proto_radius.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: 5ad093de534a02b2af1a9b01908d4dd6e71571f4 $
 * @file proto_radius.c
 * @brief RADIUS master protocol handler.
 *
 * @copyright 2017 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 * @copyright 2016 Alan DeKok (aland@freeradius.org)
 */
#include <freeradius-devel/radius/radius.h>
#include <freeradius-devel/io/listen.h>
#include <freeradius-devel/unlang/xlat_func.h>
#include <freeradius-devel/server/module_rlm.h>
#include <stdbool.h>
#include "proto_radius.h"
 
extern fr_app_t proto_radius;
 
static int type_parse(TALLOC_CTX *ctx, void *out, UNUSED 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 conf_parser_t const limit_config[] = {
        { FR_CONF_OFFSET("cleanup_delay", proto_radius_t, io.cleanup_delay), .dflt = "5.0" } ,
        { FR_CONF_OFFSET("idle_timeout", proto_radius_t, io.idle_timeout), .dflt = "30.0" } ,
        { FR_CONF_OFFSET("dynamic_timeout", proto_radius_t, io.dynamic_timeout), .dflt = "600.0" } ,
        { FR_CONF_OFFSET("nak_lifetime", proto_radius_t, io.nak_lifetime), .dflt = "30.0" } ,
 
        { FR_CONF_OFFSET("max_connections", proto_radius_t, io.max_connections), .dflt = "1024" } ,
        { FR_CONF_OFFSET("max_clients", proto_radius_t, io.max_clients), .dflt = "256" } ,
        { FR_CONF_OFFSET("max_pending_packets", proto_radius_t, io.max_pending_packets), .dflt = "256" } ,
 
        /*
         *      For performance tweaking.  NOT for normal humans.
         */
        { FR_CONF_OFFSET("max_packet_size", proto_radius_t, max_packet_size) } ,
        { FR_CONF_OFFSET("num_messages", proto_radius_t, num_messages) } ,
 
        CONF_PARSER_TERMINATOR
};
 
static const conf_parser_t priority_config[] = {
        { FR_CONF_OFFSET("Access-Request", proto_radius_t, priorities[FR_RADIUS_CODE_ACCESS_REQUEST]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "high" },
        { FR_CONF_OFFSET("Accounting-Request", proto_radius_t, priorities[FR_RADIUS_CODE_ACCOUNTING_REQUEST]),
          .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("CoA-Request", proto_radius_t, priorities[FR_RADIUS_CODE_COA_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("Disconnect-Request", proto_radius_t, priorities[FR_RADIUS_CODE_DISCONNECT_REQUEST]),
          .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("Status-Server", proto_radius_t, priorities[FR_RADIUS_CODE_STATUS_SERVER]),
          .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = channel_packet_priority, .len = &channel_packet_priority_len }, .dflt = "now" },
 
        CONF_PARSER_TERMINATOR
};
 
static conf_parser_t const log_config[] = {
        { FR_CONF_OFFSET("ignored_clients", proto_radius_t, io.log_ignored_clients), .dflt = "yes" } ,
 
        CONF_PARSER_TERMINATOR
};
 
/** How to parse a RADIUS listen section
 *
 */
static conf_parser_t const proto_radius_config[] = {
        { FR_CONF_OFFSET_FLAGS("type", CONF_FLAG_NOT_EMPTY, proto_radius_t, allowed_types), .func = type_parse },
        { FR_CONF_OFFSET_TYPE_FLAGS("transport", FR_TYPE_VOID, 0, proto_radius_t, io.submodule),
          .func = transport_parse },
 
        /*
         *      Check whether or not the *trailing* bits of a
         *      Tunnel-Password are zero, as they should be.
         */
        { FR_CONF_OFFSET("tunnel_password_zeros", proto_radius_t, tunnel_password_zeros) } ,
 
        { FR_CONF_POINTER("limit", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) limit_config },
        { FR_CONF_POINTER("priority", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) priority_config },
 
        { FR_CONF_POINTER("log", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) log_config },
 
        { FR_CONF_OFFSET("require_message_authenticator", proto_radius_t, require_message_authenticator),
          .func = cf_table_parse_int,
          .uctx = &(cf_table_parse_ctx_t){ .table = fr_radius_require_ma_table, .len = &fr_radius_require_ma_table_len },
          .dflt = "no" },
 
        { FR_CONF_OFFSET("limit_proxy_state", proto_radius_t, limit_proxy_state),
          .func = cf_table_parse_int,
          .uctx = &(cf_table_parse_ctx_t){ .table = fr_radius_limit_proxy_state_table, .len = &fr_radius_limit_proxy_state_table_len },
          .dflt = "auto" },
 
        CONF_PARSER_TERMINATOR
};
 
static fr_dict_t const *dict_radius;
 
extern fr_dict_autoload_t proto_radius_dict[];
fr_dict_autoload_t proto_radius_dict[] = {
        { .out = &dict_radius, .proto = "radius" },
        DICT_AUTOLOAD_TERMINATOR
};
 
static fr_dict_attr_t const *attr_packet_type;
static fr_dict_attr_t const *attr_user_name;
static fr_dict_attr_t const *attr_state;
static fr_dict_attr_t const *attr_proxy_state;
static fr_dict_attr_t const *attr_message_authenticator;
static fr_dict_attr_t const *attr_eap_message;
static fr_dict_attr_t const *attr_error_cause;
static fr_dict_attr_t const *attr_packet_id;
static fr_dict_attr_t const *attr_packet_authenticator;
 
extern fr_dict_attr_autoload_t proto_radius_dict_attr[];
fr_dict_attr_autoload_t proto_radius_dict_attr[] = {
        { .out = &attr_packet_type, .name = "Packet-Type", .type = FR_TYPE_UINT32, .dict = &dict_radius},
        { .out = &attr_user_name, .name = "User-Name", .type = FR_TYPE_STRING, .dict = &dict_radius},
        { .out = &attr_state, .name = "State", .type = FR_TYPE_OCTETS, .dict = &dict_radius},
        { .out = &attr_proxy_state, .name = "Proxy-State", .type = FR_TYPE_OCTETS, .dict = &dict_radius},
        { .out = &attr_message_authenticator, .name = "Message-Authenticator", .type = FR_TYPE_OCTETS, .dict = &dict_radius},
        { .out = &attr_eap_message, .name = "EAP-Message", .type = FR_TYPE_OCTETS, .dict = &dict_radius},
        { .out = &attr_error_cause, .name = "Error-Cause", .type = FR_TYPE_UINT32, .dict = &dict_radius},
        { .out = &attr_packet_id, .name = "Packet.Id", .type = FR_TYPE_UINT8, .dict = &dict_radius},
        { .out = &attr_packet_authenticator, .name = "Packet.Authenticator", .type = FR_TYPE_OCTETS, .dict = &dict_radius},
        DICT_AUTOLOAD_TERMINATOR
};
 
/** Translates the packet-type into a submodule name
 *
 * If we found a Packet-Type = Access-Request CONF_PAIR for example, here's we'd load
 * the proto_radius_auth module.
 *
 * @param[in] ctx       to allocate data in (instance of proto_radius).
 * @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_radius_t                  *inst = talloc_get_type_abort(parent, proto_radius_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_RADIUS_CODE_MAX)) {
                cf_log_err(ci, "Unknown RADIUS 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_radius_t          *inst = talloc_get_type_abort(parent, proto_radius_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(void const *instance, request_t *request, uint8_t *const data, size_t data_len)
{
        proto_radius_t const            *inst = talloc_get_type_abort_const(instance, proto_radius_t);
        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                     *client = UNCONST(fr_client_t *, address->radclient);
        fr_radius_ctx_t                 common_ctx;
        fr_radius_decode_ctx_t          decode_ctx;
 
        fr_radius_require_ma_t          require_message_authenticator = client->require_message_authenticator_is_set ?
                                                                        client->require_message_authenticator:
                                                                        inst->require_message_authenticator;
        fr_radius_limit_proxy_state_t   limit_proxy_state = client->limit_proxy_state_is_set ?
                                                            client->limit_proxy_state:
                                                            inst->limit_proxy_state;
        fr_pair_t                       *packet_vp;
 
        fr_assert(data[0] < FR_RADIUS_CODE_MAX);
 
        common_ctx = (fr_radius_ctx_t) {
                .secret = client->secret,
                .secret_length = talloc_array_length(client->secret) - 1,
        };
 
        request->packet->code = data[0];
 
        decode_ctx = (fr_radius_decode_ctx_t) {
                .common = &common_ctx,
                .tmp_ctx = talloc(request, uint8_t),
                /* decode figures out request_authenticator */
                .end = data + data_len,
                .verify = client->active,
        };
 
        if (request->packet->code == FR_RADIUS_CODE_ACCESS_REQUEST) {
                /*
                 *      bit1 is set if we've seen a packet, and the auto bit in require_message_authenticator is set/
                 *      bit2 is set if we always require a message_authenticator.
                 *      If either bit is high we require a message authenticator in the packet.
                 */
                decode_ctx.require_message_authenticator = (
                                (client->received_message_authenticator & require_message_authenticator) |
                                (require_message_authenticator & FR_RADIUS_REQUIRE_MA_YES)
                        ) > 0;
                decode_ctx.limit_proxy_state = (
                                (client->first_packet_no_proxy_state & limit_proxy_state) |
                                (limit_proxy_state & FR_RADIUS_LIMIT_PROXY_STATE_YES)
                        ) > 0;
        }
 
        /*
         *      The verify() routine over-writes the request packet vector.
         *
         *      @todo - That needs to be changed.
         */
        request->packet->id = data[1];
        request->reply->id = data[1];
        memcpy(request->packet->vector, data + 4, sizeof(request->packet->vector));
 
        request->packet->data = talloc_memdup(request->packet, data, data_len);
        request->packet->data_len = data_len;
 
        /*
         *      !client->active means a fake packet defining a dynamic client - so there will
         *      be no secret defined yet - so can't verify.
         */
        if (fr_radius_decode(request->request_ctx, &request->request_pairs,
                             data, data_len, &decode_ctx) < 0) {
                talloc_free(decode_ctx.tmp_ctx);
                RPEDEBUG("Failed decoding packet");
                return -1;
        }
        talloc_free(decode_ctx.tmp_ctx);
 
        /*
         *      Set the rest of the fields.
         */
        request->client = client;
 
        request->packet->socket = address->socket;
        fr_socket_addr_swap(&request->reply->socket, &address->socket);
 
        if (request->packet->code == FR_RADIUS_CODE_ACCESS_REQUEST) {
                /*
                 *      If require_message_authenticator is "auto" then
                 *      we start requiring messages authenticator after
                 *      the first Access-Request packet containing a
                 *      verified one.  This isn't vulnerable to the same
                 *      attack as limit_proxy_state, as the attacker would
                 *      need knowledge of the secret.
                 *
                 *      Unfortunately there are too many cases where
                 *      auto mode could break things (dealing with
                 *      multiple clients behind a NAT for example).
                 */
                if (!client->received_message_authenticator &&
                    fr_pair_find_by_da(&request->request_pairs, NULL, attr_message_authenticator)) {
                        /*
                         *      Don't print debugging messages if all is OK.
                         */
                        if (require_message_authenticator == FR_RADIUS_REQUIRE_MA_YES) {
                                client->received_message_authenticator = true;
 
                        } else if (require_message_authenticator == FR_RADIUS_REQUIRE_MA_AUTO) {
                                if (!fr_pair_find_by_da(&request->request_pairs, NULL, attr_eap_message)) {
                                        client->received_message_authenticator = true;
 
                                        RINFO("Packet from client %pV (%pV) contained a valid Message-Authenticator.  Setting \"require_message_authenticator = yes\"",
                                              fr_box_ipaddr(client->ipaddr),
                                              fr_box_strvalue_buffer(client->shortname));
                                } else {
                                        RINFO("Packet from client %pV (%pV) contained a valid Message-Authenticator but also EAP-Message",
                                              fr_box_ipaddr(client->ipaddr),
                                              fr_box_strvalue_buffer(client->shortname));
                                        RINFO("Not changing the value of 'require_message_authenticator = auto'");
                                }
                        }
                }
 
                /*
                 *      It's important we only evaluate this on the
                 *      first packet.  Otherwise an attacker could send
                 *      Access-Requests with no Proxy-State whilst
                 *      spoofing a legitimate Proxy-Server, and causing an
                 *      outage.
                 *
                 *      The likelihood of an attacker sending a packet
                 *      to coincide with the reboot of a RADIUS
                 *      server is low. That said, 'auto' should likely
                 *      not be enabled for internet facing servers.
                 */
                if (!client->received_message_authenticator &&
                    (limit_proxy_state == FR_RADIUS_LIMIT_PROXY_STATE_AUTO) &&
                    client->active && !client->seen_first_packet) {
                        client->seen_first_packet = true;
                        client->first_packet_no_proxy_state = fr_pair_find_by_da(&request->request_pairs, NULL, attr_proxy_state) == NULL;
 
                        /* None of these should be errors */
                        if (!fr_pair_find_by_da(&request->request_pairs, NULL, attr_message_authenticator)) {
                                RWARN("Packet from %pV (%pV) did not contain Message-Authenticator:",
                                      fr_box_ipaddr(client->ipaddr),
                                      fr_box_strvalue_buffer(client->shortname));
                                RWARN("- Upgrade the client, as your network is vulnerable to the BlastRADIUS attack.");
                                RWARN("- Then set 'require_message_authenticator = yes' in the client definition");
                        } else {
                                RWARN("Packet from %pV (%pV) contains Message-Authenticator:",
                                      fr_box_ipaddr(client->ipaddr),
                                      fr_box_strvalue_buffer(client->shortname));
                                RWARN("- Then set 'require_message_authenticator = yes' in the client definition");
                        }
 
                        RINFO("First packet from %pV (%pV) %s Proxy-State.  Setting \"limit_proxy_state = %s\"",
                              fr_box_ipaddr(client->ipaddr),
                              fr_box_strvalue_buffer(client->shortname),
                              client->first_packet_no_proxy_state ? "did not contain" : "contained",
                              client->first_packet_no_proxy_state ? "yes" : "no");
 
                        if (!client->first_packet_no_proxy_state) {
                                RERROR("Packet from %pV (%pV) contains Proxy-State, but no Message-Authenticator:",
                                       fr_box_ipaddr(client->ipaddr),
                                       fr_box_strvalue_buffer(client->shortname));
                                RERROR("- Upgrade the client, as your network is vulnerable to the BlastRADIUS attack.");
                                RERROR("- Then set 'require_message_authenticator = yes' in the client definition");
                        }
                }
        }
 
        REQUEST_VERIFY(request);
 
        /*
         *      If we're defining a dynamic client, this packet is
         *      fake.  We don't have a secret, so we mash all of the
         *      encrypted attributes to sane (i.e. non-hurtful)
         *      values.
         */
        if (!client->active) {
                fr_pair_t *vp;
 
                fr_assert(client->dynamic);
 
                request_set_dynamic_client(request);
 
                for (vp = fr_pair_list_head(&request->request_pairs);
                     vp != NULL;
                     vp = fr_pair_list_next(&request->request_pairs, vp)) {
                        if (fr_radius_flag_encrypted(vp->da)) {
                                switch (vp->vp_type) {
                                default:
                                        break;
 
                                case FR_TYPE_UINT32:
                                        vp->vp_uint32 = 0;
                                        break;
 
                                case FR_TYPE_IPV4_ADDR:
                                        vp->vp_ipv4addr = INADDR_ANY;
                                        break;
 
                                case FR_TYPE_OCTETS:
                                        fr_pair_value_memdup(vp, (uint8_t const *) "", 1, true);
                                        break;
 
                                case FR_TYPE_STRING:
                                        fr_pair_value_strdup(vp, "", true);
                                        break;
                                }
                        }
                }
        }
 
        /*
         *      Set the sequence to be at least one.  This will
         *      prioritize replies to Access-Challenges over other
         *      packets. The sequence will be updated (if necessary)
         *      by the RADIUS state machine.  If the request yields,
         *      it will get re-inserted with an updated sequence
         *      number.
         */
        if ((request->packet->code == FR_RADIUS_CODE_ACCESS_REQUEST) &&
            fr_pair_find_by_da(&request->request_pairs, NULL, attr_state)) {
                request->sequence = 1;
        }
 
        if (fr_packet_pairs_from_packet(request->request_ctx, &request->request_pairs, request->packet) < 0) {
                RPEDEBUG("Failed decoding 'Net.*' packet");
                return -1;
        }
 
        /*
         *      Populate Packet structure with Id and Authenticator
         */
        MEM(packet_vp = fr_pair_afrom_da_nested(request->request_ctx, &request->request_pairs, attr_packet_id));
        packet_vp->vp_uint8 = request->packet->id;
        MEM(packet_vp = fr_pair_afrom_da_nested(request->request_ctx, &request->request_pairs, attr_packet_authenticator));
        if (fr_value_box_memdup(packet_vp, &packet_vp->data, NULL, request->packet->data + 4,
                                RADIUS_AUTH_VECTOR_LENGTH, true) < 0) {
                RPEDEBUG("Failed adding Authenticator pair");
                return -1;
        }
 
        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;
        uint32_t                error_cause;
        ssize_t                 data_len;
        fr_client_t const       *client;
        fr_radius_ctx_t         common_ctx = {};
        fr_radius_encode_ctx_t  encode_ctx;
 
        client = address->radclient;
        fr_assert(client);
 
        /*
         *      No reply was set, and the client supports Protocol-Error.  Go create one.
         */
        if (unlikely((buffer_len > 1) && (request->reply->code == 0) && client->protocol_error)) {
                switch (request->packet->code) {
                case FR_RADIUS_CODE_ACCESS_REQUEST:
                        RDEBUG2("There was no response configured - sending Access-Reject");
                        request->reply->code = FR_RADIUS_CODE_ACCESS_REJECT;
                        break;
 
                case FR_RADIUS_CODE_COA_REQUEST:
                        RDEBUG2("There was no response configured - sending CoA-NAK");
                        request->reply->code = FR_RADIUS_CODE_COA_NAK;
                        goto not_routable;
 
                case FR_RADIUS_CODE_DISCONNECT_REQUEST:
                        RDEBUG2("There was no response configured - sending Disconnect-NAK");
                        request->reply->code = FR_RADIUS_CODE_DISCONNECT_NAK;
                        goto not_routable;
 
                case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
                        /*
                         *      Send Protocol-Error reply.
                         *
                         *      @todo - Session-Context-Not-Found is likely the wrong error.
                         */
                        RDEBUG2("There was no response configured - sending Protocol-Error");
 
                        request->reply->code = FR_RADIUS_CODE_PROTOCOL_ERROR;
                        error_cause = FR_ERROR_CAUSE_VALUE_SESSION_CONTEXT_NOT_FOUND;
                        goto force_reply;
 
                default:
                        RDEBUG2("There was no response configured - not sending reply");
                        break;
                }
        }
 
        /*
         *      Process layer NAK, or "Do not respond".
         */
        if ((buffer_len == 1) ||
            (request->reply->code == FR_RADIUS_CODE_DO_NOT_RESPOND) ||
            (request->reply->code == 0) || (request->reply->code >= FR_RADIUS_CODE_MAX)) {
                track->do_not_respond = true;
                return 1;
        }
 
        /*
         *      Not all clients support Protocol-Error.  The admin might have forced Protocol-Error, or we
         *      might have received a Protocol-Error from a home server.
         */
        if ((request->reply->code == FR_RADIUS_CODE_PROTOCOL_ERROR) && !client->protocol_error) {
                fr_pair_t *vp;
 
                switch (request->packet->code) {
                case FR_RADIUS_CODE_ACCESS_REQUEST:
                        RWDEBUG("Client %s does not support Protocol-Error - rewriting to Access-Reject",
                                client->shortname);
                        request->reply->code = FR_RADIUS_CODE_ACCESS_REJECT;
                        break;
 
                case FR_RADIUS_CODE_COA_REQUEST:
                        RWDEBUG2("Client %s does not support Protocol-Error - rewriting to CoA-NAK",
                                 request->client->shortname);
                        request->reply->code = FR_RADIUS_CODE_COA_NAK;
                        goto not_routable;
 
                case FR_RADIUS_CODE_DISCONNECT_REQUEST:
                        RWDEBUG2("Client %s does not support Protocol-Error - rewriting to Disconnect-NAK",
                                 request->client->shortname);
                        request->reply->code = FR_RADIUS_CODE_DISCONNECT_NAK;
 
                not_routable:
                        error_cause = FR_ERROR_CAUSE_VALUE_PROXY_REQUEST_NOT_ROUTABLE;
 
                force_reply:
                        fr_pair_list_free(&request->reply_pairs);
 
                        MEM(vp = fr_pair_afrom_da(request->reply_ctx, attr_error_cause));
                        fr_pair_append(&request->reply_pairs, vp);
                        vp->vp_uint32 = error_cause;
                        break;
 
                case FR_RADIUS_CODE_ACCOUNTING_REQUEST:
                default:
                        RWDEBUG2("Client %s does not support Protocol-Error - not replying to the client",
                                 request->client->shortname);
                        track->do_not_respond = true;
                        return 1;
                }
        }
 
        /*
         *      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_RADIUS_CODE_ACCESS_ACCEPT) {
                        *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 = true;
                        return 1;
                }
 
                memcpy(buffer, &new_client, sizeof(new_client));
                return sizeof(new_client);
        }
 
        /*
         *      Overwrite the src ip address on the outbound packet
         *      with the one specified by the client.  This is useful
         *      to work around broken DSR implementations and other
         *      routing issues.
         */
        if (client->src_ipaddr.af != AF_UNSPEC) {
                request->reply->socket.inet.src_ipaddr = client->src_ipaddr;
        }
 
        common_ctx = (fr_radius_ctx_t) {
                .secret = client->secret,
                .secret_length = talloc_array_length(client->secret) - 1,
        };
        encode_ctx = (fr_radius_encode_ctx_t) {
                .common = &common_ctx,
                .request_authenticator = request->packet->data + 4,
                .rand_ctx = (fr_fast_rand_t) {
                        .a = fr_rand(),
                        .b = fr_rand(),
                },
                .request_code = request->packet->data[0],
                .code = request->reply->code,
                .id = request->reply->id,
        };
 
        data_len = fr_radius_encode(&FR_DBUFF_TMP(buffer, buffer_len), &request->reply_pairs, &encode_ctx);
        if (data_len < 0) {
                RPEDEBUG("Failed encoding RADIUS reply");
                return -1;
        }
 
        if (fr_radius_sign(buffer, request->packet->data + 4,
                           (uint8_t const *) client->secret, talloc_array_length(client->secret) - 1) < 0) {
                RPEDEBUG("Failed signing RADIUS reply");
                return -1;
        }
 
        fr_packet_net_from_pairs(request->reply, &request->reply_pairs);
 
        if (RDEBUG_ENABLED) {
                RDEBUG("Sending %s ID %i from %pV:%i to %pV:%i length %zu via socket %s",
                       fr_radius_packet_name[request->reply->code],
                       request->reply->id,
                       fr_box_ipaddr(request->reply->socket.inet.src_ipaddr),
                       request->reply->socket.inet.src_port,
                       fr_box_ipaddr(request->reply->socket.inet.dst_ipaddr),
                       request->reply->socket.inet.dst_port,
                       data_len,
                       request->async->listen->name);
 
                log_request_pair_list(L_DBG_LVL_1, request, NULL, &request->reply_pairs, NULL);
        }
 
        return data_len;
}
 
static int mod_priority_set(void const *instance, uint8_t const *buffer, UNUSED size_t buflen)
{
        proto_radius_t const *inst = talloc_get_type_abort_const(instance, proto_radius_t);
 
        fr_assert(buffer[0] > 0);
        fr_assert(buffer[0] < FR_RADIUS_CODE_MAX);
 
        /*
         *      Disallowed packet
         */
        if (!inst->priorities[buffer[0]]) return 0;
 
        if (!inst->allowed[buffer[0]]) 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[buffer[0]];
}
 
/** 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_radius_t  *inst = talloc_get_type_abort(instance, proto_radius_t);
 
        /*
         *      io.app_io should already be set
         */
        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_radius_t          *inst = talloc_get_type_abort(mctx->mi->data, proto_radius_t);
 
        /*
         *      No IO module, it's an empty listener.
         */
        if (!inst->io.submodule) return 0;
 
        /*
         *      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));
 
#if 0
        /*
         *      No Access-Request packets, then no cleanup delay.
         */
        if (!inst->allowed[FR_RADIUS_CODE_ACCESS_REQUEST]) {
                inst->io.cleanup_delay = 0;
        }
#endif
 
        /*
         *      Ensure that the server CONF_SECTION is always set.
         */
        inst->io.server_cs = cf_item_to_section(cf_parent(mctx->mi->conf));
 
        /*
         *      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;
 
        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);
 
        /*
         *      Tell the master handler about the main protocol instance.
         */
        inst->io.app = &proto_radius;
        inst->io.app_instance = inst;
 
        /*
         *      We will need this for dynamic clients and connected sockets.
         */
        inst->io.mi = mctx->mi;
 
        /*
         *      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));
}
 
/** Get the authentication vector.
 *
 *  Note that we don't allow people to get the reply vector, because
 *  it doesn't exist until the reply is sent.
 *
 */
static xlat_action_t packet_vector_xlat(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                        UNUSED xlat_ctx_t const *xctx, request_t *request,
                                        UNUSED fr_value_box_list_t *in)
{
        fr_value_box_t  *vb;
 
        if (request->proto_dict != dict_radius) return XLAT_ACTION_FAIL;
 
        MEM(vb = fr_value_box_alloc(ctx, FR_TYPE_OCTETS, NULL));
        if (fr_value_box_memdup(vb, vb, NULL, request->packet->vector, sizeof(request->packet->vector), true) < 0) {
                talloc_free(vb);
                return XLAT_ACTION_FAIL;
        }
 
        fr_dcursor_append(out, vb);
 
        return XLAT_ACTION_DONE;
}
 
 
static int mod_load(void)
{
        if (fr_radius_global_init() < 0) {
                PERROR("Failed initialising protocol library");
                return -1;
        }
 
 
        if (!xlat_func_register(NULL, "radius.packet.vector", packet_vector_xlat, FR_TYPE_OCTETS)) return -1;
 
        return 0;
}
 
static void mod_unload(void)
{
        xlat_func_unregister("radius.packet.vector");
 
        fr_radius_global_free();
}
 
fr_app_t proto_radius = {
        .common = {
                .magic                  = MODULE_MAGIC_INIT,
                .name                   = "radius",
                .config                 = proto_radius_config,
                .inst_size              = sizeof(proto_radius_t),
                .onload                 = mod_load,
                .unload                 = mod_unload,
                .instantiate            = mod_instantiate
        },
        .dict                   = &dict_radius,
        .open                   = mod_open,
        .decode                 = mod_decode,
        .encode                 = mod_encode,
        .priority               = mod_priority_set
};