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forgejo/vendor/github.com/denisenkom/go-mssqldb/token.go
6543 792b4dba2c
[Vendor] Update directly used dependencys (#15593)
* update github.com/blevesearch/bleve v2.0.2 -> v2.0.3

* github.com/denisenkom/go-mssqldb v0.9.0 -> v0.10.0

* github.com/editorconfig/editorconfig-core-go v2.4.1 -> v2.4.2

* github.com/go-chi/cors v1.1.1 -> v1.2.0

* github.com/go-git/go-billy v5.0.0 -> v5.1.0

* github.com/go-git/go-git v5.2.0 -> v5.3.0

* github.com/go-ldap/ldap v3.2.4 -> v3.3.0

* github.com/go-redis/redis v8.6.0 -> v8.8.2

* github.com/go-sql-driver/mysql v1.5.0 -> v1.6.0

* github.com/go-swagger/go-swagger v0.26.1 -> v0.27.0

* github.com/lib/pq v1.9.0 -> v1.10.1

* github.com/mattn/go-sqlite3 v1.14.6 -> v1.14.7

* github.com/go-testfixtures/testfixtures v3.5.0 -> v3.6.0

* github.com/issue9/identicon v1.0.1 -> v1.2.0

* github.com/klauspost/compress v1.11.8 -> v1.12.1

* github.com/mgechev/revive v1.0.3 -> v1.0.6

* github.com/microcosm-cc/bluemonday v1.0.7 -> v1.0.8

* github.com/niklasfasching/go-org v1.4.0 -> v1.5.0

* github.com/olivere/elastic v7.0.22 -> v7.0.24

* github.com/pelletier/go-toml v1.8.1 -> v1.9.0

* github.com/prometheus/client_golang v1.9.0 -> v1.10.0

* github.com/xanzy/go-gitlab v0.44.0 -> v0.48.0

* github.com/yuin/goldmark v1.3.3 -> v1.3.5

* github.com/6543/go-version v1.2.4 -> v1.3.1

* do github.com/lib/pq v1.10.0 -> v1.10.1 again ...
2021-04-22 20:08:53 -04:00

890 lines
21 KiB
Go
Vendored

package mssql
import (
"context"
"encoding/binary"
"errors"
"fmt"
"io"
"io/ioutil"
"strconv"
)
//go:generate go run golang.org/x/tools/cmd/stringer -type token
type token byte
// token ids
const (
tokenReturnStatus token = 121 // 0x79
tokenColMetadata token = 129 // 0x81
tokenOrder token = 169 // 0xA9
tokenError token = 170 // 0xAA
tokenInfo token = 171 // 0xAB
tokenReturnValue token = 0xAC
tokenLoginAck token = 173 // 0xad
tokenFeatureExtAck token = 174 // 0xae
tokenRow token = 209 // 0xd1
tokenNbcRow token = 210 // 0xd2
tokenEnvChange token = 227 // 0xE3
tokenSSPI token = 237 // 0xED
tokenFedAuthInfo token = 238 // 0xEE
tokenDone token = 253 // 0xFD
tokenDoneProc token = 254
tokenDoneInProc token = 255
)
// done flags
// https://msdn.microsoft.com/en-us/library/dd340421.aspx
const (
doneFinal = 0
doneMore = 1
doneError = 2
doneInxact = 4
doneCount = 0x10
doneAttn = 0x20
doneSrvError = 0x100
)
// ENVCHANGE types
// http://msdn.microsoft.com/en-us/library/dd303449.aspx
const (
envTypDatabase = 1
envTypLanguage = 2
envTypCharset = 3
envTypPacketSize = 4
envSortId = 5
envSortFlags = 6
envSqlCollation = 7
envTypBeginTran = 8
envTypCommitTran = 9
envTypRollbackTran = 10
envEnlistDTC = 11
envDefectTran = 12
envDatabaseMirrorPartner = 13
envPromoteTran = 15
envTranMgrAddr = 16
envTranEnded = 17
envResetConnAck = 18
envStartedInstanceName = 19
envRouting = 20
)
const (
fedAuthInfoSTSURL = 0x01
fedAuthInfoSPN = 0x02
)
// COLMETADATA flags
// https://msdn.microsoft.com/en-us/library/dd357363.aspx
const (
colFlagNullable = 1
// TODO implement more flags
)
// interface for all tokens
type tokenStruct interface{}
type orderStruct struct {
ColIds []uint16
}
type doneStruct struct {
Status uint16
CurCmd uint16
RowCount uint64
errors []Error
}
func (d doneStruct) isError() bool {
return d.Status&doneError != 0 || len(d.errors) > 0
}
func (d doneStruct) getError() Error {
if len(d.errors) > 0 {
return d.errors[len(d.errors)-1]
} else {
return Error{Message: "Request failed but didn't provide reason"}
}
}
type doneInProcStruct doneStruct
// ENVCHANGE stream
// http://msdn.microsoft.com/en-us/library/dd303449.aspx
func processEnvChg(sess *tdsSession) {
size := sess.buf.uint16()
r := &io.LimitedReader{R: sess.buf, N: int64(size)}
for {
var err error
var envtype uint8
err = binary.Read(r, binary.LittleEndian, &envtype)
if err == io.EOF {
return
}
if err != nil {
badStreamPanic(err)
}
switch envtype {
case envTypDatabase:
sess.database, err = readBVarChar(r)
if err != nil {
badStreamPanic(err)
}
_, err = readBVarChar(r)
if err != nil {
badStreamPanic(err)
}
case envTypLanguage:
// currently ignored
// new value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// old value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envTypCharset:
// currently ignored
// new value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// old value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envTypPacketSize:
packetsize, err := readBVarChar(r)
if err != nil {
badStreamPanic(err)
}
_, err = readBVarChar(r)
if err != nil {
badStreamPanic(err)
}
packetsizei, err := strconv.Atoi(packetsize)
if err != nil {
badStreamPanicf("Invalid Packet size value returned from server (%s): %s", packetsize, err.Error())
}
sess.buf.ResizeBuffer(packetsizei)
case envSortId:
// currently ignored
// new value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envSortFlags:
// currently ignored
// new value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envSqlCollation:
// currently ignored
var collationSize uint8
err = binary.Read(r, binary.LittleEndian, &collationSize)
if err != nil {
badStreamPanic(err)
}
// SQL Collation data should contain 5 bytes in length
if collationSize != 5 {
badStreamPanicf("Invalid SQL Collation size value returned from server: %d", collationSize)
}
// 4 bytes, contains: LCID ColFlags Version
var info uint32
err = binary.Read(r, binary.LittleEndian, &info)
if err != nil {
badStreamPanic(err)
}
// 1 byte, contains: sortID
var sortID uint8
err = binary.Read(r, binary.LittleEndian, &sortID)
if err != nil {
badStreamPanic(err)
}
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envTypBeginTran:
tranid, err := readBVarByte(r)
if len(tranid) != 8 {
badStreamPanicf("invalid size of transaction identifier: %d", len(tranid))
}
sess.tranid = binary.LittleEndian.Uint64(tranid)
if err != nil {
badStreamPanic(err)
}
if sess.logFlags&logTransaction != 0 {
sess.log.Printf("BEGIN TRANSACTION %x\n", sess.tranid)
}
_, err = readBVarByte(r)
if err != nil {
badStreamPanic(err)
}
case envTypCommitTran, envTypRollbackTran:
_, err = readBVarByte(r)
if err != nil {
badStreamPanic(err)
}
_, err = readBVarByte(r)
if err != nil {
badStreamPanic(err)
}
if sess.logFlags&logTransaction != 0 {
if envtype == envTypCommitTran {
sess.log.Printf("COMMIT TRANSACTION %x\n", sess.tranid)
} else {
sess.log.Printf("ROLLBACK TRANSACTION %x\n", sess.tranid)
}
}
sess.tranid = 0
case envEnlistDTC:
// currently ignored
// new value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// old value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envDefectTran:
// currently ignored
// new value
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envDatabaseMirrorPartner:
sess.partner, err = readBVarChar(r)
if err != nil {
badStreamPanic(err)
}
_, err = readBVarChar(r)
if err != nil {
badStreamPanic(err)
}
case envPromoteTran:
// currently ignored
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// dtc token
// spec says it should be L_VARBYTE, so this code might be wrong
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envTranMgrAddr:
// currently ignored
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// XACT_MANAGER_ADDRESS = B_VARBYTE
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envTranEnded:
// currently ignored
// old value, B_VARBYTE
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envResetConnAck:
// currently ignored
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envStartedInstanceName:
// currently ignored
// old value, should be 0
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
// instance name
if _, err = readBVarChar(r); err != nil {
badStreamPanic(err)
}
case envRouting:
// RoutingData message is:
// ValueLength USHORT
// Protocol (TCP = 0) BYTE
// ProtocolProperty (new port) USHORT
// AlternateServer US_VARCHAR
_, err := readUshort(r)
if err != nil {
badStreamPanic(err)
}
protocol, err := readByte(r)
if err != nil || protocol != 0 {
badStreamPanic(err)
}
newPort, err := readUshort(r)
if err != nil {
badStreamPanic(err)
}
newServer, err := readUsVarChar(r)
if err != nil {
badStreamPanic(err)
}
// consume the OLDVALUE = %x00 %x00
_, err = readUshort(r)
if err != nil {
badStreamPanic(err)
}
sess.routedServer = newServer
sess.routedPort = newPort
default:
// ignore rest of records because we don't know how to skip those
sess.log.Printf("WARN: Unknown ENVCHANGE record detected with type id = %d\n", envtype)
return
}
}
}
// http://msdn.microsoft.com/en-us/library/dd358180.aspx
func parseReturnStatus(r *tdsBuffer) ReturnStatus {
return ReturnStatus(r.int32())
}
func parseOrder(r *tdsBuffer) (res orderStruct) {
len := int(r.uint16())
res.ColIds = make([]uint16, len/2)
for i := 0; i < len/2; i++ {
res.ColIds[i] = r.uint16()
}
return res
}
// https://msdn.microsoft.com/en-us/library/dd340421.aspx
func parseDone(r *tdsBuffer) (res doneStruct) {
res.Status = r.uint16()
res.CurCmd = r.uint16()
res.RowCount = r.uint64()
return res
}
// https://msdn.microsoft.com/en-us/library/dd340553.aspx
func parseDoneInProc(r *tdsBuffer) (res doneInProcStruct) {
res.Status = r.uint16()
res.CurCmd = r.uint16()
res.RowCount = r.uint64()
return res
}
type sspiMsg []byte
func parseSSPIMsg(r *tdsBuffer) sspiMsg {
size := r.uint16()
buf := make([]byte, size)
r.ReadFull(buf)
return sspiMsg(buf)
}
type fedAuthInfoStruct struct {
STSURL string
ServerSPN string
}
type fedAuthInfoOpt struct {
fedAuthInfoID byte
dataLength, dataOffset uint32
}
func parseFedAuthInfo(r *tdsBuffer) fedAuthInfoStruct {
size := r.uint32()
var STSURL, SPN string
var err error
// Each fedAuthInfoOpt is one byte to indicate the info ID,
// then a four byte offset and a four byte length.
count := r.uint32()
offset := uint32(4)
opts := make([]fedAuthInfoOpt, count)
for i := uint32(0); i < count; i++ {
fedAuthInfoID := r.byte()
dataLength := r.uint32()
dataOffset := r.uint32()
offset += 1 + 4 + 4
opts[i] = fedAuthInfoOpt{
fedAuthInfoID: fedAuthInfoID,
dataLength: dataLength,
dataOffset: dataOffset,
}
}
data := make([]byte, size-offset)
r.ReadFull(data)
for i := uint32(0); i < count; i++ {
if opts[i].dataOffset < offset {
badStreamPanicf("Fed auth info opt stated data offset %d is before data begins in packet at %d",
opts[i].dataOffset, offset)
// returns via panic
}
if opts[i].dataOffset+opts[i].dataLength > size {
badStreamPanicf("Fed auth info opt stated data length %d added to stated offset exceeds size of packet %d",
opts[i].dataOffset+opts[i].dataLength, size)
// returns via panic
}
optData := data[opts[i].dataOffset-offset : opts[i].dataOffset-offset+opts[i].dataLength]
switch opts[i].fedAuthInfoID {
case fedAuthInfoSTSURL:
STSURL, err = ucs22str(optData)
case fedAuthInfoSPN:
SPN, err = ucs22str(optData)
default:
err = fmt.Errorf("Unexpected fed auth info opt ID %d", int(opts[i].fedAuthInfoID))
}
if err != nil {
badStreamPanic(err)
}
}
return fedAuthInfoStruct{
STSURL: STSURL,
ServerSPN: SPN,
}
}
type loginAckStruct struct {
Interface uint8
TDSVersion uint32
ProgName string
ProgVer uint32
}
func parseLoginAck(r *tdsBuffer) loginAckStruct {
size := r.uint16()
buf := make([]byte, size)
r.ReadFull(buf)
var res loginAckStruct
res.Interface = buf[0]
res.TDSVersion = binary.BigEndian.Uint32(buf[1:])
prognamelen := buf[1+4]
var err error
if res.ProgName, err = ucs22str(buf[1+4+1 : 1+4+1+prognamelen*2]); err != nil {
badStreamPanic(err)
}
res.ProgVer = binary.BigEndian.Uint32(buf[size-4:])
return res
}
// https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-tds/2eb82f8e-11f0-46dc-b42d-27302fa4701a
type fedAuthAckStruct struct {
Nonce []byte
Signature []byte
}
func parseFeatureExtAck(r *tdsBuffer) map[byte]interface{} {
ack := map[byte]interface{}{}
for feature := r.byte(); feature != featExtTERMINATOR; feature = r.byte() {
length := r.uint32()
switch feature {
case featExtFEDAUTH:
// In theory we need to know the federated authentication library to
// know how to parse, but the alternatives provide compatible structures.
fedAuthAck := fedAuthAckStruct{}
if length >= 32 {
fedAuthAck.Nonce = make([]byte, 32)
r.ReadFull(fedAuthAck.Nonce)
length -= 32
}
if length >= 32 {
fedAuthAck.Signature = make([]byte, 32)
r.ReadFull(fedAuthAck.Signature)
length -= 32
}
ack[feature] = fedAuthAck
}
// Skip unprocessed bytes
if length > 0 {
io.CopyN(ioutil.Discard, r, int64(length))
}
}
return ack
}
// http://msdn.microsoft.com/en-us/library/dd357363.aspx
func parseColMetadata72(r *tdsBuffer) (columns []columnStruct) {
count := r.uint16()
if count == 0xffff {
// no metadata is sent
return nil
}
columns = make([]columnStruct, count)
for i := range columns {
column := &columns[i]
column.UserType = r.uint32()
column.Flags = r.uint16()
// parsing TYPE_INFO structure
column.ti = readTypeInfo(r)
column.ColName = r.BVarChar()
}
return columns
}
// http://msdn.microsoft.com/en-us/library/dd357254.aspx
func parseRow(r *tdsBuffer, columns []columnStruct, row []interface{}) {
for i, column := range columns {
row[i] = column.ti.Reader(&column.ti, r)
}
}
// http://msdn.microsoft.com/en-us/library/dd304783.aspx
func parseNbcRow(r *tdsBuffer, columns []columnStruct, row []interface{}) {
bitlen := (len(columns) + 7) / 8
pres := make([]byte, bitlen)
r.ReadFull(pres)
for i, col := range columns {
if pres[i/8]&(1<<(uint(i)%8)) != 0 {
row[i] = nil
continue
}
row[i] = col.ti.Reader(&col.ti, r)
}
}
// http://msdn.microsoft.com/en-us/library/dd304156.aspx
func parseError72(r *tdsBuffer) (res Error) {
length := r.uint16()
_ = length // ignore length
res.Number = r.int32()
res.State = r.byte()
res.Class = r.byte()
res.Message = r.UsVarChar()
res.ServerName = r.BVarChar()
res.ProcName = r.BVarChar()
res.LineNo = r.int32()
return
}
// http://msdn.microsoft.com/en-us/library/dd304156.aspx
func parseInfo(r *tdsBuffer) (res Error) {
length := r.uint16()
_ = length // ignore length
res.Number = r.int32()
res.State = r.byte()
res.Class = r.byte()
res.Message = r.UsVarChar()
res.ServerName = r.BVarChar()
res.ProcName = r.BVarChar()
res.LineNo = r.int32()
return
}
// https://msdn.microsoft.com/en-us/library/dd303881.aspx
func parseReturnValue(r *tdsBuffer) (nv namedValue) {
/*
ParamOrdinal
ParamName
Status
UserType
Flags
TypeInfo
CryptoMetadata
Value
*/
r.uint16()
nv.Name = r.BVarChar()
r.byte()
r.uint32() // UserType (uint16 prior to 7.2)
r.uint16()
ti := readTypeInfo(r)
nv.Value = ti.Reader(&ti, r)
return
}
func processSingleResponse(sess *tdsSession, ch chan tokenStruct, outs map[string]interface{}) {
defer func() {
if err := recover(); err != nil {
if sess.logFlags&logErrors != 0 {
sess.log.Printf("ERROR: Intercepted panic %v", err)
}
ch <- err
}
close(ch)
}()
packet_type, err := sess.buf.BeginRead()
if err != nil {
if sess.logFlags&logErrors != 0 {
sess.log.Printf("ERROR: BeginRead failed %v", err)
}
ch <- err
return
}
if packet_type != packReply {
badStreamPanic(fmt.Errorf("unexpected packet type in reply: got %v, expected %v", packet_type, packReply))
}
var columns []columnStruct
errs := make([]Error, 0, 5)
for tokens := 0; ; tokens += 1 {
token := token(sess.buf.byte())
if sess.logFlags&logDebug != 0 {
sess.log.Printf("got token %v", token)
}
switch token {
case tokenSSPI:
ch <- parseSSPIMsg(sess.buf)
return
case tokenFedAuthInfo:
ch <- parseFedAuthInfo(sess.buf)
return
case tokenReturnStatus:
returnStatus := parseReturnStatus(sess.buf)
ch <- returnStatus
case tokenLoginAck:
loginAck := parseLoginAck(sess.buf)
ch <- loginAck
case tokenFeatureExtAck:
featureExtAck := parseFeatureExtAck(sess.buf)
ch <- featureExtAck
case tokenOrder:
order := parseOrder(sess.buf)
ch <- order
case tokenDoneInProc:
done := parseDoneInProc(sess.buf)
if sess.logFlags&logRows != 0 && done.Status&doneCount != 0 {
sess.log.Printf("(%d row(s) affected)\n", done.RowCount)
}
ch <- done
case tokenDone, tokenDoneProc:
done := parseDone(sess.buf)
done.errors = errs
if sess.logFlags&logDebug != 0 {
sess.log.Printf("got DONE or DONEPROC status=%d", done.Status)
}
if done.Status&doneSrvError != 0 {
ch <- errors.New("SQL Server had internal error")
return
}
if sess.logFlags&logRows != 0 && done.Status&doneCount != 0 {
sess.log.Printf("(%d row(s) affected)\n", done.RowCount)
}
ch <- done
if done.Status&doneMore == 0 {
return
}
case tokenColMetadata:
columns = parseColMetadata72(sess.buf)
ch <- columns
case tokenRow:
row := make([]interface{}, len(columns))
parseRow(sess.buf, columns, row)
ch <- row
case tokenNbcRow:
row := make([]interface{}, len(columns))
parseNbcRow(sess.buf, columns, row)
ch <- row
case tokenEnvChange:
processEnvChg(sess)
case tokenError:
err := parseError72(sess.buf)
if sess.logFlags&logDebug != 0 {
sess.log.Printf("got ERROR %d %s", err.Number, err.Message)
}
errs = append(errs, err)
if sess.logFlags&logErrors != 0 {
sess.log.Println(err.Message)
}
case tokenInfo:
info := parseInfo(sess.buf)
if sess.logFlags&logDebug != 0 {
sess.log.Printf("got INFO %d %s", info.Number, info.Message)
}
if sess.logFlags&logMessages != 0 {
sess.log.Println(info.Message)
}
case tokenReturnValue:
nv := parseReturnValue(sess.buf)
if len(nv.Name) > 0 {
name := nv.Name[1:] // Remove the leading "@".
if ov, has := outs[name]; has {
err = scanIntoOut(name, nv.Value, ov)
if err != nil {
fmt.Println("scan error", err)
ch <- err
}
}
}
default:
badStreamPanic(fmt.Errorf("unknown token type returned: %v", token))
}
}
}
type tokenProcessor struct {
tokChan chan tokenStruct
ctx context.Context
sess *tdsSession
outs map[string]interface{}
lastRow []interface{}
rowCount int64
firstError error
}
func startReading(sess *tdsSession, ctx context.Context, outs map[string]interface{}) *tokenProcessor {
tokChan := make(chan tokenStruct, 5)
go processSingleResponse(sess, tokChan, outs)
return &tokenProcessor{
tokChan: tokChan,
ctx: ctx,
sess: sess,
outs: outs,
}
}
func (t *tokenProcessor) iterateResponse() error {
for {
tok, err := t.nextToken()
if err == nil {
if tok == nil {
return t.firstError
} else {
switch token := tok.(type) {
case []columnStruct:
t.sess.columns = token
case []interface{}:
t.lastRow = token
case doneInProcStruct:
if token.Status&doneCount != 0 {
t.rowCount += int64(token.RowCount)
}
case doneStruct:
if token.Status&doneCount != 0 {
t.rowCount += int64(token.RowCount)
}
if token.isError() && t.firstError == nil {
t.firstError = token.getError()
}
case ReturnStatus:
t.sess.setReturnStatus(token)
/*case error:
if resultError == nil {
resultError = token
}*/
}
}
} else {
return err
}
}
}
func (t tokenProcessor) nextToken() (tokenStruct, error) {
// we do this separate non-blocking check on token channel to
// prioritize it over cancellation channel
select {
case tok, more := <-t.tokChan:
err, more := tok.(error)
if more {
// this is an error and not a token
return nil, err
} else {
return tok, nil
}
default:
// there are no tokens on the channel, will need to wait
}
select {
case tok, more := <-t.tokChan:
if more {
err, ok := tok.(error)
if ok {
// this is an error and not a token
return nil, err
} else {
return tok, nil
}
} else {
// completed reading response
return nil, nil
}
case <-t.ctx.Done():
if err := sendAttention(t.sess.buf); err != nil {
// unable to send attention, current connection is bad
// notify caller and close channel
return nil, err
}
// now the server should send cancellation confirmation
// it is possible that we already received full response
// just before we sent cancellation request
// in this case current response would not contain confirmation
// and we would need to read one more response
// first lets finish reading current response and look
// for confirmation in it
if readCancelConfirmation(t.tokChan) {
// we got confirmation in current response
return nil, t.ctx.Err()
}
// we did not get cancellation confirmation in the current response
// read one more response, it must be there
t.tokChan = make(chan tokenStruct, 5)
go processSingleResponse(t.sess, t.tokChan, t.outs)
if readCancelConfirmation(t.tokChan) {
return nil, t.ctx.Err()
}
// we did not get cancellation confirmation, something is not
// right, this connection is not usable anymore
return nil, errors.New("did not get cancellation confirmation from the server")
}
}
func readCancelConfirmation(tokChan chan tokenStruct) bool {
for tok := range tokChan {
switch tok := tok.(type) {
default:
// just skip token
case doneStruct:
if tok.Status&doneAttn != 0 {
// got cancellation confirmation, exit
return true
}
}
}
return false
}