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source: webrtc/talk/p2p/base/transportdescriptionfactory.cc @ 0:4bda6873e34c

pub_scrub_3792 tip
Last change on this file since 0:4bda6873e34c was 0:4bda6873e34c, checked in by Michael Prittie <mprittie@…>, 6 years ago

Scrubbed password for publication.

File size: 6.9 KB
Line 
1/*
2 * libjingle
3 * Copyright 2012 Google Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include "talk/p2p/base/transportdescriptionfactory.h"
29
30#include "talk/base/helpers.h"
31#include "talk/base/logging.h"
32#include "talk/base/messagedigest.h"
33#include "talk/base/scoped_ptr.h"
34#include "talk/base/sslfingerprint.h"
35#include "talk/p2p/base/transportdescription.h"
36
37namespace cricket {
38
39static TransportProtocol kDefaultProtocol = ICEPROTO_GOOGLE;
40
41TransportDescriptionFactory::TransportDescriptionFactory()
42    : protocol_(kDefaultProtocol),
43      secure_(SEC_DISABLED),
44      identity_(NULL) {
45}
46
47TransportDescription* TransportDescriptionFactory::CreateOffer(
48    const TransportOptions& options,
49    const TransportDescription* current_description) const {
50  talk_base::scoped_ptr<TransportDescription> desc(new TransportDescription());
51
52  // Set the transport type depending on the selected protocol.
53  if (protocol_ == ICEPROTO_RFC5245) {
54    desc->transport_type = NS_JINGLE_ICE_UDP;
55  } else if (protocol_ == ICEPROTO_HYBRID) {
56    desc->transport_type = NS_JINGLE_ICE_UDP;
57    desc->AddOption(ICE_OPTION_GICE);
58  } else if (protocol_ == ICEPROTO_GOOGLE) {
59    desc->transport_type = NS_GINGLE_P2P;
60  }
61
62  // Generate the ICE credentials if we don't already have them.
63  if (!current_description || options.ice_restart) {
64    desc->ice_ufrag = talk_base::CreateRandomString(ICE_UFRAG_LENGTH);
65    desc->ice_pwd = talk_base::CreateRandomString(ICE_PWD_LENGTH);
66  } else {
67    desc->ice_ufrag = current_description->ice_ufrag;
68    desc->ice_pwd = current_description->ice_pwd;
69  }
70
71  // If we are trying to establish a secure transport, add a fingerprint.
72  if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
73    // Fail if we can't create the fingerprint.
74    // If we are the initiator set role to "actpass".
75    if (!SetSecurityInfo(desc.get(), CONNECTIONROLE_ACTPASS)) {
76      return NULL;
77    }
78  }
79
80  return desc.release();
81}
82
83TransportDescription* TransportDescriptionFactory::CreateAnswer(
84    const TransportDescription* offer,
85    const TransportOptions& options,
86    const TransportDescription* current_description) const {
87  // A NULL offer is treated as a GICE transport description.
88  // TODO(juberti): Figure out why we get NULL offers, and fix this upstream.
89  talk_base::scoped_ptr<TransportDescription> desc(new TransportDescription());
90
91  // Figure out which ICE variant to negotiate; prefer RFC 5245 ICE, but fall
92  // back to G-ICE if needed. Note that we never create a hybrid answer, since
93  // we know what the other side can support already.
94  if (offer && offer->transport_type == NS_JINGLE_ICE_UDP &&
95      (protocol_ == ICEPROTO_RFC5245 || protocol_ == ICEPROTO_HYBRID)) {
96    // Offer is ICE or hybrid, we support ICE or hybrid: use ICE.
97    desc->transport_type = NS_JINGLE_ICE_UDP;
98  } else if (offer && offer->transport_type == NS_JINGLE_ICE_UDP &&
99             offer->HasOption(ICE_OPTION_GICE) &&
100             protocol_ == ICEPROTO_GOOGLE) {
101    desc->transport_type = NS_GINGLE_P2P;
102    // Offer is hybrid, we support GICE: use GICE.
103  } else if ((!offer || offer->transport_type == NS_GINGLE_P2P) &&
104             (protocol_ == ICEPROTO_HYBRID || protocol_ == ICEPROTO_GOOGLE)) {
105    // Offer is GICE, we support hybrid or GICE: use GICE.
106    desc->transport_type = NS_GINGLE_P2P;
107  } else {
108    // Mismatch.
109    LOG(LS_WARNING) << "Failed to create TransportDescription answer "
110                       "because of incompatible transport types";
111    return NULL;
112  }
113
114  // Generate the ICE credentials if we don't already have them or ice is
115  // being restarted.
116  if (!current_description || options.ice_restart) {
117    desc->ice_ufrag = talk_base::CreateRandomString(ICE_UFRAG_LENGTH);
118    desc->ice_pwd = talk_base::CreateRandomString(ICE_PWD_LENGTH);
119  } else {
120    desc->ice_ufrag = current_description->ice_ufrag;
121    desc->ice_pwd = current_description->ice_pwd;
122  }
123
124  // Negotiate security params.
125  if (offer && offer->identity_fingerprint.get()) {
126    // The offer supports DTLS, so answer with DTLS, as long as we support it.
127    if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
128      // Fail if we can't create the fingerprint.
129      // Setting DTLS role to active.
130      ConnectionRole role = (options.prefer_passive_role) ?
131          CONNECTIONROLE_PASSIVE : CONNECTIONROLE_ACTIVE;
132
133      if (!SetSecurityInfo(desc.get(), role)) {
134        return NULL;
135      }
136    }
137  } else if (secure_ == SEC_REQUIRED) {
138    // We require DTLS, but the other side didn't offer it. Fail.
139    LOG(LS_WARNING) << "Failed to create TransportDescription answer "
140                       "because of incompatible security settings";
141    return NULL;
142  }
143
144  return desc.release();
145}
146
147bool TransportDescriptionFactory::SetSecurityInfo(
148    TransportDescription* desc, ConnectionRole role) const {
149  if (!identity_) {
150    LOG(LS_ERROR) << "Cannot create identity digest with no identity";
151    return false;
152  }
153
154  // This digest algorithm is used to produce the a=fingerprint lines in SDP.
155  // RFC 4572 Section 5 requires that those lines use the same hash function as
156  // the certificate's signature.
157  std::string digest_alg;
158  if (!identity_->certificate().GetSignatureDigestAlgorithm(&digest_alg)) {
159    LOG(LS_ERROR) << "Failed to retrieve the certificate's digest algorithm";
160    return false;
161  }
162
163  desc->identity_fingerprint.reset(
164      talk_base::SSLFingerprint::Create(digest_alg, identity_));
165  if (!desc->identity_fingerprint.get()) {
166    LOG(LS_ERROR) << "Failed to create identity fingerprint, alg="
167                  << digest_alg;
168    return false;
169  }
170
171  // Assign security role.
172  desc->connection_role = role;
173  return true;
174}
175
176}  // namespace cricket
177
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