is dynamically allocated.  The caller should free it (with free())
 * when it is no longer needed. */
static char *
ofconn_make_name(const struct ofproto *ofproto, const char *target)
{
    return xasprintf("%s<->%s", wdp_base_name(ofproto->wdp), target);
}

static void
ofconn_set_rate_limit(struct ofconn *ofconn, int rate, int burst)
{
    int i;

    for (i = 0; i < N_SCHEDULERS; i++) {
        struct pinsched **s = &ofconn->schedulers[i];

        if (rate > 0) {
            if (!*s) {
                *s = pinsched_create(rate, burst,
                                     ofconn->ofproto->switch_status);
            } else {
                pinsched_set_limits(*s, rate, burst);
            }
        } else {
            pinsched_destroy(*s);
            *s = NULL;
        }
    }
}

static void
ofservice_reconfigure(struct ofservice *ofservice,
                      const struct ofproto_controller *c)
{
    ofservice->probe_interval = c->probe_interval;
    ofservice->rate_limit = c->rate_limit;
    ofservice->burst_limit = c->burst_limit;
}

/* Creates a new ofservice in 'ofproto'.  Returns 0 if successful, otherwise a
 * positive errno value. */
static int
ofservice_create(struct ofproto *ofproto, const struct ofproto_controller *c)
{
    struct ofservice *ofservice;
    struct pvconn *pvconn;
    int error;

    error = pvconn_open(c->target, &pvconn);
    if (error) {
        return error;
    }

    ofservice = xzalloc(sizeof *ofservice);
    hmap_insert(&ofproto->services, &ofservice->node,
                hash_string(c->target, 0));
    ofservice->pvconn = pvconn;

    ofservice_reconfigure(ofservice, c);

    return 0;
}

static void
ofservice_destroy(struct ofproto *ofproto, struct ofservice *ofservice)
{
    hmap_remove(&ofproto->services, &ofservice->node);
    pvconn_close(ofservice->pvconn);
    free(ofservice);
}

/* Finds and returns the ofservice within 'ofproto' that has the given
 * 'target', or a null pointer if none exists. */
static struct ofservice *
ofservice_lookup(struct ofproto *ofproto, const char *target)
{
    struct ofservice *ofservice;

    HMAP_FOR_EACH_WITH_HASH (ofservice, node, hash_string(target, 0),
                             &ofproto->services) {
        if (!strcmp(pvconn_get_name(ofservice->pvconn), target)) {
            return ofservice;
        }
    }
    return NULL;
}

static bool
rule_has_out_port(const struct wdp_rule *rule, uint16_t out_port)
{
    const union ofp_action *oa;
    struct actions_iterator i;

    if (out_port == htons(OFPP_NONE)) {
        return true;
    }
    for (oa = actions_first(&i, rule->actions, rule->n_actions); oa;
         oa = actions_next(&i)) {
        if (action_outputs_to_port(oa, out_port)) {
            return true;
        }
    }
    return false;
}

static void
queue_tx(struct ofpbuf *msg, const struct ofconn *ofconn,
         struct rconn_packet_counter *counter)
{
    update_openflow_length(msg);
    if (rconn_send(ofconn->rconn, msg, counter)) {
        ofpbuf_delete(msg);
    }
}

static void
send_error_oh(const struct ofconn *ofconn, const struct ofp_header *oh,
              int error)
{
    struct ofpbuf *buf = make_ofp_error_msg(error, oh);
    if (buf) {
        COVERAGE_INC(ofproto_error);
        queue_tx(buf, ofconn, ofconn->reply_counter);
    }
}

static int
handle_echo_request(struct ofconn *ofconn, struct ofp_header *oh)
{
    struct ofp_header *rq = oh;
    queue_tx(make_echo_reply(rq), ofconn, ofconn->reply_counter);
    return 0;
}

static int
handle_features_request(struct ofproto *p, struct ofconn *ofconn,
                        struct ofp_header *oh)
{
    struct ofpbuf *features;
    int error;

    error = wdp_get_features(p->wdp, &features);
    if (!error) {
        struct ofp_switch_features *osf = features->data;

        update_openflow_length(features);
        osf->header.version = OFP_VERSION;
        osf->header.type = OFPT_FEATURES_REPLY;
        osf->header.xid = oh->xid;

        osf->datapath_id = htonll(p->datapath_id);
        osf->n_buffers = htonl(pktbuf_capacity());
        memset(osf->pad, 0, sizeof osf->pad);

        /* Turn on capabilities implemented by ofproto. */
        osf->capabilities |= htonl(OFPC_FLOW_STATS | OFPC_TABLE_STATS |
                                   OFPC_PORT_STATS);

        queue_tx(features, ofconn, ofconn->reply_counter);
    }
    return error;
}

static int
handle_get_config_request(struct ofproto *p, struct ofconn *ofconn,
                          struct ofp_header *oh)
{
    struct ofpbuf *buf;
    struct ofp_switch_config *osc;
    uint16_t flags;
    bool drop_frags;

    /* Figure out flags. */
    wdp_get_drop_frags(p->wdp, &drop_frags);
    flags = drop_frags ? OFPC_FRAG_DROP : OFPC_FRAG_NORMAL;

    /* Send reply. */
    osc = make_openflow_xid(sizeof *osc, OFPT_GET_CONFIG_REPLY, oh->xid, &buf);
    osc->flags = htons(flags);
    osc->miss_send_len = htons(ofconn->miss_send_len);
    queue_tx(buf, ofconn, ofconn->reply_counter);

    return 0;
}

static int
handle_set_config(struct ofproto *p, struct ofconn *ofconn,
                  struct ofp_switch_config *osc)
{
    uint16_t flags;
    int error;

    error = check_ofp_message(&osc->header, OFPT_SET_CONFIG, sizeof *osc);
    if (error) {
        return error;
    }
    flags = ntohs(osc->flags);

    if (ofconn->type == OFCONN_PRIMARY && ofconn->role != NX_ROLE_SLAVE) {
        switch (flags & OFPC_FRAG_MASK) {
        case OFPC_FRAG_NORMAL:
            wdp_set_drop_frags(p->wdp, false);
            break;
        case OFPC_FRAG_DROP:
            wdp_set_drop_frags(p->wdp, true);
            break;
        default:
            VLOG_WARN_RL(&rl, "requested bad fragment mode (flags=%"PRIx16")",
                         osc->flags);
            break;
        }
    }

    ofconn->miss_send_len = ntohs(osc->miss_send_len);

    return 0;
}

/* Checks whether 'ofconn' is a slave controller.  If so, returns an OpenFlow
 * error message code (composed with ofp_mkerr()) for the caller to propagate
 * upward.  Otherwise, returns 0.
 *
 * 'oh' is used to make log messages more informative. */
static int
reject_slave_controller(struct ofconn *ofconn, const struct ofp_header *oh)
{
    if (ofconn->type == OFCONN_PRIMARY && ofconn->role == NX_ROLE_SLAVE) {
        static struct vlog_rate_limit perm_rl = VLOG_RATE_LIMIT_INIT(1, 5);
        char *type_name;

        type_name = ofp_message_type_to_string(oh->type);
        VLOG_WARN_RL(&perm_rl, "rejecting %s message from slave controller",
                     type_name);
        free(type_name);

        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_EPERM);
    } else {
        return 0;
    }
}

static int
handle_packet_out(struct ofproto *p, struct ofconn *ofconn,
                  struct ofp_header *oh)
{
    struct ofp_packet_out *opo;
    struct ofpbuf payload, *buffer;
    struct ofp_action_header *actions;
    int n_actions;
    uint16_t in_port;
    flow_t flow;
    int error;

    error = reject_slave_controller(ofconn, oh);
    if (error) {
        return error;
    }

    error = check_ofp_packet_out(oh, &payload, &n_actions, p->max_ports);
    if (error) {
        return error;
    }
    opo = (struct ofp_packet_out *) oh;
    actions = opo->actions;

    COVERAGE_INC(ofproto_packet_out);
    if (opo->buffer_id != htonl(UINT32_MAX)) {
        error = pktbuf_retrieve(ofconn->pktbuf, ntohl(opo->buffer_id),
                                &buffer, &in_port);
        if (error || !buffer) {
            return error;
        }
        payload = *buffer;
    } else {
        buffer = NULL;
    }

    flow_extract(&payload, 0, ntohs(opo->in_port), &flow);
    wdp_execute(p->wdp, flow.in_port, (const union ofp_action *) actions,
                n_actions, &payload);
    ofpbuf_delete(buffer);

    return 0;
}

static int
handle_port_mod(struct ofproto *p, struct ofconn *ofconn,
                struct ofp_header *oh)
{
    const struct ofp_port_mod *opm;
    struct wdp_port port;
    int error;

    error = reject_slave_controller(ofconn, oh);
    if (error) {
        return error;
    }
    error = check_ofp_message(oh, OFPT_PORT_MOD, sizeof *opm);
    if (error) {
        return error;
    }
    opm = (struct ofp_port_mod *) oh;

    if (wdp_port_query_by_number(p->wdp, ntohs(opm->port_no), &port)) {
        error = ofp_mkerr(OFPET_PORT_MOD_FAILED, OFPPMFC_BAD_PORT);
    } else if (memcmp(port.opp.hw_addr, opm->hw_addr, OFP_ETH_ALEN)) {
        error = ofp_mkerr(OFPET_PORT_MOD_FAILED, OFPPMFC_BAD_HW_ADDR);
    } else {
        uint32_t mask, new_config;

        mask = ntohl(opm->mask) & (OFPPC_PORT_DOWN | OFPPC_NO_STP
                                   | OFPPC_NO_RECV | OFPPC_NO_RECV_STP
                                   | OFPPC_NO_FLOOD | OFPPC_NO_FWD
                                   | OFPPC_NO_PACKET_IN);
        new_config = (port.opp.config & ~mask) | (ntohl(opm->config) & mask);
        if (new_config != port.opp.config) {
            error = wdp_port_set_config(p->wdp, ntohs(opm->port_no),
                                        new_config);
        }
        if (opm->advertise) {
            netdev_set_advertisements(port.netdev, ntohl(opm->advertise));
        }
    }
    wdp_port_free(&port);

    return error;
}

static struct ofpbuf *
make_stats_reply(uint32_t xid, uint16_t type, size_t body_len)
{
    struct ofp_stats_reply *osr;
    struct ofpbuf *msg;

    msg = ofpbuf_new(MIN(sizeof *osr + body_len, UINT16_MAX));
    osr = put_openflow_xid(sizeof *osr, OFPT_STATS_REPLY, xid, msg);
    osr->type = type;
    osr->flags = htons(0);
    return msg;
}

static struct ofpbuf *
start_stats_reply(const struct ofp_stats_request *request, size_t body_len)
{
    return make_stats_reply(request->header.xid, request->type, body_len);
}

static void *
append_stats_reply(size_t nbytes, struct ofconn *ofconn, struct ofpbuf **msgp)
{
    struct ofpbuf *msg = *msgp;
    assert(nbytes <= UINT16_MAX - sizeof(struct ofp_stats_reply));
    if (nbytes + msg->size > UINT16_MAX) {
        struct ofp_stats_reply *reply = msg->data;
        reply->flags = htons(OFPSF_REPLY_MORE);
        *msgp = make_stats_reply(reply->header.xid, reply->type, nbytes);
        queue_tx(msg, ofconn, ofconn->reply_counter);
    }
    return ofpbuf_put_uninit(*msgp, nbytes);
}

static int
handle_desc_stats_request(struct ofproto *p, struct ofconn *ofconn,
                           struct ofp_stats_request *request)
{
    struct ofp_desc_stats *ods;
    struct ofpbuf *msg;

    msg = start_stats_reply(request, sizeof *ods);
    ods = append_stats_reply(sizeof *ods, ofconn, &msg);
    memset(ods, 0, sizeof *ods);
    ovs_strlcpy(ods->mfr_desc, p->mfr_desc, sizeof ods->mfr_desc);
    ovs_strlcpy(ods->hw_desc, p->hw_desc, sizeof ods->hw_desc);
    ovs_strlcpy(ods->sw_desc, p->sw_desc, sizeof ods->sw_desc);
    ovs_strlcpy(ods->serial_num, p->serial_desc, sizeof ods->serial_num);
    ovs_strlcpy(ods->dp_desc, p->dp_desc, sizeof ods->dp_desc);
    queue_tx(msg, ofconn, ofconn->reply_counter);

    return 0;
}

static int
handle_table_stats_request(struct ofproto *p, struct ofconn *ofconn,
                           struct ofp_stats_request *request)
{
    struct ofpbuf *msg;
    int error;

    msg = start_stats_reply(request, sizeof(struct ofp_table_stats) * 3);
    error = wdp_get_table_stats(p->wdp, msg);
    if (!error) {
        queue_tx(msg, ofconn, ofconn->reply_counter);
    } else {
        ofpbuf_delete(msg);
    }
    return error;
}

static void
append_port_stat(struct wdp_port *port, struct ofconn *ofconn,
                 struct ofpbuf **msgp)
{
    struct netdev_stats stats;
    struct ofp_port_stats *ops;

    /* Intentionally ignore return value, since errors will set
     * 'stats' to all-1s, which is correct for OpenFlow, and
     * netdev_get_stats() will log errors. */
    netdev_get_stats(port->netdev, &stats);

    ops = append_stats_reply(sizeof *ops, ofconn, msgp);
    ops->port_no = htons(port->opp.port_no);
    memset(ops->pad, 0, sizeof ops->pad);
    ops->rx_packets = htonll(stats.rx_packets);
    ops->tx_packets = htonll(stats.tx_packets);
    ops->rx_bytes = htonll(stats.rx_bytes);
    ops->tx_bytes = htonll(stats.tx_bytes);
    ops->rx_dropped = htonll(stats.rx_dropped);
    ops->tx_dropped = htonll(stats.tx_dropped);
    ops->rx_errors = htonll(stats.rx_errors);
    ops->tx_errors = htonll(stats.tx_errors);
    ops->rx_frame_err = htonll(stats.rx_frame_errors);
    ops->rx_over_err = htonll(stats.rx_over_errors);
    ops->rx_crc_err = htonll(stats.rx_crc_errors);
    ops->collisions = htonll(stats.collisions);
}

static int
handle_port_stats_request(struct ofproto *p, struct ofconn *ofconn,
                          struct ofp_stats_request *osr,
                          size_t arg_size)
{
    struct ofp_port_stats_request *psr;
    struct ofp_port_stats *ops;
    struct ofpbuf *msg;

    if (arg_size != sizeof *psr) {
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }
    psr = (struct ofp_port_stats_request *) osr->body;

    msg = start_stats_reply(osr, sizeof *ops * 16);
    if (psr->port_no != htons(OFPP_NONE)) {
        struct wdp_port port;

        if (!wdp_port_query_by_number(p->wdp, ntohs(psr->port_no), &port)) {
            append_port_stat(&port, ofconn, &msg);
            wdp_port_free(&port);
        }
    } else {
        struct wdp_port *ports;
        size_t n_ports;
        size_t i;

        wdp_port_list(p->wdp, &ports, &n_ports);
        for (i = 0; i < n_ports; i++) {
            append_port_stat(&ports[i], ofconn, &msg);
        }
        wdp_port_array_free(ports, n_ports);
    }

    queue_tx(msg, ofconn, ofconn->reply_counter);
    return 0;
}

struct flow_stats_cbdata {
    struct ofproto *ofproto;
    struct ofconn *ofconn;
    uint16_t out_port;
    struct ofpbuf *msg;
};

/* Obtains statistic counters for 'rule' within 'p' and stores them into
 * '*packet_countp' and '*byte_countp'.  If 'rule' is a wildcarded rule, the
 * returned statistic include statistics for all of 'rule''s subrules. */
static void
query_stats(struct ofproto *p, struct wdp_rule *rule,
            uint64_t *packet_countp, uint64_t *byte_countp)
{
    struct wdp_flow_stats stats;

    if (!wdp_flow_get_stats(p->wdp, rule, &stats)) {
        *packet_countp = stats.n_packets;
        *byte_countp = stats.n_bytes;
    } else {
        *packet_countp = 0;
        *byte_countp = 0;
    }
}

static int
flow_stats_cb(struct wdp_rule *rule, void *cbdata_)
{
    struct flow_stats_cbdata *cbdata = cbdata_;
    struct ofp_flow_stats *ofs;
    uint64_t packet_count, byte_count;
    size_t act_len, len;
    long long int tdiff = time_msec() - rule->created;
    uint32_t sec = tdiff / 1000;
    uint32_t msec = tdiff - (sec * 1000);

    if (rule_is_hidden(rule)
        || !rule_has_out_port(rule, cbdata->out_port)) {
        return 0;
    }

    act_len = sizeof *rule->actions * rule->n_actions;
    len = offsetof(struct ofp_flow_stats, actions) + act_len;

    query_stats(cbdata->ofproto, rule, &packet_count, &byte_count);

    ofs = append_stats_reply(len, cbdata->ofconn, &cbdata->msg);
    ofs->length = htons(len);
    ofs->table_id = rule->ofp_table_id;
    ofs->pad = 0;
    flow_to_match(&rule->cr.flow, cbdata->ofproto->tun_id_from_cookie,
                  &ofs->match);
    ofs->duration_sec = htonl(sec);
    ofs->duration_nsec = htonl(msec * 1000000);
    ofs->cookie = ofproto_rule_cast(rule)->flow_cookie;
    ofs->priority = htons(rule->cr.flow.priority);
    ofs->idle_timeout = htons(rule->idle_timeout);
    ofs->hard_timeout = htons(rule->hard_timeout);
    memset(ofs->pad2, 0, sizeof ofs->pad2);
    ofs->packet_count = htonll(packet_count);
    ofs->byte_count = htonll(byte_count);
    memcpy(ofs->actions, rule->actions, act_len);

    return 0;
}

static unsigned int
table_id_to_include(uint8_t table_id)
{
    return (table_id == 0xff ? UINT_MAX
            : table_id < 32 ? 1u << table_id
            : 0);
}

static unsigned int
flow_mod_table_id(const struct ofconn *ofconn, const struct ofp_flow_mod *ofm)
{
    return ofconn->flow_mod_table_id ? ntohs(ofm->command) >> 8 : 0xff;
}

static int
handle_flow_stats_request(struct ofproto *p, struct ofconn *ofconn,
                          const struct ofp_stats_request *osr,
                          size_t arg_size)
{
    struct ofp_flow_stats_request *fsr;
    struct flow_stats_cbdata cbdata;
    flow_t target;

    if (arg_size != sizeof *fsr) {
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }
    fsr = (struct ofp_flow_stats_request *) osr->body;

    COVERAGE_INC(ofproto_flows_req);
    cbdata.ofproto = p;
    cbdata.ofconn = ofconn;
    cbdata.out_port = fsr->out_port;
    cbdata.msg = start_stats_reply(osr, 1024);
    flow_from_match(&fsr->match, 0, false, 0, &target);
    wdp_flow_for_each_match(p->wdp, &target,
                            table_id_to_include(fsr->table_id),
                            flow_stats_cb, &cbdata);
    queue_tx(cbdata.msg, ofconn, ofconn->reply_counter);
    return 0;
}

struct flow_stats_ds_cbdata {
    struct ofproto *ofproto;
    struct ds *results;
};

static int
flow_stats_ds_cb(struct wdp_rule *rule, void *cbdata_)
{
    struct flow_stats_ds_cbdata *cbdata = cbdata_;
    struct ds *results = cbdata->results;
    struct ofp_match match;
    uint64_t packet_count, byte_count;
    size_t act_len = sizeof *rule->actions * rule->n_actions;

    query_stats(cbdata->ofproto, rule, &packet_count, &byte_count);
    flow_to_match(&rule->cr.flow, cbdata->ofproto->tun_id_from_cookie,
                  &match);

    ds_put_format(results, "duration=%llds, ",
                  (time_msec() - rule->created) / 1000);
    ds_put_format(results, "priority=%u, ", rule->cr.flow.priority);
    ds_put_format(results, "n_packets=%"PRIu64", ", packet_count);
    ds_put_format(results, "n_bytes=%"PRIu64", ", byte_count);
    ofp_print_match(results, &match, true);
    ofp_print_actions(results, &rule->actions->header, act_len);
    ds_put_cstr(results, "\n");

    return 0;
}

/* Adds a pretty-printed description of all flows to 'results', including
 * those marked hidden by secchan (e.g., by in-band control). */
void
ofproto_get_all_flows(struct ofproto *p, struct ds *results)
{
    struct flow_stats_ds_cbdata cbdata;
    struct ofp_match match;
    flow_t target;

    memset(&match, 0, sizeof match);
    match.wildcards = htonl(OVSFW_ALL);

    cbdata.ofproto = p;
    cbdata.results = results;

    flow_from_match(&match, 0, false, 0, &target);
    wdp_flow_for_each_match(p->wdp, &target, UINT_MAX,
                            flow_stats_ds_cb, &cbdata);
}

struct aggregate_stats_cbdata {
    struct ofproto *ofproto;
    uint16_t out_port;
    uint64_t packet_count;
    uint64_t byte_count;
    uint32_t n_flows;
};

static int
aggregate_stats_cb(struct wdp_rule *rule, void *cbdata_)
{
    struct aggregate_stats_cbdata *cbdata = cbdata_;
    uint64_t packet_count, byte_count;

    if (rule_is_hidden(rule) || !rule_has_out_port(rule, cbdata->out_port)) {
        return 0;
    }

    query_stats(cbdata->ofproto, rule, &packet_count, &byte_count);

    cbdata->packet_count += packet_count;
    cbdata->byte_count += byte_count;
    cbdata->n_flows++;

    return 0;
}

static int
handle_aggregate_stats_request(struct ofproto *p, struct ofconn *ofconn,
                               const struct ofp_stats_request *osr,
                               size_t arg_size)
{
    struct ofp_aggregate_stats_request *asr;
    struct ofp_aggregate_stats_reply *reply;
    struct aggregate_stats_cbdata cbdata;
    struct ofpbuf *msg;
    flow_t target;

    if (arg_size != sizeof *asr) {
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }
    asr = (struct ofp_aggregate_stats_request *) osr->body;

    COVERAGE_INC(ofproto_agg_request);
    cbdata.ofproto = p;
    cbdata.out_port = asr->out_port;
    cbdata.packet_count = 0;
    cbdata.byte_count = 0;
    cbdata.n_flows = 0;
    flow_from_match(&asr->match, 0, false, 0, &target);
    wdp_flow_for_each_match(p->wdp, &target,
                            table_id_to_include(asr->table_id),
                            aggregate_stats_cb, &cbdata);

    msg = start_stats_reply(osr, sizeof *reply);
    reply = append_stats_reply(sizeof *reply, ofconn, &msg);
    reply->flow_count = htonl(cbdata.n_flows);
    reply->packet_count = htonll(cbdata.packet_count);
    reply->byte_count = htonll(cbdata.byte_count);
    queue_tx(msg, ofconn, ofconn->reply_counter);
    return 0;
}

struct queue_stats_cbdata {
    struct ofconn *ofconn;
    struct wdp_port *wdp_port;
    struct ofpbuf *msg;
};

static void
put_queue_stats(struct queue_stats_cbdata *cbdata, uint32_t queue_id,
                const struct netdev_queue_stats *stats)
{
    struct ofp_queue_stats *reply;

    reply = append_stats_reply(sizeof *reply, cbdata->ofconn, &cbdata->msg);
    reply->port_no = htons(cbdata->wdp_port->opp.port_no);
    memset(reply->pad, 0, sizeof reply->pad);
    reply->queue_id = htonl(queue_id);
    reply->tx_bytes = htonll(stats->tx_bytes);
    reply->tx_packets = htonll(stats->tx_packets);
    reply->tx_errors = htonll(stats->tx_errors);
}

static void
handle_queue_stats_dump_cb(uint32_t queue_id,
                           struct netdev_queue_stats *stats,
                           void *cbdata_)
{
    struct queue_stats_cbdata *cbdata = cbdata_;

    put_queue_stats(cbdata, queue_id, stats);
}

static void
handle_queue_stats_for_port(struct wdp_port *port, uint32_t queue_id,
                            struct queue_stats_cbdata *cbdata)
{
    cbdata->wdp_port = port;
    if (queue_id == OFPQ_ALL) {
        netdev_dump_queue_stats(port->netdev,
                                handle_queue_stats_dump_cb, cbdata);
    } else {
        struct netdev_queue_stats stats;

        if (!netdev_get_queue_stats(port->netdev, queue_id, &stats)) {
            put_queue_stats(cbdata, queue_id, &stats);
        }
    }
}

static int
handle_queue_stats_request(struct ofproto *ofproto, struct ofconn *ofconn,
                           const struct ofp_stats_request *osr,
                           size_t arg_size)
{
    struct ofp_queue_stats_request *qsr;
    struct queue_stats_cbdata cbdata;
    unsigned int port_no;
    uint32_t queue_id;

    if (arg_size != sizeof *qsr) {
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }
    qsr = (struct ofp_queue_stats_request *) osr->body;

    COVERAGE_INC(ofproto_queue_req);

    cbdata.ofconn = ofconn;
    cbdata.msg = start_stats_reply(osr, 128);

    port_no = ntohs(qsr->port_no);
    queue_id = ntohl(qsr->queue_id);
    if (port_no == OFPP_ALL) {
        struct wdp_port *ports;
        size_t n_ports, i;

        wdp_port_list(ofproto->wdp, &ports, &n_ports);
        /* XXX deal with wdp_port_list() errors */
        for (i = 0; i < n_ports; i++) {
            handle_queue_stats_for_port(&ports[i], queue_id, &cbdata);
        }
        wdp_port_array_free(ports, n_ports);
    } else if (port_no < ofproto->max_ports) {
        struct wdp_port port;
        int error;

        error = wdp_port_query_by_number(ofproto->wdp, port_no, &port);
        if (!error) {
            handle_queue_stats_for_port(&port, queue_id, &cbdata);
        } else {
            /* XXX deal with wdp_port_query_by_number() errors */
        }
        wdp_port_free(&port);
    } else {
        ofpbuf_delete(cbdata.msg);
        return ofp_mkerr(OFPET_QUEUE_OP_FAILED, OFPQOFC_BAD_PORT);
    }
    queue_tx(cbdata.msg, ofconn, ofconn->reply_counter);

    return 0;
}

static int
handle_stats_request(struct ofproto *p, struct ofconn *ofconn,
                     struct ofp_header *oh)
{
    struct ofp_stats_request *osr;
    size_t arg_size;
    int error;

    error = check_ofp_message_array(oh, OFPT_STATS_REQUEST, sizeof *osr,
                                    1, &arg_size);
    if (error) {
        return error;
    }
    osr = (struct ofp_stats_request *) oh;

    switch (ntohs(osr->type)) {
    case OFPST_DESC:
        return handle_desc_stats_request(p, ofconn, osr);

    case OFPST_FLOW:
        return handle_flow_stats_request(p, ofconn, osr, arg_size);

    case OFPST_AGGREGATE:
        return handle_aggregate_stats_request(p, ofconn, osr, arg_size);

    case OFPST_TABLE:
        return handle_table_stats_request(p, ofconn, osr);

    case OFPST_PORT:
        return handle_port_stats_request(p, ofconn, osr, arg_size);

    case OFPST_QUEUE:
        return handle_queue_stats_request(p, ofconn, osr, arg_size);

    case OFPST_VENDOR:
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_VENDOR);

    default:
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_STAT);
    }
}

/* Implements OFPFC_ADD and the cases for OFPFC_MODIFY and OFPFC_MODIFY_STRICT
 * in which no matching flow already exists in the flow table.
 *
 * Adds the flow specified by 'ofm', which is followed by 'n_actions'
 * ofp_actions, to 'p''s flow table.  Returns 0 on success or an OpenFlow error
 * code as encoded by ofp_mkerr() on failure.
 *
 * 'ofconn' is used to retrieve the packet buffer specified in ofm->buffer_id,
 * if any. */
static int
add_flow(struct ofproto *p, struct ofconn *ofconn,
         const struct ofp_flow_mod *ofm, size_t n_actions)
{
    struct wdp_rule *rule;
    struct wdp_flow_put put;
    struct ofpbuf *packet;
    uint16_t in_port;
    flow_t flow;
    int error;

    flow_from_match(&ofm->match, ntohs(ofm->priority), p->tun_id_from_cookie,
                    ofm->cookie, &flow);
    if (ofm->flags & htons(OFPFF_CHECK_OVERLAP)
        && wdp_flow_overlaps(p->wdp, &flow)) {
        return ofp_mkerr(OFPET_FLOW_MOD_FAILED, OFPFMFC_OVERLAP);
    }

    put.flags = WDP_PUT_CREATE | WDP_PUT_MODIFY | WDP_PUT_ALL;
    put.flow = &flow;
    put.actions = (const union ofp_action *) ofm->actions;
    put.n_actions = n_actions;
    put.idle_timeout = ntohs(ofm->idle_timeout);
    put.hard_timeout = ntohs(ofm->hard_timeout);
    put.ofp_table_id = flow_mod_table_id(ofconn, ofm);
    put.cookie = ofm->cookie;
    put.xid = ofm->header.xid;
    error = wdp_flow_put(p->wdp, &put, NULL, &rule);
    if (error) {
        /* XXX wdp_flow_put should return OpenFlow error code. */
        return error;
    }
    ofproto_rule_init(rule);

    if (ofm->buffer_id != htonl(UINT32_MAX)) {
        error = pktbuf_retrieve(ofconn->pktbuf, ntohl(ofm->buffer_id),
                                &packet, &in_port);
        if (!error) {
            error = wdp_flow_inject(p->wdp, rule, in_port, packet);
            ofpbuf_delete(packet);
        }
    }

    return error;
}

static struct wdp_rule *
find_flow_strict(struct ofproto *p, const struct ofconn *ofconn,
                 const struct ofp_flow_mod *ofm)
{
    uint8_t table_id;
    flow_t flow;

    flow_from_match(&ofm->match, ntohs(ofm->priority),
                    p->tun_id_from_cookie, ofm->cookie, &flow);
    table_id = flow_mod_table_id(ofconn, ofm);
    return wdp_flow_get(p->wdp, &flow, table_id_to_include(table_id));
}

static int
send_buffered_packet(struct ofproto *ofproto, struct ofconn *ofconn,
                     struct wdp_rule *rule, const struct ofp_flow_mod *ofm)
{
    struct ofpbuf *packet;
    uint16_t in_port;
    int error;

    if (ofm->buffer_id == htonl(UINT32_MAX)) {
        return 0;
    }

    error = pktbuf_retrieve(ofconn->pktbuf, ntohl(ofm->buffer_id),
                            &packet, &in_port);
    if (error) {
        return error;
    }

    error = wdp_flow_inject(ofproto->wdp, rule, in_port, packet);
    ofpbuf_delete(packet);

    return error;
}

/* OFPFC_MODIFY and OFPFC_MODIFY_STRICT. */

struct modify_flows_cbdata {
    struct ofproto *ofproto;
    const struct ofp_flow_mod *ofm;
    size_t n_actions;
    struct wdp_rule *match;
};

static int modify_flow(struct ofproto *, const struct ofp_flow_mod *,
                       size_t n_actions, struct wdp_rule *)
    WARN_UNUSED_RESULT;
static int modify_flows_cb(struct wdp_rule *, void *cbdata_);

/* Implements OFPFC_ADD and OFPFC_MODIFY.  Returns 0 on success or an OpenFlow
 * error code as encoded by ofp_mkerr() on failure.
 *
 * 'ofconn' is used to retrieve the packet buffer specified in ofm->buffer_id,
 * if any. */
static int
modify_flows_loose(struct ofproto *p, struct ofconn *ofconn,
                   const struct ofp_flow_mod *ofm, size_t n_actions)
{
    struct modify_flows_cbdata cbdata;
    uint8_t table_id;
    flow_t target;
    int error;

    cbdata.ofproto = p;
    cbdata.ofm = ofm;
    cbdata.n_actions = n_actions;
    cbdata.match = NULL;

    flow_from_match(&ofm->match, 0, p->tun_id_from_cookie, ofm->cookie,
                    &target);

    table_id = flow_mod_table_id(ofconn, ofm);
    error = wdp_flow_for_each_match(p->wdp, &target,
                                    table_id_to_include(table_id),
                                    modify_flows_cb, &cbdata);
    if (error) {
        return error;
    }

    if (cbdata.match) {
        /* This credits the packet to whichever flow happened to match last.
         * That's weird.  Maybe we should do a lookup for the flow that
         * actually matches the packet?  Who knows. */
        return send_buffered_packet(p, ofconn, cbdata.match, ofm);
    } else {
        return add_flow(p, ofconn, ofm, n_actions);
    }
}

/* Implements OFPFC_MODIFY_STRICT.  Returns 0 on success or an OpenFlow error
 * code as encoded by ofp_mkerr() on failure.
 *
 * 'ofconn' is used to retrieve the packet buffer specified in ofm->buffer_id,
 * if any. */
static int
modify_flow_strict(struct ofproto *p, struct ofconn *ofconn,
                   struct ofp_flow_mod *ofm, size_t n_actions)
{
    struct wdp_rule *rule = find_flow_strict(p, ofconn, ofm);
    if (rule && !rule_is_hidden(rule)) {
        int error = modify_flow(p, ofm, n_actions, rule);
        return error ? error : send_buffered_packet(p, ofconn, rule, ofm);
    } else {
        return add_flow(p, ofconn, ofm, n_actions);
    }
}

/* Callback for modify_flows_loose(). */
static int
modify_flows_cb(struct wdp_rule *rule, void *cbdata_)
{
    struct modify_flows_cbdata *cbdata = cbdata_;

    if (!rule_is_hidden(rule)) {
        cbdata->match = rule;
        return modify_flow(cbdata->ofproto, cbdata->ofm, cbdata->n_actions,
                           rule);
    }
    return 0;
}

/* Implements core of OFPFC_MODIFY and OFPFC_MODIFY_STRICT where 'rule' has
 * been identified as a flow in 'p''s flow table to be modified, by changing
 * the rule's actions to match those in 'ofm' (which is followed by 'n_actions'
 * ofp_action[] structures). */
static int
modify_flow(struct ofproto *p, const struct ofp_flow_mod *ofm,
            size_t n_actions, struct wdp_rule *rule)
{
    const struct ofp_action_header *actions = ofm->actions;
    struct ofproto_rule *ofproto_rule = ofproto_rule_cast(rule);
    struct wdp_flow_put put;

    ofproto_rule->flow_cookie = ofm->cookie;

    /* If the actions are the same, do nothing. */
    if (n_actions == rule->n_actions
        && !memcmp(ofm->actions, rule->actions, sizeof *actions * n_actions))
    {
        return 0;
    }

    put.flags = WDP_PUT_MODIFY | WDP_PUT_ACTIONS;
    put.flow = &rule->cr.flow;
    put.actions = (const union ofp_action *) actions;
    put.n_actions = n_actions;
    put.idle_timeout = put.hard_timeout = 0;
    put.ofp_table_id = rule->ofp_table_id;
    put.cookie = ofm->cookie;
    put.xid = ofm->header.xid;
    return wdp_flow_put(p->wdp, &put, NULL, NULL);
}

/* OFPFC_DELETE implementation. */

struct delete_flows_cbdata {
    struct ofproto *ofproto;
    uint16_t out_port;
};

static int delete_flows_cb(struct wdp_rule *, void *cbdata_);
static int delete_flow_core(struct ofproto *, struct wdp_rule *,
                             uint16_t out_port);

/* Implements OFPFC_DELETE. */
static int
delete_flows_loose(struct ofproto *p, const struct ofconn *ofconn,
                   const struct ofp_flow_mod *ofm)
{
    struct delete_flows_cbdata cbdata;
    uint8_t table_id;
    flow_t target;

    cbdata.ofproto = p;
    cbdata.out_port = ofm->out_port;

    flow_from_match(&ofm->match, 0, p->tun_id_from_cookie, ofm->cookie,
                    &target);
    table_id = flow_mod_table_id(ofconn, ofm);

    return wdp_flow_for_each_match(p->wdp, &target,
                                   table_id_to_include(table_id),
                                   delete_flows_cb, &cbdata);
}

/* Implements OFPFC_DELETE_STRICT. */
static int
delete_flow_strict(struct ofproto *p, const struct ofconn *ofconn,
                   struct ofp_flow_mod *ofm)
{
    struct wdp_rule *rule = find_flow_strict(p, ofconn, ofm);
    if (rule) {
        return delete_flow_core(p, rule, ofm->out_port);
    }
    return 0;
}

/* Callback for delete_flows_loose(). */
static int
delete_flows_cb(struct wdp_rule *rule, void *cbdata_)
{
    struct delete_flows_cbdata *cbdata = cbdata_;

    return delete_flow_core(cbdata->ofproto, rule, cbdata->out_port);
}

/* Implements core of OFPFC_DELETE and OFPFC_DELETE_STRICT where 'rule' has
 * been identified as a flow to delete from 'p''s flow table, by deleting the
 * flow and sending out a OFPT_FLOW_REMOVED message to any interested
 * controller.
 *
 * Will not delete 'rule' if it is hidden.  Will delete 'rule' only if
 * 'out_port' is htons(OFPP_NONE) or if 'rule' actually outputs to the
 * specified 'out_port'. */
static int
delete_flow_core(struct ofproto *p, struct wdp_rule *rule, uint16_t out_port)
{
    if (rule_is_hidden(rule)) {
        return 0;
    }

    if (out_port != htons(OFPP_NONE) && !rule_has_out_port(rule, out_port)) {
        return 0;
    }

    return delete_flow(p, rule, OFPRR_DELETE);
}

static int
handle_flow_mod(struct ofproto *p, struct ofconn *ofconn,
                struct ofp_flow_mod *ofm)
{
    struct ofp_match orig_match;
    size_t n_actions;
    int error;

    error = reject_slave_controller(ofconn, &ofm->header);
    if (error) {
        return error;
    }
    error = check_ofp_message_array(&ofm->header, OFPT_FLOW_MOD, sizeof *ofm,
                                    sizeof *ofm->actions, &n_actions);
    if (error) {
        return error;
    }

    /* We do not support the emergency flow cache.  It will hopefully
     * get dropped from OpenFlow in the near future. */
    if (ofm->flags & htons(OFPFF_EMERG)) {
        /* There isn't a good fit for an error code, so just state that the
         * flow table is full. */
        return ofp_mkerr(OFPET_FLOW_MOD_FAILED, OFPFMFC_ALL_TABLES_FULL);
    }

    /* Normalize ofp->match.  If normalization actually changes anything, then
     * log the differences. */
    ofm->match.pad1[0] = ofm->match.pad2[0] = 0;
    orig_match = ofm->match;
    normalize_match(&ofm->match);
    if (memcmp(&ofm->match, &orig_match, sizeof orig_match)) {
        static struct vlog_rate_limit normal_rl = VLOG_RATE_LIMIT_INIT(1, 1);
        if (!VLOG_DROP_INFO(&normal_rl)) {
            char *old = ofp_match_to_literal_string(&orig_match);
            char *new = ofp_match_to_literal_string(&ofm->match);
            VLOG_INFO("%s: normalization changed ofp_match, details:",
                      rconn_get_name(ofconn->rconn));
            VLOG_INFO(" pre: %s", old);
            VLOG_INFO("post: %s", new);
            free(old);
            free(new);
        }
    }

    if (!ofm->match.wildcards) {
        ofm->priority = htons(UINT16_MAX);
    }

    error = validate_actions((const union ofp_action *) ofm->actions,
                             n_actions, p->max_ports);
    if (error) {
        return error;
    }

    if (!ofconn->flow_mod_table_id && ofm->command & htons(0xff00)) {
        static struct vlog_rate_limit table_id_rl = VLOG_RATE_LIMIT_INIT(1, 1);
        VLOG_WARN_RL(&table_id_rl, "%s: flow_mod table_id feature must be "
                     "enabled with NXT_FLOW_MOD_TABLE_ID",
                     rconn_get_name(ofconn->rconn));
        return ofp_mkerr(OFPET_FLOW_MOD_FAILED, OFPFMFC_BAD_COMMAND);
    }

    switch (ntohs(ofm->command) & 0xff) {
    case OFPFC_ADD:
        return add_flow(p, ofconn, ofm, n_actions);

    case OFPFC_MODIFY:
        return modify_flows_loose(p, ofconn, ofm, n_actions);

    case OFPFC_MODIFY_STRICT:
        return modify_flow_strict(p, ofconn, ofm, n_actions);

    case OFPFC_DELETE:
        return delete_flows_loose(p, ofconn, ofm);

    case OFPFC_DELETE_STRICT:
        return delete_flow_strict(p, ofconn, ofm);

    default:
        return ofp_mkerr(OFPET_FLOW_MOD_FAILED, OFPFMFC_BAD_COMMAND);
    }
}

static int
handle_tun_id_from_cookie(struct ofproto *p, struct nxt_tun_id_cookie *msg)
{
    int error;

    error = check_ofp_message(&msg->header, OFPT_VENDOR, sizeof *msg);
    if (error) {
        return error;
    }

    p->tun_id_from_cookie = !!msg->set;
    return 0;
}

static int
handle_flow_mod_table_id(struct ofconn *ofconn,
                         struct nxt_flow_mod_table_id *msg)
{
    int error;

    error = check_ofp_message(&msg->header, OFPT_VENDOR, sizeof *msg);
    if (error) {
        return error;
    }

    ofconn->flow_mod_table_id = !!msg->set;
    return 0;
}

static int
handle_role_request(struct ofproto *ofproto,
                    struct ofconn *ofconn, struct nicira_header *msg)
{
    struct nx_role_request *nrr;
    struct nx_role_request *reply;
    struct ofpbuf *buf;
    uint32_t role;

    if (ntohs(msg->header.length) != sizeof *nrr) {
        VLOG_WARN_RL(&rl, "received role request of length %u (expected %zu)",
                     ntohs(msg->header.length), sizeof *nrr);
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }
    nrr = (struct nx_role_request *) msg;

    if (ofconn->type != OFCONN_PRIMARY) {
        VLOG_WARN_RL(&rl, "ignoring role request on non-controller "
                     "connection");
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_EPERM);
    }

    role = ntohl(nrr->role);
    if (role != NX_ROLE_OTHER && role != NX_ROLE_MASTER
        && role != NX_ROLE_SLAVE) {
        VLOG_WARN_RL(&rl, "received request for unknown role %"PRIu32, role);

        /* There's no good error code for this. */
        return ofp_mkerr(OFPET_BAD_REQUEST, -1);
    }

    if (role == NX_ROLE_MASTER) {
        struct ofconn *other;

        HMAP_FOR_EACH (other, hmap_node, &ofproto->controllers) {
            if (other->role == NX_ROLE_MASTER) {
                other->role = NX_ROLE_SLAVE;
            }
        }
    }
    ofconn->role = role;

    reply = make_openflow_xid(sizeof *reply, OFPT_VENDOR, msg->header.xid,
                              &buf);
    reply->nxh.vendor = htonl(NX_VENDOR_ID);
    reply->nxh.subtype = htonl(NXT_ROLE_REPLY);
    reply->role = htonl(role);
    queue_tx(buf, ofconn, ofconn->reply_counter);

    return 0;
}

static int
handle_vendor(struct ofproto *p, struct ofconn *ofconn, void *msg)
{
    struct ofp_vendor_header *ovh = msg;
    struct nicira_header *nh;

    if (ntohs(ovh->header.length) < sizeof(struct ofp_vendor_header)) {
        VLOG_WARN_RL(&rl, "received vendor message of length %u "
                          "(expected at least %zu)",
                   ntohs(ovh->header.length), sizeof(struct ofp_vendor_header));
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }
    if (ovh->vendor != htonl(NX_VENDOR_ID)) {
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_VENDOR);
    }
    if (ntohs(ovh->header.length) < sizeof(struct nicira_header)) {
        VLOG_WARN_RL(&rl, "received Nicira vendor message of length %u "
                          "(expected at least %zu)",
                     ntohs(ovh->header.length), sizeof(struct nicira_header));
        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
    }

    nh = msg;
    switch (ntohl(nh->subtype)) {
    case NXT_STATUS_REQUEST:
        return switch_status_handle_request(p->switch_status, ofconn->rconn,
                                            msg);

    case NXT_TUN_ID_FROM_COOKIE:
        return handle_tun_id_from_cookie(p, msg);

    case NXT_FLOW_MOD_TABLE_ID:
        return handle_flow_mod_table_id(ofconn, msg);

    case NXT_ROLE_REQUEST:
        return handle_role_request(p, ofconn, msg);
    }

    return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_SUBTYPE);
}

static int
handle_barrier_request(struct ofconn *ofconn, struct ofp_header *oh)
{
    struct ofp_header *ob;
    struct ofpbuf *buf;

    /* Currently, everything executes synchronously, so we can just
     * immediately send the barrier reply. */
    ob = make_openflow_xid(sizeof *ob, OFPT_BARRIER_REPLY, oh->xid, &buf);
    queue_tx(buf, ofconn, ofconn->reply_counter);
    return 0;
}

static void
handle_openflow(struct ofconn *ofconn, struct ofproto *p,
                struct ofpbuf *ofp_msg)
{
    struct ofp_header *oh = ofp_msg->data;
    int error;

    COVERAGE_INC(ofproto_recv_openflow);
    switch (oh->type) {
    case OFPT_ECHO_REQUEST:
        error = handle_echo_request(ofconn, oh);
        break;

    case OFPT_ECHO_REPLY:
        error = 0;
        break;

    case OFPT_FEATURES_REQUEST:
        error = handle_features_request(p, ofconn, oh);
        break;

    case OFPT_GET_CONFIG_REQUEST:
        error = handle_get_config_request(p, ofconn, oh);
        break;

    case OFPT_SET_CONFIG:
        error = handle_set_config(p, ofconn, ofp_msg->data);
        break;

    case OFPT_PACKET_OUT:
        error = handle_packet_out(p, ofconn, ofp_msg->data);
        break;

    case OFPT_PORT_MOD:
        error = handle_port_mod(p, ofconn, oh);
        break;

    case OFPT_FLOW_MOD:
        error = handle_flow_mod(p, ofconn, ofp_msg->data);
        break;

    case OFPT_STATS_REQUEST:
        error = handle_stats_request(p, ofconn, oh);
        break;

    case OFPT_VENDOR:
        error = handle_vendor(p, ofconn, ofp_msg->data);
        break;

    case OFPT_BARRIER_REQUEST:
        error = handle_barrier_request(ofconn, oh);
        break;

    default:
        if (VLOG_IS_WARN_ENABLED()) {
            char *s = ofp_to_string(oh, ntohs(oh->length), 2);
            VLOG_DBG_RL(&rl, "OpenFlow message ignored: %s", s);
            free(s);
        }
        error = ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_TYPE);
        break;
    }

    if (error) {
        send_error_oh(ofconn, ofp_msg->data, error);
    }
}

static void
handle_flow_miss(struct ofproto *p, struct wdp_packet *packet)
{
    struct wdp_rule *rule;
    flow_t flow;

    flow_extract(packet->payload, packet->tun_id, packet->in_port, &flow);
    rule = wdp_flow_match(p->wdp, &flow);
    if (!rule) {
        /* Don't send a packet-in if OFPPC_NO_PACKET_IN asserted. */
        struct wdp_port port;

        if (!wdp_port_query_by_number(p->wdp, packet->in_port, &port)) {
            bool no_packet_in = (port.opp.config & OFPPC_NO_PACKET_IN) != 0;
            wdp_port_free(&port);
            if (no_packet_in) {
                COVERAGE_INC(ofproto_no_packet_in);
                wdp_packet_destroy(packet);
                return;
            }
        } else {
            VLOG_WARN_RL(&rl, "packet-in on unknown port %"PRIu16,
                         packet->in_port);
        }

        COVERAGE_INC(ofproto_packet_in);
        send_packet_in(p, packet);
        return;
    }

    wdp_flow_inject(p->wdp, rule, packet->in_port, packet->payload);

    if (rule->cr.flow.priority == FAIL_OPEN_PRIORITY) {
        /*
         * Extra-special case for fail-open mode.
         *
         * We are in fail-open mode and the packet matched the fail-open rule,
         * but we are connected to a controller too.  We should send the packet
         * up to the controller in the hope that it will try to set up a flow
         * and thereby allow us to exit fail-open.
         *
         * See the top-level comment in fail-open.c for more information.
         */
        send_packet_in(p, packet);
    } else {
        wdp_packet_destroy(packet);
    }
}

static void
handle_wdp_packet(struct ofproto *p, struct wdp_packet *packet)
{
    switch (packet->channel) {
    case WDP_CHAN_ACTION:
        COVERAGE_INC(ofproto_ctlr_action);
        send_packet_in(p, packet);
        break;

    case WDP_CHAN_SFLOW:
        /* XXX */
        wdp_packet_destroy(packet);
        break;

    case WDP_CHAN_MISS:
        handle_flow_miss(p, packet);
        break;

    case WDP_N_CHANS:
    default:
        wdp_packet_destroy(packet);
        VLOG_WARN_RL(&rl, "received message on unexpected channel %d",
                     (int) packet->channel);
        break;
    }
}

static struct ofpbuf *
compose_flow_removed(struct ofproto *p, const struct wdp_rule *rule,
                     uint8_t reason)
{
    long long int tdiff = time_msec() - rule->created;
    uint32_t sec = tdiff / 1000;
    uint32_t msec = tdiff - (sec * 1000);
    struct ofp_flow_removed *ofr;
    struct ofpbuf *buf;

    ofr = make_openflow(sizeof *ofr, OFPT_FLOW_REMOVED, &buf);
    flow_to_match(&rule->cr.flow, p->tun_id_from_cookie, &ofr->match);
    ofr->cookie = ofproto_rule_cast(rule)->flow_cookie;
    ofr->priority = htons(rule->cr.flow.priority);
    ofr->reason = reason;
    ofr->duration_sec = htonl(sec);
    ofr->duration_nsec = htonl(msec * 1000000);
    ofr->idle_timeout = htons(rule->idle_timeout);

    return buf;
}

static int
delete_flow(struct ofproto *p, struct wdp_rule *rule, uint8_t reason)
{
    /* We limit the maximum number of queued flow expirations it by accounting
     * them under the counter for replies.  That works because preventing
     * OpenFlow requests from being processed also prevents new flows from
     * being added (and expiring).  (It also prevents processing OpenFlow
     * requests that would not add new flows, so it is imperfect.) */

    struct ofproto_rule *ofproto_rule = ofproto_rule_cast(rule);
    struct wdp_flow_stats stats;
    struct ofpbuf *buf;
    int error;

    if (ofproto_rule->send_flow_removed) {
        /* Compose most of the ofp_flow_removed before 'rule' is destroyed. */
        buf = compose_flow_removed(p, rule, reason);
    } else {
        buf = NULL;
    }

    error = wdp_flow_delete(p->wdp, rule, &stats);
    if (error) {
        return error;
    }

    if (buf) {
        struct ofp_flow_removed *ofr;
        struct ofconn *prev = NULL;
        struct ofconn *ofconn;

        /* Compose the parts of the ofp_flow_removed that require stats. */
        ofr = buf->data;
        ofr->packet_count = htonll(stats.n_packets);
        ofr->byte_count = htonll(stats.n_bytes);

        LIST_FOR_EACH (ofconn, node, &p->all_conns) {
            if (rconn_is_connected(ofconn->rconn)) {
                if (prev) {
                    queue_tx(ofpbuf_clone(buf), prev, prev->reply_counter);
                }
                prev = ofconn;
            }
        }
        if (prev) {
            queue_tx(buf, prev, prev->reply_counter);
        } else {
            ofpbuf_delete(buf);
        }
    }
    free(ofproto_rule);

    return 0;
}

/* pinsched callback for sending 'packet' on 'ofconn'. */
static void
do_send_packet_in(struct wdp_packet *packet, void *ofconn_)
{
    struct ofconn *ofconn = ofconn_;

    rconn_send_with_limit(ofconn->rconn, packet->payload,
                          ofconn->packet_in_counter, 100);
    packet->payload = NULL;
    wdp_packet_destroy(packet);
}

/* Takes 'packet', which has been converted with do_convert_to_packet_in(), and
 * finalizes its content for sending on 'ofconn', and passes it to 'ofconn''s
 * packet scheduler for sending.
 *
 * 'max_len' specifies the maximum number of bytes of the packet to send on
 * 'ofconn' (INT_MAX specifies no limit).
 *
 * If 'clone' is true, the caller retains ownership of 'packet'.  Otherwise,
 * ownership is transferred to this function. */
static void
schedule_packet_in(struct ofconn *ofconn, struct wdp_packet *packet,
                   int max_len, bool clone)
{
    struct ofproto *ofproto = ofconn->ofproto;
    struct ofp_packet_in *opi = packet->payload->data;
    int send_len, trim_size;
    uint32_t buffer_id;

    /* Get buffer. */
    if (opi->reason == OFPR_ACTION) {
        buffer_id = UINT32_MAX;
    } else if (ofproto->fail_open && fail_open_is_active(ofproto->fail_open)) {
        buffer_id = pktbuf_get_null();
    } else if (!ofconn->pktbuf) {
        buffer_id = UINT32_MAX;
    } else {
        struct ofpbuf payload;
        payload.data = opi->data;
        payload.size = (packet->payload->size
                        - offsetof(struct ofp_packet_in, data));
        buffer_id = pktbuf_save(ofconn->pktbuf, &payload, packet->in_port);
    }

    /* Figure out how much of the packet to send. */
    send_len = ntohs(opi->total_len);
    if (buffer_id != UINT32_MAX) {
        send_len = MIN(send_len, ofconn->miss_send_len);
    }
    send_len = MIN(send_len, max_len);

    /* Adjust packet length and clone if necessary. */
    trim_size = offsetof(struct ofp_packet_in, data) + send_len;
    if (clone) {
        packet = wdp_packet_clone(packet, trim_size);
        opi = packet->payload->data;
    } else {
        packet->payload->size = trim_size;
    }

    /* Update packet headers. */
    opi->buffer_id = htonl(buffer_id);
    update_openflow_length(packet->payload);

    /* Hand over to packet scheduler.  It might immediately call into
     * do_send_packet_in() or it might buffer it for a while (until a later
     * call to pinsched_run()). */
    pinsched_send(ofconn->schedulers[opi->reason], packet->in_port,
                  packet, do_send_packet_in, ofconn);
}

/* Converts 'packet->payload' to a struct ofp_packet_in.  It must have
 * sufficient headroom to do so (e.g. as returned by xfif_recv()).
 *
 * The conversion is not complete: the caller still needs to trim any unneeded
 * payload off the end of the buffer, set the length in the OpenFlow header,
 * and set buffer_id.  Those require us to know the controller settings and so
 * must be done on a per-controller basis.
 *
 * Returns the maximum number of bytes of the packet that should be sent to
 * the controller (INT_MAX if no limit). */
static int
do_convert_to_packet_in(struct wdp_packet *packet)
{
    uint16_t total_len = packet->payload->size;
    struct ofp_packet_in *opi;

    /* Repurpose packet buffer by overwriting header. */
    opi = ofpbuf_push_zeros(packet->payload,
                            offsetof(struct ofp_packet_in, data));
    opi->header.version = OFP_VERSION;
    opi->header.type = OFPT_PACKET_IN;
    opi->total_len = htons(total_len);
    opi->in_port = htons(packet->in_port);
    if (packet->channel == WDP_CHAN_MISS) {
        opi->reason = OFPR_NO_MATCH;
        return INT_MAX;
    } else {
        opi->reason = OFPR_ACTION;
        return packet->send_len;
    }
}

/* Given 'packet' with channel WDP_CHAN_ACTION or WDP_CHAN_MISS, sends an
 * OFPT_PACKET_IN message to each OpenFlow controller as necessary according to
 * their individual configurations.
 *
 * 'packet->payload' must have sufficient headroom to convert it into a struct
 * ofp_packet_in (e.g. as returned by dpif_recv()).
 *
 * Takes ownership of 'packet'. */
static void
send_packet_in(struct ofproto *ofproto, struct wdp_packet *packet)
{
    struct ofconn *ofconn, *prev;
    int max_len;

    max_len = do_convert_to_packet_in(packet);

    prev = NULL;
    LIST_FOR_EACH (ofconn, node, &ofproto->all_conns) {
        if (ofconn_receives_async_msgs(ofconn)) {
            if (prev) {
                schedule_packet_in(prev, packet, max_len, true);
            }
            prev = ofconn;
        }
    }
    if (prev) {
        schedule_packet_in(prev, packet, max_len, false);
    } else {
        wdp_packet_destroy(packet);
    }
}

static uint64_t
pick_datapath_id(const struct ofproto *ofproto)
{
    struct wdp_port port;

    if (!wdp_port_query_by_number(ofproto->wdp, OFPP_LOCAL, &port)) {
        uint8_t ea[ETH_ADDR_LEN];
        int error;

        error = netdev_get_etheraddr(port.netdev, ea);
        if (!error) {
            wdp_port_free(&port);
            return eth_addr_to_uint64(ea);
        }
        VLOG_WARN("could not get MAC address for %s (%s)",
                  netdev_get_name(port.netdev), strerror(error));
        wdp_port_free(&port);
    }

    return ofproto->fallback_dpid;
}

static uint64_t
pick_fallback_dpid(void)
{
    uint8_t ea[ETH_ADDR_LEN];
    eth_addr_nicira_random(ea);
    return eth_addr_to_uint64(ea);
}