From 14423eaa0163d126773f39c9c1b8b51a6d35aaef Mon Sep 17 00:00:00 2001 From: Babak Vahedipour Date: Fri, 17 Jun 2022 15:39:34 +0200 Subject: [PATCH] initial commit --- LICENSE | 203 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ engine.go | 183 ++++++++++++++++++++++++++++++++++++++++++++++++ go.mod | 3 + 3 files changed, 389 insertions(+) create mode 100644 LICENSE create mode 100644 engine.go create mode 100644 go.mod diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..6b0b127 --- /dev/null +++ b/LICENSE @@ -0,0 +1,203 @@ + + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright [yyyy] [name of copyright owner] + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + diff --git a/engine.go b/engine.go new file mode 100644 index 0000000..3d49736 --- /dev/null +++ b/engine.go @@ -0,0 +1,183 @@ +// Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved. +/** + * mostly taken from aws lambda go stub for + * best compatibility. This will have to change + * to allow usage of WAS protocol and + */ +package functions + +import ( + "bytes" + "context" + "encoding/json" + "errors" + "fmt" + "io/ioutil" + "net/http" + "net/http/fcgi" + "reflect" +) + +type Handler interface { + Invoke(ctx context.Context, payload []byte) ([]byte, error) +} + +type server struct { + Handler + baseContext context.Context + jsonResponseEscapeHTML bool + jsonResponseIndentPrefix string + jsonResponseIndentValue string +} + +func (s server) ServeHTTP(w http.ResponseWriter, req *http.Request) { + body, err := ioutil.ReadAll(req.Body) + if err != nil { + http.Error(w, "can't read body", http.StatusBadRequest) + return + } + + data, err := s.Invoke(s.baseContext, body) + if err != nil { + http.Error(w, err.Error(), http.StatusInternalServerError) + return + } + w.Write(data) +} + +type bytesHandlerFunc func(context.Context, []byte) ([]byte, error) + +func (h bytesHandlerFunc) Invoke(ctx context.Context, payload []byte) ([]byte, error) { + return h(ctx, payload) +} + +func errorHandler(err error) Handler { + return bytesHandlerFunc(func(_ context.Context, _ []byte) ([]byte, error) { + return nil, err + }) +} + +func validateArguments(handler reflect.Type) (bool, error) { + handlerTakesContext := false + if handler.NumIn() > 2 { + return false, fmt.Errorf("handlers may not take more than two arguments, but handler takes %d", handler.NumIn()) + } else if handler.NumIn() > 0 { + contextType := reflect.TypeOf((*context.Context)(nil)).Elem() + argumentType := handler.In(0) + handlerTakesContext = argumentType.Implements(contextType) + if handler.NumIn() > 1 && !handlerTakesContext { + return false, fmt.Errorf("handler takes two arguments, but the first is not Context. got %s", argumentType.Kind()) + } + } + + return handlerTakesContext, nil +} + +func validateReturns(handler reflect.Type) error { + errorType := reflect.TypeOf((*error)(nil)).Elem() + + switch n := handler.NumOut(); { + case n > 2: + return fmt.Errorf("handler may not return more than two values") + case n > 1: + if !handler.Out(1).Implements(errorType) { + return fmt.Errorf("handler returns two values, but the second does not implement error") + } + case n == 1: + if !handler.Out(0).Implements(errorType) { + return fmt.Errorf("handler returns a single value, but it does not implement error") + } + } + + return nil +} + +func reflectHandler(handlerFunc interface{}, s *server) Handler { + + if handlerFunc == nil { + return errorHandler(errors.New("handler is nil")) + } + + if handler, ok := handlerFunc.(Handler); ok { + return handler + } + + handler := reflect.ValueOf(handlerFunc) + handlerType := reflect.TypeOf(handlerFunc) + if handlerType.Kind() != reflect.Func { + return errorHandler(fmt.Errorf("handler kind %s is not %s", handlerType.Kind(), reflect.Func)) + } + + takesContext, err := validateArguments(handlerType) + if err != nil { + return errorHandler(err) + } + + if err := validateReturns(handlerType); err != nil { + return errorHandler(err) + } + + return bytesHandlerFunc(func(ctx context.Context, payload []byte) ([]byte, error) { + in := bytes.NewBuffer(payload) + out := bytes.NewBuffer(nil) + decoder := json.NewDecoder(in) + encoder := json.NewEncoder(out) + encoder.SetEscapeHTML(s.jsonResponseEscapeHTML) + encoder.SetIndent(s.jsonResponseIndentPrefix, s.jsonResponseIndentValue) + + // construct arguments + var args []reflect.Value + if takesContext { + args = append(args, reflect.ValueOf(ctx)) + } + if (handlerType.NumIn() == 1 && !takesContext) || handlerType.NumIn() == 2 { + eventType := handlerType.In(handlerType.NumIn() - 1) + event := reflect.New(eventType) + if err := decoder.Decode(event.Interface()); err != nil { + return nil, err + } + args = append(args, event.Elem()) + } + + response := handler.Call(args) + + // return the error, if any + if len(response) > 0 { + if errVal, ok := response[len(response)-1].Interface().(error); ok && errVal != nil { + return nil, errVal + } + } + // set the response value, if any + var val interface{} + if len(response) > 1 { + val = response[0].Interface() + } + if err := encoder.Encode(val); err != nil { + return nil, err + } + + responseBytes := out.Bytes() + // back-compat, strip the encoder's trailing newline unless WithSetIndent was used + if s.jsonResponseIndentValue == "" && s.jsonResponseIndentPrefix == "" { + return responseBytes[:len(responseBytes)-1], nil + } + + return responseBytes, nil + }) +} + +func newServer(handlerFunc interface{}) *server { + + s := &server{ + baseContext: context.Background(), + jsonResponseEscapeHTML: false, + jsonResponseIndentPrefix: "", + jsonResponseIndentValue: "", + } + s.Handler = reflectHandler(handlerFunc, s) + return s +} + +func Start(handler interface{}) { + fcgi.Serve(nil, newServer(handler)) +} diff --git a/go.mod b/go.mod new file mode 100644 index 0000000..62aa0f7 --- /dev/null +++ b/go.mod @@ -0,0 +1,3 @@ +module github.com/cm4all/functions-go + +go 1.18