proto_dhcpv4.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: 2cd741e68c48e1218fb64fb903e6f1d0038a39b6 $
 * @file proto_dhcpv4.c
 * @brief DHCPV4 master protocol handler.
 *
 * @copyright 2017 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 * @copyright 2016 Alan DeKok (aland@freeradius.org)
 */
#define LOG_PREFIX "proto_dhcpv4"
 
#include <freeradius-devel/io/listen.h>
#include <freeradius-devel/server/module_rlm.h>
#include <freeradius-devel/util/debug.h>
#include "proto_dhcpv4.h"
 
extern fr_app_t proto_dhcpv4;
static int type_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule);
static int transport_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule);
 
static const conf_parser_t priority_config[] = {
        { FR_CONF_OFFSET("Discover", proto_dhcpv4_t, priorities[FR_DHCP_DISCOVER]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "normal" },
        { FR_CONF_OFFSET("Request", proto_dhcpv4_t, priorities[FR_DHCP_REQUEST]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "normal" },
        { FR_CONF_OFFSET("Decline", proto_dhcpv4_t, priorities[FR_DHCP_DECLINE]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "normal" },
        { FR_CONF_OFFSET("Release", proto_dhcpv4_t, priorities[FR_DHCP_RELEASE]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "normal" },
        { FR_CONF_OFFSET("Inform", proto_dhcpv4_t, priorities[FR_DHCP_INFORM]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "normal" },
        { FR_CONF_OFFSET("Lease-Query", proto_dhcpv4_t, priorities[FR_DHCP_LEASE_QUERY]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "low" },
        { FR_CONF_OFFSET("Bulk-Lease-Query", proto_dhcpv4_t, priorities[FR_DHCP_BULK_LEASE_QUERY]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "low" },
        CONF_PARSER_TERMINATOR
};
 
static conf_parser_t const limit_config[] = {
        { FR_CONF_OFFSET("cleanup_delay", proto_dhcpv4_t, io.cleanup_delay), .dflt = "5.0" } ,
        { FR_CONF_OFFSET("idle_timeout", proto_dhcpv4_t, io.idle_timeout), .dflt = "30.0" } ,
        { FR_CONF_OFFSET("dynamic_timeout", proto_dhcpv4_t, io.dynamic_timeout), .dflt = "600.0" } ,
        { FR_CONF_OFFSET("nak_lifetime", proto_dhcpv4_t, io.nak_lifetime), .dflt = "30.0" } ,
 
        { FR_CONF_OFFSET("max_connections", proto_dhcpv4_t, io.max_connections), .dflt = "1024" } ,
        { FR_CONF_OFFSET("max_clients", proto_dhcpv4_t, io.max_clients), .dflt = "256" } ,
        { FR_CONF_OFFSET("max_pending_packets", proto_dhcpv4_t, io.max_pending_packets), .dflt = "256" } ,
 
        /*
         *      For performance tweaking.  NOT for normal humans.
         */
        { FR_CONF_OFFSET("max_packet_size", proto_dhcpv4_t, max_packet_size) } ,
        { FR_CONF_OFFSET("num_messages", proto_dhcpv4_t, num_messages) } ,
        { FR_CONF_POINTER("priority", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) priority_config },
 
        CONF_PARSER_TERMINATOR
};
 
static conf_parser_t const log_config[] = {
        { FR_CONF_OFFSET("ignored_clients", proto_dhcpv4_t, io.log_ignored_clients), .dflt = "yes" } ,
 
        CONF_PARSER_TERMINATOR
};
 
/** How to parse a DHCPV4 listen section
 *
 */
static conf_parser_t const proto_dhcpv4_config[] = {
        { FR_CONF_OFFSET_FLAGS("type", CONF_FLAG_NOT_EMPTY, proto_dhcpv4_t, allowed_types), .func = type_parse },
        { FR_CONF_OFFSET_TYPE_FLAGS("transport", FR_TYPE_VOID, 0, proto_dhcpv4_t, io.submodule),
          .func = transport_parse },
 
        { FR_CONF_POINTER("log", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) log_config },
        { FR_CONF_POINTER("limit", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) limit_config },
 
        CONF_PARSER_TERMINATOR
};
 
 
static fr_dict_t const *dict_dhcpv4;
 
extern fr_dict_autoload_t proto_dhcpv4_dict[];
fr_dict_autoload_t proto_dhcpv4_dict[] = {
        { .out = &dict_dhcpv4, .proto = "dhcpv4" },
        { NULL }
};
 
static fr_dict_attr_t const *attr_message_type;
static fr_dict_attr_t const *attr_packet_type;
 
extern fr_dict_attr_autoload_t proto_dhcpv4_dict_attr[];
fr_dict_attr_autoload_t proto_dhcpv4_dict_attr[] = {
        { .out = &attr_message_type, .name = "Message-Type", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4},
        { .out = &attr_packet_type, .name = "Packet-Type", .type = FR_TYPE_UINT32, .dict = &dict_dhcpv4},
        { NULL }
};
 
/** Translates the packet-type into a submodule name
 *
 * @param[in] ctx       to allocate data in (instance of proto_dhcpv4).
 * @param[out] out      Where to write a module_instance_t containing the module handle and instance.
 * @param[in] parent    Base structure address.
 * @param[in] ci        #CONF_PAIR specifying the name of the type module.
 * @param[in] rule      unused.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int type_parse(UNUSED TALLOC_CTX *ctx, void *out, void *parent,
                      CONF_ITEM *ci, UNUSED conf_parser_t const *rule)
{
        proto_dhcpv4_t                          *inst = talloc_get_type_abort(parent, proto_dhcpv4_t);
        fr_dict_enum_value_t const              *dv;
        CONF_PAIR                               *cp;
        char const                              *value;
 
        cp = cf_item_to_pair(ci);
        value = cf_pair_value(cp);
 
        dv = fr_dict_enum_by_name(attr_packet_type, value, -1);
        if (!dv || (dv->value->vb_uint32 >= FR_DHCP_CODE_MAX)) {
                cf_log_err(ci, "Unknown DHCPv4 packet type '%s'", value);
                return -1;
        }
 
        inst->allowed[dv->value->vb_uint32] = true;
        *((char const **) out) = value;
 
        return 0;
}
 
static int transport_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule)
{
        proto_dhcpv4_t          *inst = talloc_get_type_abort(parent, proto_dhcpv4_t);
        module_instance_t       *mi;
 
        if (unlikely(virtual_server_listen_transport_parse(ctx, out, parent, ci, rule) < 0)) {
                return -1;
        }
 
        mi = talloc_get_type_abort(*(void **)out, module_instance_t);
        inst->io.app_io = (fr_app_io_t const *)mi->exported;
        inst->io.app_io_instance = mi->data;
        inst->io.app_io_conf = mi->conf;
 
        return 0;
}
 
/** Decode the packet
 *
 */
static int mod_decode(UNUSED void const *instance, request_t *request, uint8_t *const data, size_t data_len)
{
        fr_io_track_t const *track = talloc_get_type_abort_const(request->async->packet_ctx, fr_io_track_t);
        fr_io_address_t const *address = track->address;
        fr_client_t const *client;
        fr_packet_t *packet = request->packet;
 
        RHEXDUMP3(data, data_len, "proto_dhcpv4 decode packet");
 
        client = address->radclient;
 
        /*
         *      Hacks for now until we have a lower-level decode routine.
         */
        request->packet->id = fr_nbo_to_uint32(data + 4);
        request->reply->id = request->packet->id;
 
        request->packet->data = talloc_memdup(request->packet, data, data_len);
        request->packet->data_len = data_len;
 
        /*
         *      Note that we don't set a limit on max_attributes here.
         *      That MUST be set and checked in the underlying
         *      transport, via a call to fr_dhcpv4_ok().
         */
        if (fr_dhcpv4_decode(request->request_ctx, &request->request_pairs,
                             packet->data, packet->data_len, &packet->code) < 0) {
                RPEDEBUG("Failed decoding packet");
                return -1;
        }
 
        /*
         *      Set the rest of the fields.
         */
        request->client = UNCONST(fr_client_t *, client);
 
        request->packet->socket = address->socket;
        fr_socket_addr_swap(&request->reply->socket, &address->socket);
 
        if (fr_packet_pairs_from_packet(request->request_ctx, &request->request_pairs, request->packet) < 0) {
                RPEDEBUG("Failed decoding 'Net.*' packet");
                return -1;
        }
 
        REQUEST_VERIFY(request);
 
        return 0;
}
 
static ssize_t mod_encode(UNUSED void const *instance, request_t *request, uint8_t *buffer, size_t buffer_len)
{
        fr_io_track_t   *track = talloc_get_type_abort(request->async->packet_ctx, fr_io_track_t);
        fr_io_address_t const *address = track->address;
        dhcp_packet_t *reply = (dhcp_packet_t *) buffer;
        dhcp_packet_t *original = (dhcp_packet_t *) request->packet->data;
        ssize_t data_len;
        fr_client_t const *client;
 
        /*
         *      process layer NAK, or "Do not respond".  We also never
         *      send replies to a release.
         */
        if ((buffer_len == 1) ||
            (request->reply->code == FR_DHCP_DO_NOT_RESPOND) ||
            (request->reply->code == 0) || (request->reply->code >= FR_DHCP_CODE_MAX) ||
            (request->packet->code == FR_DHCP_RELEASE)) {
                track->do_not_respond = true;
                return 1;
        }
 
        client = address->radclient;
        fr_assert(client);
 
        /*
         *      Dynamic client stuff
         */
        if (client->dynamic && !client->active) {
                fr_client_t *new_client;
 
                fr_assert(buffer_len >= sizeof(client));
 
                /*
                 *      We don't accept the new client, so don't do
                 *      anything.
                 */
                if (request->reply->code != FR_DHCP_ACK) {
                        *buffer = true;
                        return 1;
                }
 
                /*
                 *      Allocate the client.  If that fails, send back a NAK.
                 *
                 *      @todo - deal with NUMA zones?  Or just deal with this
                 *      client being in different memory.
                 *
                 *      Maybe we should create a CONF_SECTION from the client,
                 *      and pass *that* back to mod_write(), which can then
                 *      parse it to create the actual client....
                 */
                new_client = client_afrom_request(NULL, request);
                if (!new_client) {
                        PERROR("Failed creating new client");
                        buffer[0] = true;
                        return 1;
                }
 
                memcpy(buffer, &new_client, sizeof(new_client));
                return sizeof(new_client);
        }
 
        if (buffer_len < MIN_PACKET_SIZE) {
                REDEBUG("Output buffer is too small to hold a DHCPv4 packet.");
                return -1;
        }
 
        memset(buffer, 0, buffer_len);
 
        /*
         *      Initialize the output packet from the input packet.
         */
#define COPY(_x) reply->_x = original->_x
#define MEMCPY(_x) memcpy(&reply->_x, &original->_x, sizeof(reply->_x))
 
        COPY(htype);
        COPY(hlen);
        COPY(xid);
        MEMCPY(chaddr);
 
        data_len = fr_dhcpv4_encode(buffer, buffer_len, original, request->reply->code,
                                    ntohl(original->xid), &request->reply_pairs);
        if (data_len < 0) {
                RPEDEBUG("Failed encoding DHCPV4 reply");
                return -1;
        }
 
        RHEXDUMP3(buffer, data_len, "proto_dhcpv4 encode packet");
 
        if (RDEBUG_ENABLED) {
                /*
                 *      We can't report the destination IP / port here as it is manipulated in mod_write
                 */
                RDEBUG("Sending %s XID %08x length %zu via socket %s",
                       dhcp_message_types[request->reply->code],
                       request->reply->id,
                       data_len,
                       request->async->listen->name);
                log_request_proto_pair_list(L_DBG_LVL_1, request, NULL, &request->reply_pairs, NULL);
        }
 
        request->reply->data_len = data_len;
        return data_len;
}
 
static int mod_priority_set(void const *instance, uint8_t const *buffer, size_t buflen)
{
        proto_dhcpv4_t const *inst = talloc_get_type_abort_const(instance, proto_dhcpv4_t);
        uint8_t const *code;
 
        if (buflen < MIN_PACKET_SIZE) return -1;
 
        code = fr_dhcpv4_packet_get_option((dhcp_packet_t const *) buffer, buflen, attr_message_type);
        fr_assert(code != NULL);
        fr_assert(code[1] == 1);
        fr_assert(code[2] != 0);
        fr_assert(code[2] < FR_DHCP_CODE_MAX);
 
        /*
         *      Disallowed packet
         */
        if (!inst->priorities[code[2]]) return 0;
 
        if (!inst->allowed[code[2]]) return -1;
 
        /*
         *      @todo - if we cared, we could also return -1 for "this
         *      is a bad packet".  But that's really only for
         *      mod_inject, as we assume that app_io->read() always
         *      returns good packets.
         */
 
        /*
         *      Return the configured priority.
         */
        return inst->priorities[code[2]];
}
 
/** Open listen sockets/connect to external event source
 *
 * @param[in] instance  Ctx data for this application.
 * @param[in] sc        to add our file descriptor to.
 * @param[in] conf      Listen section parsed to give us instance.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int mod_open(void *instance, fr_schedule_t *sc, UNUSED CONF_SECTION *conf)
{
        proto_dhcpv4_t  *inst = talloc_get_type_abort(instance, proto_dhcpv4_t);
 
        inst->io.app = &proto_dhcpv4;
        inst->io.app_instance = instance;
 
        return fr_master_io_listen(&inst->io, sc,
                                   inst->max_packet_size, inst->num_messages);
}
 
/** Instantiate the application
 *
 * Instantiate I/O and type submodules.
 *
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int mod_instantiate(module_inst_ctx_t const *mctx)
{
        proto_dhcpv4_t          *inst = talloc_get_type_abort(mctx->mi->data, proto_dhcpv4_t);
 
        /*
         *      Ensure that the server CONF_SECTION is always set.
         */
        inst->io.server_cs = cf_item_to_section(cf_parent(mctx->mi->conf));
 
        fr_assert(dict_dhcpv4 != NULL);
        fr_assert(attr_message_type != NULL);
 
        /*
         *      No IO module, it's an empty listener.
         */
        if (!inst->io.submodule) return 0;
 
        /*
         *      Tell the master handler about the main protocol instance.
         */
        inst->io.app = &proto_dhcpv4;
        inst->io.app_instance = inst;
 
        /*
         *      We will need this for dynamic clients and connected sockets.
         */
        inst->io.mi = mctx->mi;
 
        /*
         *      These configuration items are not printed by default,
         *      because normal people shouldn't be touching them.
         */
        if (!inst->max_packet_size && inst->io.app_io) inst->max_packet_size = inst->io.app_io->default_message_size;
 
        if (!inst->num_messages) inst->num_messages = 256;
 
        /*
         *      These timers are usually protocol specific.
         */
        FR_TIME_DELTA_BOUND_CHECK("idle_timeout", inst->io.idle_timeout, >=, fr_time_delta_from_sec(1));
        FR_TIME_DELTA_BOUND_CHECK("idle_timeout", inst->io.idle_timeout, <=, fr_time_delta_from_sec(600));
 
        FR_TIME_DELTA_BOUND_CHECK("nak_lifetime", inst->io.nak_lifetime, >=, fr_time_delta_from_sec(1));
        FR_TIME_DELTA_BOUND_CHECK("nak_lifetime", inst->io.nak_lifetime, <=, fr_time_delta_from_sec(600));
 
        FR_TIME_DELTA_BOUND_CHECK("cleanup_delay", inst->io.cleanup_delay, <=, fr_time_delta_from_sec(30));
        FR_TIME_DELTA_BOUND_CHECK("cleanup_delay", inst->io.cleanup_delay, >, fr_time_delta_from_sec(0));
 
        FR_INTEGER_BOUND_CHECK("num_messages", inst->num_messages, >=, 32);
        FR_INTEGER_BOUND_CHECK("num_messages", inst->num_messages, <=, 65535);
 
        FR_INTEGER_BOUND_CHECK("max_packet_size", inst->max_packet_size, >=, 1024);
        FR_INTEGER_BOUND_CHECK("max_packet_size", inst->max_packet_size, <=, 65535);
 
        /*
         *      Instantiate the transport module before calling the
         *      common instantiation function.
         */
        if (module_instantiate(inst->io.submodule) < 0) return -1;
 
        /*
         *      Instantiate the master io submodule
         */
        return fr_master_app_io.common.instantiate(MODULE_INST_CTX(inst->io.mi));
}
 
static int mod_load(void)
{
        if (fr_dhcpv4_global_init() < 0) {
                PERROR("Failed initialising protocol library");
                return -1;
        }
 
        return 0;
}
 
static void mod_unload(void)
{
        fr_dhcpv4_global_free();
}
 
fr_app_t proto_dhcpv4 = {
        .common = {
                .magic                  = MODULE_MAGIC_INIT,
                .name                   = "dhcpv4",
                .config                 = proto_dhcpv4_config,
                .inst_size              = sizeof(proto_dhcpv4_t),
 
                .onload                 = mod_load,
                .unload                 = mod_unload,
 
                .instantiate            = mod_instantiate
        },
        .dict                   = &dict_dhcpv4,
        .open                   = mod_open,
        .decode                 = mod_decode,
        .encode                 = mod_encode,
        .priority               = mod_priority_set
};