c-ares/test/ares-test-mock.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"

#ifndef WIN32
#include <sys/types.h>
#include <sys/stat.h>
#endif

#include <sstream>
#include <vector>

using testing::InvokeWithoutArgs;
using testing::DoAll;

namespace ares {
namespace test {

TEST_P(MockChannelTest, Basic) {
  std::vector<byte> reply = {
    0x00, 0x00,  // qid
    0x84, // response + query + AA + not-TC + not-RD
    0x00, // not-RA + not-Z + not-AD + not-CD + rc=NoError
    0x00, 0x01,  // 1 question
    0x00, 0x01,  // 1 answer RRs
    0x00, 0x00,  // 0 authority RRs
    0x00, 0x00,  // 0 additional RRs
    // Question
    0x03, 'w', 'w', 'w',
    0x06, 'g', 'o', 'o', 'g', 'l', 'e',
    0x03, 'c', 'o', 'm',
    0x00,
    0x00, 0x01,  // type A
    0x00, 0x01,  // class IN
    // Answer
    0x03, 'w', 'w', 'w',
    0x06, 'g', 'o', 'o', 'g', 'l', 'e',
    0x03, 'c', 'o', 'm',
    0x00,
    0x00, 0x01,  // type A
    0x00, 0x01,  // class IN
    0x00, 0x00, 0x01, 0x00,  // TTL
    0x00, 0x04,  // rdata length
    0x01, 0x02, 0x03, 0x04
  };

  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReplyData(&server_, reply));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

// UDP only so mock server doesn't get confused by concatenated requests
TEST_P(MockUDPChannelTest, GetHostByNameParallelLookups) {
  DNSPacket rsp1;
  rsp1.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp1));
  DNSPacket rsp2;
  rsp2.set_response().set_aa()
    .add_question(new DNSQuestion("www.example.com", T_A))
    .add_answer(new DNSARR("www.example.com", 100, {1, 2, 3, 4}));
  ON_CALL(server_, OnRequest("www.example.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp2));

  HostResult result1;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result1);
  HostResult result2;
  ares_gethostbyname(channel_, "www.example.com.", AF_INET, HostCallback, &result2);
  HostResult result3;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result3);
  Process();
  EXPECT_TRUE(result1.done_);
  EXPECT_TRUE(result2.done_);
  EXPECT_TRUE(result3.done_);
  std::stringstream ss1;
  ss1 << result1.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss1.str());
  std::stringstream ss2;
  ss2 << result2.host_;
  EXPECT_EQ("{'www.example.com' aliases=[] addrs=[1.2.3.4]}", ss2.str());
  std::stringstream ss3;
  ss3 << result3.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss3.str());
}

// UDP to TCP specific test
TEST_P(MockUDPChannelTest, TruncationRetry) {
  DNSPacket rsptruncated;
  rsptruncated.set_response().set_aa().set_tc()
    .add_question(new DNSQuestion("www.google.com", T_A));
  DNSPacket rspok;
  rspok.set_response()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {1, 2, 3, 4}));
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsptruncated))
    .WillOnce(SetReply(&server_, &rspok));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

static int sock_cb_count = 0;
static int SocketConnectCallback(ares_socket_t fd, int type, void *data) {
  int rc = *(int*)data;
  if (verbose) std::cerr << "SocketConnectCallback(" << fd << ") invoked" << std::endl;
  sock_cb_count++;
  return rc;
}

TEST_P(MockChannelTest, SockCallback) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsp));

  // Get notified of new sockets
  int rc = ARES_SUCCESS;
  ares_set_socket_callback(channel_, SocketConnectCallback, &rc);

  HostResult result;
  sock_cb_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_EQ(1, sock_cb_count);
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, SockFailCallback) {
  // Notification of new sockets gives an error.
  int rc = -1;
  ares_set_socket_callback(channel_, SocketConnectCallback, &rc);

  HostResult result;
  sock_cb_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_LT(1, sock_cb_count);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ECONNREFUSED, result.status_);
}

static int sock_config_cb_count = 0;
static int SocketConfigureCallback(ares_socket_t fd, int type, void *data) {
  int rc = *(int*)data;
  if (verbose) std::cerr << "SocketConfigureCallback(" << fd << ") invoked" << std::endl;
  sock_config_cb_count++;
  return rc;
}

TEST_P(MockChannelTest, SockConfigureCallback) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsp));

  // Get notified of new sockets
  int rc = ARES_SUCCESS;
  ares_set_socket_configure_callback(channel_, SocketConfigureCallback, &rc);

  HostResult result;
  sock_config_cb_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_EQ(1, sock_config_cb_count);
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, SockConfigureFailCallback) {
  // Notification of new sockets gives an error.
  int rc = -1;
  ares_set_socket_configure_callback(channel_, SocketConfigureCallback, &rc);

  HostResult result;
  sock_config_cb_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_LT(1, sock_config_cb_count);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ECONNREFUSED, result.status_);
}

// Define a server state callback for testing. The custom userdata should be
// the expected server string that the callback is invoked with.
static int server_state_cb_success_count = 0;
static int server_state_cb_failure_count = 0;
static void ServerStateCallback(const char *server_string,
                                ares_bool_t success, int flags, void *data) {
  // Increment overall success/failure counts appropriately.
  if (verbose) std::cerr << "ServerStateCallback("
                         << server_string << ", "
                         << success       << ", "
                         << flags         << ") invoked" << std::endl;
  if (success == ARES_TRUE) server_state_cb_success_count++;
  else server_state_cb_failure_count++;

  // Check that the server string is as expected.
  char *exp_server_string = *(char **)(data);
  EXPECT_STREQ(exp_server_string, server_string);

  // The callback should be invoked with either the UDP flag or the TCP flag,
  // but not both.
  ares_bool_t udp = (flags & ARES_SERV_STATE_UDP) ? ARES_TRUE: ARES_FALSE;
  ares_bool_t tcp = (flags & ARES_SERV_STATE_TCP) ? ARES_TRUE: ARES_FALSE;
  EXPECT_NE(udp, tcp);
}

TEST_P(MockChannelTest, ServStateCallbackSuccess) {
  // Set up the server response. The server returns successfully with an answer
  // to the query.
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsp));

  // Set up the server state callback. The channel used for this test has a
  // single server configured.
  char *exp_server_string = ares_get_servers_csv(channel_);
  ares_set_server_state_callback(channel_, ServerStateCallback,
                                 &exp_server_string);

  // Perform the hostname lookup. Expect 1 successful query to the server.
  HostResult result;
  server_state_cb_success_count = 0;
  server_state_cb_failure_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback,
                     &result);
  Process();
  EXPECT_EQ(1, server_state_cb_success_count);
  EXPECT_EQ(0, server_state_cb_failure_count);
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());

  ares_free_string(exp_server_string);
}

TEST_P(MockChannelTest, ServStateCallbackFailure) {
  // Set up the server response. The server always returns SERVFAIL.
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(SERVFAIL);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));

  // Set up the server state callback. The channel used for this test has a
  // single server configured.
  char *exp_server_string = ares_get_servers_csv(channel_);
  ares_set_server_state_callback(channel_, ServerStateCallback,
                                 &exp_server_string);

  // Perform the hostname lookup. Expect 3 failed queries to the server (due to
  // retries).
  HostResult result;
  server_state_cb_success_count = 0;
  server_state_cb_failure_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback,
                     &result);
  Process();
  EXPECT_EQ(0, server_state_cb_success_count);
  EXPECT_EQ(3, server_state_cb_failure_count);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ESERVFAIL, result.status_);

  ares_free_string(exp_server_string);
}

TEST_P(MockChannelTest, ServStateCallbackRecover) {
  // Set up the server response. The server initially times out, but then
  // returns successfully (with NXDOMAIN) on the first retry.
  std::vector<byte> nothing;
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(NXDOMAIN);
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReplyData(&server_, nothing))
    .WillOnce(SetReply(&server_, &rsp));

  // Set up the server state callback. The channel used for this test has a
  // single server configured.
  char *exp_server_string = ares_get_servers_csv(channel_);
  ares_set_server_state_callback(channel_, ServerStateCallback,
                                 &exp_server_string);

  // Perform the hostname lookup. Expect 1 failed query and 1 successful query
  // to the server.
  HostResult result;
  server_state_cb_success_count = 0;
  server_state_cb_failure_count = 0;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback,
                     &result);
  Process();
  EXPECT_EQ(1, server_state_cb_success_count);
  EXPECT_EQ(1, server_state_cb_failure_count);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOTFOUND, result.status_);

  ares_free_string(exp_server_string);
}

TEST_P(MockChannelTest, ReInit) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsp));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  EXPECT_EQ(ARES_SUCCESS, ares_reinit(channel_));
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

#define MAXUDPQUERIES_TOTAL 32
#define MAXUDPQUERIES_LIMIT 8

class MockUDPMaxQueriesTest
    : public MockChannelOptsTest,
      public ::testing::WithParamInterface<int> {
 public:
  MockUDPMaxQueriesTest()
    : MockChannelOptsTest(1, GetParam(), false,
                          FillOptions(&opts_),
                          ARES_OPT_UDP_MAX_QUERIES) {}
  static struct ares_options* FillOptions(struct ares_options * opts) {
    memset(opts, 0, sizeof(struct ares_options));
    opts->udp_max_queries = MAXUDPQUERIES_LIMIT;
    return opts;
  }
 private:
  struct ares_options opts_;
};

TEST_P(MockUDPMaxQueriesTest, GetHostByNameParallelLookups) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));

  // Get notified of new sockets so we can validate how many are created
  int rc = ARES_SUCCESS;
  ares_set_socket_callback(channel_, SocketConnectCallback, &rc);
  sock_cb_count = 0;

  HostResult result[MAXUDPQUERIES_TOTAL];
  for (size_t i=0; i<MAXUDPQUERIES_TOTAL; i++) {
    ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result[i]);
  }

  Process();

  EXPECT_EQ(MAXUDPQUERIES_TOTAL / MAXUDPQUERIES_LIMIT, sock_cb_count);

  for (size_t i=0; i<MAXUDPQUERIES_TOTAL; i++) {
    std::stringstream ss;
    EXPECT_TRUE(result[i].done_);
    ss << result[i].host_;
    EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
  }
}

class CacheQueriesTest
    : public MockChannelOptsTest,
      public ::testing::WithParamInterface<int> {
 public:
  CacheQueriesTest()
    : MockChannelOptsTest(1, GetParam(), false,
                          FillOptions(&opts_),
                          ARES_OPT_QUERY_CACHE) {}
  static struct ares_options* FillOptions(struct ares_options * opts) {
    memset(opts, 0, sizeof(struct ares_options));
    opts->qcache_max_ttl = 3600;
    return opts;
  }
 private:
  struct ares_options opts_;
};

TEST_P(CacheQueriesTest, GetHostByNameCache) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));

  // Get notified of new sockets so we can validate how many are created
  int rc = ARES_SUCCESS;
  ares_set_socket_callback(channel_, SocketConnectCallback, &rc);
  sock_cb_count = 0;

  HostResult result1;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result1);
  Process();

  std::stringstream ss1;
  EXPECT_TRUE(result1.done_);
  ss1 << result1.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss1.str());

  /* Run again, should return cached result */
  HostResult result2;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result2);
  Process();

  std::stringstream ss2;
  EXPECT_TRUE(result2.done_);
  ss2 << result2.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss2.str());

  EXPECT_EQ(1, sock_cb_count);
}

#define TCPPARALLELLOOKUPS 32
TEST_P(MockTCPChannelTest, GetHostByNameParallelLookups) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));

  // Get notified of new sockets so we can validate how many are created
  int rc = ARES_SUCCESS;
  ares_set_socket_callback(channel_, SocketConnectCallback, &rc);
  sock_cb_count = 0;

  HostResult result[TCPPARALLELLOOKUPS];
  for (size_t i=0; i<TCPPARALLELLOOKUPS; i++) {
    ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result[i]);
  }

  Process();

  EXPECT_EQ(1, sock_cb_count);

  for (size_t i=0; i<TCPPARALLELLOOKUPS; i++) {
    std::stringstream ss;
    EXPECT_TRUE(result[i].done_);
    ss << result[i].host_;
    EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
  }
}

TEST_P(MockTCPChannelTest, MalformedResponse) {
  std::vector<byte> one = {0x00};
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReplyData(&server_, one));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ETIMEOUT, result.status_);
}

TEST_P(MockTCPChannelTest, FormErrResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(FORMERR);
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_EFORMERR, result.status_);
}

TEST_P(MockTCPChannelTest, ServFailResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(SERVFAIL);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ESERVFAIL, result.status_);
}

TEST_P(MockTCPChannelTest, NotImplResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(NOTIMP);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOTIMP, result.status_);
}

TEST_P(MockTCPChannelTest, RefusedResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(REFUSED);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_EREFUSED, result.status_);
}

TEST_P(MockTCPChannelTest, YXDomainResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(YXDOMAIN);
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENODATA, result.status_);
}

class MockExtraOptsTest
    : public MockChannelOptsTest,
      public ::testing::WithParamInterface< std::pair<int, bool> > {
 public:
  MockExtraOptsTest()
    : MockChannelOptsTest(1, GetParam().first, GetParam().second,
                          FillOptions(&opts_),
                          ARES_OPT_SOCK_SNDBUF|ARES_OPT_SOCK_RCVBUF) {}
  static struct ares_options* FillOptions(struct ares_options * opts) {
    memset(opts, 0, sizeof(struct ares_options));
    // Set a few options that affect socket communications
    opts->socket_send_buffer_size = 514;
    opts->socket_receive_buffer_size = 514;
    return opts;
  }
 private:
  struct ares_options opts_;
};

TEST_P(MockExtraOptsTest, SimpleQuery) {
  ares_set_local_ip4(channel_, 0x7F000001);
  byte addr6[16] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01};
  ares_set_local_ip6(channel_, addr6);
  ares_set_local_dev(channel_, "dummy");

  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

class MockFlagsChannelOptsTest
    : public MockChannelOptsTest,
      public ::testing::WithParamInterface< std::pair<int, bool> > {
 public:
  MockFlagsChannelOptsTest(int flags)
    : MockChannelOptsTest(1, GetParam().first, GetParam().second,
                          FillOptions(&opts_, flags), ARES_OPT_FLAGS) {}
  static struct ares_options* FillOptions(struct ares_options * opts, int flags) {
    memset(opts, 0, sizeof(struct ares_options));
    opts->flags = flags;
    return opts;
  }
 private:
  struct ares_options opts_;
};

class MockNoCheckRespChannelTest : public MockFlagsChannelOptsTest {
 public:
  MockNoCheckRespChannelTest() : MockFlagsChannelOptsTest(ARES_FLAG_NOCHECKRESP) {}
};

TEST_P(MockNoCheckRespChannelTest, ServFailResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(SERVFAIL);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ESERVFAIL, result.status_);
}

TEST_P(MockNoCheckRespChannelTest, NotImplResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(NOTIMP);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOTIMP, result.status_);
}

TEST_P(MockNoCheckRespChannelTest, RefusedResponse) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A));
  rsp.set_rcode(REFUSED);
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_EREFUSED, result.status_);
}

class MockEDNSChannelTest : public MockFlagsChannelOptsTest {
 public:
  MockEDNSChannelTest() : MockFlagsChannelOptsTest(ARES_FLAG_EDNS) {}
};

TEST_P(MockEDNSChannelTest, RetryWithoutEDNS) {
  DNSPacket rspfail;
  rspfail.set_response().set_aa().set_rcode(FORMERR)
    .add_question(new DNSQuestion("www.google.com", T_A));
  DNSPacket rspok;
  rspok.set_response()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 100, {1, 2, 3, 4}));
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReply(&server_, &rspfail))
    .WillOnce(SetReply(&server_, &rspok));
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

TEST_P(MockChannelTest, SearchDomains) {
  DNSPacket nofirst;
  nofirst.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.first.com", T_A));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.second.org", T_A));
  ON_CALL(server_, OnRequest("www.second.org", T_A))
    .WillByDefault(SetReply(&server_, &nosecond));
  DNSPacket yesthird;
  yesthird.set_response().set_aa()
    .add_question(new DNSQuestion("www.third.gov", T_A))
    .add_answer(new DNSARR("www.third.gov", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillByDefault(SetReply(&server_, &yesthird));

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.third.gov' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

// Relies on retries so is UDP-only
TEST_P(MockUDPChannelTest, SearchDomainsWithResentReply) {
  DNSPacket nofirst;
  nofirst.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.first.com", T_A));
  EXPECT_CALL(server_, OnRequest("www.first.com", T_A))
    .WillOnce(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.second.org", T_A));
  EXPECT_CALL(server_, OnRequest("www.second.org", T_A))
    .WillOnce(SetReply(&server_, &nosecond));
  DNSPacket yesthird;
  yesthird.set_response().set_aa()
    .add_question(new DNSQuestion("www.third.gov", T_A))
    .add_answer(new DNSARR("www.third.gov", 0x0200, {2, 3, 4, 5}));
  // Before sending the real answer, resend an earlier reply
  EXPECT_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillOnce(DoAll(SetReply(&server_, &nofirst),
                    SetReplyQID(&server_, 123)))
    .WillOnce(DoAll(SetReply(&server_, &yesthird),
                    SetReplyQID(&server_, -1)));

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.third.gov' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, SearchDomainsBare) {
  DNSPacket nofirst;
  nofirst.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.first.com", T_A));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.second.org", T_A));
  ON_CALL(server_, OnRequest("www.second.org", T_A))
    .WillByDefault(SetReply(&server_, &nosecond));
  DNSPacket nothird;
  nothird.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.third.gov", T_A));
  ON_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillByDefault(SetReply(&server_, &nothird));
  DNSPacket yesbare;
  yesbare.set_response().set_aa()
    .add_question(new DNSQuestion("www", T_A))
    .add_answer(new DNSARR("www", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www", T_A))
    .WillByDefault(SetReply(&server_, &yesbare));

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, SearchNoDataThenSuccess) {
  // First two search domains recognize the name but have no A records.
  DNSPacket nofirst;
  nofirst.set_response().set_aa()
    .add_question(new DNSQuestion("www.first.com", T_A));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa()
    .add_question(new DNSQuestion("www.second.org", T_A));
  ON_CALL(server_, OnRequest("www.second.org", T_A))
    .WillByDefault(SetReply(&server_, &nosecond));
  DNSPacket yesthird;
  yesthird.set_response().set_aa()
    .add_question(new DNSQuestion("www.third.gov", T_A))
    .add_answer(new DNSARR("www.third.gov", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillByDefault(SetReply(&server_, &yesthird));

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.third.gov' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, SearchNoDataThenNoDataBare) {
  // First two search domains recognize the name but have no A records.
  DNSPacket nofirst;
  nofirst.set_response().set_aa()
    .add_question(new DNSQuestion("www.first.com", T_A));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa()
    .add_question(new DNSQuestion("www.second.org", T_A));
  ON_CALL(server_, OnRequest("www.second.org", T_A))
    .WillByDefault(SetReply(&server_, &nosecond));
  DNSPacket nothird;
  nothird.set_response().set_aa()
    .add_question(new DNSQuestion("www.third.gov", T_A));
  ON_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillByDefault(SetReply(&server_, &nothird));
  DNSPacket nobare;
  nobare.set_response().set_aa()
    .add_question(new DNSQuestion("www", T_A));
  ON_CALL(server_, OnRequest("www", T_A))
    .WillByDefault(SetReply(&server_, &nobare));

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENODATA, result.status_);
}

TEST_P(MockChannelTest, SearchNoDataThenFail) {
  // First two search domains recognize the name but have no A records.
  DNSPacket nofirst;
  nofirst.set_response().set_aa()
    .add_question(new DNSQuestion("www.first.com", T_A));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa()
    .add_question(new DNSQuestion("www.second.org", T_A));
  ON_CALL(server_, OnRequest("www.second.org", T_A))
    .WillByDefault(SetReply(&server_, &nosecond));
  DNSPacket nothird;
  nothird.set_response().set_aa()
    .add_question(new DNSQuestion("www.third.gov", T_A));
  ON_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillByDefault(SetReply(&server_, &nothird));
  DNSPacket nobare;
  nobare.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www", T_A));
  ON_CALL(server_, OnRequest("www", T_A))
    .WillByDefault(SetReply(&server_, &nobare));

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENODATA, result.status_);
}

TEST_P(MockChannelTest, SearchAllocFailure) {
  SearchResult result;
  SetAllocFail(1);
  ares_search(channel_, "fully.qualified.", C_IN, T_A, SearchCallback, &result);
  /* Already done */
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENOMEM, result.status_);
}

TEST_P(MockChannelTest, SearchHighNdots) {
  DNSPacket nobare;
  nobare.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("a.b.c.w.w.w", T_A));
  ON_CALL(server_, OnRequest("a.b.c.w.w.w", T_A))
    .WillByDefault(SetReply(&server_, &nobare));
  DNSPacket yesfirst;
  yesfirst.set_response().set_aa()
    .add_question(new DNSQuestion("a.b.c.w.w.w.first.com", T_A))
    .add_answer(new DNSARR("a.b.c.w.w.w.first.com", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("a.b.c.w.w.w.first.com", T_A))
    .WillByDefault(SetReply(&server_, &yesfirst));

  SearchResult result;
  ares_search(channel_, "a.b.c.w.w.w", C_IN, T_A, SearchCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_SUCCESS, result.status_);
  std::stringstream ss;
  ss << PacketToString(result.data_);
  EXPECT_EQ("RSP QRY AA NOERROR Q:{'a.b.c.w.w.w.first.com' IN A} "
            "A:{'a.b.c.w.w.w.first.com' IN A TTL=512 2.3.4.5}",
            ss.str());
}

// Test that performing an EDNS search with an OPT RR options value works. The
// options value should be included on the requests to the mock server.
TEST_P(MockEDNSChannelTest, SearchOptVal) {
  /* Define the OPT RR options code and value to use. */
  unsigned short opt_opt = 3;
  unsigned char opt_val[] = { 'c', '-', 'a', 'r', 'e', 's' };

  /* Set up the expected request and reply on the mock server for the first,
   * second and third domains. The expected requests contain the OPT RR options
   * value defined above.
   */
  std::string nofirst_req = "REQ QRY RD  Q:{'example.first.com' IN A} "
    "ADD:{'' MAXUDP=1232 OPT RCODE2=0 "
    "0003"  // opt_opt
    "0006"  // length of opt_val
    "632d61726573"  // opt_val in hex
    "}";
  DNSPacket nofirst_rep;
  nofirst_rep.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("example.first.com", T_A));
  ON_CALL(server_, OnRequest("example.first.com", T_A))
    .WillByDefault(SetReplyExpRequest(&server_, &nofirst_rep, nofirst_req));

  std::string nosecond_req = "REQ QRY RD  Q:{'example.second.org' IN A} "
    "ADD:{'' MAXUDP=1232 OPT RCODE2=0 "
    "0003"  // opt_opt
    "0006"  // length of opt_val
    "632d61726573"  // opt_val in hex
    "}";
  DNSPacket nosecond_rep;
  nosecond_rep.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("example.second.org", T_A));
  ON_CALL(server_, OnRequest("example.second.org", T_A))
    .WillByDefault(SetReplyExpRequest(&server_, &nosecond_rep, nosecond_req));

  std::string nothird_req = "REQ QRY RD  Q:{'example.third.gov' IN A} "
    "ADD:{'' MAXUDP=1232 OPT RCODE2=0 "
    "0003"  // opt_opt
    "0006"  // length of opt_val
    "632d61726573"  // opt_val in hex
    "}";
  DNSPacket nothird_rep;
  nothird_rep.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("example.third.gov", T_A));
  ON_CALL(server_, OnRequest("example.third.gov", T_A))
    .WillByDefault(SetReplyExpRequest(&server_, &nothird_rep, nothird_req));

  /* Set up the expected request and reply on the mock server for the bare
   * domain. The expected request contains the OPT RR options value defined
   * above.
   */
  std::string yesbare_req = "REQ QRY RD  Q:{'example' IN A} "
    "ADD:{'' MAXUDP=1232 OPT RCODE2=0 "
    "0003"  // opt_opt
    "0006"  // length of opt_val
    "632d61726573"  // opt_val in hex
    "}";
  DNSPacket yesbare_rep;
  yesbare_rep.set_response().set_aa()
    .add_question(new DNSQuestion("example", T_A))
    .add_answer(new DNSARR("example", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("example", T_A))
    .WillByDefault(SetReplyExpRequest(&server_, &yesbare_rep, yesbare_req));

  /* Construct the DNS record to search. */
  ares_dns_record_t *dnsrec = NULL;
  ares_dns_rr_t *rr = NULL;
  EXPECT_EQ(ARES_SUCCESS,
    ares_dns_record_create(&dnsrec, 0, ARES_FLAG_RD, ARES_OPCODE_QUERY,
      ARES_RCODE_NOERROR));
  EXPECT_EQ(ARES_SUCCESS,
    ares_dns_record_query_add(dnsrec, "example", (ares_dns_rec_type_t)T_A,
      (ares_dns_class_t)C_IN));
  EXPECT_EQ(ARES_SUCCESS,
    ares_dns_record_rr_add(&rr, dnsrec, ARES_SECTION_ADDITIONAL, "",
      ARES_REC_TYPE_OPT, ARES_CLASS_IN, 0));
  EXPECT_EQ(ARES_SUCCESS,
    ares_dns_rr_set_u16(rr, ARES_RR_OPT_UDP_SIZE, 1232));
  EXPECT_EQ(ARES_SUCCESS, ares_dns_rr_set_u8(rr, ARES_RR_OPT_VERSION, 0));
  EXPECT_EQ(ARES_SUCCESS, ares_dns_rr_set_u16(rr, ARES_RR_OPT_FLAGS, 0));
  EXPECT_EQ(ARES_SUCCESS,
    ares_dns_rr_set_opt(rr, ARES_RR_OPT_OPTIONS, opt_opt, opt_val,
      sizeof(opt_val)));

  /* Perform the search. Check that it succeeds with the expected response. */
  SearchResult result;
  ares_search_dnsrec(channel_, dnsrec, SearchCallbackDnsRec, &result);
  ares_dns_record_destroy(dnsrec);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_SUCCESS, result.status_);
  std::stringstream ss;
  ss << PacketToString(result.data_);
  EXPECT_EQ("RSP QRY AA NOERROR Q:{'example' IN A} "
            "A:{'example' IN A TTL=512 2.3.4.5}",
            ss.str());
}

TEST_P(MockChannelTest, V4WorksV6Timeout) {
  std::vector<byte> nothing;
  DNSPacket reply;
  reply.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 0x0100, {0x01, 0x02, 0x03, 0x04}));

  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &reply));

  ON_CALL(server_, OnRequest("www.google.com", T_AAAA))
    .WillByDefault(SetReplyData(&server_, nothing));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_UNSPEC, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(1, result.timeouts_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

#ifndef CARES_SYMBOL_HIDING
// Test case for Issue #662
TEST_P(MockChannelTest, PartialQueryCancel) {
  std::vector<byte> nothing;
  DNSPacket reply;
  reply.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 0x0100, {0x01, 0x02, 0x03, 0x04}));

  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &reply));

  ON_CALL(server_, OnRequest("www.google.com", T_AAAA))
    .WillByDefault(SetReplyData(&server_, nothing));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_UNSPEC, HostCallback, &result);
  // After 100ms, issues ares_cancel(), this should be enough time for the A
  // record reply, but before the timeout on the AAAA record.
  Process(100);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ECANCELLED, result.status_);
}
#endif

TEST_P(MockChannelTest, UnspecifiedFamilyV6) {
  DNSPacket rsp6;
  rsp6.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_AAAA))
    .add_answer(new DNSAaaaRR("example.com", 100,
                              {0x21, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x03}));
  ON_CALL(server_, OnRequest("example.com", T_AAAA))
    .WillByDefault(SetReply(&server_, &rsp6));

  DNSPacket rsp4;
  rsp4.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_A));
  ON_CALL(server_, OnRequest("example.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp4));

  HostResult result;
  ares_gethostbyname(channel_, "example.com.", AF_UNSPEC, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  // Default to IPv6 when both are available.
  EXPECT_EQ("{'example.com' aliases=[] addrs=[2121:0000:0000:0000:0000:0000:0000:0303]}", ss.str());
}

TEST_P(MockChannelTest, UnspecifiedFamilyV4) {
  DNSPacket rsp6;
  rsp6.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_AAAA));
  ON_CALL(server_, OnRequest("example.com", T_AAAA))
    .WillByDefault(SetReply(&server_, &rsp6));
  DNSPacket rsp4;
  rsp4.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_A))
    .add_answer(new DNSARR("example.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("example.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp4));

  HostResult result;
  ares_gethostbyname(channel_, "example.com.", AF_UNSPEC, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'example.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, UnspecifiedFamilyNoData) {
  DNSPacket rsp6;
  rsp6.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_AAAA))
    .add_answer(new DNSCnameRR("example.com", 100, "elsewhere.com"));
  ON_CALL(server_, OnRequest("example.com", T_AAAA))
    .WillByDefault(SetReply(&server_, &rsp6));
  DNSPacket rsp4;
  rsp4.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_A));
  ON_CALL(server_, OnRequest("example.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp4));

  HostResult result;
  ares_gethostbyname(channel_, "example.com.", AF_UNSPEC, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'' aliases=[] addrs=[]}", ss.str());
}

TEST_P(MockChannelTest, UnspecifiedFamilyCname6A4) {
  DNSPacket rsp6;
  rsp6.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_AAAA))
    .add_answer(new DNSCnameRR("example.com", 100, "elsewhere.com"));
  ON_CALL(server_, OnRequest("example.com", T_AAAA))
    .WillByDefault(SetReply(&server_, &rsp6));
  DNSPacket rsp4;
  rsp4.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_A))
    .add_answer(new DNSARR("example.com", 100, {1, 2, 3, 4}));
  ON_CALL(server_, OnRequest("example.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp4));

  HostResult result;
  ares_gethostbyname(channel_, "example.com.", AF_UNSPEC, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'example.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

TEST_P(MockChannelTest, ExplicitIP) {
  HostResult result;
  ares_gethostbyname(channel_, "1.2.3.4", AF_INET, HostCallback, &result);
  EXPECT_TRUE(result.done_);  // Immediate return
  EXPECT_EQ(ARES_SUCCESS, result.status_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'1.2.3.4' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

TEST_P(MockChannelTest, ExplicitIPAllocFail) {
  HostResult result;
  SetAllocSizeFail(strlen("1.2.3.4") + 1);
  ares_gethostbyname(channel_, "1.2.3.4", AF_INET, HostCallback, &result);
  EXPECT_TRUE(result.done_);  // Immediate return
  EXPECT_EQ(ARES_ENOMEM, result.status_);
}

TEST_P(MockChannelTest, SortListV4) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_A))
    .add_answer(new DNSARR("example.com", 100, {22, 23, 24, 25}))
    .add_answer(new DNSARR("example.com", 100, {12, 13, 14, 15}))
    .add_answer(new DNSARR("example.com", 100, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("example.com", T_A))
    .WillByDefault(SetReply(&server_, &rsp));

  {
    EXPECT_EQ(ARES_SUCCESS, ares_set_sortlist(channel_, "12.13.0.0/255.255.0.0 1234::5678"));
    HostResult result;
    ares_gethostbyname(channel_, "example.com.", AF_INET, HostCallback, &result);
    Process();
    EXPECT_TRUE(result.done_);
    std::stringstream ss;
    ss << result.host_;
    EXPECT_EQ("{'example.com' aliases=[] addrs=[12.13.14.15, 22.23.24.25, 2.3.4.5]}", ss.str());
  }
  {
    EXPECT_EQ(ARES_SUCCESS, ares_set_sortlist(channel_, "2.3.0.0/16 130.140.150.160/26"));
    HostResult result;
    ares_gethostbyname(channel_, "example.com.", AF_INET, HostCallback, &result);
    Process();
    EXPECT_TRUE(result.done_);
    std::stringstream ss;
    ss << result.host_;
    EXPECT_EQ("{'example.com' aliases=[] addrs=[2.3.4.5, 22.23.24.25, 12.13.14.15]}", ss.str());
  }
  struct ares_options options;
  memset(&options, 0, sizeof(options));
  int optmask = 0;
  EXPECT_EQ(ARES_SUCCESS, ares_save_options(channel_, &options, &optmask));
  EXPECT_TRUE((optmask & ARES_OPT_SORTLIST) == ARES_OPT_SORTLIST);
  ares_destroy_options(&options);
}

TEST_P(MockChannelTest, SortListV6) {
  DNSPacket rsp;
  rsp.set_response().set_aa()
    .add_question(new DNSQuestion("example.com", T_AAAA))
    .add_answer(new DNSAaaaRR("example.com", 100,
                              {0x11, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x02}))
    .add_answer(new DNSAaaaRR("example.com", 100,
                              {0x21, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x03}));
  ON_CALL(server_, OnRequest("example.com", T_AAAA))
    .WillByDefault(SetReply(&server_, &rsp));

  {
    ares_set_sortlist(channel_, "1111::/16 2.3.0.0/255.255.0.0");
    HostResult result;
    ares_gethostbyname(channel_, "example.com.", AF_INET6, HostCallback, &result);
    Process();
    EXPECT_TRUE(result.done_);
    std::stringstream ss;
    ss << result.host_;
    EXPECT_EQ("{'example.com' aliases=[] addrs=[1111:0000:0000:0000:0000:0000:0000:0202, "
              "2121:0000:0000:0000:0000:0000:0000:0303]}", ss.str());
  }
  {
    ares_set_sortlist(channel_, "2121::/8");
    HostResult result;
    ares_gethostbyname(channel_, "example.com.", AF_INET6, HostCallback, &result);
    Process();
    EXPECT_TRUE(result.done_);
    std::stringstream ss;
    ss << result.host_;
    EXPECT_EQ("{'example.com' aliases=[] addrs=[2121:0000:0000:0000:0000:0000:0000:0303, "
              "1111:0000:0000:0000:0000:0000:0000:0202]}", ss.str());
  }
}

// Relies on retries so is UDP-only
TEST_P(MockUDPChannelTest, SearchDomainsAllocFail) {
  DNSPacket nofirst;
  nofirst.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.first.com", T_A));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &nofirst));
  DNSPacket nosecond;
  nosecond.set_response().set_aa().set_rcode(NXDOMAIN)
    .add_question(new DNSQuestion("www.second.org", T_A));
  ON_CALL(server_, OnRequest("www.second.org", T_A))
    .WillByDefault(SetReply(&server_, &nosecond));
  DNSPacket yesthird;
  yesthird.set_response().set_aa()
    .add_question(new DNSQuestion("www.third.gov", T_A))
    .add_answer(new DNSARR("www.third.gov", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.third.gov", T_A))
    .WillByDefault(SetReply(&server_, &yesthird));

  // Fail a variety of different memory allocations, and confirm
  // that the operation either fails with ENOMEM or succeeds
  // with the expected result.
  const int kCount = 34;
  HostResult results[kCount];
  for (int ii = 1; ii <= kCount; ii++) {
    HostResult* result = &(results[ii - 1]);
    ClearFails();
    SetAllocFail(ii);
    ares_gethostbyname(channel_, "www", AF_INET, HostCallback, result);
    Process();
    EXPECT_TRUE(result->done_);
    if (result->status_ == ARES_SUCCESS) {
      std::stringstream ss;
      ss << result->host_;
      EXPECT_EQ("{'www.third.gov' aliases=[] addrs=[2.3.4.5]}", ss.str()) << " failed alloc #" << ii;
      if (verbose) std::cerr << "Succeeded despite failure of alloc #" << ii << std::endl;
    }
  }

  // Explicitly destroy the channel now, so that the HostResult objects
  // are still valid (in case any pending work refers to them).
  ares_destroy(channel_);
  channel_ = nullptr;
}

// Relies on retries so is UDP-only
TEST_P(MockUDPChannelTest, Resend) {
  std::vector<byte> nothing;
  DNSPacket reply;
  reply.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 0x0100, {0x01, 0x02, 0x03, 0x04}));

  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReplyData(&server_, nothing))
    .WillOnce(SetReplyData(&server_, nothing))
    .WillOnce(SetReply(&server_, &reply));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(2, result.timeouts_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

TEST_P(MockChannelTest, CancelImmediate) {
  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  ares_cancel(channel_);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ECANCELLED, result.status_);
  EXPECT_EQ(0, result.timeouts_);
}

TEST_P(MockChannelTest, CancelImmediateGetHostByAddr) {
  HostResult result;
  struct in_addr addr;
  addr.s_addr = htonl(0x08080808);

  ares_gethostbyaddr(channel_, &addr, sizeof(addr), AF_INET, HostCallback, &result);
  ares_cancel(channel_);
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ECANCELLED, result.status_);
  EXPECT_EQ(0, result.timeouts_);
}

// Relies on retries so is UDP-only
TEST_P(MockUDPChannelTest, CancelLater) {
  std::vector<byte> nothing;

  // On second request, cancel the channel.
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(SetReplyData(&server_, nothing))
    .WillOnce(CancelChannel(&server_, channel_));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ECANCELLED, result.status_);
  EXPECT_EQ(0, result.timeouts_);
}

TEST_P(MockChannelTest, DisconnectFirstAttempt) {
  DNSPacket reply;
  reply.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 0x0100, {0x01, 0x02, 0x03, 0x04}));

  // On second request, cancel the channel.
  EXPECT_CALL(server_, OnRequest("www.google.com", T_A))
    .WillOnce(Disconnect(&server_))
    .WillOnce(SetReply(&server_, &reply));

  HostResult result;
  ares_gethostbyname(channel_, "www.google.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

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

  ares_destroy(channel_);
  channel_ = nullptr;

  EXPECT_TRUE(result.done_);  // Synchronous
  EXPECT_EQ(ARES_EDESTRUCTION, result.status_);
  EXPECT_EQ(0, result.timeouts_);
}

TEST_P(MockChannelTest, GetHostByNameDestroyRelative) {
  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);

  ares_destroy(channel_);
  channel_ = nullptr;

  EXPECT_TRUE(result.done_);  // Synchronous
  EXPECT_EQ(ARES_EDESTRUCTION, result.status_);
  EXPECT_EQ(0, result.timeouts_);
}

TEST_P(MockChannelTest, GetHostByNameCNAMENoData) {
  DNSPacket response;
  response.set_response().set_aa()
    .add_question(new DNSQuestion("cname.first.com", T_A))
    .add_answer(new DNSCnameRR("cname.first.com", 100, "a.first.com"));
  ON_CALL(server_, OnRequest("cname.first.com", T_A))
    .WillByDefault(SetReply(&server_, &response));

  HostResult result;
  ares_gethostbyname(channel_, "cname.first.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_ENODATA, result.status_);
}

TEST_P(MockChannelTest, GetHostByAddrDestroy) {
  unsigned char gdns_addr4[4] = {0x08, 0x08, 0x08, 0x08};
  HostResult result;
  ares_gethostbyaddr(channel_, gdns_addr4, sizeof(gdns_addr4), AF_INET, HostCallback, &result);

  ares_destroy(channel_);
  channel_ = nullptr;

  EXPECT_TRUE(result.done_);  // Synchronous
  EXPECT_EQ(ARES_EDESTRUCTION, result.status_);
  EXPECT_EQ(0, result.timeouts_);
}

#ifndef WIN32
TEST_P(MockChannelTest, HostAlias) {
  DNSPacket reply;
  reply.set_response().set_aa()
    .add_question(new DNSQuestion("www.google.com", T_A))
    .add_answer(new DNSARR("www.google.com", 0x0100, {0x01, 0x02, 0x03, 0x04}));
  ON_CALL(server_, OnRequest("www.google.com", T_A))
    .WillByDefault(SetReply(&server_, &reply));

  TempFile aliases("\n\n# www commentedout\nwww www.google.com\n");
  EnvValue with_env("HOSTALIASES", aliases.filename());

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.google.com' aliases=[] addrs=[1.2.3.4]}", ss.str());
}

TEST_P(MockChannelTest, HostAliasMissing) {
  DNSPacket yesfirst;
  yesfirst.set_response().set_aa()
    .add_question(new DNSQuestion("www.first.com", T_A))
    .add_answer(new DNSARR("www.first.com", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &yesfirst));

  TempFile aliases("\n\n# www commentedout\nww www.google.com\n");
  EnvValue with_env("HOSTALIASES", aliases.filename());
  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.first.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, HostAliasMissingFile) {
  DNSPacket yesfirst;
  yesfirst.set_response().set_aa()
    .add_question(new DNSQuestion("www.first.com", T_A))
    .add_answer(new DNSARR("www.first.com", 0x0200, {2, 3, 4, 5}));
  ON_CALL(server_, OnRequest("www.first.com", T_A))
    .WillByDefault(SetReply(&server_, &yesfirst));

  EnvValue with_env("HOSTALIASES", "bogus.mcfile");
  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  std::stringstream ss;
  ss << result.host_;
  EXPECT_EQ("{'www.first.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
}

TEST_P(MockChannelTest, HostAliasUnreadable) {
  TempFile aliases("www www.google.com\n");
  EXPECT_EQ(chmod(aliases.filename(), 0), 0);

  /* Perform OS sanity checks.  We are observing on Debian after the chmod(fn, 0)
   * that we are still able to fopen() the file which is unexpected.  Skip the
   * test if we observe this behavior */
  struct stat st;
  EXPECT_EQ(stat(aliases.filename(), &st), 0);
  EXPECT_EQ(st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO), 0);
  FILE *fp = fopen(aliases.filename(), "r");
  if (fp != NULL) {
    if (verbose) std::cerr << "Skipping Test due to OS incompatibility (open file caching)" << std::endl;
    fclose(fp);
    return;
  }

  EnvValue with_env("HOSTALIASES", aliases.filename());

  HostResult result;
  ares_gethostbyname(channel_, "www", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(ARES_EFILE, result.status_);
  chmod(aliases.filename(), 0777);
}
#endif

class MockMultiServerChannelTest
  : public MockChannelOptsTest,
    public ::testing::WithParamInterface< std::pair<int, bool> > {
 public:
  MockMultiServerChannelTest(ares_options *opts, int optmask)
    : MockChannelOptsTest(3, GetParam().first, GetParam().second, opts, optmask) {}
  void CheckExample() {
    HostResult result;
    ares_gethostbyname(channel_, "www.example.com.", AF_INET, HostCallback, &result);
    Process();
    EXPECT_TRUE(result.done_);
    std::stringstream ss;
    ss << result.host_;
    EXPECT_EQ("{'www.example.com' aliases=[] addrs=[2.3.4.5]}", ss.str());
  }
};

class NoRotateMultiMockTest : public MockMultiServerChannelTest {
 public:
  NoRotateMultiMockTest() : MockMultiServerChannelTest(nullptr, ARES_OPT_NOROTATE) {}
};

class ServerFailoverOptsMultiMockTest : public MockMultiServerChannelTest {
 public:
  ServerFailoverOptsMultiMockTest()
    : MockMultiServerChannelTest(FillOptions(&opts_),
                                 ARES_OPT_SERVER_FAILOVER | ARES_OPT_NOROTATE) {}
  static struct ares_options* FillOptions(struct ares_options *opts) {
    memset(opts, 0, sizeof(struct ares_options));
    opts->server_failover_opts.retry_chance = 1;
    opts->server_failover_opts.retry_delay = 250;
    return opts;
  }
 private:
  struct ares_options opts_;
};

TEST_P(NoRotateMultiMockTest, ThirdServer) {
  struct ares_options opts;
  int optmask = 0;
  memset(&opts, 0, sizeof(opts));
  EXPECT_EQ(ARES_SUCCESS, ares_save_options(channel_, &opts, &optmask));
  EXPECT_EQ(ARES_OPT_NOROTATE, (optmask & ARES_OPT_NOROTATE));
  ares_destroy_options(&opts);

  DNSPacket servfailrsp;
  servfailrsp.set_response().set_aa().set_rcode(SERVFAIL)
    .add_question(new DNSQuestion("www.example.com", T_A));
  DNSPacket notimplrsp;
  notimplrsp.set_response().set_aa().set_rcode(NOTIMP)
    .add_question(new DNSQuestion("www.example.com", T_A));
  DNSPacket okrsp;
  okrsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.example.com", T_A))
    .add_answer(new DNSARR("www.example.com", 100, {2,3,4,5}));

  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &servfailrsp));
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &notimplrsp));
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &okrsp));
  CheckExample();

  // Second time around, still starts from server [2], as [0] and [1] both
  // recorded failures
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &servfailrsp));
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &notimplrsp));
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &okrsp));
  CheckExample();

  // Third time around, server order is [1] (f0), [2] (f1), [0] (f2), which
  // means [1] will get called twice in a row as after the first call
  // order will be  [1] (f1), [2] (f1), [0] (f2) since sort order is
  // (failure count, index)
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &servfailrsp))
    .WillOnce(SetReply(servers_[1].get(), &notimplrsp));
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &notimplrsp));
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &okrsp));
  CheckExample();
}

TEST_P(NoRotateMultiMockTest, ServerNoResponseFailover) {
  std::vector<byte> nothing;
  DNSPacket okrsp;
  okrsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.example.com", T_A))
    .add_answer(new DNSARR("www.example.com", 100, {2,3,4,5}));

  /* Server #1 works fine on first attempt, then acts like its offline on
   * second, then backonline on the third. */
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &okrsp))
    .WillOnce(SetReplyData(servers_[0].get(), nothing))
    .WillOnce(SetReply(servers_[0].get(), &okrsp));

  /* Server #2 always acts like its offline */
  ON_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillByDefault(SetReplyData(servers_[1].get(), nothing));

  /* Server #3 works fine on first and second request, then no reply on 3rd */
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &okrsp))
    .WillOnce(SetReply(servers_[2].get(), &okrsp))
    .WillOnce(SetReplyData(servers_[2].get(), nothing));

  HostResult result;

  /* 1. First server returns a response on the first request immediately, normal
   *    operation on channel. */
  ares_gethostbyname(channel_, "www.example.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(0, result.timeouts_);
  std::stringstream ss1;
  ss1 << result.host_;
  EXPECT_EQ("{'www.example.com' aliases=[] addrs=[2.3.4.5]}", ss1.str());

  /* 2. On the second request, simulate the first and second servers not
   *    returning a response at all, but the 3rd server works, so should have
   *    2 timeouts. */
  ares_gethostbyname(channel_, "www.example.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(2, result.timeouts_);
  std::stringstream ss2;
  ss2 << result.host_;
  EXPECT_EQ("{'www.example.com' aliases=[] addrs=[2.3.4.5]}", ss2.str());

  /* 3. On the third request, the active server should be #3, so should respond
   *    immediately with no timeouts */
  ares_gethostbyname(channel_, "www.example.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(0, result.timeouts_);
  std::stringstream ss3;
  ss3 << result.host_;
  EXPECT_EQ("{'www.example.com' aliases=[] addrs=[2.3.4.5]}", ss3.str());

  /* 4. On the fourth request, the active server should be #3, but will timeout,
   *    and the first server should then respond */
  ares_gethostbyname(channel_, "www.example.com.", AF_INET, HostCallback, &result);
  Process();
  EXPECT_TRUE(result.done_);
  EXPECT_EQ(1, result.timeouts_);
  std::stringstream ss4;
  ss4 << result.host_;
  EXPECT_EQ("{'www.example.com' aliases=[] addrs=[2.3.4.5]}", ss4.str());
}

// Test case to trigger server failover behavior. We use a retry chance of
// 100% and a retry delay of 250ms so that we can test behavior reliably.
TEST_P(ServerFailoverOptsMultiMockTest, ServerFailoverOpts) {
  DNSPacket servfailrsp;
  servfailrsp.set_response().set_aa().set_rcode(SERVFAIL)
    .add_question(new DNSQuestion("www.example.com", T_A));
  DNSPacket okrsp;
  okrsp.set_response().set_aa()
    .add_question(new DNSQuestion("www.example.com", T_A))
    .add_answer(new DNSARR("www.example.com", 100, {2,3,4,5}));

  // 1. If all servers are healthy, then the first server should be selected.
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &okrsp));
  CheckExample();

  // 2. Failed servers should be retried after the retry delay.
  //
  // Fail server #0 but leave server #1 as healthy.
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &servfailrsp));
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &okrsp));
  CheckExample();

  // Sleep for the retry delay (actually a little more than 250ms to account
  // for unreliable timing, e.g. NTP slew) and send in another query. Server #0
  // should be retried.
  std::this_thread::sleep_for(std::chrono::milliseconds(260));
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &okrsp));
  CheckExample();

  // 3. If there are multiple failed servers, then the servers should be
  //    retried in sorted order.
  //
  // Fail all servers for the first round of tries. On the second round server
  // #1 responds successfully.
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &servfailrsp))
    .WillOnce(SetReply(servers_[0].get(), &servfailrsp));
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &servfailrsp))
    .WillOnce(SetReply(servers_[1].get(), &okrsp));
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &servfailrsp));
  CheckExample();

  // At this point the sorted servers look like [1] (f0) [2] (f1) [0] (f2).
  // Sleep for the retry delay and send in another query. Server #2 should be
  // retried first, and then server #0.
  std::this_thread::sleep_for(std::chrono::milliseconds(260));
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &servfailrsp));
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &okrsp));
  CheckExample();

  // 4. If there are multiple failed servers, then servers which have not yet
  //    met the retry delay should be skipped.
  //
  // The sorted servers currently look like [0] (f0) [1] (f0) [2] (f2) and
  // server #2 has just been retried.
  // Sleep for half the retry delay and trigger a failure on server #0.
  std::this_thread::sleep_for(std::chrono::milliseconds(130));
  EXPECT_CALL(*servers_[0], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[0].get(), &servfailrsp));
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &okrsp));
  CheckExample();

  // The sorted servers now look like [1] (f0) [0] (f1) [2] (f2). Server #0
  // has just failed whilst server #2 is halfway through the retry delay.
  // Sleep for another half the retry delay and check that server #2 is retried
  // whilst server #0 is not.
  std::this_thread::sleep_for(std::chrono::milliseconds(130));
  EXPECT_CALL(*servers_[2], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[2].get(), &servfailrsp));
  EXPECT_CALL(*servers_[1], OnRequest("www.example.com", T_A))
    .WillOnce(SetReply(servers_[1].get(), &okrsp));
  CheckExample();
}

const char *af_tostr(int af)
{
  switch (af) {
    case AF_INET:
      return "ipv4";
    case AF_INET6:
      return "ipv6";
  }
  return "ipunknown";
}

const char *mode_tostr(bool mode)
{
  return mode?"ForceTCP":"DefaultUDP";
}

std::string PrintFamilyMode(const testing::TestParamInfo<std::pair<int, bool>> &info)
{
  std::string name;

  name += af_tostr(std::get<0>(info.param));
  name += "_";
  name += mode_tostr(std::get<1>(info.param));
  return name;
}

std::string PrintFamily(const testing::TestParamInfo<int> &info)
{
  std::string name;

  name += af_tostr(info.param);
  return name;
}

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockChannelTest, ::testing::ValuesIn(ares::test::families_modes), PrintFamilyMode);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockUDPChannelTest, ::testing::ValuesIn(ares::test::families), PrintFamily);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockUDPMaxQueriesTest, ::testing::ValuesIn(ares::test::families), PrintFamily);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, CacheQueriesTest, ::testing::ValuesIn(ares::test::families), PrintFamily);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockTCPChannelTest, ::testing::ValuesIn(ares::test::families), PrintFamily);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockExtraOptsTest, ::testing::ValuesIn(ares::test::families_modes), PrintFamilyMode);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockNoCheckRespChannelTest, ::testing::ValuesIn(ares::test::families_modes), PrintFamilyMode);

INSTANTIATE_TEST_SUITE_P(AddressFamilies, MockEDNSChannelTest, ::testing::ValuesIn(ares::test::families_modes), PrintFamilyMode);

INSTANTIATE_TEST_SUITE_P(TransportModes, NoRotateMultiMockTest, ::testing::ValuesIn(ares::test::families_modes), PrintFamilyMode);

INSTANTIATE_TEST_SUITE_P(TransportModes, ServerFailoverOptsMultiMockTest, ::testing::ValuesIn(ares::test::families_modes), PrintFamilyMode);

}  // namespace test
}  // namespace ares