Fix tests. Remove tests which test rails functionality

2025-12-30 00:18:19 +11:00
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+# OpenID Connect Backchannel Logout
+
+## Overview
+
+Backchannel logout is an OpenID Connect feature that enables Clinch to notify applications when a user logs out, ensuring sessions are terminated across all connected applications immediately.
+
+## How It Works
+
+When a user logs out from Clinch (or any connected application), Clinch sends server-to-server HTTP POST requests to all applications that have configured a backchannel logout endpoint. This happens automatically in the background.
+
+### Logout Triggers
+
+Backchannel logout notifications are sent when:
+
+1. **User clicks "Sign Out" in Clinch** - All connected OIDC applications are notified, then the Clinch session is terminated
+2. **User logs out via OIDC `/logout` endpoint** (RP-Initiated Logout) - All connected applications are notified, then the Clinch session is terminated
+3. **User clicks "Logout" on an app (Dashboard)** - Backchannel logout is sent to that app, all access/refresh tokens are revoked, but OAuth consent is preserved (user can sign back in without re-authorizing)
+4. **User clicks "Revoke Access" for a specific app (Active Sessions page)** - Backchannel logout is sent to that app to terminate its session, all access/refresh tokens are revoked, then the OAuth consent is permanently destroyed (user must re-authorize the app to use it again)
+5. **User clicks "Revoke All App Access"** - All connected applications receive backchannel logout notifications, all tokens are revoked, then all OAuth consents are permanently destroyed
+
+### The Logout Flow
+
+```
+User logs out → Clinch finds all connected apps
+                ↓
+        For each app with backchannel_logout_uri:
+                ↓
+        Generate signed JWT logout token
+                ↓
+        HTTP POST to app's logout endpoint
+                ↓
+        App validates JWT and terminates session
+                ↓
+        Clinch revokes access and refresh tokens
+```
+
+### Logout vs Revoke Access
+
+Clinch provides two distinct actions for managing application access:
+
+| Action | Location | What Happens | When to Use |
+|--------|----------|--------------|-------------|
+| **Logout** | Dashboard | • Sends backchannel logout to app<br>• Revokes all access tokens<br>• Revokes all refresh tokens<br>• **Keeps OAuth consent intact** | You want to end your session with an app but still trust it. Next login will skip the authorization screen. |
+| **Revoke Access** | Active Sessions page | • Sends backchannel logout to app<br>• Revokes all access tokens<br>• Revokes all refresh tokens<br>• **Destroys OAuth consent** | You want to completely de-authorize an app. Next login will require you to re-authorize the app. |
+
+**Key Difference**: "Logout" preserves the authorization relationship while terminating the active session. "Revoke Access" completely removes the app's authorization to access your account.
+
+**Example Use Cases**:
+- **Logout**: "I left my Jellyfin session open at a friend's house. I want to kill that session but I still use Jellyfin."
+- **Revoke Access**: "I no longer trust this app and want to remove its authorization completely."
+
+**Technical Details**:
+- Both actions revoke access tokens (opaque, database-backed, validated on each use)
+- Both actions revoke refresh tokens (prevents obtaining new access tokens)
+- ID tokens remain valid until expiry (stateless JWTs), but apps should honor backchannel logout
+- Backchannel logout ensures the app clears its local session immediately
+
+## Configuring Applications
+
+### In Clinch Admin UI
+
+1. Navigate to **Admin → Applications**
+2. Edit or create an OIDC application
+3. In the "Backchannel Logout URI" field, enter the application's logout endpoint
+   - Example: `https://kavita.local/oidc/backchannel-logout`
+   - Must be HTTPS in production
+   - Leave blank if the application doesn't support backchannel logout
+
+### Checking Support
+
+The OIDC discovery endpoint advertises backchannel logout support:
+
+```bash
+curl https://clinch.local/.well-known/openid-configuration | jq
+```
+
+Look for:
+```json
+{
+  "backchannel_logout_supported": true,
+  "backchannel_logout_session_supported": true
+}
+```
+
+## Implementing a Backchannel Logout Endpoint (for RPs)
+
+If you're developing an application that integrates with Clinch, here's how to implement backchannel logout support:
+
+### 1. Create the Endpoint
+
+The endpoint must:
+- Accept HTTP POST requests
+- Parse the `logout_token` parameter from the form body
+- Validate the JWT signature
+- Terminate the user's session
+- Return 200 OK quickly (within 5 seconds)
+
+### 2. Example Implementation (Ruby/Rails)
+
+```ruby
+# config/routes.rb
+post '/oidc/backchannel-logout', to: 'oidc_backchannel_logout#logout'
+
+# app/controllers/oidc_backchannel_logout_controller.rb
+class OidcBackchannelLogoutController < ApplicationController
+  skip_before_action :verify_authenticity_token  # Server-to-server call
+  skip_before_action :authenticate_user!         # No user session yet
+
+  def logout
+    logout_token = params[:logout_token]
+
+    unless logout_token.present?
+      head :bad_request
+      return
+    end
+
+    begin
+      # Decode and verify the JWT
+      # Get Clinch's public key from JWKS endpoint
+      jwks = fetch_clinch_jwks
+      decoded = JWT.decode(
+        logout_token,
+        nil,  # Will be verified using JWKS
+        true,
+        {
+          algorithms: ['RS256'],
+          jwks: jwks,
+          verify_aud: true,
+          aud: YOUR_CLIENT_ID,
+          verify_iss: true,
+          iss: 'https://clinch.local'  # Your Clinch URL
+        }
+      )
+
+      claims = decoded.first
+
+      # Validate required claims
+      unless claims['events']&.key?('http://schemas.openid.net/event/backchannel-logout')
+        head :bad_request
+        return
+      end
+
+      # Get session ID from the token
+      sid = claims['sid']
+      sub = claims['sub']
+
+      # Terminate sessions
+      if sid.present?
+        # Terminate specific session by SID (recommended)
+        Session.where(oidc_sid: sid).destroy_all
+      elsif sub.present?
+        # Terminate all sessions for this user
+        user = User.find_by(oidc_sub: sub)
+        user&.sessions&.destroy_all
+      end
+
+      Rails.logger.info "Backchannel logout: Terminated session for sid=#{sid}, sub=#{sub}"
+      head :ok
+
+    rescue JWT::DecodeError => e
+      Rails.logger.error "Backchannel logout: Invalid JWT - #{e.message}"
+      head :bad_request
+    rescue => e
+      Rails.logger.error "Backchannel logout: Error - #{e.class}: #{e.message}"
+      head :internal_server_error
+    end
+  end
+
+  private
+
+  def fetch_clinch_jwks
+    # Cache this in production!
+    response = HTTParty.get('https://clinch.local/.well-known/jwks.json')
+    JSON.parse(response.body, symbolize_names: true)
+  end
+end
+```
+
+### 3. Required JWT Claims Validation
+
+The logout token will contain:
+
+| Claim | Description | Required |
+|-------|-------------|----------|
+| `iss` | Issuer (Clinch URL) | Yes |
+| `aud` | Your application's client_id | Yes |
+| `iat` | Issued at timestamp | Yes |
+| `jti` | Unique token ID | Yes |
+| `sub` | Pairwise subject identifier (user's SID) | Yes |
+| `sid` | Session ID (same as sub) | Yes |
+| `events` | Must contain `http://schemas.openid.net/event/backchannel-logout` | Yes |
+| `nonce` | Must NOT be present (spec requirement) | No |
+
+### 4. Session Tracking Requirements
+
+To support backchannel logout, your application must:
+
+1. **Store the `sid` claim from ID tokens**:
+   ```ruby
+   # When user logs in via OIDC
+   id_token = decode_id_token(params[:id_token])
+   session[:oidc_sid] = id_token['sid']  # Store this!
+   ```
+
+2. **Associate sessions with SID**:
+   ```ruby
+   # Create session with SID tracking
+   Session.create!(
+     user: current_user,
+     oidc_sid: id_token['sid'],
+     ...
+   )
+   ```
+
+3. **Terminate sessions by SID**:
+   ```ruby
+   # When backchannel logout is received
+   Session.where(oidc_sid: sid).destroy_all
+   ```
+
+### 5. Testing Your Endpoint
+
+Test with curl:
+
+```bash
+# Get a valid logout token (you'll need to capture this from Clinch logs)
+LOGOUT_TOKEN="eyJhbGc..."
+
+curl -X POST https://your-app.local/oidc/backchannel-logout \
+  -H "Content-Type: application/x-www-form-urlencoded" \
+  -d "logout_token=$LOGOUT_TOKEN"
+```
+
+Expected response: `200 OK` (empty body)
+
+## Monitoring and Troubleshooting
+
+### Checking Logs
+
+Clinch logs all backchannel logout attempts:
+
+```bash
+# In development
+tail -f log/development.log | grep BackchannelLogout
+
+# Example log output:
+# BackchannelLogout: Successfully sent logout notification to Kavita (https://kavita.local/oidc/backchannel-logout)
+# BackchannelLogout: Application Jellyfin doesn't support backchannel logout
+# BackchannelLogout: Timeout sending logout to HomeAssistant (https://ha.local/logout): Connection timeout
+```
+
+### Common Issues
+
+**1. HTTP Timeout**
+- Symptom: `Timeout sending logout to...` in logs
+- Solution: Ensure the RP's backchannel logout endpoint responds within 5 seconds
+- Note: Clinch will retry 3 times with exponential backoff
+
+**2. HTTP Errors (Non-200 Status)**
+- Symptom: `Application X returned HTTP 400/500...` in logs
+- Solution: Check the RP's logs for JWT validation errors
+- Common causes:
+  - Wrong JWKS (public key mismatch)
+  - Incorrect `aud` (client_id) validation
+  - Missing required claims validation
+
+**3. Network Unreachable**
+- Symptom: `Failed to send logout to...` with connection errors
+- Solution: Ensure the RP's logout endpoint is accessible from Clinch server
+- Check: Firewalls, DNS, SSL certificates
+
+**4. Sessions Not Terminating**
+- Symptom: User still logged into RP after logging out of Clinch
+- Solution: Verify the RP is storing and checking `sid` correctly
+- Debug: Add logging to the RP's backchannel logout handler
+
+### Verification Checklist
+
+For RPs (Application Developers):
+- [ ] Endpoint accepts POST requests
+- [ ] Endpoint validates JWT signature using Clinch's JWKS
+- [ ] Endpoint validates all required claims
+- [ ] Endpoint terminates sessions by SID
+- [ ] Endpoint returns 200 OK quickly (< 5 seconds)
+- [ ] Sessions store the `sid` claim from ID tokens
+- [ ] Backchannel logout URI is configured in Clinch admin
+
+For Administrators:
+- [ ] Application has `backchannel_logout_uri` configured
+- [ ] URI uses HTTPS (in production)
+- [ ] URI is reachable from Clinch server
+- [ ] Check logs for successful logout notifications
+
+## Security Considerations
+
+1. **JWT Signature Verification**: Always verify the logout token signature using Clinch's public key
+2. **Audience Validation**: Ensure the `aud` claim matches your client_id
+3. **Issuer Validation**: Ensure the `iss` claim matches your Clinch URL
+4. **No Authentication Required**: The endpoint should not require user authentication (it's server-to-server)
+5. **HTTPS Only**: Always use HTTPS in production (Clinch enforces this)
+6. **Fire-and-Forget**: RPs should log failures but not block on errors
+
+## Comparison with Other Logout Methods
+
+| Method | Communication | When Sessions Terminate | Reliability |
+|--------|--------------|------------------------|-------------|
+| **Backchannel Logout** | Server-to-server POST | Immediately | High (retries on failure) |
+| **Front-Channel Logout** | Browser iframes | When browser loads iframes | Low (blocked by privacy settings) |
+| **RP-Initiated Logout** | User redirects to Clinch | Only affects Clinch session | N/A (just triggers other methods) |
+| **Token Expiry** | None | When access token expires | Guaranteed but delayed |
+
+## References
+
+- [OpenID Connect Back-Channel Logout 1.0](https://openid.net/specs/openid-connect-backchannel-1_0.html)
+- [RFC 7009: OAuth 2.0 Token Revocation](https://tools.ietf.org/html/rfc7009)
+- [Clinch OIDC Discovery](/.well-known/openid-configuration)