#!/usr/bin/env python

# Copyright 2020, The Android Open Source Project
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use, copy,
# modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
"""Command-line tool for AFTL support for Android Verified Boot images."""

from __future__ import division

import argparse
import binascii
import hashlib
import multiprocessing
import os
import Queue  # pylint: disable=bad-python3-import
import struct
import subprocess
import sys
import tempfile
import time


import avbtool
import proto.aftl_pb2
import proto.api_pb2
import proto.crypto.sigpb

# Android Firmware Transparency Log Data Structures


class AftlError(Exception):
  """Application-specific errors.

  These errors represent issues for which a stack-trace should not be
  presented.

  Attributes:
    message: Error message.
  """

  def __init__(self, message):
    Exception.__init__(self, message)


def rsa_key_read_pem_bytes(key_path):
  """Reads the bytes out of the passed in PEM file.

  Arguments:
    key_path: A string containing the path to the PEM file.

  Returns:
    A bytearray containing the DER encoded bytes in the PEM file.

  Raises:
    AftlError: If openssl cannot decode the PEM file.
  """
  # Use openssl to decode the PEM file.
  args = ['openssl', 'rsa', '-in', key_path, '-pubout', '-outform', 'DER']
  p = subprocess.Popen(args,
                       stdin=subprocess.PIPE,
                       stdout=subprocess.PIPE,
                       stderr=subprocess.PIPE)
  (pout, perr) = p.communicate()
  retcode = p.wait()
  if retcode != 0:
    raise AftlError('Error decoding: {}'.format(perr))
  return bytearray(pout)


def check_signature(log_root, log_root_sig,
                    transparency_log_pub_key):
  """Validates the signature provided by the transparency log.

  Arguments:
    log_root: The transparency log_root data structure.
    log_root_sig: The signature of the transparency log_root data structure.
    transparency_log_pub_key: The file path to the transparency log public key.

  Returns:
    True if the signature check passes, otherwise False.
  """

  logsig_tmp = tempfile.NamedTemporaryFile()
  logsig_tmp.write(log_root_sig)
  logsig_tmp.flush()
  logroot_tmp = tempfile.NamedTemporaryFile()
  logroot_tmp.write(log_root)
  logroot_tmp.flush()

  p = subprocess.Popen(['openssl', 'dgst', '-sha256', '-verify',
                        transparency_log_pub_key,
                        '-signature', logsig_tmp.name, logroot_tmp.name],
                       stdin=subprocess.PIPE,
                       stdout=subprocess.PIPE,
                       stderr=subprocess.PIPE)

  (_, openssl_err) = p.communicate()
  retcode = p.wait()
  if not retcode:
    return True
  sys.stderr.write('Error validating log_root signature with openssl {}'.
                   format(openssl_err))
  return False


# AFTL Merkle Tree Functionality
def rfc6962_hash_leaf(leaf):
  """RFC6962 hashing function for hashing leaves of a Merkle tree.

  Arguments:
    leaf: A bytearray containing the Merkle tree leaf to be hashed.

  Returns:
    A bytearray containing the RFC6962 SHA256 hash of the leaf.
  """
  hasher = hashlib.sha256()
  # RFC6962 states a '0' byte should be prepended to the data.
  # This is done in conjunction with the '1' byte for non-leaf
  # nodes for 2nd preimage attack resistance.
  hasher.update(b'\x00')
  hasher.update(leaf)
  return hasher.digest()


def rfc6962_hash_children(l, r):
  """Calculates the inner Merkle tree node hash of child nodes l and r.

  Arguments:
    l: A bytearray containing the left child node to be hashed.
    r: A bytearray containing the right child node to be hashed.

  Returns:
    A bytearray containing the RFC6962 SHA256 hash of 1|l|r.
  """
  hasher = hashlib.sha256()
  # RFC6962 states a '1' byte should be prepended to the concatenated data.
  # This is done in conjunction with the '0' byte for leaf
  # nodes for 2nd preimage attack resistance.
  hasher.update(b'\x01')
  hasher.update(l)
  hasher.update(r)
  return hasher.digest()


def chain_border_right(seed, proof):
  """Computes a subtree hash along the left-side tree border.

  Arguments:
    seed: A bytearray containing the starting hash.
    proof: A list of bytearrays representing the hashes in the inclusion proof.

  Returns:
    A bytearray containing the left-side subtree hash.
  """
  for h in proof:
    seed = rfc6962_hash_children(h, seed)
  return seed


def chain_inner(seed, proof, leaf_index):
  """Computes a subtree hash on or below the tree's right border.

  Arguments:
    seed: A bytearray containing the starting hash.
    proof: A list of bytearrays representing the hashes in the inclusion proof.
    leaf_index: The current leaf index.

  Returns:
    A bytearray containing the subtree hash.
  """
  for i, h in enumerate(proof):
    if leaf_index >> i & 1 == 0:
      seed = rfc6962_hash_children(seed, h)
    else:
      seed = rfc6962_hash_children(h, seed)
  return seed


def root_from_icp(leaf_index, tree_size, proof, leaf_hash):
  """Calculates the expected Merkle tree root hash.

  Arguments:
    leaf_index: The current leaf index.
    tree_size: The number of nodes in the Merkle tree.
    proof: A list of bytearrays containing the inclusion proof.
    leaf_hash: A bytearray containing the initial leaf hash.

  Returns:
    A bytearray containing the calculated Merkle tree root hash.

  Raises:
    AftlError: If invalid parameters are passed in.
  """
  if leaf_index < 0:
    raise AftlError('Invalid leaf_index value: {}'.format(leaf_index))
  if tree_size < 0:
    raise AftlError('Invalid tree_size value: {}'.format(tree_size))
  if leaf_index >= tree_size:
    err_str = 'leaf_index cannot be equal or larger than tree_size: {}, {}'
    raise AftlError(err_str.format(leaf_index, tree_size))
  if proof is None:
    raise AftlError('Inclusion proof not provided.')
  if leaf_hash is None:
    raise AftlError('No leaf hash provided.')
  # Calculate the point to split the proof into two parts.
  # The split is where the paths to leaves diverge.
  inner = (leaf_index ^ (tree_size - 1)).bit_length()
  result = chain_inner(leaf_hash, proof[:inner], leaf_index)
  result = chain_border_right(result, proof[inner:])
  return result


class AftlIcpHeader(object):
  """A class for the transparency log inclusion proof header.

  Attributes:
    magic: Magic for identifying the ICP header.
    required_icp_version_major: The major version of AVB that wrote the entry.
    required_icp_version_minor: The minor version of AVB that wrote the entry.
    aftl_descriptor_size: Total size of the header's AftlDescriptor.
    icp_count: Number of inclusion proofs represented in this structure.
  """

  SIZE = 18  # The size of the structure, in bytes
  MAGIC = 'AFTL'
  FORMAT_STRING = ('!4s2L'  # magic, major & minor version
                   'L'      # descriptor size
                   'H')     # number of inclusion proof entries

  def __init__(self, data=None):
    """Initializes a new transparency header object.

    Arguments:
      data: If not None, must be a bytearray of size |SIZE|.

    Raises:
      AftlError: If invalid structure for AftlIcpHeader.
    """
    assert struct.calcsize(self.FORMAT_STRING) == self.SIZE

    if data:
      (self.magic, self.required_icp_version_major,
       self.required_icp_version_minor, self.aftl_descriptor_size,
       self.icp_count) = struct.unpack(self.FORMAT_STRING, data)
    else:
      self.magic = self.MAGIC
      self.required_icp_version_major = avbtool.AVB_VERSION_MAJOR
      self.required_icp_version_minor = avbtool.AVB_VERSION_MINOR
      self.aftl_descriptor_size = self.SIZE
      self.icp_count = 0
    if not self.is_valid():
      raise AftlError('Invalid structure for AftlIcpHeader')

  def save(self, output):
    """Serializes the transparency header |SIZE| to disk.

    Arguments:
      output: The object to write the header to.

    Raises:
      AftlError: If invalid structure for AftlIcpHeader.
    """
    output.write(self.encode())

  def encode(self):
    """Serializes the header |SIZE| to a bytearray().

    Returns:
      A bytearray() with the encoded header.

    Raises:
      AftlError: If invalid structure for AftlIcpHeader.
    """
    if not self.is_valid():
      raise AftlError('Invalid structure for AftlIcpHeader')
    return struct.pack(self.FORMAT_STRING, self.magic,
                       self.required_icp_version_major,
                       self.required_icp_version_minor,
                       self.aftl_descriptor_size,
                       self.icp_count)

  def is_valid(self):
    """Ensures that values in an AftlIcpHeader structure are sane.

    Returns:
      True if the values in the AftlIcpHeader are sane, False otherwise.
    """
    if self.magic != AftlIcpHeader.MAGIC:
      sys.stderr.write(
          'ICP Header: magic value mismatch: {}\n'.format(self.magic))
      return False

    if self.required_icp_version_major > avbtool.AVB_VERSION_MAJOR:
      sys.stderr.write('ICP header: major version mismatch: {}\n'.format(
          self.required_icp_version_major))
      return False

    if self.required_icp_version_minor > avbtool.AVB_VERSION_MINOR:
      sys.stderr.write('ICP header: minor version mismatch: {}\n'.format(
          self.required_icp_version_minor))
      return False

    if self.aftl_descriptor_size < self.SIZE:
      sys.stderr.write('ICP Header: Invalid descriptor size: {}\n'.format(
          self.aftl_descriptor_size))
      return False

    if self.icp_count < 0 or self.icp_count > 65535:
      sys.stderr.write(
          'ICP header: ICP entry count out of range: {}\n'.format(
              self.icp_count))
      return False
    return True

  def print_desc(self, o):
    """Print the descriptor.

    Arguments:
      o: The object to write the output to.
    """
    o.write('    Major version:      {}\n'.format(
        self.required_icp_version_major))
    o.write('    Minor version:      {}\n'.format(
        self.required_icp_version_minor))
    o.write('    Descriptor size:    {}\n'.format(
        self.aftl_descriptor_size))
    o.write('    ICP entries count:  {}\n'.format(
        self.icp_count))

class AftlIcpEntry(object):
  """A class for the transparency log inclusion proof entries.

  The data that represents each of the components of the ICP entry are stored
  immediately following the ICP entry header. The format is log_url,
  SignedLogRoot, and inclusion proof hashes.

  Attributes:
    log_url_size: Length of the string representing the transparency log URL.
    leaf_index: Leaf index in the transparency log representing this entry.
    log_root_descriptor_size: Size of the transparency log's SignedLogRoot.
    fw_info_leaf_size: Size of the FirmwareInfo leaf passed to the log.
    log_root_sig_size: Size in bytes of the log_root_signature
    proof_hash_count: Number of hashes comprising the inclusion proof.
    inc_proof_size: The total size of the inclusion proof, in bytes.
    log_url: The URL for the transparency log that generated this inclusion
        proof.
    log_root_descriptor: The data comprising the signed tree head structure.
    fw_info_leaf: The data comprising the FirmwareInfo leaf.
    log_root_signature: The data comprising the log root signature.
    proofs: The hashes comprising the inclusion proof.

  """
  SIZE = 27  # The size of the structure, in bytes
  FORMAT_STRING = ('!L'   # transparency log server url size
                   'Q'    # leaf index
                   'L'    # log root descriptor size
                   'L'    # firmware info leaf size
                   'H'    # log root signature size
                   'B'    # number of hashes in the inclusion proof
                   'L')   # size of the inclusion proof in bytes
  # These are used to capture the log_url, log_root_descriptor,
  # fw_info leaf, log root signature, and the proofs elements for the
  # encode & save functions.

  def __init__(self, data=None):
    """Initializes a new ICP entry object.

    Arguments:
      data: If not None, must be a bytearray of size >= |SIZE|.

    Raises:
      AftlError: If data does not represent a well-formed AftlIcpEntry.
    """
    # Assert the header structure is of a sane size.
    assert struct.calcsize(self.FORMAT_STRING) == self.SIZE

    if data:
      # Deserialize the header from the data descriptor.
      (self.log_url_size, self.leaf_index, self.log_root_descriptor_size,
       self.fw_info_leaf_size, self.log_root_sig_size, self.proof_hash_count,
       self.inc_proof_size) = struct.unpack(
           self.FORMAT_STRING, data[0:self.SIZE])

      # Deserialize ICP entry components from the data descriptor.
      expected_format_string = '{}s{}s{}s{}s{}s'.format(
          self.log_url_size,
          self.log_root_descriptor_size,
          self.fw_info_leaf_size,
          self.log_root_sig_size,
          self.inc_proof_size)

      (self.log_url, log_root_descriptor_bytes, self.fw_info_leaf,
       self.log_root_signature, proof_bytes) = struct.unpack(
           expected_format_string, data[self.SIZE:self.get_expected_size()])
      self.log_root_descriptor = TrillianLogRootDescriptor(
          log_root_descriptor_bytes)
      self.proofs = []
      if self.proof_hash_count > 0:
        proof_idx = 0
        hash_size = self.inc_proof_size // self.proof_hash_count
        for _ in range(self.proof_hash_count):
          proof = proof_bytes[proof_idx:(proof_idx+hash_size)]
          self.proofs.append(proof)
          proof_idx += hash_size
    else:
      self.log_url_size = 0
      self.leaf_index = 0
      self.fw_info_leaf_size = 0
      self.log_root_sig_size = 0
      self.proof_hash_count = 0
      self.inc_proof_size = 0
      self.log_url = ''
      self.log_root_descriptor = TrillianLogRootDescriptor()
      log_root_descriptor_size = self.log_root_descriptor.get_expected_size()
      self.log_root_descriptor_size = log_root_descriptor_size
      self.fw_info_leaf = ''
      self.log_root_signature = ''
      self.proofs = []
    if not self.is_valid():
      raise AftlError('Invalid structure for AftlIcpEntry')

  def set_log_url(self, log_url):
    """Sets the log_url and log_url_size elements in the AftlIcpEntry.

    Arguments:
      log_url: The string representing the transparency log URL.
    """
    self.log_url = log_url
    self.log_url_size = len(log_url)

  def set_log_root_descriptor(self, log_root_descriptor):
    """Sets signed_root_descriptor and signed_root_descriptor_size.

    Arguments:
      log_root_descriptor: A TrillianLogRootDescriptor containing the
      log_root for the transparency log.
    """
    if not isinstance(log_root_descriptor, TrillianLogRootDescriptor):
      raise AftlError('Invalid data type passed to set_log_root_descriptor: '
                      'Received {}.\n'.format(type(log_root_descriptor)))
    self.log_root_descriptor = log_root_descriptor
    self.log_root_descriptor_size = log_root_descriptor.get_expected_size()

  def set_proofs(self, proofs):
    """Sets the proof_hash_count, proofs, and inc_proof_size.

    Arguments:
      proofs: A bytearray of concatenated hashes comprising the inclusion proof.
    """
    self.proof_hash_count = 0
    self.proofs = proofs
    inc_proof_size = 0
    for proof in proofs:
      inc_proof_size += len(proof)
      self.proof_hash_count += 1
    self.inc_proof_size = inc_proof_size

  def verify_icp(self, transparency_log_pub_key):
    """Verifies the contained inclusion proof given the public log key.

    Arguments:
      transparency_log_pub_key: The trusted public key for the log.

    Returns:
      True if the calculated signature matches AftlIcpEntry's. False otherwise.
    """
    leaf_hash = rfc6962_hash_leaf(self.fw_info_leaf)
    calc_root = root_from_icp(self.leaf_index,
                              self.log_root_descriptor.tree_size,
                              self.proofs,
                              leaf_hash)
    if ((calc_root == self.log_root_descriptor.root_hash) and
        check_signature(
            self.log_root_descriptor.log_root,
            self.log_root_signature,
            transparency_log_pub_key)):
      return True
    return False

  def save(self, output):
    """Serializes the transparency header |SIZE| and data to disk.

    Arguments:
      output: The object to write the header to.

    Raises:
      AftlError: If invalid entry structure.
    """
    output.write(self.encode())

  def encode(self):
    """Serializes the header |SIZE| and data to a bytearray().

    Returns:
      A bytearray() with the encoded header.

    Raises:
      AftlError: If invalid entry structure.
    """
    proof_bytes = bytearray()
    if not self.is_valid():
      raise AftlError('Invalid AftlIcpEntry structure')

    expected_format_string = '{}{}s{}s{}s{}s{}s'.format(
        self.FORMAT_STRING,
        self.log_url_size,
        self.log_root_descriptor_size,
        self.fw_info_leaf_size,
        self.log_root_sig_size,
        self.inc_proof_size)

    for proof in self.proofs:
      proof_bytes.extend(proof)

    return struct.pack(expected_format_string,
                       self.log_url_size, self.leaf_index,
                       self.log_root_descriptor_size, self.fw_info_leaf_size,
                       self.log_root_sig_size, self.proof_hash_count,
                       self.inc_proof_size, self.log_url,
                       self.log_root_descriptor.encode(),
                       str(self.fw_info_leaf),
                       str(self.log_root_signature),
                       str(proof_bytes))

  # TODO(danielaustin): Add unit test.
  def translate_response(self, transparency_log, afi_response):
    """Translates an AddFirmwareInfoResponse object to an AftlIcpEntry.

    Arguments:
      transparency_log: String representing the transparency log URL.
      afi_response: The AddFirmwareResponse object to translate.
    """
    self.set_log_url(transparency_log)
    self.leaf_index = afi_response.fw_info_proof.proof.leaf_index
    self.log_root_descriptor = TrillianLogRootDescriptor(
        afi_response.fw_info_proof.sth.log_root)
    self.log_root_signature = afi_response.fw_info_proof.sth.log_root_signature
    self.log_root_sig_size = len(self.log_root_signature)
    self.log_root_descriptor_size = self.log_root_descriptor.get_expected_size()

    proof_hashes = afi_response.fw_info_proof.proof.hashes
    self.set_proofs(proof_hashes)

  def get_expected_size(self):
    """Gets the expected size of the full entry out of the header.

    Returns:
      The expected size of the AftlIcpEntry from the header.
    """
    return (self.SIZE + self.log_url_size + self.log_root_descriptor_size +
            self.fw_info_leaf_size + self.log_root_sig_size +
            self.inc_proof_size)

  def is_valid(self):
    """Ensures that values in an AftlIcpEntry structure are sane.

    Returns:
      True if the values in the AftlIcpEntry are sane, False otherwise.
    """
    if ((self.log_url and self.log_url_size != len(self.log_url))
        or (not self.log_url and self.log_url_size != 0)):
      sys.stderr.write('ICP entry: invalid URL size: {}\n'
                       .format(self.log_url_size))
      return False

    if self.leaf_index < 0:
      sys.stderr.write('ICP entry: leaf index out of range: '
                       '{}\n'.format(self.leaf_index))
      return False

    if (not self.log_root_descriptor or
        not self.log_root_descriptor.is_valid()):
      sys.stderr.write('ICP entry: invalid TrillianLogRootDescriptor\n')
      return False

    if (self.log_root_descriptor_size !=
        self.log_root_descriptor.get_expected_size()):
      sys.stderr.write('ICP entry: invalid signed root descriptor size: '
                       '{}, should be {}\n'.format(
                           self.log_root_descriptor_size,
                           self.log_root_descriptor.get_expected_size()))
      return False

    if ((self.fw_info_leaf and self.fw_info_leaf_size != len(self.fw_info_leaf))
        or (not self.fw_info_leaf and self.fw_info_leaf_size != 0)):
      sys.stderr.write('ICP entry: invalid FirmwareInfo size: {}\n'
                       .format(self.fw_info_leaf_size))
      return False

    if self.proof_hash_count < 0:
      sys.stderr.write('ICP entry: invalid proof count: {}\n'.format(
          self.proof_hash_count))
      return False

    inc_proof_size = 0
    if self.proofs:
      for proof in self.proofs:
        inc_proof_size += len(proof)
      if self.inc_proof_size != inc_proof_size:
        sys.stderr.write('ICP entry: invalid transparency log proof size: ')
        sys.stderr.write('{}, calculated {}\n'.format(self.inc_proof_size,
                                                      inc_proof_size))
        return False
    elif self.inc_proof_size != 0:
      sys.stderr.write('ICP entry: invalid transparency log proof size '
                       '(should be 0): {}'.format(self.inc_proof_size))
      return False

    return True

  def print_desc(self, o):
    """Print the descriptor.

    Arguments:
      o: The object to write the output to.
    """
    o.write('    Transparency Log:   {}\n'.format(self.log_url))
    o.write('    Leaf index:         {}\n'.format(self.leaf_index))
    o.write('    ICP hashes:         ')
    for i, proof_hash in enumerate(self.proofs):
      if i != 0:
        o.write(' ' * 24)
      o.write('{}\n'.format(binascii.hexlify(proof_hash)))


class TrillianLogRootDescriptor(object):
  """A class representing the Trillian log_root descriptor.

  Taken from Trillian definitions:
  https://github.com/google/trillian/blob/master/trillian.proto#L255

  Attributes:
    version: The version number of the descriptor. Currently only version=1 is
        supported.
    tree_size: The size of the tree.
    root_hash_size: The size of the root hash in bytes. Valid values are between
        0 and 128.
    root_hash: The root hash as bytearray().
    timestamp: The timestamp in nanoseconds.
    revision: The revision number as long.
    metadata_size: The size of the metadata in bytes. Valid values are between
        0 and 65535.
    metadata: The metadata as bytearray().
  """
  FORMAT_STRING_PART_1 = ('!H'  # version
                          'Q'   # tree_size
                          'B'   # root_hash_size
                         )

  FORMAT_STRING_PART_2 = ('!Q'  # timestamp
                          'Q'   # revision
                          'H'   # metadata_size
                         )

  def __init__(self, data=None):
    """Initializes a new TrillianLogRoot descriptor."""
    if data:
      # Parses first part of the log_root descriptor.
      data_length = struct.calcsize(self.FORMAT_STRING_PART_1)
      (self.version, self.tree_size, self.root_hash_size) = struct.unpack(
          self.FORMAT_STRING_PART_1, data[0:data_length])
      data = data[data_length:]

      # Parses the root_hash bytes if the size indicates existance.
      if self.root_hash_size > 0:
        self.root_hash = data[0:self.root_hash_size]
        data = data[self.root_hash_size:]
      else:
        self.root_hash = bytearray()

      # Parses second part of the log_root descriptor.
      data_length = struct.calcsize(self.FORMAT_STRING_PART_2)
      (self.timestamp, self.revision, self.metadata_size) = struct.unpack(
          self.FORMAT_STRING_PART_2, data[0:data_length])
      data = data[data_length:]

      # Parses the metadata if the size indicates existance.
      if self.metadata_size > 0:
        self.metadata = data[0:self.metadata_size]
      else:
        self.metadata = bytearray()
    else:
      self.version = 1
      self.tree_size = 0
      self.root_hash_size = 0
      self.root_hash = bytearray()
      self.timestamp = 0
      self.revision = 0
      self.metadata_size = 0
      self.metadata = bytearray()

    if not self.is_valid():
      raise AftlError('Invalid structure for TrillianLogRootDescriptor.')

  def get_expected_size(self):
    """Calculates the expected size of the TrillianLogRootDescriptor.

    Returns:
      The expected size of the TrillianLogRootDescriptor.
    """
    return (struct.calcsize(self.FORMAT_STRING_PART_1) + self.root_hash_size +
            struct.calcsize(self.FORMAT_STRING_PART_2) + self.metadata_size)

  def encode(self):
    """Serializes the TrillianLogDescriptor to a bytearray().

    Returns:
      A bytearray() with the encoded header.

    Raises:
      AftlError: If invalid entry structure.
    """
    if not self.is_valid():
      raise AftlError('Invalid structure for TrillianLogRootDescriptor.')

    expected_format_string = '{}{}s{}{}s'.format(
        self.FORMAT_STRING_PART_1,
        self.root_hash_size,
        self.FORMAT_STRING_PART_2[1:],
        self.metadata_size)

    return struct.pack(expected_format_string,
                       self.version, self.tree_size, self.root_hash_size,
                       str(self.root_hash), self.timestamp, self.revision,
                       self.metadata_size, str(self.metadata))

  def is_valid(self):
    """Ensures that values in the descritor are sane.

    Returns:
      True if the values are sane; otherwise False.
    """
    cls = self.__class__.__name__
    if self.version != 1:
      sys.stderr.write('{}: Bad version value {}.'.format(cls, self.version))
      return False
    if self.tree_size < 0:
      sys.stderr.write('{}: Bad tree_size value {}.'.format(cls,
                                                            self.tree_size))
      return False
    if self.root_hash_size < 0 or self.root_hash_size > 128:
      sys.stderr.write('{}: Bad root_hash_size value {}.'.format(
          cls, self.root_hash_size))
      return False
    if len(self.root_hash) != self.root_hash_size:
      sys.stderr.write('{}: root_hash_size {} does not match with length of '
                       'root_hash {}.'.format(cls, self.root_hash_size,
                                              len(self.root_hash)))
      return False
    if self.timestamp < 0:
      sys.stderr.write('{}: Bad timestamp value {}.'.format(cls,
                                                            self.timestamp))
      return False
    if self.revision < 0:
      sys.stderr.write('{}: Bad revision value {}.'.format(cls, self.revision))
      return False
    if self.metadata_size < 0 or self.metadata_size > 65535:
      sys.stderr.write('{}: Bad metadatasize value {}.'.format(
          cls, self.metadata_size))
      return False
    if len(self.metadata) != self.metadata_size:
      sys.stderr.write('{}: metadata_size {} does not match with length of'
                       'metadata {}'.format(cls, self.metadata_size,
                                            len(self.metadata)))
      return False
    return True

  def print_desc(self, o):
    """Print the descriptor.

    Arguments:
      o: The object to write the output to.
    """
    i = ' ' * 8
    o.write('{}Version:          {}\n'.format(i, self.version))
    o.write('{}Tree size:        {}\n'.format(i, self.tree_size))
    o.write('{}Root hash size:   {}\n'.format(i, self.root_hash_size))
    if self.root_hash_size > 0:
      o.write('{}Root hash:        {}\n'.format(
          i, binascii.hexlify(self.root_hash)))
      o.write('{}Timestamp (ns):   {}\n'.format(i, self.timestamp))
    o.write('{}Revision:         {}\n'.format(i, self.revision))
    o.write('{}Metadata size:    {}\n'.format(i, self.metadata_size))
    if self.metadata_size > 0:
      o.write('{}Metadata:         {}\n'.format(i, self.metadata))


class AftlDescriptor(object):
  """A class for the transparency log inclusion proof descriptor.

  This encapsulates an AFTL ICP section with all information required to
  validate an inclusion proof.

  Attributes:
    icp_header: A header for the section.
    icp_entries: A list of AftlIcpEntry objects representing the inclusion
        proofs.
  """

  def __init__(self, data=None):
    """Initializes a new AftlDescriptor section.

    Arguments:
      data: If not None, must be a bytearray representing an AftlDescriptor.

    Raises:
      AftlError: If the data does not represent a well-formed AftlDescriptor.
    """
    if data:
      icp_header_bytes = data[0:AftlIcpHeader.SIZE]
      self.icp_header = AftlIcpHeader(icp_header_bytes)
      if not self.icp_header.is_valid():
        raise AftlError('Invalid ICP header.')
      icp_count = self.icp_header.icp_count

      # Jump past the header for entry deserialization.
      icp_index = AftlIcpHeader.SIZE
      # Validate each entry.
      self.icp_entries = []
      # Add_icp_entry updates entries and header, so set header count to
      # compensate.
      self.icp_header.icp_count = 0
      for i in range(icp_count):
        # Get the entry header from the AftlDescriptor.
        cur_icp_entry = AftlIcpEntry(data[icp_index:])
        cur_icp_entry_size = cur_icp_entry.get_expected_size()
        # Now validate the entry structure.
        if not cur_icp_entry.is_valid():
          raise AftlError('Validation of ICP entry {} failed.'.format(i))
        self.add_icp_entry(cur_icp_entry)
        icp_index += cur_icp_entry_size
    else:
      self.icp_header = AftlIcpHeader()
      self.icp_entries = []
    if not self.is_valid():
      raise AftlError('Malformed AFTLDescriptor')

  def add_icp_entry(self, avb_icp_entry):
    """Adds a new AftlIcpEntry to the AftlDescriptor, updating fields as needed.

    Arguments:
      avb_icp_entry: An AftlIcpEntry structure.
    """

    # Set the next entry field to denote that a new ICP entry will follow.
    self.icp_entries.append(avb_icp_entry)
    self.icp_header.icp_count += 1

  def save(self, output):
    """Serializes the AftlDescriptor to disk.

    Arguments:
      output: The object to write the descriptor to.

    Raises:
      AftlError: If invalid descriptor structure.
    """
    output.write(self.encode())

  def encode(self):
    """Serialize the AftlDescriptor to a bytearray().

    Returns:
      A bytearray() with the encoded header.

    Raises:
      AftlError: If invalid descriptor structure.
    """
    # The header and entries are guaranteed to be valid when encode is called.
    # Check the entire structure as a whole.
    if not self.is_valid():
      raise AftlError('Invalid AftlDescriptor structure.')

    icp_descriptor = bytearray()
    icp_descriptor.extend(self.icp_header.encode())
    for icp_entry in self.icp_entries:
      icp_descriptor.extend(icp_entry.encode())
    return icp_descriptor

  def is_valid(self):
    """Ensures that values in the AftlDescriptor are sane.

    Returns:
      True if the values in the AftlDescriptor are sane, False otherwise.
    """
    if not self.icp_header.is_valid():
      return False

    if self.icp_header.icp_count != len(self.icp_entries):
      return False

    for icp_entry in self.icp_entries:
      if not icp_entry.is_valid():
        return False
    return True

  def print_desc(self, o):
    """Print the descriptor.

    Arguments:
      o: The object to write the output to.
    """
    o.write('Android Firmware Transparency Descriptor:\n')
    o.write('  Header:\n')
    self.icp_header.print_desc(o)
    for i, icp_entry in enumerate(self.icp_entries):
      o.write('  Entry #{}:\n'.format(i + 1))
      icp_entry.print_desc(o)
      o.write('    Log Root Descriptor:\n')
      icp_entry.log_root_descriptor.print_desc(o)


class AftlCommunication(object):
  """Class to abstract the communication layer with the transparency log."""

  def __init__(self, transparency_log):
    """Initializes the object.

    Arguments:
      transparency_log: String containing the URL of a transparency log server.

    """
    self.transparency_log = transparency_log

  def AddFirmwareInfo(self, request):
    """Calls the AddFirmwareInfo RPC on the AFTL server.

    Arguments:
      request: A AddFirmwareInfoRequest message.

    Returns:
      An AddFirmwareInfoReponse message.

    Raises:
      AftlError: If grpc or the proto modules cannot be loaded, if there is an
        error communicating with the log.
    """
    raise NotImplementedError(
        'AddFirmwareInfo() needs to be implemented by subclass.')


class AftlGrpcCommunication(AftlCommunication):
  """Class that implements GRPC communication to the AFTL server."""

  def AddFirmwareInfo(self, request):
    """Calls the AddFirmwareInfo RPC on the AFTL server

    Arguments:
      request: A AddFirmwareInfoRequest message.

    Returns:
      An AddFirmwareInfoReponse message.

    Raises:
      AftlError: If grpc or the proto modules cannot be loaded, if there is an
        error communicating with the log.
    """
    # Import grpc now to avoid global dependencies as it otherwise breakes
    # running unittest with atest.
    try:
      import grpc
      import proto.api_pb2_grpc
    except ImportError as e:
      err_str = 'grpc can be installed with python pip install grpcio.\n'
      raise AftlError('Failed to import module: ({}).\n{}'.format(e, err_str))

    # Set up the gRPC channel with the transparency log.
    sys.stdout.write('Preparing to request inclusion proof from {}. This could '
                     'take ~30 seconds for the process to complete.\n'.format(
                         self.transparency_log))
    channel = grpc.insecure_channel(self.transparency_log)
    stub = proto.api_pb2_grpc.AFTLogStub(channel)

    # Attempt to transmit to the transparency log.
    sys.stdout.write('ICP is about to be requested from transparency log '
                     'with domain {}.\n'.format(self.transparency_log))
    try:
      # TODO(danielaustin): Set a reasonable timeout deadline here.
      response = stub.AddFirmwareInfo(request)
    except grpc.RpcError as e:
      raise AftlError('Error: grpc failure ({})'.format(e))
    return response


class Aftl(avbtool.Avb):
  """Business logic for aftltool command-line tool."""

  def info_image_icp(self, image_filename, output):
    """Implements the 'info_image_icp' command.

    Arguments:
      image_filename: Image file to get information from.
      output: Output file to write human-readable information to (file object).
    """
    image = avbtool.ImageHandler(image_filename)
    o = output
    (footer, header, _, _) = self._parse_image(image)

    offset = 0
    if footer:
      offset = footer.vbmeta_offset
    image.seek(offset +
               header.SIZE +
               header.authentication_data_block_size +
               header.auxiliary_data_block_size)

    # Parse the header out to get the AftlDescriptor size.
    tmp_header_bytes = image.read(AftlIcpHeader.SIZE)
    try:
      tmp_header = AftlIcpHeader(tmp_header_bytes)
    except AftlError:
      sys.stderr.write('This image does not contain a valid AftlDescriptor.\n')
      return
    # Reset to the beginning of the AftlDescriptor.
    image.seek(offset +
               header.SIZE +
               header.authentication_data_block_size +
               header.auxiliary_data_block_size)
    icp_bytes = image.read(tmp_header.aftl_descriptor_size)

    icp_descriptor = AftlDescriptor(icp_bytes)
    icp_descriptor.print_desc(o)

  def request_inclusion_proof(self, transparency_log, vbmeta_descriptor,
                              version_inc, manufacturer_key_path,
                              signing_helper, signing_helper_with_files,
                              aftl_comms=None):
    """Packages and sends a request to the specified transparency log.

    Arguments:
      transparency_log: String containing the URL of a transparency log server.
      vbmeta_descriptor: A bytearray with the vbmeta descriptor.
      version_inc: Subcomponent of the build fingerprint.
      manufacturer_key_path: Path to key used to sign messages sent to the
        transparency log servers.
      signing_helper: Program which signs a hash and returns a signature.
      signing_helper_with_files: Same as signing_helper but uses files instead.
      aftl_comms: A subclass of the AftlCommunication class. The default is
        to use AftlGrpcCommunication.

    Returns:
      An AftlIcpEntry with the inclusion proof for the log entry.

    Raises:
      AftlError: If grpc or the proto modules cannot be loaded, if there is an
         error communicating with the log, if the manufacturer_key_path
         cannot be decoded, or if the log submission cannot be signed.
    """
    # Calculate the hash of the vbmeta image.
    hasher = hashlib.sha256()
    hasher.update(vbmeta_descriptor)
    vbmeta_hash = hasher.digest()
    # Extract the key data from the PEM file.
    manufacturer_key_data = rsa_key_read_pem_bytes(manufacturer_key_path)
    # Calculate the hash of the manufacturer key data.
    hasher = hashlib.sha256()
    hasher.update(manufacturer_key_data)
    m_key_hash = hasher.digest()
    # Create an AddFirmwareInfoRequest protobuf for transmission to the
    # transparency log.
    fw_info = proto.aftl_pb2.FirmwareInfo(vbmeta_hash=vbmeta_hash,
                                          version_incremental=version_inc,
                                          manufacturer_key_hash=m_key_hash)
    signed_fw_info = bytearray()
    # AFTL supports SHA256_RSA4096 for now, more will be available.
    algorithm_name = 'SHA256_RSA4096'
    sig_num_bytes = 0
    alg_padding = ''
    try:
      alg = avbtool.ALGORITHMS[algorithm_name]
      sig_num_bytes = alg.signature_num_bytes
      alg_padding = alg.padding
    except KeyError:
      raise AftlError('Unknown algorithm with name {}'.format(algorithm_name))

    hasher = hashlib.sha256()
    hasher.update(fw_info.SerializeToString())
    fw_info_hash = hasher.digest()
    padding_and_hash = str(bytearray(alg_padding)) + fw_info_hash
    try:
      signed_fw_info = avbtool.raw_sign(signing_helper,
                                        signing_helper_with_files,
                                        algorithm_name,
                                        sig_num_bytes,
                                        manufacturer_key_path,
                                        padding_and_hash)
    except avbtool.AvbError as e:
      raise AftlError('Failed to sign FirmwareInfo with '
                      '--manufacturer_key: {}'.format(e))
    fw_info_sig = proto.crypto.sigpb.sigpb_pb2.DigitallySigned(
        hash_algorithm='SHA256',
        signature_algorithm='RSA',
        signature=str(signed_fw_info))

    sfw_info = proto.aftl_pb2.SignedFirmwareInfo(info=fw_info,
                                                 info_signature=fw_info_sig)
    request = proto.api_pb2.AddFirmwareInfoRequest(vbmeta=bytes(
        str(vbmeta_descriptor)), fw_info=sfw_info)

    # Submit signed FirmwareInfo to the server.
    if not aftl_comms:
      aftl_comms = AftlGrpcCommunication(transparency_log)
    response = aftl_comms.AddFirmwareInfo(request)

    # Return an AftlIcpEntry representing this response.
    icp_entry = AftlIcpEntry()
    icp_entry.fw_info_leaf = fw_info
    icp_entry.translate_response(transparency_log, response)
    return icp_entry

  def make_icp_from_vbmeta(self, vbmeta_image_path, output,
                           signing_helper, signing_helper_with_files,
                           version_incremental, transparency_log_servers,
                           transparency_log_pub_keys, manufacturer_key,
                           padding_size):
    """Generates a vbmeta image with inclusion proof given a vbmeta image.

    The descriptor (struct AftlDescriptor) contains the information required to
    validate an inclusion proof for a specific vbmeta image. It consists
    of a header (struct AftlIcpHeader) and zero or more entry structures
    (struct AftlIcpEntry) that contain the vbmeta leaf hash, tree size,
    root hash, inclusion proof hashes, and the signature for the root hash.

    The vbmeta image, its hash, the version_incremental part of the build
    fingerprint, and the hash of the manufacturer key are sent to the
    transparency log, with the message signed by the manufacturer key.
    An inclusion proof is calculated and returned. This inclusion proof is
    then packaged in a AftlDescriptor structure. The existing vbmeta data is
    copied to a new file, appended with the AftlDescriptor data, and written to
    output. Validation of the inclusion proof does not require
    communication with the transparency log.

    Arguments:
      vbmeta_image_path: Path to a vbmeta image file.
      output: File to write the results to.
      signing_helper: Program which signs a hash and returns a signature.
      signing_helper_with_files: Same as signing_helper but uses files instead.
      version_incremental: A string representing the subcomponent of the
        build fingerprint used to identify the vbmeta in the transparency log.
      transparency_log_servers: List of strings containing URLs of transparency
        log servers where inclusion proofs are requested from.
      transparency_log_pub_keys: List of paths to PEM files containing trusted
        public keys that correspond with the transparency_logs. There must be
        the same number of keys as log servers and they must be in the same
        order, that is, transparency_log_pub_keys[n] corresponds to
        transparency_log_servers[n].
      manufacturer_key: Path to PEM file containting the key file used to sign
        messages sent to the transparency log servers.
      padding_size: If not 0, pads output so size is a multiple of the number.

    Returns:
      True if the inclusion proofs could be fetched from the transparency log
      servers and could be successfully validated, False otherwise.

    Raises:
      AftlError: If any parameters are invalid, communication with the log
      fails or the structures are malformed.
    """
    # TODO(danielaustin): Determine the best way to handle chained vbmeta
    # structures. Currently, we only put the main one in the transparency
    # log.

    # Validates command line parameters.
    if len(transparency_log_servers) != len(transparency_log_pub_keys):
      raise AftlError('Transparency log count and public key count mismatch: '
                      '{} servers and {} public keys'.format(
                          len(transparency_log_servers),
                          len(transparency_log_pub_keys)))

    # Retrieves vbmeta structure from given partition image.
    image = avbtool.ImageHandler(vbmeta_image_path)
    (footer, header, _, _) = self._parse_image(image)
    offset = 0
    if footer:
      offset = footer.vbmeta_offset
    image.seek(offset)
    vbmeta_image = image.read(header.SIZE +
                              header.authentication_data_block_size +
                              header.auxiliary_data_block_size)

    #  Fetches inclusion proofs for vbmeta structure from all transparency logs.
    icp_entries = []
    for i, transparency_log in enumerate(transparency_log_servers):
      try:
        icp_entry = self.request_inclusion_proof(transparency_log, vbmeta_image,
                                                 version_incremental,
                                                 manufacturer_key,
                                                 signing_helper,
                                                 signing_helper_with_files)
        # TODO(danielaustin): Update icp_entry to validate if the vbmeta image
        # matches with the ICP stored data, and store the correct ICP
        # in the icp_entry.
        if not icp_entry.verify_icp(transparency_log_pub_keys[i]):
          sys.stderr.write('The ICP from {} could not be verified\n'.format(
              transparency_log))
        icp_entries.append(icp_entry)
      except AftlError as e:
        sys.stderr.write('AftlError: {}'.format(e))
        # The inclusion proof request failed.
        # Continue and see if another will succeed.
        continue
    if not icp_entries:
      sys.stderr.write('No inclusion proofs could be validated from any log.\n')
      return False

    # Prepares the AFTL descriptor to be appended to the vbmeta image.
    aftl_descriptor = AftlDescriptor()
    for icp_entry in icp_entries:
      aftl_descriptor.add_icp_entry(icp_entry)
    if not aftl_descriptor.is_valid():
      sys.stderr.write('Resulting AftlDescriptor structure is malformed\n.')
      return False

    # Write the original vbmeta descriptor, followed by the AftlDescriptor.
    if footer:  # Checks if it is a chained partition.
      # TODO(danielaustin): Add support for chained partitions like system.img
      # using similar functionality as implemented in append_vbmeta_image().
      sys.stderr.write('Image has a footer and ICP for this format is not '
                       'implemented.')
      return False

    # Writes vbmeta image with inclusion proof into a new vbmeta image.
    output.seek(0)
    output.write(vbmeta_image)
    encoded_aftl_descriptor = aftl_descriptor.encode()
    output.write(encoded_aftl_descriptor)

    if padding_size > 0:
      descriptor_size = len(vbmeta_image) + len(encoded_aftl_descriptor)
      padded_size = avbtool.round_to_multiple(descriptor_size, padding_size)
      padding_needed = padded_size - descriptor_size
      output.write('\0' * padding_needed)

    return True

  def _load_test_process_function(self, vbmeta_image_path,
                                  transparency_log_server,
                                  transparency_log_pub_key, manufacturer_key,
                                  process_number, submission_count,
                                  preserve_icp_images, result_queue):
    """Function to be used by multiprocessing.Process.

    Arguments:
      vbmeta_image_path: Path to a vbmeta image file.
      transparency_log_server: A string in host:port format of transparency log
        servers where a inclusion proof is requested from.
      transparency_log_pub_key: Path to PEM file containing trusted
        public keys that corresponds with the transparency_log_server.
      manufacturer_key: Path to PEM file containting the key file used to sign
        messages sent to the transparency log servers.
      process_number: The number of the processes executing the function.
      submission_count: Number of total submissions to perform per
        process_count.
      preserve_icp_images: Boolean to indicate if the generated vbmeta
        image files with inclusion proofs should preserved.
      result_queue: Multiprocessing.Queue object for posting execution results.
    """
    for count in range(0, submission_count):
      version_incremental = 'aftl_load_testing_{}_{}'.format(process_number,
                                                             count)
      output_file = '{}_icp.img'.format(version_incremental)
      output = open(output_file, 'wb')

      # Instrumented section.
      start_time = time.time()
      result = self.make_icp_from_vbmeta(
          vbmeta_image_path=vbmeta_image_path,
          output=output,
          signing_helper=None,
          signing_helper_with_files=None,
          version_incremental=version_incremental,
          transparency_log_servers=[transparency_log_server],
          transparency_log_pub_keys=[transparency_log_pub_key],
          manufacturer_key=manufacturer_key,
          padding_size=0)
      end_time = time.time()

      output.close()
      if not preserve_icp_images:
        os.unlink(output_file)

      # Puts the result onto the result queue.
      execution_time = end_time - start_time
      result_queue.put((start_time, end_time, execution_time,
                        version_incremental, result))

  def load_test_aftl(self, vbmeta_image_path, output, transparency_log_server,
                     transparency_log_pub_key, manufacturer_key,
                     process_count, submission_count, stats_filename,
                     preserve_icp_images):
    """Performs multi-threaded load test on a given AFTL and prints stats.

    Arguments:
      vbmeta_image_path: Path to a vbmeta image file.
      output: File to write the report to.
      transparency_log_server: A string in host:port format of transparency log
        servers where a inclusion proof is requested from.
      transparency_log_pub_key: Path to PEM file containing trusted
        public keys that corresponds with the transparency_log_server.
      manufacturer_key: Path to PEM file containting the key file used to sign
        messages sent to the transparency log servers.
      process_count: Number of processes used for parallel testing.
      submission_count: Number of total submissions to perform per
        process_count.
      stats_filename: Path to the stats file to write the raw execution data to.
      preserve_icp_images: Boolean to indicate if the generated vbmeta
        image files with inclusion proofs should preserved.

    Returns:
      True if the load tested succeeded without errors; otherwise False.
    """
    if process_count < 1 or submission_count < 1:
      sys.stderr.write('Values for --processes/--submissions '
                       'must be at least 1.')
      return False

    if not stats_filename:
      stats_filename = 'load_test_p{}_s{}.csv'.format(process_count,
                                                      submission_count)
    try:
      stats_file = open(stats_filename, 'w')
      stats_file.write('start_time,end_time,execution_time,version_incremental,'
                       'result\n')
    except IOError as e:
      sys.stderr.write('Could not open stats file {}: {}'.format(stats_file, e))
      return False

    # Launch all the processes with their workloads.
    result_queue = multiprocessing.Queue()
    processes = set()
    execution_times = []
    results = []
    for i in range(0, process_count):
      p = multiprocessing.Process(
          target=self._load_test_process_function,
          args=(vbmeta_image_path, transparency_log_server,
                transparency_log_pub_key, manufacturer_key, i, submission_count,
                preserve_icp_images, result_queue))
      p.start()
      processes.add(p)

    while processes:
      # Processes the results queue and writes these to a stats file.
      try:
        (start_time, end_time, execution_time, version_incremental,
         result) = result_queue.get(timeout=1)
        stats_file.write('{},{},{},{},{}\n'.format(start_time, end_time,
                                                   execution_time,
                                                   version_incremental, result))
        execution_times.append(execution_time)
        results.append(result)
      except Queue.Empty:
        pass

      # Checks if processes are still alive; if not clean them up. join() would
      # have been nicer but we want to continously stream out the stats to file.
      for p in processes.copy():
        if not p.is_alive():
          processes.remove(p)

    # Prepares stats.
    executions = sorted(execution_times)
    execution_count = len(execution_times)
    median = 0
    if execution_count % 2 == 0:
      median = (executions[execution_count // 2 - 1]
                + executions[execution_count // 2]) / 2
    else:
      median = executions[execution_count // 2]

    # Outputs the stats report.
    o = output
    o.write('Load testing results:\n')
    o.write('  Processes:               {}\n'.format(process_count))
    o.write('  Submissions per process: {}\n'.format(submission_count))
    o.write('\n')
    o.write('  Submissions:\n')
    o.write('    Total:                 {}\n'.format(len(executions)))
    o.write('    Succeeded:             {}\n'.format(results.count(True)))
    o.write('    Failed:                {}\n'.format(results.count(False)))
    o.write('\n')
    o.write('  Submission execution durations:\n')
    o.write('    Average:               {:.2f} sec\n'.format(
        sum(execution_times) / execution_count))
    o.write('    Median:                {:.2f} sec\n'.format(median))
    o.write('    Min:                   {:.2f} sec\n'.format(min(executions)))
    o.write('    Max:                   {:.2f} sec\n'.format(max(executions)))

    # Close the stats file.
    stats_file.close()
    return True


class AftlTool(avbtool.AvbTool):
  """Object for aftltool command-line tool."""

  def __init__(self):
    """Initializer method."""
    self.aftl = Aftl()
    super(AftlTool, self).__init__()

  def make_icp_from_vbmeta(self, args):
    """Implements the 'make_icp_from_vbmeta' sub-command."""
    args = self._fixup_common_args(args)
    self.aftl.make_icp_from_vbmeta(args.vbmeta_image_path,
                                   args.output,
                                   args.signing_helper,
                                   args.signing_helper_with_files,
                                   args.version_incremental,
                                   args.transparency_log_servers,
                                   args.transparency_log_pub_keys,
                                   args.manufacturer_key,
                                   args.padding_size)

  def info_image_icp(self, args):
    """Implements the 'info_image_icp' sub-command."""
    self.aftl.info_image_icp(args.vbmeta_image_path.name, args.output)

  def load_test_aftl(self, args):
    """Implements the 'load_test_aftl' sub-command."""
    self.aftl.load_test_aftl(args.vbmeta_image_path,
                             args.output,
                             args.transparency_log_server,
                             args.transparency_log_pub_key,
                             args.manufacturer_key,
                             args.processes,
                             args.submissions,
                             args.stats_file,
                             args.preserve_icp_images)

  def run(self, argv):
    """Command-line processor.

    Arguments:
      argv: Pass sys.argv from main.
    """
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers(title='subcommands')

    # Command: make_icp_from_vbmeta
    sub_parser = subparsers.add_parser('make_icp_from_vbmeta',
                                       help='Makes an ICP enhanced vbmeta image'
                                       ' from an existing vbmeta image.')
    sub_parser.add_argument('--output',
                            help='Output file name.',
                            type=argparse.FileType('wb'),
                            default=sys.stdout)
    sub_parser.add_argument('--vbmeta_image_path',
                            help='Path to a generate vbmeta image file.',
                            required=True)
    sub_parser.add_argument('--version_incremental',
                            help='Current build ID.',
                            required=True)
    sub_parser.add_argument('--manufacturer_key',
                            help='Path to the PEM file containing the '
                            'manufacturer key for use with the log.',
                            required=True)
    sub_parser.add_argument('--transparency_log_servers',
                            help='List of transparency log servers in '
                            'host:port format. This must not be None and must '
                            'be the same size as transparency_log_pub_keys. '
                            'Also, transparency_log_servers[n] must correspond '
                            'to transparency_log_pub_keys[n] for all values n.',
                            nargs='*',
                            required=True)
    sub_parser.add_argument('--transparency_log_pub_keys',
                            help='Paths to PEM files containing transparency '
                            'log server key(s). This must not be None and must '
                            'be the same size as transparency_log_servers. '
                            'Also, transparency_log_pub_keys[n] must '
                            'correspond to transparency_log_servers[n] for all '
                            'values n.',
                            nargs='*',
                            required=True)
    sub_parser.add_argument('--padding_size',
                            metavar='NUMBER',
                            help='If non-zero, pads output with NUL bytes so '
                            'its size is a multiple of NUMBER '
                            '(default: 0)',
                            type=avbtool.parse_number,
                            default=0)
    self._add_common_args(sub_parser)
    sub_parser.set_defaults(func=self.make_icp_from_vbmeta)

    # Command: info_image_icp
    sub_parser = subparsers.add_parser(
        'info_image_icp',
        help='Show information about AFTL ICPs in vbmeta or footer.')
    sub_parser.add_argument('--vbmeta_image_path',
                            help='Path to vbmeta image for AFTL information.',
                            type=argparse.FileType('rb'),
                            required=True)
    sub_parser.add_argument('--output',
                            help='Write info to file',
                            type=argparse.FileType('wt'),
                            default=sys.stdout)
    sub_parser.set_defaults(func=self.info_image_icp)

    # Command: load_test_aftl
    sub_parser = subparsers.add_parser(
        'load_test_aftl',
        help='Perform load testing against one AFTL log server. Note: This MUST'
        ' not be performed against a production system.')
    sub_parser.add_argument('--vbmeta_image_path',
                            help='Path to a generate vbmeta image file.',
                            required=True)
    sub_parser.add_argument('--output',
                            help='Write report to file.',
                            type=argparse.FileType('wt'),
                            default=sys.stdout)
    sub_parser.add_argument('--manufacturer_key',
                            help='Path to the PEM file containing the '
                            'manufacturer key for use with the log.',
                            required=True)
    sub_parser.add_argument('--transparency_log_server',
                            help='Transparency log servers to test against in '
                            'host:port format.',
                            required=True)
    sub_parser.add_argument('--transparency_log_pub_key',
                            help='Paths to PEM file containing transparency '
                            'log server key.',
                            required=True)
    sub_parser.add_argument('--processes',
                            help='Number of parallel processes to use for '
                            'testing (default: 1).',
                            type=avbtool.parse_number,
                            default=1)
    sub_parser.add_argument('--submissions',
                            help='Number of submissions to perform against the '
                            'log per process (default: 1).',
                            type=avbtool.parse_number,
                            default=1)
    sub_parser.add_argument('--stats_file',
                            help='Path to the stats file to write the raw '
                            'execution data to (Default: '
                            'load_test_p[processes]_s[submissions].csv.')
    sub_parser.add_argument('--preserve_icp_images',
                            help='Boolean flag to indicate if the generated '
                            'vbmeta image files with inclusion proofs should '
                            'preserved.',
                            action='store_true')
    sub_parser.set_defaults(func=self.load_test_aftl)

    args = parser.parse_args(argv[1:])
    try:
      args.func(args)
    except AftlError:
      # Indicate failure to signal to calling tools.
      sys.exit(1)

if __name__ == '__main__':
  tool = AftlTool()
  tool.run(sys.argv)