From 910a2acfa703bd302c447c4db43193d70863771e Mon Sep 17 00:00:00 2001
From: Pertti Kroger <pertti@qvik.fi>
Date: Wed, 2 Sep 2020 15:32:42 +0300
Subject: [PATCH] Open the current page rather than the target page on
 navigations to unknown pages.

This fixes some issuer's flows.
---
 .../SwedbankPayWebViewController.swift        | 41 +++++++++++++++----
 SwedbankPaySDK/Resources/good_redirects       | 17 +++++---
 2 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/SwedbankPaySDK/Classes/SwedbankPayWebViewController.swift b/SwedbankPaySDK/Classes/SwedbankPayWebViewController.swift
index 0a63cc9..396a9e0 100644
--- a/SwedbankPaySDK/Classes/SwedbankPayWebViewController.swift
+++ b/SwedbankPaySDK/Classes/SwedbankPayWebViewController.swift
@@ -181,19 +181,44 @@ extension SwedbankPayWebViewController : WKNavigationDelegate {
     
     private func decidePolicyForNormalLink(url: URL, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
         if WKWebView.canOpen(url: url), let delegate = delegate {
+            // A regular http(s) url. Check if it matches the list of
+            // tested working pages.
             delegate.allowWebViewNavigation(to: url) { allowed in
-                self.finishDecidePolicyForNormalLink(url: url, shouldUseWebView: allowed, decisionHandler: decisionHandler)
+                if !allowed {
+                    // Not tested or incompatible with web view;
+                    // must continue process is Safari.
+                    self.continueNavigationInBrowser(url: url)
+                }
+                decisionHandler(allowed ? .allow : .cancel)
             }
         } else {
-            finishDecidePolicyForNormalLink(url: url, shouldUseWebView: false, decisionHandler: decisionHandler)
+            // A custom-scheme url. Must let another app take care of it.
+            attemptOpenInExternalApp(url: url)
+            decisionHandler(.cancel)
         }
     }
     
-    private func finishDecidePolicyForNormalLink(url: URL, shouldUseWebView: Bool, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
-        if !shouldUseWebView {
-            attemptOpenCustomSchemeLink(url: url)
-        }
-        decisionHandler(shouldUseWebView ? .allow : .cancel)
+    private func continueNavigationInBrowser(url: URL) {
+        // Naively, one would think that opening the original navigation
+        // target here would work. However, testing has shown that not
+        // to be the case. Without expending time to work out the exact
+        // problem, it can be assumed that the Swedbank Pay page that
+        // redirects to the payment instrument issuer page sets up
+        // the browser environment in some way that some issuer pages
+        // depend on. Therefore the approach is that when we encounter
+        // a navigation to a page outside the goodlist, we reopen the
+        // _current_ page in the browser. This works for the Swedbank Pay
+        // "PrepareAcsChallenge" page, and it can be assumed that it will
+        // continue to work for that page. Whether it works if any previously
+        // tested flow is changed to navigate to previously unknown pages
+        // is anyone's guess, but even in those cases it is the best we can
+        // do, since attempting to restart the whole flow by opening the
+        // "originating" Swedbank Pay page will, in general not work
+        // (this has been tested). In any case, it is important to
+        // keep testing the SDK against different issuers and keep
+        // the goodlist up-to-date.
+        let target = isAtRoot ? url : (webView.url ?? url)
+        attemptOpenInExternalApp(url: target)
     }
     
     private func ensurePath(url: URL) -> URL {
@@ -217,7 +242,7 @@ extension SwedbankPayWebViewController : WKNavigationDelegate {
         }
     }
     
-    private func attemptOpenCustomSchemeLink(url: URL) {
+    private func attemptOpenInExternalApp(url: URL) {
         if #available(iOS 10, *) {
             UIApplication.shared.open(url, options: [:], completionHandler: nil)
         } else {
diff --git a/SwedbankPaySDK/Resources/good_redirects b/SwedbankPaySDK/Resources/good_redirects
index a07300a..212a80f 100644
--- a/SwedbankPaySDK/Resources/good_redirects
+++ b/SwedbankPaySDK/Resources/good_redirects
@@ -2,13 +2,18 @@
 # One pattern per line. At this time support domain names only.
 # * or ** allowed at start of domain name; * matches a single subdomain, ** matches nested subdomains
 # Lines starting with # are comments
+
 **.payex.com
+
+acs4.sparebank1.no
+
+# Transferwise
+idcheck.acs.touchtechpayments.com
+
+# Revolut
+verifiedbyvisa.acs.touchtechpayments.com
+
+# OP (fi)
 op.wlp-acs.com
 kultaraha.op.fi
 acs1.luottokunta.fi
-acs4.sparebank1.no
-
-# This is based on two PSPs, Revolut and Transferwise, which both use foo.acs.touchtechpayments.com
-# However! These will malfunction if psp-ecommerce.payex.com is opened in webview and foo.acs.touchtechpayments.com in Safari
-# To minimize the chance of users getting stuck, just allow all *.acs.touchtechpayments.com for now
-*.acs.touchtechpayments.com