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|
package starlarkmw
import (
"context"
"fmt"
"net/http"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
"github.com/caddyserver/caddy/v2/modules/caddyhttp/starlarkmw/internal/lib"
caddyscript "github.com/caddyserver/caddy/v2/pkg/caddyscript/lib"
"github.com/starlight-go/starlight/convert"
"go.starlark.net/starlark"
)
func init() {
caddy.RegisterModule(StarlarkMW{})
}
// StarlarkMW represents a middleware responder written in starlark
type StarlarkMW struct {
Script string `json:"script"`
serveHTTP *starlark.Function
setup *starlark.Function
thread *starlark.Thread
loadMiddleware *lib.LoadMiddleware
execute *lib.Execute
globals *starlark.StringDict
gctx caddy.Context
rctx caddy.Context
rcancel context.CancelFunc
}
// CaddyModule returns the Caddy module information.
func (StarlarkMW) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.starlark",
New: func() caddy.Module { return new(StarlarkMW) },
}
}
// ServeHTTP responds to an http request with starlark.
func (s *StarlarkMW) ServeHTTP(w http.ResponseWriter, r *http.Request) error {
var mwcancel context.CancelFunc
var mwctx caddy.Context
// call setup() to prepare the middleware chain if it is defined
if s.setup != nil {
mwctx, mwcancel = caddy.NewContext(s.gctx)
defer mwcancel()
s.loadMiddleware.Ctx = mwctx
args := starlark.Tuple{caddyscript.HTTPRequest{Req: r}}
_, err := starlark.Call(new(starlark.Thread), s.setup, args, nil)
if err != nil {
return fmt.Errorf("starlark setup(), %v", err)
}
}
// dynamically build middleware chain for each request
var stack caddyhttp.Handler = caddyhttp.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
wr, err := convert.ToValue(w)
if err != nil {
return fmt.Errorf("cannot convert response writer to starlark value")
}
args := starlark.Tuple{wr, caddyscript.HTTPRequest{Req: r}}
v, err := starlark.Call(new(starlark.Thread), s.serveHTTP, args, nil)
if err != nil {
return fmt.Errorf("starlark serveHTTP(), %v", err)
}
// if a responder type was returned from starlark we should run it otherwise it
// is expected to handle the request
if resp, ok := v.(lib.ResponderModule); ok {
return resp.Instance.ServeHTTP(w, r)
}
return nil
})
// TODO :- make middlewareResponseWriter exported and wrap w with that
var mid []caddyhttp.Middleware
for _, m := range s.execute.Modules {
mid = append(mid, func(next caddyhttp.Handler) caddyhttp.Handler {
return caddyhttp.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
return m.Instance.ServeHTTP(w, r, next)
})
})
}
for i := len(mid) - 1; i >= 0; i-- {
stack = mid[i](stack)
}
s.execute.Modules = nil
return stack.ServeHTTP(w, r)
}
// Cleanup cleans up any modules loaded during the creation of a starlark route.
func (s *StarlarkMW) Cleanup() error {
s.rcancel()
return nil
}
// Provision sets up the starlark env.
func (s *StarlarkMW) Provision(ctx caddy.Context) error {
// store global context
s.gctx = ctx
// setup context for cleaning up any modules loaded during starlark script parsing phase
rctx, cancel := caddy.NewContext(ctx)
s.rcancel = cancel
// setup starlark global env
env := make(starlark.StringDict)
loadMiddleware := lib.LoadMiddleware{}
loadResponder := lib.LoadResponder{
Ctx: rctx,
}
execute := lib.Execute{}
lr := starlark.NewBuiltin("loadResponder", loadResponder.Run)
lr = lr.BindReceiver(&loadResponder)
env["loadResponder"] = lr
lm := starlark.NewBuiltin("loadMiddleware", loadMiddleware.Run)
lm = lm.BindReceiver(&loadMiddleware)
env["loadMiddleware"] = lm
ex := starlark.NewBuiltin("execute", execute.Run)
ex = ex.BindReceiver(&execute)
env["execute"] = ex
// import caddyscript lib
env["time"] = caddyscript.Time{}
env["regexp"] = caddyscript.Regexp{}
// configure starlark
thread := new(starlark.Thread)
s.thread = thread
// run starlark script
globals, err := starlark.ExecFile(thread, "", s.Script, env)
if err != nil {
return fmt.Errorf("starlark exec file: %v", err.Error())
}
// extract defined methods to setup middleware chain and responder, setup is not required
var setup *starlark.Function
if _, ok := globals["setup"]; ok {
setup, ok = globals["setup"].(*starlark.Function)
if !ok {
return fmt.Errorf("setup function not defined in starlark script")
}
}
serveHTTP, ok := globals["serveHTTP"].(*starlark.Function)
if !ok {
return fmt.Errorf("serveHTTP function not defined in starlark script")
}
s.setup = setup
s.serveHTTP = serveHTTP
s.loadMiddleware = &loadMiddleware
s.execute = &execute
s.globals = &globals
return nil
}
|
