linx-server/auth.go

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package main
import (
"bufio"
"encoding/base64"
"net/http"
"os"
"strings"
"golang.org/x/crypto/scrypt"
)
const (
authPrefix = "Linx "
scryptSalt = "linx-server"
scryptN = 16384
scryptr = 8
scryptp = 1
scryptKeyLen = 32
)
type AuthOptions struct {
AuthFile string
UnauthMethods []string
}
type auth struct {
successHandler http.Handler
failureHandler http.Handler
o AuthOptions
}
func checkAuth(authFile string, decodedAuth []byte) (result bool, err error) {
f, err := os.Open(authFile)
if err != nil {
return
}
checkKey, err := scrypt.Key([]byte(decodedAuth), []byte(scryptSalt), scryptN, scryptr, scryptp, scryptKeyLen)
if err != nil {
return
}
encodedKey := base64.StdEncoding.EncodeToString(checkKey)
scanner := bufio.NewScanner(bufio.NewReader(f))
for scanner.Scan() {
if encodedKey == scanner.Text() {
result = true
return
}
}
result = false
err = scanner.Err()
return
}
func (a auth) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if sliceContains(a.o.UnauthMethods, r.Method) {
// allow unauthenticated methods
a.successHandler.ServeHTTP(w, r)
return
}
authHeader := r.Header.Get("Authorization")
if !strings.HasPrefix(authHeader, authPrefix) {
a.failureHandler.ServeHTTP(w, r)
return
}
decodedAuth, err := base64.StdEncoding.DecodeString(authHeader[len(authPrefix):])
if err != nil {
a.failureHandler.ServeHTTP(w, r)
return
}
result, err := checkAuth(a.o.AuthFile, decodedAuth)
if err != nil || !result {
a.failureHandler.ServeHTTP(w, r)
return
}
a.successHandler.ServeHTTP(w, r)
}
func UploadAuth(o AuthOptions) func(http.Handler) http.Handler {
fn := func(h http.Handler) http.Handler {
return auth{
successHandler: h,
failureHandler: http.HandlerFunc(badAuthorizationHandler),
o: o,
}
}
return fn
}
func badAuthorizationHandler(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusUnauthorized)
http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
}
func sliceContains(slice []string, s string) bool {
for _, v := range slice {
if s == v {
return true
}
}
return false
}