http/h2_connection: fix busy-loop when waiting for preface

Author: daurnimator

http/h2_connection.lua

@@ -233,8 +233,10 @@ function connection_methods:step(timeout)
 	local deadline = timeout and monotime()+timeout
 	if not self.has_confirmed_preface and self.type == "server" then
 		local ok, err, errno = socket_has_preface(self.socket, false, timeout)
+		self.had_eagain = false
 		if ok == nil then
 			if errno == ce.ETIMEDOUT then
+				self.had_eagain = true
 				return true
 			end
 			return nil, err, errno

spec/h2_connection_spec.lua

@@ -54,6 +54,14 @@ describe("http2 connection", function()
 		test_preface("PRI * HTTP/2.0\r\n\r\nSM\r\n\r") -- missing last \n
 		test_preface(("long string"):rep(1000))
 	end)
+	it("Doesn't busy-loop looking for #preface", function()
+		local s, c = ca.assert(cs.pair())
+		s = assert(h2_connection.new(s, "server"))
+		assert(s:step(0))
+		assert.not_same(0, (s:timeout()))
+		c:close()
+		s:close()
+	end)
 	it("read_http2_frame fails with EILSEQ on corrupt frame", function()
 		local spack = string.pack or require "compat53.string".pack -- luacheck: ignore 143
 		local s, c = ca.assert(cs.pair())