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tsweb: make JSONHandlerFunc implement ReturnHandler, not http.Handler

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This way something is capable of logging errors on the server.

Fixes #766

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
crawshaw/jsonhandler
David Crawshaw 4 years ago committed by David Crawshaw
parent 3aeb2e204c
commit dea3ef0597
2 changed files with 31 additions and 22 deletions
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31
tsweb/jsonhandler.go
Unescape Escape View File

@ -6,6 +6,7 @@ package tsweb
import (
"encoding/json"
"fmt"
"net/http"
)
@ -15,23 +16,23 @@ type response struct {
Data interface{} `json:"data,omitempty"`
}
// TODO: Header
// JSONHandlerFunc only take *http.Request as argument to avoid any misuse of http.ResponseWriter.
// The function's results must be (status int, data interface{}, err error).
// Return a HTTPError to show an error message, otherwise JSONHandler will only show "internal server error".
// JSONHandlerFunc is an HTTP ReturnHandler that writes JSON responses to the client.
//
// Return a HTTPError to show an error message, otherwise JSONHandlerFunc will
// only report "internal server error" to the user.
type JSONHandlerFunc func(r *http.Request) (status int, data interface{}, err error)
// ServeHTTP calls the JSONHandlerFunc and automatically marshals http responses.
// ServeHTTPReturn implements the ReturnHandler interface.
//
// Use the following code to unmarshal the request body
//
// body := new(DataType)
// if err := json.NewDecoder(r.Body).Decode(body); err != nil {
// return http.StatusBadRequest, nil, err
// }
//
// Check jsonhandler_text.go for examples
func (fn JSONHandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// See jsonhandler_text.go for examples.
func (fn JSONHandlerFunc) ServeHTTPReturn(w http.ResponseWriter, r *http.Request) error {
w.Header().Set("Content-Type", "application/json")
var resp *response
status, data, err := fn(r)
@ -53,6 +54,10 @@ func (fn JSONHandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
Error: werr.Msg,
Data: data,
}
// Unwrap the HTTPError here because we are communicating with
// the client in this handler. We don't want the wrapping
// ReturnHandler to do it too.
err = werr.Err
} else {
resp = &response{
Status: "error",
@ -61,13 +66,17 @@ func (fn JSONHandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
}
}
b, err := json.Marshal(resp)
if err != nil {
b, jerr := json.Marshal(resp)
if jerr != nil {
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte(`{"status":"error","error":"json marshal error"}`))
return
if err != nil {
return fmt.Errorf("%w, and then we could not respond: %v", err, jerr)
}
return jerr
}
w.WriteHeader(status)
w.Write(b)
return err
}

22
tsweb/jsonhandler_test.go
Unescape Escape View File

@ -61,7 +61,7 @@ func TestNewJSONHandler(t *testing.T) {
t.Run("200 simple", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("GET", "/", nil)
h21.ServeHTTP(w, r)
h21.ServeHTTPReturn(w, r)
checkStatus(w, "success", http.StatusOK)
})
@ -72,7 +72,7 @@ func TestNewJSONHandler(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("GET", "/", nil)
h.ServeHTTP(w, r)
h.ServeHTTPReturn(w, r)
checkStatus(w, "error", http.StatusForbidden)
})
@ -83,7 +83,7 @@ func TestNewJSONHandler(t *testing.T) {
t.Run("200 get data", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("GET", "/", nil)
h22.ServeHTTP(w, r)
h22.ServeHTTPReturn(w, r)
checkStatus(w, "success", http.StatusOK)
})
@ -102,21 +102,21 @@ func TestNewJSONHandler(t *testing.T) {
t.Run("200 post data", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("POST", "/", strings.NewReader(`{"Name": "tailscale"}`))
h31.ServeHTTP(w, r)
h31.ServeHTTPReturn(w, r)
checkStatus(w, "success", http.StatusOK)
})
t.Run("400 bad json", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("POST", "/", strings.NewReader(`{`))
h31.ServeHTTP(w, r)
h31.ServeHTTPReturn(w, r)
checkStatus(w, "error", http.StatusBadRequest)
})
t.Run("400 post data error", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("POST", "/", strings.NewReader(`{}`))
h31.ServeHTTP(w, r)
h31.ServeHTTPReturn(w, r)
resp := checkStatus(w, "error", http.StatusBadRequest)
if resp.Error != "name is empty" {
t.Fatalf("wrong error")
@ -141,7 +141,7 @@ func TestNewJSONHandler(t *testing.T) {
t.Run("200 post data", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("POST", "/", strings.NewReader(`{"Price": 10}`))
h32.ServeHTTP(w, r)
h32.ServeHTTPReturn(w, r)
resp := checkStatus(w, "success", http.StatusOK)
t.Log(resp.Data)
if resp.Data.Price != 20 {
@ -152,7 +152,7 @@ func TestNewJSONHandler(t *testing.T) {
t.Run("400 post data error", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("POST", "/", strings.NewReader(`{}`))
h32.ServeHTTP(w, r)
h32.ServeHTTPReturn(w, r)
resp := checkStatus(w, "error", http.StatusBadRequest)
if resp.Error != "price is empty" {
t.Fatalf("wrong error")
@ -162,7 +162,7 @@ func TestNewJSONHandler(t *testing.T) {
t.Run("500 internal server error", func(t *testing.T) {
w := httptest.NewRecorder()
r := httptest.NewRequest("POST", "/", strings.NewReader(`{"Name": "root"}`))
h32.ServeHTTP(w, r)
h32.ServeHTTPReturn(w, r)
resp := checkStatus(w, "error", http.StatusInternalServerError)
if resp.Error != "internal server error" {
t.Fatalf("wrong error")
@ -174,7 +174,7 @@ func TestNewJSONHandler(t *testing.T) {
r := httptest.NewRequest("POST", "/", nil)
JSONHandlerFunc(func(r *http.Request) (int, interface{}, error) {
return http.StatusOK, make(chan int), nil
}).ServeHTTP(w, r)
}).ServeHTTPReturn(w, r)
resp := checkStatus(w, "error", http.StatusInternalServerError)
if resp.Error != "json marshal error" {
t.Fatalf("wrong error")
@ -186,7 +186,7 @@ func TestNewJSONHandler(t *testing.T) {
r := httptest.NewRequest("POST", "/", nil)
JSONHandlerFunc(func(r *http.Request) (status int, data interface{}, err error) {
return
}).ServeHTTP(w, r)
}).ServeHTTPReturn(w, r)
checkStatus(w, "error", http.StatusInternalServerError)
})
}

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