Merge pull request #56 from mutantmonkey/auth

Add support for auth keys (and remote auth keys)

README.md

@@ -30,6 +30,8 @@ Command-line options
 - ```-xframeoptions "..." ``` -- X-Frame-Options header (default is "SAMEORIGIN")
 - ```-remoteuploads``` -- (optionally) enable remote uploads (/upload?url=https://...) 
 - ```-realip``` -- (optionally) let linx-server know you (nginx, etc) are providing the X-Real-IP and/or X-Forwarded-For headers.
+- ````-authfile path/to/authfile``` -- (optionally) require authorization for upload/delete by providing a newline-separated file of scrypted auth keys
+- ````-remoteauthfile path/to/remoteauthfile``` -- (optionally) require authorization for remote uploads by providing a newline-separated file of scrypted auth keys
 - ```-fastcgi``` -- (optionally) serve through fastcgi 
 - ```-nologs``` -- (optionally) disable request logs in stdout
 

auth.go

@@ -0,0 +1,128 @@
+package main
+
+import (
+	"bufio"
+	"encoding/base64"
+	"log"
+	"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
+	authKeys       []string
+	o              AuthOptions
+}
+
+func readAuthKeys(authFile string) []string {
+	var authKeys []string
+
+	f, err := os.Open(authFile)
+	if err != nil {
+		log.Fatal("Failed to open authfile: ", err)
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		authKeys = append(authKeys, scanner.Text())
+	}
+
+	err = scanner.Err()
+	if err != nil {
+		log.Fatal("Scanner error while reading authfile: ", err)
+	}
+
+	return authKeys
+}
+
+func checkAuth(authKeys []string, decodedAuth []byte) (result bool, err error) {
+	checkKey, err := scrypt.Key([]byte(decodedAuth), []byte(scryptSalt), scryptN, scryptr, scryptp, scryptKeyLen)
+	if err != nil {
+		return
+	}
+
+	encodedKey := base64.StdEncoding.EncodeToString(checkKey)
+	for _, v := range authKeys {
+		if encodedKey == v {
+			result = true
+			return
+		}
+	}
+
+	result = false
+	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.authKeys, 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),
+			authKeys:       readAuthKeys(o.AuthFile),
+			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
+}

auth_test.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestCheckAuth(t *testing.T) {
+	authKeys := []string{
+		"vhvZ/PT1jeTbTAJ8JdoxddqFtebSxdVb0vwPlYO+4HM=",
+		"vFpNprT9wbHgwAubpvRxYCCpA2FQMAK6hFqPvAGrdZo=",
+	}
+
+	if r, err := checkAuth(authKeys, []byte("")); err != nil && r {
+		t.Fatal("Authorization passed for empty key")
+	}
+
+	if r, err := checkAuth(authKeys, []byte("thisisnotvalid")); err != nil && r {
+		t.Fatal("Authorization passed for invalid key")
+	}
+
+	if r, err := checkAuth(authKeys, []byte("haPVipRnGJ0QovA9nyqK")); err != nil && !r {
+		t.Fatal("Authorization failed for valid key")
+	}
+}

server.go

@@ -35,6 +35,8 @@ var Config struct {
 	allowHotlink              bool
 	fastcgi                   bool
 	remoteUploads             bool
+	authFile                  string
+	remoteAuthFile            string
 }
 
 var Templates = make(map[string]*pongo2.Template)
@@ -42,6 +44,7 @@ var TemplateSet *pongo2.TemplateSet
 var staticBox *rice.Box
 var timeStarted time.Time
 var timeStartedStr string
+var remoteAuthKeys []string
 
 func setup() *web.Mux {
 	mux := web.New()
@@ -64,6 +67,13 @@ func setup() *web.Mux {
 		frame:  Config.xFrameOptions,
 	}))
 
+	if Config.authFile != "" {
+		mux.Use(UploadAuth(AuthOptions{
+			AuthFile:      Config.authFile,
+			UnauthMethods: []string{"GET", "HEAD", "OPTIONS", "TRACE"},
+		}))
+	}
+
 	// make directories if needed
 	err := os.MkdirAll(Config.filesDir, 0755)
 	if err != nil {
@@ -103,15 +113,25 @@ func setup() *web.Mux {
 	selifIndexRe := regexp.MustCompile(`^/selif/$`)
 	torrentRe := regexp.MustCompile(`^/(?P<name>[a-z0-9-\.]+)/torrent$`)
 
-	mux.Get("/", indexHandler)
-	mux.Get("/paste/", pasteHandler)
+	if Config.authFile == "" {
+		mux.Get("/", indexHandler)
+		mux.Get("/paste/", pasteHandler)
+	} else {
+		mux.Get("/", http.RedirectHandler("/API", 303))
+		mux.Get("/paste/", http.RedirectHandler("/API/", 303))
+	}
 	mux.Get("/paste", http.RedirectHandler("/paste/", 301))
+
 	mux.Get("/API/", apiDocHandler)
 	mux.Get("/API", http.RedirectHandler("/API/", 301))
 
 	if Config.remoteUploads {
 		mux.Get("/upload", uploadRemote)
 		mux.Get("/upload/", uploadRemote)
+
+		if Config.remoteAuthFile != "" {
+			remoteAuthKeys = readAuthKeys(Config.remoteAuthFile)
+		}
 	}
 
 	mux.Post("/upload", uploadPostHandler)
@@ -159,6 +179,10 @@ func main() {
 		"serve through fastcgi")
 	flag.BoolVar(&Config.remoteUploads, "remoteuploads", false,
 		"enable remote uploads")
+	flag.StringVar(&Config.authFile, "authfile", "",
+		"path to a file containing newline-separated scrypted auth keys")
+	flag.StringVar(&Config.remoteAuthFile, "remoteauthfile", "",
+		"path to a file containing newline-separated scrypted auth keys for remote uploads")
 	flag.StringVar(&Config.contentSecurityPolicy, "contentsecuritypolicy",
 		"default-src 'self'; img-src 'self' data:; style-src 'self' 'unsafe-inline'; referrer none;",
 		"value of default Content-Security-Policy header")

server_test.go

@@ -52,6 +52,47 @@ func TestIndex(t *testing.T) {
 	}
 }
 
+func TestAuthKeys(t *testing.T) {
+	Config.authFile = "/dev/null"
+
+	redirects := []string{
+		"/",
+		"/paste/",
+	}
+
+	mux := setup()
+
+	for _, v := range redirects {
+		w := httptest.NewRecorder()
+
+		req, err := http.NewRequest("GET", v, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		mux.ServeHTTP(w, req)
+
+		if w.Code != 303 {
+			t.Fatalf("Status code is not 303, but %d", w.Code)
+		}
+	}
+
+	w := httptest.NewRecorder()
+
+	req, err := http.NewRequest("POST", "/paste/", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mux.ServeHTTP(w, req)
+
+	if w.Code != 401 {
+		t.Fatalf("Status code is not 401, but %d", w.Code)
+	}
+
+	Config.authFile = ""
+}
+
 func TestNotFound(t *testing.T) {
 	mux := setup()
 	w := httptest.NewRecorder()

upload.go

@@ -138,6 +138,19 @@ func uploadPutHandler(c web.C, w http.ResponseWriter, r *http.Request) {
 }
 
 func uploadRemote(c web.C, w http.ResponseWriter, r *http.Request) {
+	if Config.remoteAuthFile != "" {
+		result, err := checkAuth(remoteAuthKeys, []byte(r.FormValue("key")))
+		if err != nil || !result {
+			unauthorizedHandler(c, w, r)
+		}
+	} else {
+		// strict referrer checking is mandatory without remote auth keys
+		if !strictReferrerCheck(r, Config.siteURL, []string{"Linx-Delete-Key", "Linx-Expiry", "Linx-Randomize"}) {
+			badRequestHandler(c, w, r)
+			return
+		}
+	}
+
 	if r.FormValue("url") == "" {
 		http.Redirect(w, r, "/", 303)
 		return