/* Copyright (c) 2014, Google Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#if !defined(__STDC_FORMAT_MACROS)
#define __STDC_FORMAT_MACROS
#endif

#include <openssl/base.h>

#if !defined(OPENSSL_WINDOWS)
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <unistd.h>
#else
#include <io.h>
OPENSSL_MSVC_PRAGMA(warning(push, 3))
#include <winsock2.h>
#include <ws2tcpip.h>
OPENSSL_MSVC_PRAGMA(warning(pop))

OPENSSL_MSVC_PRAGMA(comment(lib, "Ws2_32.lib"))
#endif

#include <assert.h>
#include <inttypes.h>
#include <string.h>
#include <time.h>

#include <openssl/aead.h>
#include <openssl/bio.h>
#include <openssl/buf.h>
#include <openssl/bytestring.h>
#include <openssl/cipher.h>
#include <openssl/crypto.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/nid.h>
#include <openssl/rand.h>
#include <openssl/ssl.h>
#include <openssl/x509.h>

#include <functional>
#include <memory>
#include <string>
#include <vector>

#include "../../crypto/internal.h"
#include "../internal.h"
#include "async_bio.h"
#include "handshake_util.h"
#include "packeted_bio.h"
#include "settings_writer.h"
#include "test_config.h"
#include "test_state.h"


#if !defined(OPENSSL_WINDOWS)
static int closesocket(int sock) {
  return close(sock);
}

static void PrintSocketError(const char *func) {
  perror(func);
}
#else
static void PrintSocketError(const char *func) {
  fprintf(stderr, "%s: %d\n", func, WSAGetLastError());
}
#endif

static int Usage(const char *program) {
  fprintf(stderr, "Usage: %s [flags...]\n", program);
  return 1;
}

template<typename T>
struct Free {
  void operator()(T *buf) {
    free(buf);
  }
};

// Connect returns a new socket connected to localhost on |port| or -1 on
// error.
static int Connect(uint16_t port) {
  for (int af : { AF_INET6, AF_INET }) {
    int sock = socket(af, SOCK_STREAM, 0);
    if (sock == -1) {
      PrintSocketError("socket");
      return -1;
    }
    int nodelay = 1;
    if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
            reinterpret_cast<const char*>(&nodelay), sizeof(nodelay)) != 0) {
      PrintSocketError("setsockopt");
      closesocket(sock);
      return -1;
    }

    sockaddr_storage ss;
    OPENSSL_memset(&ss, 0, sizeof(ss));
    ss.ss_family = af;
    socklen_t len = 0;

    if (af == AF_INET6) {
      sockaddr_in6 *sin6 = (sockaddr_in6 *) &ss;
      len = sizeof(*sin6);
      sin6->sin6_port = htons(port);
      if (!inet_pton(AF_INET6, "::1", &sin6->sin6_addr)) {
        PrintSocketError("inet_pton");
        closesocket(sock);
        return -1;
      }
    } else if (af == AF_INET) {
      sockaddr_in *sin = (sockaddr_in *) &ss;
      len = sizeof(*sin);
      sin->sin_port = htons(port);
      if (!inet_pton(AF_INET, "127.0.0.1", &sin->sin_addr)) {
        PrintSocketError("inet_pton");
        closesocket(sock);
        return -1;
      }
    }

    if (connect(sock, reinterpret_cast<const sockaddr*>(&ss), len) == 0) {
      return sock;
    }
    closesocket(sock);
  }

  PrintSocketError("connect");
  return -1;
}

class SocketCloser {
 public:
  explicit SocketCloser(int sock) : sock_(sock) {}
  ~SocketCloser() {
    // Half-close and drain the socket before releasing it. This seems to be
    // necessary for graceful shutdown on Windows. It will also avoid write
    // failures in the test runner.
#if defined(OPENSSL_WINDOWS)
    shutdown(sock_, SD_SEND);
#else
    shutdown(sock_, SHUT_WR);
#endif
    while (true) {
      char buf[1024];
      if (recv(sock_, buf, sizeof(buf), 0) <= 0) {
        break;
      }
    }
    closesocket(sock_);
  }

 private:
  const int sock_;
};

// DoRead reads from |ssl|, resolving any asynchronous operations. It returns
// the result value of the final |SSL_read| call.
static int DoRead(SSL *ssl, uint8_t *out, size_t max_out) {
  const TestConfig *config = GetTestConfig(ssl);
  TestState *test_state = GetTestState(ssl);
  int ret;
  do {
    if (config->async) {
      // The DTLS retransmit logic silently ignores write failures. So the test
      // may progress, allow writes through synchronously. |SSL_read| may
      // trigger a retransmit, so disconnect the write quota.
      AsyncBioEnforceWriteQuota(test_state->async_bio, false);
    }
    ret = CheckIdempotentError("SSL_peek/SSL_read", ssl, [&]() -> int {
      return config->peek_then_read ? SSL_peek(ssl, out, max_out)
                                    : SSL_read(ssl, out, max_out);
    });
    if (config->async) {
      AsyncBioEnforceWriteQuota(test_state->async_bio, true);
    }

    // Run the exporter after each read. This is to test that the exporter fails
    // during a renegotiation.
    if (config->use_exporter_between_reads) {
      uint8_t buf;
      if (!SSL_export_keying_material(ssl, &buf, 1, NULL, 0, NULL, 0, 0)) {
        fprintf(stderr, "failed to export keying material\n");
        return -1;
      }
    }
  } while (config->async && RetryAsync(ssl, ret));

  if (config->peek_then_read && ret > 0) {
    std::unique_ptr<uint8_t[]> buf(new uint8_t[static_cast<size_t>(ret)]);

    // SSL_peek should synchronously return the same data.
    int ret2 = SSL_peek(ssl, buf.get(), ret);
    if (ret2 != ret ||
        OPENSSL_memcmp(buf.get(), out, ret) != 0) {
      fprintf(stderr, "First and second SSL_peek did not match.\n");
      return -1;
    }

    // SSL_read should synchronously return the same data and consume it.
    ret2 = SSL_read(ssl, buf.get(), ret);
    if (ret2 != ret ||
        OPENSSL_memcmp(buf.get(), out, ret) != 0) {
      fprintf(stderr, "SSL_peek and SSL_read did not match.\n");
      return -1;
    }
  }

  return ret;
}

// WriteAll writes |in_len| bytes from |in| to |ssl|, resolving any asynchronous
// operations. It returns the result of the final |SSL_write| call.
static int WriteAll(SSL *ssl, const void *in_, size_t in_len) {
  const uint8_t *in = reinterpret_cast<const uint8_t *>(in_);
  const TestConfig *config = GetTestConfig(ssl);
  int ret;
  do {
    ret = SSL_write(ssl, in, in_len);
    if (ret > 0) {
      in += ret;
      in_len -= ret;
    }
  } while ((config->async && RetryAsync(ssl, ret)) || (ret > 0 && in_len > 0));
  return ret;
}

// DoShutdown calls |SSL_shutdown|, resolving any asynchronous operations. It
// returns the result of the final |SSL_shutdown| call.
static int DoShutdown(SSL *ssl) {
  const TestConfig *config = GetTestConfig(ssl);
  int ret;
  do {
    ret = SSL_shutdown(ssl);
  } while (config->async && RetryAsync(ssl, ret));
  return ret;
}

// DoSendFatalAlert calls |SSL_send_fatal_alert|, resolving any asynchronous
// operations. It returns the result of the final |SSL_send_fatal_alert| call.
static int DoSendFatalAlert(SSL *ssl, uint8_t alert) {
  const TestConfig *config = GetTestConfig(ssl);
  int ret;
  do {
    ret = SSL_send_fatal_alert(ssl, alert);
  } while (config->async && RetryAsync(ssl, ret));
  return ret;
}

static uint16_t GetProtocolVersion(const SSL *ssl) {
  uint16_t version = SSL_version(ssl);
  if (!SSL_is_dtls(ssl)) {
    return version;
  }
  return 0x0201 + ~version;
}

// CheckAuthProperties checks, after the initial handshake is completed or
// after a renegotiation, that authentication-related properties match |config|.
static bool CheckAuthProperties(SSL *ssl, bool is_resume,
                                const TestConfig *config) {
  if (!config->expected_ocsp_response.empty()) {
    const uint8_t *data;
    size_t len;
    SSL_get0_ocsp_response(ssl, &data, &len);
    if (config->expected_ocsp_response.size() != len ||
        OPENSSL_memcmp(config->expected_ocsp_response.data(), data, len) != 0) {
      fprintf(stderr, "OCSP response mismatch\n");
      return false;
    }
  }

  if (!config->expected_signed_cert_timestamps.empty()) {
    const uint8_t *data;
    size_t len;
    SSL_get0_signed_cert_timestamp_list(ssl, &data, &len);
    if (config->expected_signed_cert_timestamps.size() != len ||
        OPENSSL_memcmp(config->expected_signed_cert_timestamps.data(), data,
                       len) != 0) {
      fprintf(stderr, "SCT list mismatch\n");
      return false;
    }
  }

  if (config->expect_verify_result) {
    int expected_verify_result = config->verify_fail ?
      X509_V_ERR_APPLICATION_VERIFICATION :
      X509_V_OK;

    if (SSL_get_verify_result(ssl) != expected_verify_result) {
      fprintf(stderr, "Wrong certificate verification result\n");
      return false;
    }
  }

  if (!config->expect_peer_cert_file.empty()) {
    bssl::UniquePtr<X509> expect_leaf;
    bssl::UniquePtr<STACK_OF(X509)> expect_chain;
    if (!LoadCertificate(&expect_leaf, &expect_chain,
                         config->expect_peer_cert_file)) {
      return false;
    }

    // For historical reasons, clients report a chain with a leaf and servers
    // without.
    if (!config->is_server) {
      if (!sk_X509_insert(expect_chain.get(), expect_leaf.get(), 0)) {
        return false;
      }
      X509_up_ref(expect_leaf.get());  // sk_X509_insert takes ownership.
    }

    bssl::UniquePtr<X509> leaf(SSL_get_peer_certificate(ssl));
    STACK_OF(X509) *chain = SSL_get_peer_cert_chain(ssl);
    if (X509_cmp(leaf.get(), expect_leaf.get()) != 0) {
      fprintf(stderr, "Received a different leaf certificate than expected.\n");
      return false;
    }

    if (sk_X509_num(chain) != sk_X509_num(expect_chain.get())) {
      fprintf(stderr, "Received a chain of length %zu instead of %zu.\n",
              sk_X509_num(chain), sk_X509_num(expect_chain.get()));
      return false;
    }

    for (size_t i = 0; i < sk_X509_num(chain); i++) {
      if (X509_cmp(sk_X509_value(chain, i),
                   sk_X509_value(expect_chain.get(), i)) != 0) {
        fprintf(stderr, "Chain certificate %zu did not match.\n",
                i + 1);
        return false;
      }
    }
  }

  if (!!SSL_SESSION_has_peer_sha256(SSL_get_session(ssl)) !=
      config->expect_sha256_client_cert) {
    fprintf(stderr,
            "Unexpected SHA-256 client cert state: expected:%d is_resume:%d.\n",
            config->expect_sha256_client_cert, is_resume);
    return false;
  }

  if (config->expect_sha256_client_cert &&
      SSL_SESSION_get0_peer_certificates(SSL_get_session(ssl)) != nullptr) {
    fprintf(stderr, "Have both client cert and SHA-256 hash: is_resume:%d.\n",
            is_resume);
    return false;
  }

  const uint8_t *peer_sha256;
  size_t peer_sha256_len;
  SSL_SESSION_get0_peer_sha256(SSL_get_session(ssl), &peer_sha256,
                               &peer_sha256_len);
  if (SSL_SESSION_has_peer_sha256(SSL_get_session(ssl))) {
    if (peer_sha256_len != 32) {
      fprintf(stderr, "Peer SHA-256 hash had length %zu instead of 32\n",
              peer_sha256_len);
      return false;
    }
  } else {
    if (peer_sha256_len != 0) {
      fprintf(stderr, "Unexpected peer SHA-256 hash of length %zu\n",
              peer_sha256_len);
      return false;
    }
  }

  return true;
}

// CheckHandshakeProperties checks, immediately after |ssl| completes its
// initial handshake (or False Starts), whether all the properties are
// consistent with the test configuration and invariants.
static bool CheckHandshakeProperties(SSL *ssl, bool is_resume,
                                     const TestConfig *config) {
  if (!CheckAuthProperties(ssl, is_resume, config)) {
    return false;
  }

  if (SSL_get_current_cipher(ssl) == nullptr) {
    fprintf(stderr, "null cipher after handshake\n");
    return false;
  }

  if (config->expect_version != 0 &&
      SSL_version(ssl) != config->expect_version) {
    fprintf(stderr, "want version %04x, got %04x\n", config->expect_version,
            SSL_version(ssl));
    return false;
  }

  bool expect_resume =
      is_resume && (!config->expect_session_miss || SSL_in_early_data(ssl));
  if (!!SSL_session_reused(ssl) != expect_resume) {
    fprintf(stderr, "session unexpectedly was%s reused\n",
            SSL_session_reused(ssl) ? "" : " not");
    return false;
  }

  bool expect_handshake_done =
      (is_resume || !config->false_start) && !SSL_in_early_data(ssl);
  if (expect_handshake_done != GetTestState(ssl)->handshake_done) {
    fprintf(stderr, "handshake was%s completed\n",
            GetTestState(ssl)->handshake_done ? "" : " not");
    return false;
  }

  if (expect_handshake_done && !config->is_server) {
    bool expect_new_session =
        !config->expect_no_session &&
        (!SSL_session_reused(ssl) || config->expect_ticket_renewal) &&
        // Session tickets are sent post-handshake in TLS 1.3.
        GetProtocolVersion(ssl) < TLS1_3_VERSION;
    if (expect_new_session != GetTestState(ssl)->got_new_session) {
      fprintf(stderr,
              "new session was%s cached, but we expected the opposite\n",
              GetTestState(ssl)->got_new_session ? "" : " not");
      return false;
    }
  }

  if (!is_resume) {
    if (config->expect_session_id && !GetTestState(ssl)->got_new_session) {
      fprintf(stderr, "session was not cached on the server.\n");
      return false;
    }
    if (config->expect_no_session_id && GetTestState(ssl)->got_new_session) {
      fprintf(stderr, "session was unexpectedly cached on the server.\n");
      return false;
    }
  }

  // early_callback_called is updated in the handshaker, so we don't see it
  // here.
  if (!config->handoff && config->is_server &&
      !GetTestState(ssl)->early_callback_called) {
    fprintf(stderr, "early callback not called\n");
    return false;
  }

  if (!config->expected_server_name.empty()) {
    const char *server_name =
        SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
    if (server_name == nullptr ||
        server_name != config->expected_server_name) {
      fprintf(stderr, "servername mismatch (got %s; want %s)\n",
              server_name, config->expected_server_name.c_str());
      return false;
    }
  }

  if (!config->expected_next_proto.empty()) {
    const uint8_t *next_proto;
    unsigned next_proto_len;
    SSL_get0_next_proto_negotiated(ssl, &next_proto, &next_proto_len);
    if (next_proto_len != config->expected_next_proto.size() ||
        OPENSSL_memcmp(next_proto, config->expected_next_proto.data(),
                       next_proto_len) != 0) {
      fprintf(stderr, "negotiated next proto mismatch\n");
      return false;
    }
  }

  if (!config->is_server) {
    const uint8_t *alpn_proto;
    unsigned alpn_proto_len;
    SSL_get0_alpn_selected(ssl, &alpn_proto, &alpn_proto_len);
    if (alpn_proto_len != config->expected_alpn.size() ||
        OPENSSL_memcmp(alpn_proto, config->expected_alpn.data(),
                       alpn_proto_len) != 0) {
      fprintf(stderr, "negotiated alpn proto mismatch\n");
      return false;
    }
  }

  if (!config->expected_quic_transport_params.empty()) {
    const uint8_t *peer_params;
    size_t peer_params_len;
    SSL_get_peer_quic_transport_params(ssl, &peer_params, &peer_params_len);
    if (peer_params_len != config->expected_quic_transport_params.size() ||
        OPENSSL_memcmp(peer_params,
                       config->expected_quic_transport_params.data(),
                       peer_params_len) != 0) {
      fprintf(stderr, "QUIC transport params mismatch\n");
      return false;
    }
  }

  if (!config->expected_channel_id.empty()) {
    uint8_t channel_id[64];
    if (!SSL_get_tls_channel_id(ssl, channel_id, sizeof(channel_id))) {
      fprintf(stderr, "no channel id negotiated\n");
      return false;
    }
    if (config->expected_channel_id.size() != 64 ||
        OPENSSL_memcmp(config->expected_channel_id.data(), channel_id, 64) !=
            0) {
      fprintf(stderr, "channel id mismatch\n");
      return false;
    }
  }

  if (config->expected_token_binding_param != -1) {
    if (!SSL_is_token_binding_negotiated(ssl)) {
      fprintf(stderr, "no Token Binding negotiated\n");
      return false;
    }
    if (SSL_get_negotiated_token_binding_param(ssl) !=
        static_cast<uint8_t>(config->expected_token_binding_param)) {
      fprintf(stderr, "Token Binding param mismatch\n");
      return false;
    }
  }

  if (config->expect_extended_master_secret && !SSL_get_extms_support(ssl)) {
    fprintf(stderr, "No EMS for connection when expected\n");
    return false;
  }

  if (config->expect_secure_renegotiation &&
      !SSL_get_secure_renegotiation_support(ssl)) {
    fprintf(stderr, "No secure renegotiation for connection when expected\n");
    return false;
  }

  if (config->expect_no_secure_renegotiation &&
      SSL_get_secure_renegotiation_support(ssl)) {
    fprintf(stderr,
            "Secure renegotiation unexpectedly negotiated for connection\n");
    return false;
  }

  if (config->expect_peer_signature_algorithm != 0 &&
      config->expect_peer_signature_algorithm !=
          SSL_get_peer_signature_algorithm(ssl)) {
    fprintf(stderr, "Peer signature algorithm was %04x, wanted %04x.\n",
            SSL_get_peer_signature_algorithm(ssl),
            config->expect_peer_signature_algorithm);
    return false;
  }

  if (config->expect_curve_id != 0) {
    uint16_t curve_id = SSL_get_curve_id(ssl);
    if (static_cast<uint16_t>(config->expect_curve_id) != curve_id) {
      fprintf(stderr, "curve_id was %04x, wanted %04x\n", curve_id,
              static_cast<uint16_t>(config->expect_curve_id));
      return false;
    }
  }

  uint16_t cipher_id =
      static_cast<uint16_t>(SSL_CIPHER_get_id(SSL_get_current_cipher(ssl)));
  if (config->expect_cipher_aes != 0 &&
      EVP_has_aes_hardware() &&
      static_cast<uint16_t>(config->expect_cipher_aes) != cipher_id) {
    fprintf(stderr, "Cipher ID was %04x, wanted %04x (has AES hardware)\n",
            cipher_id, static_cast<uint16_t>(config->expect_cipher_aes));
    return false;
  }

  if (config->expect_cipher_no_aes != 0 &&
      !EVP_has_aes_hardware() &&
      static_cast<uint16_t>(config->expect_cipher_no_aes) != cipher_id) {
    fprintf(stderr, "Cipher ID was %04x, wanted %04x (no AES hardware)\n",
            cipher_id, static_cast<uint16_t>(config->expect_cipher_no_aes));
    return false;
  }

  if (is_resume && !SSL_in_early_data(ssl)) {
    if ((config->expect_accept_early_data && !SSL_early_data_accepted(ssl)) ||
        (config->expect_reject_early_data && SSL_early_data_accepted(ssl))) {
      fprintf(stderr,
              "Early data was%s accepted, but we expected the opposite\n",
              SSL_early_data_accepted(ssl) ? "" : " not");
      return false;
    }
  }

  if (!config->psk.empty()) {
    if (SSL_get_peer_cert_chain(ssl) != nullptr) {
      fprintf(stderr, "Received peer certificate on a PSK cipher.\n");
      return false;
    }
  } else if (!config->is_server || config->require_any_client_certificate) {
    if (SSL_get_peer_cert_chain(ssl) == nullptr) {
      fprintf(stderr, "Received no peer certificate but expected one.\n");
      return false;
    }
  }

  if (is_resume && config->expect_ticket_age_skew != 0 &&
      SSL_get_ticket_age_skew(ssl) != config->expect_ticket_age_skew) {
    fprintf(stderr, "Ticket age skew was %" PRId32 ", wanted %d\n",
            SSL_get_ticket_age_skew(ssl), config->expect_ticket_age_skew);
    return false;
  }

  if (config->expect_draft_downgrade != !!SSL_is_draft_downgrade(ssl)) {
    fprintf(stderr, "Got %sdraft downgrade signal, but wanted the opposite.\n",
            SSL_is_draft_downgrade(ssl) ? "" : "no ");
    return false;
  }

  const bool did_dummy_pq_padding = !!SSL_dummy_pq_padding_used(ssl);
  if (config->expect_dummy_pq_padding != did_dummy_pq_padding) {
    fprintf(stderr,
            "Dummy PQ padding %s observed, but expected the opposite.\n",
            did_dummy_pq_padding ? "was" : "was not");
    return false;
  }

  return true;
}

static bool DoExchange(bssl::UniquePtr<SSL_SESSION> *out_session,
                       bssl::UniquePtr<SSL> *ssl_uniqueptr,
                       const TestConfig *config, bool is_resume, bool is_retry,
                       SettingsWriter *writer);

// DoConnection tests an SSL connection against the peer. On success, it returns
// true and sets |*out_session| to the negotiated SSL session. If the test is a
// resumption attempt, |is_resume| is true and |session| is the session from the
// previous exchange.
static bool DoConnection(bssl::UniquePtr<SSL_SESSION> *out_session,
                         SSL_CTX *ssl_ctx, const TestConfig *config,
                         const TestConfig *retry_config, bool is_resume,
                         SSL_SESSION *session, SettingsWriter *writer) {
  bssl::UniquePtr<SSL> ssl = config->NewSSL(
      ssl_ctx, session, is_resume, std::unique_ptr<TestState>(new TestState));
  if (!ssl) {
    return false;
  }
  if (config->is_server) {
    SSL_set_accept_state(ssl.get());
  } else {
    SSL_set_connect_state(ssl.get());
  }


  int sock = Connect(config->port);
  if (sock == -1) {
    return false;
  }
  SocketCloser closer(sock);

  bssl::UniquePtr<BIO> bio(BIO_new_socket(sock, BIO_NOCLOSE));
  if (!bio) {
    return false;
  }
  if (config->is_dtls) {
    bssl::UniquePtr<BIO> packeted = PacketedBioCreate(GetClock());
    if (!packeted) {
      return false;
    }
    GetTestState(ssl.get())->packeted_bio = packeted.get();
    BIO_push(packeted.get(), bio.release());
    bio = std::move(packeted);
  }
  if (config->async) {
    bssl::UniquePtr<BIO> async_scoped =
        config->is_dtls ? AsyncBioCreateDatagram() : AsyncBioCreate();
    if (!async_scoped) {
      return false;
    }
    BIO_push(async_scoped.get(), bio.release());
    GetTestState(ssl.get())->async_bio = async_scoped.get();
    bio = std::move(async_scoped);
  }
  SSL_set_bio(ssl.get(), bio.get(), bio.get());
  bio.release();  // SSL_set_bio takes ownership.

  bool ret = DoExchange(out_session, &ssl, config, is_resume, false, writer);
  if (!config->is_server && is_resume && config->expect_reject_early_data) {
    // We must have failed due to an early data rejection.
    if (ret) {
      fprintf(stderr, "0-RTT exchange unexpected succeeded.\n");
      return false;
    }
    if (SSL_get_error(ssl.get(), -1) != SSL_ERROR_EARLY_DATA_REJECTED) {
      fprintf(stderr,
              "SSL_get_error did not signal SSL_ERROR_EARLY_DATA_REJECTED.\n");
      return false;
    }

    // Before reseting, early state should still be available.
    if (!SSL_in_early_data(ssl.get()) ||
        !CheckHandshakeProperties(ssl.get(), is_resume, config)) {
      fprintf(stderr, "SSL_in_early_data returned false before reset.\n");
      return false;
    }

    // Reset the connection and try again at 1-RTT.
    SSL_reset_early_data_reject(ssl.get());

    // After reseting, the socket should report it is no longer in an early data
    // state.
    if (SSL_in_early_data(ssl.get())) {
      fprintf(stderr, "SSL_in_early_data returned true after reset.\n");
      return false;
    }

    if (!SetTestConfig(ssl.get(), retry_config)) {
      return false;
    }

    assert(!config->handoff);
    ret = DoExchange(out_session, &ssl, retry_config, is_resume, true, writer);
  }

  if (!ret) {
    return false;
  }

  if (!GetTestState(ssl.get())->msg_callback_ok) {
    return false;
  }

  if (!config->expect_msg_callback.empty() &&
      GetTestState(ssl.get())->msg_callback_text !=
          config->expect_msg_callback) {
    fprintf(stderr, "Bad message callback trace. Wanted:\n%s\nGot:\n%s\n",
            config->expect_msg_callback.c_str(),
            GetTestState(ssl.get())->msg_callback_text.c_str());
    return false;
  }

  return true;
}

static bool DoExchange(bssl::UniquePtr<SSL_SESSION> *out_session,
                       bssl::UniquePtr<SSL> *ssl_uniqueptr,
                       const TestConfig *config, bool is_resume, bool is_retry,
                       SettingsWriter *writer) {
  int ret;
  SSL *ssl = ssl_uniqueptr->get();
  SSL_CTX *session_ctx = SSL_get_SSL_CTX(ssl);

  if (!config->implicit_handshake) {
    if (config->handoff) {
      if (!DoSplitHandshake(ssl_uniqueptr, writer, is_resume)) {
        return false;
      }
      ssl = ssl_uniqueptr->get();
    }

    do {
      ret = CheckIdempotentError("SSL_do_handshake", ssl, [&]() -> int {
        return SSL_do_handshake(ssl);
      });
    } while (config->async && RetryAsync(ssl, ret));

    if (config->forbid_renegotiation_after_handshake) {
      SSL_set_renegotiate_mode(ssl, ssl_renegotiate_never);
    }

    if (ret != 1 || !CheckHandshakeProperties(ssl, is_resume, config)) {
      return false;
    }

    CopySessions(session_ctx, SSL_get_SSL_CTX(ssl));

    if (is_resume && !is_retry && !config->is_server &&
        config->expect_no_offer_early_data && SSL_in_early_data(ssl)) {
      fprintf(stderr, "Client unexpectedly offered early data.\n");
      return false;
    }

    if (config->handshake_twice) {
      do {
        ret = SSL_do_handshake(ssl);
      } while (config->async && RetryAsync(ssl, ret));
      if (ret != 1) {
        return false;
      }
    }

    // Skip the |config->async| logic as this should be a no-op.
    if (config->no_op_extra_handshake &&
        SSL_do_handshake(ssl) != 1) {
      fprintf(stderr, "Extra SSL_do_handshake was not a no-op.\n");
      return false;
    }

    // Reset the state to assert later that the callback isn't called in
    // renegotations.
    GetTestState(ssl)->got_new_session = false;
  }

  if (config->export_early_keying_material > 0) {
    std::vector<uint8_t> result(
        static_cast<size_t>(config->export_early_keying_material));
    if (!SSL_export_early_keying_material(
            ssl, result.data(), result.size(), config->export_label.data(),
            config->export_label.size(),
            reinterpret_cast<const uint8_t *>(config->export_context.data()),
            config->export_context.size())) {
      fprintf(stderr, "failed to export keying material\n");
      return false;
    }
    if (WriteAll(ssl, result.data(), result.size()) < 0) {
      return false;
    }
  }

  if (config->export_keying_material > 0) {
    std::vector<uint8_t> result(
        static_cast<size_t>(config->export_keying_material));
    if (!SSL_export_keying_material(
            ssl, result.data(), result.size(), config->export_label.data(),
            config->export_label.size(),
            reinterpret_cast<const uint8_t *>(config->export_context.data()),
            config->export_context.size(), config->use_export_context)) {
      fprintf(stderr, "failed to export keying material\n");
      return false;
    }
    if (WriteAll(ssl, result.data(), result.size()) < 0) {
      return false;
    }
  }

  if (config->tls_unique) {
    uint8_t tls_unique[16];
    size_t tls_unique_len;
    if (!SSL_get_tls_unique(ssl, tls_unique, &tls_unique_len,
                            sizeof(tls_unique))) {
      fprintf(stderr, "failed to get tls-unique\n");
      return false;
    }

    if (tls_unique_len != 12) {
      fprintf(stderr, "expected 12 bytes of tls-unique but got %u",
              static_cast<unsigned>(tls_unique_len));
      return false;
    }

    if (WriteAll(ssl, tls_unique, tls_unique_len) < 0) {
      return false;
    }
  }

  if (config->send_alert) {
    if (DoSendFatalAlert(ssl, SSL_AD_DECOMPRESSION_FAILURE) < 0) {
      return false;
    }
    return true;
  }

  if (config->write_different_record_sizes) {
    if (config->is_dtls) {
      fprintf(stderr, "write_different_record_sizes not supported for DTLS\n");
      return false;
    }
    // This mode writes a number of different record sizes in an attempt to
    // trip up the CBC record splitting code.
    static const size_t kBufLen = 32769;
    std::unique_ptr<uint8_t[]> buf(new uint8_t[kBufLen]);
    OPENSSL_memset(buf.get(), 0x42, kBufLen);
    static const size_t kRecordSizes[] = {
        0, 1, 255, 256, 257, 16383, 16384, 16385, 32767, 32768, 32769};
    for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kRecordSizes); i++) {
      const size_t len = kRecordSizes[i];
      if (len > kBufLen) {
        fprintf(stderr, "Bad kRecordSizes value.\n");
        return false;
      }
      if (WriteAll(ssl, buf.get(), len) < 0) {
        return false;
      }
    }
  } else {
    static const char kInitialWrite[] = "hello";
    bool pending_initial_write = false;
    if (config->read_with_unfinished_write) {
      if (!config->async) {
        fprintf(stderr, "-read-with-unfinished-write requires -async.\n");
        return false;
      }

      // Let only one byte of the record through.
      AsyncBioAllowWrite(GetTestState(ssl)->async_bio, 1);
      int write_ret =
          SSL_write(ssl, kInitialWrite, strlen(kInitialWrite));
      if (SSL_get_error(ssl, write_ret) != SSL_ERROR_WANT_WRITE) {
        fprintf(stderr, "Failed to leave unfinished write.\n");
        return false;
      }
      pending_initial_write = true;
    } else if (config->shim_writes_first) {
      if (WriteAll(ssl, kInitialWrite, strlen(kInitialWrite)) < 0) {
        return false;
      }
    }
    if (!config->shim_shuts_down) {
      for (;;) {
        // Read only 512 bytes at a time in TLS to ensure records may be
        // returned in multiple reads.
        size_t read_size = config->is_dtls ? 16384 : 512;
        if (config->read_size > 0) {
          read_size = config->read_size;
        }
        std::unique_ptr<uint8_t[]> buf(new uint8_t[read_size]);

        int n = DoRead(ssl, buf.get(), read_size);
        int err = SSL_get_error(ssl, n);
        if (err == SSL_ERROR_ZERO_RETURN ||
            (n == 0 && err == SSL_ERROR_SYSCALL)) {
          if (n != 0) {
            fprintf(stderr, "Invalid SSL_get_error output\n");
            return false;
          }
          // Stop on either clean or unclean shutdown.
          break;
        } else if (err != SSL_ERROR_NONE) {
          if (n > 0) {
            fprintf(stderr, "Invalid SSL_get_error output\n");
            return false;
          }
          return false;
        }
        // Successfully read data.
        if (n <= 0) {
          fprintf(stderr, "Invalid SSL_get_error output\n");
          return false;
        }

        if (!config->is_server && is_resume && !is_retry &&
            config->expect_reject_early_data) {
          fprintf(stderr,
                  "Unexpectedly received data instead of 0-RTT reject.\n");
          return false;
        }

        // After a successful read, with or without False Start, the handshake
        // must be complete unless we are doing early data.
        if (!GetTestState(ssl)->handshake_done &&
            !SSL_early_data_accepted(ssl)) {
          fprintf(stderr, "handshake was not completed after SSL_read\n");
          return false;
        }

        // Clear the initial write, if unfinished.
        if (pending_initial_write) {
          if (WriteAll(ssl, kInitialWrite, strlen(kInitialWrite)) < 0) {
            return false;
          }
          pending_initial_write = false;
        }

        for (int i = 0; i < n; i++) {
          buf[i] ^= 0xff;
        }
        if (WriteAll(ssl, buf.get(), n) < 0) {
          return false;
        }
      }
    }
  }

  if (!config->is_server && !config->false_start &&
      !config->implicit_handshake &&
      // Session tickets are sent post-handshake in TLS 1.3.
      GetProtocolVersion(ssl) < TLS1_3_VERSION &&
      GetTestState(ssl)->got_new_session) {
    fprintf(stderr, "new session was established after the handshake\n");
    return false;
  }

  if (GetProtocolVersion(ssl) >= TLS1_3_VERSION && !config->is_server) {
    bool expect_new_session =
        !config->expect_no_session && !config->shim_shuts_down;
    if (expect_new_session != GetTestState(ssl)->got_new_session) {
      fprintf(stderr,
              "new session was%s cached, but we expected the opposite\n",
              GetTestState(ssl)->got_new_session ? "" : " not");
      return false;
    }

    if (expect_new_session) {
      bool got_early_data =
          GetTestState(ssl)->new_session->ticket_max_early_data != 0;
      if (config->expect_ticket_supports_early_data != got_early_data) {
        fprintf(stderr,
                "new session did%s support early data, but we expected the "
                "opposite\n",
                got_early_data ? "" : " not");
        return false;
      }
    }
  }

  if (out_session) {
    *out_session = std::move(GetTestState(ssl)->new_session);
  }

  ret = DoShutdown(ssl);

  if (config->shim_shuts_down && config->check_close_notify) {
    // We initiate shutdown, so |SSL_shutdown| will return in two stages. First
    // it returns zero when our close_notify is sent, then one when the peer's
    // is received.
    if (ret != 0) {
      fprintf(stderr, "Unexpected SSL_shutdown result: %d != 0\n", ret);
      return false;
    }
    ret = DoShutdown(ssl);
  }

  if (ret != 1) {
    fprintf(stderr, "Unexpected SSL_shutdown result: %d != 1\n", ret);
    return false;
  }

  if (SSL_total_renegotiations(ssl) > 0) {
    if (!SSL_get_session(ssl)->not_resumable) {
      fprintf(stderr,
              "Renegotiations should never produce resumable sessions.\n");
      return false;
    }

    if (SSL_session_reused(ssl)) {
      fprintf(stderr, "Renegotiations should never resume sessions.\n");
      return false;
    }

    // Re-check authentication properties after a renegotiation. The reported
    // values should remain unchanged even if the server sent different SCT
    // lists.
    if (!CheckAuthProperties(ssl, is_resume, config)) {
      return false;
    }
  }

  if (SSL_total_renegotiations(ssl) != config->expect_total_renegotiations) {
    fprintf(stderr, "Expected %d renegotiations, got %d\n",
            config->expect_total_renegotiations, SSL_total_renegotiations(ssl));
    return false;
  }

  return true;
}

class StderrDelimiter {
 public:
  ~StderrDelimiter() { fprintf(stderr, "--- DONE ---\n"); }
};

int main(int argc, char **argv) {
  // To distinguish ASan's output from ours, add a trailing message to stderr.
  // Anything following this line will be considered an error.
  StderrDelimiter delimiter;

#if defined(OPENSSL_WINDOWS)
  // Initialize Winsock.
  WORD wsa_version = MAKEWORD(2, 2);
  WSADATA wsa_data;
  int wsa_err = WSAStartup(wsa_version, &wsa_data);
  if (wsa_err != 0) {
    fprintf(stderr, "WSAStartup failed: %d\n", wsa_err);
    return 1;
  }
  if (wsa_data.wVersion != wsa_version) {
    fprintf(stderr, "Didn't get expected version: %x\n", wsa_data.wVersion);
    return 1;
  }
#else
  signal(SIGPIPE, SIG_IGN);
#endif

  CRYPTO_library_init();

  TestConfig initial_config, resume_config, retry_config;
  if (!ParseConfig(argc - 1, argv + 1, &initial_config, &resume_config,
                   &retry_config)) {
    return Usage(argv[0]);
  }

  bssl::UniquePtr<SSL_CTX> ssl_ctx;

  bssl::UniquePtr<SSL_SESSION> session;
  for (int i = 0; i < initial_config.resume_count + 1; i++) {
    bool is_resume = i > 0;
    TestConfig *config = is_resume ? &resume_config : &initial_config;
    ssl_ctx = config->SetupCtx(ssl_ctx.get());
    if (!ssl_ctx) {
      ERR_print_errors_fp(stderr);
      return 1;
    }

    if (is_resume && !initial_config.is_server && !session) {
      fprintf(stderr, "No session to offer.\n");
      return 1;
    }

    bssl::UniquePtr<SSL_SESSION> offer_session = std::move(session);
    SettingsWriter writer;
    if (!writer.Init(i, config, offer_session.get())) {
      fprintf(stderr, "Error writing settings.\n");
      return 1;
    }
    bool ok = DoConnection(&session, ssl_ctx.get(), config, &retry_config,
                           is_resume, offer_session.get(), &writer);
    if (!writer.Commit()) {
      fprintf(stderr, "Error writing settings.\n");
      return 1;
    }
    if (!ok) {
      fprintf(stderr, "Connection %d failed.\n", i + 1);
      ERR_print_errors_fp(stderr);
      return 1;
    }

    if (config->resumption_delay != 0) {
      AdvanceClock(config->resumption_delay);
    }
  }

  return 0;
}