path: root/avahi-core/browse-dns-server.c

/***
  This file is part of avahi.

  avahi 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.

  avahi 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 avahi; 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 <string.h>

#include <avahi-common/domain.h>
#include <avahi-common/malloc.h>
#include <avahi-common/error.h>

#include "browse.h"
#include "log.h"
#include "rr.h"

typedef struct AvahiDNSServerInfo AvahiDNSServerInfo;

struct AvahiDNSServerInfo {
    AvahiSDNSServerBrowser *browser;

    AvahiIfIndex interface;
    AvahiProtocol protocol;
    AvahiRecord *srv_record;
    AvahiSHostNameResolver *host_name_resolver;
    AvahiAddress address;
    AvahiLookupResultFlags flags;

    AVAHI_LLIST_FIELDS(AvahiDNSServerInfo, info);
};

struct AvahiSDNSServerBrowser {
    AvahiServer *server;

    AvahiSRecordBrowser *record_browser;
    AvahiSDNSServerBrowserCallback callback;
    void* userdata;
    AvahiProtocol aprotocol;
    AvahiLookupFlags user_flags;

    unsigned n_info;

    AVAHI_LLIST_FIELDS(AvahiSDNSServerBrowser, browser);
    AVAHI_LLIST_HEAD(AvahiDNSServerInfo, info);
};

static AvahiDNSServerInfo* get_server_info(AvahiSDNSServerBrowser *b, AvahiIfIndex interface, AvahiProtocol protocol, AvahiRecord *r) {
    AvahiDNSServerInfo *i;

    assert(b);
    assert(r);

    for (i = b->info; i; i = i->info_next)
        if (i->interface == interface &&
            i->protocol == protocol &&
            avahi_record_equal_no_ttl(r, i->srv_record))
            return i;

    return NULL;
}

static void server_info_free(AvahiSDNSServerBrowser *b, AvahiDNSServerInfo *i) {
    assert(b);
    assert(i);

    avahi_record_unref(i->srv_record);
    if (i->host_name_resolver)
        avahi_s_host_name_resolver_free(i->host_name_resolver);

    AVAHI_LLIST_REMOVE(AvahiDNSServerInfo, info, b->info, i);

    assert(b->n_info >= 1);
    b->n_info--;

    avahi_free(i);
}

static void host_name_resolver_callback(
    AvahiSHostNameResolver *r,
    AVAHI_GCC_UNUSED AvahiIfIndex interface,
    AVAHI_GCC_UNUSED AvahiProtocol protocol,
    AvahiResolverEvent event,
    const char *host_name,
    const AvahiAddress *a,
    AvahiLookupResultFlags flags,
    void* userdata) {

    AvahiDNSServerInfo *i = userdata;

    assert(r);
    assert(host_name);
    assert(i);

    switch (event) {
        case AVAHI_RESOLVER_FOUND: {
            i->address = *a;

            i->browser->callback(
                i->browser,
                i->interface,
                i->protocol,
                AVAHI_BROWSER_NEW,
                i->srv_record->data.srv.name,
                &i->address,
                i->srv_record->data.srv.port,
                i->flags | flags,
                i->browser->userdata);

            break;
        }

        case AVAHI_RESOLVER_FAILURE:
            /* Ignore */
            break;
    }

    avahi_s_host_name_resolver_free(i->host_name_resolver);
    i->host_name_resolver = NULL;
}

static void record_browser_callback(
    AvahiSRecordBrowser*rr,
    AvahiIfIndex interface,
    AvahiProtocol protocol,
    AvahiBrowserEvent event,
    AvahiRecord *record,
    AvahiLookupResultFlags flags,
    void* userdata) {

    AvahiSDNSServerBrowser *b = userdata;

    assert(rr);
    assert(b);

    /* Filter flags */
    flags &= AVAHI_LOOKUP_RESULT_CACHED | AVAHI_LOOKUP_RESULT_MULTICAST | AVAHI_LOOKUP_RESULT_WIDE_AREA;

    switch (event) {
        case AVAHI_BROWSER_NEW: {
            AvahiDNSServerInfo *i;

            assert(record);
            assert(record->key->type == AVAHI_DNS_TYPE_SRV);

            if (get_server_info(b, interface, protocol, record))
                return;

            if (b->n_info >= 10)
                return;

            if (!(i = avahi_new(AvahiDNSServerInfo, 1)))
                return; /* OOM */

            i->browser = b;
            i->interface = interface;
            i->protocol = protocol;
            i->srv_record = avahi_record_ref(record);
            i->host_name_resolver = avahi_s_host_name_resolver_new(
                b->server,
                interface, protocol,
                record->data.srv.name,
                b->aprotocol,
                b->user_flags,
                host_name_resolver_callback, i);
            i->flags = flags;

            AVAHI_LLIST_PREPEND(AvahiDNSServerInfo, info, b->info, i);

            b->n_info++;
            break;
        }

        case AVAHI_BROWSER_REMOVE: {
            AvahiDNSServerInfo *i;

            assert(record);
            assert(record->key->type == AVAHI_DNS_TYPE_SRV);

            if (!(i = get_server_info(b, interface, protocol, record)))
                return;

            if (!i->host_name_resolver)
                b->callback(
                    b,
                    interface,
                    protocol,
                    event,
                    i->srv_record->data.srv.name,
                    &i->address,
                    i->srv_record->data.srv.port,
                    i->flags | flags,
                    b->userdata);

            server_info_free(b, i);
            break;
        }

        case AVAHI_BROWSER_FAILURE:
        case AVAHI_BROWSER_ALL_FOR_NOW:
        case AVAHI_BROWSER_CACHE_EXHAUSTED:

            b->callback(
                b,
                interface,
                protocol,
                event,
                NULL,
                NULL,
                0,
                flags,
                b->userdata);

            break;
    }
}

AvahiSDNSServerBrowser *avahi_s_dns_server_browser_new(
    AvahiServer *server,
    AvahiIfIndex interface,
    AvahiProtocol protocol,
    const char *domain,
    AvahiDNSServerType type,
    AvahiProtocol aprotocol,
    AvahiLookupFlags flags,
    AvahiSDNSServerBrowserCallback callback,
    void* userdata) {

    static const char * const type_table[AVAHI_DNS_SERVER_MAX] = {
        "_domain._udp",
        "_dns-update._udp"
    };

    AvahiSDNSServerBrowser *b;
    AvahiKey *k = NULL;
    char n[AVAHI_DOMAIN_NAME_MAX];
    int r;

    assert(server);
    assert(callback);

    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_IF_VALID(interface), AVAHI_ERR_INVALID_INTERFACE);
    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_PROTO_VALID(protocol), AVAHI_ERR_INVALID_PROTOCOL);
    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_PROTO_VALID(aprotocol), AVAHI_ERR_INVALID_PROTOCOL);
    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, !domain || avahi_is_valid_domain_name(domain), AVAHI_ERR_INVALID_DOMAIN_NAME);
    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_FLAGS_VALID(flags, AVAHI_LOOKUP_USE_WIDE_AREA|AVAHI_LOOKUP_USE_MULTICAST), AVAHI_ERR_INVALID_FLAGS);
    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, type < AVAHI_DNS_SERVER_MAX, AVAHI_ERR_INVALID_FLAGS);

    if (!domain)
        domain = server->domain_name;

    if ((r = avahi_service_name_join(n, sizeof(n), NULL, type_table[type], domain)) < 0) {
        avahi_server_set_errno(server, r);
        return NULL;
    }

    if (!(b = avahi_new(AvahiSDNSServerBrowser, 1))) {
        avahi_server_set_errno(server, AVAHI_ERR_NO_MEMORY);
        return NULL;
    }

    b->server = server;
    b->callback = callback;
    b->userdata = userdata;
    b->aprotocol = aprotocol;
    b->n_info = 0;
    b->user_flags = flags;

    AVAHI_LLIST_HEAD_INIT(AvahiDNSServerInfo, b->info);
    AVAHI_LLIST_PREPEND(AvahiSDNSServerBrowser, browser, server->dns_server_browsers, b);

    if (!(k = avahi_key_new(n, AVAHI_DNS_CLASS_IN, AVAHI_DNS_TYPE_SRV))) {
        avahi_server_set_errno(server, AVAHI_ERR_NO_MEMORY);
        goto fail;
    }

    if (!(b->record_browser = avahi_s_record_browser_new(server, interface, protocol, k, flags, record_browser_callback, b)))
        goto fail;

    avahi_key_unref(k);

    return b;

fail:

    if (k)
        avahi_key_unref(k);

    avahi_s_dns_server_browser_free(b);
    return NULL;
}

void avahi_s_dns_server_browser_free(AvahiSDNSServerBrowser *b) {
    assert(b);

    while (b->info)
        server_info_free(b, b->info);

    AVAHI_LLIST_REMOVE(AvahiSDNSServerBrowser, browser, b->server->dns_server_browsers, b);

    if (b->record_browser)
        avahi_s_record_browser_free(b->record_browser);

    avahi_free(b);
}