Backport of WL#798 (MySQL IPv6 support) from 6.0.

The following 6.0 revisions were analyzed:
  - sp1r-brian@zim.(none)-20071228102738-21894
  - sp1r-brian@zim.(none)-20071228121841-56447
  - sp1r-brian@zim.(none)-20071228205403-56423
  - sp1r-brian@zim.(none)-20071228221139-55341
  - sp1r-brian@zim.(none)-20071228233443-55352
  - sp1r-brian@zim.(none)-20071229094527-61763
  - sp1r-brian@zim.(none)-20071230203739-61746
  - sp1r-brian@zim.(none)-20080102213805-61741
  - sp1r-brian@zim.(none)-20080103201041-61746
  - sp1r-brian@zim.(none)-20080104234927-59875
  - sp1r-brian@zim.(none)-20080105005827-59874
  - sp1r-brian@zim.(none)-20080105012020-59865
  - sp1r-brian@zim.(none)-20080106003858-59857
  - sp1r-brian@zim.(none)-20080123195552-31680
  - sp1r-brian@zim.(none)-20080124201848-29999
  - sp1r-brian@zim.(none)-20080129075144-36991
  - sp1r-cbell/Chuck@mysql_cab_desk.-20080215041806-21954
  - sp1r-vvaintroub@wva.-20080212124547-06272
  - sp1r-dfischer/mysqldev@mysql.com/production.mysql.com-20071223184258-15140
  - sp1r-brian@zim.(none)-20080206122216-35774
  - sp1r-baker@bk-internal.mysql.com-20080209005622-35947
  - sp1r-baker@bk-internal.mysql.com-20080224215608-24613
  - sp1r-baker@bk-internal.mysql.com-20080307170710-63543
  - sp1r-baker@bk-internal.mysql.com-20080312233205-13069
  - sp1r-Reggie@core.-20080402175211-28643
  - kpettersson@mysql.com-20080901101150-4ne74r8v0492vv42
  - alik@sun.com-20090805173811-9fzt0ymcp9tsvn7k
  - alik@sun.com-20090805173937-fcv1fdveodq5x9gb
  - alik@sun.com-20090805175009-g1od16i3t1xkw2qr
  - kostja@sun.com-20090805200643-j9i4fy7ii8ijho5c
  - alik@sun.com-20090807195303-j4fb5m4l1dgdahwo
  - alik@sun.com-20090808114848-3rkzr9kifrijzaqy
  - alik@sun.com-20090810041739-ugmx34h34uid8mox
  - alik@sun.com-20090810105306-rf43rfyzzblsy5e7
  - alik@sun.com-20090810123113-ccdjwai68b5woqdm
  - alik@sun.com-20090811080423-gb7pibec1znaydzy
  - alik@sun.com-20090811082130-5uckar1vx3kdsw7g
  - alik@sun.com-20090812202051-uqkfwwxxcjvo5ean

The following bugfixes are also backported within this patch:
  - Bug#34292: netdb.h missing in hostname.cc
  - Bug#39153: Failing to lookup a host name can lead to crash
    in current IPv6 implementation
  - Bug#38247: Server does not resolve connecting ip's
  - Bug#43006: main.skip_name_resolve fails on Windows in PB2
  - Bug#45606: ACL requires IPv4-mapped addresses to be used
  - Bug#45584: Host name cache does not work as a cache

18 files changed, 1034 insertions, 377 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7a5ee9223bc..6e8c7db3c2a 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -39,6 +39,9 @@ ADD_DEFINITIONS(-DDEFAULT_CHARSET_HOME="c:/Program Files/MySQL/MySQL Server ${MY
 ADD_DEFINITIONS(-DPACKAGE=mysql)
 ADD_DEFINITIONS(-DSHAREDIR="share")
 
+# Enable IPv6 handling code
+ADD_DEFINITIONS(-DHAVE_IPV6)
+
 # Set debug options
 SET(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DFORCE_INIT_OF_VARS")
 
diff --git a/configure.in b/configure.in
index 361d117b2dc..8e7dbcfeda6 100644
--- a/configure.in
+++ b/configure.in
@@ -864,6 +864,42 @@ AC_CHECK_DECLS(MHA_MAPSIZE_VA,
 fi
 
 #--------------------------------------------------------------------
+# Check for IPv6 support
+#--------------------------------------------------------------------
+
+AC_CHECK_HEADERS(netinet/in6.h)
+
+AC_CHECK_TYPES([struct sockaddr_in6, struct in6_addr],
+                [have_in6_types=yes],
+                [have_in6_types=no], 
+  [[
+    #ifdef WIN32
+      #include <winsock2.h>
+    #else
+      #include <sys/types.h>
+      #include <netinet/in.h>
+      #include <sys/socket.h>
+    #endif
+
+    #ifdef HAVE_NETINET_IN6_H
+      #include <netinet/in6.h>
+    #endif
+  ]])
+
+AC_MSG_CHECKING([for IPv6 support])
+
+AC_ARG_ENABLE(ipv6,
+  AS_HELP_STRING([--disable-ipv6], [Disable support for IPv6 networking]),
+  [disable_ipv6=yes], [disable_ipv6=no])
+
+if test x"$disable_ipv6" = xyes -o x"$have_in6_types" = xno; then
+  AC_MSG_RESULT([no])
+else
+  AC_DEFINE([HAVE_IPV6], [1], [Define if IPv6 networking support is present])
+  AC_MSG_RESULT([yes])
+fi
+
+#--------------------------------------------------------------------
 # Check for TCP wrapper support
 #--------------------------------------------------------------------
 
@@ -961,12 +997,6 @@ AC_CHECK_TYPES([int8, uint8, int16, uint16, int32, uint32, int64, uint64,
                 uchar, uint, ulong],[],[], [
 #include <sys/types.h>
 ])
-AC_CHECK_TYPES([in_addr_t], [], [], [
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-])
 AC_CHECK_TYPES([fp_except], [], [], [
 #include <sys/types.h>
 #include <ieeefp.h>
diff --git a/include/config-win.h b/include/config-win.h
index 431bfcfa702..68248c09bef 100644
--- a/include/config-win.h
+++ b/include/config-win.h
@@ -20,6 +20,13 @@
 
 #define BIG_TABLES
 
+/*
+  Minimal version of Windows we should be able to run on.
+  Currently Windows XP.
+*/
+#define _WIN32_WINNT     0x0501
+
+
 #if defined(_MSC_VER) && _MSC_VER >= 1400
 /* Avoid endless warnings about sprintf() etc. being unsafe. */
 #define _CRT_SECURE_NO_DEPRECATE 1
@@ -27,6 +34,7 @@
 
 #include <sys/locking.h>
 #include <winsock2.h>
+#include <Ws2tcpip.h>
 #include <fcntl.h>
 #include <io.h>
 #include <malloc.h>
@@ -88,6 +96,12 @@
 
 #define S_IROTH		S_IREAD		/* for my_lib */
 
+/* Winsock2 constant (Vista SDK and later)*/
+#define IPPROTO_IPV6 41
+#ifndef IPV6_V6ONLY
+#define IPV6_V6ONLY 27
+#endif
+
 #ifdef __BORLANDC__
 #define FILE_BINARY	O_BINARY	/* my_fopen in binary mode */
 #define O_TEMPORARY	0
diff --git a/include/my_net.h b/include/my_net.h
index 3af79ea3db5..18fb3db8e88 100644
--- a/include/my_net.h
+++ b/include/my_net.h
@@ -43,7 +43,7 @@ C_MODE_START
 #include <sys/ioctl.h>
 #endif
 
-#if !defined(__WIN__) && !defined(HAVE_BROKEN_NETINET_INCLUDES) && !defined(__BEOS__) && !defined(__NETWARE__)
+#if !defined(__WIN__) && !defined(HAVE_BROKEN_NETINET_INCLUDES) && !defined(__NETWARE__)
 #include <netinet/in_systm.h>
 #include <netinet/in.h>
 #include <netinet/ip.h>
@@ -73,11 +73,6 @@ C_MODE_START
 #define in_addr_t uint32
 #endif
 
-/* On some operating systems (e.g. Solaris) INADDR_NONE is not defined */
-#ifndef INADDR_NONE
-#define INADDR_NONE -1                          /* Error value from inet_addr */
-#endif
-
 /* Thread safe or portable version of some functions */
 
 void my_inet_ntoa(struct in_addr in, char *buf);
@@ -86,9 +81,6 @@ void my_inet_ntoa(struct in_addr in, char *buf);
   Handling of gethostbyname_r()
 */
 
-#if !defined(HPUX10)
-struct hostent;
-#endif /* HPUX */
 #if !defined(HAVE_GETHOSTBYNAME_R)
 struct hostent *my_gethostbyname_r(const char *name,
 				   struct hostent *result, char *buffer,
@@ -118,11 +110,5 @@ struct hostent *my_gethostbyname_r(const char *name,
 #define GETHOSTBYNAME_BUFF_SIZE 2048
 #endif
 
-/* On SCO you get a link error when refering to h_errno */
-#ifdef SCO
-#undef h_errno
-#define h_errno errno
-#endif
-
 C_MODE_END
 #endif
diff --git a/include/violite.h b/include/violite.h
index 3e8e430392b..eed6c46271f 100644
--- a/include/violite.h
+++ b/include/violite.h
@@ -81,13 +81,19 @@ int	vio_errno(Vio*vio);
 /* Get socket number */
 my_socket vio_fd(Vio*vio);
 /* Remote peer's address and name in text form */
-my_bool	vio_peer_addr(Vio* vio, char *buf, uint16 *port);
-/* Remotes in_addr */
-void	vio_in_addr(Vio *vio, struct in_addr *in);
+my_bool vio_peer_addr(Vio *vio, char *buf, uint16 *port, size_t buflen);
 my_bool vio_poll_read(Vio *vio, uint timeout);
 my_bool vio_is_connected(Vio *vio);
 ssize_t vio_pending(Vio *vio);
 
+my_bool vio_get_normalized_ip_string(const struct sockaddr *addr, int addr_length,
+                                     char *ip_string, size_t ip_string_size);
+
+int vio_getnameinfo(const struct sockaddr *sa,
+                    char *hostname, size_t hostname_size,
+                    char *port, size_t port_size,
+                    int flags);
+
 #ifdef HAVE_OPENSSL
 #include <openssl/opensslv.h>
 #if OPENSSL_VERSION_NUMBER < 0x0090700f
@@ -154,8 +160,7 @@ void vio_end(void);
 #define vio_should_retry(vio) 			(vio)->should_retry(vio)
 #define vio_was_interrupted(vio) 		(vio)->was_interrupted(vio)
 #define vio_close(vio)				((vio)->vioclose)(vio)
-#define vio_peer_addr(vio, buf, prt)		(vio)->peer_addr(vio, buf, prt)
-#define vio_in_addr(vio, in)			(vio)->in_addr(vio, in)
+#define vio_peer_addr(vio, buf, prt, buflen)	(vio)->peer_addr(vio, buf, prt, buflen)
 #define vio_timeout(vio, which, seconds)	(vio)->timeout(vio, which, seconds)
 #define vio_poll_read(vio, timeout)             (vio)->poll_read(vio, timeout)
 #define vio_is_connected(vio)                   (vio)->is_connected(vio)
@@ -180,8 +185,9 @@ struct st_vio
   HANDLE hPipe;
   my_bool		localhost;	/* Are we from localhost? */
   int			fcntl_mode;	/* Buffered fcntl(sd,F_GETFL) */
-  struct sockaddr_in	local;		/* Local internet address */
-  struct sockaddr_in	remote;		/* Remote internet address */
+  struct sockaddr_storage	local;		/* Local internet address */
+  struct sockaddr_storage	remote;		/* Remote internet address */
+  int addrLen;                          /* Length of remote address */
   enum enum_vio_type	type;		/* Type of connection */
   char			desc[30];	/* String description */
   char                  *read_buffer;   /* buffer for vio_read_buff */
@@ -197,8 +203,8 @@ struct st_vio
   my_bool (*is_blocking)(Vio*);
   int     (*viokeepalive)(Vio*, my_bool);
   int     (*fastsend)(Vio*);
-  my_bool (*peer_addr)(Vio*, char *, uint16*);
-  void    (*in_addr)(Vio*, struct in_addr*);
+  my_bool (*peer_addr)(Vio*, char *, uint16*, size_t);
+  void    (*in_addr)(Vio*, struct sockaddr_storage*);
   my_bool (*should_retry)(Vio*);
   my_bool (*was_interrupted)(Vio*);
   int     (*vioclose)(Vio*);
diff --git a/mysql-test/t/skip_name_resolve.test b/mysql-test/t/skip_name_resolve.test
index df010d15fa0..cd7ffe1690d 100644
--- a/mysql-test/t/skip_name_resolve.test
+++ b/mysql-test/t/skip_name_resolve.test
@@ -15,7 +15,7 @@ DROP USER mysqltest_1@'127.0.0.1/255.255.255.255';
 # Bug#13407 Remote connecting crashes server
 # Server crashed when one used USER() function in connection for which
 # was impossible to obtain peer hostname.
-connect (con1, 127.0.0.1, root, , test, $MASTER_MYPORT, );
+connect (con1, localhost, root, , test, $MASTER_MYPORT, );
 --replace_column 1 #
 SELECT USER();
 # We are only interested in the fact that statement below doesn't
diff --git a/scripts/mysql_system_tables_data.sql b/scripts/mysql_system_tables_data.sql
index 03136fe9361..a7988b5198e 100644
--- a/scripts/mysql_system_tables_data.sql
+++ b/scripts/mysql_system_tables_data.sql
@@ -24,6 +24,7 @@ set @current_hostname= @@hostname;
 INSERT INTO tmp_user VALUES ('localhost','root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0);
 REPLACE INTO tmp_user SELECT @current_hostname,'root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0 FROM dual WHERE LOWER( @current_hostname) != 'localhost';
 REPLACE INTO tmp_user VALUES ('127.0.0.1','root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0);
+REPLACE INTO tmp_user VALUES ('::1','root','','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','','','','',0,0,0,0);
 INSERT INTO tmp_user (host,user) VALUES ('localhost','');
 INSERT INTO tmp_user (host,user) SELECT @current_hostname,'' FROM dual WHERE LOWER(@current_hostname ) != 'localhost';
 INSERT INTO user SELECT * FROM tmp_user WHERE @had_user_table=0;
diff --git a/sql-common/client.c b/sql-common/client.c
index 5114b645818..1f9c00f93be 100644
--- a/sql-common/client.c
+++ b/sql-common/client.c
@@ -38,6 +38,10 @@
 
 #include "mysql.h"
 
+#ifndef __WIN__
+#include <netdb.h>
+#endif
+
 /* Remove client convenience wrappers */
 #undef max_allowed_packet
 #undef net_buffer_length
@@ -2227,9 +2231,6 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
 {
   char		buff[NAME_LEN+USERNAME_LENGTH+100];
   char		*end,*host_info= NULL;
-  my_socket	sock;
-  in_addr_t	ip_addr;
-  struct	sockaddr_in sock_addr;
   ulong		pkt_length;
   NET		*net= &mysql->net;
 #ifdef MYSQL_SERVER
@@ -2335,7 +2336,6 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
     else
     {
       mysql->options.protocol=MYSQL_PROTOCOL_MEMORY;
-      sock=0;
       unix_socket = 0;
       host=mysql->options.shared_memory_base_name;
       my_snprintf(host_info=buff, sizeof(buff)-1,
@@ -2350,12 +2350,9 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
       (unix_socket || mysql_unix_port) &&
       (!host || !strcmp(host,LOCAL_HOST)))
   {
-    host=LOCAL_HOST;
-    if (!unix_socket)
-      unix_socket=mysql_unix_port;
-    host_info=(char*) ER(CR_LOCALHOST_CONNECTION);
-    DBUG_PRINT("info",("Using UNIX sock '%s'",unix_socket));
-    if ((sock = socket(AF_UNIX,SOCK_STREAM,0)) == SOCKET_ERROR)
+    DBUG_PRINT("info", ("Using socket"));
+    my_socket sock= socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sock == SOCKET_ERROR)
     {
       set_mysql_extended_error(mysql, CR_SOCKET_CREATE_ERROR,
                                unknown_sqlstate,
@@ -2363,12 +2360,28 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
                                socket_errno);
       goto error;
     }
+
     net->vio= vio_new(sock, VIO_TYPE_SOCKET,
                       VIO_LOCALHOST | VIO_BUFFERED_READ);
-    bzero((char*) &UNIXaddr,sizeof(UNIXaddr));
-    UNIXaddr.sun_family = AF_UNIX;
+    if (!net->vio)
+    {
+      DBUG_PRINT("error",("Unknow protocol %d ", mysql->options.protocol));
+      set_mysql_error(mysql, CR_CONN_UNKNOW_PROTOCOL, unknown_sqlstate);
+      closesocket(sock);
+      goto error;
+    }
+
+    host= LOCAL_HOST;
+    if (!unix_socket)
+      unix_socket= mysql_unix_port;
+    host_info= (char*) ER(CR_LOCALHOST_CONNECTION);
+    DBUG_PRINT("info", ("Using UNIX sock '%s'", unix_socket));
+
+    bzero((char*) &UNIXaddr, sizeof(UNIXaddr));
+    UNIXaddr.sun_family= AF_UNIX;
     strmake(UNIXaddr.sun_path, unix_socket, sizeof(UNIXaddr.sun_path)-1);
-    if (my_connect(sock,(struct sockaddr *) &UNIXaddr, sizeof(UNIXaddr),
+
+    if (my_connect(sock, (struct sockaddr *) &UNIXaddr, sizeof(UNIXaddr),
 		   mysql->options.connect_timeout))
     {
       DBUG_PRINT("error",("Got error %d on connect to local server",
@@ -2377,6 +2390,8 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
                                unknown_sqlstate,
                                ER(CR_CONNECTION_ERROR),
                                unix_socket, socket_errno);
+      vio_delete(net->vio);
+      net->vio= 0;
       goto error;
     }
     mysql->options.protocol=MYSQL_PROTOCOL_SOCKET;
@@ -2387,7 +2402,6 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
        (host && !strcmp(host,LOCAL_HOST_NAMEDPIPE)) ||
        (! have_tcpip && (unix_socket || !host && is_NT()))))
   {
-    sock=0;
     if ((hPipe= create_named_pipe(mysql, mysql->options.connect_timeout,
                                   (char**) &host, (char**) &unix_socket)) ==
 	INVALID_HANDLE_VALUE)
@@ -2417,94 +2431,124 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
       (!mysql->options.protocol ||
        mysql->options.protocol == MYSQL_PROTOCOL_TCP))
   {
-    int status= -1;
+    struct addrinfo *res_lst, hints, *t_res;
+    int gai_errno;
+    char port_buf[NI_MAXSERV];
+    my_socket sock= SOCKET_ERROR;
+    int UNINIT_VAR(saved_error), status= -1;
+
     unix_socket=0;				/* This is not used */
+
     if (!port)
-      port=mysql_port;
+      port= mysql_port;
+
     if (!host)
-      host=LOCAL_HOST;
-    my_snprintf(host_info=buff,sizeof(buff)-1,ER(CR_TCP_CONNECTION),host);
-    DBUG_PRINT("info",("Server name: '%s'.  TCP sock: %d", host,port));
+      host= LOCAL_HOST;
+
+    my_snprintf(host_info=buff, sizeof(buff)-1, ER(CR_TCP_CONNECTION), host);
+    DBUG_PRINT("info",("Server name: '%s'.  TCP sock: %d", host, port));
 #ifdef MYSQL_SERVER
     thr_alarm_init(&alarmed);
     thr_alarm(&alarmed, mysql->options.connect_timeout, &alarm_buff);
 #endif
-    /* _WIN64 ;  Assume that the (int) range is enough for socket() */
-    sock = (my_socket) socket(AF_INET,SOCK_STREAM,0);
+
+    DBUG_PRINT("info",("IP '%s'", "client"));
+
 #ifdef MYSQL_SERVER
     thr_end_alarm(&alarmed);
 #endif
-    if (sock == SOCKET_ERROR)
-    {
-      set_mysql_extended_error(mysql, CR_IPSOCK_ERROR, unknown_sqlstate,
-                               ER(CR_IPSOCK_ERROR), socket_errno);
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_socktype= SOCK_STREAM;
+    hints.ai_protocol= IPPROTO_TCP;
+    hints.ai_family= AF_UNSPEC;
+
+    DBUG_PRINT("info",("IPV6 getaddrinfo %s", host));
+    my_snprintf(port_buf, NI_MAXSERV, "%d", port);
+    gai_errno= getaddrinfo(host, port_buf, &hints, &res_lst);
+
+    if (gai_errno != 0) 
+    { 
+      /* 
+        For DBUG we are keeping the right message but for client we default to
+        historical error message.
+      */
+      DBUG_PRINT("info",("IPV6 getaddrinfo error %d", gai_errno));
+      set_mysql_extended_error(mysql, CR_UNKNOWN_HOST, unknown_sqlstate,
+                               ER(CR_UNKNOWN_HOST), host, errno);
+
       goto error;
     }
-    net->vio= vio_new(sock, VIO_TYPE_TCPIP, VIO_BUFFERED_READ);
-    bzero((char*) &sock_addr,sizeof(sock_addr));
-    sock_addr.sin_family = AF_INET;
-    sock_addr.sin_port = (ushort) htons((ushort) port);
 
     /*
-      The server name may be a host name or IP address
+      A hostname might map to multiple IP addresses (IPv4/IPv6). Go over the
+      list of IP addresses until a successful connection can be established.
     */
-
-    if ((int) (ip_addr = inet_addr(host)) != (int) INADDR_NONE)
-    {
-      memcpy_fixed(&sock_addr.sin_addr,&ip_addr,sizeof(ip_addr));
-      status= my_connect(sock, (struct sockaddr *) &sock_addr,
-                         sizeof(sock_addr), mysql->options.connect_timeout);
-    }
-    else
+    DBUG_PRINT("info", ("Try connect on all addresses for host."));
+    for (t_res= res_lst; t_res; t_res= t_res->ai_next)
     {
-      int i, tmp_errno;
-      struct hostent tmp_hostent,*hp;
-      char buff2[GETHOSTBYNAME_BUFF_SIZE];
-      hp = my_gethostbyname_r(host,&tmp_hostent,buff2,sizeof(buff2),
-			      &tmp_errno);
+      DBUG_PRINT("info", ("Create socket, family: %d  type: %d  proto: %d",
+                          t_res->ai_family, t_res->ai_socktype,
+                          t_res->ai_protocol));
+      sock= socket(t_res->ai_family, t_res->ai_socktype, t_res->ai_protocol);
+      if (sock == SOCKET_ERROR)
+      {
+        saved_error= socket_errno;
+        continue;
+      }
 
+      DBUG_PRINT("info", ("Connect socket"));
+      status= my_connect(sock, t_res->ai_addr, t_res->ai_addrlen,
+                         mysql->options.connect_timeout);
       /*
-        Don't attempt to connect to non IPv4 addresses as the client could
-        end up sending information to a unknown server. For example, a IPv6
-        address might be returned from gethostbyname depending on options
-        set via the RES_OPTIONS environment variable.
+        Here we rely on my_connect() to return success only if the
+        connect attempt was really successful. Otherwise we would stop
+        trying another address, believing we were successful.
       */
-      if (!hp || (hp->h_addrtype != AF_INET))
-      {
-	my_gethostbyname_r_free();
-        set_mysql_extended_error(mysql, CR_UNKNOWN_HOST, unknown_sqlstate,
-                                 ER(CR_UNKNOWN_HOST), host, tmp_errno);
-	goto error;
-      }
+      if (!status)
+        break;
 
-      for (i= 0; status && hp->h_addr_list[i]; i++)
-      {
-        char ipaddr[18] __attribute__((unused));
-        memcpy(&sock_addr.sin_addr, hp->h_addr_list[i],
-               min(sizeof(sock_addr.sin_addr), (size_t) hp->h_length));
-        DBUG_PRINT("info",("Trying %s...",
-                          (my_inet_ntoa(sock_addr.sin_addr, ipaddr), ipaddr)));
-        /*
-          Here we rely on my_connect() to return success only if the
-          connect attempt was really successful. Otherwise we would stop
-          trying another address, believing we were successful.
-        */
-        status= my_connect(sock, (struct sockaddr *) &sock_addr,
-                           sizeof(sock_addr), mysql->options.connect_timeout);
-      }
+      /*
+        Save value as socket errno might be overwritten due to
+        calling a socket function below.
+      */
+      saved_error= socket_errno;
 
-      my_gethostbyname_r_free();
+      DBUG_PRINT("info", ("No success, close socket, try next address."));
+      closesocket(sock);
+    }
+    DBUG_PRINT("info",
+               ("End of connect attempts, sock: %d  status: %d  error: %d",
+                sock, status, saved_error));
+
+    freeaddrinfo(res_lst);
+
+    if (sock == SOCKET_ERROR)
+    {
+      set_mysql_extended_error(mysql, CR_IPSOCK_ERROR, unknown_sqlstate,
+                                ER(CR_IPSOCK_ERROR), saved_error);
+      goto error;
     }
 
     if (status)
     {
-      DBUG_PRINT("error",("Got error %d on connect to '%s'",socket_errno,
-			  host));
+      DBUG_PRINT("error",("Got error %d on connect to '%s'", saved_error, host));
       set_mysql_extended_error(mysql, CR_CONN_HOST_ERROR, unknown_sqlstate,
-                               ER(CR_CONN_HOST_ERROR), host, socket_errno);
+                                ER(CR_CONN_HOST_ERROR), host, saved_error);
+      goto error;
+    }
+
+    net->vio= vio_new(sock, VIO_TYPE_TCPIP, VIO_BUFFERED_READ);
+    if (! net->vio )
+    {
+      DBUG_PRINT("error",("Unknow protocol %d ", mysql->options.protocol));
+      set_mysql_error(mysql, CR_CONN_UNKNOW_PROTOCOL, unknown_sqlstate);
+      closesocket(sock);
       goto error;
     }
   }
+
+  DBUG_PRINT("info", ("net->vio: %p", net->vio));
   if (!net->vio)
   {
     DBUG_PRINT("error",("Unknow protocol %d ",mysql->options.protocol));
@@ -2640,14 +2684,14 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
   if (client_flag & CLIENT_MULTI_STATEMENTS)
     client_flag|= CLIENT_MULTI_RESULTS;
 
-#ifdef HAVE_OPENSSL
+#if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
   if (mysql->options.ssl_key || mysql->options.ssl_cert ||
       mysql->options.ssl_ca || mysql->options.ssl_capath ||
       mysql->options.ssl_cipher)
     mysql->options.use_ssl= 1;
   if (mysql->options.use_ssl)
     client_flag|=CLIENT_SSL;
-#endif /* HAVE_OPENSSL */
+#endif /* HAVE_OPENSSL && !EMBEDDED_LIBRARY*/
   if (db)
     client_flag|=CLIENT_CONNECT_WITH_DB;
 
@@ -2676,7 +2720,7 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
   }
   mysql->client_flag=client_flag;
 
-#ifdef HAVE_OPENSSL
+#if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
   if (client_flag & CLIENT_SSL)
   {
     /* Do the SSL layering. */
@@ -2727,7 +2771,7 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
     }
 
   }
-#endif /* HAVE_OPENSSL */
+#endif /* HAVE_OPENSSL && !EMBEDDED_LIBRARY */
 
   DBUG_PRINT("info",("Server version = '%s'  capabilites: %lu  status: %u  client_flag: %lu",
 		     mysql->server_version,mysql->server_capabilities,
diff --git a/sql/client_settings.h b/sql/client_settings.h
index fd50bfdbb88..7d103d5904d 100644
--- a/sql/client_settings.h
+++ b/sql/client_settings.h
@@ -30,10 +30,6 @@
 #define set_sigpipe(mysql)
 #define reset_sigpipe(mysql)
 #define read_user_name(A) {}
-#define mysql_rpl_query_type(A,B) MYSQL_RPL_ADMIN
-#define mysql_master_send_query(A, B, C) 1
-#define mysql_slave_send_query(A, B, C) 1
-#define mysql_rpl_probe(mysql) 0
 #undef HAVE_SMEM
 #undef _CUSTOMCONFIG_
 
diff --git a/sql/hostname.cc b/sql/hostname.cc
index b498c548e61..cf35e60061f 100644
--- a/sql/hostname.cc
+++ b/sql/hostname.cc
@@ -18,10 +18,10 @@
   @file
 
   @brief
-  Get hostname for an IP.
+  Get hostname for an IP address.
 
-    Hostnames are checked with reverse name lookup and
-    checked that they doesn't resemble an ip.
+  Hostnames are checked with reverse name lookup and checked that they
+  doesn't resemble an IP address.
 */
 
 #include "mysql_priv.h"
@@ -34,24 +34,54 @@ extern "C" {					// Because of SCO 3.2V4.2
 #ifdef HAVE_SYS_UN_H
 #include <sys/un.h>
 #endif
-#include <netdb.h>
 #include <sys/utsname.h>
 #endif // __WIN__
 #ifdef	__cplusplus
 }
 #endif
 
+/*
+  HOST_ENTRY_KEY_SIZE -- size of IP address string in the hash cache.
+*/
+
+#define HOST_ENTRY_KEY_SIZE INET6_ADDRSTRLEN
+
+/**
+  An entry in the hostname hash table cache.
+
+  Host name cache does two things:
+    - caches host names to save DNS look ups;
+    - counts connect errors from IP.
 
-class host_entry :public hash_filo_element
+  Host name can be NULL (that means DNS look up failed), but connect errors
+  still are counted.
+*/
+
+class Host_entry :public hash_filo_element
 {
 public:
-  char	 ip[sizeof(((struct in_addr *) 0)->s_addr)];
-  uint	 errors;
-  char	 *hostname;
+  /**
+    Client IP address. This is the key used with the hash table.
+
+    The client IP address is always expressed in IPv6, even when the
+    network IPv6 stack is not present.
+
+    This IP address is never used to connect to a socket.
+  */
+  char ip_key[HOST_ENTRY_KEY_SIZE];
+
+  /**
+    Number of errors during handshake phase from the IP address.
+  */
+  uint connect_errors;
+
+  /**
+    One of the host names for the IP address. May be NULL.
+  */
+  const char *hostname;
 };
 
 static hash_filo *hostname_cache;
-static pthread_mutex_t LOCK_hostname;
 
 void hostname_cache_refresh()
 {
@@ -60,219 +90,468 @@ void hostname_cache_refresh()
 
 bool hostname_cache_init()
 {
-  host_entry tmp;
-  uint offset= (uint) ((char*) (&tmp.ip) - (char*) &tmp);
-  if (!(hostname_cache=new hash_filo(HOST_CACHE_SIZE, offset,
-				     sizeof(struct in_addr),NULL,
-				     (my_hash_free_key) free,
-				     &my_charset_bin)))
+  Host_entry tmp;
+  uint key_offset= (uint) ((char*) (&tmp.ip_key) - (char*) &tmp);
+
+  if (!(hostname_cache= new hash_filo(HOST_CACHE_SIZE,
+                                      key_offset, HOST_ENTRY_KEY_SIZE,
+                                      NULL, (my_hash_free_key) free,
+                                      &my_charset_bin)))
     return 1;
+
   hostname_cache->clear();
-  (void) pthread_mutex_init(&LOCK_hostname,MY_MUTEX_INIT_SLOW);
+
   return 0;
 }
 
 void hostname_cache_free()
 {
-  if (hostname_cache)
-  {
-    (void) pthread_mutex_destroy(&LOCK_hostname);
-    delete hostname_cache;
-    hostname_cache= 0;
-  }
+  delete hostname_cache;
+  hostname_cache= NULL;
 }
 
+static void prepare_hostname_cache_key(const char *ip_string,
+                                       char *ip_key)
+{
+  int ip_string_length= strlen(ip_string);
+  DBUG_ASSERT(ip_string_length < HOST_ENTRY_KEY_SIZE);
 
-static void add_hostname(struct in_addr *in,const char *name)
+  memset(ip_key, 0, HOST_ENTRY_KEY_SIZE);
+  memcpy_fixed(ip_key, ip_string, ip_string_length);
+}
+
+static inline Host_entry *hostname_cache_search(const char *ip_key)
 {
-  if (!(specialflag & SPECIAL_NO_HOST_CACHE))
+  return (Host_entry *) hostname_cache->search((uchar *) ip_key, 0);
+}
+
+static bool add_hostname_impl(const char *ip_key, const char *hostname)
+{
+  if (hostname_cache_search(ip_key))
+    return FALSE;
+
+  size_t hostname_size= hostname ? strlen(hostname) + 1 : 0;
+
+  Host_entry *entry= (Host_entry *) malloc(sizeof (Host_entry) + hostname_size);
+
+  if (!entry)
+    return TRUE;
+
+  char *hostname_copy;
+
+  memcpy_fixed(&entry->ip_key, ip_key, HOST_ENTRY_KEY_SIZE);
+
+  if (hostname_size)
   {
-    pthread_mutex_lock(&hostname_cache->lock);
-    host_entry *entry;
-    if (!(entry=(host_entry*) hostname_cache->search((uchar*) &in->s_addr,0)))
-    {
-      uint length=name ? (uint) strlen(name) : 0;
+    hostname_copy= (char *) (entry + 1);
+    memcpy(hostname_copy, hostname, hostname_size);
 
-      if ((entry=(host_entry*) malloc(sizeof(host_entry)+length+1)))
-      {
-	char *new_name;
-	memcpy_fixed(&entry->ip, &in->s_addr, sizeof(in->s_addr));
-	if (length)
-	  memcpy(new_name= (char *) (entry+1), name, length+1);
-	else
-	  new_name=0;
-	entry->hostname=new_name;
-	entry->errors=0;
-	(void) hostname_cache->add(entry);
-      }
-    }
-    pthread_mutex_unlock(&hostname_cache->lock);
+    DBUG_PRINT("info", ("Adding '%s' -> '%s' to the hostname cache...'",
+                        (const char *) ip_key,
+                        (const char *) hostname_copy));
   }
-}
+  else
+  {
+    hostname_copy= NULL;
+
+    DBUG_PRINT("info", ("Adding '%s' -> NULL to the hostname cache...'",
+                        (const char *) ip_key));
+  }
+
+  entry->hostname= hostname_copy;
+  entry->connect_errors= 0;
 
+  return hostname_cache->add(entry);
+}
 
-inline void add_wrong_ip(struct in_addr *in)
+static bool add_hostname(const char *ip_key, const char *hostname)
 {
-  add_hostname(in,NullS);
+  if (specialflag & SPECIAL_NO_HOST_CACHE)
+    return FALSE;
+
+  pthread_mutex_lock(&hostname_cache->lock);
+
+  bool err_status= add_hostname_impl(ip_key, hostname);
+
+  pthread_mutex_unlock(&hostname_cache->lock);
+
+  return err_status;
 }
 
-void inc_host_errors(struct in_addr *in)
+void inc_host_errors(const char *ip_string)
 {
+  if (!ip_string)
+    return;
+
+  char ip_key[HOST_ENTRY_KEY_SIZE];
+  prepare_hostname_cache_key(ip_string, ip_key);
+
   pthread_mutex_lock(&hostname_cache->lock);
-  host_entry *entry;
-  if ((entry=(host_entry*) hostname_cache->search((uchar*) &in->s_addr,0)))
-    entry->errors++;
+
+  Host_entry *entry= hostname_cache_search(ip_key);
+
+  if (entry)
+    entry->connect_errors++;
+
   pthread_mutex_unlock(&hostname_cache->lock);
 }
 
-void reset_host_errors(struct in_addr *in)
+
+void reset_host_errors(const char *ip_string)
 {
+  if (!ip_string)
+    return;
+
+  char ip_key[HOST_ENTRY_KEY_SIZE];
+  prepare_hostname_cache_key(ip_string, ip_key);
+
   pthread_mutex_lock(&hostname_cache->lock);
-  host_entry *entry;
-  if ((entry=(host_entry*) hostname_cache->search((uchar*) &in->s_addr,0)))
-    entry->errors=0;
+
+  Host_entry *entry= hostname_cache_search(ip_key);
+
+  if (entry)
+    entry->connect_errors= 0;
+
   pthread_mutex_unlock(&hostname_cache->lock);
 }
 
-/* Deal with systems that don't defined INADDR_LOOPBACK */
-#ifndef INADDR_LOOPBACK
-#define INADDR_LOOPBACK 0x7f000001UL
-#endif
 
-char * ip_to_hostname(struct in_addr *in, uint *errors)
+static inline bool is_ip_loopback(const struct sockaddr *ip)
+{
+  switch (ip->sa_family) {
+  case AF_INET:
+    {
+      /* Check for IPv4 127.0.0.1. */
+      struct in_addr *ip4= &((struct sockaddr_in *) ip)->sin_addr;
+      return ntohl(ip4->s_addr) == INADDR_LOOPBACK;
+    }
+
+#ifdef HAVE_IPV6
+  case AF_INET6:
+    {
+      /* Check for IPv6 ::1. */
+      struct in6_addr *ip6= &((struct sockaddr_in6 *) ip)->sin6_addr;
+      return IN6_IS_ADDR_LOOPBACK(ip6);
+    }
+#endif /* HAVE_IPV6 */
+
+  default:
+    return FALSE;
+  }
+}
+
+static inline bool is_hostname_valid(const char *hostname)
 {
-  uint i;
-  host_entry *entry;
+  /*
+    A hostname is invalid if it starts with a number followed by a dot
+    (IPv4 address).
+  */
+
+  if (!my_isdigit(&my_charset_latin1, hostname[0]))
+    return TRUE;
+
+  const char *p= hostname + 1;
+
+  while (my_isdigit(&my_charset_latin1, *p))
+    ++p;
+
+  return *p != '.';
+}
+
+/**
+  Resolve IP-address to host name.
+
+  This function does the following things:
+    - resolves IP-address;
+    - employs Forward Confirmed Reverse DNS technique to validate IP-address;
+    - returns host name if IP-address is validated;
+    - set value to out-variable connect_errors -- this variable represents the
+      number of connection errors from the specified IP-address.
+
+  NOTE: connect_errors are counted (are supported) only for the clients
+  where IP-address can be resolved and FCrDNS check is passed.
+
+  @param [in]  ip_storage IP address (sockaddr). Must be set.
+  @param [in]  ip_string  IP address (string). Must be set.
+  @param [out] hostname
+  @param [out] connect_errors
+
+  @return Error status
+  @retval FALSE Success
+  @retval TRUE Error
+
+  The function does not set/report MySQL server error in case of failure.
+  It's caller's responsibility to handle failures of this function
+  properly.
+*/
+
+bool ip_to_hostname(struct sockaddr_storage *ip_storage,
+                    const char *ip_string,
+                    char **hostname, uint *connect_errors)
+{
+  const struct sockaddr *ip= (const sockaddr *) ip_storage;
+  int err_code;
+  bool err_status;
+
   DBUG_ENTER("ip_to_hostname");
-  *errors=0;
+  DBUG_PRINT("info", ("IP address: '%s'; family: %d.",
+                      (const char *) ip_string,
+                      (int) ip->sa_family));
 
-  /* We always treat the loopback address as "localhost". */
-  if (in->s_addr == htonl(INADDR_LOOPBACK))   // is expanded inline by gcc
-    DBUG_RETURN((char *)my_localhost);
+  /* Check if we have loopback address (127.0.0.1 or ::1). */
+
+  if (is_ip_loopback(ip))
+  {
+    DBUG_PRINT("info", ("Loopback address detected."));
+
+    *connect_errors= 0; /* Do not count connect errors from localhost. */
+    *hostname= (char *) my_localhost;
+
+    DBUG_RETURN(FALSE);
+  }
+
+  /* Prepare host name cache key. */
+
+  char ip_key[HOST_ENTRY_KEY_SIZE];
+  prepare_hostname_cache_key(ip_string, ip_key);
+
+  /* Check first if we have host name in the cache. */
 
-  /* Check first if we have name in cache */
   if (!(specialflag & SPECIAL_NO_HOST_CACHE))
   {
     pthread_mutex_lock(&hostname_cache->lock);
-    if ((entry=(host_entry*) hostname_cache->search((uchar*) &in->s_addr,0)))
+
+    Host_entry *entry= hostname_cache_search(ip_key);
+
+    if (entry)
     {
-      char *name;
-      if (!entry->hostname)
-	name=0;					// Don't allow connection
-      else
-	name=my_strdup(entry->hostname,MYF(0));
-      *errors= entry->errors;
+      *connect_errors= entry->connect_errors;
+      *hostname= NULL;
+
+      if (entry->hostname)
+        *hostname= my_strdup(entry->hostname, MYF(0));
+
+      DBUG_PRINT("info",("IP (%s) has been found in the cache. "
+                         "Hostname: '%s'; connect_errors: %d",
+                         (const char *) ip_key,
+                         (const char *) (*hostname? *hostname : "null"),
+                         (int) *connect_errors));
+
       pthread_mutex_unlock(&hostname_cache->lock);
-      DBUG_RETURN(name);
+
+      DBUG_RETURN(FALSE);
     }
+
     pthread_mutex_unlock(&hostname_cache->lock);
   }
 
-  struct hostent *hp, *check;
-  char *name;
-  LINT_INIT(check);
-#if defined(HAVE_GETHOSTBYADDR_R) && defined(HAVE_SOLARIS_STYLE_GETHOST)
-  char buff[GETHOSTBYADDR_BUFF_SIZE],buff2[GETHOSTBYNAME_BUFF_SIZE];
-  int tmp_errno;
-  struct hostent tmp_hostent, tmp_hostent2;
-#ifdef HAVE_purify
-  bzero(buff,sizeof(buff));		// Bug in purify
-#endif
-  if (!(hp=gethostbyaddr_r((char*) in,sizeof(*in),
-			   AF_INET,
-			   &tmp_hostent,buff,sizeof(buff),&tmp_errno)))
-  {
-    DBUG_PRINT("error",("gethostbyaddr_r returned %d",tmp_errno));
-    return 0;
-  }
-  if (!(check=my_gethostbyname_r(hp->h_name,&tmp_hostent2,buff2,sizeof(buff2),
-				 &tmp_errno)))
+  /*
+    Resolve host name. Return an error if a host name can not be resolved
+    (instead of returning the numeric form of the host name).
+  */
+
+  char hostname_buffer[NI_MAXHOST];
+
+  DBUG_PRINT("info", ("Resolving '%s'...", (const char *) ip_key));
+
+  err_code= vio_getnameinfo(ip, hostname_buffer, NI_MAXHOST, NULL, 0,
+                            NI_NAMEREQD);
+
+  if (err_code == EAI_NONAME)
   {
-    DBUG_PRINT("error",("gethostbyname_r returned %d",tmp_errno));
     /*
-      Don't cache responses when the DSN server is down, as otherwise
-      transient DNS failure may leave any number of clients (those
-      that attempted to connect during the outage) unable to connect
-      indefinitely.
+      There is no reverse address mapping for the IP address. A host name
+      can not be resolved.
     */
-    if (tmp_errno == HOST_NOT_FOUND || tmp_errno == NO_DATA)
-      add_wrong_ip(in);
-    my_gethostbyname_r_free();
-    DBUG_RETURN(0);
-  }
-  if (!hp->h_name[0])
-  {
-    DBUG_PRINT("error",("Got an empty hostname"));
-    add_wrong_ip(in);
-    my_gethostbyname_r_free();
-    DBUG_RETURN(0);				// Don't allow empty hostnames
-  }
-  if (!(name=my_strdup(hp->h_name,MYF(0))))
-  {
-    my_gethostbyname_r_free();
-    DBUG_RETURN(0);				// out of memory
+
+    DBUG_PRINT("error", ("IP address '%s' could not be resolved: "
+                         "no reverse address mapping.",
+                         (const char *) ip_key));
+
+    sql_print_warning("IP address '%s' could not be resolved: "
+                      "no reverse address mapping.",
+                      (const char *) ip_key);
+
+    err_status= add_hostname(ip_key, NULL);
+
+    *hostname= NULL;
+    *connect_errors= 0; /* New IP added to the cache. */
+
+    DBUG_RETURN(err_status);
   }
-  my_gethostbyname_r_free();
-#else
-  pthread_mutex_lock(&LOCK_hostname);
-  if (!(hp=gethostbyaddr((char*) in,sizeof(*in), AF_INET)))
+  else if (err_code)
   {
-    pthread_mutex_unlock(&LOCK_hostname);
-    DBUG_PRINT("error",("gethostbyaddr returned %d",errno));
+    DBUG_PRINT("error", ("IP address '%s' could not be resolved: "
+                         "getnameinfo() returned %d.",
+                         (const char *) ip_key,
+                         (int) err_code));
+
+    sql_print_warning("IP address '%s' could not be resolved: "
+                      "getnameinfo() returned error (code: %d).",
+                      (const char *) ip_key,
+                      (int) err_code);
 
-    if (errno == HOST_NOT_FOUND || errno == NO_DATA)
-      goto add_wrong_ip_and_return;
-    /* Failure, don't cache responce */
-    DBUG_RETURN(0);
+    DBUG_RETURN(TRUE);
   }
-  if (!hp->h_name[0])				// Don't allow empty hostnames
+
+  DBUG_PRINT("info", ("IP '%s' resolved to '%s'.",
+                      (const char *) ip_key,
+                      (const char *) hostname_buffer));
+
+  /*
+    Validate hostname: the server does not accept host names, which
+    resemble IP addresses.
+
+    The thing is that theoretically, a host name can be in a form of IPv4
+    address (123.example.org, or 1.2 or even 1.2.3.4). We have to deny such
+    host names because ACL-systems is not designed to work with them.
+
+    For example, it is possible to specify a host name mask (like
+    192.168.1.%) for an ACL rule. Then, if IPv4-like hostnames are allowed,
+    there is a security hole: instead of allowing access for
+    192.168.1.0/255 network (which was assumed by the user), the access
+    will be allowed for host names like 192.168.1.example.org.
+  */
+
+  if (!is_hostname_valid(hostname_buffer))
   {
-    pthread_mutex_unlock(&LOCK_hostname);
-    DBUG_PRINT("error",("Got an empty hostname"));
-    goto add_wrong_ip_and_return;
+    DBUG_PRINT("error", ("IP address '%s' has been resolved "
+                         "to the host name '%s', which resembles "
+                         "IPv4-address itself.",
+                         (const char *) ip_key,
+                         (const char *) hostname_buffer));
+
+    sql_print_warning("IP address '%s' has been resolved "
+                      "to the host name '%s', which resembles "
+                      "IPv4-address itself.",
+                      (const char *) ip_key,
+                      (const char *) hostname_buffer);
+
+    err_status= add_hostname(ip_key, NULL);
+
+    *hostname= NULL;
+    *connect_errors= 0; /* New IP added to the cache. */
+
+    DBUG_RETURN(err_status);
   }
-  if (!(name=my_strdup(hp->h_name,MYF(0))))
+
+  /* Get IP-addresses for the resolved host name (FCrDNS technique). */
+
+  struct addrinfo hints;
+  struct addrinfo *addr_info_list;
+
+  memset(&hints, 0, sizeof (struct addrinfo));
+  hints.ai_flags= AI_PASSIVE;
+  hints.ai_socktype= SOCK_STREAM;
+  hints.ai_family= AF_UNSPEC;
+
+  DBUG_PRINT("info", ("Getting IP addresses for hostname '%s'...",
+                      (const char *) hostname_buffer));
+
+  err_code= getaddrinfo(hostname_buffer, NULL, &hints, &addr_info_list);
+
+  if (err_code == EAI_NONAME)
   {
-    pthread_mutex_unlock(&LOCK_hostname);
-    DBUG_RETURN(0);				// out of memory
+    /*
+      Don't cache responses when the DNS server is down, as otherwise
+      transient DNS failure may leave any number of clients (those
+      that attempted to connect during the outage) unable to connect
+      indefinitely.
+    */
+
+    err_status= add_hostname(ip_key, NULL);
+
+    *hostname= NULL;
+    *connect_errors= 0; /* New IP added to the cache. */
+
+    DBUG_RETURN(err_status);
   }
-  check=gethostbyname(name);
-  pthread_mutex_unlock(&LOCK_hostname);
-  if (!check)
+  else if (err_code)
   {
-    DBUG_PRINT("error",("gethostbyname returned %d",errno));
-    my_free(name,MYF(0));
-    DBUG_RETURN(0);
+    DBUG_PRINT("error", ("getaddrinfo() failed with error code %d.", err_code));
+    DBUG_RETURN(TRUE);
   }
-#endif
 
-  /* Don't accept hostnames that starts with digits because they may be
-     false ip:s */
-  if (my_isdigit(&my_charset_latin1,name[0]))
+  /* Check that getaddrinfo() returned the used IP (FCrDNS technique). */
+
+  DBUG_PRINT("info", ("The following IP addresses found for '%s':",
+                      (const char *) hostname_buffer));
+
+  for (struct addrinfo *addr_info= addr_info_list;
+       addr_info; addr_info= addr_info->ai_next)
   {
-    char *pos;
-    for (pos= name+1 ; my_isdigit(&my_charset_latin1,*pos); pos++) ;
-    if (*pos == '.')
+    char ip_buffer[HOST_ENTRY_KEY_SIZE];
+
+    {
+      err_status=
+        vio_get_normalized_ip_string(addr_info->ai_addr, addr_info->ai_addrlen,
+                                     ip_buffer, sizeof (ip_buffer));
+      DBUG_ASSERT(!err_status);
+    }
+
+    DBUG_PRINT("info", ("  - '%s'", (const char *) ip_buffer));
+
+    if (strcmp(ip_key, ip_buffer) == 0)
     {
-      DBUG_PRINT("error",("mysqld doesn't accept hostnames that starts with a number followed by a '.'"));
-      my_free(name,MYF(0));
-      goto add_wrong_ip_and_return;
+      /* Copy host name string to be stored in the cache. */
+
+      *hostname= my_strdup(hostname_buffer, MYF(0));
+
+      if (!*hostname)
+      {
+        DBUG_PRINT("error", ("Out of memory."));
+
+        freeaddrinfo(addr_info_list);
+        DBUG_RETURN(TRUE);
+      }
+
+      break;
     }
   }
 
-  /* Check that 'gethostbyname' returned the used ip */
-  for (i=0; check->h_addr_list[i]; i++)
+  /* Log resolved IP-addresses if no match was found. */
+
+  if (!*hostname)
   {
-    if (*(uint32*)(check->h_addr_list)[i] == in->s_addr)
+    sql_print_information("Hostname '%s' does not resolve to '%s'.",
+                          (const char *) hostname_buffer,
+                          (const char *) ip_key);
+    sql_print_information("Hostname '%s' has the following IP addresses:",
+                          (const char *) hostname_buffer);
+
+    for (struct addrinfo *addr_info= addr_info_list;
+         addr_info; addr_info= addr_info->ai_next)
     {
-      add_hostname(in,name);
-      DBUG_RETURN(name);
+      char ip_buffer[HOST_ENTRY_KEY_SIZE];
+
+      err_status=
+        vio_get_normalized_ip_string(addr_info->ai_addr, addr_info->ai_addrlen,
+                                     ip_buffer, sizeof (ip_buffer));
+      DBUG_ASSERT(!err_status);
+
+      sql_print_information(" - %s\n", (const char *) ip_buffer);
     }
   }
-  DBUG_PRINT("error",("Couldn't verify hostname with gethostbyname"));
-  my_free(name,MYF(0));
 
-add_wrong_ip_and_return:
-  add_wrong_ip(in);
-  DBUG_RETURN(0);
+  /* Free the result of getaddrinfo(). */
+
+  freeaddrinfo(addr_info_list);
+
+  /* Add an entry for the IP to the cache. */
+
+  if (*hostname)
+  {
+    err_status= add_hostname(ip_key, *hostname);
+    *connect_errors= 0;
+  }
+  else
+  {
+    DBUG_PRINT("error",("Couldn't verify hostname with getaddrinfo()."));
+
+    err_status= add_hostname(ip_key, NULL);
+    *hostname= NULL;
+    *connect_errors= 0;
+  }
+
+  DBUG_RETURN(err_status);
 }
diff --git a/sql/mysql_priv.h b/sql/mysql_priv.h
index c6454679e28..552b834b379 100644
--- a/sql/mysql_priv.h
+++ b/sql/mysql_priv.h
@@ -53,6 +53,9 @@
 #include "sql_array.h"
 #include "sql_plugin.h"
 #include "scheduler.h"
+#ifndef __WIN__
+#include <netdb.h>
+#endif
 
 class Parser_state;
 
@@ -2235,10 +2238,11 @@ uint build_table_shadow_filename(char *buff, size_t bufflen,
 #define FRM_ONLY        (1 << 3)
 
 /* from hostname.cc */
-struct in_addr;
-char * ip_to_hostname(struct in_addr *in,uint *errors);
-void inc_host_errors(struct in_addr *in);
-void reset_host_errors(struct in_addr *in);
+bool ip_to_hostname(struct sockaddr_storage *ip_storage,
+                    const char *ip_string,
+                    char **hostname, uint *connect_errors);
+void inc_host_errors(const char *ip_string);
+void reset_host_errors(const char *ip_string);
 bool hostname_cache_init();
 void hostname_cache_free();
 void hostname_cache_refresh(void);
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 1cab245b317..5f00fa0ec64 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -106,7 +106,6 @@ extern "C" {					// Because of SCO 3.2V4.2
 #ifdef HAVE_SYS_UN_H
 #  include <sys/un.h>
 #endif
-#include <netdb.h>
 #ifdef HAVE_SELECT_H
 #  include <select.h>
 #endif
@@ -176,7 +175,7 @@ static void registerwithneb();
 static void getvolumename();
 static void getvolumeID(BYTE *volumeName);
 #endif /* __NETWARE__ */
-  
+
 
 #ifdef _AIX41
 int initgroups(const char *,unsigned int);
@@ -390,7 +389,6 @@ static my_bool opt_short_log_format= 0;
 static uint kill_cached_threads, wake_thread;
 static ulong killed_threads, thread_created;
 static ulong max_used_connections;
-static ulong my_bind_addr;			/**< the address we bind to */
 static volatile ulong cached_thread_count= 0;
 static const char *sql_mode_str= "OFF";
 /* Text representation for OPTIMIZER_SWITCH_DEFAULT */
@@ -1635,17 +1633,18 @@ static void set_root(const char *path)
 #endif
 }
 
+
 static void network_init(void)
 {
-  struct sockaddr_in	IPaddr;
 #ifdef HAVE_SYS_UN_H
   struct sockaddr_un	UNIXaddr;
 #endif
-  int	arg=1;
+  int	arg;
   int   ret;
   uint  waited;
   uint  this_wait;
   uint  retry;
+  char port_buf[NI_MAXSERV];
   DBUG_ENTER("network_init");
   LINT_INIT(ret);
 
@@ -1656,26 +1655,65 @@ static void network_init(void)
 
   if (mysqld_port != 0 && !opt_disable_networking && !opt_bootstrap)
   {
+    struct addrinfo *ai, *a;
+    struct addrinfo hints;
+    int error;
     DBUG_PRINT("general",("IP Socket is %d",mysqld_port));
-    ip_sock = socket(AF_INET, SOCK_STREAM, 0);
+
+    bzero(&hints, sizeof (hints));
+    hints.ai_flags= AI_PASSIVE;
+    hints.ai_socktype= SOCK_STREAM;
+    hints.ai_family= AF_UNSPEC;
+
+    my_snprintf(port_buf, NI_MAXSERV, "%d", mysqld_port);
+    error= getaddrinfo(my_bind_addr_str, port_buf, &hints, &ai);
+    if (error != 0)
+    {
+      DBUG_PRINT("error",("Got error: %d from getaddrinfo()", error));
+      sql_perror(ER(ER_IPSOCK_ERROR));		/* purecov: tested */
+      unireg_abort(1);				/* purecov: tested */
+    }
+
+    for (a= ai; a != NULL; a= a->ai_next)
+    {
+      ip_sock= socket(a->ai_family, a->ai_socktype, a->ai_protocol);
+      if (ip_sock != INVALID_SOCKET)
+        break;
+    }
+
     if (ip_sock == INVALID_SOCKET)
     {
       DBUG_PRINT("error",("Got error: %d from socket()",socket_errno));
       sql_perror(ER(ER_IPSOCK_ERROR));		/* purecov: tested */
       unireg_abort(1);				/* purecov: tested */
     }
-    bzero((char*) &IPaddr, sizeof(IPaddr));
-    IPaddr.sin_family = AF_INET;
-    IPaddr.sin_addr.s_addr = my_bind_addr;
-    IPaddr.sin_port = (unsigned short) htons((unsigned short) mysqld_port);
 
 #ifndef __WIN__
     /*
       We should not use SO_REUSEADDR on windows as this would enable a
       user to open two mysqld servers with the same TCP/IP port.
     */
+    arg= 1;
     (void) setsockopt(ip_sock,SOL_SOCKET,SO_REUSEADDR,(char*)&arg,sizeof(arg));
 #endif /* __WIN__ */
+
+#ifdef IPV6_V6ONLY
+     /*
+       For interoperability with older clients, IPv6 socket should
+       listen on both IPv6 and IPv4 wildcard addresses.
+       Turn off IPV6_V6ONLY option.
+
+       NOTE: this will work starting from Windows Vista only.
+       On Windows XP dual stack is not available, so it will not
+       listen on the corresponding IPv4-address.
+     */
+    if (a->ai_family == AF_INET6)
+    {
+      arg= 0;
+      (void) setsockopt(ip_sock, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&arg,
+                sizeof(arg));
+    }
+#endif
     /*
       Sometimes the port is not released fast enough when stopping and
       restarting the server. This happens quite often with the test suite
@@ -1686,8 +1724,7 @@ static void network_init(void)
     */
     for (waited= 0, retry= 1; ; retry++, waited+= this_wait)
     {
-      if (((ret= bind(ip_sock, my_reinterpret_cast(struct sockaddr *) (&IPaddr),
-                      sizeof(IPaddr))) >= 0) ||
+      if (((ret= bind(ip_sock, a->ai_addr, a->ai_addrlen)) >= 0 ) ||
           (socket_errno != SOCKET_EADDRINUSE) ||
           (waited >= mysqld_port_timeout))
         break;
@@ -1695,6 +1732,7 @@ static void network_init(void)
       this_wait= retry * retry / 3 + 1;
       sleep(this_wait);
     }
+    freeaddrinfo(ai);
     if (ret < 0)
     {
       DBUG_PRINT("error",("Got error: %d from bind",socket_errno));
@@ -1716,7 +1754,6 @@ static void network_init(void)
   if (Service.IsNT() && mysqld_unix_port[0] && !opt_bootstrap &&
       opt_enable_named_pipe)
   {
-    
     strxnmov(pipe_name, sizeof(pipe_name)-1, "\\\\.\\pipe\\",
 	     mysqld_unix_port, NullS);
     bzero((char*) &saPipeSecurity, sizeof(saPipeSecurity));
@@ -1782,6 +1819,7 @@ static void network_init(void)
     UNIXaddr.sun_family = AF_UNIX;
     strmov(UNIXaddr.sun_path, mysqld_unix_port);
     (void) unlink(mysqld_unix_port);
+    arg= 1;
     (void) setsockopt(unix_sock,SOL_SOCKET,SO_REUSEADDR,(char*)&arg,
 		      sizeof(arg));
     umask(0);
@@ -4850,7 +4888,7 @@ static bool read_init_file(char *file_name)
 
      When we enter this function, LOCK_thread_count is hold!
 */
-   
+
 void handle_connection_in_main_thread(THD *thd)
 {
   safe_mutex_assert_owner(&LOCK_thread_count);
@@ -4933,7 +4971,6 @@ void create_thread_to_handle_connection(THD *thd)
 
 static void create_new_thread(THD *thd)
 {
-  NET *net=&thd->net;
   DBUG_ENTER("create_new_thread");
 
   /*
@@ -5003,6 +5040,7 @@ inline void kill_broken_server()
 	/* Handle new connections and spawn new process to handle them */
 
 #ifndef EMBEDDED_LIBRARY
+
 void handle_connections_sockets()
 {
   my_socket sock,new_sock;
@@ -5010,7 +5048,7 @@ void handle_connections_sockets()
   uint max_used_connection= (uint) (max(ip_sock,unix_sock)+1);
   fd_set readFDs,clientFDs;
   THD *thd;
-  struct sockaddr_in cAddr;
+  struct sockaddr_storage cAddr;
   int ip_flags=0,socket_flags=0,flags;
   st_vio *vio_tmp;
   DBUG_ENTER("handle_connections_sockets");
@@ -5084,9 +5122,9 @@ void handle_connections_sockets()
 #endif /* NO_FCNTL_NONBLOCK */
     for (uint retry=0; retry < MAX_ACCEPT_RETRY; retry++)
     {
-      size_socket length=sizeof(struct sockaddr_in);
-      new_sock = accept(sock, my_reinterpret_cast(struct sockaddr *) (&cAddr),
-			&length);
+      size_socket length= sizeof(struct sockaddr_storage);
+      new_sock= accept(sock, (struct sockaddr *)(&cAddr),
+                       &length);
 #ifdef __NETWARE__ 
       // TODO: temporary fix, waiting for TCP/IP fix - DEFECT000303149
       if ((new_sock == INVALID_SOCKET) && (socket_errno == EINVAL))
@@ -5157,9 +5195,10 @@ void handle_connections_sockets()
 
     {
       size_socket dummyLen;
-      struct sockaddr dummy;
-      dummyLen = sizeof(struct sockaddr);
-      if (getsockname(new_sock,&dummy, &dummyLen) < 0)
+      struct sockaddr_storage dummy;
+      dummyLen = sizeof(dummy);
+      if (  getsockname(new_sock,(struct sockaddr *)&dummy, 
+                  (SOCKET_SIZE_TYPE *)&dummyLen) < 0  )
       {
 	sql_perror("Error on new connection socket");
 	(void) shutdown(new_sock, SHUT_RDWR);
@@ -5505,7 +5544,7 @@ errorconn:
 	      NullS);
       sql_perror(buff);
     }
-    if (handle_client_file_map) 
+    if (handle_client_file_map)
       CloseHandle(handle_client_file_map);
     if (handle_client_map)
       UnmapViewOfFile(handle_client_map);
@@ -7786,7 +7825,6 @@ static int mysql_init_variables(void)
   strmov(server_version, MYSQL_SERVER_VERSION);
   myisam_recover_options_str= sql_mode_str= "OFF";
   myisam_stats_method_str= "nulls_unequal";
-  my_bind_addr = htonl(INADDR_ANY);
   threads.empty();
   thread_cache.empty();
   key_caches.empty();
@@ -8226,27 +8264,25 @@ mysqld_get_one_option(int optid,
     my_use_symdir=0;
     break;
   case (int) OPT_BIND_ADDRESS:
-    if ((my_bind_addr= (ulong) inet_addr(argument)) == INADDR_NONE)
     {
-      struct hostent *ent;
-      if (argument[0])
-	ent=gethostbyname(argument);
-      else
+      struct addrinfo *res_lst, hints;    
+
+      bzero(&hints, sizeof(struct addrinfo));
+      hints.ai_socktype= SOCK_STREAM;
+      hints.ai_protocol= IPPROTO_TCP;
+
+      if (getaddrinfo(argument, NULL, &hints, &res_lst) != 0) 
       {
-	char myhostname[255];
-	if (gethostname(myhostname,sizeof(myhostname)) < 0)
-	{
-	  sql_perror("Can't start server: cannot get my own hostname!");
-          return 1;
-	}
-	ent=gethostbyname(myhostname);
+        sql_print_error("Can't start server: cannot resolve hostname!");
+        return 1;
       }
-      if (!ent)
+
+      if (res_lst->ai_next)
       {
-	sql_perror("Can't start server: cannot resolve hostname!");
+        sql_print_error("Can't start server: bind-address refers to multiple interfaces!");
         return 1;
       }
-      my_bind_addr = (ulong) ((in_addr*)ent->h_addr_list[0])->s_addr;
+      freeaddrinfo(res_lst);
     }
     break;
   case (int) OPT_PID_FILE:
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 641423605aa..155e7298e90 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -1785,24 +1785,83 @@ static bool compare_hostname(const acl_host_and_ip *host, const char *hostname,
 	  (ip && !wild_compare(ip, host->hostname, 0)));
 }
 
+/**
+  Check if the given host name needs to be resolved or not.
+  Host name has to be resolved if it actually contains *name*.
+
+  For example:
+    192.168.1.1               --> FALSE
+    192.168.1.0/255.255.255.0 --> FALSE
+    %                         --> FALSE
+    192.168.1.%               --> FALSE
+    AB%                       --> FALSE
+
+    AAAAFFFF                  --> TRUE (Hostname)
+    AAAA:FFFF:1234:5678       --> FALSE
+    ::1                       --> FALSE
+
+  This function does not check if the given string is a valid host name or
+  not. It assumes that the argument is a valid host name.
+
+  @param hostname   the string to check.
+
+  @return a flag telling if the argument needs to be resolved or not.
+  @retval TRUE the argument is a host name and needs to be resolved.
+  @retval FALSE the argument is either an IP address, or a patter and
+          should not be resolved.
+*/
+
 bool hostname_requires_resolving(const char *hostname)
 {
-  char cur;
   if (!hostname)
     return FALSE;
-  size_t namelen= strlen(hostname);
-  size_t lhlen= strlen(my_localhost);
-  if ((namelen == lhlen) &&
-      !my_strnncoll(system_charset_info, (const uchar *)hostname,  namelen,
-		    (const uchar *)my_localhost, strlen(my_localhost)))
+
+  /* Check if hostname is the localhost. */
+
+  size_t hostname_len= strlen(hostname);
+  size_t localhost_len= strlen(my_localhost);
+
+  if (hostname == my_localhost ||
+      (hostname_len == localhost_len &&
+       !my_strnncoll(system_charset_info,
+                     (const uchar *) hostname,  hostname_len,
+                     (const uchar *) my_localhost, strlen(my_localhost))))
+  {
     return FALSE;
-  for (; (cur=*hostname); hostname++)
+  }
+
+  /*
+    If the string contains any of {':', '%', '_', '/'}, it is definitely
+    not a host name:
+      - ':' means that the string is an IPv6 address;
+      - '%' or '_' means that the string is a pattern;
+      - '/' means that the string is an IPv4 network address;
+  */
+
+  for (const char *p= hostname; *p; ++p)
   {
-    if ((cur != '%') && (cur != '_') && (cur != '.') && (cur != '/') &&
-	((cur < '0') || (cur > '9')))
-      return TRUE;
+    switch (*p) {
+      case ':':
+      case '%':
+      case '_':
+      case '/':
+        return FALSE;
+    }
   }
-  return FALSE;
+
+  /*
+    Now we have to tell a host name (ab.cd, 12.ab) from an IPv4 address
+    (12.34.56.78). The assumption is that if the string contains only
+    digits and dots, it is an IPv4 address. Otherwise -- a host name.
+  */
+
+  for (const char *p= hostname; *p; ++p)
+  {
+    if (*p != '.' && !my_isdigit(&my_charset_latin1, *p))
+      return TRUE; /* a "letter" has been found. */
+  }
+
+  return FALSE; /* all characters are either dots or digits. */
 }
 
 
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 03a92c1a685..551a2372632 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1238,7 +1238,6 @@ public:
   HASH    user_vars;			// hash for user variables
   String  packet;			// dynamic buffer for network I/O
   String  convert_buffer;               // buffer for charset conversions
-  struct  sockaddr_in remote;		// client socket address
   struct  rand_struct rand;		// used for authentication
   struct  system_variables variables;	// Changeable local variables
   struct  system_status_var status_var; // Per thread statistic vars
diff --git a/sql/sql_connect.cc b/sql/sql_connect.cc
index f5f962a02a3..8ecafce6f93 100644
--- a/sql/sql_connect.cc
+++ b/sql/sql_connect.cc
@@ -377,7 +377,8 @@ check_user(THD *thd, enum enum_server_command command,
     if (send_old_password_request(thd) ||
         my_net_read(net) != SCRAMBLE_LENGTH_323 + 1)
     {
-      inc_host_errors(&thd->remote.sin_addr);
+      inc_host_errors(thd->main_security_ctx.ip);
+
       my_error(ER_HANDSHAKE_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
       DBUG_RETURN(1);
     }
@@ -498,9 +499,9 @@ check_user(THD *thd, enum enum_server_command command,
                     thd->main_security_ctx.host_or_ip,
                     passwd_len ? ER(ER_YES) : ER(ER_NO));
   /*
-    log access denied messages to the error log when log-warnings = 2
+    Log access denied messages to the error log when log-warnings = 2
     so that the overhead of the general query log is not required to track
-    failed connections
+    failed connections.
   */
   if (global_system_variables.log_warnings > 1)
   {
@@ -666,9 +667,9 @@ static int check_connection(THD *thd)
 
   if (!thd->main_security_ctx.host)         // If TCP/IP connection
   {
-    char ip[30];
+    char ip[NI_MAXHOST];
 
-    if (vio_peer_addr(net->vio, ip, &thd->peer_port))
+    if (vio_peer_addr(net->vio, ip, &thd->peer_port, NI_MAXHOST))
     {
       my_error(ER_BAD_HOST_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
       return 1;
@@ -676,12 +677,15 @@ static int check_connection(THD *thd)
     if (!(thd->main_security_ctx.ip= my_strdup(ip,MYF(MY_WME))))
       return 1; /* The error is set by my_strdup(). */
     thd->main_security_ctx.host_or_ip= thd->main_security_ctx.ip;
-    vio_in_addr(net->vio,&thd->remote.sin_addr);
     if (!(specialflag & SPECIAL_NO_RESOLVE))
     {
-      vio_in_addr(net->vio,&thd->remote.sin_addr);
-      thd->main_security_ctx.host=
-        ip_to_hostname(&thd->remote.sin_addr, &connect_errors);
+      if (ip_to_hostname(&net->vio->remote, thd->main_security_ctx.ip,
+                         &thd->main_security_ctx.host, &connect_errors))
+      {
+        my_error(ER_BAD_HOST_ERROR, MYF(0), ip);
+        return 1;
+      }
+
       /* Cut very long hostnames to avoid possible overflows */
       if (thd->main_security_ctx.host)
       {
@@ -714,7 +718,7 @@ static int check_connection(THD *thd)
     thd->main_security_ctx.host_or_ip= thd->main_security_ctx.host;
     thd->main_security_ctx.ip= 0;
     /* Reset sin_addr */
-    bzero((char*) &thd->remote, sizeof(thd->remote));
+    bzero((char*) &net->vio->remote, sizeof(net->vio->remote));
   }
   vio_keepalive(net->vio, TRUE);
   
@@ -769,7 +773,8 @@ static int check_connection(THD *thd)
 	(pkt_len= my_net_read(net)) == packet_error ||
 	pkt_len < MIN_HANDSHAKE_SIZE)
     {
-      inc_host_errors(&thd->remote.sin_addr);
+      inc_host_errors(thd->main_security_ctx.ip);
+
       my_error(ER_HANDSHAKE_ERROR, MYF(0),
                thd->main_security_ctx.host_or_ip);
       return 1;
@@ -779,7 +784,7 @@ static int check_connection(THD *thd)
 #include "_cust_sql_parse.h"
 #endif
   if (connect_errors)
-    reset_host_errors(&thd->remote.sin_addr);
+    reset_host_errors(thd->main_security_ctx.ip);
   if (thd->packet.alloc(thd->variables.net_buffer_length))
     return 1; /* The error is set by alloc(). */
 
@@ -813,7 +818,7 @@ static int check_connection(THD *thd)
     /* Do the SSL layering. */
     if (!ssl_acceptor_fd)
     {
-      inc_host_errors(&thd->remote.sin_addr);
+      inc_host_errors(thd->main_security_ctx.ip);
       my_error(ER_HANDSHAKE_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
       return 1;
     }
@@ -821,7 +826,8 @@ static int check_connection(THD *thd)
     if (sslaccept(ssl_acceptor_fd, net->vio, net->read_timeout))
     {
       DBUG_PRINT("error", ("Failed to accept new SSL connection"));
-      inc_host_errors(&thd->remote.sin_addr);
+      inc_host_errors(thd->main_security_ctx.ip);
+
       my_error(ER_HANDSHAKE_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
       return 1;
     }
@@ -831,7 +837,8 @@ static int check_connection(THD *thd)
     {
       DBUG_PRINT("error", ("Failed to read user information (pkt_len= %lu)",
 			   pkt_len));
-      inc_host_errors(&thd->remote.sin_addr);
+      inc_host_errors(thd->main_security_ctx.ip);
+
       my_error(ER_HANDSHAKE_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
       return 1;
     }
@@ -840,7 +847,8 @@ static int check_connection(THD *thd)
 
   if (end >= (char*) net->read_pos+ pkt_len +2)
   {
-    inc_host_errors(&thd->remote.sin_addr);
+    inc_host_errors(thd->main_security_ctx.ip);
+
     my_error(ER_HANDSHAKE_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
     return 1;
   }
@@ -878,7 +886,8 @@ static int check_connection(THD *thd)
 
   if (passwd + passwd_len + db_len > (char *)net->read_pos + pkt_len)
   {
-    inc_host_errors(&thd->remote.sin_addr);
+    inc_host_errors(thd->main_security_ctx.ip);
+
     my_error(ER_HANDSHAKE_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
     return 1;
   }
diff --git a/vio/vio.c b/vio/vio.c
index 34e02adae3d..b7bac69fc3c 100644
--- a/vio/vio.c
+++ b/vio/vio.c
@@ -78,7 +78,6 @@ static void vio_init(Vio* vio, enum enum_vio_type type,
     vio->was_interrupted=vio_was_interrupted;
     vio->vioclose	=vio_close_pipe;
     vio->peer_addr	=vio_peer_addr;
-    vio->in_addr	=vio_in_addr;
     vio->vioblocking	=vio_blocking;
     vio->is_blocking	=vio_is_blocking;
 
@@ -108,7 +107,6 @@ static void vio_init(Vio* vio, enum enum_vio_type type,
     vio->was_interrupted=vio_was_interrupted;
     vio->vioclose	=vio_close_shared_memory;
     vio->peer_addr	=vio_peer_addr;
-    vio->in_addr	=vio_in_addr;
     vio->vioblocking	=vio_blocking;
     vio->is_blocking	=vio_is_blocking;
 
@@ -136,7 +134,6 @@ static void vio_init(Vio* vio, enum enum_vio_type type,
     vio->was_interrupted=vio_was_interrupted;
     vio->vioclose	=vio_ssl_close;
     vio->peer_addr	=vio_peer_addr;
-    vio->in_addr	=vio_in_addr;
     vio->vioblocking	=vio_ssl_blocking;
     vio->is_blocking	=vio_is_blocking;
     vio->timeout	=vio_timeout;
@@ -156,7 +153,6 @@ static void vio_init(Vio* vio, enum enum_vio_type type,
     vio->was_interrupted=vio_was_interrupted;
     vio->vioclose	=vio_close;
     vio->peer_addr	=vio_peer_addr;
-    vio->in_addr	=vio_in_addr;
     vio->vioblocking	=vio_blocking;
     vio->is_blocking	=vio_is_blocking;
     vio->timeout	=vio_timeout;
diff --git a/vio/vio_priv.h b/vio/vio_priv.h
index c1ac2ab8365..fd4d767b271 100644
--- a/vio/vio_priv.h
+++ b/vio/vio_priv.h
@@ -25,6 +25,11 @@
 #include <m_string.h>
 #include <violite.h>
 
+#ifndef _WIN_
+#include <sys/socket.h>
+#include <netdb.h>
+#endif
+
 #ifdef _WIN32
 void	vio_win32_timeout(Vio *vio, uint which, uint timeout);
 #endif
diff --git a/vio/viosocket.c b/vio/viosocket.c
index 51345d072b2..8dcf978f2fa 100644
--- a/vio/viosocket.c
+++ b/vio/viosocket.c
@@ -300,53 +300,209 @@ my_socket vio_fd(Vio* vio)
   return vio->sd;
 }
 
+/**
+  Convert a sock-address (AF_INET or AF_INET6) into the "normalized" form,
+  which is the IPv4 form for IPv4-mapped or IPv4-compatible IPv6 addresses.
+
+  @note Background: when IPv4 and IPv6 are used simultaneously, IPv4
+  addresses may be written in a form of IPv4-mapped or IPv4-compatible IPv6
+  addresses. That means, one address (a.b.c.d) can be written in three forms:
+    - IPv4: a.b.c.d;
+    - IPv4-compatible IPv6: ::a.b.c.d;
+    - IPv4-mapped IPv4: ::ffff:a.b.c.d;
+
+  Having three forms of one address makes it a little difficult to compare
+  addresses with each other (the IPv4-compatible IPv6-address of foo.bar
+  will be different from the IPv4-mapped IPv6-address of foo.bar).
+
+  @note This function can be made public when it's needed.
+
+  @param src        [in] source IP address (AF_INET or AF_INET6).
+  @param src_length [in] length of the src.
+  @param dst        [out] a buffer to store normalized IP address
+                          (sockaddr_storage).
+  @param dst_length [out] actual length of the normalized IP address.
+*/
+static void vio_get_normalized_ip(const struct sockaddr *src,
+                                  int src_length,
+                                  struct sockaddr *dst,
+                                  int *dst_length)
+{
+  switch (src->sa_family) {
+  case AF_INET:
+    memcpy(dst, src, src_length);
+    *dst_length= src_length;
+    break;
+
+#ifdef HAVE_IPV6
+  case AF_INET6:
+  {
+    const struct sockaddr_in6 *src_addr6= (const struct sockaddr_in6 *) src;
+    const struct in6_addr *src_ip6= &(src_addr6->sin6_addr);
+    const uint32 *src_ip6_int32= (uint32 *) src_ip6->s6_addr;
+
+    if (IN6_IS_ADDR_V4MAPPED(src_ip6) || IN6_IS_ADDR_V4COMPAT(src_ip6))
+    {
+      struct sockaddr_in *dst_ip4= (struct sockaddr_in *) dst;
+
+      /*
+        This is an IPv4-mapped or IPv4-compatible IPv6 address. It should
+        be converted to the IPv4 form.
+      */
+
+      *dst_length= sizeof (struct sockaddr_in);
 
-my_bool vio_peer_addr(Vio * vio, char *buf, uint16 *port)
+      memset(dst_ip4, 0, *dst_length);
+      dst_ip4->sin_family= AF_INET;
+      dst_ip4->sin_port= src_addr6->sin6_port;
+
+      /*
+        In an IPv4 mapped or compatible address, the last 32 bits represent
+        the IPv4 address. The byte orders for IPv6 and IPv4 addresses are
+        the same, so a simple copy is possible.
+      */
+      dst_ip4->sin_addr.s_addr= src_ip6_int32[3];
+    }
+    else
+    {
+      /* This is a "native" IPv6 address. */
+
+      memcpy(dst, src, src_length);
+      *dst_length= src_length;
+    }
+
+    break;
+  }
+#endif /* HAVE_IPV6 */
+  }
+}
+
+
+/**
+  Return the normalized IP address string for a sock-address.
+
+  The idea is to return an IPv4-address for an IPv4-mapped and
+  IPv4-compatible IPv6 address.
+
+  The function writes the normalized IP address to the given buffer.
+  The buffer should have enough space, otherwise error flag is returned.
+  The system constant INET6_ADDRSTRLEN can be used to reserve buffers of
+  the right size.
+
+  @param addr           [in]  sockaddr object (AF_INET or AF_INET6).
+  @param addr_length    [in]  length of the addr.
+  @param ip_string      [out] buffer to write normalized IP address.
+  @param ip_string_size [in]  size of the ip_string.
+
+  @return Error status.
+  @retval TRUE in case of error (the ip_string buffer is not enough).
+  @retval FALSE on success.
+*/
+
+my_bool vio_get_normalized_ip_string(const struct sockaddr *addr,
+                                     int addr_length,
+                                     char *ip_string,
+                                     size_t ip_string_size)
+{
+  struct sockaddr_storage norm_addr_storage;
+  struct sockaddr *norm_addr= (struct sockaddr *) &norm_addr_storage;
+  int norm_addr_length;
+  int err_code;
+
+  vio_get_normalized_ip(addr, addr_length, norm_addr, &norm_addr_length);
+
+  err_code= vio_getnameinfo(norm_addr, ip_string, ip_string_size, NULL, 0,
+                            NI_NUMERICHOST);
+
+  if (!err_code)
+    return FALSE;
+
+  DBUG_PRINT("error", ("getnameinfo() failed with %d (%s).",
+                       (int) err_code,
+                       (const char *) gai_strerror(err_code)));
+  return TRUE;
+}
+
+
+/**
+  Return IP address and port of a VIO client socket.
+
+  The function returns an IPv4 address if IPv6 support is disabled.
+
+  The function returns an IPv4 address if the client socket is associated
+  with an IPv4-compatible or IPv4-mapped IPv6 address. Otherwise, the native
+  IPv6 address is returned.
+*/
+
+my_bool vio_peer_addr(Vio *vio, char *ip_buffer, uint16 *port,
+                      size_t ip_buffer_size)
 {
   DBUG_ENTER("vio_peer_addr");
-  DBUG_PRINT("enter", ("sd: %d", vio->sd));
+  DBUG_PRINT("enter", ("Client socked fd: %d", (int) vio->sd));
+
   if (vio->localhost)
   {
-    strmov(buf,"127.0.0.1");
+    /*
+      Initialize vio->remote and vio->addLen. Set vio->remote to IPv4 loopback
+      address.
+    */
+    struct in_addr *ip4= &((struct sockaddr_in *) &(vio->remote))->sin_addr;
+
+    vio->remote.ss_family= AF_INET;
+    vio->addrLen= sizeof (struct sockaddr_in);
+
+    ip4->s_addr= htonl(INADDR_LOOPBACK);
+
+    /* Initialize ip_buffer and port. */
+
+    strmov(ip_buffer, "127.0.0.1");
     *port= 0;
   }
   else
   {
-    size_socket addrLen = sizeof(vio->remote);
-    if (getpeername(vio->sd, (struct sockaddr *) (&vio->remote),
-		    &addrLen) != 0)
+    int err_code;
+    char port_buffer[NI_MAXSERV];
+
+    struct sockaddr_storage addr_storage;
+    struct sockaddr *addr= (struct sockaddr *) &addr_storage;
+    size_socket addr_length= sizeof (addr_storage);
+
+    /* Get sockaddr by socked fd. */
+
+    err_code= getpeername(vio->sd, addr, &addr_length);
+
+    if (err_code)
     {
-      DBUG_PRINT("exit", ("getpeername gave error: %d", socket_errno));
-      DBUG_RETURN(1);
+      DBUG_PRINT("exit", ("getpeername() gave error: %d", socket_errno));
+      DBUG_RETURN(TRUE);
     }
-    my_inet_ntoa(vio->remote.sin_addr,buf);
-    *port= ntohs(vio->remote.sin_port);
-  }
-  DBUG_PRINT("exit", ("addr: %s", buf));
-  DBUG_RETURN(0);
-}
 
+    /* Normalize IP address. */
 
-/*
-  Get in_addr for a TCP/IP connection
+    vio_get_normalized_ip(addr, addr_length,
+                          (struct sockaddr *) &vio->remote, &vio->addrLen);
 
-  SYNOPSIS
-    vio_in_addr()
-    vio		vio handle
-    in		put in_addr here
+    /* Get IP address & port number. */
 
-  NOTES
-    one must call vio_peer_addr() before calling this one
-*/
+    err_code= vio_getnameinfo((struct sockaddr *) &vio->remote,
+                              ip_buffer, ip_buffer_size,
+                              port_buffer, NI_MAXSERV,
+                              NI_NUMERICHOST | NI_NUMERICSERV);
 
-void vio_in_addr(Vio *vio, struct in_addr *in)
-{
-  DBUG_ENTER("vio_in_addr");
-  if (vio->localhost)
-    bzero((char*) in, sizeof(*in));
-  else
-    *in=vio->remote.sin_addr;
-  DBUG_VOID_RETURN;
+    if (err_code)
+    {
+      DBUG_PRINT("exit", ("getnameinfo() gave error: %s",
+                          gai_strerror(err_code)));
+      DBUG_RETURN(TRUE);
+    }
+
+    *port= (uint16) strtol(port_buffer, NULL, 10);
+  }
+
+  DBUG_PRINT("exit", ("Client IP address: %s; port: %d",
+                      (const char *) ip_buffer,
+                      (int) *port));
+  DBUG_RETURN(FALSE);
 }
 
 
@@ -377,7 +533,8 @@ static my_bool socket_poll_read(my_socket sd, uint timeout)
   FD_ZERO(&errorfds);
   FD_SET(fd, &readfds);
   FD_SET(fd, &errorfds);
-  if ((res= select(fd, &readfds, NULL, &errorfds, &tm) <= 0))
+  /* The first argument is ignored on Windows, so a conversion to int is OK */
+  if ((res= select((int) fd, &readfds, NULL, &errorfds, &tm) <= 0))
   {
     DBUG_RETURN(res < 0 ? 0 : 1);
   }
@@ -879,3 +1036,36 @@ ssize_t vio_pending(Vio *vio)
 
   return 0;
 }
+
+
+/**
+  This is a wrapper for the system getnameinfo(), because different OS
+  differ in the getnameinfo() implementation. For instance, Solaris 10
+  requires that the 2nd argument (salen) must match the actual size of the
+  struct sockaddr_storage passed to it.
+*/
+
+int vio_getnameinfo(const struct sockaddr *sa,
+                    char *hostname, size_t hostname_size,
+                    char *port, size_t port_size,
+                    int flags)
+{
+  int sa_length= 0;
+
+  switch (sa->sa_family) {
+  case AF_INET:
+    sa_length= sizeof (struct sockaddr_in);
+    break;
+
+#ifdef HAVE_IPV6
+  case AF_INET6:
+    sa_length= sizeof (struct sockaddr_in6);
+    break;
+#endif /* HAVE_IPV6 */
+  }
+
+  return getnameinfo(sa, sa_length,
+                     hostname, hostname_size,
+                     port, port_size,
+                     flags);
+}