/usr/share/gocode/src/github.com/pkg/sftp/examples/sftp-server/main.go is in golang-github-pkg-sftp-dev 0.0~git20160930.0.4d0e916-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 | // An example SFTP server implementation using the golang SSH package.
// Serves the whole filesystem visible to the user, and has a hard-coded username and password,
// so not for real use!
package main
import (
"flag"
"fmt"
"io/ioutil"
"log"
"net"
"os"
"github.com/pkg/sftp"
"golang.org/x/crypto/ssh"
)
// Based on example server code from golang.org/x/crypto/ssh and server_standalone
func main() {
var (
readOnly bool
debugStderr bool
)
flag.BoolVar(&readOnly, "R", false, "read-only server")
flag.BoolVar(&debugStderr, "e", false, "debug to stderr")
flag.Parse()
debugStream := ioutil.Discard
if debugStderr {
debugStream = os.Stderr
}
// An SSH server is represented by a ServerConfig, which holds
// certificate details and handles authentication of ServerConns.
config := &ssh.ServerConfig{
PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
// Should use constant-time compare (or better, salt+hash) in
// a production setting.
fmt.Fprintf(debugStream, "Login: %s\n", c.User())
if c.User() == "testuser" && string(pass) == "tiger" {
return nil, nil
}
return nil, fmt.Errorf("password rejected for %q", c.User())
},
}
privateBytes, err := ioutil.ReadFile("id_rsa")
if err != nil {
log.Fatal("Failed to load private key", err)
}
private, err := ssh.ParsePrivateKey(privateBytes)
if err != nil {
log.Fatal("Failed to parse private key", err)
}
config.AddHostKey(private)
// Once a ServerConfig has been configured, connections can be
// accepted.
listener, err := net.Listen("tcp", "0.0.0.0:2022")
if err != nil {
log.Fatal("failed to listen for connection", err)
}
fmt.Printf("Listening on %v\n", listener.Addr())
nConn, err := listener.Accept()
if err != nil {
log.Fatal("failed to accept incoming connection", err)
}
// Before use, a handshake must be performed on the incoming
// net.Conn.
_, chans, reqs, err := ssh.NewServerConn(nConn, config)
if err != nil {
log.Fatal("failed to handshake", err)
}
fmt.Fprintf(debugStream, "SSH server established\n")
// The incoming Request channel must be serviced.
go ssh.DiscardRequests(reqs)
// Service the incoming Channel channel.
for newChannel := range chans {
// Channels have a type, depending on the application level
// protocol intended. In the case of an SFTP session, this is "subsystem"
// with a payload string of "<length=4>sftp"
fmt.Fprintf(debugStream, "Incoming channel: %s\n", newChannel.ChannelType())
if newChannel.ChannelType() != "session" {
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
fmt.Fprintf(debugStream, "Unknown channel type: %s\n", newChannel.ChannelType())
continue
}
channel, requests, err := newChannel.Accept()
if err != nil {
log.Fatal("could not accept channel.", err)
}
fmt.Fprintf(debugStream, "Channel accepted\n")
// Sessions have out-of-band requests such as "shell",
// "pty-req" and "env". Here we handle only the
// "subsystem" request.
go func(in <-chan *ssh.Request) {
for req := range in {
fmt.Fprintf(debugStream, "Request: %v\n", req.Type)
ok := false
switch req.Type {
case "subsystem":
fmt.Fprintf(debugStream, "Subsystem: %s\n", req.Payload[4:])
if string(req.Payload[4:]) == "sftp" {
ok = true
}
}
fmt.Fprintf(debugStream, " - accepted: %v\n", ok)
req.Reply(ok, nil)
}
}(requests)
serverOptions := []sftp.ServerOption{
sftp.WithDebug(debugStream),
}
if readOnly {
serverOptions = append(serverOptions, sftp.ReadOnly())
fmt.Fprintf(debugStream, "Read-only server\n")
} else {
fmt.Fprintf(debugStream, "Read write server\n")
}
server, err := sftp.NewServer(
channel,
serverOptions...,
)
if err != nil {
log.Fatal(err)
}
if err := server.Serve(); err != nil {
log.Fatal("sftp server completed with error:", err)
}
}
}
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