.Dd $Mdocdate$
.Dt SNAC 5
.Os
.Sh NAME
.Nm snac
.Nd message formatting and file format documentation
.Sh DESCRIPTION
The
.Nm
daemon processes messages from other servers in the Fediverse
using the ActivityPub protocol.
.Pp
This manual describes the allowed formatting of note messages
and the disk storage layout of
.Nm
server and user data. For the operation manual, see
.Xr snac 1 .
For the administration manual, see
.Xr snac 8 .
.Ss Message Formatting
Message notes respect the entered new line breaks rigorously.
A special subset of Markdown is allowed, including:
.Bl -tag -width tenletters
.It bold
**text between two pairs of asterisks**
.It italic
*text between a pair of asterisks*
.It strikethrough text
~~text between two pairs of tildes~~
.It underlined text
__text between two pairs of underscores__
.It code
Text `between backticks` is formatted as code.
.Bd -literal
```
/* text between lines starting with three backticks is preformatted */
int main(int argc, char *argv[])
{
    return 0;
}

```
.Ed
.It links
Standalone URLs are converted to links. Also, from version 2.54,
markdown-style links in the form of [link label](url) are also
supported.
.It attached images
Standalone URLs for which the final extension is recognized as an
image (.jpg, .gif, .png, etc), are converted to ActivityPub image
attachments. Also, from version 2.57, markdown-style image links
in the form of ![alt text](image url) are also supported.
.It line separators
Horizontal rules can be inserted by typing three minus symbols
alone in a line.
.It quoted text
Lines starting with > (blockquotes).
.It bullet points
Lines starting with an asterisk or hyphen, plus a space (unsorted lists).
.It headers
One, two or three # at the beginning of a line plus a space plus
some text are converted to HTML headers.
.It user mentions
Strings in the format @user@host are requested using the Webfinger
protocol and converted to links and mentions if something reasonable
is found.
.It emoticons /emojis / smileys / silly symbols
(Note: from version 2.51, these symbols are configurable by the
instance administrator, so the available ones may differ).
.Pp
The following traditional ASCII emoticons or special strings are
converted to related emojis:
.Bd -literal
:-) :-D X-D ;-) B-) :-( :-* <3 :-/ 8-o
%-) :_( :-| >:-( :facepalm: :shrug: :shrug2:
:eyeroll: :beer: :beers: :munch: :thumb:
.Ed
.El
.Pp
.Ss Accepted HTML
All HTML tags in entries are neutered except the following ones:
.Bd -literal
a p br blockquote ul ol li cite small h2 h3
span i b u s pre code em strong hr img del
.Ed
.Pp
.Ss Disk Layout
This section documents version 2.7 of the disk storage layout.
.Pp
The base directory contains the following files and folders:
.Bl -tag -width tenletters
.It Pa server.json
Server configuration.
.It Pa user/
Directory holding user subdirectories.
.It Pa object/
Directory holding the ActivityPub objects. Filenames are hashes of each
message Id, stored in subdirectories starting with the first two letters
of the hash.
.It Pa queue/
This directory contains the global queue of input/output messages as JSON files.
File names contain timestamps that indicate when the message will
be sent. Messages not accepted by their respective servers will be re-enqueued
for later retransmission until a maximum number of retries is reached,
then discarded.
.It Pa inbox/
Directory storing collected inbox URLs from other instances.
.It Pa archive/
If this directory exists, all input and output messages are logged inside it,
including HTTP headers. Only useful for debugging. May grow to enormous sizes.
.It Pa error/
If this directory exists, HTTP signature check error headers are logged here.
Only useful for debugging.
.It Pa log/
If this directory exists, log messages are also stored there in daily files.
.It Pa app/
This directory stores Mastodon API apps.
.It Pa token/
This directory stores Mastodon API tokens.
.It Pa style.css
The server-wide CSS. The content of this file is inserted into the HTML output
unless a user-specific one exist in the user's
.Pa static/
folder.
.It Pa greeting.html
This file is served when the server base URL is requested from a web browser. See
.Xr snac 8
for more information about the customization options.
.It Pa public.idx
This file contains the list of public posts from all users in the server.
.It Pa filter_reject.txt
This (optional) file contains a list of regular expressions, one per line, to be
applied to the content of all incoming posts; if any of them match, the post is
rejected. This brings the flexibility and destruction power of regular expressions
to your Fediverse experience. To be used wisely (see
.Xr snac 8
for more information).
.It Pa announcement.txt
If this file is present, an announcement will be shown to logged in users
on every page with its contents. It is also available through the Mastodon API.
Users can dismiss the announcement, which works by storing the modification time
in the "last_announcement" field of the
.Pa user.json
file. When the file is modified, the announcement will then reappear. It can
contain only text and will be ignored if it has more than 2048 bytes.
.It Pa server.pid
This file stores the server PID in a single text line.
.El
.Pp
Each user directory is a subdirectory of 
.Pa BASEDIR/user/ ,
has the user id as name and contains the following subdirectories and files:
.Bl -tag -width tenletters
.It Pa user.json
User configuration file.
.It Pa user_o.json
User configuration override file. This file is intended for administrators to
override some user preferences. For current version, the fields that can be
overridden are 'purge_days' and 'email'.
.It Pa key.json
Secret/public key PEM data.
.It Pa followers.idx
This file contains the list of followers as a list of hashed object identifiers.
.It Pa followers/
This directory stores hard links to the actor objects in the object storage.
.It Pa following/
This directory stores the users being followed as hard links to the 'Follow'
or 'Accept' objects in the object storage. File names are the hashes of each
actor Id.
.It Pa private/
This directory stores hard links to the timeline entries in the object storage.
.It Pa private.idx
This file contains the list of timeline entries as a list of hashed
object identifiers.
.It Pa public/
This directory stores hard links to the public timeline entries in the object
storage.
.It Pa public.idx
This file contains the list of public timeline entries as a list of hashed
object identifiers.
.It Pa pinned/
This directory stores hard links to pinned posts.
.It Pa pinned.idx
This file contains the list of pinned posts as a list of hashed
object identifiers.
.It Pa bookmark/
This directory stores hard links to bookmarked posts.
.It Pa bookmark.idx
This file contains the list of pinned posts as a list of hashed
object identifiers.
.It Pa draft/
This directory stores post drafts.
.It Pa draft.idx
This file contains the list of drafts as a list of hashed
object identifiers.
.It Pa muted/
This directory contains files which names are hashes of muted actors. The
content is a line containing the actor URL.
Messages from these actors will be ignored on input and not shown in any timeline.
.It Pa hidden/
This directory contains references to the hidden timeline entries.
.It Pa limited/
This directory contains references to the actor URLs for limited users (those
being followed but with their boosts blocked).
.It Pa queue/
This directory contains the output queue of messages generated by the user as
JSON files. File names contain timestamps that indicate when the message will
be sent. Messages not accepted by their respective servers will be re-enqueued
for later retransmission until a maximum number of retries is reached,
then discarded.
.It Pa static/
Files in this directory are served as-is when requested from the
.Pa https://HOST/USER/s/...
URL path. A special file named
.Pa style.css
can contain user-specific CSS code to be inserted into the HTML of the
web interface.
.It Pa history/
This directory contains generated HTML files. They may be snapshots of the
local timeline in previous months or other cached data.
.It Pa export/
This directory will contain exported data in Mastodon-compatible CSV format
after executing the 'export_csv' command-line operation.
.It Pa import/
Mastodon-compatible CSV files must be copied into this directory to use
any of the importing functions.
.El
.Sh SEE ALSO
.Xr snac 1 ,
.Xr snac 8
.Sh AUTHORS
.An grunfink Lk https://comam.es/snac/grunfink @grunfink@comam.es
.Sh LICENSE
See the LICENSE file for details.