286 lines
8.7 KiB
Go
286 lines
8.7 KiB
Go
package oidcauth
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"strings"
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"time"
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"github.com/coreos/go-oidc"
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"github.com/hashicorp/go-uuid"
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"golang.org/x/oauth2"
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)
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var (
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oidcStateTimeout = 10 * time.Minute
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oidcStateCleanupInterval = 1 * time.Minute
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)
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// GetAuthCodeURL is the first part of the OIDC authorization code workflow.
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// The statePayload field is stored in the Authenticator instance keyed by the
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// "state" key so it can be returned during a future call to
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// ClaimsFromAuthCode.
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//
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// Requires the authenticator's config type be set to 'oidc'.
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func (a *Authenticator) GetAuthCodeURL(ctx context.Context, redirectURI string, statePayload interface{}) (string, error) {
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if a.config.authType() != authOIDCFlow {
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return "", fmt.Errorf("GetAuthCodeURL is incompatible with type %q", TypeJWT)
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}
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if redirectURI == "" {
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return "", errors.New("missing redirect_uri")
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}
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if !validRedirect(redirectURI, a.config.AllowedRedirectURIs) {
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return "", fmt.Errorf("unauthorized redirect_uri: %s", redirectURI)
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}
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// "openid" is a required scope for OpenID Connect flows
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scopes := append([]string{oidc.ScopeOpenID}, a.config.OIDCScopes...)
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// Configure an OpenID Connect aware OAuth2 client
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oauth2Config := oauth2.Config{
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ClientID: a.config.OIDCClientID,
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ClientSecret: a.config.OIDCClientSecret,
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RedirectURL: redirectURI,
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Endpoint: a.provider.Endpoint(),
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Scopes: scopes,
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}
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stateID, nonce, err := a.createOIDCState(redirectURI, statePayload)
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if err != nil {
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return "", fmt.Errorf("error generating OAuth state: %v", err)
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}
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authCodeOpts := []oauth2.AuthCodeOption{
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oidc.Nonce(nonce),
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}
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if len(a.config.OIDCACRValues) > 0 {
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authCodeOpts = append(authCodeOpts, oauth2.SetAuthURLParam("acr_values", strings.Join(a.config.OIDCACRValues, " ")))
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}
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return oauth2Config.AuthCodeURL(stateID, authCodeOpts...), nil
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}
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// ClaimsFromAuthCode is the second part of the OIDC authorization code
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// workflow. The interface{} return value is the statePayload previously passed
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// via GetAuthCodeURL.
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//
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// The error may be of type *ProviderLoginFailedError or
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// *TokenVerificationFailedError which can be detected via errors.As().
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//
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// Requires the authenticator's config type be set to 'oidc'.
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func (a *Authenticator) ClaimsFromAuthCode(ctx context.Context, stateParam, code string) (*Claims, interface{}, error) {
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if a.config.authType() != authOIDCFlow {
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return nil, nil, fmt.Errorf("ClaimsFromAuthCode is incompatible with type %q", TypeJWT)
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}
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// TODO(sso): this could be because we ACTUALLY are getting OIDC error responses and
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// should handle them elsewhere!
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if code == "" {
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return nil, nil, &ProviderLoginFailedError{
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Err: fmt.Errorf("OAuth code parameter not provided"),
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}
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}
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state := a.verifyOIDCState(stateParam)
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if state == nil {
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return nil, nil, &ProviderLoginFailedError{
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Err: fmt.Errorf("Expired or missing OAuth state."),
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}
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}
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oidcCtx := contextWithHttpClient(ctx, a.httpClient)
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var oauth2Config = oauth2.Config{
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ClientID: a.config.OIDCClientID,
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ClientSecret: a.config.OIDCClientSecret,
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RedirectURL: state.redirectURI,
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Endpoint: a.provider.Endpoint(),
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Scopes: []string{oidc.ScopeOpenID},
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}
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oauth2Token, err := oauth2Config.Exchange(oidcCtx, code)
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if err != nil {
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return nil, nil, &ProviderLoginFailedError{
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Err: fmt.Errorf("Error exchanging oidc code: %w", err),
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}
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}
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// Extract the ID Token from OAuth2 token.
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rawToken, ok := oauth2Token.Extra("id_token").(string)
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if !ok {
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return nil, nil, &TokenVerificationFailedError{
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Err: errors.New("No id_token found in response."),
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}
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}
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if a.config.VerboseOIDCLogging && a.logger != nil {
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a.logger.Debug("OIDC provider response", "ID token", rawToken)
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}
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// Parse and verify ID Token payload.
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allClaims, err := a.verifyOIDCToken(ctx, rawToken) // TODO(sso): should this use oidcCtx?
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if err != nil {
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return nil, nil, &TokenVerificationFailedError{
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Err: err,
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}
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}
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if allClaims["nonce"] != state.nonce { // TODO(sso): does this need a cast?
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return nil, nil, &TokenVerificationFailedError{
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Err: errors.New("Invalid ID token nonce."),
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}
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}
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delete(allClaims, "nonce")
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// Attempt to fetch information from the /userinfo endpoint and merge it with
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// the existing claims data. A failure to fetch additional information from this
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// endpoint will not invalidate the authorization flow.
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if userinfo, err := a.provider.UserInfo(oidcCtx, oauth2.StaticTokenSource(oauth2Token)); err == nil {
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_ = userinfo.Claims(&allClaims)
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} else {
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if a.logger != nil {
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logFunc := a.logger.Warn
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if strings.Contains(err.Error(), "user info endpoint is not supported") {
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logFunc = a.logger.Info
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}
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logFunc("error reading /userinfo endpoint", "error", err)
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}
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}
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if a.config.VerboseOIDCLogging && a.logger != nil {
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if c, err := json.Marshal(allClaims); err == nil {
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a.logger.Debug("OIDC provider response", "claims", string(c))
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} else {
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a.logger.Debug("OIDC provider response", "marshalling error", err.Error())
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}
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}
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c, err := a.extractClaims(allClaims)
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if err != nil {
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return nil, nil, &TokenVerificationFailedError{
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Err: err,
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}
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}
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if a.config.VerboseOIDCLogging && a.logger != nil {
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a.logger.Debug("OIDC provider response", "extracted_claims", c)
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}
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return c, state.payload, nil
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}
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// ProviderLoginFailedError is an error type sometimes returned from
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// ClaimsFromAuthCode().
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//
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// It represents a failure to complete the authorization code workflow with the
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// provider such as losing important OIDC parameters or a failure to fetch an
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// id_token.
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//
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// You can check for it with errors.As().
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type ProviderLoginFailedError struct {
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Err error
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}
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func (e *ProviderLoginFailedError) Error() string {
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return fmt.Sprintf("Provider login failed: %v", e.Err)
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}
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func (e *ProviderLoginFailedError) Unwrap() error { return e.Err }
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// TokenVerificationFailedError is an error type sometimes returned from
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// ClaimsFromAuthCode().
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//
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// It represents a failure to vet the returned OIDC credentials for validity
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// such as the id_token not passing verification or using an mismatched nonce.
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//
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// You can check for it with errors.As().
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type TokenVerificationFailedError struct {
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Err error
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}
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func (e *TokenVerificationFailedError) Error() string {
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return fmt.Sprintf("Token verification failed: %v", e.Err)
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}
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func (e *TokenVerificationFailedError) Unwrap() error { return e.Err }
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func (a *Authenticator) verifyOIDCToken(ctx context.Context, rawToken string) (map[string]interface{}, error) {
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allClaims := make(map[string]interface{})
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oidcConfig := &oidc.Config{
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SupportedSigningAlgs: a.config.JWTSupportedAlgs,
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}
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switch a.config.authType() {
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case authOIDCFlow:
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oidcConfig.ClientID = a.config.OIDCClientID
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case authOIDCDiscovery:
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oidcConfig.SkipClientIDCheck = true
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default:
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return nil, fmt.Errorf("unsupported auth type for this verifyOIDCToken: %d", a.config.authType())
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}
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verifier := a.provider.Verifier(oidcConfig)
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idToken, err := verifier.Verify(ctx, rawToken)
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if err != nil {
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return nil, fmt.Errorf("error validating signature: %v", err)
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}
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if err := idToken.Claims(&allClaims); err != nil {
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return nil, fmt.Errorf("unable to successfully parse all claims from token: %v", err)
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}
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// TODO(sso): why isn't this strict for OIDC?
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if err := validateAudience(a.config.BoundAudiences, idToken.Audience, false); err != nil {
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return nil, fmt.Errorf("error validating claims: %v", err)
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}
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return allClaims, nil
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}
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// verifyOIDCState tests whether the provided state ID is valid and returns the
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// associated state object if so. A nil state is returned if the ID is not found
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// or expired. The state should only ever be retrieved once and is deleted as
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// part of this request.
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func (a *Authenticator) verifyOIDCState(stateID string) *oidcState {
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defer a.oidcStates.Delete(stateID)
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if stateRaw, ok := a.oidcStates.Get(stateID); ok {
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return stateRaw.(*oidcState)
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}
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return nil
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}
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// createOIDCState make an expiring state object, associated with a random state ID
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// that is passed throughout the OAuth process. A nonce is also included in the
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// auth process, and for simplicity will be identical in length/format as the state ID.
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func (a *Authenticator) createOIDCState(redirectURI string, payload interface{}) (string, string, error) {
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// Get enough bytes for 2 160-bit IDs (per rfc6749#section-10.10)
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bytes, err := uuid.GenerateRandomBytes(2 * 20)
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if err != nil {
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return "", "", err
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}
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stateID := fmt.Sprintf("%x", bytes[:20])
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nonce := fmt.Sprintf("%x", bytes[20:])
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a.oidcStates.SetDefault(stateID, &oidcState{
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nonce: nonce,
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redirectURI: redirectURI,
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payload: payload,
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})
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return stateID, nonce, nil
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}
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// oidcState is created when an authURL is requested. The state
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// identifier is passed throughout the OAuth process.
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type oidcState struct {
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nonce string
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redirectURI string
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payload interface{}
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}
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