[qtfm] feat #4: implement QingTingFM decipher

um_cli/src/cmd/mod.rs

@@ -5,6 +5,7 @@ pub mod kgm;
 pub mod ncm;
 pub mod qmc1;
 pub mod qmc2;
+mod qtfm;
 pub mod xiami;
 pub mod xmly;
 
@@ -24,4 +25,6 @@ pub enum Commands {
     XMLY(xmly::ArgsXimalaya),
     #[command(name = "xiami")]
     Xiami(xiami::ArgsXiami),
+    #[command(name = "qtfm")]
+    QTFM(qtfm::ArgsQingTingFM),
 }

um_cli/src/cmd/qtfm.rs

@@ -0,0 +1,100 @@
+use crate::Cli;
+use anyhow::{bail, Result};
+use clap::Args;
+use std::fs::File;
+use std::io::{BufReader, BufWriter, Read, Write};
+use std::path::PathBuf;
+use umc_qtfm::nonce::make_decipher_iv;
+use umc_qtfm::Decipher;
+
+/// Decrypt a qta file (QingTingFM)
+#[derive(Args)]
+pub struct ArgsQingTingFM {
+    /// Path to output file, e.g. /export/Music/song.flac
+    #[clap(short, long)]
+    output: PathBuf,
+
+    /// Path to input file, e.g. /export/Music/song.xm
+    #[arg(name = "input")]
+    input: PathBuf,
+
+    /// Device info (CSV), in the order of "product,device,manufacturer,brand,board,model".
+    #[clap(short, long = "device")]
+    device: Option<String>,
+
+    /// Device key, in hex.
+    #[clap(short = 'k', long = "device-key")]
+    device_key: Option<String>,
+
+    /// Override name. default to file name.
+    #[clap(short, long)]
+    name: Option<String>,
+}
+
+impl ArgsQingTingFM {
+    pub fn run(&self, cli: &Cli) -> Result<i32> {
+        let mut reader = BufReader::with_capacity(cli.buffer_size, File::open(&self.input)?);
+        let mut writer = BufWriter::with_capacity(cli.buffer_size, File::create(&self.output)?);
+
+        let file_name = match &self.name {
+            Some(x) => x.clone(),
+            None => match self.input.file_name() {
+                Some(x) => x.to_string_lossy().to_string(),
+                None => bail!("failed to get file name"),
+            },
+        };
+
+        let device_key = self.make_device_key()?;
+        let iv = make_decipher_iv(file_name)?;
+
+        let decipher = Decipher::new(&device_key, &iv);
+
+        let mut offset = 0;
+        let mut buffer = vec![0u8; cli.buffer_size];
+        loop {
+            let n = reader.read(&mut buffer[..])?;
+            if n == 0 {
+                break;
+            }
+            decipher.decrypt(&mut buffer[..n], offset);
+            writer.write_all(&buffer[..n])?;
+            offset += n;
+        }
+
+        Ok(0)
+    }
+
+    fn make_device_key(&self) -> Result<[u8; 0x10]> {
+        let key = match &self.device_key {
+            Some(key) => {
+                let mut result = [0u8; 0x10];
+                hex::decode_to_slice(key, &mut result)?;
+                result
+            }
+            None => match &self.device {
+                Some(device) => {
+                    let mut device_parts = vec![];
+                    for item in device.split(',') {
+                        device_parts.push(item);
+                    }
+                    if device_parts.len() != 6 {
+                        bail!(
+                            "device needs 6 parts. current: {} part(s)",
+                            device_parts.len()
+                        );
+                    }
+                    umc_qtfm::secret::make_device_secret(
+                        device_parts[0],
+                        device_parts[1],
+                        device_parts[2],
+                        device_parts[3],
+                        device_parts[4],
+                        device_parts[5],
+                    )
+                }
+                None => bail!("one of device/device-key is required."),
+            },
+        };
+        Ok(key)
+    }
+}

um_cli/src/main.rs

@@ -34,6 +34,7 @@ fn run_command(cli: &Cli) -> Result<i32> {
         Some(Commands::JOOX(cmd)) => cmd.run(&cli),
         Some(Commands::XMLY(cmd)) => cmd.run(&cli),
         Some(Commands::Xiami(cmd)) => cmd.run(&cli),
+        Some(Commands::QTFM(cmd)) => cmd.run(&cli),
         None => {
             // https://github.com/clap-rs/clap/issues/3857#issuecomment-1161796261
             todo!("implement a sensible default command, similar to um/cli");