http_auth_handler_digest.cc revision 72a454cd3513ac24fbdd0e0cb9ad70b86a99b801 
1// Copyright (c) 2010 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "net/http/http_auth_handler_digest.h"
6
7#include <string>
8
9#include "base/logging.h"
10#include "base/md5.h"
11#include "base/rand_util.h"
12#include "base/string_util.h"
13#include "base/stringprintf.h"
14#include "base/utf_string_conversions.h"
15#include "net/base/net_errors.h"
16#include "net/base/net_util.h"
17#include "net/http/http_auth.h"
18#include "net/http/http_request_info.h"
19#include "net/http/http_util.h"
20
21namespace net {
22
23// Digest authentication is specified in RFC 2617.
24// The expanded derivations are listed in the tables below.
25
26//==========+==========+==========================================+
27//    qop   |algorithm |               response                   |
28//==========+==========+==========================================+
29//    ?     |  ?, md5, | MD5(MD5(A1):nonce:MD5(A2))               |
30//          | md5-sess |                                          |
31//--------- +----------+------------------------------------------+
32//   auth,  |  ?, md5, | MD5(MD5(A1):nonce:nc:cnonce:qop:MD5(A2)) |
33// auth-int | md5-sess |                                          |
34//==========+==========+==========================================+
35//    qop   |algorithm |                  A1                      |
36//==========+==========+==========================================+
37//          | ?, md5   | user:realm:password                      |
38//----------+----------+------------------------------------------+
39//          | md5-sess | MD5(user:realm:password):nonce:cnonce    |
40//==========+==========+==========================================+
41//    qop   |algorithm |                  A2                      |
42//==========+==========+==========================================+
43//  ?, auth |          | req-method:req-uri                       |
44//----------+----------+------------------------------------------+
45// auth-int |          | req-method:req-uri:MD5(req-entity-body)  |
46//=====================+==========================================+
47
48HttpAuthHandlerDigest::NonceGenerator::NonceGenerator() {
49}
50
51HttpAuthHandlerDigest::NonceGenerator::~NonceGenerator() {
52}
53
54HttpAuthHandlerDigest::DynamicNonceGenerator::DynamicNonceGenerator() {
55}
56
57std::string HttpAuthHandlerDigest::DynamicNonceGenerator::GenerateNonce()
58    const {
59  // This is how mozilla generates their cnonce -- a 16 digit hex string.
60  static const char domain[] = "0123456789abcdef";
61  std::string cnonce;
62  cnonce.reserve(16);
63  for (int i = 0; i < 16; ++i)
64    cnonce.push_back(domain[base::RandInt(0, 15)]);
65  return cnonce;
66}
67
68HttpAuthHandlerDigest::FixedNonceGenerator::FixedNonceGenerator(
69    const std::string& nonce)
70    : nonce_(nonce) {
71}
72
73std::string HttpAuthHandlerDigest::FixedNonceGenerator::GenerateNonce() const {
74  return nonce_;
75}
76
77HttpAuthHandlerDigest::Factory::Factory()
78    : nonce_generator_(new DynamicNonceGenerator()) {
79}
80
81HttpAuthHandlerDigest::Factory::~Factory() {
82}
83
84void HttpAuthHandlerDigest::Factory::set_nonce_generator(
85    const NonceGenerator* nonce_generator) {
86  nonce_generator_.reset(nonce_generator);
87}
88
89int HttpAuthHandlerDigest::Factory::CreateAuthHandler(
90    HttpAuth::ChallengeTokenizer* challenge,
91    HttpAuth::Target target,
92    const GURL& origin,
93    CreateReason reason,
94    int digest_nonce_count,
95    const BoundNetLog& net_log,
96    scoped_ptr<HttpAuthHandler>* handler) {
97  // TODO(cbentzel): Move towards model of parsing in the factory
98  //                 method and only constructing when valid.
99  scoped_ptr<HttpAuthHandler> tmp_handler(
100      new HttpAuthHandlerDigest(digest_nonce_count, nonce_generator_.get()));
101  if (!tmp_handler->InitFromChallenge(challenge, target, origin, net_log))
102    return ERR_INVALID_RESPONSE;
103  handler->swap(tmp_handler);
104  return OK;
105}
106
107HttpAuth::AuthorizationResult HttpAuthHandlerDigest::HandleAnotherChallenge(
108    HttpAuth::ChallengeTokenizer* challenge) {
109  // Even though Digest is not connection based, a "second round" is parsed
110  // to differentiate between stale and rejected responses.
111  // Note that the state of the current handler is not mutated - this way if
112  // there is a rejection the realm hasn't changed.
113  if (!LowerCaseEqualsASCII(challenge->scheme(), "digest"))
114    return HttpAuth::AUTHORIZATION_RESULT_INVALID;
115
116  HttpUtil::NameValuePairsIterator parameters = challenge->param_pairs();
117
118  // Try to find the "stale" value.
119  while (parameters.GetNext()) {
120    if (!LowerCaseEqualsASCII(parameters.name(), "stale"))
121      continue;
122    if (LowerCaseEqualsASCII(parameters.value(), "true"))
123      return HttpAuth::AUTHORIZATION_RESULT_STALE;
124  }
125
126  return HttpAuth::AUTHORIZATION_RESULT_REJECT;
127}
128
129bool HttpAuthHandlerDigest::Init(HttpAuth::ChallengeTokenizer* challenge) {
130  return ParseChallenge(challenge);
131}
132
133int HttpAuthHandlerDigest::GenerateAuthTokenImpl(
134    const string16* username,
135    const string16* password,
136    const HttpRequestInfo* request,
137    CompletionCallback* callback,
138    std::string* auth_token) {
139  // Generate a random client nonce.
140  std::string cnonce = nonce_generator_->GenerateNonce();
141
142  // Extract the request method and path -- the meaning of 'path' is overloaded
143  // in certain cases, to be a hostname.
144  std::string method;
145  std::string path;
146  GetRequestMethodAndPath(request, &method, &path);
147
148  *auth_token = AssembleCredentials(method, path,
149                                    *username,
150                                    *password,
151                                    cnonce, nonce_count_);
152  return OK;
153}
154
155HttpAuthHandlerDigest::HttpAuthHandlerDigest(
156    int nonce_count, const NonceGenerator* nonce_generator)
157    : stale_(false),
158      algorithm_(ALGORITHM_UNSPECIFIED),
159      qop_(QOP_UNSPECIFIED),
160      nonce_count_(nonce_count),
161      nonce_generator_(nonce_generator) {
162  DCHECK(nonce_generator_);
163}
164
165HttpAuthHandlerDigest::~HttpAuthHandlerDigest() {
166}
167
168// The digest challenge header looks like:
169//   WWW-Authenticate: Digest
170//     [realm="<realm-value>"]
171//     nonce="<nonce-value>"
172//     [domain="<list-of-URIs>"]
173//     [opaque="<opaque-token-value>"]
174//     [stale="<true-or-false>"]
175//     [algorithm="<digest-algorithm>"]
176//     [qop="<list-of-qop-values>"]
177//     [<extension-directive>]
178//
179// Note that according to RFC 2617 (section 1.2) the realm is required.
180// However we allow it to be omitted, in which case it will default to the
181// empty string.
182//
183// This allowance is for better compatibility with webservers that fail to
184// send the realm (See http://crbug.com/20984 for an instance where a
185// webserver was not sending the realm with a BASIC challenge).
186bool HttpAuthHandlerDigest::ParseChallenge(
187    HttpAuth::ChallengeTokenizer* challenge) {
188  auth_scheme_ = HttpAuth::AUTH_SCHEME_DIGEST;
189  score_ = 2;
190  properties_ = ENCRYPTS_IDENTITY;
191
192  // Initialize to defaults.
193  stale_ = false;
194  algorithm_ = ALGORITHM_UNSPECIFIED;
195  qop_ = QOP_UNSPECIFIED;
196  realm_ = nonce_ = domain_ = opaque_ = std::string();
197
198  // FAIL -- Couldn't match auth-scheme.
199  if (!LowerCaseEqualsASCII(challenge->scheme(), "digest"))
200    return false;
201
202  HttpUtil::NameValuePairsIterator parameters = challenge->param_pairs();
203
204  // Loop through all the properties.
205  while (parameters.GetNext()) {
206    // FAIL -- couldn't parse a property.
207    if (!ParseChallengeProperty(parameters.name(),
208                                parameters.value()))
209      return false;
210  }
211
212  // Check if tokenizer failed.
213  if (!parameters.valid())
214    return false;
215
216  // Check that a minimum set of properties were provided.
217  if (nonce_.empty())
218    return false;
219
220  return true;
221}
222
223bool HttpAuthHandlerDigest::ParseChallengeProperty(const std::string& name,
224                                                   const std::string& value) {
225  if (LowerCaseEqualsASCII(name, "realm")) {
226    realm_ = value;
227  } else if (LowerCaseEqualsASCII(name, "nonce")) {
228    nonce_ = value;
229  } else if (LowerCaseEqualsASCII(name, "domain")) {
230    domain_ = value;
231  } else if (LowerCaseEqualsASCII(name, "opaque")) {
232    opaque_ = value;
233  } else if (LowerCaseEqualsASCII(name, "stale")) {
234    // Parse the stale boolean.
235    stale_ = LowerCaseEqualsASCII(value, "true");
236  } else if (LowerCaseEqualsASCII(name, "algorithm")) {
237    // Parse the algorithm.
238    if (LowerCaseEqualsASCII(value, "md5")) {
239      algorithm_ = ALGORITHM_MD5;
240    } else if (LowerCaseEqualsASCII(value, "md5-sess")) {
241      algorithm_ = ALGORITHM_MD5_SESS;
242    } else {
243      DVLOG(1) << "Unknown value of algorithm";
244      return false;  // FAIL -- unsupported value of algorithm.
245    }
246  } else if (LowerCaseEqualsASCII(name, "qop")) {
247    // Parse the comma separated list of qops.
248    // auth is the only supported qop, and all other values are ignored.
249    HttpUtil::ValuesIterator qop_values(value.begin(), value.end(), ',');
250    qop_ = QOP_UNSPECIFIED;
251    while (qop_values.GetNext()) {
252      if (LowerCaseEqualsASCII(qop_values.value(), "auth")) {
253        qop_ = QOP_AUTH;
254        break;
255      }
256    }
257  } else {
258    DVLOG(1) << "Skipping unrecognized digest property";
259    // TODO(eroman): perhaps we should fail instead of silently skipping?
260  }
261  return true;
262}
263
264// static
265std::string HttpAuthHandlerDigest::QopToString(QualityOfProtection qop) {
266  switch (qop) {
267    case QOP_UNSPECIFIED:
268      return "";
269    case QOP_AUTH:
270      return "auth";
271    default:
272      NOTREACHED();
273      return "";
274  }
275}
276
277// static
278std::string HttpAuthHandlerDigest::AlgorithmToString(
279    DigestAlgorithm algorithm) {
280  switch (algorithm) {
281    case ALGORITHM_UNSPECIFIED:
282      return "";
283    case ALGORITHM_MD5:
284      return "MD5";
285    case ALGORITHM_MD5_SESS:
286      return "MD5-sess";
287    default:
288      NOTREACHED();
289      return "";
290  }
291}
292
293void HttpAuthHandlerDigest::GetRequestMethodAndPath(
294    const HttpRequestInfo* request,
295    std::string* method,
296    std::string* path) const {
297  DCHECK(request);
298
299  const GURL& url = request->url;
300
301  if (target_ == HttpAuth::AUTH_PROXY && url.SchemeIs("https")) {
302    *method = "CONNECT";
303    *path = GetHostAndPort(url);
304  } else {
305    *method = request->method;
306    *path = HttpUtil::PathForRequest(url);
307  }
308}
309
310std::string HttpAuthHandlerDigest::AssembleResponseDigest(
311    const std::string& method,
312    const std::string& path,
313    const string16& username,
314    const string16& password,
315    const std::string& cnonce,
316    const std::string& nc) const {
317  // ha1 = MD5(A1)
318  // TODO(eroman): is this the right encoding?
319  std::string ha1 = MD5String(UTF16ToUTF8(username) + ":" + realm_ + ":" +
320                              UTF16ToUTF8(password));
321  if (algorithm_ == HttpAuthHandlerDigest::ALGORITHM_MD5_SESS)
322    ha1 = MD5String(ha1 + ":" + nonce_ + ":" + cnonce);
323
324  // ha2 = MD5(A2)
325  // TODO(eroman): need to add MD5(req-entity-body) for qop=auth-int.
326  std::string ha2 = MD5String(method + ":" + path);
327
328  std::string nc_part;
329  if (qop_ != HttpAuthHandlerDigest::QOP_UNSPECIFIED) {
330    nc_part = nc + ":" + cnonce + ":" + QopToString(qop_) + ":";
331  }
332
333  return MD5String(ha1 + ":" + nonce_ + ":" + nc_part + ha2);
334}
335
336std::string HttpAuthHandlerDigest::AssembleCredentials(
337    const std::string& method,
338    const std::string& path,
339    const string16& username,
340    const string16& password,
341    const std::string& cnonce,
342    int nonce_count) const {
343  // the nonce-count is an 8 digit hex string.
344  std::string nc = base::StringPrintf("%08x", nonce_count);
345
346  // TODO(eroman): is this the right encoding?
347  std::string authorization = (std::string("Digest username=") +
348                               HttpUtil::Quote(UTF16ToUTF8(username)));
349  authorization += ", realm=" + HttpUtil::Quote(realm_);
350  authorization += ", nonce=" + HttpUtil::Quote(nonce_);
351  authorization += ", uri=" + HttpUtil::Quote(path);
352
353  if (algorithm_ != ALGORITHM_UNSPECIFIED) {
354    authorization += ", algorithm=" + AlgorithmToString(algorithm_);
355  }
356  std::string response = AssembleResponseDigest(method, path, username,
357                                                password, cnonce, nc);
358  // No need to call HttpUtil::Quote() as the response digest cannot contain
359  // any characters needing to be escaped.
360  authorization += ", response=\"" + response + "\"";
361
362  if (!opaque_.empty()) {
363    authorization += ", opaque=" + HttpUtil::Quote(opaque_);
364  }
365  if (qop_ != QOP_UNSPECIFIED) {
366    // TODO(eroman): Supposedly IIS server requires quotes surrounding qop.
367    authorization += ", qop=" + QopToString(qop_);
368    authorization += ", nc=" + nc;
369    authorization += ", cnonce=" + HttpUtil::Quote(cnonce);
370  }
371
372  return authorization;
373}
374
375}  // namespace net
376