axum-jwt-auth 0.6.3

//! A Rust library for JWT authentication with support for both local keys and remote JWKS (JSON Web Key Sets).
//!
//! This crate provides a flexible JWT authentication system that can:
//! - Validate tokens using local RSA/HMAC keys
//! - Automatically fetch and cache remote JWKS endpoints
//! - Integrate seamlessly with the Axum web framework
//! - Handle token validation with configurable options
//! - Extract tokens from multiple sources (headers or cookies)
//!
//! It builds on top of the `jsonwebtoken` crate to provide higher-level authentication primitives
//! while maintaining full compatibility with standard JWT implementations.
//!
//! # Quick Start
//!
//! ## Using Bearer Tokens (Default)
//!
//! ```ignore
//! use std::sync::Arc;
//! use axum::{Router, routing::get, Json, extract::FromRef};
//! use axum_jwt_auth::{Claims, Decoder, LocalDecoder};
//! use serde::{Deserialize, Serialize};
//!
//! #[derive(Deserialize, Serialize)]
//! struct MyClaims {
//!     sub: String,
//!     exp: usize,
//! }
//!
//! #[derive(Clone, FromRef)]
//! struct AppState {
//!     decoder: Decoder<MyClaims>,
//! }
//!
//! async fn protected_handler(user: Claims<MyClaims>) -> Json<MyClaims> {
//!     Json(user.claims)
//! }
//!
//! let decoder = LocalDecoder::builder()
//!     .keys(keys)
//!     .validation(validation)
//!     .build()
//!     .unwrap();
//!
//! let state = AppState {
//!     decoder: Arc::new(decoder),
//! };
//!
//! let app = Router::new()
//!     .route("/protected", get(protected_handler))
//!     .with_state(state);
//! ```
//!
//! ## Custom Token Extractors
//!
//! Use macros to easily define custom extractors:
//!
//! ```ignore
//! use axum_jwt_auth::{define_header_extractor, define_cookie_extractor};
//! use axum_jwt_auth::{Claims, HeaderTokenExtractor, CookieTokenExtractor};
//!
//! // Define custom extractors
//! define_header_extractor!(XAuthToken, "x-auth-token");
//! define_cookie_extractor!(AuthCookie, "auth_token");
//!
//! // Use in handlers
//! async fn header_handler(user: Claims<MyClaims, HeaderTokenExtractor<XAuthToken>>) {
//!     // Token extracted from "x-auth-token" header
//! }
//!
//! async fn cookie_handler(user: Claims<MyClaims, CookieTokenExtractor<AuthCookie>>) {
//!     // Token extracted from "auth_token" cookie
//! }
//! ```
//!
//! # Examples
//!
//! For full examples, see the [examples directory](https://github.com/cmackenzie1/axum-jwt-auth/blob/main/examples).

mod axum;
mod local;
mod remote;

use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;

use jsonwebtoken::TokenData;
use serde::de::DeserializeOwned;
use thiserror::Error;

pub use crate::axum::{
    AuthError, BearerTokenExtractor, Claims, CookieTokenExtractor, ExtractorConfig,
    HeaderTokenExtractor, TokenExtractor,
};
pub use crate::local::LocalDecoder;
pub use crate::remote::{
    RemoteJwksDecoder, RemoteJwksDecoderBuilder, RemoteJwksDecoderConfig,
    RemoteJwksDecoderConfigBuilder,
};

/// Errors that can occur during JWT decoding and validation.
#[derive(Debug, thiserror::Error)]
pub enum Error {
    /// The JWT's `kid` (key ID) was not found in the key cache.
    #[error("JWT key not found (kid: {0:?})")]
    KeyNotFound(Option<String>),

    /// Invalid decoder configuration (e.g., missing keys, algorithms, or audience).
    #[error("Configuration error: {0}")]
    Configuration(String),

    /// JWT validation or decoding error from the `jsonwebtoken` crate.
    #[error("JWT error: {0}")]
    Jwt(#[from] jsonwebtoken::errors::Error),

    /// HTTP request error when fetching remote JWKS.
    #[error("HTTP request error: {0}")]
    Reqwest(#[from] reqwest::Error),

    /// JWKS refresh failed after exhausting all retry attempts.
    #[error("JWKS refresh failed after {retry_count} attempts: {message}")]
    JwksRefresh {
        message: String,
        retry_count: usize,
        #[source]
        source: Option<Box<dyn std::error::Error + Send + Sync>>,
    },
}

/// Trait for decoding and validating JWT tokens.
///
/// Implemented by [`LocalDecoder`] and [`RemoteJwksDecoder`] to provide
/// a unified interface for JWT validation with different key sources.
pub trait JwtDecoder<T>: Send + Sync
where
    T: for<'de> DeserializeOwned,
{
    /// Decodes and validates a JWT token string, returning the parsed claims.
    ///
    /// # Errors
    ///
    /// Returns an error if the token is invalid, expired, has an invalid signature,
    /// or if the key cannot be found (for remote decoders).
    fn decode<'a>(
        &'a self,
        token: &'a str,
    ) -> Pin<Box<dyn Future<Output = Result<TokenData<T>, Error>> + Send + 'a>>;
}

/// Type alias for a thread-safe, trait-object decoder suitable for Axum state.
///
/// Use this with `Arc::new(decoder)` to share a decoder across request handlers.
pub type Decoder<T> = Arc<dyn JwtDecoder<T> + Send + Sync>;