README.md

@@ -1,6 +1,6 @@
 # Comics Viewer
 
-This small project provides a web based viewer for comics in the CBZ and CBR formats. Bear in mind that much of the code in this project is **very** old and has had lots of "just get it working" updates over the decades (not kidding) to keep up with changing PHP API requirements. It is *sooooo* not pretty (but should be *safe*).
+This small project provides a web based viewer for comics in the CBZ and CBR formats.
 
 ## This project requires
 

ajax/showcomic.php

@@ -5,18 +5,16 @@ require '../header.php';
 require_login();
 
 if ( isset($_REQUEST['comic']) ) {
-   $comicfull = realpath(COMICSDIR . base64_decode(urldecode($_REQUEST['comic'])));
+   $comic = makePathSafe(base64_decode(urldecode(($_REQUEST['comic']))));
-   if ( $comicfull === false ) exit();
+   $comicfull = COMICSDIR . $comic;
-   if ( substr($comicfull, 0, strlen(COMICSDIR)) != COMICSDIR ) exit();
-   $comic = substr($comicfull, strlen(COMICSDIR));
    $comicoutputurl = "comics" . str_replace("#", "", $comic) . "/";
    $comicoutputfull = "../" . EXTRACTSDIR . str_replace("#", "", $comic) . "/";
 } else {
    exit();
 }
 
-$ext = strtolower(substr($comicfull, -3));
+$ext = strtolower(substr($comic, -3));
-$_SESSION['comfile'] = basename($comicfull);
+$_SESSION['comfile'] = basename($comic);
 
 $data = array();
 

downloadcomic.php

@@ -5,9 +5,8 @@ require 'header.php';
 require_login();
 
 if ( isset($_REQUEST['comic']) ) {
-   $comicfull = realpath(COMICSDIR . base64_decode(urldecode($_REQUEST['comic'])));
+   $comic = makePathSafe(base64_decode(urldecode(($_REQUEST['comic']))));
-   if ( $comicfull === false ) exit();
+   $comicfull = COMICSDIR . $comic;
-   if ( substr($comicfull, 0, strlen(COMICSDIR)) != COMICSDIR ) exit();
 } else {
    exit();
 }

functions.php

@@ -5,6 +5,30 @@ function microtime_float() {
    return ((float)$usec + (float)$sec);
 }
 
+function makePathSafe($path = "") {
+   if ( $path == "" ) return "";
+   // Stick forward slashes on the ends to make matching more consistent
+   $path = "/" . $path . "/";
+   // Remove all instances of dots between forward slashes
+   while ( preg_match("/\/\.{0,}\//", $path) ) {
+      $path = preg_replace("/\/\.{0,}\//", "/", $path);
+   }
+   // Replace all instances of two consecutive forward slashes
+   while ( strpos($path, "//") !== false ) {
+      $path = str_replace("//", "/", $path);
+   }
+   // Remove all leading forward slashes
+   while ( substr($path, 0, 1) == '/' ) {
+      $path = substr($path, 1);
+   }
+   // Remove all trailing forward slashes
+   while ( substr($path, -1) == '/' ) {
+      $path = substr($path, 0, strlen($path)-1);
+   }
+   $path = "/" . $path;
+   return $path;
+}
+
 function makeThumb($item = "") {
    if ( $item == "" ) { return false; }
    if ( is_dir($item) ) {