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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 } 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(); Header { class: class, method: MessageMethod::Binding } } 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 transaction_id: [u8; 12] = [7; 12]; let mut bytes = vec![]; bytes.extend(&message_type); bytes.extend(&message_length); bytes.extend(&MAGIC_COOKIE); bytes.extend(&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(SocketAddr); impl XorMappedAddress { fn decode(encoded: Vec<u8>) -> Result<XorMappedAddress, String> { let port = ((encoded[2] as u16) << 8) + (encoded[3] as u16) ^ 0x2112; let ip = match encoded[1] { 1 => { let octets: Vec<u8> = encoded[4..8].iter().zip(&MAGIC_COOKIE).map(|(b,m)| b ^ m).collect(); IpAddr::V4(Ipv4Addr::new(octets[0], octets[1], octets[2], octets[3])) } 2 => { IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0)) }, 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]) -> 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), _ => { return Err(format!("Unknown attribute type: {}", attribute_type)) } }; attributes.push(attribute.unwrap()) } 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>) -> Result<Attribute, String> { XorMappedAddress::decode(value).map(|a| Attribute::XorMappedAddress(a)) } } #[derive(Debug)] pub struct Message { header: Header, attributes: Vec<Attribute> } impl Message { pub fn request() -> Message { let header = Header { class: MessageClass::Request, method: MessageMethod::Binding }; 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..]).unwrap(); Message { header: header, attributes: attributes } } pub fn encode(&self) -> Vec<u8> { self.header.encode() } } pub struct Client<T: ToSocketAddrs> { server: T, socket: UdpSocket } impl<T: ToSocketAddrs + Copy> Client<T> { pub fn new(server_address: T, local_port: u16) -> Client<T> { Client { server: server_address, socket: UdpSocket::bind(("0.0.0.0", local_port)).unwrap() } } pub fn send(&self, message: Vec<u8>) -> Vec<u8> { self.socket.send_to(message.as_slice(), self.server).unwrap(); 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, expected); } #[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.attributes.len(), 1); } #[test] fn test_decode_xor_mapped_address() { use std::net::{IpAddr, Ipv4Addr}; let encoded = vec![0, 1, 59, 25, 67, 210, 130, 201]; let XorMappedAddress(address) = XorMappedAddress::decode(encoded).unwrap(); assert_eq!(address.port(), 6667); assert_eq!(address.ip(), IpAddr::V4(Ipv4Addr::new(98, 192, 38, 139))); } }