Add E2EE API (#13820)

2 files changed, 152 insertions, 0 deletions

diff --git a/app/services/keys/claim_service.rb b/app/services/keys/claim_service.rb
new file mode 100644
index 000000000..672119130
--- /dev/null
+++ b/app/services/keys/claim_service.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+class Keys::ClaimService < BaseService
+  HEADERS = { 'Content-Type' => 'application/activity+json' }.freeze
+
+  class Result < ActiveModelSerializers::Model
+    attributes :account, :device_id, :key_id,
+               :key, :signature
+
+    def initialize(account, device_id, key_attributes = {})
+      @account   = account
+      @device_id = device_id
+      @key_id    = key_attributes[:key_id]
+      @key       = key_attributes[:key]
+      @signature = key_attributes[:signature]
+    end
+  end
+
+  def call(source_account, target_account_id, device_id)
+    @source_account = source_account
+    @target_account = Account.find(target_account_id)
+    @device_id      = device_id
+
+    if @target_account.local?
+      claim_local_key!
+    else
+      claim_remote_key!
+    end
+  rescue ActiveRecord::RecordNotFound
+    nil
+  end
+
+  private
+
+  def claim_local_key!
+    device = @target_account.devices.find_by(device_id: @device_id)
+    key    = nil
+
+    ApplicationRecord.transaction do
+      key = device.one_time_keys.order(Arel.sql('random()')).first!
+      key.destroy!
+    end
+
+    @result = Result.new(@target_account, @device_id, key)
+  end
+
+  def claim_remote_key!
+    query_result = QueryService.new.call(@target_account)
+    device       = query_result.find(@device_id)
+
+    return unless device.present? && device.valid_claim_url?
+
+    json = fetch_resource_with_post(device.claim_url)
+
+    return unless json.present? && json['publicKeyBase64'].present?
+
+    @result = Result.new(@target_account, @device_id, key_id: json['id'], key: json['publicKeyBase64'], signature: json.dig('signature', 'signatureValue'))
+  rescue HTTP::Error, OpenSSL::SSL::SSLError, Mastodon::Error => e
+    Rails.logger.debug "Claiming one-time key for #{@target_account.acct}:#{@device_id} failed: #{e}"
+    nil
+  end
+
+  def fetch_resource_with_post(uri)
+    build_post_request(uri).perform do |response|
+      raise Mastodon::UnexpectedResponseError, response unless response_successful?(response) || response_error_unsalvageable?(response)
+
+      body_to_json(response.body_with_limit) if response.code == 200
+    end
+  end
+
+  def build_post_request(uri)
+    Request.new(:post, uri).tap do |request|
+      request.on_behalf_of(@source_account, :uri)
+      request.add_headers(HEADERS)
+    end
+  end
+end
diff --git a/app/services/keys/query_service.rb b/app/services/keys/query_service.rb
new file mode 100644
index 000000000..286fbd834
--- /dev/null
+++ b/app/services/keys/query_service.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+class Keys::QueryService < BaseService
+  include JsonLdHelper
+
+  class Result < ActiveModelSerializers::Model
+    attributes :account, :devices
+
+    def initialize(account, devices)
+      @account = account
+      @devices = devices || []
+    end
+
+    def find(device_id)
+      @devices.find { |device| device.device_id == device_id }
+    end
+  end
+
+  class Device < ActiveModelSerializers::Model
+    attributes :device_id, :name, :identity_key, :fingerprint_key
+
+    def initialize(attributes = {})
+      @device_id       = attributes[:device_id]
+      @name            = attributes[:name]
+      @identity_key    = attributes[:identity_key]
+      @fingerprint_key = attributes[:fingerprint_key]
+      @claim_url       = attributes[:claim_url]
+    end
+
+    def valid_claim_url?
+      return false if @claim_url.blank?
+
+      begin
+        parsed_url = Addressable::URI.parse(@claim_url).normalize
+      rescue Addressable::URI::InvalidURIError
+        return false
+      end
+
+      %w(http https).include?(parsed_url.scheme) && parsed_url.host.present?
+    end
+  end
+
+  def call(account)
+    @account = account
+
+    if @account.local?
+      query_local_devices!
+    else
+      query_remote_devices!
+    end
+
+    Result.new(@account, @devices)
+  end
+
+  private
+
+  def query_local_devices!
+    @devices = @account.devices.map { |device| Device.new(device) }
+  end
+
+  def query_remote_devices!
+    return if @account.devices_url.blank?
+
+    json = fetch_resource(@account.devices_url)
+
+    return if json['items'].blank?
+
+    @devices = json['items'].map do |device|
+      Device.new(device_id: device['id'], name: device['name'], identity_key: device.dig('identityKey', 'publicKeyBase64'), fingerprint_key: device.dig('fingerprintKey', 'publicKeyBase64'), claim_url: device['claim'])
+    end
+  rescue HTTP::Error, OpenSSL::SSL::SSLError, Mastodon::Error => e
+    Rails.logger.debug "Querying devices for #{@account.acct} failed: #{e}"
+    nil
+  end
+end