epee: tighten the URL parsing regexp a little

fixes massive amounts of time spent on pathological inputs

Found by OSS-Fuzz

contrib/epee/include/net/net_parse_helpers.h

@@ -131,8 +131,8 @@ namespace net_utils
   inline
     bool parse_url_ipv6(const std::string url_str, http::url_content& content)
   {
-    STATIC_REGEXP_EXPR_1(rexp_match_uri, "^((.*?)://)?(\\[(.*)\\](:(\\d+))?)(.*)?", boost::regex::icase | boost::regex::normal);
-    //                                     12         3   4      5 6        7
+    STATIC_REGEXP_EXPR_1(rexp_match_uri, "^(([^:]*?)://)?(\\[(.*)\\](:(\\d+))?)(.*)?", boost::regex::icase | boost::regex::normal);
+    //                                     12            3   4      5 6        7
 
     content.port = 0;
     boost::smatch result;
@@ -175,8 +175,8 @@ namespace net_utils
 
     ///iframe_test.html?api_url=http://api.vk.com/api.php&api_id=3289090&api_settings=1&viewer_id=562964060&viewer_type=0&sid=0aad8d1c5713130f9ca0076f2b7b47e532877424961367d81e7fa92455f069be7e21bc3193cbd0be11895&secret=368ebbc0ef&access_token=668bc03f43981d883f73876ffff4aa8564254b359cc745dfa1b3cde7bdab2e94105d8f6d8250717569c0a7&user_id=0&group_id=0&is_app_user=1&auth_key=d2f7a895ca5ff3fdb2a2a8ae23fe679a&language=0&parent_language=0&ad_info=ElsdCQBaQlxiAQRdFUVUXiN2AVBzBx5pU1BXIgZUJlIEAWcgAUoLQg==&referrer=unknown&lc_name=9834b6a3&hash=
     //STATIC_REGEXP_EXPR_1(rexp_match_uri, "^([^?#]*)(\\?([^#]*))?(#(.*))?", boost::regex::icase | boost::regex::normal);
-    STATIC_REGEXP_EXPR_1(rexp_match_uri, "^((.*?)://)?(([^/:]*)(:(\\d+))?)(.*)?", boost::regex::icase | boost::regex::normal);
-    //                                     12         34      5 6        7
+    STATIC_REGEXP_EXPR_1(rexp_match_uri, "^(([^:]*?)://)?(([^/:]*)(:(\\d+))?)(.*)?", boost::regex::icase | boost::regex::normal);
+    //                                     12            34       5 6        7
     content.port = 0;
     boost::smatch result;	
     if(!(boost::regex_search(url_str, result, rexp_match_uri, boost::match_default) && result[0].matched))