/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/*

 * Copyright (C) 2008 Imendio AB

 *

 * This program 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 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

#include <config.h>

#include <string.h>

#include <sys/types.h>

#include <netdb.h>

/* Needed on Mac OS X */

#if HAVE_ARPA_NAMESER_COMPAT_H

#include <arpa/nameser_compat.h>

#endif

#include <arpa/nameser.h>

#include <resolv.h>

#include "lm-marshal.h"

#include "lm-misc.h"

#include "lm-blocking-resolver.h"

#define SRV_LEN 8192

#define GET_PRIV(obj) (G_TYPE_INSTANCE_GET_PRIVATE ((obj), LM_TYPE_BLOCKING_RESOLVER, LmBlockingResolverPriv))

typedef struct LmBlockingResolverPriv LmBlockingResolverPriv;

struct LmBlockingResolverPriv {

        GSource *idle_source;

};

static void     blocking_resolver_finalize    (GObject       *object);

static void     blocking_resolver_lookup      (LmResolver    *resolver);

static void     blocking_resolver_cancel      (LmResolver    *resolver);

G_DEFINE_TYPE (LmBlockingResolver, lm_blocking_resolver, LM_TYPE_RESOLVER)

static void

lm_blocking_resolver_class_init (LmBlockingResolverClass *class)

{

        GObjectClass    *object_class   = G_OBJECT_CLASS (class);

        LmResolverClass *resolver_class = LM_RESOLVER_CLASS (class);

	object_class->finalize = blocking_resolver_finalize;

        resolver_class->lookup = blocking_resolver_lookup;

        resolver_class->cancel = blocking_resolver_cancel;

	g_type_class_add_private (object_class, 

                                  sizeof (LmBlockingResolverPriv));

}

static void

lm_blocking_resolver_init (LmBlockingResolver *blocking_resolver)

{

	LmBlockingResolverPriv *priv;

	priv = GET_PRIV (blocking_resolver);

}

static void

blocking_resolver_finalize (GObject *object)

{

	LmBlockingResolverPriv *priv;

	priv = GET_PRIV (object);

        /* Ensure we don't have an idle around */

        blocking_resolver_cancel (LM_RESOLVER (object));

	(G_OBJECT_CLASS (lm_blocking_resolver_parent_class)->finalize) (object);

}

static void

blocking_resolver_lookup_host (LmBlockingResolver *resolver)

{

        gchar           *host;

        struct addrinfo  req;

        struct addrinfo *ans;

        int              err;

        g_object_get (resolver, "host", &host, NULL);

        /* Lookup */

	memset (&req, 0, sizeof(req));

	req.ai_family   = AF_UNSPEC;

	req.ai_socktype = SOCK_STREAM;

	req.ai_protocol = IPPROTO_TCP;

        err = getaddrinfo (host, NULL, &req, &ans);

	if (err != 0) {

                /* FIXME: Report error */

		return;

	}

        if (ans == NULL) {

                /* Couldn't find any results */

                /* FIXME: Report no results  */

        }

        /* FIXME: How to set and iterate the results */

        /*priv->results    = ans;

        priv->cur_result = ans; */

        g_free (host);

}

static gboolean

blocking_resolver_parse_srv_response (unsigned char  *srv, 

                                      int             srv_len, 

                                      gchar         **out_server, 

                                      guint          *out_port)

{

	int                  qdcount;

	int                  ancount;

	int                  len;

	const unsigned char *pos;

	unsigned char       *end;

	HEADER              *head;

	char                 name[256];

	char                 pref_name[256];

	guint                pref_port = 0;

	guint                pref_prio = 9999;

	pref_name[0] = 0;

	pos = srv + sizeof (HEADER);

	end = srv + srv_len;

	head = (HEADER *) srv;

	qdcount = ntohs (head->qdcount);

	ancount = ntohs (head->ancount);

	/* Ignore the questions */

	while (qdcount-- > 0 && (len = dn_expand (srv, end, pos, name, 255)) >= 0) {

		g_assert (len >= 0);

		pos += len + QFIXEDSZ;

	}

	/* Parse the answers */

	while (ancount-- > 0 && (len = dn_expand (srv, end, pos, name, 255)) >= 0) {

		/* Ignore the initial string */

		uint16_t pref, weight, port;

		g_assert (len >= 0);

		pos += len;

		/* Ignore type, ttl, class and dlen */

		pos += 10;

		GETSHORT (pref, pos);

		GETSHORT (weight, pos);

		GETSHORT (port, pos);

		len = dn_expand (srv, end, pos, name, 255);

		if (pref < pref_prio) {

			pref_prio = pref;

			strcpy (pref_name, name);

			pref_port = port;

		}

		pos += len;

	}

	if (pref_name[0]) {

		*out_server = g_strdup (pref_name);

		*out_port = pref_port;

		return TRUE;

	} 

	return FALSE;

}

static void

blocking_resolver_lookup_service (LmBlockingResolver *resolver)

{

        gchar *domain;

        gchar *service;

        gchar *protocol;

        gchar *srv;

        gchar *new_server = NULL;

        guint  new_port = 0;

        gboolean  result;

	unsigned char    srv_ans[SRV_LEN];

	int              len;

        g_object_get (resolver,

                      "domain", &domain,

                      "service", &service,

                      "protocol", &protocol,

                      NULL);

        srv = lm_resolver_create_srv_string (domain, service, protocol);

        res_init ();

        len = res_query (srv, C_IN, T_SRV, srv_ans, SRV_LEN);

        result = blocking_resolver_parse_srv_response (srv_ans, len, 

                                                       &new_server, &new_port);

        if (result == FALSE) {

                /* FIXME: Report error */

        }

        g_object_set (resolver, 

                      "host", new_server,

                      "port", new_port,

                      NULL);

        /* Lookup the new server and the new port */

        g_free (new_server);

        g_free (srv);

        g_free (domain);

        g_free (service);

        g_free (protocol);

}

static gboolean

blocking_resolver_idle_lookup (LmBlockingResolver *resolver) 

{

        LmBlockingResolverPriv *priv = GET_PRIV (resolver);

        gint                    type;

        /* Start the DNS querying */

        /* Decide if we are going to lookup a srv or host */

        g_object_get (resolver, "type", &type, NULL);

        switch (type) {

        case LM_RESOLVER_HOST:

                blocking_resolver_lookup_host (resolver);

                break;

        case LM_RESOLVER_SRV:

                blocking_resolver_lookup_service (resolver);

                break;

        };

        /* End of DNS querying */

        priv->idle_source = NULL;

        return FALSE;

}

static void

blocking_resolver_lookup (LmResolver *resolver)

{

        LmBlockingResolverPriv *priv;

        GMainContext           *context;

        g_return_if_fail (LM_IS_BLOCKING_RESOLVER (resolver));

        priv = GET_PRIV (resolver);

        g_object_get (resolver, "context", &context, NULL);

        priv->idle_source = lm_misc_add_idle (context, 

                                              (GSourceFunc) blocking_resolver_idle_lookup,

                                              resolver);

}

static void

blocking_resolver_cancel (LmResolver *resolver)

{

        LmBlockingResolverPriv *priv;

        g_return_if_fail (LM_IS_BLOCKING_RESOLVER (resolver));

        priv = GET_PRIV (resolver);

        if (priv->idle_source) {

                g_source_destroy (priv->idle_source);

                priv->idle_source = NULL;

        }

}