/
netrc.go
259 lines (236 loc) · 5.44 KB
/
netrc.go
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// Copyright © 2010 Fazlul Shahriar <fshahriar@gmail.com>.
// See LICENSE file for license details.
// Package netrc implements a parser for netrc file format.
//
// A netrc file usually resides in $HOME/.netrc and is traditionally used
// by the ftp(1) program to look up login information (username, password,
// etc.) of remote system(s). The file format is (loosely) described in
// this man page: http://linux.die.net/man/5/netrc .
package netrc
import (
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"unicode"
"unicode/utf8"
)
const (
tkMachine = iota
tkDefault
tkLogin
tkPassword
tkAccount
tkMacdef
)
var tokenNames = []string{
"Machine",
"Default",
"Login",
"Password",
"Account",
"Macdef",
}
var keywords = map[string]int{
"machine": tkMachine,
"default": tkDefault,
"login": tkLogin,
"password": tkPassword,
"account": tkAccount,
"macdef": tkMacdef,
}
// Machine contains information about a remote machine.
type Machine struct {
Name string
Login string
Password string
Account string
}
// Macros contains all the macro definitions in a netrc file.
type Macros map[string]string
type token struct {
kind int
macroName string
value string
}
type filePos struct {
name string
line int
}
// Error represents a netrc file parse error.
type Error struct {
Filename string
LineNum int // Line number
Msg string // Error message
}
// Error returns a string representation of error e.
func (e *Error) Error() string {
return fmt.Sprintf("%s:%d: %s", e.Filename, e.LineNum, e.Msg)
}
func getWord(b []byte, pos *filePos) (string, []byte) {
// Skip over leading whitespace
i := 0
for i < len(b) {
r, size := utf8.DecodeRune(b[i:])
if r == '\n' {
pos.line++
}
if !unicode.IsSpace(r) {
break
}
i += size
}
b = b[i:]
// Find end of word
i = bytes.IndexFunc(b, unicode.IsSpace)
if i < 0 {
i = len(b)
}
return string(b[0:i]), b[i:]
}
func getToken(b []byte, pos *filePos) ([]byte, *token, error) {
word, b := getWord(b, pos)
if word == "" {
return b, nil, nil // EOF reached
}
t := new(token)
var ok bool
t.kind, ok = keywords[word]
if !ok {
return b, nil, &Error{pos.name, pos.line, "keyword expected; got " + word}
}
if t.kind == tkDefault {
return b, t, nil
}
word, b = getWord(b, pos)
if word == "" {
return b, nil, &Error{pos.name, pos.line, "word expected"}
}
if t.kind == tkMacdef {
t.macroName = word
// Macro value starts on next line. The rest of current line
// should contain nothing but whitespace
i := 0
for i < len(b) {
r, size := utf8.DecodeRune(b[i:])
if r == '\n' {
i += size
pos.line++
break
}
if !unicode.IsSpace(r) {
return b, nil, &Error{pos.name, pos.line, "unexpected word"}
}
i += size
}
b = b[i:]
// Find end of macro value
i = bytes.Index(b, []byte("\n\n"))
if i < 0 { // EOF reached
i = len(b)
}
t.value = string(b[0:i])
return b[i:], t, nil
}
t.value = word
return b, t, nil
}
func parse(r io.Reader, pos *filePos) ([]*Machine, Macros, error) {
// TODO(fhs): Clear memory containing password.
b, err := ioutil.ReadAll(r)
if err != nil {
return nil, nil, err
}
mach := make([]*Machine, 0, 20)
mac := make(Macros, 10)
var defaultSeen bool
var m *Machine
var t *token
for {
b, t, err = getToken(b, pos)
if err != nil {
return nil, nil, err
}
if t == nil {
break
}
switch t.kind {
case tkMacdef:
mac[t.macroName] = t.value
case tkDefault:
if defaultSeen {
return nil, nil, &Error{pos.name, pos.line, "multiple default token"}
}
if m != nil {
mach, m = append(mach, m), nil
}
m = new(Machine)
m.Name = ""
defaultSeen = true
case tkMachine:
if m != nil {
mach, m = append(mach, m), nil
}
m = new(Machine)
m.Name = t.value
case tkLogin:
if m == nil || m.Login != "" {
return nil, nil, &Error{pos.name, pos.line, "unexpected token login "}
}
m.Login = t.value
case tkPassword:
if m == nil || m.Password != "" {
return nil, nil, &Error{pos.name, pos.line, "unexpected token password"}
}
m.Password = t.value
case tkAccount:
if m == nil || m.Account != "" {
return nil, nil, &Error{pos.name, pos.line, "unexpected token account"}
}
m.Account = t.value
}
}
if m != nil {
mach, m = append(mach, m), nil
}
return mach, mac, nil
}
// ParseFile parses the netrc file identified by filename and returns the set of
// machine information and macros defined in it. The ``default'' machine,
// which is intended to be used when no machine name matches, is identified
// by an empty machine name. There can be only one ``default'' machine.
//
// If there is a parsing error, an Error is returned.
func ParseFile(filename string) ([]*Machine, Macros, error) {
// TODO(fhs): Check if file is readable by anyone besides the user if there is password in it.
fd, err := os.Open(filename)
if err != nil {
return nil, nil, err
}
defer fd.Close()
return parse(fd, &filePos{filename, 1})
}
// FindMachine parses the netrc file identified by filename and returns
// the Machine named by name. If no Machine with name name is found, the
// ``default'' machine is returned.
func FindMachine(filename, name string) (*Machine, error) {
mach, _, err := ParseFile(filename)
if err != nil {
return nil, err
}
var def *Machine
for _, m := range mach {
if m.Name == name {
return m, nil
}
if m.Name == "" {
def = m
}
}
if def == nil {
return nil, errors.New("no machine found")
}
return def, nil
}