Module: Sinatra::Slack::InstanceHelpers

Defined in:
lib/sinatra/slack/instance_helpers.rb

Overview

Instance level helper methods

Instance Method Summary collapse

Instance Method Details

#action ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 16

def action
  @action ||= Helpers::ActionRequest.parse(params)
end

#authorized? ⇒ Boolean

Checks for Slack defined HTTP headers and computes the request signature (HMAC). If provided signature is the same as the computed one, the request is valid.

Go to this page for the verification process: api.slack.com/docs/verifying-requests-from-slack

Returns:

  • (Boolean) 


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# File 'lib/sinatra/slack/instance_helpers.rb', line 62

def authorized?
  logger.warn 'Missing Slack signing token' unless settings.slack_secret
  return true unless settings.slack_secret

  valid_headers? &&
    compute_signature(settings.slack_secret) == slack_signature
end

#channel ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 20

def channel
  @channel ||= Helpers::Channel.parse(params)
end

#command ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 12

def command
  @command ||= Helpers::CommandRequest.new(params)
end

#compute_signature(secret) ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 87

def compute_signature(secret)
  # in case someone already read it
  request.body.rewind

  # From Slack API docs, the "v0" is always fixed for now
  sig_basestring = "v0:#{slack_timestamp}:#{request.body.read}"
  "v0=#{hmac_signed(sig_basestring, secret)}"
end

#handle_request(request_handler:, request_params:, quick_reply: '...') ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 36

def handle_request(request_handler:, request_params:, quick_reply: '...')
  EM.defer do
    handle_with_rescue do
      deferred_message = request_handler.bind(self).call(*request_params)
      channel.send(deferred_message)
    end
  end

  body quick_reply
end

#handle_with_rescue ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 47

def handle_with_rescue
  return unless block_given?

  yield
rescue StandardError => ex
  logger.error ex.full_message
  channel.send(slack_error_notification)
end

#hmac_signed(to_sign, hmac_key) ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 96

def hmac_signed(to_sign, hmac_key)
  sha256 = OpenSSL::Digest.new('sha256')
  OpenSSL::HMAC.hexdigest(sha256, hmac_key, to_sign)
end

#slack_error_notification ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 30

def slack_error_notification
  slack_response '' do |r|
    r.text = 'Ups, something went wrong'
  end
end

#slack_response(callback_id) {|s_resp| ... } ⇒ Object

Yields:

  • (s_resp) 


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# File 'lib/sinatra/slack/instance_helpers.rb', line 24

def slack_response(callback_id)
  s_resp = Helpers::SlackResponse.new(callback_id)
  yield s_resp if block_given?
  s_resp
end

#slack_signature ⇒ Object

Helper methods for Slack request validation



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# File 'lib/sinatra/slack/instance_helpers.rb', line 71

def slack_signature
  @slack_signature ||= env['HTTP_X_SLACK_SIGNATURE']
end

#slack_timestamp ⇒ Object 



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# File 'lib/sinatra/slack/instance_helpers.rb', line 75

def slack_timestamp
  @slack_timestamp ||= env['HTTP_X_SLACK_REQUEST_TIMESTAMP']
end

#valid_headers? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sinatra/slack/instance_helpers.rb', line 79

def valid_headers?
  return false unless slack_signature || slack_timestamp

  # The request timestamp is more than five minutes from local time.
  # It could be a replay attack, so let's ignore it.
  (Time.now.to_i - slack_timestamp.to_i).abs <= 60 * 5
end