fix redirect url param handling (oauth2-proxy#10)

* Added conditional to prevent user-supplied redirect URL getting
clobbered

Change-type: patch

* use redirectURL as OAuthCallbackURL (as it should be!)

Change-type: patch

CHANGELOG.md

@@ -6,6 +6,7 @@
 - [#68](https://github.com/pusher/oauth2_proxy/pull/68) forward X-Auth-Access-Token header (@davidholsgrove)
 - [#41](https://github.com/pusher/oauth2_proxy/pull/41) Added option to manually specify OIDC endpoints instead of relying on discovery
 - [#83](https://github.com/pusher/oauth2_proxy/pull/83) Add `id_token` refresh to Google provider (@leki75)
+- [#10](https://github.com/pusher/oauth2_proxy/pull/10) fix redirect url param handling (@dt-rush)
 
 # v3.1.0
 

oauthproxy.go

@@ -183,7 +183,9 @@ func NewOAuthProxy(opts *Options, validator func(string) bool) *OAuthProxy {
 	}
 
 	redirectURL := opts.redirectURL
-	redirectURL.Path = fmt.Sprintf("%s/callback", opts.ProxyPrefix)
+	if redirectURL.String() == "" {
+		redirectURL.Path = fmt.Sprintf("%s/callback", opts.ProxyPrefix)
+	}
 
 	log.Printf("OAuthProxy configured for %s Client ID: %s", opts.provider.Data().ProviderName, opts.ClientID)
 	refresh := "disabled"
@@ -218,7 +220,7 @@ func NewOAuthProxy(opts *Options, validator func(string) bool) *OAuthProxy {
 		SignInPath:        fmt.Sprintf("%s/sign_in", opts.ProxyPrefix),
 		SignOutPath:       fmt.Sprintf("%s/sign_out", opts.ProxyPrefix),
 		OAuthStartPath:    fmt.Sprintf("%s/start", opts.ProxyPrefix),
-		OAuthCallbackPath: fmt.Sprintf("%s/callback", opts.ProxyPrefix),
+		OAuthCallbackPath: redirectURL.Path,
 		AuthOnlyPath:      fmt.Sprintf("%s/auth", opts.ProxyPrefix),
 
 		ProxyPrefix:        opts.ProxyPrefix,