*: add example-app

Makefile

@@ -21,11 +21,14 @@ else
 endif
 
 
-build: bin/poke
+build: bin/poke bin/example-app
 
 bin/poke: FORCE
 	@go install $(REPO_PATH)/cmd/poke
 
+bin/example-app: FORCE
+	@go install $(REPO_PATH)/cmd/example-app
+
 test:
 	@go test $(shell go list ./... | grep -v '/vendor/')
 

cmd/example-app/main.go

+package main
+
+import (
+	"bytes"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/ericchiang/oidc"
+	"github.com/spf13/cobra"
+	"golang.org/x/net/context"
+	"golang.org/x/oauth2"
+)
+
+type app struct {
+	clientID     string
+	clientSecret string
+	redirectURI  string
+
+	verifier *oidc.IDTokenVerifier
+	provider *oidc.Provider
+
+	ctx    context.Context
+	cancel context.CancelFunc
+}
+
+// return an HTTP client which trusts the provided root CAs.
+func httpClientForRootCAs(rootCAs string) (*http.Client, error) {
+	tlsConfig := tls.Config{RootCAs: x509.NewCertPool()}
+	rootCABytes, err := ioutil.ReadFile(rootCAs)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read root-ca: %v", err)
+	}
+	if !tlsConfig.RootCAs.AppendCertsFromPEM(rootCABytes) {
+		return nil, fmt.Errorf("no certs found in root CA file %q", rootCAs)
+	}
+	return &http.Client{
+		Transport: &http.Transport{
+			TLSClientConfig: &tlsConfig,
+			Proxy:           http.ProxyFromEnvironment,
+			Dial: (&net.Dialer{
+				Timeout:   30 * time.Second,
+				KeepAlive: 30 * time.Second,
+			}).Dial,
+			TLSHandshakeTimeout:   10 * time.Second,
+			ExpectContinueTimeout: 1 * time.Second,
+		},
+	}, nil
+}
+
+func cmd() *cobra.Command {
+	var (
+		a         app
+		issuerURL string
+		listen    string
+		tlsCert   string
+		tlsKey    string
+		rootCAs   string
+	)
+	c := cobra.Command{
+		Use:   "example-app",
+		Short: "An example OpenID Connect client",
+		Long:  "",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) != 0 {
+				return errors.New("surplus arguments provided")
+			}
+
+			u, err := url.Parse(a.redirectURI)
+			if err != nil {
+				return fmt.Errorf("parse redirect-uri: %v", err)
+			}
+			listenURL, err := url.Parse(listen)
+			if err != nil {
+				return fmt.Errorf("parse listen address: %v", err)
+			}
+
+			a.ctx, a.cancel = context.WithCancel(context.Background())
+
+			if rootCAs != "" {
+				client, err := httpClientForRootCAs(rootCAs)
+				if err != nil {
+					return err
+				}
+
+				// This sets the OAuth2 client and oidc client.
+				a.ctx = context.WithValue(a.ctx, oauth2.HTTPClient, &client)
+			}
+
+			// TODO(ericchiang): Retry with backoff
+			provider, err := oidc.NewProvider(a.ctx, issuerURL)
+			if err != nil {
+				return fmt.Errorf("Failed to query provider %q: %v", issuerURL, err)
+			}
+			a.provider = provider
+			a.verifier = provider.NewVerifier(a.ctx, oidc.VerifyAudience(a.clientID))
+
+			http.HandleFunc("/", a.handleIndex)
+			http.HandleFunc("/login", a.handleLogin)
+			http.HandleFunc(u.Path, a.handleCallback)
+
+			switch listenURL.Scheme {
+			case "http":
+				log.Printf("listening on %s", listen)
+				return http.ListenAndServe(listenURL.Host, nil)
+			case "https":
+				log.Printf("listening on %s", listen)
+				return http.ListenAndServeTLS(listenURL.Host, tlsCert, tlsKey, nil)
+			default:
+				return fmt.Errorf("listen address %q is not using http or https", listen)
+			}
+		},
+	}
+	c.Flags().StringVar(&a.clientID, "client-id", "example-app", "OAuth2 client ID of this application.")
+	c.Flags().StringVar(&a.clientSecret, "client-secret", "ZXhhbXBsZS1hcHAtc2VjcmV0", "OAuth2 client secret of this application.")
+	c.Flags().StringVar(&a.redirectURI, "redirect-uri", "http://127.0.0.1:5555/callback", "Callback URL for OAuth2 responses.")
+	c.Flags().StringVar(&issuerURL, "issuer", "http://127.0.0.1:5556", "URL of the OpenID Connect issuer.")
+	c.Flags().StringVar(&listen, "listen", "http://127.0.0.1:5555", "HTTP(S) address to listen at.")
+	c.Flags().StringVar(&tlsCert, "tls-cert", "", "X509 cert file to present when serving HTTPS.")
+	c.Flags().StringVar(&tlsKey, "tls-key", "", "Private key for the HTTPS cert.")
+	c.Flags().StringVar(&rootCAs, "issuer-root-ca", "", "Root certificate authorities for the issuer. Defaults to host certs.")
+	return &c
+}
+
+func main() {
+	if err := cmd().Execute(); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(2)
+	}
+}
+
+func (a *app) handleIndex(w http.ResponseWriter, r *http.Request) {
+	renderIndex(w)
+}
+
+func (a *app) oauth2Config(scopes []string) *oauth2.Config {
+	return &oauth2.Config{
+		ClientID:     a.clientID,
+		ClientSecret: a.clientSecret,
+		Endpoint:     a.provider.Endpoint(),
+		Scopes:       scopes,
+		RedirectURL:  a.redirectURI,
+	}
+}
+
+func (a *app) handleLogin(w http.ResponseWriter, r *http.Request) {
+	var scopes []string
+	if extraScopes := r.FormValue("extra_scopes"); extraScopes != "" {
+		scopes = strings.Split(extraScopes, " ")
+	}
+	var clients []string
+	if crossClients := r.FormValue("cross_client"); crossClients != "" {
+		clients = strings.Split(crossClients, " ")
+	}
+	for _, client := range clients {
+		scopes = append(scopes, "audience:server:client_id:"+client)
+	}
+
+	// TODO(ericchiang): Determine if provider does not support "offline_access" or has
+	// some other mechanism for requesting refresh tokens.
+	scopes = append(scopes, "openid", "profile", "email", "offline_access")
+	http.Redirect(w, r, a.oauth2Config(scopes).AuthCodeURL(""), http.StatusSeeOther)
+}
+
+func (a *app) handleCallback(w http.ResponseWriter, r *http.Request) {
+	if errMsg := r.FormValue("error"); errMsg != "" {
+		http.Error(w, errMsg+": "+r.FormValue("error_description"), http.StatusBadRequest)
+		return
+	}
+
+	code := r.FormValue("code")
+	refresh := r.FormValue("refresh_token")
+	var (
+		err   error
+		token *oauth2.Token
+	)
+	oauth2Config := a.oauth2Config(nil)
+	switch {
+	case code != "":
+		token, err = oauth2Config.Exchange(a.ctx, code)
+	case refresh != "":
+		t := &oauth2.Token{
+			RefreshToken: refresh,
+			Expiry:       time.Now().Add(-time.Hour),
+		}
+		token, err = oauth2Config.TokenSource(a.ctx, t).Token()
+	default:
+		http.Error(w, "no code in request", http.StatusBadRequest)
+		return
+	}
+
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to get token: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	rawIDToken, ok := token.Extra("id_token").(string)
+	if !ok {
+		http.Error(w, "no id_token in token response", http.StatusInternalServerError)
+		return
+	}
+
+	idToken, err := a.verifier.Verify(rawIDToken)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Failed to verify ID token: %v", err), http.StatusInternalServerError)
+		return
+	}
+	var claims json.RawMessage
+	idToken.Claims(&claims)
+
+	buff := new(bytes.Buffer)
+	json.Indent(buff, []byte(claims), "", "  ")
+
+	renderToken(w, a.redirectURI, rawIDToken, token.RefreshToken, buff.Bytes())
+}

cmd/example-app/templates.go

+package main
+
+import (
+	"html/template"
+	"log"
+	"net/http"
+)
+
+var indexTmpl = template.Must(template.New("index.html").Parse(`<html>
+  <body>
+    <form action="/login">
+       <p>
+         Authenticate for:<input type="text" name="cross_client" placeholder="list of client-ids">
+       </p>
+       <p>
+         Extra scopes:<input type="text" name="extra_scopes" placeholder="list of scopes">
+       </p>
+       <input type="submit" value="Login">
+    </form>
+  </body>
+</html>`))
+
+func renderIndex(w http.ResponseWriter) {
+	renderTemplate(w, indexTmpl, nil)
+}
+
+type tokenTmplData struct {
+	IDToken      string
+	RefreshToken string
+	RedirectURL  string
+	Claims       string
+}
+
+var tokenTmpl = template.Must(template.New("token.html").Parse(`<html>
+  <head>
+    <style>
+/* make pre wrap */
+pre {
+ white-space: pre-wrap;       /* css-3 */
+ white-space: -moz-pre-wrap;  /* Mozilla, since 1999 */
+ white-space: -pre-wrap;      /* Opera 4-6 */
+ white-space: -o-pre-wrap;    /* Opera 7 */
+ word-wrap: break-word;       /* Internet Explorer 5.5+ */
+}
+    </style>
+  </head>
+  <body>
+    <p> Token: <pre><code>{{ .IDToken }}</code></pre></p>
+    <p> Claims: <pre><code>{{ .Claims }}</code></pre></p>
+    <p> Refresh Token: <pre><code>{{ .RefreshToken }}</code></pre></p>
+    <p><a href="{{ .RedirectURL }}?refresh_token={{ .RefreshToken }}">Redeem refresh token</a><p>
+  </body>
+</html>
+`))
+
+func renderToken(w http.ResponseWriter, redirectURL, idToken, refreshToken string, claims []byte) {
+	renderTemplate(w, tokenTmpl, tokenTmplData{
+		IDToken:      idToken,
+		RefreshToken: refreshToken,
+		RedirectURL:  redirectURL,
+		Claims:       string(claims),
+	})
+}
+
+func renderTemplate(w http.ResponseWriter, tmpl *template.Template, data interface{}) {
+	err := tmpl.Execute(w, data)
+	if err == nil {
+		return
+	}
+
+	switch err := err.(type) {
+	case *template.Error:
+		// An ExecError guarentees that Execute has not written to the underlying reader.
+		log.Printf("Error rendering template %s: %s", tmpl.Name(), err)
+
+		// TODO(ericchiang): replace with better internal server error.
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+	default:
+		// An error with the underlying write, such as the connection being
+		// dropped. Ignore for now.
+	}
+}