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Enhance example/Ntw with esteblishing IP connection, checking local a…
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@przemobe
przemobe committed Feb 12, 2022
1 parent edc8279 commit 795354d
Showing 1 changed file with 56 additions and 43 deletions.
99 changes: 56 additions & 43 deletions examples/Ntw.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@

# This is version for MicroPython v1.17

# This file implements very simple IP stack for ENV28J60 ethernet.
# This file implements very simple IP stack for ENC28J60 ethernet.
# Supports:
# - ARP for IPv4 over Ethernet, simple ARP table
# - IPv4 for not fragmented packets only, single static IP address
Expand All @@ -20,19 +20,19 @@
import struct


ETH_TYPE_IP4 = const(0x0800)
ETH_TYPE_ARP = const(0x0806)
ETH_80211Q_TAG = const(0x8100)
ETH_TYPE_IP4 = const(0x0800)
ETH_TYPE_ARP = const(0x0806)
ETH_80211Q_TAG = const(0x8100)

ARP_HEADER_LEN = const(28)
ARP_OP_REQUEST = const(1)
ARP_OP_REPLY = const(2)
ARP_HEADER_LEN = const(28)
ARP_OP_REQUEST = const(1)
ARP_OP_REPLY = const(2)

IP4_TYPE_ICMP = const(1)
IP4_TYPE_TCP = const(6)
IP4_TYPE_UDP = const(17)
IP4_ADDR_BCAST = bytearray([255,255,255,255])
IP4_ADDR_ZERO = bytearray([0,0,0,0])
IP4_TYPE_ICMP = const(1)
IP4_TYPE_TCP = const(6)
IP4_TYPE_UDP = const(17)
IP4_ADDR_BCAST = bytearray([255,255,255,255])
IP4_ADDR_ZERO = bytearray([0,0,0,0])

ICMP4_ECHO_REPLY = const(0)
ICMP4_UNREACHABLE = const(3)
Expand All @@ -41,18 +41,14 @@

class Packet:
'''This class stores received packet information'''
def __init__(self, ntw, frame):
def __init__(self, ntw, frame, frame_len):
self.ntw = ntw
self.frame = memoryview(frame)
self.frame_len = frame_len


def procArp(pkt):
offset = pkt.eth_offset
hrtype, prtype, hrlen, prlen, oper = struct.unpack("!HHBBH", pkt.frame[0+offset:8+offset])
sha = pkt.frame[8+offset:14+offset]
spa = pkt.frame[14+offset:18+offset]
tha = pkt.frame[18+offset:24+offset]
tpa = pkt.frame[24+offset:28+offset]
hrtype, prtype, hrlen, prlen, oper, sha, spa, tha, tpa = struct.unpack_from("!HHBBH6s4s6s4s", pkt.frame, pkt.eth_offset)

print(f'Rx ARP oper={oper}')

Expand Down Expand Up @@ -166,19 +162,14 @@ def procIcmp4(pkt):


def procIp4(pkt):
offset = pkt.eth_offset
ip_hdr = struct.unpack("!BBHHHBBH", pkt.frame[0+offset:12+offset])
pkt.ip_src_addr = pkt.frame[12+offset:16+offset]
pkt.ip_dst_addr = pkt.frame[16+offset:20+offset]
pkt.ip_ver = (ip_hdr[0] >> 4) & 0xF
pkt.ip_hdrlen = (ip_hdr[0] & 0xF) << 2
pkt.ip_totlen = ip_hdr[2]
pkt.ip_proto = ip_hdr[6]
ip_ver_len, _, pkt.ip_totlen, _, ip_flags_fragoffset, ip_ttl, pkt.ip_proto, ip_hdr_chksum, pkt.ip_src_addr, pkt.ip_dst_addr = struct.unpack_from("!BBHHHBBH4s4s", pkt.frame, pkt.eth_offset)

pkt.ip_ver = (ip_ver_len >> 4) & 0xF
pkt.ip_hdrlen = (ip_ver_len & 0xF) << 2
pkt.ip_offset = pkt.eth_offset + pkt.ip_hdrlen
pkt.ip_maxoffset = pkt.eth_offset + pkt.ip_totlen
pkt.ntw.ip4RxCount += 1

#print('ip_hdr', ip_hdr, pkt.ip_hdrlen, pkt.ip_dst_addr[0], pkt.ip_dst_addr[1], pkt.ip_dst_addr[2], pkt.ip_dst_addr[3])
pkt.ntw.ip4RxCount += 1

if 4 != pkt.ip_ver:
print(f'ip_ver={pkt.ip_ver} not supported!')
Expand All @@ -193,8 +184,8 @@ def procIp4(pkt):
#print(f'IPv4 chksm={chksm} invalid!')
#return

flags_mf = (ip_hdr[4] >> 13) & 0x01
fragOffset = (ip_hdr[4] & 0x1FFF) << 3
flags_mf = (ip_flags_fragoffset >> 13) & 0x01
fragOffset = (ip_flags_fragoffset & 0x1FFF) << 3
if (0 != flags_mf) or (0 != fragOffset):
print(f'Fragmented IPv4 not supported: fragOffset={fragOffset}, flags_mf={flags_mf}')
return
Expand All @@ -213,23 +204,23 @@ def procIp4(pkt):


def printEthPkt(pkt):
print('DST:', ":".join("{:02x}".format(c) for c in pkt[0:6]),
'SRC:', ":".join("{:02x}".format(c) for c in pkt[6:12]),
'Type:', ":".join("{:02x}".format(c) for c in pkt[12:14]),
'len:', len(pkt),
'FCS', ":".join("{:02x}".format(c) for c in pkt[-4:]))
print('DST:', ":".join("{:02x}".format(c) for c in pkt.frame[0:6]),
'SRC:', ":".join("{:02x}".format(c) for c in pkt.frame[6:12]),
'Type:', ":".join("{:02x}".format(c) for c in pkt.frame[12:14]),
'len:', pkt.frame_len,
'FCS', ":".join("{:02x}".format(c) for c in pkt.frame[pkt.frame_len:pkt.frame_len+4]))


def procEth(pkt):
#printEthPkt(pkt.frame)
#printEthPkt(pkt)

pkt.eth_dst = pkt.frame[0:6]
pkt.eth_src = pkt.frame[6:12]
pkt.eth_type = struct.unpack("!H", pkt.frame[12:14])[0]
pkt.eth_type, = struct.unpack_from("!H", pkt.frame, 12)
pkt.eth_offset = 14

if ETH_80211Q_TAG == pkt.eth_type:
pkt.eth_type = struct.unpack("!H", pkt.frame[14:16])[0]
pkt.eth_type, = struct.unpack_from("!H", pkt.frame, 14)
pkt.eth_offset = 16

if ETH_TYPE_IP4 == pkt.eth_type:
Expand Down Expand Up @@ -262,7 +253,7 @@ def makeUdp4Hdr(srcIp, srcPort, dstIp, dstPort, data):

def procUdp4(pkt, bcast=False):
offset = pkt.ip_offset
pkt.udp_srcPort, pkt.udp_dstPort, udpLen, chksm_rx = struct.unpack('!HHHH', pkt.frame[offset:offset+8])
pkt.udp_srcPort, pkt.udp_dstPort, udpLen, chksm_rx = struct.unpack_from('!HHHH', pkt.frame, offset)
pkt.udp_dataLen = udpLen - 8
pkt.udp_data = memoryview(pkt.frame[offset+8:offset+udpLen])

Expand Down Expand Up @@ -337,7 +328,7 @@ def rxAllPkt(self):
if 0 >= rxLen:
print(f'Rx ERROR {rxLen}')
continue
procEth(Packet(self, self.rxBuff))
procEth(Packet(self, self.rxBuff, rxLen))

def txPkt(self, msg):
'''Function to tx packet to NIC'''
Expand Down Expand Up @@ -378,12 +369,34 @@ def sendArpRequest(self, ip4Addr):
n = self.txPkt(msg)
return n

def isLocalIp4(self, ip4Addr):
for i in range(4):
if (ip4Addr[i] & self.netIp4Mask[i]) != (self.myIp4Addr[i] & self.netIp4Mask[i]):
return False
return True

def connectIp4(self, ip4Addr):
if self.isLocalIp4(ip4Addr):
self.sendArpRequest(ip4Addr)
elif False == self.isConnectedIp4(self.gwIp4Addr):
self.sendArpRequest(self.gwIp4Addr)

def isConnectedIp4(self, ip4Addr):
if self.isLocalIp4(ip4Addr):
return None != self.getArpEntry(ip4Addr)
else:
return None != self.getArpEntry(self.gwIp4Addr)

def sendUdp4(self, tgt_ip, tgt_port, data, src_port=0):
msg = []

tgtMac = self.getArpEntry(tgt_ip)
if self.isLocalIp4(tgt_ip):
tgtMac = self.getArpEntry(tgt_ip)
else:
tgtMac = self.getArpEntry(self.gwIp4Addr)

if None == tgtMac:
print('IP address not in ARP table!')
print(f'sendUdp4: {tgt_ip[0]}.{tgt_ip[1]}.{tgt_ip[2]}.{tgt_ip[3]} not in ARP table!')
return -1

msg.append(tgtMac)
Expand Down

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