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LibPDF: Attempt to unecrypt strings and streams

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Matthew Olsson 2022-03-22 19:29:49 -07:00 • committed by Andreas Kling
parent 60c3e786be
commit 4e81663b31
2 changed files with 22 additions and 8 deletions
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29
Userland/Libraries/LibPDF/Parser.cpp
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@ -25,6 +25,7 @@ static NonnullRefPtr<T> make_object(Args... args) requires(IsBaseOf<Object, T>)
PDFErrorOr<Vector<Command>> Parser::parse_graphics_commands(Document* document, ReadonlyBytes bytes) PDFErrorOr<Vector<Command>> Parser::parse_graphics_commands(Document* document, ReadonlyBytes bytes)
{ {
auto parser = adopt_ref(*new Parser(document, bytes)); auto parser = adopt_ref(*new Parser(document, bytes));
parser->m_disable_encryption = true;
return parser->parse_graphics_commands(); return parser->parse_graphics_commands();
} }
@ -746,16 +747,23 @@ NonnullRefPtr<StringObject> Parser::parse_string()
VERIFY(!string.is_null()); VERIFY(!string.is_null());
if (string.bytes().starts_with(Array<u8, 2> { 0xfe, 0xff })) { auto string_object = make_object<StringObject>(string, is_binary_string);
if (m_document->security_handler() && !m_disable_encryption)
m_document->security_handler()->decrypt(string_object, m_current_reference_stack.last());
auto unencrypted_string = string_object->string();
if (unencrypted_string.bytes().starts_with(Array<u8, 2> { 0xfe, 0xff })) {
// The string is encoded in UTF16-BE // The string is encoded in UTF16-BE
string = TextCodec::decoder_for("utf-16be")->to_utf8(string); string_object->set_string(TextCodec::decoder_for("utf-16be")->to_utf8(unencrypted_string));
} else if (string.bytes().starts_with(Array<u8, 3> { 239, 187, 191 })) { } else if (unencrypted_string.bytes().starts_with(Array<u8, 3> { 239, 187, 191 })) {
// The string is encoded in UTF-8. This is the default anyways, but if these bytes // The string is encoded in UTF-8. This is the default anyways, but if these bytes
// are explicitly included, we have to trim them // are explicitly included, we have to trim them
string = string.substring(3); string_object->set_string(unencrypted_string.substring(3));
} }
return make_object<StringObject>(string, is_binary_string); return string_object;
} }
String Parser::parse_literal_string() String Parser::parse_literal_string()
@ -1003,17 +1011,22 @@ PDFErrorOr<NonnullRefPtr<StreamObject>> Parser::parse_stream(NonnullRefPtr<DictO
m_reader.move_by(9); m_reader.move_by(9);
consume_whitespace(); consume_whitespace();
auto stream_object = make_object<StreamObject>(dict, MUST(ByteBuffer::copy(bytes)));
if (m_document->security_handler() && !m_disable_encryption)
m_document->security_handler()->decrypt(stream_object, m_current_reference_stack.last());
if (dict->contains(CommonNames::Filter)) { if (dict->contains(CommonNames::Filter)) {
auto filter_type = MUST(dict->get_name(m_document, CommonNames::Filter))->name(); auto filter_type = MUST(dict->get_name(m_document, CommonNames::Filter))->name();
auto maybe_bytes = Filter::decode(bytes, filter_type); auto maybe_bytes = Filter::decode(stream_object->bytes(), filter_type);
if (maybe_bytes.is_error()) { if (maybe_bytes.is_error()) {
warnln("Failed to decode filter: {}", maybe_bytes.error().string_literal()); warnln("Failed to decode filter: {}", maybe_bytes.error().string_literal());
return error(String::formatted("Failed to decode filter {}", maybe_bytes.error().string_literal())); return error(String::formatted("Failed to decode filter {}", maybe_bytes.error().string_literal()));
} }
return make_object<StreamObject>(dict, maybe_bytes.value()); stream_object->buffer() = maybe_bytes.release_value();
} }
return make_object<StreamObject>(dict, MUST(ByteBuffer::copy(bytes))); return stream_object;
} }
PDFErrorOr<Vector<Command>> Parser::parse_graphics_commands() PDFErrorOr<Vector<Command>> Parser::parse_graphics_commands()

1
Userland/Libraries/LibPDF/Parser.h
View file

@ -146,6 +146,7 @@ private:
RefPtr<DictObject> m_trailer; RefPtr<DictObject> m_trailer;
Optional<LinearizationDictionary> m_linearization_dictionary; Optional<LinearizationDictionary> m_linearization_dictionary;
Vector<Reference> m_current_reference_stack; Vector<Reference> m_current_reference_stack;
bool m_disable_encryption { false };
}; };
}; };