From 058ce19858d1e97a433f9835bcf8471ac5c92140 Mon Sep 17 00:00:00 2001
From: Matthias Hannig <matthias@hannig.cc>
Date: Sun, 5 Aug 2018 18:25:59 +0200
Subject: [PATCH] improved error handling

---
 backend/api.go          |  9 ++++++--
 backend/api/response.go |  5 +++-
 backend/api_errors.go   | 51 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+), 3 deletions(-)
 create mode 100644 backend/api_errors.go

diff --git a/backend/api.go b/backend/api.go
index f3bc13c..efb03a6 100644
--- a/backend/api.go
+++ b/backend/api.go
@@ -45,9 +45,14 @@ func endpoint(wrapped apiEndpoint) httprouter.Handle {
 		// Get result from handler
 		result, err := wrapped(req, params)
 		if err != nil {
-			result = api.ErrorResponse{
-				Error: err.Error(),
+			// Get affected rs id
+			rsId, paramErr := validateSourceId(params.ByName("id"))
+			if paramErr != nil {
+				rsId = -1
 			}
+
+			// Make error response
+			result = apiErrorResponse(rsId, err)
 			payload, _ := json.Marshal(result)
 			http.Error(res, string(payload), http.StatusInternalServerError)
 			return
diff --git a/backend/api/response.go b/backend/api/response.go
index 3b553ec..eea8a45 100644
--- a/backend/api/response.go
+++ b/backend/api/response.go
@@ -12,7 +12,10 @@ type Details map[string]interface{}
 
 // Error Handling
 type ErrorResponse struct {
-	Error string `json:"error"`
+	Message       string `json:"message"`
+	Code          int    `json:"code"`
+	Tag           string `json:"tag"`
+	RouteserverId int    `json:"routeserver_id"`
 }
 
 // Cache aware api response
diff --git a/backend/api_errors.go b/backend/api_errors.go
new file mode 100644
index 0000000..5204451
--- /dev/null
+++ b/backend/api_errors.go
@@ -0,0 +1,51 @@
+package main
+
+// Improve error handling
+// Create api.ErrorResponses based on errors returned from server.
+// Strip out potentially sensitive information, eg. connection errors
+// to internal IP addresses.
+
+import (
+	"net/url"
+	"strings"
+
+	"github.com/alice-lg/alice-lg/backend/api"
+)
+
+const (
+	GENERIC_ERROR_TAG      = "GENERIC_ERROR"
+	CONNECTION_REFUSED_TAG = "CONNECTION_REFUSED"
+	CONNECTION_TIMEOUT_TAG = "CONNECTION_TIMEOUT"
+)
+
+const (
+	GENERIC_ERROR_CODE      = 42
+	CONNECTION_REFUSED_CODE = 100
+	CONNECTION_TIMEOUT_CODE = 101
+)
+
+func apiErrorResponse(routeserverId int, err error) api.ErrorResponse {
+	code := GENERIC_ERROR_CODE
+	message := err.Error()
+	tag := GENERIC_ERROR_TAG
+
+	switch e := err.(type) {
+	case *url.Error:
+		if strings.Contains(message, "connection refused") {
+			tag = CONNECTION_REFUSED_TAG
+			code = CONNECTION_REFUSED_CODE
+			message = "Connection refused while dialing the API"
+		} else if e.Timeout() {
+			tag = CONNECTION_TIMEOUT_TAG
+			code = CONNECTION_TIMEOUT_CODE
+			message = "Connection timed out when connecting to the backend API"
+		}
+	}
+
+	return api.ErrorResponse{
+		Code:          code,
+		Tag:           tag,
+		Message:       message,
+		RouteserverId: routeserverId,
+	}
+}