From 9f83e0f7ee3ca359e298a9b02df522e68cf24c50 Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Sat, 22 Jun 2019 13:24:29 +0200
Subject: [PATCH] src/backup/crypt_config.rs: simplify decode interface

---
 src/backup/crypt_config.rs | 50 ++++++++++++++------------------------
 src/backup/data_blob.rs    | 11 ++++++---
 src/backup/data_chunk.rs   | 10 +++++---
 3 files changed, 33 insertions(+), 38 deletions(-)

diff --git a/src/backup/crypt_config.rs b/src/backup/crypt_config.rs
index 49aab44b..d49335a6 100644
--- a/src/backup/crypt_config.rs
+++ b/src/backup/crypt_config.rs
@@ -106,20 +106,13 @@ impl CryptConfig {
         Ok((iv, tag))
     }
 
-    /// Decompress and decrypt chunk, verify MAC.
-    ///
-    /// Binrary ``data`` is expected to be in format returned by encode_chunk. The magic number
-    /// is not used here.
-    pub fn decode_compressed_chunk(&self, data: &[u8]) -> Result<Vec<u8>, Error> {
-
-        if data.len() < 44 {
-            bail!("Invalid chunk len (<44)");
-        }
-
-        // let magic = &data[0..8];
-        // let crc = &data[8..12];
-        let iv = &data[12..28];
-        let mac = &data[28..44];
+    /// Decompress and decrypt date, verify MAC.
+    pub fn decode_compressed_chunk(
+        &self,
+        data: &[u8],
+        iv: &[u8; 16],
+        tag: &[u8; 16],
+    ) -> Result<Vec<u8>, Error> {
 
         let dec = Vec::with_capacity(1024*1024);
 
@@ -133,7 +126,7 @@ impl CryptConfig {
         let mut decr_buf = [0u8; BUFFER_SIZE];
         let max_decoder_input = BUFFER_SIZE - self.cipher.block_size();
 
-        let mut start = 44;
+        let mut start = 0;
         loop {
             let mut end = start + max_decoder_input;
             if end > data.len() { end = data.len(); }
@@ -146,7 +139,7 @@ impl CryptConfig {
             }
         }
 
-        c.set_tag(mac)?;
+        c.set_tag(tag)?;
         let rest = c.finalize(&mut decr_buf)?;
         if rest > 0 { decompressor.write_all(&decr_buf[..rest])?; }
 
@@ -155,28 +148,21 @@ impl CryptConfig {
         Ok(decompressor.into_inner())
     }
 
-    /// Decrypt chunk, verify MAC.
-    ///
-    /// Binrary ``data`` is expected to be in format returned by encode_chunk. The magic number
-    /// is not used here.
-    pub fn decode_uncompressed_chunk(&self, data: &[u8]) -> Result<Vec<u8>, Error> {
-
-        if data.len() < 44 {
-            bail!("Invalid chunk len (<44)");
-        }
-
-        // let magic = &data[0..8];
-        // let crc = &data[8..12];
-        let iv = &data[12..28];
-        let mac = &data[28..44];
+    /// Decrypt data, verify tag.
+    pub fn decode_uncompressed_chunk(
+        &self,
+        data: &[u8],
+        iv: &[u8; 16],
+        tag: &[u8; 16],
+    ) -> Result<Vec<u8>, Error> {
 
         let decr_data = decrypt_aead(
             self.cipher,
             &self.enc_key,
             Some(iv),
             b"", //??
-            &data[44..],
-            mac,
+            data,
+            tag,
         )?;
 
         Ok(decr_data)
diff --git a/src/backup/data_blob.rs b/src/backup/data_blob.rs
index 9842f650..3bf00923 100644
--- a/src/backup/data_blob.rs
+++ b/src/backup/data_blob.rs
@@ -1,7 +1,9 @@
 use failure::*;
 use std::convert::TryInto;
 
-use crate::tools::write::*;
+use crate::tools::read::ReadUtilOps;
+use crate::tools::write::WriteUtilOps;
+
 use super::*;
 
 /// Data blob binary storage format
@@ -154,11 +156,14 @@ impl DataBlob {
             let data = zstd::block::decompress(&self.raw_data[data_start..], 16*1024*1024)?;
             return Ok(data);
         } else if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 || magic == &ENCRYPTED_BLOB_MAGIC_1_0 {
+            let header_len = std::mem::size_of::<EncryptedDataBlobHeader>();
+            let head = (&self.raw_data[..header_len]).read_value::<EncryptedDataBlobHeader>()?;
+
             if let Some(config) = config  {
                 let data = if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 {
-                    config.decode_compressed_chunk(&self.raw_data)?
+                    config.decode_compressed_chunk(&self.raw_data[header_len..], &head.iv, &head.tag)?
                 } else {
-                    config.decode_uncompressed_chunk(&self.raw_data)?
+                    config.decode_uncompressed_chunk(&self.raw_data[header_len..], &head.iv, &head.tag)?
                 };
                 return Ok(data);
             } else {
diff --git a/src/backup/data_chunk.rs b/src/backup/data_chunk.rs
index 608e2ff0..301da925 100644
--- a/src/backup/data_chunk.rs
+++ b/src/backup/data_chunk.rs
@@ -1,6 +1,7 @@
 use failure::*;
 use std::convert::TryInto;
-use crate::tools::write::*;
+use crate::tools::read::ReadUtilOps;
+use crate::tools::write::WriteUtilOps;
 
 use super::*;
 
@@ -163,11 +164,14 @@ impl DataChunk {
             let data = zstd::block::decompress(&self.raw_data[data_start..], 16*1024*1024)?;
             return Ok(data);
         } else if magic == &ENCR_COMPR_CHUNK_MAGIC_1_0 || magic == &ENCRYPTED_CHUNK_MAGIC_1_0 {
+            let header_len = std::mem::size_of::<EncryptedDataChunkHeader>();
+            let head = (&self.raw_data[..header_len]).read_value::<EncryptedDataChunkHeader>()?;
+
             if let Some(config) = config  {
                 let data = if magic == &ENCR_COMPR_CHUNK_MAGIC_1_0 {
-                    config.decode_compressed_chunk(&self.raw_data)?
+                    config.decode_compressed_chunk(&self.raw_data[header_len..], &head.iv, &head.tag)?
                 } else {
-                    config.decode_uncompressed_chunk(&self.raw_data)?
+                    config.decode_uncompressed_chunk(&self.raw_data[header_len..], &head.iv, &head.tag)?
                 };
                 return Ok(data);
             } else {