oauth2_proxy/oauthproxy.go
Mike Bland 9d8f932797 Extract api package
This is the first step towards genericizing the google_auth_proxy to support
OAuth2 providers other than Google as discussed in #65. The `api` package will
enable multiple providers to use the same `api.Request()` implementation.
2015-03-30 10:23:30 -04:00

493 lines
12 KiB
Go

package main
import (
"bytes"
"encoding/base64"
"errors"
"fmt"
"html/template"
"log"
"net"
"net/http"
"net/http/httputil"
"net/url"
"regexp"
"strings"
"time"
"github.com/18F/google_auth_proxy/api"
"github.com/bitly/go-simplejson"
)
const pingPath = "/ping"
const signInPath = "/oauth2/sign_in"
const oauthStartPath = "/oauth2/start"
const oauthCallbackPath = "/oauth2/callback"
type OauthProxy struct {
CookieSeed string
CookieKey string
CookieDomain string
CookieSecure bool
CookieHttpOnly bool
CookieExpire time.Duration
Validator func(string) bool
redirectUrl *url.URL // the url to receive requests at
oauthRedemptionUrl *url.URL // endpoint to redeem the code
oauthLoginUrl *url.URL // to redirect the user to
oauthScope string
clientID string
clientSecret string
SignInMessage string
HtpasswdFile *HtpasswdFile
DisplayHtpasswdForm bool
serveMux http.Handler
PassBasicAuth bool
skipAuthRegex []string
compiledRegex []*regexp.Regexp
templates *template.Template
}
type UpstreamProxy struct {
upstream string
handler http.Handler
}
func (u *UpstreamProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Header().Set("GAP-Upstream-Address", u.upstream)
u.handler.ServeHTTP(w, r)
}
func NewReverseProxy(target *url.URL) (proxy *httputil.ReverseProxy) {
return httputil.NewSingleHostReverseProxy(target)
}
func setProxyUpstreamHostHeader(proxy *httputil.ReverseProxy, target *url.URL) {
director := proxy.Director
proxy.Director = func(req *http.Request) {
director(req)
// use RequestURI so that we aren't unescaping encoded slashes in the request path
req.Host = target.Host
req.URL.Opaque = req.RequestURI
req.URL.RawQuery = ""
}
}
func setProxyDirector(proxy *httputil.ReverseProxy) {
director := proxy.Director
proxy.Director = func(req *http.Request) {
director(req)
// use RequestURI so that we aren't unescaping encoded slashes in the request path
req.URL.Opaque = req.RequestURI
req.URL.RawQuery = ""
}
}
func NewOauthProxy(opts *Options, validator func(string) bool) *OauthProxy {
login, _ := url.Parse("https://accounts.google.com/o/oauth2/auth")
redeem, _ := url.Parse("https://accounts.google.com/o/oauth2/token")
serveMux := http.NewServeMux()
for _, u := range opts.proxyUrls {
path := u.Path
u.Path = ""
log.Printf("mapping path %q => upstream %q", path, u)
proxy := NewReverseProxy(u)
if !opts.PassHostHeader {
setProxyUpstreamHostHeader(proxy, u)
} else {
setProxyDirector(proxy)
}
serveMux.Handle(path, &UpstreamProxy{u.Host, proxy})
}
for _, u := range opts.CompiledRegex {
log.Printf("compiled skip-auth-regex => %q", u)
}
redirectUrl := opts.redirectUrl
redirectUrl.Path = oauthCallbackPath
log.Printf("OauthProxy configured for %s", opts.ClientID)
domain := opts.CookieDomain
if domain == "" {
domain = "<default>"
}
if !opts.CookieHttpsOnly {
log.Printf("Warning: cookie-https-only setting is deprecated and will be removed in a future version. use cookie-secure")
opts.CookieSecure = opts.CookieHttpsOnly
}
log.Printf("Cookie settings: secure (https):%v httponly:%v expiry:%s domain:%s", opts.CookieSecure, opts.CookieHttpOnly, opts.CookieExpire, domain)
return &OauthProxy{
CookieKey: "_oauthproxy",
CookieSeed: opts.CookieSecret,
CookieDomain: opts.CookieDomain,
CookieSecure: opts.CookieSecure,
CookieHttpOnly: opts.CookieHttpOnly,
CookieExpire: opts.CookieExpire,
Validator: validator,
clientID: opts.ClientID,
clientSecret: opts.ClientSecret,
oauthScope: "profile email",
oauthRedemptionUrl: redeem,
oauthLoginUrl: login,
serveMux: serveMux,
redirectUrl: redirectUrl,
skipAuthRegex: opts.SkipAuthRegex,
compiledRegex: opts.CompiledRegex,
PassBasicAuth: opts.PassBasicAuth,
templates: loadTemplates(opts.CustomTemplatesDir),
}
}
func (p *OauthProxy) GetRedirectUrl(host string) string {
// default to the request Host if not set
if p.redirectUrl.Host != "" {
return p.redirectUrl.String()
}
var u url.URL
u = *p.redirectUrl
if u.Scheme == "" {
if p.CookieSecure {
u.Scheme = "https"
} else {
u.Scheme = "http"
}
}
u.Host = host
return u.String()
}
func (p *OauthProxy) GetLoginURL(host, redirect string) string {
params := url.Values{}
params.Add("redirect_uri", p.GetRedirectUrl(host))
params.Add("approval_prompt", "force")
params.Add("scope", p.oauthScope)
params.Add("client_id", p.clientID)
params.Add("response_type", "code")
if strings.HasPrefix(redirect, "/") {
params.Add("state", redirect)
}
return fmt.Sprintf("%s?%s", p.oauthLoginUrl, params.Encode())
}
func (p *OauthProxy) displayCustomLoginForm() bool {
return p.HtpasswdFile != nil && p.DisplayHtpasswdForm
}
func (p *OauthProxy) redeemCode(host, code string) (string, string, error) {
if code == "" {
return "", "", errors.New("missing code")
}
params := url.Values{}
params.Add("redirect_uri", p.GetRedirectUrl(host))
params.Add("client_id", p.clientID)
params.Add("client_secret", p.clientSecret)
params.Add("code", code)
params.Add("grant_type", "authorization_code")
req, err := http.NewRequest("POST", p.oauthRedemptionUrl.String(), bytes.NewBufferString(params.Encode()))
if err != nil {
log.Printf("failed building request %s", err.Error())
return "", "", err
}
req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
json, err := api.Request(req)
if err != nil {
log.Printf("failed making request %s", err)
return "", "", err
}
access_token, err := json.Get("access_token").String()
if err != nil {
return "", "", err
}
idToken, err := json.Get("id_token").String()
if err != nil {
return "", "", err
}
// id_token is a base64 encode ID token payload
// https://developers.google.com/accounts/docs/OAuth2Login#obtainuserinfo
jwt := strings.Split(idToken, ".")
b, err := jwtDecodeSegment(jwt[1])
if err != nil {
return "", "", err
}
data, err := simplejson.NewJson(b)
if err != nil {
return "", "", err
}
email, err := data.Get("email").String()
if err != nil {
return "", "", err
}
return access_token, email, nil
}
func jwtDecodeSegment(seg string) ([]byte, error) {
if l := len(seg) % 4; l > 0 {
seg += strings.Repeat("=", 4-l)
}
return base64.URLEncoding.DecodeString(seg)
}
func (p *OauthProxy) ClearCookie(rw http.ResponseWriter, req *http.Request) {
domain := req.Host
if h, _, err := net.SplitHostPort(domain); err == nil {
domain = h
}
if p.CookieDomain != "" {
if !strings.HasSuffix(domain, p.CookieDomain) {
log.Printf("Warning: request host is %q but using configured cookie domain of %q", domain, p.CookieDomain)
}
domain = p.CookieDomain
}
cookie := &http.Cookie{
Name: p.CookieKey,
Value: "",
Path: "/",
Domain: domain,
HttpOnly: p.CookieHttpOnly,
Secure: p.CookieSecure,
Expires: time.Now().Add(time.Duration(1) * time.Hour * -1),
}
http.SetCookie(rw, cookie)
}
func (p *OauthProxy) SetCookie(rw http.ResponseWriter, req *http.Request, val string) {
domain := req.Host
if h, _, err := net.SplitHostPort(domain); err == nil {
domain = h
}
if p.CookieDomain != "" {
if !strings.HasSuffix(domain, p.CookieDomain) {
log.Printf("Warning: request host is %q but using configured cookie domain of %q", domain, p.CookieDomain)
}
domain = p.CookieDomain
}
cookie := &http.Cookie{
Name: p.CookieKey,
Value: signedCookieValue(p.CookieSeed, p.CookieKey, val),
Path: "/",
Domain: domain,
HttpOnly: p.CookieHttpOnly,
Secure: p.CookieSecure,
Expires: time.Now().Add(p.CookieExpire),
}
http.SetCookie(rw, cookie)
}
func (p *OauthProxy) PingPage(rw http.ResponseWriter) {
rw.WriteHeader(http.StatusOK)
fmt.Fprintf(rw, "OK")
}
func (p *OauthProxy) ErrorPage(rw http.ResponseWriter, code int, title string, message string) {
log.Printf("ErrorPage %d %s %s", code, title, message)
rw.WriteHeader(code)
t := struct {
Title string
Message string
}{
Title: fmt.Sprintf("%d %s", code, title),
Message: message,
}
p.templates.ExecuteTemplate(rw, "error.html", t)
}
func (p *OauthProxy) SignInPage(rw http.ResponseWriter, req *http.Request, code int) {
p.ClearCookie(rw, req)
rw.WriteHeader(code)
t := struct {
SignInMessage string
CustomLogin bool
Redirect string
Version string
}{
SignInMessage: p.SignInMessage,
CustomLogin: p.displayCustomLoginForm(),
Redirect: req.URL.RequestURI(),
Version: VERSION,
}
p.templates.ExecuteTemplate(rw, "sign_in.html", t)
}
func (p *OauthProxy) ManualSignIn(rw http.ResponseWriter, req *http.Request) (string, bool) {
if req.Method != "POST" || p.HtpasswdFile == nil {
return "", false
}
user := req.FormValue("username")
passwd := req.FormValue("password")
if user == "" {
return "", false
}
// check auth
if p.HtpasswdFile.Validate(user, passwd) {
log.Printf("authenticated %q via HtpasswdFile", user)
return user, true
}
return "", false
}
func (p *OauthProxy) GetRedirect(req *http.Request) (string, error) {
err := req.ParseForm()
if err != nil {
return "", err
}
redirect := req.FormValue("rd")
if redirect == "" {
redirect = "/"
}
return redirect, err
}
func (p *OauthProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
// check if this is a redirect back at the end of oauth
remoteAddr := req.RemoteAddr
if req.Header.Get("X-Real-IP") != "" {
remoteAddr += fmt.Sprintf(" (%q)", req.Header.Get("X-Real-IP"))
}
var ok bool
var user string
var email string
if req.URL.Path == pingPath {
p.PingPage(rw)
return
}
for _, u := range p.compiledRegex {
match := u.MatchString(req.URL.Path)
if match {
p.serveMux.ServeHTTP(rw, req)
return
}
}
if req.URL.Path == signInPath {
redirect, err := p.GetRedirect(req)
if err != nil {
p.ErrorPage(rw, 500, "Internal Error", err.Error())
return
}
user, ok = p.ManualSignIn(rw, req)
if ok {
p.SetCookie(rw, req, user)
http.Redirect(rw, req, redirect, 302)
} else {
p.SignInPage(rw, req, 200)
}
return
}
if req.URL.Path == oauthStartPath {
redirect, err := p.GetRedirect(req)
if err != nil {
p.ErrorPage(rw, 500, "Internal Error", err.Error())
return
}
http.Redirect(rw, req, p.GetLoginURL(req.Host, redirect), 302)
return
}
if req.URL.Path == oauthCallbackPath {
// finish the oauth cycle
err := req.ParseForm()
if err != nil {
p.ErrorPage(rw, 500, "Internal Error", err.Error())
return
}
errorString := req.Form.Get("error")
if errorString != "" {
p.ErrorPage(rw, 403, "Permission Denied", errorString)
return
}
_, email, err := p.redeemCode(req.Host, req.Form.Get("code"))
if err != nil {
log.Printf("%s error redeeming code %s", remoteAddr, err)
p.ErrorPage(rw, 500, "Internal Error", err.Error())
return
}
redirect := req.Form.Get("state")
if redirect == "" {
redirect = "/"
}
// set cookie, or deny
if p.Validator(email) {
log.Printf("%s authenticating %s completed", remoteAddr, email)
p.SetCookie(rw, req, email)
http.Redirect(rw, req, redirect, 302)
return
} else {
p.ErrorPage(rw, 403, "Permission Denied", "Invalid Account")
return
}
}
if !ok {
cookie, err := req.Cookie(p.CookieKey)
if err == nil {
email, ok = validateCookie(cookie, p.CookieSeed)
user = strings.Split(email, "@")[0]
}
}
if !ok {
user, ok = p.CheckBasicAuth(req)
}
if !ok {
p.SignInPage(rw, req, 403)
return
}
// At this point, the user is authenticated. proxy normally
if p.PassBasicAuth {
req.SetBasicAuth(user, "")
req.Header["X-Forwarded-User"] = []string{user}
req.Header["X-Forwarded-Email"] = []string{email}
}
if email == "" {
rw.Header().Set("GAP-Auth", user)
} else {
rw.Header().Set("GAP-Auth", email)
}
p.serveMux.ServeHTTP(rw, req)
}
func (p *OauthProxy) CheckBasicAuth(req *http.Request) (string, bool) {
if p.HtpasswdFile == nil {
return "", false
}
s := strings.SplitN(req.Header.Get("Authorization"), " ", 2)
if len(s) != 2 || s[0] != "Basic" {
return "", false
}
b, err := base64.StdEncoding.DecodeString(s[1])
if err != nil {
return "", false
}
pair := strings.SplitN(string(b), ":", 2)
if len(pair) != 2 {
return "", false
}
if p.HtpasswdFile.Validate(pair[0], pair[1]) {
log.Printf("authenticated %q via basic auth", pair[0])
return pair[0], true
}
return "", false
}