148 lines
3.6 KiB
Python
148 lines
3.6 KiB
Python
import math
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from liteeth.common import *
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from liteeth.test.common import *
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from liteeth.test.model import mac
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def print_ip(s):
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print_with_prefix(s, "[IP]")
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def carry_around_add(a, b):
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c = a + b
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return (c & 0xffff) + (c >> 16)
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def checksum(msg):
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s = 0
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for i in range(0, len(msg), 2):
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w = msg[i] + (msg[i+1] << 8)
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s = carry_around_add(s, w)
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return ~s & 0xffff
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# IP model
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class IPPacket(Packet):
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def __init__(self, init=[]):
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Packet.__init__(self, init)
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def get_checksum(self):
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return self[10] | (self[11] << 8)
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def check_checksum(self):
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return checksum(self[:ipv4_header_len]) == 0
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def decode(self):
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header = []
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for byte in self[:ipv4_header_len]:
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header.append(self.pop(0))
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for k, v in sorted(ipv4_header.items()):
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setattr(self, k, get_field_data(v, header))
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def encode(self):
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header = 0
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for k, v in sorted(ipv4_header.items()):
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value = merge_bytes(split_bytes(getattr(self, k), math.ceil(v.width/8)), "little")
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header += (value << v.offset+(v.byte*8))
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for d in split_bytes(header, ipv4_header_len):
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self.insert(0, d)
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def insert_checksum(self):
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self[10] = 0
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self[11] = 0
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c = checksum(self[:ipv4_header_len])
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self[10] = c & 0xff
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self[11] = (c >> 8) & 0xff
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def __repr__(self):
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r = "--------\n"
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for k in sorted(ipv4_header.keys()):
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r += k + " : 0x{:0x}\n".format(getattr(self,k))
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r += "payload: "
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for d in self:
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r += "{:02x}".format(d)
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return r
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class IP(Module):
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def __init__(self, mac, mac_address, ip_address, debug=False, loopback=False):
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self.mac = mac
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self.mac_address = mac_address
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self.ip_address = ip_address
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self.debug = debug
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self.loopback = loopback
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self.rx_packet = IPPacket()
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self.table = {}
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self.request_pending = False
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self.udp_callback = None
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self.icmp_callback = None
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self.mac.set_ip_callback(self.callback)
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def set_udp_callback(self, callback):
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self.udp_callback = callback
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def set_icmp_callback(self, callback):
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self.icmp_callback = callback
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def send(self, packet):
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packet.encode()
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packet.insert_checksum()
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if self.debug:
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print_ip(">>>>>>>>")
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print_ip(packet)
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mac_packet = mac.MACPacket(packet)
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mac_packet.target_mac = 0x12345678abcd # XXX
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mac_packet.sender_mac = self.mac_address
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mac_packet.ethernet_type = ethernet_type_ip
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self.mac.send(mac_packet)
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def callback(self, packet):
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packet = IPPacket(packet)
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if not packet.check_checksum():
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received = packet.get_checksum()
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packet.insert_checksum()
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expected = packet.get_checksum()
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raise ValueError("Checksum error received {:04x} / expected {:04x}".format(received, expected))
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packet.decode()
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if self.debug:
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print_ip("<<<<<<<<")
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print_ip(packet)
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if self.loopback:
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self.send(packet)
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else:
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if packet.version != 0x4:
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raise ValueError
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if packet.ihl != 0x5:
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raise ValueError
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self.process(packet)
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def process(self, packet):
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if packet.protocol == udp_protocol:
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if self.udp_callback is not None:
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self.udp_callback(packet)
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elif packet.protocol == icmp_protocol:
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if self.icmp_callback is not None:
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self.icmp_callback(packet)
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if __name__ == "__main__":
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from liteeth.test.model.dumps import *
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from liteeth.test.model.mac import *
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errors = 0
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# UDP packet
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packet = MACPacket(udp)
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packet.decode_remove_header()
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#print(packet)
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packet = IPPacket(packet)
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# check decoding
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errors += not packet.check_checksum()
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packet.decode()
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#print(packet)
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errors += verify_packet(packet, {})
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# check encoding
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packet.encode()
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packet.insert_checksum()
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errors += not packet.check_checksum()
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packet.decode()
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#print(packet)
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errors += verify_packet(packet, {})
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print("ip errors " + str(errors)) |