forked from plgd-dev/go-coap
/
sessionbase.go
159 lines (136 loc) · 3.98 KB
/
sessionbase.go
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package coap
import (
"context"
"fmt"
"log"
"sync"
"sync/atomic"
"time"
)
type sessionResp struct {
ch chan *Request // channel must have size 1 for non-blocking write to channel
}
type sessionBase struct {
srv *Server
handler *TokenHandler
sequence uint64
blockWiseTransfer bool
blockWiseTransferSzx uint32 //BlockWiseSzx
mapPairs map[[MaxTokenSize]byte]map[uint16]*sessionResp //storage of channel Message
mapPairsLock sync.Mutex //to sync add remove token
}
func (s *sessionBase) blockWiseSzx() BlockWiseSzx {
return BlockWiseSzx(atomic.LoadUint32(&s.blockWiseTransferSzx))
}
func (s *sessionBase) setBlockWiseSzx(szx BlockWiseSzx) {
atomic.StoreUint32(&s.blockWiseTransferSzx, uint32(szx))
}
func (s *sessionBase) Sequence() uint64 {
return atomic.AddUint64(&s.sequence, 1)
}
func (s *sessionBase) blockWiseMaxPayloadSize(peer BlockWiseSzx) (int, BlockWiseSzx) {
szx := s.blockWiseSzx()
if peer < szx {
return szxToBytes[peer], peer
}
return szxToBytes[szx], szx
}
func (s *sessionBase) TokenHandler() *TokenHandler {
return s.handler
}
func (s *sessionBase) exchangeFunc(req Message, writeTimeout, readTimeout time.Duration, pairChan *sessionResp, write func(msg Message, timeout time.Duration) error) (Message, error) {
err := write(req, writeTimeout)
if err != nil {
return nil, err
}
select {
case resp := <-pairChan.ch:
return resp.Msg, nil
case <-time.After(readTimeout):
return nil, ErrTimeout
}
}
func (s *sessionBase) newSessionResp(token []byte, messageID uint16) (*sessionResp, error) {
var pairToken [MaxTokenSize]byte
copy(pairToken[:], token)
//register msgid to token
pairChan := &sessionResp{make(chan *Request, 1)}
s.mapPairsLock.Lock()
defer s.mapPairsLock.Unlock()
if s.mapPairs[pairToken] == nil {
s.mapPairs[pairToken] = make(map[uint16]*sessionResp)
}
if s.mapPairs[pairToken][messageID] != nil {
return nil, ErrTokenAlreadyExist
}
s.mapPairs[pairToken][messageID] = pairChan
return pairChan, nil
}
func (s *sessionBase) getSessionResp(token []byte, messageID uint16) *sessionResp {
var pairToken [MaxTokenSize]byte
copy(pairToken[:], token)
s.mapPairsLock.Lock()
defer s.mapPairsLock.Unlock()
if m, ok := s.mapPairs[pairToken]; ok {
if p, ok := m[messageID]; ok {
return p
}
}
return nil
}
func (s *sessionBase) removeSessionResp(token []byte, messageID uint16) {
var pairToken [MaxTokenSize]byte
copy(pairToken[:], token)
s.mapPairsLock.Lock()
defer s.mapPairsLock.Unlock()
delete(s.mapPairs[pairToken], messageID)
if len(s.mapPairs[pairToken]) == 0 {
delete(s.mapPairs, pairToken)
}
}
func (s *sessionBase) exchangeWithContext(ctx context.Context, req Message, writeMsgWithContext func(context.Context, Message) error) (Message, error) {
if err := validateMsg(req); err != nil {
return nil, fmt.Errorf("cannot exchange: %v", err)
}
//register msgid to token
pairChan, err := s.newSessionResp(req.Token(), req.MessageID())
if err != nil {
return nil, err
}
defer s.removeSessionResp(req.Token(), req.MessageID())
err = writeMsgWithContext(ctx, req)
if err != nil {
return nil, fmt.Errorf("cannot exchange: %v", err)
}
select {
case request := <-pairChan.ch:
return request.Msg, nil
case <-ctx.Done():
if ctx.Err() != nil {
return nil, fmt.Errorf("cannot exchange: %v", ctx.Err())
}
return nil, fmt.Errorf("cannot exchange: cancelled")
}
}
func validateMsg(msg Message) error {
if msg.Payload() != nil && msg.Option(ContentFormat) == nil {
return ErrContentFormatNotSet
}
if msg.Payload() == nil && msg.Option(ContentFormat) != nil {
return ErrInvalidPayload
}
return nil
}
func (s *sessionBase) handlePairMsg(w ResponseWriter, r *Request) bool {
//validate token
pair := s.getSessionResp(r.Msg.Token(), r.Msg.MessageID())
if pair != nil {
select {
case pair.ch <- r:
default:
log.Fatal("Exactly one message can be send to pair. This is second message.")
}
return true
}
return false
}