Repo created

TMessagesProj/jni/voip/webrtc/pc/dtls_srtp_transport.cc

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+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "pc/dtls_srtp_transport.h"
+
+#include <string.h>
+
+#include <string>
+#include <utility>
+
+#include "api/dtls_transport_interface.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/ssl_stream_adapter.h"
+
+namespace {
+// Value specified in RFC 5764.
+static const char kDtlsSrtpExporterLabel[] = "EXTRACTOR-dtls_srtp";
+}  // namespace
+
+namespace webrtc {
+
+DtlsSrtpTransport::DtlsSrtpTransport(bool rtcp_mux_enabled,
+                                     const FieldTrialsView& field_trials)
+    : SrtpTransport(rtcp_mux_enabled, field_trials) {}
+
+void DtlsSrtpTransport::SetDtlsTransports(
+    cricket::DtlsTransportInternal* rtp_dtls_transport,
+    cricket::DtlsTransportInternal* rtcp_dtls_transport) {
+  // Transport names should be the same.
+  if (rtp_dtls_transport && rtcp_dtls_transport) {
+    RTC_DCHECK(rtp_dtls_transport->transport_name() ==
+               rtcp_dtls_transport->transport_name());
+  }
+
+  // When using DTLS-SRTP, we must reset the SrtpTransport every time the
+  // DtlsTransport changes and wait until the DTLS handshake is complete to set
+  // the newly negotiated parameters.
+  // If `active_reset_srtp_params_` is true, intentionally reset the SRTP
+  // parameter even though the DtlsTransport may not change.
+  if (IsSrtpActive() && (rtp_dtls_transport != rtp_dtls_transport_ ||
+                         active_reset_srtp_params_)) {
+    ResetParams();
+  }
+
+  const std::string transport_name =
+      rtp_dtls_transport ? rtp_dtls_transport->transport_name() : "null";
+
+  if (rtcp_dtls_transport && rtcp_dtls_transport != rtcp_dtls_transport_) {
+    // This would only be possible if using BUNDLE but not rtcp-mux, which isn't
+    // allowed according to the BUNDLE spec.
+    RTC_CHECK(!(IsSrtpActive()))
+        << "Setting RTCP for DTLS/SRTP after the DTLS is active "
+           "should never happen.";
+  }
+
+  if (rtcp_dtls_transport) {
+    RTC_LOG(LS_INFO) << "Setting RTCP Transport on " << transport_name
+                     << " transport " << rtcp_dtls_transport;
+  }
+  SetRtcpDtlsTransport(rtcp_dtls_transport);
+  SetRtcpPacketTransport(rtcp_dtls_transport);
+
+  RTC_LOG(LS_INFO) << "Setting RTP Transport on " << transport_name
+                   << " transport " << rtp_dtls_transport;
+  SetRtpDtlsTransport(rtp_dtls_transport);
+  SetRtpPacketTransport(rtp_dtls_transport);
+
+  MaybeSetupDtlsSrtp();
+}
+
+void DtlsSrtpTransport::SetRtcpMuxEnabled(bool enable) {
+  SrtpTransport::SetRtcpMuxEnabled(enable);
+  if (enable) {
+    MaybeSetupDtlsSrtp();
+  }
+}
+
+void DtlsSrtpTransport::UpdateSendEncryptedHeaderExtensionIds(
+    const std::vector<int>& send_extension_ids) {
+  if (send_extension_ids_ == send_extension_ids) {
+    return;
+  }
+  send_extension_ids_.emplace(send_extension_ids);
+  if (DtlsHandshakeCompleted()) {
+    // Reset the crypto parameters to update the send extension IDs.
+    SetupRtpDtlsSrtp();
+  }
+}
+
+void DtlsSrtpTransport::UpdateRecvEncryptedHeaderExtensionIds(
+    const std::vector<int>& recv_extension_ids) {
+  if (recv_extension_ids_ == recv_extension_ids) {
+    return;
+  }
+  recv_extension_ids_.emplace(recv_extension_ids);
+  if (DtlsHandshakeCompleted()) {
+    // Reset the crypto parameters to update the receive extension IDs.
+    SetupRtpDtlsSrtp();
+  }
+}
+
+bool DtlsSrtpTransport::IsDtlsActive() {
+  auto rtcp_dtls_transport =
+      rtcp_mux_enabled() ? nullptr : rtcp_dtls_transport_;
+  return (rtp_dtls_transport_ && rtp_dtls_transport_->IsDtlsActive() &&
+          (!rtcp_dtls_transport || rtcp_dtls_transport->IsDtlsActive()));
+}
+
+bool DtlsSrtpTransport::IsDtlsConnected() {
+  auto rtcp_dtls_transport =
+      rtcp_mux_enabled() ? nullptr : rtcp_dtls_transport_;
+  return (rtp_dtls_transport_ &&
+          rtp_dtls_transport_->dtls_state() == DtlsTransportState::kConnected &&
+          (!rtcp_dtls_transport || rtcp_dtls_transport->dtls_state() ==
+                                       DtlsTransportState::kConnected));
+}
+
+bool DtlsSrtpTransport::IsDtlsWritable() {
+  auto rtcp_packet_transport =
+      rtcp_mux_enabled() ? nullptr : rtcp_dtls_transport_;
+  return rtp_dtls_transport_ && rtp_dtls_transport_->writable() &&
+         (!rtcp_packet_transport || rtcp_packet_transport->writable());
+}
+
+bool DtlsSrtpTransport::DtlsHandshakeCompleted() {
+  return IsDtlsActive() && IsDtlsConnected();
+}
+
+void DtlsSrtpTransport::MaybeSetupDtlsSrtp() {
+  if (IsSrtpActive() || !IsDtlsWritable()) {
+    return;
+  }
+
+  SetupRtpDtlsSrtp();
+
+  if (!rtcp_mux_enabled() && rtcp_dtls_transport_) {
+    SetupRtcpDtlsSrtp();
+  }
+}
+
+void DtlsSrtpTransport::SetupRtpDtlsSrtp() {
+  // Use an empty encrypted header extension ID vector if not set. This could
+  // happen when the DTLS handshake is completed before processing the
+  // Offer/Answer which contains the encrypted header extension IDs.
+  std::vector<int> send_extension_ids;
+  std::vector<int> recv_extension_ids;
+  if (send_extension_ids_) {
+    send_extension_ids = *send_extension_ids_;
+  }
+  if (recv_extension_ids_) {
+    recv_extension_ids = *recv_extension_ids_;
+  }
+
+  int selected_crypto_suite;
+  rtc::ZeroOnFreeBuffer<unsigned char> send_key;
+  rtc::ZeroOnFreeBuffer<unsigned char> recv_key;
+
+  if (!ExtractParams(rtp_dtls_transport_, &selected_crypto_suite, &send_key,
+                     &recv_key) ||
+      !SetRtpParams(selected_crypto_suite, &send_key[0],
+                    static_cast<int>(send_key.size()), send_extension_ids,
+                    selected_crypto_suite, &recv_key[0],
+                    static_cast<int>(recv_key.size()), recv_extension_ids)) {
+    RTC_LOG(LS_WARNING) << "DTLS-SRTP key installation for RTP failed";
+  }
+}
+
+void DtlsSrtpTransport::SetupRtcpDtlsSrtp() {
+  // Return if the DTLS-SRTP is active because the encrypted header extension
+  // IDs don't need to be updated for RTCP and the crypto params don't need to
+  // be reset.
+  if (IsSrtpActive()) {
+    return;
+  }
+
+  std::vector<int> send_extension_ids;
+  std::vector<int> recv_extension_ids;
+  if (send_extension_ids_) {
+    send_extension_ids = *send_extension_ids_;
+  }
+  if (recv_extension_ids_) {
+    recv_extension_ids = *recv_extension_ids_;
+  }
+
+  int selected_crypto_suite;
+  rtc::ZeroOnFreeBuffer<unsigned char> rtcp_send_key;
+  rtc::ZeroOnFreeBuffer<unsigned char> rtcp_recv_key;
+  if (!ExtractParams(rtcp_dtls_transport_, &selected_crypto_suite,
+                     &rtcp_send_key, &rtcp_recv_key) ||
+      !SetRtcpParams(selected_crypto_suite, &rtcp_send_key[0],
+                     static_cast<int>(rtcp_send_key.size()), send_extension_ids,
+                     selected_crypto_suite, &rtcp_recv_key[0],
+                     static_cast<int>(rtcp_recv_key.size()),
+                     recv_extension_ids)) {
+    RTC_LOG(LS_WARNING) << "DTLS-SRTP key installation for RTCP failed";
+  }
+}
+
+bool DtlsSrtpTransport::ExtractParams(
+    cricket::DtlsTransportInternal* dtls_transport,
+    int* selected_crypto_suite,
+    rtc::ZeroOnFreeBuffer<unsigned char>* send_key,
+    rtc::ZeroOnFreeBuffer<unsigned char>* recv_key) {
+  if (!dtls_transport || !dtls_transport->IsDtlsActive()) {
+    return false;
+  }
+
+  if (!dtls_transport->GetSrtpCryptoSuite(selected_crypto_suite)) {
+    RTC_LOG(LS_ERROR) << "No DTLS-SRTP selected crypto suite";
+    return false;
+  }
+
+  RTC_LOG(LS_INFO) << "Extracting keys from transport: "
+                   << dtls_transport->transport_name();
+
+  int key_len;
+  int salt_len;
+  if (!rtc::GetSrtpKeyAndSaltLengths((*selected_crypto_suite), &key_len,
+                                     &salt_len)) {
+    RTC_LOG(LS_ERROR) << "Unknown DTLS-SRTP crypto suite"
+                      << selected_crypto_suite;
+    return false;
+  }
+
+  // OK, we're now doing DTLS (RFC 5764)
+  rtc::ZeroOnFreeBuffer<unsigned char> dtls_buffer(key_len * 2 + salt_len * 2);
+
+  // RFC 5705 exporter using the RFC 5764 parameters
+  if (!dtls_transport->ExportKeyingMaterial(kDtlsSrtpExporterLabel, NULL, 0,
+                                            false, &dtls_buffer[0],
+                                            dtls_buffer.size())) {
+    RTC_LOG(LS_WARNING) << "DTLS-SRTP key export failed";
+    RTC_DCHECK_NOTREACHED();  // This should never happen
+    return false;
+  }
+
+  // Sync up the keys with the DTLS-SRTP interface
+  rtc::ZeroOnFreeBuffer<unsigned char> client_write_key(key_len + salt_len);
+  rtc::ZeroOnFreeBuffer<unsigned char> server_write_key(key_len + salt_len);
+  size_t offset = 0;
+  memcpy(&client_write_key[0], &dtls_buffer[offset], key_len);
+  offset += key_len;
+  memcpy(&server_write_key[0], &dtls_buffer[offset], key_len);
+  offset += key_len;
+  memcpy(&client_write_key[key_len], &dtls_buffer[offset], salt_len);
+  offset += salt_len;
+  memcpy(&server_write_key[key_len], &dtls_buffer[offset], salt_len);
+
+  rtc::SSLRole role;
+  if (!dtls_transport->GetDtlsRole(&role)) {
+    RTC_LOG(LS_WARNING) << "Failed to get the DTLS role.";
+    return false;
+  }
+
+  if (role == rtc::SSL_SERVER) {
+    *send_key = std::move(server_write_key);
+    *recv_key = std::move(client_write_key);
+  } else {
+    *send_key = std::move(client_write_key);
+    *recv_key = std::move(server_write_key);
+  }
+  return true;
+}
+
+void DtlsSrtpTransport::SetDtlsTransport(
+    cricket::DtlsTransportInternal* new_dtls_transport,
+    cricket::DtlsTransportInternal** old_dtls_transport) {
+  if (*old_dtls_transport == new_dtls_transport) {
+    return;
+  }
+
+  if (*old_dtls_transport) {
+    (*old_dtls_transport)->UnsubscribeDtlsTransportState(this);
+  }
+
+  *old_dtls_transport = new_dtls_transport;
+
+  if (new_dtls_transport) {
+    new_dtls_transport->SubscribeDtlsTransportState(
+        this,
+        [this](cricket::DtlsTransportInternal* transport,
+               DtlsTransportState state) { OnDtlsState(transport, state); });
+  }
+}
+
+void DtlsSrtpTransport::SetRtpDtlsTransport(
+    cricket::DtlsTransportInternal* rtp_dtls_transport) {
+  SetDtlsTransport(rtp_dtls_transport, &rtp_dtls_transport_);
+}
+
+void DtlsSrtpTransport::SetRtcpDtlsTransport(
+    cricket::DtlsTransportInternal* rtcp_dtls_transport) {
+  SetDtlsTransport(rtcp_dtls_transport, &rtcp_dtls_transport_);
+}
+
+void DtlsSrtpTransport::OnDtlsState(cricket::DtlsTransportInternal* transport,
+                                    DtlsTransportState state) {
+  RTC_DCHECK(transport == rtp_dtls_transport_ ||
+             transport == rtcp_dtls_transport_);
+
+  if (on_dtls_state_change_) {
+    on_dtls_state_change_();
+  }
+
+  if (state != DtlsTransportState::kConnected) {
+    ResetParams();
+    return;
+  }
+
+  MaybeSetupDtlsSrtp();
+}
+
+void DtlsSrtpTransport::OnWritableState(
+    rtc::PacketTransportInternal* packet_transport) {
+  MaybeSetupDtlsSrtp();
+}
+
+void DtlsSrtpTransport::SetOnDtlsStateChange(
+    std::function<void(void)> callback) {
+  on_dtls_state_change_ = std::move(callback);
+}
+}  // namespace webrtc