PHP processing steps to apply to a URL to make it safe

From	James Harris <james.harris.1@gmail.com>
Newsgroups	comp.lang.php
Subject	PHP processing steps to apply to a URL to make it safe
Date	2016-02-17 09:37 +0000
Organization	A noiseless patient Spider
Message-ID	<na1es3$rsd$1@dont-email.me> (permalink)

Show all headers | View raw

In line with the principle of a program vetting its input, this is about 
vetting the supplied URL.

In order to process a URL or parts of a URL in PHP what processing ought 
to be applied to it? I have been using some steps which I will write 
below but I am becoming increasingly uncertain that I have covered all 
the bases.

The main concern is safety - ensuring that the PHP code is protected 
against anything that might otherwise trip it up. The second concern is 
correctness in even corner cases such as odd browsers or extended 
character sets.

I have been working with $_SERVER["REQUEST_URI"], in case that is relevant.

Steps so far:

   urldecode to convert %nn etc

   trim "/" from the ends in order to normalise

   check each character is from an allowed set

   check there are no // parts

   check there are no .. parts

All needed? Any not needed? Latest firefox strips out any .. entries 
before sending the URL but I am not sure that all earlier browsers would.

In addition to the above, could the URL be in Unicode form? I was 
thinking to change to index through it with

   $uri[n]

but I gather that will index bytes and not characters. Could the URL 
string that PHP receives be stored as Unicode and should something like 
mb_substr be used instead?

That's all the steps I have come up with so far. It seems a lot. 
Presumably you guys have steps you use yourselves. Are all the things I 
have listed necessary? Is there anything else that should be done to 
process URLs (or components thereof) safely and correctly?

James

Back to comp.lang.php | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-17 09:37 +0000
  Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-17 11:05 +0100
    Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-17 15:04 +0000
      Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 10:54 -0500
        Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-18 01:09 +0000
          Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 21:12 -0500
            Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 19:07 +0000
              Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-20 21:07 +0100
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 20:35 +0000
                Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-20 21:40 +0100
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 21:02 +0000
              Re: PHP processing steps to apply to a URL to make it safe gordonb.lkcah@burditt.org (Gordon Burditt) - 2016-02-29 21:29 -0600
      Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-17 23:33 +0100
        Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-18 01:12 +0000
          Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-18 21:48 +0100
        Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-18 08:05 +0100
          Re: PHP processing steps to apply to a URL to make it safe Tim Streater <timstreater@greenbee.net> - 2016-02-18 09:59 +0000
            Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-18 10:29 +0000
              Re: PHP processing steps to apply to a URL to make it safe Tim Streater <timstreater@greenbee.net> - 2016-02-18 11:36 +0000
            Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-18 15:44 +0100
          Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-18 21:47 +0100
      Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-18 08:02 +0100
        Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 19:29 +0000
          Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-20 21:37 +0100
            Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 21:37 +0000
              Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-21 15:02 +0100
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-21 15:02 +0000
  Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 08:19 -0500
    Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 14:43 +0100
      Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-17 15:04 +0100
        Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 15:17 +0100
          Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-17 15:47 +0100
            Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 15:57 +0100
              Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 10:57 -0500
                Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 17:10 +0100
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 12:11 -0500
                Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 18:51 +0100
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 12:55 -0500
              Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-17 19:06 +0100
                Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 20:19 +0100
                Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-18 08:18 +0100
                Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-18 09:20 +0100
                Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-18 15:48 +0100
                Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-18 16:25 +0100
                Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-18 17:00 +0100
                Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-18 22:26 +0100
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-18 10:48 -0500
            Re: PHP processing steps to apply to a URL to make it safe "Christoph M. Becker" <cmbecker69@arcor.de> - 2016-02-17 16:38 +0100
              Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 10:56 -0500
              Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-17 19:08 +0100
              Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-17 23:35 +0100
          Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 09:56 -0500
            Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 16:44 +0100
              Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 12:12 -0500
                Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 19:04 +0100
      Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 09:55 -0500
        Re: PHP processing steps to apply to a URL to make it safe "R.Wieser" <address@not.available> - 2016-02-17 16:39 +0100
          Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 11:00 -0500
    Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-17 15:15 +0000
      Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-17 11:05 -0500
        Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-18 01:18 +0000
      Re: PHP processing steps to apply to a URL to make it safe Arno Welzel <usenet@arnowelzel.de> - 2016-02-17 19:14 +0100
        Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-18 00:19 +0000
      Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-17 23:36 +0100
  Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-17 23:26 +0100
    Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-18 00:36 +0000
      Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-18 22:03 +0100
        Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 19:38 +0000
          Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-20 21:17 +0100
            Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-20 20:56 +0000
              Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-20 23:48 +0100
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-21 09:37 +0000
                Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-21 14:42 +0100
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-21 15:03 +0000
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-21 14:09 -0500
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-21 19:34 +0000
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-21 14:49 -0500
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-21 19:56 +0000
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-21 20:29 -0500
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-22 07:30 +0000
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-22 08:13 -0500
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-22 15:01 +0000
                Re: PHP processing steps to apply to a URL to make it safe Jerry Stuckle <jstucklex@attglobal.net> - 2016-02-22 10:31 -0500
                Re: PHP processing steps to apply to a URL to make it safe Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-22 00:10 +0100
                Re: PHP processing steps to apply to a URL to make it safe James Harris <james.harris.1@gmail.com> - 2016-02-21 23:45 +0000
  Re: PHP processing steps to apply to a URL to make it safe pittendrigh <Sandy.Pittendrigh@gmail.com> - 2016-03-22 05:23 -0700

csiph-web