feat: v2 (#599)

Read https://github.com/filebrowser/filebrowser/pull/575.

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Former-commit-id: e032e0804dd051df86f42962de2b39caec5318b7

auth/proxy.go

@@ -0,0 +1,35 @@
+package auth
+
+import (
+	"net/http"
+	"os"
+
+	"github.com/filebrowser/filebrowser/v2/settings"
+	"github.com/filebrowser/filebrowser/v2/users"
+	"github.com/filebrowser/filebrowser/v2/errors"
+)
+
+// MethodProxyAuth is used to identify no auth.
+const MethodProxyAuth settings.AuthMethod = "proxy"
+
+// ProxyAuth is a proxy implementation of an auther.
+type ProxyAuth struct {
+	Header  string
+	storage *users.Storage
+}
+
+// Auth authenticates the user via an HTTP header.
+func (a *ProxyAuth) Auth(r *http.Request) (*users.User, error) {
+	username := r.Header.Get(a.Header)
+	user, err := a.storage.Get(username)
+	if err == errors.ErrNotExist {
+		return nil, os.ErrPermission
+	}
+
+	return user, err
+}
+
+// SetStorage attaches the storage to the auther.
+func (a *ProxyAuth) SetStorage(s *users.Storage) {
+	a.storage = s
+}