1 // Copyright 2020 The PDFium Authors
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 "public/fpdf_signature.h"
6
7 #include <utility>
8 #include <vector>
9
10 #include "constants/form_fields.h"
11 #include "core/fpdfapi/parser/cpdf_array.h"
12 #include "core/fpdfapi/parser/cpdf_dictionary.h"
13 #include "core/fpdfapi/parser/cpdf_document.h"
14 #include "core/fxcrt/stl_util.h"
15 #include "fpdfsdk/cpdfsdk_helpers.h"
16 #include "third_party/base/numerics/safe_conversions.h"
17
18 namespace {
19
CollectSignatures(CPDF_Document * doc)20 std::vector<RetainPtr<const CPDF_Dictionary>> CollectSignatures(
21 CPDF_Document* doc) {
22 std::vector<RetainPtr<const CPDF_Dictionary>> signatures;
23 const CPDF_Dictionary* root = doc->GetRoot();
24 if (!root)
25 return signatures;
26
27 RetainPtr<const CPDF_Dictionary> acro_form = root->GetDictFor("AcroForm");
28 if (!acro_form)
29 return signatures;
30
31 RetainPtr<const CPDF_Array> fields = acro_form->GetArrayFor("Fields");
32 if (!fields)
33 return signatures;
34
35 CPDF_ArrayLocker locker(std::move(fields));
36 for (auto& field : locker) {
37 RetainPtr<const CPDF_Dictionary> field_dict = field->GetDict();
38 if (field_dict && field_dict->GetNameFor(pdfium::form_fields::kFT) ==
39 pdfium::form_fields::kSig) {
40 signatures.push_back(std::move(field_dict));
41 }
42 }
43 return signatures;
44 }
45
46 } // namespace
47
FPDF_GetSignatureCount(FPDF_DOCUMENT document)48 FPDF_EXPORT int FPDF_CALLCONV FPDF_GetSignatureCount(FPDF_DOCUMENT document) {
49 auto* doc = CPDFDocumentFromFPDFDocument(document);
50 if (!doc)
51 return -1;
52
53 return fxcrt::CollectionSize<int>(CollectSignatures(doc));
54 }
55
56 FPDF_EXPORT FPDF_SIGNATURE FPDF_CALLCONV
FPDF_GetSignatureObject(FPDF_DOCUMENT document,int index)57 FPDF_GetSignatureObject(FPDF_DOCUMENT document, int index) {
58 auto* doc = CPDFDocumentFromFPDFDocument(document);
59 if (!doc)
60 return nullptr;
61
62 std::vector<RetainPtr<const CPDF_Dictionary>> signatures =
63 CollectSignatures(doc);
64 if (!fxcrt::IndexInBounds(signatures, index))
65 return nullptr;
66
67 return FPDFSignatureFromCPDFDictionary(signatures[index].Get());
68 }
69
70 FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetContents(FPDF_SIGNATURE signature,void * buffer,unsigned long length)71 FPDFSignatureObj_GetContents(FPDF_SIGNATURE signature,
72 void* buffer,
73 unsigned long length) {
74 const CPDF_Dictionary* signature_dict =
75 CPDFDictionaryFromFPDFSignature(signature);
76 if (!signature_dict)
77 return 0;
78
79 RetainPtr<const CPDF_Dictionary> value_dict =
80 signature_dict->GetDictFor(pdfium::form_fields::kV);
81 if (!value_dict)
82 return 0;
83
84 ByteString contents = value_dict->GetByteStringFor("Contents");
85 const unsigned long contents_len =
86 pdfium::base::checked_cast<unsigned long>(contents.GetLength());
87 if (buffer && length >= contents_len)
88 memcpy(buffer, contents.c_str(), contents_len);
89
90 return contents_len;
91 }
92
93 FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetByteRange(FPDF_SIGNATURE signature,int * buffer,unsigned long length)94 FPDFSignatureObj_GetByteRange(FPDF_SIGNATURE signature,
95 int* buffer,
96 unsigned long length) {
97 const CPDF_Dictionary* signature_dict =
98 CPDFDictionaryFromFPDFSignature(signature);
99 if (!signature_dict)
100 return 0;
101
102 RetainPtr<const CPDF_Dictionary> value_dict =
103 signature_dict->GetDictFor(pdfium::form_fields::kV);
104 if (!value_dict)
105 return 0;
106
107 RetainPtr<const CPDF_Array> byte_range = value_dict->GetArrayFor("ByteRange");
108 if (!byte_range)
109 return 0;
110
111 const unsigned long byte_range_len =
112 fxcrt::CollectionSize<unsigned long>(*byte_range);
113 if (buffer && length >= byte_range_len) {
114 for (size_t i = 0; i < byte_range_len; ++i)
115 buffer[i] = byte_range->GetIntegerAt(i);
116 }
117 return byte_range_len;
118 }
119
120 FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetSubFilter(FPDF_SIGNATURE signature,char * buffer,unsigned long length)121 FPDFSignatureObj_GetSubFilter(FPDF_SIGNATURE signature,
122 char* buffer,
123 unsigned long length) {
124 const CPDF_Dictionary* signature_dict =
125 CPDFDictionaryFromFPDFSignature(signature);
126 if (!signature_dict)
127 return 0;
128
129 RetainPtr<const CPDF_Dictionary> value_dict =
130 signature_dict->GetDictFor(pdfium::form_fields::kV);
131 if (!value_dict || !value_dict->KeyExist("SubFilter"))
132 return 0;
133
134 ByteString sub_filter = value_dict->GetNameFor("SubFilter");
135 return NulTerminateMaybeCopyAndReturnLength(sub_filter, buffer, length);
136 }
137
138 FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetReason(FPDF_SIGNATURE signature,void * buffer,unsigned long length)139 FPDFSignatureObj_GetReason(FPDF_SIGNATURE signature,
140 void* buffer,
141 unsigned long length) {
142 const CPDF_Dictionary* signature_dict =
143 CPDFDictionaryFromFPDFSignature(signature);
144 if (!signature_dict)
145 return 0;
146
147 RetainPtr<const CPDF_Dictionary> value_dict =
148 signature_dict->GetDictFor(pdfium::form_fields::kV);
149 if (!value_dict)
150 return 0;
151
152 RetainPtr<const CPDF_Object> obj = value_dict->GetObjectFor("Reason");
153 if (!obj || !obj->IsString())
154 return 0;
155
156 return Utf16EncodeMaybeCopyAndReturnLength(obj->GetUnicodeText(), buffer,
157 length);
158 }
159
160 FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetTime(FPDF_SIGNATURE signature,char * buffer,unsigned long length)161 FPDFSignatureObj_GetTime(FPDF_SIGNATURE signature,
162 char* buffer,
163 unsigned long length) {
164 const CPDF_Dictionary* signature_dict =
165 CPDFDictionaryFromFPDFSignature(signature);
166 if (!signature_dict)
167 return 0;
168
169 RetainPtr<const CPDF_Dictionary> value_dict =
170 signature_dict->GetDictFor(pdfium::form_fields::kV);
171 if (!value_dict)
172 return 0;
173
174 RetainPtr<const CPDF_Object> obj = value_dict->GetObjectFor("M");
175 if (!obj || !obj->IsString())
176 return 0;
177
178 return NulTerminateMaybeCopyAndReturnLength(obj->GetString(), buffer, length);
179 }
180
181 FPDF_EXPORT unsigned int FPDF_CALLCONV
FPDFSignatureObj_GetDocMDPPermission(FPDF_SIGNATURE signature)182 FPDFSignatureObj_GetDocMDPPermission(FPDF_SIGNATURE signature) {
183 int permission = 0;
184 const CPDF_Dictionary* signature_dict =
185 CPDFDictionaryFromFPDFSignature(signature);
186 if (!signature_dict)
187 return permission;
188
189 RetainPtr<const CPDF_Dictionary> value_dict =
190 signature_dict->GetDictFor(pdfium::form_fields::kV);
191 if (!value_dict)
192 return permission;
193
194 RetainPtr<const CPDF_Array> references = value_dict->GetArrayFor("Reference");
195 if (!references)
196 return permission;
197
198 CPDF_ArrayLocker locker(std::move(references));
199 for (auto& reference : locker) {
200 RetainPtr<const CPDF_Dictionary> reference_dict = reference->GetDict();
201 if (!reference_dict)
202 continue;
203
204 ByteString transform_method = reference_dict->GetNameFor("TransformMethod");
205 if (transform_method != "DocMDP")
206 continue;
207
208 RetainPtr<const CPDF_Dictionary> transform_params =
209 reference_dict->GetDictFor("TransformParams");
210 if (!transform_params)
211 continue;
212
213 // Valid values are 1, 2 and 3; 2 is the default.
214 permission = transform_params->GetIntegerFor("P", 2);
215 if (permission < 1 || permission > 3)
216 permission = 0;
217
218 return permission;
219 }
220
221 return permission;
222 }
223