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src/backup/data_blob.rs: impl. ChecksumWriter

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To correctly compute crc,hmac of final data.
This commit is contained in:
Dietmar Maurer 2019-08-12 08:53:53 +02:00
parent f796351c54
commit 706638f803
1 changed files with 77 additions and 51 deletions
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122
src/backup/data_blob.rs
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@ -294,14 +294,56 @@ impl DataBlob {
use std::io::{Read, BufRead, Write, Seek, SeekFrom};
enum BlobWriterState<'a, W: Write> {
Uncompressed { writer: W, hasher: crc32fast::Hasher },
Compressed { compr: zstd::stream::write::Encoder<W>, hasher: crc32fast::Hasher },
Signed {
struct ChecksumWriter<'a, W> {
writer: W,
hasher: crc32fast::Hasher,
signer: openssl::sign::Signer<'a>,
},
signer: Option<openssl::sign::Signer<'a>>,
}
impl <'a, W: Write> ChecksumWriter<'a, W> {
fn new(writer: W, signer: Option<openssl::sign::Signer<'a>>) -> Self {
let hasher = crc32fast::Hasher::new();
Self { writer, hasher, signer }
}
pub fn finish(mut self) -> Result<(W, u32, Option<[u8; 32]>), Error> {
let crc = self.hasher.finalize();
if let Some(ref mut signer) = self.signer {
let mut tag = [0u8; 32];
signer.sign(&mut tag)?;
Ok((self.writer, crc, Some(tag)))
} else {
Ok((self.writer, crc, None))
}
}
}
impl <'a, W: Write> Write for ChecksumWriter<'a, W> {
fn write(&mut self, buf: &[u8]) -> Result<usize, std::io::Error> {
self.hasher.update(buf);
if let Some(ref mut signer) = self.signer {
signer.update(buf).
map_err(|err| {
std::io::Error::new(
std::io::ErrorKind::Other,
format!("hmac update failed - {}", err))
})?;
}
self.writer.write(buf)
}
fn flush(&mut self) -> Result<(), std::io::Error> {
self.writer.flush()
}
}
enum BlobWriterState<'a, W: Write> {
Uncompressed { csum_writer: ChecksumWriter<'a, W> },
Compressed { compr: zstd::stream::write::Encoder<ChecksumWriter<'a, W>> },
Signed { csum_writer: ChecksumWriter<'a, W> },
}
/// Write compressed data blobs
@ -312,30 +354,27 @@ pub struct DataBlobWriter<'a, W: Write> {
impl <'a, W: Write + Seek> DataBlobWriter<'a, W> {
pub fn new_uncompressed(mut writer: W) -> Result<Self, Error> {
let hasher = crc32fast::Hasher::new();
writer.seek(SeekFrom::Start(0))?;
let head = DataBlobHeader { magic: UNCOMPRESSED_BLOB_MAGIC_1_0, crc: [0; 4] };
unsafe {
writer.write_le_value(head)?;
}
let state = BlobWriterState::Uncompressed { writer, hasher };
Ok(Self { state })
let csum_writer = ChecksumWriter::new(writer, None);
Ok(Self { state: BlobWriterState::Uncompressed { csum_writer }})
}
pub fn new_compressed(mut writer: W) -> Result<Self, Error> {
let hasher = crc32fast::Hasher::new();
writer.seek(SeekFrom::Start(0))?;
let head = DataBlobHeader { magic: COMPRESSED_BLOB_MAGIC_1_0, crc: [0; 4] };
unsafe {
writer.write_le_value(head)?;
}
let compr = zstd::stream::write::Encoder::new(writer, 1)?;
let state = BlobWriterState::Compressed { compr, hasher };
Ok(Self { state })
let csum_writer = ChecksumWriter::new(writer, None);
let compr = zstd::stream::write::Encoder::new(csum_writer, 1)?;
Ok(Self { state: BlobWriterState::Compressed { compr }})
}
pub fn new_signed(mut writer: W, config: &'a CryptConfig) -> Result<Self, Error> {
let hasher = crc32fast::Hasher::new();
writer.seek(SeekFrom::Start(0))?;
let head = AuthenticatedDataBlobHeader {
head: DataBlobHeader { magic: AUTHENTICATED_BLOB_MAGIC_1_0, crc: [0; 4] },
@ -345,16 +384,15 @@ impl <'a, W: Write + Seek> DataBlobWriter<'a, W> {
writer.write_le_value(head)?;
}
let signer = config.data_signer();
let state = BlobWriterState::Signed { writer, hasher, signer };
Ok(Self { state })
let csum_writer = ChecksumWriter::new(writer, Some(signer));
Ok(Self { state: BlobWriterState::Signed { csum_writer }})
}
pub fn finish(self) -> Result<W, Error> {
match self.state {
BlobWriterState::Uncompressed { mut writer, hasher } => {
BlobWriterState::Uncompressed { csum_writer } => {
// write CRC
let crc = hasher.finalize();
let (mut writer, crc, _) = csum_writer.finish()?;
let head = DataBlobHeader { magic: COMPRESSED_BLOB_MAGIC_1_0, crc: crc.to_le_bytes() };
writer.seek(SeekFrom::Start(0))?;
@ -364,11 +402,10 @@ impl <'a, W: Write + Seek> DataBlobWriter<'a, W> {
return Ok(writer)
}
BlobWriterState::Compressed { compr, hasher } => {
let mut writer = compr.finish()?;
BlobWriterState::Compressed { compr } => {
let csum_writer = compr.finish()?;
let (mut writer, crc, _) = csum_writer.finish()?;
// write CRC
let crc = hasher.finalize();
let head = DataBlobHeader { magic: COMPRESSED_BLOB_MAGIC_1_0, crc: crc.to_le_bytes() };
writer.seek(SeekFrom::Start(0))?;
@ -378,15 +415,13 @@ impl <'a, W: Write + Seek> DataBlobWriter<'a, W> {
return Ok(writer)
}
BlobWriterState::Signed { mut writer, hasher, signer, .. } => {
// write CRC and hmac
let crc = hasher.finalize();
BlobWriterState::Signed { csum_writer } => {
let (mut writer, crc, tag) = csum_writer.finish()?;
let mut head = AuthenticatedDataBlobHeader {
let head = AuthenticatedDataBlobHeader {
head: DataBlobHeader { magic: AUTHENTICATED_BLOB_MAGIC_1_0, crc: crc.to_le_bytes() },
tag: [0u8; 32],
tag: tag.unwrap(),
};
signer.sign(&mut head.tag)?;
writer.seek(SeekFrom::Start(0))?;
unsafe {
@ -403,37 +438,28 @@ impl <'a, W: Write + Seek> Write for DataBlobWriter<'a, W> {
fn write(&mut self, buf: &[u8]) -> Result<usize, std::io::Error> {
match self.state {
BlobWriterState::Uncompressed { ref mut writer, ref mut hasher } => {
hasher.update(buf);
writer.write(buf)
BlobWriterState::Uncompressed { ref mut csum_writer } => {
csum_writer.write(buf)
}
BlobWriterState::Compressed { ref mut compr, ref mut hasher } => {
hasher.update(buf);
BlobWriterState::Compressed { ref mut compr } => {
compr.write(buf)
}
BlobWriterState::Signed { ref mut writer, ref mut hasher, ref mut signer, .. } => {
hasher.update(buf);
signer.update(buf).
map_err(|err| {
std::io::Error::new(
std::io::ErrorKind::Other,
format!("hmac update failed - {}", err))
})?;
writer.write(buf)
BlobWriterState::Signed { ref mut csum_writer } => {
csum_writer.write(buf)
}
}
}
fn flush(&mut self) -> Result<(), std::io::Error> {
match self.state {
BlobWriterState::Uncompressed { ref mut writer, .. } => {
writer.flush()
BlobWriterState::Uncompressed { ref mut csum_writer } => {
csum_writer.flush()
}
BlobWriterState::Compressed { ref mut compr, .. } => {
BlobWriterState::Compressed { ref mut compr } => {
compr.flush()
}
BlobWriterState::Signed { ref mut writer, .. } => {
writer.flush()
BlobWriterState::Signed { ref mut csum_writer } => {
csum_writer.flush()
}
}
}