[joox] feat #1: add joox decipher implementation

um_cli/src/cmd/joox.rs

@@ -0,0 +1,49 @@
+use crate::Cli;
+use anyhow::Result;
+use clap::Args;
+use std::fs::File;
+use std::io::{BufReader, BufWriter, Read, Seek, SeekFrom, Write};
+use std::path::PathBuf;
+use umc_joox::decrypt::JooxDecipher;
+use umc_joox::header::Header;
+
+/// Decrypt a ofl_en file (Joox Music, Encryption V4)
+#[derive(Args)]
+pub struct ArgsJoox {
+    /// Path to output file, e.g. /export/Music/song.flac
+    #[clap(short, long)]
+    output: PathBuf,
+
+    /// Path to input file, e.g. /export/Music/song.ofl_en
+    #[arg(name = "input")]
+    input: PathBuf,
+
+    /// Device GUID
+    #[clap(short = 'u', long)]
+    device_guid: String,
+}
+
+impl ArgsJoox {
+    pub fn run(&self, _cli: &Cli) -> Result<i32> {
+        let mut file_input = File::open(&self.input)?;
+
+        let mut header_buffer = [0u8; 0x0c];
+        file_input.read_exact(&mut header_buffer)?;
+        let header = Header::from_buffer(&header_buffer, &self.device_guid)?;
+        file_input.seek(SeekFrom::Start(header.audio_start_offset as u64))?;
+
+        let reader = BufReader::new(file_input);
+        let mut input_stream = reader.take(header.original_file_len);
+
+        let file_output = File::create(&self.output)?;
+        let mut writer = BufWriter::new(file_output);
+
+        let mut buffer = vec![0u8; header.get_audio_block_size()].into_boxed_slice();
+        while let Ok(()) = input_stream.read_exact(&mut buffer) {
+            let result = header.decrypt_audio_block(&mut buffer)?;
+            writer.write_all(result)?;
+        }
+
+        Ok(0)
+    }
+}