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feat(relay): refresh_token grant — rotation, DPoP binding check
+142
-4
+142
-4
crates/relay/src/routes/oauth_token.rs
+142
-4
crates/relay/src/routes/oauth_token.rs
···
21
21
use crate::auth::{
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cleanup_expired_nonces, issue_nonce, validate_dpop_for_token_endpoint, DpopTokenEndpointError,
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};
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-
use crate::db::oauth::store_oauth_refresh_token;
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+
use crate::db::oauth::{
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consume_oauth_refresh_token, store_oauth_refresh_token,
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+
};
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use crate::routes::token::generate_token;
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// ── Request / response types ──────────────────────────────────────────────────
···
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match grant_type {
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"authorization_code" => handle_authorization_code(&state, &headers, form).await,
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"refresh_token" => {
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-
// Implemented in Phase 6.
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-
OAuthTokenError::new("invalid_grant", "refresh_token grant not yet implemented")
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.into_response()
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+
handle_refresh_token(&state, &headers, form).await
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}
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_ => OAuthTokenError::new(
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"unsupported_grant_type",
···
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expires_in: 300,
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refresh_token: refresh.plaintext,
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scope: auth_code.scope,
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+
}),
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+
)
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.into_response()
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+
}
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+
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async fn handle_refresh_token(
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state: &AppState,
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+
headers: &HeaderMap,
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+
form: TokenRequestForm,
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+
) -> Response {
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+
// Prune stale nonces on every request.
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+
cleanup_expired_nonces(&state.dpop_nonces).await;
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+
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+
// Required fields.
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+
let refresh_token_plaintext = match form.refresh_token.as_deref() {
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Some(t) if !t.is_empty() => t.to_string(),
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+
_ => {
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return OAuthTokenError::new("invalid_request", "missing parameter: refresh_token")
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+
.into_response();
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+
}
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+
};
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+
let client_id = match form.client_id.as_deref() {
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Some(id) if !id.is_empty() => id.to_string(),
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+
_ => {
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return OAuthTokenError::new("invalid_request", "missing parameter: client_id")
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+
.into_response();
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+
}
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+
};
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+
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+
// Validate DPoP proof — must be present, structurally valid, and carry a valid server nonce.
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let dpop_token = match headers.get("DPoP").and_then(|v| v.to_str().ok()) {
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Some(t) => t.to_string(),
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None => {
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return OAuthTokenError::new("invalid_dpop_proof", "DPoP header required")
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.into_response();
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}
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};
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+
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let token_url = format!(
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"{}/oauth/token",
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state.config.public_url.trim_end_matches('/')
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);
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+
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+
let jkt = match validate_dpop_for_token_endpoint(
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&dpop_token,
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"POST",
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&token_url,
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&state.dpop_nonces,
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)
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.await
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{
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Ok(jkt) => jkt,
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Err(DpopTokenEndpointError::MissingHeader) => {
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return OAuthTokenError::new("invalid_dpop_proof", "DPoP header required")
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+
.into_response();
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}
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Err(DpopTokenEndpointError::InvalidProof(msg)) => {
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return OAuthTokenError::new("invalid_dpop_proof", msg).into_response();
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}
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Err(DpopTokenEndpointError::UseNonce(fresh_nonce)) => {
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+
return OAuthTokenError::with_nonce(
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"use_dpop_nonce",
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"DPoP nonce required",
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fresh_nonce,
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)
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.into_response();
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}
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};
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+
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// Hash the presented refresh token for DB lookup.
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let token_hash = crate::routes::token::sha256_hex(
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&URL_SAFE_NO_PAD
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.decode(refresh_token_plaintext.as_str())
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.unwrap_or_else(|_| refresh_token_plaintext.as_bytes().to_vec()),
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+
);
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+
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// Atomically consume the refresh token (SELECT + DELETE).
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let stored = match consume_oauth_refresh_token(&state.db, &token_hash).await {
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Ok(Some(row)) => row,
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+
Ok(None) => {
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+
return OAuthTokenError::new("invalid_grant", "refresh token not found or expired")
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+
.into_response();
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+
}
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+
Err(e) => {
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tracing::error!(error = %e, "failed to consume refresh token");
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+
return OAuthTokenError::new("server_error", "database error").into_response();
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+
}
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+
};
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+
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// Verify client_id matches the stored value.
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+
if stored.client_id != client_id {
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return OAuthTokenError::new("invalid_grant", "client_id mismatch").into_response();
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+
}
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+
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// DPoP binding check: if the refresh token was bound to a specific key, the same key must be used.
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+
if let Some(ref stored_jkt) = stored.jkt {
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+
if *stored_jkt != jkt {
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+
return OAuthTokenError::new("invalid_grant", "DPoP key mismatch").into_response();
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+
}
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+
}
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+
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// Issue new ES256 access token.
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let access_token =
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match issue_access_token(&state.oauth_signing_keypair, &stored.did, &stored.scope, &jkt) {
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Ok(t) => t,
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+
Err(e) => return e.into_response(),
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+
};
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+
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// Generate and store new refresh token (rotation: old token already deleted above).
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let new_refresh = generate_token();
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+
if let Err(e) = store_oauth_refresh_token(
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&state.db,
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&new_refresh.hash,
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&stored.client_id,
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+
&stored.did,
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&jkt,
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)
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+
.await
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{
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tracing::error!(error = %e, "failed to store rotated refresh token");
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+
return OAuthTokenError::new("server_error", "database error").into_response();
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+
}
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+
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+
// Issue fresh DPoP nonce for the next request.
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+
let fresh_nonce = issue_nonce(&state.dpop_nonces).await;
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+
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+
let mut response_headers = axum::http::HeaderMap::new();
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+
response_headers.insert("DPoP-Nonce", fresh_nonce.parse().unwrap());
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+
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+
(
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StatusCode::OK,
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+
response_headers,
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+
Json(TokenResponse {
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+
access_token,
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+
token_type: "DPoP",
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+
expires_in: 300,
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+
refresh_token: new_refresh.plaintext,
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+
scope: stored.scope,
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}),
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)
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.into_response()