Add m-esr52 at 52.6.0

1 files changed, 1262 insertions, 0 deletions

diff --git a/media/mtransport/transportlayerdtls.cpp b/media/mtransport/transportlayerdtls.cpp
new file mode 100644
index 0000000000..55bf53f1b4
--- /dev/null
+++ b/media/mtransport/transportlayerdtls.cpp
@@ -0,0 +1,1262 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Original author: ekr@rtfm.com
+
+#include "transportlayerdtls.h"
+
+#include <algorithm>
+#include <queue>
+#include <sstream>
+
+#include "dtlsidentity.h"
+#include "keyhi.h"
+#include "logging.h"
+#include "mozilla/Move.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "nsCOMPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIEventTarget.h"
+#include "nsNetCID.h"
+#include "nsServiceManagerUtils.h"
+#include "ssl.h"
+#include "sslerr.h"
+#include "sslproto.h"
+#include "transportflow.h"
+
+
+namespace mozilla {
+
+MOZ_MTLOG_MODULE("mtransport")
+
+static PRDescIdentity transport_layer_identity = PR_INVALID_IO_LAYER;
+
+// TODO: Implement a mode for this where
+// the channel is not ready until confirmed externally
+// (e.g., after cert check).
+
+#define UNIMPLEMENTED                                           \
+  MOZ_MTLOG(ML_ERROR,                                           \
+       "Call to unimplemented function "<< __FUNCTION__);       \
+  MOZ_ASSERT(false);                                            \
+  PR_SetError(PR_NOT_IMPLEMENTED_ERROR, 0)
+
+#define MAX_ALPN_LENGTH 255
+
+// We need to adapt the NSPR/libssl model to the TransportFlow model.
+// The former wants pull semantics and TransportFlow wants push.
+//
+// - A TransportLayerDtls assumes it is sitting on top of another
+//   TransportLayer, which means that events come in asynchronously.
+// - NSS (libssl) wants to sit on top of a PRFileDesc and poll.
+// - The TransportLayerNSPRAdapter is a PRFileDesc containing a
+//   FIFO.
+// - When TransportLayerDtls.PacketReceived() is called, we insert
+//   the packets in the FIFO and then do a PR_Recv() on the NSS
+//   PRFileDesc, which eventually reads off the FIFO.
+//
+// All of this stuff is assumed to happen solely in a single thread
+// (generally the SocketTransportService thread)
+struct Packet {
+  Packet() : data_(nullptr), len_(0) {}
+
+  void Assign(const void *data, int32_t len) {
+    data_.reset(new uint8_t[len]);
+    memcpy(data_.get(), data, len);
+    len_ = len;
+  }
+
+  UniquePtr<uint8_t[]> data_;
+  int32_t len_;
+};
+
+void TransportLayerNSPRAdapter::PacketReceived(const void *data, int32_t len) {
+  if (enabled_) {
+    input_.push(new Packet());
+    input_.back()->Assign(data, len);
+  }
+}
+
+int32_t TransportLayerNSPRAdapter::Recv(void *buf, int32_t buflen) {
+  if (input_.empty()) {
+    PR_SetError(PR_WOULD_BLOCK_ERROR, 0);
+    return -1;
+  }
+
+  Packet* front = input_.front();
+  if (buflen < front->len_) {
+    MOZ_ASSERT(false, "Not enough buffer space to receive into");
+    PR_SetError(PR_BUFFER_OVERFLOW_ERROR, 0);
+    return -1;
+  }
+
+  int32_t count = front->len_;
+  memcpy(buf, front->data_.get(), count);
+
+  input_.pop();
+  delete front;
+
+  return count;
+}
+
+int32_t TransportLayerNSPRAdapter::Write(const void *buf, int32_t length) {
+  if (!enabled_) {
+    MOZ_MTLOG(ML_WARNING, "Writing to disabled transport layer");
+    return -1;
+  }
+
+  TransportResult r = output_->SendPacket(
+      static_cast<const unsigned char *>(buf), length);
+  if (r >= 0) {
+    return r;
+  }
+
+  if (r == TE_WOULDBLOCK) {
+    PR_SetError(PR_WOULD_BLOCK_ERROR, 0);
+  } else {
+    PR_SetError(PR_IO_ERROR, 0);
+  }
+
+  return -1;
+}
+
+
+// Implementation of NSPR methods
+static PRStatus TransportLayerClose(PRFileDesc *f) {
+  f->dtor(f);
+  return PR_SUCCESS;
+}
+
+static int32_t TransportLayerRead(PRFileDesc *f, void *buf, int32_t length) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static int32_t TransportLayerWrite(PRFileDesc *f, const void *buf, int32_t length) {
+  TransportLayerNSPRAdapter *io = reinterpret_cast<TransportLayerNSPRAdapter *>(f->secret);
+  return io->Write(buf, length);
+}
+
+static int32_t TransportLayerAvailable(PRFileDesc *f) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+int64_t TransportLayerAvailable64(PRFileDesc *f) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static PRStatus TransportLayerSync(PRFileDesc *f) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static int32_t TransportLayerSeek(PRFileDesc *f, int32_t offset,
+                                  PRSeekWhence how) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static int64_t TransportLayerSeek64(PRFileDesc *f, int64_t offset,
+                                    PRSeekWhence how) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static PRStatus TransportLayerFileInfo(PRFileDesc *f, PRFileInfo *info) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static PRStatus TransportLayerFileInfo64(PRFileDesc *f, PRFileInfo64 *info) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static int32_t TransportLayerWritev(PRFileDesc *f, const PRIOVec *iov,
+                                    int32_t iov_size, PRIntervalTime to) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static PRStatus TransportLayerConnect(PRFileDesc *f, const PRNetAddr *addr,
+                                      PRIntervalTime to) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static PRFileDesc *TransportLayerAccept(PRFileDesc *sd, PRNetAddr *addr,
+                                        PRIntervalTime to) {
+  UNIMPLEMENTED;
+  return nullptr;
+}
+
+static PRStatus TransportLayerBind(PRFileDesc *f, const PRNetAddr *addr) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static PRStatus TransportLayerListen(PRFileDesc *f, int32_t depth) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static PRStatus TransportLayerShutdown(PRFileDesc *f, int32_t how) {
+  // This is only called from NSS when we are the server and the client refuses
+  // to provide a certificate.  In this case, the handshake is destined for
+  // failure, so we will just let this pass.
+  TransportLayerNSPRAdapter *io = reinterpret_cast<TransportLayerNSPRAdapter *>(f->secret);
+  io->SetEnabled(false);
+  return PR_SUCCESS;
+}
+
+// This function does not support peek, or waiting until `to`
+static int32_t TransportLayerRecv(PRFileDesc *f, void *buf, int32_t buflen,
+                                  int32_t flags, PRIntervalTime to) {
+  MOZ_ASSERT(flags == 0);
+  if (flags != 0) {
+    PR_SetError(PR_NOT_IMPLEMENTED_ERROR, 0);
+    return -1;
+  }
+
+  TransportLayerNSPRAdapter *io = reinterpret_cast<TransportLayerNSPRAdapter *>(f->secret);
+  return io->Recv(buf, buflen);
+}
+
+// Note: this is always nonblocking and assumes a zero timeout.
+static int32_t TransportLayerSend(PRFileDesc *f, const void *buf, int32_t amount,
+                                  int32_t flags, PRIntervalTime to) {
+  int32_t written = TransportLayerWrite(f, buf, amount);
+  return written;
+}
+
+static int32_t TransportLayerRecvfrom(PRFileDesc *f, void *buf, int32_t amount,
+                                      int32_t flags, PRNetAddr *addr, PRIntervalTime to) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static int32_t TransportLayerSendto(PRFileDesc *f, const void *buf, int32_t amount,
+                                    int32_t flags, const PRNetAddr *addr, PRIntervalTime to) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static int16_t TransportLayerPoll(PRFileDesc *f, int16_t in_flags, int16_t *out_flags) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static int32_t TransportLayerAcceptRead(PRFileDesc *sd, PRFileDesc **nd,
+                                        PRNetAddr **raddr,
+                                        void *buf, int32_t amount, PRIntervalTime t) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static int32_t TransportLayerTransmitFile(PRFileDesc *sd, PRFileDesc *f,
+                                          const void *headers, int32_t hlen,
+                                          PRTransmitFileFlags flags, PRIntervalTime t) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static PRStatus TransportLayerGetpeername(PRFileDesc *f, PRNetAddr *addr) {
+  // TODO: Modify to return unique names for each channel
+  // somehow, as opposed to always the same static address. The current
+  // implementation messes up the session cache, which is why it's off
+  // elsewhere
+  addr->inet.family = PR_AF_INET;
+  addr->inet.port = 0;
+  addr->inet.ip = 0;
+
+  return PR_SUCCESS;
+}
+
+static PRStatus TransportLayerGetsockname(PRFileDesc *f, PRNetAddr *addr) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static PRStatus TransportLayerGetsockoption(PRFileDesc *f, PRSocketOptionData *opt) {
+  switch (opt->option) {
+    case PR_SockOpt_Nonblocking:
+      opt->value.non_blocking = PR_TRUE;
+      return PR_SUCCESS;
+    default:
+      UNIMPLEMENTED;
+      break;
+  }
+
+  return PR_FAILURE;
+}
+
+// Imitate setting socket options. These are mostly noops.
+static PRStatus TransportLayerSetsockoption(PRFileDesc *f,
+                                            const PRSocketOptionData *opt) {
+  switch (opt->option) {
+    case PR_SockOpt_Nonblocking:
+      return PR_SUCCESS;
+    case PR_SockOpt_NoDelay:
+      return PR_SUCCESS;
+    default:
+      UNIMPLEMENTED;
+      break;
+  }
+
+  return PR_FAILURE;
+}
+
+static int32_t TransportLayerSendfile(PRFileDesc *out, PRSendFileData *in,
+                                      PRTransmitFileFlags flags, PRIntervalTime to) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static PRStatus TransportLayerConnectContinue(PRFileDesc *f, int16_t flags) {
+  UNIMPLEMENTED;
+  return PR_FAILURE;
+}
+
+static int32_t TransportLayerReserved(PRFileDesc *f) {
+  UNIMPLEMENTED;
+  return -1;
+}
+
+static const struct PRIOMethods TransportLayerMethods = {
+  PR_DESC_LAYERED,
+  TransportLayerClose,
+  TransportLayerRead,
+  TransportLayerWrite,
+  TransportLayerAvailable,
+  TransportLayerAvailable64,
+  TransportLayerSync,
+  TransportLayerSeek,
+  TransportLayerSeek64,
+  TransportLayerFileInfo,
+  TransportLayerFileInfo64,
+  TransportLayerWritev,
+  TransportLayerConnect,
+  TransportLayerAccept,
+  TransportLayerBind,
+  TransportLayerListen,
+  TransportLayerShutdown,
+  TransportLayerRecv,
+  TransportLayerSend,
+  TransportLayerRecvfrom,
+  TransportLayerSendto,
+  TransportLayerPoll,
+  TransportLayerAcceptRead,
+  TransportLayerTransmitFile,
+  TransportLayerGetsockname,
+  TransportLayerGetpeername,
+  TransportLayerReserved,
+  TransportLayerReserved,
+  TransportLayerGetsockoption,
+  TransportLayerSetsockoption,
+  TransportLayerSendfile,
+  TransportLayerConnectContinue,
+  TransportLayerReserved,
+  TransportLayerReserved,
+  TransportLayerReserved,
+  TransportLayerReserved
+};
+
+TransportLayerDtls::~TransportLayerDtls() {
+  nspr_io_adapter_->SetEnabled(false);
+  if (timer_) {
+    timer_->Cancel();
+  }
+}
+
+nsresult TransportLayerDtls::InitInternal() {
+  // Get the transport service as an event target
+  nsresult rv;
+  target_ = do_GetService(NS_SOCKETTRANSPORTSERVICE_CONTRACTID, &rv);
+
+  if (NS_FAILED(rv)) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't get socket transport service");
+    return rv;
+  }
+
+  timer_ = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't get timer");
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+
+void TransportLayerDtls::WasInserted() {
+  // Connect to the lower layers
+  if (!Setup()) {
+    TL_SET_STATE(TS_ERROR);
+  }
+}
+
+
+// Set the permitted and default ALPN identifiers.
+// The default is here to allow for peers that don't want to negotiate ALPN
+// in that case, the default string will be reported from GetNegotiatedAlpn().
+// Setting the default to the empty string causes the transport layer to fail
+// if ALPN is not negotiated.
+// Note: we only support Unicode strings here, which are encoded into UTF-8,
+// even though ALPN ostensibly allows arbitrary octet sequences.
+nsresult TransportLayerDtls::SetAlpn(
+  const std::set<std::string>& alpn_allowed,
+  const std::string& alpn_default) {
+
+  alpn_allowed_ = alpn_allowed;
+  alpn_default_ = alpn_default;
+
+  return NS_OK;
+}
+
+
+nsresult TransportLayerDtls::SetVerificationAllowAll() {
+  // Defensive programming
+  if (verification_mode_ != VERIFY_UNSET)
+    return NS_ERROR_ALREADY_INITIALIZED;
+
+  verification_mode_ = VERIFY_ALLOW_ALL;
+
+  return NS_OK;
+}
+
+nsresult
+TransportLayerDtls::SetVerificationDigest(const std::string digest_algorithm,
+                                          const unsigned char *digest_value,
+                                          size_t digest_len) {
+  // Defensive programming
+  if (verification_mode_ != VERIFY_UNSET &&
+      verification_mode_ != VERIFY_DIGEST) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  // Note that we do not sanity check these values for length.
+  // We merely ensure they will fit into the buffer.
+  // TODO: is there a Data construct we could use?
+  if (digest_len > kMaxDigestLength)
+    return NS_ERROR_INVALID_ARG;
+
+  digests_.push_back(new VerificationDigest(
+      digest_algorithm, digest_value, digest_len));
+
+  verification_mode_ = VERIFY_DIGEST;
+
+  return NS_OK;
+}
+
+// These are the named groups that we will allow.
+static const SSLNamedGroup NamedGroupPreferences[] = {
+  ssl_grp_ec_curve25519,
+  ssl_grp_ec_secp256r1,
+  ssl_grp_ec_secp384r1,
+  ssl_grp_ffdhe_2048,
+  ssl_grp_ffdhe_3072
+};
+
+// TODO: make sure this is called from STS. Otherwise
+// we have thread safety issues
+bool TransportLayerDtls::Setup() {
+  CheckThread();
+  SECStatus rv;
+
+  if (!downward_) {
+    MOZ_MTLOG(ML_ERROR, "DTLS layer with nothing below. This is useless");
+    return false;
+  }
+  nspr_io_adapter_ = MakeUnique<TransportLayerNSPRAdapter>(downward_);
+
+  if (!identity_) {
+    MOZ_MTLOG(ML_ERROR, "Can't start DTLS without an identity");
+    return false;
+  }
+
+  if (verification_mode_ == VERIFY_UNSET) {
+    MOZ_MTLOG(ML_ERROR,
+              "Can't start DTLS without specifying a verification mode");
+    return false;
+  }
+
+  if (transport_layer_identity == PR_INVALID_IO_LAYER) {
+    transport_layer_identity = PR_GetUniqueIdentity("nssstreamadapter");
+  }
+
+  UniquePRFileDesc pr_fd(PR_CreateIOLayerStub(transport_layer_identity,
+                                              &TransportLayerMethods));
+  MOZ_ASSERT(pr_fd != nullptr);
+  if (!pr_fd)
+    return false;
+  pr_fd->secret = reinterpret_cast<PRFilePrivate *>(nspr_io_adapter_.get());
+
+  UniquePRFileDesc ssl_fd(DTLS_ImportFD(nullptr, pr_fd.get()));
+  MOZ_ASSERT(ssl_fd != nullptr);  // This should never happen
+  if (!ssl_fd) {
+    return false;
+  }
+
+  Unused << pr_fd.release(); // ownership transfered to ssl_fd;
+
+  if (role_ == CLIENT) {
+    MOZ_MTLOG(ML_INFO, "Setting up DTLS as client");
+    rv = SSL_GetClientAuthDataHook(ssl_fd.get(), GetClientAuthDataHook,
+                                   this);
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, "Couldn't set identity");
+      return false;
+    }
+  } else {
+    MOZ_MTLOG(ML_INFO, "Setting up DTLS as server");
+    // Server side
+    rv = SSL_ConfigSecureServer(ssl_fd.get(), identity_->cert().get(),
+                                identity_->privkey(),
+                                identity_->auth_type());
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, "Couldn't set identity");
+      return false;
+    }
+
+    UniqueCERTCertList zero_certs(CERT_NewCertList());
+    rv = SSL_SetTrustAnchors(ssl_fd.get(), zero_certs.get());
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, "Couldn't set trust anchors");
+      return false;
+    }
+
+    // Insist on a certificate from the client
+    rv = SSL_OptionSet(ssl_fd.get(), SSL_REQUEST_CERTIFICATE, PR_TRUE);
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, "Couldn't request certificate");
+      return false;
+    }
+
+    rv = SSL_OptionSet(ssl_fd.get(), SSL_REQUIRE_CERTIFICATE, PR_TRUE);
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, "Couldn't require certificate");
+      return false;
+    }
+  }
+
+  // Require TLS 1.1 or 1.2. Perhaps some day in the future we will allow TLS
+  // 1.0 for stream modes.
+  SSLVersionRange version_range = {
+    SSL_LIBRARY_VERSION_TLS_1_1,
+    SSL_LIBRARY_VERSION_TLS_1_2
+  };
+
+  rv = SSL_VersionRangeSet(ssl_fd.get(), &version_range);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Can't disable SSLv3");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_ENABLE_SESSION_TICKETS, PR_FALSE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable session tickets");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_NO_CACHE, PR_TRUE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable session caching");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_ENABLE_DEFLATE, PR_FALSE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable deflate");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_ENABLE_RENEGOTIATION,
+                     SSL_RENEGOTIATE_NEVER);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable renegotiation");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_ENABLE_FALSE_START, PR_FALSE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable false start");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_NO_LOCKS, PR_TRUE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable locks");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_REUSE_SERVER_ECDHE_KEY, PR_FALSE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable ECDHE key reuse");
+    return false;
+  }
+
+  if (!SetupCipherSuites(ssl_fd)) {
+    return false;
+  }
+
+  rv = SSL_NamedGroupConfig(ssl_fd.get(), NamedGroupPreferences,
+                            mozilla::ArrayLength(NamedGroupPreferences));
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't set named groups");
+    return false;
+  }
+
+  // Certificate validation
+  rv = SSL_AuthCertificateHook(ssl_fd.get(), AuthCertificateHook,
+                               reinterpret_cast<void *>(this));
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't set certificate validation hook");
+    return false;
+  }
+
+  if (!SetupAlpn(ssl_fd)) {
+    return false;
+  }
+
+  // Now start the handshake
+  rv = SSL_ResetHandshake(ssl_fd.get(), role_ == SERVER ? PR_TRUE : PR_FALSE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't reset handshake");
+    return false;
+  }
+  ssl_fd_ = Move(ssl_fd);
+
+  // Finally, get ready to receive data
+  downward_->SignalStateChange.connect(this, &TransportLayerDtls::StateChange);
+  downward_->SignalPacketReceived.connect(this, &TransportLayerDtls::PacketReceived);
+
+  if (downward_->state() == TS_OPEN) {
+    TL_SET_STATE(TS_CONNECTING);
+    Handshake();
+  }
+
+  return true;
+}
+
+bool TransportLayerDtls::SetupAlpn(UniquePRFileDesc& ssl_fd) const {
+  if (alpn_allowed_.empty()) {
+    return true;
+  }
+
+  SECStatus rv = SSL_OptionSet(ssl_fd.get(), SSL_ENABLE_NPN, PR_FALSE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't disable NPN");
+    return false;
+  }
+
+  rv = SSL_OptionSet(ssl_fd.get(), SSL_ENABLE_ALPN, PR_TRUE);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't enable ALPN");
+    return false;
+  }
+
+  unsigned char buf[MAX_ALPN_LENGTH];
+  size_t offset = 0;
+  for (auto tag = alpn_allowed_.begin();
+       tag != alpn_allowed_.end(); ++tag) {
+    if ((offset + 1 + tag->length()) >= sizeof(buf)) {
+      MOZ_MTLOG(ML_ERROR, "ALPN too long");
+      return false;
+    }
+    buf[offset++] = tag->length();
+    memcpy(buf + offset, tag->c_str(), tag->length());
+    offset += tag->length();
+  }
+  rv = SSL_SetNextProtoNego(ssl_fd.get(), buf, offset);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't set ALPN string");
+    return false;
+  }
+  return true;
+}
+
+// Ciphers we need to enable.  These are on by default in standard firefox
+// builds, but can be disabled with prefs and they aren't on in our unit tests
+// since that uses NSS default configuration.
+//
+// Only override prefs to comply with MUST statements in the security-arch doc.
+// Anything outside this list is governed by the usual combination of policy
+// and user preferences.
+static const uint32_t EnabledCiphers[] = {
+  TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+  TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
+};
+
+// Disable all NSS suites modes without PFS or with old and rusty ciphersuites.
+// Anything outside this list is governed by the usual combination of policy
+// and user preferences.
+static const uint32_t DisabledCiphers[] = {
+  // Bug 1310061: disable all SHA384 ciphers until fixed
+  TLS_AES_256_GCM_SHA384,
+  TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+  TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+  TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,
+  TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384,
+  TLS_DHE_RSA_WITH_AES_256_GCM_SHA384,
+  TLS_DHE_DSS_WITH_AES_256_GCM_SHA384,
+
+  TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA,
+  TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+  TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
+  TLS_ECDHE_RSA_WITH_RC4_128_SHA,
+
+  TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
+  TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA,
+  TLS_DHE_DSS_WITH_RC4_128_SHA,
+
+  TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA,
+  TLS_ECDH_RSA_WITH_AES_128_CBC_SHA,
+  TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA,
+  TLS_ECDH_RSA_WITH_AES_256_CBC_SHA,
+  TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA,
+  TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA,
+  TLS_ECDH_ECDSA_WITH_RC4_128_SHA,
+  TLS_ECDH_RSA_WITH_RC4_128_SHA,
+
+  TLS_RSA_WITH_AES_128_GCM_SHA256,
+  TLS_RSA_WITH_AES_256_GCM_SHA384,
+  TLS_RSA_WITH_AES_128_CBC_SHA,
+  TLS_RSA_WITH_AES_128_CBC_SHA256,
+  TLS_RSA_WITH_CAMELLIA_128_CBC_SHA,
+  TLS_RSA_WITH_AES_256_CBC_SHA,
+  TLS_RSA_WITH_AES_256_CBC_SHA256,
+  TLS_RSA_WITH_CAMELLIA_256_CBC_SHA,
+  TLS_RSA_WITH_SEED_CBC_SHA,
+  TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+  TLS_RSA_WITH_RC4_128_SHA,
+  TLS_RSA_WITH_RC4_128_MD5,
+
+  TLS_DHE_RSA_WITH_DES_CBC_SHA,
+  TLS_DHE_DSS_WITH_DES_CBC_SHA,
+  TLS_RSA_WITH_DES_CBC_SHA,
+
+  TLS_ECDHE_ECDSA_WITH_NULL_SHA,
+  TLS_ECDHE_RSA_WITH_NULL_SHA,
+  TLS_ECDH_ECDSA_WITH_NULL_SHA,
+  TLS_ECDH_RSA_WITH_NULL_SHA,
+  TLS_RSA_WITH_NULL_SHA,
+  TLS_RSA_WITH_NULL_SHA256,
+  TLS_RSA_WITH_NULL_MD5,
+};
+
+bool TransportLayerDtls::SetupCipherSuites(UniquePRFileDesc& ssl_fd) const {
+  SECStatus rv;
+
+  // Set the SRTP ciphers
+  if (!srtp_ciphers_.empty()) {
+    // Note: std::vector is guaranteed to contiguous
+    rv = SSL_SetSRTPCiphers(ssl_fd.get(), &srtp_ciphers_[0],
+                            srtp_ciphers_.size());
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, "Couldn't set SRTP cipher suite");
+      return false;
+    }
+  }
+
+  for (const auto& cipher : EnabledCiphers) {
+    MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Enabling: " << cipher);
+    rv = SSL_CipherPrefSet(ssl_fd.get(), cipher, PR_TRUE);
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_ERROR, LAYER_INFO <<
+                "Unable to enable suite: " << cipher);
+      return false;
+    }
+  }
+
+  for (const auto& cipher : DisabledCiphers) {
+    MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Disabling: " << cipher);
+
+    PRBool enabled = false;
+    rv = SSL_CipherPrefGet(ssl_fd.get(), cipher, &enabled);
+    if (rv != SECSuccess) {
+      MOZ_MTLOG(ML_NOTICE, LAYER_INFO <<
+                "Unable to check if suite is enabled: " << cipher);
+      return false;
+    }
+    if (enabled) {
+      rv = SSL_CipherPrefSet(ssl_fd.get(), cipher, PR_FALSE);
+      if (rv != SECSuccess) {
+        MOZ_MTLOG(ML_NOTICE, LAYER_INFO <<
+                  "Unable to disable suite: " << cipher);
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+nsresult TransportLayerDtls::GetCipherSuite(uint16_t* cipherSuite) const {
+  CheckThread();
+  if (!cipherSuite) {
+    MOZ_MTLOG(ML_ERROR, LAYER_INFO << "GetCipherSuite passed a nullptr");
+    return NS_ERROR_NULL_POINTER;
+  }
+  if (state_ != TS_OPEN) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  SSLChannelInfo info;
+  SECStatus rv = SSL_GetChannelInfo(ssl_fd_.get(), &info, sizeof(info));
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_NOTICE, LAYER_INFO << "GetCipherSuite can't get channel info");
+    return NS_ERROR_FAILURE;
+  }
+  *cipherSuite = info.cipherSuite;
+  return NS_OK;
+}
+
+void TransportLayerDtls::StateChange(TransportLayer *layer, State state) {
+  if (state <= state_) {
+    MOZ_MTLOG(ML_ERROR, "Lower layer state is going backwards from ours");
+    TL_SET_STATE(TS_ERROR);
+    return;
+  }
+
+  switch (state) {
+    case TS_NONE:
+      MOZ_ASSERT(false);  // Can't happen
+      break;
+
+    case TS_INIT:
+      MOZ_MTLOG(ML_ERROR,
+                LAYER_INFO << "State change of lower layer to INIT forbidden");
+      TL_SET_STATE(TS_ERROR);
+      break;
+
+    case TS_CONNECTING:
+      MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Lower layer is connecting.");
+      break;
+
+    case TS_OPEN:
+      MOZ_MTLOG(ML_ERROR,
+                LAYER_INFO << "Lower layer is now open; starting TLS");
+      // Async, since the ICE layer might need to send a STUN response, and we
+      // don't want the handshake to start until that is sent.
+      TL_SET_STATE(TS_CONNECTING);
+      timer_->Cancel();
+      timer_->SetTarget(target_);
+      timer_->InitWithFuncCallback(TimerCallback,
+                                   this,
+                                   0,
+                                   nsITimer::TYPE_ONE_SHOT);
+      break;
+
+    case TS_CLOSED:
+      MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Lower layer is now closed");
+      TL_SET_STATE(TS_CLOSED);
+      break;
+
+    case TS_ERROR:
+      MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Lower layer experienced an error");
+      TL_SET_STATE(TS_ERROR);
+      break;
+  }
+}
+
+void TransportLayerDtls::Handshake() {
+  // Clear the retransmit timer
+  timer_->Cancel();
+
+  SECStatus rv = SSL_ForceHandshake(ssl_fd_.get());
+
+  if (rv == SECSuccess) {
+    MOZ_MTLOG(ML_NOTICE,
+              LAYER_INFO << "****** SSL handshake completed ******");
+    if (!cert_ok_) {
+      MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Certificate check never occurred");
+      TL_SET_STATE(TS_ERROR);
+      return;
+    }
+    if (!CheckAlpn()) {
+      // Despite connecting, the connection doesn't have a valid ALPN label.
+      // Forcibly close the connection so that the peer isn't left hanging
+      // (assuming the close_notify isn't dropped).
+      ssl_fd_ = nullptr;
+      TL_SET_STATE(TS_ERROR);
+      return;
+    }
+
+    TL_SET_STATE(TS_OPEN);
+  } else {
+    int32_t err = PR_GetError();
+    switch(err) {
+      case SSL_ERROR_RX_MALFORMED_HANDSHAKE:
+        MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Malformed DTLS message; ignoring");
+        // If this were TLS (and not DTLS), this would be fatal, but
+        // here we're required to ignore bad messages, so fall through
+        MOZ_FALLTHROUGH;
+      case PR_WOULD_BLOCK_ERROR:
+        MOZ_MTLOG(ML_NOTICE, LAYER_INFO << "Handshake would have blocked");
+        PRIntervalTime timeout;
+        rv = DTLS_GetHandshakeTimeout(ssl_fd_.get(), &timeout);
+        if (rv == SECSuccess) {
+          uint32_t timeout_ms = PR_IntervalToMilliseconds(timeout);
+
+          MOZ_MTLOG(ML_DEBUG,
+                    LAYER_INFO << "Setting DTLS timeout to " << timeout_ms);
+          timer_->SetTarget(target_);
+          timer_->InitWithFuncCallback(TimerCallback,
+                                       this, timeout_ms,
+                                       nsITimer::TYPE_ONE_SHOT);
+        }
+        break;
+      default:
+        const char *err_msg = PR_ErrorToName(err);
+        MOZ_MTLOG(ML_ERROR, LAYER_INFO << "DTLS handshake error " << err << " ("
+                  << err_msg << ")");
+        TL_SET_STATE(TS_ERROR);
+        break;
+    }
+  }
+}
+
+// Checks if ALPN was negotiated correctly and returns false if it wasn't.
+// After this returns successfully, alpn_ will be set to the negotiated
+// protocol.
+bool TransportLayerDtls::CheckAlpn() {
+  if (alpn_allowed_.empty()) {
+    return true;
+  }
+
+  SSLNextProtoState alpnState;
+  char chosenAlpn[MAX_ALPN_LENGTH];
+  unsigned int chosenAlpnLen;
+  SECStatus rv = SSL_GetNextProto(ssl_fd_.get(), &alpnState,
+                                  reinterpret_cast<unsigned char*>(chosenAlpn),
+                                  &chosenAlpnLen, sizeof(chosenAlpn));
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, LAYER_INFO << "ALPN error");
+    return false;
+  }
+  switch (alpnState) {
+    case SSL_NEXT_PROTO_SELECTED:
+    case SSL_NEXT_PROTO_NEGOTIATED:
+      break; // OK
+
+    case SSL_NEXT_PROTO_NO_SUPPORT:
+      MOZ_MTLOG(ML_NOTICE, LAYER_INFO << "ALPN not negotiated, "
+                << (alpn_default_.empty() ? "failing" : "selecting default"));
+      alpn_ = alpn_default_;
+      return !alpn_.empty();
+
+    case SSL_NEXT_PROTO_NO_OVERLAP:
+      // This only happens if there is a custom NPN/ALPN callback installed and
+      // that callback doesn't properly handle ALPN.
+      MOZ_MTLOG(ML_ERROR, LAYER_INFO << "error in ALPN selection callback");
+      return false;
+
+    case SSL_NEXT_PROTO_EARLY_VALUE:
+      MOZ_CRASH("Unexpected 0-RTT ALPN value");
+      return false;
+  }
+
+  // Warning: NSS won't null terminate the ALPN string for us.
+  std::string chosen(chosenAlpn, chosenAlpnLen);
+  MOZ_MTLOG(ML_NOTICE, LAYER_INFO << "Selected ALPN string: " << chosen);
+  if (alpn_allowed_.find(chosen) == alpn_allowed_.end()) {
+    // Maybe our peer chose a protocol we didn't offer (when we are client), or
+    // something is seriously wrong.
+    std::ostringstream ss;
+    for (auto i = alpn_allowed_.begin(); i != alpn_allowed_.end(); ++i) {
+      ss << (i == alpn_allowed_.begin() ? " '" : ", '") << *i << "'";
+    }
+    MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Bad ALPN string: '" << chosen
+              << "'; permitted:" << ss.str());
+    return false;
+  }
+  alpn_ = chosen;
+  return true;
+}
+
+
+void TransportLayerDtls::PacketReceived(TransportLayer* layer,
+                                        const unsigned char *data,
+                                        size_t len) {
+  CheckThread();
+  MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "PacketReceived(" << len << ")");
+
+  if (state_ != TS_CONNECTING && state_ != TS_OPEN) {
+    MOZ_MTLOG(ML_DEBUG,
+              LAYER_INFO << "Discarding packet in inappropriate state");
+    return;
+  }
+
+  // not DTLS per RFC 7983
+  if (data[0] < 20 || data[0] > 63) {
+    return;
+  }
+
+  nspr_io_adapter_->PacketReceived(data, len);
+
+  // If we're still connecting, try to handshake
+  if (state_ == TS_CONNECTING) {
+    Handshake();
+  }
+
+  // Now try a recv if we're open, since there might be data left
+  if (state_ == TS_OPEN) {
+    // nICEr uses a 9216 bytes buffer to allow support for jumbo frames
+    unsigned char buf[9216];
+    int32_t rv;
+    // One packet might contain several DTLS packets
+    do {
+      rv = PR_Recv(ssl_fd_.get(), buf, sizeof(buf), 0, PR_INTERVAL_NO_WAIT);
+      if (rv > 0) {
+        // We have data
+        MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Read " << rv << " bytes from NSS");
+        SignalPacketReceived(this, buf, rv);
+      } else if (rv == 0) {
+        TL_SET_STATE(TS_CLOSED);
+      } else {
+        int32_t err = PR_GetError();
+
+        if (err == PR_WOULD_BLOCK_ERROR) {
+          // This gets ignored
+          MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Receive would have blocked");
+        } else {
+          MOZ_MTLOG(ML_NOTICE, LAYER_INFO << "NSS Error " << err);
+          TL_SET_STATE(TS_ERROR);
+        }
+      }
+    } while (rv > 0);
+  }
+}
+
+TransportResult TransportLayerDtls::SendPacket(const unsigned char *data,
+                                               size_t len) {
+  CheckThread();
+  if (state_ != TS_OPEN) {
+    MOZ_MTLOG(ML_ERROR, LAYER_INFO << "Can't call SendPacket() in state "
+              << state_);
+    return TE_ERROR;
+  }
+
+  int32_t rv = PR_Send(ssl_fd_.get(), data, len, 0, PR_INTERVAL_NO_WAIT);
+
+  if (rv > 0) {
+    // We have data
+    MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Wrote " << rv << " bytes to SSL Layer");
+    return rv;
+  }
+
+  if (rv == 0) {
+    TL_SET_STATE(TS_CLOSED);
+    return 0;
+  }
+
+  int32_t err = PR_GetError();
+
+  if (err == PR_WOULD_BLOCK_ERROR) {
+    // This gets ignored
+    MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Send would have blocked");
+    return TE_WOULDBLOCK;
+  }
+
+  MOZ_MTLOG(ML_NOTICE, LAYER_INFO << "NSS Error " << err);
+  TL_SET_STATE(TS_ERROR);
+  return TE_ERROR;
+}
+
+SECStatus TransportLayerDtls::GetClientAuthDataHook(void *arg, PRFileDesc *fd,
+                                                    CERTDistNames *caNames,
+                                                    CERTCertificate **pRetCert,
+                                                    SECKEYPrivateKey **pRetKey) {
+  MOZ_MTLOG(ML_DEBUG, "Server requested client auth");
+
+  TransportLayerDtls *stream = reinterpret_cast<TransportLayerDtls *>(arg);
+  stream->CheckThread();
+
+  if (!stream->identity_) {
+    MOZ_MTLOG(ML_ERROR, "No identity available");
+    PR_SetError(SSL_ERROR_NO_CERTIFICATE, 0);
+    return SECFailure;
+  }
+
+  *pRetCert = CERT_DupCertificate(stream->identity_->cert().get());
+  if (!*pRetCert) {
+    PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
+    return SECFailure;
+  }
+
+  *pRetKey = SECKEY_CopyPrivateKey(stream->identity_->privkey());
+  if (!*pRetKey) {
+    CERT_DestroyCertificate(*pRetCert);
+    *pRetCert = nullptr;
+    PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
+    return SECFailure;
+  }
+
+  return SECSuccess;
+}
+
+nsresult TransportLayerDtls::SetSrtpCiphers(std::vector<uint16_t> ciphers) {
+  // TODO: We should check these
+  srtp_ciphers_ = ciphers;
+
+  return NS_OK;
+}
+
+nsresult TransportLayerDtls::GetSrtpCipher(uint16_t *cipher) const {
+  CheckThread();
+  if (state_ != TS_OPEN) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  SECStatus rv = SSL_GetSRTPCipher(ssl_fd_.get(), cipher);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_DEBUG, "No SRTP cipher negotiated");
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult TransportLayerDtls::ExportKeyingMaterial(const std::string& label,
+                                                  bool use_context,
+                                                  const std::string& context,
+                                                  unsigned char *out,
+                                                  unsigned int outlen) {
+  CheckThread();
+  if (state_ != TS_OPEN) {
+    MOZ_ASSERT(false, "Transport must be open for ExportKeyingMaterial");
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  SECStatus rv = SSL_ExportKeyingMaterial(ssl_fd_.get(),
+                                          label.c_str(),
+                                          label.size(),
+                                          use_context,
+                                          reinterpret_cast<const unsigned char *>(
+                                              context.c_str()),
+                                          context.size(),
+                                          out,
+                                          outlen);
+  if (rv != SECSuccess) {
+    MOZ_MTLOG(ML_ERROR, "Couldn't export SSL keying material");
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+SECStatus TransportLayerDtls::AuthCertificateHook(void *arg,
+                                                  PRFileDesc *fd,
+                                                  PRBool checksig,
+                                                  PRBool isServer) {
+  TransportLayerDtls *stream = reinterpret_cast<TransportLayerDtls *>(arg);
+  stream->CheckThread();
+  return stream->AuthCertificateHook(fd, checksig, isServer);
+}
+
+SECStatus
+TransportLayerDtls::CheckDigest(const RefPtr<VerificationDigest>& digest,
+                                UniqueCERTCertificate& peer_cert) const {
+  unsigned char computed_digest[kMaxDigestLength];
+  size_t computed_digest_len;
+
+  MOZ_MTLOG(ML_DEBUG, LAYER_INFO << "Checking digest, algorithm="
+            << digest->algorithm_);
+  nsresult res =
+      DtlsIdentity::ComputeFingerprint(peer_cert,
+                                       digest->algorithm_,
+                                       computed_digest,
+                                       sizeof(computed_digest),
+                                       &computed_digest_len);
+  if (NS_FAILED(res)) {
+    MOZ_MTLOG(ML_ERROR, "Could not compute peer fingerprint for digest " <<
+              digest->algorithm_);
+    // Go to end
+    PR_SetError(SSL_ERROR_BAD_CERTIFICATE, 0);
+    return SECFailure;
+  }
+
+  if (computed_digest_len != digest->len_) {
+    MOZ_MTLOG(ML_ERROR, "Digest is wrong length " << digest->len_ <<
+              " should be " << computed_digest_len << " for algorithm " <<
+              digest->algorithm_);
+    PR_SetError(SSL_ERROR_BAD_CERTIFICATE, 0);
+    return SECFailure;
+  }
+
+  if (memcmp(digest->value_, computed_digest, computed_digest_len) != 0) {
+    MOZ_MTLOG(ML_ERROR, "Digest does not match");
+    PR_SetError(SSL_ERROR_BAD_CERTIFICATE, 0);
+    return SECFailure;
+  }
+
+  return SECSuccess;
+}
+
+
+SECStatus TransportLayerDtls::AuthCertificateHook(PRFileDesc *fd,
+                                                  PRBool checksig,
+                                                  PRBool isServer) {
+  CheckThread();
+  UniqueCERTCertificate peer_cert(SSL_PeerCertificate(fd));
+
+  // We are not set up to take this being called multiple
+  // times. Change this if we ever add renegotiation.
+  MOZ_ASSERT(!auth_hook_called_);
+  if (auth_hook_called_) {
+    PR_SetError(PR_UNKNOWN_ERROR, 0);
+    return SECFailure;
+  }
+  auth_hook_called_ = true;
+
+  MOZ_ASSERT(verification_mode_ != VERIFY_UNSET);
+
+  switch (verification_mode_) {
+    case VERIFY_UNSET:
+      // Break out to error exit
+      PR_SetError(PR_UNKNOWN_ERROR, 0);
+      break;
+
+    case VERIFY_ALLOW_ALL:
+      cert_ok_ = true;
+      return SECSuccess;
+
+    case VERIFY_DIGEST:
+      {
+        MOZ_ASSERT(digests_.size() != 0);
+        // Check all the provided digests
+
+        // Checking functions call PR_SetError()
+        SECStatus rv = SECFailure;
+        for (size_t i = 0; i < digests_.size(); i++) {
+          RefPtr<VerificationDigest> digest = digests_[i];
+          rv = CheckDigest(digest, peer_cert);
+
+          // Matches a digest, we are good to go
+          if (rv == SECSuccess) {
+            cert_ok_ = true;
+            return SECSuccess;
+          }
+        }
+      }
+      break;
+    default:
+      MOZ_CRASH();  // Can't happen
+  }
+
+  return SECFailure;
+}
+
+void TransportLayerDtls::TimerCallback(nsITimer *timer, void *arg) {
+  TransportLayerDtls *dtls = reinterpret_cast<TransportLayerDtls *>(arg);
+
+  MOZ_MTLOG(ML_DEBUG, "DTLS timer expired");
+
+  dtls->Handshake();
+}
+
+}  // close namespace