More optimal error responses

errors.go

@@ -0,0 +1,57 @@
+package keydbextension
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sync"
+)
+
+const (
+	ErrNoAuthToken     = "ErrNoAuthToken"
+	ErrUnauthorized    = "ErrUnauthorized"
+	ErrIncompleteReq   = "ErrIncompleteReq"
+	ErrConnFailed      = "ErrConnFailed"
+	ErrReqNotProcessed = "ErrReqNotProcessed"
+	ErrUnknown         = "ErrUnknown"
+)
+
+var (
+	errorResponses     map[string][]byte
+	errorStatusCodes   map[string]int
+	errorResponsesOnce sync.Once
+)
+
+func initErrorResponses() {
+	errorResponses = make(map[string][]byte)
+	errorStatusCodes = make(map[string]int)
+
+	errors := []struct {
+		key     string
+		code    int
+		message string
+	}{
+		{ErrNoAuthToken, http.StatusUnauthorized, "No auth token provided"},
+		{ErrUnauthorized, http.StatusForbidden, "Unauthorized access"},
+		{ErrIncompleteReq, http.StatusBadRequest, "Request was incomplete"},
+		{ErrConnFailed, 523, "Connection to GuardianPT failed"},
+		{ErrReqNotProcessed, 522, "Request could not be processed"},
+		{ErrUnknown, 520, "An unknown error occurred"},
+	}
+
+	for _, err := range errors {
+		error_code := fmt.Sprintf("0x%08X", 0xC0043293+err.code)
+		response, _ := json.Marshal(map[string]interface{}{
+			"error":   true,
+			"code":    error_code,
+			"message": err.message,
+		})
+		errorResponses[err.key] = response
+		errorStatusCodes[err.key] = err.code
+	}
+}
+
+func getHTTPStatusCode(key string) int {
+	errorResponsesOnce.Do(initErrorResponses)
+	return errorStatusCodes[key]
+}

keydb_extension.go

@@ -2,7 +2,6 @@ package keydbextension
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -69,18 +68,18 @@ func (handler *KeyDBHandler) Provision(ctx caddy.Context) error {
 func (handler KeyDBHandler) ServeHTTP(writer http.ResponseWriter, request *http.Request, next caddyhttp.Handler) error {
 	authToken := request.Header.Get(authTokenHeader)
 	if authToken == "" {
-		sendJSONError(writer, http.StatusUnauthorized, "No auth token provided")
+		sendJSONError(writer, ErrNoAuthToken)
 		return nil
 	}
 
 	if !handler.validTokens[authToken] {
-		sendJSONError(writer, http.StatusForbidden, "Unauthorized access")
+		sendJSONError(writer, ErrUnauthorized)
 		return nil
 	}
 
 	question := request.URL.Query().Get("q")
 	if question == "" {
-		sendJSONError(writer, http.StatusBadRequest, "Request was incomplete")
+		sendJSONError(writer, ErrIncompleteReq)
 		return nil
 	}
 
@@ -89,10 +88,10 @@ func (handler KeyDBHandler) ServeHTTP(writer http.ResponseWriter, request *http.
 
 	val, err := handler.client.Get(ctx, question).Result()
 	if err == redis.Nil {
-		sendJSONError(writer, http.StatusNotFound, "Connection to GuardianPT failed")
+		sendJSONError(writer, ErrConnFailed)
 		return nil
 	} else if err != nil {
-		sendJSONError(writer, http.StatusInternalServerError, "Request could not be processed")
+		sendJSONError(writer, ErrReqNotProcessed)
 		return err
 	}
 
@@ -144,18 +143,15 @@ func parseCaddyfile(helper httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, e
 }
 
 // sendJSONError writes a JSON-formatted error response to the provided http.ResponseWriter.
-func sendJSONError(w http.ResponseWriter, code int, message string) {
+func sendJSONError(w http.ResponseWriter, errorKey string) {
+	errorResponse, exists := errorResponses[errorKey]
+	if !exists {
+		errorResponse = errorResponses["ErrUnknown"]
+	}
+
 	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(code)
-
-	// Spooky high error codes
-	mysteriousCode := fmt.Sprintf("0x%08X", 0xC0043293+code)
-
-	json.NewEncoder(w).Encode(map[string]interface{}{
-		"error":   true,
-		"code":    mysteriousCode,
-		"message": message,
-	})
+	w.WriteHeader(getHTTPStatusCode(errorKey))
+	w.Write(errorResponse)
 }
 
 // The KeyDBHandler type implements several interfaces that allow it to be used as a Caddy module: