parse ssh commands with shlex

instead of use our bugged home made method.

Fixes #72

README.md

@@ -811,6 +811,7 @@ The **connection failed logs** can be used for integration in tools such as [Fai
 - [PipeAt](https://github.com/eikenb/pipeat)
 - [ZeroConf](https://github.com/grandcat/zeroconf)
 - [SB Admin 2](https://github.com/BlackrockDigital/startbootstrap-sb-admin-2)
+- [shlex](https://github.com/google/shlex)
 
 Some code was initially taken from [Pterodactyl sftp server](https://github.com/pterodactyl/sftp-server)
 

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/go-sql-driver/mysql v1.5.0
 	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e // indirect
 	github.com/golang/protobuf v1.3.3 // indirect
+	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/grandcat/zeroconf v1.0.0
 	github.com/lib/pq v1.3.0
 	github.com/mattn/go-sqlite3 v2.0.3+incompatible

go.sum

@@ -103,6 +103,8 @@ github.com/google/pprof v0.0.0-20181206194817-3ea8567a2e57/go.mod h1:zfwlbNMJ+OI
 github.com/google/pprof v0.0.0-20190515194954-54271f7e092f/go.mod h1:zfwlbNMJ+OItoe0UupaVj+oy1omPYYDuagoSzA8v9mc=
 github.com/google/pprof v0.0.0-20191218002539-d4f498aebedc/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
 github.com/googleapis/gax-go/v2 v2.0.5 h1:sjZBwGj9Jlw33ImPtvFviGYvseOtDM7hkSKB7+Tv3SM=
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=

sftpd/internal_test.go

@@ -606,7 +606,7 @@ func TestSSHCommandPath(t *testing.T) {
 }
 
 func TestSSHParseCommandPayload(t *testing.T) {
-	cmd := "command -a  -f  some\\ spaces\\ \\ .txt"
+	cmd := "command -a  -f  /ab\\ à/some\\ spaces\\ \\ \\(\\).txt"
 	name, args, _ := parseCommandPayload(cmd)
 	if name != "command" {
 		t.Errorf("unexpected command: %v", name)
@@ -614,9 +614,13 @@ func TestSSHParseCommandPayload(t *testing.T) {
 	if len(args) != 3 {
 		t.Errorf("unexpected number of arguments %v/3", len(args))
 	}
-	if !utils.IsStringInSlice("some spaces  .txt", args) {
+	if args[2] != "/ab à/some spaces  ().txt" {
 		t.Errorf("command parsing error, expected arguments not found: %v", args)
 	}
+	_, _, err := parseCommandPayload("")
+	if err == nil {
+		t.Error("parsing invalid command must fail")
+	}
 }
 
 func TestSSHCommandErrors(t *testing.T) {

sftpd/ssh_cmd.go

@@ -22,6 +22,7 @@ import (
 	"github.com/drakkan/sftpgo/metrics"
 	"github.com/drakkan/sftpgo/utils"
 	"github.com/drakkan/sftpgo/vfs"
+	"github.com/google/shlex"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -45,11 +46,11 @@ type systemCommand struct {
 func processSSHCommand(payload []byte, connection *Connection, channel ssh.Channel, enabledSSHCommands []string) bool {
 	var msg sshSubsystemExecMsg
 	if err := ssh.Unmarshal(payload, &msg); err == nil {
-		name, args, err := parseCommandPayload(strings.TrimSpace(msg.Command))
-		connection.Log(logger.LevelDebug, logSenderSSH, "new ssh command: %#v args: %v user: %v, error: %v",
-			name, args, connection.User.Username, err)
+		name, args, err := parseCommandPayload(msg.Command)
+		connection.Log(logger.LevelDebug, logSenderSSH, "new ssh command: %#v args: %v num args: %v user: %v, error: %v",
+			name, args, len(args), connection.User.Username, err)
 		if err == nil && utils.IsStringInSlice(name, enabledSSHCommands) {
-			connection.command = fmt.Sprintf("%v %v", name, strings.Join(args, " "))
+			connection.command = msg.Command
 			if name == "scp" && len(args) >= 2 {
 				connection.protocol = protocolSCP
 				connection.channel = channel
@@ -421,17 +422,15 @@ func computeHashForFile(hasher hash.Hash, path string) (string, error) {
 }
 
 func parseCommandPayload(command string) (string, []string, error) {
-	parts := strings.Split(strings.ReplaceAll(command, "\\ ", "\\"), " ")
+	parts, err := shlex.Split(command)
+	if err == nil && len(parts) == 0 {
+		err = fmt.Errorf("invalid command: %#v", command)
+	}
+	if err != nil {
+		return "", []string{}, err
+	}
 	if len(parts) < 2 {
 		return parts[0], []string{}, nil
 	}
-	args := []string{}
-	for _, arg := range parts[1:] {
-		parsed := strings.TrimSpace(strings.ReplaceAll(arg, "\\", " "))
-		if len(parsed) == 0 {
-			continue
-		}
-		args = append(args, parsed)
-	}
-	return parts[0], args, nil
+	return parts[0], parts[1:], nil
 }