path: root/activitypub.rb

# TODO
# follow request confirmation
# anchors (return after archive)
# boost
# federation
# client post media
# test with pleroma etc
require 'uri'
require 'base64'
require 'digest/sha2'
require 'net/http'
require 'sinatra'

USER = "pdp8"
WWW_DOMAIN = "pdp8.info"
WWW_URL = "https://#{WWW_DOMAIN}"
SOCIAL_DOMAIN = "social.#{WWW_DOMAIN}"

ACCOUNT = "#{USER}@#{SOCIAL_DOMAIN}"
SOCIAL_URL = "https://#{SOCIAL_DOMAIN}"
ACTOR = File.join(SOCIAL_URL, USER)

enable :sessions
set :session_secret, File.read(".secret").chomp
set :default_content_type, 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
set :port, 9292

post "/inbox" do # server-server
  verify!
  request.body.rewind # in case someone already read it
  body = request.body.read
  action = JSON.parse body

  case action["type"]

  when "Create"
    create action["object"]

  when "Delete"
    delete action["object"]

  when "Update"
    delete action["object"]
    create action["object"]

  when "Follow"
    File.open(File.join("public", "followers", mention(action["actor"]) + ".json"), "w+") { |f| f.puts body }
    accept = { "@context" => "https://www.w3.org/ns/activitystreams",
               "id" => File.join(SOCIAL_URL + "#accepts", SecureRandom.uuid),
               "type" => "Accept",
               "actor" => ACTOR,
               "object" => action }
    send_signed accept, action["actor"]

  when "Undo"
    o = action["object"]
    case o["type"]
    when "Follow"
      Dir["public/followers/*.json"].each do |follower|
        FileUtils.rm follower if JSON.parse(File.read(follower))["actor"] == o["actor"]
      end
    end

  when "Accept"
    o = action["object"]
    case o["type"]
    when "Follow"
      File.open(File.join("public","following",mention(o['object'])+".json"),"w+"){|f| f.puts o.to_json}
    end
  #when "Announce"

  else
    p "Unknown action: #{action['type']}"
    p body
  end
end

post "/outbox" do # client-server
  protected!
  request.body.rewind # in case someone already read it
  body = request.body.read
  date = Time.now.strftime("%Y-%m-%dT%H:%M:%S")
  # TODO hashtags, replys
  outbox_path = File.join("public/outbox", date + ".json")
  object_path = File.join("public/objects", date + ".json")
  create = {
    "@context" => "https://www.w3.org/ns/activitystreams",
    "id" => File.join(SOCIAL_URL, outbox_path),
    "type" => "Create",
    "actor" => ACTOR,
    "object" => {
      "id" => File.join(SOCIAL_URL, object_path),
      "type" => "Note",
      "attributedTo" => ACTOR,
      "published" => date,
      "content" => "",
      "to" => ["https://www.w3.org/ns/activitystreams#Public"]
    },
    "published" => date,
    "to" => ["https://www.w3.org/ns/activitystreams#Public"]
  }
  recipients = []
  if /^@/.match body
    mentions, body = body.split("\n", 2)
    mentions.split(/, */).each do |m|
      recipients << actor(m.chomp)
    end
  end
  create["object"]["content"] = body.lines.select { |l| !l.empty? }.join("<br>")
  recipients += Dir[File.join("public/followers", "*.json")].collect { |f| JSON.parse(File.read(f))["actor"] }
  recipients.delete ACTOR
  recipients.uniq!
  create["object"]["to"] += recipients
  create["to"] += recipients

  File.open(outbox_path, "w+") { |f| f.puts create.to_json }
  File.open(object_path, "w+") { |f| f.puts create["object"].to_json }

  recipients.each { |r| send_signed create, r }
end

post "/archive/*" do
  protected!
  FileUtils.mv params['splat'][0], "archive/"
  redirect to("/")
end

post "/delete/*" do
  protected!
  FileUtils.rm params['splat'][0]
  redirect to("/")
end

post "/delete" do
  protected!
  FileUtils.rm Dir["inbox/*.json"]
  redirect to("/")
end

post "/follow/*" do
  protected!
  mention = params['splat'][0]
  actor = actor(mention)
  follow = { "@context" => "https://www.w3.org/ns/activitystreams",
             "id" => File.join(SOCIAL_URL, "following", mention + ".json"),
             "type" => "Follow",
             "actor" => ACTOR,
             "object" => actor }
  send_signed follow, actor
  redirect to("/")
end

post "/unfollow/*" do
  protected!
  mention = params['splat'][0]
  actor = actor(mention)
  following_path = File.join("public", "following", mention + ".json")
  if File.exists?(following_path)
    undo = { "@context" => "https://www.w3.org/ns/activitystreams",
             "id" => File.join(SOCIAL_URL + "#undo", SecureRandom.uuid),
             "type" => "Undo",
             "actor" => ACTOR,
             "object" => JSON.parse(File.read(following_path)) }
    send_signed undo, actor
    FileUtils.rm following_path
    redirect to("/")
  end
end

post "/login" do
  session["client"] = true if params["secret"] == File.read(".pwd").chomp
  redirect to("/")
end

get "/.well-known/webfinger" do
  if request["resource"] == "acct:#{ACCOUNT}"
    send_file "./public/webfinger", :type => "application/jrd+json"
  else
    halt 404
  end
end

get "/archive", :provides => 'html' do
  protected!
  dir_html "archive"
end

get "/", :provides => 'html' do
  protected!
  dir_html "inbox"
end

["/outbox","/following","/followers"].each do |path|
  get path do 
    ordered_collection(path).to_json
  end
end

helpers do

  def protected!
    redirect("/login.html") unless session['client']
  end

  def verify!
    # https://github.com/mastodon/mastodon/blob/main/app/controllers/concerns/signature_verification.rb
    # TODO verify digest
    begin
      signature_params = {}
      request.env["HTTP_SIGNATURE"].split(',').each do |pair|
        k, v = pair.split('=')
        signature_params[k] = v.gsub('"', '')
      end

      key_id = signature_params['keyId']
      headers = signature_params['headers']
      signature = Base64.decode64(signature_params['signature'])

      actor = fetch key_id
      key = OpenSSL::PKey::RSA.new(actor['publicKey']['publicKeyPem'])

      comparison = headers.split(' ').map do |signed_params_name|
        if signed_params_name == '(request-target)'
          '(request-target): post /inbox'
        elsif signed_params_name == 'content-type'
          "#{signed_params_name}: #{request.env["CONTENT_TYPE"]}"
        else
          "#{signed_params_name}: #{request.env["HTTP_" + signed_params_name.upcase]}"
        end
      end.join("\n")

      halt 400 unless key.verify(OpenSSL::Digest.new('SHA256'), signature, comparison)
    rescue => e
      p request.env["HTTP_SIGNATURE"]
      p e
      halt 400
    end
  end
end

def dir_html dir
  items = Dir[File.join(dir, '*.json')].sort.collect do |file|
    item = JSON.parse(File.read(file))
    mention = mention(item['attributedTo'])
    following_path = File.join('public', 'following', mention + '.json')
    File.exists?(following_path) ? follow = 'unfollow' : follow = 'follow'
    { :id => item['id'],
      :parent => item['inReplyTo'],
      :file => file,
      :actor_url => item['attributedTo'],
      :mention => mention,
      :follow => follow,
      :content => item['content'],
      :attachment => item['attachment'],
      :replies => []
    }
  end.compact
  threads = []
  items.each do |i|
    if i[:parent].nil? or items.select{|it| it[:id] == i[:parent] }.empty?
      threads << i
    else
      items.select{|it| it[:id] == i[:parent] }.each{|it| it[:replies] << i}
    end
  end
  html="<!DOCTYPE html>
  <html lang='en'>
    <head>
      <link rel='stylesheet' type='text/css' href='/style.css'>
    </head>
    <body>
      <h1>#{dir}</h1>
  "
  threads.each do |item|
    html << item_html(item,dir)
  end
  html << "
    <form action='delete' method='post'>
      <button>Delete all</button>
    </form>
    </body>
  </html>" if dir == "inbox"
  html
end

def item_html item, dir, indent=2
  html = "
  <div style='margin-left:#{indent}em'>
  <b><a href='#{ item[:actor_url] }', target='_blank'>#{ item[:mention] }</a></b>&nbsp;
  <form action='#{ File.join item[:follow], item[:mention] }' method='post'>
    <button>#{ item[:follow].capitalize }</button>
  </form>
  &nbsp;
  "
  case dir
  when "inbox"
    html << "
    <form action='#{ File.join 'archive', item[:file] }' method='post'>
      <button>Archive</button>
    </form>
    "
  when "archive"
    html << "
    <form action='#{ File.join 'delete', item[:file] }' method='post'>
      <button>Delete</button>
    </form>
    "
  end
  html << "
  #{ item[:content].gsub('<br />','') }"
  if item[:attachment]
    item[:attachment].each do |att|
      html << "<br>"
      case att['mediaType']
      when /audio/
        html << "<audio controls=''><source src='#{ att['url'] }' type='#{ att['mediaType'] }'></audio>"
      when /image/
        html << "<a href='#{ att['url'] }'><img src='#{ att['url'] }'></a>"
      when /video/
        html << "<video controls=''><source src='#{ att['url'] }' type='#{ att['mediaType'] }'></video>"
      else
        html << "#{ att }<br>
        <a href='#{ att['url'] }'>#{ att['url'] }</a>"
      end
    end 
  end 
  html << "
  </div>"
  item[:replies].each do |r|
    html << item_html(r,dir,indent+4)
  end

  html
end

def delete object
  Dir["inbox/*.json"].each do |doc|
    FileUtils.rm doc if JSON.parse(File.read(doc))["id"] == object["id"]
  end
end

def create object
  unless object['type'] == 'Person'
    doc = File.join("inbox", "#{Time.now.strftime('%Y-%m-%dT%H:%M:%S.%N')}.json")
    File.open(doc, "w+") { |f| f.puts object.to_json }
  end
end

def mention actor
  people = File.read('inbox/people.tsv').split("\n").collect {|l| l.chomp.split("\t")}
  person = people.select{|p| p[1] == actor} 
  if person.empty?
    mention = "#{fetch(actor)["preferredUsername"]}@#{URI(actor).host}"
    File.open('inbox/people.tsv','a'){|f| f.puts "#{mention}\t#{actor}"}
    mention
  else
    person[0][0]
  end
end

def actor mention
  mention = mention.sub(/^@/, '').chomp
  user, server = mention.split("@")
  fetch("https://#{server}/.well-known/webfinger?resource=acct:#{mention}",
      "application/jrd+json")["links"].select { |l|
    l["rel"] == "self"
  }[0]["href"]
end

def fetch url, accept = 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"', limit = 10
  uri = URI(url)
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true
  header = { 'Accept' => accept }
  request = Net::HTTP::Get.new(uri.request_uri, header)
  response = http.request(request)
  case response
  when Net::HTTPSuccess
    return JSON.parse(response.body)
  when Net::HTTPRedirection
    fetch response['location'], accept, limit-1
  else
    puts "Unknown response: #{response.code}, #{response.message}\n#{response.code}"
  end
end

def ordered_collection dir
  posts = Dir[File.join("public",dir, "*.json")].collect { |f| JSON.parse(File.read f) }.sort_by { |o| o["published"] }
  {
    "@context" => "https://www.w3.org/ns/activitystreams",
    "summary" => "#{USER} #{dir}",
    "type" => "OrderedCollection",
    "totalItems" => posts.size,
    "orderedItems" => posts,
  }
end

def send_signed object, url
  # https://github.com/mastodon/mastodon/blob/main/app/lib/request.rb
  keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
  date = Time.now.utc.httpdate
  uri = URI.parse(url)

  sha256 = OpenSSL::Digest::SHA256.new
  body = object.to_json
  digest = "SHA-256=" + sha256.base64digest(body)

  signed_string = "(request-target): post #{inbox uri}\nhost: #{uri.host}\ndate: #{date}\ndigest: #{digest}\ncontent-type: application/activity+json"
  signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest.new('SHA256'), signed_string))
  signed_header = 'keyId="' + ACTOR + '#main-key",algorithm="rsa-sha256",headers="(request-target) host date digest content-type",signature="' + signature + '"'

  puts `/run/current-system/sw/bin/curl -i -X POST -H 'Content-Type: application/activity+json' -H 'Host: #{uri.host}' -H 'Date: #{date}' -H 'Digest: #{digest}' -H 'Signature: #{signed_header}' -d '#{body}' #{fetch(url)['inbox']}`
end

def inbox uri
  URI(fetch(uri)["inbox"]).request_uri
end