/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 2019, 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.haxx.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.
 *
 ***************************************************************************/
#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 */
}

UNITTEST_START

/* introduce a scope and prove the corner case with write overflow,
 * so we can prove this test would detect it and that it is properly fixed
 */
do {
const char *bad = "this.is.a.hostname.where.each.individual.part.is.within."
                  "the.sixtythree.character.limit.but.still.long.enough.to."
                  "trigger.the.the.buffer.overflow......it.is.chosen.to.be."
                  "of.a.length.such.that.it.causes.a.two.byte.buffer......."
                  "overwrite.....making.it.longer.causes.doh.encode.to....."
                  ".return.early.so.dont.change.its.length.xxxx.xxxxxxxxxxx"
                  "..xxxxxx.....xx..........xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
                  "xxxxxxxxxxxxxxxxxxxxxxxxxx.xxxxxxxxxxxxxxxx..x......xxxx"
                  "xxxx..xxxxxxxxxxxxxxxxxxx.x...xxxx.x.x.x...xxxxx";

/* plays the role of struct dnsprobe in urldata.h */
struct demo {
    unsigned char dohbuffer[512];
    unsigned char canary1;
    unsigned char canary2;
    unsigned char canary3;
};

size_t olen = 100000;
struct demo victim;
victim.canary1 = 87; /* magic numbers, arbritrarily picked */
victim.canary2 = 35;
victim.canary3 = 41;
DOHcode d = doh_encode(bad, DNS_TYPE_A, victim.dohbuffer,
                       sizeof(victim.dohbuffer), &olen);
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");
if(d == DOH_OK)
{
  fail_unless(olen <= sizeof(victim.dohbuffer), "wrote outside bounds");
  fail_unless(olen > strlen(bad), "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 *sunshine2 = "aa.com";

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");

/* add one letter, the response should be one longer */
size_t olen2 = magic1;
DOHcode 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 */
size_t olen;
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