forked from TrueCloudLab/restic
131 lines
3.7 KiB
Go
131 lines
3.7 KiB
Go
// An example SFTP server implementation using the golang SSH package.
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// Serves the whole filesystem visible to the user, and has a hard-coded username and password,
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// so not for real use!
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package main
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import (
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"net"
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"os"
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"github.com/pkg/sftp"
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"golang.org/x/crypto/ssh"
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)
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// Based on example server code from golang.org/x/crypto/ssh and server_standalone
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func main() {
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var (
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readOnly bool
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debugStderr bool
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)
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flag.BoolVar(&readOnly, "R", false, "read-only server")
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flag.BoolVar(&debugStderr, "e", false, "debug to stderr")
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flag.Parse()
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debugStream := ioutil.Discard
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if debugStderr {
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debugStream = os.Stderr
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}
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// An SSH server is represented by a ServerConfig, which holds
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// certificate details and handles authentication of ServerConns.
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config := &ssh.ServerConfig{
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PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
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// Should use constant-time compare (or better, salt+hash) in
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// a production setting.
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fmt.Fprintf(debugStream, "Login: %s\n", c.User())
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if c.User() == "testuser" && string(pass) == "tiger" {
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return nil, nil
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}
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return nil, fmt.Errorf("password rejected for %q", c.User())
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},
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}
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privateBytes, err := ioutil.ReadFile("id_rsa")
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if err != nil {
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log.Fatal("Failed to load private key", err)
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}
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private, err := ssh.ParsePrivateKey(privateBytes)
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if err != nil {
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log.Fatal("Failed to parse private key", err)
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}
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config.AddHostKey(private)
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// Once a ServerConfig has been configured, connections can be
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// accepted.
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listener, err := net.Listen("tcp", "0.0.0.0:2022")
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if err != nil {
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log.Fatal("failed to listen for connection", err)
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}
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fmt.Printf("Listening on %v\n", listener.Addr())
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nConn, err := listener.Accept()
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if err != nil {
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log.Fatal("failed to accept incoming connection", err)
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}
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// Before use, a handshake must be performed on the incoming net.Conn.
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sconn, chans, reqs, err := ssh.NewServerConn(nConn, config)
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if err != nil {
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log.Fatal("failed to handshake", err)
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}
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log.Println("login detected:", sconn.User())
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fmt.Fprintf(debugStream, "SSH server established\n")
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// The incoming Request channel must be serviced.
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go ssh.DiscardRequests(reqs)
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// Service the incoming Channel channel.
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for newChannel := range chans {
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// Channels have a type, depending on the application level
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// protocol intended. In the case of an SFTP session, this is "subsystem"
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// with a payload string of "<length=4>sftp"
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fmt.Fprintf(debugStream, "Incoming channel: %s\n", newChannel.ChannelType())
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if newChannel.ChannelType() != "session" {
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newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
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fmt.Fprintf(debugStream, "Unknown channel type: %s\n", newChannel.ChannelType())
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continue
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}
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channel, requests, err := newChannel.Accept()
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if err != nil {
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log.Fatal("could not accept channel.", err)
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}
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fmt.Fprintf(debugStream, "Channel accepted\n")
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// Sessions have out-of-band requests such as "shell",
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// "pty-req" and "env". Here we handle only the
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// "subsystem" request.
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go func(in <-chan *ssh.Request) {
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for req := range in {
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fmt.Fprintf(debugStream, "Request: %v\n", req.Type)
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ok := false
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switch req.Type {
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case "subsystem":
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fmt.Fprintf(debugStream, "Subsystem: %s\n", req.Payload[4:])
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if string(req.Payload[4:]) == "sftp" {
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ok = true
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}
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}
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fmt.Fprintf(debugStream, " - accepted: %v\n", ok)
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req.Reply(ok, nil)
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}
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}(requests)
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root := sftp.InMemHandler()
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server := sftp.NewRequestServer(channel, root)
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if err := server.Serve(); err == io.EOF {
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server.Close()
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log.Print("sftp client exited session.")
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} else if err != nil {
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log.Fatal("sftp server completed with error:", err)
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}
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}
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}
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