Viewer: Fix issues with IPv6 address handling

- Remove brackets from IPv6 addresses before using them to reference
  Preferences nodes.

- Fix several issues that prevented IPv6 addresses from being used as
  VNC hostnames.

ChangeLog.md

@@ -76,6 +76,9 @@ specified and the session desktop file for the window manager cannot be found.
 13. Fixed a regression introduced by 3.0 beta1[24] that caused the TurboVNC
 Server to leak memory when the RFB flow control extensions were used.
 
+14. Fixed several issues in the TurboVNC Viewer that prevented IPv6 addresses
+from being used as VNC hostnames.
+
 
 3.0.3
 =====

java/com/turbovnc/rfb/Hostname.java

@@ -1,4 +1,5 @@
-/* Copyright (C) 2012, 2016, 2018, 2020 D. R. Commander. All Rights Reserved.
+/* Copyright (C) 2012, 2016, 2018, 2020, 2023-2024 D. R. Commander.
+ * All Rights Reserved.
  * Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
  *
  * This is free software; you can redistribute it and/or modify
@@ -23,27 +24,56 @@
 
 public final class Hostname {
 
- public static String getHost(String vncServerName) {
+ // Find the position of the first colon in the display number/port portion of
+ // the VNC server name.
+
+ public static int getColonPos(String vncServerName) {
  int colonPos = vncServerName.lastIndexOf(':');
  int bracketPos = vncServerName.lastIndexOf(']');
- boolean doubleColon = false;
 
+ // No colon = hostname only
+ if (colonPos == -1)
+ return -1;
+ // Last colon is inside square brackets = IPv6 address only
  if (bracketPos != -1 && colonPos < bracketPos)
- colonPos = -1;
- while (colonPos > 0 && vncServerName.charAt(colonPos - 1) == ':') {
+ return -1;
+ // If the last colon is part of a series, then find the first colon in the
+ // series.
+ while (colonPos > 0 && vncServerName.charAt(colonPos - 1) == ':')
  colonPos--;
- doubleColon = true;
+ if (colonPos == 0) {
+ // IPv6 loopback address only (special case)
+ if (vncServerName.equals("::1"))
+ return -1;
+ // Display number/port specified without host
+ return colonPos;
  }
- if (doubleColon) {
- // Check for preceding single colon, indicating an IPv6 address
- for (int p = colonPos - 1; p >= 0; p--) {
- if (vncServerName.charAt(p) == ':') {
- if (p == 0 || vncServerName.charAt(p - 1) != ':')
- colonPos = -1;
- break;
- }
- }
+ // Display number/port specified with bracketed IPv6 address
+ if (bracketPos != -1 && colonPos - 1 == bracketPos)
+ return colonPos;
+
+ // Check for preceding colons, indicating an IPv6 address.
+ int colonCount = 0, p = colonPos;
+ while ((p = vncServerName.lastIndexOf(':', p - 1)) > 0) {
+ // Double colon = abbreviated IPv6 address
+ if (vncServerName.charAt(p - 1) == ':')
+ return colonPos;
+ colonCount++;
+ // 7 colons = full IPv6 address
+ if (colonCount >= 7)
+ return colonPos;
  }
+ // Invalid format (IPv6 address is incomplete or hostname contains colons)
+ if (colonCount > 0)
+ return -1;
+
+ // Display number/port specified with hostname
+ return colonPos;
+ }
+
+ public static String getHost(String vncServerName) {
+ int colonPos = getColonPos(vncServerName);
+
  if (colonPos == 0)
  return "localhost";
  if (colonPos == -1)
@@ -52,26 +82,8 @@ public static String getHost(String vncServerName) {
  }
 
  public static int getPort(String vncServerName) {
- int colonPos = vncServerName.lastIndexOf(':');
- int bracketPos = vncServerName.lastIndexOf(']');
- boolean doubleColon = false;
+ int colonPos = getColonPos(vncServerName);
 
- if (bracketPos != -1 && colonPos < bracketPos)
- colonPos = -1;
- while (colonPos > 0 && vncServerName.charAt(colonPos - 1) == ':') {
- colonPos--;
- doubleColon = true;
- }
- if (doubleColon) {
- // Check for preceding single colon, indicating an IPv6 address
- for (int p = colonPos - 1; p >= 0; p--) {
- if (vncServerName.charAt(p) == ':') {
- if (p == 0 || vncServerName.charAt(p - 1) != ':')
- colonPos = -1;
- break;
- }
- }
- }
  if (colonPos == -1 || colonPos == vncServerName.length() - 1)
  return Utils.getBooleanProperty("turbovnc.sessmgr", true) ? 0 : 5900;
  if (vncServerName.charAt(colonPos + 1) == ':') {

java/com/turbovnc/vncviewer/CConn.java

@@ -103,7 +103,7 @@ public CConn(VncViewer viewer_, Socket sock_) {
 
  if (opts.serverName != null &&
  !Params.alwaysShowConnectionDialog.getValue()) {
- if (opts.via == null || opts.via.indexOf(':') < 0) {
+ if (opts.via == null || Hostname.getColonPos(opts.via) < 0) {
  port = opts.port = Hostname.getPort(opts.serverName);
  serverName = opts.serverName = Hostname.getHost(opts.serverName);
  }
@@ -118,7 +118,7 @@ public CConn(VncViewer viewer_, Socket sock_) {
  serverName = opts.serverName;
  }
 
- if (opts.via != null && opts.via.indexOf(':') >= 0) {
+ if (opts.via != null && Hostname.getColonPos(opts.via) >= 0) {
  port = Hostname.getPort(opts.via);
  serverName = Hostname.getHost(opts.via);
  } else if (opts.via != null || opts.tunnel ||

java/com/turbovnc/vncviewer/ServerDialog.java

@@ -222,7 +222,7 @@ private boolean commit() {
  throw new WarningException("No server name specified");
 
  // set params
- if (opts.via != null && opts.via.indexOf(':') >= 0) {
+ if (opts.via != null && Hostname.getColonPos(opts.via) >= 0) {
  opts.serverName = serverName;
  } else {
  int atIndex = serverName.lastIndexOf('@');

java/com/turbovnc/vncviewer/Tunnel.java

@@ -1,4 +1,4 @@
-/* Copyright (C) 2012-2015, 2017-2018, 2020-2023 D. R. Commander.
+/* Copyright (C) 2012-2015, 2017-2018, 2020-2024 D. R. Commander.
  * All Rights Reserved.
  * Copyright (C) 2012, 2016 Brian P. Hinz. All Rights Reserved.
  * Copyright (C) 2000 Const Kaplinsky. All Rights Reserved.
@@ -61,7 +61,7 @@ public static void createTunnel(Options opts) throws Exception {
  gatewayHost = opts.via;
  remoteHost = Hostname.getHost(opts.serverName);
  }
- if (opts.serverName != null && opts.serverName.indexOf(':') < 0 &&
+ if (opts.serverName != null && Hostname.getColonPos(opts.serverName) < 0 &&
  opts.port > 0)
  remotePort = opts.port;
  else
@@ -85,6 +85,7 @@ public static void createTunnel(Options opts) throws Exception {
  vlog.debug("Opening SSH tunnel through gateway " + gatewayHost);
  if (opts.sshSession == null)
  createTunnelJSch(gatewayHost, opts);
+ remoteHost = remoteHost.replaceAll("[\\[\\]]", "");
  vlog.debug("Forwarding local port " + localPort + " to " + remoteHost +
  ":" + remotePort + " (relative to gateway)");
  opts.sshSession.setPortForwardingL(localPort, remoteHost, remotePort);

java/com/turbovnc/vncviewer/VncViewer.java

@@ -625,8 +625,7 @@ public static void tileWindows() {
  public void start() {
  vlog.debug("start called");
  String host = opts.serverName;
- if (host != null && host.indexOf(':') < 0 &&
- opts.port > 0) {
+ if (host != null && Hostname.getColonPos(host) < 0 && opts.port > 0) {
  opts.serverName = host + ((opts.port >= 5900 && opts.port <= 5999) ?
  (":" + (opts.port - 5900)) : ("::" + opts.port));
  }