/
auth.go
356 lines (320 loc) · 8.61 KB
/
auth.go
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package main
import (
"bytes"
"encoding/base64"
"errors"
"fmt"
"github.com/cyfdecyf/bufio"
"net"
"os"
"strconv"
"strings"
"text/template"
"time"
)
const (
authRealm = "meow proxy"
authRawBodyTmpl = `<!DOCTYPE html>
<html>
<head> <title>meow Proxy</title> </head>
<body>
<h1>407 Proxy authentication required</h1>
<hr />
Generated by <i>meow</i>
</body>
</html>
`
)
type netAddr struct {
ip net.IP
mask net.IPMask
}
type authUser struct {
// user name is the key to auth.user, no need to store here
passwd string
ha1 string // used in request digest, initialized ondemand
port uint16 // 0 means any port
}
var auth struct {
required bool
user map[string]*authUser
allowedClient []netAddr
authed *TimeoutSet // cache authenticated users based on ip
template *template.Template
}
func (au *authUser) initHA1(user string) {
if au.ha1 == "" {
au.ha1 = md5sum(user + ":" + authRealm + ":" + au.passwd)
}
}
func parseUserPasswd(userPasswd string) (user string, au *authUser, err error) {
arr := strings.Split(userPasswd, ":")
n := len(arr)
if n == 1 || n > 3 {
err = errors.New("user password: " + userPasswd +
" syntax wrong, should be username:password[:port]")
return
}
user, passwd := arr[0], arr[1]
if user == "" || passwd == "" {
err = errors.New("user password " + userPasswd +
" should not contain empty user name or password")
return "", nil, err
}
var port int
if n == 3 && arr[2] != "" {
port, err = strconv.Atoi(arr[2])
if err != nil || port <= 0 || port > 0xffff {
err = errors.New("user password: " + userPasswd + " invalid port")
return "", nil, err
}
}
au = &authUser{passwd, "", uint16(port)}
return user, au, nil
}
func parseAllowedClient(val string) {
if val == "" {
return
}
arr := strings.Split(val, ",")
auth.allowedClient = make([]netAddr, len(arr))
for i, v := range arr {
s := strings.TrimSpace(v)
ipAndMask := strings.Split(s, "/")
if len(ipAndMask) > 2 {
Fatal("allowedClient syntax error: client should be the form ip/nbitmask")
}
ip := net.ParseIP(ipAndMask[0])
if ip == nil {
Fatalf("allowedClient syntax error %s: ip address not valid\n", s)
}
var mask net.IPMask
if len(ipAndMask) == 2 {
nbit, err := strconv.Atoi(ipAndMask[1])
if err != nil {
Fatalf("allowedClient syntax error %s: %v\n", s, err)
}
if nbit > 32 {
Fatal("allowedClient error: mask number should <= 32")
}
mask = NewNbitIPv4Mask(nbit)
} else {
mask = NewNbitIPv4Mask(32)
}
auth.allowedClient[i] = netAddr{ip.Mask(mask), mask}
}
}
func addUserPasswd(val string) {
if val == "" {
return
}
user, au, err := parseUserPasswd(val)
debug.Println("user:", user, "port:", au.port)
if err != nil {
Fatal(err)
}
if _, ok := auth.user[user]; ok {
Fatal("duplicate user:", user)
}
auth.user[user] = au
}
func loadUserPasswdFile(file string) {
if file == "" {
return
}
f, err := os.Open(file)
if err != nil {
Fatal("error opening user passwd fle:", err)
}
r := bufio.NewReader(f)
s := bufio.NewScanner(r)
for s.Scan() {
addUserPasswd(s.Text())
}
f.Close()
}
func initAuth() {
if config.UserPasswd != "" ||
config.UserPasswdFile != "" ||
config.AllowedClient != "" {
auth.required = true
} else {
return
}
auth.user = make(map[string]*authUser)
addUserPasswd(config.UserPasswd)
loadUserPasswdFile(config.UserPasswdFile)
parseAllowedClient(config.AllowedClient)
auth.authed = NewTimeoutSet(time.Duration(config.AuthTimeout) * time.Hour)
rawTemplate := "HTTP/1.1 407 Proxy Authentication Required\r\n" +
"Proxy-Authenticate: Digest realm=\"" + authRealm + "\", nonce=\"{{.Nonce}}\", qop=\"auth\"\r\n" +
"Content-Type: text/html\r\n" +
"Cache-Control: no-cache\r\n" +
"Content-Length: " + fmt.Sprintf("%d", len(authRawBodyTmpl)) + "\r\n\r\n" + authRawBodyTmpl
var err error
if auth.template, err = template.New("auth").Parse(rawTemplate); err != nil {
Fatal("internal error generating auth template:", err)
}
}
// Return err = nil if authentication succeed. nonce would be not empty if
// authentication is needed, and should be passed back on subsequent call.
func Authenticate(conn *clientConn, r *Request) (err error) {
clientIP, _, _ := net.SplitHostPort(conn.RemoteAddr().String())
if auth.authed.has(clientIP) {
debug.Printf("%s has already authed\n", clientIP)
return
}
if authIP(clientIP) { // IP is allowed
return
}
err = authUserPasswd(conn, r)
if err == nil {
auth.authed.add(clientIP)
}
return
}
// authIP checks whether the client ip address matches one in allowedClient.
// It uses a sequential search.
func authIP(clientIP string) bool {
ip := net.ParseIP(clientIP)
if ip == nil {
panic("authIP should always get IP address")
}
for _, na := range auth.allowedClient {
if ip.Mask(na.mask).Equal(na.ip) {
debug.Printf("client ip %s allowed\n", clientIP)
return true
}
}
return false
}
func genNonce() string {
buf := new(bytes.Buffer)
fmt.Fprintf(buf, "%x", time.Now().Unix())
return buf.String()
}
func calcRequestDigest(kv map[string]string, ha1, method string) string {
// Refer to rfc2617 section 3.2.2.1 Request-Digest
arr := []string{
ha1,
kv["nonce"],
kv["nc"],
kv["cnonce"],
"auth",
md5sum(method + ":" + kv["uri"]),
}
return md5sum(strings.Join(arr, ":"))
}
func checkProxyAuthorization(conn *clientConn, r *Request) error {
if debug {
debug.Printf("cli(%s) authorization: %s\n", conn.RemoteAddr(), r.ProxyAuthorization)
}
arr := strings.SplitN(r.ProxyAuthorization, " ", 2)
if len(arr) != 2 {
return errors.New("auth: malformed ProxyAuthorization header: " + r.ProxyAuthorization)
}
authMethod := strings.ToLower(strings.TrimSpace(arr[0]))
if authMethod == "digest" {
return authDigest(conn, r, arr[1])
} else if authMethod == "basic" {
return authBasic(conn, arr[1])
}
return errors.New("auth: method " + arr[0] + " unsupported, must use digest")
}
func authPort(conn *clientConn, user string, au *authUser) error {
if au.port == 0 {
return nil
}
_, portStr, _ := net.SplitHostPort(conn.LocalAddr().String())
port, _ := strconv.Atoi(portStr)
if uint16(port) != au.port {
errl.Printf("cli(%s) auth: user %s port not match\n", conn.RemoteAddr(), user)
return errAuthRequired
}
return nil
}
func authBasic(conn *clientConn, userPasswd string) error {
b64, err := base64.StdEncoding.DecodeString(userPasswd)
if err != nil {
return errors.New("auth:" + err.Error())
}
arr := strings.Split(string(b64), ":")
if len(arr) != 2 {
return errors.New("auth: malformed basic auth user:passwd")
}
user := arr[0]
passwd := arr[1]
au, ok := auth.user[user]
if !ok || au.passwd != passwd {
return errAuthRequired
}
return authPort(conn, user, au)
}
func authDigest(conn *clientConn, r *Request, keyVal string) error {
authHeader := parseKeyValueList(keyVal)
if len(authHeader) == 0 {
return errors.New("auth: empty authorization list")
}
nonceTime, err := strconv.ParseInt(authHeader["nonce"], 16, 64)
if err != nil {
return fmt.Errorf("auth: nonce %v", err)
}
// If nonce time too early, reject. iOS will create a new connection to do
// authentication.
if time.Now().Sub(time.Unix(nonceTime, 0)) > time.Minute {
return errAuthRequired
}
user := authHeader["username"]
au, ok := auth.user[user]
if !ok {
errl.Printf("cli(%s) auth: no such user: %s\n", conn.RemoteAddr(), authHeader["username"])
return errAuthRequired
}
if err = authPort(conn, user, au); err != nil {
return err
}
if authHeader["qop"] != "auth" {
return errors.New("auth: qop wrong: " + authHeader["qop"])
}
response, ok := authHeader["response"]
if !ok {
return errors.New("auth: no request-digest response")
}
au.initHA1(user)
digest := calcRequestDigest(authHeader, au.ha1, r.Method)
if response != digest {
errl.Printf("cli(%s) auth: digest not match, maybe password wrong", conn.RemoteAddr())
return errAuthRequired
}
return nil
}
func authUserPasswd(conn *clientConn, r *Request) (err error) {
if r.ProxyAuthorization != "" {
// client has sent authorization header
err = checkProxyAuthorization(conn, r)
if err == nil {
return
} else if err != errAuthRequired {
sendErrorPage(conn, statusBadReq, "Bad authorization request", err.Error())
return
}
// auth required to through the following
}
nonce := genNonce()
data := struct {
Nonce string
}{
nonce,
}
buf := new(bytes.Buffer)
if err := auth.template.Execute(buf, data); err != nil {
return fmt.Errorf("error generating auth response: %v", err)
}
if bool(debug) && verbose {
debug.Printf("authorization response:\n%s", buf.String())
}
if _, err := conn.Write(buf.Bytes()); err != nil {
return fmt.Errorf("send auth response error: %v", err)
}
return errAuthRequired
}