1 files changed, 186 insertions, 0 deletions
diff --git a/modules/http/http_tls_cert.lua b/modules/http/http_tls_cert.lua
new file mode 100644
index 0000000..7e557c4
--- /dev/null
+++ b/modules/http/http_tls_cert.lua
@@ -0,0 +1,186 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+--[[
+	Conventions:
+		- key = private+public key-pair in openssl.pkey format
+		- certs = lua list of certificates (at least one), each in openssl.x509 format,
+			ordered from leaf to almost-root
+		- panic('...') is used on bad problems instead of returning nils or such
+--]]
+local tls_cert = {}
+
+local ffi = require('ffi')
+local x509, pkey = require('openssl.x509'), require('openssl.pkey')
+
+-- @function Create self-signed certificate; return certs, key
+local function new_ephemeral(host)
+	-- Import luaossl directly
+	local name = require('openssl.x509.name')
+	local altname = require('openssl.x509.altname')
+	local openssl_bignum = require('openssl.bignum')
+	local openssl_rand = require('openssl.rand')
+	-- Create self-signed certificate
+	host = host or hostname()
+	local crt = x509.new()
+	local now = os.time()
+	crt:setVersion(3)
+	-- serial needs to be unique or browsers will show uninformative error messages
+	crt:setSerial(openssl_bignum.fromBinary(openssl_rand.bytes(16)))
+	-- use the host we're listening on as canonical name
+	local dn = name.new()
+	dn:add("CN", host)
+	crt:setSubject(dn)
+	crt:setIssuer(dn) -- should match subject for a self-signed
+	local alt = altname.new()
+	alt:add("DNS", host)
+	crt:setSubjectAlt(alt)
+	-- Valid for 90 days
+	crt:setLifetime(now, now + 90*60*60*24)
+	-- Can't be used as a CA
+	crt:setBasicConstraints{CA=false}
+	crt:setBasicConstraintsCritical(true)
+	-- Create and set key (default: EC/P-256 as a most "interoperable")
+	local key = pkey.new {type = 'EC', curve = 'prime256v1'}
+	crt:setPublicKey(key)
+	crt:sign(key)
+	return { crt }, key
+end
+
+-- @function Write certs and key to files
+local function write_cert_files(certs, key, certfile, keyfile)
+	-- Write certs
+	local f = assert(io.open(certfile, 'w'), string.format('cannot open "%s" for writing', certfile))
+	for _, cert in ipairs(certs) do
+		f:write(tostring(cert))
+	end
+	f:close()
+	-- Write key as a pair
+	f = assert(io.open(keyfile, 'w'), string.format('cannot open "%s" for writing', keyfile))
+	local pub, priv = key:toPEM('public', 'private')
+	assert(f:write(pub .. priv))
+	f:close()
+end
+
+-- @function Start maintenance of a self-signed TLS context (at ephem_state.ctx).
+-- Keep updating the ephem_state.servers table.  Stop updating by calling _destroy().
+-- TODO: each process maintains its own ephemeral cert ATM, and the files aren't ever read from.
+function tls_cert.ephemeral_state_maintain(ephem_state, certfile, keyfile)
+	local certs, key = new_ephemeral()
+	write_cert_files(certs, key, certfile, keyfile)
+	ephem_state.ctx = tls_cert.new_tls_context(certs, key)
+	-- Each server needs to have its ctx updated.
+	for _, s in pairs(ephem_state.servers) do
+		s.server.ctx = ephem_state.ctx
+		s.config.ctx = ephem_state.ctx -- not required, but let's keep it synchronized
+	end
+	log_info(ffi.C.LOG_GRP_HTTP, 'created new ephemeral TLS certificate')
+	local _, expiry_stamp = certs[1]:getLifetime()
+	local wait_msec = 1000 * math.max(1, expiry_stamp - os.time() - 3 * 24 * 3600)
+	if not ephem_state.timer_id then
+		ephem_state.timer_id = event.after(wait_msec, function ()
+			tls_cert.ephemeral_state_maintain(ephem_state, certfile, keyfile)
+		end)
+	else
+		event.reschedule(ephem_state.timer_id, wait_msec)
+	end
+end
+function tls_cert.ephemeral_state_destroy(ephem_state)
+	if ephem_state and ephem_state.timer_id then
+		event.cancel(ephem_state.timer_id)
+	end
+end
+
+-- @function Read a certificate chain and a key from files; return certs, key
+function tls_cert.load(certfile, keyfile)
+	-- get key
+	local f, err = io.open(keyfile, 'r')
+	if not f then
+		panic('[http] unable to open TLS key file: %s', err)
+	end
+	local key = pkey.new(f:read('*all'))
+	f:close()
+	if not key then
+		panic('[http] unable to parse TLS key file %s', keyfile)
+	end
+
+	-- get certs list
+	local certs = {}
+	local f, err = io.open(certfile, 'r')
+	if not f then
+		panic('[http] unable to read TLS certificate file: %s', err)
+	end
+	while true do
+		-- Get the next "block" = single certificate as PEM string.
+		local block = nil
+		local line
+		repeat
+			line = f:read()
+			if not line then break end
+			if block then
+				block = block .. '\n' .. line
+			else
+				block = line
+			end
+			-- separator: "posteb" in https://tools.ietf.org/html/rfc7468#section-3
+		until string.sub(line, 1, 9) == '-----END '
+		-- Empty block means clean EOF.
+		if not block then break end
+		if not line then
+			panic('[http] unable to parse TLS certificate file %s, certificate number %d', certfile, 1 + #certs)
+		end
+
+		-- Parse the cert and append to the list.
+		local cert = x509.new(block, 'PEM')
+		if not cert then
+			panic('[http] unable to parse TLS certificate file %s, certificate number %d', certfile, 1 + #certs)
+		end
+		table.insert(certs, cert)
+	end
+	f:close()
+
+	return certs, key
+end
+
+
+-- @function Prefer HTTP/2 or HTTP/1.1
+local function alpnselect(_, protos)
+	for _, proto in ipairs(protos) do
+		if proto == 'h2' or proto == 'http/1.1' then
+			return proto
+		end
+	end
+	return nil
+end
+
+local warned_old_luaossl = false
+
+-- @function Return a new TLS context for a server.
+function tls_cert.new_tls_context(certs, key)
+	local ctx = require('http.tls').new_server_context()
+	if ctx.setAlpnSelect then
+		ctx:setAlpnSelect(alpnselect)
+	end
+	assert(ctx:setPrivateKey(key))
+	assert(ctx:setCertificate(certs[1]))
+
+	-- Set up certificate chain to be sent, if required and possible.
+	if #certs == 1 then return ctx end
+	if ctx.setCertificateChain then
+		local chain = require('openssl.x509.chain').new()
+		assert(chain)
+		for i = 2, #certs do
+			chain:add(certs[i])
+			assert(chain)
+		end
+		assert(ctx:setCertificateChain(chain))
+	elseif not warned_old_luaossl then
+		-- old luaossl version -> only final cert sent to clients
+		log_warn(ffi.C.LOG_GRP_HTTP,
+			'need luaossl >= 20181207 to support sending intermediary certificate to clients')
+		warned_old_luaossl = true
+	end
+	return ctx
+end
+
+
+return tls_cert
+