class Server(object):
def __init__(self, boot_nodes):
# the endpoint of this server
# this is a fake ip address used in packets.
self.endpoint = EndPoint(u'127.0.0.1', 30303, 30303)
# boot nodes
self.boot_nodes = boot_nodes
# hold all of pending
self.pending_hold = []
# last pong received time of the special node id
self.last_pong_received = {}
# last ping received time of the special node id
self.last_ping_received = {}
# have the private key
priv_key_file = open('priv_key', 'r')
priv_key_serialized = priv_key_file.read()
priv_key_file.close()
self.priv_key = PrivateKey()
self.priv_key.deserialize(priv_key_serialized)
# routing table
self.table = RoutingTable(
Node(self.endpoint,
pubkey_format(self.priv_key.pubkey)[1:]), self)
# initialize UDP socket
self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.sock.bind(('0.0.0.0', self.endpoint.udpPort))
# set socket non-blocking mode
self.sock.setblocking(0)
def add_table(self, node):
self.table.add_node(node)
def add_pending(self, pending):
pending.start()
self.pending_hold.append(pending)
return pending
def run(self):
gevent.spawn(self.clean_pending)
gevent.spawn(self.listen)
# wait forever
evt = Event()
evt.wait()
def clean_pending(self):
while True:
for pending in list(self.pending_hold):
if not pending.is_alive:
self.pending_hold.remove(pending)
time.sleep(K_REQUEST_TIMEOUT)
def listen(self):
LOGGER.info("{:5} listening...".format(''))
while True:
ready = select([self.sock], [], [], 1.0)
if ready[0]:
data, addr = self.sock.recvfrom(2048)
# non-block data reading
gevent.spawn(self.receive, data, addr)
def receive(self, data, addr):
"""
macSize = 256 / 8 = 32
sigSize = 520 / 8 = 65
headSize = macSize + sigSize = 97
hash, sig, sigdata := buf[:macSize], buf[macSize:headSize], buf[headSize:]
shouldhash := crypto.Sha3(buf[macSize:])
"""
# verify hash
msg_hash = data[:32]
assert msg_hash == keccak256(
data[32:]), "First 32 bytes are not keccak256 hash of the rest"
# verify signature
signature = data[32:97]
signed_data = data[97:]
deserialized_sig = self.priv_key.ecdsa_recoverable_deserialize(
signature[:64], ord(signature[64]))
remote_pubkey = self.priv_key.ecdsa_recover(keccak256(signed_data),
deserialized_sig,
raw=True)
pub = PublicKey()
pub.public_key = remote_pubkey
verified = pub.ecdsa_verify(
keccak256(signed_data),
pub.ecdsa_recoverable_convert(deserialized_sig),
raw=True)
assert verified, "Signature invalid"
pubkey = pubkey_format(pub)[1:]
hex_id = binascii.hexlify(keccak256(pubkey))
packet_type = data[97]
payload = rlp.decode(data[98:])
if packet_type == PingNode.packet_type:
# fake ip in packet
payload[1][0] = addr[0]
ping = PingNode.unpack(payload)
if expired(ping):
return
self.receive_ping(addr, pubkey, ping, msg_hash)
elif packet_type == Pong.packet_type:
pong = Pong.unpack(payload)
if expired(pong):
return
self.receive_pong(addr, pubkey, pong)
elif packet_type == FindNeighbors.packet_type:
fn = FindNeighbors.unpack(payload)
if expired(fn):
return
self.receive_find_neighbors(addr, pubkey, fn)
elif packet_type == Neighbors.packet_type:
neighbours = Neighbors.unpack(payload)
if expired(neighbours):
return
self.receive_neighbors(addr, pubkey, neighbours)
else:
assert False, " Unknown message type: {}".format(packet_type)
def receive_pong(self, addr, pubkey, pong):
remote_id = keccak256(pubkey)
# response to ping
last_pong_received = self.last_pong_received
def match_callback():
# solicited reply
last_pong_received[remote_id] = time.time()
self.handle_reply(addr, pubkey, Pong.packet_type, pong, match_callback)
def receive_ping(self, addr, pubkey, ping, msg_hash):
remote_id = keccak256(pubkey)
endpoint_to = EndPoint(addr[0], ping.endpoint_from.udpPort,
ping.endpoint_from.tcpPort)
pong = Pong(endpoint_to, msg_hash, time.time() + K_EXPIRATION)
node_to = Node(pong.to, pubkey)
# sending Pong response
self.send_sock(pong, node_to)
LOGGER.info("{:5} {}@{}:{} (Pong)".format(
'---->',
binascii.hexlify(node_to.node_id)[:8], addr[0],
ping.endpoint_from.udpPort))
self.handle_reply(addr, pubkey, PingNode.packet_type, ping)
node = Node(endpoint_to, pubkey)
if time.time() - self.last_pong_received.get(remote_id,
0) > K_BOND_EXPIRATION:
self.ping(node, lambda: self.add_table(node))
else:
self.add_table(node)
self.last_ping_received[remote_id] = time.time()
def receive_find_neighbors(self, addr, pubkey, fn):
remote_id = keccak256(pubkey)
if time.time() - self.last_pong_received.get(remote_id,
0) > K_BOND_EXPIRATION:
# lost origin or origin is off
return
target_id = keccak256(fn.target)
closest = self.table.closest(target_id, BUCKET_SIZE)
# sent neighbours in chunks
ns = Neighbors([], time.time() + K_EXPIRATION)
sent = False
node_to = Node(EndPoint(addr[0], addr[1], addr[1]), pubkey)
for c in closest:
ns.nodes.append(c)
if len(ns.nodes) == K_MAX_NEIGHBORS:
self.send_sock(ns, node_to)
LOGGER.info("{:5} {}@{}:{} {}".format(
'---->',
binascii.hexlify(node_to.node_id)[:8], addr[0], addr[1],
ns))
ns.nodes = []
sent = True
if len(ns.nodes) > 0 or not sent:
self.send_sock(ns, node_to)
LOGGER.info("{:5} {}@{}:{} {}".format(
'---->',
binascii.hexlify(node_to.node_id)[:8], addr[0], addr[1], ns))
def receive_neighbors(self, addr, pubkey, neighbours):
# response to find neighbours
self.handle_reply(addr, pubkey, Neighbors.packet_type, neighbours)
def handle_reply(self,
addr,
pubkey,
packet_type,
packet,
match_callback=None):
remote_id = keccak256(pubkey)
is_match = False
for pending in self.pending_hold:
if pending.is_alive and packet_type == pending.packet_type:
if remote_id == pending.from_id:
is_match = True
pending.emit(packet)
match_callback and match_callback()
elif pending.ep is not None and pending.ep == addr:
LOGGER.error('{:5} {}@{}:{} mismatch request {}'.format(
'',
binascii.hexlify(remote_id)[:8], addr[0], addr[1],
binascii.hexlify(pending.from_id)[:8]))
# is_match = True
# pending.emit(packet)
# match_callback and match_callback()
# for bucket in self.table.buckets:
# for node in bucket.nodes:
# if node.node_id == pending.from_id:
# node.set_pubkey(pubkey)
if not is_match:
LOGGER.warning('{:5} {}@{}:{} ({}) unsolicited response'.format(
'<-//-',
binascii.hexlify(remote_id)[:8], addr[0], addr[1],
PACKET_TYPES.get(packet.packet_type)))
def ping(self, node, callback=None):
"""
send a ping request to the given node and return instantly
invoke callback while reply arrives
"""
ping = PingNode(self.endpoint, node.endpoint,
time.time() + K_EXPIRATION)
message = self.wrap_packet(ping)
msg_hash = message[:32]
def reply_call(chunks):
if chunks.pop().echo == msg_hash:
if callback is not None:
callback()
return True
ep = (node.endpoint.address.exploded, node.endpoint.udpPort)
pending = self.add_pending(Pending(node, Pong.packet_type, reply_call))
self.sock.sendto(message, ep)
LOGGER.info("{:5} {}@{}:{} (Ping)".format(
'---->',
binascii.hexlify(node.node_id)[:8], ep[0], ep[1]))
return pending
def find_neighbors(self, node, target_key):
"""
send a find neighbours request to the given node and
waits until the node has sent up to k neighbours
"""
node_id = node.node_id
if time.time() - self.last_ping_received.get(node_id,
0) > K_BOND_EXPIRATION:
send_ping = self.ping(node)
receive_ping = self.add_pending(
Pending(node, PingNode.packet_type, lambda _: True))
# wait until endpoint proof is finished
gevent.joinall([send_ping, receive_ping])
fn = FindNeighbors(target_key, time.time() + K_EXPIRATION)
def reply_call(chunks):
num_received = 0
for neighbors in chunks:
num_received += len(neighbors.nodes)
if num_received >= BUCKET_SIZE:
return True
pending = self.add_pending(
Pending(node, Neighbors.packet_type, reply_call, timeout=2))
self.send_sock(fn, node)
ep = (node.endpoint.address.exploded, node.endpoint.udpPort)
LOGGER.info("{:5} {}@{}:{} (FN {})".format(
'---->',
binascii.hexlify(node.node_id)[:8], ep[0], ep[1],
binascii.hexlify(keccak256(fn.target))[:8]))
# block to wait for neighbours
ret = pending.get()
if ret:
neighbor_nodes = []
for chunk in ret:
for n in chunk.nodes:
neighbor_nodes.append(n)
return neighbor_nodes
def send_sock(self, packet, node):
endpoint = node.endpoint
message = self.wrap_packet(packet)
ep = (endpoint.address.exploded, endpoint.udpPort)
self.sock.sendto(message, ep)
def wrap_packet(self, packet):
"""
UDP packets are structured as follows:
hash || signature || packet-type || packet-data
packet-type: single byte < 2**7 // valid values are [1,4]
packet-data: RLP encoded list. Packet properties are serialized in the order in
which they're defined. See packet-data below.
Offset |
0 | MDC | Ensures integrity of packet,
65 | signature | Ensures authenticity of sender, `SIGN(sender-privkey, MDC)`
97 | type | Single byte in range [1, 4] that determines the structure of Data
98 | data | RLP encoded, see section Packet Data
The packets are signed and authenticated. The sender's Node ID is determined by
recovering the public key from the signature.
sender-pubkey = ECRECOVER(Signature)
The integrity of the packet can then be verified by computing the
expected MDC of the packet as:
MDC = SHA3(sender-pubkey || type || data)
As an optimization, implementations may look up the public key by
the UDP sending address and compute MDC before recovering the sender ID.
If the MDC values do not match, the packet can be dropped.
"""
payload = packet.packet_type + rlp.encode(packet.pack())
sig = self.priv_key.ecdsa_sign_recoverable(keccak256(payload),
raw=True)
sig_serialized = self.priv_key.ecdsa_recoverable_serialize(sig)
payload = sig_serialized[0] + chr(sig_serialized[1]) + payload
payload_hash = keccak256(payload)
return payload_hash + payload
