Implement refresh in OIDC connector

This has added the access=offline parameter and prompt=consent parameter
to the initial request, this works with google, assuming other providers
will ignore the prompt parameter

connector/oidc/oidc.go

@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/coreos/go-oidc"
 	"golang.org/x/oauth2"
@@ -172,9 +173,9 @@ func (c *oidcConnector) LoginURL(s connector.Scopes, callbackURL, state string)
 		if len(c.hostedDomains) > 1 {
 			preferredDomain = "*"
 		}
-		return c.oauth2Config.AuthCodeURL(state, oauth2.SetAuthURLParam("hd", preferredDomain)), nil
+		return c.oauth2Config.AuthCodeURL(state, oauth2.AccessTypeOffline, oauth2.SetAuthURLParam("prompt", "consent"), oauth2.SetAuthURLParam("hd", preferredDomain)), nil
 	}
-	return c.oauth2Config.AuthCodeURL(state), nil
+	return c.oauth2Config.AuthCodeURL(state, oauth2.AccessTypeOffline, oauth2.SetAuthURLParam("prompt", "consent")), nil
 }
 
 type oauth2Error struct {
@@ -265,6 +266,7 @@ func (c *oidcConnector) HandleCallback(s connector.Scopes, r *http.Request) (ide
 		Username:      name,
 		Email:         email,
 		EmailVerified: emailVerified,
+		ConnectorData: []byte(token.RefreshToken),
 	}
 
 	if c.userIDKey != "" {
@@ -280,5 +282,54 @@ func (c *oidcConnector) HandleCallback(s connector.Scopes, r *http.Request) (ide
 
 // Refresh is implemented for backwards compatibility, even though it's a no-op.
 func (c *oidcConnector) Refresh(ctx context.Context, s connector.Scopes, identity connector.Identity) (connector.Identity, error) {
+	t := &oauth2.Token{
+		RefreshToken: string(identity.ConnectorData),
+		Expiry:       time.Now().Add(-time.Hour),
+	}
+	token, err := c.oauth2Config.TokenSource(ctx, t).Token()
+	if err != nil {
+		return identity, fmt.Errorf("oidc: failed to get token: %v", err)
+	}
+
+	rawIDToken, ok := token.Extra("id_token").(string)
+	if !ok {
+		return identity, errors.New("oidc: no id_token in token response")
+	}
+	idToken, err := c.verifier.Verify(ctx, rawIDToken)
+	if err != nil {
+		return identity, fmt.Errorf("oidc: failed to verify ID Token: %v", err)
+	}
+
+	var claims struct {
+		Username      string `json:"name"`
+		Email         string `json:"email"`
+		EmailVerified bool   `json:"email_verified"`
+		HostedDomain  string `json:"hd"`
+	}
+	if err := idToken.Claims(&claims); err != nil {
+		return identity, fmt.Errorf("oidc: failed to decode claims: %v", err)
+	}
+
+	if len(c.hostedDomains) > 0 {
+		found := false
+		for _, domain := range c.hostedDomains {
+			if claims.HostedDomain == domain {
+				found = true
+				break
+			}
+		}
+
+		if !found {
+			return identity, fmt.Errorf("oidc: unexpected hd claim %v", claims.HostedDomain)
+		}
+	}
+
+	identity = connector.Identity{
+		UserID:        idToken.Subject,
+		Username:      claims.Username,
+		Email:         claims.Email,
+		EmailVerified: claims.EmailVerified,
+		ConnectorData: []byte(token.RefreshToken),
+	}
 	return identity, nil
 }