104 lines
3.9 KiB
Python
104 lines
3.9 KiB
Python
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#!/usr/bin/env python3
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"""
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Chapter 10 Packet class for IRIG106 Chapter 10 frame parsing
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"""
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import struct
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from typing import Dict, Optional
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try:
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from scapy.layers.inet import IP, UDP
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except ImportError:
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print("Error: scapy library not found. Install with: pip install scapy")
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exit(1)
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class Chapter10Packet:
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"""Represents an IRIG106 Chapter 10 packet"""
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def __init__(self, packet, original_frame_num: Optional[int] = None):
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"""
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Initialize Chapter 10 packet from raw scapy packet
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Args:
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packet: Raw scapy packet
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original_frame_num: Original frame number in PCAP file
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"""
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self.raw_packet = packet
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self.original_frame_num: Optional[int] = original_frame_num
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# Extract basic packet info
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self.timestamp = float(packet.time)
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self.packet_size = len(packet)
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# Extract IP/UDP info if available
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if packet.haslayer(IP) and packet.haslayer(UDP):
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ip_layer = packet[IP]
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udp_layer = packet[UDP]
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self.src_ip = ip_layer.src
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self.dst_ip = ip_layer.dst
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self.src_port = udp_layer.sport
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self.dst_port = udp_layer.dport
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self.payload = bytes(udp_layer.payload)
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else:
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self.src_ip = ""
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self.dst_ip = ""
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self.src_port = 0
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self.dst_port = 0
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self.payload = bytes()
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# Parse Chapter 10 header
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self.ch10_header = self._parse_ch10_header()
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def _parse_ch10_header(self) -> Optional[Dict]:
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"""Parse Chapter 10 header from payload"""
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if len(self.payload) < 28: # Minimum payload size (4-byte prefix + 24-byte Ch10 header)
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return None
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try:
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# Look for Ch10 sync pattern in first several bytes
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ch10_offset = None
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for offset in range(min(8, len(self.payload) - 24)):
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sync_pattern = struct.unpack('<H', self.payload[offset:offset+2])[0]
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if sync_pattern == 0xEB25: # Ch10 sync pattern
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ch10_offset = offset
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break
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if ch10_offset is None:
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return None
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# Parse Chapter 10 header starting at found offset
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base = ch10_offset
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sync_pattern = struct.unpack('<H', self.payload[base:base+2])[0]
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channel_id = struct.unpack('<H', self.payload[base+2:base+4])[0]
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packet_length = struct.unpack('<I', self.payload[base+4:base+8])[0]
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data_length = struct.unpack('<I', self.payload[base+8:base+12])[0]
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header_version = self.payload[base+12]
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sequence_number = self.payload[base+13]
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packet_flags = self.payload[base+14]
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data_type = self.payload[base+15]
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rtc_low = struct.unpack('<I', self.payload[base+16:base+20])[0]
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rtc_high = struct.unpack('<H', self.payload[base+20:base+22])[0]
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checksum = struct.unpack('<H', self.payload[base+22:base+24])[0]
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# Store the offset for reference
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self.ch10_offset = ch10_offset
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return {
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'sync_pattern': f'0x{sync_pattern:04X}',
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'channel_id': channel_id,
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'packet_length': packet_length,
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'data_length': data_length,
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'header_version': header_version,
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'sequence_number': sequence_number,
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'packet_flags': f'0x{packet_flags:02X}',
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'data_type': f'0x{data_type:02X}',
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'rtc_low': rtc_low,
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'rtc_high': rtc_high,
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'checksum': f'0x{checksum:04X}',
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'rtc_timestamp': (rtc_high << 32) | rtc_low,
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'ch10_offset': ch10_offset
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}
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except (struct.error, IndexError):
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return None
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