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import socket
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import struct
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def format_mac_address(mac_bytes):
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"""
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Format a MAC address from bytes to a human-readable string.
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Args:
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mac_bytes (bytes): The MAC address in bytes format.
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Returns:
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str: The MAC address in human-readable format.
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"""
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mac_str = mac_bytes.hex()
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mac_formatted = ':'.join(mac_str[i:i+2] for i in range(0, 12, 2))
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return mac_formatted
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class AgreementUtil():
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@staticmethod
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def create_udp_packet(data, dest_port, src_port):
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"""
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创建UDP数据包
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Returns:
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bytes: `UDP数据包`.
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"""
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# UDP header fields
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udp_header = struct.pack('!HHHH', src_port, dest_port, 8 + len(data), 0) # Length includes header length
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return udp_header + data.encode()
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@staticmethod
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def create_ip_packet(udp_packet, dest_ip, src_ip):
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"""
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创建IP数据包
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Returns:
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bytes: IP数据包
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"""
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# IP header fields
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version = 4
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ihl = 5 # Internet Header Length
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type_of_service = 0
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total_length = 20 + len(udp_packet) # 20 bytes IP header + UDP packet length
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identification = 54321
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flags = 0 # Don't fragment
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fragment_offset = 0
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ttl = 64 # Time to live
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protocol = 17 # UDP
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checksum = 0 # For simplicity, set to 0
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source_ip = socket.inet_aton(src_ip)
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dest_ip = socket.inet_aton(dest_ip)
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# IP数据包头部字段
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ip_header = struct.pack('!BBHHHBBH4s4s',
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(version << 4) + ihl, type_of_service, total_length,
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identification, (flags << 13) + fragment_offset,
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ttl, protocol, checksum, source_ip, dest_ip)
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return ip_header + udp_packet
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@staticmethod
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def create_ethernet_frame(ip_packet, dest_mac, src_mac):
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"""
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创建以太网帧数据包
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Returns:
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bytes: 以太网帧数据包
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"""
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# Convert MAC addresses from string format to bytes
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dest_mac_bytes = bytes.fromhex(dest_mac.replace(':', ''))
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src_mac_bytes = bytes.fromhex(src_mac.replace(':', ''))
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# Ethernet type for IP (0x0800)
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ethernet_type = 0x0800
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# Pack Ethernet frame fields
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ethernet_frame = struct.pack('!6s6sH', dest_mac_bytes, src_mac_bytes, ethernet_type)
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return ethernet_frame + ip_packet
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@staticmethod
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def parse_ethernet_frame(frame):
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"""
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解析以太网帧数据包
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Returns: 发送端MAC，接收端MAC，以太网类型，IP数据包
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"""
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dest_mac, src_mac, ethertype = struct.unpack('!6s6sH', frame[:14])
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payload = frame[14:]
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return format_mac_address(src_mac), format_mac_address(dest_mac), ethertype, payload
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@staticmethod
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def parse_ip_packet(packet):
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"""
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解析 IP 数据包
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Returns: 发送端IP，接收端IP，协议，UDP数据包
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"""
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version_ihl, type_of_service, total_length, identification, flags_fragment_offset, \
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ttl, protocol, checksum, source_ip, dest_ip = struct.unpack('!BBHHHBBH4s4s', packet[:20])
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payload = packet[20:]
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return socket.inet_ntoa(source_ip), socket.inet_ntoa(dest_ip), protocol, payload
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@staticmethod
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def parse_udp_packet(packet):
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"""
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解析UDP数据包
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Returns:
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tuple: 发送主机端口，接收主机端口，数据
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"""
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src_port, dest_port, length, checksum = struct.unpack('!HHHH', packet[:8])
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data = packet[8:]
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return src_port, dest_port, data.decode()
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