/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0 and ISC
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 */

/*
 * Copyright (C) Stichting NLnet, Netherlands, stichting@nlnet.nl.
 * Copyright (C) John Eaglesham
 *
 * 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 THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR 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.
 */

#include "dlz_perl_driver.h"
#include <EXTERN.h>
#include <perl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <dlz_minimal.h>

#define BUF_LEN 64 /* Should be big enough, right? hah */

/* Enable debug logging? */
#if 0
#define carp(...) cd->log(ISC_LOG_INFO, __VA_ARGS__);
#else /* if 0 */
#define carp(...)
#endif /* if 0 */

#ifndef MULTIPLICITY
/* This is a pretty terrible work-around for handling HUP/rndc reconfig, but
 * the way BIND/DLZ handles reloads causes it to create a second back end
 * before removing the first. In the case of a single global interpreter,
 * serious problems arise. We can hack around this, but it's much better to do
 * it properly and link against a perl compiled with multiplicity. */
static PerlInterpreter *global_perl = NULL;
static int global_perl_dont_free = 0;
#endif /* ifndef MULTIPLICITY */

typedef struct config_data {
	PerlInterpreter *perl;
	char *perl_source;
	SV *perl_class;

	/* Functions given to us by bind9 */
	log_t *log;
	dns_sdlz_putrr_t *putrr;
	dns_sdlz_putnamedrr_t *putnamedrr;
	dns_dlz_writeablezone_t *writeable_zone;
} config_data_t;

/* Note, this code generates warnings due to lost type qualifiers.  This code
 * is (almost) verbatim from perlembed, and is known to work correctly despite
 * the warnings.
 */
EXTERN_C void xs_init(pTHX);
EXTERN_C void
boot_DynaLoader(pTHX_ CV *cv);
EXTERN_C void
boot_DLZ_Perl__clientinfo(pTHX_ CV *cv);
EXTERN_C void
boot_DLZ_Perl(pTHX_ CV *cv);
EXTERN_C void
xs_init(pTHX) {
	const char *file = __FILE__;
	dXSUB_SYS;

	/* DynaLoader is a special case */
	newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
	newXS("DLZ_Perl::clientinfo::bootstrap", boot_DLZ_Perl__clientinfo,
	      file);
	newXS("DLZ_Perl::bootstrap", boot_DLZ_Perl, file);
}

/*
 * methods
 */

/*
 * remember a helper function, from the bind9 dlz_dlopen driver
 */
static void
b9_add_helper(config_data_t *state, const char *helper_name, void *ptr) {
	if (strcmp(helper_name, "log") == 0) {
		state->log = ptr;
	}
	if (strcmp(helper_name, "putrr") == 0) {
		state->putrr = ptr;
	}
	if (strcmp(helper_name, "putnamedrr") == 0) {
		state->putnamedrr = ptr;
	}
	if (strcmp(helper_name, "writeable_zone") == 0) {
		state->writeable_zone = ptr;
	}
}

int
dlz_version(unsigned int *flags) {
	UNUSED(flags);
	return (DLZ_DLOPEN_VERSION);
}

isc_result_t
dlz_allnodes(const char *zone, void *dbdata, dns_sdlzallnodes_t *allnodes) {
	config_data_t *cd = (config_data_t *)dbdata;
	isc_result_t retval;
	int rrcount, r;
	SV *record_ref;
	SV **rr_name;
	SV **rr_type;
	SV **rr_ttl;
	SV **rr_data;
#ifdef MULTIPLICITY
	PerlInterpreter *my_perl = cd->perl;
#endif /* ifdef MULTIPLICITY */
	dSP;

	PERL_SET_CONTEXT(cd->perl);
	ENTER;
	SAVETMPS;

	PUSHMARK(SP);
	XPUSHs(cd->perl_class);
	XPUSHs(sv_2mortal(newSVpv(zone, 0)));
	PUTBACK;

	carp("DLZ Perl: Calling allnodes for zone %s", zone);
	rrcount = call_method("allnodes", G_ARRAY | G_EVAL);
	carp("DLZ Perl: Call to allnodes returned rrcount of %i", rrcount);

	SPAGAIN;

	if (SvTRUE(ERRSV)) {
		(void)POPs;
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl: allnodes for zone %s died in eval: %s", zone,
			SvPV_nolen(ERRSV));
		retval = ISC_R_FAILURE;
		goto CLEAN_UP_AND_RETURN;
	}

	if (!rrcount) {
		retval = ISC_R_NOTFOUND;
		goto CLEAN_UP_AND_RETURN;
	}

	retval = ISC_R_SUCCESS;
	r = 0;
	while (r++ < rrcount) {
		record_ref = POPs;
		if ((!SvROK(record_ref)) ||
		    (SvTYPE(SvRV(record_ref)) != SVt_PVAV))
		{
			cd->log(ISC_LOG_ERROR,
				"DLZ Perl: allnodes for zone %s "
				"returned an invalid value "
				"(expected array of arrayrefs)",
				zone);
			retval = ISC_R_FAILURE;
			break;
		}

		record_ref = SvRV(record_ref);

		rr_name = av_fetch((AV *)record_ref, 0, 0);
		rr_type = av_fetch((AV *)record_ref, 1, 0);
		rr_ttl = av_fetch((AV *)record_ref, 2, 0);
		rr_data = av_fetch((AV *)record_ref, 3, 0);

		if (rr_name == NULL || rr_type == NULL || rr_ttl == NULL ||
		    rr_data == NULL)
		{
			cd->log(ISC_LOG_ERROR,
				"DLZ Perl: allnodes for zone %s "
				"returned an array that was missing data",
				zone);
			retval = ISC_R_FAILURE;
			break;
		}

		carp("DLZ Perl: Got record %s/%s = %s", SvPV_nolen(*rr_name),
		     SvPV_nolen(*rr_type), SvPV_nolen(*rr_data));
		retval = cd->putnamedrr(allnodes, SvPV_nolen(*rr_name),
					SvPV_nolen(*rr_type), SvIV(*rr_ttl),
					SvPV_nolen(*rr_data));
		if (retval != ISC_R_SUCCESS) {
			cd->log(ISC_LOG_ERROR,
				"DLZ Perl: putnamedrr in allnodes "
				"for zone %s failed with code %i "
				"(did lookup return invalid record data?)",
				zone, retval);
			break;
		}
	}

CLEAN_UP_AND_RETURN:
	PUTBACK;
	FREETMPS;
	LEAVE;

	carp("DLZ Perl: Returning from allnodes, r = %i, retval = %i", r,
	     retval);

	return (retval);
}

isc_result_t
dlz_allowzonexfr(void *dbdata, const char *name, const char *client) {
	config_data_t *cd = (config_data_t *)dbdata;
	int r;
	isc_result_t retval;
#ifdef MULTIPLICITY
	PerlInterpreter *my_perl = cd->perl;
#endif /* ifdef MULTIPLICITY */
	dSP;

	PERL_SET_CONTEXT(cd->perl);
	ENTER;
	SAVETMPS;

	PUSHMARK(SP);
	XPUSHs(cd->perl_class);
	XPUSHs(sv_2mortal(newSVpv(name, 0)));
	XPUSHs(sv_2mortal(newSVpv(client, 0)));
	PUTBACK;

	r = call_method("allowzonexfr", G_SCALAR | G_EVAL);
	SPAGAIN;

	if (SvTRUE(ERRSV)) {
		/*
		 * On error there's an undef at the top of the stack. Pop
		 * it away so we don't leave junk on the stack for the next
		 * caller.
		 */
		(void)POPs;
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl: allowzonexfr died in eval: %s",
			SvPV_nolen(ERRSV));
		retval = ISC_R_FAILURE;
	} else if (r == 0) {
		/* Client returned nothing -- zone not found. */
		retval = ISC_R_NOTFOUND;
	} else if (r > 1) {
		/* Once again, clean out the stack when possible. */
		while (r--) {
			POPi;
		}
		cd->log(ISC_LOG_ERROR, "DLZ Perl: allowzonexfr returned too "
				       "many parameters!");
		retval = ISC_R_FAILURE;
	} else {
		/*
		 * Client returned true/false -- we're authoritative for
		 * the zone.
		 */
		r = POPi;
		if (r) {
			retval = ISC_R_SUCCESS;
		} else {
			retval = ISC_R_NOPERM;
		}
	}

	PUTBACK;
	FREETMPS;
	LEAVE;
	return (retval);
}

#if DLZ_DLOPEN_VERSION < 3
isc_result_t
dlz_findzonedb(void *dbdata, const char *name)
#else  /* if DLZ_DLOPEN_VERSION < 3 */
isc_result_t
dlz_findzonedb(void *dbdata, const char *name, dns_clientinfomethods_t *methods,
	       dns_clientinfo_t *clientinfo)
#endif /* if DLZ_DLOPEN_VERSION < 3 */
{
	config_data_t *cd = (config_data_t *)dbdata;
	int r;
	isc_result_t retval;
#ifdef MULTIPLICITY
	PerlInterpreter *my_perl = cd->perl;
#endif /* ifdef MULTIPLICITY */

#if DLZ_DLOPEN_VERSION >= 3
	UNUSED(methods);
	UNUSED(clientinfo);
#endif /* if DLZ_DLOPEN_VERSION >= 3 */

	dSP;
	carp("DLZ Perl: findzone looking for '%s'", name);

	PERL_SET_CONTEXT(cd->perl);
	ENTER;
	SAVETMPS;

	PUSHMARK(SP);
	XPUSHs(cd->perl_class);
	XPUSHs(sv_2mortal(newSVpv(name, 0)));
	PUTBACK;

	r = call_method("findzone", G_SCALAR | G_EVAL);
	SPAGAIN;

	if (SvTRUE(ERRSV)) {
		/*
		 * On error there's an undef at the top of the stack. Pop
		 * it away so we don't leave junk on the stack for the next
		 * caller.
		 */
		(void)POPs;
		cd->log(ISC_LOG_ERROR, "DLZ Perl: findzone died in eval: %s",
			SvPV_nolen(ERRSV));
		retval = ISC_R_FAILURE;
	} else if (r == 0) {
		retval = ISC_R_FAILURE;
	} else if (r > 1) {
		/* Once again, clean out the stack when possible. */
		while (r--) {
			POPi;
		}
		cd->log(ISC_LOG_ERROR, "DLZ Perl: findzone returned too many "
				       "parameters!");
		retval = ISC_R_FAILURE;
	} else {
		r = POPi;
		if (r) {
			retval = ISC_R_SUCCESS;
		} else {
			retval = ISC_R_NOTFOUND;
		}
	}

	PUTBACK;
	FREETMPS;
	LEAVE;
	return (retval);
}

#if DLZ_DLOPEN_VERSION == 1
isc_result_t
dlz_lookup(const char *zone, const char *name, void *dbdata,
	   dns_sdlzlookup_t *lookup)
#else  /* if DLZ_DLOPEN_VERSION == 1 */
isc_result_t
dlz_lookup(const char *zone, const char *name, void *dbdata,
	   dns_sdlzlookup_t *lookup, dns_clientinfomethods_t *methods,
	   dns_clientinfo_t *clientinfo)
#endif /* if DLZ_DLOPEN_VERSION == 1 */
{
	isc_result_t retval;
	config_data_t *cd = (config_data_t *)dbdata;
	int rrcount, r;
	dlz_perl_clientinfo_opaque opaque;
	SV *record_ref;
	SV **rr_type;
	SV **rr_ttl;
	SV **rr_data;
#ifdef MULTIPLICITY
	PerlInterpreter *my_perl = cd->perl;
#endif /* ifdef MULTIPLICITY */

#if DLZ_DLOPEN_VERSION >= 2
	UNUSED(methods);
	UNUSED(clientinfo);
#endif /* if DLZ_DLOPEN_VERSION >= 2 */

	dSP;
	PERL_SET_CONTEXT(cd->perl);
	ENTER;
	SAVETMPS;

	opaque.methods = methods;
	opaque.clientinfo = clientinfo;

	PUSHMARK(SP);
	XPUSHs(cd->perl_class);
	XPUSHs(sv_2mortal(newSVpv(name, 0)));
	XPUSHs(sv_2mortal(newSVpv(zone, 0)));
	XPUSHs(sv_2mortal(newSViv((IV)&opaque)));
	PUTBACK;

	carp("DLZ Perl: Searching for name %s in zone %s", name, zone);
	rrcount = call_method("lookup", G_ARRAY | G_EVAL);
	carp("DLZ Perl: Call to lookup returned %i", rrcount);

	SPAGAIN;

	if (SvTRUE(ERRSV)) {
		(void)POPs;
		cd->log(ISC_LOG_ERROR, "DLZ Perl: lookup died in eval: %s",
			SvPV_nolen(ERRSV));
		retval = ISC_R_FAILURE;
		goto CLEAN_UP_AND_RETURN;
	}

	if (!rrcount) {
		retval = ISC_R_NOTFOUND;
		goto CLEAN_UP_AND_RETURN;
	}

	retval = ISC_R_SUCCESS;
	r = 0;
	while (r++ < rrcount) {
		record_ref = POPs;
		if ((!SvROK(record_ref)) ||
		    (SvTYPE(SvRV(record_ref)) != SVt_PVAV))
		{
			cd->log(ISC_LOG_ERROR, "DLZ Perl: lookup returned an "
					       "invalid value (expected array "
					       "of arrayrefs)!");
			retval = ISC_R_FAILURE;
			break;
		}

		record_ref = SvRV(record_ref);

		rr_type = av_fetch((AV *)record_ref, 0, 0);
		rr_ttl = av_fetch((AV *)record_ref, 1, 0);
		rr_data = av_fetch((AV *)record_ref, 2, 0);

		if (rr_type == NULL || rr_ttl == NULL || rr_data == NULL) {
			cd->log(ISC_LOG_ERROR,
				"DLZ Perl: lookup for record %s in "
				"zone %s returned an array that was "
				"missing data",
				name, zone);
			retval = ISC_R_FAILURE;
			break;
		}

		carp("DLZ Perl: Got record %s = %s", SvPV_nolen(*rr_type),
		     SvPV_nolen(*rr_data));
		retval = cd->putrr(lookup, SvPV_nolen(*rr_type), SvIV(*rr_ttl),
				   SvPV_nolen(*rr_data));

		if (retval != ISC_R_SUCCESS) {
			cd->log(ISC_LOG_ERROR,
				"DLZ Perl: putrr for lookup of %s in "
				"zone %s failed with code %i "
				"(did lookup return invalid record data?)",
				name, zone, retval);
			break;
		}
	}

CLEAN_UP_AND_RETURN:
	PUTBACK;
	FREETMPS;
	LEAVE;

	carp("DLZ Perl: Returning from lookup, r = %i, retval = %i", r, retval);

	return (retval);
}

static const char *
#ifdef MULTIPLICITY
missing_perl_method(const char *perl_class_name, PerlInterpreter *my_perl)
#else  /* ifdef MULTIPLICITY */
missing_perl_method(const char *perl_class_name)
#endif /* ifdef MULTIPLICITY */
{
	char full_name[BUF_LEN];
	const char *methods[] = { "new", "findzone", "lookup", NULL };
	int i = 0;

	while (methods[i] != NULL) {
		snprintf(full_name, BUF_LEN, "%s::%s", perl_class_name,
			 methods[i]);

		if (get_cv(full_name, 0) == NULL) {
			return (methods[i]);
		}
		i++;
	}

	return (NULL);
}

isc_result_t
dlz_create(const char *dlzname, unsigned int argc, char *argv[], void **dbdata,
	   ...) {
	config_data_t *cd;
	char *perlrun[] = { (char *)"", NULL, (char *)"dlz perl", NULL };
	char *perl_class_name;
	int r;
	va_list ap;
	const char *helper_name;
	const char *missing_method_name;
	char *call_argv_args = NULL;
#ifdef MULTIPLICITY
	PerlInterpreter *my_perl;
#endif /* ifdef MULTIPLICITY */

	cd = malloc(sizeof(config_data_t));
	if (cd == NULL) {
		return (ISC_R_NOMEMORY);
	}

	memset(cd, 0, sizeof(config_data_t));

	/* fill in the helper functions */
	va_start(ap, dbdata);
	while ((helper_name = va_arg(ap, const char *)) != NULL) {
		b9_add_helper(cd, helper_name, va_arg(ap, void *));
	}
	va_end(ap);

	if (argc < 2) {
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl '%s': Missing script argument.", dlzname);
		free(cd);
		return (ISC_R_FAILURE);
	}

	if (argc < 3) {
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl '%s': Missing class name argument.", dlzname);
		free(cd);
		return (ISC_R_FAILURE);
	}
	perl_class_name = argv[2];

	cd->log(ISC_LOG_INFO, "DLZ Perl '%s': Loading '%s' from location '%s'",
		dlzname, perl_class_name, argv[1], argc);

#ifndef MULTIPLICITY
	if (global_perl) {
		/*
		 * PERL_SET_CONTEXT not needed here as we're guaranteed to
		 * have an implicit context thanks to an undefined
		 * MULTIPLICITY.
		 */
		PL_perl_destruct_level = 1;
		perl_destruct(global_perl);
		perl_free(global_perl);
		global_perl = NULL;
		global_perl_dont_free = 1;
	}
#endif /* ifndef MULTIPLICITY */

	cd->perl = perl_alloc();
	if (cd->perl == NULL) {
		free(cd);
		return (ISC_R_FAILURE);
	}
#ifdef MULTIPLICITY
	my_perl = cd->perl;
#endif /* ifdef MULTIPLICITY */
	PERL_SET_CONTEXT(cd->perl);

	/*
	 * We will re-create the interpreter during an rndc reconfig, so we
	 * must set this variable per perlembed in order to insure we can
	 * clean up Perl at a later time.
	 */
	PL_perl_destruct_level = 1;
	perl_construct(cd->perl);
	PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
	/* Prevent crashes from clients writing to $0 */
	PL_origalen = 1;

	cd->perl_source = strdup(argv[1]);
	if (cd->perl_source == NULL) {
		free(cd);
		return (ISC_R_NOMEMORY);
	}

	perlrun[1] = cd->perl_source;
	if (perl_parse(cd->perl, xs_init, 3, perlrun, (char **)NULL)) {
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl '%s': Failed to parse Perl script, aborting",
			dlzname);
		goto CLEAN_UP_PERL_AND_FAIL;
	}

	/* Let Perl know about our callbacks. */
	call_argv("DLZ_Perl::clientinfo::bootstrap", G_DISCARD | G_NOARGS,
		  &call_argv_args);
	call_argv("DLZ_Perl::bootstrap", G_DISCARD | G_NOARGS, &call_argv_args);

	/*
	 * Run the script. We don't really need to do this since we have
	 * the init callback, but there's not really a downside either.
	 */
	if (perl_run(cd->perl)) {
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl '%s': Script exited with an error, aborting",
			dlzname);
		goto CLEAN_UP_PERL_AND_FAIL;
	}

#ifdef MULTIPLICITY
	if ((missing_method_name = missing_perl_method(perl_class_name,
						       my_perl)))
#else  /* ifdef MULTIPLICITY */
	if ((missing_method_name = missing_perl_method(perl_class_name)))
#endif /* ifdef MULTIPLICITY */
	{
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl '%s': Missing required function '%s', "
			"aborting",
			dlzname, missing_method_name);
		goto CLEAN_UP_PERL_AND_FAIL;
	}

	dSP;
	ENTER;
	SAVETMPS;

	PUSHMARK(SP);
	XPUSHs(sv_2mortal(newSVpv(perl_class_name, 0)));

	/* Build flattened hash of config info. */
	XPUSHs(sv_2mortal(newSVpv("log_context", 0)));
	XPUSHs(sv_2mortal(newSViv((IV)cd->log)));

	/* Argument to pass to new? */
	if (argc == 4) {
		XPUSHs(sv_2mortal(newSVpv("argv", 0)));
		XPUSHs(sv_2mortal(newSVpv(argv[3], 0)));
	}

	PUTBACK;

	r = call_method("new", G_EVAL | G_SCALAR);

	SPAGAIN;

	if (r) {
		cd->perl_class = SvREFCNT_inc(POPs);
	}

	PUTBACK;
	FREETMPS;
	LEAVE;

	if (SvTRUE(ERRSV)) {
		(void)POPs;
		cd->log(ISC_LOG_ERROR, "DLZ Perl '%s': new died in eval: %s",
			dlzname, SvPV_nolen(ERRSV));
		goto CLEAN_UP_PERL_AND_FAIL;
	}

	if (!r || !sv_isobject(cd->perl_class)) {
		cd->log(ISC_LOG_ERROR,
			"DLZ Perl '%s': new failed to return a blessed object",
			dlzname);
		goto CLEAN_UP_PERL_AND_FAIL;
	}

	*dbdata = cd;

#ifndef MULTIPLICITY
	global_perl = cd->perl;
#endif /* ifndef MULTIPLICITY */
	return (ISC_R_SUCCESS);

CLEAN_UP_PERL_AND_FAIL:
	PL_perl_destruct_level = 1;
	perl_destruct(cd->perl);
	perl_free(cd->perl);
	free(cd->perl_source);
	free(cd);
	return (ISC_R_FAILURE);
}

void
dlz_destroy(void *dbdata) {
	config_data_t *cd = (config_data_t *)dbdata;
#ifdef MULTIPLICITY
	PerlInterpreter *my_perl = cd->perl;
#endif /* ifdef MULTIPLICITY */

	cd->log(ISC_LOG_INFO, "DLZ Perl: Unloading driver.");

#ifndef MULTIPLICITY
	if (!global_perl_dont_free) {
#endif /* ifndef MULTIPLICITY */
		PERL_SET_CONTEXT(cd->perl);
		PL_perl_destruct_level = 1;
		perl_destruct(cd->perl);
		perl_free(cd->perl);
#ifndef MULTIPLICITY
		global_perl_dont_free = 0;
		global_perl = NULL;
	}
#endif /* ifndef MULTIPLICITY */

	free(cd->perl_source);
	free(cd);
}