feat: abstract method to perform action

sdgb-api/src/title/encryption/mod.rs

@@ -3,6 +3,7 @@ use std::io::{Read, Write as _};
 use aes::cipher::{
     BlockDecryptMut, BlockEncryptMut, BlockSizeUser, KeyIvInit, block_padding::Pkcs7,
 };
+
 use digest::generic_array::GenericArray;
 use flate2::write::ZlibEncoder;
 use flate2::{Compression, read::ZlibDecoder};
@@ -12,6 +13,20 @@ use crate::title::{MaiVersion, MaiVersionExt, Sdgb1_40, Sdgb1_50, error::ApiErro
 impl MaiVersionExt for Sdgb1_40 {
     fn decode(mut data: impl AsMut<[u8]>) -> Result<Vec<u8>, ApiError> {
         let mut decompressed = decompress(data.as_mut());
+        if decompressed.is_empty() {
+            return Err(ApiError::EmptyResponse);
+        }
+
+        let orig_len = decompressed.len();
+
+        let remain = 16 - decompressed.len() % 16;
+
+        if
+        // weird but nessacary for Rust Pkcs7
+        remain != 16 {
+            decompressed.resize(remain + orig_len, remain as _);
+        }
+
         let unpad_size = decrypt(&mut decompressed, Self::AES_KEY, Self::AES_IV)?.len();
         decompressed.truncate(unpad_size);
         Ok(decompressed)
@@ -26,6 +41,10 @@ impl MaiVersionExt for Sdgb1_40 {
 
 impl MaiVersionExt for Sdgb1_50 {
     fn decode(mut data: impl AsMut<[u8]>) -> Result<Vec<u8>, ApiError> {
+        if data.as_mut().is_empty() {
+            return Err(ApiError::EmptyResponse);
+        }
+
         let decrypted = decrypt(&mut data, Self::AES_KEY, Self::AES_IV)?;
         let decompressed = decompress(decrypted);
         Ok(decompressed)