decrypting a response body

decrypt_body.rs

use aes_gcm::{
    aead::{generic_array::GenericArray, Aead},
    Aes256Gcm,
};

async fn decrypt_body(
    mut response: reqwest::Response,
    cipher: &Aes256Gcm,
) -> anyhow::Result<reqwest::Response> {
    let mut headers = std::mem::take(response.headers_mut());
    let status = response.status().as_u16();
    let bytes = response.bytes().await?;
    let nonce = GenericArray::from_slice(&bytes[..12]);
    let decrypted = cipher.decrypt(nonce, &bytes[12..]).unwrap();
    let mut response = http::Response::builder().status(status);
    let headers_mut = response.headers_mut().unwrap();
    for (key, value) in headers.drain() {
        if let Some(key) = key {
            headers_mut.insert(key, value);
        }
    }
    let response = response.body(decrypted)?;
    Ok(reqwest::Response::from(response))
}

#[async_trait::async_trait]
pub trait DecryptBody {
    async fn decrypt_body(self, cipher: &Aes256Gcm) -> anyhow::Result<Self>
    where
        Self: Sized;
}

#[async_trait::async_trait]
impl DecryptBody for reqwest::Response {
    async fn decrypt_body(self, cipher: &Aes256Gcm) -> anyhow::Result<Self>
    where
        Self: Sized,
    {
        decrypt_body(self, cipher).await
    }
}