oidc-demo-app/handlers/oidc_callback.go

/*
 Copyright 2020, 2021 Jan Dittberner


 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 handlers

import (
	"context"
	"net/http"

	"github.com/go-openapi/runtime/client"
	"github.com/lestrrat-go/jwx/jwk"
	log "github.com/sirupsen/logrus"
	"golang.org/x/oauth2"

	"git.cacert.org/oidc_demo_app/services"
)

const (
	sessionKeyAccessToken = iota
	sessionKeyRefreshToken
	sessionKeyIdToken
	sessionRedirectTarget
)

type oidcCallbackHandler struct {
	keySet       jwk.Set
	logger       *log.Logger
	oauth2Config *oauth2.Config
}

func (c *oidcCallbackHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	if r.URL.Path != "/callback" {
		http.NotFound(w, r)
		return
	}

	errorText := r.URL.Query().Get("error")
	errorDescription := r.URL.Query().Get("error_description")
	if errorText != "" {
		errorDetails := &ErrorDetails{
			ErrorMessage: errorText,
		}
		if errorDescription != "" {
			errorDetails.ErrorDetails = []string{errorDescription}
		}
		GetErrorBucket(r).AddError(errorDetails)
		return
	}

	code := r.URL.Query().Get("code")

	ctx := context.Background()
	httpClient, err := client.TLSClient(client.TLSClientOptions{InsecureSkipVerify: true})
	ctx = context.WithValue(ctx, oauth2.HTTPClient, httpClient)

	tok, err := c.oauth2Config.Exchange(ctx, code)
	if err != nil {
		c.logger.Error(err)
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
		return
	}

	session, err := services.GetSessionStore().Get(r, "resource_session")
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	session.Values[sessionKeyAccessToken] = tok.AccessToken
	session.Values[sessionKeyRefreshToken] = tok.RefreshToken

	idToken := tok.Extra("id_token").(string)
	session.Values[sessionKeyIdToken] = idToken

	if oidcToken, err := ParseIdToken(idToken, c.keySet); err != nil {
		c.logger.Error(err)
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	} else {
		c.logger.Debugf(`
ID Token
========

Subject:          %s
Audience:         %s
Issued at:        %s
Issued by:        %s
Not valid before: %s
Not valid after:  %s

`,
			oidcToken.Subject(),
			oidcToken.Audience(),
			oidcToken.IssuedAt(),
			oidcToken.Issuer(),
			oidcToken.NotBefore(),
			oidcToken.Expiration(),
		)
	}

	if err = session.Save(r, w); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
	if redirectTarget, ok := session.Values[sessionRedirectTarget]; ok {
		w.Header().Set("Location", redirectTarget.(string))
	} else {
		w.Header().Set("Location", "/")
	}

	w.WriteHeader(http.StatusFound)
}

func NewCallbackHandler(ctx context.Context, logger *log.Logger) *oidcCallbackHandler {
	return &oidcCallbackHandler{
		keySet:       services.GetJwkSet(ctx),
		logger:       logger,
		oauth2Config: services.GetOAuth2Config(ctx),
	}
}