c-ares/test/ares-test-misc.cc

/* MIT License
 *
 * Copyright (c) The c-ares project and its contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * SPDX-License-Identifier: MIT
 */
#include "ares-test.h"
#include "dns-proto.h"

#include <string>
#include <vector>

namespace ares {
namespace test {

TEST_F(DefaultChannelTest, GetServers) {
  std::string servers = GetNameServers(channel_);
  if (verbose) {
    std::cerr << "Nameserver: " << servers << std::endl;
  }
}

TEST_F(DefaultChannelTest, GetServersFailures) {
  EXPECT_EQ(ARES_SUCCESS,
            ares_set_servers_csv(channel_, "1.2.3.4,2.3.4.5"));
  struct ares_addr_node* servers = nullptr;
  SetAllocFail(1);
  EXPECT_EQ(ARES_ENOMEM, ares_get_servers(channel_, &servers));
  SetAllocFail(2);
  EXPECT_EQ(ARES_ENOMEM, ares_get_servers(channel_, &servers));
  EXPECT_EQ(ARES_ENODATA, ares_get_servers(nullptr, &servers));
}

TEST_F(DefaultChannelTest, SetServers) {
  /* NOTE: This test is because we have actual external users doing test case
   *       simulation and removing all servers to generate various error
   *       conditions in their own code.  It would make more sense to return
   *       ARES_ENODATA, but due to historical users, we can't break them.
   *       See: https://github.com/nodejs/node/pull/50800
   */
  EXPECT_EQ(ARES_SUCCESS, ares_set_servers(channel_, nullptr));
  std::string expected_empty = "";
  EXPECT_EQ(expected_empty, GetNameServers(channel_));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOSERVER, result.status_);


  struct ares_addr_node server1;
  struct ares_addr_node server2;
  server1.next = &server2;
  server1.family = AF_INET;
  server1.addr.addr4.s_addr = htonl(0x01020304);
  server2.next = nullptr;
  server2.family = AF_INET;
  server2.addr.addr4.s_addr = htonl(0x02030405);
  EXPECT_EQ(ARES_ENODATA, ares_set_servers(nullptr, &server1));

  EXPECT_EQ(ARES_SUCCESS, ares_set_servers(channel_, &server1));
  std::string expected = "1.2.3.4:53,2.3.4.5:53";
  EXPECT_EQ(expected, GetNameServers(channel_));
}

TEST_F(DefaultChannelTest, SetServersPorts) {
  /* NOTE: This test is because we have actual external users doing test case
   *       simulation and removing all servers to generate various error
   *       conditions in their own code.  It would make more sense to return
   *       ARES_ENODATA, but due to historical users, we can't break them.
   *       See: https://github.com/nodejs/node/pull/50800
   */
  EXPECT_EQ(ARES_SUCCESS, ares_set_servers_ports(channel_, nullptr));
  std::string expected_empty = "";
  EXPECT_EQ(expected_empty, GetNameServers(channel_));

  struct ares_addr_port_node server1;
  struct ares_addr_port_node server2;
  server1.next = &server2;
  server1.family = AF_INET;
  server1.addr.addr4.s_addr = htonl(0x01020304);
  server1.udp_port = 111;
  server1.tcp_port = 111;
  server2.next = nullptr;
  server2.family = AF_INET;
  server2.addr.addr4.s_addr = htonl(0x02030405);
  server2.udp_port = 0;
  server2.tcp_port = 0;
  EXPECT_EQ(ARES_ENODATA, ares_set_servers_ports(nullptr, &server1));

  EXPECT_EQ(ARES_SUCCESS, ares_set_servers_ports(channel_, &server1));
  std::string expected = "1.2.3.4:111,2.3.4.5:53";
  EXPECT_EQ(expected, GetNameServers(channel_));
}

TEST_F(DefaultChannelTest, SetServersCSV) {
  EXPECT_EQ(ARES_ENODATA, ares_set_servers_csv(nullptr, "1.2.3.4"));
  EXPECT_EQ(ARES_ENODATA, ares_set_servers_csv(nullptr, "xyzzy,plugh"));
  EXPECT_EQ(ARES_ENODATA, ares_set_servers_csv(nullptr, "256.1.2.3"));
  EXPECT_EQ(ARES_ENODATA, ares_set_servers_csv(nullptr, "1.2.3.4.5"));
  EXPECT_EQ(ARES_ENODATA, ares_set_servers_csv(nullptr, "1:2:3:4:5"));

  /* NOTE: This test is because we have actual external users doing test case
   *       simulation and removing all servers to generate various error
   *       conditions in their own code.  It would make more sense to return
   *       ARES_ENODATA, but due to historical users, we can't break them.
   *       See: https://github.com/nodejs/node/pull/50800
   */
  EXPECT_EQ(ARES_SUCCESS, ares_set_servers_csv(channel_, NULL));
  std::string expected_empty = "";
  EXPECT_EQ(expected_empty, GetNameServers(channel_));
  EXPECT_EQ(ARES_SUCCESS, ares_set_servers_csv(channel_, ""));
  EXPECT_EQ(expected_empty, GetNameServers(channel_));


  EXPECT_EQ(ARES_SUCCESS,
            ares_set_servers_csv(channel_, "1.2.3.4,0102:0304:0506:0708:0910:1112:1314:1516,2.3.4.5"));
  std::string expected = "1.2.3.4:53,[102:304:506:708:910:1112:1314:1516]:53,2.3.4.5:53";
  EXPECT_EQ(expected, GetNameServers(channel_));

  // Same, with spaces
  EXPECT_EQ(ARES_SUCCESS,
            ares_set_servers_csv(channel_, "1.2.3.4 , [0102:0304:0506:0708:0910:1112:1314:1516]:53, 2.3.4.5"));
  EXPECT_EQ(expected, GetNameServers(channel_));

  // Ignore invalid link-local interface, keep rest.
  EXPECT_EQ(ARES_SUCCESS,
            ares_set_servers_csv(channel_, "1.2.3.4 , [0102:0304:0506:0708:0910:1112:1314:1516]:53, [fe80::1]:53%iface0, 2.3.4.5"));
  EXPECT_EQ(expected, GetNameServers(channel_));

  // Same, with ports
  EXPECT_EQ(ARES_SUCCESS,
            ares_set_servers_ports_csv(channel_, "1.2.3.4:54,[0102:0304:0506:0708:0910:1112:1314:1516]:80,2.3.4.5:55"));
  std::string expected2 = {"1.2.3.4:54,[102:304:506:708:910:1112:1314:1516]:80,2.3.4.5:55"};
  EXPECT_EQ(expected2, GetNameServers(channel_));

  // Should survive duplication
  ares_channel_t *channel2;
  EXPECT_EQ(ARES_SUCCESS, ares_dup(&channel2, channel_));
  EXPECT_EQ(expected2, GetNameServers(channel2));
  ares_destroy(channel2);

  // Allocation failure cases
  for (int fail = 1; fail <= 5; fail++) {
    SetAllocFail(fail);
    EXPECT_EQ(ARES_ENOMEM,
              ares_set_servers_csv(channel_, "1.2.3.4,0102:0304:0506:0708:0910:1112:1314:1516,2.3.4.5"));
  }

  EXPECT_EQ(ARES_EBADSTR, ares_set_servers_csv(channel_, "2.3.4.5,1.2.3.4:,3.4.5.6"));
  EXPECT_EQ(ARES_EBADSTR, ares_set_servers_csv(channel_, "2.3.4.5,1.2.3.4:Z,3.4.5.6"));
}

TEST_F(DefaultChannelTest, TimeoutValue) {
  struct timeval tinfo;
  tinfo.tv_sec = 0;
  tinfo.tv_usec = 0;
  struct timeval tmax;
  tmax.tv_sec = 0;
  tmax.tv_usec = 10;
  struct timeval* pt;

  // No timers => get max back.
  pt = ares_timeout(channel_, &tmax, &tinfo);
  EXPECT_EQ(&tmax, pt);
  EXPECT_EQ(0, pt->tv_sec);
  EXPECT_EQ(10, pt->tv_usec);

  pt = ares_timeout(channel_, nullptr, &tinfo);
  EXPECT_EQ(nullptr, pt);

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);

  // Now there's a timer running.
  pt = ares_timeout(channel_, &tmax, &tinfo);
  EXPECT_EQ(&tmax, pt);
  EXPECT_EQ(0, pt->tv_sec);
  EXPECT_EQ(10, pt->tv_usec);

  tmax.tv_sec = 100;
  pt = ares_timeout(channel_, &tmax, &tinfo);
  EXPECT_EQ(&tinfo, pt);

  pt = ares_timeout(channel_, nullptr, &tinfo);
  EXPECT_EQ(&tinfo, pt);

  Process();
}

TEST_F(LibraryTest, InetNtoP) {
  struct in_addr addr;
  addr.s_addr = htonl(0x01020304);
  char buffer[256];
  EXPECT_EQ(buffer, ares_inet_ntop(AF_INET, &addr, buffer, sizeof(buffer)));
  EXPECT_EQ("1.2.3.4", std::string(buffer));
}

TEST_F(LibraryTest, Mkquery) {
  byte* p;
  int len;
  ares_mkquery("example.com", C_IN, T_A, 0x1234, 0, &p, &len);
  std::vector<byte> data(p, p + len);
  ares_free_string(p);

  std::string actual = PacketToString(data);
  DNSPacket pkt;
  pkt.set_qid(0x1234).add_question(new DNSQuestion("example.com", T_A));
  std::string expected = PacketToString(pkt.data());
  EXPECT_EQ(expected, actual);
}

TEST_F(LibraryTest, CreateQuery) {
  byte* p;
  int len;
  // This is hard to really test with escaping since DNS names don't allow
  // bad characters.  So we'll escape good characters.
  EXPECT_EQ(ARES_SUCCESS,
            ares_create_query("ex\\097m\\ple.com", C_IN, T_A, 0x1234, 0,
                              &p, &len, 0));
  std::vector<byte> data(p, p + len);
  ares_free_string(p);

  std::string actual = PacketToString(data);
  DNSPacket pkt;
  pkt.set_qid(0x1234).add_question(new DNSQuestion("example.com", T_A));
  std::string expected = PacketToString(pkt.data());
  EXPECT_EQ(expected, actual);
}

TEST_F(LibraryTest, CreateQueryTrailingEscapedDot) {
  byte* p;
  int len;
  EXPECT_EQ(ARES_SUCCESS,
            ares_create_query("example.com\\.", C_IN, T_A, 0x1234, 0,
                              &p, &len, 0));
  std::vector<byte> data(p, p + len);
  ares_free_string(p);

  std::string actual = PacketToString(data);
  EXPECT_EQ("REQ QRY  Q:{'example.com\\.' IN A}", actual);
}

TEST_F(LibraryTest, CreateQueryNameTooLong) {
  byte* p;
  int len;
  EXPECT_EQ(ARES_EBADNAME,
            ares_create_query(
              "a1234567890123456789.b1234567890123456789.c1234567890123456789.d1234567890123456789."
              "a1234567890123456789.b1234567890123456789.c1234567890123456789.d1234567890123456789."
              "a1234567890123456789.b1234567890123456789.c1234567890123456789.d1234567890123456789."
              "x1234567890123456789.y1234567890123456789.",
              C_IN, T_A, 0x1234, 0, &p, &len, 0));
}

TEST_F(LibraryTest, CreateQueryFailures) {
  byte* p;
  int len;
  // RC1035 has a 255 byte limit on names.
  std::string longname;
  for (int ii = 0; ii < 17; ii++) {
    longname += "fedcba9876543210";
  }
  p = nullptr;
  EXPECT_EQ(ARES_EBADNAME,
            ares_create_query(longname.c_str(), C_IN, T_A, 0x1234, 0,
                    &p, &len, 0));
  if (p) ares_free_string(p);

  SetAllocFail(1);

  p = nullptr;
  EXPECT_EQ(ARES_ENOMEM,
            ares_create_query("example.com", C_IN, T_A, 0x1234, 0,
                    &p, &len, 0));
  if (p) ares_free_string(p);

  // 63-char limit on a single label
  std::string longlabel = "a.a123456789b123456789c123456789d123456789e123456789f123456789g123456789.org";
  p = nullptr;
  EXPECT_EQ(ARES_EBADNAME,
            ares_create_query(longlabel.c_str(), C_IN, T_A, 0x1234, 0,
                    &p, &len, 0));
  if (p) ares_free_string(p);

  // Empty non-terminal label
  p = nullptr;
  EXPECT_EQ(ARES_EBADNAME,
            ares_create_query("example..com", C_IN, T_A, 0x1234, 0,
                    &p, &len, 0));
  if (p) ares_free_string(p);

  EXPECT_EQ(ARES_EFORMERR,
            ares_create_query(NULL, C_IN, T_A, 0x1234, 0, NULL, NULL, 0));
}

TEST_F(LibraryTest, CreateQueryOnionDomain) {
  byte* p;
  int len;
  EXPECT_EQ(ARES_ENOTFOUND,
            ares_create_query("dontleak.onion", C_IN, T_A, 0x1234, 0,
                              &p, &len, 0));
}

TEST_F(DefaultChannelTest, HostByNameOnionDomain) {
  HostResult result;
  ares_gethostbyname(channel_, "dontleak.onion", AF_INET, HostCallback, &result);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOTFOUND, result.status_);
}

TEST_F(DefaultChannelTest, HostByNameFileOnionDomain) {
  struct hostent *h;
  EXPECT_EQ(ARES_ENOTFOUND,
            ares_gethostbyname_file(channel_, "dontleak.onion", AF_INET, &h));
}

TEST_F(DefaultChannelTest, GetAddrinfoOnionDomain) {
  AddrInfoResult result;
  struct ares_addrinfo_hints hints = {};
  hints.ai_family = AF_UNSPEC;
  ares_getaddrinfo(channel_, "dontleak.onion", NULL, &hints, AddrInfoCallback, &result);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOTFOUND, result.status_);
}

// Interesting question: should tacking on a search domain let the query
// through? It seems safer to reject it because "supersecret.onion.search"
// still leaks information about the query to malicious resolvers.
TEST_F(DefaultChannelTest, SearchOnionDomain) {
  SearchResult result;
  ares_search(channel_, "dontleak.onion", C_IN, T_A,
              SearchCallback, &result);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOTFOUND, result.status_);
}

TEST_F(DefaultChannelTest, SendFailure) {
  unsigned char buf[2] = {};
  SearchResult result;
  ares_send(channel_, buf, sizeof(buf), SearchCallback, &result);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_EBADQUERY, result.status_);
}

static std::string ExpandName(const std::vector<byte>& data, int offset,
                              long *enclen) {
  char *name = nullptr;
  int rc = ares_expand_name(data.data() + offset, data.data(), (int)data.size(),
                            &name, enclen);
  EXPECT_EQ(ARES_SUCCESS, rc);
  std::string result;
  if (rc == ARES_SUCCESS) {
    result = name;
  } else {
    result = "<error>";
  }
  ares_free_string(name);
  return result;
}

TEST_F(LibraryTest, ExpandName) {
  long enclen;
  std::vector<byte> data1 = {1, 'a', 2, 'b', 'c', 3, 'd', 'e', 'f', 0};
  EXPECT_EQ("a.bc.def", ExpandName(data1, 0, &enclen));
  EXPECT_EQ(data1.size(), (size_t)enclen);

  std::vector<byte> data2 = {0};
  EXPECT_EQ("", ExpandName(data2, 0, &enclen));
  EXPECT_EQ(1, enclen);

  // Complete name indirection
  std::vector<byte> data3 = {0x12, 0x23,
                             3, 'd', 'e', 'f', 0,
                             0xC0, 2};
  EXPECT_EQ("def", ExpandName(data3, 2, &enclen));
  EXPECT_EQ(5, enclen);
  EXPECT_EQ("def", ExpandName(data3, 7, &enclen));
  EXPECT_EQ(2, enclen);

  // One label then indirection
  std::vector<byte> data4 = {0x12, 0x23,
                             3, 'd', 'e', 'f', 0,
                             1, 'a', 0xC0, 2};
  EXPECT_EQ("def", ExpandName(data4, 2, &enclen));
  EXPECT_EQ(5, enclen);
  EXPECT_EQ("a.def", ExpandName(data4, 7, &enclen));
  EXPECT_EQ(4, enclen);

  // Two labels then indirection
  std::vector<byte> data5 = {0x12, 0x23,
                             3, 'd', 'e', 'f', 0,
                             1, 'a', 1, 'b', 0xC0, 2};
  EXPECT_EQ("def", ExpandName(data5, 2, &enclen));
  EXPECT_EQ(5, enclen);
  EXPECT_EQ("a.b.def", ExpandName(data5, 7, &enclen));
  EXPECT_EQ(6, enclen);

  // Empty name, indirection to empty name
  std::vector<byte> data6 = {0x12, 0x23,
                             0,
                             0xC0, 2};
  EXPECT_EQ("", ExpandName(data6, 2, &enclen));
  EXPECT_EQ(1, enclen);
  EXPECT_EQ("", ExpandName(data6, 3, &enclen));
  EXPECT_EQ(2, enclen);
}

TEST_F(LibraryTest, ExpandNameFailure) {
  std::vector<byte> data1 = {0x03, 'c', 'o', 'm', 0x00};
  char *name = nullptr;
  long enclen;
  SetAllocFail(1);
  EXPECT_EQ(ARES_ENOMEM,
            ares_expand_name(data1.data(), data1.data(), (int)data1.size(),
                             &name, &enclen));

  // Empty packet
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data1.data(), data1.data(), 0, &name, &enclen));

  // Start beyond enclosing data
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data1.data() + data1.size(), data1.data(), (int)data1.size(),
                             &name, &enclen));

  // Length beyond size of enclosing data
  std::vector<byte> data2a = {0x13, 'c', 'o', 'm', 0x00};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data2a.data(), data2a.data(), (int)data2a.size(),
                             &name, &enclen));
  std::vector<byte> data2b = {0x1};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data2b.data(), data2b.data(), (int)data2b.size(),
                             &name, &enclen));
  std::vector<byte> data2c = {0xC0};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data2c.data(), data2c.data(), (int)data2c.size(),
                             &name, &enclen));

  // Indirection beyond enclosing data
  std::vector<byte> data3a = {0xC0, 0x02};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data3a.data(), data3a.data(), (int)data3a.size(),
                             &name, &enclen));
  std::vector<byte> data3b = {0xC0, 0x0A, 'c', 'o', 'm', 0x00};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data3b.data(), data3b.data(), (int)data3b.size(),
                             &name, &enclen));

  // Invalid top bits in label length
  std::vector<byte> data4 = {0x03, 'c', 'o', 'm', 0x00, 0x80, 0x00};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data4.data() + 5, data4.data(), (int)data4.size(),
                             &name, &enclen));

  // Label too long: 64-byte label, with invalid top 2 bits of length (01).
  std::vector<byte> data5 = {0x40,
                             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
                             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
                             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
                             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
                             0x00};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data5.data(), data5.data(), (int)data5.size(),
                             &name, &enclen)) << name;

  // Incomplete indirect length
  std::vector<byte> data6 = {0x03, 'c', 'o', 'm', 0x00, 0xC0};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data6.data() + 5, data6.data(), (int)data6.size(),
                             &name, &enclen));

  // Indirection loops
  std::vector<byte> data7 = {0xC0, 0x02, 0xC0, 0x00};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data7.data(), data7.data(), (int)data7.size(),
                             &name, &enclen));
  std::vector<byte> data8 = {3, 'd', 'e', 'f', 0xC0, 0x08, 0x00, 0x00,
                             3, 'a', 'b', 'c', 0xC0, 0x00};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data8.data(), data8.data(), (int)data8.size(),
                             &name, &enclen));
  std::vector<byte> data9 = {0x12, 0x23,  // start 2 bytes in
                             3, 'd', 'e', 'f', 0xC0, 0x02};
  EXPECT_EQ(ARES_EBADNAME,
            ares_expand_name(data9.data() + 2, data9.data(), (int)data9.size(),
                             &name, &enclen));
}

TEST_F(LibraryTest, CreateEDNSQuery) {
  byte* p;
  int len;
  EXPECT_EQ(ARES_SUCCESS,
            ares_create_query("example.com", C_IN, T_A, 0x1234, 0,
                              &p, &len, 1280));
  std::vector<byte> data(p, p + len);
  ares_free_string(p);

  std::string actual = PacketToString(data);
  DNSPacket pkt;
  pkt.set_qid(0x1234).add_question(new DNSQuestion("example.com", T_A))
    .add_additional(new DNSOptRR(0, 0, 0, 1280, { }, { } /* No server cookie */));
  std::string expected = PacketToString(pkt.data());
  EXPECT_EQ(expected, actual);
}

TEST_F(LibraryTest, CreateRootQuery) {
  byte* p;
  int len;
  ares_create_query(".", C_IN, T_A, 0x1234, 0, &p, &len, 0);
  std::vector<byte> data(p, p + len);
  ares_free_string(p);

  std::string actual = PacketToString(data);
  DNSPacket pkt;
  pkt.set_qid(0x1234).add_question(new DNSQuestion("", T_A));
  std::string expected = PacketToString(pkt.data());
  EXPECT_EQ(expected, actual);
}

TEST_F(LibraryTest, Version) {
  // Assume linked to same version
  EXPECT_EQ(std::string(ARES_VERSION_STR),
            std::string(ares_version(nullptr)));
  int version;
  ares_version(&version);
  EXPECT_EQ(ARES_VERSION, version);
}

TEST_F(LibraryTest, ExpandString) {
  std::vector<byte> s1 = { 3, 'a', 'b', 'c'};
  char* result = nullptr;
  long len;
  EXPECT_EQ(ARES_SUCCESS,
            ares_expand_string(s1.data(), s1.data(), (int)s1.size(),
                               (unsigned char**)&result, &len));
  EXPECT_EQ("abc", std::string(result));
  EXPECT_EQ(1 + 3, len);  // amount of data consumed includes 1 byte len
  ares_free_string(result);
  result = nullptr;
  EXPECT_EQ(ARES_EBADSTR,
            ares_expand_string(s1.data() + 1, s1.data(), (int)s1.size(),
                               (unsigned char**)&result, &len));
  EXPECT_EQ(ARES_EBADSTR,
            ares_expand_string(s1.data() + 4, s1.data(), (int)s1.size(),
                               (unsigned char**)&result, &len));
  SetAllocFail(1);
  EXPECT_EQ(ARES_ENOMEM,
            ares_expand_string(s1.data(), s1.data(), (int)s1.size(),
                               (unsigned char**)&result, &len));
}

TEST_F(LibraryTest, DNSMapping) {
  ares_dns_rec_type_t types[] = {
    ARES_REC_TYPE_A,
    ARES_REC_TYPE_NS,
    ARES_REC_TYPE_CNAME,
    ARES_REC_TYPE_SOA,
    ARES_REC_TYPE_PTR,
    ARES_REC_TYPE_HINFO,
    ARES_REC_TYPE_MX,
    ARES_REC_TYPE_TXT,
    ARES_REC_TYPE_SIG,
    ARES_REC_TYPE_AAAA,
    ARES_REC_TYPE_SRV,
    ARES_REC_TYPE_NAPTR,
    ARES_REC_TYPE_OPT,
    ARES_REC_TYPE_TLSA,
    ARES_REC_TYPE_SVCB,
    ARES_REC_TYPE_HTTPS,
    ARES_REC_TYPE_ANY,
    ARES_REC_TYPE_URI,
    ARES_REC_TYPE_CAA
  };

  for (size_t i=0; i<sizeof(types) / sizeof(*types); i++) {
    ares_dns_rec_type_t type;
    EXPECT_TRUE(ares_dns_rec_type_fromstr(&type, ares_dns_rec_type_tostr(types[i])));
    EXPECT_EQ(types[i], type);
    size_t cnt;
    const ares_dns_rr_key_t *keys = ares_dns_rr_get_keys(type, &cnt);
    for (size_t j=0; j<cnt; j++) {
      const char *name = ares_dns_rr_key_tostr(keys[j]);
      EXPECT_NE(nullptr, name);
      EXPECT_NE("UNKNOWN", std::string(name));
      EXPECT_EQ(type, ares_dns_rr_key_to_rec_type(keys[j]));
      EXPECT_NE(0, (int)ares_dns_rr_key_datatype(keys[j]));
    }
  }
}

TEST_F(LibraryTest, StrError) {
  ares_status_t status[] = {
    ARES_SUCCESS, ARES_ENODATA, ARES_EFORMERR, ARES_ESERVFAIL, ARES_ENOTFOUND,
    ARES_ENOTIMP, ARES_EREFUSED, ARES_EBADQUERY, ARES_EBADNAME, ARES_EBADFAMILY,
    ARES_EBADRESP, ARES_ECONNREFUSED, ARES_ETIMEOUT, ARES_EOF, ARES_EFILE,
    ARES_ENOMEM, ARES_EDESTRUCTION, ARES_EBADSTR, ARES_EBADFLAGS, ARES_ENONAME,
    ARES_EBADHINTS, ARES_ENOTINITIALIZED, ARES_ELOADIPHLPAPI,
    ARES_EADDRGETNETWORKPARAMS, ARES_ECANCELLED, ARES_ESERVICE, ARES_ENOSERVER
  };
  size_t i;
  const char *str = nullptr;

  for (i=0; i < sizeof(status) / sizeof(*status); i++) {
    str = ares_strerror((int)status[i]);
    EXPECT_NE(nullptr, str);
    EXPECT_NE("unknown", std::string(str));
  }

  /* unknown value */
  str = ares_strerror(0x12345678);
  EXPECT_NE(nullptr, str);
  EXPECT_EQ("unknown", std::string(str));
}

TEST_F(LibraryTest, UsageErrors) {
  ares_cancel(NULL);
  ares_set_socket_callback(NULL, NULL, NULL);
  ares_set_socket_configure_callback(NULL, NULL, NULL);
  ares_set_socket_functions(NULL, NULL, NULL);
  ares_destroy(NULL);
  ares_expand_name(NULL, NULL, 0, NULL, NULL);
  ares_expand_string(NULL, NULL, 0, NULL, NULL);
  ares_fds(NULL, NULL, NULL);
  ares_getaddrinfo(NULL, NULL, NULL, NULL, NULL, NULL);
  ares_gethostbyaddr(NULL, NULL, 0, 0, NULL, NULL);
  ares_getnameinfo(NULL, NULL, 0, 0, NULL, NULL);
  ares_reinit(NULL);
  ares_dup(NULL, NULL);
  ares_set_local_ip4(NULL, 0);
  ares_set_local_ip6(NULL, NULL);
  ares_set_local_dev(NULL, NULL);
  ares_query_dnsrec(NULL, NULL, ARES_CLASS_IN, ARES_REC_TYPE_A, NULL, NULL, NULL);
  ares_query(NULL, NULL, ARES_CLASS_IN, ARES_REC_TYPE_A, NULL, NULL);
}


}  // namespace test
}  // namespace ares