Adding upstream version 1:10.5.12.upstream/1%10.5.12upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1437 insertions, 0 deletions

diff --git a/sql/net_serv.cc b/sql/net_serv.cc
new file mode 100644
index 00000000..1d2409f1
--- /dev/null
+++ b/sql/net_serv.cc
@@ -0,0 +1,1437 @@
+/* Copyright (c) 2000, 2016, Oracle and/or its affiliates.
+   Copyright (c) 2012, 2020, MariaDB Corporation.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA */
+
+/**
+  @file
+
+  This file is the net layer API for the MySQL client/server protocol.
+
+  Write and read of logical packets to/from socket.
+
+  Writes are cached into net_buffer_length big packets.
+  Read packets are reallocated dynamicly when reading big packets.
+  Each logical packet has the following pre-info:
+  3 byte length & 1 byte package-number.
+
+  This file needs to be written in C as it's used by the libmysql client as a
+  C file.
+*/
+
+/*
+  HFTODO this must be hidden if we don't want client capabilities in 
+  embedded library
+ */
+
+#include "mariadb.h"
+#include <mysql.h>
+#include <mysql_com.h>
+#include <mysqld_error.h>
+#include <my_sys.h>
+#include <m_string.h>
+#include <my_net.h>
+#include <violite.h>
+#include <signal.h>
+#include "probes_mysql.h"
+#include <debug_sync.h>
+#include "proxy_protocol.h"
+
+PSI_memory_key key_memory_NET_buff;
+PSI_memory_key key_memory_NET_compress_packet;
+
+#ifdef EMBEDDED_LIBRARY
+#undef MYSQL_SERVER
+#undef MYSQL_CLIENT
+#define MYSQL_CLIENT
+#endif /*EMBEDDED_LIBRARY */
+
+/*
+  to reduce the number of ifdef's in the code
+*/
+#ifdef EXTRA_DEBUG
+#define EXTRA_DEBUG_fprintf fprintf
+#define EXTRA_DEBUG_fflush fflush
+#define EXTRA_DEBUG_ASSERT DBUG_ASSERT
+#else
+static void inline EXTRA_DEBUG_fprintf(...) {}
+#ifndef MYSQL_SERVER
+static int inline EXTRA_DEBUG_fflush(...) { return 0; }
+#endif
+#endif /* EXTRA_DEBUG */
+
+#ifdef MYSQL_SERVER
+#include <sql_class.h>
+#include <sql_connect.h>
+#define MYSQL_SERVER_my_error my_error
+#else
+static void inline MYSQL_SERVER_my_error(...) {}
+#endif
+
+#ifndef EXTRA_DEBUG_ASSERT
+# define EXTRA_DEBUG_ASSERT(X) do {} while(0)
+#endif
+
+/*
+  The following handles the differences when this is linked between the
+  client and the server.
+
+  This gives an error if a too big packet is found.
+  The server can change this, but because the client can't normally do this
+  the client should have a bigger max_allowed_packet.
+*/
+
+#if defined(__WIN__) || !defined(MYSQL_SERVER)
+  /* The following is because alarms doesn't work on windows. */
+#ifndef NO_ALARM
+#define NO_ALARM
+#endif
+#endif
+
+#ifndef NO_ALARM
+#include "my_pthread.h"
+void sql_print_error(const char *format,...);
+#else
+#define DONT_USE_THR_ALARM
+#endif /* NO_ALARM */
+
+#include "thr_alarm.h"
+
+#ifdef MYSQL_SERVER
+/*
+  The following variables/functions should really not be declared
+  extern, but as it's hard to include sql_priv.h here, we have to
+  live with this for a while.
+*/
+extern ulonglong test_flags;
+extern ulong bytes_sent, bytes_received, net_big_packet_count;
+#ifdef HAVE_QUERY_CACHE
+#define USE_QUERY_CACHE
+extern void query_cache_insert(void *thd, const char *packet, size_t length,
+                               unsigned pkt_nr);
+#endif // HAVE_QUERY_CACHE
+#define update_statistics(A) A
+extern my_bool thd_net_is_killed(THD *thd);
+/* Additional instrumentation hooks for the server */
+#include "mysql_com_server.h"
+#else
+#define update_statistics(A)
+#define thd_net_is_killed(A) 0
+#endif
+
+
+static my_bool net_write_buff(NET *, const uchar *, size_t len);
+
+my_bool net_allocate_new_packet(NET *net, void *thd, uint my_flags);
+
+/** Init with packet info. */
+
+my_bool my_net_init(NET *net, Vio *vio, void *thd, uint my_flags)
+{
+  DBUG_ENTER("my_net_init");
+  DBUG_PRINT("enter", ("my_flags: %u", my_flags));
+  net->vio = vio;
+  net->read_timeout= 0;
+  net->write_timeout= 0;
+  my_net_local_init(net);			/* Set some limits */
+
+  if (net_allocate_new_packet(net, thd, my_flags))
+    DBUG_RETURN(1);
+
+  net->error=0; net->return_status=0;
+  net->pkt_nr=net->compress_pkt_nr=0;
+  net->last_error[0]=0;
+  net->compress=0; net->reading_or_writing=0;
+  net->where_b = net->remain_in_buf=0;
+  net->net_skip_rest_factor= 0;
+  net->last_errno=0;
+  net->thread_specific_malloc= MY_TEST(my_flags & MY_THREAD_SPECIFIC);
+  net->thd= 0;
+#ifdef MYSQL_SERVER
+  net->extension= NULL;
+  net->thd= thd;
+#endif
+
+  if (vio)
+  {
+    /* For perl DBI/DBD. */
+    net->fd= vio_fd(vio);
+#if defined(MYSQL_SERVER) && !defined(__WIN__)
+    if (!(test_flags & TEST_BLOCKING))
+    {
+      my_bool old_mode;
+      vio_blocking(vio, FALSE, &old_mode);
+    }
+#endif
+    vio_fastsend(vio);
+  }
+  DBUG_RETURN(0);
+}
+
+
+/**
+  Allocate and assign new net buffer
+
+  @note In case of error the old buffer left
+
+  @retval TRUE error
+  @retval FALSE success
+*/
+
+my_bool net_allocate_new_packet(NET *net, void *thd, uint my_flags)
+{
+  uchar *tmp;
+  DBUG_ENTER("net_allocate_new_packet");
+  if (!(tmp= (uchar*) my_malloc(key_memory_NET_buff,
+                                (size_t) net->max_packet +
+				NET_HEADER_SIZE + COMP_HEADER_SIZE + 1,
+				MYF(MY_WME | my_flags))))
+    DBUG_RETURN(1);
+  net->buff= tmp;
+  net->buff_end=net->buff+net->max_packet;
+  net->write_pos=net->read_pos = net->buff;
+  DBUG_RETURN(0);
+}
+
+
+void net_end(NET *net)
+{
+  DBUG_ENTER("net_end");
+  my_free(net->buff);
+  net->buff=0;
+  DBUG_VOID_RETURN;
+}
+
+
+/** Realloc the packet buffer. */
+
+my_bool net_realloc(NET *net, size_t length)
+{
+  uchar *buff;
+  size_t pkt_length;
+  DBUG_ENTER("net_realloc");
+  DBUG_PRINT("enter",("length: %lu", (ulong) length));
+
+  if (length >= net->max_packet_size)
+  {
+    DBUG_PRINT("error", ("Packet too large. Max size: %lu",
+                         net->max_packet_size));
+    /* @todo: 1 and 2 codes are identical. */
+    net->error= 1;
+    net->last_errno= ER_NET_PACKET_TOO_LARGE;
+    MYSQL_SERVER_my_error(ER_NET_PACKET_TOO_LARGE, MYF(0));
+    DBUG_RETURN(1);
+  }
+  pkt_length = (length+IO_SIZE-1) & ~(IO_SIZE-1); 
+  /*
+    We must allocate some extra bytes for the end 0 and to be able to
+    read big compressed blocks + 1 safety byte since uint3korr() in
+    my_real_read() may actually read 4 bytes depending on build flags and
+    platform.
+  */
+  if (!(buff= (uchar*) my_realloc(key_memory_NET_buff,
+                                  (char*) net->buff, pkt_length +
+                                  NET_HEADER_SIZE + COMP_HEADER_SIZE + 1,
+                                  MYF(MY_WME | (net->thread_specific_malloc
+                                                ?  MY_THREAD_SPECIFIC : 0)))))
+  {
+    /* @todo: 1 and 2 codes are identical. */
+    net->error= 1;
+    net->last_errno= ER_OUT_OF_RESOURCES;
+    /* In the server the error is reported by MY_WME flag. */
+    DBUG_RETURN(1);
+  }
+  net->buff=net->write_pos=buff;
+  net->buff_end=buff+(net->max_packet= (ulong) pkt_length);
+  DBUG_RETURN(0);
+}
+
+
+/**
+  Check if there is any data to be read from the socket.
+
+  @param sd   socket descriptor
+
+  @retval
+    0  No data to read
+  @retval
+    1  Data or EOF to read
+  @retval
+    -1   Don't know if data is ready or not
+*/
+
+#if !defined(EMBEDDED_LIBRARY) && defined(DBUG_OFF)
+
+static int net_data_is_ready(my_socket sd)
+{
+#ifdef HAVE_POLL
+  struct pollfd ufds;
+  int res;
+
+  ufds.fd= sd;
+  ufds.events= POLLIN | POLLPRI;
+  if (!(res= poll(&ufds, 1, 0)))
+    return 0;
+  if (res < 0 || !(ufds.revents & (POLLIN | POLLPRI)))
+    return 0;
+  return 1;
+#else
+  fd_set sfds;
+  struct timeval tv;
+  int res;
+
+#ifndef __WIN__
+  /* Windows uses an _array_ of 64 fd's as default, so it's safe */
+  if (sd >= FD_SETSIZE)
+    return -1;
+#define NET_DATA_IS_READY_CAN_RETURN_MINUS_ONE
+#endif
+
+  FD_ZERO(&sfds);
+  FD_SET(sd, &sfds);
+
+  tv.tv_sec= tv.tv_usec= 0;
+
+  if ((res= select((int) (sd + 1), &sfds, NULL, NULL, &tv)) < 0)
+    return 0;
+  else
+    return MY_TEST(res ? FD_ISSET(sd, &sfds) : 0);
+#endif /* HAVE_POLL */
+}
+
+#endif /* EMBEDDED_LIBRARY */
+
+/**
+  Clear (reinitialize) the NET structure for a new command.
+
+  @remark Performs debug checking of the socket buffer to
+          ensure that the protocol sequence is correct.
+
+   - Read from socket until there is nothing more to read. Discard
+     what is read.
+   - Initialize net for new net_read/net_write calls.
+
+   If there is anything when to read 'net_clear' is called this
+   normally indicates an error in the protocol. Normally one should not
+   need to do clear the communication buffer. If one compiles without
+   -DUSE_NET_CLEAR then one wins one read call / query.
+
+   When connection is properly closed (for TCP it means with
+   a FIN packet), then select() considers a socket "ready to read",
+   in the sense that there's EOF to read, but read() returns 0.
+
+  @param net			NET handler
+  @param clear_buffer           if <> 0, then clear all data from comm buff
+*/
+
+void net_clear(NET *net, my_bool clear_buffer __attribute__((unused)))
+{
+  DBUG_ENTER("net_clear");
+
+/*
+  We don't do a clear in case of not DBUG_OFF to catch bugs in the
+  protocol handling.
+*/
+
+#if (!defined(EMBEDDED_LIBRARY) && defined(DBUG_OFF)) || defined(USE_NET_CLEAR)
+  if (clear_buffer)
+  {
+    size_t count;
+    int ready;
+    while ((ready= net_data_is_ready(vio_fd(net->vio))) > 0)
+    {
+      /* The socket is ready */
+      if ((long) (count= vio_read(net->vio, net->buff,
+                                  (size_t) net->max_packet)) > 0)
+      {
+        DBUG_PRINT("info",("skipped %ld bytes from file: %s",
+                           (long) count, vio_description(net->vio)));
+        EXTRA_DEBUG_fprintf(stderr,"Note: net_clear() skipped %ld bytes from file: %s\n",
+                (long) count, vio_description(net->vio));
+      }
+      else
+      {
+        DBUG_PRINT("info",("socket ready but only EOF to read - disconnected"));
+        net->error= 2;
+        break;
+      }
+    }
+#ifdef NET_DATA_IS_READY_CAN_RETURN_MINUS_ONE
+    /* 'net_data_is_ready' returned "don't know" */
+    if (ready == -1)
+    {
+      /* Read unblocking to clear net */
+      my_bool old_mode;
+      if (!vio_blocking(net->vio, FALSE, &old_mode))
+      {
+        while ((long) (count= vio_read(net->vio, net->buff,
+                                       (size_t) net->max_packet)) > 0)
+          DBUG_PRINT("info",("skipped %ld bytes from file: %s",
+                             (long) count, vio_description(net->vio)));
+        vio_blocking(net->vio, TRUE, &old_mode);
+      }
+    }
+#endif /* NET_DATA_IS_READY_CAN_RETURN_MINUS_ONE */
+  }
+#endif /* EMBEDDED_LIBRARY */
+  net->pkt_nr=net->compress_pkt_nr=0;		/* Ready for new command */
+  net->write_pos=net->buff;
+  DBUG_VOID_RETURN;
+}
+
+
+/** Flush write_buffer if not empty. */
+
+my_bool net_flush(NET *net)
+{
+  my_bool error= 0;
+  DBUG_ENTER("net_flush");
+  if (net->buff != net->write_pos)
+  {
+    error= MY_TEST(net_real_write(net, net->buff,
+                                  (size_t) (net->write_pos - net->buff)));
+    net->write_pos= net->buff;
+  }
+  /* Sync packet number if using compression */
+  if (net->compress)
+    net->pkt_nr=net->compress_pkt_nr;
+  DBUG_RETURN(error);
+}
+
+
+/*****************************************************************************
+** Write something to server/client buffer
+*****************************************************************************/
+
+/**
+  Write a logical packet with packet header.
+
+  Format: Packet length (3 bytes), packet number (1 byte)
+  When compression is used, a 3 byte compression length is added.
+
+  @note If compression is used, the original packet is modified!
+*/
+
+my_bool my_net_write(NET *net, const uchar *packet, size_t len)
+{
+  uchar buff[NET_HEADER_SIZE];
+
+  if (unlikely(!net->vio)) /* nowhere to write */
+    return 0;
+
+  MYSQL_NET_WRITE_START(len);
+
+  /*
+    Big packets are handled by splitting them in packets of MAX_PACKET_LENGTH
+    length. The last packet is always a packet that is < MAX_PACKET_LENGTH.
+    (The last packet may even have a length of 0)
+  */
+  while (len >= MAX_PACKET_LENGTH)
+  {
+    const ulong z_size = MAX_PACKET_LENGTH;
+    int3store(buff, z_size);
+    buff[3]= (uchar) net->pkt_nr++;
+    if (net_write_buff(net, buff, NET_HEADER_SIZE) ||
+	net_write_buff(net, packet, z_size))
+    {
+      MYSQL_NET_WRITE_DONE(1);
+      return 1;
+    }
+    packet += z_size;
+    len-=     z_size;
+  }
+  /* Write last packet */
+  int3store(buff,len);
+  buff[3]= (uchar) net->pkt_nr++;
+  if (net_write_buff(net, buff, NET_HEADER_SIZE))
+  {
+    MYSQL_NET_WRITE_DONE(1);
+    return 1;
+  }
+#ifndef DEBUG_DATA_PACKETS
+  DBUG_DUMP("packet_header", buff, NET_HEADER_SIZE);
+#endif
+  my_bool rc= MY_TEST(net_write_buff(net, packet, len));
+  MYSQL_NET_WRITE_DONE(rc);
+  return rc;
+}
+
+
+/**
+  Send a command to the server.
+
+    The reason for having both header and packet is so that libmysql
+    can easy add a header to a special command (like prepared statements)
+    without having to re-alloc the string.
+
+    As the command is part of the first data packet, we have to do some data
+    juggling to put the command in there, without having to create a new
+    packet.
+  
+    This function will split big packets into sub-packets if needed.
+    (Each sub packet can only be 2^24 bytes)
+
+  @param net		NET handler
+  @param command	Command in MySQL server (enum enum_server_command)
+  @param header	Header to write after command
+  @param head_len	Length of header
+  @param packet	Query or parameter to query
+  @param len		Length of packet
+
+  @retval
+    0	ok
+  @retval
+    1	error
+*/
+
+my_bool
+net_write_command(NET *net,uchar command,
+		  const uchar *header, size_t head_len,
+		  const uchar *packet, size_t len)
+{
+  size_t length=len+1+head_len;			/* 1 extra byte for command */
+  uchar buff[NET_HEADER_SIZE+1];
+  uint header_size=NET_HEADER_SIZE+1;
+  my_bool rc;
+  DBUG_ENTER("net_write_command");
+  DBUG_PRINT("enter",("length: %lu", (ulong) len));
+
+  DBUG_EXECUTE_IF("simulate_error_on_packet_write",
+                  {
+                    if (command == COM_BINLOG_DUMP)
+                    {
+                      net->last_errno = ER_NET_ERROR_ON_WRITE;
+                      DBUG_ASSERT(!debug_sync_set_action(
+                      (THD *)net->thd,
+                      STRING_WITH_LEN("now SIGNAL parked WAIT_FOR continue")));
+                      DBUG_RETURN(true);
+                    }
+                  };);
+  MYSQL_NET_WRITE_START(length);
+
+  buff[4]=command;				/* For first packet */
+
+  if (length >= MAX_PACKET_LENGTH)
+  {
+    /* Take into account that we have the command in the first header */
+    len= MAX_PACKET_LENGTH - 1 - head_len;
+    do
+    {
+      int3store(buff, MAX_PACKET_LENGTH);
+      buff[3]= (uchar) net->pkt_nr++;
+      if (net_write_buff(net, buff, header_size) ||
+	  net_write_buff(net, header, head_len) ||
+	  net_write_buff(net, packet, len))
+      {
+        MYSQL_NET_WRITE_DONE(1);
+	DBUG_RETURN(1);
+      }
+      packet+= len;
+      length-= MAX_PACKET_LENGTH;
+      len= MAX_PACKET_LENGTH;
+      head_len= 0;
+      header_size= NET_HEADER_SIZE;
+    } while (length >= MAX_PACKET_LENGTH);
+    len=length;					/* Data left to be written */
+  }
+  int3store(buff,length);
+  buff[3]= (uchar) net->pkt_nr++;
+  rc= MY_TEST(net_write_buff(net, buff, header_size) ||
+              (head_len && net_write_buff(net, header, head_len)) ||
+              net_write_buff(net, packet, len) || net_flush(net));
+  MYSQL_NET_WRITE_DONE(rc);
+  DBUG_RETURN(rc);
+}
+
+/**
+  Caching the data in a local buffer before sending it.
+
+   Fill up net->buffer and send it to the client when full.
+
+    If the rest of the to-be-sent-packet is bigger than buffer,
+    send it in one big block (to avoid copying to internal buffer).
+    If not, copy the rest of the data to the buffer and return without
+    sending data.
+
+  @param net		Network handler
+  @param packet	Packet to send
+  @param len		Length of packet
+
+  @note
+    The cached buffer can be sent as it is with 'net_flush()'.
+    In this code we have to be careful to not send a packet longer than
+    MAX_PACKET_LENGTH to net_real_write() if we are using the compressed
+    protocol as we store the length of the compressed packet in 3 bytes.
+
+  @retval
+    0	ok
+  @retval
+    1
+*/
+
+static my_bool
+net_write_buff(NET *net, const uchar *packet, size_t len)
+{
+  size_t left_length;
+  if (net->compress && net->max_packet > MAX_PACKET_LENGTH)
+    left_length= (MAX_PACKET_LENGTH - (net->write_pos - net->buff));
+  else
+    left_length= (net->buff_end - net->write_pos);
+
+#ifdef DEBUG_DATA_PACKETS
+  DBUG_DUMP("data_written", packet, len);
+#endif
+  if (len > left_length)
+  {
+    if (net->write_pos != net->buff)
+    {
+      /* Fill up already used packet and write it */
+      memcpy((char*) net->write_pos,packet,left_length);
+      if (net_real_write(net, net->buff, 
+			 (size_t) (net->write_pos - net->buff) + left_length))
+	return 1;
+      net->write_pos= net->buff;
+      packet+= left_length;
+      len-= left_length;
+    }
+    if (net->compress)
+    {
+      /*
+	We can't have bigger packets than 16M with compression
+	Because the uncompressed length is stored in 3 bytes
+      */
+      left_length= MAX_PACKET_LENGTH;
+      while (len > left_length)
+      {
+	if (net_real_write(net, packet, left_length))
+	  return 1;
+	packet+= left_length;
+	len-= left_length;
+      }
+    }
+    if (len > net->max_packet)
+      return net_real_write(net, packet, len) ? 1 : 0;
+    /* Send out rest of the blocks as full sized blocks */
+  }
+  if (len)
+    memcpy((char*) net->write_pos,packet,len);
+  net->write_pos+= len;
+  return 0;
+}
+
+
+/**
+  Read and write one packet using timeouts.
+  If needed, the packet is compressed before sending.
+
+  @todo
+    - TODO is it needed to set this variable if we have no socket
+*/
+
+int
+net_real_write(NET *net,const uchar *packet, size_t len)
+{
+  size_t length;
+  const uchar *pos,*end;
+  thr_alarm_t alarmed;
+#ifndef NO_ALARM
+  ALARM alarm_buff;
+#endif
+  uint retry_count=0;
+  my_bool net_blocking = vio_is_blocking(net->vio);
+  DBUG_ENTER("net_real_write");
+
+#if defined(MYSQL_SERVER) && defined(USE_QUERY_CACHE)
+  query_cache_insert(net->thd, (char*) packet, len, net->pkt_nr);
+#endif
+
+  if (unlikely(net->error == 2))
+    DBUG_RETURN(-1);				/* socket can't be used */
+
+  net->reading_or_writing=2;
+#ifdef HAVE_COMPRESS
+  if (net->compress)
+  {
+    size_t complen;
+    uchar *b;
+    uint header_length=NET_HEADER_SIZE+COMP_HEADER_SIZE;
+    if (!(b= (uchar*) my_malloc(key_memory_NET_compress_packet,
+                                len + NET_HEADER_SIZE + COMP_HEADER_SIZE + 1,
+                                MYF(MY_WME | (net->thread_specific_malloc
+                                              ? MY_THREAD_SPECIFIC : 0)))))
+    {
+      net->error= 2;
+      net->last_errno= ER_OUT_OF_RESOURCES;
+      /* In the server, the error is reported by MY_WME flag. */
+      net->reading_or_writing= 0;
+      DBUG_RETURN(1);
+    }
+    memcpy(b+header_length,packet,len);
+
+    /* Don't compress error packets (compress == 2) */
+    if (net->compress == 2 || my_compress(b+header_length, &len, &complen))
+      complen=0;
+    int3store(&b[NET_HEADER_SIZE],complen);
+    int3store(b,len);
+    b[3]=(uchar) (net->compress_pkt_nr++);
+    len+= header_length;
+    packet= b;
+  }
+#endif /* HAVE_COMPRESS */
+
+#ifdef DEBUG_DATA_PACKETS
+  DBUG_DUMP("data_written", packet, len);
+#endif
+
+#ifndef NO_ALARM
+  thr_alarm_init(&alarmed);
+  if (net_blocking)
+    thr_alarm(&alarmed, net->write_timeout, &alarm_buff);
+#else
+  alarmed=0;
+  /* Write timeout is set in my_net_set_write_timeout */
+#endif /* NO_ALARM */
+
+  pos= packet;
+  end=pos+len;
+  while (pos != end)
+  {
+    if ((long) (length= vio_write(net->vio,pos,(size_t) (end-pos))) <= 0)
+    {
+      my_bool interrupted = vio_should_retry(net->vio);
+#if !defined(__WIN__)
+      if ((interrupted || length == 0) && !thr_alarm_in_use(&alarmed))
+      {
+        if (!thr_alarm(&alarmed, net->write_timeout, &alarm_buff))
+        {                                       /* Always true for client */
+	  my_bool old_mode;
+	  while (vio_blocking(net->vio, TRUE, &old_mode) < 0)
+	  {
+	    if (vio_should_retry(net->vio) && retry_count++ < net->retry_count)
+	      continue;
+	    EXTRA_DEBUG_fprintf(stderr,
+		    "%s: my_net_write: fcntl returned error %d, aborting thread\n",
+		    my_progname,vio_errno(net->vio));
+	    net->error= 2;                     /* Close socket */
+            net->last_errno= ER_NET_PACKET_TOO_LARGE;
+            MYSQL_SERVER_my_error(ER_NET_PACKET_TOO_LARGE, MYF(0));
+	    goto end;
+	  }
+	  retry_count=0;
+	  continue;
+	}
+      }
+      else
+#endif /* !defined(__WIN__) */
+	if (thr_alarm_in_use(&alarmed) && !thr_got_alarm(&alarmed) &&
+	    interrupted)
+      {
+	if (retry_count++ < net->retry_count)
+	    continue;
+	  EXTRA_DEBUG_fprintf(stderr, "%s: write looped, aborting thread\n",
+		  my_progname);
+      }
+#ifndef MYSQL_SERVER
+      if (vio_errno(net->vio) == SOCKET_EINTR)
+      {
+	DBUG_PRINT("warning",("Interrupted write. Retrying..."));
+	continue;
+      }
+#endif /* !defined(MYSQL_SERVER) */
+      net->error= 2;				/* Close socket */
+      net->last_errno= (interrupted ? ER_NET_WRITE_INTERRUPTED :
+                               ER_NET_ERROR_ON_WRITE);
+      MYSQL_SERVER_my_error(net->last_errno, MYF(0));
+      break;
+    }
+    pos+=length;
+    update_statistics(thd_increment_bytes_sent(net->thd, length));
+  }
+#ifndef __WIN__
+ end:
+#endif
+#ifdef HAVE_COMPRESS
+  if (net->compress)
+    my_free((void*) packet);
+#endif
+  if (thr_alarm_in_use(&alarmed))
+  {
+    my_bool old_mode;
+    thr_end_alarm(&alarmed);
+    if (!net_blocking)
+      vio_blocking(net->vio, net_blocking, &old_mode);
+  }
+  net->reading_or_writing=0;
+  DBUG_RETURN(((int) (pos != end)));
+}
+
+
+/*****************************************************************************
+** Read something from server/clinet
+*****************************************************************************/
+
+#ifndef NO_ALARM
+
+static my_bool net_safe_read(NET *net, uchar *buff, size_t length,
+			     thr_alarm_t *alarmed)
+{
+  uint retry_count=0;
+  while (length > 0)
+  {
+    size_t tmp;
+    if ((long) (tmp= vio_read(net->vio, buff, length)) <= 0)
+    {
+      my_bool interrupted = vio_should_retry(net->vio);
+      if (!thr_got_alarm(alarmed) && interrupted)
+      {					/* Probably in MIT threads */
+	if (retry_count++ < net->retry_count)
+	  continue;
+      }
+      return 1;
+    }
+    length-= tmp;
+    buff+= tmp;
+  }
+  return 0;
+}
+
+/**
+  Help function to clear the commuication buffer when we get a too big packet.
+
+  @param net		Communication handle
+  @param remain	Bytes to read
+  @param alarmed	Parameter for thr_alarm()
+  @param alarm_buff	Parameter for thr_alarm()
+
+  @retval
+   0	Was able to read the whole packet
+  @retval
+   1	Got mailformed packet from client
+*/
+
+static my_bool my_net_skip_rest(NET *net, uint32 remain, thr_alarm_t *alarmed,
+				ALARM *alarm_buff)
+{
+  longlong limit= net->max_packet_size*net->net_skip_rest_factor;
+  uint32 old=remain;
+  DBUG_ENTER("my_net_skip_rest");
+  DBUG_PRINT("enter",("bytes_to_skip: %u", (uint) remain));
+
+  /* The following is good for debugging */
+  update_statistics(thd_increment_net_big_packet_count(net->thd, 1));
+
+  if (!thr_alarm_in_use(alarmed))
+  {
+    my_bool old_mode;
+    if (thr_alarm(alarmed,net->read_timeout, alarm_buff) ||
+	vio_blocking(net->vio, TRUE, &old_mode) < 0)
+      DBUG_RETURN(1);				/* Can't setup, abort */
+  }
+  for (;;)
+  {
+    while (remain > 0)
+    {
+      size_t length= MY_MIN(remain, net->max_packet);
+      if (net_safe_read(net, net->buff, length, alarmed))
+	DBUG_RETURN(1);
+      update_statistics(thd_increment_bytes_received(net->thd, length));
+      remain -= (uint32) length;
+      limit-= length;
+      if (limit < 0)
+        DBUG_RETURN(1);
+    }
+    if (old != MAX_PACKET_LENGTH)
+      break;
+    if (net_safe_read(net, net->buff, NET_HEADER_SIZE, alarmed))
+      DBUG_RETURN(1);
+    limit-= NET_HEADER_SIZE;
+    old=remain= uint3korr(net->buff);
+    net->pkt_nr++;
+  }
+  DBUG_RETURN(0);
+}
+#endif /* NO_ALARM */
+
+
+/**
+  Try to parse and process proxy protocol header.
+
+  This function is called in case MySQL packet header cannot be parsed.
+  It checks if proxy header was sent, and that it was send from allowed remote
+  host, as defined by proxy-protocol-networks parameter.
+
+  If proxy header is parsed, then THD and ACL structures and changed to indicate
+  the new peer address and port.
+
+  Note, that proxy header can only be sent either when the connection is established,
+  or as the client reply packet to
+*/
+#undef IGNORE                   /* for Windows */
+typedef enum { RETRY, ABORT, IGNORE} handle_proxy_header_result;
+static handle_proxy_header_result handle_proxy_header(NET *net)
+{
+#if !defined(MYSQL_SERVER) || defined(EMBEDDED_LIBRARY)
+  return IGNORE;
+#else
+  THD *thd= (THD *)net->thd;
+
+  if (!has_proxy_protocol_header(net) || !thd ||
+      thd->get_command() != COM_CONNECT)
+    return IGNORE;
+
+  /*
+    Proxy information found in the first 4 bytes received so far.
+    Read and parse proxy header , change peer ip address and port in THD.
+  */
+  proxy_peer_info peer_info;
+
+  if (!thd->net.vio)
+  {
+    DBUG_ASSERT(0);
+    return ABORT;
+  }
+
+  if (!is_proxy_protocol_allowed((sockaddr *)&(thd->net.vio->remote)))
+  {
+     /* proxy-protocol-networks variable needs to be set to allow this remote address */
+     my_printf_error(ER_HOST_NOT_PRIVILEGED, "Proxy header is not accepted from %s",
+       MYF(0), thd->main_security_ctx.ip);
+     return ABORT;
+  }
+
+  if (parse_proxy_protocol_header(net, &peer_info))
+  {
+     /* Failed to parse proxy header*/
+     my_printf_error(ER_UNKNOWN_ERROR, "Failed to parse proxy header", MYF(0));
+     return ABORT;
+  }
+
+  if (peer_info.is_local_command)
+    /* proxy header indicates LOCAL connection, no action necessary */
+    return RETRY;
+  /* Change peer address in THD and ACL structures.*/
+  uint host_errors;
+  return (handle_proxy_header_result)thd_set_peer_addr(thd,
+                         &(peer_info.peer_addr), NULL, peer_info.port,
+                         false, &host_errors);
+#endif
+}
+
+/**
+  Reads one packet to net->buff + net->where_b.
+  Long packets are handled by my_net_read().
+  This function reallocates the net->buff buffer if necessary.
+
+  @return
+    Returns length of packet.
+*/
+
+static ulong
+my_real_read(NET *net, size_t *complen,
+             my_bool header __attribute__((unused)))
+{
+  uchar *pos;
+  size_t length;
+  uint i,retry_count=0;
+  ulong len=packet_error;
+  my_bool expect_error_packet __attribute__((unused))= 0;
+  thr_alarm_t alarmed;
+#ifndef NO_ALARM
+  ALARM alarm_buff;
+#endif
+
+retry:
+
+  my_bool net_blocking=vio_is_blocking(net->vio);
+  uint32 remain= (net->compress ? NET_HEADER_SIZE+COMP_HEADER_SIZE :
+		  NET_HEADER_SIZE);
+#ifdef MYSQL_SERVER
+  size_t count= remain;
+  struct st_net_server *server_extension= 0;
+
+  if (header)
+  {
+    server_extension= static_cast<st_net_server*> (net->extension);
+    if (server_extension != NULL)
+    {
+      void *user_data= server_extension->m_user_data;
+      server_extension->m_before_header(net, user_data, count);
+    }
+  }
+#endif
+
+  *complen = 0;
+
+  net->reading_or_writing=1;
+  thr_alarm_init(&alarmed);
+#ifndef NO_ALARM
+  if (net_blocking)
+    thr_alarm(&alarmed,net->read_timeout,&alarm_buff);
+#else
+  /* Read timeout is set in my_net_set_read_timeout */
+#endif /* NO_ALARM */
+
+    pos = net->buff + net->where_b;		/* net->packet -4 */
+    for (i=0 ; i < 2 ; i++)
+    {
+      while (remain > 0)
+      {
+	/* First read is done with non blocking mode */
+        if ((long) (length= vio_read(net->vio, pos, remain)) <= 0L)
+        {
+          my_bool interrupted = vio_should_retry(net->vio);
+
+	  DBUG_PRINT("info",("vio_read returned %ld  errno: %d",
+			     (long) length, vio_errno(net->vio)));
+
+          if (i== 0 && unlikely(thd_net_is_killed((THD*) net->thd)))
+          {
+            DBUG_PRINT("info", ("thd is killed"));
+            len= packet_error;
+            net->error= 0;
+            net->last_errno= ER_CONNECTION_KILLED;
+            MYSQL_SERVER_my_error(net->last_errno, MYF(0));
+            goto end;
+          }
+
+#if !defined(__WIN__) && defined(MYSQL_SERVER)
+	  /*
+	    We got an error that there was no data on the socket. We now set up
+	    an alarm to not 'read forever', change the socket to the blocking
+	    mode and try again
+	  */
+	  if ((interrupted || length == 0) && !thr_alarm_in_use(&alarmed))
+	  {
+	    if (!thr_alarm(&alarmed,net->read_timeout,&alarm_buff)) /* Don't wait too long */
+	    {
+	      my_bool old_mode;
+	      while (vio_blocking(net->vio, TRUE, &old_mode) < 0)
+	      {
+		if (vio_should_retry(net->vio) &&
+		    retry_count++ < net->retry_count)
+		  continue;
+		DBUG_PRINT("error",
+			   ("fcntl returned error %d, aborting thread",
+			    vio_errno(net->vio)));
+		EXTRA_DEBUG_fprintf(stderr,
+			"%s: read: fcntl returned error %d, aborting thread\n",
+			my_progname,vio_errno(net->vio));
+		len= packet_error;
+		net->error= 2;                 /* Close socket */
+	        net->last_errno= ER_NET_FCNTL_ERROR;
+		MYSQL_SERVER_my_error(ER_NET_FCNTL_ERROR, MYF(0));
+		goto end;
+	      }
+	      retry_count=0;
+	      continue;
+	    }
+	  }
+#endif /* (!defined(__WIN__) && defined(MYSQL_SERVER) */
+	  if (thr_alarm_in_use(&alarmed) && !thr_got_alarm(&alarmed) &&
+	      interrupted)
+	  {					/* Probably in MIT threads */
+	    if (retry_count++ < net->retry_count)
+	      continue;
+	    EXTRA_DEBUG_fprintf(stderr, "%s: read looped with error %d, aborting thread\n",
+		    my_progname,vio_errno(net->vio));
+	  }
+#ifndef MYSQL_SERVER
+	  if (length != 0 && vio_errno(net->vio) == SOCKET_EINTR)
+	  {
+	    DBUG_PRINT("warning",("Interrupted read. Retrying..."));
+	    continue;
+	  }
+#endif
+	  DBUG_PRINT("error",("Couldn't read packet: remain: %u  errno: %d  length: %ld",
+			      remain, vio_errno(net->vio), (long) length));
+	  len= packet_error;
+	  net->error= 2;				/* Close socket */
+          net->last_errno= (vio_was_timeout(net->vio) ?
+                                   ER_NET_READ_INTERRUPTED :
+                                   ER_NET_READ_ERROR);
+          MYSQL_SERVER_my_error(net->last_errno, MYF(0));
+	  goto end;
+	}
+	remain -= (uint32) length;
+	pos+= length;
+	update_statistics(thd_increment_bytes_received(net->thd, length));
+      }
+
+#ifdef DEBUG_DATA_PACKETS
+      DBUG_DUMP("data_read", net->buff+net->where_b, length);
+#endif
+      if (i == 0)
+      {					/* First parts is packet length */
+        size_t helping;
+#ifndef DEBUG_DATA_PACKETS
+        DBUG_DUMP("packet_header", net->buff+net->where_b,
+                  NET_HEADER_SIZE);
+#endif
+	if (net->buff[net->where_b + 3] != (uchar) net->pkt_nr)
+        {
+#ifndef MYSQL_SERVER
+          if (net->buff[net->where_b + 3] == (uchar) (net->pkt_nr -1))
+          {
+            /*
+              If the server was killed then the server may have missed the
+              last sent client packet and the packet numbering may be one off.
+            */
+            DBUG_PRINT("warning", ("Found possible out of order packets"));
+            expect_error_packet= 1;
+          }
+          else
+#endif
+            goto packets_out_of_order;
+        }
+        net->compress_pkt_nr= ++net->pkt_nr;
+#ifdef HAVE_COMPRESS
+	if (net->compress)
+	{
+          /*
+            The following uint3korr() may read 4 bytes, so make sure we don't
+            read unallocated or uninitialized memory. The right-hand expression
+            must match the size of the buffer allocated in net_realloc().
+          */
+          DBUG_ASSERT(net->where_b + NET_HEADER_SIZE + sizeof(uint32) <=
+                      net->max_packet + NET_HEADER_SIZE + COMP_HEADER_SIZE + 1);
+	  /*
+	    If the packet is compressed then complen > 0 and contains the
+	    number of bytes in the uncompressed packet
+	  */
+	  *complen=uint3korr(&(net->buff[net->where_b + NET_HEADER_SIZE]));
+	}
+#endif
+
+	len=uint3korr(net->buff+net->where_b);
+	if (!len)				/* End of big multi-packet */
+	  goto end;
+	helping = MY_MAX(len,*complen) + net->where_b;
+	/* The necessary size of net->buff */
+	if (helping >= net->max_packet)
+	{
+	  if (net_realloc(net,helping))
+	  {
+#if defined(MYSQL_SERVER) && !defined(NO_ALARM)
+	    if (!net->compress &&
+		!my_net_skip_rest(net, (uint32) len, &alarmed, &alarm_buff))
+	      net->error= 3;		/* Successfully skiped packet */
+#endif
+	    len= packet_error;          /* Return error and close connection */
+	    goto end;
+	  }
+	}
+	pos=net->buff + net->where_b;
+	remain = (uint32) len;
+#ifdef MYSQL_SERVER
+        if (server_extension != NULL)
+        {
+          void *user_data= server_extension->m_user_data;
+          server_extension->m_after_header(net, user_data, count, 0);
+          server_extension=  NULL;
+        }
+#endif
+      }
+#ifndef MYSQL_SERVER
+      else if (expect_error_packet)
+      {
+        /*
+          This check is safe both for compressed and not compressed protocol
+          as for the compressed protocol errors are not compressed anymore.
+        */
+        if (net->buff[net->where_b] != (uchar) 255)
+        {
+          /* Restore pkt_nr to original value */
+          net->pkt_nr--;
+          goto packets_out_of_order;
+        }
+      }
+#endif
+    }
+
+end:
+  if (thr_alarm_in_use(&alarmed))
+  {
+    my_bool old_mode;
+    thr_end_alarm(&alarmed);
+    if (!net_blocking)
+      vio_blocking(net->vio, net_blocking, &old_mode);
+  }
+  net->reading_or_writing=0;
+#ifdef DEBUG_DATA_PACKETS
+  if (len != packet_error)
+    DBUG_DUMP("data_read", net->buff+net->where_b, len);
+#endif
+#ifdef MYSQL_SERVER
+  if (server_extension != NULL)
+  {
+    void *user_data= server_extension->m_user_data;
+    server_extension->m_after_header(net, user_data, count, 1);
+    DBUG_ASSERT(len == packet_error || len == 0);
+  }
+#endif
+  return(len);
+
+packets_out_of_order:
+  {
+    switch (handle_proxy_header(net)) {
+    case ABORT:
+        /* error happened, message is already written. */
+        len= packet_error;
+        goto end; 
+    case RETRY:
+        goto retry;
+    case IGNORE:
+        break;
+    }
+
+    DBUG_PRINT("error",
+               ("Packets out of order (Found: %d, expected %u)",
+                (int) net->buff[net->where_b + 3],
+                net->pkt_nr));
+    EXTRA_DEBUG_ASSERT(0);
+    /*
+       We don't make noise server side, since the client is expected
+       to break the protocol for e.g. --send LOAD DATA .. LOCAL where
+       the server expects the client to send a file, but the client
+       may reply with a new command instead.
+    */
+#ifndef MYSQL_SERVER
+    EXTRA_DEBUG_fflush(stdout);
+    EXTRA_DEBUG_fprintf(stderr,"Error: Packets out of order (Found: %d, expected %d)\n",
+                        (int) net->buff[net->where_b + 3],
+                        (uint) (uchar) net->pkt_nr);
+    EXTRA_DEBUG_fflush(stderr);
+#endif
+    len= packet_error;
+    MYSQL_SERVER_my_error(ER_NET_PACKETS_OUT_OF_ORDER, MYF(0));
+    goto end;
+  }
+}
+
+
+
+/* Old interface. See my_net_read_packet() for function description */
+
+#undef my_net_read
+
+ulong my_net_read(NET *net)
+{
+  return my_net_read_packet(net, 0);
+}
+
+
+/**
+  Read a packet from the client/server and return it without the internal
+  package header.
+
+  If the packet is the first packet of a multi-packet packet
+  (which is indicated by the length of the packet = 0xffffff) then
+  all sub packets are read and concatenated.
+
+  If the packet was compressed, its uncompressed and the length of the
+  uncompressed packet is returned.
+
+  read_from_server is set when the server is reading a new command
+  from the client.
+
+  @return
+  The function returns the length of the found packet or packet_error.
+  net->read_pos points to the read data.
+*/
+ulong
+my_net_read_packet(NET *net, my_bool read_from_server)
+{
+  ulong reallen = 0;
+  return my_net_read_packet_reallen(net, read_from_server, &reallen); 
+}
+
+
+ulong
+my_net_read_packet_reallen(NET *net, my_bool read_from_server, ulong* reallen)
+{
+  size_t len, complen;
+
+  MYSQL_NET_READ_START();
+
+  *reallen = 0;
+#ifdef HAVE_COMPRESS
+  if (!net->compress)
+  {
+#endif
+    len = my_real_read(net,&complen, read_from_server);
+    if (len == MAX_PACKET_LENGTH)
+    {
+      /* First packet of a multi-packet.  Concatenate the packets */
+      ulong save_pos = net->where_b;
+      size_t total_length= 0;
+      do
+      {
+	net->where_b += (ulong)len;
+	total_length += len;
+	len = my_real_read(net,&complen, 0);
+      } while (len == MAX_PACKET_LENGTH);
+      if (likely(len != packet_error))
+	len+= total_length;
+      net->where_b = save_pos;
+    }
+
+    net->read_pos = net->buff + net->where_b;
+    if (likely(len != packet_error))
+    {
+      net->read_pos[len]=0;		/* Safeguard for mysql_use_result */
+      *reallen = (ulong)len;
+    }
+    MYSQL_NET_READ_DONE(0, len);
+    return (ulong)len;
+#ifdef HAVE_COMPRESS
+  }
+  else
+  {
+    /* We are using the compressed protocol */
+
+    ulong buf_length;
+    ulong start_of_packet;
+    ulong first_packet_offset;
+    uint read_length, multi_byte_packet=0;
+
+    if (net->remain_in_buf)
+    {
+      buf_length= net->buf_length;		/* Data left in old packet */
+      first_packet_offset= start_of_packet= (net->buf_length -
+					     net->remain_in_buf);
+      /* Restore the character that was overwritten by the end 0 */
+      net->buff[start_of_packet]= net->save_char;
+    }
+    else
+    {
+      /* reuse buffer, as there is nothing in it that we need */
+      buf_length= start_of_packet= first_packet_offset= 0;
+    }
+    for (;;)
+    {
+      ulong packet_len;
+
+      if (buf_length - start_of_packet >= NET_HEADER_SIZE)
+      {
+	read_length = uint3korr(net->buff+start_of_packet);
+	if (!read_length)
+	{ 
+	  /* End of multi-byte packet */
+	  start_of_packet += NET_HEADER_SIZE;
+	  break;
+	}
+	if (read_length + NET_HEADER_SIZE <= buf_length - start_of_packet)
+	{
+	  if (multi_byte_packet)
+	  {
+	    /* Remove packet header for second packet */
+	    memmove(net->buff + first_packet_offset + start_of_packet,
+		    net->buff + first_packet_offset + start_of_packet +
+		    NET_HEADER_SIZE,
+		    buf_length - start_of_packet);
+	    start_of_packet += read_length;
+	    buf_length -= NET_HEADER_SIZE;
+	  }
+	  else
+	    start_of_packet+= read_length + NET_HEADER_SIZE;
+
+	  if (read_length != MAX_PACKET_LENGTH)	/* last package */
+	  {
+	    multi_byte_packet= 0;		/* No last zero len packet */
+	    break;
+	  }
+	  multi_byte_packet= NET_HEADER_SIZE;
+	  /* Move data down to read next data packet after current one */
+	  if (first_packet_offset)
+	  {
+	    memmove(net->buff,net->buff+first_packet_offset,
+		    buf_length-first_packet_offset);
+	    buf_length-=first_packet_offset;
+	    start_of_packet -= first_packet_offset;
+	    first_packet_offset=0;
+	  }
+	  continue;
+	}
+      }
+      /* Move data down to read next data packet after current one */
+      if (first_packet_offset)
+      {
+	memmove(net->buff,net->buff+first_packet_offset,
+		buf_length-first_packet_offset);
+	buf_length-=first_packet_offset;
+	start_of_packet -= first_packet_offset;
+	first_packet_offset=0;
+      }
+
+      net->where_b=buf_length;
+      if ((packet_len = my_real_read(net,&complen, read_from_server))
+          == packet_error)
+      {
+        MYSQL_NET_READ_DONE(1, 0);
+	return packet_error;
+      }
+      read_from_server= 0;
+      if (my_uncompress(net->buff + net->where_b, packet_len,
+			&complen))
+      {
+	net->error= 2;			/* caller will close socket */
+        net->last_errno= ER_NET_UNCOMPRESS_ERROR;
+	MYSQL_SERVER_my_error(ER_NET_UNCOMPRESS_ERROR, MYF(0));
+        MYSQL_NET_READ_DONE(1, 0);
+	return packet_error;
+      }
+      buf_length+= (ulong)complen;
+      *reallen += packet_len;
+    }
+
+    net->read_pos=      net->buff+ first_packet_offset + NET_HEADER_SIZE;
+    net->buf_length=    buf_length;
+    net->remain_in_buf= (ulong) (buf_length - start_of_packet);
+    len = ((ulong) (start_of_packet - first_packet_offset) - NET_HEADER_SIZE -
+           multi_byte_packet);
+    net->save_char= net->read_pos[len];	/* Must be saved */
+    net->read_pos[len]=0;		/* Safeguard for mysql_use_result */
+  }
+#endif /* HAVE_COMPRESS */
+  MYSQL_NET_READ_DONE(0, len);
+  return (ulong)len;
+}
+
+
+void my_net_set_read_timeout(NET *net, uint timeout)
+{
+  DBUG_ENTER("my_net_set_read_timeout");
+  DBUG_PRINT("enter", ("timeout: %d", timeout));
+  if (net->read_timeout != timeout)
+  {
+    net->read_timeout= timeout;
+    if (net->vio)
+      vio_timeout(net->vio, 0, timeout);
+  }
+  DBUG_VOID_RETURN;
+}
+
+
+void my_net_set_write_timeout(NET *net, uint timeout)
+{
+  DBUG_ENTER("my_net_set_write_timeout");
+  DBUG_PRINT("enter", ("timeout: %d", timeout));
+  if (net->write_timeout != timeout)
+  {
+    net->write_timeout= timeout;
+    if (net->vio)
+      vio_timeout(net->vio, 1, timeout);
+  }
+  DBUG_VOID_RETURN;
+}