/*
 * jabberd - Jabber Open Source Server
 * Copyright (c) 2002-2003 Jeremie Miller, Thomas Muldowney,
 *                         Ryan Eatmon, Robert Norris
 *
 * 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
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
 */

/* this module talks to a MySQL server via libmysqlclient */

#include "c2s.h"
#include <mysql.h>

#define MYSQL_LU  1024   /* maximum length of username - should correspond to field length */
#define MYSQL_LR   256   /* maximum length of realm - should correspond to field length */
#define MYSQL_LP   256   /* maximum length of password - should correspond to field length */


typedef struct mysqlcontext_st {
  MYSQL * conn;
  char * sql_create;
  char * sql_select;
  char * sql_setpassword;
  char * sql_delete;
  char * field_password;
  } *mysqlcontext_t;

static MYSQL_RES *_ar_mysql_get_user_tuple(authreg_t ar, char *username, char *realm) {
    mysqlcontext_t ctx = (mysqlcontext_t) ar->private;
    MYSQL *conn = ctx->conn;
    char iuser[MYSQL_LU+1], irealm[MYSQL_LR+1];
    char euser[MYSQL_LU*2+1], erealm[MYSQL_LR*2+1], sql[1024 + MYSQL_LU*2 + MYSQL_LR*2 + 1];  /* query(1024) + euser + erealm + \0(1) */
    MYSQL_RES *res;
    
    if(mysql_ping(conn) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: connection to database lost");
        return NULL;
    }

    snprintf(iuser, MYSQL_LU+1, "%s", username);
    snprintf(irealm, MYSQL_LR+1, "%s", realm);

    mysql_real_escape_string(conn, euser, iuser, strlen(iuser));
    mysql_real_escape_string(conn, erealm, irealm, strlen(irealm));

    sprintf(sql, ctx->sql_select, euser, erealm);

    log_debug(ZONE, "prepared sql: %s", sql);

    if(mysql_query(conn, sql) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: sql select failed: %s", mysql_error(conn));
        return NULL;
    }

    res = mysql_store_result(conn);
    if(res == NULL) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: sql result retrieval failed: %s", mysql_error(conn));
        return NULL;
    }

    if(mysql_num_rows(res) != 1) {
        mysql_free_result(res);
        return NULL;
    }

    return res;
}

static int _ar_mysql_user_exists(authreg_t ar, char *username, char *realm) {
    MYSQL_RES *res = _ar_mysql_get_user_tuple(ar, username, realm);

    if(res != NULL) {
        mysql_free_result(res);
        return 1;
    }

    return 0;
}

static int _ar_mysql_get_password(authreg_t ar, char *username, char *realm, char password[257]) {
    mysqlcontext_t ctx = (mysqlcontext_t) ar->private;
    MYSQL *conn = ctx->conn;
    MYSQL_RES *res = _ar_mysql_get_user_tuple(ar, username, realm);
    MYSQL_FIELD *field;
    MYSQL_ROW tuple;
    int i, fpass = 0;

    if(res == NULL)
        return 1;

    for(i = mysql_num_fields(res) - 1; i >= 0; i--) {
        field = mysql_fetch_field_direct(res, i);
        if(strcmp(field->name, ctx->field_password) == 0) {
            fpass = i;
            break;
        }
    }

    if((tuple = mysql_fetch_row(res)) == NULL) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: sql tuple retrieval failed: %s", mysql_error(conn));
        mysql_free_result(res);
        return 1;
    }

    if(tuple[fpass] == NULL) {
        mysql_free_result(res);
        return 1;
    }

    strcpy(password, tuple[fpass]);

    mysql_free_result(res);

    return 0;
}

static int _ar_mysql_set_password(authreg_t ar, char *username, char *realm, char password[257]) {
    mysqlcontext_t ctx = (mysqlcontext_t) ar->private;
    MYSQL *conn = ctx->conn;
    char iuser[MYSQL_LU+1], irealm[MYSQL_LR+1];
    char euser[MYSQL_LU*2+1], erealm[MYSQL_LR*2+1], epass[513], sql[1024+MYSQL_LU*2+MYSQL_LR*2+512+1];  /* query(1024) + euser + erealm + epass(512) + \0(1) */

    if(mysql_ping(conn) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: connection to database lost");
        return 1;
    }

    snprintf(iuser, MYSQL_LU+1, "%s", username);
    snprintf(irealm, MYSQL_LR+1, "%s", realm);

    password[256]= '\0';

    mysql_real_escape_string(conn, euser, iuser, strlen(iuser));
    mysql_real_escape_string(conn, erealm, irealm, strlen(irealm));
    mysql_real_escape_string(conn, epass, password, strlen(password));

    sprintf(sql, ctx->sql_setpassword, epass, euser, erealm);

    log_debug(ZONE, "prepared sql: %s", sql);

    if(mysql_query(conn, sql) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: sql update failed: %s", mysql_error(conn));
        return 1;
    }

    return 0;
}

static int _ar_mysql_create_user(authreg_t ar, char *username, char *realm) {
    mysqlcontext_t ctx = (mysqlcontext_t) ar->private;
    MYSQL *conn = ctx->conn;
    char iuser[MYSQL_LU+1], irealm[MYSQL_LR+1];
    char euser[MYSQL_LU*2+1], erealm[MYSQL_LR*2+1], sql[1024+MYSQL_LU*2+MYSQL_LR*2+1];    /* query(1024) + euser + erealm + \0(1) */
    MYSQL_RES *res = _ar_mysql_get_user_tuple(ar, username, realm);

    if(res != NULL) {
        mysql_free_result(res);
        return 1;
    }

    mysql_free_result(res);

    if(mysql_ping(conn) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: connection to database lost");
        return 1;
    }

    snprintf(iuser, MYSQL_LU+1, "%s", username);
    snprintf(irealm, MYSQL_LR+1, "%s", realm);

    mysql_real_escape_string(conn, euser, iuser, strlen(iuser));
    mysql_real_escape_string(conn, erealm, irealm, strlen(irealm));

    sprintf(sql, ctx->sql_create, euser, erealm);

    log_debug(ZONE, "prepared sql: %s", sql);

    if(mysql_query(conn, sql) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: sql insert failed: %s", mysql_error(conn));
        return 1;
    }

    return 0;
}

static int _ar_mysql_delete_user(authreg_t ar, char *username, char *realm) {
    mysqlcontext_t ctx = (mysqlcontext_t) ar->private;
    MYSQL *conn = ctx->conn;
    char iuser[MYSQL_LU+1], irealm[MYSQL_LR+1];
    char euser[MYSQL_LU*2+1], erealm[MYSQL_LR*2+1], sql[1024+MYSQL_LU*2+MYSQL_LR*2+1];    /* query(1024) + euser + erealm + \0(1) */

    if(mysql_ping(conn) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: connection to database lost");
        return 1;
    }

    snprintf(iuser, MYSQL_LU+1, "%s", username);
    snprintf(irealm, MYSQL_LR+1, "%s", realm);

    mysql_real_escape_string(conn, euser, iuser, strlen(iuser));
    mysql_real_escape_string(conn, erealm, irealm, strlen(irealm));

    sprintf(sql, ctx->sql_delete, euser, erealm);

    log_debug(ZONE, "prepared sql: %s", sql);

    if(mysql_query(conn, sql) != 0) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: sql insert failed: %s", mysql_error(conn));
        return 1;
    }

    return 0;
}

static void _ar_mysql_free(authreg_t ar) {
    mysqlcontext_t ctx = (mysqlcontext_t) ar->private;
    MYSQL *conn = ctx->conn;

    if(conn != NULL)
       mysql_close(conn);

    free(ctx->sql_create);
    free(ctx->sql_select);
    free(ctx->sql_setpassword);
    free(ctx->sql_delete);
    free(ctx);
}

/** Provide a configuration parameter or default value. */
static char * _ar_mysql_param( config_t c, char * key, char * def ) {
    char * value = config_get_one( c, key, 0 );
    if( value == NULL )
      return def;
    else
      return value;
}

/* Ensure the sprintf template is less than 1K long and contains the */
/* required parameter placeholder types. The types string contains */
/* one each, in order, of the one character sprintf types that are */
/* expected to follow the escape characters '%' in the template. */
/* Returns 0 on success, or an error message on failures. */
static char * _ar_mysql_check_template( char * template, char * types ) {
    int pScan = 0;
    int pType = 0;
    char c;

    /* check that it's 1K or less */
    if( strlen( template ) > 1024 ) return "longer than 1024 characters";  

    /* count the parameter placeholders */
    while( pScan < strlen( template ) )
    {
      if( template[ pScan++ ] != '%' ) continue;
      
      c = template[ pScan++ ];
      if( c == '%' ) continue; /* ignore escaped precentages */
      if( c == types[ pType ] )
      {
	/* we found the placeholder */
	pType++;  /* search for the next type */
        continue;
      }

      /* we found an unexpected placeholder type */
      return "contained unexpected placeholder type";
    }

    if( pType < strlen( types ) )
      return "contained too few placeholders";
    else
      return 0;  
}

/* Ensure the SQL template is less than 1K long and contains the */
/* required parameter placeholders.  If there is an error, it is   */
/* written to the error log. */
/* Returns 0 on success, or 1 on errors. */
static int _ar_mysql_check_sql( authreg_t ar, char * sql, char * types ) {
  char * error;

  error = _ar_mysql_check_template( sql, types );
  if( error == 0 ) return 0;  /* alls right :) */

  /* signal error */
  log_write( ar->c2s->log, LOG_ERR, "mysql: template error: %s - %s", error, sql );
  return 1;
}

/** start me up */
DLLEXPORT int ar_init(authreg_t ar) {
    char *host, *port, *dbname, *user, *pass;
    char *create, *select, *setpassword, *delete;
    char *table, *username, *realm;
    char *template;
    int strlentur; /* string length of table, user, and realm strings */
    MYSQL *conn;
    mysqlcontext_t mysqlcontext;

    /* configure the database context with field names and SQL statements */
    mysqlcontext = (mysqlcontext_t) malloc( sizeof( struct mysqlcontext_st ) );
    ar->private = mysqlcontext;
    ar->free = _ar_mysql_free;

    /* determine our field names and table name */
    username = _ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.field.username"
	       , "username" ); 
    realm = _ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.field.realm"
	       , "realm" ); 
    mysqlcontext->field_password = _ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.field.password"
	       , "password" ); 
    table = _ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.table"
	       , "authreg" ); 

    /* craft the default SQL statements */
    /* we leave unused statements allocated to simplify code - a small price to pay */
    /* bounds checking and parameter format verification will be perfomed if the statement is used (see next section) */
    /* For malloc(), there is no +1 for trailing 0 as parameter substitution will net us several extra characters */

    strlentur = strlen( table ) + strlen( username) + strlen( realm );  /* avoid repetition */

    template = "INSERT INTO `%s` ( `%s`, `%s` ) VALUES ( '%%s', '%%s' )";
    create = malloc( strlen( template ) + strlentur ); 
    sprintf( create, template, table, username, realm );

    template = "SELECT `%s` FROM `%s` WHERE `%s` = '%%s' AND `%s` = '%%s'";
    select = malloc( strlen( template )
		     + strlen( mysqlcontext->field_password )
		     + strlentur ); 
    sprintf( select, template
	     , mysqlcontext->field_password
	     , table, username, realm );

    template = "UPDATE `%s` SET `%s` = '%%s' WHERE `%s` = '%%s' AND `%s` = '%%s'";
    setpassword = malloc( strlen( template ) + strlentur + strlen( mysqlcontext->field_password ) ); 
    sprintf( setpassword, template, table, mysqlcontext->field_password, username, realm );

    template = "DELETE FROM `%s` WHERE `%s` = '%%s' AND `%s` = '%%s'";
    delete = malloc( strlen( template ) + strlentur ); 
    sprintf( delete, template, table, username, realm );

    /* allow the default SQL statements to be overridden; also verify the statements format and length */
    mysqlcontext->sql_create = strdup(_ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.sql.create"
           , create ));
    if( _ar_mysql_check_sql( ar, mysqlcontext->sql_create, "ss" ) != 0 ) return 1;

    mysqlcontext->sql_select = strdup(_ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.sql.select"
           , select ));
    if( _ar_mysql_check_sql( ar, mysqlcontext->sql_select, "ss" ) != 0 ) return 1;

    mysqlcontext->sql_setpassword = strdup(_ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.sql.setpassword"
           , setpassword ));
    if( _ar_mysql_check_sql( ar, mysqlcontext->sql_setpassword, "sss" ) != 0 ) return 1;

    mysqlcontext->sql_delete = strdup(_ar_mysql_param( ar->c2s->config
	       , "authreg.mysql.sql.delete"
           , delete ));
    if( _ar_mysql_check_sql( ar, mysqlcontext->sql_delete, "ss" ) != 0 ) return 1;

    /* echo our configuration to debug */
    log_debug( ZONE, "SQL to create account: %s", mysqlcontext->sql_create );
    log_debug( ZONE, "SQL to query user information: %s", mysqlcontext->sql_select );
    log_debug( ZONE, "SQL to set password: %s", mysqlcontext->sql_setpassword );
    log_debug( ZONE, "SQL to delete account: %s", mysqlcontext->sql_delete );

    free(create);
    free(select);
    free(setpassword);
    free(delete);

    host = config_get_one(ar->c2s->config, "authreg.mysql.host", 0);
    port = config_get_one(ar->c2s->config, "authreg.mysql.port", 0);
    dbname = config_get_one(ar->c2s->config, "authreg.mysql.dbname", 0);
    user = config_get_one(ar->c2s->config, "authreg.mysql.user", 0);
    pass = config_get_one(ar->c2s->config, "authreg.mysql.pass", 0);

    if(host == NULL || port == NULL || dbname == NULL || user == NULL || pass == NULL) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: invalid module config");
        return 1;
    }

    log_debug( ZONE, "mysql connecting as '%s' to database '%s' on %s:%s", user, dbname, host, port );

    conn = mysql_init(NULL);
    mysqlcontext->conn = conn;

    if(conn == NULL) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: unable to allocate database connection state");
        return 1;
    }

#if MYSQL_VERSION_ID > 32349
    /* Set mysql_options for client ver 3.23.50 or later (workaround for mysql bug in 3.23.49) */
    mysql_options(conn, MYSQL_READ_DEFAULT_GROUP, "jabberd");
#endif

    /* connect with CLIENT_INTERACTIVE to get a (possibly) higher timeout value than default */
    if(mysql_real_connect(conn, host, user, pass, dbname, atoi(port), NULL, CLIENT_INTERACTIVE) == NULL) {
        log_write(ar->c2s->log, LOG_ERR, "mysql: connection to database failed: %s", mysql_error(conn));
        return 1;
    }

    mysql_query(conn, "SET NAMES 'utf8'");

    /* Set reconnect flag to 1 (set to 0 by default from mysql 5 on) */
    conn->reconnect = 1;

    ar->user_exists = _ar_mysql_user_exists;
    ar->get_password = _ar_mysql_get_password;
    ar->set_password = _ar_mysql_set_password;
    ar->create_user = _ar_mysql_create_user;
    ar->delete_user = _ar_mysql_delete_user;

    return 0;
}