92 lines
2.5 KiB
Go
92 lines
2.5 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tsweb
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import (
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"encoding/json"
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"fmt"
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"net/http"
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)
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type response struct {
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Status string `json:"status"`
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Error string `json:"error,omitempty"`
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Data interface{} `json:"data,omitempty"`
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}
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// JSONHandlerFunc is an HTTP ReturnHandler that writes JSON responses to the client.
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//
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// Return a HTTPError to show an error message, otherwise JSONHandlerFunc will
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// only report "internal server error" to the user with status code 500.
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type JSONHandlerFunc func(r *http.Request) (status int, data interface{}, err error)
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// ServeHTTPReturn implements the ReturnHandler interface.
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//
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// Use the following code to unmarshal the request body
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//
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// body := new(DataType)
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// if err := json.NewDecoder(r.Body).Decode(body); err != nil {
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// return http.StatusBadRequest, nil, err
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// }
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//
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// See jsonhandler_test.go for examples.
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func (fn JSONHandlerFunc) ServeHTTPReturn(w http.ResponseWriter, r *http.Request) error {
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w.Header().Set("Content-Type", "application/json")
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var resp *response
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status, data, err := fn(r)
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if err != nil {
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if werr, ok := err.(HTTPError); ok {
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resp = &response{
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Status: "error",
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Error: werr.Msg,
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Data: data,
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}
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// Unwrap the HTTPError here because we are communicating with
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// the client in this handler. We don't want the wrapping
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// ReturnHandler to do it too.
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err = werr.Err
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if werr.Msg != "" {
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err = fmt.Errorf("%s: %w", werr.Msg, err)
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}
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// take status from the HTTPError to encourage error handling in one location
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if status != 0 && status != werr.Code {
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err = fmt.Errorf("[unexpected] non-zero status that does not match HTTPError status, status: %d, HTTPError.code: %d: %w", status, werr.Code, err)
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}
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status = werr.Code
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} else {
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status = http.StatusInternalServerError
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resp = &response{
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Status: "error",
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Error: "internal server error",
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}
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}
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} else if status == 0 {
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status = http.StatusInternalServerError
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resp = &response{
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Status: "error",
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Error: "internal server error",
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}
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} else if err == nil {
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resp = &response{
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Status: "success",
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Data: data,
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}
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}
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b, jerr := json.Marshal(resp)
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if jerr != nil {
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte(`{"status":"error","error":"json marshal error"}`))
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if err != nil {
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return fmt.Errorf("%w, and then we could not respond: %v", err, jerr)
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}
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return jerr
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}
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w.WriteHeader(status)
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w.Write(b)
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return err
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}
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