waveterm/pkg/shexec/parser.go

354 lines
9.0 KiB
Go

package shexec
import (
"bytes"
"fmt"
"io"
"regexp"
"strings"
"github.com/alessio/shellescape"
"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,
"LINENO": true,
"BASH_LINENO": true,
"BASH_REMATCH": true,
"BASH_SOURCE": true,
"BASH_SUBSHELL": 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,
"COLUMNS": true,
// we want these in our remote state object
// "EUID": true,
// "SHELLOPTS": true,
// "UID": true,
// "BASH_VERSINFO": true,
// "BASH_VERSION": true,
}
type DeclareDeclType struct {
Args string
Name string
Value string
}
var declareDeclArgsRe = regexp.MustCompile("^[aAxrifx]*$")
var bashValidIdentifierRe = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")
func (d *DeclareDeclType) Validate() error {
if len(d.Name) == 0 || !IsValidBashIdentifier(d.Name) {
return fmt.Errorf("invalid shell variable name (invalid bash identifier)")
}
if strings.Index(d.Value, "\x00") >= 0 {
return fmt.Errorf("invalid shell variable value (cannot contain 0 byte)")
}
if !declareDeclArgsRe.MatchString(d.Args) {
return fmt.Errorf("invalid shell variable type %s", shellescape.Quote(d.Args))
}
return nil
}
func (d *DeclareDeclType) Serialize() string {
return fmt.Sprintf("%s|%s=%s\x00", d.Args, d.Name, d.Value)
}
func (d *DeclareDeclType) EnvString() string {
return d.Name + "=" + d.Value
}
func (d *DeclareDeclType) DeclareStmt() string {
var argsStr string
if d.Args == "" {
argsStr = "--"
} else {
argsStr = "-" + d.Args
}
return fmt.Sprintf("declare %s %s=%s", argsStr, d.Name, shellescape.Quote(d.Value))
}
// envline should be valid
func ParseDeclLine(envLine string) *DeclareDeclType {
eqIdx := strings.Index(envLine, "=")
if eqIdx == -1 {
return nil
}
namePart := envLine[0:eqIdx]
valPart := envLine[eqIdx+1:]
pipeIdx := strings.Index(namePart, "|")
if pipeIdx == -1 {
return nil
}
return &DeclareDeclType{
Args: namePart[0:pipeIdx],
Name: namePart[pipeIdx+1:],
Value: valPart,
}
}
func DeclMapFromState(state *packet.ShellState) map[string]*DeclareDeclType {
if state == nil {
return nil
}
rtn := make(map[string]*DeclareDeclType)
vars := bytes.Split(state.ShellVars, []byte{0})
for _, varLine := range vars {
decl := ParseDeclLine(string(varLine))
if decl != nil {
rtn[decl.Name] = decl
}
}
return rtn
}
func SerializeDeclMap(declMap map[string]*DeclareDeclType) []byte {
var rtn bytes.Buffer
for _, decl := range declMap {
rtn.WriteString(decl.Serialize())
}
return rtn.Bytes()
}
func EnvMapFromState(state *packet.ShellState) map[string]string {
if state == nil {
return nil
}
rtn := make(map[string]string)
vars := bytes.Split(state.ShellVars, []byte{0})
for _, varLine := range vars {
decl := ParseDeclLine(string(varLine))
if decl != nil && decl.IsExport() {
rtn[decl.Name] = decl.Value
}
}
return rtn
}
func ShellVarMapFromState(state *packet.ShellState) map[string]string {
if state == nil {
return nil
}
rtn := make(map[string]string)
vars := bytes.Split(state.ShellVars, []byte{0})
for _, varLine := range vars {
decl := ParseDeclLine(string(varLine))
if decl != nil {
rtn[decl.Name] = decl.Value
}
}
return rtn
}
func VarDeclsFromState(state *packet.ShellState) []*DeclareDeclType {
if state == nil {
return nil
}
var rtn []*DeclareDeclType
vars := bytes.Split(state.ShellVars, []byte{0})
for _, varLine := range vars {
decl := ParseDeclLine(string(varLine))
if decl != nil {
rtn = append(rtn, decl)
}
}
return rtn
}
func IsValidBashIdentifier(s string) bool {
return bashValidIdentifierRe.MatchString(s)
}
func (d *DeclareDeclType) IsExport() bool {
return strings.Index(d.Args, "x") >= 0
}
func (d *DeclareDeclType) IsReadOnly() bool {
return strings.Index(d.Args, "r") >= 0
}
func parseDeclareStmt(stmt *syntax.Stmt, src []byte) (*DeclareDeclType, error) {
cmd := stmt.Cmd
decl, ok := cmd.(*syntax.DeclClause)
if !ok || decl.Variant.Value != "declare" || len(decl.Args) != 2 {
return nil, fmt.Errorf("invalid declare variant")
}
rtn := &DeclareDeclType{}
declArgs := decl.Args[0]
if !declArgs.Naked || len(declArgs.Value.Parts) != 1 {
return nil, fmt.Errorf("wrong number of declare args parts")
}
declArgsLit, ok := declArgs.Value.Parts[0].(*syntax.Lit)
if !ok {
return nil, fmt.Errorf("declare args is not a literal")
}
if !strings.HasPrefix(declArgsLit.Value, "-") {
return nil, fmt.Errorf("declare args not an argument (does not start with '-')")
}
if declArgsLit.Value == "--" {
rtn.Args = ""
} else {
rtn.Args = declArgsLit.Value[1:]
}
declAssign := decl.Args[1]
if declAssign.Name == nil {
return nil, fmt.Errorf("declare does not have a valid name")
}
rtn.Name = declAssign.Name.Value
if declAssign.Naked || declAssign.Index != nil || declAssign.Append {
return nil, fmt.Errorf("invalid decl format")
}
if declAssign.Value != nil {
varValueStr, err := QuotedLitToStr(declAssign.Value)
if err != nil {
return nil, fmt.Errorf("parsing declare value: %w", err)
}
rtn.Value = varValueStr
} else if declAssign.Array != nil {
rtn.Value = string(src[declAssign.Array.Pos().Offset():declAssign.Array.End().Offset()])
} else {
return nil, fmt.Errorf("invalid decl, not plain value or array")
}
if err := rtn.Validate(); err != nil {
return nil, err
}
return rtn, 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 varsBuffer bytes.Buffer
var firstParseErr error
for _, stmt := range file.Stmts {
decl, err := parseDeclareStmt(stmt, declareBytes)
if err != nil {
if firstParseErr == nil {
firstParseErr = err
}
}
if decl != nil && !NoStoreVarNames[decl.Name] {
varsBuffer.WriteString(decl.Serialize())
}
}
state.ShellVars = varsBuffer.Bytes()
if firstParseErr != nil {
state.Error = firstParseErr.Error()
}
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 = strings.TrimSpace(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]
} else if strings.HasSuffix(cwdStr, "\n") {
cwdStr = cwdStr[0 : len(cwdStr)-1]
}
rtn.Cwd = string(cwdStr)
err := parseDeclareOutput(rtn, fields[2])
if err != nil {
return nil, err
}
rtn.Aliases = strings.ReplaceAll(string(fields[3]), "\r\n", "\n")
rtn.Funcs = strings.ReplaceAll(string(fields[4]), "\r\n", "\n")
return rtn, nil
}