| package sftp |
| |
| import ( |
| "encoding" |
| "io" |
| "path" |
| "path/filepath" |
| "strconv" |
| "sync" |
| "syscall" |
| |
| "github.com/pkg/errors" |
| ) |
| |
| var maxTxPacket uint32 = 1 << 15 |
| |
| type handleHandler func(string) string |
| |
| // Handlers contains the 4 SFTP server request handlers. |
| type Handlers struct { |
| FileGet FileReader |
| FilePut FileWriter |
| FileCmd FileCmder |
| FileList FileLister |
| } |
| |
| // RequestServer abstracts the sftp protocol with an http request-like protocol |
| type RequestServer struct { |
| *serverConn |
| Handlers Handlers |
| pktMgr *packetManager |
| openRequests map[string]*Request |
| openRequestLock sync.RWMutex |
| handleCount int |
| } |
| |
| // NewRequestServer creates/allocates/returns new RequestServer. |
| // Normally there there will be one server per user-session. |
| func NewRequestServer(rwc io.ReadWriteCloser, h Handlers) *RequestServer { |
| svrConn := &serverConn{ |
| conn: conn{ |
| Reader: rwc, |
| WriteCloser: rwc, |
| }, |
| } |
| return &RequestServer{ |
| serverConn: svrConn, |
| Handlers: h, |
| pktMgr: newPktMgr(svrConn), |
| openRequests: make(map[string]*Request), |
| } |
| } |
| |
| // New Open packet/Request |
| func (rs *RequestServer) nextRequest(r *Request) string { |
| rs.openRequestLock.Lock() |
| defer rs.openRequestLock.Unlock() |
| rs.handleCount++ |
| handle := strconv.Itoa(rs.handleCount) |
| rs.openRequests[handle] = r |
| return handle |
| } |
| |
| // Returns Request from openRequests, bool is false if it is missing |
| // If the method is different, save/return a new Request w/ that Method. |
| // |
| // The Requests in openRequests work essentially as open file descriptors that |
| // you can do different things with. What you are doing with it are denoted by |
| // the first packet of that type (read/write/etc). We create a new Request when |
| // it changes to set the request.Method attribute in a thread safe way. |
| func (rs *RequestServer) getRequest(handle, method string) (*Request, bool) { |
| rs.openRequestLock.RLock() |
| r, ok := rs.openRequests[handle] |
| rs.openRequestLock.RUnlock() |
| if !ok || r.Method == method { |
| return r, ok |
| } |
| // if we make it here we need to replace the request |
| rs.openRequestLock.Lock() |
| defer rs.openRequestLock.Unlock() |
| r, ok = rs.openRequests[handle] |
| if !ok || r.Method == method { // re-check needed b/c lock race |
| return r, ok |
| } |
| r = &Request{Method: method, Filepath: r.Filepath, state: r.state} |
| rs.openRequests[handle] = r |
| return r, ok |
| } |
| |
| func (rs *RequestServer) closeRequest(handle string) error { |
| rs.openRequestLock.Lock() |
| defer rs.openRequestLock.Unlock() |
| if r, ok := rs.openRequests[handle]; ok { |
| delete(rs.openRequests, handle) |
| return r.close() |
| } |
| return syscall.EBADF |
| } |
| |
| // Close the read/write/closer to trigger exiting the main server loop |
| func (rs *RequestServer) Close() error { return rs.conn.Close() } |
| |
| // Serve requests for user session |
| func (rs *RequestServer) Serve() error { |
| var wg sync.WaitGroup |
| runWorker := func(ch requestChan) { |
| wg.Add(1) |
| go func() { |
| defer wg.Done() |
| if err := rs.packetWorker(ch); err != nil { |
| rs.conn.Close() // shuts down recvPacket |
| } |
| }() |
| } |
| pktChan := rs.pktMgr.workerChan(runWorker) |
| |
| var err error |
| var pkt requestPacket |
| var pktType uint8 |
| var pktBytes []byte |
| for { |
| pktType, pktBytes, err = rs.recvPacket() |
| if err != nil { |
| break |
| } |
| |
| pkt, err = makePacket(rxPacket{fxp(pktType), pktBytes}) |
| if err != nil { |
| debug("makePacket err: %v", err) |
| rs.conn.Close() // shuts down recvPacket |
| break |
| } |
| |
| pktChan <- pkt |
| } |
| |
| close(pktChan) // shuts down sftpServerWorkers |
| wg.Wait() // wait for all workers to exit |
| |
| return err |
| } |
| |
| func (rs *RequestServer) packetWorker(pktChan chan requestPacket) error { |
| for pkt := range pktChan { |
| var rpkt responsePacket |
| switch pkt := pkt.(type) { |
| case *sshFxInitPacket: |
| rpkt = sshFxVersionPacket{sftpProtocolVersion, nil} |
| case *sshFxpClosePacket: |
| handle := pkt.getHandle() |
| rpkt = statusFromError(pkt, rs.closeRequest(handle)) |
| case *sshFxpRealpathPacket: |
| rpkt = cleanPacketPath(pkt) |
| case isOpener: |
| request := requestFromPacket(pkt) |
| handle := rs.nextRequest(request) |
| p, ok := pkt.(*sshFxpOpenPacket) |
| if ok && p.hasPflags(ssh_FXF_CREAT) { |
| request.call(rs.Handlers, pkt) |
| } |
| rpkt = sshFxpHandlePacket{pkt.id(), handle} |
| case *sshFxpFstatPacket: |
| handle := pkt.getHandle() |
| request, ok := rs.getRequest(handle, requestMethod(pkt)) |
| if !ok { |
| rpkt = statusFromError(pkt, syscall.EBADF) |
| } else { |
| request = requestFromPacket( |
| &sshFxpStatPacket{ID: pkt.id(), Path: request.Filepath}) |
| rpkt = request.call(rs.Handlers, pkt) |
| } |
| case *sshFxpFsetstatPacket: |
| handle := pkt.getHandle() |
| request, ok := rs.getRequest(handle, requestMethod(pkt)) |
| if !ok { |
| rpkt = statusFromError(pkt, syscall.EBADF) |
| } else { |
| request = requestFromPacket( |
| &sshFxpSetstatPacket{ID: pkt.id(), Path: request.Filepath, |
| Flags: pkt.Flags, Attrs: pkt.Attrs, |
| }) |
| rpkt = request.call(rs.Handlers, pkt) |
| } |
| case hasHandle: |
| handle := pkt.getHandle() |
| request, ok := rs.getRequest(handle, requestMethod(pkt)) |
| if !ok { |
| rpkt = statusFromError(pkt, syscall.EBADF) |
| } else { |
| rpkt = request.call(rs.Handlers, pkt) |
| } |
| case hasPath: |
| request := requestFromPacket(pkt) |
| rpkt = request.call(rs.Handlers, pkt) |
| default: |
| return errors.Errorf("unexpected packet type %T", pkt) |
| } |
| |
| err := rs.sendPacket(rpkt) |
| if err != nil { |
| return err |
| } |
| } |
| return nil |
| } |
| |
| func cleanPacketPath(pkt *sshFxpRealpathPacket) responsePacket { |
| path := cleanPath(pkt.getPath()) |
| return &sshFxpNamePacket{ |
| ID: pkt.id(), |
| NameAttrs: []sshFxpNameAttr{{ |
| Name: path, |
| LongName: path, |
| Attrs: emptyFileStat, |
| }}, |
| } |
| } |
| |
| // Makes sure we have a clean POSIX (/) absolute path to work with |
| func cleanPath(p string) string { |
| p = filepath.ToSlash(p) |
| if !path.IsAbs(p) { |
| p = "/" + p |
| } |
| return path.Clean(p) |
| } |
| |
| // Wrap underlying connection methods to use packetManager |
| func (rs *RequestServer) sendPacket(m encoding.BinaryMarshaler) error { |
| if pkt, ok := m.(responsePacket); ok { |
| rs.pktMgr.readyPacket(pkt) |
| } else { |
| return errors.Errorf("unexpected packet type %T", m) |
| } |
| return nil |
| } |
| |
| func (rs *RequestServer) sendError(p ider, err error) error { |
| return rs.sendPacket(statusFromError(p, err)) |
| } |