proto_bfd_udp.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: 2e40eb6b90eedd466c1025ff99b87ac7cf054f8c $
 * @file proto_bfd_udp.c
 * @brief BFD handler for UDP.
 *
 * @copyright 2023 Network RADIUS SAS (legal@networkradius.com)
 */
#include <netdb.h>
#include <freeradius-devel/server/protocol.h>
#include <freeradius-devel/util/udp.h>
#include <freeradius-devel/util/trie.h>
#include <freeradius-devel/bfd/bfd.h>
#include <freeradius-devel/io/application.h>
#include <freeradius-devel/io/listen.h>
#include <freeradius-devel/io/schedule.h>
 
#include "session.h"
 
extern fr_app_io_t proto_bfd_udp;
 
typedef struct {
        char const                      *name;                  //!< socket name
        int                             sockfd;
 
        fr_io_address_t                 *connection;            //!< for connected sockets.
 
        fr_stats_t                      stats;                  //!< statistics for this socket
 
} proto_bfd_udp_thread_t;
 
typedef struct {
        CONF_SECTION                    *cs;                    //!< our configuration
        char const                      *server_name;           //!< virtual server name
 
        fr_ipaddr_t                     ipaddr;                 //!< IP address to listen on.
 
        char const                      *interface;             //!< Interface to bind to.
        char const                      *port_name;             //!< Name of the port for getservent().
 
        uint32_t                        recv_buff;              //!< How big the kernel's receive buffer should be.
        uint32_t                        send_buff;              //!< How big the kernel's send buffer should be.
 
        uint16_t                        port;                   //!< Port to listen on.
 
        uint8_t                         ttl;                    //!< default ttl
 
        bool                            only_state_changes;     //!< on read(), only send packets which signal a state change
 
        bool                            recv_buff_is_set;       //!< Whether we were provided with a recv_buff
        bool                            send_buff_is_set;       //!< Whether we were provided with a send_buff
        bool                            dynamic_clients;        //!< whether we have dynamic clients
 
        fr_rb_tree_t                    *peers;                 //!< our peers
 
        fr_trie_t                       *trie;                  //!< for parsed networks
        fr_ipaddr_t                     *allow;                 //!< allowed networks for dynamic clients
        fr_ipaddr_t                     *deny;                  //!< denied networks for dynamic clients
} proto_bfd_udp_t;
 
 
static const conf_parser_t networks_config[] = {
        { FR_CONF_OFFSET_TYPE_FLAGS("allow", FR_TYPE_COMBO_IP_PREFIX , CONF_FLAG_MULTI, proto_bfd_udp_t, allow) },
        { FR_CONF_OFFSET_TYPE_FLAGS("deny", FR_TYPE_COMBO_IP_PREFIX , CONF_FLAG_MULTI, proto_bfd_udp_t, deny) },
 
        CONF_PARSER_TERMINATOR
};
 
 
static const conf_parser_t udp_listen_config[] = {
        { FR_CONF_OFFSET_TYPE_FLAGS("ipaddr", FR_TYPE_COMBO_IP_ADDR, 0, proto_bfd_udp_t, ipaddr) },
        { FR_CONF_OFFSET_TYPE_FLAGS("ipv4addr", FR_TYPE_IPV4_ADDR, 0, proto_bfd_udp_t, ipaddr) },
        { FR_CONF_OFFSET_TYPE_FLAGS("ipv6addr", FR_TYPE_IPV6_ADDR, 0, proto_bfd_udp_t, ipaddr) },
 
        { FR_CONF_OFFSET("interface", proto_bfd_udp_t, interface) },
        { FR_CONF_OFFSET("port_name", proto_bfd_udp_t, port_name) },
 
        { FR_CONF_OFFSET("port", proto_bfd_udp_t, port) },
 
        { FR_CONF_OFFSET("ttl", proto_bfd_udp_t, ttl), .dflt = "255" },
 
        { FR_CONF_OFFSET("only_state_changes", proto_bfd_udp_t, only_state_changes), .dflt = "yes" },
 
        { FR_CONF_OFFSET_IS_SET("recv_buff", FR_TYPE_UINT32, 0, proto_bfd_udp_t, recv_buff) },
        { FR_CONF_OFFSET_IS_SET("send_buff", FR_TYPE_UINT32, 0, proto_bfd_udp_t, send_buff) },
 
//      { FR_CONF_OFFSET("dynamic_clients", proto_bfd_udp_t, dynamic_clients) } ,
        { FR_CONF_POINTER("networks", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) networks_config },
 
        CONF_PARSER_TERMINATOR
};
 
 
static ssize_t mod_read(fr_listen_t *li, void **packet_ctx, fr_time_t *recv_time_p, uint8_t *buffer, size_t buffer_len,
                        size_t *leftover)
{
        proto_bfd_udp_t const           *inst = talloc_get_type_abort_const(li->app_io_instance, proto_bfd_udp_t);
        proto_bfd_udp_thread_t          *thread = talloc_get_type_abort(li->thread_instance, proto_bfd_udp_thread_t);
        fr_io_address_t                 *address, **address_p;
        fr_client_t                     *client;
 
        int                             flags;
        ssize_t                         data_size;
        size_t                          packet_len;
 
        bfd_packet_t                    *packet;
        char const                      *err = NULL;
        bfd_state_change_t              state_change;
        bfd_wrapper_t                   *wrapper = (bfd_wrapper_t *) buffer;
 
        *leftover = 0;          /* always for UDP */
 
        /*
         *      Where the addresses should go.  This is a special case
         *      for proto_bfd.
         */
        address_p = (fr_io_address_t **)packet_ctx;
        address = *address_p;
 
        /*
         *      Tell udp_recv if we're connected or not.
         */
        flags = UDP_FLAGS_CONNECTED * (thread->connection != NULL);
 
        data_size = udp_recv(thread->sockfd, flags, &address->socket, wrapper->packet, buffer_len - offsetof(bfd_wrapper_t, packet), recv_time_p);
        if (data_size < 0) {
                PDEBUG2("proto_bfd_udp got read error");
                return data_size;
        }
 
        if (!data_size) {
                DEBUG2("proto_bfd_udp got no data: ignoring");
                return 0;
        }
 
        /*
         *      Try to find the client before looking at any packet data.
         */
        client =  fr_rb_find(inst->peers, &(fr_client_t) { .ipaddr = address->socket.inet.src_ipaddr, .proto = IPPROTO_UDP });
        if (!client) {
                DEBUG2("BFD %s - Received invalid packet on %s - unknown client %pV:%u", inst->server_name, thread->name,
                       fr_box_ipaddr(address->socket.inet.src_ipaddr), address->socket.inet.src_port);
                thread->stats.total_packets_dropped++;
                return 0;
        }
 
        packet_len = data_size;
 
        if (!fr_bfd_packet_ok(&err, wrapper->packet, packet_len)) {
                DEBUG2("BFD %s - Received invalid packet on %s - %s", inst->server_name, thread->name, err);
                thread->stats.total_malformed_requests++;
                return 0;
        }
 
        thread->stats.total_requests++;
        packet = (bfd_packet_t *) wrapper->packet;
 
        /*
         *      Print out what we received.
         */
        DEBUG2("BFD %s peer %s received %s", client->shortname, inst->server_name, fr_bfd_packet_names[packet->state]);
 
        /*
         *      Run the BFD state machine.  Depending on that result,
         *      we either send the packet through to unlang, or not.
         */
        state_change = bfd_session_process((bfd_session_t *) client, packet);
 
        if ((state_change == BFD_STATE_CHANGE_INVALID) || (state_change == BFD_STATE_CHANGE_ADMIN_DOWN)) return 0;
 
        if ((state_change == BFD_STATE_CHANGE_NONE) && inst->only_state_changes) return 0;
 
        wrapper->type = BFD_WRAPPER_RECV_PACKET;
        wrapper->state_change = state_change;
 
        return sizeof(wrapper) + packet_len;
}
 
static ssize_t mod_write(fr_listen_t *li, void *packet_ctx, UNUSED fr_time_t request_time,
                         uint8_t *buffer, size_t buffer_len, UNUSED size_t written)
{
        proto_bfd_udp_thread_t  *thread = talloc_get_type_abort(li->thread_instance, proto_bfd_udp_thread_t);
        fr_io_track_t           *track = talloc_get_type_abort(packet_ctx, fr_io_track_t);
        bfd_session_t           *session;
        ssize_t                 rcode;
#ifndef NDEBUG
        char const              *err;
#endif
 
        /*
         *      @todo - share a stats interface with the parent?  or
         *      put the stats in the listener, so that proto_bfd
         *      can update them, too.. <sigh>
         */
        thread->stats.total_responses++;
 
        session = UNCONST(bfd_session_t *, track->address->radclient);
 
        fr_assert(buffer_len >= FR_BFD_HEADER_LENGTH);
 
        fr_assert(fr_bfd_packet_ok(&err, buffer, buffer_len));
 
        DEBUG("BFD %s peer %s sending %s",
              session->server_name, session->client.shortname, fr_bfd_packet_names[session->session_state]);
 
        rcode = sendfromto(session->sockfd, buffer, buffer_len, 0, 0,
                           (struct sockaddr *) &session->local_sockaddr, session->local_salen,
                           (struct sockaddr *) &session->remote_sockaddr, session->remote_salen);
        if (rcode < 0) {
                ERROR("Failed sending packet: %s", fr_syserror(errno));
                bfd_session_admin_down(session);
                return 0;
        }
 
        return rcode;
}
 
static void mod_network_get(int *ipproto, bool *dynamic_clients, fr_trie_t const **trie, void *instance)
{
        proto_bfd_udp_t *inst = talloc_get_type_abort(instance, proto_bfd_udp_t);
 
        *ipproto = IPPROTO_UDP;
        *dynamic_clients = inst->dynamic_clients;
        *trie = inst->trie;
}
 
/** Open a UDP listener for RADIUS
 *
 */
static int mod_open(fr_listen_t *li)
{
        proto_bfd_udp_t const           *inst = talloc_get_type_abort_const(li->app_io_instance, proto_bfd_udp_t);
        proto_bfd_udp_thread_t  *thread = talloc_get_type_abort(li->thread_instance, proto_bfd_udp_thread_t);
 
        int                             sockfd;
        fr_ipaddr_t                     ipaddr = inst->ipaddr;
        uint16_t                        port = inst->port;
 
        li->fd = sockfd = fr_socket_server_udp(&inst->ipaddr, &port, inst->port_name, true);
        if (sockfd < 0) {
                PERROR("Failed opening UDP socket");
        error:
                return -1;
        }
 
        li->app_io_addr = fr_socket_addr_alloc_inet_src(li, IPPROTO_UDP, 0, &inst->ipaddr, port);
 
        /*
         *      Set SO_REUSEPORT before bind, so that all packets can
         *      listen on the same destination IP address.
         */
        if (1) {
                int on = 1;
 
                if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on)) < 0) {
                        ERROR("Failed to set socket 'reuseport': %s", fr_syserror(errno));
                        return -1;
                }
        }
 
#ifdef SO_RCVBUF
        if (inst->recv_buff_is_set) {
                int opt;
 
                opt = inst->recv_buff;
                if (setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(int)) < 0) {
                        WARN("Failed setting 'recv_buf': %s", fr_syserror(errno));
                }
        }
#endif
 
#ifdef SO_SNDBUF
        if (inst->send_buff_is_set) {
                int opt;
 
                opt = inst->send_buff;
                if (setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &opt, sizeof(int)) < 0) {
                        WARN("Failed setting 'send_buf': %s", fr_syserror(errno));
                }
        }
#endif
 
#ifdef IP_TTL
        {
                int opt;
 
                opt = inst->ttl;
                if (setsockopt(sockfd, IPPROTO_IP, IP_TTL, &opt, sizeof(opt)) < 0) {
                        WARN("Failed setting 'ttl': %s", fr_syserror(errno));
                }
        }
#endif
 
        /*
         *      @todo - cache ifindex for use with udpfromto.
         */
        if (fr_socket_bind(sockfd, inst->interface, &ipaddr, &port) < 0) {
                close(sockfd);
                PERROR("Failed binding socket");
                goto error;
        }
 
        thread->sockfd = sockfd;
 
        fr_assert((cf_parent(inst->cs) != NULL) && (cf_parent(cf_parent(inst->cs)) != NULL));   /* listen { ... } */
 
        thread->name = fr_app_io_socket_name(thread, &proto_bfd_udp,
                                             NULL, 0,
                                             &inst->ipaddr, inst->port,
                                             inst->interface);
 
        return 0;
}
 
/** Set the file descriptor for this socket.
 *
 */
static int mod_fd_set(fr_listen_t *li, int fd)
{
        proto_bfd_udp_t const           *inst = talloc_get_type_abort_const(li->app_io_instance, proto_bfd_udp_t);
        proto_bfd_udp_thread_t  *thread = talloc_get_type_abort(li->thread_instance, proto_bfd_udp_thread_t);
 
        thread->sockfd = fd;
 
        thread->name = fr_app_io_socket_name(thread, &proto_bfd_udp,
                                             &thread->connection->socket.inet.src_ipaddr, thread->connection->socket.inet.src_port,
                                             &inst->ipaddr, inst->port,
                                             inst->interface);
 
        return 0;
}
 
static char const *mod_name(fr_listen_t *li)
{
        proto_bfd_udp_thread_t  *thread = talloc_get_type_abort(li->thread_instance, proto_bfd_udp_thread_t);
 
        return thread->name;
}
 
 
static int mod_instantiate(module_inst_ctx_t const *mctx)
{
        proto_bfd_udp_t         *inst = talloc_get_type_abort(mctx->mi->data, proto_bfd_udp_t);
        CONF_SECTION            *conf = mctx->mi->conf;
        size_t                  num;
        CONF_ITEM               *ci;
        CONF_SECTION            *server_cs;
        fr_rb_iter_inorder_t    iter;
        bfd_session_t   *peer;
 
        inst->cs = conf;
 
        /*
         *      Complain if no "ipaddr" is set.
         */
        if (inst->ipaddr.af == AF_UNSPEC) {
                cf_log_err(conf, "No 'ipaddr' was specified in the 'udp' section");
                return -1;
        }
 
        if (inst->recv_buff_is_set) {
                FR_INTEGER_BOUND_CHECK("recv_buff", inst->recv_buff, >=, 32);
                FR_INTEGER_BOUND_CHECK("recv_buff", inst->recv_buff, <=, INT_MAX);
        }
 
        if (inst->send_buff_is_set) {
                FR_INTEGER_BOUND_CHECK("send_buff", inst->send_buff, >=, 256);
                FR_INTEGER_BOUND_CHECK("send_buff", inst->send_buff, <=, (1 << 30));
        }
 
        FR_INTEGER_BOUND_CHECK("ttl", inst->ttl, >=, 64);
 
        if (!inst->port) {
                struct servent *s;
 
                if (!inst->port_name) {
                        cf_log_err(conf, "No 'port' was specified in the 'udp' section");
                        return -1;
                }
 
                s = getservbyname(inst->port_name, "udp");
                if (!s) {
                        cf_log_err(conf, "Unknown value for 'port_name = %s", inst->port_name);
                        return -1;
                }
 
                inst->port = ntohl(s->s_port);
        }
 
        /*
         *      Parse and create the trie for dynamic clients, even if
         *      there's no dynamic clients.
         */
        num = talloc_array_length(inst->allow);
        if (!num) {
                if (inst->dynamic_clients) {
                        cf_log_err(conf, "The 'allow' subsection MUST contain at least one 'network' entry when 'dynamic_clients = true'.");
                        return -1;
                }
        } else {
                inst->trie = fr_master_io_network(inst, inst->ipaddr.af, inst->allow, inst->deny);
                if (!inst->trie) {
                        cf_log_perr(conf, "Failed creating list of networks");
                        return -1;
                }
        }
 
        ci = cf_section_to_item(mctx->mi->parent->conf); /* listen { ... } */
        fr_assert(ci != NULL);
        ci = cf_parent(ci);
        fr_assert(ci != NULL);
 
        server_cs = cf_item_to_section(ci);
        inst->server_name = cf_section_name2(server_cs);
 
        /*
         *      Look up peer list.
         */
        inst->peers = cf_data_value(cf_data_find(server_cs, fr_rb_tree_t, "peers"));
        if (!inst->peers) {
                cf_log_err(conf, "Failed finding peer list");
                return -1;
        }
 
        /*
         *      Walk over the list of peers, associating them with this listener.
         */
        for (peer = fr_rb_iter_init_inorder(&iter, inst->peers);
             peer != NULL;
             peer = fr_rb_iter_next_inorder(&iter)) {
                if (peer->client.ipaddr.af != inst->ipaddr.af) continue;
 
                if (peer->inst) continue;
 
                /*
                 *      unspecified src_ipaddr is us, OR our address
                 *      matches.
                 */
                if (!(fr_ipaddr_is_inaddr_any(&peer->client.src_ipaddr) ||
                      (fr_ipaddr_cmp(&peer->client.src_ipaddr, &inst->ipaddr) == 0))) continue;
 
                peer->inst = inst;
                peer->client.src_ipaddr = inst->ipaddr; /* override inaddr_any */
 
                /*
                 *      Cache these so that they don't get recalculated on every packet.
                 */
                fr_ipaddr_to_sockaddr(&peer->remote_sockaddr, &peer->remote_salen, &peer->client.ipaddr, peer->port);
                fr_ipaddr_to_sockaddr(&peer->local_sockaddr, &peer->local_salen, &inst->ipaddr, inst->port);
 
                if (bfd_session_init(peer) < 0) {
                        return -1;
                }
        }
 
        return 0;
}
 
static fr_client_t *mod_client_find(fr_listen_t *li, fr_ipaddr_t const *ipaddr, int ipproto)
{
        proto_bfd_udp_t const   *inst = talloc_get_type_abort_const(li->app_io_instance, proto_bfd_udp_t);
 
        if (ipproto != IPPROTO_UDP) return NULL;
 
        return fr_rb_find(inst->peers, &(fr_client_t) { .ipaddr = *ipaddr, .proto = IPPROTO_UDP });
}
 
/** Set the event list for a new socket
 *
 * @param[in] li the listener
 * @param[in] el the event list
 * @param[in] nr context from the network side
 */
static void mod_event_list_set(fr_listen_t *li, fr_event_list_t *el, void *nr)
{
        proto_bfd_udp_t const   *inst = talloc_get_type_abort_const(li->app_io_instance, proto_bfd_udp_t);
        proto_bfd_udp_thread_t  *thread = talloc_get_type_abort(li->thread_instance, proto_bfd_udp_thread_t);
        fr_rb_iter_inorder_t    iter;
        bfd_session_t           *peer;
 
        /*
         *      Walk over the list of peers, associating them with this listener.
         */
        for (peer = fr_rb_iter_init_inorder(&iter, inst->peers);
             peer != NULL;
             peer = fr_rb_iter_next_inorder(&iter)) {
                if (peer->inst != inst) continue;
 
                peer->el = el;
                peer->listen = li;
                peer->nr = (fr_network_t *) nr;
                peer->sockfd = thread->sockfd;
                peer->server_name = inst->server_name;
                peer->only_state_changes = inst->only_state_changes;
 
                bfd_session_start(peer);
        }
}
 
 
fr_app_io_t proto_bfd_udp = {
        .common = {
                .magic                  = MODULE_MAGIC_INIT,
                .name                   = "bfd_udp",
                .config                 = udp_listen_config,
                .inst_size              = sizeof(proto_bfd_udp_t),
                .thread_inst_size       = sizeof(proto_bfd_udp_thread_t),
                .instantiate            = mod_instantiate
        },
        .default_message_size   = FR_BFD_HEADER_LENGTH + 64, /* enough for some auth packets */
        .track_duplicates       = false,
 
        .open                   = mod_open,
        .read                   = mod_read,
        .write                  = mod_write,
        .fd_set                 = mod_fd_set,
        .network_get            = mod_network_get,
        .event_list_set         = mod_event_list_set,
        .client_find            = mod_client_find,
        .get_name               = mod_name,
};