-
Notifications
You must be signed in to change notification settings - Fork 4.5k
/
Reference.cs
499 lines (442 loc) · 22.7 KB
/
Reference.cs
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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.IO;
using System.Net;
using System.Xml;
using System.Diagnostics.CodeAnalysis;
namespace System.Security.Cryptography.Xml
{
public class Reference
{
internal const string DefaultDigestMethod = SignedXml.XmlDsigSHA256Url;
private string? _id;
private string? _uri;
private string? _type;
private TransformChain _transformChain;
private string _digestMethod;
private byte[]? _digestValue;
private HashAlgorithm? _hashAlgorithm;
private readonly object? _refTarget;
private readonly ReferenceTargetType _refTargetType;
private XmlElement? _cachedXml;
private SignedXml? _signedXml;
internal CanonicalXmlNodeList? _namespaces;
//
// public constructors
//
public Reference()
{
_transformChain = new TransformChain();
_refTarget = null;
_refTargetType = ReferenceTargetType.UriReference;
_cachedXml = null;
_digestMethod = DefaultDigestMethod;
}
public Reference(Stream stream)
{
_transformChain = new TransformChain();
_refTarget = stream;
_refTargetType = ReferenceTargetType.Stream;
_cachedXml = null;
_digestMethod = DefaultDigestMethod;
}
public Reference(string? uri)
{
_transformChain = new TransformChain();
_refTarget = uri;
_uri = uri;
_refTargetType = ReferenceTargetType.UriReference;
_cachedXml = null;
_digestMethod = DefaultDigestMethod;
}
internal Reference(XmlElement element)
{
_transformChain = new TransformChain();
_refTarget = element;
_refTargetType = ReferenceTargetType.XmlElement;
_cachedXml = null;
_digestMethod = DefaultDigestMethod;
}
//
// public properties
//
public string? Id
{
get { return _id; }
set { _id = value; }
}
public string? Uri
{
get { return _uri; }
set
{
_uri = value;
_cachedXml = null;
}
}
public string? Type
{
get { return _type; }
set
{
_type = value;
_cachedXml = null;
}
}
public string DigestMethod
{
get { return _digestMethod; }
set
{
_digestMethod = value;
_cachedXml = null;
}
}
public byte[]? DigestValue
{
get { return _digestValue; }
set
{
_digestValue = value;
_cachedXml = null;
}
}
public TransformChain TransformChain
{
get => _transformChain ??= new TransformChain();
set
{
_transformChain = value;
_cachedXml = null;
}
}
[MemberNotNullWhen(true, nameof(_cachedXml))]
internal bool CacheValid
{
get
{
return (_cachedXml != null);
}
}
internal SignedXml? SignedXml
{
get { return _signedXml; }
set { _signedXml = value; }
}
internal ReferenceTargetType ReferenceTargetType
{
get
{
return _refTargetType;
}
}
private static readonly string[] s_expectedAttrNames = new string[] { "Id", "URI", "Type" };
//
// public methods
//
public XmlElement GetXml()
{
if (CacheValid) return _cachedXml;
XmlDocument document = new XmlDocument();
document.PreserveWhitespace = true;
return GetXml(document);
}
internal XmlElement GetXml(XmlDocument document)
{
// Create the Reference
XmlElement referenceElement = document.CreateElement("Reference", SignedXml.XmlDsigNamespaceUrl);
if (!string.IsNullOrEmpty(_id))
referenceElement.SetAttribute("Id", _id);
if (_uri != null)
referenceElement.SetAttribute("URI", _uri);
if (!string.IsNullOrEmpty(_type))
referenceElement.SetAttribute("Type", _type);
// Add the transforms to the Reference
if (TransformChain.Count != 0)
referenceElement.AppendChild(TransformChain.GetXml(document, SignedXml.XmlDsigNamespaceUrl));
// Add the DigestMethod
if (string.IsNullOrEmpty(_digestMethod))
throw new CryptographicException(SR.Cryptography_Xml_DigestMethodRequired);
XmlElement digestMethodElement = document.CreateElement("DigestMethod", SignedXml.XmlDsigNamespaceUrl);
digestMethodElement.SetAttribute("Algorithm", _digestMethod);
referenceElement.AppendChild(digestMethodElement);
if (DigestValue == null)
{
if (_hashAlgorithm!.Hash == null)
throw new CryptographicException(SR.Cryptography_Xml_DigestValueRequired);
DigestValue = _hashAlgorithm.Hash;
}
XmlElement digestValueElement = document.CreateElement("DigestValue", SignedXml.XmlDsigNamespaceUrl);
digestValueElement.AppendChild(document.CreateTextNode(Convert.ToBase64String(_digestValue!)));
referenceElement.AppendChild(digestValueElement);
return referenceElement;
}
[RequiresDynamicCode(CryptoHelpers.XsltRequiresDynamicCodeMessage)]
[RequiresUnreferencedCode(CryptoHelpers.CreateFromNameUnreferencedCodeMessage)]
public void LoadXml(XmlElement value)
{
if (value is null)
{
throw new ArgumentNullException(nameof(value));
}
_id = Utils.GetAttribute(value, "Id", SignedXml.XmlDsigNamespaceUrl);
_uri = Utils.GetAttribute(value, "URI", SignedXml.XmlDsigNamespaceUrl);
_type = Utils.GetAttribute(value, "Type", SignedXml.XmlDsigNamespaceUrl);
if (!Utils.VerifyAttributes(value, s_expectedAttrNames))
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference");
XmlNamespaceManager nsm = new XmlNamespaceManager(value.OwnerDocument.NameTable);
nsm.AddNamespace("ds", SignedXml.XmlDsigNamespaceUrl);
// Transforms
bool hasTransforms = false;
TransformChain = new TransformChain();
XmlNodeList? transformsNodes = value.SelectNodes("ds:Transforms", nsm);
if (transformsNodes != null && transformsNodes.Count != 0)
{
if (transformsNodes.Count > 1)
{
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/Transforms");
}
hasTransforms = true;
XmlElement transformsElement = (transformsNodes[0] as XmlElement)!;
if (!Utils.VerifyAttributes(transformsElement, (string[]?)null))
{
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/Transforms");
}
XmlNodeList? transformNodes = transformsElement.SelectNodes("ds:Transform", nsm);
if (transformNodes != null)
{
if (transformNodes.Count != transformsElement.SelectNodes("*")!.Count)
{
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/Transforms");
}
if (transformNodes.Count > Utils.MaxTransformsPerReference)
{
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/Transforms");
}
foreach (XmlNode transformNode in transformNodes)
{
XmlElement transformElement = (transformNode as XmlElement)!;
string? algorithm = Utils.GetAttribute(transformElement, "Algorithm", SignedXml.XmlDsigNamespaceUrl);
if (algorithm == null || !Utils.VerifyAttributes(transformElement, "Algorithm"))
{
throw new CryptographicException(SR.Cryptography_Xml_UnknownTransform);
}
Transform? transform = CryptoHelpers.CreateFromName<Transform>(algorithm);
if (transform == null)
{
throw new CryptographicException(SR.Cryptography_Xml_UnknownTransform);
}
AddTransform(transform);
// let the transform read the children of the transformElement for data
transform.LoadInnerXml(transformElement.ChildNodes);
// Hack! this is done to get around the lack of here() function support in XPath
if (transform is XmlDsigEnvelopedSignatureTransform)
{
// Walk back to the Signature tag. Find the nearest signature ancestor
// Signature-->SignedInfo-->Reference-->Transforms-->Transform
XmlNode? signatureTag = transformElement.SelectSingleNode("ancestor::ds:Signature[1]", nsm);
// Resolve the reference to get starting point for position calculation.
// This needs to match the way CalculateSignature resolves URI references.
XmlNode? referenceTarget = null;
if (_uri == null || _uri.Length == 0)
{
referenceTarget = transformElement.OwnerDocument;
}
else if (_uri[0] == '#')
{
string idref = Utils.ExtractIdFromLocalUri(_uri);
if (idref == "xpointer(/)")
{
referenceTarget = transformElement.OwnerDocument;
}
else
{
referenceTarget = SignedXml!.GetIdElement(transformElement.OwnerDocument, idref);
}
}
XmlNodeList? signatureList = referenceTarget?.SelectNodes(".//ds:Signature", nsm);
if (signatureList != null)
{
int position = 0;
foreach (XmlNode node in signatureList)
{
position++;
if (node == signatureTag)
{
((XmlDsigEnvelopedSignatureTransform)transform).SignaturePosition = position;
break;
}
}
}
}
}
}
}
// DigestMethod
XmlNodeList? digestMethodNodes = value.SelectNodes("ds:DigestMethod", nsm);
if (digestMethodNodes == null || digestMethodNodes.Count == 0 || digestMethodNodes.Count > 1)
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/DigestMethod");
XmlElement digestMethodElement = (digestMethodNodes[0] as XmlElement)!;
_digestMethod = Utils.GetAttribute(digestMethodElement, "Algorithm", SignedXml.XmlDsigNamespaceUrl)!;
if (_digestMethod == null || !Utils.VerifyAttributes(digestMethodElement, "Algorithm"))
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/DigestMethod");
// DigestValue
XmlNodeList? digestValueNodes = value.SelectNodes("ds:DigestValue", nsm);
if (digestValueNodes == null || digestValueNodes.Count == 0 || digestValueNodes.Count > 1)
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/DigestValue");
XmlElement digestValueElement = (digestValueNodes[0] as XmlElement)!;
_digestValue = Convert.FromBase64String(Utils.DiscardWhiteSpaces(digestValueElement.InnerText));
if (!Utils.VerifyAttributes(digestValueElement, (string[]?)null))
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference/DigestValue");
// Verify that there aren't any extra nodes that aren't allowed
int expectedChildNodeCount = hasTransforms ? 3 : 2;
if (value.SelectNodes("*")!.Count != expectedChildNodeCount)
throw new CryptographicException(SR.Cryptography_Xml_InvalidElement, "Reference");
// cache the Xml
_cachedXml = value;
}
public void AddTransform(Transform transform)
{
if (transform is null)
{
throw new ArgumentNullException(nameof(transform));
}
transform.Reference = this;
TransformChain.Add(transform);
}
[RequiresUnreferencedCode(CryptoHelpers.CreateFromNameUnreferencedCodeMessage)]
internal void UpdateHashValue(XmlDocument document, CanonicalXmlNodeList refList)
{
DigestValue = CalculateHashValue(document, refList);
}
// What we want to do is pump the input through the TransformChain and then
// hash the output of the chain document is the document context for resolving relative references
[RequiresUnreferencedCode(CryptoHelpers.CreateFromNameUnreferencedCodeMessage)]
internal byte[]? CalculateHashValue(XmlDocument document, CanonicalXmlNodeList refList)
{
// refList is a list of elements that might be targets of references
// Now's the time to create our hashing algorithm
_hashAlgorithm = CryptoHelpers.CreateNonTransformFromName<HashAlgorithm>(_digestMethod);
if (_hashAlgorithm == null)
throw new CryptographicException(SR.Cryptography_Xml_CreateHashAlgorithmFailed);
// Let's go get the target.
string baseUri = (document == null ? System.Environment.CurrentDirectory + "\\" : document.BaseURI);
Stream? hashInputStream = null;
WebResponse? response = null;
Stream? inputStream = null;
XmlResolver? resolver = null;
byte[] hashval;
try
{
switch (_refTargetType)
{
case ReferenceTargetType.Stream:
// This is the easiest case. We already have a stream, so just pump it through the TransformChain
resolver = (SignedXml!.ResolverSet ? SignedXml._xmlResolver : XmlResolverHelper.GetThrowingResolver());
hashInputStream = TransformChain.TransformToOctetStream((Stream?)_refTarget, resolver, baseUri);
break;
case ReferenceTargetType.UriReference:
// Second-easiest case -- dereference the URI & pump through the TransformChain
// handle the special cases where the URI is null (meaning whole doc)
// or the URI is just a fragment (meaning a reference to an embedded Object)
if (_uri == null)
{
// We need to create a DocumentNavigator out of the XmlElement
resolver = (SignedXml!.ResolverSet ? SignedXml._xmlResolver : XmlResolverHelper.GetThrowingResolver());
// In the case of a Uri-less reference, we will simply pass null to the transform chain.
// The first transform in the chain is expected to know how to retrieve the data to hash.
hashInputStream = TransformChain.TransformToOctetStream((Stream?)null, resolver!, baseUri);
}
else if (_uri.Length == 0)
{
// This is the self-referential case. First, check that we have a document context.
// The Enveloped Signature does not discard comments as per spec; those will be omitted during the transform chain process
if (document == null)
throw new CryptographicException(SR.Format(SR.Cryptography_Xml_SelfReferenceRequiresContext, _uri));
// Normalize the containing document
resolver = (SignedXml!.ResolverSet ? SignedXml._xmlResolver : XmlResolverHelper.GetThrowingResolver());
XmlDocument docWithNoComments = Utils.DiscardComments(Utils.PreProcessDocumentInput(document, resolver!, baseUri));
hashInputStream = TransformChain.TransformToOctetStream(docWithNoComments, resolver, baseUri);
}
else if (_uri[0] == '#')
{
// If we get here, then we are constructing a Reference to an embedded DataObject
// referenced by an Id = attribute. Go find the relevant object
string idref = Utils.GetIdFromLocalUri(_uri, out bool discardComments);
if (idref == "xpointer(/)")
{
// This is a self referential case
if (document == null)
throw new CryptographicException(SR.Format(SR.Cryptography_Xml_SelfReferenceRequiresContext, _uri));
// We should not discard comments here!!!
resolver = (SignedXml!.ResolverSet ? SignedXml._xmlResolver : XmlResolverHelper.GetThrowingResolver());
hashInputStream = TransformChain.TransformToOctetStream(Utils.PreProcessDocumentInput(document, resolver!, baseUri), resolver, baseUri);
break;
}
XmlElement? elem = SignedXml!.GetIdElement(document, idref);
if (elem != null)
_namespaces = Utils.GetPropagatedAttributes(elem.ParentNode as XmlElement);
if (elem == null)
{
// Go throw the referenced items passed in
if (refList != null)
{
foreach (XmlNode node in refList)
{
XmlElement? tempElem = node as XmlElement;
if ((tempElem != null) && (Utils.HasAttribute(tempElem, "Id", SignedXml.XmlDsigNamespaceUrl))
&& (Utils.GetAttribute(tempElem, "Id", SignedXml.XmlDsigNamespaceUrl)!.Equals(idref)))
{
elem = tempElem;
if (_signedXml!._context != null)
_namespaces = Utils.GetPropagatedAttributes(_signedXml._context);
break;
}
}
}
}
if (elem == null)
throw new CryptographicException(SR.Cryptography_Xml_InvalidReference);
XmlDocument normDocument = Utils.PreProcessElementInput(elem, resolver!, baseUri);
// Add the propagated attributes
Utils.AddNamespaces(normDocument.DocumentElement!, _namespaces);
resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : XmlResolverHelper.GetThrowingResolver());
if (discardComments)
{
// We should discard comments before going into the transform chain
XmlDocument docWithNoComments = Utils.DiscardComments(normDocument);
hashInputStream = TransformChain.TransformToOctetStream(docWithNoComments, resolver, baseUri);
}
else
{
// This is an XPointer reference, do not discard comments!!!
hashInputStream = TransformChain.TransformToOctetStream(normDocument, resolver, baseUri);
}
}
else
{
throw new CryptographicException(SR.Cryptography_Xml_UriNotResolved, _uri);
}
break;
case ReferenceTargetType.XmlElement:
// We need to create a DocumentNavigator out of the XmlElement
resolver = (SignedXml!.ResolverSet ? SignedXml._xmlResolver : XmlResolverHelper.GetThrowingResolver());
hashInputStream = TransformChain.TransformToOctetStream(Utils.PreProcessElementInput((XmlElement)_refTarget!, resolver!, baseUri), resolver, baseUri);
break;
default:
throw new CryptographicException(SR.Cryptography_Xml_UriNotResolved, _uri);
}
// Compute the new hash value
hashInputStream = SignedXmlDebugLog.LogReferenceData(this, hashInputStream);
hashval = _hashAlgorithm.ComputeHash(hashInputStream!);
}
finally
{
hashInputStream?.Close();
response?.Close();
inputStream?.Close();
}
return hashval;
}
}
}