aboutsummaryrefslogtreecommitdiff
path: root/p2p/base/transport_description_factory.cc
blob: 5cce2ac09d659eed1b3f2ff82f77dd616731fa66 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
/*
 *  Copyright 2012 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 "p2p/base/transport_description_factory.h"

#include <stddef.h>

#include <memory>
#include <string>

#include "p2p/base/transport_description.h"
#include "rtc_base/logging.h"
#include "rtc_base/ssl_fingerprint.h"

namespace cricket {

TransportDescriptionFactory::TransportDescriptionFactory()
    : secure_(SEC_DISABLED) {}

TransportDescriptionFactory::~TransportDescriptionFactory() = default;

std::unique_ptr<TransportDescription> TransportDescriptionFactory::CreateOffer(
    const TransportOptions& options,
    const TransportDescription* current_description,
    IceCredentialsIterator* ice_credentials) const {
  auto desc = std::make_unique<TransportDescription>();

  // Generate the ICE credentials if we don't already have them.
  if (!current_description || options.ice_restart) {
    IceParameters credentials = ice_credentials->GetIceCredentials();
    desc->ice_ufrag = credentials.ufrag;
    desc->ice_pwd = credentials.pwd;
  } else {
    desc->ice_ufrag = current_description->ice_ufrag;
    desc->ice_pwd = current_description->ice_pwd;
  }
  desc->AddOption(ICE_OPTION_TRICKLE);
  if (options.enable_ice_renomination) {
    desc->AddOption(ICE_OPTION_RENOMINATION);
  }

  // If we are trying to establish a secure transport, add a fingerprint.
  if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
    // Fail if we can't create the fingerprint.
    // If we are the initiator set role to "actpass".
    if (!SetSecurityInfo(desc.get(), CONNECTIONROLE_ACTPASS)) {
      return NULL;
    }
  }

  return desc;
}

std::unique_ptr<TransportDescription> TransportDescriptionFactory::CreateAnswer(
    const TransportDescription* offer,
    const TransportOptions& options,
    bool require_transport_attributes,
    const TransportDescription* current_description,
    IceCredentialsIterator* ice_credentials) const {
  // TODO(juberti): Figure out why we get NULL offers, and fix this upstream.
  if (!offer) {
    RTC_LOG(LS_WARNING) << "Failed to create TransportDescription answer "
                           "because offer is NULL";
    return NULL;
  }

  auto desc = std::make_unique<TransportDescription>();
  // Generate the ICE credentials if we don't already have them or ice is
  // being restarted.
  if (!current_description || options.ice_restart) {
    IceParameters credentials = ice_credentials->GetIceCredentials();
    desc->ice_ufrag = credentials.ufrag;
    desc->ice_pwd = credentials.pwd;
  } else {
    desc->ice_ufrag = current_description->ice_ufrag;
    desc->ice_pwd = current_description->ice_pwd;
  }
  desc->AddOption(ICE_OPTION_TRICKLE);
  if (options.enable_ice_renomination) {
    desc->AddOption(ICE_OPTION_RENOMINATION);
  }

  // Negotiate security params.
  if (offer && offer->identity_fingerprint.get()) {
    // The offer supports DTLS, so answer with DTLS, as long as we support it.
    if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
      // Fail if we can't create the fingerprint.
      // Setting DTLS role to active.
      ConnectionRole role = (options.prefer_passive_role)
                                ? CONNECTIONROLE_PASSIVE
                                : CONNECTIONROLE_ACTIVE;

      if (!SetSecurityInfo(desc.get(), role)) {
        return NULL;
      }
    }
  } else if (require_transport_attributes && secure_ == SEC_REQUIRED) {
    // We require DTLS, but the other side didn't offer it. Fail.
    RTC_LOG(LS_WARNING) << "Failed to create TransportDescription answer "
                           "because of incompatible security settings";
    return NULL;
  }

  return desc;
}

bool TransportDescriptionFactory::SetSecurityInfo(TransportDescription* desc,
                                                  ConnectionRole role) const {
  if (!certificate_) {
    RTC_LOG(LS_ERROR) << "Cannot create identity digest with no certificate";
    return false;
  }

  // This digest algorithm is used to produce the a=fingerprint lines in SDP.
  // RFC 4572 Section 5 requires that those lines use the same hash function as
  // the certificate's signature, which is what CreateFromCertificate does.
  desc->identity_fingerprint =
      rtc::SSLFingerprint::CreateFromCertificate(*certificate_);
  if (!desc->identity_fingerprint) {
    return false;
  }

  // Assign security role.
  desc->connection_role = role;
  return true;
}

}  // namespace cricket