in aliyun-python-sdk-core/aliyunsdkcore/vendored/requests/packages/urllib3/packages/socks.py [0:0]
def _negotiate_SOCKS4(self, dest_addr, dest_port):
"""Negotiates a connection through a SOCKS4 server."""
proxy_type, addr, port, rdns, username, password = self.proxy
writer = self.makefile("wb")
reader = self.makefile("rb", 0) # buffering=0 renamed in Python 3
try:
# Check if the destination address provided is an IP address
remote_resolve = False
try:
addr_bytes = socket.inet_aton(dest_addr)
except socket.error:
# It's a DNS name. Check where it should be resolved.
if rdns:
addr_bytes = b"\x00\x00\x00\x01"
remote_resolve = True
else:
addr_bytes = socket.inet_aton(
socket.gethostbyname(dest_addr))
# Construct the request packet
writer.write(struct.pack(">BBH", 0x04, 0x01, dest_port))
writer.write(addr_bytes)
# The username parameter is considered userid for SOCKS4
if username:
writer.write(username)
writer.write(b"\x00")
# DNS name if remote resolving is required
# NOTE: This is actually an extension to the SOCKS4 protocol
# called SOCKS4A and may not be supported in all cases.
if remote_resolve:
writer.write(dest_addr.encode("idna") + b"\x00")
writer.flush()
# Get the response from the server
resp = self._readall(reader, 8)
if resp[0:1] != b"\x00":
# Bad data
raise GeneralProxyError(
"SOCKS4 proxy server sent invalid data")
status = ord(resp[1:2])
if status != 0x5A:
# Connection failed: server returned an error
error = SOCKS4_ERRORS.get(status, "Unknown error")
raise SOCKS4Error("{0:#04x}: {1}".format(status, error))
# Get the bound address/port
self.proxy_sockname = (socket.inet_ntoa(resp[4:]),
struct.unpack(">H", resp[2:4])[0])
if remote_resolve:
self.proxy_peername = socket.inet_ntoa(addr_bytes), dest_port
else:
self.proxy_peername = dest_addr, dest_port
finally:
reader.close()
writer.close()