tun2: return a snazzy html page when no backend is connected

2017-09-30 11:04:33 -07:00 · 2017-09-30 11:04:33 -07:00 · 930d16a1a2
parent 235eed3d84
commit 930d16a1a2
1 changed files with 34 additions and 1 deletions
--- a/lib/tun2/server.go
+++ b/lib/tun2/server.go
@ -1,13 +1,17 @@
 package tun2

 import (
+	"bytes"
 	"context"
 	"crypto/tls"
 	"encoding/json"
 	"errors"
+	"fmt"
+	"io/ioutil"
 	"math/rand"
 	"net"
 	"net/http"
+	"os"
 	"sync"
 	"time"

@ -444,7 +448,36 @@ func (s *Server) RoundTrip(req *http.Request) (*http.Response, error) {
 				"uri":    req.RequestURI,
 			})

-			return nil, ErrNoSuchBackend
+			template := `<html><head><title>no backends connected</title></head><body><h1>no backends connected</h1><p>Please ensure a backend is running for ${HOST}. This is request ID ${REQ_ID}.</p></body></html>`
+
+			resbody := []byte(os.Expand(template, func(in string) string {
+				switch in {
+				case "HOST":
+					return req.Host
+				case "REQ_ID":
+					return req.Header.Get("X-Request-Id")
+				}
+
+				return "<unknown>"
+			}))
+			reshdr := req.Header
+			reshdr.Set("Content-Type", "text/html; charset=utf-8")
+
+			resp := &http.Response{
+				Status:     fmt.Sprintf("%d Bad Gateway", http.StatusBadGateway),
+				StatusCode: http.StatusBadGateway,
+				Body:       ioutil.NopCloser(bytes.NewBuffer(resbody)),
+
+				Proto:         req.Proto,
+				ProtoMajor:    req.ProtoMajor,
+				ProtoMinor:    req.ProtoMinor,
+				Header:        reshdr,
+				ContentLength: len(resbody),
+				Close:         true,
+				Request:       req,
+			}
+
+			return resp, nil
 		}
 	}