0e1c1cc92d
Test: atest NetworkStaticLibHostPythonTests Change-Id: I211d071232d1730c043eef29e1bf2bce27a6e2a6
70 lines
No EOL
2.5 KiB
Python
70 lines
No EOL
2.5 KiB
Python
# Copyright (C) 2024 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from ipaddress import IPv4Address
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from socket import inet_aton
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ETHER_BROADCAST_MAC_ADDRESS = "FF:FF:FF:FF:FF:FF"
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ARP_REQUEST_OP = 1
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ARP_REPLY_OP = 2
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"""
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This variable defines a template for constructing ARP packets in hexadecimal format.
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It's used to provide the common fields for ARP packet, and replaced needed fields when constructing
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"""
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ARP_TEMPLATE = (
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# Ether Header (14 bytes)
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"{dst_mac}" + # DA
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"{src_mac}" + # SA
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"0806" + # ARP
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# ARP Header (28 bytes)
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"0001" + # Hardware type (Ethernet)
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"0800" + # Protocol type (IPv4)
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"06" + # hardware address length
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"04" + # protocol address length
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"{opcode}" + # opcode
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"{sender_mac}" + # sender MAC
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"{sender_ip}" + # sender IP
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"{target_mac}" + # target MAC
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"{target_ip}" # target IP
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)
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def construct_arp_packet(src_mac, dst_mac, src_ip, dst_ip, op) -> str:
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"""Constructs an ARP packet as a hexadecimal string.
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This function creates an ARP packet by filling in the required fields
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in a predefined ARP packet template.
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Args:
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src_mac: The MAC address of the sender. (e.g. "11:22:33:44:55:66")
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dst_mac: The MAC address of the recipient. (e.g. "aa:bb:cc:dd:ee:ff")
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src_ip: The IP address of the sender. (e.g. "1.1.1.1")
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dst_ip: The IP address of the target machine. (e.g. "2.2.2.2")
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op: The op code of the ARP packet, refer to ARP_*_OP
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Returns:
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A string representing the ARP packet in hexadecimal format.
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"""
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# Replace the needed fields from packet template
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arp_pkt = ARP_TEMPLATE.format(
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dst_mac=dst_mac.replace(":",""),
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src_mac=src_mac.replace(":",""),
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opcode=str(op).rjust(4, "0"),
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sender_mac=src_mac.replace(":",""),
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sender_ip=inet_aton(src_ip).hex(),
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target_mac=("000000000000" if op == ARP_REQUEST_OP else dst_mac.replace(":", "")),
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target_ip=inet_aton(dst_ip).hex()
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)
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# always convert to upper case hex string
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return arp_pkt.upper() |