Add regular expression support in header match

docs/configuration/http_conn_man/route_config/route.rst

@@ -198,7 +198,7 @@ The router can match a request to a route based on headers specified in the rout
 .. code-block:: json
 
   [
-    {"name": "...", "value": "..."}
+    {"name": "...", "value": "...", "regex": "..."}
   ]
 
 name
@@ -208,6 +208,11 @@ value
   *(optional, string)* Specifies the value of the header. If the value is absent a request that has
   the *name* header will match, regardless of the header's value.
 
+regex
+  *(optional, boolean)* Specifies whether the header value is a regular
+  expression or not. Defaults to false. The regex grammar used in the value field
+  is defined `here <http://en.cppreference.com/w/cpp/regex/ecmascript>`_.
+
 The router will check the request's headers against all the specified
 headers in the route config. A match will happen if all the headers in the route are present in
 the request with the same values (or based on presence if the ``value`` field is not in the config).

docs/configuration/http_filters/fault_filter.rst

@@ -119,7 +119,7 @@ actual fault injection further depend on the values of *abort_percent* and
 .. code-block:: json
 
   [
-    {"name": "...", "value": "..."}
+    {"name": "...", "value": "...", "regex": "..."}
   ]
 
 name
@@ -130,6 +130,11 @@ value
   absent a request that has the *name* header will match, regardless of the
   header's value.
 
+regex
+  *(optional, boolean)* Specifies whether the header value is a regular expression
+  or not. Defaults to false. The regex grammar used in the value field
+  is defined `here <http://en.cppreference.com/w/cpp/regex/ecmascript>`_.
+
 The filter will check the request's headers against all the specified
 headers in the filter config. A match will happen if all the headers in the
 config are present in the request with the same values (or based on

source/common/http/filter/fault_filter.cc

@@ -60,7 +60,8 @@ FaultFilterConfig::FaultFilterConfig(const Json::Object& json_config, Runtime::L
     for (const Json::ObjectPtr& header_map : config_headers) {
       // allow header value to be empty, allows matching to be only based on header presence.
       fault_filter_headers_.emplace_back(Http::LowerCaseString(header_map->getString("name")),
-                                         header_map->getString("value", EMPTY_STRING));
+                                         header_map->getString("value", EMPTY_STRING),
+                                         header_map->getBoolean("regex", false));
     }
   }
 }

source/common/router/config_impl.cc

@@ -48,17 +48,20 @@ Upstream::ResourcePriority ConfigUtility::parsePriority(const Json::Object& conf
   }
 }
 
-bool ConfigUtility::matchHeaders(const Http::HeaderMap& headers,
-                                 const std::vector<HeaderData> request_headers) {
+bool ConfigUtility::matchHeaders(const Http::HeaderMap& request_headers,
+                                 const std::vector<HeaderData> config_headers) {
   bool matches = true;
 
-  if (!request_headers.empty()) {
-    for (const HeaderData& header_data : request_headers) {
-      const Http::HeaderEntry* header = headers.get(header_data.name_);
-      if (header_data.value_ == EMPTY_STRING) {
+  if (!config_headers.empty()) {
+    for (const HeaderData& cfg_header_data : config_headers) {
+      const Http::HeaderEntry* header = request_headers.get(cfg_header_data.name_);
+      if (cfg_header_data.value_.empty()) {
         matches &= (header != nullptr);
+      } else if (!cfg_header_data.is_regex_) {
+        matches &= (header != nullptr) && (header->value() == cfg_header_data.value_.c_str());
       } else {
-        matches &= (header != nullptr) && (header->value() == header_data.value_.c_str());
+        matches &= (header != nullptr) &&
+                   std::regex_match(header->value().c_str(), cfg_header_data.regex_pattern_);
       }
       if (!matches) {
         break;
@@ -91,8 +94,11 @@ RouteEntryImplBase::RouteEntryImplBase(const VirtualHostImpl& vhost, const Json:
     std::vector<Json::ObjectPtr> config_headers = route.getObjectArray("headers");
     for (const Json::ObjectPtr& header_map : config_headers) {
       // allow header value to be empty, allows matching to be only based on header presence.
+      // Regex is an opt-in. Unless explicitly mentioned, we will use header values for exact string
+      // matches.
       config_headers_.emplace_back(Http::LowerCaseString(header_map->getString("name")),
-                                   header_map->getString("value", EMPTY_STRING));
+                                   header_map->getString("value", EMPTY_STRING),
+                                   header_map->getBoolean("regex", false));
     }
   }
 }

source/common/router/config_impl.h

@@ -46,11 +46,14 @@ class SslRedirector : public RedirectEntry {
 class ConfigUtility {
 public:
   struct HeaderData {
-    HeaderData(const Http::LowerCaseString& name, const std::string& value)
-        : name_(name), value_(value) {}
+    HeaderData(const Http::LowerCaseString& name, const std::string& value, const bool is_regex)
+        : name_(name), value_(value), regex_pattern_(value_, std::regex::optimize),
+          is_regex_(is_regex) {}
 
     const Http::LowerCaseString name_;
     const std::string value_;
+    const std::regex regex_pattern_;
+    const bool is_regex_;
   };
 
   /**

test/common/router/config_impl_test.cc

@@ -3,8 +3,8 @@
 #include "common/json/json_loader.h"
 #include "common/router/config_impl.h"
 
-#include "test/mocks/upstream/mocks.h"
 #include "test/mocks/runtime/mocks.h"
+#include "test/mocks/upstream/mocks.h"
 #include "test/test_common/utility.h"
 
 using testing::_;
@@ -436,6 +436,20 @@ TEST(RouteMatcherTest, HeaderMatchedRouting) {
             {"name": "test_header_presence"}
           ]
         },
+        {
+          "prefix": "/",
+          "cluster": "local_service_with_header_pattern_set_regex",
+          "headers" : [
+            {"name": "test_header_pattern", "value": "^user=test-\\d+$", "regex": true}
+          ]
+        },
+        {
+          "prefix": "/",
+          "cluster": "local_service_with_header_pattern_unset_regex",
+          "headers" : [
+            {"name": "test_header_pattern", "value": "^customer=test-\\d+$"}
+          ]
+        },
         {
           "prefix": "/",
           "cluster": "local_service_without_headers"
@@ -484,6 +498,19 @@ TEST(RouteMatcherTest, HeaderMatchedRouting) {
     EXPECT_EQ("local_service_with_empty_headers",
               config.routeForRequest(headers, 0)->clusterName());
   }
+
+  {
+    Http::TestHeaderMapImpl headers = genHeaders("www.lyft.com", "/", "GET");
+    headers.addViaCopy("test_header_pattern", "user=test-1223");
+    EXPECT_EQ("local_service_with_header_pattern_set_regex",
+              config.routeForRequest(headers, 0)->clusterName());
+  }
+
+  {
+    Http::TestHeaderMapImpl headers = genHeaders("www.lyft.com", "/", "GET");
+    headers.addViaCopy("test_header_pattern", "customer=test-1223");
+    EXPECT_EQ("local_service_without_headers", config.routeForRequest(headers, 0)->clusterName());
+  }
 }
 
 TEST(RouteMatcherTest, ContentType) {