id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
2188	Regex matches bad strings	koen@…	John Maddock	"I wrote the following small program to test if a string is a valid ip. The regex gives a false positive for the case listed below.
For comparison I've also added a perl program which does it correctly.

#include <iostream>
#include <boost/regex.hpp>

bool regex_match(const std::string &text, const std::string &match) {
  try {
    const boost::regex regex(match);
    boost::smatch matches;
    return boost::regex_match(text, matches, regex);
  } catch(boost::regex_error &e) {
    return false;
  }
}

int main() {
  if(regex_match(""1.2.03"", ""^(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])(\\.(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])){3}$"")) {
    std::cout << ""GOOD :)\n"";
  } else {
    std::cout << ""BAD  :(\n"";
  }
}

The corresponding perl program does it correctly:

if('1.2.03' =~ m/^(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])(\.(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])){3}$/) {
  print ""GOOD :)\n"";
}

"	Bugs	closed	Boost 1.37.0	regex	Boost Development Trunk	Problem	fixed	regex false positive