snmp.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: 3640834e39910cd0f01ded26c0974c6e8055e9db $
 *
 * @file src/lib/server/snmp.c
 * @brief Implements an SNMP-like interface using FreeRADIUS attributes
 *
 * @author Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 *
 * @copyright 2016 The FreeRADIUS server project
 * @copyright 2016 Network RADIUS SAS
 */
RCSID("$Id: 3640834e39910cd0f01ded26c0974c6e8055e9db $")
 
#include <freeradius-devel/util/atexit.h>
#include <freeradius-devel/util/debug.h>
 
#include <freeradius-devel/util/misc.h>
#include <freeradius-devel/util/proto.h>
#include <freeradius-devel/util/value.h>
 
#include <freeradius-devel/server/dependency.h>
#include <freeradius-devel/server/main_loop.h>
 
#include <freeradius-devel/protocol/snmp/freeradius.h>
 
static fr_dict_t const *dict_snmp;
 
extern fr_dict_autoload_t snmp_dict[];
fr_dict_autoload_t snmp_dict[] = {
        { .out = &dict_snmp, .proto = "snmp" },
        { NULL }
};
 
static fr_dict_attr_t const *attr_snmp_operation;
static fr_dict_attr_t const *attr_snmp_type;
static fr_dict_attr_t const *attr_snmp_failure;
static fr_dict_attr_t const *attr_snmp_root;
 
extern fr_dict_attr_autoload_t snmp_dict_attr[];
fr_dict_attr_autoload_t snmp_dict_attr[] = {
        { .out = &attr_snmp_operation, .name = "FreeRADIUS-SNMP-Operation", .type = FR_TYPE_UINT8, .dict = &dict_snmp },
        { .out = &attr_snmp_type, .name = "FreeRADIUS-SNMP-Type", .type = FR_TYPE_UINT8, .dict = &dict_snmp },
        { .out = &attr_snmp_failure, .name = "FreeRADIUS-SNMP-Failure", .type = FR_TYPE_UINT8, .dict = &dict_snmp },
        { .out = &attr_snmp_root, .name = "FreeRADIUS-Iso", .type = FR_TYPE_TLV, .dict = &dict_snmp },
        { NULL }
};
 
#define FR_FREERADIUS_SNMP_TYPE_OBJECT 0
 
#define SNMP_MAP_TERMINATOR     { .name = NULL, .da = NULL, .type = 0 }
 
typedef struct fr_snmp_map fr_snmp_map_t;
 
typedef int (*fr_snmp_get_func_t)(TALLOC_CTX *ctx, fr_value_box_t *out, fr_snmp_map_t const *map, void *snmp_ctx);
typedef int (*fr_snmp_set_func_t)(fr_snmp_map_t const *map, void *snmp_ctx, fr_value_box_t *data);
typedef int (*fr_snmp_index_func_t)(TALLOC_CTX *ctx, void **snmp_ctx_out,
                                    fr_snmp_map_t const *map, void const *snmp_ctx_in, uint32_t index);
 
/** Maps a fr_pair_t to the source of a value
 *
 * @note Arrays of maps must be in ascending attribute order.
 *      This is because the lookup is performed using a binary
 *      search, not by index.
 *
 * Mappings between attributes and snmp values are more complex in
 * an SNMP based interface, because we need to traverse the tree,
 * looking at indexes in multiple levels of mapping tables.
 */
struct fr_snmp_map {
        char const              *name;                  //!< Attribute number.  Table entries must be in
                                                        //!< attribute number order.
        fr_dict_attr_t const    *da;                    //!< Dictionary attribute (resolved from attribute number).
        unsigned int            type;                   //!< SNMP type - More specific than attribute type.
 
        fr_snmp_get_func_t      get;                    //!< Function to retrieve value.
        fr_snmp_set_func_t      set;                    //!< Function to write a new value.
        fr_snmp_index_func_t    index;                  //!< Function for traversing indexes.
 
        union {
                size_t                  offset;         //!< Offset in snmp_ctx (passed to index function).
                fr_snmp_map_t           *last;          //!< Last sibling at this level.
        };
 
        fr_snmp_map_t           *child;                 //!< Child map.
};
 
static fr_time_t start_time;
static fr_time_t reset_time;
static int reset_state = FR_RADIUS_AUTH_SERV_CONFIG_RESET_VALUE_RUNNING;
 
static int snmp_value_serv_ident_get(TALLOC_CTX *ctx, fr_value_box_t *out, NDEBUG_UNUSED fr_snmp_map_t const *map,
                                     UNUSED void *snmp_ctx)
{
        fr_assert(map->da->type == FR_TYPE_STRING);
 
        fr_value_box_asprintf(ctx, out, NULL, false, "FreeRADIUS %s", radiusd_version_short);
 
        return 0;
}
 
static int snmp_value_uptime_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out, NDEBUG_UNUSED fr_snmp_map_t const *map,
                                 UNUSED void *snmp_ctx)
{
        fr_time_t now;
        fr_time_delta_t delta;
 
        fr_assert(map->da->type == FR_TYPE_UINT32);
 
        now = fr_time();
        delta = fr_time_sub(now, start_time);
 
        /*
         *      ticks are in 1/100's of seconds.
         */
        out->vb_uint32 += fr_time_delta_to_csec(delta);
 
        return 0;
}
 
static int snmp_config_reset_time_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out, NDEBUG_UNUSED fr_snmp_map_t const *map,
                                      UNUSED void *snmp_ctx)
{
        fr_time_t now;
        fr_time_delta_t delta;
 
        fr_assert(map->da->type == FR_TYPE_UINT32);
 
        now = fr_time();
        delta = fr_time_sub(now, reset_time);
 
        /*
         *      ticks are in 1/100's of seconds.
         */
        out->vb_uint32 += fr_time_delta_to_csec(delta);
 
        return 0;
}
 
static int snmp_config_reset_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out, NDEBUG_UNUSED fr_snmp_map_t const *map,
                                 UNUSED void *snmp_ctx)
{
        fr_assert(map->da->type == FR_TYPE_UINT32);
 
        out->vb_uint32 = reset_state;
 
        return 0;
}
 
static int snmp_config_reset_set(NDEBUG_UNUSED fr_snmp_map_t const *map, UNUSED void *snmp_ctx, fr_value_box_t *in)
{
        fr_assert(map->da->type == FR_TYPE_UINT32);
 
        switch (in->vb_uint32) {
        case FR_RADIUS_AUTH_SERV_CONFIG_RESET_VALUE_RESET:
                main_loop_signal_raise(RADIUS_SIGNAL_SELF_HUP);
                reset_time = fr_time();
                return 0;
 
        default:
                return -(FR_FREERADIUS_SNMP_FAILURE_VALUE_WRONG_VALUE);
        }
 
}
 
static int snmp_auth_stats_offset_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out,
                                      fr_snmp_map_t const *map, UNUSED void *snmp_ctx)
{
        fr_assert(map->da->type == FR_TYPE_UINT32);
 
        out->vb_uint32 = *(uint32_t *)((uint8_t *)(&radius_auth_stats) + map->offset);
 
        return 0;
}
 
static int snmp_client_index(UNUSED TALLOC_CTX *ctx, void **snmp_ctx_out,
                             UNUSED fr_snmp_map_t const *map,
                             NDEBUG_UNUSED void const *snmp_ctx_in, uint32_t index_num)
{
        fr_client_t *client;
 
        fr_assert(!snmp_ctx_in);
 
        client = client_findbynumber(NULL, index_num - 1);      /* Clients indexed from 0 */
        if (!client) return 1;          /* No more clients */
 
        *snmp_ctx_out = client;
 
        return 0;
}
 
static int snmp_client_index_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out,
                                 UNUSED fr_snmp_map_t const *map, void *snmp_ctx)
{
        fr_client_t *client = snmp_ctx;
 
        fr_assert(client);
 
        out->vb_uint32 = client->number + 1;            /* Clients indexed from 0 */
 
        return 0;
}
 
static int snmp_client_ipv4addr_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out,
                                    NDEBUG_UNUSED fr_snmp_map_t const *map, void *snmp_ctx)
{
        fr_client_t *client = snmp_ctx;
 
        fr_assert(client);
        fr_assert(map->da->type == FR_TYPE_IPV4_ADDR);
 
        /*
         *      The old SNMP MIB only allowed access
         *      to the IPv4 address.
         *
         *      The EXT mib allows access to either
         *      address.
         */
        if (client->ipaddr.af != AF_INET) return 0;
        memcpy(&out->vb_ip, &client->ipaddr, sizeof(out->vb_ip));
 
        return 0;
}
 
static int snmp_client_id_get(TALLOC_CTX *ctx, fr_value_box_t *out,
                              NDEBUG_UNUSED fr_snmp_map_t const *map, void *snmp_ctx)
{
        fr_client_t *client = snmp_ctx;
 
        fr_assert(client);
        fr_assert(map->da->type == FR_TYPE_STRING);
 
        fr_value_box_bstrdup_buffer(ctx, out, NULL, client->longname, false);
 
        return 0;
}
 
static int snmp_auth_client_stats_offset_get(UNUSED TALLOC_CTX *ctx, fr_value_box_t *out,
                                             fr_snmp_map_t const *map, void *snmp_ctx)
{
        fr_client_t *client = snmp_ctx;
 
        fr_assert(client);
        fr_assert(map->da->type == FR_TYPE_UINT32);
 
        out->vb_uint32 = *(uint32_t *)((uint8_t *)(&client->auth) + map->offset);
 
        return 0;
}
 
static fr_snmp_map_t snmp_auth_client_entry_counters[] = {
        { .name = "Radius-Auth-Client-Index",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_INTEGER,
          .get = snmp_client_index_get },
        { .name = "Radius-Auth-Client-Address",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_IPADDRESS,
          .get = snmp_client_ipv4addr_get },
        { .name = "Radius-Auth-Client-ID",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_STRING,
          .get = snmp_client_id_get },
        { .name = "Radius-Auth-Serv-Access-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_requests),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Dup-Access-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_dup_requests),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Access-Accepts",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_access_accepts),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Access-Rejects",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_access_rejects),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Access-Challenges",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_access_challenges),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Malformed-Access-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_malformed_requests),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Bad-Authenticators",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_bad_authenticators),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Packets-Dropped",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_packets_dropped),
          .get = snmp_auth_client_stats_offset_get },
        { .name = "Radius-Auth-Serv-Unknown-Types",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_unknown_types),
          .get = snmp_auth_client_stats_offset_get },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_auth_client_entry[] = {
        { .name = "Radius-Auth-Client-Entry",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .index = snmp_client_index,
          .child = snmp_auth_client_entry_counters },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_auth_serv_counters[] = {
        { .name = "Radius-Auth-Serv-Ident",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_STRING,
          .get = snmp_value_serv_ident_get },
        { .name = "Radius-Auth-Serv-Up-Time",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_TIMETICKS,
          .get = snmp_value_uptime_get },
        { .name = "Radius-Auth-Serv-Reset-Time",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_TIMETICKS,
          .get = snmp_config_reset_time_get},
        { .name = "Radius-Auth-Serv-Config-Reset",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_INTEGER,
          .get = snmp_config_reset_get,
          .set = snmp_config_reset_set },
        { .name = "Radius-Auth-Serv-Total-Access-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_requests),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Invalid-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_invalid_requests),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Dup-Access-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_dup_requests),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Access-Accepts",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_access_accepts),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Access-Rejects",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_access_rejects),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Access-Challenges",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_access_challenges),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Malformed-Access-Requests",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_malformed_requests),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Bad-Authenticators",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_bad_authenticators),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Packets-Dropped",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_packets_dropped),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Serv-Total-Unknown-Types",
          .type = FR_FREERADIUS_SNMP_TYPE_VALUE_COUNTER,
          .offset = offsetof(fr_stats_t, total_unknown_types),
          .get = snmp_auth_stats_offset_get },
        { .name = "Radius-Auth-Client-table",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_auth_client_entry},
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_auth_serv[] = {
        { .name = "Radius-Auth-Serv",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_auth_serv_counters },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_auth_serv_mib_objects[] = {
        { .name = "Radius-Auth-Serv-Mib-Objects",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_auth_serv },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_auth_serv_mib[] = {
        { .name = "Radius-Auth-Serv-Mib",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_auth_serv_mib_objects },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_authentication[] = {
        { .name = "Radius-Authentication",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_auth_serv_mib },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_radius_mib[] = {
        { .name = "Radius-Mib",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_authentication },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_mib_2[] = {
        { .name = "FreeRADIUS-Mib-2",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_radius_mib },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_mgmt[] = {
        { .name = "FreeRADIUS-Mgmt",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_mib_2 },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_internet[] = {
        { .name = "FreeRADIUS-Internet",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_mgmt },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_dod[] = {
        { .name = "FreeRADIUS-Dod",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_internet },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_org[] = {
        { .name = "FreeRADIUS-Org",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_dod },
        SNMP_MAP_TERMINATOR
};
 
static fr_snmp_map_t snmp_iso[] = {
        { .name = "FreeRADIUS-Iso",
          .type = FR_FREERADIUS_SNMP_TYPE_OBJECT,
          .child = snmp_org },
        SNMP_MAP_TERMINATOR
};
 
static ssize_t snmp_process(fr_dcursor_t *out, request_t *request,
                            fr_da_stack_t *da_stack, unsigned int depth,
                            fr_dcursor_t *cursor,
                            fr_snmp_map_t const *map, void *snmp_ctx, unsigned int snmp_op);
 
/** Perform a binary search to find a map matching a da
 *
 * @param map to search in.
 * @param da to search for.
 * @return
 *      - Matching map if da was found.
 *      - NULL if da was not found.
 */
static fr_snmp_map_t const *snmp_map_search(fr_snmp_map_t const map[], fr_dict_attr_t const *da)
{
        fr_snmp_map_t const *p = &map[1], *q = map[0].last, *m;
 
        fr_assert(p <= q);
 
        /*
         *      Fast path...
         */
        if (p == q) {
                fr_assert(p->da);
 
                if (p->da->attr == da->attr) return p;
                return NULL;
        }
 
        m = p + ((q - p) / 2);
 
        while (p <= q) {
                if (m->da->attr < da->attr) p = m + 1;
                else if (m->da->attr == da->attr) break;
                else q = m - 1;
                m = p + ((q - p) / 2);
        }
        if (p > q) return NULL;
 
        return m;
}
 
/** Perform depth first traversal of the tree until we hit a leaf node
 *
 * This is used for building a fake da_stack, for findNext, so that if
 * we get a findNext operation on something that's not a leaf, we can
 * find the first leaf under that branch of the tree.
 *
 * @param[out] da_stack to rewrite.
 * @param[in] depth at which to start rewriting.
 * @param[in] map at this level.
 */
static void snmp_next_leaf(fr_da_stack_t *da_stack, unsigned int depth, fr_snmp_map_t const *map)
{
        uint32_t i;
        fr_snmp_map_t const *map_p = map;
 
        for (i = depth; (i < FR_DICT_MAX_TLV_STACK) && map_p; i++) {
                da_stack->da[i] = map_p->da;
                map_p = map_p->child;
        }
        da_stack->depth = i;
}
 
static ssize_t snmp_process_index(fr_dcursor_t *out, request_t *request,
                                  fr_da_stack_t *da_stack, unsigned int depth,
                                  fr_dcursor_t cursor,
                                  fr_snmp_map_t const *map, void *snmp_ctx, unsigned int snmp_op,
                                  uint32_t index_num)
{
        ssize_t         ret;
        uint32_t        i;
 
        /*
         *      Can't modify snmp_ctx, as we may need to go back up
         *      the stack, and retry when performing a getNext.
         */
        void            *this_snmp_ctx = NULL;
        TALLOC_CTX      *tmp_ctx;
 
        for (i = index_num; i < UINT32_MAX; i++) {
                fr_dict_attr_t const    *da;
                fr_pair_t               *vp;
 
                tmp_ctx = talloc_new(request);
                if (!tmp_ctx) {
                        fr_strerror_const("Out Of Memory");
                        return -(depth);
                }
 
                ret = map->index(tmp_ctx, &this_snmp_ctx, map, snmp_ctx, i);
                if (ret < 0) {
                        talloc_free(tmp_ctx);
                        return ret;             /* error */
                }
                if (ret > 0) {
                        talloc_free(tmp_ctx);
 
                        if (snmp_op != FR_FREERADIUS_SNMP_OPERATION_VALUE_GETNEXT) {
                        invalid:
                                fr_strerror_const("Invalid OID: Match stopped here");
                                return -(depth);
                        }
 
                        return ret;             /* no more entries at this level, findNext at lower level */
                }
 
                ret = snmp_process(out, request,
                                   da_stack, depth + 1,
                                   &cursor,
                                   map->child, this_snmp_ctx, snmp_op);
                TALLOC_FREE(tmp_ctx);
 
                if (ret < 0) return ret;        /* error */
                if (ret > 0) {                  /* findNext */
                        if (snmp_op != FR_FREERADIUS_SNMP_OPERATION_VALUE_GETNEXT) goto invalid;
 
                        /*
                         *      Rebuild the stack to point to the first
                         *      leaf (usually .1) of the entry.
                         *
                         *      If we've unwound to this level then we're
                         *      going to try again with a new entry.
                         *      We need to start at the start of that
                         *      entry, not at the end (where we previously
                         *      were).
                         */
                        fr_proto_da_stack_build(da_stack, map->da);
                        this_snmp_ctx = NULL;
                        continue;
                }
 
                /*
                 *      Success! - Build and prepend an index
                 *      attribute to let the client know which entry
                 *      we processed.
                 */
                da = fr_dict_attr_child_by_num(map->da->parent, 0);
                if (!da) {
                        fr_strerror_printf("No index attribute defined for \"%s\"", map->name);
                        return -(depth);
                }
 
                MEM(vp = fr_pair_afrom_da(request->reply_ctx, da));
                vp->vp_uint32 = i;
                fr_dcursor_prepend(out, vp);
 
                return 0;                       /* done */
        }
 
        fr_strerror_const("Invalid OID: Hit max index");
 
        return -(depth);
}
 
static ssize_t snmp_process_index_attr(fr_dcursor_t *out, request_t *request,
                                       fr_da_stack_t *da_stack, unsigned int depth,
                                       fr_dcursor_t *cursor,
                                       fr_snmp_map_t const *map, void *snmp_ctx, unsigned int snmp_op)
{
        fr_pair_t       *next;
        uint32_t        index_num;
        fr_pair_t       *vp;
 
        FR_PROTO_STACK_PRINT(da_stack, depth);
 
        if (map[0].last < &map[1]) {
                fr_strerror_const("Invalid OID: Empty map");
        error:
                return -(ssize_t)depth;
        }
 
        if (map[1].type != FR_FREERADIUS_SNMP_TYPE_OBJECT) {
                fr_strerror_const("Invalid OID: Cannot traverse leaf");
                goto error;
        }
 
        if (!map[1].index) {
                fr_strerror_printf("Invalid OID: Got index attribute, but SNMP object is not "
                                   "a table entry");
                goto error;
        }
 
        if (da_stack->da[depth]->type != FR_TYPE_UINT32) {
                fr_strerror_printf("Bad index attribute: Index attribute \"%s\" should be a integer, "
                                   "but is a %s", da_stack->da[depth]->name,
                                   fr_type_to_str(da_stack->da[depth]->type));
                goto error;
        }
 
        /*
         *      Get the index from the index attribute's value.
         */
        vp = fr_dcursor_current(cursor);
        index_num = vp->vp_uint32;
 
        /*
         *      Advance the cursor to the next index attribute
         *      if it is an index attribute...
         */
        next = fr_dcursor_next_peek(cursor);
        if (next && fr_dict_attr_common_parent(vp->da, next->da, true)) {
                fr_proto_da_stack_build(da_stack, next->da);
 
                while ((next = fr_dcursor_next(cursor))) if (fr_dict_attr_common_parent(vp->da, next->da, true)) break;
        }
 
        return snmp_process_index(out, request,
                                  da_stack, depth,
                                  *cursor,
                                  &map[1], snmp_ctx, snmp_op,
                                  index_num);
}
 
static ssize_t snmp_process_tlv(fr_dcursor_t *out, request_t *request,
                                fr_da_stack_t *da_stack, unsigned int depth,
                                fr_dcursor_t *cursor,
                                fr_snmp_map_t const *map, void *snmp_ctx, unsigned int snmp_op)
{
        fr_snmp_map_t const     *map_p;
        ssize_t                 ret;
 
        FR_PROTO_STACK_PRINT(da_stack, depth);
 
        /*
         *      Return element in map that matches the da at this
         *      level in the da_stack.
         */
        map_p = snmp_map_search(map, da_stack->da[depth]);
        if (!map_p) {
        invalid:
                fr_strerror_const("Invalid OID: Match stopped here");
        error:
                return -(ssize_t)depth;
        }
 
        if (!map_p->child) {
                fr_strerror_const("Internal error: Dictionary and SNMP map structure mismatch");
                goto error;
        }
 
        /*
         *      Allow for attributes that represent fixed indexes
         *      usually *-Entry attributes.
         *
         *      This allows a complete SNMP OID to be represented
         *      as a single attribute (with index 1 being used for
         *      each traversal).
         *
         *      The real purpose is to allow the fake da_stack
         *      code to work correctly without needing to add
         *      fake index attributes
         */
        if (map_p->index) {
                return snmp_process_index(out, request,
                                          da_stack, depth,
                                          *cursor,
                                          map_p, snmp_ctx, snmp_op,
                                          da_stack->da[depth]->attr);
        }
 
        for (;;) {
                ret = snmp_process(out, request,
                                   da_stack, depth + 1,
                                   cursor,
                                   map_p->child, snmp_ctx, snmp_op);
                if (ret < 0) return ret;        /* error */
                if (ret > 0) {                  /* findNext */
                        if (snmp_op != FR_FREERADIUS_SNMP_OPERATION_VALUE_GETNEXT) goto invalid;
                        if (++map_p <= map[0].last) continue;
                        return 1;               /* findNext at lower level */
                }
                return 0;                       /* done */
        }
}
 
static ssize_t snmp_process_leaf(fr_dcursor_t *out, request_t *request,
                                 fr_da_stack_t *da_stack, unsigned int depth,
                                 fr_dcursor_t *cursor,
                                 fr_snmp_map_t const *map, void *snmp_ctx, unsigned int snmp_op)
{
        fr_pair_t               *vp;
        fr_snmp_map_t const     *map_p;
 
        FR_PROTO_STACK_PRINT(da_stack, depth);
 
        vp = fr_dcursor_current(cursor);
 
        /*
         *      Return element in map that matches the da at this
         *      level in the da_stack.
         */
        map_p = snmp_map_search(map, da_stack->da[depth]);
        if (!map_p) {
                fr_strerror_const("Invalid OID: Match stopped here");
        error:
                return -(ssize_t)depth;
        }
 
        /*
         *      It's a leaf attribute, call the correct get/set function
         */
        switch (snmp_op) {
        case FR_FREERADIUS_SNMP_OPERATION_VALUE_GETNEXT:
                if (map_p == map[0].last) {
                        return 1;       /* findNext at lower level */
                }
                if (map_p->da == vp->da) {              /* Next unless we faked part of the stack */
                        map_p++;
 
                        /*
                         *      We were called with a leaf map, but advanced
                         *      to a non-leaf map.
                         */
                        if (map_p->type == FR_FREERADIUS_SNMP_TYPE_OBJECT) {
                                return snmp_process(out, request,
                                                    da_stack, depth + 1,
                                                    cursor,
                                                    map_p->child, snmp_ctx, snmp_op);
                        }
                }
                FALL_THROUGH;
 
        case FR_FREERADIUS_SNMP_OPERATION_VALUE_GET:
        {
                fr_value_box_t data = (fr_value_box_t) {};
 
                /*
                 *      Verify map is a leaf
                 */
                if (map_p->type == FR_FREERADIUS_SNMP_TYPE_OBJECT) {
                        fr_strerror_const("Invalid OID: Is not a leaf node");
                        goto error;
                }
 
                if (!map_p->get) {
                        fr_strerror_const("Invalid operation: Node does not support GET operations");
                        goto error;
                }
 
                /*
                 *      Get functions can only return a single
                 *      attribute.  To reduce boilerplate code
                 *      in callbacks, we handled allocating and
                 *      inserting fr_pair_ts, and pass in a
                 *      fr_value_box_t struct for the callback
                 *      to complete.
                 */
                if (map_p->get(request->reply, &data, map_p, snmp_ctx) < 0) goto error;
 
                MEM(vp = fr_pair_afrom_da(request->reply_ctx, map_p->da));
                fr_value_box_steal(vp, &vp->data, &data);
                fr_dcursor_append(out, vp);
 
                MEM(vp = fr_pair_afrom_da(request->reply_ctx, attr_snmp_type));
                vp->vp_uint32 = map_p->type;
                fr_dcursor_append(out, vp);
        }
                return 0;
 
        case FR_FREERADIUS_SNMP_OPERATION_VALUE_SET:
        {
                ssize_t ret;
 
                if (!map_p->set || (map_p->type == FR_FREERADIUS_SNMP_TYPE_OBJECT)) {
                        MEM(vp = fr_pair_afrom_da(request->reply_ctx, attr_snmp_failure));
                        vp->vp_uint32 = FR_FREERADIUS_SNMP_FAILURE_VALUE_NOT_WRITABLE;
                        fr_dcursor_append(out, vp);
                        return 0;
                }
 
                vp = fr_dcursor_current(cursor);
                ret = map_p->set(map_p, snmp_ctx, &vp->data);
                if (ret < 0) switch (-(ret)) {
                case FR_FREERADIUS_SNMP_FAILURE_VALUE_NOT_WRITABLE:
                case FR_FREERADIUS_SNMP_FAILURE_VALUE_WRONG_TYPE:
                case FR_FREERADIUS_SNMP_FAILURE_VALUE_WRONG_LENGTH:
                case FR_FREERADIUS_SNMP_FAILURE_VALUE_WRONG_VALUE:
                case FR_FREERADIUS_SNMP_FAILURE_VALUE_INCONSISTENT_VALUE:
                        MEM(vp = fr_pair_afrom_da(request->reply_ctx, attr_snmp_failure));
                        vp->vp_uint32 = -(ret);
                        fr_dcursor_append(out, vp);
                        break;
 
                default:
                        goto error;
                }
        }
                return 0;
 
        default:
                fr_assert(0);
                goto error;
        }
}
 
/** Traverse a tree of SNMP maps
 *
 * @param[out] out              Where to write response attributes.
 * @param[in] request           The current request.
 * @param[in,out] da_stack      we're traversing.
 * @param[in] depth             we're currently at in the da_stack.
 * @param[in] cursor            representing the current attribute we're processing.
 * @param[in] map               matching the current depth in the da_stack.
 * @param[in] snmp_ctx          allocated by the previous index traversal function.
 * @param[in] snmp_op           we're performing.
 * @return
 *      - 0 on success.
 *      - 1 to signal caller that it should find the next OID at this level
 *      and recurse again.
 *      - <0 the depth at which an error occurred, as a negative integer.
 */
static ssize_t snmp_process(fr_dcursor_t *out, request_t *request,
                            fr_da_stack_t *da_stack, unsigned int depth,
                            fr_dcursor_t *cursor,
                            fr_snmp_map_t const *map, void *snmp_ctx, unsigned int snmp_op)
{
        fr_assert(map);
 
        FR_PROTO_STACK_PRINT(da_stack, depth);
 
        /*
         *      We've run out of stack... This is an error unless
         *      we're performing a getNext operation, in which
         *      case we fake the rest of the stack.
         */
        if (!da_stack->da[depth]) {
                if (snmp_op != FR_FREERADIUS_SNMP_OPERATION_VALUE_GETNEXT) {
                        fr_strerror_const("Invalid OID: Not a leaf");
                        return -(ssize_t)(depth - 1);
                }
                snmp_next_leaf(da_stack, depth, &map[1]);
 
                if (!fr_cond_assert(da_stack->da[depth])) return -1;
        }
 
        /*
         *      It's an index attribute, use the value of
         *      the index attribute to traverse the index.
         */
        if (da_stack->da[depth]->attr == 0) return snmp_process_index_attr(out, request,
                                                                           da_stack, depth,
                                                                           cursor,
                                                                           map, snmp_ctx, snmp_op);
 
        /*
         *      It's a TLV, recurse, and locate the map
         *      matching the next deepest DA in the
         *      da_stack.
         */
        if (da_stack->da[depth]->type == FR_TYPE_TLV) return snmp_process_tlv(out, request,
                                                                              da_stack, depth,
                                                                              cursor,
                                                                              map, snmp_ctx, snmp_op);
 
        /*
         *      Must be a leaf, call the appropriate get/set function
         *      and create attributes for the response.
         */
        return snmp_process_leaf(out, request,
                                 da_stack, depth,
                                 cursor,
                                 map, snmp_ctx, snmp_op);
}
 
int fr_snmp_process(request_t *request)
{
        fr_dcursor_t            request_cursor, op_cursor, out_cursor, reply_cursor;
        fr_pair_list_t          head;
        fr_pair_t               *vp;
 
        char                    oid_str[FR_DICT_MAX_TLV_STACK * 4];     /* .<num>{1,3} */
        size_t                  oid_len, len;
 
        fr_da_stack_t           da_stack;
        unsigned int            depth;
        ssize_t                 ret;
 
        fr_pair_t               *op;
 
        fr_pair_list_init(&head);
        fr_pair_dcursor_init(&request_cursor, &request->request_pairs);
        fr_pair_dcursor_by_da_init(&op_cursor, &request->request_pairs, attr_snmp_operation);
        fr_pair_dcursor_init(&reply_cursor, &request->reply_pairs);
        fr_pair_dcursor_init(&out_cursor, &head);
 
        RDEBUG2("Processing SNMP stats request");
 
        /*
         *      First take a pass over the request, converting
         *      any unknown types back to real attributes.
         *
         *      This hack is required because empty TLVs are
         *      not allowed in the RADIUS protocol, so we
         *      encode the TLV as an octet type attribute
         */
        for (vp = fr_dcursor_head(&request_cursor);
             vp;
             vp = fr_dcursor_next(&request_cursor)) {
                fr_dict_attr_t const *da;
 
                if (!vp->da->flags.is_unknown) continue;
 
                da = fr_dict_attr_unknown_resolve(NULL, vp->da);
                if (!da) {
                        WARN("Failed converting \"%s\" to a known attribute", vp->da->name);
                        continue;
                }
 
                RDEBUG2("Unknown attribute \"%s\" resolves to \"%s\"", vp->da->name, da->name);
 
                /*
                 *      Clear out any junk values
                 */
                if (da->type == FR_TYPE_TLV) fr_value_box_clear(&vp->data);
 
                if (fr_pair_reinit_from_da(&request->request_pairs, vp, da) < 0) {
                        RPWARN("Failed converting unknown attribute to known attribute");
                        continue;
                }
        }
 
        for (vp = fr_pair_dcursor_by_ancestor_init(&request_cursor, &request->request_pairs, attr_snmp_root);
             vp;
             vp = fr_dcursor_next(&request_cursor)) {
                fr_proto_da_stack_build(&da_stack, vp->da);
 
                /*
                 *      Wind to the frame in the TLV stack that matches our
                 *      SNMP root.
                 */
                for (depth = 0; da_stack.da[depth]; depth++) if (attr_snmp_root == da_stack.da[depth]) break;
 
                /*
                 *      Any attribute returned by fr_dcursor_next_by_ancestor
                 *      should have the SNMP root attribute as an ancestor.
                 */
                fr_assert(da_stack.da[depth]);
                fr_assert(da_stack.da[depth] == attr_snmp_root);
 
                /*
                 *      Operator attribute acts as a request delimiter
                 */
                op = fr_dcursor_current(&op_cursor);
                if (!op) {
                        ERROR("Missing operation (%s)", attr_snmp_operation->name);
                        return -1;
                }
                fr_dcursor_next(&op_cursor);
 
                switch (op->vp_uint32) {
                case FR_FREERADIUS_SNMP_OPERATION_VALUE_PING:
                case FR_FREERADIUS_SNMP_OPERATION_VALUE_GET:
                case FR_FREERADIUS_SNMP_OPERATION_VALUE_GETNEXT:
                case FR_FREERADIUS_SNMP_OPERATION_VALUE_SET:
                        break;
 
                default:
                        ERROR("Invalid operation %u", vp->vp_uint32);
                        return -1;
                }
 
                /*
                 *      Returns depth (as negative integer) at which the error occurred
                 */
                ret = snmp_process(&out_cursor, request,
                                   &da_stack, depth,
                                   &request_cursor,
                                   snmp_iso, NULL, op->vp_uint32);
                if (ret < 0) {
                        fr_sbuff_t      oid_str_sbuff = FR_SBUFF_OUT(oid_str, sizeof(oid_str));
                        fr_pair_list_free(&head);
 
                        (void) fr_sbuff_in_char(&oid_str_sbuff, '.');
 
                        /* Get the length of the matching part */
                        oid_len = fr_dict_attr_oid_print(&oid_str_sbuff, attr_snmp_root, da_stack.da[-(ret)], false);
 
                        /* Get the last frame in the current stack */
                        len = fr_dict_attr_oid_print(&oid_str_sbuff, attr_snmp_root,
                                                     da_stack.da[da_stack.depth - 1], false);
 
                        /* Use the difference in OID string length to place the marker */
                        REMARKER(oid_str, oid_len - (len - oid_len), "%s", fr_strerror());
 
                        return -1;
                }
        }
 
        fr_dcursor_head(&out_cursor);
        fr_dcursor_merge(&reply_cursor, &out_cursor);
 
        return 0;
}
 
/** Internal SNMP initialisation function (used for recursion)
 *
 */
static int _fr_snmp_init_r(fr_snmp_map_t map[], fr_dict_attr_t const *parent)
{
        unsigned int i;
 
        for (i = 0; map[i].name; i++) {
                if (map[i].type == FR_FREERADIUS_SNMP_TYPE_OBJECT) {
                        int ret;
 
                        fr_assert(map[i].child);
 
                        map[i].da = fr_dict_attr_by_name(NULL, parent, map[i].name);
                        if (!map[i].da) {
                                ERROR("Incomplete dictionary: Missing definition for \"%s\"", map[i].name);
                                return -1;
                        }
 
                        ret = _fr_snmp_init_r(map[i].child, map[i].da);
                        if (ret < 0) return -1;
 
                        continue;
                }
 
                map[i].da = fr_dict_attr_by_name(NULL, parent, map[i].name);
                if (!map[i].da) {
                        ERROR("Incomplete dictionary: Missing definition for \"%s\"", map[i].name);
                        return -1;
                }
        }
 
        /*
         *      Shift the contents of the map, clearing the first entry.
         *
         *      @note We could also do a quicksort here but we assume
         *      that future developers will heed this warning to list
         *      attributes in ascending order.
         */
        memmove(&map[1], map, sizeof(*map) * i);
        memset(&map[0], 0, sizeof(*map));
        map[0].name = "Not the map offset you were looking for";
        map[0].last = &map[i];  /* This allows us to perform a binary search in the array */
 
        return 0;
}
static int _fr_snmp_init(UNUSED void *uctx)
{
        start_time = fr_time();
        reset_time = start_time;
 
        if (fr_dict_autoload(snmp_dict) < 0) {
                fr_perror("snmp_init");
                return -1;
        }
 
        if (fr_dict_attr_autoload(snmp_dict_attr) < 0) {
                fr_perror("snmp_init");
                return -1;
        }
 
        return _fr_snmp_init_r(snmp_iso, fr_dict_root(dict_snmp));      /* The SNMP root node */
}
 
static int _fr_snmp_free(UNUSED void *uctx)
{
        fr_dict_autofree(snmp_dict);
 
        return 0;
}
 
/** Initialise the tree of SNMP map structures used to attach callbacks to OIDs
 *
 */
int fr_snmp_init(void)
{
        int ret;
 
        fr_atexit_global_once_ret(&ret, _fr_snmp_init, _fr_snmp_free, NULL);
 
        return ret;
}