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package azure
/*
This file is largely based on rjw57/oauth2device's code, with the follow differences:
* scope -> resource, and only allow a single one
* receive "Message" in the DeviceCode struct and show it to users as the prompt
* azure-xplat-cli has the following behavior that this emulates:
- does not send client_secret during the token exchange
- sends resource again in the token exchange request
*/
import (
"fmt"
"net/http"
"net/url"
"time"
"github.com/Azure/go-autorest/autorest"
)
const (
logPrefix = "autorest/azure/devicetoken:"
)
var (
// ErrDeviceGeneric represents an unknown error from the token endpoint when using device flow
ErrDeviceGeneric = fmt.Errorf("%s Error while retrieving OAuth token: Unknown Error", logPrefix)
// ErrDeviceAccessDenied represents an access denied error from the token endpoint when using device flow
ErrDeviceAccessDenied = fmt.Errorf("%s Error while retrieving OAuth token: Access Denied", logPrefix)
// ErrDeviceAuthorizationPending represents the server waiting on the user to complete the device flow
ErrDeviceAuthorizationPending = fmt.Errorf("%s Error while retrieving OAuth token: Authorization Pending", logPrefix)
// ErrDeviceCodeExpired represents the server timing out and expiring the code during device flow
ErrDeviceCodeExpired = fmt.Errorf("%s Error while retrieving OAuth token: Code Expired", logPrefix)
// ErrDeviceSlowDown represents the service telling us we're polling too often during device flow
ErrDeviceSlowDown = fmt.Errorf("%s Error while retrieving OAuth token: Slow Down", logPrefix)
errCodeSendingFails = "Error occurred while sending request for Device Authorization Code"
errCodeHandlingFails = "Error occurred while handling response from the Device Endpoint"
errTokenSendingFails = "Error occurred while sending request with device code for a token"
errTokenHandlingFails = "Error occurred while handling response from the Token Endpoint (during device flow)"
)
// DeviceCode is the object returned by the device auth endpoint
// It contains information to instruct the user to complete the auth flow
type DeviceCode struct {
DeviceCode *string `json:"device_code,omitempty"`
UserCode *string `json:"user_code,omitempty"`
VerificationURL *string `json:"verification_url,omitempty"`
ExpiresIn *int64 `json:"expires_in,string,omitempty"`
Interval *int64 `json:"interval,string,omitempty"`
Message *string `json:"message"` // Azure specific
Resource string // store the following, stored when initiating, used when exchanging
OAuthConfig OAuthConfig
ClientID string
}
// TokenError is the object returned by the token exchange endpoint
// when something is amiss
type TokenError struct {
Error *string `json:"error,omitempty"`
ErrorCodes []int `json:"error_codes,omitempty"`
ErrorDescription *string `json:"error_description,omitempty"`
Timestamp *string `json:"timestamp,omitempty"`
TraceID *string `json:"trace_id,omitempty"`
}
// DeviceToken is the object return by the token exchange endpoint
// It can either look like a Token or an ErrorToken, so put both here
// and check for presence of "Error" to know if we are in error state
type deviceToken struct {
Token
TokenError
}
// InitiateDeviceAuth initiates a device auth flow. It returns a DeviceCode
// that can be used with CheckForUserCompletion or WaitForUserCompletion.
func InitiateDeviceAuth(client *autorest.Client, oauthConfig OAuthConfig, clientID, resource string) (*DeviceCode, error) {
req, _ := autorest.Prepare(
&http.Request{},
autorest.AsPost(),
autorest.AsFormURLEncoded(),
autorest.WithBaseURL(oauthConfig.DeviceCodeEndpoint.String()),
autorest.WithFormData(url.Values{
"client_id": []string{clientID},
"resource": []string{resource},
}),
)
resp, err := autorest.SendWithSender(client, req)
if err != nil {
return nil, fmt.Errorf("%s %s: %s", logPrefix, errCodeSendingFails, err)
}
var code DeviceCode
err = autorest.Respond(
resp,
autorest.WithErrorUnlessStatusCode(http.StatusOK),
autorest.ByUnmarshallingJSON(&code),
autorest.ByClosing())
if err != nil {
return nil, fmt.Errorf("%s %s: %s", logPrefix, errCodeHandlingFails, err)
}
code.ClientID = clientID
code.Resource = resource
code.OAuthConfig = oauthConfig
return &code, nil
}
// CheckForUserCompletion takes a DeviceCode and checks with the Azure AD OAuth endpoint
// to see if the device flow has: been completed, timed out, or otherwise failed
func CheckForUserCompletion(client *autorest.Client, code *DeviceCode) (*Token, error) {
req, _ := autorest.Prepare(
&http.Request{},
autorest.AsPost(),
autorest.AsFormURLEncoded(),
autorest.WithBaseURL(code.OAuthConfig.TokenEndpoint.String()),
autorest.WithFormData(url.Values{
"client_id": []string{code.ClientID},
"code": []string{*code.DeviceCode},
"grant_type": []string{OAuthGrantTypeDeviceCode},
"resource": []string{code.Resource},
}),
)
resp, err := autorest.SendWithSender(client, req)
if err != nil {
return nil, fmt.Errorf("%s %s: %s", logPrefix, errTokenSendingFails, err)
}
var token deviceToken
err = autorest.Respond(
resp,
autorest.WithErrorUnlessStatusCode(http.StatusOK, http.StatusBadRequest),
autorest.ByUnmarshallingJSON(&token),
autorest.ByClosing())
if err != nil {
return nil, fmt.Errorf("%s %s: %s", logPrefix, errTokenHandlingFails, err)
}
if token.Error == nil {
return &token.Token, nil
}
switch *token.Error {
case "authorization_pending":
return nil, ErrDeviceAuthorizationPending
case "slow_down":
return nil, ErrDeviceSlowDown
case "access_denied":
return nil, ErrDeviceAccessDenied
case "code_expired":
return nil, ErrDeviceCodeExpired
default:
return nil, ErrDeviceGeneric
}
}
// WaitForUserCompletion calls CheckForUserCompletion repeatedly until a token is granted or an error state occurs.
// This prevents the user from looping and checking against 'ErrDeviceAuthorizationPending'.
func WaitForUserCompletion(client *autorest.Client, code *DeviceCode) (*Token, error) {
intervalDuration := time.Duration(*code.Interval) * time.Second
waitDuration := intervalDuration
for {
token, err := CheckForUserCompletion(client, code)
if err == nil {
return token, nil
}
switch err {
case ErrDeviceSlowDown:
waitDuration += waitDuration
case ErrDeviceAuthorizationPending:
// noop
default: // everything else is "fatal" to us
return nil, err
}
if waitDuration > (intervalDuration * 3) {
return nil, fmt.Errorf("%s Error waiting for user to complete device flow. Server told us to slow_down too much", logPrefix)
}
time.Sleep(waitDuration)
}
}
|
