PHP utility collection with hybrid and fluent APIs.

βŒˆβŒ‹ βŽ‡ branch:  hybrid7 libraries

Update of "input"

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Artifact ID: 123cee651e8f934f7744bc3134a4db52934e8d34
Page Name:input
Date: 2014-03-20 00:55:59
Original User: mario
Parent: ffb0ac9d87386be728784a019aeb7a1c18661ec1 (diff)
Next 48f5f077adb6fb1ce4e15f7ffef783f97c38e18a

new input()

The input class wraps the superglobals $_REQUEST, $_GET, $_POST, $_SERVER and $_COOKIE. It provides streamlined sanitization with unobtrusive filter names and a unique semi-fluent syntax:

    $_REQUEST<mark style="background: linear-gradient(#f7f6f5,#f7e655,#f7f6f5); color:#fa3">->text</mark>["content"]

Filtering functions can also be chained, as in $_GET->text->html["title"]. There are various whitelisting and sanitizing methods for that.

  • This approach addresses input constraint validation at the earliest feasible entry point.

  • Unifies access through a central verification mechanism.

  • Allows reliable input interpolation instantly into many target contexts.

Additionally it can still shadow/audit casual and unverfied accesses. Its overall API simplicity is meant to encourage safety; through minimal effort.

Available filters

There's a wide range of built-in methods. Often the basic filters are sufficient and best suited for combination.

Method Type Sample Usage
int cast 123 Only numeric characters, cast to integer.
name white abc12_x3 Alphanumeric symbols only.
id white xy_2.1 Alphanumeric chars, dot and underscore.
words white abc def Text with minimal interpunction (only spaces allowed).
text white Hello, World! Common natural text with basic interpunction (including quotes, but no < >).
filename filter basename.txt Replace all non-alphanumeric characters with underscores.
float cast 3.14159 Cast to float.
boolean cast true, false Converts "false/true" or "0/1" or "off/on" and "no/yes" to boolean.
ascii white Aa#:β€œ,n0~ Characters in the ASCII range 0 .. 127
nocontrol white Aa#:β€œ,n~ Fiilters out control characters (< 32), except r n t.
spaces filter Single line Turns linebreaks / whitespace (r n t) into spaces only.
q black β€œvalueβ€œ Shorthand for addslashes.
escape black []β€œ{}'$`!Β΄&?/><|*~;^ Broader escaping of well-known meta charactes (quotes and regex).
html filter &amp; htmlspecialchars (shorthand)
Structural Following filters constrain specific input formats.
datetime white 1999-12-31T23:59:59Z HTML5 datetime values
date white 2015-07-17 Just date string.
time white 23:59:20.17 Time specifier.
color white #FF5022 Hex color value.
tel white "+1-347-2214144 International-format telephone number.
iconv filter
Convert input to UTF-8
utf7 black
Filter some UTF-7 out.
ip white ::1 IPv4 or IPv6 address
ipv4 white IPv4 address only
public white Validate IP to be public.
email white you Syntactically valid email address.
url white
Ensure URL syntax xxx:///
http white http:// localhost/ More conservative http:// URL constraint.
uri white
More generic URI syntax.
xml cast
Create a SimpleXML object from input.
json cast {β€žkeyβ€œ:β€œvalueβ€œ} json_decode()
purify filter <b>basic</b> Utilizes HTMLPurifier
NOP Virtual / control filters.
log control
Raw value access with logging.
raw control
Raw access with E_NOTICE (is the default).
disallow control
Disallow unfiltered variable access (configurable per INPUT_DIRECT).
is control
Is a meta filter, that applies the following filter chain, then checks if the content would have passed unaffected. Returns a boolean if all constraints were matched.
Parameterized These filters require method access $_GET->default(β€židβ€œ, β€žindexβ€œ) instead of the plain array key syntax.
length(ID, 20) filter Hello Wo Cuts strings to maximum given length.
range(ID, 1, 15) white 17 Constrains numeric input to the given range.
default filter … Uses default value, if no input present.
regex white/black … Custom regular expression method ->regex("field", "/(abc)/")
in_array white a,b,c Can be used with array parameter, or a simpler comma-separated of allowed values.

Multi-Apply Following filters work on a set of input variables, instead of a single one.
array control
Is automatically applied to input subarrays, so filters are run on each entry.
list control
Combine multiple input variables per name (comma-separated list) and apply filtering collectively; finally return a named result array.
multi control
Also grabs a list of input variables. But does not run filters on scalars within, but pass the combined set to filter functions. This is used in combination with e.g. http_build_query
Global functions
strtolower filter
Any global function can be chained actually. It just needs to accept one parameter, modify its input (string), and return something in return. Custom userland functions can thus be utilized.
urlencode filter
strip_tags filter

Inadvised filters Care should be taken here. Liberal application will lead to a false sense of security.
sql filter
Configurable PDO::quote shorthand.
mysql filter
Shorthand to mysql_real_escape_string (doubly discouraged).
xss black
Minimal XSS blacklist

As mentioned, any global function can be utilized implicitly. A few core string functions are useful in this context. But the intended target are custom functions.

Binding filters

One can even bind new functions or class methods using:

 $_GET->_filtername = array("AppFilter", "validSessionID");

It's imperative to shadow the filternames using an underscore _ prefix however. See for example input.inspekt.php for some examples. This allows them to be chained still:


(Btw, to use some of the input filter methods statically and outside of their scope, one could use $value = input::_datetime($value); for instance.)

Complex filters

With ->list and ->multi you can utilize some more crafty features. For instance:


Will rebuild an URL-encoded string from three input variables.

Wrapper implementation

Basically the filters are initialized for all superglobals like:

 $_GET = new input($_GET);

The original variables are stored in ->__vars[] internally. Each $_GET->filtername pseudo-method access is accumulated in a filter chain.

The first use of array ["key"] or method ("key") requests, applies the filter chain to the named input variable, then returns the constrained value.

Filter chain defaults

It's possible to define a default filter for remaining $_GET["old"] accesses with the INPUT_DIRECT constant.

  • Per default it uses "raw" which just prints a notice.
  • It can also be set to "disable" to prevent such uses.
  • Another alternative would be "q" to emulate magic quotes (not recommended).
  • Or using "sql" to securely use $_POST["fields"] in SQL strings, if that's the default target (also not recommended).

Another option is to predefine a filter chain on a particular superglobal with ->always():


Then any $_RAW["access"] would still use these filters. Yet additional more context-specific filters could also be intermixed.

It's equivalent to having the filter chain built up, before accessing an entry:


Btw, to reset a default filter chain, use ->__always = array();

Predeclaring filters for raw access

While this somewhat amounts to magic_quotes 2.0, you can also pre-define filter chains on a variable name basis:

 $_GET->__rules["old_id"] = array("int", array());

This is suitable for bolting a minimum of safety onto old code, whose data flow is structurally hard to fix otherwise.

Differences to plain $_GET / $_POST / $_REQUEST </h3>

Because the whole ArrayAccess and Iterator interfaces are implemented, it's easy to transition existing code to new input(). There are few behavioural discrepancies.

One thing that won't work however is the common / olden idiom:

 if ($_POST) {

To probe for presence of input data, one should check one of the keys, or rather:

  if (count($_POST)) {

Which has the same effect.

->has() ->no() ->keys()

These three convenience methods make some idioms more readble. Instead of testing for isset($_GET["key"]) one can now write: $_GET->has("key"). Or to probe for the opposite $_GET->no("sleep").

In place of array_keys() there's now $_REQUEST->keys(), also slightly shorter.

Notice emission

Syntactic salt ala isset($_GET["id"]) ? $_GET["id"] : "" for silent value substitution has become commonplace.

It's made redundant here, because input{} itself already probes for existence of variables. Notices for absent values are only generated afterwards, and only if requested. Thus they can be reenabled when needed, unlike with the isset and ?: supper suppression syntax.

INPUT_DIRECT controls the default filter for $_GET["raw"] access. If it's set to raw then this specific filter name will engage. And raw honors INPUT_SILENCE. Per default it still emits useful notices. If set to 1 it will no more.

Rewritten code can default to $_REQUEST->raw->default("id", 123) however. This combines both the default value substitution, but still permits bringing back notices and hence debugging.

Closing remarks

Using such an input filter does not mean one can forgo database esaping et al. It just adds another layer of format constraining and thus security atop. And it's a very simple and convenient layer. (Complexity seldomly helps with that.)