Line provider: added getting an email address from id_token

providers/line/line.go

@@ -8,7 +8,9 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"time"
 
+	"github.com/golang-jwt/jwt/v4"
 	"github.com/markbates/goth"
 	"golang.org/x/oauth2"
 )
@@ -17,8 +19,14 @@ const (
 	authURL      string = "https://access.line.me/oauth2/v2.1/authorize"
 	tokenURL     string = "https://api.line.me/oauth2/v2.1/token"
 	endpointUser string = "https://api.line.me/v2/profile"
+	issuerURL    string = "https://access.line.me"
 )
 
+type IDTokenClaims struct {
+	jwt.StandardClaims
+	Email string `json:"email"`
+}
+
 // Provider is the implementation of `goth.Provider` for accessing Line.me.
 type Provider struct {
 	ClientKey       string
@@ -95,11 +103,9 @@ func (p *Provider) FetchUser(session goth.Session) (goth.User, error) {
 
 	response, err := c.Do(req)
 	if err != nil {
-		if response != nil {
-			response.Body.Close()
-		}
 		return user, err
 	}
+	defer response.Body.Close()
 
 	if response.StatusCode != http.StatusOK {
 		return user, fmt.Errorf("%s responded with a %d trying to fetch user information", p.providerName, response.StatusCode)
@@ -125,6 +131,13 @@ func (p *Provider) FetchUser(session goth.Session) (goth.User, error) {
 	user.NickName = u.DisplayName
 	user.AvatarURL = u.PictureURL
 	user.UserID = u.UserID
+
+	if sess.IDToken != "" {
+		if err = p.addDataFromIdToken(sess.IDToken, &user); err != nil {
+			return user, err
+		}
+	}
+
 	return user, err
 }
 
@@ -141,9 +154,7 @@ func newConfig(provider *Provider, scopes []string) *oauth2.Config {
 	}
 
 	if len(scopes) > 0 {
-		for _, scope := range scopes {
-			c.Scopes = append(c.Scopes, scope)
-		}
+		c.Scopes = append(c.Scopes, scopes...)
 	}
 	return c
 }
@@ -167,3 +178,36 @@ func (p *Provider) SetBotPrompt(botPrompt string) {
 	}
 	p.authCodeOptions = append(p.authCodeOptions, oauth2.SetAuthURLParam("bot_prompt", botPrompt))
 }
+
+func (p *Provider) addDataFromIdToken(idToken string, user *goth.User) error {
+	token, err := jwt.ParseWithClaims(idToken, &IDTokenClaims{}, func(t *jwt.Token) (interface{}, error) {
+		claims := t.Claims.(*IDTokenClaims)
+		vErr := new(jwt.ValidationError)
+
+		if !claims.VerifyAudience(p.ClientKey, true) {
+			vErr.Inner = fmt.Errorf("audience is incorrect")
+			vErr.Errors |= jwt.ValidationErrorAudience
+		}
+		if !claims.VerifyIssuer(issuerURL, true) {
+			vErr.Inner = fmt.Errorf("issuer is incorrect")
+			vErr.Errors |= jwt.ValidationErrorIssuer
+		}
+		if !claims.VerifyExpiresAt(time.Now().Unix(), true) {
+			vErr.Inner = fmt.Errorf("token is expired")
+			vErr.Errors |= jwt.ValidationErrorExpired
+		}
+		if vErr.Errors > 0 {
+			return nil, vErr
+		}
+
+		return []byte(p.Secret), nil
+	})
+
+	if err != nil {
+		return err
+	}
+
+	user.Email = token.Claims.(*IDTokenClaims).Email
+
+	return nil
+}

providers/line/session.go

@@ -15,6 +15,7 @@ type Session struct {
 	AccessToken  string
 	RefreshToken string
 	ExpiresAt    time.Time
+	IDToken      string
 }
 
 var _ goth.Session = &Session{}
@@ -42,6 +43,11 @@ func (s *Session) Authorize(provider goth.Provider, params goth.Params) (string,
 	s.AccessToken = token.AccessToken
 	s.RefreshToken = token.RefreshToken
 	s.ExpiresAt = token.Expiry
+
+	if idToken := token.Extra("id_token"); idToken != nil {
+		s.IDToken = idToken.(string)
+	}
+
 	return token.AccessToken, err
 }
 

providers/line/session_test.go

@@ -36,7 +36,7 @@ func Test_ToJSON(t *testing.T) {
 	s := &line.Session{}
 
 	data := s.Marshal()
-	a.Equal(data, `{"AuthURL":"","AccessToken":"","RefreshToken":"","ExpiresAt":"0001-01-01T00:00:00Z"}`)
+	a.Equal(data, `{"AuthURL":"","AccessToken":"","RefreshToken":"","ExpiresAt":"0001-01-01T00:00:00Z","IDToken":""}`)
 }
 
 func Test_String(t *testing.T) {