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use std::net::UdpSocket;
use std::time::{Duration, Instant};
use std::net::{IpAddr};
use pnet_packet::Packet;
use crate::interface::{self, MacAddr};
const TIMEOUT: u64 = 3000;
#[derive(Clone, Debug)]
pub struct Gateway {
pub mac_addr: MacAddr,
pub ip_addr: IpAddr,
}
pub fn get_default_gateway() -> Result<Gateway, String> {
let default_idx = match interface::get_default_interface_index() {
Some(idx) => idx,
None => return Err(String::from("Failed to get default interface")),
};
let interfaces = pnet_datalink::interfaces();
let interface = interfaces.into_iter().filter(|interface: &pnet_datalink::NetworkInterface| interface.index == default_idx).next().expect("Failed to get Interface");
let config = pnet_datalink::Config {
write_buffer_size: 4096,
read_buffer_size: 4096,
read_timeout: None,
write_timeout: None,
channel_type: pnet_datalink::ChannelType::Layer2,
bpf_fd_attempts: 1000,
linux_fanout: None,
promiscuous: false,
};
let (mut _tx, mut rx) = match pnet_datalink::channel(&interface, config) {
Ok(pnet_datalink::Channel::Ethernet(tx, rx)) => (tx, rx),
Ok(_) => panic!("Unknown channel type"),
Err(e) => panic!("Error happened {}", e),
};
match send_udp_packet() {
Ok(_) => (),
Err(e) => return Err(format!("Failed to send UDP packet {}", e)),
}
receive_packets(&mut rx)
}
fn send_udp_packet() -> Result<(), String> {
let buf = [0u8; 0];
let socket = match UdpSocket::bind("0.0.0.0:0") {
Ok(s) => s,
Err(e) => return Err(format!("Failed to create UDP socket {}", e)),
};
let dest: &str = "1.1.1.1:80";
match socket.set_ttl(1) {
Ok(_) => (),
Err(e) => return Err(format!("Failed to set TTL {}", e)),
}
match socket.send_to(&buf, dest) {
Ok(_) => (),
Err(e) => return Err(format!("Failed to send data {}", e)),
}
Ok(())
}
fn receive_packets(rx: &mut Box<dyn pnet_datalink::DataLinkReceiver>) -> Result<Gateway, String>{
let timeout = Duration::from_millis(TIMEOUT);
let start_time = Instant::now();
loop {
match rx.next() {
Ok(frame) => {
let frame = match pnet_packet::ethernet::EthernetPacket::new(frame) {
Some(f) => f,
None => return Err(String::from("Failed to read packet")),
};
match frame.get_ethertype() {
pnet_packet::ethernet::EtherTypes::Ipv4 => {
if let Some(ip_addr) = ipv4_handler(&frame) {
let gateway = Gateway {
mac_addr: MacAddr::new(frame.get_source().octets()),
ip_addr: ip_addr,
};
return Ok(gateway);
}
},
pnet_packet::ethernet::EtherTypes::Ipv6 => {
if let Some(ip_addr) = ipv6_handler(&frame) {
let gateway = Gateway {
mac_addr: MacAddr::new(frame.get_source().octets()),
ip_addr: ip_addr,
};
return Ok(gateway);
}
},
_ => {}
}
},
Err(e) => {
return Err(format!("An error occurred while reading: {}", e));
}
}
if Instant::now().duration_since(start_time) > timeout {
return Err(String::from("Recieve timeout"));
}else{
match send_udp_packet() {
Ok(_) => (),
Err(e) => return Err(format!("Failed to send UDP packet {}", e)),
}
}
}
}
fn ipv4_handler(ethernet: &pnet_packet::ethernet::EthernetPacket) -> Option<IpAddr> {
if let Some(packet) = pnet_packet::ipv4::Ipv4Packet::new(ethernet.payload()) {
match packet.get_next_level_protocol() {
pnet_packet::ip::IpNextHeaderProtocols::Icmp => {
return icmp_handler(&packet);
},
_ => {
None
}
}
}else{
None
}
}
fn ipv6_handler(ethernet: &pnet_packet::ethernet::EthernetPacket) -> Option<IpAddr> {
if let Some(packet) = pnet_packet::ipv6::Ipv6Packet::new(ethernet.payload()) {
match packet.get_next_header() {
pnet_packet::ip::IpNextHeaderProtocols::Icmpv6 => {
return icmpv6_handler(&packet);
},
_ => {
None
}
}
}else{
None
}
}
fn icmp_handler(ip_packet: &pnet_packet::ipv4::Ipv4Packet) -> Option<IpAddr> {
if let Some(packet) = pnet_packet::icmp::IcmpPacket::new(ip_packet.payload()) {
if packet.get_icmp_type() == pnet_packet::icmp::IcmpTypes::TimeExceeded {
let ipv4_addr = ip_packet.get_source();
return Some(IpAddr::V4(ipv4_addr))
}else{
None
}
}else{
None
}
}
fn icmpv6_handler(ip_packet: &pnet_packet::ipv6::Ipv6Packet) -> Option<IpAddr> {
if let Some(packet) = pnet_packet::icmpv6::Icmpv6Packet::new(ip_packet.payload()) {
if packet.get_icmpv6_type() == pnet_packet::icmpv6::Icmpv6Types::TimeExceeded {
let ipv6_addr = ip_packet.get_source();
return Some(IpAddr::V6(ipv6_addr))
}else{
None
}
}else{
None
}
}