Disable custom IP lookup

This adds a flag, `-L` which will disable the ability to do custom IP
lookups.

When `-L` is set we:
- Remove the interactive text input and form elements
- Remove the button(s) related to lookup
- Don't process incoming `?ip=`
- Remove some help text related to the functionality

Author: torkildr

README.md

@@ -142,6 +142,7 @@ Usage of echoip:
         Path to GeoIP country database
   -l string
         Listening address (default ":8080")
+  -L    Disable custom IP lookup
   -p    Enable port lookup
   -r    Perform reverse hostname lookups
   -s    Show sponsor logo

cmd/echoip/main.go

@@ -35,6 +35,7 @@ func main() {
 	listen := flag.String("l", ":8080", "Listening address")
 	reverseLookup := flag.Bool("r", false, "Perform reverse hostname lookups")
 	portLookup := flag.Bool("p", false, "Enable port lookup")
+	noCustomIP := flag.Bool("L", false, "Disable custom IP lookup")
 	template := flag.String("t", "html", "Path to template dir")
 	cacheSize := flag.Int("C", 0, "Size of response cache. Set to 0 to disable")
 	profile := flag.Bool("P", false, "Enables profiling handlers")
@@ -71,6 +72,10 @@ func main() {
 		log.Println("Enabling sponsor logo")
 		server.Sponsor = *sponsor
 	}
+	if *noCustomIP {
+		log.Println("Disabling custom IP lookup")
+		server.NoCustomIP = true
+	}
 	if len(headers) > 0 {
 		log.Printf("Trusting remote IP from header(s): %s", headers.String())
 	}

html/index.html

@@ -31,6 +31,11 @@
         </div>
         {{ end }}
         <h1 class="site-title">❯ curl {{ .Host }}</h1>
+        {{ if .NoCustomIP }}
+        <div class="ip-form">
+          <input class="ip-input" type="text" value="{{ .IP }}" readonly>
+        </div>
+        {{ else }}
         <form class="ip-form" action="/" method="GET">
           <input class="ip-input" type="text" name="ip" value="{{ .IP }}">
           <div class="ip-buttons">
@@ -40,6 +45,7 @@ <h1 class="site-title">❯ curl {{ .Host }}</h1>
             {{ end }}
           </div>
         </form>
+        {{ end }}
         <p class="ip-meta">
           {{- if .City }}{{ .City }}{{ if .Country }}, {{ end }}{{ end -}}
           {{- .Country -}}
@@ -222,7 +228,9 @@ <h3>Plain text</h3>
         <div class="note">
           <ul>
             <li>Set the <code>Accept: application/json</code> header to request response as JSON.</li>
+            {{ if not .NoCustomIP }}
             <li>Append <code>?ip=IP</code> to the request URL to lookup information for a different IP. This is not supported for the <code>/port</code> endpoint.</li>
+            {{ end }}
           </ul>
         </div>
         <h3>JSON</h3>

http/http.go

@@ -35,6 +35,7 @@ type Server struct {
 	gr         geo.Reader
 	profile    bool
 	Sponsor    bool
+	NoCustomIP bool
 }
 
 type Response struct {
@@ -129,7 +130,7 @@ func userAgentFromRequest(r *http.Request) *useragent.UserAgent {
 }
 
 func (s *Server) newResponse(r *http.Request) (Response, error) {
-	ip, err := ipFromRequest(s.IPHeaders, r, true)
+	ip, err := ipFromRequest(s.IPHeaders, r, !s.NoCustomIP)
 	if err != nil {
 		return Response{}, err
 	}
@@ -193,7 +194,7 @@ func (s *Server) newPortResponse(r *http.Request) (PortResponse, error) {
 }
 
 func (s *Server) CLIHandler(w http.ResponseWriter, r *http.Request) *appError {
-	ip, err := ipFromRequest(s.IPHeaders, r, true)
+	ip, err := ipFromRequest(s.IPHeaders, r, !s.NoCustomIP)
 	if err != nil {
 		return badRequest(err).WithMessage(err.Error()).AsJSON()
 	}
@@ -364,6 +365,7 @@ func (s *Server) DefaultHandler(w http.ResponseWriter, r *http.Request) *appErro
 		Port           bool
 		Sponsor        bool
 		ExplicitLookup bool
+		NoCustomIP     bool
 	}{
 		response,
 		r.Host,
@@ -374,7 +376,8 @@ func (s *Server) DefaultHandler(w http.ResponseWriter, r *http.Request) *appErro
 		string(json),
 		s.LookupPort != nil,
 		s.Sponsor,
-		r.URL.Query().Has("ip"),
+		!s.NoCustomIP && r.URL.Query().Has("ip"),
+		s.NoCustomIP,
 	}
 	if err := t.Execute(w, &data); err != nil {
 		return internalServerError(err)