PyBitmessage-2021-04-27/src/network/socks4a.py

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import socket
import struct
from proxy import Proxy, ProxyError, GeneralProxyError
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class Socks4aError(ProxyError):
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"""SOCKS4a error base class"""
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errorCodes = (
"Request granted",
"Request rejected or failed",
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"Request rejected because SOCKS server cannot connect to identd"
" on the client",
"Request rejected because the client program and identd report"
" different user-ids",
"Unknown error"
)
class Socks4a(Proxy):
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"""SOCKS4a proxy class"""
def __init__(self, address=None):
Proxy.__init__(self, address)
self.ipaddr = None
self.destport = address[1]
def state_init(self):
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"""Protocol initialisation (before connection is established)"""
self.set_state("auth_done", 0)
return True
def state_pre_connect(self):
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"""Handle feedback from SOCKS4a while it is connecting on our behalf"""
# Get the response
if self.read_buf[0:1] != chr(0x00).encode():
# bad data
self.close()
raise GeneralProxyError(1)
elif self.read_buf[1:2] != chr(0x5A).encode():
# Connection failed
self.close()
if ord(self.read_buf[1:2]) in (91, 92, 93):
# socks 4 error
raise Socks4aError(ord(self.read_buf[1:2]) - 90)
else:
raise Socks4aError(4)
# Get the bound address/port
self.boundport = struct.unpack(">H", self.read_buf[2:4])[0]
self.boundaddr = self.read_buf[4:]
self.__proxysockname = (self.boundaddr, self.boundport)
if self.ipaddr:
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self.__proxypeername = (
socket.inet_ntoa(self.ipaddr), self.destination[1])
else:
self.__proxypeername = (self.destination[0], self.destport)
self.set_state("proxy_handshake_done", length=8)
return True
def proxy_sock_name(self):
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"""
Handle return value when using SOCKS4a for DNS resolving
instead of connecting.
"""
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return socket.inet_ntoa(self.__proxysockname[0])
class Socks4aConnection(Socks4a):
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"""Child SOCKS4a class used for making outbound connections."""
def __init__(self, address):
Socks4a.__init__(self, address=address)
def state_auth_done(self):
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"""Request connection to be made"""
# Now we can request the actual connection
rmtrslv = False
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self.append_write_buf(
struct.pack('>BBH', 0x04, 0x01, self.destination[1]))
# If the given destination address is an IP address, we'll
# use the IPv4 address request even if remote resolving was specified.
try:
self.ipaddr = socket.inet_aton(self.destination[0])
self.append_write_buf(self.ipaddr)
except socket.error:
# Well it's not an IP number, so it's probably a DNS name.
if Proxy._remote_dns:
# Resolve remotely
rmtrslv = True
self.ipaddr = None
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self.append_write_buf(
struct.pack("BBBB", 0x00, 0x00, 0x00, 0x01))
else:
# Resolve locally
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self.ipaddr = socket.inet_aton(
socket.gethostbyname(self.destination[0]))
self.append_write_buf(self.ipaddr)
if self._auth:
self.append_write_buf(self._auth[0])
self.append_write_buf(chr(0x00).encode())
if rmtrslv:
self.append_write_buf(self.destination[0] + chr(0x00).encode())
self.set_state("pre_connect", length=0, expectBytes=8)
return True
def state_pre_connect(self):
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"""Tell SOCKS4a to initiate a connection"""
try:
return Socks4a.state_pre_connect(self)
except Socks4aError as e:
self.close_reason = e.message
self.set_state("close")
class Socks4aResolver(Socks4a):
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"""DNS resolver class using SOCKS4a"""
def __init__(self, host):
self.host = host
self.port = 8444
Socks4a.__init__(self, address=(self.host, self.port))
def state_auth_done(self):
# Now we can request the actual connection
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self.append_write_buf(
struct.pack('>BBH', 0x04, 0xF0, self.destination[1]))
self.append_write_buf(struct.pack("BBBB", 0x00, 0x00, 0x00, 0x01))
if self._auth:
self.append_write_buf(self._auth[0])
self.append_write_buf(chr(0x00).encode())
self.append_write_buf(self.host + chr(0x00).encode())
self.set_state("pre_connect", length=0, expectBytes=8)
return True
def resolved(self):
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"""
Resolving is done, process the return value. To use this within
PyBitmessage, a callback needs to be implemented which hasn't
been done yet.
"""
print "Resolved %s as %s" % (self.host, self.proxy_sock_name())