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activitypub-single-php-file/index.php

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PHP
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<?php
/*
* "This code is not a code of honour... no highly esteemed code is commemorated here... nothing valued is here."
* "What is here is dangerous and repulsive to us. This message is a warning about danger."
* This is a rudimentary, single-file, low complexity, minimum functionality, ActivityPub server.
* For educational purposes only.
* The Server produces an Actor who can be followed.
* The Actor can send messages to followers.
* The message can have linkable URls, hashtags, and mentions.
* An image and alt text can be attached to the message.
* The Actor can follow, unfollow, block, and unblock remote accounts.
* The Server saves logs about requests it receives and sends.
* This code is NOT suitable for production use.
* SPDX-License-Identifier: AGPL-3.0-or-later
* This code is also "licenced" under CRAPL v0 - https://matt.might.net/articles/crapl/
* "Any appearance of design in the Program is purely coincidental and should not in any way be mistaken for evidence of thoughtful software construction."
* For more information, please re-read.
*/
// Preamble: Set your details here
// This is where you set up your account's name and bio.
// You also need to provide a public/private keypair.
// The posting page is protected with a password that also needs to be set here.
// Set up the Actor's information
// Edit these:
$username = rawurlencode("example"); // Type the @ username that you want. Do not include an "@".
$realName = "E. Xample. Jr."; // This is the user's "real" name.
$summary = "Some text about the user."; // This is the bio of your user.
// Generate locally or from https://cryptotools.net/rsagen
// Newlines must be replaced with "\n"
$key_private = "-----BEGIN RSA PRIVATE KEY-----\n...\n-----END RSA PRIVATE KEY-----";
$key_public = "-----BEGIN PUBLIC KEY-----\n...\n-----END PUBLIC KEY-----";
// Password for sending messages
$password = "P4ssW0rd";
/** No need to edit anything below here. But please go exploring! **/
// Internal data
$server = $_SERVER["SERVER_NAME"]; // Do not change this!
// Some requests require a User-Agent string.
define( "USERAGENT", "activitypub-single-php-file/0.0" );
// Set up where to save logs, posts, and images.
// You can change these directories to something more suitable if you like.
$data = "data";
$directories = array(
"inbox" => "{$data}/inbox",
"followers" => "{$data}/followers",
"following" => "{$data}/following",
"logs" => "{$data}/logs",
"posts" => "posts",
"images" => "images",
);
// Create the directories if they don't already exist.
foreach ( $directories as $directory ) {
if( !is_dir( $directory ) ) { mkdir( $data ); mkdir( $directory ); }
}
// Get the information sent to this server
$input = file_get_contents( "php://input" );
$body = json_decode( $input,true );
$bodyData = print_r( $body, true );
// If the root has been requested, manually set the path to `/`
!empty( $_GET["path"] ) ? $path = $_GET["path"] : $path = "/";
// Routing:
// The .htaccess changes /whatever to /?path=whatever
// This runs the function of the path requested.
switch ( $path ) {
case ".well-known/webfinger":
webfinger(); // Mandatory. Static.
case ".well-known/nodeinfo":
wk_nodeinfo(); // Optional. Static.
case "nodeinfo/2.1":
nodeinfo(); // Optional. Static.
case rawurldecode( $username ):
case "@" . rawurldecode( $username ): // Some software assumes usernames start with an `@`
username(); // Mandatory. Static
case "following":
following(); // Mandatory. Can be static or dynamic.
case "followers":
followers(); // Mandatory. Can be static or dynamic.
case "inbox":
inbox(); // Mandatory.
case "outbox":
outbox(); // Optional. Dynamic.
case "write":
write(); // User interface for writing posts.
case "action/send":
send(); // API for posting content to the Fediverse.
case "users":
users(); // User interface for (un)following & (un)blocking an external user.
case "action/users":
action_users();// API for following a user.
case "read":
view( "read" );// User interface for reading posts.
case "/":
view( "home" );// User interface for seeing what the user has posted.
default:
die();
}
// The WebFinger Protocol is used to identify accounts.
// It is requested with `example.com/.well-known/webfinger?resource=acct:username@example.com`
// This server only has one user, so it ignores the query string and always returns the same details.
function webfinger() {
global $username, $server;
$webfinger = array(
"subject" => "acct:{$username}@{$server}",
"links" => array(
array(
"rel" => "self",
"type" => "application/activity+json",
"href" => "https://{$server}/{$username}"
)
)
);
header( "Content-Type: application/json" );
echo json_encode( $webfinger );
die();
}
// User:
// Requesting `example.com/username` returns a JSON document with the user's information.
function username() {
global $username, $realName, $summary, $server, $key_public;
$user = array(
"@context" => [
"https://www.w3.org/ns/activitystreams",
"https://w3id.org/security/v1"
],
"id" => "https://{$server}/{$username}",
"type" => "Person",
"following" => "https://{$server}/following",
"followers" => "https://{$server}/followers",
"inbox" => "https://{$server}/inbox",
"outbox" => "https://{$server}/outbox",
"preferredUsername" => rawurldecode( $username ),
"name" => "{$realName}",
"summary" => "{$summary}",
"url" => "https://{$server}/{$username}",
"manuallyApprovesFollowers" => false,
"discoverable" => true,
"published" => "2024-02-29T12:34:56Z",
"icon" => [
"type" => "Image",
"mediaType" => "image/png",
"url" => "https://{$server}/icon.png"
],
"image" => [
"type" => "Image",
"mediaType" => "image/png",
"url" => "https://{$server}/banner.png"
],
"publicKey" => [
"id" => "https://{$server}/{$username}#main-key",
"owner" => "https://{$server}/{$username}",
"publicKeyPem" => $key_public
]
);
header( "Content-Type: application/activity+json" );
echo json_encode( $user );
die();
}
// Follower / Following:
// These JSON documents show how many users are following / followers-of this account.
// The information here is self-attested. So you can lie and use any number you want.
function following() {
global $server, $directories;
// Get all the files
$following_files = glob( $directories["following"] . "/*.json" );
// Number of users
$totalItems = count( $following_files );
// Sort users by most recent first
usort( $following_files, function( $a, $b ) {
return filemtime($b) - filemtime($a);
});
// Create a list of all accounts being followed
$items = array();
foreach ( $following_files as $following_file ) {
$following = json_decode( file_get_contents( $following_file ), true );
$items[] = $following["id"];
}
$following = array(
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/following",
"type" => "Collection",
"totalItems" => $totalItems,
"items" => $items
);
header( "Content-Type: application/activity+json" );
echo json_encode( $following );
die();
}
function followers() {
global $server, $directories;
// The number of followers is self-reported.
// You can set this to any number you like.
// Get all the files
$follower_files = glob( $directories["followers"] . "/*.json" );
// Number of users
$totalItems = count( $follower_files );
// Sort users by most recent first
usort( $follower_files, function( $a, $b ) {
return filemtime($b) - filemtime($a);
});
// Create a list of everyone being followed
$items = array();
foreach ( $follower_files as $follower_file ) {
$following = json_decode( file_get_contents( $follower_file ), true );
$items[] = $following["id"];
}
$followers = array(
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/followers",
"type" => "Collection",
"totalItems" => $totalItems,
"items" => $items
);
header( "Content-Type: application/activity+json" );
echo json_encode( $followers );
die();
}
// Inbox:
// The `/inbox` is the main server. It receives all requests.
function inbox() {
global $body, $server, $username, $key_private, $directories;
// Get the message, type, and ID
$inbox_message = $body;
$inbox_type = $inbox_message["type"];
// This inbox only sends responses to follow requests.
// A remote server sends the inbox a follow request which is a JSON file saying who they are.
// The details of the remote user's server is saved to a file so that future messages can be delivered to the follower.
// An accept request is cryptographically signed and POST'd back to the remote server.
if ( "Follow" == $inbox_type ) {
// Validate HTTP Message Signature
if ( !verifyHTTPSignature() ) { die(); }
// Get the parameters
$follower_id = $inbox_message["id"]; // E.g. https://mastodon.social/(unique id)
$follower_actor = $inbox_message["actor"]; // E.g. https://mastodon.social/users/Edent
// Get the actor's profile as JSON
$follower_actor_details = getDataFromURl( $follower_actor );
// Save the actor's data in `/data/followers/`
$follower_filename = urlencode( $follower_actor );
file_put_contents( $directories["followers"] . "/{$follower_filename}.json", json_encode( $follower_actor_details ) );
// Get the new follower's Inbox
$follower_inbox = $follower_actor_details["inbox"];
// Response Message ID
// This isn't used for anything important so could just be a random number
$guid = uuid();
// Create the Accept message to the new follower
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/{$guid}",
"type" => "Accept",
"actor" => "https://{$server}/{$username}",
"object" => [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => $follower_id,
"type" => $inbox_type,
"actor" => $follower_actor,
"object" => "https://{$server}/{$username}",
]
];
// The Accept is POSTed to the inbox on the server of the user who requested the follow
sendMessageToSingle( $follower_inbox, $message );
} else {
// Messages to ignore.
// Some servers are very chatty. They send lots of irrelevant messages.
// Before even bothering to validate them, we can delete them.
// This server doesn't handle Add, Remove, or Reject
// See https://www.w3.org/wiki/ActivityPub/Primer
if ( "Add" == $inbox_type || "Remove" == $inbox_type || "Reject" == $inbox_type ) {
die();
}
// Messages from accounts which aren't being followed.
// Some servers send delete messages about users we don't follow.
// Lemmy sends messages even after unfollowing or blocking a channel
// Get a list of every account we follow
// Get all the files
$following_files = glob( $directories["following"] . "/*.json");
// Create a list of all accounts being followed
$following_ids = array();
foreach ( $following_files as $following_file ) {
$following = json_decode( file_get_contents( $following_file ), true );
$following_ids[] = $following["id"];
}
// Is this from someone we follow?
in_array( $inbox_message["actor"], $following_ids ) ? $from_following = true: $from_following = false;
// Get a list of every account following us
// Get all the files
$followers_files = glob( $directories["followers"] . "/*.json");
// Create a list of all accounts being followed
$followers_ids = array();
foreach ( $followers_files as $follower_file ) {
$follower = json_decode( file_get_contents( $follower_file ), true );
$followers_ids[] = $follower["id"];
}
// Is this from someone following us?
in_array( $inbox_message["actor"], $followers_ids ) ? $from_follower = true: $from_follower = false;
// Has the user has been specifically CC'd?
if ( isset( $inbox_message["cc"] ) ) {
if ( is_array( $inbox_message["cc"] ) ) {
$reply = in_array( "https://{$server}/{$username}", $inbox_message["cc"] );
} else {
$reply = ( "https://{$server}/{$username}" === $inbox_message["cc"] );
}
} else {
$reply = false;
}
// As long as one of these is true, the server will process it
if ( !$reply && !$from_following && !$from_follower ) {
// Don't bother processing it at all.
die();
}
// Validate HTTP Message Signature
if ( !verifyHTTPSignature() ) { die(); }
// If this is an Undo, Delete, or Update message, try to process it
if ( "Undo" == $inbox_type || "Delete" == $inbox_type || "Update" == $inbox_type ) {
undo( $inbox_message );
}
}
// If the message is valid, save the message in `/data/inbox/`
$uuid = uuid( $inbox_message );
$inbox_filename = $uuid . "." . urlencode( $inbox_type ) . ".json";
file_put_contents( $directories["inbox"] . "/{$inbox_filename}", json_encode( $inbox_message ) );
die();
}
// Unique ID:
// Every message sent should have a unique ID.
// This can be anything you like. Some servers use a random number.
// I prefer a date-sortable string.
function uuid( $message = null) {
// UUIDs that this server *sends* will be [timestamp]-[random]
// 65e99ab4-5d43-f074-b43e-463f9c5cf05c
if ( is_null( $message ) ) {
return sprintf( "%08x-%04x-%04x-%04x-%012x",
time(),
mt_rand(0, 0xffff),
mt_rand(0, 0xffff),
mt_rand(0, 0x3fff) | 0x8000,
mt_rand(0, 0xffffffffffff)
);
} else {
// UUIDs that this server *saves* will be [timestamp]-[hash of message ID]
// 65eadace-8f434346648f6b96df89dda901c5176b10a6d83961dd3c1ac88b59b2dc327aa4
// The message might have its own object
if ( isset( $message["object"]["id"] ) ) {
$id = $message["object"]["id"];
} else {
$id = $message["id"];
}
return sprintf( "%08x", time() ) . "-" . hash( "sha256", $id );
}
}
// Headers:
// Every message that your server sends needs to be cryptographically signed with your Private Key.
// This is a complicated process.
// Please read https://blog.joinmastodon.org/2018/07/how-to-make-friends-and-verify-requests/ for more information.
function generate_signed_headers( $message, $host, $path, $method ) {
global $server, $username, $key_private;
// Location of the Public Key
$keyId = "https://{$server}/{$username}#main-key";
// Get the Private Key
$signer = openssl_get_privatekey( $key_private );
// Timestamp this message was sent
$date = date( "D, d M Y H:i:s \G\M\T" );
// There are subtly different signing requirements for POST and GET.
if ( "POST" == $method ) {
// Encode the message object to JSON
$message_json = json_encode( $message );
// Generate signing variables
$hash = hash( "sha256", $message_json, true );
$digest = base64_encode( $hash );
// Sign the path, host, date, and digest
$stringToSign = "(request-target): post $path\nhost: $host\ndate: $date\ndigest: SHA-256=$digest";
// The signing function returns the variable $signature
// https://www.php.net/manual/en/function.openssl-sign.php
openssl_sign(
$stringToSign,
$signature,
$signer,
OPENSSL_ALGO_SHA256
);
// Encode the signature
$signature_b64 = base64_encode( $signature );
// Full signature header
$signature_header = 'keyId="' . $keyId . '",algorithm="rsa-sha256",headers="(request-target) host date digest",signature="' . $signature_b64 . '"';
// Header for POST request
$headers = array(
"Host: {$host}",
"Date: {$date}",
"Digest: SHA-256={$digest}",
"Signature: {$signature_header}",
"Content-Type: application/activity+json",
"Accept: application/activity+json",
);
} else if ( "GET" == $method ) {
// Sign the path, host, date - NO DIGEST because there's no message sent.
$stringToSign = "(request-target): get $path\nhost: $host\ndate: $date";
// The signing function returns the variable $signature
// https://www.php.net/manual/en/function.openssl-sign.php
openssl_sign(
$stringToSign,
$signature,
$signer,
OPENSSL_ALGO_SHA256
);
// Encode the signature
$signature_b64 = base64_encode( $signature );
// Full signature header
$signature_header = 'keyId="' . $keyId . '",algorithm="rsa-sha256",headers="(request-target) host date",signature="' . $signature_b64 . '"';
// Header for GET request
$headers = array(
"Host: {$host}",
"Date: {$date}",
"Signature: {$signature_header}",
"Accept: application/activity+json, application/json",
);
}
return $headers;
}
// User Interface for Homepage.
// This creates a basic HTML page. This content appears when someone visits the root of your site.
function view( $style ) {
global $username, $server, $realName, $summary, $directories;
$rawUsername = rawurldecode( $username );
// What sort of viewable page is this?
switch ( $style ) {
case "home":
$h1 = "HomePage";
$directory = "posts";
break;
case "read":
$h1 = "InBox";
$directory = "inbox";
break;
}
// Counters for followers, following, and posts
$follower_files = glob( $directories["followers"] . "/*.json" );
$totalFollowers = count( $follower_files );
$following_files = glob( $directories["following"] . "/*.json" );
$totalFollowing = count( $following_files );
// Show the HTML page
echo <<< HTML
<!DOCTYPE html>
<html lang="en-GB">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta property="og:url" content="https://{$server}">
<meta property="og:type" content="website">
<meta property="og:title" content="{$realName}">
<meta property="og:description" content="{$summary}">
<meta property="og:image" content="https://{$server}/banner.png">
<title>{$h1} {$realName}</title>
<style>
* { max-width: 100%; }
body { margin:0; padding: 0; font-family:sans-serif; }
@media screen and (max-width: 800px) { body { width: 100%; }}
@media screen and (min-width: 799px) { body { width: 800px; margin: 0 auto; }}
address { font-style: normal; }
img { max-width: 50%; }
.h-feed { margin:auto; width: 100%; }
.h-feed > header { text-align: center; margin: 0 auto; }
.h-feed .banner { text-align: center; margin:0 auto; max-width: 650px; }
.h-feed > h1, .h-feed > h2 { margin-top: 10px; margin-bottom: 0; }
.h-feed > header > h1:has(span.p-author), h2:has(a.p-nickname) { word-wrap: break-word; max-width: 90%; padding-left:20px; }
.h-feed .u-feature:first-child { margin-top: 10px; margin-bottom: -150px; max-width: 100%;}
.h-feed .u-photo { max-height: 8vw; max-width:100%; min-height: 120px; }
.h-feed .about { font-size: smaller; background-color: #F5F5F5; padding: 10px; border-top: dotted 1px #808080; border-bottom: dotted 1px #808080; }
.h-feed > ul { padding-left: 0; list-style-type: none; }
.h-feed > ul > li { padding: 10px; border-bottom: dotted 1px #808080; }
.h-entry { padding-right: 10px; }
.h-entry time { font-weight: bold; }
.h-entry .e-content a { word-wrap: break-word; }
</style>
</head>
<body>
<main class="h-feed">
<header>
<div class="banner">
<img src="banner.png" alt="" class="u-feature"><br>
<img src="icon.png" alt="icon" class="u-photo">
</div>
<address>
<h1 class="p-name p-author">{$realName}</h1>
<h2><a class="p-nickname u-url" rel="author" href="https://{$server}/{$username}">@{$rawUsername}@{$server}</a></h2>
</address>
<p class="p-summary">{$summary}</p>
<p>Following: {$totalFollowing} | Followers: {$totalFollowers}</p>
<div class="about">
<p><a href="https://gitlab.com/edent/activitypub-single-php-file/">This software is licenced under AGPL 3.0</a>.</p>
<p>This site is a basic <a href="https://www.w3.org/TR/activitypub/">ActivityPub</a> server designed to be <a href="https://shkspr.mobi/blog/2024/02/activitypub-server-in-a-single-file/">a lightweight educational tool</a>.</p>
</div>
</header>
<ul>
HTML;
// Get all the files in the directory
$message_files = array_reverse( glob( $directories[$directory] . "/*.json") );
// There are lots of messages. The UI will only show 200.
// However, there will be lots of duplicates, updates, etc.
// This looks through the most recent 1,000
$message_files = array_slice( $message_files, 0, 1000 );
// Loop through the messages:
// Ensure messages are in the right order.
$messages_ordered = [];
foreach ( $message_files as $message_file ) {
// Split the filename
$file_parts = explode(".", $message_file );
$type = $file_parts[1];
// Ignore any messages which aren't for display
if ( "Undo" == $type || "Delete" == $type ) { continue; }
// Get the contents of the JSON
$message = json_decode( file_get_contents( $message_file ), true );
// Sometimes messages are received out of order.
// This sorts them by their published time or, if there is none, the received time.
// Use the timestamp of the message. If there is none, use the date in the filename
if ( isset( $message["published"] ) ) {
$published = $message["published"];
} else {
$segments = explode( "/", explode( "-", $message_file ?? "" )[0]);
$published_hexstamp = end( $segments );
$published_time = hexdec( $published_hexstamp );
$published = date( "c", $published_time );
}
// Place in an array where the key is the timestamp
$messages_ordered[$published] = $message;
}
// Sort with newest on top
krsort( $messages_ordered );
// Only keep the most recent 200
$messages_ordered = array_slice( $messages_ordered, 0, 200 );
// HTML is *probably* sanitised by the sender. But let's not risk it, eh?
// Using the allow-list from https://docs.joinmastodon.org/spec/activitypub/#sanitization
$allowed_elements = ["p", "span", "br", "a", "del", "pre", "code", "em", "strong", "b", "i", "u", "ul", "ol", "li", "blockquote"];
// Print the items in a list
foreach ( $messages_ordered as $published=>$message ) {
// Received messages have an `object` which contains their data.
// Sent messages *are* their data
if ( isset( $message["object"] ) ) {
$object = $message["object"];
} else {
$object = $message;
}
if ( isset( $object["id"] ) ) {
$id = $object["id"];
$publishedHTML = "<a href=\"{$id}\">{$published}</a>";
} else {
$id = "";
$publishedHTML = $published;
}
// For displaying the post's information
$timeHTML = "<time datetime=\"{$published}\" class=\"u-url\" rel=\"bookmark\">{$publishedHTML}</time>";
// Get the actor who authored the message
if ( isset( $object["attributedTo"] ) ) {
$actor = $object["attributedTo"];
} else if ( isset( $message["actor"] ) ) {
// Usually found in Like and Announce messages
$actor = $message["actor"];
} else {
// Should never happen!
$actor = "https://example.com/anonymous";
}
// Assume that what comes after the final `/` in the URl is the name
$actorArray = explode( "/", $actor );
$actorName = end( $actorArray );
$actorServer = parse_url( $actor, PHP_URL_HOST );
$actorUsername = "@{$actorName}@{$actorServer}";
// Make i18n usernames readable and safe.
$actorName = htmlspecialchars( rawurldecode( $actorName ) );
$actorHTML = "<a href=\"$actor\">@{$actorName}</a>";
// Buttons to interact with a message.
// By default, just shows a "Follow User" button.
if ( "read" == $style ) {
$interactHTML = "<a href=\"/users?account=$actorUsername\">👤</a> ";
} else {
$interactHTML = "";
}
// What type of message is this?
$type = $message["type"];
// Render the message according to type
if ( "Create" == $type || "Update" == $type || "Note" == $type ) {
// Get the HTML content
// There is a slight difference between the formatting of sent and received messages
if ( "Note" == $type ) {
$content = $message["content"];
} else {
// If there is a content node
if ( isset ( $object["content"] ) ) {
$content = $object["content"];
} else {
// Anything weird will just get dumped to screen
htmlspecialchars( print_r( $object, true ) );
}
}
// Sanitise the HTML
$content = strip_tags( $content, $allowed_elements );
// Is this a reply to something?
if ( isset( $object["inReplyTo"] ) ) {
$replyToURl = $object["inReplyTo"];
$replyTo = "in reply to <a href=\"{$replyToURl}\">$replyToURl</a>";
} else {
$replyTo = "";
}
// Has the user has been specifically CC'd?
if ( isset( $object["cc"] ) ) {
$reply = in_array( "https://{$server}/{$username}", $object["cc"] );
} else {
$reply = false;
}
// Is there is a Content Warning?
if ( isset( $object["summary"] ) ) {
$summary = $object["summary"];
$summary = strip_tags( $summary, $allowed_elements );
// Hide the content until the user interacts with it.
$content = "<details><summary>{$summary}</summary>{$content}</details>";
}
// Is there a poll?
// ActivityPub specification - https://www.w3.org/TR/activitystreams-vocabulary/#questions
// Mastodon documentation - https://docs.joinmastodon.org/spec/activitypub/#Question
if ( isset( $object["oneOf"] ) ) {
$content .= "<h3>Poll Results:</h3>";
foreach ( $object["oneOf"] as $pollOption ) {
$pollOptionName = htmlspecialchars( $pollOption["name"] );
$pollOptionValue = htmlspecialchars( $pollOption["replies"]["totalItems"] );
$content .= "{$pollOptionName}: $pollOptionValue<br>";
}
}
if ( isset( $object["anyOf"] ) ) {
$content .= "<h3>Poll Results</h3>";
foreach ( $object["anyOf"] as $pollOption ) {
$pollOptionName = htmlspecialchars( $pollOption["name"] );
$pollOptionValue = htmlspecialchars( $pollOption["replies"]["totalItems"] );
$content .= "{$pollOptionName}: $pollOptionValue<br>";
}
}
// Add any images
if ( isset( $object["attachment"] ) ) {
foreach ( $object["attachment"] as $attachment ) {
// Only use things which have a MIME Type set
if ( isset( $attachment["mediaType"] ) ) {
$mediaURl = $attachment["url"];
$mime = $attachment["mediaType"];
// Use the first half of the MIME Type.
// For example `image/png` or `video/mp4`
$mediaType = explode( "/", $mime )[0];
if ( "image" == $mediaType ) {
// Get the alt text
isset( $attachment["name"] ) ? $alt = $attachment["name"] : $alt = "";
$content .= "<img src='{$mediaURl}' alt='{$alt}'>";
} else if ( "video" == $mediaType ) {
$content .= "<video controls><source src='{$mediaURl}' type='{$mime}'></video>";
}else if ( "audio" == $mediaType ) {
$content .= "<audio controls src='{$mediaURl}' type='{$mime}'></audio>";
}
}
}
}
// What sort of message is this?
switch ( $type ) {
case "Create":
case "Note":
$verb = "wrote";
break;
case "Update":
$verb = "updated";
break;
default:
$verb = "said";
break;
}
// Add some interaction buttons
$interactHTML .= "<a href=\"/write?reply=$id\">↩️</a> " .
"<a href=\"/write?announce=$id\">🔁</a> " .
"<a href=\"/write?like=$id\">⚝</a> ";
if ( $reply ) {
// Highlight that this is a reply
$messageHTML = "<mark>{$timeHTML} {$actorHTML} {$verb} {$replyTo}:</mark> <blockquote class=\"e-content\">{$content}</blockquote>";
} else {
$messageHTML = "{$timeHTML} {$actorHTML} {$verb} {$replyTo}: <blockquote class=\"e-content\">{$content}</blockquote>";
}
} else if ( "Follow" == $type ) {
$messageHTML = "<mark>{$timeHTML} {$actorHTML} followed you</mark>";
} else if ( "Like" == $type ) {
$object = $message["object"];
$objectHTML = "<a href=\"$object\">{$object}</a>";
$messageHTML = "{$timeHTML} {$actorHTML} liked {$objectHTML}";
} else if ( "Announce" == $type ) {
$object = $message["object"];
$objectHTML = "<a href=\"$object\">{$object}</a>";
$messageHTML = "{$timeHTML} {$actorHTML} boosted {$objectHTML}";
} else {
// Not a message we're interested in displaying. Probably a delete or undo.
continue;
}
// Display the message
echo "<li><article class=\"h-entry\">{$messageHTML}<br>{$interactHTML}</article></li>";
}
echo <<< HTML
</ul>
</main>
</body>
</html>
HTML;
die();
}
// User Interface for Writing:
// This creates a basic HTML form. Type in your message and your password. It then POSTs the data to the `/action/send` endpoint.
function write() {
$send = "/action/send";
if ( isset( $_GET["announce"] ) && filter_var( $_GET["announce"], FILTER_VALIDATE_URL ) ) {
$announceURl = $_GET["announce"];
} else {
$announceURl = "";
}
if ( isset( $_GET["like"] ) && filter_var( $_GET["like"], FILTER_VALIDATE_URL ) ) {
$likeURl = $_GET["like"];
} else {
$likeURl = "";
}
if ( isset( $_GET["reply"] ) && filter_var( $_GET["reply"], FILTER_VALIDATE_URL ) ) {
$replyURl = $_GET["reply"];
} else {
$replyURl = "";
}
echo <<< HTML
<!DOCTYPE html>
<html lang="en-GB">
<head>
<meta charset="UTF-8">
<title>Send Message</title>
<style>
*{font-family:sans-serif;font-size:1.1em;}
</style>
</head>
<body>
<fieldset>
<legend>Send a message</legend>
<form action="{$send}" method="post" enctype="multipart/form-data">
<input type="hidden" id="type" name="type" value="Create">
<label for="content">Your message:</label><br>
<textarea id="content" name="content" rows="5" cols="32"></textarea><br>
<label for="inReplyTo">Reply to URl:</label>
<input type="url" name="inReplyTo" id="inReplyTo" size="32" value="{$replyURl}"><br>
<label for="image">Attach an image</label><br>
<input type="file" name="image" id="image" accept="image/*"><br>
<label for="alt">Alt Text</label>
<input type="text" name="alt" id="alt" size="32" /><br>
<label for="password">Password</label><br>
<input type="password" name="password" id="password" size="32"><br><br>
<input type="submit" value="Post Message">
</form>
</fieldset>
<fieldset>
<legend>Like a post</legend>
<form action="{$send}" method="post" enctype="multipart/form-data">
<input type="hidden" id="type" name="type" value="Like">
<label for="postURl">URl of post to like:</label>
<input type="url" name="postURl" id="postURl" size="32" value="{$likeURl}"><br>
<label for="password">Password</label><br>
<input type="password" name="password" id="password" size="32"><br><br>
<input type="submit" value="Like the message">
</form>
</fieldset>
<fieldset>
<legend>Boost a post</legend>
<form action="{$send}" method="post" enctype="multipart/form-data">
<input type="hidden" id="type" name="type" value="Announce">
<label for="postURl">URl of post to boost:</label>
<input type="url" name="postURl" id="postURl" size="32" value="{$announceURl}"><br>
<label for="password">Password</label><br>
<input type="password" name="password" id="password" size="32"><br><br>
<input type="submit" value="Boost the Message">
</form>
</fieldset>
</body>
</html>
HTML;
die();
}
// Send Endpoint:
// This takes the submitted message and checks the password is correct.
// It reads all the followers' data in `data/followers`.
// It constructs a list of shared inboxes and unique inboxes.
// It sends the message to every server that is following this account.
function send() {
global $password, $server, $username, $key_private, $directories;
// Does the posted password match the stored password?
if( $password != $_POST["password"] ) { echo "Wrong password."; die(); }
// What sort of message is being sent?
$type = $_POST["type"];
// Likes and Announces have an identical message structure
if ( "Like" == $type || "Announce" == $type ) {
// Was a URl sent?
if ( isset( $_POST["postURl"] ) && filter_var( $_POST["postURl"], FILTER_VALIDATE_URL ) ) {
$postURl = $_POST["postURl"];
} else {
echo "No valid URl sent.";
die();
}
if ( "Like" == $type ) {
// The message will need to be sent to the inbox of the author of the message
$inbox_single = getInboxFromMessageURl( $postURl );
}
// Outgoing Message ID
$guid = uuid();
// Construct the Message
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/posts/{$guid}.json",
"type" => $type,
"actor" => "https://{$server}/{$username}",
"published"=> date( "c" ),
"object" => $postURl
];
// Announces are sent to an audience
// The audience is public and it is sent to all followers
// TODO: Let the original poster know we boosted them
if ( $type == "Announce" ) {
$message = array_merge( $message,
array(
"to" => ["https://www.w3.org/ns/activitystreams#Public"],
"cc" => ["https://{$server}/followers"])
);
}
// Construct the Note
// This is for saving in the logs
$note = $message;
} else if ( $type == "Create" ) {
// Get the posted content
$content = $_POST["content"];
// Is this a reply?
if ( isset( $_POST["inReplyTo"] ) && filter_var( $_POST["inReplyTo"], FILTER_VALIDATE_URL ) ) {
$inReplyTo = $_POST["inReplyTo"];
} else {
$inReplyTo = null;
}
// Process the content into HTML to get hashtags etc
list( "HTML" => $content, "TagArray" => $tags ) = process_content( $content );
// Is there an image attached?
if ( isset( $_FILES['image']['tmp_name'] ) && ( "" != $_FILES['image']['tmp_name'] ) ) {
// Get information about the image
$image = $_FILES['image']['tmp_name'];
$image_info = getimagesize( $image );
$image_ext = image_type_to_extension( $image_info[2] );
$image_mime = $image_info["mime"];
// Files are stored according to their hash
// A hash of "abc123" is stored in "/images/abc123.jpg"
$sha1 = sha1_file( $image );
$image_full_path = $directories["images"] . "/{$sha1}.{$image_ext}";
// Move media to the correct location
move_uploaded_file( $image, $image_full_path );
// Get the alt text
if ( isset( $_POST["alt"] ) ) {
$alt = $_POST["alt"];
} else {
$alt = "";
}
// Construct the attachment value for the post
$attachment = array( [
"type" => "Image",
"mediaType" => "{$image_mime}",
"url" => "https://{$server}/{$image_full_path}",
"name" => $alt
] );
} else {
$attachment = [];
}
// Current time - ISO8601
$timestamp = date( "c" );
// Outgoing Message ID
$guid = uuid();
// Construct the Note
// `contentMap` is used to prevent unnecessary "translate this post" pop ups
// hardcoded to English
$note = [
"@context" => array(
"https://www.w3.org/ns/activitystreams"
),
"id" => "https://{$server}/posts/{$guid}.json",
"type" => "Note",
"published" => $timestamp,
"attributedTo" => "https://{$server}/{$username}",
"inReplyTo" => $inReplyTo,
"content" => $content,
"contentMap" => ["en" => $content],
"to" => ["https://www.w3.org/ns/activitystreams#Public"],
"tag" => $tags,
"attachment" => $attachment
];
// Construct the Message
// The audience is public and it is sent to all followers
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/posts/{$guid}.json",
"type" => "Create",
"actor" => "https://{$server}/{$username}",
"to" => [
"https://www.w3.org/ns/activitystreams#Public"
],
"cc" => [
"https://{$server}/followers"
],
"object" => $note
];
}
// Save the permalink
$note_json = json_encode( $note );
file_put_contents( $directories["posts"] . "/{$guid}.json", print_r( $note_json, true ) );
// Is this message going to one user? (Usually a Like)
if ( isset( $inbox_single ) ) {
$messageSent = sendMessageToSingle( $inbox_single, $message );
} else { // Send to all the user's followers
$messageSent = sendMessageToFollowers( $message );
}
// Render the JSON so the user can see the POST has worked
if ( $messageSent ) {
header( "Location: https://{$server}/posts/{$guid}.json" );
die();
} else {
echo "ERROR!";
die();
}
}
// POST a signed message to a single inbox
function sendMessageToSingle( $inbox, $message ) {
global $directories;
$inbox_host = parse_url( $inbox, PHP_URL_HOST );
$inbox_path = parse_url( $inbox, PHP_URL_PATH );
// Generate the signed headers
$headers = generate_signed_headers( $message, $inbox_host, $inbox_path, "POST" );
// POST the message and header to the requester's inbox
$ch = curl_init( $inbox );
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_CUSTOMREQUEST, "POST" );
curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $message ) );
curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers );
curl_setopt( $ch, CURLOPT_USERAGENT, USERAGENT );
curl_exec( $ch );
// Check for errors
if( curl_errno( $ch ) ) {
$timestamp = ( new DateTime() )->format( DATE_RFC3339_EXTENDED );
file_put_contents( $directories["logs"] . "/{$timestamp}.Error.txt", curl_error( $ch ) );
return false;
}
curl_close( $ch );
return true;
}
// POST a signed message to the inboxes of all followers
function sendMessageToFollowers( $message ) {
global $directories;
// Read existing followers
$followers = glob( $directories["followers"] . "/*.json" );
// Get all the inboxes
$inboxes = [];
foreach ( $followers as $follower ) {
// Get the data about the follower
$follower_info = json_decode( file_get_contents( $follower ), true );
// Some servers have "Shared inboxes"
// If you have lots of followers on a single server, you only need to send the message once.
if( isset( $follower_info["endpoints"]["sharedInbox"] ) ) {
$sharedInbox = $follower_info["endpoints"]["sharedInbox"];
if ( !in_array( $sharedInbox, $inboxes ) ) {
$inboxes[] = $sharedInbox;
}
} else {
// If not, use the individual inbox
$inbox = $follower_info["inbox"];
if ( !in_array( $inbox, $inboxes ) ) {
$inboxes[] = $inbox;
}
}
}
// Prepare to use the multiple cURL handle
// This makes it more efficient to send many simultaneous messages
$mh = curl_multi_init();
// Loop through all the inboxes of the followers
// Each server needs its own cURL handle
// Each POST to an inbox needs to be signed separately
foreach ( $inboxes as $inbox ) {
$inbox_host = parse_url( $inbox, PHP_URL_HOST );
$inbox_path = parse_url( $inbox, PHP_URL_PATH );
// Generate the signed headers
$headers = generate_signed_headers( $message, $inbox_host, $inbox_path, "POST" );
// POST the message and header to the requester's inbox
$ch = curl_init( $inbox );
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_CUSTOMREQUEST, "POST" );
curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $message ) );
curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers );
curl_setopt( $ch, CURLOPT_USERAGENT, USERAGENT );
// Add the handle to the multi-handle
curl_multi_add_handle( $mh, $ch );
}
// Execute the multi-handle
do {
$status = curl_multi_exec( $mh, $active );
if ( $active ) {
curl_multi_select( $mh );
}
} while ( $active && $status == CURLM_OK );
// Close the multi-handle
curl_multi_close( $mh );
return true;
}
// Content can be plain text. But to add clickable links and hashtags, it needs to be turned into HTML.
// Tags are also included separately in the note
function process_content( $content ) {
global $server;
// Convert any URls into hyperlinks
$link_pattern = '/\bhttps?:\/\/\S+/iu'; // Sloppy regex
$replacement = function ( $match ) {
$url = htmlspecialchars( $match[0], ENT_QUOTES, "UTF-8" );
return "<a href=\"$url\">$url</a>";
};
$content = preg_replace_callback( $link_pattern, $replacement, $content );
// Get any hashtags
$hashtags = [];
$hashtag_pattern = '/(?:^|\s)\#(\w+)/'; // Beginning of string, or whitespace, followed by #
preg_match_all( $hashtag_pattern, $content, $hashtag_matches );
foreach ( $hashtag_matches[1] as $match ) {
$hashtags[] = $match;
}
// Construct the tag value for the note object
$tags = [];
foreach ( $hashtags as $hashtag ) {
$tags[] = array(
"type" => "Hashtag",
"name" => "#{$hashtag}",
);
}
// Add HTML links for hashtags into the text
// Todo: Make these links do something.
$content = preg_replace(
$hashtag_pattern,
" <a href='https://{$server}/tag/$1'>#$1</a>",
$content
);
// Detect user mentions
$usernames = [];
$usernames_pattern = '/@(\S+)@(\S+)/'; // This is a *very* sloppy regex
preg_match_all( $usernames_pattern, $content, $usernames_matches );
foreach ( $usernames_matches[0] as $match ) {
$usernames[] = $match;
}
// Construct the mentions value for the note object
// This goes in the generic "tag" property
// TODO: Add this to the CC field & appropriate inbox
foreach ( $usernames as $username ) {
list( , $user, $domain ) = explode( "@", $username );
$tags[] = array(
"type" => "Mention",
"href" => "https://{$domain}/@{$user}",
"name" => "{$username}"
);
// Add HTML links to usernames
$username_link = "<a href=\"https://{$domain}/@{$user}\">$username</a>";
$content = str_replace( $username, $username_link, $content );
}
// Construct HTML breaks from carriage returns and line breaks
$linebreak_patterns = array( "\r\n", "\r", "\n" ); // Variations of line breaks found in raw text
$content = str_replace( $linebreak_patterns, "<br/>", $content );
// Construct the content
$content = "<p>{$content}</p>";
return [
"HTML" => $content,
"TagArray" => $tags
];
}
// When given the URl of a post, this looks up the post, finds the user, then returns their inbox or shared inbox
function getInboxFromMessageURl( $url ) {
// Get details about the message
$messageData = getDataFromURl( $url );
// The author is the user who the message is attributed to
if ( isset ( $messageData["attributedTo"] ) && filter_var( $messageData["attributedTo"], FILTER_VALIDATE_URL) ) {
$profileData = getDataFromURl( $messageData["attributedTo"] );
} else {
return null;
}
// Get the shared inbox or personal inbox
if( isset( $profileData["endpoints"]["sharedInbox"] ) ) {
$inbox = $profileData["endpoints"]["sharedInbox"];
} else {
// If not, use the individual inbox
$inbox = $profileData["inbox"];
}
// Return the destination inbox if it is valid
if ( filter_var( $inbox, FILTER_VALIDATE_URL) ) {
return $inbox;
} else {
return null;
}
}
// GET a request to a URl and returns structured data
function getDataFromURl ( $url ) {
// Check this is a valid https address
if(
( filter_var( $url, FILTER_VALIDATE_URL) != true) ||
( parse_url( $url, PHP_URL_SCHEME ) != "https" )
) { die(); }
// Split the URL
$url_host = parse_url( $url, PHP_URL_HOST );
$url_path = parse_url( $url, PHP_URL_PATH );
// Generate signed headers for this request
$headers = generate_signed_headers( null, $url_host, $url_path, "GET" );
// Set cURL options
$ch = curl_init( $url );
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_FOLLOWLOCATION, true );
curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers );
curl_setopt( $ch, CURLOPT_USERAGENT, USERAGENT );
// Execute the cURL session
$urlJSON = curl_exec( $ch );
// Check for errors
if (curl_errno( $ch )) {
// Handle cURL error
die();
}
// Close cURL session
curl_close( $ch );
return json_decode( $urlJSON, true );
}
// The Outbox contains a date-ordered list (newest first) of all the user's posts
// This is optional.
function outbox() {
global $server, $username, $directories;
// Get all posts
$posts = array_reverse( glob( $directories["posts"] . "/*.json") );
// Number of posts
$totalItems = count( $posts );
// Create an ordered list
$orderedItems = [];
foreach ( $posts as $post ) {
$postData = json_decode( file_get_contents( $post ), true );
$orderedItems[] = array(
"type" => $postData["type"],
"actor" => "https://{$server}/{$username}",
"object" => "https://{$server}/{$post}"
);
}
// Create User's outbox
$outbox = array(
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/outbox",
"type" => "OrderedCollection",
"totalItems" => $totalItems,
"summary" => "All the user's posts",
"orderedItems" => $orderedItems
);
// Render the page
header( "Content-Type: application/activity+json" );
echo json_encode( $outbox );
die();
}
// This creates a UI for the user to follow another user
function users() {
if ( isset( $_GET["account"] ) ) {
$accountURl = htmlspecialchars( $_GET["account"] );
} else {
$accountURl = "";
}
echo <<< HTML
<!DOCTYPE html>
<html lang="en-GB">
<head>
<meta charset="UTF-8">
<title>Follow</title>
<style>
*{font-family:sans-serif;font-size:1.1em;}
</style>
</head>
<body>
<form action="/action/users" method="post" enctype="multipart/form-data">
<label for="user">User:</label>
<input name="user" id="user" type="text" size="32" placeholder="@user@example.com" value="{$accountURl}"><br>
<label for="action">action</label><br>
<select name="action" id="action">
<option value="">--Please choose an option--</option>
<option value="Follow">Follow</option>
<option value="Unfollow">Unfollow</option>
<option value="Block">Block</option>
<option value="Unblock">Unblock</option>
</select><br>
<label for="password">Password</label><br>
<input name="password" id="password" type="password" size="32"><br>
<input type="submit" value="Send User Request">
</form>
</body>
</html>
HTML;
die();
}
// This receives a request to follow an external user
// It looks up the external user's details
// Then it sends a follow request
// If the request is accepted, it saves the details in `data/following/` as a JSON file
function action_users() {
global $password, $server, $username, $key_private, $directories;
// Does the posted password match the stored password?
if( $password != $_POST["password"] ) { echo "Wrong Password!"; die(); }
// Get the posted content
$user = $_POST["user"];
$action = $_POST["action"];
// Is this a valid action?
if ( match( $action ) {
"Follow", "Unfollow", "Block", "Unblock" => false,
default => true,
} ) {
// Discard it, no further processing.
echo "{$action} not supported";
die();
}
// Split the user (@user@example.com) into username and server
list( , $follow_name, $follow_server ) = explode( "@", $user );
// Get the Webfinger
// This request does not always need to be signed, but safest to do so anyway.
$webfingerURl = "https://{$follow_server}/.well-known/webfinger?resource=acct:{$follow_name}@{$follow_server}";
$webfinger = getDataFromURl( $webfingerURl );
// Get the link to the user
foreach( $webfinger["links"] as $link ) {
if ( "self" == $link["rel"] ) {
$profileURl = $link["href"];
}
}
if ( !isset( $profileURl ) ) { echo "No profile" . print_r( $webfinger, true ); die(); }
// Get the user's details
$profileData = getDataFromURl( $profileURl );
// Get the user's inbox
$profileInbox = $profileData["inbox"];
// Create a user request
$guid = uuid();
// Different user actions have subtly different messages to send.
if ( "Follow" == $action ) {
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/{$guid}",
"type" => "Follow",
"actor" => "https://{$server}/{$username}",
"object" => $profileURl
];
} else if ( "Unfollow" == $action ) {
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/{$guid}",
"type" => "Undo",
"actor" => "https://{$server}/{$username}",
"object" => array(
//"id" => null, // Should be the original ID if possible, but not necessary https://www.w3.org/wiki/ActivityPub/Primer/Referring_to_activities
"type" => "Follow",
"actor" => "https://{$server}/{$username}",
"object" => $profileURl
)
];
} else if ( "Block" == $action ) {
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/{$guid}",
"type" => "Block",
"actor" => "https://{$server}/{$username}",
"object" => $profileURl,
"to" => $profileURl
];
} else if ( "Unblock" == $action ) {
$message = [
"@context" => "https://www.w3.org/ns/activitystreams",
"id" => "https://{$server}/{$guid}",
"type" => "Undo",
"actor" => "https://{$server}/{$username}",
"object" => array(
//"id" => null, // Should be the original ID if possible, but not necessary https://www.w3.org/wiki/ActivityPub/Primer/Referring_to_activities
"type" => "Block",
"actor" => "https://{$server}/{$username}",
"object" => $profileURl
)
];
}
// Sign & send the request
sendMessageToSingle( $profileInbox, $message );
if ( "Follow" == $action ) {
// Save the user's details
$following_filename = urlencode( $profileURl );
file_put_contents( $directories["following"] . "/{$following_filename}.json", json_encode( $profileData ) );
// Render the JSON so the user can see the POST has worked
header( "Location: https://{$server}/data/following/" . urlencode( $following_filename ) . ".json" );
} else if ( "Block" == $action || "Unfollow" == $action ) {
// Delete the user if they exist in the following directory.
$following_filename = urlencode( $profileURl );
unlink( $directories["following"] . "/{$following_filename}.json" );
// Let the user know it worked
echo "{$user} {$action}ed!";
} else if ( "Unblock" == $action ) {
// Let the user know it worked
echo "{$user} {$action}ed!";
}
die();
}
// Verify the signature sent with the message.
// This is optional
// It is very confusing
function verifyHTTPSignature() {
global $input, $body, $server, $directories;
// What type of message is this? What's the time now?
// Used in the log filename.
$type = urlencode( $body["type"] );
$timestamp = ( new DateTime() )->format( DATE_RFC3339_EXTENDED );
// Get the headers send with the request
$headers = getallheaders();
// Ensure the header keys match the format expected by the signature
$headers = array_change_key_case( $headers, CASE_LOWER );
// Validate the timestamp
// 7.2.4 of https://datatracker.ietf.org/doc/rfc9421/
if ( !isset( $headers["date"] ) ) {
// No date set
// Filename for the log
$filename = "{$timestamp}.{$type}.Signature.Date_Failure.txt";
// Save headers and request data to the timestamped file in the logs directory
file_put_contents( $directories["logs"] . "/{$filename}",
"Original Body:\n" . print_r( $body, true ) . "\n\n" .
"Original Headers:\n" . print_r( $headers, true ) . "\n\n"
);
return null;
}
$dateHeader = $headers["date"];
$headerDatetime = DateTime::createFromFormat('D, d M Y H:i:s T', $dateHeader);
$currentDatetime = new DateTime();
// First, check if the message was sent no more than ± 1 hour
// https://github.com/mastodon/mastodon/blob/82c2af0356ff888e9665b5b08fda58c7722be637/app/controllers/concerns/signature_verification.rb#L11
// Calculate the time difference in seconds
$timeDifference = abs( $currentDatetime->getTimestamp() - $headerDatetime->getTimestamp() );
if ( $timeDifference > 3600 ) {
// Write a log detailing the error
// Filename for the log
$filename = "{$timestamp}.{$type}.Signature.Delay_Failure.txt";
// Save headers and request data to the timestamped file in the logs directory
file_put_contents( $directories["logs"] . "/{$filename}",
"Header Date:\n" . print_r( $dateHeader, true ) . "\n" .
"Server Date:\n" . print_r( $currentDatetime->format('D, d M Y H:i:s T'), true ) ."\n" .
"Original Body:\n" . print_r( $body, true ) . "\n\n" .
"Original Headers:\n" . print_r( $headers, true ) . "\n\n"
);
return false;
}
// Is there a significant difference between the Date header and the published timestamp?
// Two minutes chosen because Friendica is frequently more than a minute skewed
$published = $body["published"];
$publishedDatetime = new DateTime($published);
// Calculate the time difference in seconds
$timeDifference = abs( $publishedDatetime->getTimestamp() - $headerDatetime->getTimestamp() );
if ( $timeDifference > 120 ) {
// Write a log detailing the error
// Filename for the log
$filename = "{$timestamp}.{$type}.Signature.Time_Failure.txt";
// Save headers and request data to the timestamped file in the logs directory
file_put_contents( $directories["logs"] . "/{$filename}",
"Header Date:\n" . print_r( $dateHeader, true ) . "\n" .
"Published Date:\n" . print_r( $publishedDatetime->format('D, d M Y H:i:s T'), true ) ."\n" .
"Original Body:\n" . print_r( $body, true ) . "\n\n" .
"Original Headers:\n" . print_r( $headers, true ) . "\n\n"
);
return false;
}
// Validate the Digest
// It is the hash of the raw input string, in binary, encoded as base64.
$digestString = $headers["digest"];
// Usually in the form `SHA-256=Ofv56Jm9rlowLR9zTkfeMGLUG1JYQZj0up3aRPZgT0c=`
// The Base64 encoding may have multiple `=` at the end. So split this at the first `=`
$digestData = explode( "=", $digestString, 2 );
$digestAlgorithm = $digestData[0];
$digestHash = $digestData[1];
// There might be many different hashing algorithms
// TODO: Find a way to transform these automatically
// See https://github.com/superseriousbusiness/gotosocial/issues/1186#issuecomment-1976166659 and https://github.com/snarfed/bridgy-fed/issues/430 for hs2019
if ( "SHA-256" == $digestAlgorithm || "hs2019" == $digestAlgorithm ) {
$digestAlgorithm = "sha256";
} else if ( "SHA-512" == $digestAlgorithm ) {
$digestAlgorithm = "sha512";
}
// Manually calculate the digest based on the data sent
$digestCalculated = base64_encode( hash( $digestAlgorithm, $input, true ) );
// Does our calculation match what was sent?
if ( !( $digestCalculated == $digestHash ) ) {
// Write a log detailing the error
$filename = "{$timestamp}.{$type}.Signature.Digest_Failure.txt";
// Save headers and request data to the timestamped file in the logs directory
file_put_contents( $directories["logs"] . "/{$filename}",
"Original Input:\n" . print_r( $input, true ) . "\n" .
"Original Digest:\n" . print_r( $digestString, true ) . "\n" .
"Calculated Digest:\n" . print_r( $digestCalculated, true ) . "\n"
);
return false;
}
// Examine the signature
$signatureHeader = $headers["signature"];
// Extract key information from the Signature header
$signatureParts = [];
// Converts 'a=b,c=d e f' into ["a"=>"b", "c"=>"d e f"]
// word="text"
preg_match_all('/(\w+)="([^"]+)"/', $signatureHeader, $matches);
foreach ( $matches[1] as $index => $key ) {
$signatureParts[$key] = $matches[2][$index];
}
// Manually reconstruct the header string
$signatureHeaders = explode(" ", $signatureParts["headers"] );
$signatureString = "";
foreach ( $signatureHeaders as $signatureHeader ) {
if ( "(request-target)" == $signatureHeader ) {
$method = strtolower( $_SERVER["REQUEST_METHOD"] );
$target = $_SERVER["REQUEST_URI"];
$signatureString .= "(request-target): {$method} {$target}\n";
} else if ( "host" == $signatureHeader ) {
$host = strtolower( $_SERVER["HTTP_HOST"] );
$signatureString .= "host: {$host}\n";
} else {
$signatureString .= "{$signatureHeader}: " . $headers[$signatureHeader] . "\n";
}
}
// Remove trailing newline
$signatureString = trim( $signatureString );
// Get the Public Key
// The link to the key might be sent with the body, but is always sent in the Signature header.
$publicKeyURL = $signatureParts["keyId"];
// This is usually in the form `https://example.com/user/username#main-key`
// This is to differentiate if the user has multiple keys
// TODO: Check the actual key
$userData = getDataFromURl( $publicKeyURL );
$publicKey = $userData["publicKey"]["publicKeyPem"];
// Check that the actor's key is the same as the key used to sign the message
// Get the actor's public key
$actorData = getDataFromURl( $body["actor"] );
$actorPublicKey = $actorData["publicKey"]["publicKeyPem"];
if ( $publicKey != $actorPublicKey ) {
// Filename for the log
$filename = "{$timestamp}.{$type}.Signature.Mismatch_Failure.txt";
// Save headers and request data to the timestamped file in the logs directory
file_put_contents( $directories["logs"] . "/{$filename}",
"Original Body:\n" . print_r( $body, true ) . "\n\n" .
"Original Headers:\n" . print_r( $headers, true ) . "\n\n" .
"Signature Headers:\n" . print_r( $signatureHeaders, true ) . "\n\n" .
"publicKeyURL:\n" . print_r( $publicKeyURL, true ) . "\n\n" .
"publicKey:\n" . print_r( $publicKey, true ) . "\n\n" .
"actorPublicKey:\n" . print_r( $actorPublicKey, true ) . "\n"
);
return false;
}
// Get the remaining parts
$signature = base64_decode( $signatureParts["signature"] );
$algorithm = $signatureParts["algorithm"];
// There might be many different signing algorithms
// TODO: Find a way to transform these automatically
// See https://github.com/superseriousbusiness/gotosocial/issues/1186#issuecomment-1976166659 and https://github.com/snarfed/bridgy-fed/issues/430 for hs2019
if ( "hs2019" == $algorithm ) {
$algorithm = "sha256";
}
// Finally! Calculate whether the signature is valid
// Returns 1 if verified, 0 if not, false or -1 if an error occurred
$verified = openssl_verify(
$signatureString,
$signature,
$publicKey,
$algorithm
);
// Convert to boolean
if ( $verified === 1 ) {
$verified = true;
} elseif ( $verified === 0 ) {
$verified = false;
} else {
$verified = null;
}
// Filename for the log
$filename = "{$timestamp}.{$type}.Signature.". json_encode( $verified ) . ".txt";
// Save headers and request data to the timestamped file in the logs directory
file_put_contents( $directories["logs"] . "/{$filename}",
"Original Body:\n" . print_r( $body, true ) . "\n\n" .
"Original Headers:\n" . print_r( $headers, true ) . "\n\n" .
"Signature Headers:\n" . print_r( $signatureHeaders, true ) . "\n\n" .
"Calculated signatureString:\n" . print_r( $signatureString, true ) . "\n\n" .
"Calculated algorithm:\n" . print_r( $algorithm, true ) . "\n\n" .
"publicKeyURL:\n" . print_r( $publicKeyURL, true ) . "\n\n" .
"publicKey:\n" . print_r( $publicKey, true ) . "\n\n" .
"actorPublicKey:\n" . print_r( $actorPublicKey, true ) . "\n"
);
return $verified;
}
// The NodeInfo Protocol is used to identify servers.
// It is looked up with `example.com/.well-known/nodeinfo`
// See https://nodeinfo.diaspora.software/
function wk_nodeinfo() {
global $server;
$nodeinfo = array(
"links" => array(
array(
"rel" => "self",
"type" => "http://nodeinfo.diaspora.software/ns/schema/2.1",
"href" => "https://{$server}/nodeinfo/2.1"
)
)
);
header( "Content-Type: application/json" );
echo json_encode( $nodeinfo );
die();
}
// The NodeInfo Protocol is used to identify servers.
// It is looked up with `example.com/.well-known/nodeinfo` which points to this resource
// See http://nodeinfo.diaspora.software/docson/index.html#/ns/schema/2.0#$$expand
function nodeinfo() {
global $server, $directories;
// Get all posts
$posts = glob( $directories["posts"] . "/*.json") ;
// Number of posts
$totalItems = count( $posts );
$nodeinfo = array(
"version" => "2.1", // Version of the schema, not the software
"software" => array(
"name" => "Single File ActivityPub Server in PHP",
"version" => "0.000000001",
"repository" => "https://gitlab.com/edent/activitypub-single-php-file/"
),
"protocols" => array( "activitypub"),
"services" => array(
"inbound" => array(),
"outbound" => array()
),
"openRegistrations" => false,
"usage" => array(
"users" => array(
"total" => 1
),
"localPosts" => $totalItems
),
"metadata"=> array(
"nodeName" => "activitypub-single-php-file",
"nodeDescription" => "This is a single PHP file which acts as an extremely basic ActivityPub server.",
"spdx" => "AGPL-3.0-or-later"
)
);
header( "Content-Type: application/json" );
echo json_encode( $nodeinfo );
die();
}
// Perform the Undo action requested
function undo( $message ) {
global $server, $directories;
// Get some basic data
$type = $message["type"];
$id = $message["id"];
// The thing being undone
$object = $message["object"];
// Does the thing being undone have its own ID or Type?
if ( isset( $object["id"] ) ) {
$object_id = $object["id"];
} else {
$object_id = $id;
}
if ( isset( $object["type"] ) ) {
$object_type = $object["type"];
} else {
$object_type = $type;
}
// Inbox items are stored as the hash of the original ID
$object_id_hash = hash( "sha256", $object_id );
// Find all the inbox messages which have that ID
$inbox_files = glob( $directories["inbox"] . "/*.json" );
foreach ( $inbox_files as $inbox_file ) {
// Filenames are `data/inbox/[date]-[SHA256 hash0].[Type].json
// Find the position of the first hyphen and the first dot
$hyphenPosition = strpos( $inbox_file, '-' );
$dotPosition = strpos( $inbox_file, '.' );
if ( $hyphenPosition !== false && $dotPosition !== false ) {
// Extract the text between the hyphen and the first dot
$file_id_hash = substr( $inbox_file, $hyphenPosition + 1, $dotPosition - $hyphenPosition - 1);
} else {
// Ignore the file and move to the next.
continue;
}
// If this has the same hash as the item being undone
if ( $object_id_hash == $file_id_hash ) {
// Delete the file
unlink( $inbox_file );
// If this was the undoing of a follow request, remove the external user from followers 😢
if ( "Follow" == $object_type ) {
$actor = $object["actor"];
$follower_filename = urlencode( $actor );
unlink( $directories["followers"] . "/{$follower_filename}.json" );
}
// Stop looping
break;
}
}
}
// "One to stun, two to kill, three to make sure"
die();
die();
die();
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