connector/linkedin: implement RefreshConnector interface

Do Refresh() by querying user's profile data.

Since LinkedIn doesn't provide refresh tokens at all, and the access
tokens have 60 days expiration, refresh tokens issued by Dex will fail
to update after 60 days.
Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>

connector/linkedin/linkedin.go

@@ -45,15 +45,20 @@ func (c *Config) Open(id string, logger logrus.FieldLogger) (connector.Connector
 	}, nil
 }
 
+type connectorData struct {
+	AccessToken string `json:"accessToken"`
+}
+
 type linkedInConnector struct {
 	oauth2Config *oauth2.Config
 	logger       logrus.FieldLogger
 }
 
-// LinkedIn doesn't provide refresh tokens, so we don't implement
-// RefreshConnector here.
+// LinkedIn doesn't provide refresh tokens, so refresh tokens issued by Dex
+// will expire in 60 days (default LinkedIn token lifetime).
 var (
 	_ connector.CallbackConnector = (*linkedInConnector)(nil)
+	_ connector.RefreshConnector  = (*linkedInConnector)(nil)
 )
 
 // LoginURL returns an access token request URL
@@ -92,9 +97,40 @@ func (c *linkedInConnector) HandleCallback(s connector.Scopes, r *http.Request)
 		EmailVerified: true,
 	}
 
+	if s.OfflineAccess {
+		data := connectorData{AccessToken: token.AccessToken}
+		connData, err := json.Marshal(data)
+		if err != nil {
+			return identity, fmt.Errorf("linkedin: marshal connector data: %v", err)
+		}
+		identity.ConnectorData = connData
+	}
+
 	return identity, nil
 }
 
+func (c *linkedInConnector) Refresh(ctx context.Context, s connector.Scopes, ident connector.Identity) (connector.Identity, error) {
+	if len(ident.ConnectorData) == 0 {
+		return ident, fmt.Errorf("linkedin: no upstream access token found")
+	}
+
+	var data connectorData
+	if err := json.Unmarshal(ident.ConnectorData, &data); err != nil {
+		return ident, fmt.Errorf("linkedin: unmarshal access token: %v", err)
+	}
+
+	client := c.oauth2Config.Client(ctx, &oauth2.Token{AccessToken: data.AccessToken})
+	profile, err := c.profile(ctx, client)
+	if err != nil {
+		return ident, fmt.Errorf("linkedin: get profile: %v", err)
+	}
+
+	ident.Username = profile.fullname()
+	ident.Email = profile.Email
+
+	return ident, nil
+}
+
 type profile struct {
 	ID        string `json:"id"`
 	FirstName string `json:"firstName"`