Module: Mpp::Server::Verify

Extended by:
T::Sig
Defined in:
lib/mpp/server/verify.rb

Constant Summary collapse

DEFAULT_EXPIRES_MINUTES = 
5

Class Method Summary collapse

Class Method Details

.create_challenge(method, intent_name, request, realm, secret_key, description = nil, meta = nil, expires = nil) ⇒ Object 



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# File 'lib/mpp/server/verify.rb', line 98

def create_challenge(method, intent_name, request, realm, secret_key,
  description = nil, meta = nil, expires = nil)
  expires = nil if expires && !expires.is_a?(String)

  if expires.nil?
    expires_dt = Time.now.utc + (DEFAULT_EXPIRES_MINUTES * 60)
    expires = expires_dt.strftime("%Y-%m-%dT%H:%M:%S.%LZ")
  end

  Mpp::Challenge.create(
    secret_key: secret_key,
    realm: realm,
    method: method,
    intent: intent_name,
    request: request,
    expires: expires,
    description: description,
    meta: meta
  )
end

.extract_payment_scheme(header) ⇒ Object 



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# File 'lib/mpp/server/verify.rb', line 120

def extract_payment_scheme(header)
  header.split(",").each do |scheme|
    scheme = scheme.strip
    return scheme if scheme.downcase.start_with?("payment ")
  end
  nil
end

.verify_or_challenge(authorization:, intent:, request:, realm:, secret_key:, method: nil, description: nil, meta: nil, expires: nil) ⇒ Object 



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# File 'lib/mpp/server/verify.rb', line 19

def verify_or_challenge(authorization:, intent:, request:, realm:, secret_key:,
  method: nil, description: nil, meta: nil, expires: nil)
  method_name = method || "tempo"
  request = Mpp::Units.transform_units(request)

  new_challenge = Kernel.lambda {
    create_challenge(method_name, intent.name, request, realm, secret_key, description, meta, expires)
  }

  return new_challenge.call if authorization.nil?

  payment_scheme = extract_payment_scheme(authorization)
  return new_challenge.call if payment_scheme.nil?

  begin
    credential = Mpp::Credential.from_authorization(payment_scheme)
  rescue Mpp::ParseError
    return new_challenge.call
  end

  # Stateless challenge verification
  echo = credential.challenge
  begin
    echo_request = echo.request.empty? ? {} : Mpp::Parsing.b64_decode(echo.request)
    echo_opaque = (echo.opaque && !T.must(echo.opaque).empty?) ? Mpp::Parsing.b64_decode(echo.opaque) : nil
  rescue Mpp::ParseError
    return new_challenge.call
  end

  expected_id = Mpp.generate_challenge_id(
    secret_key: secret_key,
    realm: echo.realm,
    method: echo.method,
    intent: echo.intent,
    request: echo_request,
    expires: echo.expires,
    digest: echo.digest,
    opaque: echo_opaque
  )
  return new_challenge.call unless Mpp.secure_compare(echo.id, expected_id)

  # Assert echoed fields match server's values
  return new_challenge.call unless echo.realm == realm && echo.method == method_name && echo.intent == intent.name

  # Assert echoed request matches server's current request
  return new_challenge.call unless echo_request == request

  return new_challenge.call unless echo_opaque == meta

  # Reject expired challenges as defense-in-depth
  if echo.expires
    begin
      expires_dt = Time.iso8601(T.must(echo.expires).gsub("Z", "+00:00"))
      return new_challenge.call if expires_dt < Time.now.utc
    rescue ArgumentError
      # If we can't parse, continue to stricter check below
    end
  end

  # Verify echoed request parameters match endpoint's expected request
  request.each do |key, value|
    return new_challenge.call unless echo_request[key] == value
  end

  # Enforce challenge expiry - fail closed
  return new_challenge.call unless echo.expires

  begin
    expires_dt = Time.iso8601(T.must(echo.expires).gsub("Z", "+00:00"))
  rescue ArgumentError
    return new_challenge.call
  end
  return new_challenge.call if expires_dt < Time.now.utc

  receipt = intent.verify(credential, request)
  [credential, receipt]
end