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[3.1.0] Revamp URI handling of percent encoding and validation.

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git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1709 48356398-32a2-884e-a903-53898d9a118a
This commit is contained in:
Edward Z. Yang 2008-05-14 02:19:00 +00:00
parent 77ce3e8b4a
commit cb5d5d0648
13 changed files with 261 additions and 50 deletions
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2
NEWS
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@ -32,6 +32,8 @@ NEWS ( CHANGELOG and HISTORY ) HTMLPurifier
! Commas, not dashes, used for serializer IDs. This change is forwards-compatible
and allows for version numbers like "3.1.0-dev".
! %HTML.Allowed deals gracefully with whitespace anywhere, anytime!
! HTML Purifier's URI handling is a lot more robust, with much stricter
validation checks and better percent encoding handling.
- InterchangeBuilder now alphabetizes its lists
- Validation error in configdoc output fixed
- Iconv and other encoding errors muted even with custom error handlers that

3
TODO
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@ -11,6 +11,8 @@ If no interest is expressed for a feature that may require a considerable
amount of effort to implement, it may get endlessly delayed. Do not be
afraid to cast your vote for the next feature to be implemented!
- Implement validation for query and for fragment
FUTURE VERSIONS
---------------
@ -47,6 +49,7 @@ FUTURE VERSIONS
AttrDef class). Probably will use CSSTidy class?
# More control over allowed CSS properties using a modularization
# HTML 5 support
# IRI support
- Standardize token armor for all areas of processing
- Convert RTL/LTR override characters to <bdo> tags, or vice versa on demand.
Also, enable disabling of directionality

4
configdoc/usage.xml
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@ -215,12 +215,12 @@
</directive>
<directive id="URI.Disable">
<file name="HTMLPurifier/AttrDef/URI.php">
<line>24</line>
<line>23</line>
</file>
</directive>
<directive id="URI.Munge">
<file name="HTMLPurifier/AttrDef/URI.php">
<line>78</line>
<line>68</line>
</file>
</directive>
<directive id="Core.ColorKeywords">

12
library/HTMLPurifier/AttrDef/URI.php
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@ -7,7 +7,7 @@
class HTMLPurifier_AttrDef_URI extends HTMLPurifier_AttrDef
{
protected $parser, $percentEncoder;
protected $parser;
protected $embedsResource;
/**
@ -15,7 +15,6 @@ class HTMLPurifier_AttrDef_URI extends HTMLPurifier_AttrDef
*/
public function __construct($embeds_resource = false) {
$this->parser = new HTMLPurifier_URIParser();
$this->percentEncoder = new HTMLPurifier_PercentEncoder();
$this->embedsResource = (bool) $embeds_resource;
}
@ -23,9 +22,7 @@ class HTMLPurifier_AttrDef_URI extends HTMLPurifier_AttrDef
if ($config->get('URI', 'Disable')) return false;
// initial operations
$uri = $this->parseCDATA($uri);
$uri = $this->percentEncoder->normalize($uri);
// parse the URI
$uri = $this->parser->parse($uri);
@ -61,13 +58,6 @@ class HTMLPurifier_AttrDef_URI extends HTMLPurifier_AttrDef
$context->destroy('EmbeddedURI');
if (!$ok) return false;
// munge scheme off if necessary (this must be last)
if (!is_null($uri->scheme) && is_null($uri->host)) {
if ($uri_def->defaultScheme == $uri->scheme) {
$uri->scheme = null;
}
}
// back to string
$result = $uri->toString();

20
library/HTMLPurifier/AttrDef/URI/Host.php
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@ -36,11 +36,23 @@ class HTMLPurifier_AttrDef_URI_Host extends HTMLPurifier_AttrDef
$ipv4 = $this->ipv4->validate($string, $config, $context);
if ($ipv4 !== false) return $ipv4;
// validate a domain name here, do filtering, etc etc etc
// A regular domain name.
// We could use this, but it would break I18N domain names
//$match = preg_match('/^[a-z0-9][\w\-\.]*[a-z0-9]$/i', $string);
//if (!$match) return false;
// This breaks I18N domain names, but we don't have proper IRI support,
// so force users to insert Punycode. If there's complaining we'll
// try to fix things into an international friendly form.
// The productions describing this are:
$a = '[a-z]'; // alpha
$an = '[a-z0-9]'; // alphanum
$and = '[a-z0-9-]'; // alphanum | "-"
// domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
$domainlabel = "$an($and*$an)?";
// toplabel = alpha | alpha *( alphanum | "-" ) alphanum
$toplabel = "$a($and*$an)?";
// hostname = *( domainlabel "." ) toplabel [ "." ]
$match = preg_match("/^($domainlabel\.)*$toplabel\.?$/i", $string);
if (!$match) return false;
return $string;
}

65
library/HTMLPurifier/PercentEncoder.php
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@ -2,12 +2,68 @@
/**
* Class that handles operations involving percent-encoding in URIs.
*
* @warning
* Be careful when reusing instances of PercentEncoder. The object
* you use for normalize() SHOULD NOT be used for encode(), or
* vice-versa.
*/
class HTMLPurifier_PercentEncoder
{
/**
* Fix up percent-encoding by decoding unreserved characters and normalizing
* Reserved characters to preserve when using encode().
*/
protected $preserve = array();
/**
* String of characters that should be preserved while using encode().
*/
public function __construct($preserve = false) {
// unreserved letters, ought to const-ify
for ($i = 48; $i <= 57; $i++) $this->preserve[$i] = true; // digits
for ($i = 65; $i <= 90; $i++) $this->preserve[$i] = true; // upper-case
for ($i = 97; $i <= 122; $i++) $this->preserve[$i] = true; // lower-case
$this->preserve[45] = true; // Dash -
$this->preserve[46] = true; // Period .
$this->preserve[95] = true; // Underscore _
$this->preserve[126]= true; // Tilde ~
// extra letters not to escape
if ($preserve !== false) {
for ($i = 0, $c = strlen($preserve); $i < $c; $i++) {
$this->preserve[ord($preserve[$i])] = true;
}
}
}
/**
* Our replacement for urlencode, it encodes all non-reserved characters,
* as well as any extra characters that were instructed to be preserved.
* @note
* Assumes that the string has already been normalized, making any
* and all percent escape sequences valid. Percents will not be
* re-escaped, regardless of their status in $preserve
* @param $string String to be encoded
* @return Encoded string.
*/
public function encode($string) {
$ret = '';
for ($i = 0, $c = strlen($string); $i < $c; $i++) {
if ($string[$i] !== '%' && !isset($this->preserve[$int = ord($string[$i])]) ) {
$ret .= '%' . sprintf('%02X', $int);
} else {
$ret .= $string[$i];
}
}
return $ret;
}
/**
* Fix up percent-encoding by decoding unreserved characters and normalizing.
* @warning This function is affected by $preserve, even though the
* usual desired behavior is for this not to preserve those
* characters. Be careful when reusing instances of PercentEncoder!
* @param $string String to normalize
*/
public function normalize($string) {
@ -27,12 +83,7 @@ class HTMLPurifier_PercentEncoder
continue;
}
$int = hexdec($encoding);
if (
($int >= 48 && $int <= 57) || // digits
($int >= 65 && $int <= 90) || // uppercase letters
($int >= 97 && $int <= 122) || // lowercase letters
$int == 126 || $int == 45 || $int == 46 || $int == 95 // ~-._
) {
if (isset($this->preserve[$int])) {
$ret .= chr($int) . $text;
continue;
}

70
library/HTMLPurifier/URI.php
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@ -1,7 +1,12 @@
<?php
/**
* HTML Purifier's internal representation of a URI
* HTML Purifier's internal representation of a URI.
* @note
* Internal data-structures are completely escaped. If the data needs
* to be used in a non-URI context (which is very unlikely), be sure
* to decode it first. The URI may not necessarily be well-formed until
* validate() is called.
*/
class HTMLPurifier_URI
{
@ -49,13 +54,27 @@ class HTMLPurifier_URI
}
/**
* Generic validation method applicable for all schemes
* Generic validation method applicable for all schemes. May modify
* this URI in order to get it into a compliant form.
* @param $config Instance of HTMLPurifier_Config
* @param $context Instance of HTMLPurifier_Context
* @return True if validation/filtering succeeds, false if failure
*/
public function validate($config, $context) {
// ABNF definitions from RFC 3986
$chars_sub_delims = '!$&\'()*+,;=';
$chars_gen_delims = ':/?#[]@';
$chars_pchar = $chars_sub_delims . ':@';
// validate scheme (MUST BE FIRST!)
if (!is_null($this->scheme) && is_null($this->host)) {
$def = $config->getDefinition('URI');
if ($def->defaultScheme === $this->scheme) {
$this->scheme = null;
}
}
// validate host
if (!is_null($this->host)) {
$host_def = new HTMLPurifier_AttrDef_URI_Host();
@ -63,18 +82,51 @@ class HTMLPurifier_URI
if ($this->host === false) $this->host = null;
}
// validate username
if (!is_null($this->userinfo)) {
$encoder = new HTMLPurifier_PercentEncoder($chars_sub_delims . ':');
$this->userinfo = $encoder->encode($this->userinfo);
}
// validate port
if (!is_null($this->port)) {
if ($this->port < 1 || $this->port > 65535) $this->port = null;
}
// query and fragment are quite simple in terms of definition:
// *( pchar / "/" / "?" ), so define their validation routines
// when we start fixing percent encoding
// path gets to be validated against a hodge-podge of rules depending
// on the status of authority and scheme, but it's not that important,
// esp. since it won't be applicable to everyone
// validate path
$path_parts = array();
$segments_encoder = new HTMLPurifier_PercentEncoder($chars_pchar . '/');
if (!is_null($this->host)) {
// path-abempty (hier and relative)
$this->path = $segments_encoder->encode($this->path);
} elseif ($this->path !== '' && $this->path[0] === '/') {
// path-absolute (hier and relative)
if (strlen($this->path) >= 2 && $this->path[1] === '/') {
// This shouldn't ever happen!
$this->path = '';
} else {
$this->path = $segments_encoder->encode($this->path);
}
} elseif (!is_null($this->scheme) && $this->path !== '') {
// path-rootless (hier)
// Short circuit evaluation means we don't need to check nz
$this->path = $segments_encoder->encode($this->path);
} elseif (is_null($this->scheme) && $this->path !== '') {
// path-noscheme (relative)
// (once again, not checking nz)
$segment_nc_encoder = new HTMLPurifier_PercentEncoder($chars_sub_delims . '@');
$c = strpos($this->path, '/');
if ($c !== false) {
$this->path =
$segment_nc_encoder->encode(substr($this->path, 0, $c)) .
$segments_encoder->encode(substr($this->path, $c));
} else {
$this->path = $segment_nc_encoder->encode($this->path);
}
} else {
// path-empty (hier and relative)
$this->path = ''; // just to be safe
}
return true;

41
library/HTMLPurifier/URIParser.php
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@ -2,24 +2,39 @@
/**
* Parses a URI into the components and fragment identifier as specified
* by RFC 2396.
* @todo Replace regexps with a native PHP parser
* by RFC 3986.
*/
class HTMLPurifier_URIParser
{
/**
* Parses a URI
* Instance of HTMLPurifier_PercentEncoder to do normalization with.
*/
protected $percentEncoder;
public function __construct() {
$this->percentEncoder = new HTMLPurifier_PercentEncoder();
}
/**
* Parses a URI.
* @param $uri string URI to parse
* @return HTMLPurifier_URI representation of URI
* @return HTMLPurifier_URI representation of URI. This representation has
* not been validated yet and may not conform to RFC.
*/
public function parse($uri) {
$uri = $this->percentEncoder->normalize($uri);
// Regexp is as per Appendix B.
// Note that ["<>] are an addition to the RFC's recommended
// characters, because they represent external delimeters.
$r_URI = '!'.
'(([^:/?#<>\'"]+):)?'. // 2. Scheme
'(//([^/?#<>\'"]*))?'. // 4. Authority
'([^?#<>\'"]*)'. // 5. Path
'(\?([^#<>\'"]*))?'. // 7. Query
'(#([^<>\'"]*))?'. // 8. Fragment
'(([^:/?#"<>]+):)?'. // 2. Scheme
'(//([^/?#"<>]*))?'. // 4. Authority
'([^?#"<>]*)'. // 5. Path
'(\?([^#"<>]*))?'. // 7. Query
'(#([^"<>]*))?'. // 8. Fragment
'!';
$matches = array();
@ -36,13 +51,7 @@ class HTMLPurifier_URIParser
// further parse authority
if ($authority !== null) {
// ridiculously inefficient: it's a stacked regex!
$HEXDIG = '[A-Fa-f0-9]';
$unreserved = 'A-Za-z0-9-._~'; // make sure you wrap with []
$sub_delims = '!$&\'()'; // needs []
$pct_encoded = "%$HEXDIG$HEXDIG";
$r_userinfo = "(?:[$unreserved$sub_delims:]|$pct_encoded)*";
$r_authority = "/^(($r_userinfo)@)?(\[[^\]]+\]|[^:]*)(:(\d*))?/";
$r_authority = "/^((.+?)@)?(\[[^\]]+\]|[^:]*)(:(\d*))?/";
$matches = array();
preg_match($r_authority, $authority, $matches);
$userinfo = !empty($matches[1]) ? $matches[2] : null;

21
tests/HTMLPurifier/AttrDef/URI/HostTest.php
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@ -14,6 +14,27 @@ class HTMLPurifier_AttrDef_URI_HostTest extends HTMLPurifier_AttrDefHarness
$this->assertDef('124.15.6.89'); // IPv4
$this->assertDef('www.google.com'); // reg-name
// more domain name tests
$this->assertDef('test.');
$this->assertDef('sub.test.');
$this->assertDef('.test', false);
$this->assertDef('ff');
$this->assertDef('1f', false);
$this->assertDef('-f', false);
$this->assertDef('f1');
$this->assertDef('f-', false);
$this->assertDef('sub.ff');
$this->assertDef('sub.1f', false);
$this->assertDef('sub.-f', false);
$this->assertDef('sub.f1');
$this->assertDef('sub.f-', false);
$this->assertDef('ff.top');
$this->assertDef('1f.top');
$this->assertDef('-f.top', false);
$this->assertDef('ff.top');
$this->assertDef('f1.top');
$this->assertDef('f-.top', false);
}
}

13
tests/HTMLPurifier/AttrDef/URITest.php
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@ -29,6 +29,19 @@ class HTMLPurifier_AttrDef_URITest extends HTMLPurifier_AttrDefHarness
);
}
function testPercentEncoding() {
$this->assertDef(
'http:colon:mercenary',
'colon%3Amercenary'
);
}
function testPercentEncodingPreserve() {
$this->assertDef(
'http://www.example.com/abcABC123-_.!~*()\''
);
}
function testEmbeds() {
$this->def = new HTMLPurifier_AttrDef_URI(true);
$this->assertDef('http://sub.example.com/alas?foo=asd');

23
tests/HTMLPurifier/PercentEncoderTest.php
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@ -35,5 +35,28 @@ class HTMLPurifier_PercentEncoderTest extends HTMLPurifier_Harness
}
function assertEncode($string, $expect = true, $preserve = false) {
if ($expect === true) $expect = $string;
$encoder = new HTMLPurifier_PercentEncoder($preserve);
$result = $encoder->encode($string);
$this->assertIdentical($result, $expect);
}
function test_encode_noChange() {
$this->assertEncode('abc012-_~.');
}
function test_encode_encode() {
$this->assertEncode('>', '%3E');
}
function test_encode_preserve() {
$this->assertEncode('<>', '<%3E', '<');
}
function test_encode_low() {
$this->assertEncode("\1", '%01');
}
}

9
tests/HTMLPurifier/URIParserTest.php
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@ -13,6 +13,13 @@ class HTMLPurifier_URIParserTest extends HTMLPurifier_Harness
$this->assertEqual($result, $expect);
}
function testPercentNormalization() {
$this->assertParsing(
'%G',
null, null, null, null, '%25G', null, null
);
}
function testRegular() {
$this->assertParsing(
'http://www.example.com/webhp?q=foo#result2',
@ -121,7 +128,7 @@ class HTMLPurifier_URIParserTest extends HTMLPurifier_Harness
function testMalformedTag() {
$this->assertParsing(
'http://www.example.com/\'>"',
'http://www.example.com/>',
'http', null, 'www.example.com', null, '/', null, null
);
}

28
tests/HTMLPurifier/URITest.php
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@ -160,4 +160,32 @@ class HTMLPurifier_URITest extends HTMLPurifier_URIHarness
$this->assertValidation('http://[2001:0db8:85z3:08d3:1319:8a2e:0370:7334]', 'http:');
}
function test_validate_removeRedundantScheme() {
$this->assertValidation('http:foo:/:', 'foo%3A/:');
}
function test_validate_username() {
$this->assertValidation("http://user\xE3\x91\x94:@foo.com", 'http://user%E3%91%94:@foo.com');
}
function test_validate_path_abempty() {
$this->assertValidation("http://host/\xE3\x91\x94:", 'http://host/%E3%91%94:');
}
function test_validate_path_absolute() {
$this->assertValidation("/\xE3\x91\x94:", '/%E3%91%94:');
}
function test_validate_path_rootless() {
$this->assertValidation("mailto:\xE3\x91\x94:", 'mailto:%E3%91%94:');
}
function test_validate_path_noscheme() {
$this->assertValidation("\xE3\x91\x94", '%E3%91%94');
}
function test_validate_path_empty() {
$this->assertValidation('http://google.com');
}
}