module Oauth2ProxyAuthentication

# File lib/oauth2_proxy_authentication/signature.rb, line 38
def self.parse_digest(name)
  OpenSSL::Digest.new name
rescue
  nil
end

# File lib/oauth2_proxy_authentication/signature.rb, line 32
def self.request_signature(request, digest, secret_key)
  hmac = OpenSSL::HMAC.new secret_key, digest
  hmac << string_to_sign(request) << (request.body || '')
  digest.name.downcase + ' ' + Base64.strict_encode64(hmac.digest)
end

# File lib/oauth2_proxy_authentication/signature.rb, line 24
def self.signed_headers(request)
  HEADERS.map { |name| request[name] || '' }
end

# File lib/oauth2_proxy_authentication/signature.rb, line 28
def self.string_to_sign(req)
  [req.method, signed_headers(req).join("\n"), req.uri.path].join("\n")
end

# File lib/oauth2_proxy_authentication/signature.rb, line 44
def self.validate_request(request, key)
  header = request['Gap-Signature']
  return NO_SIGNATURE unless header
  components = header.split ' '
  return INVALID_FORMAT, header unless components.size == 2
  digest = parse_digest components.first
  return UNSUPPORTED_ALGORITHM, header unless digest
  computed = request_signature(request, digest, key)
  [(header == computed) ? MATCH : MISMATCH, header, computed]
end