Select oauth provider

bouquins/auth.go

@@ -15,9 +15,65 @@ const (
 	alphanums            = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
 	sessionName          = "bouquins"
 	sessionOAuthState    = "oauthState"
+	sessionOAuthProvider = "provider"
 	sessionUser          = "username"
+
+	pProvider = "provider"
 )
 
+var (
+	Providers = [1]OAuth2Provider{GithubProvider("github")}
+)
+
+type OAuth2Provider interface {
+	GetUser(token *oauth2.Token) (string, error)
+	Name() string
+}
+
+type GithubProvider string
+
+func (p GithubProvider) Name() string {
+	return string(p)
+}
+func (p GithubProvider) GetUser(token *oauth2.Token) (string, error) {
+	apiReq, err := http.NewRequest("GET", "https://api.github.com/user/emails", nil)
+	apiReq.Header.Add("Accept", "application/vnd.github.v3+json")
+	apiReq.Header.Add("Authorization", "token "+token.AccessToken)
+	client := &http.Client{}
+	response, err := client.Do(apiReq)
+	defer response.Body.Close()
+	if err != nil {
+		log.Println("Auth error", err)
+		return "", fmt.Errorf("Authentification error")
+	}
+
+	dec := json.NewDecoder(response.Body)
+	var emails []GitHubEmail
+	err = dec.Decode(&emails)
+	if err != nil {
+		log.Println("Error reading github API response", err)
+		return "", fmt.Errorf("Error reading github API response")
+	}
+	fmt.Printf("Content: %s\n", emails)
+	var userEmail string
+	for _, email := range emails {
+		if email.Primary && email.Verified {
+			userEmail = email.Email
+		}
+	}
+	log.Println("User email:", userEmail)
+	return userEmail, nil
+}
+
+func findProvider(name string) OAuth2Provider {
+	for _, p := range Providers {
+		if p.Name() == name {
+			return p
+		}
+	}
+	return nil
+}
+
 // generates a 16 characters long random string
 func securedRandString() string {
 	b := make([]byte, 16)
@@ -51,12 +107,18 @@ func (app *Bouquins) SessionSet(name string, value string, res http.ResponseWrit
 
 // LoginPage redirects to OAuth login page (github)
 func (app *Bouquins) LoginPage(res http.ResponseWriter, req *http.Request) error {
-	// TODO choose provider
+	provider := req.URL.Query().Get(pProvider)
+	oauth := app.OAuthConf[provider]
+	if oauth != nil {
+		app.SessionSet(sessionOAuthProvider, provider, res, req)
 		state := securedRandString()
 		app.SessionSet(sessionOAuthState, state, res, req)
-	url := app.OAuthConf.AuthCodeURL(state)
+		url := oauth.AuthCodeURL(state)
 		http.Redirect(res, req, url, http.StatusTemporaryRedirect)
 		return nil
+	}
+	// choose provider
+	return app.render(res, tplProvider, app.NewModel("Authentification", "provider", req))
 }
 
 // LogoutPage logout connected user
@@ -68,45 +130,31 @@ func (app *Bouquins) LogoutPage(res http.ResponseWriter, req *http.Request) erro
 // CallbackPage handle OAuth 2 callback
 func (app *Bouquins) CallbackPage(res http.ResponseWriter, req *http.Request) error {
 	savedState := app.Session(req).Values[sessionOAuthState]
-	if savedState == "" {
-		return fmt.Errorf("missing saved oauth state")
+	providerParam := app.Session(req).Values[sessionOAuthProvider]
+	if savedState == "" || providerParam == "" {
+		return fmt.Errorf("missing oauth data")
+	}
+	providerName := providerParam.(string)
+	oauth := app.OAuthConf[providerName]
+	provider := findProvider(providerName)
+	if oauth == nil || provider == nil {
+		return fmt.Errorf("missing oauth configuration")
 	}
 	app.SessionSet(sessionOAuthState, "", res, req)
+	app.SessionSet(sessionOAuthProvider, "", res, req)
 	state := req.FormValue("state")
 	if state != savedState {
 		return fmt.Errorf("invalid oauth state, expected '%s', got '%s'", "state", state)
 	}
 	code := req.FormValue("code")
-	token, err := app.OAuthConf.Exchange(oauth2.NoContext, code)
+	token, err := oauth.Exchange(oauth2.NoContext, code)
 	if err != nil {
 		return fmt.Errorf("Code exchange failed with '%s'", err)
 	}
-	apiReq, err := http.NewRequest("GET", "https://api.github.com/user/emails", nil)
-	apiReq.Header.Add("Accept", "application/vnd.github.v3+json")
-	apiReq.Header.Add("Authorization", "token "+token.AccessToken)
-	client := &http.Client{}
-	response, err := client.Do(apiReq)
-	defer response.Body.Close()
+	userEmail, err := provider.GetUser(token)
 	if err != nil {
-		log.Println("Auth error", err)
-		return fmt.Errorf("Authentification error")
+		return err
 	}
-
-	dec := json.NewDecoder(response.Body)
-	var emails []GitHubEmail
-	err = dec.Decode(&emails)
-	if err != nil {
-		log.Println("Error reading github API response", err)
-		return fmt.Errorf("Error reading github API response")
-	}
-	fmt.Printf("Content: %s\n", emails)
-	var userEmail string
-	for _, email := range emails {
-		if email.Primary && email.Verified {
-			userEmail = email.Email
-		}
-	}
-	log.Println("User email:", userEmail)
 	// FIXME list allowed users
 	if userEmail == "meutel+github@meutel.net" {
 		app.SessionSet(sessionUser, "Meutel", res, req)

bouquins/bouquins.go

@@ -27,6 +27,7 @@ const (
 	tplIndex    = "index.html"
 	tplSearch   = "search.html"
 	tplAbout    = "about.html"
+	tplProvider = "provider.html"
 
 	pList    = "list"
 	pOrder   = "order"
@@ -74,7 +75,7 @@ type GitHubEmail struct {
 type Bouquins struct {
 	Tpl       *template.Template
 	DB        *sql.DB
-	OAuthConf *oauth2.Config
+	OAuthConf map[string]*oauth2.Config
 	Cookies   *sessions.CookieStore
 }
 

main.go

@@ -71,7 +71,8 @@ func initApp() *BouquinsConf {
 	}
 
 	// TODO conf by provider, client ID and secret in conf file
-	oauthConf := &oauth2.Config{
+	oauthConf := make(map[string]*oauth2.Config)
+	oauthConf["github"] = &oauth2.Config{
 		ClientID:     "8b0aedf07828f06918a0",
 		ClientSecret: "eb26ec9c986fc28bd169bdddf169b794861e0d65",
 		Scopes:       []string{"user:email"},

templates/provider.html

@@ -0,0 +1,9 @@
+{{ template "header.html" . }}
+<div class="container" id="provider">
+  <p>Veuillez sélectionner un mode d'authentification:<p>
+  <ul>
+    <!-- TODO list providers, icon -->
+    <li><a href="/login?provider=github">Github</a></li>
+  </ul>
+</div>
+{{ template "footer.html" . }}