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packets.go
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packets.go
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// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
//
// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
package mysql
import (
"bytes"
"crypto/tls"
"database/sql/driver"
"encoding/binary"
"encoding/json"
"fmt"
"io"
"math"
"strconv"
"time"
)
// MySQL client/server protocol documentations.
// https://dev.mysql.com/doc/dev/mysql-server/latest/PAGE_PROTOCOL.html
// https://mariadb.com/kb/en/clientserver-protocol/
// Read packet to buffer 'data'
func (mc *mysqlConn) readPacket() ([]byte, error) {
var prevData []byte
for {
// read packet header
data, err := mc.buf.readNext(4)
if err != nil {
if cerr := mc.canceled.Value(); cerr != nil {
return nil, cerr
}
mc.log(err)
mc.Close()
return nil, ErrInvalidConn
}
// packet length [24 bit]
pktLen := int(uint32(data[0]) | uint32(data[1])<<8 | uint32(data[2])<<16)
// check packet sync [8 bit]
if data[3] != mc.sequence {
mc.Close()
if data[3] > mc.sequence {
return nil, ErrPktSyncMul
}
return nil, ErrPktSync
}
mc.sequence++
// packets with length 0 terminate a previous packet which is a
// multiple of (2^24)-1 bytes long
if pktLen == 0 {
// there was no previous packet
if prevData == nil {
mc.log(ErrMalformPkt)
mc.Close()
return nil, ErrInvalidConn
}
return prevData, nil
}
// read packet body [pktLen bytes]
data, err = mc.buf.readNext(pktLen)
if err != nil {
if cerr := mc.canceled.Value(); cerr != nil {
return nil, cerr
}
mc.log(err)
mc.Close()
return nil, ErrInvalidConn
}
// return data if this was the last packet
if pktLen < maxPacketSize {
// zero allocations for non-split packets
if prevData == nil {
return data, nil
}
return append(prevData, data...), nil
}
prevData = append(prevData, data...)
}
}
// Write packet buffer 'data'
func (mc *mysqlConn) writePacket(data []byte) error {
pktLen := len(data) - 4
if pktLen > mc.maxAllowedPacket {
return ErrPktTooLarge
}
for {
var size int
if pktLen >= maxPacketSize {
data[0] = 0xff
data[1] = 0xff
data[2] = 0xff
size = maxPacketSize
} else {
data[0] = byte(pktLen)
data[1] = byte(pktLen >> 8)
data[2] = byte(pktLen >> 16)
size = pktLen
}
data[3] = mc.sequence
// Write packet
if mc.writeTimeout > 0 {
if err := mc.netConn.SetWriteDeadline(time.Now().Add(mc.writeTimeout)); err != nil {
mc.cleanup()
mc.log(err)
return err
}
}
n, err := mc.netConn.Write(data[:4+size])
if err != nil {
if cerr := mc.canceled.Value(); cerr != nil {
return cerr
}
mc.cleanup()
if n == 0 && pktLen == len(data)-4 {
// only for the first loop iteration when nothing was written yet
mc.log(err)
return errBadConnNoWrite
} else {
return err
}
}
if n != 4+size {
// io.Writer(b) must return a non-nil error if it cannot write len(b) bytes.
// The io.ErrShortWrite error is used to indicate that this rule has not been followed.
mc.cleanup()
return io.ErrShortWrite
}
mc.sequence++
if size != maxPacketSize {
return nil
}
pktLen -= size
data = data[size:]
}
}
/******************************************************************************
* Initialization Process *
******************************************************************************/
// Handshake Initialization Packet
// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::Handshake
func (mc *mysqlConn) readHandshakePacket() (data []byte, plugin string, err error) {
data, err = mc.readPacket()
if err != nil {
// for init we can rewrite this to ErrBadConn for sql.Driver to retry, since
// in connection initialization we don't risk retrying non-idempotent actions.
if err == ErrInvalidConn {
return nil, "", driver.ErrBadConn
}
return
}
if data[0] == iERR {
return nil, "", mc.handleErrorPacket(data)
}
// protocol version [1 byte]
if data[0] < minProtocolVersion {
return nil, "", fmt.Errorf(
"unsupported protocol version %d. Version %d or higher is required",
data[0],
minProtocolVersion,
)
}
// server version [null terminated string]
// connection id [4 bytes]
pos := 1 + bytes.IndexByte(data[1:], 0x00) + 1 + 4
// first part of the password cipher [8 bytes]
authData := data[pos : pos+8]
// (filler) always 0x00 [1 byte]
pos += 8 + 1
// capability flags (lower 2 bytes) [2 bytes]
mc.flags = clientFlag(binary.LittleEndian.Uint16(data[pos : pos+2]))
if mc.flags&clientProtocol41 == 0 {
return nil, "", ErrOldProtocol
}
if mc.flags&clientSSL == 0 && mc.cfg.TLS != nil {
if mc.cfg.AllowFallbackToPlaintext {
mc.cfg.TLS = nil
} else {
return nil, "", ErrNoTLS
}
}
pos += 2
if len(data) > pos {
// character set [1 byte]
// status flags [2 bytes]
// capability flags (upper 2 bytes) [2 bytes]
// length of auth-plugin-data [1 byte]
// reserved (all [00]) [10 bytes]
pos += 1 + 2 + 2 + 1 + 10
// second part of the password cipher [minimum 13 bytes],
// where len=MAX(13, length of auth-plugin-data - 8)
//
// The web documentation is ambiguous about the length. However,
// according to mysql-5.7/sql/auth/sql_authentication.cc line 538,
// the 13th byte is "\0 byte, terminating the second part of
// a scramble". So the second part of the password cipher is
// a NULL terminated string that's at least 13 bytes with the
// last byte being NULL.
//
// The official Python library uses the fixed length 12
// which seems to work but technically could have a hidden bug.
authData = append(authData, data[pos:pos+12]...)
pos += 13
// EOF if version (>= 5.5.7 and < 5.5.10) or (>= 5.6.0 and < 5.6.2)
// \NUL otherwise
if end := bytes.IndexByte(data[pos:], 0x00); end != -1 {
plugin = string(data[pos : pos+end])
} else {
plugin = string(data[pos:])
}
// make a memory safe copy of the cipher slice
var b [20]byte
copy(b[:], authData)
return b[:], plugin, nil
}
// make a memory safe copy of the cipher slice
var b [8]byte
copy(b[:], authData)
return b[:], plugin, nil
}
// Client Authentication Packet
// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::HandshakeResponse
func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, plugin string) error {
// Adjust client flags based on server support
clientFlags := clientProtocol41 |
clientSecureConn |
clientLongPassword |
clientTransactions |
clientLocalFiles |
clientPluginAuth |
clientMultiResults |
clientConnectAttrs |
mc.flags&clientLongFlag
if mc.cfg.ClientFoundRows {
clientFlags |= clientFoundRows
}
// To enable TLS / SSL
if mc.cfg.TLS != nil {
clientFlags |= clientSSL
}
if mc.cfg.MultiStatements {
clientFlags |= clientMultiStatements
}
// encode length of the auth plugin data
var authRespLEIBuf [9]byte
authRespLen := len(authResp)
authRespLEI := appendLengthEncodedInteger(authRespLEIBuf[:0], uint64(authRespLen))
if len(authRespLEI) > 1 {
// if the length can not be written in 1 byte, it must be written as a
// length encoded integer
clientFlags |= clientPluginAuthLenEncClientData
}
pktLen := 4 + 4 + 1 + 23 + len(mc.cfg.User) + 1 + len(authRespLEI) + len(authResp) + 21 + 1
// To specify a db name
if n := len(mc.cfg.DBName); n > 0 {
clientFlags |= clientConnectWithDB
pktLen += n + 1
}
// encode length of the connection attributes
var connAttrsLEIBuf [9]byte
connAttrsLen := len(mc.connector.encodedAttributes)
connAttrsLEI := appendLengthEncodedInteger(connAttrsLEIBuf[:0], uint64(connAttrsLen))
pktLen += len(connAttrsLEI) + len(mc.connector.encodedAttributes)
// Calculate packet length and get buffer with that size
data, err := mc.buf.takeBuffer(pktLen + 4)
if err != nil {
// cannot take the buffer. Something must be wrong with the connection
mc.log(err)
return errBadConnNoWrite
}
// ClientFlags [32 bit]
data[4] = byte(clientFlags)
data[5] = byte(clientFlags >> 8)
data[6] = byte(clientFlags >> 16)
data[7] = byte(clientFlags >> 24)
// MaxPacketSize [32 bit] (none)
data[8] = 0x00
data[9] = 0x00
data[10] = 0x00
data[11] = 0x00
// Collation ID [1 byte]
cname := mc.cfg.Collation
if cname == "" {
cname = defaultCollation
}
var found bool
data[12], found = collations[cname]
if !found {
// Note possibility for false negatives:
// could be triggered although the collation is valid if the
// collations map does not contain entries the server supports.
return fmt.Errorf("unknown collation: %q", cname)
}
// Filler [23 bytes] (all 0x00)
pos := 13
for ; pos < 13+23; pos++ {
data[pos] = 0
}
// SSL Connection Request Packet
// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::SSLRequest
if mc.cfg.TLS != nil {
// Send TLS / SSL request packet
if err := mc.writePacket(data[:(4+4+1+23)+4]); err != nil {
return err
}
// Switch to TLS
tlsConn := tls.Client(mc.netConn, mc.cfg.TLS)
if err := tlsConn.Handshake(); err != nil {
if cerr := mc.canceled.Value(); cerr != nil {
return cerr
}
return err
}
mc.netConn = tlsConn
mc.buf.nc = tlsConn
}
// User [null terminated string]
if len(mc.cfg.User) > 0 {
pos += copy(data[pos:], mc.cfg.User)
}
data[pos] = 0x00
pos++
// Auth Data [length encoded integer]
pos += copy(data[pos:], authRespLEI)
pos += copy(data[pos:], authResp)
// Databasename [null terminated string]
if len(mc.cfg.DBName) > 0 {
pos += copy(data[pos:], mc.cfg.DBName)
data[pos] = 0x00
pos++
}
pos += copy(data[pos:], plugin)
data[pos] = 0x00
pos++
// Connection Attributes
pos += copy(data[pos:], connAttrsLEI)
pos += copy(data[pos:], []byte(mc.connector.encodedAttributes))
// Send Auth packet
return mc.writePacket(data[:pos])
}
// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::AuthSwitchResponse
func (mc *mysqlConn) writeAuthSwitchPacket(authData []byte) error {
pktLen := 4 + len(authData)
data, err := mc.buf.takeSmallBuffer(pktLen)
if err != nil {
// cannot take the buffer. Something must be wrong with the connection
mc.log(err)
return errBadConnNoWrite
}
// Add the auth data [EOF]
copy(data[4:], authData)
return mc.writePacket(data)
}
/******************************************************************************
* Command Packets *
******************************************************************************/
func (mc *mysqlConn) writeCommandPacket(command byte) error {
// Reset Packet Sequence
mc.sequence = 0
data, err := mc.buf.takeSmallBuffer(4 + 1)
if err != nil {
// cannot take the buffer. Something must be wrong with the connection
mc.log(err)
return errBadConnNoWrite
}
// Add command byte
data[4] = command
// Send CMD packet
return mc.writePacket(data)
}
func (mc *mysqlConn) writeCommandPacketStr(command byte, arg string) error {
// Reset Packet Sequence
mc.sequence = 0
pktLen := 1 + len(arg)
data, err := mc.buf.takeBuffer(pktLen + 4)
if err != nil {
// cannot take the buffer. Something must be wrong with the connection
mc.log(err)
return errBadConnNoWrite
}
// Add command byte
data[4] = command
// Add arg
copy(data[5:], arg)
// Send CMD packet
return mc.writePacket(data)
}
func (mc *mysqlConn) writeCommandPacketUint32(command byte, arg uint32) error {
// Reset Packet Sequence
mc.sequence = 0
data, err := mc.buf.takeSmallBuffer(4 + 1 + 4)
if err != nil {
// cannot take the buffer. Something must be wrong with the connection
mc.log(err)
return errBadConnNoWrite
}
// Add command byte
data[4] = command
// Add arg [32 bit]
data[5] = byte(arg)
data[6] = byte(arg >> 8)
data[7] = byte(arg >> 16)
data[8] = byte(arg >> 24)
// Send CMD packet
return mc.writePacket(data)
}
/******************************************************************************
* Result Packets *
******************************************************************************/
func (mc *mysqlConn) readAuthResult() ([]byte, string, error) {
data, err := mc.readPacket()
if err != nil {
return nil, "", err
}
// packet indicator
switch data[0] {
case iOK:
// resultUnchanged, since auth happens before any queries or
// commands have been executed.
return nil, "", mc.resultUnchanged().handleOkPacket(data)
case iAuthMoreData:
return data[1:], "", err
case iEOF:
if len(data) == 1 {
// https://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::OldAuthSwitchRequest
return nil, "mysql_old_password", nil
}
pluginEndIndex := bytes.IndexByte(data, 0x00)
if pluginEndIndex < 0 {
return nil, "", ErrMalformPkt
}
plugin := string(data[1:pluginEndIndex])
authData := data[pluginEndIndex+1:]
return authData, plugin, nil
default: // Error otherwise
return nil, "", mc.handleErrorPacket(data)
}
}
// Returns error if Packet is not a 'Result OK'-Packet
func (mc *okHandler) readResultOK() error {
data, err := mc.conn().readPacket()
if err != nil {
return err
}
if data[0] == iOK {
return mc.handleOkPacket(data)
}
return mc.conn().handleErrorPacket(data)
}
// Result Set Header Packet
// https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_query_response.html
func (mc *okHandler) readResultSetHeaderPacket() (int, error) {
// handleOkPacket replaces both values; other cases leave the values unchanged.
mc.result.affectedRows = append(mc.result.affectedRows, 0)
mc.result.insertIds = append(mc.result.insertIds, 0)
data, err := mc.conn().readPacket()
if err != nil {
return 0, err
}
switch data[0] {
case iOK:
return 0, mc.handleOkPacket(data)
case iERR:
return 0, mc.conn().handleErrorPacket(data)
case iLocalInFile:
return 0, mc.handleInFileRequest(string(data[1:]))
}
// column count
// https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_query_response_text_resultset.html
num, _, _ := readLengthEncodedInteger(data)
// ignore remaining data in the packet. see #1478.
return int(num), nil
}
// Error Packet
// http://dev.mysql.com/doc/internals/en/generic-response-packets.html#packet-ERR_Packet
func (mc *mysqlConn) handleErrorPacket(data []byte) error {
if data[0] != iERR {
return ErrMalformPkt
}
// 0xff [1 byte]
// Error Number [16 bit uint]
errno := binary.LittleEndian.Uint16(data[1:3])
// 1792: ER_CANT_EXECUTE_IN_READ_ONLY_TRANSACTION
// 1290: ER_OPTION_PREVENTS_STATEMENT (returned by Aurora during failover)
if (errno == 1792 || errno == 1290) && mc.cfg.RejectReadOnly {
// Oops; we are connected to a read-only connection, and won't be able
// to issue any write statements. Since RejectReadOnly is configured,
// we throw away this connection hoping this one would have write
// permission. This is specifically for a possible race condition
// during failover (e.g. on AWS Aurora). See README.md for more.
//
// We explicitly close the connection before returning
// driver.ErrBadConn to ensure that `database/sql` purges this
// connection and initiates a new one for next statement next time.
mc.Close()
return driver.ErrBadConn
}
me := &MySQLError{Number: errno}
pos := 3
// SQL State [optional: # + 5bytes string]
if data[3] == 0x23 {
copy(me.SQLState[:], data[4:4+5])
pos = 9
}
// Error Message [string]
me.Message = string(data[pos:])
return me
}
func readStatus(b []byte) statusFlag {
return statusFlag(b[0]) | statusFlag(b[1])<<8
}
// Returns an instance of okHandler for codepaths where mysqlConn.result doesn't
// need to be cleared first (e.g. during authentication, or while additional
// resultsets are being fetched.)
func (mc *mysqlConn) resultUnchanged() *okHandler {
return (*okHandler)(mc)
}
// okHandler represents the state of the connection when mysqlConn.result has
// been prepared for processing of OK packets.
//
// To correctly populate mysqlConn.result (updated by handleOkPacket()), all
// callpaths must either:
//
// 1. first clear it using clearResult(), or
// 2. confirm that they don't need to (by calling resultUnchanged()).
//
// Both return an instance of type *okHandler.
type okHandler mysqlConn
// Exposes the underlying type's methods.
func (mc *okHandler) conn() *mysqlConn {
return (*mysqlConn)(mc)
}
// clearResult clears the connection's stored affectedRows and insertIds
// fields.
//
// It returns a handler that can process OK responses.
func (mc *mysqlConn) clearResult() *okHandler {
mc.result = mysqlResult{}
return (*okHandler)(mc)
}
// Ok Packet
// http://dev.mysql.com/doc/internals/en/generic-response-packets.html#packet-OK_Packet
func (mc *okHandler) handleOkPacket(data []byte) error {
var n, m int
var affectedRows, insertId uint64
// 0x00 [1 byte]
// Affected rows [Length Coded Binary]
affectedRows, _, n = readLengthEncodedInteger(data[1:])
// Insert id [Length Coded Binary]
insertId, _, m = readLengthEncodedInteger(data[1+n:])
// Update for the current statement result (only used by
// readResultSetHeaderPacket).
if len(mc.result.affectedRows) > 0 {
mc.result.affectedRows[len(mc.result.affectedRows)-1] = int64(affectedRows)
}
if len(mc.result.insertIds) > 0 {
mc.result.insertIds[len(mc.result.insertIds)-1] = int64(insertId)
}
// server_status [2 bytes]
mc.status = readStatus(data[1+n+m : 1+n+m+2])
if mc.status&statusMoreResultsExists != 0 {
return nil
}
// warning count [2 bytes]
return nil
}
// Read Packets as Field Packets until EOF-Packet or an Error appears
// http://dev.mysql.com/doc/internals/en/com-query-response.html#packet-Protocol::ColumnDefinition41
func (mc *mysqlConn) readColumns(count int) ([]mysqlField, error) {
columns := make([]mysqlField, count)
for i := 0; ; i++ {
data, err := mc.readPacket()
if err != nil {
return nil, err
}
// EOF Packet
if data[0] == iEOF && (len(data) == 5 || len(data) == 1) {
if i == count {
return columns, nil
}
return nil, fmt.Errorf("column count mismatch n:%d len:%d", count, len(columns))
}
// Catalog
pos, err := skipLengthEncodedString(data)
if err != nil {
return nil, err
}
// Database [len coded string]
n, err := skipLengthEncodedString(data[pos:])
if err != nil {
return nil, err
}
pos += n
// Table [len coded string]
if mc.cfg.ColumnsWithAlias {
tableName, _, n, err := readLengthEncodedString(data[pos:])
if err != nil {
return nil, err
}
pos += n
columns[i].tableName = string(tableName)
} else {
n, err = skipLengthEncodedString(data[pos:])
if err != nil {
return nil, err
}
pos += n
}
// Original table [len coded string]
n, err = skipLengthEncodedString(data[pos:])
if err != nil {
return nil, err
}
pos += n
// Name [len coded string]
name, _, n, err := readLengthEncodedString(data[pos:])
if err != nil {
return nil, err
}
columns[i].name = string(name)
pos += n
// Original name [len coded string]
n, err = skipLengthEncodedString(data[pos:])
if err != nil {
return nil, err
}
pos += n
// Filler [uint8]
pos++
// Charset [charset, collation uint8]
columns[i].charSet = data[pos]
pos += 2
// Length [uint32]
columns[i].length = binary.LittleEndian.Uint32(data[pos : pos+4])
pos += 4
// Field type [uint8]
columns[i].fieldType = fieldType(data[pos])
pos++
// Flags [uint16]
columns[i].flags = fieldFlag(binary.LittleEndian.Uint16(data[pos : pos+2]))
pos += 2
// Decimals [uint8]
columns[i].decimals = data[pos]
//pos++
// Default value [len coded binary]
//if pos < len(data) {
// defaultVal, _, err = bytesToLengthCodedBinary(data[pos:])
//}
}
}
// Read Packets as Field Packets until EOF-Packet or an Error appears
// http://dev.mysql.com/doc/internals/en/com-query-response.html#packet-ProtocolText::ResultsetRow
func (rows *textRows) readRow(dest []driver.Value) error {
mc := rows.mc
if rows.rs.done {
return io.EOF
}
data, err := mc.readPacket()
if err != nil {
return err
}
// EOF Packet
if data[0] == iEOF && len(data) == 5 {
// server_status [2 bytes]
rows.mc.status = readStatus(data[3:])
rows.rs.done = true
if !rows.HasNextResultSet() {
rows.mc = nil
}
return io.EOF
}
if data[0] == iERR {
rows.mc = nil
return mc.handleErrorPacket(data)
}
// RowSet Packet
var (
n int
isNull bool
pos int = 0
)
for i := range dest {
// Read bytes and convert to string
var buf []byte
buf, isNull, n, err = readLengthEncodedString(data[pos:])
pos += n
if err != nil {
return err
}
if isNull {
dest[i] = nil
continue
}
switch rows.rs.columns[i].fieldType {
case fieldTypeTimestamp,
fieldTypeDateTime,
fieldTypeDate,
fieldTypeNewDate:
if mc.parseTime {
dest[i], err = parseDateTime(buf, mc.cfg.Loc)
} else {
dest[i] = buf
}
case fieldTypeTiny, fieldTypeShort, fieldTypeInt24, fieldTypeYear, fieldTypeLong:
dest[i], err = strconv.ParseInt(string(buf), 10, 64)
case fieldTypeLongLong:
if rows.rs.columns[i].flags&flagUnsigned != 0 {
dest[i], err = strconv.ParseUint(string(buf), 10, 64)
} else {
dest[i], err = strconv.ParseInt(string(buf), 10, 64)
}
case fieldTypeFloat:
var d float64
d, err = strconv.ParseFloat(string(buf), 32)
dest[i] = float32(d)
case fieldTypeDouble:
dest[i], err = strconv.ParseFloat(string(buf), 64)
default:
dest[i] = buf
}
if err != nil {
return err
}
}
return nil
}
// Reads Packets until EOF-Packet or an Error appears. Returns count of Packets read
func (mc *mysqlConn) readUntilEOF() error {
for {
data, err := mc.readPacket()
if err != nil {
return err
}
switch data[0] {
case iERR:
return mc.handleErrorPacket(data)
case iEOF:
if len(data) == 5 {
mc.status = readStatus(data[3:])
}
return nil
}
}
}
/******************************************************************************
* Prepared Statements *
******************************************************************************/
// Prepare Result Packets
// http://dev.mysql.com/doc/internals/en/com-stmt-prepare-response.html
func (stmt *mysqlStmt) readPrepareResultPacket() (uint16, error) {
data, err := stmt.mc.readPacket()
if err == nil {
// packet indicator [1 byte]
if data[0] != iOK {
return 0, stmt.mc.handleErrorPacket(data)
}
// statement id [4 bytes]
stmt.id = binary.LittleEndian.Uint32(data[1:5])
// Column count [16 bit uint]
columnCount := binary.LittleEndian.Uint16(data[5:7])
// Param count [16 bit uint]
stmt.paramCount = int(binary.LittleEndian.Uint16(data[7:9]))
// Reserved [8 bit]
// Warning count [16 bit uint]
return columnCount, nil
}
return 0, err
}
// http://dev.mysql.com/doc/internals/en/com-stmt-send-long-data.html
func (stmt *mysqlStmt) writeCommandLongData(paramID int, arg []byte) error {
maxLen := stmt.mc.maxAllowedPacket - 1
pktLen := maxLen
// After the header (bytes 0-3) follows before the data:
// 1 byte command
// 4 bytes stmtID
// 2 bytes paramID
const dataOffset = 1 + 4 + 2
// Cannot use the write buffer since
// a) the buffer is too small
// b) it is in use
data := make([]byte, 4+1+4+2+len(arg))
copy(data[4+dataOffset:], arg)
for argLen := len(arg); argLen > 0; argLen -= pktLen - dataOffset {
if dataOffset+argLen < maxLen {
pktLen = dataOffset + argLen
}
stmt.mc.sequence = 0
// Add command byte [1 byte]
data[4] = comStmtSendLongData
// Add stmtID [32 bit]
data[5] = byte(stmt.id)
data[6] = byte(stmt.id >> 8)
data[7] = byte(stmt.id >> 16)
data[8] = byte(stmt.id >> 24)
// Add paramID [16 bit]
data[9] = byte(paramID)
data[10] = byte(paramID >> 8)
// Send CMD packet
err := stmt.mc.writePacket(data[:4+pktLen])
if err == nil {
data = data[pktLen-dataOffset:]
continue
}
return err
}
// Reset Packet Sequence
stmt.mc.sequence = 0
return nil
}
// Execute Prepared Statement
// http://dev.mysql.com/doc/internals/en/com-stmt-execute.html
func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
if len(args) != stmt.paramCount {
return fmt.Errorf(
"argument count mismatch (got: %d; has: %d)",
len(args),
stmt.paramCount,
)
}
const minPktLen = 4 + 1 + 4 + 1 + 4
mc := stmt.mc
// Determine threshold dynamically to avoid packet size shortage.
longDataSize := mc.maxAllowedPacket / (stmt.paramCount + 1)
if longDataSize < 64 {
longDataSize = 64
}
// Reset packet-sequence
mc.sequence = 0
var data []byte
var err error
if len(args) == 0 {
data, err = mc.buf.takeBuffer(minPktLen)
} else {
data, err = mc.buf.takeCompleteBuffer()
// In this case the len(data) == cap(data) which is used to optimise the flow below.
}