bind/fuzz/dns_rdata_fromwire_text.c

/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * 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/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

#include <isc/buffer.h>
#include <isc/lex.h>
#include <isc/mem.h>
#include <isc/result.h>
#include <isc/util.h>

#include <dns/callbacks.h>
#include <dns/compress.h>
#include <dns/master.h>
#include <dns/rdata.h>
#include <dns/rdatatype.h>

#include "fuzz.h"

bool debug = false;

/*
 * Fuzz input to dns_rdata_fromwire(). Then convert the result
 * to text, back to wire format, to multiline text, and back to wire
 * format again, checking for consistency throughout the sequence.
 */

static isc_mem_t *mctx = NULL;
static isc_lex_t *lex = NULL;

int
LLVMFuzzerInitialize(int *argc __attribute__((unused)),
		     char ***argv __attribute__((unused))) {
	isc_lexspecials_t specials;

	isc_mem_create(&mctx);
	CHECK(isc_lex_create(mctx, 64, &lex));

	memset(specials, 0, sizeof(specials));
	specials[0] = 1;
	specials['('] = 1;
	specials[')'] = 1;
	specials['"'] = 1;
	isc_lex_setspecials(lex, specials);
	isc_lex_setcomments(lex, ISC_LEXCOMMENT_DNSMASTERFILE);

	return (0);
}

static void
nullmsg(dns_rdatacallbacks_t *cb, const char *fmt, ...) {
	va_list args;

	UNUSED(cb);

	if (debug) {
		va_start(args, fmt);
		vfprintf(stderr, fmt, args);
		fprintf(stderr, "\n");
		va_end(args);
	}
}

int
LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
	char totext[64 * 1044 * 4];
	dns_compress_t cctx;
	dns_rdatatype_t rdtype;
	dns_rdataclass_t rdclass;
	dns_rdatatype_t typelist[256] = { 1000 }; /* unknown */
	dns_rdataclass_t classlist[] = { dns_rdataclass_in, dns_rdataclass_hs,
					 dns_rdataclass_ch, dns_rdataclass_any,
					 60 };
	dns_rdata_t rdata1 = DNS_RDATA_INIT, rdata2 = DNS_RDATA_INIT,
		    rdata3 = DNS_RDATA_INIT;
	dns_rdatacallbacks_t callbacks;
	isc_buffer_t source, target;
	isc_result_t result;
	unsigned char fromtext[1024];
	unsigned char fromwire[1024];
	unsigned char towire[1024];
	unsigned int classes = (sizeof(classlist) / sizeof(classlist[0]));
	unsigned int types = 1, flags, t;

	/*
	 * First 2 bytes are used to select type and class.
	 * dns_rdata_fromwire() only accepts input up to 2^16-1 octets.
	 */
	if (size < 2 || size > 0xffff + 2) {
		return (0);
	}

	/*
	 * Append known types to list.
	 */
	for (t = 1; t <= 0x10000; t++) {
		char typebuf[256];
		if (dns_rdatatype_ismeta(t)) {
			continue;
		}
		dns_rdatatype_format(t, typebuf, sizeof(typebuf));
		if (strncmp(typebuf, "TYPE", 4) != 0) {
			/* Assert when we need to grow typelist. */
			assert(types < sizeof(typelist) / sizeof(typelist[0]));
			typelist[types++] = t;
		}
	}

	/*
	 * Random type and class from a limited set.
	 */
	rdtype = typelist[(*data++) % types];
	size--;
	rdclass = classlist[(*data++) % classes];
	size--;

	if (debug) {
		fprintf(stderr, "type=%u, class=%u\n", rdtype, rdclass);
	}

	dns_rdatacallbacks_init(&callbacks);
	callbacks.warn = callbacks.error = nullmsg;

	isc_buffer_constinit(&source, data, size);
	isc_buffer_add(&source, size);
	isc_buffer_setactive(&source, size);

	isc_buffer_init(&target, fromwire, sizeof(fromwire));

	/*
	 * Reject invalid rdata. (Disallow decompression as we are
	 * reading a packet)
	 */
	CHECK(dns_rdata_fromwire(&rdata1, rdclass, rdtype, &source,
				 DNS_DECOMPRESS_NEVER, 0, &target));
	assert(rdata1.length == size);

	/*
	 * Convert to text from wire.
	 */
	isc_buffer_init(&target, totext, sizeof(totext) - 1);
	result = dns_rdata_totext(&rdata1, NULL, &target);
	assert(result == ISC_R_SUCCESS);

	/*
	 * Make debugging easier by NUL terminating.
	 */
	totext[isc_buffer_usedlength(&target)] = 0;

	/*
	 * Convert to wire from text.
	 */
	isc_buffer_constinit(&source, totext, isc_buffer_usedlength(&target));
	isc_buffer_add(&source, isc_buffer_usedlength(&target));
	CHECK(isc_lex_openbuffer(lex, &source));

	isc_buffer_init(&target, fromtext, sizeof(fromtext));
	result = dns_rdata_fromtext(&rdata2, rdclass, rdtype, lex, dns_rootname,
				    0, mctx, &target, &callbacks);
	if (debug && result != ISC_R_SUCCESS) {
		fprintf(stderr, "'%s'\n", totext);
	}
	assert(result == ISC_R_SUCCESS);
	assert(rdata2.length == size);
	assert(!memcmp(rdata2.data, data, size));

	/*
	 * Convert to multi-line text from wire.
	 */
	isc_buffer_init(&target, totext, sizeof(totext));
	flags = dns_master_styleflags(&dns_master_style_default);
	result = dns_rdata_tofmttext(&rdata1, dns_rootname, flags, 80 - 32, 4,
				     "\n", &target);
	assert(result == ISC_R_SUCCESS);

	/*
	 * Convert to wire from text.
	 */
	isc_buffer_constinit(&source, totext, isc_buffer_usedlength(&target));
	isc_buffer_add(&source, isc_buffer_usedlength(&target));
	CHECK(isc_lex_openbuffer(lex, &source));

	isc_buffer_init(&target, fromtext, sizeof(fromtext));
	result = dns_rdata_fromtext(&rdata3, rdclass, rdtype, lex, dns_rootname,
				    0, mctx, &target, &callbacks);
	assert(result == ISC_R_SUCCESS);
	assert(rdata3.length == size);
	assert(!memcmp(rdata3.data, data, size));

	/*
	 * Convert rdata back to wire.
	 */
	CHECK(dns_compress_init(&cctx, mctx));
	dns_compress_disable(&cctx);
	isc_buffer_init(&target, towire, sizeof(towire));
	result = dns_rdata_towire(&rdata1, &cctx, &target);
	dns_compress_invalidate(&cctx);
	assert(result == ISC_R_SUCCESS);
	assert(target.used == size);
	assert(!memcmp(target.base, data, size));

	return (0);
}