diff --git a/json-adapter b/json-adapter new file mode 100755 index 0000000..36ab08b Binary files /dev/null and b/json-adapter differ diff --git a/main.go b/main.go index 07aedaf..96d3fe0 100644 --- a/main.go +++ b/main.go @@ -15,6 +15,40 @@ import ( "time" ) +var httpc = &http.Client{ + Timeout: time.Minute, + Transport: &http.Transport{ + DisableKeepAlives: true, + }, +} + +type Handler struct { + tmpl *template.Template + target *url.URL +} + +func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) { + if err := h.serveHTTP(w, r); err != nil { + log.Println("!", err) + http.Error(w, err.Error(), http.StatusBadRequest) + } +} + +func (h Handler) serveHTTP(w http.ResponseWriter, r *http.Request) error { + b, err := adapt(r.Body, h.tmpl) + if err != nil { + return err + } + + resp, err := proxy(h.target, r, io.NopCloser(bytes.NewReader(b))) + if err != nil { + return err + } + defer resp.Body.Close() + + return forward(w, resp) +} + func main() { fs := flag.NewFlagSet(os.Args[0], flag.ContinueOnError) p := fs.Int("p", 28080, "port") @@ -34,66 +68,55 @@ func main() { panic(err) } - c := &http.Client{ - Timeout: time.Minute, - Transport: &http.Transport{ - DisableKeepAlives: true, - }, - } - - handle := func(w http.ResponseWriter, r *http.Request) error { - b, _ := io.ReadAll(io.LimitReader(r.Body, 1024*1024)) - - var v interface{} - if err := json.Unmarshal(b, &v); err != nil { - return err - } - buff := bytes.NewBuffer(nil) - if err := tmpl.Execute(buff, v); err != nil { - return err - } - - log.Printf("%s => %s => %s", b, buff.Bytes(), u.String()) - - req, err := http.NewRequest(r.Method, u.String(), io.NopCloser(buff)) - if err != nil { - return err - } - req = req.WithContext(r.Context()) - for k, v := range r.Header { - switch strings.ToLower(k) { - case "content-length": - default: - req.Header.Set(k, v[0]) - for _, v := range v[1:] { - req.Header.Add(k, v) - } - } - } - resp, err := c.Do(req) - if err != nil { - return err - } - defer resp.Body.Close() - - for k, v := range resp.Header { - w.Header().Set(k, v[0]) - for _, v := range v[1:] { - w.Header().Add(k, v) - } - } - w.WriteHeader(resp.StatusCode) - io.Copy(w, resp.Body) - - return nil - } + h := Handler{tmpl: tmpl, target: u} log.Println("listening on", *p) - if err := http.ListenAndServe(":"+strconv.Itoa(*p), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { - if err := handle(w, r); err != nil { - log.Println("!", err) - http.Error(w, err.Error(), http.StatusBadRequest) - } - })); err != nil { + if err := http.ListenAndServe(":"+strconv.Itoa(*p), h); err != nil { panic(err) } } + +func adapt(r io.Reader, tmpl *template.Template) ([]byte, error) { + b, _ := io.ReadAll(io.LimitReader(r, 1024*1024)) + var v interface{} + buff := bytes.NewBuffer(nil) + if err := json.Unmarshal(b, &v); err != nil { + return nil, err + } else if err := tmpl.Execute(buff, v); err != nil { + return nil, err + } + log.Printf("%s => %s", b, buff.Bytes()) + return buff.Bytes(), nil +} + +func proxy(u *url.URL, r *http.Request, rc io.ReadCloser) (*http.Response, error) { + req, err := http.NewRequest(r.Method, u.String(), rc) + if err != nil { + return nil, err + } + + req = req.WithContext(r.Context()) + for k, v := range r.Header { + switch strings.ToLower(k) { + case "content-length": + default: + req.Header.Set(k, v[0]) + for _, v := range v[1:] { + req.Header.Add(k, v) + } + } + } + + return httpc.Do(req) +} + +func forward(w http.ResponseWriter, resp *http.Response) error { + for k, v := range resp.Header { + w.Header().Set(k, v[0]) + for _, v := range v[1:] { + w.Header().Add(k, v) + } + } + w.WriteHeader(resp.StatusCode) + io.Copy(w, resp.Body) + return nil +}