From 5dcf053b4c3b054a6e52d580ad10a0b9de135d3b Mon Sep 17 00:00:00 2001
From: Mario <mario@mariovavti.com>
Date: Sat, 4 Sep 2021 07:32:01 +0000
Subject: implement strict mode for base64url_decode() and introduce
 unpack_link_id()

---
 include/text.php | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

(limited to 'include/text.php')

diff --git a/include/text.php b/include/text.php
index e0910f83e..bd2df45aa 100644
--- a/include/text.php
+++ b/include/text.php
@@ -2156,12 +2156,12 @@ function base64url_encode($s, $strip_padding = true) {
 	return $s;
 }
 
-function base64url_decode($s) {
+function base64url_decode($s, $strict = false) {
 	if(is_array($s)) {
 		logger('base64url_decode: illegal input: ' . print_r(debug_backtrace(), true));
 		return $s;
 	}
-	return base64_decode(strtr($s,'-_','+/'));
+	return base64_decode(strtr($s,'-_','+/'), $strict);
 }
 
 
@@ -2175,12 +2175,12 @@ function base64special_encode($s, $strip_padding = true) {
 	return $s;
 }
 
-function base64special_decode($s) {
+function base64special_decode($s, $strict = false) {
 	if(is_array($s)) {
 		logger('base64url_decode: illegal input: ' . print_r(debug_backtrace(), true));
 		return $s;
 	}
-	return base64_decode(strtr($s,',.','+/'));
+	return base64_decode(strtr($s,',.','+/'), $strict);
 }
 
 /**
@@ -3589,6 +3589,21 @@ function gen_link_id($mid) {
 	return $mid;
 }
 
+/**
+ * @brief check if the provided string starts with 'b64.' and try to decode it if so.
+ * If it could be decoded return the decoded string or false if decoding failed.
+ * If the string does not start with 'b64.', return the string as is.
+ *
+ * @param string $mid
+ * @return string|boolean false
+ */
+function unpack_link_id($mid) {
+	if (is_string($mid) && strpos($mid, 'b64.') === 0) {
+		$mid = @base64url_decode(substr($mid, 4), true);
+		return $mid;
+	}
+	return $mid;
+}
 
 // callback for array_walk
 
-- 
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