some important stuff we'll need

6 files changed, 1128 insertions, 0 deletions

diff --git a/lib/htmlpurifier/library/HTMLPurifier/Strategy/Composite.php b/lib/htmlpurifier/library/HTMLPurifier/Strategy/Composite.php
new file mode 100644
index 000000000..92aefd33e
--- /dev/null
+++ b/lib/htmlpurifier/library/HTMLPurifier/Strategy/Composite.php
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * Composite strategy that runs multiple strategies on tokens.
+ */
+abstract class HTMLPurifier_Strategy_Composite extends HTMLPurifier_Strategy
+{
+
+    /**
+     * List of strategies to run tokens through.
+     */
+    protected $strategies = array();
+
+    public function execute($tokens, $config, $context) {
+        foreach ($this->strategies as $strategy) {
+            $tokens = $strategy->execute($tokens, $config, $context);
+        }
+        return $tokens;
+    }
+
+}
+
+// vim: et sw=4 sts=4
diff --git a/lib/htmlpurifier/library/HTMLPurifier/Strategy/Core.php b/lib/htmlpurifier/library/HTMLPurifier/Strategy/Core.php
new file mode 100644
index 000000000..d90e15860
--- /dev/null
+++ b/lib/htmlpurifier/library/HTMLPurifier/Strategy/Core.php
@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * Core strategy composed of the big four strategies.
+ */
+class HTMLPurifier_Strategy_Core extends HTMLPurifier_Strategy_Composite
+{
+
+    public function __construct() {
+        $this->strategies[] = new HTMLPurifier_Strategy_RemoveForeignElements();
+        $this->strategies[] = new HTMLPurifier_Strategy_MakeWellFormed();
+        $this->strategies[] = new HTMLPurifier_Strategy_FixNesting();
+        $this->strategies[] = new HTMLPurifier_Strategy_ValidateAttributes();
+    }
+
+}
+
+// vim: et sw=4 sts=4
diff --git a/lib/htmlpurifier/library/HTMLPurifier/Strategy/FixNesting.php b/lib/htmlpurifier/library/HTMLPurifier/Strategy/FixNesting.php
new file mode 100644
index 000000000..f81802391
--- /dev/null
+++ b/lib/htmlpurifier/library/HTMLPurifier/Strategy/FixNesting.php
@@ -0,0 +1,328 @@
+<?php
+
+/**
+ * Takes a well formed list of tokens and fixes their nesting.
+ *
+ * HTML elements dictate which elements are allowed to be their children,
+ * for example, you can't have a p tag in a span tag.  Other elements have
+ * much more rigorous definitions: tables, for instance, require a specific
+ * order for their elements.  There are also constraints not expressible by
+ * document type definitions, such as the chameleon nature of ins/del
+ * tags and global child exclusions.
+ *
+ * The first major objective of this strategy is to iterate through all the
+ * nodes (not tokens) of the list of tokens and determine whether or not
+ * their children conform to the element's definition.  If they do not, the
+ * child definition may optionally supply an amended list of elements that
+ * is valid or require that the entire node be deleted (and the previous
+ * node rescanned).
+ *
+ * The second objective is to ensure that explicitly excluded elements of
+ * an element do not appear in its children.  Code that accomplishes this
+ * task is pervasive through the strategy, though the two are distinct tasks
+ * and could, theoretically, be seperated (although it's not recommended).
+ *
+ * @note Whether or not unrecognized children are silently dropped or
+ *       translated into text depends on the child definitions.
+ *
+ * @todo Enable nodes to be bubbled out of the structure.
+ */
+
+class HTMLPurifier_Strategy_FixNesting extends HTMLPurifier_Strategy
+{
+
+    public function execute($tokens, $config, $context) {
+        //####################################################################//
+        // Pre-processing
+
+        // get a copy of the HTML definition
+        $definition = $config->getHTMLDefinition();
+
+        // insert implicit "parent" node, will be removed at end.
+        // DEFINITION CALL
+        $parent_name = $definition->info_parent;
+        array_unshift($tokens, new HTMLPurifier_Token_Start($parent_name));
+        $tokens[] = new HTMLPurifier_Token_End($parent_name);
+
+        // setup the context variable 'IsInline', for chameleon processing
+        // is 'false' when we are not inline, 'true' when it must always
+        // be inline, and an integer when it is inline for a certain
+        // branch of the document tree
+        $is_inline = $definition->info_parent_def->descendants_are_inline;
+        $context->register('IsInline', $is_inline);
+
+        // setup error collector
+        $e =& $context->get('ErrorCollector', true);
+
+        //####################################################################//
+        // Loop initialization
+
+        // stack that contains the indexes of all parents,
+        // $stack[count($stack)-1] being the current parent
+        $stack = array();
+
+        // stack that contains all elements that are excluded
+        // it is organized by parent elements, similar to $stack,
+        // but it is only populated when an element with exclusions is
+        // processed, i.e. there won't be empty exclusions.
+        $exclude_stack = array();
+
+        // variable that contains the start token while we are processing
+        // nodes. This enables error reporting to do its job
+        $start_token = false;
+        $context->register('CurrentToken', $start_token);
+
+        //####################################################################//
+        // Loop
+
+        // iterate through all start nodes. Determining the start node
+        // is complicated so it has been omitted from the loop construct
+        for ($i = 0, $size = count($tokens) ; $i < $size; ) {
+
+            //################################################################//
+            // Gather information on children
+
+            // child token accumulator
+            $child_tokens = array();
+
+            // scroll to the end of this node, report number, and collect
+            // all children
+            for ($j = $i, $depth = 0; ; $j++) {
+                if ($tokens[$j] instanceof HTMLPurifier_Token_Start) {
+                    $depth++;
+                    // skip token assignment on first iteration, this is the
+                    // token we currently are on
+                    if ($depth == 1) continue;
+                } elseif ($tokens[$j] instanceof HTMLPurifier_Token_End) {
+                    $depth--;
+                    // skip token assignment on last iteration, this is the
+                    // end token of the token we're currently on
+                    if ($depth == 0) break;
+                }
+                $child_tokens[] = $tokens[$j];
+            }
+
+            // $i is index of start token
+            // $j is index of end token
+
+            $start_token = $tokens[$i]; // to make token available via CurrentToken
+
+            //################################################################//
+            // Gather information on parent
+
+            // calculate parent information
+            if ($count = count($stack)) {
+                $parent_index = $stack[$count-1];
+                $parent_name  = $tokens[$parent_index]->name;
+                if ($parent_index == 0) {
+                    $parent_def   = $definition->info_parent_def;
+                } else {
+                    $parent_def   = $definition->info[$parent_name];
+                }
+            } else {
+                // processing as if the parent were the "root" node
+                // unknown info, it won't be used anyway, in the future,
+                // we may want to enforce one element only (this is
+                // necessary for HTML Purifier to clean entire documents
+                $parent_index = $parent_name = $parent_def = null;
+            }
+
+            // calculate context
+            if ($is_inline === false) {
+                // check if conditions make it inline
+                if (!empty($parent_def) && $parent_def->descendants_are_inline) {
+                    $is_inline = $count - 1;
+                }
+            } else {
+                // check if we're out of inline
+                if ($count === $is_inline) {
+                    $is_inline = false;
+                }
+            }
+
+            //################################################################//
+            // Determine whether element is explicitly excluded SGML-style
+
+            // determine whether or not element is excluded by checking all
+            // parent exclusions. The array should not be very large, two
+            // elements at most.
+            $excluded = false;
+            if (!empty($exclude_stack)) {
+                foreach ($exclude_stack as $lookup) {
+                    if (isset($lookup[$tokens[$i]->name])) {
+                        $excluded = true;
+                        // no need to continue processing
+                        break;
+                    }
+                }
+            }
+
+            //################################################################//
+            // Perform child validation
+
+            if ($excluded) {
+                // there is an exclusion, remove the entire node
+                $result = false;
+                $excludes = array(); // not used, but good to initialize anyway
+            } else {
+                // DEFINITION CALL
+                if ($i === 0) {
+                    // special processing for the first node
+                    $def = $definition->info_parent_def;
+                } else {
+                    $def = $definition->info[$tokens[$i]->name];
+
+                }
+
+                if (!empty($def->child)) {
+                    // have DTD child def validate children
+                    $result = $def->child->validateChildren(
+                        $child_tokens, $config, $context);
+                } else {
+                    // weird, no child definition, get rid of everything
+                    $result = false;
+                }
+
+                // determine whether or not this element has any exclusions
+                $excludes = $def->excludes;
+            }
+
+            // $result is now a bool or array
+
+            //################################################################//
+            // Process result by interpreting $result
+
+            if ($result === true || $child_tokens === $result) {
+                // leave the node as is
+
+                // register start token as a parental node start
+                $stack[] = $i;
+
+                // register exclusions if there are any
+                if (!empty($excludes)) $exclude_stack[] = $excludes;
+
+                // move cursor to next possible start node
+                $i++;
+
+            } elseif($result === false) {
+                // remove entire node
+
+                if ($e) {
+                    if ($excluded) {
+                        $e->send(E_ERROR, 'Strategy_FixNesting: Node excluded');
+                    } else {
+                        $e->send(E_ERROR, 'Strategy_FixNesting: Node removed');
+                    }
+                }
+
+                // calculate length of inner tokens and current tokens
+                $length = $j - $i + 1;
+
+                // perform removal
+                array_splice($tokens, $i, $length);
+
+                // update size
+                $size -= $length;
+
+                // there is no start token to register,
+                // current node is now the next possible start node
+                // unless it turns out that we need to do a double-check
+
+                // this is a rought heuristic that covers 100% of HTML's
+                // cases and 99% of all other cases. A child definition
+                // that would be tricked by this would be something like:
+                // ( | a b c) where it's all or nothing. Fortunately,
+                // our current implementation claims that that case would
+                // not allow empty, even if it did
+                if (!$parent_def->child->allow_empty) {
+                    // we need to do a double-check
+                    $i = $parent_index;
+                    array_pop($stack);
+                }
+
+                // PROJECTED OPTIMIZATION: Process all children elements before
+                // reprocessing parent node.
+
+            } else {
+                // replace node with $result
+
+                // calculate length of inner tokens
+                $length = $j - $i - 1;
+
+                if ($e) {
+                    if (empty($result) && $length) {
+                        $e->send(E_ERROR, 'Strategy_FixNesting: Node contents removed');
+                    } else {
+                        $e->send(E_WARNING, 'Strategy_FixNesting: Node reorganized');
+                    }
+                }
+
+                // perform replacement
+                array_splice($tokens, $i + 1, $length, $result);
+
+                // update size
+                $size -= $length;
+                $size += count($result);
+
+                // register start token as a parental node start
+                $stack[] = $i;
+
+                // register exclusions if there are any
+                if (!empty($excludes)) $exclude_stack[] = $excludes;
+
+                // move cursor to next possible start node
+                $i++;
+
+            }
+
+            //################################################################//
+            // Scroll to next start node
+
+            // We assume, at this point, that $i is the index of the token
+            // that is the first possible new start point for a node.
+
+            // Test if the token indeed is a start tag, if not, move forward
+            // and test again.
+            $size = count($tokens);
+            while ($i < $size and !$tokens[$i] instanceof HTMLPurifier_Token_Start) {
+                if ($tokens[$i] instanceof HTMLPurifier_Token_End) {
+                    // pop a token index off the stack if we ended a node
+                    array_pop($stack);
+                    // pop an exclusion lookup off exclusion stack if
+                    // we ended node and that node had exclusions
+                    if ($i == 0 || $i == $size - 1) {
+                        // use specialized var if it's the super-parent
+                        $s_excludes = $definition->info_parent_def->excludes;
+                    } else {
+                        $s_excludes = $definition->info[$tokens[$i]->name]->excludes;
+                    }
+                    if ($s_excludes) {
+                        array_pop($exclude_stack);
+                    }
+                }
+                $i++;
+            }
+
+        }
+
+        //####################################################################//
+        // Post-processing
+
+        // remove implicit parent tokens at the beginning and end
+        array_shift($tokens);
+        array_pop($tokens);
+
+        // remove context variables
+        $context->destroy('IsInline');
+        $context->destroy('CurrentToken');
+
+        //####################################################################//
+        // Return
+
+        return $tokens;
+
+    }
+
+}
+
+// vim: et sw=4 sts=4
diff --git a/lib/htmlpurifier/library/HTMLPurifier/Strategy/MakeWellFormed.php b/lib/htmlpurifier/library/HTMLPurifier/Strategy/MakeWellFormed.php
new file mode 100644
index 000000000..c7aa1bb86
--- /dev/null
+++ b/lib/htmlpurifier/library/HTMLPurifier/Strategy/MakeWellFormed.php
@@ -0,0 +1,532 @@
+<?php
+
+/**
+ * Takes tokens makes them well-formed (balance end tags, etc.)
+ *
+ * Specification of the armor attributes this strategy uses:
+ *
+ *      - MakeWellFormed_TagClosedError: This armor field is used to
+ *        suppress tag closed errors for certain tokens [TagClosedSuppress],
+ *        in particular, if a tag was generated automatically by HTML
+ *        Purifier, we may rely on our infrastructure to close it for us
+ *        and shouldn't report an error to the user [TagClosedAuto].
+ */
+class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
+{
+
+    /**
+     * Array stream of tokens being processed.
+     */
+    protected $tokens;
+
+    /**
+     * Current index in $tokens.
+     */
+    protected $t;
+
+    /**
+     * Current nesting of elements.
+     */
+    protected $stack;
+
+    /**
+     * Injectors active in this stream processing.
+     */
+    protected $injectors;
+
+    /**
+     * Current instance of HTMLPurifier_Config.
+     */
+    protected $config;
+
+    /**
+     * Current instance of HTMLPurifier_Context.
+     */
+    protected $context;
+
+    public function execute($tokens, $config, $context) {
+
+        $definition = $config->getHTMLDefinition();
+
+        // local variables
+        $generator = new HTMLPurifier_Generator($config, $context);
+        $escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
+        // used for autoclose early abortion
+        $global_parent_allowed_elements = array();
+        if (isset($definition->info[$definition->info_parent])) {
+            // may be unset under testing circumstances
+            $global_parent_allowed_elements = $definition->info[$definition->info_parent]->child->getAllowedElements($config);
+        }
+        $e = $context->get('ErrorCollector', true);
+        $t = false; // token index
+        $i = false; // injector index
+        $token      = false; // the current token
+        $reprocess  = false; // whether or not to reprocess the same token
+        $stack = array();
+
+        // member variables
+        $this->stack   =& $stack;
+        $this->t       =& $t;
+        $this->tokens  =& $tokens;
+        $this->config  = $config;
+        $this->context = $context;
+
+        // context variables
+        $context->register('CurrentNesting', $stack);
+        $context->register('InputIndex',     $t);
+        $context->register('InputTokens',    $tokens);
+        $context->register('CurrentToken',   $token);
+
+        // -- begin INJECTOR --
+
+        $this->injectors = array();
+
+        $injectors = $config->getBatch('AutoFormat');
+        $def_injectors = $definition->info_injector;
+        $custom_injectors = $injectors['Custom'];
+        unset($injectors['Custom']); // special case
+        foreach ($injectors as $injector => $b) {
+            // XXX: Fix with a legitimate lookup table of enabled filters
+            if (strpos($injector, '.') !== false) continue;
+            $injector = "HTMLPurifier_Injector_$injector";
+            if (!$b) continue;
+            $this->injectors[] = new $injector;
+        }
+        foreach ($def_injectors as $injector) {
+            // assumed to be objects
+            $this->injectors[] = $injector;
+        }
+        foreach ($custom_injectors as $injector) {
+            if (!$injector) continue;
+            if (is_string($injector)) {
+                $injector = "HTMLPurifier_Injector_$injector";
+                $injector = new $injector;
+            }
+            $this->injectors[] = $injector;
+        }
+
+        // give the injectors references to the definition and context
+        // variables for performance reasons
+        foreach ($this->injectors as $ix => $injector) {
+            $error = $injector->prepare($config, $context);
+            if (!$error) continue;
+            array_splice($this->injectors, $ix, 1); // rm the injector
+            trigger_error("Cannot enable {$injector->name} injector because $error is not allowed", E_USER_WARNING);
+        }
+
+        // -- end INJECTOR --
+
+        // a note on reprocessing:
+        //      In order to reduce code duplication, whenever some code needs
+        //      to make HTML changes in order to make things "correct", the
+        //      new HTML gets sent through the purifier, regardless of its
+        //      status. This means that if we add a start token, because it
+        //      was totally necessary, we don't have to update nesting; we just
+        //      punt ($reprocess = true; continue;) and it does that for us.
+
+        // isset is in loop because $tokens size changes during loop exec
+        for (
+            $t = 0;
+            $t == 0 || isset($tokens[$t - 1]);
+            // only increment if we don't need to reprocess
+            $reprocess ? $reprocess = false : $t++
+        ) {
+
+            // check for a rewind
+            if (is_int($i) && $i >= 0) {
+                // possibility: disable rewinding if the current token has a
+                // rewind set on it already. This would offer protection from
+                // infinite loop, but might hinder some advanced rewinding.
+                $rewind_to = $this->injectors[$i]->getRewind();
+                if (is_int($rewind_to) && $rewind_to < $t) {
+                    if ($rewind_to < 0) $rewind_to = 0;
+                    while ($t > $rewind_to) {
+                        $t--;
+                        $prev = $tokens[$t];
+                        // indicate that other injectors should not process this token,
+                        // but we need to reprocess it
+                        unset($prev->skip[$i]);
+                        $prev->rewind = $i;
+                        if ($prev instanceof HTMLPurifier_Token_Start) array_pop($this->stack);
+                        elseif ($prev instanceof HTMLPurifier_Token_End) $this->stack[] = $prev->start;
+                    }
+                }
+                $i = false;
+            }
+
+            // handle case of document end
+            if (!isset($tokens[$t])) {
+                // kill processing if stack is empty
+                if (empty($this->stack)) break;
+
+                // peek
+                $top_nesting = array_pop($this->stack);
+                $this->stack[] = $top_nesting;
+
+                // send error [TagClosedSuppress]
+                if ($e && !isset($top_nesting->armor['MakeWellFormed_TagClosedError'])) {
+                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by document end', $top_nesting);
+                }
+
+                // append, don't splice, since this is the end
+                $tokens[] = new HTMLPurifier_Token_End($top_nesting->name);
+
+                // punt!
+                $reprocess = true;
+                continue;
+            }
+
+            $token = $tokens[$t];
+
+            //echo '<br>'; printTokens($tokens, $t); printTokens($this->stack);
+            //flush();
+
+            // quick-check: if it's not a tag, no need to process
+            if (empty($token->is_tag)) {
+                if ($token instanceof HTMLPurifier_Token_Text) {
+                    foreach ($this->injectors as $i => $injector) {
+                        if (isset($token->skip[$i])) continue;
+                        if ($token->rewind !== null && $token->rewind !== $i) continue;
+                        $injector->handleText($token);
+                        $this->processToken($token, $i);
+                        $reprocess = true;
+                        break;
+                    }
+                }
+                // another possibility is a comment
+                continue;
+            }
+
+            if (isset($definition->info[$token->name])) {
+                $type = $definition->info[$token->name]->child->type;
+            } else {
+                $type = false; // Type is unknown, treat accordingly
+            }
+
+            // quick tag checks: anything that's *not* an end tag
+            $ok = false;
+            if ($type === 'empty' && $token instanceof HTMLPurifier_Token_Start) {
+                // claims to be a start tag but is empty
+                $token = new HTMLPurifier_Token_Empty($token->name, $token->attr, $token->line, $token->col, $token->armor);
+                $ok = true;
+            } elseif ($type && $type !== 'empty' && $token instanceof HTMLPurifier_Token_Empty) {
+                // claims to be empty but really is a start tag
+                $this->swap(new HTMLPurifier_Token_End($token->name));
+                $this->insertBefore(new HTMLPurifier_Token_Start($token->name, $token->attr, $token->line, $token->col, $token->armor));
+                // punt (since we had to modify the input stream in a non-trivial way)
+                $reprocess = true;
+                continue;
+            } elseif ($token instanceof HTMLPurifier_Token_Empty) {
+                // real empty token
+                $ok = true;
+            } elseif ($token instanceof HTMLPurifier_Token_Start) {
+                // start tag
+
+                // ...unless they also have to close their parent
+                if (!empty($this->stack)) {
+
+                    // Performance note: you might think that it's rather
+                    // inefficient, recalculating the autoclose information
+                    // for every tag that a token closes (since when we
+                    // do an autoclose, we push a new token into the
+                    // stream and then /process/ that, before
+                    // re-processing this token.)  But this is
+                    // necessary, because an injector can make an
+                    // arbitrary transformations to the autoclosing
+                    // tokens we introduce, so things may have changed
+                    // in the meantime.  Also, doing the inefficient thing is
+                    // "easy" to reason about (for certain perverse definitions
+                    // of "easy")
+
+                    $parent = array_pop($this->stack);
+                    $this->stack[] = $parent;
+
+                    if (isset($definition->info[$parent->name])) {
+                        $elements = $definition->info[$parent->name]->child->getAllowedElements($config);
+                        $autoclose = !isset($elements[$token->name]);
+                    } else {
+                        $autoclose = false;
+                    }
+
+                    if ($autoclose && $definition->info[$token->name]->wrap) {
+                        // Check if an element can be wrapped by another 
+                        // element to make it valid in a context (for 
+                        // example, <ul><ul> needs a <li> in between)
+                        $wrapname = $definition->info[$token->name]->wrap;
+                        $wrapdef = $definition->info[$wrapname];
+                        $elements = $wrapdef->child->getAllowedElements($config);
+                        $parent_elements = $definition->info[$parent->name]->child->getAllowedElements($config);
+                        if (isset($elements[$token->name]) && isset($parent_elements[$wrapname])) {
+                            $newtoken = new HTMLPurifier_Token_Start($wrapname);
+                            $this->insertBefore($newtoken);
+                            $reprocess = true;
+                            continue;
+                        }
+                    }
+
+                    $carryover = false;
+                    if ($autoclose && $definition->info[$parent->name]->formatting) {
+                        $carryover = true;
+                    }
+
+                    if ($autoclose) {
+                        // check if this autoclose is doomed to fail
+                        // (this rechecks $parent, which his harmless)
+                        $autoclose_ok = isset($global_parent_allowed_elements[$token->name]);
+                        if (!$autoclose_ok) {
+                            foreach ($this->stack as $ancestor) {
+                                $elements = $definition->info[$ancestor->name]->child->getAllowedElements($config);
+                                if (isset($elements[$token->name])) {
+                                    $autoclose_ok = true;
+                                    break;
+                                }
+                                if ($definition->info[$token->name]->wrap) {
+                                    $wrapname = $definition->info[$token->name]->wrap;
+                                    $wrapdef = $definition->info[$wrapname];
+                                    $wrap_elements = $wrapdef->child->getAllowedElements($config);
+                                    if (isset($wrap_elements[$token->name]) && isset($elements[$wrapname])) {
+                                        $autoclose_ok = true;
+                                        break;
+                                    }
+                                }
+                            }
+                        }
+                        if ($autoclose_ok) {
+                            // errors need to be updated
+                            $new_token = new HTMLPurifier_Token_End($parent->name);
+                            $new_token->start = $parent;
+                            if ($carryover) {
+                                $element = clone $parent;
+                                // [TagClosedAuto]
+                                $element->armor['MakeWellFormed_TagClosedError'] = true;
+                                $element->carryover = true;
+                                $this->processToken(array($new_token, $token, $element));
+                            } else {
+                                $this->insertBefore($new_token);
+                            }
+                            // [TagClosedSuppress]
+                            if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
+                                if (!$carryover) {
+                                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
+                                } else {
+                                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
+                                }
+                            }
+                        } else {
+                            $this->remove();
+                        }
+                        $reprocess = true;
+                        continue;
+                    }
+
+                }
+                $ok = true;
+            }
+
+            if ($ok) {
+                foreach ($this->injectors as $i => $injector) {
+                    if (isset($token->skip[$i])) continue;
+                    if ($token->rewind !== null && $token->rewind !== $i) continue;
+                    $injector->handleElement($token);
+                    $this->processToken($token, $i);
+                    $reprocess = true;
+                    break;
+                }
+                if (!$reprocess) {
+                    // ah, nothing interesting happened; do normal processing
+                    $this->swap($token);
+                    if ($token instanceof HTMLPurifier_Token_Start) {
+                        $this->stack[] = $token;
+                    } elseif ($token instanceof HTMLPurifier_Token_End) {
+                        throw new HTMLPurifier_Exception('Improper handling of end tag in start code; possible error in MakeWellFormed');
+                    }
+                }
+                continue;
+            }
+
+            // sanity check: we should be dealing with a closing tag
+            if (!$token instanceof HTMLPurifier_Token_End) {
+                throw new HTMLPurifier_Exception('Unaccounted for tag token in input stream, bug in HTML Purifier');
+            }
+
+            // make sure that we have something open
+            if (empty($this->stack)) {
+                if ($escape_invalid_tags) {
+                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
+                    $this->swap(new HTMLPurifier_Token_Text(
+                        $generator->generateFromToken($token)
+                    ));
+                } else {
+                    $this->remove();
+                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
+                }
+                $reprocess = true;
+                continue;
+            }
+
+            // first, check for the simplest case: everything closes neatly.
+            // Eventually, everything passes through here; if there are problems
+            // we modify the input stream accordingly and then punt, so that
+            // the tokens get processed again.
+            $current_parent = array_pop($this->stack);
+            if ($current_parent->name == $token->name) {
+                $token->start = $current_parent;
+                foreach ($this->injectors as $i => $injector) {
+                    if (isset($token->skip[$i])) continue;
+                    if ($token->rewind !== null && $token->rewind !== $i) continue;
+                    $injector->handleEnd($token);
+                    $this->processToken($token, $i);
+                    $this->stack[] = $current_parent;
+                    $reprocess = true;
+                    break;
+                }
+                continue;
+            }
+
+            // okay, so we're trying to close the wrong tag
+
+            // undo the pop previous pop
+            $this->stack[] = $current_parent;
+
+            // scroll back the entire nest, trying to find our tag.
+            // (feature could be to specify how far you'd like to go)
+            $size = count($this->stack);
+            // -2 because -1 is the last element, but we already checked that
+            $skipped_tags = false;
+            for ($j = $size - 2; $j >= 0; $j--) {
+                if ($this->stack[$j]->name == $token->name) {
+                    $skipped_tags = array_slice($this->stack, $j);
+                    break;
+                }
+            }
+
+            // we didn't find the tag, so remove
+            if ($skipped_tags === false) {
+                if ($escape_invalid_tags) {
+                    $this->swap(new HTMLPurifier_Token_Text(
+                        $generator->generateFromToken($token)
+                    ));
+                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
+                } else {
+                    $this->remove();
+                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
+                }
+                $reprocess = true;
+                continue;
+            }
+
+            // do errors, in REVERSE $j order: a,b,c with </a></b></c>
+            $c = count($skipped_tags);
+            if ($e) {
+                for ($j = $c - 1; $j > 0; $j--) {
+                    // notice we exclude $j == 0, i.e. the current ending tag, from
+                    // the errors... [TagClosedSuppress]
+                    if (!isset($skipped_tags[$j]->armor['MakeWellFormed_TagClosedError'])) {
+                        $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by element end', $skipped_tags[$j]);
+                    }
+                }
+            }
+
+            // insert tags, in FORWARD $j order: c,b,a with </a></b></c>
+            $replace = array($token);
+            for ($j = 1; $j < $c; $j++) {
+                // ...as well as from the insertions
+                $new_token = new HTMLPurifier_Token_End($skipped_tags[$j]->name);
+                $new_token->start = $skipped_tags[$j];
+                array_unshift($replace, $new_token);
+                if (isset($definition->info[$new_token->name]) && $definition->info[$new_token->name]->formatting) {
+                    // [TagClosedAuto]
+                    $element = clone $skipped_tags[$j];
+                    $element->carryover = true;
+                    $element->armor['MakeWellFormed_TagClosedError'] = true;
+                    $replace[] = $element;
+                }
+            }
+            $this->processToken($replace);
+            $reprocess = true;
+            continue;
+        }
+
+        $context->destroy('CurrentNesting');
+        $context->destroy('InputTokens');
+        $context->destroy('InputIndex');
+        $context->destroy('CurrentToken');
+
+        unset($this->injectors, $this->stack, $this->tokens, $this->t);
+        return $tokens;
+    }
+
+    /**
+     * Processes arbitrary token values for complicated substitution patterns.
+     * In general:
+     *
+     * If $token is an array, it is a list of tokens to substitute for the
+     * current token. These tokens then get individually processed. If there
+     * is a leading integer in the list, that integer determines how many
+     * tokens from the stream should be removed.
+     *
+     * If $token is a regular token, it is swapped with the current token.
+     *
+     * If $token is false, the current token is deleted.
+     *
+     * If $token is an integer, that number of tokens (with the first token
+     * being the current one) will be deleted.
+     *
+     * @param $token Token substitution value
+     * @param $injector Injector that performed the substitution; default is if
+     *        this is not an injector related operation.
+     */
+    protected function processToken($token, $injector = -1) {
+
+        // normalize forms of token
+        if (is_object($token)) $token = array(1, $token);
+        if (is_int($token))    $token = array($token);
+        if ($token === false)  $token = array(1);
+        if (!is_array($token)) throw new HTMLPurifier_Exception('Invalid token type from injector');
+        if (!is_int($token[0])) array_unshift($token, 1);
+        if ($token[0] === 0) throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
+
+        // $token is now an array with the following form:
+        // array(number nodes to delete, new node 1, new node 2, ...)
+
+        $delete = array_shift($token);
+        $old = array_splice($this->tokens, $this->t, $delete, $token);
+
+        if ($injector > -1) {
+            // determine appropriate skips
+            $oldskip = isset($old[0]) ? $old[0]->skip : array();
+            foreach ($token as $object) {
+                $object->skip = $oldskip;
+                $object->skip[$injector] = true;
+            }
+        }
+
+    }
+
+    /**
+     * Inserts a token before the current token. Cursor now points to
+     * this token.  You must reprocess after this.
+     */
+    private function insertBefore($token) {
+        array_splice($this->tokens, $this->t, 0, array($token));
+    }
+
+    /**
+     * Removes current token. Cursor now points to new token occupying previously
+     * occupied space.  You must reprocess after this.
+     */
+    private function remove() {
+        array_splice($this->tokens, $this->t, 1);
+    }
+
+    /**
+     * Swap current token with new token. Cursor points to new token (no
+     * change).  You must reprocess after this.
+     */
+    private function swap($token) {
+        $this->tokens[$this->t] = $token;
+    }
+
+}
+
+// vim: et sw=4 sts=4
diff --git a/lib/htmlpurifier/library/HTMLPurifier/Strategy/RemoveForeignElements.php b/lib/htmlpurifier/library/HTMLPurifier/Strategy/RemoveForeignElements.php
new file mode 100644
index 000000000..bccaf14d3
--- /dev/null
+++ b/lib/htmlpurifier/library/HTMLPurifier/Strategy/RemoveForeignElements.php
@@ -0,0 +1,188 @@
+<?php
+
+/**
+ * Removes all unrecognized tags from the list of tokens.
+ *
+ * This strategy iterates through all the tokens and removes unrecognized
+ * tokens. If a token is not recognized but a TagTransform is defined for
+ * that element, the element will be transformed accordingly.
+ */
+
+class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
+{
+
+    public function execute($tokens, $config, $context) {
+        $definition = $config->getHTMLDefinition();
+        $generator = new HTMLPurifier_Generator($config, $context);
+        $result = array();
+
+        $escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
+        $remove_invalid_img  = $config->get('Core.RemoveInvalidImg');
+
+        // currently only used to determine if comments should be kept
+        $trusted = $config->get('HTML.Trusted');
+        $comment_lookup = $config->get('HTML.AllowedComments');
+        $comment_regexp = $config->get('HTML.AllowedCommentsRegexp');
+        $check_comments = $comment_lookup !== array() || $comment_regexp !== null;
+
+        $remove_script_contents = $config->get('Core.RemoveScriptContents');
+        $hidden_elements     = $config->get('Core.HiddenElements');
+
+        // remove script contents compatibility
+        if ($remove_script_contents === true) {
+            $hidden_elements['script'] = true;
+        } elseif ($remove_script_contents === false && isset($hidden_elements['script'])) {
+            unset($hidden_elements['script']);
+        }
+
+        $attr_validator = new HTMLPurifier_AttrValidator();
+
+        // removes tokens until it reaches a closing tag with its value
+        $remove_until = false;
+
+        // converts comments into text tokens when this is equal to a tag name
+        $textify_comments = false;
+
+        $token = false;
+        $context->register('CurrentToken', $token);
+
+        $e = false;
+        if ($config->get('Core.CollectErrors')) {
+            $e =& $context->get('ErrorCollector');
+        }
+
+        foreach($tokens as $token) {
+            if ($remove_until) {
+                if (empty($token->is_tag) || $token->name !== $remove_until) {
+                    continue;
+                }
+            }
+            if (!empty( $token->is_tag )) {
+                // DEFINITION CALL
+
+                // before any processing, try to transform the element
+                if (
+                    isset($definition->info_tag_transform[$token->name])
+                ) {
+                    $original_name = $token->name;
+                    // there is a transformation for this tag
+                    // DEFINITION CALL
+                    $token = $definition->
+                                info_tag_transform[$token->name]->
+                                    transform($token, $config, $context);
+                    if ($e) $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Tag transform', $original_name);
+                }
+
+                if (isset($definition->info[$token->name])) {
+
+                    // mostly everything's good, but
+                    // we need to make sure required attributes are in order
+                    if (
+                        ($token instanceof HTMLPurifier_Token_Start || $token instanceof HTMLPurifier_Token_Empty) &&
+                        $definition->info[$token->name]->required_attr &&
+                        ($token->name != 'img' || $remove_invalid_img) // ensure config option still works
+                    ) {
+                        $attr_validator->validateToken($token, $config, $context);
+                        $ok = true;
+                        foreach ($definition->info[$token->name]->required_attr as $name) {
+                            if (!isset($token->attr[$name])) {
+                                $ok = false;
+                                break;
+                            }
+                        }
+                        if (!$ok) {
+                            if ($e) $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Missing required attribute', $name);
+                            continue;
+                        }
+                        $token->armor['ValidateAttributes'] = true;
+                    }
+
+                    if (isset($hidden_elements[$token->name]) && $token instanceof HTMLPurifier_Token_Start) {
+                        $textify_comments = $token->name;
+                    } elseif ($token->name === $textify_comments && $token instanceof HTMLPurifier_Token_End) {
+                        $textify_comments = false;
+                    }
+
+                } elseif ($escape_invalid_tags) {
+                    // invalid tag, generate HTML representation and insert in
+                    if ($e) $e->send(E_WARNING, 'Strategy_RemoveForeignElements: Foreign element to text');
+                    $token = new HTMLPurifier_Token_Text(
+                        $generator->generateFromToken($token)
+                    );
+                } else {
+                    // check if we need to destroy all of the tag's children
+                    // CAN BE GENERICIZED
+                    if (isset($hidden_elements[$token->name])) {
+                        if ($token instanceof HTMLPurifier_Token_Start) {
+                            $remove_until = $token->name;
+                        } elseif ($token instanceof HTMLPurifier_Token_Empty) {
+                            // do nothing: we're still looking
+                        } else {
+                            $remove_until = false;
+                        }
+                        if ($e) $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Foreign meta element removed');
+                    } else {
+                        if ($e) $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Foreign element removed');
+                    }
+                    continue;
+                }
+            } elseif ($token instanceof HTMLPurifier_Token_Comment) {
+                // textify comments in script tags when they are allowed
+                if ($textify_comments !== false) {
+                    $data = $token->data;
+                    $token = new HTMLPurifier_Token_Text($data);
+                } elseif ($trusted || $check_comments) {
+                    // always cleanup comments
+                    $trailing_hyphen = false;
+                    if ($e) {
+                        // perform check whether or not there's a trailing hyphen
+                        if (substr($token->data, -1) == '-') {
+                            $trailing_hyphen = true;
+                        }
+                    }
+                    $token->data = rtrim($token->data, '-');
+                    $found_double_hyphen = false;
+                    while (strpos($token->data, '--') !== false) {
+                        $found_double_hyphen = true;
+                        $token->data = str_replace('--', '-', $token->data);
+                    }
+                    if ($trusted || !empty($comment_lookup[trim($token->data)]) || ($comment_regexp !== NULL && preg_match($comment_regexp, trim($token->data)))) {
+                        // OK good
+                        if ($e) {
+                            if ($trailing_hyphen) {
+                                $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Trailing hyphen in comment removed');
+                            }
+                            if ($found_double_hyphen) {
+                                $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Hyphens in comment collapsed');
+                            }
+                        }
+                    } else {
+                        if ($e) {
+                            $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Comment removed');
+                        }
+                        continue;
+                    }
+                } else {
+                    // strip comments
+                    if ($e) $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Comment removed');
+                    continue;
+                }
+            } elseif ($token instanceof HTMLPurifier_Token_Text) {
+            } else {
+                continue;
+            }
+            $result[] = $token;
+        }
+        if ($remove_until && $e) {
+            // we removed tokens until the end, throw error
+            $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Token removed to end', $remove_until);
+        }
+
+        $context->destroy('CurrentToken');
+
+        return $result;
+    }
+
+}
+
+// vim: et sw=4 sts=4
diff --git a/lib/htmlpurifier/library/HTMLPurifier/Strategy/ValidateAttributes.php b/lib/htmlpurifier/library/HTMLPurifier/Strategy/ValidateAttributes.php
new file mode 100644
index 000000000..c3328a9d4
--- /dev/null
+++ b/lib/htmlpurifier/library/HTMLPurifier/Strategy/ValidateAttributes.php
@@ -0,0 +1,39 @@
+<?php
+
+/**
+ * Validate all attributes in the tokens.
+ */
+
+class HTMLPurifier_Strategy_ValidateAttributes extends HTMLPurifier_Strategy
+{
+
+    public function execute($tokens, $config, $context) {
+
+        // setup validator
+        $validator = new HTMLPurifier_AttrValidator();
+
+        $token = false;
+        $context->register('CurrentToken', $token);
+
+        foreach ($tokens as $key => $token) {
+
+            // only process tokens that have attributes,
+            //   namely start and empty tags
+            if (!$token instanceof HTMLPurifier_Token_Start && !$token instanceof HTMLPurifier_Token_Empty) continue;
+
+            // skip tokens that are armored
+            if (!empty($token->armor['ValidateAttributes'])) continue;
+
+            // note that we have no facilities here for removing tokens
+            $validator->validateToken($token, $config, $context);
+
+            $tokens[$key] = $token; // for PHP 4
+        }
+        $context->destroy('CurrentToken');
+
+        return $tokens;
+    }
+
+}
+
+// vim: et sw=4 sts=4