ControlMatcher: error versus NOMATCH checking (#12551)

This updates the ControlMatcher logic to distinguish between error
conditions versus NOMATCH conditions. Without this patch, ControlMatcher
was emitting incorrect regex matching warnings for NOMATCH conditions.

Author: bneradt

src/proxy/ControlMatcher.cc

@@ -476,13 +476,15 @@ RegexMatcher<Data, MatchResult>::Match(RequestData *rdata, MatchResult *result)
   // The function unescapifyStr() is already called in
   // HttpRequestData::get_string(); therefore, no need to call again here.
   for (int i = 0; i < num_el; i++) {
-    if (regex_array[i].exec(url_str) == true) {
+    RegexMatches matches;
+    int          r = regex_array[i].exec(url_str, matches);
+    if (r >= 0) {
       Dbg(dbg_ctl_matcher, "%s Matched %s with regex at line %d", matcher_name, url_str, data_array[i].line_num);
       data_array[i].UpdateMatch(result, rdata);
-    } else {
+    } else if (r != PCRE2_ERROR_NOMATCH) {
       // An error has occurred
-      Warning("Error matching regex at line %d.", data_array[i].line_num);
-    } // else it's -1 which means no match was found.
+      Warning("Error matching regex for url: %s:%d (%d)", file_name ? file_name : "unknown", data_array[i].line_num, r);
+    } // else: PCRE2_ERROR_NOMATCH
   }
   ats_free(url_str);
 }
@@ -521,14 +523,17 @@ HostRegexMatcher<Data, MatchResult>::Match(RequestData *rdata, MatchResult *resu
     url_str = "";
   }
   for (int i = 0; i < num_el; i++) {
-    if (this->regex_array[i].exec(url_str) == true) {
+    RegexMatches matches;
+    int          r = this->regex_array[i].exec(url_str, matches);
+    if (r >= 0) {
       Dbg(dbg_ctl_matcher, "%s Matched %s with regex at line %d", const_cast<char *>(this->matcher_name), url_str,
           this->data_array[i].line_num);
       this->data_array[i].UpdateMatch(result, rdata);
-    } else {
+    } else if (r != PCRE2_ERROR_NOMATCH) {
       // An error has occurred
-      Warning("error matching regex at line %d", this->data_array[i].line_num);
-    }
+      Warning("Error matching regex for host: %s:%d (%d)", this->file_name ? this->file_name : "unknown",
+              this->data_array[i].line_num, r);
+    } // else: PCRE2_ERROR_NOMATCH
   }
 }
 

src/tsutil/Regex.cc

@@ -312,7 +312,7 @@ Regex::exec(std::string_view subject, uint32_t flags) const
   RegexMatches matches;
 
   int count = this->exec(subject, matches, flags);
-  return count > 0;
+  return count >= 0;
 }
 
 //----------------------------------------------------------------------------
@@ -330,7 +330,7 @@ Regex::exec(std::string_view subject, RegexMatches &matches, uint32_t flags) con
 
   // check if there is a compiled regex
   if (code == nullptr) {
-    return 0;
+    return PCRE2_ERROR_NULL;
   }
   int count = pcre2_match(code, reinterpret_cast<PCRE2_SPTR>(subject.data()), subject.size(), 0, flags,
                           RegexMatches::_MatchData::get(matches._match_data), RegexContext::get_instance()->get_match_context());

src/tsutil/unit_tests/test_Regex.cc

@@ -23,6 +23,9 @@
 #include <string_view>
 #include <vector>
 
+#define PCRE2_CODE_UNIT_WIDTH 8
+#include <pcre2.h>
+
 #include "tscore/ink_assert.h"
 #include "tscore/ink_defs.h"
 #include "tsutil/Regex.h"
@@ -168,7 +171,7 @@ TEST_CASE("Regex", "[libts][Regex]")
     Regex        r;
     RegexMatches matches;
     REQUIRE(r.exec("foo") == false);
-    REQUIRE(r.exec("foo", matches) == 0);
+    REQUIRE(r.exec("foo", matches) == PCRE2_ERROR_NULL);
   }
 
   // test for recompiling the regular expression