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feat(oauth2): add RFC 8707 resource indicators and audience validation
Implements RFC 8707 Resource Indicators for OAuth2 provider to enable proper audience validation and token binding for multi-tenant scenarios. Key changes: - Add resource parameter support to authorization and token endpoints - Implement server-side audience validation for opaque tokens - Add database fields: ResourceUri (codes) and Audience (tokens) - Add comprehensive resource parameter validation logic - Add cross-resource audience validation in API middleware - Add extensive test coverage for RFC 8707 scenarios - Enhance PKCE implementation with timing attack protection This enables OAuth2 clients to specify target resource servers and prevents token abuse across different Coder deployments through proper audience binding. Change-Id: I3924cb2139e837e3ac0b0bd40a5aeb59637ebc1b Signed-off-by: Thomas Kosiewski <tk@coder.com>
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‎CLAUDE.md

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@@ -120,6 +120,29 @@ Read [cursor rules](.cursorrules).
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4. Run `make gen` again
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5. Run `make lint` to catch any remaining issues
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### In-Memory Database Testing
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When adding new database fields:
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- **CRITICAL**: Update `coderd/database/dbmem/dbmem.go` in-memory implementations
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- The `Insert*` functions must include ALL new fields, not just basic ones
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- Common issue: Tests pass with real database but fail with in-memory database due to missing field mappings
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- Always verify in-memory database functions match the real database schema after migrations
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Example pattern:
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```go
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// In dbmem.go - ensure ALL fields are included
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code := database.OAuth2ProviderAppCode{
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ID: arg.ID,
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CreatedAt: arg.CreatedAt,
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// ... existing fields ...
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ResourceUri: arg.ResourceUri, // New field
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CodeChallenge: arg.CodeChallenge, // New field
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CodeChallengeMethod: arg.CodeChallengeMethod, // New field
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}
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```
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## Architecture
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### Core Components
@@ -204,6 +227,12 @@ When working on OAuth2 provider features:
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- Avoid dependency on referer headers for security decisions
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- Support proper state parameter validation
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6. **RFC 8707 Resource Indicators**:
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- Store resource parameters in database for server-side validation (opaque tokens)
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- Validate resource consistency between authorization and token requests
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- Support audience validation in refresh token flows
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- Resource parameter is optional but must be consistent when provided
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### OAuth2 Error Handling Pattern
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```go
@@ -258,3 +287,6 @@ Always run the full test suite after OAuth2 changes:
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2. **"package should be X_test"** - Use `package_test` naming for test files
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3. **SQL type errors** - Use `sql.Null*` types for nullable fields
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4. **Missing newlines** - Ensure files end with newline character
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5. **OAuth2 tests failing but scripts working** - Check in-memory database implementations in `dbmem.go`
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6. **Resource indicator validation failing** - Ensure database stores and retrieves resource parameters correctly
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7. **PKCE tests failing** - Verify both authorization code storage and token exchange handle PKCE fields

‎coderd/database/dbauthz/dbauthz.go

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@@ -2165,6 +2165,25 @@ func (q *querier) GetOAuth2ProviderAppSecretsByAppID(ctx context.Context, appID
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return q.db.GetOAuth2ProviderAppSecretsByAppID(ctx, appID)
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}
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func (q *querier) GetOAuth2ProviderAppTokenByAPIKeyID(ctx context.Context, apiKeyID string) (database.OAuth2ProviderAppToken, error) {
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token, err := q.db.GetOAuth2ProviderAppTokenByAPIKeyID(ctx, apiKeyID)
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if err != nil {
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return database.OAuth2ProviderAppToken{}, err
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}
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// Get the associated API key to check ownership
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apiKey, err := q.db.GetAPIKeyByID(ctx, token.APIKeyID)
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if err != nil {
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return database.OAuth2ProviderAppToken{}, err
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}
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if err := q.authorizeContext(ctx, policy.ActionRead, rbac.ResourceOauth2AppCodeToken.WithOwner(apiKey.UserID.String())); err != nil {
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return database.OAuth2ProviderAppToken{}, err
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}
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return token, nil
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}
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func (q *querier) GetOAuth2ProviderAppTokenByPrefix(ctx context.Context, hashPrefix []byte) (database.OAuth2ProviderAppToken, error) {
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token, err := q.db.GetOAuth2ProviderAppTokenByPrefix(ctx, hashPrefix)
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if err != nil {

‎coderd/database/dbmem/dbmem.go

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@@ -4050,6 +4050,19 @@ func (q *FakeQuerier) GetOAuth2ProviderAppSecretsByAppID(_ context.Context, appI
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return []database.OAuth2ProviderAppSecret{}, sql.ErrNoRows
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}
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func (q *FakeQuerier) GetOAuth2ProviderAppTokenByAPIKeyID(_ context.Context, apiKeyID string) (database.OAuth2ProviderAppToken, error) {
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q.mutex.Lock()
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defer q.mutex.Unlock()
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for _, token := range q.oauth2ProviderAppTokens {
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if token.APIKeyID == apiKeyID {
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return token, nil
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}
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}
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return database.OAuth2ProviderAppToken{}, sql.ErrNoRows
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}
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func (q *FakeQuerier) GetOAuth2ProviderAppTokenByPrefix(_ context.Context, hashPrefix []byte) (database.OAuth2ProviderAppToken, error) {
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q.mutex.Lock()
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defer q.mutex.Unlock()
@@ -8938,13 +8951,16 @@ func (q *FakeQuerier) InsertOAuth2ProviderAppCode(_ context.Context, arg databas
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for _, app := range q.oauth2ProviderApps {
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if app.ID == arg.AppID {
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code := database.OAuth2ProviderAppCode{
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ID: arg.ID,
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CreatedAt: arg.CreatedAt,
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ExpiresAt: arg.ExpiresAt,
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SecretPrefix: arg.SecretPrefix,
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HashedSecret: arg.HashedSecret,
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UserID: arg.UserID,
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AppID: arg.AppID,
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ID: arg.ID,
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CreatedAt: arg.CreatedAt,
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ExpiresAt: arg.ExpiresAt,
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SecretPrefix: arg.SecretPrefix,
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HashedSecret: arg.HashedSecret,
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UserID: arg.UserID,
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AppID: arg.AppID,
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ResourceUri: arg.ResourceUri,
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CodeChallenge: arg.CodeChallenge,
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CodeChallengeMethod: arg.CodeChallengeMethod,
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}
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q.oauth2ProviderAppCodes = append(q.oauth2ProviderAppCodes, code)
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return code, nil

‎coderd/database/dbmetrics/querymetrics.go

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‎coderd/database/dbmock/dbmock.go

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‎coderd/database/querier.go

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‎coderd/database/queries.sql.go

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‎coderd/database/queries/oauth2.sql

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@@ -136,6 +136,9 @@ INSERT INTO oauth2_provider_app_tokens (
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-- name: GetOAuth2ProviderAppTokenByPrefix :one
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SELECT * FROM oauth2_provider_app_tokens WHERE hash_prefix = $1;
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-- name: GetOAuth2ProviderAppTokenByAPIKeyID :one
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SELECT * FROM oauth2_provider_app_tokens WHERE api_key_id = $1;
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-- name: GetOAuth2ProviderAppsByUserID :many
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SELECT
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COUNT(DISTINCT oauth2_provider_app_tokens.id) as token_count,

‎coderd/httpmw/apikey.go

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@@ -240,6 +240,16 @@ func ExtractAPIKey(rw http.ResponseWriter, r *http.Request, cfg ExtractAPIKeyCon
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})
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}
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// Validate OAuth2 provider app token audience (RFC 8707) if applicable
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if key.LoginType == database.LoginTypeOAuth2ProviderApp {
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if err := validateOAuth2ProviderAppTokenAudience(ctx, cfg.DB, *key, r); err != nil {
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return optionalWrite(http.StatusForbidden, codersdk.Response{
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Message: "Token audience mismatch",
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Detail: err.Error(),
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})
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}
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}
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// We only check OIDC stuff if we have a valid APIKey. An expired key means we don't trust the requestor
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// really is the user whose key they have, and so we shouldn't be doing anything on their behalf including possibly
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// refreshing the OIDC token.
@@ -446,6 +456,47 @@ func ExtractAPIKey(rw http.ResponseWriter, r *http.Request, cfg ExtractAPIKeyCon
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return key, &actor, true
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}
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// validateOAuth2ProviderAppTokenAudience validates that an OAuth2 provider app token
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// is being used with the correct audience/resource server (RFC 8707).
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func validateOAuth2ProviderAppTokenAudience(ctx context.Context, db database.Store, key database.APIKey, r *http.Request) error {
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// Get the OAuth2 provider app token to check its audience
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//nolint:gocritic // System needs to access token for audience validation
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token, err := db.GetOAuth2ProviderAppTokenByAPIKeyID(dbauthz.AsSystemRestricted(ctx), key.ID)
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if err != nil {
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return xerrors.Errorf("failed to get OAuth2 token: %w", err)
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}
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// If no audience is set, allow the request (for backward compatibility)
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if !token.Audience.Valid || token.Audience.String == "" {
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return nil
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}
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// Extract the expected audience from the request
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expectedAudience := extractExpectedAudience(r)
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// Validate that the token's audience matches the expected audience
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if token.Audience.String != expectedAudience {
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return xerrors.Errorf("token audience %q does not match expected audience %q",
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token.Audience.String, expectedAudience)
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}
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return nil
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}
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// extractExpectedAudience determines the expected audience for the current request.
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// This should match the resource parameter used during authorization.
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func extractExpectedAudience(r *http.Request) string {
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// For MCP compliance, the audience should be the canonical URI of the resource server
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// This typically matches the access URL of the Coder deployment
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scheme := "https"
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if r.TLS == nil {
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scheme = "http"
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}
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// Use the Host header to construct the canonical audience URI
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return fmt.Sprintf("%s://%s", scheme, r.Host)
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}
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// UserRBACSubject fetches a user's rbac.Subject from the database. It pulls all roles from both
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// site and organization scopes. It also pulls the groups, and the user's status.
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func UserRBACSubject(ctx context.Context, db database.Store, userID uuid.UUID, scope rbac.ExpandableScope) (rbac.Subject, database.UserStatus, error) {

‎coderd/identityprovider/authorize.go

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@@ -44,6 +44,15 @@ func extractAuthorizeParams(r *http.Request, callbackURL *url.URL) (authorizePar
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codeChallenge: p.String(vals, "", "code_challenge"),
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codeChallengeMethod: p.String(vals, "", "code_challenge_method"),
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}
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// Validate resource indicator syntax (RFC 8707): must be absolute URI without fragment
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if params.resource != "" {
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if u, err := url.Parse(params.resource); err != nil || u.Scheme == "" || u.Fragment != "" {
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p.Errors = append(p.Errors, codersdk.ValidationError{
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Field: "resource",
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Detail: "must be an absolute URI without fragment",
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})
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}
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}
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p.ErrorExcessParams(vals)
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if len(p.Errors) > 0 {

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