androscalpel/apk_frauder/src/zip_writer.rs

287 lines
12 KiB
Rust

use std::io;
use std::io::{Cursor, Read, Seek, SeekFrom, Write};
use crate::compression::CompressionMethod;
use crate::data_descriptor::DataDescriptor;
use crate::end_of_central_directory::{
EndCentralDirectory, Zip64EndCentralDirectory, Zip64EndCentralDirectoryLocator,
};
use crate::{general_purpose_flags, FileHeader, FileInfo, LocalFileHeader, ZipFileReader};
use androscalpel_serializer::Serializable;
use flate2::write::DeflateEncoder;
use flate2::{Compression, CrcWriter};
pub struct ZipFileWriter<T: Write> {
files: Vec<FileInfo>,
zip64_end_of_central_directory: Option<Zip64EndCentralDirectory>,
current_offset: u64,
data: T,
}
impl<T: Write> ZipFileWriter<T> {
/// If provided, `zip64_info` is used to get the value that are not computable from
/// the state, like version needed to extract.
pub fn new(writer: T, zip64_info: Option<Zip64EndCentralDirectory>) -> Self {
Self {
current_offset: 0,
zip64_end_of_central_directory: zip64_info,
files: vec![],
data: writer,
}
}
/// Insert a file from an existing zip
pub fn insert_file_from_zip<U: Read + Seek>(
&mut self,
mut file_info: FileInfo,
zip_file: &mut ZipFileReader<U>,
) {
let file_off = file_info.get_file_offset();
let file_size = file_info.get_compressed_size();
file_info.set_offset_local_header(self.current_offset);
file_info.local_header.serialize(&mut self.data).unwrap();
zip_file.data.seek(SeekFrom::Start(file_off)).unwrap();
let mut remaining_size = file_size;
let mut buffer = [0u8; 4096];
while remaining_size != 0 {
let read = zip_file
.data
.read(&mut buffer[0..core::cmp::min(4096, remaining_size as usize)])
.unwrap();
self.data.write_all(&buffer[0..read]).unwrap();
remaining_size -= read as u64;
}
self.current_offset += file_info.local_header.size() as u64 + file_size;
self.files.push(file_info);
}
/// Insert a file
/// `header` provide for the values that are not computed from the file.
/// `local_header` can be provided is information in the local header differ
/// from the central directory header.
pub fn insert_file<U: Read + Seek>(
&mut self,
file: &mut U,
mut header: FileHeader,
local_header: Option<LocalFileHeader>,
data_descriptor: Option<DataDescriptor>,
) {
assert!(header.general_purpose_flags & general_purpose_flags::MASK_ENCRYPTED == 0);
assert!(
header.general_purpose_flags & general_purpose_flags::MASK_USE_DATA_DESCRIPTOR == 0
); // TODO
assert!(header.general_purpose_flags & general_purpose_flags::MASK_STRONG_ENCRYPTION == 0);
assert!(
header.general_purpose_flags & general_purpose_flags::MASK_ENCRYPTED_CENTRAL_DIR == 0
);
assert!(
header.general_purpose_flags
& (general_purpose_flags::MASK_COMPRESS_OPTION_1
| general_purpose_flags::MASK_COMPRESS_OPTION_2
| general_purpose_flags::MASK_UTF8_FILENAME)
== 0
);
assert!(
header.compression_method == CompressionMethod::Deflated
|| header.compression_method == CompressionMethod::Stored
);
let mut local_header = if let Some(header) = local_header {
assert!(header.general_purpose_flags & general_purpose_flags::MASK_ENCRYPTED == 0);
assert!(
header.general_purpose_flags & general_purpose_flags::MASK_USE_DATA_DESCRIPTOR == 0
); // TODO
assert!(
header.general_purpose_flags & general_purpose_flags::MASK_STRONG_ENCRYPTION == 0
);
assert!(
header.general_purpose_flags & general_purpose_flags::MASK_ENCRYPTED_CENTRAL_DIR
== 0
);
assert!(
header.general_purpose_flags
& (general_purpose_flags::MASK_COMPRESS_OPTION_1
| general_purpose_flags::MASK_COMPRESS_OPTION_2
| general_purpose_flags::MASK_UTF8_FILENAME)
== 0
);
assert!(
header.compression_method == CompressionMethod::Deflated
|| header.compression_method == CompressionMethod::Stored
);
LocalFileHeader {
version_needed_to_extract: header.version_needed_to_extract,
general_purpose_flags: if header.compression_method == CompressionMethod::Deflated {
header.general_purpose_flags
& (general_purpose_flags::MASK_COMPRESS_OPTION_1
| general_purpose_flags::MASK_COMPRESS_OPTION_2)
} else {
0
},
compression_method: header.compression_method,
last_mod_file_time: header.last_mod_file_time,
last_mod_file_data: header.last_mod_file_data,
crc_32: 0,
compressed_size: 0,
uncompressed_size: 0,
file_name: header.file_name,
extra_field: header.extra_field,
malformed_extra_field: header.malformed_extra_field.clone(),
decryption_header: None,
}
} else {
LocalFileHeader {
version_needed_to_extract: header.version_needed_to_extract,
general_purpose_flags: if header.compression_method == CompressionMethod::Deflated {
header.general_purpose_flags
& (general_purpose_flags::MASK_COMPRESS_OPTION_1
| general_purpose_flags::MASK_COMPRESS_OPTION_2)
} else {
0
},
compression_method: header.compression_method,
last_mod_file_time: header.last_mod_file_time,
last_mod_file_data: header.last_mod_file_data,
crc_32: 0,
compressed_size: 0,
uncompressed_size: 0,
file_name: header.file_name.clone(),
extra_field: header.extra_field.clone(),
malformed_extra_field: header.malformed_extra_field.clone(),
decryption_header: None,
}
};
let pos = file.stream_position().unwrap();
let pos_end = file.seek(SeekFrom::End(0)).unwrap();
file.seek(SeekFrom::Start(pos)).unwrap();
let uncompressed_size = pos_end - pos;
let header_offset = self.current_offset;
local_header.set_uncompressed_size(uncompressed_size);
let data = match local_header.compression_method {
CompressionMethod::Stored => {
let mut crc_writer = CrcWriter::new(Vec::new());
io::copy(file, &mut crc_writer).unwrap();
local_header.crc_32 = crc_writer.crc().sum();
crc_writer.into_inner()
}
CompressionMethod::Deflated => {
// TODO: find a way to do this in place, the compressed data can be large, and storing it
// in memory is bad, but Deflate consume the Reader, so we cannot juste give it self.data
// TODO: Compression::default -> use flag?
let mut compressor =
CrcWriter::new(DeflateEncoder::new(Vec::new(), Compression::default()));
io::copy(file, &mut compressor).unwrap();
local_header.crc_32 = compressor.crc().sum();
compressor.into_inner().finish().unwrap()
}
_ => unimplemented!(),
};
local_header.set_compressed_size(data.len() as u64);
local_header.serialize(&mut self.data).unwrap();
self.current_offset += local_header.size() as u64;
io::copy(&mut Cursor::new(data), &mut self.data).unwrap();
self.current_offset += local_header.get_compressed_size();
header.crc_32 = local_header.crc_32;
header.set_compressed_size(local_header.get_compressed_size());
header.set_uncompressed_size(local_header.get_uncompressed_size());
header.set_offset_local_header(header_offset);
// TODO: compression flags are not used right now, set to zero
local_header.general_purpose_flags &= !(general_purpose_flags::MASK_COMPRESS_OPTION_1
| general_purpose_flags::MASK_COMPRESS_OPTION_2);
header.general_purpose_flags &= !(general_purpose_flags::MASK_COMPRESS_OPTION_1
| general_purpose_flags::MASK_COMPRESS_OPTION_2);
if data_descriptor.is_some() {
panic!("Writing file with data_descriptor is not yet implemented");
}
let file_info = FileInfo {
local_header,
header,
data_descriptor,
};
self.files.push(file_info);
}
/// Finish the zip file by writing the central directory.
pub fn write_central_directory(&mut self) {
for file_info in &self.files {
file_info.header.serialize(&mut self.data).unwrap();
}
let number_of_entries_in_central_directory_on_disk = self.files.len();
let number_of_entries_in_central_directory = self.files.len();
let size_central_directory: u64 = self
.files
.iter()
.map(|file| file.header.size() as u64)
.sum();
let offset_central_directory = self.current_offset;
let use_zip64 = (number_of_entries_in_central_directory_on_disk > u16::MAX as usize)
|| (number_of_entries_in_central_directory > u16::MAX as usize)
|| (size_central_directory > u32::MAX as u64)
|| (offset_central_directory > u32::MAX as u64)
|| self.zip64_end_of_central_directory.is_some();
if use_zip64 {
if self.zip64_end_of_central_directory.is_none() {
self.zip64_end_of_central_directory = Some(Zip64EndCentralDirectory {
version_made_by: 45,
version_needed_to_extract: 45,
number_of_this_disk: 0,
disk_number_of_central_directory_start: 0,
number_entry_in_central_directory_on_this_disk: 0,
number_entry_in_central_directory: 0,
size_of_central_directory: 0,
offset_central_directory: 0,
extensible_data: vec![],
})
}
let zip64_edc = self.zip64_end_of_central_directory.as_mut().unwrap();
zip64_edc.number_entry_in_central_directory_on_this_disk =
number_of_entries_in_central_directory_on_disk as u64;
zip64_edc.number_entry_in_central_directory =
number_of_entries_in_central_directory as u64;
zip64_edc.size_of_central_directory = size_central_directory;
zip64_edc.offset_central_directory = offset_central_directory;
zip64_edc.serialize(&mut self.data).unwrap();
Zip64EndCentralDirectoryLocator {
disk_number_of_zip64_end_central_directory_start: 0,
offset_zip64_end_of_central_directory_record: offset_central_directory
+ size_central_directory,
total_number_of_disks: 0,
}
.serialize(&mut self.data)
.unwrap();
}
EndCentralDirectory {
disk_number: 0,
disk_number_of_central_directory_start: 0,
number_of_entries_in_central_directory_on_disk: if use_zip64 {
u16::MAX
} else {
number_of_entries_in_central_directory_on_disk as u16
},
number_of_entries_in_central_directory: if use_zip64 {
u16::MAX
} else {
number_of_entries_in_central_directory as u16
},
size_central_directory: if use_zip64 {
u32::MAX
} else {
size_central_directory as u32
},
offset_central_directory: if use_zip64 {
u32::MAX
} else {
offset_central_directory as u32
},
comment: vec![],
}
.serialize(&mut self.data)
.unwrap();
}
}