/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 2019 - 2022, Daniel Stenberg, , 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 "curlcheck.h" #include "doh.h" /* from the lib dir */ static CURLcode unit_setup(void) { /* whatever you want done first */ return CURLE_OK; } static void unit_stop(void) { /* done before shutting down and exiting */ } #ifndef CURL_DISABLE_DOH UNITTEST_START /* * 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."; int 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 < (int)(sizeof(playlist)/sizeof(*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_encode(name, 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 = DNS_TYPE_A; unsigned char buffer[128]; const size_t buflen = sizeof(buffer); const size_t magic1 = 9765; size_t olen1 = magic1; const char *sunshine1 = "a.com"; const char *dotshine1 = "a.com."; const char *sunshine2 = "aa.com"; size_t olen2; DOHcode ret2; size_t olen; DOHcode ret = doh_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_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_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_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_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); UNITTEST_STOP #else /* CURL_DISABLE_DOH */ UNITTEST_START { return 1; /* nothing to do, just fail */ } UNITTEST_STOP #endif