Improve TakingNames.io request generation

Before we were pre-generating a DNS request ID every time the
add tunnel page was visited. Now we have a separate endpoint for
generating the IDs only after the user indicates they actually
want to perform a TakingNames.io domain request.

templates/edit_tunnel.tmpl

@@ -5,7 +5,7 @@
      <div class='input'>
        <p>
          Enter a domain below, or automatically configure DNS using
-         <a href='{{$.TakingNamesLink}}'>TakingNames.io</a>
+         <a href='/takingnames'>TakingNames.io</a>
        </p>
        <label for="domain">Domain:</label>
        <input type="text" id="domain" name="domain" value="{{$.Domain}}" required>

ui_handler.go

@@ -160,36 +160,16 @@ func (h *WebUiHandler) handleWebUiRequest(w http.ResponseWriter, r *http.Request
 			users[tokenData.Owner] = user
 		}
 
-		requestId, _ := genRandomCode(32)
-
-		req := DNSRequest{
-			Records: []*DNSRecord{
-				&DNSRecord{
-					Type:  "A",
-					Value: h.config.PublicIp,
-					TTL:   300,
-				},
-			},
-		}
-
-		h.db.SetDNSRequest(requestId, req)
-
-		adminDomain := h.db.GetAdminDomain()
-
-		tnLink := fmt.Sprintf("https://takingnames.io/dnsapi?requester=%s&request-id=%s", adminDomain, requestId)
-
 		templateData := struct {
-			Domain          string
+			Domain string
-			UserId          string
+			UserId string
-			User            User
+			User   User
-			Users           map[string]User
+			Users  map[string]User
-			TakingNamesLink string
 		}{
-			Domain:          domain,
+			Domain: domain,
-			UserId:          tokenData.Owner,
+			UserId: tokenData.Owner,
-			User:            user,
+			User:   user,
-			Users:           users,
+			Users:  users,
-			TakingNamesLink: tnLink,
 		}
 
 		err = h.tmpl.ExecuteTemplate(w, "edit_tunnel.tmpl", templateData)
@@ -266,6 +246,26 @@ func (h *WebUiHandler) handleWebUiRequest(w http.ResponseWriter, r *http.Request
 		message := r.Form.Get("message")
 
 		h.alertDialog(w, r, message, "/")
+	case "/takingnames":
+		requestId, _ := genRandomCode(32)
+
+		req := DNSRequest{
+			Records: []*DNSRecord{
+				&DNSRecord{
+					Type:  "A",
+					Value: h.config.PublicIp,
+					TTL:   300,
+				},
+			},
+		}
+
+		h.db.SetDNSRequest(requestId, req)
+
+		adminDomain := h.db.GetAdminDomain()
+
+		tnLink := fmt.Sprintf("https://takingnames.io/dnsapi?requester=%s&request-id=%s", adminDomain, requestId)
+
+		http.Redirect(w, r, tnLink, 303)
 	default:
 		if strings.HasPrefix(r.URL.Path, "/tunnels/") {