From c4b44fb12108c0764d1fa4ef1c37f11a54379343 Mon Sep 17 00:00:00 2001
From: Piotr Szarmanski
Date: Mon, 24 Oct 2022 10:50:11 +0200
Subject: Add hash-backend and update README.
---
README | 17 +++++++++++++++++
eris.asd | 2 ++
src/eris-decode.lisp | 29 +++++++++++++++++++----------
src/eris.lisp | 1 +
src/file-backend.lisp | 4 +++-
src/hash-backend.lisp | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
src/package.lisp | 10 +++++++++-
7 files changed, 102 insertions(+), 12 deletions(-)
create mode 100644 src/hash-backend.lisp
diff --git a/README b/README
index 21afb2f..606afba 100644
--- a/README
+++ b/README
@@ -41,3 +41,20 @@ function will attempt to decode an ERIS read-capability in parallel into a file
specified by the OUTPUT-FILE string or pathspec.
See the docstrings of the specific functions for more details.
+
+
+
+A high-level API is provided for convenience in backend.lisp. The concept is
+that a backend object is created, which holds information like output-function,
+fetch-function, caching details, block-size, etc. and the {en/de}coding
+functions simply take the backend as an argument.
+
+This interface consists of two generic functions: store-data, for encoding data,
+and fetch-read-capability, for retrieving the contents of a read-capability
+object.
+
+As an example, a file-based backend called file-backend is provided. It can be
+used simply by making an instance of the 'file-backend class with a :directory
+argument, which will point to the directory in which ERIS data is to be stored.
+
+There is also hash-backend, which implements a simple hash-table backend.
diff --git a/eris.asd b/eris.asd
index 0ec5c7f..1c18f7f 100644
--- a/eris.asd
+++ b/eris.asd
@@ -13,6 +13,8 @@
(:file "base32")
(:file "eris")
(:file "eris-decode")
+ (:file "backend")
+ (:file "file-backend")
#+unix (:file "parallel-decoder"))))
:in-order-to ((test-op (test-op :eris/test))))
diff --git a/src/eris-decode.lisp b/src/eris-decode.lisp
index ba20e9d..3d93312 100644
--- a/src/eris-decode.lisp
+++ b/src/eris-decode.lisp
@@ -218,19 +218,28 @@ hash-table is used, a (copy-seq) needs to be done on the return value of
gethash.
The keyword argument CACHE-CAPACITY indicates the amount of blocks stored in the
-cache."
+cache. It may be NIL to turn off caching entirely."
(declare (type read-capability read-capability)
(type function fetch-function)
- (type integer cache-capacity))
+ (type (or integer null) cache-capacity))
(with-slots (level block-size root-reference-pair) read-capability
- (let* ((get-block (cached-lambda (:cache-class 'lru-cache
- :capacity cache-capacity
- :table (make-hash-table :size (1+ cache-capacity) :test #'equalp))
- (reference key &optional nonce)
- (let* ((block (execute-fetch-function fetch-function reference)))
- (unless block (error 'missing-block :reference reference))
- (hash-check block reference)
- (decrypt-block block key nonce))))
+ (let* ((get-block (if cache-capacity ;; handle caching
+ (cached-lambda (:cache-class 'lru-cache
+ :capacity cache-capacity
+ :table (make-hash-table :size (1+ cache-capacity) :test #'equalp))
+ (reference key nonce)
+ (declare (type octet-vector reference key))
+ (let ((block (execute-fetch-function fetch-function reference)))
+ (declare (type octet-vector block))
+ (hash-check block reference)
+ (decrypt-block block key nonce)))
+ (lambda (reference key nonce)
+ (declare (type octet-vector reference key)
+ (optimize (debug 3)))
+ (let ((block (execute-fetch-function fetch-function reference)))
+ (declare (type octet-vector block))
+ (hash-check block reference)
+ (decrypt-block block key nonce)))))
(root (funcall get-block (reference root-reference-pair) (key root-reference-pair) (make-nonce level))))
;; "Implementations MUST verify the key appearing in the read capability
;; if level of encoded content is larger than 0."
diff --git a/src/eris.lisp b/src/eris.lisp
index 4693104..ed4a05e 100644
--- a/src/eris.lisp
+++ b/src/eris.lisp
@@ -81,6 +81,7 @@ object, using the bytes from the OCTETS vector from at START."
(make-instance 'reference-pair :key key :reference reference)))
(defun decrypt-block (input key &optional (nonce null-secret))
+ (declare (type octet-vector input key nonce))
(ironclad:decrypt-in-place
(ironclad:make-cipher :chacha :mode :stream :key key :initialization-vector nonce)
input)
diff --git a/src/file-backend.lisp b/src/file-backend.lisp
index 2bb8693..03e3ef7 100644
--- a/src/file-backend.lisp
+++ b/src/file-backend.lisp
@@ -43,7 +43,9 @@
(lambda (reference)
(let* ((base32 (bytes-to-base32-unpadded reference))
(file (merge-pathnames directory base32)))
- (alexandria:read-file-into-byte-vector file)))
+ (if (probe-file file)
+ (alexandria:read-file-into-byte-vector file)
+ (error 'missing-block :reference reference))))
output-function
(lambda (block reference)
(let* ((base32 (bytes-to-base32-unpadded reference))
diff --git a/src/hash-backend.lisp b/src/hash-backend.lisp
new file mode 100644
index 0000000..91dc673
--- /dev/null
+++ b/src/hash-backend.lisp
@@ -0,0 +1,51 @@
+;; This file is part of eris-cl.
+;; Copyright (C) 2022 Piotr Szarmański
+
+;; eris-cl is free software: you can redistribute it and/or modify it under the
+;; terms of the GNU Lesser General Public License as published by the Free
+;; Software Foundation, either version 3 of the License, or (at your option) any
+;; later version.
+
+;; eris-cl is distributed in the hope that it will be useful, but WITHOUT ANY
+;; WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+;; A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License along with
+;; eris-cl. If not, see <https://www.gnu.org/licenses/>.
+
+(in-package :eris)
+
+(defclass hash-backend (encoding-backend decoding-backend)
+ ((table :type hash-table)))
+
+(defmethod shared-initialize :after ((hash-backend hash-backend) slot-names
+ &rest initargs
+ &key &allow-other-keys)
+
+ (declare (ignore initargs slot-names))
+ (let ((hash-table (make-hash-table :test #'equalp)))
+ (with-slots (table output-function fetch-function) hash-backend
+ (setf table hash-table
+ fetch-function (lambda (reference)
+ (declare (type octet-vector reference))
+ (copy-seq (gethash reference hash-table)))
+ output-function (lambda (block reference)
+ (declare (type octet-vector block reference))
+ (setf (gethash reference hash-table)
+ block))))))
+
+(defmethod fetch-read-capability (read-capability (backend hash-backend) &key &allow-other-keys)
+ (declare (type read-capability read-capability))
+ (with-slots (fetch-function) backend
+ (eris-decode read-capability fetch-function :cache-capacity nil)))
+
+(defmethod store-data (input (backend hash-backend) &key (secret null-secret) (block-size 1kib) &allow-other-keys)
+ (declare (type octet-vector secret))
+ (with-slots (output-function) backend
+ (eris-encode input
+ block-size
+ output-function
+ :hash-output nil
+ :secret secret)))
+
+
diff --git a/src/package.lisp b/src/package.lisp
index 873a453..0265f74 100644
--- a/src/package.lisp
+++ b/src/package.lisp
@@ -43,4 +43,12 @@
#:padding-error
#:version-mismatch
#:hash-mismatch
- #:invalid-internal-block))
+ #:invalid-internal-block
+ #:missing-block
+
+ #:store-data
+ #:fetch-read-capability
+ #:encoding-backend
+ #:decoding-backend
+ #:file-backend
+ #:hash-backend))
--
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