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use aes_gcm_siv::{
aead::{generic_array::GenericArray, Aead},
Aes256GcmSiv, KeyInit,
};
use anyhow::{anyhow, bail, Context};
use base64::Engine;
use bincode::{Decode, Encode};
use jellycommon::Asset;
use log::warn;
use std::{path::PathBuf, sync::LazyLock};
use crate::{cache::CachePath, SECRETS};
const VERSION: u32 = 2;
static ASSET_KEY: LazyLock<Aes256GcmSiv> = LazyLock::new(|| {
if let Some(sk) = &SECRETS.session_key {
let r = base64::engine::general_purpose::STANDARD
.decode(sk)
.expect("key invalid; should be valid base64");
aes_gcm_siv::Aes256GcmSiv::new_from_slice(&r)
.expect("key has the wrong length; should be 32 bytes")
} else {
warn!("session_key not configured; generating a random one.");
aes_gcm_siv::Aes256GcmSiv::new_from_slice(&[(); 32].map(|_| rand::random())).unwrap()
}
});
#[derive(Debug, Encode, Decode)]
pub enum AssetInner {
Federated { host: String, asset: Vec<u8> },
Cache(CachePath),
Assets(PathBuf),
}
impl AssetInner {
pub fn ser(&self) -> Asset {
let mut plaintext = Vec::new();
plaintext.extend(u32::to_le_bytes(VERSION));
plaintext.extend(bincode::encode_to_vec(&self, bincode::config::standard()).unwrap());
while plaintext.len() % 16 == 0 {
plaintext.push(0);
}
let nonce = [(); 12].map(|_| rand::random());
let mut ciphertext = ASSET_KEY
.encrypt(&GenericArray::from(nonce), plaintext.as_slice())
.unwrap();
ciphertext.extend(nonce);
Asset(base64::engine::general_purpose::URL_SAFE.encode(&ciphertext))
}
pub fn deser(s: &str) -> anyhow::Result<Self> {
let ciphertext = base64::engine::general_purpose::URL_SAFE.decode(&s)?;
let (ciphertext, nonce) = ciphertext.split_at(ciphertext.len() - 12);
let plaintext = ASSET_KEY
.decrypt(nonce.into(), ciphertext)
.map_err(|_| anyhow!("asset token decrypt failed"))?;
let version = u32::from_le_bytes(plaintext[0..4].try_into().unwrap());
if version != VERSION {
bail!("asset token version mismatch");
}
let (data, _): (AssetInner, _) =
bincode::decode_from_slice(&plaintext[4..], bincode::config::standard())
.context("asset token has invalid format")?;
Ok(data)
}
}
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