reiver-fediverse/id/syntax.html

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<article>
<h1>Fediverse ID (Fediverse)</h1>
<section>
<address class="h-card">
by
<a rel="author" class="u-url" href="http://changelog.ca/"><span class="p-given-name">Charles</span> <span class="p-additional-name">Iliya</span> <span class="p-family-name">Krempeaux</span></a>
</address>
</section>
<section>
<p>
The final say for what is and is not a valid <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> are the many implementations of <ziba-link transform="lowercase">WebFinger</ziba-link> in-the-wild in all the different <ziba-link transform="lowercase">Fediverse software</ziba-link> out there.
(Which could be different from each other.)
</p>
<p>
Because, from a technical point-of-view, a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> is turned into an <ziba-link>acct URI</ziba-link> and then resolved with <ziba-link transform="lowercase">WebFinger</ziba-link>.
</p>
<p>
Also, there currently is no canonical syntax for a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link>.
Currently, the syntax of a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> is whatever each implementation supports.
(Which again could be different from each other.)
</p>
<p>
But, having said that, we can infer a <em>minimum syntax</em> for what should be considered a valid<ziba-link transform="lowerllamacase">Fediverse ID</ziba-link>.
I.e., the syntax that any implmentation for <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link>s <em>should</em> support.
But, to say it explicitly, an implemention for <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link>s <em>could</em> support more than just what is given by this syntax.
</p>
<section>
<h2>acct URI</h2>
<p>
Part of the process of <strong>resolving</strong> a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> transfomrs a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> into an <ziba-link>acct URI</ziba-link>.
(And then using that <ziba-link>acct URI</ziba-link> version of the <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> makes a request to <ziba-link transform="lowercase">WebFinger</ziba-link>.)
</p>
<p>
Here is an example of transforming a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> into an <ziba-link>acct URI</ziba-link>:
</p>
<pre>
at sign
@joeblow@example.com ← Fediverse ID
acct:joeblow@example.com ← acct URI
no at sign
</pre>
<p>
A client would then make a request to:
</p>
<pre>
https://example.com/.well-known/host-meta
</pre>
<p>
To discover what the (template) URL for <ziba-link transform="lowercase">WebFinger</ziba-link> is.
And then, for example, if it is at:
</p>
<pre>
https://example.com/.well-known/webfinger?resource={uri}
</pre>
<p>
Then make a request to:
</p>
<pre>
https://example.com/.well-known/webfinger?resource=acct:joeblow@example.com
</pre>
</section>
<section>
<h2>Fediverse ID Syntax</h2>
<p>
Inferring from IETF RFC-7565 (The 'acct' URI Scheme) and referenced IEFC RFCs, the syntax of a <ziba-link transform="lowerllamacase">Fediverse ID</ziba-link> is:
</p>
<pre>
fediverseID = "@" actor "@" host
</pre>
<p>
Where “actor” is defined as:
</p>
<pre>
actor = unreserved / sub-delims 0*( unreserved / pct-encoded / sub-delims )
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
pct-encoded = "%" HEXDIG HEXDIG
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39 ; 0-9
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
</pre>
<p>
(Again note that an implementation <em>could</em> support more characters for “actor” than what is given by this definition.)
</p>
<p>
And “host” is defined as
</p>
<pre>
host = IP-literal / IPv4address / reg-name
IP-literal = "[" ( IPv6address / IPvFuture ) "]"
IPv6address = 6( h16 ":" ) ls32
/ "::" 5( h16 ":" ) ls32
/ [ h16 ] "::" 4( h16 ":" ) ls32
/ [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
/ [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
/ [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32
/ [ *4( h16 ":" ) h16 ] "::" ls32
/ [ *5( h16 ":" ) h16 ] "::" h16
/ [ *6( h16 ":" ) h16 ] "::"
h16 = 1*4HEXDIG
ls32 = ( h16 ":" h16 ) / IPv4address
IPvFuture = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255
reg-name = *( unreserved / pct-encoded / sub-delims )
</pre>
</section>
</article>