vpncloud/src/ip.rs

use std::net::{SocketAddr, Ipv4Addr, Ipv6Addr};
use std::collections::{hash_map, HashMap};
use std::fmt;

use super::cloud::{InterfaceMessage, Error};
use super::util::{as_obj, as_bytes};


#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum IpAddress {
    V4(Ipv4Addr),
    V6(Ipv6Addr)
}

#[derive(PartialEq)]
pub enum IpHeader {
    V4{src: Ipv4Addr, dst: Ipv4Addr},
    V6{src: Ipv6Addr, dst: Ipv6Addr}
}

impl fmt::Debug for IpHeader {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        match self {
            &IpHeader::V4{src, dst} => write!(formatter, "src: {}, dst: {}", src, dst),
            &IpHeader::V6{src, dst} => write!(formatter, "src: {}, dst: {}", src, dst)
        }
    }
}

impl InterfaceMessage for IpHeader {
    type Address = IpAddress;

    fn src(&self) -> Self::Address {
        match self {
            &IpHeader::V4{src, dst: _} => IpAddress::V4(src),
            &IpHeader::V6{src, dst: _} => IpAddress::V6(src)
        }
    }

    fn dst(&self) -> Self::Address {
        match self {
            &IpHeader::V4{src: _, dst} => IpAddress::V4(dst),
            &IpHeader::V6{src: _, dst} => IpAddress::V6(dst)
        }
    }

    fn encode_to(&self, payload: &[u8], data: &mut [u8]) -> usize {
        unimplemented!()
    }

    fn parse_from(data: &[u8]) -> Result<(Self, &[u8]), Error> {
        unimplemented!()
    }
}



struct RoutingEntry {
    address: SocketAddr,
    bytes: Vec<u8>,
    prefix_len: u8
}

pub struct RoutingTable(HashMap<Vec<u8>, Vec<RoutingEntry>>);

impl RoutingTable {
    pub fn new() -> Self {
        RoutingTable(HashMap::new())
    }

    pub fn add(&mut self, bytes: Vec<u8>, prefix_len: u8, address: SocketAddr) {
        let group_len = (prefix_len as usize / 16) * 2;
        let group_bytes: Vec<u8> = bytes[..group_len].iter().map(|b| *b).collect();
        let routing_entry = RoutingEntry{address: address, bytes: bytes, prefix_len: prefix_len};
        match self.0.entry(group_bytes) {
            hash_map::Entry::Occupied(mut entry) => entry.get_mut().push(routing_entry),
            hash_map::Entry::Vacant(entry) => { entry.insert(vec![routing_entry]); () }
        }
    }

    pub fn lookup(&self, bytes: Vec<u8>) -> Option<SocketAddr> {
        let mut len = bytes.len()/2 * 2;
        for i in 0..len/2 {
            if let Some(group) = self.0.get(&bytes[0..len-2*i]) {
                for entry in group {
                    if entry.bytes.len() != bytes.len() {
                        continue;
                    }
                    let mut match_len = 0;
                    for i in 0..bytes.len() {
                        let b = bytes[i] ^ entry.bytes[i];
                        if b == 0 {
                            match_len += 8;
                        } else {
                            match_len += b.leading_zeros();
                            break;
                        }
                    }
                    if match_len as u8 >= entry.prefix_len {
                        return Some(entry.address);
                    }
                }
            }
        }
        None
    }
}