/*

 * Copyright (c) 2011, 2012, 2013, 2014, 2017 Nicira, Inc.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at:

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <config.h>

#include "route-table.h"

#include <errno.h>

#include <sys/types.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <sys/socket.h>

#include <linux/rtnetlink.h>

#include <net/if.h>

#include "coverage.h"

#include "hash.h"

#include "netdev.h"

#include "netlink.h"

#include "netlink-notifier.h"

#include "netlink-socket.h"

#include "openvswitch/list.h"

#include "openvswitch/ofpbuf.h"

#include "ovs-router.h"

#include "packets.h"

#include "rtnetlink.h"

#include "tnl-ports.h"

#include "openvswitch/vlog.h"

/* Linux 2.6.36 added RTA_MARK, so define it just in case we're building with

 * old headers.  (We can't test for it with #ifdef because it's an enum.) */

#define RTA_MARK 16

VLOG_DEFINE_THIS_MODULE(route_table);

COVERAGE_DEFINE(route_table_dump);

static struct ovs_mutex route_table_mutex = OVS_MUTEX_INITIALIZER;

static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);

/* Global change number for route-table, which should be incremented

 * every time route_table_reset() is called.  */

static uint64_t rt_change_seq;

static struct nln *nln = NULL;

static struct route_table_msg nln_rtmsg_change;

static struct nln_notifier *route_notifier = NULL;

static struct nln_notifier *route6_notifier = NULL;

static struct nln_notifier *name_notifier = NULL;

static bool route_table_valid = false;

static void route_table_reset(void);

static void route_table_handle_msg(const struct route_table_msg *, void *aux);

static void route_table_change(struct route_table_msg *, void *aux);

static void route_map_clear(void);

static void name_table_init(void);

static void name_table_change(const struct rtnetlink_change *, void *);

static void

route_data_destroy_nexthops__(struct route_data *rd)

{

    struct route_data_nexthop *rdnh;

    LIST_FOR_EACH_POP (rdnh, nexthop_node, &rd->nexthops) {

        if (rdnh && rdnh != &rd->primary_next_hop__) {

            free(rdnh);

        }

    }

}

void

route_data_destroy(struct route_data *rd)

{

    route_data_destroy_nexthops__(rd);

}

uint64_t

route_table_get_change_seq(void)

{

    return rt_change_seq;

}

/* Users of the route_table module should register themselves with this

 * function before making any other route_table function calls. */

void

route_table_init(void)

    OVS_EXCLUDED(route_table_mutex)

{

    ovs_mutex_lock(&route_table_mutex);

    ovs_assert(!nln);

    ovs_assert(!route_notifier);

    ovs_assert(!route6_notifier);

    ovs_router_init();

    nln = nln_create(NETLINK_ROUTE, route_table_parse, &nln_rtmsg_change);

    route_notifier =

        nln_notifier_create(nln, RTNLGRP_IPV4_ROUTE,

                            (nln_notify_func *) route_table_change, NULL);

    route6_notifier =

        nln_notifier_create(nln, RTNLGRP_IPV6_ROUTE,

                            (nln_notify_func *) route_table_change, NULL);

    route_table_reset();

    name_table_init();

    ovs_mutex_unlock(&route_table_mutex);

}

/* Run periodically to update the locally maintained routing table. */

void

route_table_run(void)

    OVS_EXCLUDED(route_table_mutex)

{

    ovs_mutex_lock(&route_table_mutex);

    if (nln) {

        rtnetlink_run();

        nln_run(nln);

        if (!route_table_valid) {

            route_table_reset();

        }

    }

    ovs_mutex_unlock(&route_table_mutex);

}

/* Causes poll_block() to wake up when route_table updates are required. */

void

route_table_wait(void)

    OVS_EXCLUDED(route_table_mutex)

{

    ovs_mutex_lock(&route_table_mutex);

    if (nln) {

        rtnetlink_wait();

        nln_wait(nln);

    }

    ovs_mutex_unlock(&route_table_mutex);

}

bool

route_table_dump_one_table(uint32_t id,

                           route_table_handle_msg_callback *handle_msg_cb,

                           void *aux)

{

    uint64_t reply_stub[NL_DUMP_BUFSIZE / 8];

    struct ofpbuf request, reply, buf;

    struct rtmsg *rq_msg;

    bool filtered = true;

    struct nl_dump dump;

    ofpbuf_init(&request, 0);

    nl_msg_put_nlmsghdr(&request, sizeof *rq_msg, RTM_GETROUTE, NLM_F_REQUEST);

    rq_msg = ofpbuf_put_zeros(&request, sizeof *rq_msg);

    rq_msg->rtm_family = AF_UNSPEC;

    if (id > UCHAR_MAX) {

        rq_msg->rtm_table = RT_TABLE_UNSPEC;

        nl_msg_put_u32(&request, RTA_TABLE, id);

    } else {

        rq_msg->rtm_table = id;

    }

    nl_dump_start(&dump, NETLINK_ROUTE, &request);

    ofpbuf_uninit(&request);

    ofpbuf_use_stub(&buf, reply_stub, sizeof reply_stub);

    while (nl_dump_next(&dump, &reply, &buf)) {

        struct route_table_msg msg;

        if (route_table_parse(&reply, &msg)) {

            struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(&reply);

            /* Older kernels do not support filtering. */

            if (!(nlmsghdr->nlmsg_flags & NLM_F_DUMP_FILTERED)) {

                filtered = false;

            }

            handle_msg_cb(&msg, aux);

            route_data_destroy(&msg.rd);

        }

    }

    ofpbuf_uninit(&buf);

    nl_dump_done(&dump);

    return filtered;

}

static void

route_table_reset(void)

{

    uint32_t tables[] = {

        RT_TABLE_DEFAULT,

        RT_TABLE_MAIN,

        RT_TABLE_LOCAL,

    };

    route_map_clear();

    netdev_get_addrs_list_flush();

    route_table_valid = true;

    rt_change_seq++;

    COVERAGE_INC(route_table_dump);

    for (size_t i = 0; i < ARRAY_SIZE(tables); i++) {

        if (!route_table_dump_one_table(tables[i],

                                        route_table_handle_msg, NULL)) {

            /* Got unfiltered reply, no need to dump further. */

            break;

        }

    }

}

/* Returns true if the given route requires nexthop information (output

 * interface, nexthop IP, ...).  Returns false for special route types

 * that don't need this information. */

static bool

route_type_needs_nexthop(unsigned char rtmsg_type)

{

    switch (rtmsg_type) {

    case RTN_BLACKHOLE:

    case RTN_THROW:

    case RTN_UNREACHABLE:

    case RTN_PROHIBIT:

        return false;

    default:

        return true;

    }

}

static int

route_table_parse__(struct ofpbuf *buf, size_t ofs,

                    const struct nlmsghdr *nlmsg,

                    const struct rtmsg *rtm,

                    const struct rtnexthop *rtnh,

                    struct route_table_msg *change)

{

    bool parsed, ipv4 = false;

    static const struct nl_policy policy[] = {

        [RTA_DST] = { .type = NL_A_U32, .optional = true  },

        [RTA_OIF] = { .type = NL_A_U32, .optional = true },

        [RTA_GATEWAY] = { .type = NL_A_U32, .optional = true },

        [RTA_MARK] = { .type = NL_A_U32, .optional = true },

        [RTA_PREFSRC] = { .type = NL_A_U32, .optional = true },

        [RTA_TABLE] = { .type = NL_A_U32, .optional = true },

        [RTA_PRIORITY] = { .type = NL_A_U32, .optional = true },

        [RTA_VIA] = { .type = NL_A_RTA_VIA, .optional = true },

        [RTA_MULTIPATH] = { .type = NL_A_NESTED, .optional = true },

    };

    static const struct nl_policy policy6[] = {

        [RTA_DST] = { .type = NL_A_IPV6, .optional = true },

        [RTA_OIF] = { .type = NL_A_U32, .optional = true },

        [RTA_MARK] = { .type = NL_A_U32, .optional = true },

        [RTA_GATEWAY] = { .type = NL_A_IPV6, .optional = true },

        [RTA_PREFSRC] = { .type = NL_A_IPV6, .optional = true },

        [RTA_TABLE] = { .type = NL_A_U32, .optional = true },

        [RTA_PRIORITY] = { .type = NL_A_U32, .optional = true },

        [RTA_VIA] = { .type = NL_A_RTA_VIA, .optional = true },

        [RTA_MULTIPATH] = { .type = NL_A_NESTED, .optional = true },

    };

    struct nlattr *attrs[ARRAY_SIZE(policy)];

    if (rtm->rtm_family == AF_INET) {

        parsed = nl_policy_parse(buf, ofs, policy, attrs,

                                 ARRAY_SIZE(policy));

        ipv4 = true;

    } else if (rtm->rtm_family == AF_INET6) {

        parsed = nl_policy_parse(buf, ofs, policy6, attrs,

                                 ARRAY_SIZE(policy6));

    } else {

        VLOG_DBG_RL(&rl, "received non AF_INET rtnetlink route message");

        return 0;

    }

    if (parsed) {

        struct route_data_nexthop *rdnh = NULL;

        int rta_oif;      /* Output interface index. */

        memset(change, 0, sizeof *change);

        ovs_list_init(&change->rd.nexthops);

        rdnh = rtnh ? xzalloc(sizeof *rdnh) : &change->rd.primary_next_hop__;

        ovs_list_insert(&change->rd.nexthops, &rdnh->nexthop_node);

        rdnh->family = rtm->rtm_family;

        change->relevant = true;

        if (rtm->rtm_scope == RT_SCOPE_NOWHERE) {

            change->relevant = false;

        }

        if (rtm->rtm_type != RTN_UNICAST &&

            rtm->rtm_type != RTN_LOCAL) {

            change->relevant = false;

        }

        change->rd.rta_table_id = rtm->rtm_table;

        if (attrs[RTA_TABLE]) {

            change->rd.rta_table_id = nl_attr_get_u32(attrs[RTA_TABLE]);

        }

        change->nlmsg_type     = nlmsg->nlmsg_type;

        change->rd.rtm_dst_len = rtm->rtm_dst_len;

        change->rd.rtm_protocol = rtm->rtm_protocol;

        change->rd.rtn_local = rtm->rtm_type == RTN_LOCAL;

        if (attrs[RTA_OIF] && rtnh) {

            VLOG_DBG_RL(&rl, "unexpected RTA_OIF attribute while parsing "

                             "nested RTA_MULTIPATH attributes");

            goto error_out;

        }

        if (attrs[RTA_OIF] || rtnh) {

            rta_oif = rtnh ? rtnh->rtnh_ifindex

                           : nl_attr_get_u32(attrs[RTA_OIF]);

            if (!if_indextoname(rta_oif, rdnh->ifname)) {

                int error = errno;

                VLOG_DBG_RL(&rl, "could not find interface name[%u]: %s",

                            rta_oif, ovs_strerror(error));

                if (error == ENXIO) {

                    change->relevant = false;

                } else {

                    goto error_out;

                }

            }

        }

        if (attrs[RTA_DST]) {

            if (ipv4) {

                ovs_be32 dst;

                dst = nl_attr_get_be32(attrs[RTA_DST]);

                in6_addr_set_mapped_ipv4(&change->rd.rta_dst, dst);

            } else {

                change->rd.rta_dst = nl_attr_get_in6_addr(attrs[RTA_DST]);

            }

        } else if (ipv4) {

            in6_addr_set_mapped_ipv4(&change->rd.rta_dst, 0);

        }

        if (attrs[RTA_PREFSRC]) {

            if (ipv4) {

                ovs_be32 prefsrc;

                prefsrc = nl_attr_get_be32(attrs[RTA_PREFSRC]);

                in6_addr_set_mapped_ipv4(&change->rd.rta_prefsrc, prefsrc);

            } else {

                change->rd.rta_prefsrc =

                    nl_attr_get_in6_addr(attrs[RTA_PREFSRC]);

            }

        }

        if (attrs[RTA_GATEWAY]) {

            if (ipv4) {

                ovs_be32 gw;

                gw = nl_attr_get_be32(attrs[RTA_GATEWAY]);

                in6_addr_set_mapped_ipv4(&rdnh->addr, gw);

            } else {

                rdnh->addr = nl_attr_get_in6_addr(attrs[RTA_GATEWAY]);

            }

        }

        if (attrs[RTA_MARK]) {

            change->rd.rta_mark = nl_attr_get_u32(attrs[RTA_MARK]);

        }

        if (attrs[RTA_PRIORITY]) {

            change->rd.rta_priority = nl_attr_get_u32(attrs[RTA_PRIORITY]);

        }

        if (attrs[RTA_VIA]) {

            const struct rtvia *rtvia = nl_attr_get(attrs[RTA_VIA]);

            ovs_be32 addr;

            if (attrs[RTA_GATEWAY]) {

                VLOG_DBG_RL(&rl, "route message can not contain both "

                                 "RTA_GATEWAY and RTA_VIA");

                goto error_out;

            }

            rdnh->family = rtvia->rtvia_family;

            switch (rdnh->family) {

            case AF_INET:

                if (nl_attr_get_size(attrs[RTA_VIA])

                        - sizeof *rtvia < sizeof addr) {

                    VLOG_DBG_RL(&rl, "got short message while parsing RTA_VIA "

                                     "attribute for family AF_INET");

                    goto error_out;

                }

                memcpy(&addr, rtvia->rtvia_addr, sizeof addr);

                in6_addr_set_mapped_ipv4(&rdnh->addr, addr);

                break;

            case AF_INET6:

                if (nl_attr_get_size(attrs[RTA_VIA])

                        - sizeof *rtvia < sizeof rdnh->addr) {

                    VLOG_DBG_RL(&rl, "got short message while parsing RTA_VIA "

                                     "attribute for family AF_INET6");

                    goto error_out;

                }

                memcpy(&rdnh->addr, rtvia->rtvia_addr, sizeof rdnh->addr);

                break;

            default:

                VLOG_DBG_RL(&rl, "unsupported address family, %d, "

                                 "in via attribute", rdnh->family);

                goto error_out;

            }

        }

        if (attrs[RTA_MULTIPATH]) {

            const struct nlattr *nla;

            size_t left;

            if (rtnh) {

                VLOG_DBG_RL(&rl, "unexpected nested RTA_MULTIPATH attribute");

                goto error_out;

            }

            /* The change->rd->nexthops list is unconditionally populated with

             * a single rdnh entry as we start parsing above.  Multiple

             * branches above may access it or jump to error_out, and having it

             * on the list is the only way to ensure proper cleanup.

             *

             * Getting to this point, we know that the above branches has not

             * provided next hop information, because information about

             * multiple next hops is encoded in the nested attributes after the

             * RTA_MULTIPATH attribute.

             *

             * Before retrieving those we need to remove the empty rdnh entry

             * from the list. */

            route_data_destroy_nexthops__(&change->rd);

            NL_NESTED_FOR_EACH (nla, left, attrs[RTA_MULTIPATH]) {

                struct route_table_msg mp_change;

                struct rtnexthop *mp_rtnh;

                struct ofpbuf mp_buf;

                ofpbuf_use_const(&mp_buf, nla, nla->nla_len);

                mp_rtnh = ofpbuf_try_pull(&mp_buf, sizeof *mp_rtnh);

                if (!mp_rtnh) {

                    VLOG_DBG_RL(&rl, "got short message while parsing "

                                     "multipath attribute");

                    goto error_out;

                }

                if (!route_table_parse__(&mp_buf, 0, nlmsg, rtm, mp_rtnh,

                                         &mp_change)) {

                    goto error_out;

                }

                ovs_list_push_back_all(&change->rd.nexthops,

                                       &mp_change.rd.nexthops);

            }

        }

        if (route_type_needs_nexthop(rtm->rtm_type)

            && !attrs[RTA_OIF] && !attrs[RTA_GATEWAY]

            && !attrs[RTA_VIA] && !attrs[RTA_MULTIPATH]) {

            VLOG_DBG_RL(&rl, "route message needs an RTA_OIF, RTA_GATEWAY, "

                             "RTA_VIA or RTA_MULTIPATH attribute");

            goto error_out;

        }

        /* Add any additional RTA attribute processing before RTA_MULTIPATH. */

        /* Ensure that the change->rd->nexthops list is cleared in cases when

         * the route does not need a next hop. */

        if (!route_type_needs_nexthop(rtm->rtm_type)) {

            route_data_destroy_nexthops__(&change->rd);

        }

    } else {

        VLOG_DBG_RL(&rl, "received unparseable rtnetlink route message");

        goto error_out;

    }

    /* Success. */

    return ipv4 ? RTNLGRP_IPV4_ROUTE : RTNLGRP_IPV6_ROUTE;

error_out:

    route_data_destroy(&change->rd);

    return 0;

}

/* Parse Netlink message in buf, which is expected to contain a UAPI rtmsg

 * header and associated route attributes.

 *

 * Return RTNLGRP_IPV4_ROUTE or RTNLGRP_IPV6_ROUTE on success, and 0 on a parse

 * error.

 *

 * On success, memory may have been allocated, and it is the caller's

 * responsibility to free it with a call to route_data_destroy().

 *

 * In case of error, any allocated memory will be freed before returning. */

int

route_table_parse(struct ofpbuf *buf, void *change)

{

    struct nlmsghdr *nlmsg;

    struct rtmsg *rtm;

    nlmsg = ofpbuf_at(buf, 0, NLMSG_HDRLEN);

    rtm = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *rtm);

    if (!nlmsg || !rtm) {

        return 0;

    }

    return route_table_parse__(buf, NLMSG_HDRLEN + sizeof *rtm,

                               nlmsg, rtm, NULL, change);

}

static bool

is_standard_table_id(uint32_t table_id)

{

    return !table_id

           || table_id == RT_TABLE_DEFAULT

           || table_id == RT_TABLE_MAIN

           || table_id == RT_TABLE_LOCAL;

}

static void

route_table_change(struct route_table_msg *change, void *aux OVS_UNUSED)

{

    if (!change

        || (change->relevant

            && is_standard_table_id(change->rd.rta_table_id))) {

        route_table_valid = false;

    }

    if (change) {

        route_data_destroy(&change->rd);

    }

}

static void

route_table_handle_msg(const struct route_table_msg *change,

                       void *aux OVS_UNUSED)

{

    if (change->relevant && change->nlmsg_type == RTM_NEWROUTE

            && !ovs_list_is_empty(&change->rd.nexthops)) {

        const struct route_data *rd = &change->rd;

        const struct route_data_nexthop *rdnh;

        /* The ovs-router module currently does not implement lookup or

         * storage for routes with multiple next hops.  For backwards

         * compatibility, we use the first next hop. */

        rdnh = CONTAINER_OF(ovs_list_front(&change->rd.nexthops),

                            const struct route_data_nexthop, nexthop_node);

        ovs_router_insert(rd->rta_mark, &rd->rta_dst,

                          IN6_IS_ADDR_V4MAPPED(&rd->rta_dst)

                          ? rd->rtm_dst_len + 96 : rd->rtm_dst_len,

                          rd->rtn_local, rdnh->ifname, &rdnh->addr,

                          &rd->rta_prefsrc);

    }

}

static void

route_map_clear(void)

{

    ovs_router_flush();

}

bool

route_table_fallback_lookup(const struct in6_addr *ip6_dst OVS_UNUSED,

                            char name[] OVS_UNUSED,

                            struct in6_addr *gw6)

{

    *gw6 = in6addr_any;

    return false;

}

/* name_table . */

static void

name_table_init(void)

{

    name_notifier = rtnetlink_notifier_create(name_table_change, NULL);

}

static void

name_table_change(const struct rtnetlink_change *change,

                  void *aux OVS_UNUSED)

{

    if (change && change->irrelevant) {

        return;

    }

    /* Changes to interface status can cause routing table changes that some

     * versions of the linux kernel do not advertise for some reason. */

    route_table_valid = false;

    if (change && change->nlmsg_type == RTM_DELLINK) {

        if (change->ifname) {

            tnl_port_map_delete_ipdev(change->ifname);

        }

    }

}