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check / check (push) Failing after 3s
Details
fetch: destination directory, skip files already present, save the manifest, require a signer (closes #101) 
fetch takes --dest (default .) and writes every file there through the
existing symlink and hard-link guards, which now work relative to that
directory. A file already there with the listed size and hash is
skipped; a leftover temp file is still replaced. Once every file
verifies, the manifest is saved as index.mf through the same temp file
and rename, so check runs on the result. --require-signature is shared
with check and enforced through verifyRequiredSigner, on a Checker over
the manifest held in memory, before anything is downloaded or written.

Model: opus-5-5
2026-10-04 15:20:55 +00:00

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# mfer
[mfer](https://git.eeqj.de/sneak/mfer) is a [WTFPL](https://wtfpl.net)-licensed
(public domain) [Go](https://golang.org) library and command-line tool by
[@sneak](https://sneak.berlin) that specifies and generates `.mf` manifest files
over a directory tree to encapsulate metadata about the files — such as
cryptographic checksums and signatures over same — to aid in archiving,
downloading, streaming, and mirroring. It was first published in 2022. The
manifest files' data is serialized with Google's
[protobuf serialization format](https://developers.google.com/protocol-buffers).
The structure of these files can be found
[in the format specification](https://git.eeqj.de/sneak/mfer/src/branch/main/mfer/mf.proto)
which is included in the [project repository](https://git.eeqj.de/sneak/mfer).
The current version is pre-1.0 and while the repo was published in 2022, there
has not yet been any versioned release. [SemVer](https://semver.org) will be
used for releases.
This project was started by [@sneak](https://sneak.berlin) to scratch an itch in
2022 and is currently a one-person effort, though the goal is for this to emerge
as a de-facto standard and be incorporated into other software. A compatible
javascript library is planned.
# Getting Started
`mfer` builds from source with a Go 1.23+ toolchain. The generated protobuf code
is committed, so no `protoc` toolchain is required:
```sh
git clone https://git.eeqj.de/sneak/mfer.git
cd mfer
go build -o bin/mfer ./cmd/mfer
```
Generate a manifest for a directory tree, verify it later, and fetch a published
tree by URL:
```sh
# Write index.mf, a manifest of the files under the current directory.
bin/mfer gen .
# Verify the files on disk against the manifest. Exits nonzero if any file
# is missing or corrupted.
bin/mfer check index.mf
# Download and cryptographically verify a tree published over HTTP into
# ./mirror: mfer fetches <url>/index.mf, downloads every file it lists,
# skipping any already there with the right hash, then saves the manifest as
# mirror/index.mf.
bin/mfer fetch --dest mirror https://example.com/tree/
```
Run `bin/mfer help` for the full command list, or `bin/mfer <command> --help`
for a single command's options.
# Build Status
CI runs `script/cibuild`, which builds the Docker image with `--no-cache`, so
the formatting, lint and test steps in the `Dockerfile` run on every build. The
`main` branch must always be green.
# Entrypoints
This repository adheres to the
[Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
standard: normalized scripts in `script/` are the entrypoints for the
development workflow, and the Makefile targets are thin shims that call them. We
provide:
- `script/bootstrap` — install all dependencies (Go, Go module download, and
node/yarn plus the prettier version pinned in `package.json`/`yarn.lock`),
idempotently; golangci-lint is not installed, it runs only in Docker
- `script/setup` — make a fresh clone ready for development: runs
`script/bootstrap`, then `script/install-precommit`
- `script/projectname` — output the project name (`mfer`); used by other scripts
such as `script/docker`
- `script/test` — run the test suite (`go test`); one test fails when
`mfer/mf.proto` no longer matches the hash `script/generate` recorded
- `script/generate` (`make generate`) — regenerate `mfer/mf.pb.go` from
`mfer/mf.proto` and record the hash of that `mfer/mf.proto` in
`mfer/mf.proto.sha256`; the only thing that regenerates the committed
`mfer/mf.pb.go`. It needs the exact versions that wrote the committed file,
and refuses to run with any other: `protoc` 33.4 (unpack
`protoc-33.4-<platform>.zip` from
[its release](https://github.com/protocolbuffers/protobuf/releases/tag/v33.4)
and put its `bin/protoc` on `PATH`) and `protoc-gen-go` v1.36.11
(`go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.36.11`, which
installs it in `$(go env GOPATH)/bin`; `make generate` adds that directory to
`PATH`)
- `script/fuzz` — fuzz the manifest parser for one minute; run by hand
(`make fuzz`), never by CI, while `script/test` runs its committed seed corpus
as ordinary tests
- `script/lint` — run `golangci-lint` in Docker: builds only the `lint` stage of
the `Dockerfile` (the Go format check, then the linter), uncached so it runs
every time, then removes the image
- `script/fmt` — format all code and docs (writes): `gofumpt` and
`script/prettier --write`
- `script/prettier` — run prettier over the repository's canonical file set
(Markdown and JSON, minus `.prettierignore`) in the given mode, `--write` or
`--check`; the single definition of that file set, so `script/fmt` and
`script/fmt-check` cannot disagree about it
- `script/fmt-check` — check formatting without writing: `script/fmt-check-go`
plus `script/prettier --check`
- `script/fmt-check-go` — the Go half of `script/fmt-check`, on its own, for the
Docker lint stage, whose image has no node
- `script/check` — run `script/test`, `script/lint`, and `script/fmt-check`
- `script/docker` — build the Docker image tagged with the project name
- `script/cibuild` — CI entrypoint: builds the image with the same command as
`script/docker`, uncached, so the checks in the Dockerfile run every time
- `script/precommit` — pre-commit checks: `go mod tidy` verification, then
`script/check`
- `script/install-precommit` — install the git pre-commit hook that runs
`script/precommit`
# Participation
The community is as yet nonexistent so there are no defined policies or norms
yet. Primary development happens on a privately-run Gitea instance at
[https://git.eeqj.de/sneak/mfer](https://git.eeqj.de/sneak/mfer) and issues are
[tracked there](https://git.eeqj.de/sneak/mfer/issues).
Changes must always be formatted with a standard `go fmt`, syntactically valid,
and must pass the linting defined in the repository's `.golangci.yml`, which
`make lint` runs in Docker. The `main` branch is protected and all changes must
be made via [pull requests](https://git.eeqj.de/sneak/mfer/pulls) and pass CI to
be merged. Any changes submitted to this project must also be
[WTFPL-licensed](https://wtfpl.net) to be considered.
See [`REPO_POLICIES.md`](REPO_POLICIES.md) for detailed coding standards,
tooling requirements, and workflow conventions.
# Rationale
## The problem
Given a plain URL, there is no standard way to safely and programmatically
download everything "under" that URL path. `wget -r` can traverse directory
listings if they're enabled, but every server has a different format, and this
does not verify cryptographic integrity of the files, or enable them to be
fetched using a different protocol other than HTTP/s.
Currently, the solution that people are using are sidecar files in the format of
`SHASUMS` checksum files, as well as a `SHASUMS.asc` PGP detached signature.
This is not checksum-algorithm-agnostic and the sidecar file is not always
consistently named.
Real issues I face:
- when I plug in an ExFAT hard drive, I don't know if any files on the
filesystem are corrupted or missing
- current ad-hoc solution are `SHASUMS`/`SHASUMS.asc` files
- when I want to mirror an HTTP archive, I have to use special tools like
debmirror that understand the archive format
- the debian repository metadata structure is hot garbage
- when I download a large file via HTTP, I have no way of knowing if the file
content is what it's supposed to be
## The solution
A standard, a manifest file format, and a tool for generating same.
The manifest file would be called `index.mf`, and the tool for generating such
would be called `mfer`.
The manifest file would do several important things:
- have a standard filename, so if given `https://example.com/downloadpackage/`
one could fetch `https://example.com/downloadpackage/index.mf` to enumerate
the full directory listing.
- contain a version field for extensibility
- contain structured data (protobuf, json, or cbor)
- provide an inner signed container, so that the manifest file itself can embed
a signature and a public key alongside in a single file
- contain a list of files, each with a relative path to the manifest
- contain manifest timestamp
- contain ctime/mtime information for files so that file metadata can be
preserved
- contain cryptographic checksums in several different algorithms for each file
- probably encoded with multihash to indicate algo + hash
- sha256 at the minimum
- would be nice to include an IPFS/IPLD CIDv1 root hash for each file, which
likely involves doing an ipfs file object chunking
- maybe even including the complete IPFS/IPLD directory tree objects and
chunklists?
- this is because generating an `index.mf` does not imply publishing on
ipfs at that time
- maybe a bittorrent chunklist for torrent client compatibility? perhaps a
top-level infohash for the whole manifest?
# Design
The repository is split into a reusable library and a thin command-line wrapper
around it.
- `mfer/` is the reusable library and the heart of the project: it defines the
manifest format and implements building, scanning, checking, serialization,
and signing. The protobuf schema is `mfer/mf.proto`, and the generated code it
produces (`mfer/mf.pb.go`) is committed alongside it so the library builds
with `go get` and needs no `protoc` toolchain.
- `internal/cli/` holds the command implementations — `generate` (alias `gen`),
`check`, `freshen`, `export`, `list` (alias `ls`), `fetch`, and `version` —
that wire the library to the command-line interface.
- `internal/log/` provides the logging used by the commands and the library.
- `internal/bork/` provides the error the library returns when a manifest's
decompressed contents are not the size the manifest records.
- `cmd/mfer/` is the entrypoint: its `main` package runs `internal/cli` and
exits with the status it returns.
Everything under `internal/` is private to this repository; only the `mfer/`
package is intended for import by other software.
# Design Goals
- Replace SHASUMS/SHASUMS.asc files
- be easy to download/resume a whole directory tree published via HTTP
- be easy to use across protocols (given an HTTPS url, fetch manifest, then
download file contents via bittorrent or ipfs)
- not strongly coupled to HTTP use case, should not require special hosting,
content types, or HTTP headers being sent
# Non-Goals
- Manifest generation speed
- likely involves IPFS chunking, bittorrent chunking, and several different
cryptographic hash functions over the entirety of each and every file
- Small manifest file size (within reason)
- 30MiB files are "small" these days, given modern storage/bandwidth
- metadata size should not be used as an excuse to sacrifice utility (such
as providing checksums over each chunk of a large file)
# Original Design Questions
These were the open questions when the project started; open design questions
are now tracked only in the [issues](https://git.eeqj.de/sneak/mfer/issues).
- Should the manifest file include checksums of individual file chunks, or just
for the whole assembled file? If so, should the chunk size be fixed or
dynamic? Still open, on
[issue 81](https://git.eeqj.de/sneak/mfer/issues/81#issuecomment-118698).
- Should the manifest signature format be GnuPG signatures, or those from
OpenBSD's signify (of which there is a good
[golang implementation](https://github.com/frankbraun/gosignify))? Still open,
as question 10 on [issue 82](https://git.eeqj.de/sneak/mfer/issues/82).
- Should the on-disk serialization format be proto3 or json? Settled: it is
proto3, see `docs/FORMAT.md` and `mfer/mf.proto`.
# Tool Examples
- `mfer gen` / `mfer gen .`
- recurses under current directory and writes out an `index.mf`
- `mfer check` / `mfer check .`
- verifies checksums of all files in manifest, displaying error and exiting
nonzero if any files are missing or corrupted
- `mfer fetch https://example.com/stuff/`
- fetches `/stuff/index.mf` and downloads all files listed in manifest into
the current directory, or the one given with `--dest`, and assures
cryptographic integrity of downloaded files. A file already there with the
size and hash the manifest lists is skipped. Once every file is in place,
the manifest is saved there as `index.mf`, so `mfer check` can verify the
tree later.
- `mfer fetch --require-signature <fingerprint> https://example.com/stuff/`
- as above, but first refuses a manifest not signed by the key with that
fingerprint, as `mfer check --require-signature` does, before downloading
any file.
# Implementation Plan
## Phase One:
- golang module for reusability/embedding
- golang module client providing `mfer` CLI
## Phase Two:
- ES6 or TypeScript module for reusability/embedding
- ES6/TypeScript module client providing `mfer.js` CLI
# Hopes And Dreams
- `aria2c https://example.com/manifestdirectory/`
- (fetches `https://example.com/manifestdirectory/index.mf`, downloads and
checksums all files, resumes any that exist locally already)
- `mfer fetch https://example.com/manifestdirectory/`
- a command line option to zero/omit mtime/ctime, as well as manifest timestamp,
and sort all directory listings so that manifest file generation is
deterministic/reproducible
- URL format
`mfer fetch https://exmaple.com/manifestdirectory/?key=5539AD00DE4C42F3AFE11575052443F4DF2A55C2`
to assert in the URL which PGP signing key should be used in the manifest, so
that shared URLs have a cryptographic trust root
- a "well-known" key in the manifest that maps well known keys (could reuse the
http spec) to specific file paths in the manifest.
- example: a `berlin.sneak.app.slideshow` key that maps to a json slideshow
config listing what image paths to show, and for how long, and in what
order
# Use Cases
## Web Images
I'd like to be able to put a bunch of images into a directory, generate a
manifest, and then point a slideshow client (such as an ambient display, or a
react app with the target directory in a query string arg) at that statically
hosted directory, and have it discover the full list of images available at that
URL.
## Software Distribution
I'd like to be able to download a whole tree of files available via HTTP
resumably by either HTTP or IPFS/BitTorrent without a .torrent file.
## Filesystem Archive Integrity
I use filesystems that don't include data checksums, and I would like a
cryptographically signed checksum file so that I can later verify that a set of
archive files have not been modified, none are missing, and that the checksums
have not been altered in storage by a second party.
## Filesystem-Independent Checksums
I would like to be able to plug in a hard drive or flash drive and, if there is
an `index.mf` in the root, automatically detect missing/corrupted files,
regardless of filesystem format.
# Collaboration
Please email [`sneak@sneak.berlin`](mailto:sneak@sneak.berlin) with your desired
username for an account on this Gitea instance.
# TODO
Open work, open design questions included, is tracked in this repo's issues:
[https://git.eeqj.de/sneak/mfer/issues](https://git.eeqj.de/sneak/mfer/issues).
# See Also
## Prior Art: Metalink
- [Metalink - Mozilla Wiki](https://wiki.mozilla.org/Metalink)
- [Metalink - Wikipedia](https://en.wikipedia.org/wiki/Metalink)
- [RFC 5854 - The Metalink Download Description Format](https://datatracker.ietf.org/doc/html/rfc5854)
- [RFC 6249 - Metalink/HTTP: Mirrors and Hashes](https://www.rfc-editor.org/rfc/rfc6249.html)
## Links
- Repo: [https://git.eeqj.de/sneak/mfer](https://git.eeqj.de/sneak/mfer)
- Issues:
[https://git.eeqj.de/sneak/mfer/issues](https://git.eeqj.de/sneak/mfer/issues)
# Author
- [@sneak](https://sneak.berlin)
# License
- [WTFPL](https://wtfpl.net)
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