headless_lms_server/controllers/main_frontend/oauth/
token.rs

1use crate::domain::oauth::dpop::verify_dpop_from_actix_for_token;
2use crate::domain::oauth::errors::TokenGrantError;
3use crate::domain::oauth::helpers::{oauth_invalid_client, ok_json_no_cache, scope_has_openid};
4use crate::domain::oauth::oauth_validated::OAuthValidated;
5use crate::domain::oauth::oidc::generate_id_token;
6use crate::domain::oauth::token_query::TokenQuery;
7use crate::domain::oauth::token_response::TokenResponse;
8use crate::domain::oauth::token_service::{
9    TokenGrantRequest, TokenGrantResult, generate_token_pair, process_token_grant,
10};
11use crate::domain::rate_limit_middleware_builder::{RateLimit, RateLimitConfig};
12use crate::prelude::*;
13use actix_web::{HttpResponse, web};
14use chrono::{Duration, Utc};
15use domain::error::{OAuthErrorCode, OAuthErrorData};
16use headless_lms_base::config::ApplicationConfiguration;
17use models::{
18    library::oauth::token_digest_sha256, oauth_access_token::TokenType, oauth_client::OAuthClient,
19};
20use sqlx::PgPool;
21use utoipa::OpenApi;
22
23#[derive(OpenApi)]
24#[openapi(paths(token))]
25#[allow(dead_code)]
26pub(crate) struct MainFrontendOauthTokenApiDoc;
27
28/// Handles the `/token` endpoint for exchanging authorization codes or refresh tokens.
29///
30/// This endpoint issues and rotates OAuth 2.0 and OpenID Connect tokens with support for
31/// **PKCE**, **DPoP sender-constrained tokens**, and **ID Token issuance**.
32///
33/// ### Authorization Code Grant
34/// - Validates client credentials (`client_id`, `client_secret`) or public client rules.
35/// - Verifies the authorization code, its redirect URI, PKCE binding (`code_verifier`), and expiration.
36/// - Optionally verifies a DPoP proof and binds the issued tokens to the DPoP JWK thumbprint (`dpop_jkt`).
37/// - Issues a new access token, refresh token, and (for OIDC requests) an ID token.
38///
39/// ### Refresh Token Grant
40/// - Validates the refresh token and client binding.
41/// - Verifies DPoP proof when applicable (must match the original `dpop_jkt`).
42/// - Rotates the refresh token (revokes the old one, inserts a new one linked to it).
43/// - Issues a new access token (and ID token if `openid` scope requested).
44///
45/// ### Security Features
46/// - **PKCE (RFC 7636)**: Enforced for public clients and optionally for confidential ones.
47/// - **DPoP (RFC 9449)**: Sender-constrains tokens to a JWK thumbprint.
48/// - **Refresh Token Rotation**: Prevents replay by revoking old RTs on use.
49/// - **OIDC ID Token**: Issued only if `openid` is in the granted scopes.
50///
51/// Follows:
52/// - [RFC 6749 §3.2 — Token Endpoint](https://datatracker.ietf.org/doc/html/rfc6749#section-3.2)
53/// - [RFC 7636 — PKCE](https://datatracker.ietf.org/doc/html/rfc7636)
54/// - [RFC 9449 — DPoP](https://datatracker.ietf.org/doc/html/rfc9449)
55/// - [OIDC Core §3.1.3 — Token Endpoint](https://openid.net/specs/openid-connect-core-1_0.html#TokenEndpoint)
56///
57/// # Example
58/// ```http
59/// POST /api/v0/main-frontend/oauth/token HTTP/1.1
60/// Content-Type: application/x-www-form-urlencoded
61///
62/// grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA&redirect_uri=http://localhost&client_id=test-client-id&client_secret=test-secret&code_verifier=dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
63/// ```
64///
65/// Successful response:
66/// ```http
67/// HTTP/1.1 200 OK
68/// Content-Type: application/json
69///
70/// {
71///   "access_token": "2YotnFZFEjr1zCsicMWpAA",
72///   "refresh_token": "tGzv3JOkF0XG5Qx2TlKWIA",
73///   "id_token": "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...",
74///   "token_type": "DPoP",
75///   "expires_in": 3600
76/// }
77/// ```
78///
79/// Example error:
80/// ```http
81/// HTTP/1.1 401 Unauthorized
82/// Content-Type: application/json
83///
84/// {
85///   "error": "invalid_client",
86///   "error_description": "invalid client secret"
87/// }
88/// ```
89///
90/// Example DPoP error:
91/// ```http
92/// HTTP/1.1 401 Unauthorized
93/// WWW-Authenticate: DPoP error="use_dpop_proof", error_description="Missing DPoP header"
94/// ```
95#[instrument(skip(pool, app_conf, form))]
96#[utoipa::path(
97    post,
98    path = "/token",
99    operation_id = "exchangeOauthToken",
100    tag = "oauth",
101    request_body(
102        content = serde_json::Value,
103        content_type = "application/x-www-form-urlencoded"
104    ),
105    responses(
106        (status = 200, description = "OAuth token response", body = serde_json::Value),
107        (status = 401, description = "OAuth token error")
108    )
109)]
110pub async fn token(
111    pool: web::Data<PgPool>,
112    OAuthValidated(form): OAuthValidated<TokenQuery>,
113    req: actix_web::HttpRequest,
114    app_conf: web::Data<ApplicationConfiguration>,
115) -> ControllerResult<HttpResponse> {
116    let mut conn = pool.acquire().await?;
117    let server_token = skip_authorize();
118
119    let access_ttl = Duration::hours(1);
120    let refresh_ttl = Duration::days(30);
121
122    let client = OAuthClient::find_by_client_id(&mut conn, &form.client_id)
123        .await
124        .map_err(|e| {
125            tracing::error!(err = %e, "OAuth token: client lookup failed");
126            oauth_invalid_client("invalid client_id")
127        })?;
128
129    // Add non-secret fields to the span for observability
130    tracing::Span::current().record("client_id", &form.client_id);
131
132    if client.is_confidential() {
133        match client.client_secret {
134            Some(ref secret) => {
135                let token_hmac_key = &app_conf.oauth_server_configuration.oauth_token_hmac_key;
136                if !secret.constant_eq(&token_digest_sha256(
137                    &form.client_secret.clone().unwrap_or_default(),
138                    token_hmac_key,
139                )) {
140                    return Err(oauth_invalid_client("invalid client secret"));
141                }
142            }
143            None => {
144                return Err(oauth_invalid_client(
145                    "client_secret required for confidential clients",
146                ));
147            }
148        }
149    }
150
151    // Check if client allows this grant type
152    let grant_kind = form.grant.kind();
153    tracing::Span::current().record("grant_type", format!("{:?}", grant_kind));
154    if !client.allows_grant(grant_kind) {
155        return Err(ControllerError::new(
156            ControllerErrorType::OAuthError(Box::new(OAuthErrorData {
157                error: OAuthErrorCode::UnsupportedGrantType.as_str().into(),
158                error_description: "grant type not allowed for this client".into(),
159                redirect_uri: None,
160                state: None,
161                nonce: None,
162            })),
163            "Grant type not allowed for this client",
164            None::<anyhow::Error>,
165        ));
166    }
167
168    // DPoP vs Bearer selection (token endpoint uses deferred replay so use_dpop_nonce does not revoke the auth code)
169    let dpop_jkt_opt = if req.headers().get("DPoP").is_some() {
170        Some(
171            verify_dpop_from_actix_for_token(
172                &mut conn,
173                &req,
174                &app_conf.oauth_server_configuration.dpop_nonce_key,
175            )
176            .await?,
177        )
178    } else {
179        if !client.bearer_allowed {
180            return Err(oauth_invalid_client(
181                "client not allowed to use other than dpop-bound tokens",
182            ));
183        }
184        None
185    };
186
187    let issued_token_type = if dpop_jkt_opt.is_some() {
188        TokenType::DPoP
189    } else {
190        TokenType::Bearer
191    };
192    tracing::Span::current().record("token_type", format!("{:?}", issued_token_type));
193
194    let token_hmac_key = &app_conf.oauth_server_configuration.oauth_token_hmac_key;
195    let token_pair = generate_token_pair(token_hmac_key);
196    let access_token = token_pair.access_token.clone();
197    let refresh_token = token_pair.refresh_token.clone();
198    let refresh_token_expires_at = Utc::now() + refresh_ttl;
199    let access_expires_at = Utc::now() + access_ttl;
200
201    let request = TokenGrantRequest {
202        grant: &form.grant,
203        client: &client,
204        token_pair,
205        access_expires_at,
206        refresh_expires_at: refresh_token_expires_at,
207        issued_token_type,
208        dpop_jkt: dpop_jkt_opt.as_deref(),
209        token_hmac_key,
210    };
211
212    let TokenGrantResult {
213        user_id,
214        scopes: scope_vec,
215        nonce: nonce_opt,
216        access_expires_at: at_expires_at,
217        issue_id_token,
218    } = process_token_grant(&mut conn, request)
219        .await
220        .map_err(|e: TokenGrantError| ControllerError::from(e))?;
221
222    let base_url = app_conf.base_url.trim_end_matches('/');
223    let id_token = if issue_id_token && scope_has_openid(&scope_vec) {
224        Some(generate_id_token(
225            user_id,
226            &client.client_id,
227            nonce_opt.as_deref(),
228            at_expires_at,
229            &format!("{}/api/v0/main-frontend/oauth", base_url),
230            &app_conf,
231        )?)
232    } else {
233        None
234    };
235
236    let response = TokenResponse {
237        access_token,
238        refresh_token: Some(refresh_token),
239        id_token,
240        token_type: match issued_token_type {
241            TokenType::Bearer => "Bearer".to_string(),
242            TokenType::DPoP => "DPoP".to_string(),
243        },
244        expires_in: access_ttl.num_seconds() as u32,
245    };
246
247    server_token.authorized_ok(ok_json_no_cache(response))
248}
249
250pub fn _add_routes(cfg: &mut web::ServiceConfig) {
251    cfg.service(
252        web::resource("/token")
253            .wrap(RateLimit::new(RateLimitConfig {
254                per_minute: Some(100),
255                per_hour: Some(500),
256                per_day: Some(2000),
257                per_month: None,
258                ..Default::default()
259            }))
260            .route(web::post().to(token)),
261    );
262}
headless_lms_server/controllers/main_frontend/oauth/token.rs

headless_lms_server/controllers/main_frontend/oauth/
token.rs
