/********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2006 Wilmer van der Gaast and others                *
  \********************************************************************/

/* Storage backend that uses an XMLish format for all data. */

/*
  This program 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 with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#define BITLBEE_CORE
#include "bitlbee.h"
#include "base64.h"
#include "rc4.h"
#include "md5.h"

typedef enum
{
	XML_PASS_CHECK_ONLY = -1,
	XML_PASS_UNKNOWN = 0,
	XML_PASS_WRONG,
	XML_PASS_OK
} xml_pass_st;

/* To make it easier later when extending the format: */
#define XML_FORMAT_VERSION 1

struct xml_parsedata
{
	irc_t *irc;
	char *current_setting;
	account_t *current_account;
	char *given_nick;
	char *given_pass;
	xml_pass_st pass_st;
};

static char *xml_attr( const gchar **attr_names, const gchar **attr_values, const gchar *key )
{
	int i;
	
	for( i = 0; attr_names[i]; i ++ )
		if( g_strcasecmp( attr_names[i], key ) == 0 )
			return (char*) attr_values[i];
	
	return NULL;
}

static void xml_destroy_xd( gpointer data )
{
	struct xml_parsedata *xd = data;
	
	g_free( xd->given_nick );
	g_free( xd->given_pass );
	g_free( xd );
}

static void xml_start_element( GMarkupParseContext *ctx, const gchar *element_name, const gchar **attr_names, const gchar **attr_values, gpointer data, GError **error )
{
	struct xml_parsedata *xd = data;
	irc_t *irc = xd->irc;
	
	if( g_strcasecmp( element_name, "user" ) == 0 )
	{
		char *nick = xml_attr( attr_names, attr_values, "nick" );
		char *pass = xml_attr( attr_names, attr_values, "password" );
		md5_byte_t *pass_dec = NULL;
		
		if( !nick || !pass )
		{
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Missing attributes for %s element", element_name );
		}
		else if( base64_decode( pass, &pass_dec ) != 21 )
		{
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Error while decoding password attribute" );
		}
		else
		{
			md5_byte_t pass_md5[16];
			md5_state_t md5_state;
			int i;
			
			md5_init( &md5_state );
			md5_append( &md5_state, (md5_byte_t*) xd->given_pass, strlen( xd->given_pass ) );
			md5_append( &md5_state, (md5_byte_t*) pass_dec + 16, 5 ); /* Hmmm, salt! */
			md5_finish( &md5_state, pass_md5 );
			
			for( i = 0; i < 16; i ++ )
			{
				if( pass_dec[i] != pass_md5[i] )
				{
					xd->pass_st = XML_PASS_WRONG;
					g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
					             "Password mismatch" );
					break;
				}
			}
			
			/* If we reached the end of the loop, it was a match! */
			if( i == 16 )
			{
				if( xd->pass_st != XML_PASS_CHECK_ONLY )
					xd->pass_st = XML_PASS_OK;
			}
		}
		
		g_free( pass_dec );
	}
	else if( xd->pass_st < XML_PASS_OK )
	{
		/* Let's not parse anything else if we only have to check
		   the password. */
	}
	else if( g_strcasecmp( element_name, "account" ) == 0 )
	{
		char *protocol, *handle, *server, *password = NULL, *autoconnect;
		char *pass_b64 = NULL;
		unsigned char *pass_rc4 = NULL;
		int pass_len;
		struct prpl *prpl = NULL;
		
		handle = xml_attr( attr_names, attr_values, "handle" );
		pass_b64 = xml_attr( attr_names, attr_values, "password" );
		server = xml_attr( attr_names, attr_values, "server" );
		autoconnect = xml_attr( attr_names, attr_values, "autoconnect" );
		
		protocol = xml_attr( attr_names, attr_values, "protocol" );
		if( protocol )
			prpl = find_protocol( protocol );
		
		if( !handle || !pass_b64 || !protocol )
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Missing attributes for %s element", element_name );
		else if( !prpl )
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Unknown protocol: %s", protocol );
		else if( ( pass_len = base64_decode( pass_b64, (unsigned char**) &pass_rc4 ) ) &&
		                rc4_decode( pass_rc4, pass_len,
		                            &password, 
									xd->given_pass ) )
		{
			xd->current_account = account_add( irc, prpl, handle, password );
			if( server )
				set_setstr( &xd->current_account->set, "server", server );
			if( autoconnect )
				set_setstr( &xd->current_account->set, "auto_connect", autoconnect );
		}
		else
		{
			/* Actually the _decode functions don't even return error codes,
			   but maybe they will later... */
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Error while decrypting account password" );
		}
		
		g_free( pass_rc4 );
		g_free( password );
	}
	else if( g_strcasecmp( element_name, "setting" ) == 0 )
	{
		char *setting;
		
		if( xd->current_setting )
		{
			g_free( xd->current_setting );
			xd->current_setting = NULL;
		}
		
		if( ( setting = xml_attr( attr_names, attr_values, "name" ) ) )
			xd->current_setting = g_strdup( setting );
		else
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Missing attributes for %s element", element_name );
	}
	else if( g_strcasecmp( element_name, "buddy" ) == 0 )
	{
		char *handle, *nick;
		
		handle = xml_attr( attr_names, attr_values, "handle" );
		nick = xml_attr( attr_names, attr_values, "nick" );
		
		if( xd->current_account && handle && nick )
		{
			nick_set( xd->current_account, handle, nick );
		}
		else
		{
			g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_INVALID_CONTENT,
			             "Missing attributes for %s element", element_name );
		}
	}
	else
	{
		g_set_error( error, G_MARKUP_ERROR, G_MARKUP_ERROR_UNKNOWN_ELEMENT,
		             "Unkown element: %s", element_name );
	}
}

static void xml_end_element( GMarkupParseContext *ctx, const gchar *element_name, gpointer data, GError **error )
{
	struct xml_parsedata *xd = data;
	
	if( g_strcasecmp( element_name, "setting" ) == 0 && xd->current_setting )
	{
		g_free( xd->current_setting );
		xd->current_setting = NULL;
	}
	else if( g_strcasecmp( element_name, "account" ) == 0 )
	{
		xd->current_account = NULL;
	}
}

static void xml_text( GMarkupParseContext *ctx, const gchar *text_orig, gsize text_len, gpointer data, GError **error )
{
	char text[text_len+1];
	struct xml_parsedata *xd = data;
	irc_t *irc = xd->irc;
	
	strncpy( text, text_orig, text_len );
	text[text_len] = 0;
	
	if( xd->pass_st < XML_PASS_OK )
	{
		/* Let's not parse anything else if we only have to check
		   the password, or if we didn't get the chance to check it
		   yet. */
	}
	else if( g_strcasecmp( g_markup_parse_context_get_element( ctx ), "setting" ) == 0 && xd->current_setting )
	{
		set_setstr( xd->current_account ? &xd->current_account->set : &irc->set,
		            xd->current_setting, (char*) text );
		g_free( xd->current_setting );
		xd->current_setting = NULL;
	}
}

GMarkupParser xml_parser =
{
	xml_start_element,
	xml_end_element,
	xml_text,
	NULL,
	NULL
};

static void xml_init( void )
{
	if( access( global.conf->configdir, F_OK ) != 0 )
		log_message( LOGLVL_WARNING, "The configuration directory %s does not exist. Configuration won't be saved.", global.conf->configdir );
	else if( access( global.conf->configdir, R_OK ) != 0 || access( global.conf->configdir, W_OK ) != 0 )
		log_message( LOGLVL_WARNING, "Permission problem: Can't read/write from/to %s.", global.conf->configdir );
}

static storage_status_t xml_load_real( const char *my_nick, const char *password, irc_t *irc, xml_pass_st action )
{
	GMarkupParseContext *ctx;
	struct xml_parsedata *xd;
	char *fn, buf[512];
	GError *gerr = NULL;
	int fd, st;
	
	if( irc && irc->status & USTATUS_IDENTIFIED )
		return( 1 );
	
	xd = g_new0( struct xml_parsedata, 1 );
	xd->irc = irc;
	xd->given_nick = g_strdup( my_nick );
	xd->given_pass = g_strdup( password );
	xd->pass_st = action;
	nick_lc( xd->given_nick );
	
	fn = g_strdup_printf( "%s%s%s", global.conf->configdir, xd->given_nick, ".xml" );
	if( ( fd = open( fn, O_RDONLY ) ) < 0 )
	{
		xml_destroy_xd( xd );
		g_free( fn );
		return STORAGE_NO_SUCH_USER;
	}
	g_free( fn );
	
	ctx = g_markup_parse_context_new( &xml_parser, 0, xd, xml_destroy_xd );
	
	while( ( st = read( fd, buf, sizeof( buf ) ) ) > 0 )
	{
		if( !g_markup_parse_context_parse( ctx, buf, st, &gerr ) || gerr )
		{
			xml_pass_st pass_st = xd->pass_st;
			
			g_markup_parse_context_free( ctx );
			close( fd );
			
			if( pass_st == XML_PASS_WRONG )
			{
				g_clear_error( &gerr );
				return STORAGE_INVALID_PASSWORD;
			}
			else
			{
				if( gerr && irc )
					irc_usermsg( irc, "Error from XML-parser: %s", gerr->message );
				
				g_clear_error( &gerr );
				return STORAGE_OTHER_ERROR;
			}
		}
	}
	/* Just to be sure... */
	g_clear_error( &gerr );
	
	g_markup_parse_context_free( ctx );
	close( fd );
	
	if( action == XML_PASS_CHECK_ONLY )
		return STORAGE_OK;
	
	irc->status |= USTATUS_IDENTIFIED;
	
	return STORAGE_OK;
}

static storage_status_t xml_load( const char *my_nick, const char *password, irc_t *irc )
{
	return xml_load_real( my_nick, password, irc, XML_PASS_UNKNOWN );
}

static storage_status_t xml_check_pass( const char *my_nick, const char *password )
{
	/* This is a little bit risky because we have to pass NULL for the
	   irc_t argument. This *should* be fine, if I didn't miss anything... */
	return xml_load_real( my_nick, password, NULL, XML_PASS_CHECK_ONLY );
}

static int xml_printf( int fd, int indent, char *fmt, ... )
{
	va_list params;
	char *out;
	char tabs[9] = "\t\t\t\t\t\t\t\t";
	int len;
	
	/* Maybe not very clean, but who needs more than 8 levels of indentation anyway? */
	if( write( fd, tabs, indent <= 8 ? indent : 8 ) != indent )
		return 0;
	
	va_start( params, fmt );
	out = g_markup_vprintf_escaped( fmt, params );
	va_end( params );
	
	len = strlen( out );
	len -= write( fd, out, len );
	g_free( out );
	
	return len == 0;
}

static gboolean xml_save_nick( gpointer key, gpointer value, gpointer data );

static storage_status_t xml_save( irc_t *irc, int overwrite )
{
	char path[512], *path2, *pass_buf = NULL;
	set_t *set;
	account_t *acc;
	int fd;
	md5_byte_t pass_md5[21];
	md5_state_t md5_state;
	
	if( irc->password == NULL )
	{
		irc_usermsg( irc, "Please register yourself if you want to save your settings." );
		return STORAGE_OTHER_ERROR;
	}
	
	path2 = g_strdup( irc->nick );
	nick_lc( path2 );
	g_snprintf( path, sizeof( path ) - 2, "%s%s%s", global.conf->configdir, path2, ".xml" );
	g_free( path2 );
	
	if( !overwrite && access( path, F_OK ) != -1 )
		return STORAGE_ALREADY_EXISTS;
	
	strcat( path, "~" );
	if( ( fd = open( path, O_WRONLY | O_CREAT | O_TRUNC, 0600 ) ) < 0 )
	{
		irc_usermsg( irc, "Error while opening configuration file." );
		return STORAGE_OTHER_ERROR;
	}
	
	/* Generate a salted md5sum of the password. Use 5 bytes for the salt
	   (to prevent dictionary lookups of passwords) to end up with a 21-
	   byte password hash, more convenient for base64 encoding. */
	random_bytes( pass_md5 + 16, 5 );
	md5_init( &md5_state );
	md5_append( &md5_state, (md5_byte_t*) irc->password, strlen( irc->password ) );
	md5_append( &md5_state, pass_md5 + 16, 5 ); /* Add the salt. */
	md5_finish( &md5_state, pass_md5 );
	/* Save the hash in base64-encoded form. */
	pass_buf = base64_encode( pass_md5, 21 );
	
	if( !xml_printf( fd, 0, "<user nick=\"%s\" password=\"%s\" version=\"%d\">\n", irc->nick, pass_buf, XML_FORMAT_VERSION ) )
		goto write_error;
	
	g_free( pass_buf );
	
	for( set = irc->set; set; set = set->next )
		if( set->value && set->def )
			if( !xml_printf( fd, 1, "<setting name=\"%s\">%s</setting>\n", set->key, set->value ) )
				goto write_error;
	
	for( acc = irc->accounts; acc; acc = acc->next )
	{
		unsigned char *pass_rc4;
		char *pass_b64;
		int pass_len;
		
		pass_len = rc4_encode( acc->pass, strlen( acc->pass ), (unsigned char**) &pass_rc4, irc->password );
		pass_b64 = base64_encode( pass_rc4, pass_len );
		g_free( pass_rc4 );
		
		if( !xml_printf( fd, 1, "<account protocol=\"%s\" handle=\"%s\" password=\"%s\" autoconnect=\"%d\"", acc->prpl->name, acc->user, pass_b64, acc->auto_connect ) )
		{
			g_free( pass_b64 );
			goto write_error;
		}
		g_free( pass_b64 );
		
		if( acc->server && acc->server[0] && !xml_printf( fd, 0, " server=\"%s\"", acc->server ) )
			goto write_error;
		if( !xml_printf( fd, 0, ">\n" ) )
			goto write_error;
		
		for( set = acc->set; set; set = set->next )
			if( set->value && set->def && !( set->flags & ACC_SET_NOSAVE ) )
				if( !xml_printf( fd, 2, "<setting name=\"%s\">%s</setting>\n", set->key, set->value ) )
					goto write_error;
		
		/* This probably looks pretty strange. g_hash_table_foreach
		   is quite a PITA already (but it can't get much better in
		   C without using #define, I'm afraid), and since it
		   doesn't seem to be possible to abort the foreach on write
		   errors, so instead let's use the _find function and
		   return TRUE on write errors. Which means, if we found
		   something, there was an error. :-) */
		if( g_hash_table_find( acc->nicks, xml_save_nick, (gpointer) fd ) )
			goto write_error;
		
		if( !xml_printf( fd, 1, "</account>\n" ) )
			goto write_error;
	}
	
	if( !xml_printf( fd, 0, "</user>\n" ) )
		goto write_error;
	
	close( fd );
	
	path2 = g_strndup( path, strlen( path ) - 1 );
	if( rename( path, path2 ) != 0 )
	{
		irc_usermsg( irc, "Error while renaming temporary configuration file." );
		
		g_free( path2 );
		unlink( path );
		
		return STORAGE_OTHER_ERROR;
	}
	
	g_free( path2 );
	
	return STORAGE_OK;

write_error:
	g_free( pass_buf );
	
	irc_usermsg( irc, "Write error. Disk full?" );
	close( fd );
	
	return STORAGE_OTHER_ERROR;
}

static gboolean xml_save_nick( gpointer key, gpointer value, gpointer data )
{
	return !xml_printf( (int) data, 2, "<buddy handle=\"%s\" nick=\"%s\" />\n", key, value );
}

static storage_status_t xml_remove( const char *nick, const char *password )
{
	char s[512];
	storage_status_t status;

	status = xml_check_pass( nick, password );
	if( status != STORAGE_OK )
		return status;

	g_snprintf( s, 511, "%s%s%s", global.conf->configdir, nick, ".xml" );
	if( unlink( s ) == -1 )
		return STORAGE_OTHER_ERROR;
	
	return STORAGE_OK;
}

storage_t storage_xml = {
	.name = "xml",
	.init = xml_init,
	.check_pass = xml_check_pass,
	.remove = xml_remove,
	.load = xml_load,
	.save = xml_save
};