Merge pull request #2909 from DataDog/maximo/consistent-query-string-…

…regexp-config

Fixing DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP Empty Value Behavior

src/DDTrace/Util/Normalizer.php

@@ -216,10 +216,9 @@ private static function generateFilteredPostFields($postKey, $postVal, array $wh
                 // Concatenate the postkey and postval into '<postkey>=<postval>'
                 $postField = "$postKey=$postVal";
 
-                // Match it with the regex to redact if needed
+                // Match it with the regex to redact if needed and regex is not empty
                 $obfuscationRegex = \ini_get('datadog.trace.obfuscation_query_string_regexp');
-                $obfuscationRegex = '(' . $obfuscationRegex . ')';
-                if (preg_match($obfuscationRegex, $postField)) {
+                if ($obfuscationRegex != "" && preg_match('(' . $obfuscationRegex . ')', $postField)) {
                     return [$postKey => '<redacted>'];
                 } else {
                     return [$postKey => $postVal];

tests/ext/root_span_url_with_query_params_obfuscation_empty.phpt

@@ -0,0 +1,23 @@
+--TEST--
+Root span with http.url and unobfuscated query string with empty regex
+--INI--
+datadog.trace.obfuscation_query_string_regexp=
+--ENV--
+DD_TRACE_GENERATE_ROOT_SPAN=0
+HTTPS=off
+HTTP_HOST=localhost:9999
+SCRIPT_NAME=/foo.php
+REQUEST_URI=/users?application_key=123
+QUERY_STRING=application_key=123
+METHOD=GET
+--GET--
+application_key=123
+--FILE--
+<?php
+DDTrace\start_span();
+DDTrace\close_span();
+$spans = dd_trace_serialize_closed_spans();
+var_dump($spans[0]['meta']["http.url"]);
+?>
+--EXPECT--
+string(48) "https://localhost:9999/users?application_key=123"

zend_abstract_interface/uri_normalization/uri_normalization.c

@@ -157,7 +157,7 @@ zend_string *zai_filter_query_string(zai_str queryString, zend_array *whitelist,
         zend_hash_get_current_key(whitelist, &str, &numkey);
         if (zend_string_equals_literal(str, "*")) {
             zend_string *qs = zend_string_init(queryString.ptr, queryString.len, 0);
-            if (pattern) {
+            if (pattern && ZSTR_LEN(pattern)) {
                 zend_string *replacement = zend_string_init(ZEND_STRL("<redacted>"), 0);
 
                 smart_str regex = {0};