[wasm/kgm] feat #2: add kgm glue

Cargo.lock

@@ -485,6 +485,7 @@ dependencies = [
  "console_error_panic_hook",
  "getrandom",
  "um_audio",
+ "umc_kgm",
  "umc_kuwo",
  "umc_ncm",
  "umc_qmc",

um_wasm/Cargo.toml

@@ -23,6 +23,7 @@ getrandom = { version = "0.2", features = ["js"] }
 # all the `std::fmt` and `std::panicking` infrastructure, so isn't great for
 # code size when deploying.
 console_error_panic_hook = { version = "0.1.7", optional = true }
+umc_kgm = { path = "../um_crypto/kgm" }
 umc_kuwo = { path = "../um_crypto/kuwo" }
 umc_ncm = { path = "../um_crypto/ncm" }
 umc_qmc = { path = "../um_crypto/qmc" }

um_wasm/src/exports/kgm.rs

@@ -0,0 +1,37 @@
+use umc_kgm::{header::Header, Decipher};
+use wasm_bindgen::prelude::wasm_bindgen;
+use wasm_bindgen::JsError;
+
+/// KuGou KGM file header.
+#[wasm_bindgen(js_name=KuGouHeader)]
+pub struct JsKuGouHeader(Header);
+
+#[wasm_bindgen(js_class = KuGouHeader)]
+impl JsKuGouHeader {
+    /// Parse the KuGou header (0x400 bytes)
+    pub fn parse(header: &[u8]) -> Result<JsKuGouHeader, JsError> {
+        Ok(JsKuGouHeader(
+            Header::from_buffer(header).map_err(JsError::from)?,
+        ))
+    }
+}
+
+/// KuGou KGM file decipher.
+#[wasm_bindgen(js_name=KuGouDecipher)]
+pub struct JsKuGouDecipher(Decipher);
+
+#[wasm_bindgen(js_class=KuGouDecipher)]
+impl JsKuGouDecipher {
+    /// Create an instance of cipher (decipher) for decryption
+    #[wasm_bindgen(constructor)]
+    pub fn new(header: &JsKuGouHeader) -> Result<JsKuGouDecipher, JsError> {
+        Ok(JsKuGouDecipher(
+            Decipher::new(&header.0).map_err(JsError::from)?,
+        ))
+    }
+
+    /// Decrypt a buffer.
+    pub fn decrypt(&self, buffer: &mut [u8], offset: usize) {
+        self.0.decrypt(buffer, offset)
+    }
+}

um_wasm/src/exports/mod.rs

@@ -1,4 +1,5 @@
 pub mod audio;
+pub mod kgm;
 pub mod kuwo;
 pub mod ncm;
 pub mod qmc;