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|
package sftp
/*
Imported from: https://github.com/pkg/sftp
*/
import (
"encoding"
"sort"
"sync"
)
// The goal of the packetManager is to keep the outgoing packets in the same
// order as the incoming as is requires by section 7 of the RFC.
type packetManager struct {
requests chan orderedPacket
responses chan orderedPacket
fini chan struct{}
incoming orderedPackets
outgoing orderedPackets
sender packetSender // connection object
working *sync.WaitGroup
packetCount uint32
// it is not nil if the allocator is enabled
alloc *allocator
}
type packetSender interface {
sendPacket(encoding.BinaryMarshaler) error
}
func newPktMgr(sender packetSender) *packetManager {
s := &packetManager{
requests: make(chan orderedPacket, SftpServerWorkerCount),
responses: make(chan orderedPacket, SftpServerWorkerCount),
fini: make(chan struct{}),
incoming: make([]orderedPacket, 0, SftpServerWorkerCount),
outgoing: make([]orderedPacket, 0, SftpServerWorkerCount),
sender: sender,
working: &sync.WaitGroup{},
}
go s.controller()
return s
}
//// packet ordering
func (s *packetManager) newOrderID() uint32 {
s.packetCount++
return s.packetCount
}
// returns the next orderID without incrementing it.
// This is used before receiving a new packet, with the allocator enabled, to associate
// the slice allocated for the received packet with the orderID that will be used to mark
// the allocated slices for reuse once the request is served
func (s *packetManager) getNextOrderID() uint32 {
return s.packetCount + 1
}
type orderedRequest struct {
requestPacket
orderid uint32
}
func (s *packetManager) newOrderedRequest(p requestPacket) orderedRequest {
return orderedRequest{requestPacket: p, orderid: s.newOrderID()}
}
func (p orderedRequest) orderID() uint32 { return p.orderid }
func (p orderedRequest) setOrderID(oid uint32) { p.orderid = oid }
type orderedResponse struct {
responsePacket
orderid uint32
}
func (s *packetManager) newOrderedResponse(p responsePacket, id uint32,
) orderedResponse {
return orderedResponse{responsePacket: p, orderid: id}
}
func (p orderedResponse) orderID() uint32 { return p.orderid }
func (p orderedResponse) setOrderID(oid uint32) { p.orderid = oid }
type orderedPacket interface {
id() uint32
orderID() uint32
}
type orderedPackets []orderedPacket
func (o orderedPackets) Sort() {
sort.Slice(o, func(i, j int) bool {
return o[i].orderID() < o[j].orderID()
})
}
//// packet registry
// register incoming packets to be handled
func (s *packetManager) incomingPacket(pkt orderedRequest) {
s.working.Add(1)
s.requests <- pkt
}
// register outgoing packets as being ready
func (s *packetManager) readyPacket(pkt orderedResponse) {
s.responses <- pkt
s.working.Done()
}
// shut down packetManager controller
func (s *packetManager) close() {
// pause until current packets are processed
s.working.Wait()
close(s.fini)
}
// Passed a worker function, returns a channel for incoming packets.
// Keep process packet responses in the order they are received while
// maximizing throughput of file transfers.
func (s *packetManager) workerChan(runWorker func(chan orderedRequest),
) chan orderedRequest {
// multiple workers for faster read/writes
rwChan := make(chan orderedRequest, SftpServerWorkerCount)
for i := 0; i < SftpServerWorkerCount; i++ {
runWorker(rwChan)
}
// single worker to enforce sequential processing of everything else
cmdChan := make(chan orderedRequest)
runWorker(cmdChan)
pktChan := make(chan orderedRequest, SftpServerWorkerCount)
go func() {
for pkt := range pktChan {
switch pkt.requestPacket.(type) {
case *sshFxpReadPacket, *sshFxpWritePacket:
s.incomingPacket(pkt)
rwChan <- pkt
continue
case *sshFxpClosePacket:
// wait for reads/writes to finish when file is closed
// incomingPacket() call must occur after this
s.working.Wait()
}
s.incomingPacket(pkt)
// all non-RW use sequential cmdChan
cmdChan <- pkt
}
close(rwChan)
close(cmdChan)
s.close()
}()
return pktChan
}
// process packets
func (s *packetManager) controller() {
for {
select {
case pkt := <-s.requests:
debug("incoming id (oid): %v (%v)", pkt.id(), pkt.orderID())
s.incoming = append(s.incoming, pkt)
s.incoming.Sort()
case pkt := <-s.responses:
debug("outgoing id (oid): %v (%v)", pkt.id(), pkt.orderID())
s.outgoing = append(s.outgoing, pkt)
s.outgoing.Sort()
case <-s.fini:
return
}
s.maybeSendPackets()
}
}
// send as many packets as are ready
func (s *packetManager) maybeSendPackets() {
for {
if len(s.outgoing) == 0 || len(s.incoming) == 0 {
debug("break! -- outgoing: %v; incoming: %v",
len(s.outgoing), len(s.incoming))
break
}
out := s.outgoing[0]
in := s.incoming[0]
// debug("incoming: %v", ids(s.incoming))
// debug("outgoing: %v", ids(s.outgoing))
if in.orderID() == out.orderID() {
debug("Sending packet: %v", out.id())
s.sender.sendPacket(out.(encoding.BinaryMarshaler))
if s.alloc != nil {
// mark for reuse the slices allocated for this request
s.alloc.ReleasePages(in.orderID())
}
// pop off heads
copy(s.incoming, s.incoming[1:]) // shift left
s.incoming[len(s.incoming)-1] = nil // clear last
s.incoming = s.incoming[:len(s.incoming)-1] // remove last
copy(s.outgoing, s.outgoing[1:]) // shift left
s.outgoing[len(s.outgoing)-1] = nil // clear last
s.outgoing = s.outgoing[:len(s.outgoing)-1] // remove last
} else {
break
}
}
}
// func oids(o []orderedPacket) []uint32 {
// res := make([]uint32, 0, len(o))
// for _, v := range o {
// res = append(res, v.orderId())
// }
// return res
// }
// func ids(o []orderedPacket) []uint32 {
// res := make([]uint32, 0, len(o))
// for _, v := range o {
// res = append(res, v.id())
// }
// return res
// }
|
