From 4277635bed26835cc1d101b2150592d2d107bc6b Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Fri, 16 Mar 2018 13:28:51 -0700
Subject: [PATCH] http2: clean up Http2Settings

Use of a MaybeStackBuffer was just silly. Fix a long standing todo
Reduce code duplication a bit.

PR-URL: https://github.com/nodejs/node/pull/19400
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 src/node_http2.cc | 62 ++++++++++++-----------------------------------
 src/node_http2.h  |  8 +-----
 2 files changed, 16 insertions(+), 54 deletions(-)

diff --git a/src/node_http2.cc b/src/node_http2.cc
index f4fd1ffc127897..a40129fb3fa083 100644
--- a/src/node_http2.cc
+++ b/src/node_http2.cc
@@ -190,60 +190,28 @@ Http2Options::Http2Options(Environment* env) {
 }
 
 void Http2Session::Http2Settings::Init() {
-  entries_.AllocateSufficientStorage(IDX_SETTINGS_COUNT);
   AliasedBuffer<uint32_t, v8::Uint32Array>& buffer =
       env()->http2_state()->settings_buffer;
   uint32_t flags = buffer[IDX_SETTINGS_COUNT];
 
   size_t n = 0;
 
-  if (flags & (1 << IDX_SETTINGS_HEADER_TABLE_SIZE)) {
-    uint32_t val = buffer[IDX_SETTINGS_HEADER_TABLE_SIZE];
-    DEBUG_HTTP2SESSION2(session_, "setting header table size: %d\n", val);
-    entries_[n].settings_id = NGHTTP2_SETTINGS_HEADER_TABLE_SIZE;
-    entries_[n].value = val;
-    n++;
+#define GRABSETTING(N, trace)                                                 \
+  if (flags & (1 << IDX_SETTINGS_##N)) {                                      \
+    uint32_t val = buffer[IDX_SETTINGS_##N];                                  \
+    DEBUG_HTTP2SESSION2(session_, "setting " trace ": %d\n", val);            \
+    entries_[n++] =                                                           \
+        nghttp2_settings_entry {NGHTTP2_SETTINGS_##N, val};                   \
   }
 
-  if (flags & (1 << IDX_SETTINGS_MAX_CONCURRENT_STREAMS)) {
-    uint32_t val = buffer[IDX_SETTINGS_MAX_CONCURRENT_STREAMS];
-    DEBUG_HTTP2SESSION2(session_, "setting max concurrent streams: %d\n", val);
-    entries_[n].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
-    entries_[n].value = val;
-    n++;
-  }
-
-  if (flags & (1 << IDX_SETTINGS_MAX_FRAME_SIZE)) {
-    uint32_t val = buffer[IDX_SETTINGS_MAX_FRAME_SIZE];
-    DEBUG_HTTP2SESSION2(session_, "setting max frame size: %d\n", val);
-    entries_[n].settings_id = NGHTTP2_SETTINGS_MAX_FRAME_SIZE;
-    entries_[n].value = val;
-    n++;
-  }
-
-  if (flags & (1 << IDX_SETTINGS_INITIAL_WINDOW_SIZE)) {
-    uint32_t val = buffer[IDX_SETTINGS_INITIAL_WINDOW_SIZE];
-    DEBUG_HTTP2SESSION2(session_, "setting initial window size: %d\n", val);
-    entries_[n].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
-    entries_[n].value = val;
-    n++;
-  }
-
-  if (flags & (1 << IDX_SETTINGS_MAX_HEADER_LIST_SIZE)) {
-    uint32_t val = buffer[IDX_SETTINGS_MAX_HEADER_LIST_SIZE];
-    DEBUG_HTTP2SESSION2(session_, "setting max header list size: %d\n", val);
-    entries_[n].settings_id = NGHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE;
-    entries_[n].value = val;
-    n++;
-  }
+  GRABSETTING(HEADER_TABLE_SIZE, "header table size");
+  GRABSETTING(MAX_CONCURRENT_STREAMS, "max concurrent streams");
+  GRABSETTING(MAX_FRAME_SIZE, "max frame size");
+  GRABSETTING(INITIAL_WINDOW_SIZE, "initial window size");
+  GRABSETTING(MAX_HEADER_LIST_SIZE, "max header list size");
+  GRABSETTING(ENABLE_PUSH, "enable push");
 
-  if (flags & (1 << IDX_SETTINGS_ENABLE_PUSH)) {
-    uint32_t val = buffer[IDX_SETTINGS_ENABLE_PUSH];
-    DEBUG_HTTP2SESSION2(session_, "setting enable push: %d\n", val);
-    entries_[n].settings_id = NGHTTP2_SETTINGS_ENABLE_PUSH;
-    entries_[n].value = val;
-    n++;
-  }
+#undef GRABSETTING
 
   count_ = n;
 }
@@ -289,7 +257,7 @@ Local<Value> Http2Session::Http2Settings::Pack() {
   ssize_t ret =
       nghttp2_pack_settings_payload(
         reinterpret_cast<uint8_t*>(Buffer::Data(buf)), len,
-        *entries_, count_);
+        &entries_[0], count_);
   if (ret >= 0)
     return buf;
   else
@@ -344,7 +312,7 @@ void Http2Session::Http2Settings::RefreshDefaults(Environment* env) {
 void Http2Session::Http2Settings::Send() {
   Http2Scope h2scope(session_);
   CHECK_EQ(nghttp2_submit_settings(**session_, NGHTTP2_FLAG_NONE,
-                                   *entries_, length()), 0);
+                                   &entries_[0], count_), 0);
 }
 
 void Http2Session::Http2Settings::Done(bool ack) {
diff --git a/src/node_http2.h b/src/node_http2.h
index b4ee1b8e8d775c..780bdc8c6e1919 100644
--- a/src/node_http2.h
+++ b/src/node_http2.h
@@ -1207,12 +1207,6 @@ class Http2Session::Http2Settings : public AsyncWrap {
   void Send();
   void Done(bool ack);
 
-  size_t length() const { return count_; }
-
-  nghttp2_settings_entry* operator*() {
-    return *entries_;
-  }
-
   // Returns a Buffer instance with the serialized SETTINGS payload
   Local<Value> Pack();
 
@@ -1229,7 +1223,7 @@ class Http2Session::Http2Settings : public AsyncWrap {
   Http2Session* session_;
   uint64_t startTime_;
   size_t count_ = 0;
-  MaybeStackBuffer<nghttp2_settings_entry, IDX_SETTINGS_COUNT> entries_;
+  nghttp2_settings_entry entries_[IDX_SETTINGS_COUNT];
 };
 
 class ExternalHeader :