plugins/prefetch/pattern.cc - trafficserver - Git at Google

 /*
   Licensed to the Apache Software Foundation (ASF) under one
   or more contributor license agreements.  See the NOTICE file
   distributed with this work for additional information
   regarding copyright ownership.  The ASF licenses this file
   to you under the Apache License, Version 2.0 (the
   "License"); you may not use this file except in compliance
   with the License.  You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */

 /**
  * @file pattern.cc
  * @brief PRCE related classes.
  * @see pattern.h
  */

 #include "pattern.h"
 #include "tsutil/Regex.h"

 static void
 replaceString(String &str, const String &from, const String &to)
 {
   if (from.empty()) {
     return;
   }

   String::size_type start_pos = 0;
   while ((start_pos = str.find(from, start_pos)) != String::npos) {
     str.replace(start_pos, from.length(), to);
     start_pos += to.length();
   }
 }

 Pattern::Pattern() : _pattern(""), _replacement("") {}

 /**
  * @brief Initializes PCRE2 pattern by providing the subject and replacement strings.
  * @param pattern PCRE2 pattern, a string containing PCRE2 patterns, capturing groups.
  * @param replacement PCRE2 replacement, a string where $0 ... $9 will be replaced with the corresponding capturing groups
  * @return true if successful, false if failure
  */
 bool
 Pattern::init(const String &pattern, const String &replacement)
 {
   _pattern.assign(pattern);
   _replacement.assign(replacement);

   _tokenCount = 0;

   if (!compile()) {
     PrefetchDebug("failed to initialize pattern:'%s', replacement:'%s'", pattern.c_str(), replacement.c_str());
     return false;
   }

   return true;
 }

 /**
  * @brief Initializes PCRE2 pattern by providing the pattern only or pattern+replacement in a single configuration string.
  * @see init()
  * @param config PCRE2 pattern <pattern> or PCRE2 pattern + replacement in format /<pattern>/<replacement>/
  * @return true if successful, false if failure
  */
 bool
 Pattern::init(const String &config)
 {
   if (config[0] == '/') {
     /* This is a config in format /regex/replacement/ */
     String pattern;
     String replacement;

     size_t start   = 1;
     size_t current = 0;
     size_t next    = 1;
     do {
       current = next + 1;
       next    = config.find_first_of('/', current);
     } while (next != String::npos && '\\' == config[next - 1]);

     if (next != String::npos) {
       pattern = config.substr(start, next - start);
     } else {
       /* Error, no closing '/' */
       PrefetchError("failed to parse the pattern in '%s'", config.c_str());
       return false;
     }

     start = next + 1;
     do {
       current = next + 1;
       next    = config.find_first_of('/', current);
     } while (next != String::npos && '\\' == config[next - 1]);

     if (next != String::npos) {
       replacement = config.substr(start, next - start);
     } else {
       /* Error, no closing '/' */
       PrefetchError("failed to parse the replacement in '%s'", config.c_str());
       return false;
     }

     // Remove '\' which escaped '/' inside the pattern and replacement strings.
     ::replaceString(pattern, "\\/", "/");
     ::replaceString(replacement, "\\/", "/");

     return this->init(pattern, replacement);
   } else {
     return this->init(config, "");
   }

   /* Should never get here. */
   return false;
 }

 /**
  * @brief Checks if the pattern object was initialized with a meaningful regex pattern.
  * @return true if initialized, false if not.
  */
 bool
 Pattern::empty() const
 {
   return _pattern.empty() || _regex.empty();
 }

 /**
  * @brief Capture or capture-and-replace depending on whether a replacement string is specified.
  * @see replace()
  * @see capture()
  * @param subject PCRE2 subject string
  * @param result vector of strings where the result of captures or the replacements will be returned.
  * @return true if there was a match and capture or replacement succeeded, false if failure.
  */
 bool
 Pattern::process(const String &subject, StringVector &result)
 {
   if (!_replacement.empty()) {
     /* Replacement pattern was provided in the configuration - capture and replace. */
     String element;
     if (replace(subject, element)) {
       result.push_back(element);
     } else {
       return false;
     }
   } else {
     /* Replacement was not provided so return all capturing groups except the group zero. */
     StringVector captures;
     if (capture(subject, captures)) {
       if (captures.size() == 1) {
         result.push_back(captures[0]);
       } else {
         StringVector::iterator it = captures.begin() + 1;
         for (; it != captures.end(); it++) {
           result.push_back(*it);
         }
       }
     } else {
       return false;
     }
   }

   return true;
 }

 /**
  * @brief PCRE2 matches a subject string against the regex pattern.
  * @param subject PCRE2 subject
  * @return true - matched, false - did not.
  */
 bool
 Pattern::match(const String &subject)
 {
   PrefetchDebug("matching '%s' to '%s'", _pattern.c_str(), subject.c_str());

   if (_regex.empty()) {
     return false;
   }

   RegexMatches matches;
   int          matchCount = _regex.exec(subject, matches, RE_NOTEMPTY);
   if (matchCount < 0) {
     if (matchCount != RE_ERROR_NOMATCH) {
       PrefetchError("matching error %d", matchCount);
     }
     return false;
   }

   return true;
 }

 /**
  * @brief Return all PCRE2 capture groups that matched in the subject string
  * @param subject PCRE2 subject string
  * @param result reference to vector of strings containing all capture groups
  */
 bool
 Pattern::capture(const String &subject, StringVector &result)
 {
   PrefetchDebug("matching '%s' to '%s'", _pattern.c_str(), subject.c_str());

   if (_regex.empty()) {
     return false;
   }

   RegexMatches matches;
   int          matchCount = _regex.exec(subject, matches, RE_NOTEMPTY);

   if (matchCount <= 0) {
     if (matchCount != RE_ERROR_NOMATCH) {
       PrefetchError("matching error %d", matchCount);
     }
     return false;
   }

   for (int i = 0; i < matchCount; i++) {
     std::string_view match = matches[i];
     result.emplace_back(match.data(), match.length());
     PrefetchDebug("capturing '%s' %d", result.back().c_str(), i);
   }

   return true;
 }

 /**
  * @brief Replaces all replacements found in the replacement string with what matched in the PCRE2 capturing groups.
  * @param subject PCRE2 subject string
  * @param result reference to A string where the result of the replacement will be stored
  * @return true - success, false - nothing matched or failure.
  */
 bool
 Pattern::replace(const String &subject, String &result)
 {
   PrefetchDebug("matching '%s' to '%s'", _pattern.c_str(), subject.c_str());

   if (_regex.empty()) {
     return false;
   }

   RegexMatches matches;
   int          matchCount = _regex.exec(subject, matches, RE_NOTEMPTY);

   if (matchCount <= 0) {
     if (matchCount != RE_ERROR_NOMATCH) {
       PrefetchError("matching error %d", matchCount);
     }
     return false;
   }

   /* Verify the replacement has the right number of matching groups */
   for (int i = 0; i < _tokenCount; i++) {
     if (_tokens[i] >= matchCount) {
       PrefetchError("invalid reference in replacement string: $%d", _tokens[i]);
       return false;
     }
   }

   int previous = 0;
   for (int i = 0; i < _tokenCount; i++) {
     int              replIndex = _tokens[i];
     std::string_view dst       = matches[replIndex];

     String src(_replacement, _tokenOffset[i], 2);

     PrefetchDebug("replacing '%s' with '%.*s'", src.c_str(), static_cast<int>(dst.length()), dst.data());

     result.append(_replacement, previous, _tokenOffset[i] - previous);
     result.append(dst.data(), dst.length());

     previous = _tokenOffset[i] + 2; /* 2 is the size of $0 or $1 or $2, ... or $9 */
   }

   result.append(_replacement, previous, _replacement.length() - previous);

   PrefetchDebug("replacing '%s' resulted in '%s'", _replacement.c_str(), result.c_str());

   return true;
 }

 /**
  * @brief PCRE2 compiles the regex, called only during initialization.
  * @return true if successful, false if not.
  */
 bool
 Pattern::compile()
 {
   PrefetchDebug("compiling pattern:'%s', replacement:'%s'", _pattern.c_str(), _replacement.c_str());

   std::string error;
   int         erroffset;
   if (!_regex.compile(_pattern, error, erroffset)) {
     PrefetchError("compile of regex '%s' at char %d: %s", _pattern.c_str(), erroffset, error.c_str());
     return false;
   }

   if (_replacement.empty()) {
     /* No replacement necessary - we are done. */
     return true;
   }

   _tokenCount  = 0;
   bool success = true;

   for (unsigned i = 0; i < _replacement.length(); i++) {
     if (_replacement[i] == '$') {
       if (_tokenCount >= TOKENCOUNT) {
         PrefetchError("too many tokens in replacement string: %s", _replacement.c_str());

         success = false;
         break;
       } else if (_replacement[i + 1] < '0' || _replacement[i + 1] > '9') {
         PrefetchError("invalid replacement token $%c in %s: should be $0 - $9", _replacement[i + 1], _replacement.c_str());

         success = false;
         break;
       } else {
         /* Store the location of the replacement */
         /* Convert '0' to 0 */
         _tokens[_tokenCount]      = _replacement[i + 1] - '0';
         _tokenOffset[_tokenCount] = i;
         _tokenCount++;
         /* Skip the next char */
         i++;
       }
     }
   }

   return success;
 }

 /**
  * @brief Destructor, deletes all patterns.
  */
 MultiPattern::~MultiPattern() {}

 /**
  * @brief Check if empty.
  * @return true if the classification contains any patterns, false otherwise
  */
 bool
 MultiPattern::empty() const
 {
   return _list.empty();
 }

 /**
  * @brief Adds a pattern to the multi-pattern
  *
  * The order of addition matters during the classification
  * @param pattern pattern pointer
  */
 void
 MultiPattern::add(std::unique_ptr<Pattern> pattern)
 {
   this->_list.push_back(std::move(pattern));
 }

 /**
  * @brief Matches the subject string against all patterns.
  * @param subject subject string.
  * @return true if any matches, false if nothing matches.
  */
 bool
 MultiPattern::match(const String &subject) const
 {
   for (auto &p : this->_list) {
     if (nullptr != p && p->match(subject)) {
       return true;
     }
   }
   return false;
 }

 /**
  * @brief Calls Pattern::replace() on all patterns in the multi-pattern one by one until the first match.
  * @param subject subject string.
  * @param result vector of the result.
  * @return true if any matches, false if nothing matches.
  */
 bool
 MultiPattern::replace(const String &subject, String &result) const
 {
   for (auto &p : this->_list) {
     if (nullptr != p && p->replace(subject, result)) {
       return true;
     }
   }
   return false;
 }

 /**
  * @brief Returns the name of the multi-pattern (set during the instantiation only).
  */
 const String &
 MultiPattern::name() const
 {
   return _name;
 }
	/*
	Licensed to the Apache Software Foundation (ASF) under one
	or more contributor license agreements. See the NOTICE file
	distributed with this work for additional information
	regarding copyright ownership. The ASF licenses this file
	to you under the Apache License, Version 2.0 (the
	"License"); you may not use this file except in compliance
	with the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	*/

	/**
	* @file pattern.cc
	* @brief PRCE related classes.
	* @see pattern.h
	*/

	#include "pattern.h"
	#include "tsutil/Regex.h"

	static void
	replaceString(String &str, const String &from, const String &to)
	{
	if (from.empty()) {
	return;
	}

	String::size_type start_pos = 0;
	while ((start_pos = str.find(from, start_pos)) != String::npos) {
	str.replace(start_pos, from.length(), to);
	start_pos += to.length();
	}
	}

	Pattern::Pattern() : _pattern(""), _replacement("") {}

	/**
	* @brief Initializes PCRE2 pattern by providing the subject and replacement strings.
	* @param pattern PCRE2 pattern, a string containing PCRE2 patterns, capturing groups.
	* @param replacement PCRE2 replacement, a string where $0 ... $9 will be replaced with the corresponding capturing groups
	* @return true if successful, false if failure
	*/
	bool
	Pattern::init(const String &pattern, const String &replacement)
	{
	_pattern.assign(pattern);
	_replacement.assign(replacement);

	_tokenCount = 0;

	if (!compile()) {
	PrefetchDebug("failed to initialize pattern:'%s', replacement:'%s'", pattern.c_str(), replacement.c_str());
	return false;
	}

	return true;
	}

	/**
	* @brief Initializes PCRE2 pattern by providing the pattern only or pattern+replacement in a single configuration string.
	* @see init()
	* @param config PCRE2 pattern <pattern> or PCRE2 pattern + replacement in format /<pattern>/<replacement>/
	* @return true if successful, false if failure
	*/
	bool
	Pattern::init(const String &config)
	{
	if (config[0] == '/') {
	/* This is a config in format /regex/replacement/ */
	String pattern;
	String replacement;

	size_t start = 1;
	size_t current = 0;
	size_t next = 1;
	do {
	current = next + 1;
	next = config.find_first_of('/', current);
	} while (next != String::npos && '\\' == config[next - 1]);

	if (next != String::npos) {
	pattern = config.substr(start, next - start);
	} else {
	/* Error, no closing '/' */
	PrefetchError("failed to parse the pattern in '%s'", config.c_str());
	return false;
	}

	start = next + 1;
	do {
	current = next + 1;
	next = config.find_first_of('/', current);
	} while (next != String::npos && '\\' == config[next - 1]);

	if (next != String::npos) {
	replacement = config.substr(start, next - start);
	} else {
	/* Error, no closing '/' */
	PrefetchError("failed to parse the replacement in '%s'", config.c_str());
	return false;
	}

	// Remove '\' which escaped '/' inside the pattern and replacement strings.
	::replaceString(pattern, "\\/", "/");
	::replaceString(replacement, "\\/", "/");

	return this->init(pattern, replacement);
	} else {
	return this->init(config, "");
	}

	/* Should never get here. */
	return false;
	}

	/**
	* @brief Checks if the pattern object was initialized with a meaningful regex pattern.
	* @return true if initialized, false if not.
	*/
	bool
	Pattern::empty() const
	{
	return _pattern.empty() \|\| _regex.empty();
	}

	/**
	* @brief Capture or capture-and-replace depending on whether a replacement string is specified.
	* @see replace()
	* @see capture()
	* @param subject PCRE2 subject string
	* @param result vector of strings where the result of captures or the replacements will be returned.
	* @return true if there was a match and capture or replacement succeeded, false if failure.
	*/
	bool
	Pattern::process(const String &subject, StringVector &result)
	{
	if (!_replacement.empty()) {
	/* Replacement pattern was provided in the configuration - capture and replace. */
	String element;
	if (replace(subject, element)) {
	result.push_back(element);
	} else {
	return false;
	}
	} else {
	/* Replacement was not provided so return all capturing groups except the group zero. */
	StringVector captures;
	if (capture(subject, captures)) {
	if (captures.size() == 1) {
	result.push_back(captures[0]);
	} else {
	StringVector::iterator it = captures.begin() + 1;
	for (; it != captures.end(); it++) {
	result.push_back(*it);
	}
	}
	} else {
	return false;
	}
	}

	return true;
	}

	/**
	* @brief PCRE2 matches a subject string against the regex pattern.
	* @param subject PCRE2 subject
	* @return true - matched, false - did not.
	*/
	bool
	Pattern::match(const String &subject)
	{
	PrefetchDebug("matching '%s' to '%s'", _pattern.c_str(), subject.c_str());

	if (_regex.empty()) {
	return false;
	}

	RegexMatches matches;
	int matchCount = _regex.exec(subject, matches, RE_NOTEMPTY);
	if (matchCount < 0) {
	if (matchCount != RE_ERROR_NOMATCH) {
	PrefetchError("matching error %d", matchCount);
	}
	return false;
	}

	return true;
	}

	/**
	* @brief Return all PCRE2 capture groups that matched in the subject string
	* @param subject PCRE2 subject string
	* @param result reference to vector of strings containing all capture groups
	*/
	bool
	Pattern::capture(const String &subject, StringVector &result)
	{
	PrefetchDebug("matching '%s' to '%s'", _pattern.c_str(), subject.c_str());

	if (_regex.empty()) {
	return false;
	}

	RegexMatches matches;
	int matchCount = _regex.exec(subject, matches, RE_NOTEMPTY);

	if (matchCount <= 0) {
	if (matchCount != RE_ERROR_NOMATCH) {
	PrefetchError("matching error %d", matchCount);
	}
	return false;
	}

	for (int i = 0; i < matchCount; i++) {
	std::string_view match = matches[i];
	result.emplace_back(match.data(), match.length());
	PrefetchDebug("capturing '%s' %d", result.back().c_str(), i);
	}

	return true;
	}

	/**
	* @brief Replaces all replacements found in the replacement string with what matched in the PCRE2 capturing groups.
	* @param subject PCRE2 subject string
	* @param result reference to A string where the result of the replacement will be stored
	* @return true - success, false - nothing matched or failure.
	*/
	bool
	Pattern::replace(const String &subject, String &result)
	{
	PrefetchDebug("matching '%s' to '%s'", _pattern.c_str(), subject.c_str());

	if (_regex.empty()) {
	return false;
	}

	RegexMatches matches;
	int matchCount = _regex.exec(subject, matches, RE_NOTEMPTY);

	if (matchCount <= 0) {
	if (matchCount != RE_ERROR_NOMATCH) {
	PrefetchError("matching error %d", matchCount);
	}
	return false;
	}

	/* Verify the replacement has the right number of matching groups */
	for (int i = 0; i < _tokenCount; i++) {
	if (_tokens[i] >= matchCount) {
	PrefetchError("invalid reference in replacement string: $%d", _tokens[i]);
	return false;
	}
	}

	int previous = 0;
	for (int i = 0; i < _tokenCount; i++) {
	int replIndex = _tokens[i];
	std::string_view dst = matches[replIndex];

	String src(_replacement, _tokenOffset[i], 2);

	PrefetchDebug("replacing '%s' with '%.*s'", src.c_str(), static_cast<int>(dst.length()), dst.data());

	result.append(_replacement, previous, _tokenOffset[i] - previous);
	result.append(dst.data(), dst.length());

	previous = _tokenOffset[i] + 2; /* 2 is the size of $0 or $1 or $2, ... or $9 */
	}

	result.append(_replacement, previous, _replacement.length() - previous);

	PrefetchDebug("replacing '%s' resulted in '%s'", _replacement.c_str(), result.c_str());

	return true;
	}

	/**
	* @brief PCRE2 compiles the regex, called only during initialization.
	* @return true if successful, false if not.
	*/
	bool
	Pattern::compile()
	{
	PrefetchDebug("compiling pattern:'%s', replacement:'%s'", _pattern.c_str(), _replacement.c_str());

	std::string error;
	int erroffset;
	if (!_regex.compile(_pattern, error, erroffset)) {
	PrefetchError("compile of regex '%s' at char %d: %s", _pattern.c_str(), erroffset, error.c_str());
	return false;
	}

	if (_replacement.empty()) {
	/* No replacement necessary - we are done. */
	return true;
	}

	_tokenCount = 0;
	bool success = true;

	for (unsigned i = 0; i < _replacement.length(); i++) {
	if (_replacement[i] == '$') {
	if (_tokenCount >= TOKENCOUNT) {
	PrefetchError("too many tokens in replacement string: %s", _replacement.c_str());

	success = false;
	break;
	} else if (_replacement[i + 1] < '0' \|\| _replacement[i + 1] > '9') {
	PrefetchError("invalid replacement token $%c in %s: should be $0 - $9", _replacement[i + 1], _replacement.c_str());

	success = false;
	break;
	} else {
	/* Store the location of the replacement */
	/* Convert '0' to 0 */
	_tokens[_tokenCount] = _replacement[i + 1] - '0';
	_tokenOffset[_tokenCount] = i;
	_tokenCount++;
	/* Skip the next char */
	i++;
	}
	}
	}

	return success;
	}

	/**
	* @brief Destructor, deletes all patterns.
	*/
	MultiPattern::~MultiPattern() {}

	/**
	* @brief Check if empty.
	* @return true if the classification contains any patterns, false otherwise
	*/
	bool
	MultiPattern::empty() const
	{
	return _list.empty();
	}

	/**
	* @brief Adds a pattern to the multi-pattern
	*
	* The order of addition matters during the classification
	* @param pattern pattern pointer
	*/
	void
	MultiPattern::add(std::unique_ptr<Pattern> pattern)
	{
	this->_list.push_back(std::move(pattern));
	}

	/**
	* @brief Matches the subject string against all patterns.
	* @param subject subject string.
	* @return true if any matches, false if nothing matches.
	*/
	bool
	MultiPattern::match(const String &subject) const
	{
	for (auto &p : this->_list) {
	if (nullptr != p && p->match(subject)) {
	return true;
	}
	}
	return false;
	}

	/**
	* @brief Calls Pattern::replace() on all patterns in the multi-pattern one by one until the first match.
	* @param subject subject string.
	* @param result vector of the result.
	* @return true if any matches, false if nothing matches.
	*/
	bool
	MultiPattern::replace(const String &subject, String &result) const
	{
	for (auto &p : this->_list) {
	if (nullptr != p && p->replace(subject, result)) {
	return true;
	}
	}
	return false;
	}

	/**
	* @brief Returns the name of the multi-pattern (set during the instantiation only).
	*/
	const String &
	MultiPattern::name() const
	{
	return _name;
	}