oauth.go

/*
Copyright 2015 All rights reserved.
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 main

import (
	"strings"
	"time"

	"github.com/coreos/go-oidc/jose"
	"github.com/coreos/go-oidc/oauth2"
	"github.com/coreos/go-oidc/oidc"
)

//
// verifyToken verify that the token in the user context is valid
//
func verifyToken(client *oidc.Client, token jose.JWT) error {
	// step: verify the token is whom they say they are
	if err := client.VerifyJWT(token); err != nil {
		if strings.Contains(err.Error(), "token is expired") {
			return ErrAccessTokenExpired
		}

		return err
	}

	return nil
}

//
// getRefreshedToken attempts to refresh the access token, returning the parsed token and the time it expires or a error
//
func getRefreshedToken(client *oidc.Client, t string) (jose.JWT, time.Time, error) {
	response, err := getToken(client, oauth2.GrantTypeRefreshToken, t)
	if err != nil {
		if strings.Contains(err.Error(), "token expired") {
			return jose.JWT{}, time.Time{}, ErrRefreshTokenExpired
		}
		return jose.JWT{}, time.Time{}, err
	}

	// step: parse the access token
	token, identity, err := parseToken(response.AccessToken)
	if err != nil {
		return jose.JWT{}, time.Time{}, err
	}

	return token, identity.ExpiresAt, nil
}

//
// exchangeAuthenticationCode exchanges the authentication code with the oauth server for a access token
//
func exchangeAuthenticationCode(client *oidc.Client, code string) (oauth2.TokenResponse, error) {
	return getToken(client, oauth2.GrantTypeAuthCode, code)
}

//
// getToken retrieves a code from the provider, extracts and verified the token
//
func getToken(client *oidc.Client, grantType, code string) (oauth2.TokenResponse, error) {
	// step: retrieve the client
	c, err := client.OAuthClient()
	if err != nil {
		return oauth2.TokenResponse{}, err
	}

	// step: request a token from the authentication server
	return c.RequestToken(grantType, code)
}

//
// parseToken retrieve the user identity from the token
//
func parseToken(t string) (jose.JWT, *oidc.Identity, error) {
	// step: parse and return the token
	token, err := jose.ParseJWT(t)
	if err != nil {
		return jose.JWT{}, nil, err
	}

	// step: parse the claims
	claims, err := token.Claims()
	if err != nil {
		return jose.JWT{}, nil, err
	}

	// step: get the identity
	identity, err := oidc.IdentityFromClaims(claims)
	if err != nil {
		return jose.JWT{}, nil, err
	}

	return token, identity, nil
}