410 lines
12 KiB
Go
410 lines
12 KiB
Go
// Package oidc implements OpenID Connect client logic for the golang.org/x/oauth2 package.
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package oidc
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import (
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"context"
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"crypto/sha256"
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"crypto/sha512"
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"encoding/base64"
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"encoding/json"
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"errors"
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"fmt"
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"hash"
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"io/ioutil"
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"mime"
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"net/http"
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"strings"
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"time"
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"golang.org/x/oauth2"
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jose "gopkg.in/square/go-jose.v2"
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)
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const (
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// ScopeOpenID is the mandatory scope for all OpenID Connect OAuth2 requests.
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ScopeOpenID = "openid"
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// ScopeOfflineAccess is an optional scope defined by OpenID Connect for requesting
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// OAuth2 refresh tokens.
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//
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// Support for this scope differs between OpenID Connect providers. For instance
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// Google rejects it, favoring appending "access_type=offline" as part of the
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// authorization request instead.
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//
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// See: https://openid.net/specs/openid-connect-core-1_0.html#OfflineAccess
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ScopeOfflineAccess = "offline_access"
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)
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var (
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errNoAtHash = errors.New("id token did not have an access token hash")
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errInvalidAtHash = errors.New("access token hash does not match value in ID token")
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)
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// ClientContext returns a new Context that carries the provided HTTP client.
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//
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// This method sets the same context key used by the golang.org/x/oauth2 package,
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// so the returned context works for that package too.
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//
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// myClient := &http.Client{}
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// ctx := oidc.ClientContext(parentContext, myClient)
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//
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// // This will use the custom client
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// provider, err := oidc.NewProvider(ctx, "https://accounts.example.com")
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//
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func ClientContext(ctx context.Context, client *http.Client) context.Context {
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return context.WithValue(ctx, oauth2.HTTPClient, client)
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}
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func doRequest(ctx context.Context, req *http.Request) (*http.Response, error) {
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client := http.DefaultClient
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if c, ok := ctx.Value(oauth2.HTTPClient).(*http.Client); ok {
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client = c
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}
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return client.Do(req.WithContext(ctx))
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}
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// Provider represents an OpenID Connect server's configuration.
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type Provider struct {
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issuer string
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authURL string
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tokenURL string
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userInfoURL string
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algorithms []string
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// Raw claims returned by the server.
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rawClaims []byte
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remoteKeySet KeySet
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}
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type cachedKeys struct {
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keys []jose.JSONWebKey
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expiry time.Time
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}
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type providerJSON struct {
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Issuer string `json:"issuer"`
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AuthURL string `json:"authorization_endpoint"`
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TokenURL string `json:"token_endpoint"`
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JWKSURL string `json:"jwks_uri"`
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UserInfoURL string `json:"userinfo_endpoint"`
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Algorithms []string `json:"id_token_signing_alg_values_supported"`
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}
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// supportedAlgorithms is a list of algorithms explicitly supported by this
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// package. If a provider supports other algorithms, such as HS256 or none,
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// those values won't be passed to the IDTokenVerifier.
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var supportedAlgorithms = map[string]bool{
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RS256: true,
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RS384: true,
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RS512: true,
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ES256: true,
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ES384: true,
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ES512: true,
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PS256: true,
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PS384: true,
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PS512: true,
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}
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// NewProvider uses the OpenID Connect discovery mechanism to construct a Provider.
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//
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// The issuer is the URL identifier for the service. For example: "https://accounts.google.com"
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// or "https://login.salesforce.com".
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func NewProvider(ctx context.Context, issuer string) (*Provider, error) {
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wellKnown := strings.TrimSuffix(issuer, "/") + "/.well-known/openid-configuration"
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req, err := http.NewRequest("GET", wellKnown, nil)
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if err != nil {
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return nil, err
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}
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resp, err := doRequest(ctx, req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return nil, fmt.Errorf("unable to read response body: %v", err)
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("%s: %s", resp.Status, body)
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}
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var p providerJSON
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err = unmarshalResp(resp, body, &p)
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if err != nil {
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return nil, fmt.Errorf("oidc: failed to decode provider discovery object: %v", err)
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}
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if p.Issuer != issuer {
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return nil, fmt.Errorf("oidc: issuer did not match the issuer returned by provider, expected %q got %q", issuer, p.Issuer)
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}
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var algs []string
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for _, a := range p.Algorithms {
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if supportedAlgorithms[a] {
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algs = append(algs, a)
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}
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}
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return &Provider{
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issuer: p.Issuer,
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authURL: p.AuthURL,
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tokenURL: p.TokenURL,
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userInfoURL: p.UserInfoURL,
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algorithms: algs,
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rawClaims: body,
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remoteKeySet: NewRemoteKeySet(ctx, p.JWKSURL),
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}, nil
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}
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// Claims unmarshals raw fields returned by the server during discovery.
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//
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// var claims struct {
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// ScopesSupported []string `json:"scopes_supported"`
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// ClaimsSupported []string `json:"claims_supported"`
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// }
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//
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// if err := provider.Claims(&claims); err != nil {
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// // handle unmarshaling error
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// }
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//
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// For a list of fields defined by the OpenID Connect spec see:
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// https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderMetadata
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func (p *Provider) Claims(v interface{}) error {
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if p.rawClaims == nil {
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return errors.New("oidc: claims not set")
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}
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return json.Unmarshal(p.rawClaims, v)
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}
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// Endpoint returns the OAuth2 auth and token endpoints for the given provider.
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func (p *Provider) Endpoint() oauth2.Endpoint {
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return oauth2.Endpoint{AuthURL: p.authURL, TokenURL: p.tokenURL}
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}
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// UserInfo represents the OpenID Connect userinfo claims.
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type UserInfo struct {
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Subject string `json:"sub"`
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Profile string `json:"profile"`
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Email string `json:"email"`
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EmailVerified bool `json:"email_verified"`
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claims []byte
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}
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// Claims unmarshals the raw JSON object claims into the provided object.
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func (u *UserInfo) Claims(v interface{}) error {
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if u.claims == nil {
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return errors.New("oidc: claims not set")
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}
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return json.Unmarshal(u.claims, v)
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}
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// UserInfo uses the token source to query the provider's user info endpoint.
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func (p *Provider) UserInfo(ctx context.Context, tokenSource oauth2.TokenSource) (*UserInfo, error) {
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if p.userInfoURL == "" {
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return nil, errors.New("oidc: user info endpoint is not supported by this provider")
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}
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req, err := http.NewRequest("GET", p.userInfoURL, nil)
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if err != nil {
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return nil, fmt.Errorf("oidc: create GET request: %v", err)
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}
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token, err := tokenSource.Token()
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if err != nil {
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return nil, fmt.Errorf("oidc: get access token: %v", err)
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}
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token.SetAuthHeader(req)
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resp, err := doRequest(ctx, req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("%s: %s", resp.Status, body)
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}
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var userInfo UserInfo
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if err := json.Unmarshal(body, &userInfo); err != nil {
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return nil, fmt.Errorf("oidc: failed to decode userinfo: %v", err)
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}
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userInfo.claims = body
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return &userInfo, nil
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}
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// IDToken is an OpenID Connect extension that provides a predictable representation
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// of an authorization event.
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//
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// The ID Token only holds fields OpenID Connect requires. To access additional
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// claims returned by the server, use the Claims method.
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type IDToken struct {
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// The URL of the server which issued this token. OpenID Connect
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// requires this value always be identical to the URL used for
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// initial discovery.
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//
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// Note: Because of a known issue with Google Accounts' implementation
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// this value may differ when using Google.
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//
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// See: https://developers.google.com/identity/protocols/OpenIDConnect#obtainuserinfo
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Issuer string
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// The client ID, or set of client IDs, that this token is issued for. For
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// common uses, this is the client that initialized the auth flow.
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//
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// This package ensures the audience contains an expected value.
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Audience []string
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// A unique string which identifies the end user.
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Subject string
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// Expiry of the token. Ths package will not process tokens that have
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// expired unless that validation is explicitly turned off.
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Expiry time.Time
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// When the token was issued by the provider.
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IssuedAt time.Time
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// Initial nonce provided during the authentication redirect.
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//
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// This package does NOT provided verification on the value of this field
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// and it's the user's responsibility to ensure it contains a valid value.
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Nonce string
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// at_hash claim, if set in the ID token. Callers can verify an access token
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// that corresponds to the ID token using the VerifyAccessToken method.
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AccessTokenHash string
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// signature algorithm used for ID token, needed to compute a verification hash of an
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// access token
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sigAlgorithm string
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// Raw payload of the id_token.
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claims []byte
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// Map of distributed claim names to claim sources
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distributedClaims map[string]claimSource
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}
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// Claims unmarshals the raw JSON payload of the ID Token into a provided struct.
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//
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// idToken, err := idTokenVerifier.Verify(rawIDToken)
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// if err != nil {
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// // handle error
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// }
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// var claims struct {
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// Email string `json:"email"`
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// EmailVerified bool `json:"email_verified"`
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// }
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// if err := idToken.Claims(&claims); err != nil {
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// // handle error
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// }
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//
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func (i *IDToken) Claims(v interface{}) error {
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if i.claims == nil {
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return errors.New("oidc: claims not set")
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}
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return json.Unmarshal(i.claims, v)
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}
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// VerifyAccessToken verifies that the hash of the access token that corresponds to the iD token
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// matches the hash in the id token. It returns an error if the hashes don't match.
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// It is the caller's responsibility to ensure that the optional access token hash is present for the ID token
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// before calling this method. See https://openid.net/specs/openid-connect-core-1_0.html#CodeIDToken
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func (i *IDToken) VerifyAccessToken(accessToken string) error {
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if i.AccessTokenHash == "" {
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return errNoAtHash
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}
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var h hash.Hash
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switch i.sigAlgorithm {
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case RS256, ES256, PS256:
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h = sha256.New()
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case RS384, ES384, PS384:
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h = sha512.New384()
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case RS512, ES512, PS512:
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h = sha512.New()
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default:
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return fmt.Errorf("oidc: unsupported signing algorithm %q", i.sigAlgorithm)
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}
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h.Write([]byte(accessToken)) // hash documents that Write will never return an error
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sum := h.Sum(nil)[:h.Size()/2]
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actual := base64.RawURLEncoding.EncodeToString(sum)
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if actual != i.AccessTokenHash {
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return errInvalidAtHash
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}
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return nil
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}
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type idToken struct {
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Issuer string `json:"iss"`
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Subject string `json:"sub"`
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Audience audience `json:"aud"`
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Expiry jsonTime `json:"exp"`
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IssuedAt jsonTime `json:"iat"`
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NotBefore *jsonTime `json:"nbf"`
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Nonce string `json:"nonce"`
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AtHash string `json:"at_hash"`
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ClaimNames map[string]string `json:"_claim_names"`
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ClaimSources map[string]claimSource `json:"_claim_sources"`
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}
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type claimSource struct {
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Endpoint string `json:"endpoint"`
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AccessToken string `json:"access_token"`
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}
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type audience []string
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func (a *audience) UnmarshalJSON(b []byte) error {
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var s string
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if json.Unmarshal(b, &s) == nil {
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*a = audience{s}
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return nil
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}
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var auds []string
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if err := json.Unmarshal(b, &auds); err != nil {
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return err
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}
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*a = audience(auds)
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return nil
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}
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type jsonTime time.Time
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func (j *jsonTime) UnmarshalJSON(b []byte) error {
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var n json.Number
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if err := json.Unmarshal(b, &n); err != nil {
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return err
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}
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var unix int64
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if t, err := n.Int64(); err == nil {
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unix = t
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} else {
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f, err := n.Float64()
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if err != nil {
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return err
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}
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unix = int64(f)
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}
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*j = jsonTime(time.Unix(unix, 0))
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return nil
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}
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func unmarshalResp(r *http.Response, body []byte, v interface{}) error {
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err := json.Unmarshal(body, &v)
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if err == nil {
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return nil
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}
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ct := r.Header.Get("Content-Type")
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mediaType, _, parseErr := mime.ParseMediaType(ct)
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if parseErr == nil && mediaType == "application/json" {
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return fmt.Errorf("got Content-Type = application/json, but could not unmarshal as JSON: %v", err)
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}
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return fmt.Errorf("expected Content-Type = application/json, got %q: %v", ct, err)
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}
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