feat: accept audience from scope audience:server:client_id

Author: barrbrain

src/cmd/create/public.rs

@@ -2,7 +2,7 @@ use crate::{
     cmd::create::CreateCommon,
     config::{Client, ClientType, Config},
     http::{HttpOptions, create_client},
-    oidc::{extra_scopes, refresh_token_request},
+    oidc::{extra_scopes, other_audiences, refresh_token_request},
     server::{Bind, Server},
     utils::OrNone,
 };
@@ -221,9 +221,16 @@ Open the following URL in your browser and perform the interactive login process
         // check ID token
 
         if let Some(id_token) = token.extra_fields().id_token() {
+            let scopes = self.common.scope.as_deref();
+            let verifier =
+                client
+                    .id_token_verifier()
+                    .set_other_audience_verifier_fn(move |other| {
+                        other_audiences(scopes).any(|aud| other == &aud)
+                    });
             id_token
                 .clone()
-                .into_claims(&client.id_token_verifier(), &nonce)
+                .into_claims(&verifier, &nonce)
                 .context("failed to verify ID token")?;
         }
 

src/oidc.rs

@@ -8,7 +8,7 @@ use anyhow::{anyhow, bail};
 use biscuit::{Empty, jws::Compact};
 use oauth2::{EndpointMaybeSet, EndpointNotSet, EndpointSet, RefreshToken};
 use openidconnect::{
-    ClientId, ClientSecret, IssuerUrl, Scope,
+    Audience, ClientId, ClientSecret, IssuerUrl, Scope,
     core::{CoreClient, CoreProviderMetadata, CoreTokenResponse},
 };
 use time::OffsetDateTime;
@@ -103,6 +103,18 @@ pub fn extra_scopes(scope: Option<&str>) -> impl Iterator<Item = Scope> {
         .map(|s| Scope::new(s.into()))
 }
 
+/// Other audiences specified in scope may be implicitly trusted.
+/// The `audience:server:client_id:{CLIENT_ID}` format originates with GoogleAuthUtil.
+/// See <https://github.com/ctron/oidc-cli/pull/14> for context and
+/// <https://dexidp.io/docs/configuration/custom-scopes-claims-clients/>.
+pub fn other_audiences(scope: Option<&str>) -> impl Iterator<Item = Audience> {
+    scope
+        .into_iter()
+        .flat_map(|s| s.split(' '))
+        .filter_map(|s| s.strip_prefix("audience:server:client_id:"))
+        .map(|aud| Audience::new(aud.into()))
+}
+
 pub fn check_refresh_token_expiration(refresh_token: &str) -> anyhow::Result<()> {
     if let Ok(token) =
         Compact::<RefreshTokenClaims, Empty>::new_encoded(refresh_token).unverified_payload()