referral.c

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/*
 *   This program is 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: 202481613a47404389e4d4f9c22afbc90abe0e2c $
 * @file lib/ldap/referral.c
 * @brief Functions to handle ldap referrals
 *
 * @author Nick Porter <nick.porter@networkradius.com>
 * @copyright 2021 The FreeRADIUS Server Project.
 */
RCSID("$Id: 202481613a47404389e4d4f9c22afbc90abe0e2c $")
 
#include <freeradius-devel/ldap/base.h>
 
 
/** Clear up a fr_ldap_referral_t
 *
 * If there is a parsed referral_url, that must be freed using libldap's ldap_free_urldesc
 */
static int _fr_ldap_referral_free(fr_ldap_referral_t *referral)
{
        if (referral->referral_url) ldap_free_urldesc(referral->referral_url);
        if (referral->host_uri) ldap_memfree(referral->host_uri);
        return 0;
}
 
/** Allocate a new structure to handle an LDAP referral, setting the destructor
 *
 * @param[in] ctx       to allocate the referral in
 * @param[in] request   the LDAP query relates to.
 * @return
 *      - a new referral structure on success
 *      - NULL on failure
 */
fr_ldap_referral_t *fr_ldap_referral_alloc(TALLOC_CTX *ctx, request_t *request)
{
        fr_ldap_referral_t      *referral;
 
        referral = talloc_zero(ctx, fr_ldap_referral_t);
        if (!referral) {
                PERROR("Failed to allocate LDAP referral container");
                return NULL;
        }
        referral->request = request;
        talloc_set_destructor(referral, _fr_ldap_referral_free);
 
        return referral;
}
 
/** Callback to send LDAP referral queries when a trunk becomes active
 *
 */
static void _ldap_referral_send(UNUSED fr_trunk_t *trunk, UNUSED fr_trunk_state_t prev,
                                UNUSED fr_trunk_state_t state, void *uctx)
{
        fr_ldap_referral_t      *referral = talloc_get_type_abort(uctx, fr_ldap_referral_t);
        fr_ldap_query_t         *query = referral->query;
        request_t               *request = referral->request;
 
        /*
         *      If referral is set, then another LDAP trunk has gone active first and sent the referral
         */
        if (query->referral) return;
 
        /*
         *      Enqueue referral query on active trunk connection
         */
        query->referral = referral;
        switch (fr_trunk_request_enqueue(&query->treq, referral->ttrunk->trunk, request, query, NULL)) {
        case FR_TRUNK_ENQUEUE_OK:
        case FR_TRUNK_ENQUEUE_IN_BACKLOG:
                break;
 
        default:
                ROPTIONAL(RERROR, ERROR, "Failed enqueueing pending LDAP referral");
                query->ret = LDAP_RESULT_ERROR;
                if (request) unlang_interpret_mark_runnable(request);
                return;
        }
 
        ROPTIONAL(RDEBUG3, DEBUG3, "Pending LDAP referral query queued on active trunk");
}
 
 
/** Follow an LDAP referral
 *
 * The returned list of LDAP referrals should already be in query->referrals.
 * We check all the possible referrals and look for one where there already
 * is an active trunk connection.
 *
 * @param t             Thread running the query.
 * @param request       related to the query.
 * @param query         whose result was one or more referral URLs.
 * @return
 *      - 0 on success.
 *      - < 0 on failure.
 */
int fr_ldap_referral_follow(fr_ldap_thread_t *t, request_t *request, fr_ldap_query_t *query)
{
        fr_ldap_config_t        *config = t->config;
        fr_ldap_thread_trunk_t  *ttrunk = NULL;
        int                     referral_no = -1;
        fr_ldap_referral_t      *referral;
        LDAPURLDesc             temp_desc;
 
        fr_trunk_request_signal_complete(query->treq);
        query->treq = NULL;
 
        if (query->referral_depth > 1) {
        /*
         *      If we've already parsed a referral, clear the existing list of followers.
         */
                fr_dlist_talloc_free(&query->referrals);
                query->referral = NULL;
        } else {
        /*
         *      Otherwise initialise the list header for followers.
         */
                fr_dlist_talloc_init(&query->referrals, fr_ldap_referral_t, entry);
        }
 
        while (query->referral_urls[++referral_no]) {
                if (!ldap_is_ldap_url(query->referral_urls[referral_no])) {
                        ROPTIONAL(RERROR, ERROR, "Referral %s does not look like an LDAP URL",
                                  query->referral_urls[referral_no]);
                        continue;
                }
 
                referral = fr_ldap_referral_alloc(query, request);
                if (!referral) continue;
 
                referral->query = query;
 
                if (ldap_url_parse(query->referral_urls[referral_no], &referral->referral_url)) {
                        ROPTIONAL(RERROR, ERROR,
                                  "Failed parsing referral LDAP URL %s", query->referral_urls[referral_no]);
                free_referral:
                        talloc_free(referral);
                        continue;
                }
 
                temp_desc = (LDAPURLDesc){
                        .lud_scheme = referral->referral_url->lud_scheme,
                        .lud_host = referral->referral_url->lud_host,
                        .lud_port = referral->referral_url->lud_port,
                        .lud_scope = -1
                };
                referral->host_uri = ldap_url_desc2str(&temp_desc);
                if (!referral->host_uri) {
                        ROPTIONAL(RERROR, ERROR,
                                 "Failed building LDAP host URI from %s", query->referral_urls[referral_no]);
                }
 
                if (config->use_referral_credentials) {
                        char    **ext;
 
                        /*
                         *      If there are no extensions, OpenLDAP doesn't
                         *      bother allocating an array.
                         */
                        for (ext = referral->referral_url->lud_exts; ext && *ext; ext++) {
                                char const *p;
                                bool critical = false;
 
                                p = *ext;
 
                                if (*p == '!') {
                                        critical = true;
                                        p++;
                                }
 
                                /*
                                 *      LDAP Parse URL unescapes the extensions for us
                                 */
                                switch (fr_table_value_by_substr(fr_ldap_supported_extensions, p, -1, LDAP_EXT_UNSUPPORTED)) {
                                case LDAP_EXT_BINDNAME:
                                        p = strchr(p, '=');
                                        if (!p) {
                                        bad_ext:
                                                ROPTIONAL(RERROR, ERROR,
                                                          "Failed parsing extension \"%s\": "
                                                          "No attribute/value delimiter '='", *ext);
                                                goto free_referral;
                                        }
                                        referral->identity = p + 1;
                                        break;
 
                                case LDAP_EXT_BINDPW:
                                        p = strchr(p, '=');
                                        if (!p) goto bad_ext;
                                        referral->password = p + 1;
                                        break;
 
                                default:
                                        if (critical) {
                                                ROPTIONAL(RERROR, ERROR,
                                                          "Failed parsing critical extension \"%s\": "
                                                          "Not supported by FreeRADIUS", *ext);
                                                goto free_referral;
                                        }
                                        ROPTIONAL(RDEBUG2, DEBUG2, "Skipping unsupported extension \"%s\"", *ext);
                                        continue;
                                }
                        }
                } else {
                        if (config->rebind) {
                                referral->identity = config->admin_identity;
                                referral->password = config->admin_password;
                        }
                }
 
                fr_dlist_insert_tail(&query->referrals, referral);
                if (fr_thread_ldap_trunk_state(t, referral->host_uri,
                                               referral->identity) != FR_TRUNK_STATE_ACTIVE) {
                        ROPTIONAL(RDEBUG3, DEBUG3,
                                  "No active LDAP trunk for URI %s, bound as %s",
                                  referral->host_uri, referral->identity);
                        continue;
                }
 
                ttrunk = fr_thread_ldap_trunk_get(t, referral->host_uri, referral->identity,
                                                  referral->password, request, config);
 
                if (!ttrunk) {
                        ROPTIONAL(RERROR, ERROR, "Unable to connect to LDAP referral URL");
                        fr_dlist_talloc_free_item(&query->referrals, referral);
                        continue;
                }
 
                /*
                 *      We have an active trunk enqueue the request
                 */
                query->referral = referral;
                switch (fr_trunk_request_enqueue(&query->treq, ttrunk->trunk, request, query, NULL)) {
                case FR_TRUNK_ENQUEUE_OK:
                case FR_TRUNK_ENQUEUE_IN_BACKLOG:
                        break;
 
                default:
                        ROPTIONAL(RERROR, ERROR, "Failed to enqueue request for referral");
                        goto free_referral;
                }
                return 0;
        }
 
        /*
         *      None of the referrals parsed successfully
         */
        if (fr_dlist_num_elements(&query->referrals) == 0) {
                ROPTIONAL(RERROR, ERROR, "No valid LDAP referrals to follow");
                return -1;
        }
 
        /*
         *      We have parsed referrals, but none of them matched an existing active connection.
         *      Launch new trunks with callbacks so the first to become active will run the query.
         */
        referral = NULL;
        while ((referral = fr_dlist_next(&query->referrals, referral))) {
                ttrunk = fr_thread_ldap_trunk_get(t, referral->host_uri, referral->identity,
                                                  referral->password, request, config);
                if (!ttrunk) {
                        fr_dlist_talloc_free_item(&query->referrals, referral);
                        continue;
                }
                referral->ttrunk = ttrunk;
                fr_trunk_add_watch(ttrunk->trunk, FR_TRUNK_STATE_ACTIVE, _ldap_referral_send, true, referral);
                ROPTIONAL(RDEBUG4, DEBUG4, "Watch inserted to send referral query on active trunk");
        }
 
        return 0;
}
 
/** Follow an alternative LDAP referral
 *
 * If an initial chase of an LDAP referral results in an error being returned
 * this function can be used to attempt one of the other referral URLs given
 * in the initial query results.
 *
 * The initial use of fr_ldap_referral_follow may have launched trunks for
 * any referral URLs which parsed successfully, so this starts by looking
 * for the first which has an active state and sends the query that way.
 *
 * If no active trunks match the remaining servers listed in referrals then
 * new trunks are launched with watchers to send the query on the first
 * active trunk.
 *
 * @param t             Thread running the query.
 * @param request       the query relates to.
 * @param query         whose referrals are being chased.
 * @return
 *      - 0 on success.
 *      - < 0 on failure.
 */
int fr_ldap_referral_next(fr_ldap_thread_t *t, request_t *request, fr_ldap_query_t *query)
{
        fr_ldap_config_t        *config = t->config;
        fr_ldap_referral_t      *referral = NULL;
        fr_ldap_thread_trunk_t  *ttrunk;
 
        fr_trunk_request_signal_complete(query->treq);
        query->treq = NULL;
 
        while ((referral = fr_dlist_next(&query->referrals, referral))) {
                if (fr_thread_ldap_trunk_state(t, referral->host_uri,
                                               referral->identity) != FR_TRUNK_STATE_ACTIVE) {
                        ROPTIONAL(RDEBUG3, DEBUG3, "No active LDAP trunk for URI %s, bind DN %s",
                                  referral->host_uri, referral->identity);
                        continue;
                }
 
                ttrunk = fr_thread_ldap_trunk_get(t, referral->host_uri, referral->identity,
                                                  referral->password, request, config);
 
                if (!ttrunk) {
                        ROPTIONAL(RERROR, ERROR, "Unable to connect to LDAP referral URL");
                        fr_dlist_talloc_free_item(&query->referrals, referral);
                        continue;
                }
 
                /*
                 *      We have an active trunk enqueue the request
                 */
                query->referral = referral;
                switch(fr_trunk_request_enqueue(&query->treq, ttrunk->trunk, request, query, NULL)) {
                case FR_TRUNK_ENQUEUE_OK:
                case FR_TRUNK_ENQUEUE_IN_BACKLOG:
                        break;
 
                default:
                        ROPTIONAL(RERROR, ERROR, "Failed to enqueue request for referral");
                        continue;
                }
                return 0;
        }
 
        /*
         *      None of the referrals parsed successfully
         */
        if (fr_dlist_num_elements(&query->referrals) == 0) {
                ROPTIONAL(RERROR, ERROR, "No valid LDAP referrals to follow");
                return -1;
        }
 
        /*
         *      None of the remaining referrals have an active trunk.
         *      Launch new trunks with callbacks so the first to become active will run the query.
         */
        referral = NULL;
        while ((referral = fr_dlist_next(&query->referrals, referral))) {
                ttrunk = fr_thread_ldap_trunk_get(t, referral->host_uri, referral->identity,
                                                  referral->password, request, config);
                if (!ttrunk) {
                        fr_dlist_talloc_free_item(&query->referrals, referral);
                        continue;
                }
                referral->ttrunk = ttrunk;
                fr_trunk_add_watch(ttrunk->trunk, FR_TRUNK_STATE_ACTIVE, _ldap_referral_send, true, referral);
                ROPTIONAL(RDEBUG4, DEBUG4, "Watch inserted to send referral query on active trunk");
        }
 
        return 0;
}