From 5b17655818ad7e9a027a24e2e33e5cf43e46e990 Mon Sep 17 00:00:00 2001
From: Sunjay Bhatia <sunjayb@vmware.com>
Date: Fri, 26 Feb 2021 15:06:10 -0500
Subject: [PATCH] lua http filter: Expose requestedServerName on streamInfo

Fixes https://github.com/envoyproxy/envoy/issues/15142

Signed-off-by: Sunjay Bhatia <sunjayb@vmware.com>
---
 .../http/http_filters/lua_filter.rst          | 11 ++++++++++
 .../extensions/filters/http/lua/wrappers.cc   |  5 +++++
 source/extensions/filters/http/lua/wrappers.h |  9 ++++++++-
 .../filters/http/lua/lua_filter_test.cc       | 20 +++++++++++++++++++
 .../filters/http/lua/lua_integration_test.cc  |  7 +++++++
 .../filters/http/lua/wrappers_test.cc         | 19 ++++++++++++++++++
 6 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/docs/root/configuration/http/http_filters/lua_filter.rst b/docs/root/configuration/http/http_filters/lua_filter.rst
index 126667737271..387c796cb86b 100644
--- a/docs/root/configuration/http/http_filters/lua_filter.rst
+++ b/docs/root/configuration/http/http_filters/lua_filter.rst
@@ -692,6 +692,17 @@ Returns a downstream :ref:`SSL connection info object <config_http_filters_lua_s
 
 .. _config_http_filters_lua_stream_info_dynamic_metadata_wrapper:
 
+requestedServerName()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: lua
+
+  streamInfo:requestedServerName()
+
+// TODO: fix this below
+Returns the string representation of :repo:`requested server name <include/envoy/stream_info/stream_info.h>`
+(e.g. SNI in TLS) for the current request if present.
+
 Dynamic metadata object API
 ---------------------------
 
diff --git a/source/extensions/filters/http/lua/wrappers.cc b/source/extensions/filters/http/lua/wrappers.cc
index 68b7af66188d..04fa2842ea64 100644
--- a/source/extensions/filters/http/lua/wrappers.cc
+++ b/source/extensions/filters/http/lua/wrappers.cc
@@ -141,6 +141,11 @@ int StreamInfoWrapper::luaDownstreamDirectRemoteAddress(lua_State* state) {
   return 1;
 }
 
+int StreamInfoWrapper::luaRequestedServerName(lua_State* state) {
+  lua_pushstring(state, stream_info_.requestedServerName().c_str());
+  return 1;
+}
+
 DynamicMetadataMapIterator::DynamicMetadataMapIterator(DynamicMetadataMapWrapper& parent)
     : parent_{parent}, current_{parent_.streamInfo().dynamicMetadata().filter_metadata().begin()} {}
 
diff --git a/source/extensions/filters/http/lua/wrappers.h b/source/extensions/filters/http/lua/wrappers.h
index ba4170dbfaaa..3a1124c4c3cb 100644
--- a/source/extensions/filters/http/lua/wrappers.h
+++ b/source/extensions/filters/http/lua/wrappers.h
@@ -186,7 +186,8 @@ class StreamInfoWrapper : public Filters::Common::Lua::BaseLuaObject<StreamInfoW
             {"dynamicMetadata", static_luaDynamicMetadata},
             {"downstreamLocalAddress", static_luaDownstreamLocalAddress},
             {"downstreamDirectRemoteAddress", static_luaDownstreamDirectRemoteAddress},
-            {"downstreamSslConnection", static_luaDownstreamSslConnection}};
+            {"downstreamSslConnection", static_luaDownstreamSslConnection},
+            {"requestedServerName", static_luaRequestedServerName}};
   }
 
 private:
@@ -221,6 +222,12 @@ class StreamInfoWrapper : public Filters::Common::Lua::BaseLuaObject<StreamInfoW
    */
   DECLARE_LUA_FUNCTION(StreamInfoWrapper, luaDownstreamDirectRemoteAddress);
 
+  /**
+   * Get requested server name
+   * @return requested server name (e.g. SNI in TLS), if any.
+   */
+  DECLARE_LUA_FUNCTION(StreamInfoWrapper, luaRequestedServerName);
+
   // Envoy::Lua::BaseLuaObject
   void onMarkDead() override {
     dynamic_metadata_wrapper_.reset();
diff --git a/test/extensions/filters/http/lua/lua_filter_test.cc b/test/extensions/filters/http/lua/lua_filter_test.cc
index 55fb35aca76f..49735403cc8b 100644
--- a/test/extensions/filters/http/lua/lua_filter_test.cc
+++ b/test/extensions/filters/http/lua/lua_filter_test.cc
@@ -1778,6 +1778,26 @@ TEST_F(LuaHttpFilterTest, GetCurrentProtocol) {
   EXPECT_EQ(Http::FilterHeadersStatus::Continue, filter_->decodeHeaders(request_headers, true));
 }
 
+// Get the requested server name.
+TEST_F(LuaHttpFilterTest, GetRequestedServerName) {
+  const std::string SCRIPT{R"EOF(
+    function envoy_on_request(request_handle)
+      request_handle:logTrace(request_handle:streamInfo():requestedServerName())
+    end
+  )EOF"};
+
+  InSequence s;
+  setup(SCRIPT);
+
+  EXPECT_CALL(decoder_callbacks_, streamInfo()).WillOnce(ReturnRef(stream_info_));
+  std::string server_name = "foo.example.com";
+  EXPECT_CALL(stream_info_, requestedServerName()).WillOnce(ReturnRef(server_name));
+
+  Http::TestRequestHeaderMapImpl request_headers{{":path", "/"}};
+  EXPECT_CALL(*filter_, scriptLog(spdlog::level::trace, StrEq("foo.example.com")));
+  EXPECT_EQ(Http::FilterHeadersStatus::Continue, filter_->decodeHeaders(request_headers, true));
+}
+
 // Set and get stream info dynamic metadata.
 TEST_F(LuaHttpFilterTest, SetGetDynamicMetadata) {
   const std::string SCRIPT{R"EOF(
diff --git a/test/extensions/filters/http/lua/lua_integration_test.cc b/test/extensions/filters/http/lua/lua_integration_test.cc
index 342259997c13..c203579a05d4 100644
--- a/test/extensions/filters/http/lua/lua_integration_test.cc
+++ b/test/extensions/filters/http/lua/lua_integration_test.cc
@@ -291,6 +291,8 @@ name: lua
         request_handle:streamInfo():downstreamLocalAddress())
       request_handle:headers():add("request_downstream_directremote_address_value", 
         request_handle:streamInfo():downstreamDirectRemoteAddress())
+      request_handle:headers():add("request_requested_server_name",
+        request_handle:streamInfo():requestedServerName())
     end
 
     function envoy_on_response(response_handle)
@@ -364,6 +366,11 @@ name: lua
           .getStringView(),
       GetParam() == Network::Address::IpVersion::v4 ? "127.0.0.1:" : "[::1]:"));
 
+  EXPECT_EQ("", upstream_request_->headers()
+                    .get(Http::LowerCaseString("request_requested_server_name"))[0]
+                    ->value()
+                    .getStringView());
+
   Http::TestResponseHeaderMapImpl response_headers{{":status", "200"}, {"foo", "bar"}};
   upstream_request_->encodeHeaders(response_headers, false);
   Buffer::OwnedImpl response_data1("good");
diff --git a/test/extensions/filters/http/lua/wrappers_test.cc b/test/extensions/filters/http/lua/wrappers_test.cc
index 04f5deef048c..2097b2696452 100644
--- a/test/extensions/filters/http/lua/wrappers_test.cc
+++ b/test/extensions/filters/http/lua/wrappers_test.cc
@@ -300,6 +300,25 @@ TEST_F(LuaStreamInfoWrapperTest, ReturnCurrentDownstreamAddresses) {
   wrapper.reset();
 }
 
+TEST_F(LuaStreamInfoWrapperTest, ReturnRequestedServerName) {
+  const std::string SCRIPT{R"EOF(
+      function callMe(object)
+        testPrint(object:requestedServerName())
+      end
+    )EOF"};
+
+  InSequence s;
+  setup(SCRIPT);
+
+  NiceMock<Envoy::StreamInfo::MockStreamInfo> stream_info;
+  stream_info.requested_server_name_ = "some.sni.io";
+  Filters::Common::Lua::LuaDeathRef<StreamInfoWrapper> wrapper(
+      StreamInfoWrapper::create(coroutine_->luaState(), stream_info), true);
+  EXPECT_CALL(printer_, testPrint("some.sni.io"));
+  start("callMe");
+  wrapper.reset();
+}
+
 // Set, get and iterate stream info dynamic metadata.
 TEST_F(LuaStreamInfoWrapperTest, SetGetAndIterateDynamicMetadata) {
   const std::string SCRIPT{R"EOF(