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script.go
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script.go
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// Package script provides lua scripting for skipper
package script
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"net/http"
"net/url"
"os"
"strings"
log "github.com/sirupsen/logrus"
lua "github.com/yuin/gopher-lua"
lua_parse "github.com/yuin/gopher-lua/parse"
"github.com/zalando/skipper/filters"
"github.com/zalando/skipper/script/base64"
"github.com/cjoudrey/gluahttp"
"github.com/cjoudrey/gluaurl"
gjson "layeh.com/gopher-json"
)
var (
// InitialPoolSize is the number of lua states created initially per route
InitialPoolSize int = 3
// MaxPoolSize is the number of lua states stored per route - there may be more parallel
// requests, but only this number is cached.
MaxPoolSize int = 10
errLuaSourcesDisabled = errors.New("lua Sources are disabled")
)
type LuaOptions struct {
// Modules configures enabled standard and additional (preloaded) Lua modules.
// For standard Lua modules (see https://www.lua.org/manual/5.1/manual.html)
// use "<module>.<symbol>" (e.g. "base.print") to selectively enable module symbols.
// Additional modules are preloaded with all symbols.
// Empty value enables all modules.
Modules []string
// Sources that are allowed as input sources. Valid sources
// are "none", "file" and "inline". Empty slice will enable
// both as default. To disable the use of lua filters use
// "none".
Sources []string
}
type luaScript struct {
modules []string
sources []string
}
// NewLuaScript creates a new filter spec
func NewLuaScript() filters.Spec {
spec, _ := NewLuaScriptWithOptions(LuaOptions{})
return spec
}
// NewLuaScriptWithOptions creates a new filter spec with options
func NewLuaScriptWithOptions(opts LuaOptions) (filters.Spec, error) {
sources := opts.Sources
if len(sources) == 0 {
// backwards compatible default, allow all
sources = append(sources, "file", "inline")
} else if contains("none", opts.Sources) {
sources = nil
}
return &luaScript{
modules: opts.Modules,
sources: sources,
}, nil
}
// Name returns the name of the filter ("lua")
func (ls *luaScript) Name() string {
return filters.LuaName
}
// CreateFilter creates the lua script filter.
func (ls *luaScript) CreateFilter(config []interface{}) (filters.Filter, error) {
if len(ls.sources) == 0 {
return nil, errLuaSourcesDisabled
}
if len(config) == 0 {
return nil, filters.ErrInvalidFilterParameters
}
src, ok := config[0].(string)
if !ok {
return nil, filters.ErrInvalidFilterParameters
}
var params []string
for _, p := range config[1:] {
ps, ok := p.(string)
if !ok {
return nil, filters.ErrInvalidFilterParameters
}
params = append(params, ps)
}
s := &script{source: src, routeParams: params}
if err := s.initScript(ls.modules, ls.sources); err != nil {
return nil, err
}
return s, nil
}
type script struct {
source string
routeParams []string
pool chan *lua.LState
proto *lua.FunctionProto
load []luaModule
preload []luaModule
hasRequest bool
hasResponse bool
}
func (s *script) getState() (*lua.LState, error) {
select {
case L := <-s.pool:
if L == nil {
return nil, errors.New("pool closed")
}
return L, nil
default:
return s.newState()
}
}
func (s *script) putState(L *lua.LState) {
if s.pool == nil { // pool closed
L.Close()
return
}
select {
case s.pool <- L:
default: // pool full, close state
L.Close()
}
}
func (s *script) newState() (*lua.LState, error) {
L := lua.NewState(lua.Options{SkipOpenLibs: true})
for _, m := range s.load {
m.load(L)
}
for _, m := range s.preload {
m.preload(L)
}
L.Push(L.NewFunctionFromProto(s.proto))
err := L.PCall(0, lua.MultRet, nil)
if err != nil {
L.Close()
return nil, err
}
return L, nil
}
func (s *script) initScript(modules, validSources []string) error {
// Compile
var reader io.Reader
var name string
if strings.HasSuffix(s.source, ".lua") {
if !contains("file", validSources) {
return fmt.Errorf(`invalid lua source referenced "file", allowed: "%v"`, validSources)
}
file, err := os.Open(s.source)
if err != nil {
return err
}
defer func() {
if err = file.Close(); err != nil {
log.Errorf("Failed to close lua file %s: %v", s.source, err)
}
}()
reader = bufio.NewReader(file)
name = s.source
} else {
if !contains("inline", validSources) {
return fmt.Errorf(`invalid lua source referenced "inline", allowed: "%v"`, validSources)
}
reader = strings.NewReader(s.source)
name = "<script>"
}
chunk, err := lua_parse.Parse(reader, name)
if err != nil {
return err
}
proto, err := lua.Compile(chunk, name)
if err != nil {
return err
}
s.proto = proto
// Configure enabled modules and symbols
moduleConfig := moduleConfig(modules)
if len(moduleConfig) == 0 {
s.load = append(s.load, standardModules...)
} else {
L := lua.NewState(lua.Options{SkipOpenLibs: true})
defer L.Close()
for _, m := range standardModules {
name := m.name
if m.name == lua.BaseLibName {
name = "base" // alias for empty lua.BaseLibName
}
if symbols, ok := moduleConfig[name]; ok {
if len(symbols) > 0 {
m = m.withSymbols(L, symbols)
}
s.load = append(s.load, m)
}
}
}
// Configure additional modules
additionalModules := []luaModule{
{"base64", base64.Loader, nil},
{"http", gluahttp.NewHttpModule(&http.Client{}).Loader, nil},
{"url", gluaurl.Loader, nil},
{"json", gjson.Loader, nil},
}
if len(moduleConfig) == 0 {
s.preload = append(s.preload, additionalModules...)
} else {
for _, m := range additionalModules {
// TODO: enable selected symbols for preloaded modules
if _, ok := moduleConfig[m.name]; ok {
s.preload = append(s.preload, m)
}
}
}
// Detect request and response functions
// Note: use s.newState() instead of lua.NewState() to load only enabled modules
L, err := s.newState()
if err != nil {
return err
}
defer L.Close()
if fn := L.GetGlobal("request"); fn.Type() == lua.LTFunction {
s.hasRequest = true
}
if fn := L.GetGlobal("response"); fn.Type() == lua.LTFunction {
s.hasResponse = true
}
if !s.hasRequest && !s.hasResponse {
return errors.New("at least one of `request` and `response` function must be present")
}
// Init state pool
s.pool = make(chan *lua.LState, MaxPoolSize) // FIXME make configurable
for i := 0; i < InitialPoolSize; i++ {
L, err := s.newState()
if err != nil {
return err
}
s.putState(L)
}
return nil
}
func (s *script) Request(f filters.FilterContext) {
if s.hasRequest {
s.runFunc("request", f)
}
}
func (s *script) Response(f filters.FilterContext) {
if s.hasResponse {
s.runFunc("response", f)
}
}
func (s *script) runFunc(name string, f filters.FilterContext) {
L, err := s.getState()
if err != nil {
log.Errorf("Error obtaining lua environment: %v", err)
return
}
defer s.putState(L)
pt := L.CreateTable(len(s.routeParams), len(s.routeParams))
for i, p := range s.routeParams {
k, v, _ := strings.Cut(p, "=")
pt.RawSetString(k, lua.LString(v))
pt.RawSetInt(i+1, lua.LString(p))
}
err = L.CallByParam(
lua.P{
Fn: L.GetGlobal(name),
NRet: 0,
Protect: true,
},
s.filterContextAsLuaTable(L, f),
pt,
)
if err != nil {
log.Errorf("Error calling %s from %s: %v", name, s.source, err)
}
}
func (s *script) filterContextAsLuaTable(L *lua.LState, f filters.FilterContext) *lua.LTable {
// this will be passed as parameter to the lua functions
// add metatable to dynamically access fields in the context
t := L.CreateTable(0, 0)
mt := L.CreateTable(0, 1)
mt.RawSetString("__index", L.NewFunction(getContextValue(f)))
L.SetMetatable(t, mt)
return t
}
func serveRequest(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
t := s.Get(-1)
r, ok := t.(*lua.LTable)
if !ok {
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("unsupported type %v, need a table", t.Type())
// return 0
s.Push(lua.LString("invalid type, need a table"))
return 1
}
res := &http.Response{}
r.ForEach(serveTableWalk(res))
f.Serve(res)
return 0
}
}
func serveTableWalk(res *http.Response) func(lua.LValue, lua.LValue) {
return func(k, v lua.LValue) {
sk, ok := k.(lua.LString)
if !ok {
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("unsupported key type %v, need a string", k.Type())
return
}
switch string(sk) {
case "status_code":
n, ok := v.(lua.LNumber)
if !ok {
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("unsupported status_code type %v, need a number", v.Type())
return
}
res.StatusCode = int(n)
case "header":
t, ok := v.(*lua.LTable)
if !ok {
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("unsupported header type %v, need a table", v.Type())
return
}
h := make(http.Header)
t.ForEach(serveHeaderWalk(h))
res.Header = h
case "body":
var body []byte
var err error
switch v.Type() {
case lua.LTString:
data := string(v.(lua.LString))
body = []byte(data)
case lua.LTTable:
body, err = gjson.Encode(v.(*lua.LTable))
if err != nil {
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("%v", err)
return
}
}
res.Body = io.NopCloser(bytes.NewBuffer(body))
}
}
}
func serveHeaderWalk(h http.Header) func(lua.LValue, lua.LValue) {
return func(k, v lua.LValue) {
h.Set(k.String(), v.String())
}
}
func getContextValue(f filters.FilterContext) func(*lua.LState) int {
var request, response, state_bag, path_param *lua.LTable
var serve *lua.LFunction
return func(s *lua.LState) int {
key := s.ToString(-1)
var ret lua.LValue
switch key {
case "request":
// initialize access to request on first use
if request == nil {
request = s.CreateTable(0, 0)
mt := s.CreateTable(0, 2)
mt.RawSetString("__index", s.NewFunction(getRequestValue(f)))
mt.RawSetString("__newindex", s.NewFunction(setRequestValue(f)))
s.SetMetatable(request, mt)
}
ret = request
case "response":
if response == nil {
response = s.CreateTable(0, 0)
mt := s.CreateTable(0, 2)
mt.RawSetString("__index", s.NewFunction(getResponseValue(f)))
mt.RawSetString("__newindex", s.NewFunction(setResponseValue(f)))
s.SetMetatable(response, mt)
}
ret = response
case "state_bag":
if state_bag == nil {
state_bag = s.CreateTable(0, 0)
mt := s.CreateTable(0, 2)
mt.RawSetString("__index", s.NewFunction(getStateBag(f)))
mt.RawSetString("__newindex", s.NewFunction(setStateBag(f)))
s.SetMetatable(state_bag, mt)
}
ret = state_bag
case "path_param":
if path_param == nil {
path_param = s.CreateTable(0, 0)
mt := s.CreateTable(0, 1)
mt.RawSetString("__index", s.NewFunction(getPathParam(f)))
s.SetMetatable(path_param, mt)
}
ret = path_param
case "serve":
if serve == nil {
serve = s.NewFunction(serveRequest(f))
}
ret = serve
default:
return 0
}
s.Push(ret)
return 1
}
}
func getRequestValue(f filters.FilterContext) func(*lua.LState) int {
var header, cookie, url_query *lua.LTable
return func(s *lua.LState) int {
key := s.ToString(-1)
var ret lua.LValue
switch key {
case "header":
if header == nil {
header = s.CreateTable(0, 0)
mt := s.CreateTable(0, 3)
mt.RawSetString("__index", s.NewFunction(getRequestHeader(f)))
mt.RawSetString("__newindex", s.NewFunction(setRequestHeader(f)))
mt.RawSetString("__call", s.NewFunction(iterateRequestHeader(f)))
s.SetMetatable(header, mt)
}
ret = header
case "cookie":
if cookie == nil {
cookie = s.CreateTable(0, 0)
mt := s.CreateTable(0, 3)
mt.RawSetString("__index", s.NewFunction(getRequestCookie(f)))
mt.RawSetString("__newindex", s.NewFunction(unsupported("setting cookie is not supported")))
mt.RawSetString("__call", s.NewFunction(iterateRequestCookie(f)))
s.SetMetatable(cookie, mt)
}
ret = cookie
case "outgoing_host":
ret = lua.LString(f.OutgoingHost())
case "backend_url":
ret = lua.LString(f.BackendUrl())
case "host":
ret = lua.LString(f.Request().Host)
case "remote_addr":
ret = lua.LString(f.Request().RemoteAddr)
case "content_length":
ret = lua.LNumber(f.Request().ContentLength)
case "proto":
ret = lua.LString(f.Request().Proto)
case "method":
ret = lua.LString(f.Request().Method)
case "url":
ret = lua.LString(f.Request().URL.String())
case "url_path":
ret = lua.LString(f.Request().URL.Path)
case "url_query":
if url_query == nil {
url_query = s.CreateTable(0, 0)
mt := s.CreateTable(0, 3)
mt.RawSetString("__index", s.NewFunction(getRequestURLQuery(f)))
mt.RawSetString("__newindex", s.NewFunction(setRequestURLQuery(f)))
mt.RawSetString("__call", s.NewFunction(iterateRequestURLQuery(f)))
s.SetMetatable(url_query, mt)
}
ret = url_query
case "url_raw_query":
ret = lua.LString(f.Request().URL.RawQuery)
default:
return 0
}
s.Push(ret)
return 1
}
}
func setRequestValue(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
key := s.ToString(-2)
switch key {
case "outgoing_host":
f.SetOutgoingHost(s.ToString(-1))
case "url":
u, err := url.Parse(s.ToString(-1))
if err != nil {
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("%v", err)
return 0
}
f.Request().URL = u
case "url_path":
f.Request().URL.Path = s.ToString(-1)
case "url_raw_query":
f.Request().URL.RawQuery = s.ToString(-1)
default:
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("unsupported request field %s", key)
// do nothing for now
}
return 0
}
}
func getResponseValue(f filters.FilterContext) func(*lua.LState) int {
var header *lua.LTable
return func(s *lua.LState) int {
key := s.ToString(-1)
var ret lua.LValue
switch key {
case "header":
if header == nil {
header = s.CreateTable(0, 0)
mt := s.CreateTable(0, 3)
mt.RawSetString("__index", s.NewFunction(getResponseHeader(f)))
mt.RawSetString("__newindex", s.NewFunction(setResponseHeader(f)))
mt.RawSetString("__call", s.NewFunction(iterateResponseHeader(f)))
s.SetMetatable(header, mt)
}
ret = header
case "status_code":
ret = lua.LNumber(f.Response().StatusCode)
default:
return 0
}
s.Push(ret)
return 1
}
}
func setResponseValue(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
key := s.ToString(-2)
switch key {
case "status_code":
v := s.Get(-1)
n, ok := v.(lua.LNumber)
if !ok {
s.RaiseError("unsupported status_code type %v, need a number", v.Type())
return 0
}
f.Response().StatusCode = int(n)
default:
s.RaiseError("unsupported response field %s", key)
}
return 0
}
}
func getStateBag(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
fld := s.ToString(-1)
res, ok := f.StateBag()[fld]
if !ok {
return 0
}
switch res := res.(type) {
case string:
s.Push(lua.LString(res))
case int:
s.Push(lua.LNumber(res))
case int64:
s.Push(lua.LNumber(res))
case float64:
s.Push(lua.LNumber(res))
default:
return 0
}
return 1
}
}
func setStateBag(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
fld := s.ToString(-2)
val := s.Get(-1)
var res interface{}
switch val.Type() {
case lua.LTString:
res = string(val.(lua.LString))
case lua.LTNumber:
res = float64(val.(lua.LNumber))
default:
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// s.RaiseError("unsupported state bag value type %v, need a string or a number", val.Type())
return 0
}
f.StateBag()[fld] = res
return 0
}
}
func getRequestHeader(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
hdr := s.ToString(-1)
res := f.Request().Header.Get(hdr)
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// if res != "" {
// s.Push(lua.LString(res))
// return 1
// }
// return 0
s.Push(lua.LString(res))
return 1
}
}
func setRequestHeader(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
lv := s.Get(-1)
hdr := s.ToString(-2)
switch lv.Type() {
case lua.LTNil:
f.Request().Header.Del(hdr)
case lua.LTString:
str := string(lv.(lua.LString))
if str == "" {
f.Request().Header.Del(hdr)
} else {
f.Request().Header.Set(hdr, str)
}
default:
val := s.ToString(-1)
f.Request().Header.Set(hdr, val)
}
return 0
}
}
func iterateRequestHeader(f filters.FilterContext) func(*lua.LState) int {
// https://www.lua.org/pil/7.2.html
return func(s *lua.LState) int {
s.Push(s.NewFunction(nextHeader(f.Request().Header)))
return 1
}
}
func getRequestCookie(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
k := s.ToString(-1)
c, err := f.Request().Cookie(k)
if err == nil {
s.Push(lua.LString(c.Value))
return 1
}
return 0
}
}
func iterateRequestCookie(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
s.Push(s.NewFunction(nextCookie(f.Request().Cookies())))
return 1
}
}
func nextCookie(cookies []*http.Cookie) func(*lua.LState) int {
return func(s *lua.LState) int {
if len(cookies) > 0 {
c := cookies[0]
s.Push(lua.LString(c.Name))
s.Push(lua.LString(c.Value))
cookies[0] = nil // mind peace
cookies = cookies[1:]
return 2
}
return 0
}
}
func getResponseHeader(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
hdr := s.ToString(-1)
res := f.Response().Header.Get(hdr)
// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
// if res != "" {
// s.Push(lua.LString(res))
// return 1
// }
// return 0
s.Push(lua.LString(res))
return 1
}
}
func setResponseHeader(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
lv := s.Get(-1)
hdr := s.ToString(-2)
switch lv.Type() {
case lua.LTNil:
f.Response().Header.Del(hdr)
case lua.LTString:
str := string(lv.(lua.LString))
if str == "" {
f.Response().Header.Del(hdr)
} else {
f.Response().Header.Set(hdr, str)
}
default:
val := s.ToString(-1)
f.Response().Header.Set(hdr, val)
}
return 0
}
}
func iterateResponseHeader(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
s.Push(s.NewFunction(nextHeader(f.Response().Header)))
return 1
}
}
func nextHeader(h http.Header) func(*lua.LState) int {
keys := make([]string, 0, len(h))
for k := range h {
keys = append(keys, k)
}
return func(s *lua.LState) int {
if len(keys) > 0 {
k := keys[0]
s.Push(lua.LString(k))
s.Push(lua.LString(h.Get(k)))
keys[0] = "" // mind peace
keys = keys[1:]
return 2
}
return 0
}
}
func getRequestURLQuery(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
k := s.ToString(-1)
res := f.Request().URL.Query().Get(k)
if res != "" {
s.Push(lua.LString(res))
return 1
}
return 0
}
}
func setRequestURLQuery(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
lv := s.Get(-1)
k := s.ToString(-2)
q := f.Request().URL.Query()
switch lv.Type() {
case lua.LTNil:
q.Del(k)
case lua.LTString:
str := string(lv.(lua.LString))
if str == "" {
q.Del(k)
} else {
q.Set(k, str)
}
default:
val := s.ToString(-1)
q.Set(k, val)
}
f.Request().URL.RawQuery = q.Encode()
return 0
}
}
func iterateRequestURLQuery(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
s.Push(s.NewFunction(nextQuery(f.Request().URL.Query())))
return 1
}
}
func nextQuery(v url.Values) func(*lua.LState) int {
keys := make([]string, 0, len(v))
for k := range v {
keys = append(keys, k)
}
return func(s *lua.LState) int {
if len(keys) > 0 {
k := keys[0]
s.Push(lua.LString(k))
s.Push(lua.LString(v.Get(k)))
keys[0] = "" // mind peace
keys = keys[1:]
return 2
}
return 0
}
}
func getPathParam(f filters.FilterContext) func(*lua.LState) int {
return func(s *lua.LState) int {
n := s.ToString(-1)
p := f.PathParam(n)
if p != "" {
s.Push(lua.LString(p))
return 1
}
return 0
}
}
func unsupported(message string) func(*lua.LState) int {
return func(s *lua.LState) int {
s.RaiseError(message)
return 0
}
}
func contains(s string, a []string) bool {
for _, w := range a {
if s == w {
return true
}
}
return false
}