Added IPv6 setting to ovpn3 client API via

ClientAPI::Config::ipv6 string:

  IPv6 preference
    no      -- disable IPv6, so tunnel will be IPv4-only
    yes     -- request combined IPv4/IPv6 tunnel
    default (or empty string) -- leave decision to server

client/ovpncli.cpp

@@ -314,6 +314,7 @@ namespace openvpn {
 	// extra settings submitted by API client
 	std::string server_override;
 	Protocol proto_override;
+	IPv6Setting ipv6;
 	int conn_timeout = 0;
 	bool tun_persist = false;
 	bool google_dns_fallback = false;
@@ -396,6 +397,10 @@ namespace openvpn {
 	if (!config.protoOverride.empty())
 	  Protocol::parse(config.protoOverride, false);
 
+	// validate IPv6 setting
+	if (!config.ipv6.empty())
+	  IPv6Setting::parse(config.ipv6);
+
 	// parse config
 	OptionList::KeyValueList kvl;
 	kvl.reserve(config.contentList.size());
@@ -448,6 +453,8 @@ namespace openvpn {
 	state->private_key_password = config.privateKeyPassword;
 	if (!config.protoOverride.empty())
 	  state->proto_override = Protocol::parse(config.protoOverride, false);
+	if (!config.ipv6.empty())
+	  state->ipv6 = IPv6Setting::parse(config.ipv6);
 	if (!config.compressionMode.empty())
 	  state->proto_context_options->parse_compression_mode(config.compressionMode);
 	if (eval.externalPki)
@@ -641,6 +648,7 @@ namespace openvpn {
 	cc.cli_events = state->events;
 	cc.server_override = state->server_override;
 	cc.proto_override = state->proto_override;
+	cc.ipv6 = state->ipv6;
 	cc.conn_timeout = state->conn_timeout;
 	cc.tun_persist = state->tun_persist;
 	cc.google_dns_fallback = state->google_dns_fallback;

client/ovpncli.hpp

@@ -168,6 +168,12 @@ namespace openvpn {
       // Should be tcp, udp, or adaptive.
       std::string protoOverride;
 
+      // IPv6 preference
+      //  no      -- disable IPv6, so tunnel will be IPv4-only
+      //  yes     -- request combined IPv4/IPv6 tunnel
+      //  default (or empty string) -- leave decision to server
+      std::string ipv6;
+
       // Connection timeout in seconds, or 0 to retry indefinitely
       int connTimeout = 0;
 

openvpn/client/cliopt.hpp

@@ -41,6 +41,7 @@
 #include <openvpn/crypto/cryptodcsel.hpp>
 #include <openvpn/ssl/mssparms.hpp>
 #include <openvpn/tun/tunmtu.hpp>
+#include <openvpn/tun/ipv6_setting.hpp>
 
 #include <openvpn/transport/socket_protect.hpp>
 #include <openvpn/transport/reconnect_notify.hpp>
@@ -114,6 +115,7 @@ namespace openvpn {
       std::string gui_version;
       std::string server_override;
       Protocol proto_override;
+      IPv6Setting ipv6;
       int conn_timeout = 0;
       SessionStats::Ptr cli_stats;
       ClientEvent::Queue::Ptr cli_events;
@@ -229,7 +231,7 @@ namespace openvpn {
       cp->set_xmit_creds(!autologin || pcc.hasEmbeddedPassword() || config.autologin_sessions);
       cp->gui_version = config.gui_version;
       cp->force_aes_cbc_ciphersuites = config.force_aes_cbc_ciphersuites; // also used to disable proto V2
-      cp->extra_peer_info = config.extra_peer_info;
+      cp->extra_peer_info = build_peer_info(config);
       cp->frame = frame;
       cp->now = &now_;
       cp->rng = rng;
@@ -453,7 +455,13 @@ namespace openvpn {
 	// base options where only a single instance of each option makes sense
 	push_base->singleton.extend(opt, "redirect-dns");
 	push_base->singleton.extend(opt, "inactive");
-	push_base->singleton.extend(opt, "block-ipv6");
+
+	// IPv6
+	{
+	  const unsigned int n = push_base->singleton.extend(opt, "block-ipv6");
+	  if (!n && config.ipv6() == IPv6Setting::NO)
+	    push_base->singleton.emplace_back("block-ipv6");
+	}
       }
 
       // show unused options
@@ -461,6 +469,19 @@ namespace openvpn {
 	OPENVPN_LOG("UNUSED OPTIONS" << std::endl << opt.render(Option::RENDER_TRUNC_64|Option::RENDER_NUMBER|Option::RENDER_BRACKET|Option::RENDER_UNUSED));
     }
 
+    static PeerInfo::Set::Ptr build_peer_info(const Config& config)
+    {
+      PeerInfo::Set::Ptr pi = config.extra_peer_info->copy();
+
+      // IPv6
+      if (config.ipv6() == IPv6Setting::NO)
+	pi->emplace_back("IV_IPv6", "0");
+      else if (config.ipv6() == IPv6Setting::YES)
+	pi->emplace_back("IV_IPv6", "1");
+
+      return pi;
+    }
+
     void next()
     {
       bool omit_next = false;

openvpn/tun/ipv6_setting.hpp

@@ -0,0 +1,89 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2015 OpenVPN Technologies, Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    This program is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef OPENVPN_TUN_IPv6_SETTING_H
+#define OPENVPN_TUN_IPv6_SETTING_H
+
+#include <openvpn/common/exception.hpp>
+
+namespace openvpn {
+  class IPv6Setting
+  {
+  public:
+    enum Type {
+      NO,
+      YES,
+      DEFAULT,
+    };
+
+    IPv6Setting()
+    {
+    }
+
+    explicit IPv6Setting(const Type t)
+      : type_(t)
+    {
+    }
+
+    Type operator()() const { return type_; }
+
+    std::string to_string() const
+    {
+      switch (type_)
+	{
+	case NO:
+	  return "no";
+	case YES:
+	  return "yes";
+	case DEFAULT:
+	default:
+	  return "default";
+	}
+    }
+
+    static IPv6Setting parse(const std::string& str)
+    {
+      if (str == "no")
+	return IPv6Setting(NO);
+      else if (str == "yes")
+	return IPv6Setting(YES);
+      else if (str == "default")
+	return IPv6Setting(DEFAULT);
+      else
+	throw Exception("IPv6Setting: unrecognized setting");
+    }
+
+    bool operator==(const IPv6Setting& other) const
+    {
+      return type_ == other.type_;
+    }
+
+    bool operator!=(const IPv6Setting& other) const
+    {
+      return type_ != other.type_;
+    }
+
+  private:
+    Type type_ = DEFAULT;
+  };
+}
+
+#endif

test/ovpncli/cli.cpp

@@ -241,6 +241,7 @@ int openvpn_client(int argc, char *argv[], const std::string* profile_content)
     { "response",       required_argument,  nullptr,      'r' },
     { "dc",             required_argument,  nullptr,      'D' },
     { "proto",          required_argument,  nullptr,      'P' },
+    { "ipv6",           required_argument,  nullptr,      '6' },
     { "server",         required_argument,  nullptr,      's' },
     { "timeout",        required_argument,  nullptr,      't' },
     { "compress",       required_argument,  nullptr,      'c' },
@@ -283,6 +284,7 @@ int openvpn_client(int argc, char *argv[], const std::string* profile_content)
 	std::string response;
 	std::string dynamicChallengeCookie;
 	std::string proto;
+	std::string ipv6;
 	std::string server;
 	int timeout = 0;
 	std::string compress;
@@ -311,7 +313,7 @@ int openvpn_client(int argc, char *argv[], const std::string* profile_content)
 
 	int ch;
 	optind = 1;
-	while ((ch = getopt_long(argc, argv, "BAdeTCxfgjmvau:p:r:D:P:s:t:c:z:M:h:q:U:W:I:G:k:", longopts, nullptr)) != -1)
+	while ((ch = getopt_long(argc, argv, "BAdeTCxfgjmvau:p:r:D:P:6:s:t:c:z:M:h:q:U:W:I:G:k:", longopts, nullptr)) != -1)
 	  {
 	    switch (ch)
 	      {
@@ -339,6 +341,9 @@ int openvpn_client(int argc, char *argv[], const std::string* profile_content)
 	      case 'P':
 		proto = optarg;
 		break;
+	      case '6':
+		ipv6 = optarg;
+		break;
 	      case 's':
 		server = optarg;
 		break;
@@ -459,6 +464,7 @@ int openvpn_client(int argc, char *argv[], const std::string* profile_content)
 	      config.protoOverride = proto;
 	      config.connTimeout = timeout;
 	      config.compressionMode = compress;
+	      config.ipv6 = ipv6;
 	      config.privateKeyPassword = privateKeyPassword;
 	      config.tlsVersionMinOverride = tlsVersionMinOverride;
 	      config.disableClientCert = disableClientCert;
@@ -621,6 +627,7 @@ int openvpn_client(int argc, char *argv[], const std::string* profile_content)
       std::cout << "--dc, -D             : dynamic challenge/response cookie" << std::endl;
       std::cout << "--proto, -P          : protocol override (udp|tcp)" << std::endl;
       std::cout << "--server, -s         : server override" << std::endl;
+      std::cout << "--ipv6, -6           : IPv6 (yes|no|default)" << std::endl;
       std::cout << "--timeout, -t        : timeout" << std::endl;
       std::cout << "--compress, -c       : compression mode (yes|no|asym)" << std::endl;
       std::cout << "--pk-password, -z    : private key password" << std::endl;