Bug in send method. Interface is not being taken into account #4506
Description
Brief description
Specified interface is not being taken into account when using send method.
Scapy version
2.5.0
Python version
3.11
Operating system
Debian 12
Additional environment information
No response
How to reproduce
When trying to send a packet over a specific interface, the interface specified is being ignored in the send method in scapy/arch/linux.py. For example:
import random
from scapy.all import *
random_data = random.randbytes(1024)
packet = IP(dst='192.168.4.3') / UDP(sport=4321, dport=1234) / Raw(load=random_data)
send(packet, iface="eth1")Upon opening Wireshark, I noticed that packets were being sent over my eth0 interface rather than the specified eth1. After further inspecting the code and debugging, I found this function in scapy:
class L3PacketSocket(L2Socket):
def send(self, x):
# type: (Packet) -> int
iff = x.route()[0]
if iff is None:
iff = network_name(conf.iface)
sdto = (iff, self.type)
self.outs.bind(sdto)
sn = self.outs.getsockname()
ll = lambda x: x # type: Callable[[Packet], Packet]
type_x = type(x)
if type_x in conf.l3types:
sdto = (iff, conf.l3types.layer2num[type_x])
if sn[3] in conf.l2types:
ll = lambda x: conf.l2types.num2layer[sn[3]]() / x
if self.lvl == 3 and type_x != self.LL:
warning("Incompatible L3 types detected using %s instead of %s !",
type_x, self.LL)
self.LL = type_x
sx = raw(ll(x))
x.sent_time = time.time()
try:
return self.outs.sendto(sx, sdto)
except socket.error as msg:
if msg.errno == 22 and len(sx) < conf.min_pkt_size:
return self.outs.send(
sx + b"\x00" * (conf.min_pkt_size - len(sx))
)
elif conf.auto_fragment and msg.errno == 90:
i = 0
for p in x.fragment():
i += self.outs.sendto(raw(ll(p)), sdto)
return i
else:
raiseAs you can see in iff = x.route()[0], the interface is being determined by the route method, and the one I specified is completely ignored throughout the function.
Actual result
No response
Expected result
No response
Related resources
No response