X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fwide-area.c;fp=src%2Fwide-area.c;h=d5237d32142333aae6333ff0a7f5842167e89686;hb=f1de9dcaab953757252d51b4725cbfa36daa10a5;hp=0000000000000000000000000000000000000000;hpb=7a5b2f69af7d36d6cd4153142f125fa011784e03;p=catta

diff --git a/src/wide-area.c b/src/wide-area.c
new file mode 100644
index 0000000..d5237d3
--- /dev/null
+++ b/src/wide-area.c
@@ -0,0 +1,723 @@
+/***
+  This file is part of catta.
+
+  catta is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  catta 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 Lesser General
+  Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with catta; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <netinet/in.h>
+
+#include <catta/malloc.h>
+#include <catta/error.h>
+#include <catta/timeval.h>
+
+#include "internal.h"
+#include "browse.h"
+#include "socket.h"
+#include <catta/log.h>
+#include "hashmap.h"
+#include "wide-area.h"
+#include "addr-util.h"
+#include "rr-util.h"
+
+#define CACHE_ENTRIES_MAX 500
+
+typedef struct CattaWideAreaCacheEntry CattaWideAreaCacheEntry;
+
+struct CattaWideAreaCacheEntry {
+    CattaWideAreaLookupEngine *engine;
+
+    CattaRecord *record;
+    struct timeval timestamp;
+    struct timeval expiry;
+
+    CattaTimeEvent *time_event;
+
+    CATTA_LLIST_FIELDS(CattaWideAreaCacheEntry, by_key);
+    CATTA_LLIST_FIELDS(CattaWideAreaCacheEntry, cache);
+};
+
+struct CattaWideAreaLookup {
+    CattaWideAreaLookupEngine *engine;
+    int dead;
+
+    uint32_t id;  /* effectively just an uint16_t, but we need it as an index for a hash table */
+    CattaTimeEvent *time_event;
+
+    CattaKey *key, *cname_key;
+
+    int n_send;
+    CattaDnsPacket *packet;
+
+    CattaWideAreaLookupCallback callback;
+    void *userdata;
+
+    CattaAddress dns_server_used;
+
+    CATTA_LLIST_FIELDS(CattaWideAreaLookup, lookups);
+    CATTA_LLIST_FIELDS(CattaWideAreaLookup, by_key);
+};
+
+struct CattaWideAreaLookupEngine {
+    CattaServer *server;
+
+    int fd_ipv4, fd_ipv6;
+    CattaWatch *watch_ipv4, *watch_ipv6;
+
+    uint16_t next_id;
+
+    /* Cache */
+    CATTA_LLIST_HEAD(CattaWideAreaCacheEntry, cache);
+    CattaHashmap *cache_by_key;
+    unsigned cache_n_entries;
+
+    /* Lookups */
+    CATTA_LLIST_HEAD(CattaWideAreaLookup, lookups);
+    CattaHashmap *lookups_by_id;
+    CattaHashmap *lookups_by_key;
+
+    int cleanup_dead;
+
+    CattaAddress dns_servers[CATTA_WIDE_AREA_SERVERS_MAX];
+    unsigned n_dns_servers;
+    unsigned current_dns_server;
+};
+
+static CattaWideAreaLookup* find_lookup(CattaWideAreaLookupEngine *e, uint16_t id) {
+    CattaWideAreaLookup *l;
+    int i = (int) id;
+
+    assert(e);
+
+    if (!(l = catta_hashmap_lookup(e->lookups_by_id, &i)))
+        return NULL;
+
+    assert(l->id == id);
+
+    if (l->dead)
+        return NULL;
+
+    return l;
+}
+
+static int send_to_dns_server(CattaWideAreaLookup *l, CattaDnsPacket *p) {
+    CattaAddress *a;
+
+    assert(l);
+    assert(p);
+
+    if (l->engine->n_dns_servers <= 0)
+        return -1;
+
+    assert(l->engine->current_dns_server < l->engine->n_dns_servers);
+
+    a = &l->engine->dns_servers[l->engine->current_dns_server];
+    l->dns_server_used = *a;
+
+    if (a->proto == CATTA_PROTO_INET) {
+
+        if (l->engine->fd_ipv4 < 0)
+            return -1;
+
+        return catta_send_dns_packet_ipv4(l->engine->fd_ipv4, CATTA_IF_UNSPEC, p, NULL, &a->data.ipv4, CATTA_DNS_PORT);
+
+    } else {
+        assert(a->proto == CATTA_PROTO_INET6);
+
+        if (l->engine->fd_ipv6 < 0)
+            return -1;
+
+        return catta_send_dns_packet_ipv6(l->engine->fd_ipv6, CATTA_IF_UNSPEC, p, NULL, &a->data.ipv6, CATTA_DNS_PORT);
+    }
+}
+
+static void next_dns_server(CattaWideAreaLookupEngine *e) {
+    assert(e);
+
+    e->current_dns_server++;
+
+    if (e->current_dns_server >= e->n_dns_servers)
+        e->current_dns_server = 0;
+}
+
+static void lookup_stop(CattaWideAreaLookup *l) {
+    assert(l);
+
+    l->callback = NULL;
+
+    if (l->time_event) {
+        catta_time_event_free(l->time_event);
+        l->time_event = NULL;
+    }
+}
+
+static void sender_timeout_callback(CattaTimeEvent *e, void *userdata) {
+    CattaWideAreaLookup *l = userdata;
+    struct timeval tv;
+
+    assert(l);
+
+    /* Try another DNS server after three retries */
+    if (l->n_send >= 3 && catta_address_cmp(&l->engine->dns_servers[l->engine->current_dns_server], &l->dns_server_used) == 0) {
+        next_dns_server(l->engine);
+
+        if (catta_address_cmp(&l->engine->dns_servers[l->engine->current_dns_server], &l->dns_server_used) == 0)
+            /* There is no other DNS server, fail */
+            l->n_send = 1000;
+    }
+
+    if (l->n_send >= 6) {
+        catta_log_warn(__FILE__": Query timed out.");
+        catta_server_set_errno(l->engine->server, CATTA_ERR_TIMEOUT);
+        l->callback(l->engine, CATTA_BROWSER_FAILURE, CATTA_LOOKUP_RESULT_WIDE_AREA, NULL, l->userdata);
+        lookup_stop(l);
+        return;
+    }
+
+    assert(l->packet);
+    send_to_dns_server(l, l->packet);
+    l->n_send++;
+
+    catta_time_event_update(e, catta_elapse_time(&tv, 1000, 0));
+}
+
+CattaWideAreaLookup *catta_wide_area_lookup_new(
+    CattaWideAreaLookupEngine *e,
+    CattaKey *key,
+    CattaWideAreaLookupCallback callback,
+    void *userdata) {
+
+    struct timeval tv;
+    CattaWideAreaLookup *l, *t;
+    uint8_t *p;
+
+    assert(e);
+    assert(key);
+    assert(callback);
+    assert(userdata);
+
+    l = catta_new(CattaWideAreaLookup, 1);
+    l->engine = e;
+    l->dead = 0;
+    l->key = catta_key_ref(key);
+    l->cname_key = catta_key_new_cname(l->key);
+    l->callback = callback;
+    l->userdata = userdata;
+
+    /* If more than 65K wide area quries are issued simultaneously,
+     * this will break. This should be limited by some higher level */
+
+    for (;; e->next_id++)
+        if (!find_lookup(e, e->next_id))
+            break; /* This ID is not yet used. */
+
+    l->id = e->next_id++;
+
+    /* We keep the packet around in case we need to repeat our query */
+    l->packet = catta_dns_packet_new(0);
+
+    catta_dns_packet_set_field(l->packet, CATTA_DNS_FIELD_ID, (uint16_t) l->id);
+    catta_dns_packet_set_field(l->packet, CATTA_DNS_FIELD_FLAGS, CATTA_DNS_FLAGS(0, 0, 0, 0, 1, 0, 0, 0, 0, 0));
+
+    p = catta_dns_packet_append_key(l->packet, key, 0);
+    assert(p);
+
+    catta_dns_packet_set_field(l->packet, CATTA_DNS_FIELD_QDCOUNT, 1);
+
+    if (send_to_dns_server(l, l->packet) < 0) {
+        catta_log_error(__FILE__": Failed to send packet.");
+        catta_dns_packet_free(l->packet);
+        catta_key_unref(l->key);
+        if (l->cname_key)
+            catta_key_unref(l->cname_key);
+        catta_free(l);
+        return NULL;
+    }
+
+    l->n_send = 1;
+
+    l->time_event = catta_time_event_new(e->server->time_event_queue, catta_elapse_time(&tv, 500, 0), sender_timeout_callback, l);
+
+    catta_hashmap_insert(e->lookups_by_id, &l->id, l);
+
+    t = catta_hashmap_lookup(e->lookups_by_key, l->key);
+    CATTA_LLIST_PREPEND(CattaWideAreaLookup, by_key, t, l);
+    catta_hashmap_replace(e->lookups_by_key, catta_key_ref(l->key), t);
+
+    CATTA_LLIST_PREPEND(CattaWideAreaLookup, lookups, e->lookups, l);
+
+    return l;
+}
+
+static void lookup_destroy(CattaWideAreaLookup *l) {
+    CattaWideAreaLookup *t;
+    assert(l);
+
+    lookup_stop(l);
+
+    t = catta_hashmap_lookup(l->engine->lookups_by_key, l->key);
+    CATTA_LLIST_REMOVE(CattaWideAreaLookup, by_key, t, l);
+    if (t)
+        catta_hashmap_replace(l->engine->lookups_by_key, catta_key_ref(l->key), t);
+    else
+        catta_hashmap_remove(l->engine->lookups_by_key, l->key);
+
+    CATTA_LLIST_REMOVE(CattaWideAreaLookup, lookups, l->engine->lookups, l);
+
+    catta_hashmap_remove(l->engine->lookups_by_id, &l->id);
+    catta_dns_packet_free(l->packet);
+
+    if (l->key)
+        catta_key_unref(l->key);
+
+    if (l->cname_key)
+        catta_key_unref(l->cname_key);
+
+    catta_free(l);
+}
+
+void catta_wide_area_lookup_free(CattaWideAreaLookup *l) {
+    assert(l);
+
+    if (l->dead)
+        return;
+
+    l->dead = 1;
+    l->engine->cleanup_dead = 1;
+    lookup_stop(l);
+}
+
+void catta_wide_area_cleanup(CattaWideAreaLookupEngine *e) {
+    CattaWideAreaLookup *l, *n;
+    assert(e);
+
+    while (e->cleanup_dead) {
+        e->cleanup_dead = 0;
+
+        for (l = e->lookups; l; l = n) {
+            n = l->lookups_next;
+
+            if (l->dead)
+                lookup_destroy(l);
+        }
+    }
+}
+
+static void cache_entry_free(CattaWideAreaCacheEntry *c) {
+    CattaWideAreaCacheEntry *t;
+    assert(c);
+
+    if (c->time_event)
+        catta_time_event_free(c->time_event);
+
+    CATTA_LLIST_REMOVE(CattaWideAreaCacheEntry, cache, c->engine->cache, c);
+
+    t = catta_hashmap_lookup(c->engine->cache_by_key, c->record->key);
+    CATTA_LLIST_REMOVE(CattaWideAreaCacheEntry, by_key, t, c);
+    if (t)
+        catta_hashmap_replace(c->engine->cache_by_key, catta_key_ref(c->record->key), t);
+    else
+        catta_hashmap_remove(c->engine->cache_by_key, c->record->key);
+
+    c->engine->cache_n_entries --;
+
+    catta_record_unref(c->record);
+    catta_free(c);
+}
+
+static void expiry_event(CattaTimeEvent *te, void *userdata) {
+    CattaWideAreaCacheEntry *e = userdata;
+
+    assert(te);
+    assert(e);
+
+    cache_entry_free(e);
+}
+
+static CattaWideAreaCacheEntry* find_record_in_cache(CattaWideAreaLookupEngine *e, CattaRecord *r) {
+    CattaWideAreaCacheEntry *c;
+
+    assert(e);
+    assert(r);
+
+    for (c = catta_hashmap_lookup(e->cache_by_key, r->key); c; c = c->by_key_next)
+        if (catta_record_equal_no_ttl(r, c->record))
+            return c;
+
+    return NULL;
+}
+
+static void run_callbacks(CattaWideAreaLookupEngine *e, CattaRecord *r) {
+    CattaWideAreaLookup *l;
+
+    assert(e);
+    assert(r);
+
+    for (l = catta_hashmap_lookup(e->lookups_by_key, r->key); l; l = l->by_key_next) {
+        if (l->dead || !l->callback)
+            continue;
+
+        l->callback(e, CATTA_BROWSER_NEW, CATTA_LOOKUP_RESULT_WIDE_AREA, r, l->userdata);
+    }
+
+    if (r->key->clazz == CATTA_DNS_CLASS_IN && r->key->type == CATTA_DNS_TYPE_CNAME) {
+        /* It's a CNAME record, so we have to scan the all lookups to see if one matches */
+
+        for (l = e->lookups; l; l = l->lookups_next) {
+            CattaKey *key;
+
+            if (l->dead || !l->callback)
+                continue;
+
+            if ((key = catta_key_new_cname(l->key))) {
+                if (catta_key_equal(r->key, key))
+                    l->callback(e, CATTA_BROWSER_NEW, CATTA_LOOKUP_RESULT_WIDE_AREA, r, l->userdata);
+
+                catta_key_unref(key);
+            }
+        }
+    }
+}
+
+static void add_to_cache(CattaWideAreaLookupEngine *e, CattaRecord *r) {
+    CattaWideAreaCacheEntry *c;
+    int is_new;
+
+    assert(e);
+    assert(r);
+
+    if ((c = find_record_in_cache(e, r))) {
+        is_new = 0;
+
+        /* Update the existing entry */
+        catta_record_unref(c->record);
+    } else {
+        CattaWideAreaCacheEntry *t;
+
+        is_new = 1;
+
+        /* Enforce cache size */
+        if (e->cache_n_entries >= CACHE_ENTRIES_MAX)
+            /* Eventually we should improve the caching algorithm here */
+            goto finish;
+
+        c = catta_new(CattaWideAreaCacheEntry, 1);
+        c->engine = e;
+        c->time_event = NULL;
+
+        CATTA_LLIST_PREPEND(CattaWideAreaCacheEntry, cache, e->cache, c);
+
+        /* Add the new entry to the cache entry hash table */
+        t = catta_hashmap_lookup(e->cache_by_key, r->key);
+        CATTA_LLIST_PREPEND(CattaWideAreaCacheEntry, by_key, t, c);
+        catta_hashmap_replace(e->cache_by_key, catta_key_ref(r->key), t);
+
+        e->cache_n_entries ++;
+    }
+
+    c->record = catta_record_ref(r);
+
+    gettimeofday(&c->timestamp, NULL);
+    c->expiry = c->timestamp;
+    catta_timeval_add(&c->expiry, r->ttl * 1000000);
+
+    if (c->time_event)
+        catta_time_event_update(c->time_event, &c->expiry);
+    else
+        c->time_event = catta_time_event_new(e->server->time_event_queue, &c->expiry, expiry_event, c);
+
+finish:
+
+    if (is_new)
+        run_callbacks(e, r);
+}
+
+static int map_dns_error(uint16_t error) {
+    static const int table[16] = {
+        CATTA_OK,
+        CATTA_ERR_DNS_FORMERR,
+        CATTA_ERR_DNS_SERVFAIL,
+        CATTA_ERR_DNS_NXDOMAIN,
+        CATTA_ERR_DNS_NOTIMP,
+        CATTA_ERR_DNS_REFUSED,
+        CATTA_ERR_DNS_YXDOMAIN,
+        CATTA_ERR_DNS_YXRRSET,
+        CATTA_ERR_DNS_NXRRSET,
+        CATTA_ERR_DNS_NOTAUTH,
+        CATTA_ERR_DNS_NOTZONE,
+        CATTA_ERR_INVALID_DNS_ERROR,
+        CATTA_ERR_INVALID_DNS_ERROR,
+        CATTA_ERR_INVALID_DNS_ERROR,
+        CATTA_ERR_INVALID_DNS_ERROR,
+        CATTA_ERR_INVALID_DNS_ERROR
+    };
+
+    assert(error <= 15);
+
+    return table[error];
+}
+
+static void handle_packet(CattaWideAreaLookupEngine *e, CattaDnsPacket *p) {
+    CattaWideAreaLookup *l = NULL;
+    int i, r;
+
+    CattaBrowserEvent final_event = CATTA_BROWSER_ALL_FOR_NOW;
+
+    assert(e);
+    assert(p);
+
+    /* Some superficial validity tests */
+    if (catta_dns_packet_check_valid(p) < 0 || catta_dns_packet_is_query(p)) {
+        catta_log_warn(__FILE__": Ignoring invalid response for wide area datagram.");
+        goto finish;
+    }
+
+    /* Look for the lookup that issued this query */
+    if (!(l = find_lookup(e, catta_dns_packet_get_field(p, CATTA_DNS_FIELD_ID))) || l->dead)
+        goto finish;
+
+    /* Check whether this a packet indicating a failure */
+    if ((r = catta_dns_packet_get_field(p, CATTA_DNS_FIELD_FLAGS) & 15) != 0 ||
+        catta_dns_packet_get_field(p, CATTA_DNS_FIELD_ANCOUNT) == 0) {
+
+        catta_server_set_errno(e->server, r == 0 ? CATTA_ERR_NOT_FOUND : map_dns_error(r));
+        /* Tell the user about the failure */
+        final_event = CATTA_BROWSER_FAILURE;
+
+        /* We go on here, since some of the records contained in the
+           reply might be interesting in some way */
+    }
+
+    /* Skip over the question */
+    for (i = (int) catta_dns_packet_get_field(p, CATTA_DNS_FIELD_QDCOUNT); i > 0; i--) {
+        CattaKey *k;
+
+        if (!(k = catta_dns_packet_consume_key(p, NULL))) {
+            catta_log_warn(__FILE__": Wide area response packet too short or invalid while reading question key. (Maybe a UTF-8 problem?)");
+            catta_server_set_errno(e->server, CATTA_ERR_INVALID_PACKET);
+            final_event = CATTA_BROWSER_FAILURE;
+            goto finish;
+        }
+
+        catta_key_unref(k);
+    }
+
+    /* Process responses */
+    for (i = (int) catta_dns_packet_get_field(p, CATTA_DNS_FIELD_ANCOUNT) +
+             (int) catta_dns_packet_get_field(p, CATTA_DNS_FIELD_NSCOUNT) +
+             (int) catta_dns_packet_get_field(p, CATTA_DNS_FIELD_ARCOUNT); i > 0; i--) {
+
+        CattaRecord *rr;
+
+        if (!(rr = catta_dns_packet_consume_record(p, NULL))) {
+            catta_log_warn(__FILE__": Wide area response packet too short or invalid while reading response record. (Maybe a UTF-8 problem?)");
+            catta_server_set_errno(e->server, CATTA_ERR_INVALID_PACKET);
+            final_event = CATTA_BROWSER_FAILURE;
+            goto finish;
+        }
+
+        add_to_cache(e, rr);
+        catta_record_unref(rr);
+    }
+
+finish:
+
+    if (l && !l->dead) {
+        if (l->callback)
+            l->callback(e, final_event, CATTA_LOOKUP_RESULT_WIDE_AREA, NULL, l->userdata);
+
+        lookup_stop(l);
+    }
+}
+
+static void socket_event(CATTA_GCC_UNUSED CattaWatch *w, int fd, CATTA_GCC_UNUSED CattaWatchEvent events, void *userdata) {
+    CattaWideAreaLookupEngine *e = userdata;
+    CattaDnsPacket *p = NULL;
+
+    if (fd == e->fd_ipv4)
+        p = catta_recv_dns_packet_ipv4(e->fd_ipv4, NULL, NULL, NULL, NULL, NULL);
+    else {
+        assert(fd == e->fd_ipv6);
+        p = catta_recv_dns_packet_ipv6(e->fd_ipv6, NULL, NULL, NULL, NULL, NULL);
+    }
+
+    if (p) {
+        handle_packet(e, p);
+        catta_dns_packet_free(p);
+    }
+}
+
+CattaWideAreaLookupEngine *catta_wide_area_engine_new(CattaServer *s) {
+    CattaWideAreaLookupEngine *e;
+
+    assert(s);
+
+    e = catta_new(CattaWideAreaLookupEngine, 1);
+    e->server = s;
+    e->cleanup_dead = 0;
+
+    /* Create sockets */
+    e->fd_ipv4 = s->config.use_ipv4 ? catta_open_unicast_socket_ipv4() : -1;
+    e->fd_ipv6 = s->config.use_ipv6 ? catta_open_unicast_socket_ipv6() : -1;
+
+    if (e->fd_ipv4 < 0 && e->fd_ipv6 < 0) {
+        catta_log_error(__FILE__": Failed to create wide area sockets: %s", errnostrsocket());
+
+        if (e->fd_ipv6 >= 0)
+            closesocket(e->fd_ipv6);
+
+        if (e->fd_ipv4 >= 0)
+            closesocket(e->fd_ipv4);
+
+        catta_free(e);
+        return NULL;
+    }
+
+    /* Create watches */
+
+    e->watch_ipv4 = e->watch_ipv6 = NULL;
+
+    if (e->fd_ipv4 >= 0)
+        e->watch_ipv4 = s->poll_api->watch_new(e->server->poll_api, e->fd_ipv4, CATTA_WATCH_IN, socket_event, e);
+    if (e->fd_ipv6 >= 0)
+        e->watch_ipv6 = s->poll_api->watch_new(e->server->poll_api, e->fd_ipv6, CATTA_WATCH_IN, socket_event, e);
+
+    e->n_dns_servers = e->current_dns_server = 0;
+    e->next_id = (uint16_t) rand();
+
+    /* Initialize cache */
+    CATTA_LLIST_HEAD_INIT(CattaWideAreaCacheEntry, e->cache);
+    e->cache_by_key = catta_hashmap_new((CattaHashFunc) catta_key_hash, (CattaEqualFunc) catta_key_equal, (CattaFreeFunc) catta_key_unref, NULL);
+    e->cache_n_entries = 0;
+
+    /* Initialize lookup list */
+    e->lookups_by_id = catta_hashmap_new((CattaHashFunc) catta_int_hash, (CattaEqualFunc) catta_int_equal, NULL, NULL);
+    e->lookups_by_key = catta_hashmap_new((CattaHashFunc) catta_key_hash, (CattaEqualFunc) catta_key_equal, (CattaFreeFunc) catta_key_unref, NULL);
+    CATTA_LLIST_HEAD_INIT(CattaWideAreaLookup, e->lookups);
+
+    return e;
+}
+
+void catta_wide_area_engine_free(CattaWideAreaLookupEngine *e) {
+    assert(e);
+
+    catta_wide_area_clear_cache(e);
+
+    while (e->lookups)
+        lookup_destroy(e->lookups);
+
+    catta_hashmap_free(e->cache_by_key);
+    catta_hashmap_free(e->lookups_by_id);
+    catta_hashmap_free(e->lookups_by_key);
+
+    if (e->watch_ipv4)
+        e->server->poll_api->watch_free(e->watch_ipv4);
+
+    if (e->watch_ipv6)
+        e->server->poll_api->watch_free(e->watch_ipv6);
+
+    if (e->fd_ipv6 >= 0)
+        closesocket(e->fd_ipv6);
+
+    if (e->fd_ipv4 >= 0)
+        closesocket(e->fd_ipv4);
+
+    catta_free(e);
+}
+
+void catta_wide_area_clear_cache(CattaWideAreaLookupEngine *e) {
+    assert(e);
+
+    while (e->cache)
+        cache_entry_free(e->cache);
+
+    assert(e->cache_n_entries == 0);
+}
+
+void catta_wide_area_set_servers(CattaWideAreaLookupEngine *e, const CattaAddress *a, unsigned n) {
+    assert(e);
+
+    if (a) {
+        for (e->n_dns_servers = 0; n > 0 && e->n_dns_servers < CATTA_WIDE_AREA_SERVERS_MAX; a++, n--)
+            if ((a->proto == CATTA_PROTO_INET && e->fd_ipv4 >= 0) || (a->proto == CATTA_PROTO_INET6 && e->fd_ipv6 >= 0))
+                e->dns_servers[e->n_dns_servers++] = *a;
+    } else {
+        assert(n == 0);
+        e->n_dns_servers = 0;
+    }
+
+    e->current_dns_server = 0;
+
+    catta_wide_area_clear_cache(e);
+}
+
+void catta_wide_area_cache_dump(CattaWideAreaLookupEngine *e, CattaDumpCallback callback, void* userdata) {
+    CattaWideAreaCacheEntry *c;
+
+    assert(e);
+    assert(callback);
+
+    callback(";; WIDE AREA CACHE ;;; ", userdata);
+
+    for (c = e->cache; c; c = c->cache_next) {
+        char *t = catta_record_to_string(c->record);
+        callback(t, userdata);
+        catta_free(t);
+    }
+}
+
+unsigned catta_wide_area_scan_cache(CattaWideAreaLookupEngine *e, CattaKey *key, CattaWideAreaLookupCallback callback, void *userdata) {
+    CattaWideAreaCacheEntry *c;
+    CattaKey *cname_key;
+    unsigned n = 0;
+
+    assert(e);
+    assert(key);
+    assert(callback);
+
+    for (c = catta_hashmap_lookup(e->cache_by_key, key); c; c = c->by_key_next) {
+        callback(e, CATTA_BROWSER_NEW, CATTA_LOOKUP_RESULT_WIDE_AREA|CATTA_LOOKUP_RESULT_CACHED, c->record, userdata);
+        n++;
+    }
+
+    if ((cname_key = catta_key_new_cname(key))) {
+
+        for (c = catta_hashmap_lookup(e->cache_by_key, cname_key); c; c = c->by_key_next) {
+            callback(e, CATTA_BROWSER_NEW, CATTA_LOOKUP_RESULT_WIDE_AREA|CATTA_LOOKUP_RESULT_CACHED, c->record, userdata);
+            n++;
+        }
+
+        catta_key_unref(cname_key);
+    }
+
+    return n;
+}
+
+int catta_wide_area_has_servers(CattaWideAreaLookupEngine *e) {
+    assert(e);
+
+    return e->n_dns_servers > 0;
+}
+
+
+