/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- */

/*  Lac - Library for asynchronous communication
 *  Copyright (C) 2000, 2001, 2002, 2003  Søren Sandmann
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the 
 *  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 *  Boston, MA  02111-1307, USA.
 */
#define LAC_IPV6_UNSAFE

#include "lac.h"

#include <string.h>

#include "lacdns-messages.h"
#include "lacdns-cache.h"
#include "lacdns-nameserver.h"
#include "lacdns-query.h"
#include "lacdns-config.h"

#include "lacinternals.h"

#include <stdlib.h>

#include "config.h"
#ifdef HAVE_NETINET_IN_H
#  include <netinet/in.h>
#endif

/*
 * DNS RFC's:
 * 
 *      1034:   Domain names - concepts and facilities
 *               - standard
 *
 *      1035:   Domain names - implementation and specification
 *              - standard
 *
 *      1101:   DNS Encoding of Network Names and Other Types
 *              - textual representation for resource records
 *
 *      1183:   New DNS RR Definitions
 *              - defines RR type 17-21
 *              - experimental
 *
 *      1637:   DNS NSAP Resource Records
 *              - defines RR type 22
 *              - (Network Service Access Protocol)
 *              - experimental
 *
 *      1876:   A Means for Expressing Location Information
 *              in the Domain Name System
 *              - defines RR type 29
 *              - longitude/altitude
 *              - experimental
 *
 *      1982:   Serial Number Arithmetic
 *              - defines the meaning of the "serial" field in SOA
 *                records
 *              - proposed standard
 *
 *      1995:   Incremental Zone Transfers in DNS
 *              - proposed standard
 *
 *      1996:   A Mechanism for Prompt Notification of
 *              Zone Changes (DNS NOTIFY).
 *              - proposed standards
 *
 *      2136:   Dynamic Updates in the Domain Name System (DNS UPDATE)
 *      
 *      2137:   Secure Domain Name System Dynamic Update
 *
 *      2181:   Clarifications to the DNS Specification
 *              - IP packet header address usage from
 *                multi-homed servers,
 *              - TTLs in sets of records with the same name,
 *                class, and type,
 *              - correct handling of zone cuts,
 *              - three minor issues concerning SOA records and
 *                their use,
 *              - the precise definition of the Time to Live (TTL)
 *              - Use of the TC (truncated) header bit
 *              - the issue of what is an authoritative, or
 *                canonical, name,
 *              - and the issue of what makes a valid DNS label.
 *
 *      2308:   Negative Caching
 *
 *      2535:   Domain Name System Security Extensions
 *
 *      2845:   Secret Key Transaction Authentication for DNS (TSIG)
 */

struct LacAddress
{
    struct in_addr in_address;
};

/* lac_dns_error_quark */
GQuark
lac_dns_error_quark (void)
{
    static GQuark q = 0;
    
    if (q == 0)
	q = g_quark_from_static_string ("lac-dns-error-quark");
    
    return q;
}

/*
 * lac_address_new_lookup_all_from_name ()
 */
typedef struct AddressesLookupInfo {
    gchar *             domain;
    LacAddressesFunc    f;
    gpointer            data;
} AddressesLookupInfo;

static void
get_addresses_callback (const DnsQueryEvent *event, gpointer data)
{
    GPtrArray *addresses = NULL;
    GError *err = NULL;
    AddressesLookupInfo *info = data;
    const GList *list;

    switch (event->type)
    {
    case DNS_QUERY_EVENT_RESULTS:
	addresses = g_ptr_array_new ();
	
	for (list = event->results.results; list; list = list->next)
	{
	    RData *a = list->data;
	    LacAddress *addr =
		lac_address_new_from_a_b_c_d (
                    a->u.a.a, a->u.a.b, a->u.a.c, a->u.a.d);
	    
	    g_ptr_array_add (addresses, addr);
	}
	break;
	
    case DNS_QUERY_EVENT_NO_SUCH_NAME:
	err = g_error_new (
	    LAC_DNS_ERROR, LAC_DNS_ERROR_NO_SUCH_NAME,
	    "The name %s was not found", info->domain);
	break;
	
    case DNS_QUERY_EVENT_NO_DATA:
	err = g_error_new (
	    LAC_DNS_ERROR, LAC_DNS_ERROR_NO_DATA,
	    "No addresses found for %s", info->domain);
	break;
	
    case DNS_QUERY_EVENT_ERROR:
	err = g_error_copy (event->error.err);
	break;
    }

    info->f (addresses, info->data, err);

    g_free (info->domain);
    g_free (info);
    
    if (addresses)
    {
	gint i;
	for (i = 0; i < addresses->len; ++i)
	    lac_address_free (addresses->pdata[i]);
	g_ptr_array_free (addresses, TRUE);
    }
    
    if (err)
	g_error_free (err);
}

void
lac_address_new_lookup_all_from_name (const gchar      *name,
                                      LacAddressesFunc  f,
                                      gpointer          data)
{
    AddressesLookupInfo *info;
    LacAddress *address;
    GError *err = NULL;

    if (!dns_config_initialize (&err))
    {
        f (NULL, data, err);

        g_error_free (err);
        return;
    }
    
    /* check if name is on the "a.b.c.d" form */
    address = lac_address_new_from_string (name);
    if (address)
    {
	GPtrArray *addresses;

        addresses = g_ptr_array_new ();
	g_ptr_array_add (addresses, address);

        f (addresses, data, NULL);

        lac_address_free (address);
        g_ptr_array_free (addresses, TRUE);

        return;
    }

    info = g_new (AddressesLookupInfo, 1);
    info->domain = g_strdup (name);
    info->f = f;
    info->data = data;
    
    dns_query (name, A_TYPE, get_addresses_callback, info);
}

/*
 * lac_address_lookup_from_name()
 */
typedef struct {
    LacAddressFunc      f;
    gpointer            data;
} GetAddressInfo;

static void
dns_addr_callback (const GPtrArray *addresses,
                   gpointer         data,
                   const GError    *err)
{
    GetAddressInfo *info = data;

    if (err)
        info->f (NULL, info->data, err);
    else
        info->f (addresses->pdata[0], info->data, err);

    g_free (info);
}

void
lac_address_new_lookup_from_name (const gchar    *name,
                                  LacAddressFunc  f,
                                  gpointer        data)
{
    GetAddressInfo *info;
    
    g_return_if_fail (name != NULL);
    g_return_if_fail (f != NULL);

    info = g_new (GetAddressInfo, 1);
    info->f = f;
    info->data = data;

    lac_address_new_lookup_all_from_name (name, dns_addr_callback, info);
}

/*
 * lac_address_lookup_name()
 */
typedef struct NameLookupInfo {
    LacAddress  *address;
    LacNameFunc  f;
    gpointer     data;
} NameLookupInfo;

static void
get_name_callback (const DnsQueryEvent *event, gpointer data)
{
    NameLookupInfo *info = data;
    gchar  *name =         NULL;
    GError *err  =         NULL;
    gchar *free_me =       NULL;
    RData *ptr;

    switch (event->type)
    {
    case DNS_QUERY_EVENT_RESULTS:
	ptr = event->results.results->data;
	free_me = name = domain_name_to_string (ptr->u.ptr.ptr_name);
	break;
	
    case DNS_QUERY_EVENT_NO_SUCH_NAME:
        free_me = lac_address_to_string (info->address);
	err = g_error_new (
	    LAC_DNS_ERROR, LAC_DNS_ERROR_NO_SUCH_NAME,
	    "No names found for %s", free_me);
	break;
	
    case DNS_QUERY_EVENT_NO_DATA:
        free_me = lac_address_to_string (info->address);
	err = g_error_new (
	    LAC_DNS_ERROR, LAC_DNS_ERROR_NO_DATA,
	    "No names found for %s", free_me);
	break;
	
    case DNS_QUERY_EVENT_ERROR:
	err = g_error_copy (event->error.err);
	break;
    }

    info->f (name, info->data, err);

    lac_address_free (info->address);
    g_free (info);
    
    if (free_me)
        g_free (free_me);
}

static gchar *
address_to_in_addr_arpa (const LacAddress *addr)
{
    gint a, b, c, d;
    
    g_return_val_if_fail (addr != NULL, NULL);

    lac_address_get_a_b_c_d (addr, &a, &b, &c, &d);

    return g_strdup_printf ("%d.%d.%d.%d.in-addr.arpa.", d, c, b, a);
}

void
lac_address_lookup_name (const LacAddress  *address,
                         LacNameFunc        f,
                         gpointer           data)
{
    NameLookupInfo *info;
    gchar *domain_str;
    GError *err = NULL;

    if (!dns_config_initialize (&err))
    {
        f (NULL, data, err);

        g_error_free (err);
        return;
    }

    domain_str = address_to_in_addr_arpa (address);

    info = g_new (NameLookupInfo, 1);
    info->address = lac_address_copy (address);
    info->f = f;
    info->data = data;

    dns_query (domain_str, PTR_TYPE, get_name_callback, info);
    g_free (domain_str);
}

/*
 * "blocking" versions
 */

/*
 * lac_address_new_from_name_wait()
 */
typedef struct {
    LacAddress *result;
    GError *    err;
    GMainLoop * loop;
} GetHostByNameInfo;

static void
ghbn_callback (const GPtrArray *addresses, gpointer data, const GError *err)
{
    GetHostByNameInfo *ghbn_info = data;

    if (addresses)
    {
        ghbn_info->result = lac_address_copy (addresses->pdata[0]);
        ghbn_info->err    = NULL;
    }
    else
    {
        ghbn_info->result = NULL;
        ghbn_info->err    = g_error_copy (err);
    }

    if (g_main_loop_is_running (ghbn_info->loop))
        g_main_loop_quit (ghbn_info->loop);
}

/*
 * Lookup an address from a name. This function waits for the name
 * to arrive. Note that this function runs a recursive main loop,
 * so for example GTK+ applications will still process expose
 * events etc. while waiting inside this function. Of course
 * this also means that timeouts and idles etc. will still possibly
 * run.
 */
LacAddress *
lac_address_new_from_name_wait (const gchar       *name,
                                GError           **err)
{
    GetHostByNameInfo ghbn_info;
    
    ghbn_info.loop = g_main_loop_new (NULL, FALSE);
    
    lac_address_new_lookup_all_from_name (
        name, ghbn_callback, &ghbn_info);

    g_main_loop_run (ghbn_info.loop);

    g_main_loop_unref (ghbn_info.loop);

    if (ghbn_info.err)
    {
        g_propagate_error (err, ghbn_info.err);
        return NULL;
    }
    else
    {
        return ghbn_info.result;
    }
}

/*
 * lac_address_lookup_name_wait
 */
typedef struct {
    gchar *     result;
    GError *    err;
    GMainLoop * loop;
} GetHostByAddrInfo;

static void
ghba_callback (const gchar *name, gpointer data, const GError *err)
{
    GetHostByAddrInfo *ghba_info = data;

    if (name)
    {
        ghba_info->result = g_strdup (name);
        ghba_info->err = NULL;
    }
    else
    {
        ghba_info->result = NULL;
        ghba_info->err = g_error_copy (err);
    }

    if (g_main_loop_is_running (ghba_info->loop))
        g_main_loop_quit (ghba_info->loop);
}

gchar *
lac_address_lookup_name_wait (const LacAddress  *addr,
                              GError           **err)
{
    GetHostByAddrInfo ghba_info;

    ghba_info.loop = g_main_loop_new (NULL, FALSE);
    
    lac_address_lookup_name (addr, ghba_callback, &ghba_info);

    g_main_loop_run (ghba_info.loop);

    g_main_loop_unref (ghba_info.loop);
    
    if (ghba_info.err)
    {
        g_propagate_error (err, ghba_info.err);
        return NULL;
    }
    else
    {
        return ghba_info.result;
    }
}

LacAddress *
lac_address_allocate (void)
{
    LacAddress *addr = g_new0 (LacAddress, 1);
    
    return addr;
}

LacAddress *
lac_address_copy (const LacAddress *addr)
{
    LacAddress *copy = lac_address_allocate ();
    *copy = *addr;
    return copy;
}

void
lac_address_free (LacAddress *addr)
{
    g_return_if_fail (addr != NULL);
    
    g_free (addr);
}

LacAddress *
lac_address_new_from_a_b_c_d (gchar a,
                              gchar b,
                              gchar c,
                              gchar d)
{
    LacAddress *addr = lac_address_allocate ();
    guchar *addr_bytes = (guchar *)&(addr->in_address.s_addr);
    
    addr_bytes[0] = a;
    addr_bytes[1] = b;
    addr_bytes[2] = c;
    addr_bytes[3] = d;
    
    return addr;
}

/* FIXME: is this correct when there are more than three dots?
 */
LacAddress *
lac_address_new_from_string (const gchar *str)
{
    LacAddress *addr = NULL;
    gchar **strs;
    gint numbers[4];
    gint i;
    
    g_return_val_if_fail (str != NULL, NULL);
    
    strs = g_strsplit (str, ".", 4);
    
    for (i = 0; i < 4; ++i)
    {
        gchar *endptr;
        
        if (!strs[i])
            goto err;
        numbers[i] = strtol (strs[i], &endptr, 10);
        if (*endptr != '\0' || endptr == strs[i])
            goto err;
    }
    if (strs[4])
        goto err;
    
    addr = lac_address_new_from_a_b_c_d (
        numbers[0], numbers[1], numbers[2], numbers[3]);
    
 err:
    g_strfreev (strs);
    
    return addr;
}

void
lac_address_new_lookup_from_localhost (LacAddressFunc f,
                                       gpointer       data)
{
    gchar *name;
    
    name = lac_gethostname ();
    lac_address_new_lookup_from_name (name, f, data);
    g_free (name);
}

typedef struct {
    LacAddress *result;
    GError     *err;
    GMainLoop  *loop;
} NewFromLocalHostInfo;

static void
localhost_callback (const LacAddress *address,
                    gpointer          data,
                    const GError     *err)
{
    NewFromLocalHostInfo *info = data;

    if (address)
    {
        info->result = lac_address_copy (address);
        info->err = NULL;
    }
    else
    {
        info->result = NULL;
        info->err = g_error_copy (err);
    }

    if (g_main_loop_is_running (info->loop))
        g_main_loop_quit (info->loop);
}

LacAddress *
lac_address_new_from_localhost_wait (GError      **err)
{
    NewFromLocalHostInfo info;

    info.loop = g_main_loop_new (NULL, FALSE);

    lac_address_new_lookup_from_localhost (localhost_callback, &info);

    g_main_loop_run (info.loop);

    g_main_loop_unref (info.loop);
    
    if (info.err)
    {
        g_propagate_error (err, info.err);
        return NULL;
    }
    else
    {
        return info.result;
    }
}

guint
lac_address_hash (gconstpointer addr)
{
    return (guint)(((LacAddress *)addr)->in_address.s_addr);
}

gint
lac_address_compare (gconstpointer addr1, gconstpointer addr2)
{
    const LacAddress *a1 = addr1;
    const LacAddress *a2 = addr2;
    
    if (a1->in_address.s_addr == a2->in_address.s_addr)
	return 0;
    if (a1->in_address.s_addr > a2->in_address.s_addr)
	return 1;
    return -1;
}

gboolean
lac_address_equal (gconstpointer addr1, gconstpointer addr2)
{
    const LacAddress *a1 = addr1;
    const LacAddress *a2 = addr2;
    
    return a1->in_address.s_addr == a2->in_address.s_addr;
}

gchar *
lac_address_to_string (const LacAddress *addr) 
{
    guchar *addr_bytes;
    struct in_addr in_addr;
    
    g_return_val_if_fail (addr != NULL, NULL);

    lac_address_get_in_addr (addr, &in_addr);
    
    addr_bytes = (guchar *)&(in_addr.s_addr);
    
    return g_strdup_printf ("%d.%d.%d.%d",
                            addr_bytes[0], addr_bytes[1],
                            addr_bytes[2], addr_bytes[3]);
}

void
lac_address_get_a_b_c_d (const LacAddress *addr,
                         gint             *a,
                         gint             *b,
                         gint             *c,
                         gint             *d)
{
    const guchar *addr_bytes;

    g_return_if_fail (addr != NULL);
    
    addr_bytes = (const guchar *)&(addr->in_address.s_addr);

    if (a)
        *a = addr_bytes[0];
    if (b)
        *b = addr_bytes[1];
    if (c)
        *c = addr_bytes[2];
    if (d)
        *d = addr_bytes[3];
}

void
lac_address_get_in_addr (const LacAddress *addr,
                         struct in_addr   *in_addr)
{
    *in_addr = addr->in_address;
}

void
lac_address_set_in_addr (LacAddress     *addr,
                         struct in_addr *in_addr)
{
    addr->in_address = *in_addr;
}