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|
package hook
import (
"bufio"
"crypto/md5"
"crypto/rand"
"errors"
"fmt"
"io"
"os"
"strings"
"time"
"tunnel/pkg/server/env"
"tunnel/pkg/server/queue"
)
const authTimeout = 5 * time.Second
const saltSize = 16
const hashSize = md5.Size
var hashNone = strings.Repeat("\x00", hashSize)
type authHook struct {
Passive bool
}
type auth struct {
file *os.File
user string
salt string
pass string
peer struct {
user string
salt string
}
hash string
passive bool
stageHello chan struct{}
stageHash chan struct{}
ready chan struct{}
recver chan struct{}
sender chan struct{}
tmr *time.Timer
}
var errAuthFail = errors.New("mismatch auth hash")
var errAuthUnknown = errors.New("unknown auth peer")
var errTimeout = errors.New("timeout")
func hashsum(args ...string) string {
h := md5.New()
for _, s := range args {
io.WriteString(h, s)
}
return string(h.Sum(nil))
}
func getpass(f *os.File, salt string, user string) string {
f.Seek(0, 0)
match := func(s, t string) bool {
if salt == "" {
return s == t
}
return hashsum(salt, s) == t
}
for scanner := bufio.NewScanner(f); scanner.Scan(); {
splitted := strings.SplitN(scanner.Text(), "#", 2)
tokens := strings.Fields(splitted[0])
if len(tokens) > 1 && match(tokens[0], user) {
return tokens[1]
}
}
return ""
}
func (a *auth) Init(authfile string, user string) error {
file, err := os.Open(authfile)
if err != nil {
return fmt.Errorf("authfile: %w", err)
}
a.file = file
if user != "" {
pass := getpass(file, "", user)
if pass == "" {
file.Close()
return fmt.Errorf("authfile: no pass for user '%s'", user)
}
a.user = user
a.pass = pass
}
b := make([]byte, saltSize)
if _, err := rand.Read(b); err != nil {
return err
}
a.salt = string(b)
a.tmr = time.NewTimer(authTimeout)
return nil
}
func (a *auth) sync(c chan struct{}) error {
select {
case <-a.tmr.C:
return errTimeout
case <-a.recver:
return io.EOF
case <-a.sender:
return io.EOF
case <-c:
return nil
}
}
func (a *auth) Send(rq, wq queue.Q) error {
w := wq.Writer()
io.WriteString(w, a.salt)
if a.passive {
io.WriteString(w, hashNone)
} else {
io.WriteString(w, hashsum(a.salt, a.user))
}
if err := a.sync(a.stageHello); err != nil {
return err
}
if a.passive && a.peer.user == hashNone {
close(a.sender)
return fmt.Errorf("can not be passive together")
}
var pass string
if a.peer.user == hashNone {
pass = hashsum(a.pass)
} else {
pass = getpass(a.file, a.peer.salt, a.peer.user)
if pass == "" {
close(a.sender)
return fmt.Errorf("no pass for peer")
}
if a.passive {
a.pass = hashsum(pass)
}
}
io.WriteString(w, hashsum(a.peer.salt, pass))
if err := a.sync(a.stageHash); err != nil {
return err
}
if a.hash != hashsum(a.salt, a.pass) {
close(a.sender)
return errAuthFail
}
close(a.ready)
return queue.IoCopy(rq.Reader(), w)
}
func (a *auth) read(r io.Reader, n int, s *string) error {
b := make([]byte, n)
if _, err := io.ReadFull(r, b); err != nil {
close(a.recver)
return err
}
*s = string(b)
return nil
}
func (a *auth) Recv(rq, wq queue.Q) error {
r := rq.Reader()
if err := a.read(r, saltSize, &a.peer.salt); err != nil {
return err
}
if err := a.read(r, hashSize, &a.peer.user); err != nil {
return err
}
close(a.stageHello)
if err := a.read(r, hashSize, &a.hash); err != nil {
return err
}
close(a.stageHash)
if err := a.sync(a.ready); err != nil {
return err
}
a.tmr.Stop()
return queue.IoCopy(r, wq.Writer())
}
func (a *auth) Close() {
a.file.Close()
}
func (h *authHook) New(env env.Env) (interface{}, error) {
file := env.Value("authfile")
if file == "" {
return nil, errors.New("no authfile configured")
}
user := ""
if !h.Passive {
user = env.Value("authuser")
if user == "" {
return nil, errors.New("no authuser configured")
}
}
a := &auth{
passive: h.Passive,
ready: make(chan struct{}),
recver: make(chan struct{}),
sender: make(chan struct{}),
stageHello: make(chan struct{}),
stageHash: make(chan struct{}),
}
if err := a.Init(file, user); err != nil {
return nil, err
}
return a, nil
}
func init() {
register("auth", "chap out/in", authHook{})
}
|
