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grab shell vars with export vars

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This commit is contained in:
sawka 2022-10-24 21:26:39 -07:00
parent 5d6c77491f
commit 674a6ef11e
4 changed files with 222 additions and 54 deletions
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11
main-mshell.go
View File

@ -526,13 +526,14 @@ func main() {
} else if firstArg == "--version" {
fmt.Printf("mshell %s\n", base.MShellVersion)
return
} else if firstArg == "--env" {
rtnCode, err := handleEnv()
} else if firstArg == "--test-env" {
state, err := shexec.GetShellState()
if state != nil {
}
if err != nil {
fmt.Fprintf(os.Stderr, "[error] %v\n", err)
}
if rtnCode != 0 {
os.Exit(rtnCode)
os.Exit(1)
}
} else if firstArg == "--single" {
handleSingle(false)

10
pkg/packet/packet.go
View File

@ -109,10 +109,12 @@ func MakePacket(packetType string) (PacketType, error) {
}
type ShellState struct {
Cwd string `json:"cwd,omitempty"`
Env0 []byte `json:"env0,omitempty"`
Aliases string `json:"aliases,omitempty"`
Funcs string `json:"funcs,omitempty"`
Version string `json:"version,omitempty"`
Cwd string `json:"cwd,omitempty"`
ShellVars string `json:"shellvars,omitempty"`
Env0 []byte `json:"env0,omitempty"`
Aliases string `json:"aliases,omitempty"`
Funcs string `json:"funcs,omitempty"`
}
type CmdDataPacketType struct {

200
pkg/shexec/parser.go Normal file
View File

@ -0,0 +1,200 @@
package shexec
import (
"bytes"
"fmt"
"io"
"strings"
"github.com/scripthaus-dev/mshell/pkg/packet"
"mvdan.cc/sh/v3/expand"
"mvdan.cc/sh/v3/syntax"
)
type ParseEnviron struct {
Env map[string]string
}
func (e *ParseEnviron) Get(name string) expand.Variable {
val, ok := e.Env[name]
if !ok {
return expand.Variable{}
}
return expand.Variable{
Exported: true,
Kind: expand.String,
Str: val,
}
}
func (e *ParseEnviron) Each(fn func(name string, vr expand.Variable) bool) {
for key, _ := range e.Env {
rtn := fn(key, e.Get(key))
if !rtn {
break
}
}
}
func doCmdSubst(commandStr string, w io.Writer, word *syntax.CmdSubst) error {
return nil
}
func doProcSubst(w *syntax.ProcSubst) (string, error) {
return "", nil
}
func GetParserConfig(envMap map[string]string) *expand.Config {
cfg := &expand.Config{
Env: &ParseEnviron{Env: envMap},
GlobStar: false,
NullGlob: false,
NoUnset: false,
CmdSubst: func(w io.Writer, word *syntax.CmdSubst) error { return doCmdSubst("", w, word) },
ProcSubst: doProcSubst,
ReadDir: nil,
}
return cfg
}
func QuotedLitToStr(word *syntax.Word) (string, error) {
cfg := GetParserConfig(nil)
return expand.Literal(cfg, word)
}
// https://wiki.bash-hackers.org/syntax/shellvars
var NoStoreVarNames = map[string]bool{
"BASH": true,
"BASHOPTS": true,
"BASHPID": true,
"BASH_ALIASES": true,
"BASH_ARGC": true,
"BASH_ARGV": true,
"BASH_ARGV0": true,
"BASH_CMDS": true,
"BASH_COMMAND": true,
"BASH_EXECUTION_STRING": true,
"BASH_LINENO": true,
"BASH_REMATCH": true,
"BASH_SOURCE": true,
"BASH_SUBSHELL": true,
"BASH_VERSINFO": true,
"BASH_VERSION": true,
"COPROC": true,
"DIRSTACK": true,
"EPOCHREALTIME": true,
"EPOCHSECONDS": true,
"FUNCNAME": true,
"HISTCMD": true,
"OLDPWD": true,
"PIPESTATUS": true,
"PPID": true,
"PWD": true,
"RANDOM": true,
"SECONDS": true,
"SHLVL": true,
"HISTFILE": true,
"HISTFILESIZE": true,
"HISTCONTROL": true,
"HISTIGNORE": true,
"HISTSIZE": true,
"HISTTIMEFORMAT": true,
"SRANDOM": true,
}
func parseDeclareStmt(envBuffer *bytes.Buffer, varsBuffer *bytes.Buffer, stmt *syntax.Stmt, src []byte) error {
cmd := stmt.Cmd
decl, ok := cmd.(*syntax.DeclClause)
if !ok || decl.Variant.Value != "declare" || len(decl.Args) != 2 {
return fmt.Errorf("invalid declare variant")
}
declArgs := decl.Args[0]
if !declArgs.Naked || len(declArgs.Value.Parts) != 1 {
return fmt.Errorf("wrong number of declare args parts")
}
declArgLit, ok := declArgs.Value.Parts[0].(*syntax.Lit)
if !ok {
return fmt.Errorf("declare args is not a literal")
}
declArgStr := declArgLit.Value
if !strings.HasPrefix(declArgStr, "-") {
return fmt.Errorf("declare args not an argument (does not start with '-')")
}
declAssign := decl.Args[1]
if declAssign.Name == nil {
return fmt.Errorf("declare does not have a valid name")
}
varName := declAssign.Name.Value
if NoStoreVarNames[varName] {
return nil
}
if strings.Index(varName, "=") != -1 || strings.Index(varName, "\x00") != -1 {
return fmt.Errorf("invalid varname (cannot contain '=' or 0 byte)")
}
fullDeclBytes := src[decl.Pos().Offset():decl.End().Offset()]
if strings.Index(declArgStr, "x") == -1 {
// non-exported vars get written to vars as decl statements
varsBuffer.Write(fullDeclBytes)
varsBuffer.WriteRune('\n')
return nil
}
if declArgStr != "-x" {
return fmt.Errorf("can only export plain bash variables (no arrays)")
}
// exported vars are parsed into Env0 format
if declAssign.Naked || declAssign.Array != nil || declAssign.Index != nil || declAssign.Append || declAssign.Value == nil {
return fmt.Errorf("invalid variable to export")
}
varValue := declAssign.Value
varValueStr, err := QuotedLitToStr(varValue)
if err != nil {
return fmt.Errorf("parsing declare value: %w", err)
}
if strings.Index(varValueStr, "\x00") != -1 {
return fmt.Errorf("invalid export var value (cannot contain 0 byte)")
}
envBuffer.WriteString(fmt.Sprintf("%s=%s\x00", varName, varValueStr))
return nil
}
func parseDeclareOutput(state *packet.ShellState, declareBytes []byte) error {
r := bytes.NewReader(declareBytes)
parser := syntax.NewParser(syntax.Variant(syntax.LangBash))
file, err := parser.Parse(r, "aliases")
if err != nil {
return err
}
var envBuffer, varsBuffer bytes.Buffer
for _, stmt := range file.Stmts {
err = parseDeclareStmt(&envBuffer, &varsBuffer, stmt, declareBytes)
if err != nil {
// TODO where to put parse errors?
continue
}
}
state.Env0 = envBuffer.Bytes()
state.ShellVars = varsBuffer.String()
return nil
}
func ParseShellStateOutput(outputBytes []byte) (*packet.ShellState, error) {
// 5 fields: version, cwd, env/vars, aliases, funcs
fields := bytes.Split(outputBytes, []byte{0, 0})
if len(fields) != 5 {
return nil, fmt.Errorf("invalid shell state output, wrong number of fields, fields=%d", len(fields))
}
rtn := &packet.ShellState{}
rtn.Version = string(fields[0])
if strings.Index(rtn.Version, "bash") == -1 {
return nil, fmt.Errorf("invalid shell state output, only bash is supported")
}
cwdStr := string(fields[1])
if strings.HasSuffix(cwdStr, "\r\n") {
cwdStr = cwdStr[0 : len(cwdStr)-2]
}
rtn.Cwd = string(cwdStr)
parseDeclareOutput(rtn, fields[2])
rtn.Aliases = strings.ReplaceAll(string(fields[3]), "\r\n", "\n")
rtn.Funcs = strings.ReplaceAll(string(fields[4]), "\r\n", "\n")
return rtn, nil
}

55
pkg/shexec/shexec.go
View File

@ -47,6 +47,8 @@ const MaxMaxPtySize = 100 * 1024 * 1024
const GetStateTimeout = 5 * time.Second
const GetShellStateCmd = `echo bash v${BASH_VERSINFO[0]}.${BASH_VERSINFO[1]}.${BASH_VERSINFO[2]}; printf "\x00\x00"; pwd; printf "\x00\x00"; declare -p $(compgen -A variable); printf "\x00\x00"; alias -p; printf "\x00\x00"; declare -f;`
const ClientCommandFmt = `
PATH=$PATH:~/.mshell;
which mshell > /dev/null;
@ -976,7 +978,7 @@ shopt -s extglob
if pk.ReturnState {
rcFileStr += `
_scripthaus_exittrap () {
%s --env; alias -p; printf \"\\x00\\x00\"; declare -f;
` + GetShellStateCmd + `
}
trap _scripthaus_exittrap EXIT
`
@ -984,18 +986,15 @@ trap _scripthaus_exittrap EXIT
return rcFileStr
}
func makeExitTrap(fdNum int) (string, error) {
stateCmd, err := GetShellStateRedirectCommandStr(fdNum)
if err != nil {
return "", err
}
func makeExitTrap(fdNum int) string {
stateCmd := GetShellStateRedirectCommandStr(fdNum)
fmtStr := `
_scripthaus_exittrap () {
%s
}
trap _scripthaus_exittrap EXIT
`
return fmt.Sprintf(fmtStr, stateCmd), nil
return fmt.Sprintf(fmtStr, stateCmd)
}
func RunCommandSimple(pk *packet.RunPacketType, sender *packet.PacketSender, fromServer bool) (rtnShExec *ShExecType, rtnErr error) {
@ -1028,10 +1027,7 @@ func RunCommandSimple(pk *packet.RunPacketType, sender *packet.PacketSender, fro
cmd.ReturnState.FdNum = 20
rtnStateWriter = pw
defer pw.Close()
trapCmdStr, err := makeExitTrap(cmd.ReturnState.FdNum)
if err != nil {
return nil, err
}
trapCmdStr := makeExitTrap(cmd.ReturnState.FdNum)
rcFileStr += trapCmdStr
}
rcFileFdNum, err := AddRunData(pk, rcFileStr, "rcfile")
@ -1438,44 +1434,13 @@ func runSimpleCmdInPty(ecmd *exec.Cmd) ([]byte, error) {
return outputBuf.Bytes(), nil
}
func GetShellStateCommandStr() (string, error) {
execFile, err := os.Executable()
if err != nil {
return "", fmt.Errorf("cannot find local mshell executable: %w", err)
}
return fmt.Sprintf(`%s --env; alias -p; printf \"\\x00\\x00\"; declare -f`, shellescape.Quote(execFile)), nil
}
func GetShellStateRedirectCommandStr(outputFdNum int) (string, error) {
cmdStr, err := GetShellStateCommandStr()
if err != nil {
return "", err
}
return fmt.Sprintf("cat <(%s) > /dev/fd/%d", cmdStr, outputFdNum), nil
}
func ParseShellStateOutput(outputBytes []byte) (*packet.ShellState, error) {
fields := bytes.Split(outputBytes, []byte{0, 0})
if len(fields) != 4 {
return nil, fmt.Errorf("invalid shell state output, wrong number of fields, fields=%d", len(fields))
}
rtn := &packet.ShellState{}
rtn.Cwd = string(fields[0])
if len(fields[1]) > 0 {
rtn.Env0 = append(fields[1], '\x00')
}
rtn.Aliases = strings.ReplaceAll(string(fields[2]), "\r\n", "\n")
rtn.Funcs = strings.ReplaceAll(string(fields[3]), "\r\n", "\n")
return rtn, nil
func GetShellStateRedirectCommandStr(outputFdNum int) string {
return fmt.Sprintf("cat <(%s) > /dev/fd/%d", GetShellStateCmd, outputFdNum)
}
func GetShellState() (*packet.ShellState, error) {
ctx, _ := context.WithTimeout(context.Background(), GetStateTimeout)
cmdStr, err := GetShellStateCommandStr()
if err != nil {
return nil, err
}
ecmd := exec.CommandContext(ctx, "bash", "-l", "-i", "-c", cmdStr)
ecmd := exec.CommandContext(ctx, "bash", "-l", "-i", "-c", GetShellStateCmd)
outputBytes, err := runSimpleCmdInPty(ecmd)
if err != nil {
return nil, err