MDEV-6536: make --bind=hostname to listen on both IPv6 and IPv4 addresses

Binding to a hostname now makes MariaDB server to listen on all addresses
that hostname resolves to.

Rebased to 10.6 by Daniel Black

Closes: #1668

include/mysql/psi/mysql_socket.h

@@ -75,6 +75,15 @@ struct st_mysql_socket
   /** The real socket descriptor. */
   my_socket fd;
 
+  /** Is this a Unix-domain socket? */
+  char is_unix_domain_socket;
+
+  /** Is this a socket opened for the extra port? */
+  char is_extra_port;
+
+  /** Address family of the socket. (See sa_family from struct sockaddr). */
+  unsigned short address_family;
+
   /**
     The instrumentation hook.
     Note that this hook is not conditionally defined,
@@ -105,7 +114,7 @@ typedef struct st_mysql_socket MYSQL_SOCKET;
 static inline MYSQL_SOCKET
 mysql_socket_invalid()
 {
-  MYSQL_SOCKET mysql_socket= {INVALID_SOCKET, NULL};
+  MYSQL_SOCKET mysql_socket= {INVALID_SOCKET, 0, 0, 0, NULL};
   return mysql_socket;
 }
 

mysql-test/main/bind_address_resolution.opt

+--bind-address=localhost

mysql-test/main/bind_address_resolution.result

+CREATE TABLE t (a TEXT);
+connect con1,localhost,root,,test;
+SELECT * FROM t;
+a
+connect con2,127.0.0.1,root,,test;
+SELECT * FROM t;
+a
+connect con3,::1,root,,test;
+SELECT * FROM t;
+a
+connection default;
+DROP TABLE t;
+disconnect con1;
+disconnect con2;
+disconnect con3;

mysql-test/main/bind_address_resolution.test

+--source include/check_ipv6.inc
+--source include/not_embedded.inc
+
+# The server is started with --bind-address=localhost, and should
+# listen on all addresses 'localhost' resolves to. With at least
+# 127.0.0.1 and ::1 amongst them.
+
+CREATE TABLE t (a TEXT);
+--connect(con1,localhost,root,,test)
+SELECT * FROM t;
+--connect(con2,127.0.0.1,root,,test)
+SELECT * FROM t;
+--connect(con3,::1,root,,test)
+SELECT * FROM t;
+--connection default
+DROP TABLE t;
+--disconnect con1
+--disconnect con2
+--disconnect con3

mysql-test/suite/perfschema/r/socket_instances_func.result

@@ -80,15 +80,16 @@ Expect 1
 1
 # Characteristics of 'server_tcpip_socket' entry
 #    Server listening socket, TCP/IP
-#    There is only one entry with 'wait/io/socket/sql/server_tcpip_socket'.
-#    It shares the same thread id as 'wait/io/socket/sql/server_unix_socket'.
-SELECT COUNT(*) = 1 AS 'Expect 1'
+#    There are two entries with 'wait/io/socket/sql/server_tcpip_socket',
+#    for [::] and for 0.0.0.0.
+#    They share the same thread id with 'wait/io/socket/sql/server_unix_socket'.
+SELECT COUNT(*) = 2 AS 'Expect 1'
 FROM performance_schema.socket_instances
 WHERE EVENT_NAME = 'wait/io/socket/sql/server_tcpip_socket';
 Expect 1
 1
 # Get the 'server_tcpip_socket' thread id
-SELECT THREAD_ID INTO @thread_id
+SELECT DISTINCT THREAD_ID INTO @thread_id
 FROM performance_schema.socket_instances
 WHERE EVENT_NAME = 'wait/io/socket/sql/server_tcpip_socket';
 #    Check the content.
@@ -100,6 +101,7 @@ FROM performance_schema.socket_instances
 WHERE EVENT_NAME = 'wait/io/socket/sql/server_tcpip_socket';
 Expect 1
 1
+1
 # Characteristics of 'server_unix_socket' entry
 #    Server listening socket, unix domain (socket file)
 #    There is only one entry with 'wait/io/socket/sql/server_unix_socket'.
@@ -123,12 +125,12 @@ WHERE EVENT_NAME = 'wait/io/socket/sql/server_unix_socket';
 Expect 1
 1
 # Server listening sockets (TCP and Unix) are handled on the same thread
-SELECT COUNT(*) = 2 AS 'Expect 1'
+SELECT COUNT(*) = 3 AS 'Expect 1'
 FROM performance_schema.socket_instances
 WHERE THREAD_ID = @thread_id;
 Expect 1
 1
-SELECT COUNT(*) = 2 AS 'Expect 1'
+SELECT COUNT(*) = 3 AS 'Expect 1'
 FROM performance_schema.socket_instances
 WHERE THREAD_ID = @thread_id;
 Expect 1

mysql-test/suite/perfschema/t/socket_instances_func.test

@@ -38,6 +38,10 @@ if($my_socket_debug)
   --echo IPV6=$check_ipv6_supported, IPV4_MAPPED=$check_ipv4_mapped_supported, LOCALHOST=$my_localhost
 }
 
+# This test only runs when IPv6 is supported (see include/check_ipv6.inc), so
+# the server will listen on both IPv4 and IPv6 wildcard addresses. That's why
+# the expected number of TCP/IP listeners is always 2.
+
 #
 # Preserve the current state of SOCKET_INSTANCES
 #
@@ -222,17 +226,18 @@ AND PORT = 0 AND THREAD_ID = @thread_id;
 
 --echo # Characteristics of 'server_tcpip_socket' entry
 --echo #    Server listening socket, TCP/IP
---echo #    There is only one entry with 'wait/io/socket/sql/server_tcpip_socket'.
---echo #    It shares the same thread id as 'wait/io/socket/sql/server_unix_socket'.
+--echo #    There are two entries with 'wait/io/socket/sql/server_tcpip_socket',
+--echo #    for [::] and for 0.0.0.0.
+--echo #    They share the same thread id with 'wait/io/socket/sql/server_unix_socket'.
 
-SELECT COUNT(*) = 1 AS 'Expect 1'
+SELECT COUNT(*) = 2 AS 'Expect 1'
 FROM performance_schema.socket_instances
 WHERE EVENT_NAME = 'wait/io/socket/sql/server_tcpip_socket';
 
 # Store the thread id of server_tcpip_socket
 --echo # Get the 'server_tcpip_socket' thread id
 
-SELECT THREAD_ID INTO @thread_id
+SELECT DISTINCT THREAD_ID INTO @thread_id
 FROM performance_schema.socket_instances
 WHERE EVENT_NAME = 'wait/io/socket/sql/server_tcpip_socket';
 
@@ -288,14 +293,14 @@ WHERE EVENT_NAME = 'wait/io/socket/sql/server_unix_socket';
 --disable_query_log ONCE
 eval SET @thread_id = $server_tcpip_thread_id;
 
-eval SELECT COUNT(*) = 2 AS 'Expect 1'
+eval SELECT COUNT(*) = 3 AS 'Expect 1'
 FROM performance_schema.socket_instances
 WHERE THREAD_ID = @thread_id;
 
 --disable_query_log ONCE
 eval SET @thread_id = $server_unix_thread_id;
 
-eval SELECT COUNT(*) = 2 AS 'Expect 1'
+eval SELECT COUNT(*) = 3 AS 'Expect 1'
 FROM performance_schema.socket_instances
 WHERE THREAD_ID = @thread_id;
 

mysql-test/suite/rpl/t/rpl_ipv6.cnf

@@ -12,7 +12,7 @@ log-bin=                 master-bin
 loose-innodb
 
 skip-name-resolve
-bind-address=               ::
+bind-address=               *
 
 
 [mysqld.2]
@@ -38,7 +38,7 @@ report-user=                root
 
 skip-slave-start
 skip-name-resolve
-bind-address=               ::
+bind-address=               *
 
 # Directory where slaves find the dumps generated by "load data"
 # on the server. The path need to have constant length otherwise

sql/handle_connections_win.cc

@@ -22,11 +22,13 @@
 #include <mswsock.h>
 #include <mysql/psi/mysql_socket.h>
 #include <sddl.h>
+#include <vector>
 
 #include <handle_connections_win.h>
 
 /* From mysqld.cc */
-extern MYSQL_SOCKET base_ip_sock, extra_ip_sock;
+extern HANDLE hEventShutdown;
+extern std::vector<MYSQL_SOCKET> listen_sockets;
 #ifdef HAVE_POOL_OF_THREADS
 extern PTP_CALLBACK_ENVIRON get_threadpool_win_callback_environ();
 extern void tp_win_callback_prolog();
@@ -128,6 +130,9 @@ struct Socket_Listener: public Listener
   /** Client socket passed to AcceptEx() call.*/
   SOCKET m_client_socket;
 
+  /** Listening socket. */
+  MYSQL_SOCKET m_listen_socket;
+
   /** Buffer for sockaddrs passed to AcceptEx()/GetAcceptExSockaddrs() */
   char m_buffer[2 * sizeof(sockaddr_storage) + 32];
 
@@ -162,7 +167,8 @@ struct Socket_Listener: public Listener
   */
   Socket_Listener(MYSQL_SOCKET listen_socket, PTP_CALLBACK_ENVIRON callback_environ) :
     Listener((HANDLE)listen_socket.fd,0),
-    m_client_socket(INVALID_SOCKET)
+    m_client_socket(INVALID_SOCKET),
+    m_listen_socket(listen_socket)
   {
     if (callback_environ)
     {
@@ -184,7 +190,8 @@ struct Socket_Listener: public Listener
   void begin_accept()
   {
 retry :
-    m_client_socket= socket(server_socket_ai_family, SOCK_STREAM, IPPROTO_TCP);
+    m_client_socket= socket(m_listen_socket.address_family, SOCK_STREAM,
+                            IPPROTO_TCP);
     if (m_client_socket == INVALID_SOCKET)
     {
       sql_perror("socket() call failed.");
@@ -233,7 +240,6 @@ retry :
     }
 
     MYSQL_SOCKET s_client{m_client_socket};
-    MYSQL_SOCKET s_listen{(SOCKET)m_handle};
 
 #ifdef HAVE_PSI_SOCKET_INTERFACE
     /* Parse socket addresses buffer filled by AcceptEx(),
@@ -246,7 +252,8 @@ retry :
       &local_addr, &local_addr_len, &remote_addr, &remote_addr_len);
 
     s_client.m_psi= PSI_SOCKET_CALL(init_socket)
-      (key_socket_client_connection, (const my_socket*)&s_listen.fd, remote_addr, remote_addr_len);
+      (key_socket_client_connection, (const my_socket*)&m_listen_socket.fd,
+       remote_addr, remote_addr_len);
 #endif
 
     /* Start accepting new connection. After this point, do not use
@@ -255,7 +262,7 @@ retry :
 
     /* Some chores post-AcceptEx() that we need to create a normal socket.*/
     if (setsockopt(s_client.fd, SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT,
-      (char *)&s_listen.fd, sizeof(s_listen.fd)))
+      (char *)&m_listen_socket.fd, sizeof(m_listen_socket.fd)))
     {
       if (!abort_loop)
       {
@@ -265,7 +272,7 @@ retry :
     }
 
     /* Create a new connection.*/
-    handle_accepted_socket(s_client, s_listen);
+    handle_accepted_socket(s_client, m_listen_socket);
   }
 
   ~Socket_Listener()
@@ -280,14 +287,12 @@ retry :
   */
   static void init_winsock_extensions()
   {
-    SOCKET s= mysql_socket_getfd(base_ip_sock);
-    if (s == INVALID_SOCKET)
-      s= mysql_socket_getfd(extra_ip_sock);
-    if (s == INVALID_SOCKET)
-    {
+    if (listen_sockets.size() == 0) {
       /* --skip-networking was used*/
       return;
     }
+
+    SOCKET s= mysql_socket_getfd(listen_sockets[0]);
     GUID guid_AcceptEx= WSAID_ACCEPTEX;
     GUID guid_GetAcceptExSockaddrs= WSAID_GETACCEPTEXSOCKADDRS;
 
@@ -540,22 +545,24 @@ static void create_shutdown_event()
 */
 
 
-#define MAX_WAIT_HANDLES 32
 #define NUM_PIPE_LISTENERS 24
 #define SHUTDOWN_IDX 0
 #define LISTENER_START_IDX 1
 
-static Listener *all_listeners[MAX_WAIT_HANDLES];
-static HANDLE wait_events[MAX_WAIT_HANDLES];
-static int n_listeners;
+static std::vector<Listener *> all_listeners;
+static std::vector<HANDLE> wait_events;
 
 void network_init_win()
 {
   Socket_Listener::init_winsock_extensions();
 
   /* Listen for TCP connections on "extra-port" (no threadpool).*/
-  if (extra_ip_sock.fd != INVALID_SOCKET)
-    all_listeners[n_listeners++]= new Socket_Listener(extra_ip_sock, 0);
+  for (std::vector<MYSQL_SOCKET>::iterator it= listen_sockets.begin();
+       it != listen_sockets.end(); ++it)
+  {
+    if (it->is_extra_port)
+      all_listeners.push_back(new Socket_Listener(*it, 0));
+  }
 
   /* Listen for named pipe connections */
   if (mysqld_unix_port[0] && !opt_bootstrap && opt_enable_named_pipe)
@@ -564,17 +571,22 @@ void network_init_win()
       Use several listeners for pipe, to reduce ERROR_PIPE_BUSY on client side.
     */
     for (int i= 0; i < NUM_PIPE_LISTENERS; i++)
-      all_listeners[n_listeners++]= new Pipe_Listener();
+      all_listeners.push_back(new Pipe_Listener());
   }
 
-  if (base_ip_sock.fd != INVALID_SOCKET)
+  for (std::vector<MYSQL_SOCKET>::iterator it= listen_sockets.begin();
+       it != listen_sockets.end(); ++it)
   {
-     /* Wait for TCP connections.*/
-    SetFileCompletionNotificationModes((HANDLE)base_ip_sock.fd, FILE_SKIP_SET_EVENT_ON_HANDLE);
-    all_listeners[n_listeners++]= new Socket_Listener(base_ip_sock, get_threadpool_win_callback_environ());
+    if (it->is_extra_port)
+      continue;
+    /* Wait for TCP connections.*/
+    SetFileCompletionNotificationModes((HANDLE)it->fd,
+                                       FILE_SKIP_SET_EVENT_ON_HANDLE);
+    all_listeners.push_back(
+      new Socket_Listener(*it, get_threadpool_win_callback_environ()));
   }
 
-  if (!n_listeners && !opt_bootstrap)
+  if (all_listeners.size() == 0 && !opt_bootstrap)
   {
     sql_print_error("Either TCP connections or named pipe connections must be enabled.");
     unireg_abort(1);
@@ -586,26 +598,41 @@ void handle_connections_win()
   int n_waits;
 
   create_shutdown_event();
-  wait_events[SHUTDOWN_IDX]= hEventShutdown;
+  wait_events.push_back(hEventShutdown);
   n_waits= 1;
 
-  for (int i= 0; i < n_listeners; i++)
+  for (int i= 0; i < all_listeners.size(); i++)
   {
     HANDLE wait_handle= all_listeners[i]->wait_handle();
     if (wait_handle)
     {
       DBUG_ASSERT((i == 0) || (all_listeners[i - 1]->wait_handle() != 0));
-      wait_events[n_waits++]= wait_handle;
+      wait_events.push_back(wait_handle);
     }
     all_listeners[i]->begin_accept();
   }
 
   mysqld_win_set_startup_complete();
 
+  // WaitForMultipleObjects can't wait on more than MAXIMUM_WAIT_OBJECTS
+  // handles simultaneously. Since MAXIMUM_WAIT_OBJECTS is only 64, there is
+  // a theoretical possiblity of exceeding that limit on installations where
+  // host name resolves to a lot of addresses.
+  if (wait_events.size() > MAXIMUM_WAIT_OBJECTS)
+  {
+    sql_print_warning(
+      "Too many wait events (%lu). Some connection listeners won't be handled. "
+      "Try to switch \"thread-handling\" to \"pool-of-threads\" and/or disable "
+      "\"extra-port\".", static_cast<ulong>(wait_events.size()));
+    wait_events.resize(MAXIMUM_WAIT_OBJECTS);
+  }
+
   for (;;)
   {
-    DWORD idx = WaitForMultipleObjects(n_waits ,wait_events, FALSE, INFINITE);
-    DBUG_ASSERT((int)idx >= 0 && (int)idx < n_waits);
+    DBUG_ASSERT(wait_events.size() <= MAXIMUM_WAIT_OBJECTS);
+    DWORD idx = WaitForMultipleObjects((DWORD)wait_events.size(),
+                                       wait_events.data(), FALSE, INFINITE);
+    DBUG_ASSERT((int)idx >= 0 && (int)idx < (int)wait_events.size());
 
     if (idx == SHUTDOWN_IDX)
       break;
@@ -616,7 +643,7 @@ void handle_connections_win()
   mysqld_win_initiate_shutdown();
 
   /* Cleanup */
-  for (int i= 0; i < n_listeners; i++)
+  for (size_t i= 0; i < all_listeners.size(); i++)
   {
     Listener *listener= all_listeners[i];
     if (listener->wait_handle())

sql/mysqld.cc

@@ -338,7 +338,6 @@ static char *character_set_filesystem_name;
 static char *lc_messages;
 static char *lc_time_names_name;
 char *my_bind_addr_str;
-int server_socket_ai_family;
 static char *default_collation_name;
 char *default_storage_engine, *default_tmp_storage_engine;
 char *enforced_storage_engine=NULL;
@@ -1349,7 +1348,8 @@ static Buffered_logs buffered_logs;
 struct my_rnd_struct sql_rand; ///< used by sql_class.cc:THD::THD()
 
 #ifndef EMBEDDED_LIBRARY
-MYSQL_SOCKET unix_sock, base_ip_sock, extra_ip_sock;
+std::vector<MYSQL_SOCKET> listen_sockets;
+bool unix_sock_is_online= false;
 /**
   Error reporter that buffer log messages.
   @param level          log message level
@@ -1690,28 +1690,15 @@ static void close_connections(void)
 
   /* Abort listening to new connections */
   DBUG_PRINT("quit",("Closing sockets"));
-  if (!opt_disable_networking )
+  for (std::vector<MYSQL_SOCKET>::iterator sock = listen_sockets.begin();
+       sock != listen_sockets.end(); ++sock)
   {
-    if (mysql_socket_getfd(base_ip_sock) != INVALID_SOCKET)
-    {
-      (void) mysql_socket_close(base_ip_sock);
-      base_ip_sock= MYSQL_INVALID_SOCKET;
-    }
-    if (mysql_socket_getfd(extra_ip_sock) != INVALID_SOCKET)
-    {
-      (void) mysql_socket_close(extra_ip_sock);
-      extra_ip_sock= MYSQL_INVALID_SOCKET;
-    }
+    (void) mysql_socket_close(*sock);
+    if (sock->is_unix_domain_socket)
+      (void) unlink(mysqld_unix_port);
   }
+  listen_sockets.clear();
 
-#ifdef HAVE_SYS_UN_H
-  if (mysql_socket_getfd(unix_sock) != INVALID_SOCKET)
-  {
-    (void) mysql_socket_close(unix_sock);
-    (void) unlink(mysqld_unix_port);
-    unix_sock= MYSQL_INVALID_SOCKET;
-  }
-#endif
   end_thr_alarm(0);			 // Abort old alarms.
 
   /*
@@ -1800,13 +1787,20 @@ static void close_server_sock()
 #ifdef HAVE_CLOSE_SERVER_SOCK
   DBUG_ENTER("close_server_sock");
 
-  close_socket(base_ip_sock, "TCP/IP");
-  close_socket(extra_ip_sock, "TCP/IP");
-  close_socket(unix_sock, "unix/IP");
-
-  if (mysql_socket_getfd(unix_sock) != INVALID_SOCKET)
-    (void) unlink(mysqld_unix_port);
-  base_ip_sock= extra_ip_sock= unix_sock= MYSQL_INVALID_SOCKET;
+  for (std::vector<MYSQL_SOCKET>::iterator sock= listen_sockets.begin();
+       sock != listen_sockets.end(); ++sock)
+  {
+    if (sock->is_unix_domain_socket)
+    {
+      close_socket(*sock, "unix/IP");
+      (void) unlink(mysqld_unix_port);
+    }
+    else
+    {
+      close_socket(*sock, "TCP/IP");
+    }
+  }
+  listen_sockets.clear();
 
   DBUG_VOID_RETURN;
 #endif
@@ -2241,7 +2235,9 @@ static void set_root(const char *path)
    Activate usage of a tcp port
 */
 
-static MYSQL_SOCKET activate_tcp_port(uint port)
+static void activate_tcp_port(uint port,
+                              std::vector<MYSQL_SOCKET> *listen_sockets,
+                              bool is_extra_port= false)
 {
   struct addrinfo *ai, *a;
   struct addrinfo hints;
@@ -2273,20 +2269,6 @@ static MYSQL_SOCKET activate_tcp_port(uint port)
     unireg_abort(1);				/* purecov: tested */
   }
 
-  /*
-    special case: for wildcard addresses prefer ipv6 over ipv4,
-    because we later switch off IPV6_V6ONLY, so ipv6 wildcard
-    addresses will work for ipv4 too
-  */
-  if (!real_bind_addr_str && ai->ai_family == AF_INET && ai->ai_next
-      && ai->ai_next->ai_family == AF_INET6)
-  {
-    a= ai;
-    ai= ai->ai_next;
-    a->ai_next= ai->ai_next;
-    ai->ai_next= a;
-  }
-
   for (a= ai; a != NULL; a= a->ai_next)
   {
     ip_sock= mysql_socket_socket(key_socket_tcpip, a->ai_family,
@@ -2309,99 +2291,98 @@ static MYSQL_SOCKET activate_tcp_port(uint port)
     }
     else 
     {
-      server_socket_ai_family= a->ai_family;
+      ip_sock.address_family= a->ai_family;
       sql_print_information("Server socket created on IP: '%s'.",
                           (const char *) ip_addr);
-      break;
-    }
-  }
 
-  if (mysql_socket_getfd(ip_sock) == INVALID_SOCKET)
-  {
-    DBUG_PRINT("error",("Got error: %d from socket()",socket_errno));
-    sql_perror(ER_DEFAULT(ER_IPSOCK_ERROR));  /* purecov: tested */
-    unireg_abort(1);				/* purecov: tested */
-  }
+      if (mysql_socket_getfd(ip_sock) == INVALID_SOCKET)
+      {
+        DBUG_PRINT("error",("Got error: %d from socket()",socket_errno));
+        sql_perror(ER_DEFAULT(ER_IPSOCK_ERROR));  /* purecov: tested */
+        unireg_abort(1);                          /* purecov: tested */
+      }
 
-  mysql_socket_set_thread_owner(ip_sock);
+      mysql_socket_set_thread_owner(ip_sock);
 
 #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) mysql_socket_setsockopt(ip_sock,SOL_SOCKET,SO_REUSEADDR,(char*)&arg,
-                                 sizeof(arg));
+      /*
+        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) mysql_socket_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) mysql_socket_setsockopt(ip_sock, IPPROTO_IPV6, IPV6_V6ONLY,
-                                   (char*)&arg, sizeof(arg));
-  }
+      /*
+        If an address name resolves to both IPv4 and IPv6 addresses, the server
+        will listen on them both. With IPV6_V6ONLY unset, listening on an IPv6
+        wildcard address may cause listening on an IPv4 wildcard address
+        to fail. That's why IPV6_V6ONLY needs to be forcefully turned on.
+      */
+      if (a->ai_family == AF_INET6)
+      {
+        arg= 1;
+        (void) mysql_socket_setsockopt(ip_sock, IPPROTO_IPV6, IPV6_V6ONLY,
+                                       (char*)&arg, sizeof(arg));
+      }
 #endif
 
 #ifdef IP_FREEBIND
-  arg= 1;
-  (void) mysql_socket_setsockopt(ip_sock, IPPROTO_IP, IP_FREEBIND, (char*) &arg,
-                                 sizeof(arg));
+      arg= 1;
+      (void) mysql_socket_setsockopt(ip_sock, IPPROTO_IP, IP_FREEBIND,
+                                     (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
-    on busy Linux systems. Retry to bind the address at these intervals:
-    Sleep intervals: 1, 2, 4,  6,  9, 13, 17, 22, ...
-    Retry at second: 1, 3, 7, 13, 22, 35, 52, 74, ...
-    Limit the sequence by mysqld_port_timeout (set --port-open-timeout=#).
-  */
-  int ret;
-  uint waited, retry, this_wait;
-  for (waited= 0, retry= 1; ; retry++, waited+= this_wait)
-  {
-    if (((ret= mysql_socket_bind(ip_sock, a->ai_addr, a->ai_addrlen)) >= 0 ) ||
-        (socket_errno != SOCKET_EADDRINUSE) ||
-        (waited >= mysqld_port_timeout))
-      break;
-    sql_print_information("Retrying bind on TCP/IP port %u", port);
-    this_wait= retry * retry / 3 + 1;
-    sleep(this_wait);
-  }
-  freeaddrinfo(ai);
-  if (ret < 0)
-  {
-    char buff[100];
-    sprintf(buff, "Can't start server: Bind on TCP/IP port. Got error: %d",
-            (int) socket_errno);
-    sql_perror(buff);
-    sql_print_error("Do you already have another mysqld server running on "
-                    "port: %u ?", port);
-    unireg_abort(1);
-  }
-  if (mysql_socket_listen(ip_sock,(int) back_log) < 0)
-  {
-    sql_perror("Can't start server: listen() on TCP/IP port");
-    sql_print_error("listen() on TCP/IP failed with error %d",
-                    socket_errno);
-    unireg_abort(1);
-  }
+      /*
+        Sometimes the port is not released fast enough when stopping and
+        restarting the server. This happens quite often with the test suite
+        on busy Linux systems. Retry to bind the address at these intervals:
+        Sleep intervals: 1, 2, 4,  6,  9, 13, 17, 22, ...
+        Retry at second: 1, 3, 7, 13, 22, 35, 52, 74, ...
+        Limit the sequence by mysqld_port_timeout (set --port-open-timeout=#).
+      */
+      int ret;
+      uint waited, retry, this_wait;
+      for (waited= 0, retry= 1; ; retry++, waited+= this_wait)
+      {
+        if (((ret= mysql_socket_bind(ip_sock, a->ai_addr, a->ai_addrlen)) >= 0 )
+            || (socket_errno != SOCKET_EADDRINUSE)
+            || (waited >= mysqld_port_timeout))
+          break;
+        sql_print_information("Retrying bind on TCP/IP port %u", port);
+        this_wait= retry * retry / 3 + 1;
+        sleep(this_wait);
+      }
+
+      if (ret < 0)
+      {
+        char buff[100];
+        sprintf(buff, "Can't start server: Bind on TCP/IP port. Got error: %d",
+                (int) socket_errno);
+        sql_perror(buff);
+        sql_print_error("Do you already have another mysqld server running on "
+                        "port: %u ?", port);
+        unireg_abort(1);
+      }
+      if (mysql_socket_listen(ip_sock,(int) back_log) < 0)
+      {
+        sql_perror("Can't start server: listen() on TCP/IP port");
+        sql_print_error("listen() on TCP/IP failed with error %d",
+                        socket_errno);
+        unireg_abort(1);
+      }
 
 #ifdef FD_CLOEXEC
-  (void) fcntl(mysql_socket_getfd(ip_sock), F_SETFD, FD_CLOEXEC);
+      (void) fcntl(mysql_socket_getfd(ip_sock), F_SETFD, FD_CLOEXEC);
 #endif
+      ip_sock.is_extra_port= is_extra_port;
+      listen_sockets->push_back(ip_sock);
+    }
+  }
 
-  DBUG_RETURN(ip_sock);
+  freeaddrinfo(ai);
+  DBUG_VOID_RETURN;
 }
 
 static void network_init(void)
@@ -2431,9 +2412,11 @@ static void network_init(void)
   if (!opt_disable_networking && !opt_bootstrap)
   {
     if (mysqld_port)
-      base_ip_sock= activate_tcp_port(mysqld_port);
+      activate_tcp_port(mysqld_port, &listen_sockets,
+                        /* is_extra_port= */ false);
     if (mysqld_extra_port)
-      extra_ip_sock= activate_tcp_port(mysqld_extra_port);
+      activate_tcp_port(mysqld_extra_port, &listen_sockets,
+                        /* is_extra_port= */ true);
   }
 
 #if defined(HAVE_SYS_UN_H)
@@ -2442,6 +2425,7 @@ static void network_init(void)
   */
   if (mysqld_unix_port[0] && !opt_bootstrap)
   {
+    MYSQL_SOCKET unix_sock= MYSQL_INVALID_SOCKET;
     size_t port_len;
     DBUG_PRINT("general",("UNIX Socket is %s",mysqld_unix_port));
 
@@ -2458,6 +2442,9 @@ static void network_init(void)
       unireg_abort(1);				/* purecov: inspected */
     }
 
+    unix_sock.is_unix_domain_socket= true;
+    listen_sockets.push_back(unix_sock);
+    unix_sock_is_online= true;
     mysql_socket_set_thread_owner(unix_sock);
 
     bzero((char*) &UNIXaddr, sizeof(UNIXaddr));
@@ -5645,8 +5632,7 @@ int mysqld_main(int argc, char **argv)
 
   if (IS_SYSVAR_AUTOSIZE(&server_version_ptr))
     sql_print_information(ER_DEFAULT(ER_STARTUP), my_progname, server_version,
-                          ((mysql_socket_getfd(unix_sock) == INVALID_SOCKET) ?
-                           (char*) "" : mysqld_unix_port),
+                          (unix_sock_is_online ? mysqld_unix_port : (char*) ""),
                           mysqld_port, MYSQL_COMPILATION_COMMENT);
   else
   {
@@ -5658,8 +5644,7 @@ int mysqld_main(int argc, char **argv)
 
     sql_print_information(ER_DEFAULT(ER_STARTUP), my_progname,
                           real_server_version,
-                          ((mysql_socket_getfd(unix_sock) == INVALID_SOCKET) ?
-                           (char*) "" : mysqld_unix_port),
+                          (unix_sock_is_online ? mysqld_unix_port : (char*) ""),
                           mysqld_port, MYSQL_COMPILATION_COMMENT);
   }
 
@@ -5866,8 +5851,7 @@ void handle_accepted_socket(MYSQL_SOCKET new_sock, MYSQL_SOCKET sock)
 {
 #ifdef HAVE_LIBWRAP
   {
-    if (mysql_socket_getfd(sock) == mysql_socket_getfd(base_ip_sock) ||
-      mysql_socket_getfd(sock) == mysql_socket_getfd(extra_ip_sock))
+    if (!sock.is_unix_domain_socket)
     {
       struct request_info req;
       signal(SIGCHLD, SIG_DFL);
@@ -5910,11 +5894,9 @@ void handle_accepted_socket(MYSQL_SOCKET new_sock, MYSQL_SOCKET sock)
   DBUG_PRINT("info", ("Creating CONNECT for new connection"));
 
   if (auto connect= new CONNECT(new_sock,
-                                mysql_socket_getfd(sock) ==
-                                mysql_socket_getfd(unix_sock) ?
+                                sock.is_unix_domain_socket ?
                                 VIO_TYPE_SOCKET : VIO_TYPE_TCPIP,
-                                mysql_socket_getfd(sock) ==
-                                mysql_socket_getfd(extra_ip_sock) ?
+                                sock.is_extra_port ?
                                 extra_thread_scheduler : thread_scheduler))
     create_new_thread(connect);
   else
@@ -5950,36 +5932,30 @@ void handle_connections_sockets()
   struct sockaddr_storage cAddr;
   int retval;
 #ifdef HAVE_POLL
-  int socket_count= 0;
-  struct pollfd fds[3]; // for ip_sock, unix_sock and extra_ip_sock
-  MYSQL_SOCKET  pfs_fds[3]; // for performance schema
-#define setup_fds(X)                    \
-    mysql_socket_set_thread_owner(X);             \
-    pfs_fds[socket_count]= (X);                   \
-    fds[socket_count].fd= mysql_socket_getfd(X);  \
-    fds[socket_count].events= POLLIN;   \
-    socket_count++
+  std::vector<struct pollfd> fds; // for ip_sock, unix_sock and extra_ip_sock
 #else
-#define setup_fds(X)    FD_SET(mysql_socket_getfd(X),&clientFDs)
   fd_set readFDs,clientFDs;
-  FD_ZERO(&clientFDs);
 #endif
 
   DBUG_ENTER("handle_connections_sockets");
 
-  if (mysql_socket_getfd(base_ip_sock) != INVALID_SOCKET)
+#ifdef HAVE_POLL
+  fds.resize(listen_sockets.size());
+  for (size_t i= 0; i < listen_sockets.size(); i++)
   {
-    setup_fds(base_ip_sock);
-    set_non_blocking_if_supported(base_ip_sock);
+    mysql_socket_set_thread_owner(listen_sockets[i]);
+    fds[i].fd= mysql_socket_getfd(listen_sockets[i]);
+    fds[i].events= POLLIN;
+    set_non_blocking_if_supported(listen_sockets[i]);
   }
-  if (mysql_socket_getfd(extra_ip_sock) != INVALID_SOCKET)
+#else
+  FD_ZERO(&clientFDs);
+  for (size_t i= 0; i < listen_sockets.size(); i++)
   {
-    setup_fds(extra_ip_sock);
-    set_non_blocking_if_supported(extra_ip_sock);
+    int fd= mysql_socket_getfd(listen_sockets[i]);
+    FD_SET(fd, &clientFDs);
+    set_non_blocking_if_supported(listen_sockets[i]);
   }
-#ifdef HAVE_SYS_UN_H
-  setup_fds(unix_sock);
-  set_non_blocking_if_supported(unix_sock);
 #endif
 
   sd_notify(0, "READY=1\n"
@@ -5989,10 +5965,10 @@ void handle_connections_sockets()
   while (!abort_loop)
   {
 #ifdef HAVE_POLL
-    retval= poll(fds, socket_count, -1);
+    retval= poll(fds.data(), fds.size(), -1);
 #else
     readFDs=clientFDs;
-    retval= select((int) 0,&readFDs,0,0,0);
+    retval= select(FD_SETSIZE, &readFDs, NULL, NULL, NULL);
 #endif
 
     if (retval < 0)
@@ -6016,22 +5992,23 @@ void handle_connections_sockets()
 
     /* Is this a new connection request ? */
 #ifdef HAVE_POLL
-    for (int i= 0; i < socket_count; ++i) 
+    for (size_t i= 0; i < fds.size(); ++i)
     {
       if (fds[i].revents & POLLIN)
       {
-        sock= pfs_fds[i];
+        sock= listen_sockets[i];
         break;
       }
     }
 #else  // HAVE_POLL
-    if (FD_ISSET(mysql_socket_getfd(base_ip_sock),&readFDs))
-      sock=  base_ip_sock;
-    else
-    if (FD_ISSET(mysql_socket_getfd(extra_ip_sock),&readFDs))
-      sock=  extra_ip_sock;
-    else
-      sock = unix_sock;
+    for (size_t i=0; i < listen_sockets.size(); i++)
+    {
+      if (FD_ISSET(mysql_socket_getfd(listen_sockets[i]), &readFDs))
+      {
+        sock= listen_sockets[i];
+        break;
+      }
+    }
 #endif // HAVE_POLL
 
     for (uint retry=0; retry < MAX_ACCEPT_RETRY; retry++)
@@ -7514,9 +7491,6 @@ static int mysql_init_variables(void)
   character_set_filesystem= &my_charset_bin;
 
   opt_specialflag= SPECIAL_ENGLISH;
-#ifndef EMBEDDED_LIBRARY 
-  unix_sock= base_ip_sock= extra_ip_sock= MYSQL_INVALID_SOCKET;
-#endif
   mysql_home_ptr= mysql_home;
   log_error_file_ptr= log_error_file;
   protocol_version= PROTOCOL_VERSION;

sql/mysqld.h

@@ -147,7 +147,6 @@ extern ulong opt_replicate_events_marked_for_skip;
 extern char *default_tz_name;
 extern Time_zone *default_tz;
 extern char *my_bind_addr_str;
-extern int server_socket_ai_family;
 extern char *default_storage_engine, *default_tmp_storage_engine;
 extern char *enforced_storage_engine;
 extern char *gtid_pos_auto_engines;