dlz_odbc_driver.c

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/*
 * Copyright (C) 2002 Stichting NLnet, Netherlands, [e-mail].
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the
 * above copyright notice and this permission notice appear in all
 * copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND STICHTING NLNET
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * STICHTING NLNET BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE
 * USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * The development of Dynamically Loadable Zones (DLZ) for Bind 9 was
 * conceived and contributed by Rob Butler.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the
 * above copyright notice and this permission notice appear in all
 * copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ROB BUTLER
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * ROB BUTLER BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE
 * USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifdef DLZ_ODBC

#include <config.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <dns/log.h>
#include <dns/sdlz.h>
#include <dns/result.h>

#include <isc/mem.h>
#include <isc/platform.h>
#include <isc/print.h>
#include <isc/result.h>
#include <isc/string.h>
#include <isc/util.h>

#include <named/globals.h>

#include <dlz/sdlz_helper.h>
#include <dlz/dlz_odbc_driver.h>

#include <sql.h>
#include <sqlext.h>
#include <sqltypes.h>

static dns_sdlzimplementation_t *dlz_odbc = NULL;

#define dbc_search_limit 30
#define ALLNODES 1
#define ALLOWXFR 2
#define AUTHORITY 3
#define FINDZONE 4
#define LOOKUP 5

#define sqlOK(a) ((a == SQL_SUCCESS || a == SQL_SUCCESS_WITH_INFO) ? -1 : 0)

/*
 * Private Structures
 */

/*
 * structure to hold ODBC connection & statement
 */

typedef struct{
	SQLHDBC   dbc;
	SQLHSTMT  stmnt;
} odbc_db_t;

/*
 * Structure to hold everthing needed by this "instance" of the odbc driver
 * remember, the driver code is only loaded once, but may have many separate
 * instances
 */

typedef struct {

#ifdef ISC_PLATFORM_USETHREADS

    db_list_t    *db;       /* handle to a list of DB */

#else

    dbinstance_t *db;       /* handle to db */

#endif

    SQLHENV      sql_env;  /* handle to SQL environment */
    SQLCHAR      *dsn;
    SQLCHAR      *user;
    SQLCHAR      *pass;
} odbc_instance_t;

/* forward reference */

static size_t
odbc_makesafe(char *to, const char *from, size_t length);

/*
 * Private methods
 */

static SQLSMALLINT
safeLen(void *a) {
	if (a == NULL)
		return 0;
	return strlen((char *) a);
}

/*% propertly cleans up an odbc_instance_t */

static void
destroy_odbc_instance(odbc_instance_t *odbc_inst) {

#ifdef ISC_PLATFORM_USETHREADS

	dbinstance_t *ndbi = NULL;
	dbinstance_t *dbi = NULL;

	/* get the first DBI in the list */
	ndbi = ISC_LIST_HEAD(*odbc_inst->db);

	/* loop through the list */
	while (ndbi != NULL) {
		dbi = ndbi;
		/* get the next DBI in the list */
		ndbi = ISC_LIST_NEXT(dbi, link);

		/* if we have a connection / statement object in memory */
		if (dbi->dbconn != NULL) {
			/* free statement handle */
			if (((odbc_db_t *) (dbi->dbconn))->stmnt != NULL) {
				SQLFreeHandle(SQL_HANDLE_STMT,
					      ((odbc_db_t *)
					       (dbi->dbconn))->stmnt);
				((odbc_db_t *) (dbi->dbconn))->stmnt = NULL;
			}

			/* disconnect from database & free connection handle */
			if (((odbc_db_t *) (dbi->dbconn))->dbc != NULL) {
				SQLDisconnect(((odbc_db_t *)
					       dbi->dbconn)->dbc);
				SQLFreeHandle(SQL_HANDLE_DBC,
					      ((odbc_db_t *)
					       (dbi->dbconn))->dbc);
				((odbc_db_t *) (dbi->dbconn))->dbc = NULL;
			}

			/* free memory that held connection & statement. */
			isc_mem_free(ns_g_mctx, dbi->dbconn);
		}
		/* release all memory that comprised a DBI */
		destroy_sqldbinstance(dbi);
	}
	/* release memory for the list structure */
	isc_mem_put(ns_g_mctx, odbc_inst->db, sizeof(db_list_t));

#else /* ISC_PLATFORM_USETHREADS */

	/* free statement handle */
	if (((odbc_db_t *) (odbc_inst->db->dbconn))->stmnt != NULL) {
		SQLFreeHandle(SQL_HANDLE_STMT,
			      ((odbc_db_t *) (odbc_inst->db->dbconn))->stmnt);
		((odbc_db_t *) (odbc_inst->db->dbconn))->stmnt = NULL;
	}

	/* disconnect from database, free connection handle */
	if (((odbc_db_t *) (odbc_inst->db->dbconn))->dbc != NULL) {
		SQLDisconnect(((odbc_db_t *) (odbc_inst->db->dbconn))->dbc);
		SQLFreeHandle(SQL_HANDLE_DBC,
			      ((odbc_db_t *) (odbc_inst->db->dbconn))->dbc);
		((odbc_db_t *) (odbc_inst->db->dbconn))->dbc = NULL;
	}
	/*	free mem for the odbc_db_t structure held in db */
	if (((odbc_db_t *) odbc_inst->db->dbconn) != NULL) {
		isc_mem_free(ns_g_mctx, odbc_inst->db->dbconn);
		odbc_inst->db->dbconn = NULL;
	}

	if (odbc_inst->db != NULL)
		destroy_sqldbinstance(odbc_inst->db);

#endif /* ISC_PLATFORM_USETHREADS */


	/* free sql environment */
	if (odbc_inst->sql_env != NULL)
		SQLFreeHandle(SQL_HANDLE_ENV, odbc_inst->sql_env);

	/* free ODBC instance strings */
	if (odbc_inst->dsn != NULL)
		isc_mem_free(ns_g_mctx, odbc_inst->dsn);
	if (odbc_inst->pass != NULL)
		isc_mem_free(ns_g_mctx, odbc_inst->pass);
	if (odbc_inst->user != NULL)
		isc_mem_free(ns_g_mctx, odbc_inst->user);

	/* free memory for odbc_inst */
	if (odbc_inst != NULL)
		isc_mem_put(ns_g_mctx, odbc_inst, sizeof(odbc_instance_t));

}

/*% Connects to database, and creates ODBC statements */

static isc_result_t
odbc_connect(odbc_instance_t *dbi, odbc_db_t **dbc) {

	odbc_db_t *ndb = *dbc;
	SQLRETURN sqlRes;
	isc_result_t result = ISC_R_SUCCESS;

	if (ndb != NULL) {
		/*
		 * if db != null, we have to do some cleanup
		 * if statement handle != null free it
		 */
		if (ndb->stmnt != NULL) {
			SQLFreeHandle(SQL_HANDLE_STMT, ndb->stmnt);
			ndb->stmnt = NULL;
		}

		/* if connection handle != null free it */
		if (ndb->dbc != NULL) {
			SQLFreeHandle(SQL_HANDLE_DBC, ndb->dbc);
			ndb->dbc = NULL;
		}
	} else {
		ndb = isc_mem_allocate(ns_g_mctx, sizeof(odbc_db_t));
		if (ndb == NULL) {
			isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
				      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
				      "Odbc driver unable to allocate memory");
			return ISC_R_NOMEMORY;
		}
		memset(ndb, 0, sizeof(odbc_db_t));
	}

	sqlRes = SQLAllocHandle(SQL_HANDLE_DBC, dbi->sql_env, &(ndb->dbc));
	if (!sqlOK(sqlRes)) {
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
			      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
			      "Odbc driver unable to allocate memory");
		result = ISC_R_NOMEMORY;
		goto cleanup;
	}

	sqlRes = SQLConnect(ndb->dbc, dbi->dsn, safeLen(dbi->dsn), dbi->user,
			    safeLen(dbi->user), dbi->pass, safeLen(dbi->pass));
	if (!sqlOK(sqlRes)) {
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
			      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
			      "Odbc driver unable to connect");
		result = ISC_R_FAILURE;
		goto cleanup;
	}

	sqlRes = SQLAllocHandle(SQL_HANDLE_STMT, ndb->dbc, &(ndb->stmnt));
	if (!sqlOK(sqlRes)) {
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
			      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
			      "Odbc driver unable to allocate memory");
		result = ISC_R_NOMEMORY;
		goto cleanup;
	}

	*dbc = ndb;

	return ISC_R_SUCCESS;

 cleanup:

	if (ndb != NULL) {

		/* if statement handle != null free it */
		if (ndb->stmnt != NULL) {
			SQLFreeHandle(SQL_HANDLE_STMT, ndb->stmnt);
			ndb->stmnt = NULL;
		}

		/* if connection handle != null free it */
		if (ndb->dbc != NULL) {
			SQLDisconnect(ndb->dbc);
			SQLFreeHandle(SQL_HANDLE_DBC, ndb->dbc);
			ndb->dbc = NULL;
		}
		/* free memory holding ndb */
		isc_mem_free(ns_g_mctx, ndb);
	}

	return result;
}

/*%
 * Loops through the list of DB instances, attempting to lock
 * on the mutex.  If successful, the DBI is reserved for use
 * and the thread can perform queries against the database.
 * If the lock fails, the next one in the list is tried.
 * looping continues until a lock is obtained, or until
 * the list has been searched dbc_search_limit times.
 * This function is only used when the driver is compiled for
 * multithreaded operation.
 */

#ifdef ISC_PLATFORM_USETHREADS

static dbinstance_t *
odbc_find_avail_conn(db_list_t *dblist)
{
	dbinstance_t *dbi = NULL;
	dbinstance_t *head;
	int count = 0;

	/* get top of list */
	head = dbi = ISC_LIST_HEAD(*dblist);

	/* loop through list */
	while (count < dbc_search_limit) {
		/* try to lock on the mutex */
		if (isc_mutex_trylock(&dbi->instance_lock) == ISC_R_SUCCESS)
			return dbi; /* success, return the DBI for use. */

		/* not successful, keep trying */
		dbi = ISC_LIST_NEXT(dbi, link);

		/* check to see if we have gone to the top of the list. */
		if (dbi == NULL) {
			count++;
			dbi = head;
		}
	}
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
		      DNS_LOGMODULE_DLZ, ISC_LOG_INFO,
		      "Odbc driver unable to find available "
		      "connection after searching %d times",
		      count);
	return NULL;
}

#endif /* ISC_PLATFORM_USETHREADS */

/*% Allocates memory for a new string, and then constructs the new
 * string by "escaping" the input string.  The new string is
 * safe to be used in queries.  This is necessary because we cannot
 * be sure of what types of strings are passed to us, and we don't
 * want special characters in the string causing problems.
 */

static char *
odbc_escape_string(const char *instr) {

	char *outstr;
	unsigned int len;

	if (instr == NULL)
		return NULL;

	len = strlen(instr);

	outstr = isc_mem_allocate(ns_g_mctx ,(2 * len * sizeof(char)) + 1);
	if (outstr == NULL)
		return NULL;

	odbc_makesafe(outstr, instr, len);

	return outstr;
}

/* ---------------
 * Escaping arbitrary strings to get valid SQL strings/identifiers.
 *
 * Replaces "\\" with "\\\\" and "'" with "''".
 * length is the length of the buffer pointed to by
 * from.  The buffer at to must be at least 2*length + 1 characters
 * long.  A terminating NUL character is written.
 *
 * NOTICE!!!
 * This function was borrowed directly from PostgreSQL's libpq.
 *
 * The copyright statements from the original file containing this
 * function are included below:
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 * ---------------
 */

static size_t
odbc_makesafe(char *to, const char *from, size_t length)
{
	const char *source = from;
	char	   *target = to;
	unsigned int remaining = length;

	while (remaining > 0)
	{
		switch (*source)
		{
			case '\\':
				*target = '\\';
				target++;
				*target = '\\';
				/* target and remaining are updated below. */
				break;

			case '\'':
				*target = '\'';
				target++;
				*target = '\'';
				/* target and remaining are updated below. */
				break;

			default:
				*target = *source;
				/* target and remaining are updated below. */
		}
		source++;
		target++;
		remaining--;
	}

	/* Write the terminating NUL character. */
	*target = '\0';

	return target - to;
}

/*%
 * This function is the real core of the driver.   Zone, record
 * and client strings are passed in (or NULL is passed if the
 * string is not available).  The type of query we want to run
 * is indicated by the query flag, and the dbdata object is passed
 * passed in to.  dbdata really holds either:
 *		1) a list of database instances (in multithreaded mode) OR
 *		2) a single database instance (in single threaded mode)
 * The function will construct the query and obtain an available
 * database instance (DBI).  It will then run the query and hopefully
 * obtain a result set.  The data base instance that is used is returned
 * to the caller so they can get the data from the result set from it.
 * If successfull, it will be the responsibility of the caller to close
 * the cursor, and unlock the mutex of the DBI when they are done with it.
 * If not successfull, this function will perform all the cleanup.
 */


static isc_result_t
odbc_get_resultset(const char *zone, const char *record,
		   const char *client, unsigned int query,
		   void *dbdata, dbinstance_t **r_dbi)
{

	isc_result_t result;
	dbinstance_t *dbi = NULL;
	char *querystring = NULL;
	unsigned int j = 0;
	SQLRETURN sqlRes;

	REQUIRE(*r_dbi == NULL);

	/* get db instance / connection */
#ifdef ISC_PLATFORM_USETHREADS

	/* find an available DBI from the list */
	dbi = odbc_find_avail_conn(((odbc_instance_t *) dbdata)->db);

#else /* ISC_PLATFORM_USETHREADS */

	/*
	 * only 1 DBI - no need to lock instance lock either
	 * only 1 thread in the whole process, no possible contention.
	 */
	dbi =  (dbinstance_t *) ((odbc_instance_t *) dbdata)->db;

#endif /* ISC_PLATFORM_USETHREADS */

	/* if DBI is null, can't do anything else */
	if (dbi == NULL) {
		result = ISC_R_FAILURE;
		goto cleanup;
	}

	/* what type of query are we going to run? */
	switch(query) {
	case ALLNODES:
		/*
		 * if the query was not passed in from the config file
		 * then we can't run it.  return not_implemented, so
		 * it's like the code for that operation was never
		 * built into the driver.... AHHH flexibility!!!
		 */