def _send_kexinit(self):
"""_send_kexinit(self) -> None
Sets self2remote.kexinit_packet.
Separate function to help with unittests.
"""
cookie = random.get_random_data(16)
server_keys = [x.name for x in self.self2remote.supported_server_keys]
server_keys.reverse()
packet = ssh_packet.pack_payload(
ssh_packet.PAYLOAD_MSG_KEXINIT,
(
SSH_MSG_KEXINIT,
cookie,
[x.name for x in self.self2remote.supported_key_exchanges],
# [x.name for x in self.self2remote.supported_server_keys],
server_keys,
[x.name for x in self.c2s.supported_ciphers],
[x.name for x in self.s2c.supported_ciphers],
[x.name for x in self.c2s.supported_macs],
[x.name for x in self.s2c.supported_macs],
[x.name for x in self.c2s.supported_compressions],
[x.name for x in self.s2c.supported_compressions],
[x.name for x in self.c2s.supported_languages],
[x.name for x in self.s2c.supported_languages],
self.self2remote.proactive_kex, # first_kex_packet_follows
0 # reserved
))
self.self2remote.kexinit_packet = packet
return packet
def _send_packet(self, data):
# Packet is:
# uint32 packet_length
# byte padding_length
# byte[n1] payload
# byte[n2] random padding
# byte[m] MAC
self.debug.write(ssh_debug.DEBUG_3, 'send_packet( len(data)=%i )',
(len(data), ))
data = self.self2remote.compression.compress(data)
# packet_len + padding_length + payload + random_padding
# must be multiple of cipher block size.
block_size = max(8, self.self2remote.cipher.block_size)
padding_length = block_size - ((5 + len(data)) % block_size)
if padding_length < 4:
padding_length += block_size
# Total packet size must also be at least 16 bytes.
base_size = 5 + len(data) + padding_length
minimum_size = max(16, block_size)
if base_size < minimum_size:
self.debug.write(ssh_debug.DEBUG_2,
'send_packet: base size too small')
# Add enough padding to make it big enough.
# Make a first guess of the padding length.
padding_length_guess = minimum_size - base_size
# See how much larger it should be to make it a multiple of the
# block size.
additional_padding_length = block_size - (
(5 + len(data) + padding_length_guess) % block_size)
padding_length = padding_length_guess + additional_padding_length
self.debug.write(ssh_debug.DEBUG_2, 'send_packet: padding_length=%i',
(padding_length, ))
self.debug.write(ssh_debug.DEBUG_2, 'send_packet: cipher=%s',
(self.self2remote.cipher.name, ))
packet_length = 1 + len(data) + padding_length
self.debug.write(ssh_debug.DEBUG_2, 'send_packet: packet_length=%i',
(packet_length, ))
random_padding = random.get_random_data(padding_length)
chunk = struct.pack('>Ic', packet_length,
chr(padding_length)) + data + random_padding
self.debug.write(ssh_debug.DEBUG_2, 'send_packet: chunk_length=%i',
(len(chunk), ))
mac = self.self2remote.mac.digest(
self.self2remote.packet_sequence_number, chunk)
self.self2remote.inc_packet_sequence_number()
self.debug.write(ssh_debug.DEBUG_2, 'send_packet: mac=%r', (mac, ))
# self.debug.write(ssh_debug.DEBUG_2, 'send_packet: chunk=%r', (chunk,))
encrypted_chunk = self.self2remote.cipher.encrypt(chunk)
# self.debug.write(ssh_debug.DEBUG_2, 'send_packet: encrypted_chunk=%r', (encrypted_chunk,))
self.transport.write(encrypted_chunk + mac)
