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// Copyright 2020 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "public/fpdf_signature.h"
#include <utility>
#include <vector>
#include "constants/form_fields.h"
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_document.h"
#include "core/fxcrt/compiler_specific.h"
#include "core/fxcrt/fx_memcpy_wrappers.h"
#include "core/fxcrt/numerics/safe_conversions.h"
#include "core/fxcrt/span.h"
#include "core/fxcrt/span_util.h"
#include "core/fxcrt/stl_util.h"
#include "fpdfsdk/cpdfsdk_helpers.h"
namespace {
std::vector<RetainPtr<const CPDF_Dictionary>> CollectSignatures(
CPDF_Document* doc) {
std::vector<RetainPtr<const CPDF_Dictionary>> signatures;
const CPDF_Dictionary* root = doc->GetRoot();
if (!root)
return signatures;
RetainPtr<const CPDF_Dictionary> acro_form = root->GetDictFor("AcroForm");
if (!acro_form)
return signatures;
RetainPtr<const CPDF_Array> fields = acro_form->GetArrayFor("Fields");
if (!fields)
return signatures;
CPDF_ArrayLocker locker(std::move(fields));
for (auto& field : locker) {
RetainPtr<const CPDF_Dictionary> field_dict = field->GetDict();
if (field_dict && field_dict->GetNameFor(pdfium::form_fields::kFT) ==
pdfium::form_fields::kSig) {
signatures.push_back(std::move(field_dict));
}
}
return signatures;
}
} // namespace
FPDF_EXPORT int FPDF_CALLCONV FPDF_GetSignatureCount(FPDF_DOCUMENT document) {
auto* doc = CPDFDocumentFromFPDFDocument(document);
if (!doc)
return -1;
return fxcrt::CollectionSize<int>(CollectSignatures(doc));
}
FPDF_EXPORT FPDF_SIGNATURE FPDF_CALLCONV
FPDF_GetSignatureObject(FPDF_DOCUMENT document, int index) {
auto* doc = CPDFDocumentFromFPDFDocument(document);
if (!doc)
return nullptr;
std::vector<RetainPtr<const CPDF_Dictionary>> signatures =
CollectSignatures(doc);
if (!fxcrt::IndexInBounds(signatures, index))
return nullptr;
return FPDFSignatureFromCPDFDictionary(signatures[index].Get());
}
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetContents(FPDF_SIGNATURE signature,
void* buffer,
unsigned long length) {
const CPDF_Dictionary* signature_dict =
CPDFDictionaryFromFPDFSignature(signature);
if (!signature_dict) {
return 0;
}
RetainPtr<const CPDF_Dictionary> value_dict =
signature_dict->GetDictFor(pdfium::form_fields::kV);
if (!value_dict) {
return 0;
}
// SAFETY: required from caller.
auto result_span = UNSAFE_BUFFERS(SpanFromFPDFApiArgs(buffer, length));
ByteString contents = value_dict->GetByteStringFor("Contents");
fxcrt::try_spancpy(result_span, contents.span());
return pdfium::checked_cast<unsigned long>(contents.span().size());
}
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetByteRange(FPDF_SIGNATURE signature,
int* buffer,
unsigned long length) {
const CPDF_Dictionary* signature_dict =
CPDFDictionaryFromFPDFSignature(signature);
if (!signature_dict)
return 0;
RetainPtr<const CPDF_Dictionary> value_dict =
signature_dict->GetDictFor(pdfium::form_fields::kV);
if (!value_dict)
return 0;
RetainPtr<const CPDF_Array> byte_range = value_dict->GetArrayFor("ByteRange");
if (!byte_range)
return 0;
const unsigned long byte_range_len =
fxcrt::CollectionSize<unsigned long>(*byte_range);
if (buffer && length >= byte_range_len) {
for (size_t i = 0; i < byte_range_len; ++i) {
UNSAFE_TODO(buffer[i]) = byte_range->GetIntegerAt(i);
}
}
return byte_range_len;
}
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetSubFilter(FPDF_SIGNATURE signature,
char* buffer,
unsigned long length) {
const CPDF_Dictionary* signature_dict =
CPDFDictionaryFromFPDFSignature(signature);
if (!signature_dict)
return 0;
RetainPtr<const CPDF_Dictionary> value_dict =
signature_dict->GetDictFor(pdfium::form_fields::kV);
if (!value_dict || !value_dict->KeyExist("SubFilter"))
return 0;
ByteString sub_filter = value_dict->GetNameFor("SubFilter");
// SAFETY: required from caller.
return NulTerminateMaybeCopyAndReturnLength(
sub_filter, UNSAFE_BUFFERS(SpanFromFPDFApiArgs(buffer, length)));
}
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetReason(FPDF_SIGNATURE signature,
void* buffer,
unsigned long length) {
const CPDF_Dictionary* signature_dict =
CPDFDictionaryFromFPDFSignature(signature);
if (!signature_dict)
return 0;
RetainPtr<const CPDF_Dictionary> value_dict =
signature_dict->GetDictFor(pdfium::form_fields::kV);
if (!value_dict)
return 0;
RetainPtr<const CPDF_Object> obj = value_dict->GetObjectFor("Reason");
if (!obj || !obj->IsString())
return 0;
// SAFETY: required from caller.
return Utf16EncodeMaybeCopyAndReturnLength(
obj->GetUnicodeText(),
UNSAFE_BUFFERS(SpanFromFPDFApiArgs(buffer, length)));
}
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDFSignatureObj_GetTime(FPDF_SIGNATURE signature,
char* buffer,
unsigned long length) {
const CPDF_Dictionary* signature_dict =
CPDFDictionaryFromFPDFSignature(signature);
if (!signature_dict)
return 0;
RetainPtr<const CPDF_Dictionary> value_dict =
signature_dict->GetDictFor(pdfium::form_fields::kV);
if (!value_dict)
return 0;
RetainPtr<const CPDF_Object> obj = value_dict->GetObjectFor("M");
if (!obj || !obj->IsString())
return 0;
// SAFETY: required from caller.
return NulTerminateMaybeCopyAndReturnLength(
obj->GetString(), UNSAFE_BUFFERS(SpanFromFPDFApiArgs(buffer, length)));
}
FPDF_EXPORT unsigned int FPDF_CALLCONV
FPDFSignatureObj_GetDocMDPPermission(FPDF_SIGNATURE signature) {
int permission = 0;
const CPDF_Dictionary* signature_dict =
CPDFDictionaryFromFPDFSignature(signature);
if (!signature_dict)
return permission;
RetainPtr<const CPDF_Dictionary> value_dict =
signature_dict->GetDictFor(pdfium::form_fields::kV);
if (!value_dict)
return permission;
RetainPtr<const CPDF_Array> references = value_dict->GetArrayFor("Reference");
if (!references)
return permission;
CPDF_ArrayLocker locker(std::move(references));
for (auto& reference : locker) {
RetainPtr<const CPDF_Dictionary> reference_dict = reference->GetDict();
if (!reference_dict)
continue;
ByteString transform_method = reference_dict->GetNameFor("TransformMethod");
if (transform_method != "DocMDP")
continue;
RetainPtr<const CPDF_Dictionary> transform_params =
reference_dict->GetDictFor("TransformParams");
if (!transform_params)
continue;
// Valid values are 1, 2 and 3; 2 is the default.
permission = transform_params->GetIntegerFor("P", 2);
if (permission < 1 || permission > 3)
permission = 0;
return permission;
}
return permission;
}