Provide inbucket object in Lua (#351)

* fix delve fortify thingy
* Expose inbucket.after.message_stored in lua
* Expose inbucket.after.message_deleted in lua
* Expose inbucket.before.mail_accepted in lua

pkg/extension/luahost/bind_inbucket.go

@@ -0,0 +1,218 @@
+package luahost
+
+import (
+	"errors"
+	"fmt"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+const (
+	inbucketName       = "inbucket"
+	inbucketBeforeName = "inbucket_before"
+	inbucketAfterName  = "inbucket_after"
+)
+
+// Inbucket is the primary Lua interface data structure.
+type Inbucket struct {
+	After  InbucketAfterFuncs
+	Before InbucketBeforeFuncs
+}
+
+// InbucketAfterFuncs holds references to Lua extension functions to be called async
+// after Inbucket handles an event.
+type InbucketAfterFuncs struct {
+	MessageDeleted *lua.LFunction
+	MessageStored  *lua.LFunction
+}
+
+// InbucketBeforeFuncs holds references to Lua extension functions to be called
+// before Inbucket handles an event.
+type InbucketBeforeFuncs struct {
+	MailAccepted *lua.LFunction
+}
+
+func registerInbucketTypes(ls *lua.LState) {
+	// inbucket type.
+	mt := ls.NewTypeMetatable(inbucketName)
+	ls.SetField(mt, "__index", ls.NewFunction(inbucketIndex))
+
+	// inbucket global var.
+	ud := wrapInbucket(ls, &Inbucket{})
+	ls.SetGlobal(inbucketName, ud)
+
+	// inbucket.after type.
+	mt = ls.NewTypeMetatable(inbucketAfterName)
+	ls.SetField(mt, "__index", ls.NewFunction(inbucketAfterIndex))
+	ls.SetField(mt, "__newindex", ls.NewFunction(inbucketAfterNewIndex))
+
+	// inbucket.before type.
+	mt = ls.NewTypeMetatable(inbucketBeforeName)
+	ls.SetField(mt, "__index", ls.NewFunction(inbucketBeforeIndex))
+	ls.SetField(mt, "__newindex", ls.NewFunction(inbucketBeforeNewIndex))
+}
+
+func wrapInbucket(ls *lua.LState, val *Inbucket) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(inbucketName))
+
+	return ud
+}
+
+func wrapInbucketAfter(ls *lua.LState, val *InbucketAfterFuncs) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(inbucketAfterName))
+
+	return ud
+}
+
+func wrapInbucketBefore(ls *lua.LState, val *InbucketBeforeFuncs) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(inbucketBeforeName))
+
+	return ud
+}
+
+func getInbucket(ls *lua.LState) (*Inbucket, error) {
+	lv := ls.GetGlobal(inbucketName)
+	if lv == nil {
+		return nil, errors.New("inbucket object was nil")
+	}
+
+	ud, ok := lv.(*lua.LUserData)
+	if !ok {
+		return nil, fmt.Errorf("inbucket object was type %s instead of UserData", lv.Type())
+	}
+
+	val, ok := ud.Value.(*Inbucket)
+	if !ok {
+		return nil, fmt.Errorf("inbucket object (%v) could not be cast", ud.Value)
+	}
+
+	return val, nil
+}
+
+func checkInbucket(ls *lua.LState, pos int) *Inbucket {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*Inbucket); ok {
+		return val
+	}
+	ls.ArgError(1, inbucketName+" expected")
+	return nil
+}
+
+func checkInbucketAfter(ls *lua.LState, pos int) *InbucketAfterFuncs {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*InbucketAfterFuncs); ok {
+		return val
+	}
+	ls.ArgError(1, inbucketAfterName+" expected")
+	return nil
+}
+
+func checkInbucketBefore(ls *lua.LState, pos int) *InbucketBeforeFuncs {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*InbucketBeforeFuncs); ok {
+		return val
+	}
+	ls.ArgError(1, inbucketBeforeName+" expected")
+	return nil
+}
+
+// inbucket getter.
+func inbucketIndex(ls *lua.LState) int {
+	ib := checkInbucket(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "after":
+		ls.Push(wrapInbucketAfter(ls, &ib.After))
+	case "before":
+		ls.Push(wrapInbucketBefore(ls, &ib.Before))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// inbucket.after getter.
+func inbucketAfterIndex(ls *lua.LState) int {
+	after := checkInbucketAfter(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "message_deleted":
+		ls.Push(funcOrNil(after.MessageDeleted))
+	case "message_stored":
+		ls.Push(funcOrNil(after.MessageStored))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// inbucket.after setter.
+func inbucketAfterNewIndex(ls *lua.LState) int {
+	m := checkInbucketAfter(ls, 1)
+	index := ls.CheckString(2)
+
+	switch index {
+	case "message_deleted":
+		m.MessageDeleted = ls.CheckFunction(3)
+	case "message_stored":
+		m.MessageStored = ls.CheckFunction(3)
+	default:
+		ls.RaiseError("invalid inbucket.after index %q", index)
+	}
+
+	return 0
+}
+
+// inbucket.before getter.
+func inbucketBeforeIndex(ls *lua.LState) int {
+	before := checkInbucketBefore(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "mail_accepted":
+		ls.Push(funcOrNil(before.MailAccepted))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// inbucket.before setter.
+func inbucketBeforeNewIndex(ls *lua.LState) int {
+	m := checkInbucketBefore(ls, 1)
+	index := ls.CheckString(2)
+
+	switch index {
+	case "mail_accepted":
+		m.MailAccepted = ls.CheckFunction(3)
+	default:
+		ls.RaiseError("invalid inbucket.before index %q", index)
+	}
+
+	return 0
+}
+
+func funcOrNil(f *lua.LFunction) lua.LValue {
+	if f == nil {
+		return lua.LNil
+	}
+
+	return f
+}

pkg/extension/luahost/bind_inbucket_test.go

@@ -0,0 +1,102 @@
+package luahost
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+)
+
+func TestInbucketAfterFuncs(t *testing.T) {
+	// This Script registers each function and calls it.  No effort is made to use the arguments
+	// that Inbucket expects, this is only to validate the inbucket.after data structure getters
+	// and setters.
+	script := `
+		assert(inbucket, "inbucket should not be nil")
+		assert(inbucket.after, "inbucket.after should not be nil")
+
+		local fns = { "message_deleted", "message_stored" }
+
+		-- Verify functions start off nil.
+		for i, name in ipairs(fns) do
+			assert(inbucket.after[name] == nil, "after." .. name .. " should be nil")
+		end
+
+		-- Test function to track func calls made, ensures no crossed wires.
+		local calls = {}
+		function makeTestFunc(create_name)
+			return function(call_name)
+				calls[create_name] = call_name
+			end
+		end
+
+		-- Set after functions, verify not nil, and call them.
+		for i, name in ipairs(fns) do
+			inbucket.after[name] = makeTestFunc(name)
+			assert(inbucket.after[name], "after." .. name .. " should not be nil")
+		end
+
+		-- Call each function.  Separate loop to verify final state in 'calls'.
+		for i, name in ipairs(fns) do
+			inbucket.after[name](name)
+		end
+
+		-- Verify functions were called.
+		for i, name in ipairs(fns) do
+			assert(calls[name], "after." .. name .. " should have been called")
+			assert(calls[name] == name,
+				string.format("after.%s was called with incorrect argument %s", name, calls[name]))
+		end
+	`
+
+	ls := lua.NewState()
+	registerInbucketTypes(ls)
+	require.NoError(t, ls.DoString(script))
+}
+
+func TestInbucketBeforeFuncs(t *testing.T) {
+	// This Script registers each function and calls it.  No effort is made to use the arguments
+	// that Inbucket expects, this is only to validate the inbucket.before data structure getters
+	// and setters.
+	script := `
+		assert(inbucket, "inbucket should not be nil")
+		assert(inbucket.before, "inbucket.before should not be nil")
+
+		local fns = { "mail_accepted" }
+
+		-- Verify functions start off nil.
+		for i, name in ipairs(fns) do
+			assert(inbucket.before[name] == nil, "before." .. name .. " should be nil")
+		end
+
+		-- Test function to track func calls made, ensures no crossed wires.
+		local calls = {}
+		function makeTestFunc(create_name)
+			return function(call_name)
+				calls[create_name] = call_name
+			end
+		end
+
+		-- Set before functions, verify not nil, and call them.
+		for i, name in ipairs(fns) do
+			inbucket.before[name] = makeTestFunc(name)
+			assert(inbucket.before[name], "before." .. name .. " should not be nil")
+		end
+
+		-- Call each function.  Separate loop to verify final state in 'calls'.
+		for i, name in ipairs(fns) do
+			inbucket.before[name](name)
+		end
+
+		-- Verify functions were called.
+		for i, name in ipairs(fns) do
+			assert(calls[name], "before." .. name .. " should have been called")
+			assert(calls[name] == name,
+				string.format("before.%s was called with incorrect argument %s", name, calls[name]))
+		end
+	`
+
+	ls := lua.NewState()
+	registerInbucketTypes(ls)
+	require.NoError(t, ls.DoString(script))
+}

pkg/extension/luahost/lua.go

@@ -17,7 +17,6 @@ import (
 
 // Host of Lua extensions.
 type Host struct {
-	Functions  []string // Functions detected in lua script.
 	extHost    *extension.Host
 	pool       *statePool
 	logContext zerolog.Context
@@ -88,45 +87,29 @@ func (h *Host) CreateChannel(name string) chan lua.LValue {
 	return h.pool.createChannel(name)
 }
 
-const afterMessageDeletedFnName string = "after_message_deleted"
-const afterMessageStoredFnName string = "after_message_stored"
-const beforeMailAcceptedFnName string = "before_mail_accepted"
-
 // Detects global lua event listener functions and wires them up.
 func (h *Host) wireFunctions(logger zerolog.Logger, ls *lua.LState) {
-	detectFn := func(name string) bool {
-		lval := ls.GetGlobal(name)
-		switch lval.Type() {
-		case lua.LTFunction:
-			logger.Debug().Msgf("Detected %q function", name)
-			h.Functions = append(h.Functions, name)
-			return true
-		case lua.LTNil:
-			logger.Debug().Msgf("Did not detect %q function", name)
-		default:
-			logger.Fatal().Msgf("Found global named %q, but was a %v instead of a function",
-				name, lval.Type().String())
-		}
-
-		return false
+	ib, err := getInbucket(ls)
+	if err != nil {
+		logger.Fatal().Err(err).Msg("Failed to get inbucket global")
 	}
 
 	events := h.extHost.Events
 	const listenerName string = "lua"
 
-	if detectFn(afterMessageDeletedFnName) {
+	if ib.After.MessageDeleted != nil {
 		events.AfterMessageDeleted.AddListener(listenerName, h.handleAfterMessageDeleted)
 	}
-	if detectFn(afterMessageStoredFnName) {
+	if ib.After.MessageStored != nil {
 		events.AfterMessageStored.AddListener(listenerName, h.handleAfterMessageStored)
 	}
-	if detectFn(beforeMailAcceptedFnName) {
+	if ib.Before.MailAccepted != nil {
 		events.BeforeMailAccepted.AddListener(listenerName, h.handleBeforeMailAccepted)
 	}
 }
 
 func (h *Host) handleAfterMessageDeleted(msg event.MessageMetadata) {
-	logger, ls, lfunc, ok := h.prepareFuncCall(afterMessageDeletedFnName)
+	logger, ls, ib, ok := h.prepareInbucketFuncCall("after.message_deleted")
 	if !ok {
 		return
 	}
@@ -135,7 +118,7 @@ func (h *Host) handleAfterMessageDeleted(msg event.MessageMetadata) {
 	// Call lua function.
 	logger.Debug().Msgf("Calling Lua function with %+v", msg)
 	if err := ls.CallByParam(
-		lua.P{Fn: lfunc, NRet: 0, Protect: true},
+		lua.P{Fn: ib.After.MessageDeleted, NRet: 0, Protect: true},
 		wrapMessageMetadata(ls, &msg),
 	); err != nil {
 		logger.Error().Err(err).Msg("Failed to call Lua function")
@@ -143,7 +126,7 @@ func (h *Host) handleAfterMessageDeleted(msg event.MessageMetadata) {
 }
 
 func (h *Host) handleAfterMessageStored(msg event.MessageMetadata) {
-	logger, ls, lfunc, ok := h.prepareFuncCall(afterMessageStoredFnName)
+	logger, ls, ib, ok := h.prepareInbucketFuncCall("after.message_stored")
 	if !ok {
 		return
 	}
@@ -152,7 +135,7 @@ func (h *Host) handleAfterMessageStored(msg event.MessageMetadata) {
 	// Call lua function.
 	logger.Debug().Msgf("Calling Lua function with %+v", msg)
 	if err := ls.CallByParam(
-		lua.P{Fn: lfunc, NRet: 0, Protect: true},
+		lua.P{Fn: ib.After.MessageStored, NRet: 0, Protect: true},
 		wrapMessageMetadata(ls, &msg),
 	); err != nil {
 		logger.Error().Err(err).Msg("Failed to call Lua function")
@@ -160,7 +143,7 @@ func (h *Host) handleAfterMessageStored(msg event.MessageMetadata) {
 }
 
 func (h *Host) handleBeforeMailAccepted(addr event.AddressParts) *bool {
-	logger, ls, lfunc, ok := h.prepareFuncCall(beforeMailAcceptedFnName)
+	logger, ls, ib, ok := h.prepareInbucketFuncCall("after.message_stored")
 	if !ok {
 		return nil
 	}
@@ -168,7 +151,7 @@ func (h *Host) handleBeforeMailAccepted(addr event.AddressParts) *bool {
 
 	logger.Debug().Msgf("Calling Lua function with %+v", addr)
 	if err := ls.CallByParam(
-		lua.P{Fn: lfunc, NRet: 1, Protect: true},
+		lua.P{Fn: ib.Before.MailAccepted, NRet: 1, Protect: true},
 		lua.LString(addr.Local),
 		lua.LString(addr.Domain),
 	); err != nil {
@@ -193,7 +176,7 @@ func (h *Host) handleBeforeMailAccepted(addr event.AddressParts) *bool {
 }
 
 // Common preparation for calling Lua functions.
-func (h *Host) prepareFuncCall(funcName string) (logger zerolog.Logger, ls *lua.LState, lfunc lua.LValue, ok bool) {
+func (h *Host) prepareInbucketFuncCall(funcName string) (logger zerolog.Logger, ls *lua.LState, ib *Inbucket, ok bool) {
 	logger = h.logContext.Str("event", funcName).Logger()
 
 	ls, err := h.pool.getState()
@@ -202,11 +185,11 @@ func (h *Host) prepareFuncCall(funcName string) (logger zerolog.Logger, ls *lua.
 		return logger, nil, nil, false
 	}
 
-	lfunc = ls.GetGlobal(funcName)
-	if lfunc.Type() != lua.LTFunction {
-		logger.Error().Msgf("global %q is no longer a function", funcName)
+	ib, err = getInbucket(ls)
+	if err != nil {
+		logger.Error().Err(err).Msg("Failed to obtain Lua inbucket object")
 		return logger, nil, nil, false
 	}
 
-	return logger, ls, lfunc, true
+	return logger, ls, ib, true
 }

pkg/extension/luahost/lua_test.go

@@ -65,7 +65,7 @@ func TestAfterMessageDeleted(t *testing.T) {
 	script := `
 		async = true
 
-		function after_message_deleted(msg)
+		function inbucket.after.message_deleted(msg)
 			-- Full message bindings tested elsewhere.
 			assert_eq(msg.mailbox, "mb1")
 			assert_eq(msg.id, "id1")
@@ -96,7 +96,7 @@ func TestAfterMessageStored(t *testing.T) {
 	script := `
 		async = true
 
-		function after_message_stored(msg)
+		function inbucket.after.message_stored(msg)
 			-- Full message bindings tested elsewhere.
 			assert_eq(msg.mailbox, "mb1")
 			assert_eq(msg.id, "id1")
@@ -125,7 +125,7 @@ func TestAfterMessageStored(t *testing.T) {
 func TestBeforeMailAccepted(t *testing.T) {
 	// Register lua event listener.
 	script := `
-		function before_mail_accepted(localpart, domain)
+		function inbucket.before.mail_accepted(localpart, domain)
 			return localpart == "from" and domain == "test"
 		end
 	`

pkg/extension/luahost/pool.go

@@ -37,6 +37,7 @@ func (lp *statePool) newState() (*lua.LState, error) {
 	}
 
 	// Register custom types.
+	registerInbucketTypes(ls)
 	registerMessageMetadataType(ls)
 	registerMailAddressType(ls)
 	registerPolicyType(ls)

shell.nix

@@ -32,4 +32,7 @@ pkgs.mkShell {
 
     scripts.qt
   ];
+
+  # Prevents launch errors with delve debugger.
+  hardeningDisable = [ "fortify" ];
 }