Implement SSL server socket over OpenSSL.

net/socket/ssl_server_socket_openssl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "net/socket/ssl_server_socket_openssl.h"
+
+#include <openssl/err.h>
+#include <openssl/ssl.h>
+
+#include "base/callback_helpers.h"
 #include "base/logging.h"
-#include "net/socket/ssl_server_socket.h"
+#include "crypto/openssl_util.h"
+#include "crypto/rsa_private_key.h"
+#include "net/base/net_errors.h"
+#include "net/socket/openssl_ssl_util.h"
+#include "net/socket/ssl_error_params.h"
 
-// TODO(bulach): Provide simple stubs for EnableSSLServerSockets and
-// CreateSSLServerSocket so that when building for OpenSSL rather than NSS,
-// so that the code using SSL server sockets can be compiled and disabled
-// programatically rather than requiring to be carved out from the compile.
+#define GotoState(s) next_handshake_state_ = s
 
 namespace net {
 
 void EnableSSLServerSockets() {
-  NOTIMPLEMENTED();
+  // No-op because CreateSSLServerSocket() calls crypto::EnsureOpenSSLInit().
 }
 
 scoped_ptr<SSLServerSocket> CreateSSLServerSocket(
     scoped_ptr<StreamSocket> socket,
     X509Certificate* certificate,
     crypto::RSAPrivateKey* key,
     const SSLConfig& ssl_config) {
+  crypto::EnsureOpenSSLInit();
+  return scoped_ptr<SSLServerSocket>(
+      new SSLServerSocketOpenSSL(socket.Pass(), certificate, key, ssl_config));
+}
+
+SSLServerSocketOpenSSL::SSLServerSocketOpenSSL(
+    scoped_ptr<StreamSocket> transport_socket,
+    scoped_refptr<X509Certificate> certificate,
+    crypto::RSAPrivateKey* key,
+    const SSLConfig& ssl_config)
+    : transport_send_busy_(false),
+      transport_recv_busy_(false),
+      transport_recv_eof_(false),
+      user_read_buf_len_(0),
+      user_write_buf_len_(0),
+      transport_write_error_(OK),
+      ssl_(NULL),
+      transport_bio_(NULL),
+      transport_socket_(transport_socket.Pass()),
+      ssl_config_(ssl_config),
+      cert_(certificate),
+      next_handshake_state_(STATE_NONE),
+      completed_handshake_(false) {
+  // TODO(byungchul): Need a better way to clone a key.
+  std::vector<uint8> key_bytes;
+  CHECK(key->ExportPrivateKey(&key_bytes));
+  key_.reset(crypto::RSAPrivateKey::CreateFromPrivateKeyInfo(key_bytes));
+  CHECK(key_.get());
+}
+
+SSLServerSocketOpenSSL::~SSLServerSocketOpenSSL() {
+  if (ssl_) {
+    // Calling SSL_shutdown prevents the session from being marked as
+    // unresumable.
+    SSL_shutdown(ssl_);
+    SSL_free(ssl_);
+    ssl_ = NULL;
+  }
+  if (transport_bio_) {
+    BIO_free_all(transport_bio_);
+    transport_bio_ = NULL;
+  }
+}
+
+int SSLServerSocketOpenSSL::Handshake(const CompletionCallback& callback) {
+  net_log_.BeginEvent(NetLog::TYPE_SSL_SERVER_HANDSHAKE);
+
+  // Set up new ssl object.
+  int rv = Init();
+  if (rv != OK) {
+    LOG(ERROR) << "Failed to initialize OpenSSL: rv=" << rv;
+    net_log_.EndEventWithNetErrorCode(NetLog::TYPE_SSL_SERVER_HANDSHAKE, rv);
+    return rv;
+  }
+
+  // Set SSL to server mode. Handshake happens in the loop below.
+  SSL_set_accept_state(ssl_);
+
+  GotoState(STATE_HANDSHAKE);
+  rv = DoHandshakeLoop(OK);
+  if (rv == ERR_IO_PENDING) {
+    user_handshake_callback_ = callback;
+  } else {
+    net_log_.EndEventWithNetErrorCode(NetLog::TYPE_SSL_SERVER_HANDSHAKE, rv);
+  }
+
+  return rv > OK ? OK : rv;
+}
+
+int SSLServerSocketOpenSSL::ExportKeyingMaterial(
+    const base::StringPiece& label,
+    bool has_context,
+    const base::StringPiece& context,
+    unsigned char* out,
+    unsigned int outlen) {
+  if (!IsConnected())
+    return ERR_SOCKET_NOT_CONNECTED;
+
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+
+  int rv = SSL_export_keying_material(
+      ssl_, out, outlen, label.data(), label.size(),
+      reinterpret_cast<const unsigned char*>(context.data()),
+      context.length(), context.length() > 0);
+
+  if (rv != 1) {
+    int ssl_error = SSL_get_error(ssl_, rv);
+    LOG(ERROR) << "Failed to export keying material;"
+               << " returned " << rv
+               << ", SSL error code " << ssl_error;
+    return MapOpenSSLError(ssl_error, err_tracer);
+  }
+  return OK;
+}
+
+int SSLServerSocketOpenSSL::GetTLSUniqueChannelBinding(std::string* out) {
   NOTIMPLEMENTED();
-  return scoped_ptr<SSLServerSocket>();
+  return ERR_NOT_IMPLEMENTED;
+}
+
+int SSLServerSocketOpenSSL::Read(IOBuffer* buf, int buf_len,
+                                 const CompletionCallback& callback) {
+  DCHECK(user_read_callback_.is_null());
+  DCHECK(user_handshake_callback_.is_null());
+  DCHECK(!user_read_buf_.get());
+  DCHECK(!callback.is_null());
+
+  user_read_buf_ = buf;
+  user_read_buf_len_ = buf_len;
+
+  DCHECK(completed_handshake_);
+
+  int rv = DoReadLoop(OK);
+
+  if (rv == ERR_IO_PENDING) {
+    user_read_callback_ = callback;
+  } else {
+    user_read_buf_ = NULL;
+    user_read_buf_len_ = 0;
+  }
+
+  return rv;
+}
+
+int SSLServerSocketOpenSSL::Write(IOBuffer* buf, int buf_len,
+                                  const CompletionCallback& callback) {
+  DCHECK(user_write_callback_.is_null());
+  DCHECK(!user_write_buf_.get());
+  DCHECK(!callback.is_null());
+
+  user_write_buf_ = buf;
+  user_write_buf_len_ = buf_len;
+
+  int rv = DoWriteLoop(OK);
+
+  if (rv == ERR_IO_PENDING) {
+    user_write_callback_ = callback;
+  } else {
+    user_write_buf_ = NULL;
+    user_write_buf_len_ = 0;
+  }
+  return rv;
+}
+
+int SSLServerSocketOpenSSL::SetReceiveBufferSize(int32 size) {
+  return transport_socket_->SetReceiveBufferSize(size);
+}
+
+int SSLServerSocketOpenSSL::SetSendBufferSize(int32 size) {
+  return transport_socket_->SetSendBufferSize(size);
+}
+
+int SSLServerSocketOpenSSL::Connect(const CompletionCallback& callback) {
+  NOTIMPLEMENTED();
+  return ERR_NOT_IMPLEMENTED;
+}
+
+void SSLServerSocketOpenSSL::Disconnect() {
+  transport_socket_->Disconnect();
+}
+
+bool SSLServerSocketOpenSSL::IsConnected() const {
+  // TODO(wtc): Check transport_socket_->IsConnected() as well.

[wtc, 2014/05/16 19:36:14]

This comment should say "Find out if we should check transport_socket..."

[byungchul, 2014/05/16 19:50:32]

Done.

+  return completed_handshake_;
+}
+
+bool SSLServerSocketOpenSSL::IsConnectedAndIdle() const {
+  return completed_handshake_ && transport_socket_->IsConnectedAndIdle();
+}
+
+int SSLServerSocketOpenSSL::GetPeerAddress(IPEndPoint* address) const {
+  if (!IsConnected())
+    return ERR_SOCKET_NOT_CONNECTED;
+  return transport_socket_->GetPeerAddress(address);
+}
+
+int SSLServerSocketOpenSSL::GetLocalAddress(IPEndPoint* address) const {
+  if (!IsConnected())
+    return ERR_SOCKET_NOT_CONNECTED;
+  return transport_socket_->GetLocalAddress(address);
+}
+
+const BoundNetLog& SSLServerSocketOpenSSL::NetLog() const {
+  return net_log_;
+}
+
+void SSLServerSocketOpenSSL::SetSubresourceSpeculation() {
+  transport_socket_->SetSubresourceSpeculation();
+}
+
+void SSLServerSocketOpenSSL::SetOmniboxSpeculation() {
+  transport_socket_->SetOmniboxSpeculation();
+}
+
+bool SSLServerSocketOpenSSL::WasEverUsed() const {
+  return transport_socket_->WasEverUsed();
+}
+
+bool SSLServerSocketOpenSSL::UsingTCPFastOpen() const {
+  return transport_socket_->UsingTCPFastOpen();
+}
+
+bool SSLServerSocketOpenSSL::WasNpnNegotiated() const {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+NextProto SSLServerSocketOpenSSL::GetNegotiatedProtocol() const {
+  // NPN is not supported by this class.
+  return kProtoUnknown;
+}
+
+bool SSLServerSocketOpenSSL::GetSSLInfo(SSLInfo* ssl_info) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+void SSLServerSocketOpenSSL::OnSendComplete(int result) {
+  if (next_handshake_state_ == STATE_HANDSHAKE) {
+    // In handshake phase.
+    OnHandshakeIOComplete(result);
+    return;
+  }
+
+  // TODO(byungchul): This state machine is not correct. Copy the state machine
+  // of SSLClientSocketOpenSSL::OnSendComplete() which handles it better.
+  if (!completed_handshake_)
+    return;
+
+  if (user_write_buf_.get()) {
+    int rv = DoWriteLoop(result);
+    if (rv != ERR_IO_PENDING)
+      DoWriteCallback(rv);
+  } else {
+    // Ensure that any queued ciphertext is flushed.
+    DoTransportIO();
+  }
+}
+
+void SSLServerSocketOpenSSL::OnRecvComplete(int result) {
+  if (next_handshake_state_ == STATE_HANDSHAKE) {
+    // In handshake phase.
+    OnHandshakeIOComplete(result);
+    return;
+  }
+
+  // Network layer received some data, check if client requested to read
+  // decrypted data.
+  if (!user_read_buf_.get() || !completed_handshake_)
+    return;
+
+  int rv = DoReadLoop(result);
+  if (rv != ERR_IO_PENDING)
+    DoReadCallback(rv);
+}
+
+void SSLServerSocketOpenSSL::OnHandshakeIOComplete(int result) {
+  int rv = DoHandshakeLoop(result);
+  if (rv == ERR_IO_PENDING)
+    return;
+
+  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_SSL_SERVER_HANDSHAKE, rv);
+  if (!user_handshake_callback_.is_null())
+    DoHandshakeCallback(rv);
+}
+
+// Return 0 for EOF,
+// > 0 for bytes transferred immediately,
+// < 0 for error (or the non-error ERR_IO_PENDING).
+int SSLServerSocketOpenSSL::BufferSend() {
+  if (transport_send_busy_)
+    return ERR_IO_PENDING;
+
+  if (!send_buffer_.get()) {
+    // Get a fresh send buffer out of the send BIO.
+    size_t max_read = BIO_ctrl_pending(transport_bio_);
+    if (!max_read)
+      return 0;  // Nothing pending in the OpenSSL write BIO.
+    send_buffer_ = new DrainableIOBuffer(new IOBuffer(max_read), max_read);
+    int read_bytes = BIO_read(transport_bio_, send_buffer_->data(), max_read);
+    DCHECK_GT(read_bytes, 0);
+    CHECK_EQ(static_cast<int>(max_read), read_bytes);
+  }
+
+  int rv = transport_socket_->Write(
+      send_buffer_.get(),
+      send_buffer_->BytesRemaining(),
+      base::Bind(&SSLServerSocketOpenSSL::BufferSendComplete,
+                 base::Unretained(this)));
+  if (rv == ERR_IO_PENDING) {
+    transport_send_busy_ = true;
+  } else {
+    TransportWriteComplete(rv);
+  }
+  return rv;
+}
+
+void SSLServerSocketOpenSSL::BufferSendComplete(int result) {
+  transport_send_busy_ = false;
+  TransportWriteComplete(result);
+  OnSendComplete(result);
+}
+
+void SSLServerSocketOpenSSL::TransportWriteComplete(int result) {
+  DCHECK(ERR_IO_PENDING != result);
+  if (result < 0) {
+    // Got a socket write error; close the BIO to indicate this upward.
+    //
+    // TODO(davidben): The value of |result| gets lost. Feed the error back into
+    // the BIO so it gets (re-)detected in OnSendComplete. Perhaps with
+    // BIO_set_callback.
+    DVLOG(1) << "TransportWriteComplete error " << result;
+    (void)BIO_shutdown_wr(SSL_get_wbio(ssl_));
+
+    // Match the fix for http://crbug.com/249848 in NSS by erroring future reads
+    // from the socket after a write error.
+    //
+    // TODO(davidben): Avoid having read and write ends interact this way.
+    transport_write_error_ = result;
+    (void)BIO_shutdown_wr(transport_bio_);
+    send_buffer_ = NULL;
+  } else {
+    DCHECK(send_buffer_.get());
+    send_buffer_->DidConsume(result);
+    DCHECK_GE(send_buffer_->BytesRemaining(), 0);
+    if (send_buffer_->BytesRemaining() <= 0)
+      send_buffer_ = NULL;
+  }
+}
+
+int SSLServerSocketOpenSSL::BufferRecv() {
+  if (transport_recv_busy_)
+    return ERR_IO_PENDING;
+
+  // Determine how much was requested from |transport_bio_| that was not
+  // actually available.
+  size_t requested = BIO_ctrl_get_read_request(transport_bio_);
+  if (requested == 0) {
+    // This is not a perfect match of error codes, as no operation is
+    // actually pending. However, returning 0 would be interpreted as
+    // a possible sign of EOF, which is also an inappropriate match.
+    return ERR_IO_PENDING;
+  }
+
+  // Known Issue: While only reading |requested| data is the more correct
+  // implementation, it has the downside of resulting in frequent reads:
+  // One read for the SSL record header (~5 bytes) and one read for the SSL
+  // record body. Rather than issuing these reads to the underlying socket
+  // (and constantly allocating new IOBuffers), a single Read() request to
+  // fill |transport_bio_| is issued. As long as an SSL client socket cannot
+  // be gracefully shutdown (via SSL close alerts) and re-used for non-SSL
+  // traffic, this over-subscribed Read()ing will not cause issues.
+  size_t max_write = BIO_ctrl_get_write_guarantee(transport_bio_);
+  if (!max_write)
+    return ERR_IO_PENDING;
+
+  recv_buffer_ = new IOBuffer(max_write);
+  int rv = transport_socket_->Read(
+      recv_buffer_.get(),
+      max_write,
+      base::Bind(&SSLServerSocketOpenSSL::BufferRecvComplete,
+                 base::Unretained(this)));
+  if (rv == ERR_IO_PENDING) {
+    transport_recv_busy_ = true;
+  } else {
+    rv = TransportReadComplete(rv);
+  }
+  return rv;
+}
+
+void SSLServerSocketOpenSSL::BufferRecvComplete(int result) {
+  result = TransportReadComplete(result);
+  OnRecvComplete(result);
+}
+
+int SSLServerSocketOpenSSL::TransportReadComplete(int result) {
+  DCHECK(ERR_IO_PENDING != result);
+  if (result <= 0) {
+    DVLOG(1) << "TransportReadComplete result " << result;
+    // Received 0 (end of file) or an error. Either way, bubble it up to the
+    // SSL layer via the BIO. TODO(joth): consider stashing the error code, to
+    // relay up to the SSL socket client (i.e. via DoReadCallback).
+    if (result == 0)
+      transport_recv_eof_ = true;
+    (void)BIO_shutdown_wr(transport_bio_);
+  } else if (transport_write_error_ < 0) {
+    // Mirror transport write errors as read failures; transport_bio_ has been
+    // shut down by TransportWriteComplete, so the BIO_write will fail, failing
+    // the CHECK. http://crbug.com/335557.
+    result = transport_write_error_;
+  } else {
+    DCHECK(recv_buffer_.get());
+    int ret = BIO_write(transport_bio_, recv_buffer_->data(), result);
+    // A write into a memory BIO should always succeed.
+    DCHECK_EQ(result, ret);
+  }
+  recv_buffer_ = NULL;
+  transport_recv_busy_ = false;
+  return result;
+}
+
+// Do as much network I/O as possible between the buffer and the
+// transport socket. Return true if some I/O performed, false
+// otherwise (error or ERR_IO_PENDING).
+bool SSLServerSocketOpenSSL::DoTransportIO() {
+  bool network_moved = false;
+  int rv;
+  // Read and write as much data as possible. The loop is necessary because
+  // Write() may return synchronously.
+  do {
+    rv = BufferSend();
+    if (rv != ERR_IO_PENDING && rv != 0)
+      network_moved = true;
+  } while (rv > 0);
+  if (!transport_recv_eof_ && BufferRecv() != ERR_IO_PENDING)
+    network_moved = true;
+  return network_moved;
+}
+
+int SSLServerSocketOpenSSL::DoPayloadRead() {
+  DCHECK(user_read_buf_.get());
+  DCHECK_GT(user_read_buf_len_, 0);
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  int rv = SSL_read(ssl_, user_read_buf_->data(), user_read_buf_len_);
+  if (rv >= 0)
+    return rv;
+  int ssl_error = SSL_get_error(ssl_, rv);
+  int net_error = MapOpenSSLError(ssl_error, err_tracer);
+  if (net_error != ERR_IO_PENDING) {
+    net_log_.AddEvent(NetLog::TYPE_SSL_READ_ERROR,
+                      CreateNetLogSSLErrorCallback(net_error, ssl_error));
+  }
+  return net_error;
+}
+
+int SSLServerSocketOpenSSL::DoPayloadWrite() {
+  DCHECK(user_write_buf_.get());
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  int rv = SSL_write(ssl_, user_write_buf_->data(), user_write_buf_len_);
+  if (rv >= 0)
+    return rv;
+  int ssl_error = SSL_get_error(ssl_, rv);
+  int net_error = MapOpenSSLError(ssl_error, err_tracer);
+  if (net_error != ERR_IO_PENDING) {
+    net_log_.AddEvent(NetLog::TYPE_SSL_WRITE_ERROR,
+                      CreateNetLogSSLErrorCallback(net_error, ssl_error));
+  }
+  return net_error;
+}
+
+int SSLServerSocketOpenSSL::DoHandshakeLoop(int last_io_result) {
+  int rv = last_io_result;
+  do {
+    // Default to STATE_NONE for next state.
+    // (This is a quirk carried over from the windows
+    // implementation.  It makes reading the logs a bit harder.)
+    // State handlers can and often do call GotoState just
+    // to stay in the current state.
+    State state = next_handshake_state_;
+    GotoState(STATE_NONE);
+    switch (state) {
+      case STATE_HANDSHAKE:
+        rv = DoHandshake();
+        break;
+      case STATE_NONE:
+      default:
+        rv = ERR_UNEXPECTED;
+        LOG(DFATAL) << "unexpected state " << state;
+        break;
+    }
+
+    // Do the actual network I/O
+    bool network_moved = DoTransportIO();
+    if (network_moved && next_handshake_state_ == STATE_HANDSHAKE) {
+      // In general we exit the loop if rv is ERR_IO_PENDING.  In this
+      // special case we keep looping even if rv is ERR_IO_PENDING because
+      // the transport IO may allow DoHandshake to make progress.
+      rv = OK;  // This causes us to stay in the loop.
+    }
+  } while (rv != ERR_IO_PENDING && next_handshake_state_ != STATE_NONE);
+  return rv;
+}
+
+int SSLServerSocketOpenSSL::DoReadLoop(int result) {
+  DCHECK(completed_handshake_);
+  DCHECK(next_handshake_state_ == STATE_NONE);
+
+  if (result < 0)
+    return result;
+
+  bool network_moved;
+  int rv;
+  do {
+    rv = DoPayloadRead();
+    network_moved = DoTransportIO();
+  } while (rv == ERR_IO_PENDING && network_moved);
+  return rv;
+}
+
+int SSLServerSocketOpenSSL::DoWriteLoop(int result) {
+  DCHECK(completed_handshake_);
+  DCHECK_EQ(next_handshake_state_, STATE_NONE);
+
+  if (result < 0)
+    return result;
+
+  bool network_moved;
+  int rv;
+  do {
+    rv = DoPayloadWrite();
+    network_moved = DoTransportIO();
+  } while (rv == ERR_IO_PENDING && network_moved);
+  return rv;
+}
+
+int SSLServerSocketOpenSSL::DoHandshake() {
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  int net_error = OK;
+  int rv = SSL_do_handshake(ssl_);
+
+  if (rv == 1) {
+    completed_handshake_ = true;
+  } else {
+    int ssl_error = SSL_get_error(ssl_, rv);
+    net_error = MapOpenSSLError(ssl_error, err_tracer);
+
+    // If not done, stay in this state
+    if (net_error == ERR_IO_PENDING) {
+      GotoState(STATE_HANDSHAKE);
+    } else {
+      LOG(ERROR) << "handshake failed; returned " << rv
+                 << ", SSL error code " << ssl_error
+                 << ", net_error " << net_error;
+      net_log_.AddEvent(NetLog::TYPE_SSL_HANDSHAKE_ERROR,
+                        CreateNetLogSSLErrorCallback(net_error, ssl_error));
+    }
+  }
+  return net_error;
+}
+
+void SSLServerSocketOpenSSL::DoHandshakeCallback(int rv) {
+  DCHECK_NE(rv, ERR_IO_PENDING);
+  ResetAndReturn(&user_handshake_callback_).Run(rv > OK ? OK : rv);
+}
+
+void SSLServerSocketOpenSSL::DoReadCallback(int rv) {
+  DCHECK(rv != ERR_IO_PENDING);
+  DCHECK(!user_read_callback_.is_null());
+
+  user_read_buf_ = NULL;
+  user_read_buf_len_ = 0;
+  ResetAndReturn(&user_read_callback_).Run(rv);
+}
+
+void SSLServerSocketOpenSSL::DoWriteCallback(int rv) {
+  DCHECK(rv != ERR_IO_PENDING);
+  DCHECK(!user_write_callback_.is_null());
+
+  user_write_buf_ = NULL;
+  user_write_buf_len_ = 0;
+  ResetAndReturn(&user_write_callback_).Run(rv);
+}
+
+int SSLServerSocketOpenSSL::Init() {
+  DCHECK(!ssl_);
+  DCHECK(!transport_bio_);
+
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+
+  crypto::ScopedOpenSSL<SSL_CTX, SSL_CTX_free> ssl_ctx(
+      // It support SSLv2, SSLv3, and TLSv1.
+      SSL_CTX_new(SSLv23_server_method()));
+  ssl_ = SSL_new(ssl_ctx.get());
+  if (!ssl_)
+    return ERR_UNEXPECTED;
+
+  BIO* ssl_bio = NULL;
+  // 0 => use default buffer sizes.
+  if (!BIO_new_bio_pair(&ssl_bio, 0, &transport_bio_, 0))
+    return ERR_UNEXPECTED;
+  DCHECK(ssl_bio);
+  DCHECK(transport_bio_);
+
+  SSL_set_bio(ssl_, ssl_bio, ssl_bio);
+
+  // Set certificate and private key.
+  DCHECK(cert_->os_cert_handle());
+  if (SSL_use_certificate(ssl_, cert_->os_cert_handle()) != 1) {
+    LOG(ERROR) << "Cannot set certificate.";
+    return ERR_UNEXPECTED;
+  }
+
+  DCHECK(key_->key());
+  if (SSL_use_PrivateKey(ssl_, key_->key()) != 1) {
+    LOG(ERROR) << "Cannot set private key.";
+    return ERR_UNEXPECTED;
+  }
+
+  // OpenSSL defaults some options to on, others to off. To avoid ambiguity,
+  // set everything we care about to an absolute value.
+  SslSetClearMask options;
+  options.ConfigureFlag(SSL_OP_NO_SSLv2, true);
+  bool ssl3_enabled = (ssl_config_.version_min == SSL_PROTOCOL_VERSION_SSL3);
+  options.ConfigureFlag(SSL_OP_NO_SSLv3, !ssl3_enabled);
+  bool tls1_enabled = (ssl_config_.version_min <= SSL_PROTOCOL_VERSION_TLS1 &&
+                       ssl_config_.version_max >= SSL_PROTOCOL_VERSION_TLS1);
+  options.ConfigureFlag(SSL_OP_NO_TLSv1, !tls1_enabled);
+  bool tls1_1_enabled =
+      (ssl_config_.version_min <= SSL_PROTOCOL_VERSION_TLS1_1 &&
+       ssl_config_.version_max >= SSL_PROTOCOL_VERSION_TLS1_1);
+  options.ConfigureFlag(SSL_OP_NO_TLSv1_1, !tls1_1_enabled);
+  bool tls1_2_enabled =
+      (ssl_config_.version_min <= SSL_PROTOCOL_VERSION_TLS1_2 &&
+       ssl_config_.version_max >= SSL_PROTOCOL_VERSION_TLS1_2);
+  options.ConfigureFlag(SSL_OP_NO_TLSv1_2, !tls1_2_enabled);
+
+  options.ConfigureFlag(SSL_OP_NO_COMPRESSION, true);
+
+  SSL_set_options(ssl_, options.set_mask);
+  SSL_clear_options(ssl_, options.clear_mask);
+
+  // Same as above, this time for the SSL mode.
+  SslSetClearMask mode;
+
+  mode.ConfigureFlag(SSL_MODE_RELEASE_BUFFERS, true);
+
+  SSL_set_mode(ssl_, mode.set_mask);
+  SSL_clear_mode(ssl_, mode.clear_mask);
+
+  return OK;
 }
 
 }  // namespace net