dlz_postgres_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_POSTGRES

#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_postgres_driver.h>

/* temporarily include time. */
#include <time.h>

#include <libpq-fe.h>

static dns_sdlzimplementation_t *dlz_postgres = NULL;

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

/*
 * Private methods
 */

/* ---------------
 * 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 function was originally called PQescapeString and renamed
 * to postgres_makesafe to avoid a naming collision.
 * PQescapeString is a new function made available in Postgres 7.2.
 * For some reason the function is not properly exported on Win32
 * builds making the function unavailable on Windows.  Also, since
 * this function is new it would require building this driver with
 * the libpq 7.2.  By borrowing this function the Windows problem
 * is solved, and the dependence on libpq 7.2 is removed.  Libpq is
 * still required of course, but an older version should work now too.
 *
 * 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
postgres_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;
}

#ifdef ISC_PLATFORM_USETHREADS

/*%
 * Properly cleans up a list of database instances.
 * This function is only used when the driver is compiled for
 * multithreaded operation.
 */
static void
postgres_destroy_dblist(db_list_t *dblist)
{

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

	/* get the first DBI in the list */
	ndbi = ISC_LIST_HEAD(*dblist);

	/* loop through the list */
	while (ndbi != NULL) {
		dbi = ndbi;
		/* get the next DBI in the list */
		ndbi = ISC_LIST_NEXT(dbi, link);
		/* release DB connection */
		if (dbi->dbconn != NULL)
			PQfinish((PGconn *) dbi->dbconn);
		/* release all memory that comprised a DBI */
		destroy_sqldbinstance(dbi);
	}
	/* release memory for the list structure */
	isc_mem_put(ns_g_mctx, dblist, sizeof(db_list_t));
}

/*%
 * 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.
 */

static dbinstance_t *
postgres_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,
		      "Postgres 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 *
postgres_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;

	postgres_makesafe(outstr, instr, len);
	/* PQescapeString(outstr, instr, len); */

	return outstr;
}

/*%
 * 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.  Postgres is nice, in that once the result
 * set is returned, we can make the db connection available for another
 * thread to use, while this thread continues on.  So, the DBI is made
 * available ASAP by unlocking the instance_lock after we have cleaned
 * it up properly.
 */
static isc_result_t
postgres_get_resultset(const char *zone, const char *record,
		       const char *client, unsigned int query,
		       void *dbdata, PGresult **rs)
{
	isc_result_t result;
	dbinstance_t *dbi = NULL;
	char *querystring = NULL;
	unsigned int i = 0;
	unsigned int j = 0;

	/* temporarily get a unique thread # */
	unsigned int dlz_thread_num = 1+(int) (1000.0*rand()/(RAND_MAX+1.0));

	REQUIRE(*rs == NULL);

	/* temporary logging message */
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
		      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
		      "%d Getting DBI", dlz_thread_num);

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

	/* find an available DBI from the list */
	dbi = postgres_find_avail_conn((db_list_t *) dbdata);

#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 *) dbdata;

#endif /* ISC_PLATFORM_USETHREADS */

	/* temporary logging message */
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
		      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
		      "%d Got DBI - checking query", dlz_thread_num);

	/* 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!!!
		 */
		if (dbi->allnodes_q == NULL) {
			result = ISC_R_NOTIMPLEMENTED;
			goto cleanup;
		}
		break;
	case ALLOWXFR:
		/* same as comments as ALLNODES */
		if (dbi->allowxfr_q == NULL) {
			result = ISC_R_NOTIMPLEMENTED;
			goto cleanup;
		}
		break;
	case AUTHORITY:
		/* same as comments as ALLNODES */
		if (dbi->authority_q == NULL) {
			result = ISC_R_NOTIMPLEMENTED;
			goto cleanup;
		}
		break;
	case FINDZONE:
		/* this is required.  It's the whole point of DLZ! */
		if (dbi->findzone_q == NULL) {
			isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
				      DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
				      "No query specified for findzone.  "
				      "Findzone requires a query");
			result = ISC_R_FAILURE;
			goto cleanup;
		}
		break;
	case LOOKUP:
		/* this is required.  It's also a major point of DLZ! */
		if (dbi->lookup_q == NULL) {
			isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
				      DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
				      "No query specified for lookup.  "
				      "Lookup requires a query");
			result = ISC_R_FAILURE;
			goto cleanup;
		}
		break;
	default:
		/*
		 * this should never happen.  If it does, the code is
		 * screwed up!
		 */
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "Incorrect query flag passed to "
				 "postgres_get_resultset");
		result = ISC_R_UNEXPECTED;
		goto cleanup;
	}

	/* temporary logging message */
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
		      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
		      "%d checked query", dlz_thread_num);

	/*
	 * was a zone string passed?  If so, make it safe for use in
	 * queries.
	 */
	if (zone != NULL) {
		dbi->zone = postgres_escape_string(zone);
		if (dbi->zone == NULL) {
			result = ISC_R_NOMEMORY;
			goto cleanup;
		}
	} else {	/* no string passed, set the string pointer to NULL */
		dbi->zone = NULL;
	}

	/* temporary logging message */
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
		      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
		      "%d did zone", dlz_thread_num);

	/*
	 * was a record string passed?  If so, make it safe for use in
	 * queries.
	 */
	if (record != NULL) {
		dbi->record = postgres_escape_string(record);
		if (dbi->record == NULL) {
			result = ISC_R_NOMEMORY;
			goto cleanup;
		}
	} else {	/* no string passed, set the string pointer to NULL */
		dbi->record = NULL;
	}


	/* temporary logging message */
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
		      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
		      "%d did record", dlz_thread_num);

	/*
	 * was a client string passed?  If so, make it safe for use in
	 * queries.
	 */
	if (client != NULL) {
		dbi->client = postgres_escape_string(client);
		if (dbi->client == NULL) {
			result = ISC_R_NOMEMORY;
			goto cleanup;
		}
	} else {	/* no string passed, set the string pointer to NULL */