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extern crate rand; use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, ToSocketAddrs, UdpSocket}; use std::mem; const MAGIC_COOKIE: [u8; 4] = [0x21, 0x12, 0xA4, 0x42]; #[repr(u16)] #[derive(Clone, Copy, Debug, PartialEq)] pub enum MessageClass { Request = 0b00000000000000, Indication = 0b00000000010000, SuccessResponse = 0b00000100000000, FailureResponse = 0b00000100010000 } impl MessageClass { fn from_u16(num: u16) -> Option<MessageClass> { match num { 0b00000000000000 => Some(MessageClass::Request), 0b00000000010000 => Some(MessageClass::Indication), 0b00000100000000 => Some(MessageClass::SuccessResponse), 0b00000100010000 => Some(MessageClass::FailureResponse), _ => None } } } #[repr(u16)] #[derive(Clone, Copy, Debug, PartialEq)] pub enum MessageMethod { Binding = 0b00000000000001 } #[derive(Debug)] struct Header { class: MessageClass, method: MessageMethod, transaction_id: [u8; 12] } impl Header { pub fn decode(encoded: &[u8]) -> Header { let message_type = ((encoded[0] as u16) << 8) | (encoded[1] as u16); let class = MessageClass::from_u16(message_type & 0b00000100010000).unwrap(); let mut transaction_id = [0u8; 12]; for (t, &e) in transaction_id.iter_mut().zip(&encoded[8..20]) { *t = e; } Header { class: class, method: MessageMethod::Binding, transaction_id: transaction_id } } fn encode(&self) -> Vec<u8> { let message_type: [u8; 2] = unsafe { mem::transmute(self.message_type().swap_bytes()) }; let message_length: [u8; 2] = unsafe { mem::transmute(self.message_length().swap_bytes()) }; let mut bytes = vec![]; bytes.extend(&message_type); bytes.extend(&message_length); bytes.extend(&MAGIC_COOKIE); bytes.extend(&self.transaction_id); bytes } fn message_length(&self) -> u16 { 0 } fn message_type(&self) -> u16 { (self.class as u16) | (self.method as u16) } } #[derive(Debug)] pub struct XorMappedAddress(pub SocketAddr); impl XorMappedAddress { fn decode(encoded: Vec<u8>, transaction_id: [u8; 12]) -> Result<XorMappedAddress, String> { let port = (((encoded[2] as u16) << 8) | (encoded[3] as u16)) ^ 0x2112; let encoded_ip = &encoded[4..]; let ip = match encoded[1] { 1 => { let octets: Vec<u8> = encoded_ip.iter() .zip(&MAGIC_COOKIE) .map(|(b,m)| b ^ m) .collect(); IpAddr::V4(Ipv4Addr::new(octets[0], octets[1], octets[2], octets[3])) } 2 => { let segments: Vec<u8> = encoded_ip.iter() .zip(MAGIC_COOKIE.iter().chain(&transaction_id)) .map(|(b, k)| b ^ k) .collect(); let segments: Vec<u16> = segments.chunks(2) .map(|seg| ((seg[0] as u16) << 8) | (seg[1] as u16)) .collect(); IpAddr::V6(Ipv6Addr::new( segments[0], segments[1], segments[2], segments[3], segments[4], segments[5], segments[6], segments[7])) }, e @ _ => { return Err(format!("Invalid address family: {:?}", e)) } }; let address = SocketAddr::new(ip, port); Ok(XorMappedAddress(address)) } } #[derive(Debug)] pub enum Attribute { MappedAddress, Username, MessageIntegrity, ErrorCode, UnknownAttributes, Realm, Nonce, XorMappedAddress(XorMappedAddress) } impl Attribute { fn decode_all(encoded: &[u8], transaction_id: [u8; 12]) -> Result<Vec<Attribute>, String> { let mut encoded = encoded.to_vec(); let mut attributes = vec![]; while !encoded.is_empty() { let attribute_type = ((encoded.remove(0) as u16) << 8) | (encoded.remove(0) as u16); let length = ((encoded.remove(0) as usize) << 8) | (encoded.remove(0) as usize); let value = encoded.drain(..length).collect(); let attribute = match attribute_type { 0x0001 => Attribute::decode_mapped_address(value), 0x0006 => Attribute::decode_username(value), 0x0008 => Attribute::decode_message_integrity(value), 0x0009 => Attribute::decode_error_code(value), 0x000A => Attribute::decode_unknown_attributes(value), 0x0014 => Attribute::decode_realm(value), 0x0015 => Attribute::decode_nonce(value), 0x0020 => Attribute::decode_xor_mapped_address(value, transaction_id), _ => { Err(format!("Unknown attribute type: 0x{:x}", attribute_type)) } }; match attribute { Ok(attr) => attributes.push(attr), Err(error) => println!("{}", error) } } Ok(attributes) } fn decode_mapped_address(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::MappedAddress) } fn decode_username(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::Username) } fn decode_message_integrity(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::MessageIntegrity) } fn decode_error_code(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::ErrorCode) } fn decode_unknown_attributes(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::UnknownAttributes) } fn decode_realm(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::Realm) } fn decode_nonce(_value: Vec<u8>) -> Result<Attribute, String> { Ok(Attribute::Nonce) } fn decode_xor_mapped_address(value: Vec<u8>, transaction_id: [u8; 12]) -> Result<Attribute, String> { XorMappedAddress::decode(value, transaction_id).map(|a| Attribute::XorMappedAddress(a)) } } #[derive(Debug)] pub struct Message { header: Header, pub attributes: Vec<Attribute> } impl Message { pub fn request() -> Message { let header = Header { class: MessageClass::Request, method: MessageMethod::Binding, transaction_id: rand::random::<[u8; 12]>() }; Message { header: header, attributes: vec![] } } pub fn decode(encoded: Vec<u8>) -> Message { let header = Header::decode(&encoded[..20]); let attributes = Attribute::decode_all(&encoded[20..], header.transaction_id).unwrap(); Message { header: header, attributes: attributes } } pub fn encode(&self) -> Vec<u8> { self.header.encode() } } pub enum IpVersion { V4, V6 } pub struct Client { server: SocketAddr, socket: UdpSocket } impl Client { pub fn new<T: ToSocketAddrs>(server_address: T, local_port: u16, ip_version: IpVersion) -> Client { let server_address = server_address.to_socket_addrs().unwrap().next().unwrap(); let listen_addr = match ip_version { IpVersion::V4 => IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)), IpVersion::V6 => IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0)) }; let listen_addr = SocketAddr::new(listen_addr, local_port); Client { server: server_address, socket: UdpSocket::bind(listen_addr).expect("Couldn't bind port") } } pub fn send(&self, message: Vec<u8>) -> Vec<u8> { self.socket.send_to(message.as_slice(), self.server).expect("Couldn't send request"); let mut buf = [0; 512]; let (amt, _) = self.socket.recv_from(&mut buf).unwrap(); buf[..amt].to_vec() } } #[cfg(test)] mod tests { use super::*; #[test] fn test_encode_message() { let encoded = Message::request().encode(); let expected = vec![0, 1, 0, 0, 33, 18, 164, 66, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7]; assert_eq!(encoded.len(), 20); assert_eq!(encoded[..8], expected[..8]); } #[test] fn test_decode_message() { let encoded: Vec<u8> = vec![ 1, 1, 0, 12, 33, 18, 164, 66, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 0, 32, 0, 8, 0, 1, 183, 220, 67, 210, 130, 201]; let message = Message::decode(encoded); assert_eq!(message.header.method, MessageMethod::Binding); assert_eq!(message.header.class, MessageClass::SuccessResponse); assert_eq!(message.header.transaction_id, [7u8; 12]); assert_eq!(message.attributes.len(), 1); } #[test] fn test_decode_xor_ipv4_mapped_address() { use std::net::{IpAddr, Ipv4Addr}; let encoded = vec![0, 1, 59, 25, 67, 210, 130, 201]; let transaction_id = [7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7]; let XorMappedAddress(address) = XorMappedAddress::decode(encoded, transaction_id).unwrap(); assert_eq!(address.port(), 6667); assert_eq!(address.ip(), IpAddr::V4(Ipv4Addr::new(98, 192, 38, 139))); } #[test] fn test_decode_xor_ipv6_mapped_address() { use std::net::{IpAddr, Ipv6Addr}; let encoded = vec![0, 2, 59, 25, 7, 18, 180, 71, 183, 36, 62, 39, 230, 88, 229, 248, 15, 179, 161, 129]; let transaction_id = [7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7]; let XorMappedAddress(address) = XorMappedAddress::decode(encoded, transaction_id).unwrap(); assert_eq!(address.port(), 6667); assert_eq!(address.ip(), IpAddr::V6(Ipv6Addr::new( 0x2600, 0x1005, 0xb023, 0x3920, 0xe15f, 0xe2ff, 0x8b4, 0xa686))); } }