Merge tag 'upstream/2.4_rc1'

Upstream version 2.4~rc1

29 files changed, 581 insertions, 204 deletions

diff --git a/src/openvpn/Makefile.in b/src/openvpn/Makefile.in
index ff15d6d..9ef9b28 100644
--- a/src/openvpn/Makefile.in
+++ b/src/openvpn/Makefile.in
@@ -1,4 +1,4 @@
-# Makefile.in generated by automake 1.13.4 from Makefile.am.
+# Makefile.in generated by automake 1.14.1 from Makefile.am.
 # @configure_input@
 
 # Copyright (C) 1994-2013 Free Software Foundation, Inc.
@@ -655,14 +655,14 @@ distclean-compile:
 @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/$*.Tpo $(DEPDIR)/$*.Po
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='$<' object='$@' libtool=no @AMDEPBACKSLASH@
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
-@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(COMPILE) -c $<
+@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(COMPILE) -c -o $@ $<
 
 .c.obj:
 @am__fastdepCC_TRUE@	$(AM_V_CC)$(COMPILE) -MT $@ -MD -MP -MF $(DEPDIR)/$*.Tpo -c -o $@ `$(CYGPATH_W) '$<'`
 @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/$*.Tpo $(DEPDIR)/$*.Po
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='$<' object='$@' libtool=no @AMDEPBACKSLASH@
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
-@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(COMPILE) -c `$(CYGPATH_W) '$<'`
+@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(COMPILE) -c -o $@ `$(CYGPATH_W) '$<'`
 
 .c.lo:
 @am__fastdepCC_TRUE@	$(AM_V_CC)$(LTCOMPILE) -MT $@ -MD -MP -MF $(DEPDIR)/$*.Tpo -c -o $@ $<
diff --git a/src/openvpn/basic.h b/src/openvpn/basic.h
index 298cf10..48d4d9b 100644
--- a/src/openvpn/basic.h
+++ b/src/openvpn/basic.h
@@ -30,7 +30,7 @@
 /* size of an array */
 #define SIZE(x) (sizeof(x)/sizeof(x[0]))
 
-/* clear an object */
+/* clear an object (may be optimized away, use secure_memzero() to erase secrets) */
 #define CLEAR(x) memset(&(x), 0, sizeof(x))
 
 #define IPV4_NETMASK_HOST 0xffffffffU
diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c
index 52c6ab9..6af8dbb 100644
--- a/src/openvpn/buffer.c
+++ b/src/openvpn/buffer.c
@@ -155,7 +155,9 @@ void
 buf_clear (struct buffer *buf)
 {
   if (buf->capacity > 0)
-    memset (buf->data, 0, buf->capacity);
+    {
+      secure_memzero (buf->data, buf->capacity);
+    }
   buf->len = 0;
   buf->offset = 0;
 }
@@ -438,13 +440,16 @@ format_hex_ex (const uint8_t *data, int size, int maxoutput,
 	       unsigned int space_break_flags, const char* separator,
 	       struct gc_arena *gc)
 {
-  struct buffer out = alloc_buf_gc (maxoutput ? maxoutput :
-				    ((size * 2) + (size / (space_break_flags & FHE_SPACE_BREAK_MASK)) * (int) strlen (separator) + 2),
-				    gc);
-  int i;
-  for (i = 0; i < size; ++i)
+  const size_t bytes_per_hexblock = space_break_flags & FHE_SPACE_BREAK_MASK;
+  const size_t separator_len = separator ? strlen (separator) : 0;
+  static_assert (INT_MAX <= SIZE_MAX, "Code assumes INT_MAX <= SIZE_MAX");
+  const size_t out_len = maxoutput > 0 ? maxoutput :
+	    ((size * 2) + ((size / bytes_per_hexblock) * separator_len) + 2);
+
+  struct buffer out = alloc_buf_gc (out_len, gc);
+  for (int i = 0; i < size; ++i)
     {
-      if (separator && i && !(i % (space_break_flags & FHE_SPACE_BREAK_MASK)))
+      if (separator && i && !(i % bytes_per_hexblock))
 	buf_printf (&out, "%s", separator);
       if (space_break_flags & FHE_CAPS)
 	buf_printf (&out, "%02X", data[i]);
@@ -616,9 +621,7 @@ string_clear (char *str)
 {
   if (str)
     {
-      const int len = strlen (str);
-      if (len > 0)
-	memset (str, 0, len);
+      secure_memzero (str, strlen (str));
     }
 }
 
diff --git a/src/openvpn/buffer.h b/src/openvpn/buffer.h
index 8070439..7747003 100644
--- a/src/openvpn/buffer.h
+++ b/src/openvpn/buffer.h
@@ -328,6 +328,49 @@ has_digit (const unsigned char* src)
   return false;
 }
 
+/**
+ * Securely zeroise memory.
+ *
+ * This code and description are based on code supplied by Zhaomo Yang, of the
+ * University of California, San Diego (which was released into the public
+ * domain).
+ *
+ * The secure_memzero function attempts to ensure that an optimizing compiler
+ * does not remove the intended operation if cleared memory is not accessed
+ * again by the program. This code has been tested under Clang 3.9.0 and GCC
+ * 6.2 with optimization flags -O, -Os, -O0, -O1, -O2, and -O3 on
+ * Ubuntu 16.04.1 LTS; under Clang 3.9.0 with optimization flags -O, -Os,
+ * -O0, -O1, -O2, and -O3 on FreeBSD 10.2-RELEASE; under Microsoft Visual Studio
+ * 2015 with optimization flags /O1, /O2 and /Ox on Windows 10.
+ *
+ * Theory of operation:
+ *
+ * 1. On Windows, use the SecureZeroMemory which ensures that data is
+ *    overwritten.
+ * 2. Under GCC or Clang, use a memory barrier, which forces the preceding
+ *    memset to be carried out. The overhead of a memory barrier is usually
+ *    negligible.
+ * 3. If none of the above are available, use the volatile pointer
+ *    technique to zero memory one byte at a time.
+ *
+ * @param data	Pointer to data to zeroise.
+ * @param len	Length of data, in bytes.
+ */
+static inline void
+secure_memzero (void *data, size_t len)
+{
+#if defined(_WIN32)
+  SecureZeroMemory (data, len);
+#elif defined(__GNUC__) || defined(__clang__)
+  memset(data, 0, len);
+  __asm__ __volatile__("" : : "r"(data) : "memory");
+#else
+  volatile char *p = (volatile char *) data;
+  while (len--)
+    *p++ = 0;
+#endif
+}
+
 /*
  * printf append to a buffer with overflow check,
  * due to usage of vsnprintf, it will leave space for
diff --git a/src/openvpn/console_builtin.c b/src/openvpn/console_builtin.c
index 6b0211d..06994fd 100644
--- a/src/openvpn/console_builtin.c
+++ b/src/openvpn/console_builtin.c
@@ -218,7 +218,7 @@ static bool get_console_input (const char *prompt, const bool echo, char *input,
         if (gp)
         {
             strncpynt (input, gp, capacity);
-            memset (gp, 0, strlen (gp));
+            secure_memzero (gp, strlen (gp));
             ret = true;
         }
     }
diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
index 05622ce..708cc92 100644
--- a/src/openvpn/crypto.c
+++ b/src/openvpn/crypto.c
@@ -86,12 +86,11 @@ openvpn_encrypt_aead (struct buffer *buf, struct buffer work,
   {
     struct buffer iv_buffer;
     struct packet_id_net pin;
-    uint8_t iv[OPENVPN_MAX_IV_LENGTH];
+    uint8_t iv[OPENVPN_MAX_IV_LENGTH] = {0};
     const int iv_len = cipher_ctx_iv_length (ctx->cipher);
 
     ASSERT (iv_len >= OPENVPN_AEAD_MIN_IV_LEN && iv_len <= OPENVPN_MAX_IV_LENGTH);
 
-    memset(iv, 0, sizeof(iv));
     buf_set_write (&iv_buffer, iv, iv_len);
 
     /* IV starts with packet id to make the IV unique for packet */
@@ -175,7 +174,7 @@ openvpn_encrypt_v1 (struct buffer *buf, struct buffer work,
       /* Do Encrypt from buf -> work */
       if (ctx->cipher)
 	{
-	  uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH];
+	  uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH] = {0};
 	  const int iv_size = cipher_ctx_iv_length (ctx->cipher);
 	  const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt (ctx->cipher);
 	  int outlen;
@@ -190,8 +189,6 @@ openvpn_encrypt_v1 (struct buffer *buf, struct buffer work,
 
 	  if (cipher_kt_mode_cbc(cipher_kt))
 	    {
-	      CLEAR (iv_buf);
-
 	      /* generate pseudo-random IV */
 	      if (opt->flags & CO_USE_IV)
 		prng_bytes (iv_buf, iv_size);
@@ -214,7 +211,6 @@ openvpn_encrypt_v1 (struct buffer *buf, struct buffer work,
 	      ASSERT (packet_id_initialized(&opt->packet_id));
 
 	      packet_id_alloc_outgoing (&opt->packet_id.send, &pin, true);
-	      memset (iv_buf, 0, iv_size);
 	      buf_set_write (&b, iv_buf, iv_size);
 	      ASSERT (packet_id_write (&pin, &b, true, false));
 	    }
@@ -550,14 +546,13 @@ openvpn_decrypt_v1 (struct buffer *buf, struct buffer work,
 	{
 	  const int iv_size = cipher_ctx_iv_length (ctx->cipher);
 	  const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt (ctx->cipher);
-	  uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH];
+	  uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH] = { 0 };
 	  int outlen;
 
 	  /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
 	  ASSERT (buf_init (&work, FRAME_HEADROOM_ADJ (frame, FRAME_HEADROOM_MARKER_DECRYPT)));
 
 	  /* use IV if user requested it */
-	  CLEAR (iv_buf);
 	  if (opt->flags & CO_USE_IV)
 	    {
 	      if (buf->len < iv_size)
@@ -1128,7 +1123,7 @@ crypto_read_openvpn_key (const struct key_type *key_type,
   init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], key_type,
 		OPENVPN_OP_DECRYPT, log_prefix);
 
-  CLEAR (key2);
+  secure_memzero (&key2, sizeof (key2));
 }
 
 /* header and footer for static key file */
@@ -1380,8 +1375,8 @@ write_key_file (const int nkeys, const char *filename)
       buf_printf (&out, "%s\n", fmt);
 
       /* zero memory which held key component (will be freed by GC) */
-      memset (fmt, 0, strlen(fmt));
-      CLEAR (key);
+      secure_memzero (fmt, strlen (fmt));
+      secure_memzero (&key, sizeof (key));
     }
 
   buf_printf (&out, "%s\n", static_key_foot);
diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index 1ea06bb..306b6c6 100644
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -47,6 +47,7 @@
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/objects.h>
+#include <openssl/rand.h>
 #include <openssl/ssl.h>
 
 /*
diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index 470dc89..74f1139 100644
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -30,6 +30,10 @@
 
 #include "syshead.h"
 
+#ifdef ENABLE_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 #include "win32.h"
 #include "init.h"
 #include "sig.h"
@@ -926,6 +930,13 @@ bool
 possibly_become_daemon (const struct options *options)
 {
   bool ret = false;
+
+#ifdef ENABLE_SYSTEMD
+  /* return without forking if we are running from systemd */
+  if (sd_notify(0, "READY=0") > 0)
+    return ret;
+#endif
+
   if (options->daemon)
     {
       ASSERT (!options->inetd);
@@ -1251,11 +1262,19 @@ initialization_sequence_completed (struct context *c, const unsigned int flags)
       show_adapters (M_INFO|M_NOPREFIX);
       msg (M_INFO, "%s With Errors ( see http://openvpn.net/faq.html#dhcpclientserv )", message);
 #else
+#ifdef ENABLE_SYSTEMD
+      sd_notifyf(0, "STATUS=Failed to start up: %s With Errors\nERRNO=1", message);
+#endif /* HAVE_SYSTEMD_SD_DAEMON_H */
       msg (M_INFO, "%s With Errors", message);
 #endif
     }
   else
-    msg (M_INFO, "%s", message);
+    {
+#ifdef ENABLE_SYSTEMD
+      sd_notifyf(0, "READY=1\nSTATUS=%s\nMAINPID=%lu", message, (unsigned long) getpid());
+#endif
+      msg (M_INFO, "%s", message);
+    }
 
   /* Flag that we initialized */
   if ((flags & (ISC_ERRORS|ISC_SERVER)) == 0)
@@ -1932,8 +1951,14 @@ do_deferred_options (struct context *c, const unsigned int found)
     {
       struct tls_session *session = &c->c2.tls_multi->session[TM_ACTIVE];
       if (found & OPT_P_NCP)
-	msg (D_PUSH, "OPTIONS IMPORT: data channel crypto options modified");
-      /* Do not regenerate keys if server sends an extra push request */
+	{
+	  msg (D_PUSH, "OPTIONS IMPORT: data channel crypto options modified");
+	}
+      else if (c->options.ncp_enabled)
+	{
+	  tls_poor_mans_ncp(&c->options, c->c2.tls_multi->remote_ciphername);
+	}
+      /* Do not regenerate keys if server sends an extra push reply */
       if (!session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized &&
 	  !tls_session_update_crypto_params(session, &c->options, &c->c2.frame))
 	{
diff --git a/src/openvpn/manage.c b/src/openvpn/manage.c
index 77a8006..4918ed2 100644
--- a/src/openvpn/manage.c
+++ b/src/openvpn/manage.c
@@ -3154,7 +3154,7 @@ management_query_user_pass (struct management *man,
 	  man->connection.up_query.nocache = up->nocache; /* preserve caller's nocache setting */
 	  *up = man->connection.up_query;
 	}
-      CLEAR (man->connection.up_query);
+      secure_memzero (&man->connection.up_query, sizeof (man->connection.up_query));
     }
 
   gc_free (&gc);
diff --git a/src/openvpn/misc.c b/src/openvpn/misc.c
index 56d43e0..4e06c91 100644
--- a/src/openvpn/misc.c
+++ b/src/openvpn/misc.c
@@ -501,7 +501,7 @@ remove_env_item (const char *str, const bool do_free, struct env_item **list)
 	    *list = current->next;
 	  if (do_free)
 	    {
-	      memset (current->string, 0, strlen (current->string));
+	      secure_memzero (current->string, strlen (current->string));
 	      free (current->string);
 	      free (current);
 	    }
@@ -1342,7 +1342,7 @@ purge_user_pass (struct user_pass *up, const bool force)
   static bool warn_shown = false;
   if (nocache || force)
     {
-      CLEAR (*up);
+      secure_memzero (up, sizeof(*up));
       up->nocache = nocache;
     }
   else if (!warn_shown)
diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 8f3d34e..4fc8b02 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -2317,6 +2317,10 @@ void multi_process_float (struct multi_context* m, struct multi_instance* mi)
 	mroute_addr_print (&mi->real, &gc),
 	print_link_socket_actual (&m->top.c2.from, &gc));
 
+    /* remove old address from hash table before changing address */
+    ASSERT (hash_remove (m->hash, &mi->real));
+    ASSERT (hash_remove (m->iter, &mi->real));
+
     /* change external network address of the remote peer */
     mi->real = real;
     generate_prefix (mi);
@@ -2330,8 +2334,8 @@ void multi_process_float (struct multi_context* m, struct multi_instance* mi)
 
     tls_update_remote_addr (mi->context.c2.tls_multi, &mi->context.c2.from);
 
-    ASSERT (hash_add (m->hash, &mi->real, mi, true));
-    ASSERT (hash_add (m->iter, &mi->real, mi, true));
+    ASSERT (hash_add (m->hash, &mi->real, mi, false));
+    ASSERT (hash_add (m->iter, &mi->real, mi, false));
 
 #ifdef MANAGEMENT_DEF_AUTH
     ASSERT (hash_add (m->cid_hash, &mi->context.c2.mda_context.cid, mi, true));
diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index 7f128c3..47acd97 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -704,7 +704,8 @@ static const char usage_message[] =
   "                    which allow multiple addresses,\n"
   "                    --dhcp-option must be repeated.\n"
   "                    DOMAIN name : Set DNS suffix\n"
-  "                    DNS addr    : Set domain name server address(es)\n"
+  "                    DNS addr    : Set domain name server address(es) (IPv4)\n"
+  "                    DNS6 addr   : Set domain name server address(es) (IPv6)\n"
   "                    NTP         : Set NTP server address(es)\n"
   "                    NBDD        : Set NBDD server address(es)\n"
   "                    WINS addr   : Set WINS server address(es)\n"
@@ -716,8 +717,8 @@ static const char usage_message[] =
   "--dhcp-pre-release : Ask Windows to release the previous TAP adapter lease on\n"
 "                       startup.\n"
   "--dhcp-release     : Ask Windows to release the TAP adapter lease on shutdown.\n"
-  "--register-dns  : Run net stop dnscache, net start dnscache, ipconfig /flushdns\n"
-  "                  and ipconfig /registerdns on connection initiation.\n"
+  "--register-dns  : Run ipconfig /flushdns and ipconfig /registerdns\n"
+  "                  on connection initiation.\n"
   "--tap-sleep n   : Sleep for n seconds after TAP adapter open before\n"
   "                  attempting to set adapter properties.\n"
   "--pause-exit         : When run from a console window, pause before exiting.\n"
@@ -1642,6 +1643,8 @@ show_settings (const struct options *o)
   SHOW_STR (shared_secret_file);
   SHOW_INT (key_direction);
   SHOW_STR (ciphername);
+  SHOW_BOOL (ncp_enabled);
+  SHOW_STR (ncp_ciphers);
   SHOW_STR (authname);
   SHOW_STR (prng_hash);
   SHOW_INT (prng_nonce_secret_len);
@@ -2523,6 +2526,22 @@ options_postprocess_mutate_ce (struct options *o, struct connection_entry *ce)
 
 }
 
+#ifdef _WIN32
+/* If iservice is in use, we need def1 method for redirect-gateway */
+static void
+remap_redirect_gateway_flags (struct options *opt)
+{
+  if (opt->routes
+      && opt->route_method == ROUTE_METHOD_SERVICE
+      && opt->routes->flags & RG_REROUTE_GW
+      && !(opt->routes->flags & RG_DEF1))
+    {
+      msg (M_INFO, "Flag 'def1' added to --redirect-gateway (iservice is in use)");
+      opt->routes->flags |= RG_DEF1;
+    }
+}
+#endif
+
 static void
 options_postprocess_mutate_invariant (struct options *options)
 {
@@ -2552,6 +2571,8 @@ options_postprocess_mutate_invariant (struct options *options)
       options->tuntap_options.ip_win32_type = IPW32_SET_MANUAL;
       options->ifconfig_noexec = false;
     }
+
+  remap_redirect_gateway_flags (options);
 #endif
 
 #if P2MP_SERVER
@@ -3444,6 +3465,36 @@ options_string_version (const char* s, struct gc_arena *gc)
 
 #endif /* ENABLE_OCC */
 
+char *
+options_string_extract_option (const char *options_string,const char *opt_name,
+    struct gc_arena *gc)
+{
+  char *ret = NULL;
+  const size_t opt_name_len = strlen(opt_name);
+
+  const char *p = options_string;
+  while (p)
+    {
+      if (0 == strncmp(p, opt_name, opt_name_len) &&
+	  strlen(p) > (opt_name_len+1) && p[opt_name_len] == ' ')
+	{
+	  /* option found, extract value */
+	  const char *start = &p[opt_name_len+1];
+	  const char *end = strchr (p, ',');
+	  size_t val_len = end ? end - start : strlen (start);
+	  ret = gc_malloc (val_len+1, true, gc);
+	  memcpy (ret, start, val_len);
+	  break;
+	}
+      p = strchr (p, ',');
+      if (p)
+	{
+	  p++; /* skip delimiter */
+	}
+    }
+  return ret;
+}
+
 static void
 foreign_option (struct options *o, char *argv[], int len, struct env_set *es)
 {
@@ -3652,7 +3703,7 @@ usage_version (void)
   show_windows_version( M_INFO|M_NOPREFIX );
 #endif
   msg (M_INFO|M_NOPREFIX, "Originally developed by James Yonan");
-  msg (M_INFO|M_NOPREFIX, "Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>");
+  msg (M_INFO|M_NOPREFIX, "Copyright (C) 2002-2016 OpenVPN Technologies, Inc. <sales@openvpn.net>");
 #ifndef ENABLE_SMALL
 #ifdef CONFIGURE_DEFINES
   msg (M_INFO|M_NOPREFIX, "Compile time defines: %s", CONFIGURE_DEFINES);
@@ -3935,7 +3986,7 @@ read_inline_file (struct in_src *is, const char *close_tag, struct gc_arena *gc)
   ret = string_alloc (BSTR (&buf), gc);
   buf_clear (&buf);
   free_buf (&buf);
-  CLEAR (line);
+  secure_memzero (line, sizeof (line));
   return ret;
 }
 
@@ -4050,7 +4101,7 @@ read_config_file (struct options *options,
     {
       msg (msglevel, "In %s:%d: Maximum recursive include levels exceeded in include attempt of file %s -- probably you have a configuration file that tries to include itself.", top_file, top_line, file);
     }
-  CLEAR (line);
+  secure_memzero (line, sizeof (line));
   CLEAR (p);
 }
 
@@ -4082,7 +4133,7 @@ read_config_string (const char *prefix,
 	}
       CLEAR (p);
     }
-  CLEAR (line);
+  secure_memzero (line, sizeof (line));
 }
 
 void
@@ -4374,6 +4425,8 @@ add_option (struct options *options,
    */
   if (streq (p[0], "setenv") && p[1] && streq (p[1], "opt") && !(permission_mask & OPT_P_PULL_MODE))
     {
+      if (!p[2])
+        p[2] = "setenv opt"; /* will trigger an error that includes setenv opt */
       p += 2;
       msglevel_fc = M_WARN;
     }
@@ -5672,6 +5725,10 @@ add_option (struct options *options,
 	      goto err;
 	    }
 	}
+#ifdef _WIN32
+      /* we need this here to handle pushed --redirect-gateway */
+      remap_redirect_gateway_flags (options);
+#endif
       options->routes->flags |= RG_ENABLE;
     }
   else if (streq (p[0], "remote-random-hostname") && !p[1])
@@ -6406,6 +6463,20 @@ add_option (struct options *options,
 	{
 	  dhcp_option_address_parse ("DNS", p[2], o->dns, &o->dns_len, msglevel);
 	}
+      else if (streq (p[1], "DNS6") && p[2] && ipv6_addr_safe(p[2]))
+	{
+	  struct in6_addr addr;
+	  foreign_option (options, p, 3, es);
+	  if (o->dns6_len >= N_DHCP_ADDR)
+	    {
+	      msg (msglevel, "--dhcp-option DNS6: maximum of %d dns servers can be specified",
+		   N_DHCP_ADDR);
+	    }
+	  else if (get_ipv6_addr (p[2], &addr, NULL, msglevel))
+	    {
+	      o->dns6[o->dns6_len++] = addr;
+	    }
+	}
       else if (streq (p[1], "WINS") && p[2])
 	{
 	  dhcp_option_address_parse ("WINS", p[2], o->wins, &o->wins_len, msglevel);
@@ -6427,7 +6498,14 @@ add_option (struct options *options,
 	  msg (msglevel, "--dhcp-option: unknown option type '%s' or missing or unknown parameter", p[1]);
 	  goto err;
 	}
-      o->dhcp_options = true;
+
+      /* flag that we have options to give to the TAP driver's DHCPv4 server
+       *  - skipped for "DNS6", as that's not a DHCPv4 option
+       */
+      if (!streq (p[1], "DNS6"))
+	{
+	  o->dhcp_options = true;
+	}
     }
 #endif
 #ifdef _WIN32
diff --git a/src/openvpn/options.h b/src/openvpn/options.h
index a028556..067728a 100644
--- a/src/openvpn/options.h
+++ b/src/openvpn/options.h
@@ -726,6 +726,20 @@ void options_warning (char *actual, const char *expected);
 
 #endif
 
+/**
+ * Given an OpenVPN options string, extract the value of an option.
+ *
+ * @param options_string	Zero-terminated, comma-separated options string
+ * @param opt_name		The name of the option to extract
+ * @param gc			The gc to allocate the return value
+ *
+ * @return gc-allocated value of option with name opt_name if option was found,
+ *         or NULL otherwise.
+ */
+char *options_string_extract_option (const char *options_string,
+    const char *opt_name, struct gc_arena *gc);
+
+
 void options_postprocess (struct options *options);
 
 void pre_pull_save (struct options *o);
diff --git a/src/openvpn/push.c b/src/openvpn/push.c
index f86bdd3..9953079 100644
--- a/src/openvpn/push.c
+++ b/src/openvpn/push.c
@@ -42,31 +42,6 @@
 
 static char push_reply_cmd[] = "PUSH_REPLY";
 
-/**
- * Add an option to the given push list by providing a format string.
- *
- * The string added to the push options is allocated in o->gc, so the caller
- * does not have to preserve anything.
- *
- * @param gc        GC arena where options are allocated
- * @param push_list Push list containing options
- * @param msglevel  The message level to use when printing errors
- * @param fmt       Format string for the option
- * @param ...       Format string arguments
- *
- * @return true on success, false on failure.
- */
-static bool push_option_fmt(struct gc_arena *gc, struct push_list *push_list,
-			    int msglevel, const char *fmt, ...)
-#ifdef __GNUC__
-#if __USE_MINGW_ANSI_STDIO
-    __attribute__ ((format (gnu_printf, 4, 5)))
-#else
-    __attribute__ ((format (__printf__, 4, 5)))
-#endif
-#endif
-    ;
-
 /*
  * Auth username/password
  *
@@ -177,6 +152,30 @@ server_pushed_signal (struct context *c, const struct buffer *buffer, const bool
 }
 
 #if P2MP_SERVER
+/**
+ * Add an option to the given push list by providing a format string.
+ *
+ * The string added to the push options is allocated in o->gc, so the caller
+ * does not have to preserve anything.
+ *
+ * @param gc        GC arena where options are allocated
+ * @param push_list Push list containing options
+ * @param msglevel  The message level to use when printing errors
+ * @param fmt       Format string for the option
+ * @param ...       Format string arguments
+ *
+ * @return true on success, false on failure.
+ */
+static bool push_option_fmt(struct gc_arena *gc, struct push_list *push_list,
+			    int msglevel, const char *fmt, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+    __attribute__ ((format (gnu_printf, 4, 5)))
+#else
+    __attribute__ ((format (__printf__, 4, 5)))
+#endif
+#endif
+    ;
 
 /*
  * Send auth failed message from server to client.
@@ -263,7 +262,7 @@ incoming_push_message (struct context *c, const struct buffer *buffer)
 	      !tls_session_update_crypto_params (session, &c->options,
 		  &c->c2.frame))
 	    {
-	      msg (D_TLS_ERRORS, "TLS Error: server generate_key_expansion failed");
+	      msg (D_TLS_ERRORS, "TLS Error: initializing data channel failed");
 	      goto error;
 	    }
 	}
@@ -371,6 +370,10 @@ prepare_push_reply (struct context *c, struct gc_arena *gc,
 	  push_option_fmt(gc, push_list, M_USAGE, "cipher %s", o->ciphername);
 	}
     }
+  else if (o->ncp_enabled)
+    {
+      tls_poor_mans_ncp (o, tls_multi->remote_ciphername);
+    }
 
   /* If server uses --auth-gen-token and we have an auth token
    * to send to the client
diff --git a/src/openvpn/push.h b/src/openvpn/push.h
index d6cb4b1..1dfd80e 100644
--- a/src/openvpn/push.h
+++ b/src/openvpn/push.h
@@ -51,10 +51,9 @@ void receive_auth_failed (struct context *c, const struct buffer *buffer);
 
 void server_pushed_signal (struct context *c, const struct buffer *buffer, const bool restart, const int adv);
 
-#if P2MP_SERVER
-
 void incoming_push_message (struct context *c, const struct buffer *buffer);
 
+#if P2MP_SERVER
 void clone_push_list (struct options *o);
 
 void push_option (struct options *o, const char *opt, int msglevel);
diff --git a/src/openvpn/sig.c b/src/openvpn/sig.c
index 0ff1437..b3ae645 100644
--- a/src/openvpn/sig.c
+++ b/src/openvpn/sig.c
@@ -378,7 +378,8 @@ process_sigterm (struct context *c)
 
 /**
  * If a restart signal is received during exit-notification, reset the
- * signal and return true.
+ * signal and return true. If its a soft restart signal from the event loop
+ * which implies the loop cannot continue, remap to SIGTERM to exit promptly.
  */
 static bool
 ignore_restart_signals (struct context *c)
@@ -388,10 +389,20 @@ ignore_restart_signals (struct context *c)
   if ( (c->sig->signal_received == SIGUSR1 || c->sig->signal_received == SIGHUP) &&
         event_timeout_defined(&c->c2.explicit_exit_notification_interval) )
     {
-       msg (M_INFO, "Ignoring %s received during exit notification",
-            signal_name(c->sig->signal_received, true));
-       signal_reset (c->sig);
-       ret = true;
+       if (c->sig->source == SIG_SOURCE_HARD)
+         {
+            msg (M_INFO, "Ignoring %s received during exit notification",
+                 signal_name(c->sig->signal_received, true));
+            signal_reset (c->sig);
+            ret = true;
+         }
+       else
+         {
+            msg (M_INFO, "Converting soft %s received during exit notification to SIGTERM",
+                 signal_name(c->sig->signal_received, true));
+            register_signal(c, SIGTERM, "exit-with-notification");
+            ret = false;
+         }
     }
 #endif
   return ret;
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index dc06350..34d163f 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -512,6 +512,54 @@ tls_version_parse(const char *vstr, const char *extra)
     return TLS_VER_BAD;
 }
 
+/**
+ * Load (or possibly reload) the CRL file into the SSL context.
+ * No reload is performed under the following conditions:
+ * - the CRL file was passed inline
+ * - the CRL file was not modified since the last (re)load
+ *
+ * @param ssl_ctx       The TLS context to use when reloading the CRL
+ * @param crl_file      The file name to load the CRL from, or
+ *                      "[[INLINE]]" in the case of inline files.
+ * @param crl_inline    A string containing the CRL
+ */
+static void
+tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx, const char *crl_file,
+		   const char *crl_file_inline)
+{
+  /* if something goes wrong with stat(), we'll store 0 as mtime */
+  platform_stat_t crl_stat = {0};
+
+  /*
+   * an inline CRL can't change at runtime, therefore there is no need to
+   * reload it. It will be reloaded upon config change + SIGHUP.
+   * Use always '1' as dummy timestamp in this case: it will trigger the
+   * first load, but will prevent any future reload.
+   */
+  if (crl_file_inline)
+    {
+      crl_stat.st_mtime = 1;
+    }
+  else if (platform_stat(crl_file, &crl_stat) < 0)
+    {
+      msg(M_WARN, "WARNING: Failed to stat CRL file, not (re)loading CRL.");
+      return;
+    }
+
+  /*
+   * Store the CRL if this is the first time or if the file was changed since
+   * the last load.
+   * Note: Windows does not support tv_nsec.
+   */
+  if ((ssl_ctx->crl_last_size == crl_stat.st_size) &&
+      (ssl_ctx->crl_last_mtime.tv_sec == crl_stat.st_mtime))
+    return;
+
+  ssl_ctx->crl_last_mtime.tv_sec = crl_stat.st_mtime;
+  ssl_ctx->crl_last_size = crl_stat.st_size;
+  backend_tls_ctx_reload_crl(ssl_ctx, crl_file, crl_file_inline);
+}
+
 /*
  * Initialize SSL context.
  * All files are in PEM format.
@@ -894,7 +942,7 @@ key_state_free (struct key_state *ks, bool clear)
 #endif
 
   if (clear)
-    CLEAR (*ks);
+    secure_memzero (ks, sizeof (*ks));
 }
 
 /** @} name Functions for initialization and cleanup of key_state structures */
@@ -973,7 +1021,7 @@ tls_session_init (struct tls_multi *multi, struct tls_session *session)
 
   /* Initialize control channel authentication parameters */
   session->tls_wrap = session->opt->tls_wrap;
-  session->tls_wrap.work = alloc_buf (TLS_CHANNEL_BUF_SIZE);
+  session->tls_wrap.work = alloc_buf (BUF_SIZE (&session->opt->frame));
 
   /* initialize packet ID replay window for --tls-auth */
   packet_id_init (&session->tls_wrap.opt.packet_id,
@@ -1024,7 +1072,7 @@ tls_session_free (struct tls_session *session, bool clear)
   cert_hash_free (session->cert_hash_set);
 
   if (clear)
-    CLEAR (*session);
+    secure_memzero (session, sizeof (*session));
 }
 
 /** @} name Functions for initialization and cleanup of tls_session structures */
@@ -1048,7 +1096,7 @@ move_session (struct tls_multi* multi, int dest, int src, bool reinit_src)
   if (reinit_src)
     tls_session_init (multi, &multi->session[src]);
   else
-    CLEAR (multi->session[src]);
+    secure_memzero (&multi->session[src], sizeof (multi->session[src]));
 
   dmsg (D_TLS_DEBUG, "TLS: move_session: exit");
 }
@@ -1212,15 +1260,17 @@ tls_multi_free (struct tls_multi *multi, bool clear)
 
   if (multi->auth_token)
     {
-      memset (multi->auth_token, 0, AUTH_TOKEN_SIZE);
+      secure_memzero (multi->auth_token, AUTH_TOKEN_SIZE);
       free (multi->auth_token);
     }
 
+  free (multi->remote_ciphername);
+
   for (i = 0; i < TM_SIZE; ++i)
     tls_session_free (&multi->session[i], false);
 
   if (clear)
-    CLEAR (*multi);
+    secure_memzero (multi, sizeof (*multi));
 
   free(multi);
 }
@@ -1320,13 +1370,20 @@ write_control_auth (struct tls_session *session,
     }
   else if (session->tls_wrap.mode == TLS_WRAP_CRYPT)
     {
-      buf_init (&session->tls_wrap.work, buf->offset);
+      ASSERT (buf_init (&session->tls_wrap.work, buf->offset));
       ASSERT (buf_write (&session->tls_wrap.work, &header, sizeof(header)));
       ASSERT (session_id_write (&session->session_id, &session->tls_wrap.work));
-      ASSERT (tls_crypt_wrap (buf, &session->tls_wrap.work, &session->tls_wrap.opt));
-      /* Don't change the original data in buf, it's used by the reliability
-       * layer to resend on failure. */
-      *buf = session->tls_wrap.work;
+      if (tls_crypt_wrap (buf, &session->tls_wrap.work, &session->tls_wrap.opt))
+	{
+	  /* Don't change the original data in buf, it's used by the reliability
+	   * layer to resend on failure. */
+	  *buf = session->tls_wrap.work;
+	}
+      else
+	{
+	  buf->len = 0;
+	  return;
+	}
     }
   *to_link_addr = &ks->remote_addr;
 }
@@ -1503,7 +1560,7 @@ tls1_P_hash(const md_kt_t *md_kt,
     }
   hmac_ctx_cleanup(&ctx);
   hmac_ctx_cleanup(&ctx_tmp);
-  CLEAR (A1);
+  secure_memzero (A1, sizeof (A1));
 
   dmsg (D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex (out_orig, olen_orig, 0, &gc));
   gc_free (&gc);
@@ -1556,7 +1613,7 @@ tls1_PRF(const uint8_t *label,
   for (i=0; i<olen; i++)
     out1[i]^=out2[i];
 
-  memset (out2, 0, olen);
+  secure_memzero (out2, olen);
 
   dmsg (D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex (out1, olen, 0, &gc));
 
@@ -1613,13 +1670,15 @@ generate_key_expansion (struct key_ctx_bi *key,
 			const struct session_id *server_sid,
 			bool server)
 {
-  uint8_t master[48];
-  struct key2 key2;
+  uint8_t master[48] = { 0 };
+  struct key2 key2 = { 0 };
   bool ret = false;
-  int i;
 
-  CLEAR (master);
-  CLEAR (key2);
+  if (key->initialized)
+    {
+      msg (D_TLS_ERRORS, "TLS Error: key already initialized");
+      goto exit;
+    }
 
   /* debugging print of source key material */
   key_source2_print (key_src);
@@ -1655,7 +1714,7 @@ generate_key_expansion (struct key_ctx_bi *key,
   key2_print (&key2, key_type, "Master Encrypt", "Master Decrypt");
 
   /* check for weak keys */
-  for (i = 0; i < 2; ++i)
+  for (int i = 0; i < 2; ++i)
     {
       fixup_key (&key2.keys[i], key_type);
       if (!check_key (&key2.keys[i], key_type))
@@ -1691,8 +1750,8 @@ generate_key_expansion (struct key_ctx_bi *key,
   ret = true;
 
  exit:
-  CLEAR (master);
-  CLEAR (key2);
+  secure_memzero (&master, sizeof (master));
+  secure_memzero (&key2, sizeof (key2));
 
   return ret;
 }
@@ -1714,8 +1773,8 @@ key_ctx_update_implicit_iv(struct key_ctx *ctx, uint8_t *key, size_t key_len) {
     }
 }
 
-static bool
-item_in_list(const char *item, const char *list)
+bool
+tls_item_in_cipher_list(const char *item, const char *list)
 {
   char *tmp_ciphers = string_alloc (list, NULL);
   char *tmp_ciphers_orig = tmp_ciphers;
@@ -1732,18 +1791,61 @@ item_in_list(const char *item, const char *list)
   return token != NULL;
 }
 
-bool
-tls_session_update_crypto_params(struct tls_session *session,
-    const struct options *options, struct frame *frame)
+void
+tls_poor_mans_ncp(struct options *o, const char *remote_ciphername)
+{
+  if (o->ncp_enabled && remote_ciphername &&
+      0 != strcmp(o->ciphername, remote_ciphername))
+    {
+      if (tls_item_in_cipher_list(remote_ciphername, o->ncp_ciphers))
+	{
+	  o->ciphername = string_alloc(remote_ciphername, &o->gc);
+	  msg (D_TLS_DEBUG_LOW, "Using peer cipher '%s'", o->ciphername);
+	}
+    }
+}
+
+/**
+ * Generate data channel keys for the supplied TLS session.
+ *
+ * This erases the source material used to generate the data channel keys, and
+ * can thus be called only once per session.
+ */
+static bool
+tls_session_generate_data_channel_keys(struct tls_session *session)
 {
   bool ret = false;
   struct key_state *ks = &session->key[KS_PRIMARY];	/* primary key */
+  const struct session_id *client_sid = session->opt->server ?
+      &ks->session_id_remote : &session->session_id;
+  const struct session_id *server_sid = !session->opt->server ?
+      &ks->session_id_remote : &session->session_id;
 
   ASSERT (ks->authenticated);
 
+  if (!generate_key_expansion (&ks->crypto_options.key_ctx_bi,
+      &session->opt->key_type, ks->key_src, client_sid, server_sid,
+      session->opt->server))
+    {
+      msg (D_TLS_ERRORS, "TLS Error: generate_key_expansion failed");
+      goto cleanup;
+    }
+  tls_limit_reneg_bytes (session->opt->key_type.cipher,
+			 &session->opt->renegotiate_bytes);
+
+  ret = true;
+cleanup:
+  secure_memzero (ks->key_src, sizeof (*ks->key_src));
+  return ret;
+}
+
+bool
+tls_session_update_crypto_params(struct tls_session *session,
+    const struct options *options, struct frame *frame)
+{
   if (!session->opt->server &&
       0 != strcmp(options->ciphername, session->opt->config_ciphername) &&
-      !item_in_list(options->ciphername, options->ncp_ciphers))
+      !tls_item_in_cipher_list(options->ciphername, options->ncp_ciphers))
     {
       msg (D_TLS_ERRORS, "Error: pushed cipher not allowed - %s not in %s or %s",
 	  options->ciphername, session->opt->config_ciphername,
@@ -1768,23 +1870,7 @@ tls_session_update_crypto_params(struct tls_session *session,
   frame_init_mssfix(frame, options);
   frame_print (frame, D_MTU_INFO, "Data Channel MTU parms");
 
-  const struct session_id *client_sid = session->opt->server ?
-      &ks->session_id_remote : &session->session_id;
-  const struct session_id *server_sid = !session->opt->server ?
-      &ks->session_id_remote : &session->session_id;
-  if (!generate_key_expansion (&ks->crypto_options.key_ctx_bi,
-      &session->opt->key_type, ks->key_src, client_sid, server_sid,
-      session->opt->server))
-    {
-      msg (D_TLS_ERRORS, "TLS Error: server generate_key_expansion failed");
-      goto cleanup;
-    }
-  tls_limit_reneg_bytes (session->opt->key_type.cipher,
-			 &session->opt->renegotiate_bytes);
-  ret = true;
-cleanup:
-  CLEAR (*ks->key_src);
-  return ret;
+  return tls_session_generate_data_channel_keys (session);
 }
 
 static bool
@@ -1979,7 +2065,7 @@ key_method_1_write (struct buffer *buf, struct tls_session *session)
   init_key_ctx (&ks->crypto_options.key_ctx_bi.encrypt, &key,
 		&session->opt->key_type, OPENVPN_OP_ENCRYPT,
 		"Data Channel Encrypt");
-  CLEAR (key);
+  secure_memzero (&key, sizeof (key));
 
   /* send local options string */
   {
@@ -2152,28 +2238,19 @@ key_method_2_write (struct buffer *buf, struct tls_session *session)
     {
       if (ks->authenticated)
 	{
-	  if (!generate_key_expansion (&ks->crypto_options.key_ctx_bi,
-				       &session->opt->key_type,
-				       ks->key_src,
-				       &ks->session_id_remote,
-				       &session->session_id,
-				       true))
+	  if (!tls_session_generate_data_channel_keys (session))
 	    {
 	      msg (D_TLS_ERRORS, "TLS Error: server generate_key_expansion failed");
 	      goto error;
 	    }
 	}
-		      
-      CLEAR (*ks->key_src);
-      tls_limit_reneg_bytes (session->opt->key_type.cipher,
-			     &session->opt->renegotiate_bytes);
     }
 
   return true;
 
  error:
   msg (D_TLS_ERRORS, "TLS Error: Key Method #2 write failed");
-  CLEAR (*ks->key_src);
+  secure_memzero (ks->key_src, sizeof (*ks->key_src));
   return false;
 }
 
@@ -2228,13 +2305,13 @@ key_method_1_read (struct buffer *buf, struct tls_session *session)
   init_key_ctx (&ks->crypto_options.key_ctx_bi.decrypt, &key,
 		&session->opt->key_type, OPENVPN_OP_DECRYPT,
 		"Data Channel Decrypt");
-  CLEAR (key);
+  secure_memzero (&key, sizeof (key));
   ks->authenticated = true;
   return true;
 
  error:
   buf_clear (buf);
-  CLEAR (key);
+  secure_memzero (&key, sizeof (key));
   return false;
 }
 
@@ -2303,10 +2380,20 @@ key_method_2_read (struct buffer *buf, struct tls_multi *multi, struct tls_sessi
   if ( multi->peer_info )
       output_peer_info_env (session->opt->es, multi->peer_info);
 
+  free (multi->remote_ciphername);
+  multi->remote_ciphername =
+      options_string_extract_option (options, "cipher", NULL);
+
   if (tls_peer_info_ncp_ver (multi->peer_info) < 2)
     {
-      /* Peer does not support NCP */
-      session->opt->ncp_enabled = false;
+      /* Peer does not support NCP, but leave NCP enabled if the local and
+       * remote cipher do not match to attempt 'poor-man's NCP'.
+       */
+      if (multi->remote_ciphername == NULL ||
+           0 == strcmp(multi->remote_ciphername, multi->opt.config_ciphername))
+       {
+         session->opt->ncp_enabled = false;
+       }
     }
 #endif
 
@@ -2338,7 +2425,7 @@ key_method_2_read (struct buffer *buf, struct tls_multi *multi, struct tls_sessi
     }
 
   /* clear username and password from memory */
-  CLEAR (*up);
+  secure_memzero (up, sizeof (*up));
 
   /* Perform final authentication checks */
   if (ks->authenticated)
@@ -2383,27 +2470,18 @@ key_method_2_read (struct buffer *buf, struct tls_multi *multi, struct tls_sessi
    */
   if (!session->opt->server && (!session->opt->pull || ks->key_id > 0))
     {
-      if (!generate_key_expansion (&ks->crypto_options.key_ctx_bi,
-				   &session->opt->key_type,
-				   ks->key_src,
-				   &session->session_id,
-				   &ks->session_id_remote,
-				   false))
+      if (!tls_session_generate_data_channel_keys (session))
 	{
 	  msg (D_TLS_ERRORS, "TLS Error: client generate_key_expansion failed");
 	  goto error;
 	}
-
-      CLEAR (*ks->key_src);
-      tls_limit_reneg_bytes (session->opt->key_type.cipher,
-			     &session->opt->renegotiate_bytes);
     }
 
   gc_free (&gc);
   return true;
 
  error:
-  CLEAR (*ks->key_src);
+  secure_memzero (ks->key_src, sizeof (*ks->key_src));
   buf_clear (buf);
   gc_free (&gc);
   return false;
@@ -2551,7 +2629,10 @@ tls_process (struct tls_multi *multi,
 	  ks->state = S_START;
 	  state_change = true;
 
-	  /* Reload the CRL before TLS negotiation */
+	  /*
+	   * Attempt CRL reload before TLS negotiation. Won't be performed if
+	   * the file was not modified since the last reload
+	   */
 	  if (session->opt->crl_file &&
 	      !(session->opt->ssl_flags & SSLF_CRL_VERIFY_DIR))
 	    {
@@ -2609,22 +2690,6 @@ tls_process (struct tls_multi *multi,
 	  break;
 	}
 
-#ifndef TLS_AGGREGATE_ACK
-      /* Send 1 or more ACKs (each received control packet gets one ACK) */
-      if (!to_link->len && !reliable_ack_empty (ks->rec_ack))
-	{
-	  buf = &ks->ack_write_buf;
-	  ASSERT (buf_init (buf, FRAME_HEADROOM (&multi->opt.frame)));
-	  write_control_auth (session, ks, buf, to_link_addr, P_ACK_V1,
-			      RELIABLE_ACK_SIZE, false);
-	  *to_link = *buf;
-	  active = true;
-	  state_change = true;
-	  dmsg (D_TLS_DEBUG, "Dedicated ACK -> TCP/UDP");
-	  break;
-	}
-#endif
-
       /* Write incoming ciphertext to TLS object */
       buf = reliable_get_buf_sequenced (ks->rec_reliable);
       if (buf)
@@ -2769,7 +2834,6 @@ tls_process (struct tls_multi *multi,
 
   update_time ();
 
-#ifdef TLS_AGGREGATE_ACK
   /* Send 1 or more ACKs (each received control packet gets one ACK) */
   if (!to_link->len && !reliable_ack_empty (ks->rec_ack))
     {
@@ -2779,10 +2843,8 @@ tls_process (struct tls_multi *multi,
 			  RELIABLE_ACK_SIZE, false);
       *to_link = buf;
       active = true;
-      state_change = true;
       dmsg (D_TLS_DEBUG, "Dedicated ACK -> TCP/UDP");
     }
-#endif
 
   /* When should we wake up again? */
   {
diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h
index 777b621..c971b75 100644
--- a/src/openvpn/ssl.h
+++ b/src/openvpn/ssl.h
@@ -70,15 +70,8 @@
 #define P_FIRST_OPCODE                 1
 #define P_LAST_OPCODE                  9
 
-/* Should we aggregate TLS
- * acknowledgements, and tack them onto
- * control packets? */
-#define TLS_AGGREGATE_ACK
-
 /*
- * If TLS_AGGREGATE_ACK, set the
- * max number of acknowledgments that
- * can "hitch a ride" on an outgoing
+ * Set the max number of acknowledgments that can "hitch a ride" on an outgoing
  * non-P_ACK_V1 control packet.
  */
 #define CONTROL_SEND_ACK_MAX 4
@@ -489,6 +482,15 @@ void tls_update_remote_addr (struct tls_multi *multi,
 bool tls_session_update_crypto_params(struct tls_session *session,
     const struct options *options, struct frame *frame);
 
+/**
+ * "Poor man's NCP": Use peer cipher if it is an allowed (NCP) cipher.
+ * Allows non-NCP peers to upgrade their cipher individually.
+ *
+ * Make sure to call tls_session_update_crypto_params() after calling this
+ * function.
+ */
+void tls_poor_mans_ncp(struct options *o, const char *remote_ciphername);
+
 #ifdef MANAGEMENT_DEF_AUTH
 static inline char *
 tls_get_peer_info(const struct tls_multi *multi)
@@ -512,6 +514,13 @@ int tls_peer_info_ncp_ver(const char *peer_info);
  */
 bool tls_check_ncp_cipher_list(const char *list);
 
+/**
+ * Return true iff item is present in the colon-separated zero-terminated
+ * cipher list.
+ */
+bool tls_item_in_cipher_list(const char *item, const char *list);
+
+
 /*
  * inline functions
  */
diff --git a/src/openvpn/ssl_backend.h b/src/openvpn/ssl_backend.h
index 0777c61..3fbd2b4 100644
--- a/src/openvpn/ssl_backend.h
+++ b/src/openvpn/ssl_backend.h
@@ -353,7 +353,7 @@ void key_state_ssl_free(struct key_state_ssl *ks_ssl);
  *                      "[[INLINE]]" in the case of inline files.
  * @param crl_inline    A string containing the CRL
  */
-void tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx,
+void backend_tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx,
     const char *crl_file, const char *crl_inline);
 
 /**
diff --git a/src/openvpn/ssl_common.h b/src/openvpn/ssl_common.h
index 28702af..7938f41 100644
--- a/src/openvpn/ssl_common.h
+++ b/src/openvpn/ssl_common.h
@@ -540,6 +540,8 @@ struct tls_multi
   uint32_t peer_id;
   bool use_peer_id;
 
+  char *remote_ciphername;	/**< cipher specified in peer's config file */
+
   char *auth_token;      /**< If server sends a generated auth-token,
                           *   this is the token to use for future
                           *   user/pass authentications in this session.
diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
index 7fa35a7..11ee65b 100644
--- a/src/openvpn/ssl_mbedtls.c
+++ b/src/openvpn/ssl_mbedtls.c
@@ -771,7 +771,7 @@ static void tls_version_to_major_minor(int tls_ver, int *major, int *minor) {
 }
 
 void
-tls_ctx_reload_crl(struct tls_root_ctx *ctx, const char *crl_file,
+backend_tls_ctx_reload_crl(struct tls_root_ctx *ctx, const char *crl_file,
     const char *crl_inline)
 {
   ASSERT (crl_file);
diff --git a/src/openvpn/ssl_mbedtls.h b/src/openvpn/ssl_mbedtls.h
index 3edeedc..a4a7f05 100644
--- a/src/openvpn/ssl_mbedtls.h
+++ b/src/openvpn/ssl_mbedtls.h
@@ -74,6 +74,8 @@ struct tls_root_ctx {
     mbedtls_x509_crt *ca_chain;		/**< CA chain for remote verification */
     mbedtls_pk_context *priv_key;	/**< Local private key */
     mbedtls_x509_crl *crl;              /**< Certificate Revocation List */
+    struct timespec crl_last_mtime;     /**< CRL last modification time */
+    off_t crl_last_size;		/**< size of last loaded CRL */
 #if defined(ENABLE_PKCS11)
     mbedtls_pkcs11_context *priv_key_pkcs11;	/**< PKCS11 private key */
 #endif
diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index 51669fc..4f472ff 100644
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -772,7 +772,7 @@ end:
 }
 
 void
-tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx, const char *crl_file,
+backend_tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx, const char *crl_file,
         const char *crl_inline)
 {
   X509_CRL *crl = NULL;
diff --git a/src/openvpn/ssl_openssl.h b/src/openvpn/ssl_openssl.h
index 97dc742..115ac43 100644
--- a/src/openvpn/ssl_openssl.h
+++ b/src/openvpn/ssl_openssl.h
@@ -49,6 +49,8 @@
  */
 struct tls_root_ctx {
     SSL_CTX *ctx;
+    struct timespec crl_last_mtime;
+    off_t crl_last_size;
 };
 
 struct key_state_ssl {
diff --git a/src/openvpn/ssl_verify.c b/src/openvpn/ssl_verify.c
index a099776..4328828 100644
--- a/src/openvpn/ssl_verify.c
+++ b/src/openvpn/ssl_verify.c
@@ -1176,7 +1176,7 @@ verify_user_pass(struct user_pass *up, struct tls_multi *multi,
       if (memcmp_constant_time(multi->auth_token, up->password,
                  strlen(multi->auth_token)) != 0)
         {
-          memset (multi->auth_token, 0, AUTH_TOKEN_SIZE);
+          secure_memzero (multi->auth_token, AUTH_TOKEN_SIZE);
           free (multi->auth_token);
           multi->auth_token = NULL;
           multi->auth_token_sent = false;
@@ -1262,7 +1262,7 @@ verify_user_pass(struct user_pass *up, struct tls_multi *multi,
                   "No auth-token will be activated now");
 	      if (multi->auth_token)
 		{
-		  memset (multi->auth_token, 0, AUTH_TOKEN_SIZE);
+		  secure_memzero (multi->auth_token, AUTH_TOKEN_SIZE);
 		  free (multi->auth_token);
 		  multi->auth_token = NULL;
 		}
diff --git a/src/openvpn/ssl_verify_mbedtls.c b/src/openvpn/ssl_verify_mbedtls.c
index 332f04b..4260823 100644
--- a/src/openvpn/ssl_verify_mbedtls.c
+++ b/src/openvpn/ssl_verify_mbedtls.c
@@ -348,12 +348,10 @@ x509_setenv (struct env_set *es, int cert_depth, mbedtls_x509_crt *cert)
   int i;
   unsigned char c;
   const mbedtls_x509_name *name;
-  char s[128];
+  char s[128] = { 0 };
 
   name = &cert->subject;
 
-  memset( s, 0, sizeof( s ) );
-
   while( name != NULL )
     {
       char name_expand[64+8];
diff --git a/src/openvpn/syshead.h b/src/openvpn/syshead.h
index 8de7d87..f5008b7 100644
--- a/src/openvpn/syshead.h
+++ b/src/openvpn/syshead.h
@@ -26,7 +26,7 @@
 #define SYSHEAD_H
 
 #include "compat.h"
-#include "compat-stdbool.h"
+#include <stdbool.h>
 
 /* branch prediction hints */
 #if defined(__GNUC__)
diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 77ae72f..572e168 100644
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -68,6 +68,9 @@ static void netsh_ifconfig (const struct tuntap_options *to,
 			    const in_addr_t ip,
 			    const in_addr_t netmask,
 			    const unsigned int flags);
+static void netsh_set_dns6_servers (const struct in6_addr *addr_list,
+				    const int addr_len,
+				    const char *flex_name);
 static void netsh_command (const struct argv *a, int n, int msglevel);
 
 static const char *netsh_get_id (const char *dev_node, struct gc_arena *gc);
@@ -132,6 +135,74 @@ out:
   return ret;
 }
 
+static bool
+do_dns6_service (bool add, const struct tuntap *tt)
+{
+  DWORD len;
+  bool ret = false;
+  ack_message_t ack;
+  struct gc_arena gc = gc_new ();
+  HANDLE pipe = tt->options.msg_channel;
+  int addr_len = add ? tt->options.dns6_len : 0;
+
+  if (addr_len == 0 && add) /* no addresses to add */
+      return true;
+
+  dns_cfg_message_t dns = {
+    .header = {
+      (add ? msg_add_dns_cfg : msg_del_dns_cfg),
+      sizeof (dns_cfg_message_t),
+      0 },
+    .iface = { .index = tt->adapter_index, .name = "" },
+    .domains = "",
+    .family = AF_INET6,
+    .addr_len = addr_len
+  };
+
+  /* interface name is required */
+  strncpy (dns.iface.name, tt->actual_name, sizeof (dns.iface.name));
+  dns.iface.name[sizeof (dns.iface.name) - 1] = '\0';
+
+  if (addr_len > _countof(dns.addr))
+    {
+      addr_len = _countof(dns.addr);
+      dns.addr_len = addr_len;
+      msg(M_WARN, "Number of IPv6 DNS addresses sent to service truncated to %d",
+          addr_len);
+    }
+
+  for (int i = 0; i < addr_len; ++i)
+    {
+      dns.addr[i].ipv6 = tt->options.dns6[i];
+    }
+
+  msg (D_LOW, "%s IPv6 dns servers on '%s' (if_index = %d) using service",
+       (add ? "Setting" : "Deleting"), dns.iface.name, dns.iface.index);
+
+  if (!WriteFile (pipe, &dns, sizeof (dns), &len, NULL) ||
+      !ReadFile (pipe, &ack, sizeof (ack), &len, NULL))
+    {
+      msg (M_WARN, "TUN: could not talk to service: %s [%lu]",
+           strerror_win32 (GetLastError (), &gc), GetLastError ());
+      goto out;
+    }
+
+  if (ack.error_number != NO_ERROR)
+    {
+      msg (M_WARN, "TUN: %s IPv6 dns failed using service: %s [status=%u if_name=%s]",
+           (add ? "adding" : "deleting"), strerror_win32 (ack.error_number, &gc),
+           ack.error_number, dns.iface.name);
+      goto out;
+    }
+
+  msg (M_INFO, "IPv6 dns servers %s using service", (add ? "set" : "deleted"));
+  ret = true;
+
+out:
+  gc_free (&gc);
+  return ret;
+}
+
 #endif
 
 #ifdef TARGET_SOLARIS
@@ -1372,9 +1443,16 @@ do_ifconfig (struct tuntap *tt,
 
     if ( do_ipv6 )
       {
-	if (tt->options.msg_channel)
+	if (tt->options.ip_win32_type == IPW32_SET_MANUAL)
+	  {
+	    msg (M_INFO, "******** NOTE:  Please manually set the v6 IP of '%s' to %s (if it is not already set)",
+	         actual,
+	         ifconfig_ipv6_local);
+          }
+	else if (tt->options.msg_channel)
 	  {
 	    do_address_service (true, AF_INET6, tt);
+	    do_dns6_service (true, tt);
 	  }
 	else
 	  {
@@ -1388,10 +1466,15 @@ do_ifconfig (struct tuntap *tt,
 			 iface,
 			 ifconfig_ipv6_local );
 	    netsh_command (&argv, 4, M_FATAL);
+	    /* set ipv6 dns servers if any are specified */
+	    netsh_set_dns6_servers(tt->options.dns6, tt->options.dns6_len, actual);
 	  }
 
 	/* explicit route needed */
-	add_route_connected_v6_net(tt, es);
+	if (tt->options.ip_win32_type != IPW32_SET_MANUAL)
+	  {
+	    add_route_connected_v6_net(tt, es);
+	  }
       }
 #else
       msg (M_FATAL, "Sorry, but I don't know how to do 'ifconfig' commands on this operating system.  You should ifconfig your TUN/TAP device manually or use an --up script.");
@@ -1623,14 +1706,20 @@ void
 open_tun (const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
 {
 #define ANDROID_TUNNAME "vpnservice-tun"
-  int i;
   struct user_pass up;
   struct gc_arena gc = gc_new ();
   bool opentun;
 
   int oldtunfd = tt->fd;
 
-  for (i = 0; i < tt->options.dns_len; ++i) {
+  /* Prefer IPv6 DNS servers,
+   * Android will use the DNS server in the order we specify*/
+  for (int i = 0; i < tt->options.dns6_len; i++) {
+    management_android_control (management, "DNS6SERVER",
+				print_in6_addr (tt->options.dns6[i], 0, &gc));
+  }
+
+  for (int i = 0; i < tt->options.dns_len; i++) {
     management_android_control (management, "DNSSERVER",
 				print_in_addr_t(tt->options.dns[i], 0, &gc));
   }
@@ -4508,23 +4597,9 @@ ipconfig_register_dns (const struct env_set *es)
   bool status;
   const char err[] = "ERROR: Windows ipconfig command failed";
 
-  msg (D_TUNTAP_INFO, "Start net commands...");
+  msg (D_TUNTAP_INFO, "Start ipconfig commands for register-dns...");
   netcmd_semaphore_lock ();
 
-  argv_printf (&argv, "%s%sc stop dnscache",
-	       get_win_sys_path(),
-	       WIN_NET_PATH_SUFFIX);
-  argv_msg (D_TUNTAP_INFO, &argv);
-  status = openvpn_execve_check (&argv, es, 0, err);
-  argv_reset(&argv);
-
-  argv_printf (&argv, "%s%sc start dnscache",
-	       get_win_sys_path(),
-	       WIN_NET_PATH_SUFFIX);
-  argv_msg (D_TUNTAP_INFO, &argv);
-  status = openvpn_execve_check (&argv, es, 0, err);
-  argv_reset(&argv);
-
   argv_printf (&argv, "%s%sc /flushdns",
 	       get_win_sys_path(),
 	       WIN_IPCONFIG_PATH_SUFFIX);
@@ -4540,7 +4615,7 @@ ipconfig_register_dns (const struct env_set *es)
   argv_reset(&argv);
 
   netcmd_semaphore_release ();
-  msg (D_TUNTAP_INFO, "End net commands...");
+  msg (D_TUNTAP_INFO, "End ipconfig commands for register-dns...");
 }
 
 void
@@ -4617,6 +4692,41 @@ ip_addr_member_of (const in_addr_t addr, const IP_ADDR_STRING *ias)
   return false;
 }
 
+/**
+ * Set the ipv6 dns servers on the specified interface.
+ * The list of dns servers currently set on the interface
+ * are cleared first.
+ * No action is taken if number of addresses (addr_len) < 1.
+ */
+static void
+netsh_set_dns6_servers (const struct in6_addr *addr_list,
+			const int addr_len,
+			const char *flex_name)
+{
+    struct gc_arena gc = gc_new ();
+    struct argv argv = argv_new ();
+
+    for (int i = 0; i < addr_len; ++i)
+    {
+	const char *fmt = (i == 0) ?
+	    "%s%sc interface ipv6 set dns %s static %s"
+	    : "%s%sc interface ipv6 add dns %s %s";
+	argv_printf (&argv, fmt, get_win_sys_path(),
+		     NETSH_PATH_SUFFIX, flex_name,
+		     print_in6_addr (addr_list[i], 0, &gc));
+
+	/* disable slow address validation on Windows 7 and higher */
+	if (win32_version_info() >= WIN_7)
+	    argv_printf_cat (&argv, "%s", "validate=no");
+
+	/* Treat errors while adding as non-fatal as we do not check for duplicates */
+	netsh_command (&argv, 1, (i==0)? M_FATAL : M_NONFATAL);
+    }
+
+    argv_reset (&argv);
+    gc_free (&gc);
+}
+
 static void
 netsh_ifconfig_options (const char *type,
 			const in_addr_t *addr_list,
@@ -5540,6 +5650,8 @@ close_tun (struct tuntap *tt)
           if (tt->options.msg_channel)
             {
               do_address_service (false, AF_INET6, tt);
+	      if (tt->options.dns6_len > 0)
+		  do_dns6_service (false, tt);
             }
           else
             {
@@ -5563,6 +5675,17 @@ close_tun (struct tuntap *tt)
                            ifconfig_ipv6_local);
 
               netsh_command (&argv, 1, M_WARN);
+
+	      /* delete ipv6 dns servers if any were set */
+	      if (tt->options.dns6_len > 0)
+		{
+		  argv_printf (&argv,
+			       "%s%sc interface ipv6 delete dns %s all",
+			       get_win_sys_path(),
+			       NETSH_PATH_SUFFIX,
+			       tt->actual_name);
+		  netsh_command (&argv, 1, M_WARN);
+		}
               argv_reset (&argv);
             }
 	}
diff --git a/src/openvpn/tun.h b/src/openvpn/tun.h
index dedd915..9b5a1b7 100644
--- a/src/openvpn/tun.h
+++ b/src/openvpn/tun.h
@@ -107,6 +107,9 @@ struct tuntap_options {
   bool dhcp_release;
 
   bool register_dns;
+
+  struct in6_addr dns6[N_DHCP_ADDR];
+  int dns6_len;
 };
 
 #elif TARGET_LINUX