forked from sigstore/sigstore
/
device.go
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/
device.go
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//
// Copyright 2021 The Sigstore Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package oauthflow implements OAuth/OIDC support for device and token flows
package oauthflow
import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"net/url"
"strings"
"time"
"github.com/coreos/go-oidc/v3/oidc"
"golang.org/x/oauth2"
)
const (
// SigstoreDeviceURL specifies the Device Code endpoint for the public good Sigstore service
/* #nosec */
// Deprecated: this constant (while correct) should not be used
SigstoreDeviceURL = "https://oauth2.sigstore.dev/auth/device/code"
// SigstoreTokenURL specifies the Token endpoint for the public good Sigstore service
/* #nosec */
// Deprecated: this constant (while correct) should not be used
SigstoreTokenURL = "https://oauth2.sigstore.dev/auth/device/token"
)
type deviceResp struct {
DeviceCode string `json:"device_code"`
UserCode string `json:"user_code"`
VerificationURI string `json:"verification_uri"`
VerificationURIComplete string `json:"verification_uri_complete"`
Interval int `json:"interval"`
ExpiresIn int `json:"expires_in"`
}
type tokenResp struct {
IDToken string `json:"id_token"`
Error string `json:"error"`
}
// DeviceFlowTokenGetter fetches an OIDC Identity token using the Device Code Grant flow as specified in RFC8628
type DeviceFlowTokenGetter struct {
MessagePrinter func(string)
Sleeper func(time.Duration)
Issuer string
codeURL string
}
// NewDeviceFlowTokenGetter creates a new DeviceFlowTokenGetter that retrieves an OIDC Identity Token using a Device Code Grant
// Deprecated: NewDeviceFlowTokenGetter is deprecated; use NewDeviceFlowTokenGetterForIssuer() instead
func NewDeviceFlowTokenGetter(issuer, codeURL, _ string) *DeviceFlowTokenGetter {
return &DeviceFlowTokenGetter{
MessagePrinter: func(s string) { fmt.Println(s) },
Sleeper: time.Sleep,
Issuer: issuer,
codeURL: codeURL,
}
}
// NewDeviceFlowTokenGetterForIssuer creates a new DeviceFlowTokenGetter that retrieves an OIDC Identity Token using a Device Code Grant
func NewDeviceFlowTokenGetterForIssuer(issuer string) *DeviceFlowTokenGetter {
return &DeviceFlowTokenGetter{
MessagePrinter: func(s string) { fmt.Println(s) },
Sleeper: time.Sleep,
Issuer: issuer,
}
}
func (d *DeviceFlowTokenGetter) deviceFlow(p *oidc.Provider, clientID, redirectURL string) (string, error) {
// require that OIDC provider support PKCE to provide sufficient security for the CLI
pkce, err := NewPKCE(p)
if err != nil {
return "", err
}
data := url.Values{
"client_id": []string{clientID},
"scope": []string{"openid email"},
"code_challenge_method": []string{pkce.Method},
"code_challenge": []string{pkce.Challenge},
}
if redirectURL != "" {
// If a redirect uri is provided then use it
data["redirect_uri"] = []string{redirectURL}
}
codeURL, err := d.CodeURL()
if err != nil {
return "", err
}
/* #nosec */
resp, err := http.PostForm(codeURL, data)
if err != nil {
return "", err
}
defer resp.Body.Close()
b, err := io.ReadAll(resp.Body)
if err != nil {
return "", err
}
if resp.StatusCode != http.StatusOK {
return "", fmt.Errorf("%s: %s", resp.Status, b)
}
parsed := deviceResp{}
if err := json.Unmarshal(b, &parsed); err != nil {
return "", err
}
uri := parsed.VerificationURIComplete
if uri == "" {
uri = parsed.VerificationURI
}
d.MessagePrinter(fmt.Sprintf("Enter the verification code %s in your browser at: %s", parsed.UserCode, uri))
d.MessagePrinter(fmt.Sprintf("Code will be valid for %d seconds", parsed.ExpiresIn))
for {
// Some providers use a secret here, we don't need for sigstore oauth one so leave it off.
data := url.Values{
"grant_type": []string{"urn:ietf:params:oauth:grant-type:device_code"},
"device_code": []string{parsed.DeviceCode},
"scope": []string{"openid", "email"},
"code_verifier": []string{pkce.Value},
}
/* #nosec */
resp, err := http.PostForm(p.Endpoint().TokenURL, data)
if err != nil {
return "", err
}
defer resp.Body.Close()
b, err := io.ReadAll(resp.Body)
if err != nil {
return "", err
}
tr := tokenResp{}
if err := json.Unmarshal(b, &tr); err != nil {
return "", err
}
if tr.IDToken != "" {
d.MessagePrinter("Token received!")
return tr.IDToken, nil
}
switch tr.Error {
case "access_denied", "expired_token":
return "", fmt.Errorf("error obtaining token: %s", tr.Error)
case "authorization_pending":
d.Sleeper(time.Duration(parsed.Interval) * time.Second)
case "slow_down":
// Add ten seconds if we got told to slow down
d.Sleeper(time.Duration(parsed.Interval)*time.Second + 10*time.Second)
default:
return "", fmt.Errorf("unexpected error in device flow: %s", tr.Error)
}
}
}
// GetIDToken gets an OIDC ID Token from the specified provider using the device code grant flow
func (d *DeviceFlowTokenGetter) GetIDToken(p *oidc.Provider, cfg oauth2.Config) (*OIDCIDToken, error) {
idToken, err := d.deviceFlow(p, cfg.ClientID, cfg.RedirectURL)
if err != nil {
return nil, err
}
verifier := p.Verifier(&oidc.Config{ClientID: cfg.ClientID})
parsedIDToken, err := verifier.Verify(context.Background(), idToken)
if err != nil {
return nil, err
}
subj, err := SubjectFromToken(parsedIDToken)
if err != nil {
return nil, err
}
return &OIDCIDToken{
RawString: idToken,
Subject: subj,
}, nil
}
// CodeURL fetches the device authorization endpoint URL from the provider's well-known configuration endpoint
func (d *DeviceFlowTokenGetter) CodeURL() (string, error) {
if d.codeURL != "" {
return d.codeURL, nil
}
wellKnown := strings.TrimSuffix(d.Issuer, "/") + "/.well-known/openid-configuration"
/* #nosec */
httpClient := &http.Client{
Timeout: 3 * time.Second,
}
resp, err := httpClient.Get(wellKnown)
if err != nil {
return "", err
}
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
return "", fmt.Errorf("unable to read response body: %w", err)
}
if resp.StatusCode != http.StatusOK {
return "", fmt.Errorf("%s: %s", resp.Status, body)
}
providerConfig := struct {
Issuer string `json:"issuer"`
DeviceEndpoint string `json:"device_authorization_endpoint"`
}{}
if err = json.Unmarshal(body, &providerConfig); err != nil {
return "", fmt.Errorf("oidc: failed to decode provider discovery object: %w", err)
}
if d.Issuer != providerConfig.Issuer {
return "", fmt.Errorf("oidc: issuer did not match the issuer returned by provider, expected %q got %q", d.Issuer, providerConfig.Issuer)
}
if providerConfig.DeviceEndpoint == "" {
return "", fmt.Errorf("oidc: device authorization endpoint not returned by provider")
}
d.codeURL = providerConfig.DeviceEndpoint
return d.codeURL, nil
}