From 407899404dbf9decc8be2cf5e7acf5b1aec05f93 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Mon, 23 Jan 2017 19:16:57 +1100
Subject: [PATCH 1/2] http/h2_connection: Add some (optional) debugging calls

---
 http/h2_connection.lua | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/http/h2_connection.lua b/http/h2_connection.lua
index e1f445bb..144ffa01 100644
--- a/http/h2_connection.lua
+++ b/http/h2_connection.lua
@@ -160,6 +160,12 @@ local function new_connection(socket, conn_type, settings)
 	socket:setvbuf("full", math.huge) -- 'infinite' buffering; no write locks needed
 	socket:setmode("b", "bna") -- writes that don't explicitly buffer will now flush the buffer. autoflush on
 	socket:onerror(onerror)
+	if self.debug then
+		self.debug(string.format("h2_connection.new(socket=%s, type=%s, ...) = %s\n",
+			tostring(socket),
+			conn_type,
+			tostring(self)))
+	end
 	if self.type == "client" then
 		assert(socket:xwrite(preface, "f", 0))
 	end
@@ -387,6 +393,15 @@ function connection_methods:read_http2_frame(timeout)
 	end
 	-- reserved bit MUST be ignored by receivers
 	streamid = band(streamid, 0x7fffffff)
+	if self.debug then
+		self.debug(string.format("h2_connection.read_http2_frame(self=%s, timeout=%f) = type=%s, flags=%d, streamid=%d, #payload=%d\n",
+			tostring(self),
+			timeout or math.huge,
+			h2_stream.frame_types[typ] or tostring(typ),
+			flags,
+			streamid,
+			#payload))
+	end
 	return typ, flags, streamid, payload
 end
 
@@ -394,6 +409,16 @@ end
 -- hence it's not always total failure.
 -- It's up to the caller to take some action (e.g. closing) rather than doing it here
 function connection_methods:write_http2_frame(typ, flags, streamid, payload, timeout, flush)
+	if self.debug then
+		self.debug(string.format("h2_connection.write_http2_frame(self=%s, type=%s, flags=%d, streamid=%d, #payload=%d, timeout=%f, flush=%q)\n",
+			tostring(self),
+			h2_stream.frame_types[typ] or tostring(typ),
+			flags,
+			streamid,
+			#payload,
+			timeout or math.huge,
+			flush or ""))
+	end
 	if #payload > self.peer_settings[known_settings.MAX_FRAME_SIZE] then
 		return nil, h2_error.errors.FRAME_SIZE_ERROR:new_traceback("frame too large"), ce.E2BIG
 	end

From 4d716b54eb7c59a32b1d7025c136b8008bb750c9 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Mon, 23 Jan 2017 19:36:00 +1100
Subject: [PATCH 2/2] http/connection_common: Initialise connection.debug from
 environmental variable

---
 http/connection_common.lua | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/http/connection_common.lua b/http/connection_common.lua
index 432acfe4..cf0267bb 100644
--- a/http/connection_common.lua
+++ b/http/connection_common.lua
@@ -4,6 +4,16 @@ local ce = require "cqueues.errno"
 
 local connection_methods = {}
 
+local function positive(x)
+	return x ~= nil and x ~= "0" and x:lower() ~= "false" and x:lower() ~= "no"
+end
+
+if positive(os.getenv "LUA_HTTP_DEBUG") then
+	function connection_methods.debug(...)
+		io.stderr:write(...)
+	end
+end
+
 local function onerror(socket, op, why, lvl) -- luacheck: ignore 212
 	local err = string.format("%s: %s", op, ce.strerror(why))
 	if op == "starttls" then