branch: master
unit1655.c
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
#include "unitcheck.h"
#include "doh.h"
static CURLcode test_unit1655(const char *arg)
{
UNITTEST_BEGIN_SIMPLE
#ifndef CURL_DISABLE_DOH
/*
* Prove detection of write overflow using a short buffer and a name
* of maximal valid length.
*
* Prove detection of other invalid input.
*/
do {
static const char max[] =
/* ..|....1.........2.........3.........4.........5.........6... */
/* 3456789012345678901234567890123456789012345678901234567890123 */
"this.is.a.maximum-length.hostname." /* 34: 34 */
"with-no-label-of-greater-length-than-the-sixty-three-characters."
/* 64: 98 */
"specified.in.the.RFCs." /* 22: 120 */
"and.with.a.QNAME.encoding.whose.length.is.exactly." /* 50: 170 */
"the.maximum.length.allowed." /* 27: 197 */
"that.is.two-hundred.and.fifty-six." /* 34: 231 */
"including.the.last.null." /* 24: 255 */
"";
static const char toolong[] =
/* ..|....1.........2.........3.........4.........5.........6... */
/* 3456789012345678901234567890123456789012345678901234567890123 */
"here.is.a.hostname.which.is.just.barely.too.long." /* 49: 49 */
"to.be.encoded.as.a.QNAME.of.the.maximum.allowed.length."
/* 55: 104 */
"which.is.256.including.a.final.zero-length.label." /* 49: 153 */
"representing.the.root.node.so.that.a.name.with." /* 47: 200 */
"a.trailing.dot.may.have.up.to." /* 30: 230 */
"255.characters.never.more." /* 26: 256 */
"";
static const char emptylabel[] =
"this.is.an.otherwise-valid.hostname."
".with.an.empty.label.";
static const char outsizelabel[] =
"this.is.an.otherwise-valid.hostname."
"with-a-label-of-greater-length-than-the-sixty-three-characters-"
"specified.in.the.RFCs.";
size_t i;
struct test {
const char *name;
const DOHcode expected_result;
};
/* plays the role of struct dnsprobe in urldata.h */
struct demo {
unsigned char dohbuffer[255 + 16]; /* deliberately short buffer */
unsigned char canary1;
unsigned char canary2;
unsigned char canary3;
};
const struct test playlist[4] = {
{ toolong, DOH_DNS_NAME_TOO_LONG }, /* expect early failure */
{ emptylabel, DOH_DNS_BAD_LABEL }, /* also */
{ outsizelabel, DOH_DNS_BAD_LABEL }, /* also */
{ max, DOH_OK } /* expect buffer overwrite */
};
for(i = 0; i < CURL_ARRAYSIZE(playlist); i++) {
const char *name = playlist[i].name;
size_t olen = 100000;
struct demo victim;
DOHcode d;
victim.canary1 = 87; /* magic numbers, arbitrarily picked */
victim.canary2 = 35;
victim.canary3 = 41;
d = doh_req_encode(name, CURL_DNS_TYPE_A, victim.dohbuffer,
sizeof(struct demo), /* allow room for overflow */
&olen);
fail_unless(d == playlist[i].expected_result,
"result returned was not as expected");
if(d == playlist[i].expected_result) {
if(name == max) {
fail_if(victim.canary1 == 87,
"demo one-byte buffer overwrite did not happen");
}
else {
fail_unless(victim.canary1 == 87,
"one-byte buffer overwrite has happened");
}
fail_unless(victim.canary2 == 35,
"two-byte buffer overwrite has happened");
fail_unless(victim.canary3 == 41,
"three-byte buffer overwrite has happened");
}
else {
if(d == DOH_OK) {
fail_unless(olen <= sizeof(victim.dohbuffer),
"wrote outside bounds");
fail_unless(olen > strlen(name), "unrealistic low size");
}
}
}
} while(0);
/* run normal cases and try to trigger buffer length related errors */
do {
DNStype dnstype = CURL_DNS_TYPE_A;
unsigned char buffer[128];
const size_t buflen = sizeof(buffer);
const size_t magic1 = 9765;
size_t olen1 = magic1;
static const char *sunshine1 = "a.com";
static const char *dotshine1 = "a.com.";
static const char *sunshine2 = "aa.com";
size_t olen2;
DOHcode ret2;
size_t olen;
DOHcode ret = doh_req_encode(sunshine1, dnstype, buffer, buflen, &olen1);
fail_unless(ret == DOH_OK, "sunshine case 1 should pass fine");
fail_if(olen1 == magic1, "olen has not been assigned properly");
fail_unless(olen1 > strlen(sunshine1), "bad out length");
/* with a trailing dot, the response should have the same length */
olen2 = magic1;
ret2 = doh_req_encode(dotshine1, dnstype, buffer, buflen, &olen2);
fail_unless(ret2 == DOH_OK, "dotshine case should pass fine");
fail_if(olen2 == magic1, "olen has not been assigned properly");
fail_unless(olen1 == olen2, "olen should not grow for a trailing dot");
/* add one letter, the response should be one longer */
olen2 = magic1;
ret2 = doh_req_encode(sunshine2, dnstype, buffer, buflen, &olen2);
fail_unless(ret2 == DOH_OK, "sunshine case 2 should pass fine");
fail_if(olen2 == magic1, "olen has not been assigned properly");
fail_unless(olen1 + 1 == olen2, "olen should grow with the hostname");
/* pass a short buffer, should fail */
ret = doh_req_encode(sunshine1, dnstype, buffer, olen1 - 1, &olen);
fail_if(ret == DOH_OK, "short buffer should have been noticed");
/* pass a minimum buffer, should succeed */
ret = doh_req_encode(sunshine1, dnstype, buffer, olen1, &olen);
fail_unless(ret == DOH_OK, "minimal length buffer should be long enough");
fail_unless(olen == olen1, "bad buffer length");
} while(0);
#endif /* CURL_DISABLE_DOH */
UNITTEST_END_SIMPLE
}