--- a/core/certmanager.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/core/certmanager.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -9,7 +9,6 @@
 local ssl = require "ssl";
 local configmanager = require "core.configmanager";
 local log = require "util.logger".init("certmanager");
-local ssl_context = ssl.context or require "ssl.context";
 local ssl_newcontext = ssl.newcontext;
 local new_config = require"util.sslconfig".new;
 local stat = require "lfs".attributes;
@@ -313,10 +312,6 @@
 	core_defaults.curveslist = nil;
 end
 
-local path_options = { -- These we pass through resolve_path()
-	key = true, certificate = true, cafile = true, capath = true, dhparam = true
-}
-
 local function create_context(host, mode, ...)
 	local cfg = new_config();
 	cfg:apply(core_defaults);
@@ -352,34 +347,7 @@
 		if user_ssl_config.certificate and not user_ssl_config.key then return nil, "No key present in SSL/TLS configuration for "..host; end
 	end
 
-	for option in pairs(path_options) do
-		if type(user_ssl_config[option]) == "string" then
-			user_ssl_config[option] = resolve_path(config_path, user_ssl_config[option]);
-		else
-			user_ssl_config[option] = nil;
-		end
-	end
-
-	-- LuaSec expects dhparam to be a callback that takes two arguments.
-	-- We ignore those because it is mostly used for having a separate
-	-- set of params for EXPORT ciphers, which we don't have by default.
-	if type(user_ssl_config.dhparam) == "string" then
-		local f, err = io_open(user_ssl_config.dhparam);
-		if not f then return nil, "Could not open DH parameters: "..err end
-		local dhparam = f:read("*a");
-		f:close();
-		user_ssl_config.dhparam = function() return dhparam; end
-	end
-
-	local ctx, err = ssl_newcontext(user_ssl_config);
-
-	-- COMPAT Older LuaSec ignores the cipher list from the config, so we have to take care
-	-- of it ourselves (W/A for #x)
-	if ctx and user_ssl_config.ciphers then
-		local success;
-		success, err = ssl_context.setcipher(ctx, user_ssl_config.ciphers);
-		if not success then ctx = nil; end
-	end
+	local ctx, err = cfg:build();
 
 	if not ctx then
 		err = err or "invalid ssl config"

--- a/core/portmanager.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/core/portmanager.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -240,21 +240,22 @@
 	log("debug", "Gathering certificates for SNI for host %s, %s service", host, service or "default");
 	for name, interface, port, n, active_service --luacheck: ignore 213
 		in active_services:iter(service, nil, nil, nil) do
-		if active_service.server.hosts and active_service.tls_cfg then
-			local config_prefix = (active_service.config_prefix or name).."_";
-			if config_prefix == "_" then config_prefix = ""; end
-			local prefix_ssl_config = config.get(host, config_prefix.."ssl");
+		if active_service.server and active_service.tls_cfg then
 			local alternate_host = name and config.get(host, name.."_host");
 			if not alternate_host and name == "https" then
 				-- TODO should this be some generic thing? e.g. in the service definition
 				alternate_host = config.get(host, "http_host");
 			end
 			local autocert = certmanager.find_host_cert(alternate_host or host);
-			-- luacheck: ignore 211/cfg
-			local ssl, err, cfg = certmanager.create_context(host, "server", prefix_ssl_config, autocert, active_service.tls_cfg);
-			if ssl then
-				active_service.server.hosts[alternate_host or host] = ssl;
-			else
+			local manualcert = active_service.tls_cfg;
+			local certificate = (autocert and autocert.certificate) or manualcert.certificate;
+			local key = (autocert and autocert.key) or manualcert.key;
+			local ok, err = active_service.server:sslctx():set_sni_host(
+				host,
+				certificate,
+				key
+			);
+			if not ok then
 				log("error", "Error creating TLS context for SNI host %s: %s", host, err);
 			end
 		end
@@ -277,7 +278,7 @@
 	for name, interface, port, n, active_service --luacheck: ignore 213
 		in active_services:iter(nil, nil, nil, nil) do
 		if active_service.tls_cfg then
-			active_service.server.hosts[host] = nil;
+			active_service.server:sslctx():remove_sni_host(host)
 		end
 	end
 end);

--- a/net/server_epoll.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/net/server_epoll.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -18,7 +18,6 @@
 local logger = require "util.logger";
 local log = logger.init("server_epoll");
 local socket = require "socket";
-local luasec = require "ssl";
 local realtime = require "util.time".now;
 local monotonic = require "util.time".monotonic;
 local indexedbheap = require "util.indexedbheap";
@@ -614,6 +613,30 @@
 	self._sslctx = sslctx;
 end
 
+function interface:sslctx()
+	return self.tls_ctx
+end
+
+function interface:ssl_info()
+	local sock = self.conn;
+	return sock.info and sock:info();
+end
+
+function interface:ssl_peercertificate()
+	local sock = self.conn;
+	return sock.getpeercertificate and sock:getpeercertificate();
+end
+
+function interface:ssl_peerverification()
+	local sock = self.conn;
+	return sock.getpeerverification and sock:getpeerverification();
+end
+
+function interface:ssl_peerfinished()
+	local sock = self.conn;
+	return sock.getpeerfinished and sock:getpeerfinished();
+end
+
 function interface:starttls(tls_ctx)
 	if tls_ctx then self.tls_ctx = tls_ctx; end
 	self.starttls = false;
@@ -641,11 +664,7 @@
 	self.starttls = false;
 	self:debug("Starting TLS now");
 	self:updatenames(); -- Can't getpeer/sockname after wrap()
-	local ok, conn, err = pcall(luasec.wrap, self.conn, self.tls_ctx);
-	if not ok then
-		conn, err = ok, conn;
-		self:debug("Failed to initialize TLS: %s", err);
-	end
+	local conn, err = self.tls_ctx:wrap(self.conn);
 	if not conn then
 		self:on("disconnect", err);
 		self:destroy();
@@ -656,8 +675,8 @@
 	if conn.sni then
 		if self.servername then
 			conn:sni(self.servername);
-		elseif self._server and type(self._server.hosts) == "table" and next(self._server.hosts) ~= nil then
-			conn:sni(self._server.hosts, true);
+		elseif next(self.tls_ctx._sni_contexts) ~= nil then
+			conn:sni(self.tls_ctx._sni_contexts, true);
 		end
 	end
 	if self.extra and self.extra.tlsa and conn.settlsa then

--- a/net/server_event.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/net/server_event.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -47,7 +47,7 @@
 local coroutine_wrap = coroutine.wrap
 local coroutine_yield = coroutine.yield
 
-local has_luasec, ssl = pcall ( require , "ssl" )
+local has_luasec = pcall ( require , "ssl" )
 local socket = require "socket"
 local levent = require "luaevent.core"
 local inet = require "util.net";
@@ -153,7 +153,7 @@
 	_ = self.eventwrite and self.eventwrite:close( )
 	self.eventread, self.eventwrite = nil, nil
 	local err
-	self.conn, err = ssl.wrap( self.conn, self._sslctx )
+	self.conn, err = self._sslctx:wrap(self.conn)
 	if err then
 		self.fatalerror = err
 		self.conn = nil  -- cannot be used anymore
@@ -168,8 +168,8 @@
 	if self.conn.sni then
 		if self.servername then
 			self.conn:sni(self.servername);
-		elseif self._server and type(self._server.hosts) == "table" and next(self._server.hosts) ~= nil then
-			self.conn:sni(self._server.hosts, true);
+		elseif next(self._sslctx._sni_contexts) ~= nil then
+			self.conn:sni(self._sslctx._sni_contexts, true);
 		end
 	end
 
@@ -274,6 +274,26 @@
 	return self:_lock(self.nointerface, true, self.nowriting);
 end
 
+function interface_mt:sslctx()
+	return self._sslctx
+end
+
+function interface_mt:ssl_info()
+	return self.conn.info and self.conn:info()
+end
+
+function interface_mt:ssl_peercertificate()
+	return self.conn.getpeercertificate and self.conn:getpeercertificate()
+end
+
+function interface_mt:ssl_peerverification()
+	return self.conn.getpeerverification and self.conn:getpeerverification()
+end
+
+function interface_mt:ssl_peerfinished()
+	return self.conn.getpeerfinished and self.conn:getpeerfinished()
+end
+
 function interface_mt:resume()
 	self:_lock(self.nointerface, false, self.nowriting);
 	if self.readcallback and not self.eventread then

--- a/net/server_select.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/net/server_select.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -359,6 +359,18 @@
 	handler.sslctx = function ( )
 		return sslctx
 	end
+	handler.ssl_info = function( )
+		return socket.info and socket:info()
+	end
+	handler.ssl_peercertificate = function( )
+		return socket.getpeercertificate and socket:getpeercertificate()
+	end
+	handler.ssl_peerverification = function( )
+		return socket.getpeerverification and socket:getpeerverification()
+	end
+	handler.ssl_peerfinished = function( )
+		return socket.getpeerfinished and socket:getpeerfinished()
+	end
 	handler.send = function( _, data, i, j )
 		return send( socket, data, i, j )
 	end
@@ -652,7 +664,7 @@
 			end
 			out_put( "server.lua: attempting to start tls on " .. tostring( socket ) )
 			local oldsocket, err = socket
-			socket, err = ssl_wrap( socket, sslctx )	-- wrap socket
+			socket, err = sslctx:wrap(socket)	-- wrap socket
 
 			if not socket then
 				out_put( "server.lua: error while starting tls on client: ", tostring(err or "unknown error") )
@@ -662,8 +674,8 @@
 			if socket.sni then
 				if self.servername then
 					socket:sni(self.servername);
-				elseif self._server and type(self._server.hosts) == "table" and next(self._server.hosts) ~= nil then
-					socket:sni(self.server().hosts, true);
+				elseif next(sslctx._sni_contexts) ~= nil then
+					socket:sni(sslctx._sni_contexts, true);
 				end
 			end
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/net/tls_luasec.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -0,0 +1,90 @@
+-- Prosody IM
+-- Copyright (C) 2021 Prosody folks
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+
+--[[
+This file provides a shim abstraction over LuaSec, consolidating some code
+which was previously spread between net.server backends, portmanager and
+certmanager.
+
+The goal is to provide a more or less well-defined API on top of LuaSec which
+abstracts away some of the things which are not needed and simplifies usage of
+commonly used things (such as SNI contexts). Eventually, network backends
+which do not rely on LuaSocket+LuaSec should be able to provide *this* API
+instead of having to mimic LuaSec.
+]]
+local softreq = require"util.dependencies".softreq;
+local ssl = softreq"ssl";
+local ssl_newcontext = ssl.newcontext;
+local ssl_context = ssl.context or softreq"ssl.context";
+local io_open = io.open;
+
+local context_api = {};
+local context_mt = {__index = context_api};
+
+function context_api:set_sni_host(host, cert, key)
+	local ctx, err = self._builder:clone():apply({
+		certificate = cert,
+		key = key,
+	}):build();
+	if not ctx then
+		return false, err
+	end
+
+	self._sni_contexts[host] = ctx._inner
+
+	return true, nil
+end
+
+function context_api:remove_sni_host(host)
+	self._sni_contexts[host] = nil
+end
+
+function context_api:wrap(sock)
+	local ok, conn, err = pcall(ssl.wrap, sock, self._inner);
+	if not ok then
+		return nil, err
+	end
+	return conn, nil
+end
+
+local function new_context(cfg, builder)
+	-- LuaSec expects dhparam to be a callback that takes two arguments.
+	-- We ignore those because it is mostly used for having a separate
+	-- set of params for EXPORT ciphers, which we don't have by default.
+	if type(cfg.dhparam) == "string" then
+		local f, err = io_open(cfg.dhparam);
+		if not f then return nil, "Could not open DH parameters: "..err end
+		local dhparam = f:read("*a");
+		f:close();
+		cfg.dhparam = function() return dhparam; end
+	end
+
+	local inner, err = ssl_newcontext(cfg);
+	if not inner then
+		return nil, err
+	end
+
+	-- COMPAT Older LuaSec ignores the cipher list from the config, so we have to take care
+	-- of it ourselves (W/A for #x)
+	if inner and cfg.ciphers then
+		local success;
+		success, err = ssl_context.setcipher(inner, cfg.ciphers);
+		if not success then
+			return nil, err
+		end
+	end
+
+	return setmetatable({
+		_inner = inner,
+		_builder = builder,
+		_sni_contexts = {},
+	}, context_mt), nil
+end
+
+return {
+	new_context = new_context,
+};

--- a/plugins/mod_admin_shell.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/plugins/mod_admin_shell.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -807,9 +807,7 @@
 		mapper = function(conn, session)
 			if not session.secure then return "insecure"; end
 			if not conn or not conn:ssl() then return "secure" end
-			local sock = conn and conn:socket();
-			if not sock then return "secure"; end
-			local tls_info = sock.info and sock:info();
+			local tls_info = conn.ssl_info and conn:ssl_info();
 			return tls_info and tls_info.protocol or "secure";
 		end;
 	};
@@ -819,8 +817,7 @@
 		width = 30;
 		key = "conn";
 		mapper = function(conn)
-			local sock = conn:socket();
-			local info = sock and sock.info and sock:info();
+			local info = conn and conn.ssl_info and conn:ssl_info();
 			if info then return info.cipher end
 		end;
 	};

--- a/plugins/mod_c2s.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/plugins/mod_c2s.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -117,8 +117,7 @@
 		session.secure = true;
 		session.encrypted = true;
 
-		local sock = session.conn:socket();
-		local info = sock.info and sock:info();
+		local info = session.conn:ssl_info();
 		if type(info) == "table" then
 			(session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);
 			session.compressed = info.compression;
@@ -295,8 +294,7 @@
 		session.encrypted = true;
 
 		-- Check if TLS compression is used
-		local sock = conn:socket();
-		local info = sock.info and sock:info();
+		local info = conn:ssl_info();
 		if type(info) == "table" then
 			(session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);
 			session.compressed = info.compression;

--- a/plugins/mod_s2s.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/plugins/mod_s2s.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -383,10 +383,10 @@
 --- Helper to check that a session peer's certificate is valid
 local function check_cert_status(session)
 	local host = session.direction == "outgoing" and session.to_host or session.from_host
-	local conn = session.conn:socket()
+	local conn = session.conn
 	local cert
-	if conn.getpeercertificate then
-		cert = conn:getpeercertificate()
+	if conn.ssl_peercertificate then
+		cert = conn:ssl_peercertificate()
 	end
 
 	return module:fire_event("s2s-check-certificate", { host = host, session = session, cert = cert });
@@ -398,8 +398,7 @@
 	session.secure = true;
 	session.encrypted = true;
 
-	local sock = session.conn:socket();
-	local info = sock.info and sock:info();
+	local info = session.conn:ssl_info();
 	if type(info) == "table" then
 		(session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);
 		session.compressed = info.compression;

--- a/plugins/mod_s2s_auth_certs.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/plugins/mod_s2s_auth_certs.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -9,7 +9,7 @@
 
 module:hook("s2s-check-certificate", function(event)
 	local session, host, cert = event.session, event.host, event.cert;
-	local conn = session.conn:socket();
+	local conn = session.conn;
 	local log = session.log or log;
 
 	if not cert then
@@ -18,8 +18,8 @@
 	end
 
 	local chain_valid, errors;
-	if conn.getpeerverification then
-		chain_valid, errors = conn:getpeerverification();
+	if conn.ssl_peerverification then
+		chain_valid, errors = conn:ssl_peerverification();
 	else
 		chain_valid, errors = false, { { "Chain verification not supported by this version of LuaSec" } };
 	end

--- a/plugins/mod_saslauth.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/plugins/mod_saslauth.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -242,7 +242,7 @@
 end);
 
 local function tls_unique(self)
-	return self.userdata["tls-unique"]:getpeerfinished();
+	return self.userdata["tls-unique"]:ssl_peerfinished();
 end
 
 local mechanisms_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-sasl' };
@@ -262,18 +262,17 @@
 			-- check whether LuaSec has the nifty binding to the function needed for tls-unique
 			-- FIXME: would be nice to have this check only once and not for every socket
 			if sasl_handler.add_cb_handler then
-				local socket = origin.conn:socket();
-				local info = socket.info and socket:info();
-				if info.protocol == "TLSv1.3" then
+				local info = origin.conn:ssl_info();
+				if info and info.protocol == "TLSv1.3" then
 					log("debug", "Channel binding 'tls-unique' undefined in context of TLS 1.3");
-				elseif socket.getpeerfinished and socket:getpeerfinished() then
+				elseif origin.conn.ssl_peerfinished and origin.conn:ssl_peerfinished() then
 					log("debug", "Channel binding 'tls-unique' supported");
 					sasl_handler:add_cb_handler("tls-unique", tls_unique);
 				else
 					log("debug", "Channel binding 'tls-unique' not supported (by LuaSec?)");
 				end
 				sasl_handler["userdata"] = {
-					["tls-unique"] = socket;
+					["tls-unique"] = origin.conn;
 				};
 			else
 				log("debug", "Channel binding not supported by SASL handler");

--- a/util/sslconfig.lua	Mon Apr 25 16:35:10 2022 +0100
+++ b/util/sslconfig.lua	Wed Apr 27 17:44:14 2022 +0200
@@ -3,9 +3,16 @@
 local type = type;
 local pairs = pairs;
 local rawset = rawset;
+local rawget = rawget;
+local error = error;
 local t_concat = table.concat;
 local t_insert = table.insert;
 local setmetatable = setmetatable;
+local config_path = prosody.paths.config or ".";
+local resolve_path = require"util.paths".resolve_relative_path;
+
+-- TODO: use net.server directly here
+local tls_impl  = require"net.tls_luasec";
 
 local _ENV = nil;
 -- luacheck: std none
@@ -34,7 +41,7 @@
 			options[value] = true;
 		end
 	end
-	config[field] = options;
+	rawset(config, field, options)
 end
 
 handlers.verifyext = handlers.options;
@@ -70,6 +77,20 @@
 -- TLS 1.3 ciphers
 finalisers.ciphersuites = finalisers.ciphers;
 
+-- Path expansion
+function finalisers.key(path)
+	if type(path) == "string" then
+		return resolve_path(config_path, path);
+	else
+		return nil
+	end
+end
+finalisers.certificate = finalisers.key;
+finalisers.cafile = finalisers.key;
+finalisers.capath = finalisers.key;
+-- XXX: copied from core/certmanager.lua, but this seems odd, because it would remove a dhparam function from the config
+finalisers.dhparam = finalisers.key;
+
 -- protocol = "x" should enable only that protocol
 -- protocol = "x+" should enable x and later versions
 
@@ -89,11 +110,14 @@
 
 -- Merge options from 'new' config into 'config'
 local function apply(config, new)
+	-- 0 == cache
+	rawset(config, 0, nil);
 	if type(new) == "table" then
 		for field, value in pairs(new) do
 			(handlers[field] or rawset)(config, field, value);
 		end
 	end
+	return config
 end
 
 -- Finalize the config into the form LuaSec expects
@@ -107,17 +131,45 @@
 	return output;
 end
 
+local function build(config)
+	local cached = rawget(config, 0);
+	if cached then
+		return cached, nil
+	end
+
+	local ctx, err = tls_impl.new_context(config:final(), config);
+	if ctx then
+		rawset(config, 0, ctx);
+	end
+	return ctx, err
+end
+
 local sslopts_mt = {
 	__index = {
 		apply = apply;
 		final = final;
+		build = build;
 	};
+	__newindex = function()
+		error("SSL config objects cannot be modified directly. Use :apply()")
+	end;
 };
 
+
 local function new()
 	return setmetatable({options={}}, sslopts_mt);
 end
 
+local function clone(config)
+	local result = new();
+	for k, v in pairs(config) do
+		rawset(result, k, v);
+	end
+	return result
+end
+
+sslopts_mt.__index.clone = clone;
+
 return {
 	apply = apply;
 	final = final;