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Fix for issue #108 - Make sure the buffer is large enough before ever… #110

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Merged
merged 3 commits into from
Apr 19, 2023
Merged

Fix for issue #108 - Make sure the buffer is large enough before ever… #110

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c666a7b
Fix for issue #108 - Make sure the buffer is large enough before ever…
dgnuff Apr 9, 2023
34c4ab2
Fix for issue #108 - Remove global _BUFF and replace with local buff …
dgnuff Apr 14, 2023
a22a887
Fix for issue #108 - black formatting correction
dgnuff Apr 15, 2023
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151 changes: 75 additions & 76 deletions adafruit_wiznet5k/adafruit_wiznet5k_dhcp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -85,8 +85,8 @@
_LEASE_TIME = 51
_OPT_END = 255

# Packet buffer
_BUFF = bytearray(318)
# Packet buffer size
_BUFF_SIZE = const(318)


class DHCP:
Expand Down Expand Up @@ -166,95 +166,95 @@ def send_dhcp_message(
:param float time_elapsed: Number of seconds elapsed since DHCP process started
:param bool renew: Set True for renew and rebind, defaults to False
"""
_BUFF[:] = b"\x00" * len(_BUFF)
buff = bytearray(_BUFF_SIZE)
# OP
_BUFF[0] = _DHCP_BOOT_REQUEST
buff[0] = _DHCP_BOOT_REQUEST
# HTYPE
_BUFF[1] = _DHCP_HTYPE10MB
buff[1] = _DHCP_HTYPE10MB
# HLEN
_BUFF[2] = _DHCP_HLENETHERNET
buff[2] = _DHCP_HLENETHERNET
# HOPS
_BUFF[3] = _DHCP_HOPS
buff[3] = _DHCP_HOPS

# Transaction ID (xid)
self._initial_xid = htonl(self._transaction_id)
self._initial_xid = self._initial_xid.to_bytes(4, "big")
_BUFF[4:8] = self._initial_xid
buff[4:8] = self._initial_xid

# seconds elapsed
_BUFF[8] = (int(time_elapsed) & 0xFF00) >> 8
_BUFF[9] = int(time_elapsed) & 0x00FF
buff[8] = (int(time_elapsed) & 0xFF00) >> 8
buff[9] = int(time_elapsed) & 0x00FF

# flags
flags = htons(0x8000)
flags = flags.to_bytes(2, "big")
_BUFF[10] = flags[1]
_BUFF[11] = flags[0]
buff[10] = flags[1]
buff[11] = flags[0]

# NOTE: Skipping ciaddr/yiaddr/siaddr/giaddr
# as they're already set to 0.0.0.0
# Except when renewing, then fill in ciaddr
if renew:
_BUFF[12:16] = bytes(self.local_ip)
buff[12:16] = bytes(self.local_ip)

# chaddr
_BUFF[28:34] = self._mac_address
buff[28:34] = self._mac_address

# NOTE: 192 octets of 0's, BOOTP legacy

# Magic Cookie
_BUFF[236:240] = _MAGIC_COOKIE
buff[236:240] = _MAGIC_COOKIE

# Option - DHCP Message Type
_BUFF[240] = 53
_BUFF[241] = 0x01
_BUFF[242] = state
buff[240] = 53
buff[241] = 0x01
buff[242] = state

# Option - Client Identifier
_BUFF[243] = 61
buff[243] = 61
# Length
_BUFF[244] = 0x07
buff[244] = 0x07
# HW Type - ETH
_BUFF[245] = 0x01
buff[245] = 0x01
# Client MAC Address
for mac, val in enumerate(self._mac_address):
_BUFF[246 + mac] = val
buff[246 + mac] = val

# Option - Host Name
_BUFF[252] = 12
buff[252] = 12
hostname_len = len(self._hostname)
after_hostname = 254 + hostname_len
_BUFF[253] = hostname_len
_BUFF[254:after_hostname] = self._hostname
buff[253] = hostname_len
buff[254:after_hostname] = self._hostname

if state == _DHCP_REQUEST and not renew:
# Set the parsed local IP addr
_BUFF[after_hostname] = 50
_BUFF[after_hostname + 1] = 0x04
_BUFF[after_hostname + 2 : after_hostname + 6] = bytes(self.local_ip)
buff[after_hostname] = 50
buff[after_hostname + 1] = 0x04
buff[after_hostname + 2 : after_hostname + 6] = bytes(self.local_ip)
# Set the parsed dhcp server ip addr
_BUFF[after_hostname + 6] = 54
_BUFF[after_hostname + 7] = 0x04
_BUFF[after_hostname + 8 : after_hostname + 12] = bytes(self.dhcp_server_ip)
buff[after_hostname + 6] = 54
buff[after_hostname + 7] = 0x04
buff[after_hostname + 8 : after_hostname + 12] = bytes(self.dhcp_server_ip)

_BUFF[after_hostname + 12] = 55
_BUFF[after_hostname + 13] = 0x06
buff[after_hostname + 12] = 55
buff[after_hostname + 13] = 0x06
# subnet mask
_BUFF[after_hostname + 14] = 1
buff[after_hostname + 14] = 1
# routers on subnet
_BUFF[after_hostname + 15] = 3
buff[after_hostname + 15] = 3
# DNS
_BUFF[after_hostname + 16] = 6
buff[after_hostname + 16] = 6
# domain name
_BUFF[after_hostname + 17] = 15
buff[after_hostname + 17] = 15
# renewal (T1) value
_BUFF[after_hostname + 18] = 58
buff[after_hostname + 18] = 58
# rebinding (T2) value
_BUFF[after_hostname + 19] = 59
_BUFF[after_hostname + 20] = 255
buff[after_hostname + 19] = 59
buff[after_hostname + 20] = 255

# Send DHCP packet
self._sock.send(_BUFF)
self._sock.send(buff)

# pylint: disable=too-many-branches, too-many-statements
def parse_dhcp_response(
Expand All @@ -264,89 +264,88 @@ def parse_dhcp_response(

:return Tuple[int, bytearray]: DHCP packet type and ID.
"""
global _BUFF # pylint: disable=global-statement
# store packet in buffer
_BUFF = bytearray(self._sock.recv(len(_BUFF)))
buff = bytearray(self._sock.recv(_BUFF_SIZE))
if self._debug:
print("DHCP Response: ", _BUFF)
print("DHCP Response: ", buff)

# -- Parse Packet, FIXED -- #
# Validate OP
if _BUFF[0] != _DHCP_BOOT_REPLY:
if buff[0] != _DHCP_BOOT_REPLY:
raise RuntimeError(
"Malformed Packet - \
DHCP message OP is not expected BOOT Reply."
)

xid = _BUFF[4:8]
xid = buff[4:8]
if bytes(xid) != self._initial_xid:
raise ValueError("DHCP response ID mismatch.")

self.local_ip = tuple(_BUFF[16:20])
self.local_ip = tuple(buff[16:20])
# Check that there is a server ID.
if _BUFF[28:34] == b"\x00\x00\x00\x00\x00\x00":
if buff[28:34] == b"\x00\x00\x00\x00\x00\x00":
raise ValueError("No DHCP server ID in the response.")

if _BUFF[236:240] != _MAGIC_COOKIE:
if buff[236:240] != _MAGIC_COOKIE:
raise ValueError("No DHCP Magic Cookie in the response.")

# -- Parse Packet, VARIABLE -- #
ptr = 240
while _BUFF[ptr] != _OPT_END:
if _BUFF[ptr] == _MSG_TYPE:
while buff[ptr] != _OPT_END:
if buff[ptr] == _MSG_TYPE:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += opt_len
msg_type = _BUFF[ptr]
msg_type = buff[ptr]
ptr += 1
elif _BUFF[ptr] == _SUBNET_MASK:
elif buff[ptr] == _SUBNET_MASK:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self.subnet_mask = tuple(_BUFF[ptr : ptr + opt_len])
self.subnet_mask = tuple(buff[ptr : ptr + opt_len])
ptr += opt_len
elif _BUFF[ptr] == _DHCP_SERVER_ID:
elif buff[ptr] == _DHCP_SERVER_ID:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self.dhcp_server_ip = tuple(_BUFF[ptr : ptr + opt_len])
self.dhcp_server_ip = tuple(buff[ptr : ptr + opt_len])
ptr += opt_len
elif _BUFF[ptr] == _LEASE_TIME:
elif buff[ptr] == _LEASE_TIME:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self._lease_time = int.from_bytes(_BUFF[ptr : ptr + opt_len], "big")
self._lease_time = int.from_bytes(buff[ptr : ptr + opt_len], "big")
ptr += opt_len
elif _BUFF[ptr] == _ROUTERS_ON_SUBNET:
elif buff[ptr] == _ROUTERS_ON_SUBNET:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self.gateway_ip = tuple(_BUFF[ptr : ptr + 4])
self.gateway_ip = tuple(buff[ptr : ptr + 4])
ptr += opt_len
elif _BUFF[ptr] == _DNS_SERVERS:
elif buff[ptr] == _DNS_SERVERS:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self.dns_server_ip = tuple(_BUFF[ptr : ptr + 4])
self.dns_server_ip = tuple(buff[ptr : ptr + 4])
ptr += opt_len # still increment even though we only read 1 addr.
elif _BUFF[ptr] == _T1_VAL:
elif buff[ptr] == _T1_VAL:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self._t1 = int.from_bytes(_BUFF[ptr : ptr + opt_len], "big")
self._t1 = int.from_bytes(buff[ptr : ptr + opt_len], "big")
ptr += opt_len
elif _BUFF[ptr] == _T2_VAL:
elif buff[ptr] == _T2_VAL:
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
self._t2 = int.from_bytes(_BUFF[ptr : ptr + opt_len], "big")
self._t2 = int.from_bytes(buff[ptr : ptr + opt_len], "big")
ptr += opt_len
elif _BUFF[ptr] == 0:
elif buff[ptr] == 0:
break
else:
# We're not interested in this option
ptr += 1
opt_len = _BUFF[ptr]
opt_len = buff[ptr]
ptr += 1
# no-op
ptr += opt_len
Expand Down