hometown/app/lib/webfinger.rb
Eugen Rochko ce6aaed432 Remove dependency on goldfinger gem (#14919)
There are edge cases where requests to certain hosts timeout when
using the vanilla HTTP.rb gem, which the goldfinger gem uses. Now
that we no longer need to support OStatus servers, webfinger logic
is so simple that there is no point encapsulating it in a gem, so
we can just use our own Request class. With that, we benefit from
more robust timeout code and IPv4/IPv6 resolution.

Fix #14091
2020-10-19 14:48:54 +02:00

94 lines
2.2 KiB
Ruby

# frozen_string_literal: true
class Webfinger
class Error < StandardError; end
class Response
def initialize(body)
@json = Oj.load(body, mode: :strict)
end
def subject
@json['subject']
end
def link(rel, attribute)
links.dig(rel, attribute)
end
private
def links
@links ||= @json['links'].map { |link| [link['rel'], link] }.to_h
end
end
def initialize(uri)
_, @domain = uri.split('@')
raise ArgumentError, 'Webfinger requested for local account' if @domain.nil?
@uri = uri
end
def perform
Response.new(body_from_webfinger)
rescue Oj::ParseError
raise Webfinger::Error, "Invalid JSON in response for #{@uri}"
rescue Addressable::URI::InvalidURIError
raise Webfinger::Error, "Invalid URI for #{@uri}"
end
private
def body_from_webfinger(url = standard_url, use_fallback = true)
webfinger_request(url).perform do |res|
if res.code == 200
res.body_with_limit
elsif res.code == 404 && use_fallback
body_from_host_meta
else
raise Webfinger::Error, "Request for #{@uri} returned HTTP #{res.code}"
end
end
end
def body_from_host_meta
host_meta_request.perform do |res|
if res.code == 200
body_from_webfinger(url_from_template(res.body_with_limit), false)
else
raise Webfinger::Error, "Request for #{@uri} returned HTTP #{res.code}"
end
end
end
def url_from_template(str)
link = Nokogiri::XML(str).at_xpath('//xmlns:Link[@rel="lrdd"]')
if link.present?
link['template'].gsub('{uri}', @uri)
else
raise Webfinger::Error, "Request for #{@uri} returned host-meta without link to Webfinger"
end
rescue Nokogiri::XML::XPath::SyntaxError
raise Webfinger::Error, "Invalid XML encountered in host-meta for #{@uri}"
end
def host_meta_request
Request.new(:get, host_meta_url).add_headers('Accept' => 'application/xrd+xml, application/xml, text/xml')
end
def webfinger_request(url)
Request.new(:get, url).add_headers('Accept' => 'application/jrd+json, application/json')
end
def standard_url
"https://#{@domain}/.well-known/webfinger?resource=#{@uri}"
end
def host_meta_url
"https://#{@domain}/.well-known/host-meta"
end
end