From d8a93d506a524efd15858dc2fc5c15b2f21eebaf Mon Sep 17 00:00:00 2001
From: Raffael Sahli <sahli@gyselroth.com>
Date: Tue, 3 Mar 2020 14:20:24 +0100
Subject: [PATCH] fix: native clients must be able to request a dynamic port
 rfc8252#section-7.3

fixes #284
---
 authorize_helper.go      | 37 ++++++++++++++++++++++++++++++++++++-
 authorize_helper_test.go | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/authorize_helper.go b/authorize_helper.go
index 5c73e428..6aa087a5 100644
--- a/authorize_helper.go
+++ b/authorize_helper.go
@@ -23,6 +23,7 @@ package fosite
 
 import (
 	"net/url"
+	"regexp"
 	"strings"
 
 	"github.com/asaskevich/govalidator"
@@ -83,7 +84,7 @@ func MatchRedirectURIWithClientRedirectURIs(rawurl string, client Client) (*url.
 			// If no redirect_uri was given and the client has exactly one valid redirect_uri registered, use that instead
 			return redirectURIFromClient, nil
 		}
-	} else if rawurl != "" && StringInSlice(rawurl, client.GetRedirectURIs()) {
+	} else if rawurl != "" && isMatchingRedirectURI(rawurl, client.GetRedirectURIs()) {
 		// If a redirect_uri was given and the clients knows it (simple string comparison!)
 		// return it.
 		if parsed, err := url.Parse(rawurl); err == nil && IsValidRedirectURI(parsed) {
@@ -95,6 +96,40 @@ func MatchRedirectURIWithClientRedirectURIs(rawurl string, client Client) (*url.
 	return nil, errors.WithStack(ErrInvalidRequest.WithHint(`The "redirect_uri" parameter does not match any of the OAuth 2.0 Client's pre-registered redirect urls.`))
 }
 
+// Match a requested  redirect URI against a pool of registered client URIs
+//
+// Test a given redirect URI against a pool of URIs provided by a registered client.
+// If the OAuth 2.0 Client has loopback URIs registered either an IPv4 URI http://127.0.0.1 or
+// an IPv6 URI http://[::1] a client is allowed to request a dynamic port and the server MUST accept
+// it as a valid redirection uri.
+//
+// https://tools.ietf.org/html/rfc8252#section-7.3
+// Native apps that are able to open a port on the loopback network
+// interface without needing special permissions (typically, those on
+// desktop operating systems) can use the loopback interface to receive
+// the OAuth redirect.
+//
+// Loopback redirect URIs use the "http" scheme and are constructed with
+// the loopback IP literal and whatever port the client is listening on.
+func isMatchingRedirectURI(uri string, haystack []string) bool {
+	for _, b := range haystack {
+		l := strings.ToLower(b)
+		if l == strings.ToLower(uri) || isLoopbackURI(uri, l) {
+			return true
+		}
+	}
+	return false
+}
+
+func isLoopbackURI(uri string, registeredURI string) bool {
+	if registeredURI != "http://127.0.0.1" && registeredURI != "http://[::1]" {
+		return false
+	}
+
+	match, _ := regexp.MatchString("http://(127.0.0.1|\\[::1\\]):?(\\d+)?", uri)
+	return match
+}
+
 // IsValidRedirectURI validates a redirect_uri as specified in:
 //
 // * https://tools.ietf.org/html/rfc6749#section-3.1.2
diff --git a/authorize_helper_test.go b/authorize_helper_test.go
index 71f786a6..6d1c5f0b 100644
--- a/authorize_helper_test.go
+++ b/authorize_helper_test.go
@@ -154,6 +154,46 @@ func TestDoesClientWhiteListRedirect(t *testing.T) {
 			url:     "https://bar.com/cb123",
 			isError: true,
 		},
+		{
+			client:   &DefaultClient{RedirectURIs: []string{"http://[::1]"}},
+			url:      "http://[::1]:1024",
+			isError:  false,
+			expected: "http://[::1]:1024",
+		},
+		{
+			client:   &DefaultClient{RedirectURIs: []string{"http://[::1]"}},
+			url:      "http://[::1]:1024/cb",
+			isError:  false,
+			expected: "http://[::1]:1024/cb",
+		},
+		{
+			client:  &DefaultClient{RedirectURIs: []string{"http://[::1]"}},
+			url:     "http://foo.bar/bar",
+			isError: true,
+		},
+		{
+			client:   &DefaultClient{RedirectURIs: []string{"http://127.0.0.1"}},
+			url:      "http://127.0.0.1:1024",
+			isError:  false,
+			expected: "http://127.0.0.1:1024",
+		},
+		{
+			client:   &DefaultClient{RedirectURIs: []string{"http://127.0.0.1"}},
+			url:      "http://127.0.0.1:64000/cb",
+			isError:  false,
+			expected: "http://127.0.0.1:64000/cb",
+		},
+		{
+			client:   &DefaultClient{RedirectURIs: []string{"http://127.0.0.1"}},
+			url:      "http://127.0.0.1",
+			isError:  false,
+			expected: "http://127.0.0.1",
+		},
+		{
+			client:  &DefaultClient{RedirectURIs: []string{"http://127.0.0.1"}},
+			url:     "http://foo.bar/bar",
+			isError: true,
+		},
 	} {
 		redir, err := MatchRedirectURIWithClientRedirectURIs(c.url, c.client)
 		assert.Equal(t, c.isError, err != nil, "%d: %s", k, err)