def send_packet(packet):
packet = IP(packet)
del packet.chksum
if UDP in packet:
del packet[UDP].chksum
if TCP in packet:
del packet[TCP].chksum
packet = packet.__class__(str(packet))
send(packet, verbose=False)
def fix_packet(packet):
packet = IP(packet)
del packet.chksum
if UDP in packet:
del packet[UDP].chksum
if TCP in packet:
del packet[TCP].chksum
packet = packet.__class__(str(packet))
return str(packet[IP])
print(ip_dest)
ip_header.version = 4
ip_header.ihl = ip_hdr_len // 4
ip_header.tos = 0x0
ip_header.len = (ip_hdr_len + udp_pkt_len)
ip_header.id = 0
ip_header.flags = 0
ip_header.frag = 0
ip_header.ttl = 64
ip_header.proto = 17
#ip_header.chksum= 0x7ce6
ip_header.src = ip_src
ip_header.dst = ip_dst
del ip_header.chksum
ip_header = ip_header.__class__(str(ip_header))
#ip_header.show2()
#print("-------------------------------------")
#hexdump((ip_header.version << 4) | ip_header.ihl)
#print(ip_header.version << 4)
#print(ip_header.ihl)
#print(ip_header.proto)
#hexdump(ip_header)
#ip_pkt_len = ip_hdr_len + udp_pkt_len
#ip_version = 4
#ip_ihl = ip_hdr_len // 4
#ip_tos = 0
#ip_id = 0
#ip_frag_off = 0
#incoming_time = int.from_bytes(decrypted_payload[0:8], byteorder='big')
#incoming_pkt = IP(decrypted_payload[8:])
incoming_pkt = IP(inbound_sidechannel_shaper.process_packet(sender, decrypted_payload))
incoming_pkt.src = localdb_ipmappings[sender]
#Debug
#timediff = abs(incoming_time - int(time.time() * 1000))
#sys.stderr.write("Incoming packet delayed by {} ms.\n".format(timediff))
#Assign the appropriate destination IP (this is a constant)
incoming_pkt.dst = CONST_DST_IP
#Recalculate the IPv4 checksum
del incoming_pkt.chksum
#If this carries a UDP packet recalculate the checksum from the new pseudoheader
if incoming_pkt.haslayer(UDP):
del incoming_pkt[UDP].chksum
#If this carries a TCP packet recalculate the checksum from the new pseudoheader
if incoming_pkt.haslayer(TCP):
del incoming_pkt[TCP].chksum
incoming_pkt = incoming_pkt.__class__(bytes(incoming_pkt))
#Send it over to Socat
sys.stdout.buffer.write(socat_format(incoming_pkt))
sys.stdout.buffer.flush()