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session.go
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session.go
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package tds
import (
"context"
"crypto/rand"
"crypto/rsa"
"crypto/sha1"
"crypto/tls"
"database/sql"
"database/sql/driver"
"encoding/asn1"
"encoding/pem"
"fmt"
"io"
"net"
"regexp"
"strconv"
"time"
"errors"
)
var validHost = regexp.MustCompile("([[:alpha:]]|[_.-])*:[0-9]+$")
// ErrUnsupportedPassWordEncrytion is caused by an unsupported password encrytion scheme (used by ASE <= 15.0.1)
var ErrUnsupportedPassWordEncrytion = errors.New("tds: login failed. Unsupported encryption")
// non configurable logout Timeout
var logoutTimeout = 5
var isError = func(s SybError) bool {
return s.Severity > 10
}
// tds session.
//
// this struct actually implements the protocol,
// sends queries, processes answers
// It also embeds the response/query structs
type session struct {
valid bool
charConvert bool
res *Result // response info
// tds buffer to split into TDS PDUs, send and read packets
b *buf
c io.ReadWriteCloser // net connection
capabilities capabilities // tds capabilities
// parameters
packetSize int
readTimeout int
writeTimeout int
loginTimeout int
// tds env
database string
charset string
language string
server string
serverType string
// tokens for reuse
envChange envChange
done done
returnStatus returnStatus
sqlMessage sqlMessage
// netlib sesion state
state *state
messageMap map[token]messageReader
// error handling routine
IsError func(SybError) bool
}
// instantiate a login sctruct
func newLogin(prm connParams) *login {
// default values
l := &login{library: defaultLibrary, protocolVersion: defaultProtocolVersion,
libraryVersion: defaultLibraryVersion, charset: prm.charset,
clientHost: prm.clientHost, user: prm.user,
encrypted: loginSecEncrypt1 | loginSecEncrypt2 | loginSecNonce,
app: prm.app, packetSize: prm.packetSize, pid: prm.pid}
if prm.encryptPassword == "no" {
l.encrypted = 0
l.password, l.password2 = prm.password, prm.password
}
return l
}
// dial the connection, init the TDS buffer, attempt login
func newSession(prm connParams) (s *session, err error) {
s = &session{envChange: envChange{msg: newMsg(envChangeToken)},
done: done{msg: newMsg(doneToken)},
sqlMessage: sqlMessage{msg: newMsg(sqlMessageToken)},
returnStatus: returnStatus{msg: newMsg(returnStatusToken)},
IsError: isError, packetSize: prm.packetSize,
readTimeout: prm.readTimeout, writeTimeout: prm.writeTimeout,
loginTimeout: prm.loginTimeout, res: &Result{lastError: nil}}
// init resultset, buffer, parameters, message cache...
s.res.s = s
s.server = prm.host
s.messageMap = map[token]messageReader{envChangeToken: &s.envChange,
doneProcToken: &s.done, doneInProcToken: &s.done,
doneToken: &s.done, returnStatusToken: &s.returnStatus,
sqlMessageToken: &s.sqlMessage}
// connect
if s.c, err = dial(prm); err != nil {
return s, err
}
// init netlib buffer
s.b = newBuf(s.packetSize, s.c)
s.b.ReadTimeout, s.b.WriteTimeout = s.readTimeout, s.writeTimeout
s.b.defaultMessageMap = s.messageMap
// init state
s.state = &state{handler: func(t token) error {
var err error
// process all common tokens (doneToken, doneInProc, envChange, info, etc)
// this will fill the result structure, the sqlMessages array, etc
switch t {
case sqlMessageToken:
err = s.processsqlMessage()
case envChangeToken:
err = s.processEnvChange()
case returnStatusToken:
err = s.processReturnStatus()
case doneProcToken, doneInProcToken, doneToken:
// last message for this stream
err = s.processDone(token(t))
}
// error was found, return now to caller.
// Typically processDone returns an error
// when a critical sybase error was faced during processing of the rows.
// We need to make this error bubbles up.
return err
}}
// now log in
if err = s.login(prm); err != nil {
// retry without password encryption
if err == ErrUnsupportedPassWordEncrytion && prm.encryptPassword == "try" {
s.c.Close()
prm.encryptPassword = "no"
return newSession(prm)
}
return s, err
}
return s, nil
}
// dial connects to the target host and returns a writer.
func dial(prm connParams) (io.ReadWriteCloser, error) {
if prm.ssl == "on" {
return tls.DialWithDialer(&net.Dialer{Timeout: time.Duration(prm.loginTimeout) * time.Second},
"tcp", prm.host, &tls.Config{InsecureSkipVerify: true})
}
return net.DialTimeout("tcp", prm.host,
time.Duration(prm.loginTimeout)*time.Second)
}
// login sends the login packets. Login and capabilities required.
// If asked, it will also handle password encryption.
func (s *session) login(prm connParams) (err error) {
login := newLogin(prm)
login.msg = msg{flags: fixedSize}
s.capabilities = *newCapabilities()
s.capabilities.msg = newMsg(capabilitiesToken)
login.setCapabilities(s.capabilities)
ctx, cancel := context.WithTimeout(context.Background(),
time.Duration(s.loginTimeout)*time.Second)
defer cancel()
// send the login
if err = s.b.send(ctx, loginPacket, login, &login.capabilities); err != nil {
return fmt.Errorf("tds: login send failed: %s", err)
}
s.clearResult()
loginAck := &loginAck{msg: newMsg(loginAckToken)}
pf := &columns{msg: newMsg(paramFmtToken)}
wpf := &columns{msg: newMsg(paramFmt2Token), flags: wide | param}
p := &row{msg: newMsg(paramToken)}
// only retry once
try := 0
// get login ack/auth challenge message
loginResponse:
for f := s.initState(ctx,
map[token]messageReader{loginAckToken: loginAck,
capabilitiesToken: &s.capabilities,
paramFmtToken: pf,
paramFmt2Token: wpf,
paramToken: p}); f != nil; f = f(s.state) {
switch s.state.t {
// bind the param descriptor and the param
case paramFmtToken:
p.columns = pf.fmts
case paramFmt2Token:
p.columns = wpf.fmts
}
}
if s.state.err != nil && s.state.err != io.EOF {
return s.state.err
}
// RSA encryption supported, extract the public key
// only 1 try
if len(p.data) > 0 && try == 0 {
// check if server supports RSA encryption
if rsa, ok := p.data[0].(int64); ok {
if rsa != 1 {
return ErrUnsupportedPassWordEncrytion
}
} else {
return ErrUnsupportedPassWordEncrytion
}
// get rsa public key, and encrypt
try = 1
block, _ := pem.Decode(p.data[1].([]byte))
if block == nil {
return ErrUnsupportedPassWordEncrytion
}
var pk rsa.PublicKey
_, err := asn1.Unmarshal(block.Bytes, &pk)
if err != nil {
return ErrUnsupportedPassWordEncrytion
}
// nonce introduces randomness to avoid replay attacks
var message []byte
if len(p.data) > 2 {
nonce := p.data[2].([]byte)
message = append(nonce, []byte(prm.password)...)
} else {
// no nonce, do not know this encryption method
return ErrUnsupportedPassWordEncrytion
}
ciphertext, err := rsa.EncryptOAEP(sha1.New(), rand.Reader, &pk, message, []byte{})
if err != nil {
return ErrUnsupportedPassWordEncrytion
}
// send the encrypted password
// unknown sybMsg for now, help welcome
msg1 := &sybMsg{msg: newMsg(msgToken), field1: 0x01, field2: 0x0001F}
msg2 := &sybMsg{msg: newMsg(msgToken), field1: 0x01, field2: 0x0020}
cols1 := &columns{msg: newMsg(paramFmtToken), fmts: []colFmt{
{colType: getType(longBinaryType, 2147483647)},
}}
row1 := &row{msg: newMsg(paramToken), data: []driver.Value{ciphertext},
columns: cols1.fmts[:]}
cols2 := &columns{msg: newMsg(paramFmtToken), fmts: []colFmt{
{colType: getType(varcharType, 255)},
{colType: getType(longBinaryType, 2147483647)},
}}
row2 := &row{msg: newMsg(paramToken), data: []driver.Value{"", ciphertext},
columns: cols2.fmts[:]}
if err = s.b.send(ctx, normalPacket, msg1, cols1, row1, msg2, cols2, row2); err != nil {
return fmt.Errorf("tds: login send failed: %s", err)
}
// re-read, we should get login ack now
goto loginResponse
}
if loginAck.ack != 5 {
return errors.New("tds: login failed. Please check username/password")
}
// we are logged in
s.valid = true
// keep the server name provided in the loginAck
s.serverType = loginAck.server
// use the proper database
if prm.database != "" {
if _, err = s.simpleExec(ctx, "use "+prm.database); err != nil {
return fmt.Errorf("tds: use database failed: %s", err)
}
}
return err
}
// checkErr check if the given error is fatal.
// If the error is not a sybase error message,
// but another unknown error, mark the connection as bad.
// If the root cause is EOF or a context cancelled,
// simply rethrow it so that driver can catch them.
func (s *session) checkErr(err error, msg string, ignoreEOF bool) error {
if !s.valid {
return driver.ErrBadConn
}
// fastpath for io.EOF
switch err {
case nil:
return nil
case io.EOF:
if ignoreEOF {
return nil
}
return io.EOF
case context.Canceled, context.DeadlineExceeded:
return err
}
// if the error is not a standard sybase message,
// the connection is invalid
if _, ok := err.(SybError); !ok {
s.valid = false
}
return fmt.Errorf("%s: %s", msg, err)
}
// Close terminates the session
// by sending logout message and closing tcp connection.
func (s *session) Close() error {
// no connection
if s.c == nil {
s.valid = false
return nil
}
defer s.c.Close()
ctx, cancel := context.WithTimeout(context.Background(),
time.Duration(logoutTimeout)*time.Second)
defer cancel()
if err := s.b.send(ctx, normalPacket,
logout{msg: newMsg(logoutToken)}); err != nil {
return fmt.Errorf("tds: close failed: %s", err)
}
return nil
}
func (s *session) Begin() (driver.Tx, error) {
return s.BeginTx(nil,
driver.TxOptions{Isolation: driver.IsolationLevel(sql.LevelDefault)})
}
// ErrInvalidIsolationLevel is raised when an unsupported isolation level is asked.
var ErrInvalidIsolationLevel = errors.New("tds: invalid or unsupported isolation level")
// ErrNoReadOnly is raise when readonly attribute of driver.TxOptions is set.
// Readonly sessions are not supported by sybase.
var ErrNoReadOnly = errors.New("tds: readonly is unsupported")
// map between sql.IsolationLevel and sybase isolation levels
var isolationLevelMap = []int{isolationReadCommited, isolationReadUncommited,
isolationReadCommited, isolationNotImplemented,
isolationRepeatableRead, isolationNotImplemented, isolationSerializable,
isolationNotImplemented}
// BeginTx implements driver.ConnBeginTx interface
func (s *session) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
// connection is bad
if !s.valid {
return s, driver.ErrBadConn
}
if opts.ReadOnly {
return s, ErrNoReadOnly
}
if sql.IsolationLevel(opts.Isolation) != sql.LevelDefault {
if int(opts.Isolation) > len(isolationLevelMap) {
return s, ErrInvalidIsolationLevel
}
level := isolationLevelMap[int(opts.Isolation)]
if level == isolationNotImplemented {
return s, ErrInvalidIsolationLevel
}
// send the option change command to set isolation level
optCmd := optionCmd{msg: newMsg(optionCmdToken), command: optionSet,
option: optionIsolationLevel, value: level}
if err := s.b.send(ctx, normalPacket, &optCmd); err != nil {
s.valid = false
return s, s.checkErr(err, "tds: isolation level set failed", false)
}
for f := s.initState(ctx, map[token]messageReader{}); f != nil; f = f(s.state) {
}
if s.state.err = s.checkErr(s.state.err, "tds: isolation level set failed", true); s.state.err != nil {
s.valid = false
return s, s.state.err
}
}
_, err := s.simpleExec(ctx, `begin tran
if @@transtate != 0 raiserror 25000 'Invalid transaction state'`)
return s, s.checkErr(err, "tds: begin failed", true)
}
func (s *session) Commit() error {
_, err := s.simpleExec(nil, `if @@trancount > 0 commit tran
if @@transtate != 1 raiserror 25000 'Invalid transaction state'`)
return s.checkErr(err, "tds: commit failed", true)
}
func (s *session) Rollback() error {
_, err := s.simpleExec(nil, `if @@trancount > 0 rollback tran
if @@transtate != 3 raiserror 25000 'Invalid transaction state'`)
return s.checkErr(err, "tds: rollback failed", true)
}
// Ping implements driver.Pinger interface
func (s *session) Ping(ctx context.Context) error {
if !s.valid {
return driver.ErrBadConn
}
_, err := s.SelectValue(ctx, "")
if err != nil {
return err
}
return nil
}
// Exec implements the Execer interface.
// The aim is to use language queries when no parameters are given
func (s *session) Query(query string, args []driver.Value) (driver.Rows, error) {
if len(args) != 0 {
return nil, driver.ErrSkip
}
return s.simpleQuery(nil, query)
}
// Implement the "QueryerContext" interface
func (s *session) QueryContext(ctx context.Context, query string,
namedArgs []driver.NamedValue) (driver.Rows, error) {
if len(namedArgs) != 0 {
return nil, driver.ErrSkip
}
return s.simpleQuery(ctx, query)
}
func (s *session) simpleQuery(ctx context.Context, query string) (rows *Rows, err error) {
if !s.valid {
return &emptyRows, driver.ErrBadConn
}
// send query
if err := s.b.send(ctx, normalPacket, &language{msg: newMsg(languageToken), query: query}); err != nil {
s.valid = false
return &emptyRows, s.checkErr(err, "tds: query send failed", false)
}
s.clearResult()
return newRow(ctx, s)
}
// Exec implements the Querier interface.
// The aim is to use language queries when no parameters are given
func (s *session) Exec(query string, args []driver.Value) (driver.Result, error) {
if len(args) != 0 {
return &emptyResult, driver.ErrSkip
}
return s.simpleExec(nil, query)
}
// Implement the "ExecerContext" interface
func (s *session) ExecContext(ctx context.Context, query string,
namedArgs []driver.NamedValue) (driver.Result, error) {
if len(namedArgs) != 0 {
return &emptyResult, driver.ErrSkip
}
return s.simpleExec(ctx, query)
}
func (s *session) simpleExec(ctx context.Context, query string) (res *Result, err error) {
if !s.valid {
return &emptyResult, driver.ErrBadConn
}
// send query
rows, err := s.simpleQuery(ctx, query)
if err = s.checkErr(err, "tds: exec failed", true); err != nil {
return &emptyResult, err
}
rows.Close()
return &(*s.res), nil
}
// Prepare prepares a statement and returns it
func (s *session) Prepare(query string) (driver.Stmt, error) {
if !s.valid {
return &emptyStmt, driver.ErrBadConn
}
return newStmt(nil, s, query)
}
// Prepare prepares a statement and returns it
func (s *session) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
if !s.valid {
return &emptyStmt, driver.ErrBadConn
}
return newStmt(ctx, s, query)
}
// Reads exactly one value from an sql query
func (s *session) SelectValue(ctx context.Context, query string) (value interface{}, err error) {
// send query
rows, err := s.simpleQuery(ctx, query)
if err != nil {
return nil, s.checkErr(err, "tds: select value failed", false)
}
defer rows.Close()
vals := make([]driver.Value, 1)
err = rows.Next(vals)
if err != io.EOF && err != nil {
return nil, err
}
return vals[0], nil
}
func (s *session) clearResult() {
s.res.affectedRows, s.res.returnStatus = 0, 0
s.res.hasError, s.res.hasAffectedRows, s.res.hasReturnStatus, s.res.final = false, false, false, false
s.res.messages = nil
s.res.lastError = nil
}
// returns a brand new netlib state
func newState(ctx context.Context, msg map[token]messageReader,
handler func(token) error) *state {
return &state{msg: msg, ctx: ctx, handler: handler}
}
// initiates a new netlib state and reads first message.
// Will also return a state function to read next message.
func (s *session) initState(ctx context.Context,
messages map[token]messageReader) stateFn {
s.state.ctx, s.state.msg = ctx, messages
s.state.err = nil
return s.b.receive(s.state)
}
// process the error/info messages and determine if there's an error
func (s *session) processsqlMessage() (err error) {
// add it to the list of messages which is reset at each query
s.res.messages = append(s.res.messages, s.sqlMessage.SybError)
// propagate if its an error
if s.IsError(s.sqlMessage.SybError) {
s.res.lastError = s.sqlMessage.SybError
}
return nil
}
// process the env change messages and determine if there's an error
func (s *session) processEnvChange() (err error) {
switch s.envChange.changeType {
default:
return fmt.Errorf("tds: unknow env change type: %#x",
s.envChange.changeType)
case dbChange:
s.database = s.envChange.newValue
case langChange:
s.language = s.envChange.newValue
case charsetChange:
switch s.envChange.newValue {
default:
if err = s.b.SetCharset(s.envChange.newValue); err != nil {
return fmt.Errorf("tds: cannot encode to '%s' charset: %s", s.envChange.newValue, err)
}
s.charset = s.envChange.newValue
s.charConvert = true
case "":
if err = s.b.SetCharset(s.envChange.oldValue); err != nil {
return fmt.Errorf("tds: cannot encode to '%s' charset: %s", s.envChange.oldValue, err)
}
s.charset = s.envChange.oldValue
s.charConvert = true
case "utf8":
s.charset = s.envChange.newValue
}
case packetSizeChange:
if packetSize, err := strconv.Atoi(s.envChange.newValue); err == nil {
s.packetSize = packetSize
s.b.PacketSize = packetSize
}
}
return nil
}
// process the done token's information (row count, error status, final ?)
func (s *session) processDone(t token) (err error) {
// ignore most doneInProc tokens
if t == doneInProcToken && s.done.status&doneProc == 0 {
return nil
}
// get row count if any
if s.done.status&doneCount != 0 || s.done.status&doneProc != 0 {
// done with doneProc set will contain
// the row count for inserts in prepared statements when "send doneinproc" is 0
s.res.hasAffectedRows = true
s.res.affectedRows = int64(s.done.count)
}
// check if this token indicates an error
if s.done.status&doneError != 0 && s.res.lastError == nil {
s.res.lastError = errors.New("unknow error reported by done token")
}
// last bit set
s.res.final = s.done.status&doneMoreResults == 0
// return error if found during this message stream.
if s.res.final {
if s.res.lastError != nil {
return s.res.lastError
}
return io.EOF
}
return nil
}
// process the return status token. Sent when executing a stored procedure
func (s *session) processReturnStatus() (err error) {
s.res.hasReturnStatus = true
s.res.returnStatus = int(s.returnStatus.status)
return nil
}