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extern crate rand; extern crate url; extern crate serde; extern crate serde_json; use errors::*; use errors::ErrorKind::*; use self::rand::{thread_rng, Rng}; use self::serde_json::de; use self::serde_json::value::Value; use self::url::Url; use std::cmp; use std::io; use std::io::{BufRead, BufReader, Write}; use std::net::TcpStream; use std::thread; use std::time::{Duration, Instant}; const CIRCUIT_BREAKER_WAIT_AFTER_BREAKING_MS: u64 = 2000; const CIRCUIT_BREAKER_WAIT_BETWEEN_ROUNDS_MS: u64 = 250; const CIRCUIT_BREAKER_ROUNDS_BEFORE_BREAKING: u32 = 4; const DEFAULT_NAME: &'static str = "#rustlang"; const DEFAULT_PORT: u16 = 4222; const URI_SCHEME: &'static str = "nats"; const RETRIES_MAX: u32 = 10; #[derive(Clone, Debug)] struct Credentials { username: String, password: String } #[derive(Clone, Debug)] struct ServerInfo { host: String, port: u16, credentials: Option<Credentials>, max_payload: usize } #[derive(Debug)] struct ClientState { stream_writer: TcpStream, buf_reader: BufReader<TcpStream>, max_payload: usize } #[derive(Debug)] pub struct Client { servers_info: Vec<ServerInfo>, server_idx: usize, verbose: bool, pedantic: bool, name: String, state: Option<ClientState>, circuit_breaker: Option<Instant>, sid: u64 } #[derive(Serialize, Debug)] struct ConnectNoCredentials { verbose: bool, pedantic: bool, name: String } #[derive(Serialize, Debug)] struct ConnectWithCredentials { verbose: bool, pedantic: bool, name: String, user: String, pass: String } #[derive(Debug)] pub struct Channel { pub sid: u64 } #[derive(Debug)] pub struct Event { pub subject: String, pub channel: Channel, pub msg: Vec<u8>, pub inbox: Option<String> } pub struct Events<'t> { client: &'t mut Client } impl Client { pub fn new<T: ToStringVec>(uris: T) -> Result<Client, NatsError> { let mut servers_info = Vec::new(); for uri in uris.to_string_vec() { let parsed = try!(parse_nats_uri(&uri)); let host = try!(parsed.host_str().ok_or((InvalidClientConfig, "Missing host name"))).to_owned(); let port = parsed.port().unwrap_or(DEFAULT_PORT); let credentials = match (parsed.username(), parsed.password()) { ("", None) => None, ("", Some(_)) => return Err(NatsError::from((InvalidClientConfig, "Username can't be empty"))), (_, None) => return Err(NatsError::from((InvalidClientConfig, "Password can't be empty"))), (username, Some(password)) => Some(Credentials { username: username.to_owned(), password: password.to_owned() }) }; servers_info.push(ServerInfo { host: host, port: port, credentials: credentials, max_payload: 0 }) } thread_rng().shuffle(&mut servers_info); Ok(Client { servers_info: servers_info, server_idx: 0, verbose: false, pedantic: false, name: DEFAULT_NAME.to_owned(), state: None, sid: 1, circuit_breaker: None }) } pub fn set_synchronous(&mut self, synchronous: bool) { self.verbose = synchronous; } pub fn set_name(&mut self, name: &str) { self.name = name.to_owned(); } pub fn subscribe(&mut self, subject: &str, queue: Option<&str>) -> Result<Channel, NatsError> { try!(subject_check(subject)); let sid = self.sid; let cmd = match queue { None => format!("SUB {} {}\r\n", subject, sid), Some(queue) => { try!(queue_check(queue)); format!("SUB {} {} {}\r\n", subject, queue, sid) } }; let verbose = self.verbose; try!(self.maybe_connect()); let res = self.with_reconnect(|mut state| -> Result<Channel, NatsError> { try!(state.stream_writer.write_all(cmd.as_bytes())); try!(wait_ok(&mut state, verbose)); Ok(Channel { sid: sid }) }); if res.is_ok() { self.sid = self.sid.wrapping_add(1); } res } pub fn unsubscribe(&mut self, channel: Channel) -> Result<(), NatsError> { let cmd = format!("UNSUB {}\r\n", channel.sid); let verbose = self.verbose; try!(self.maybe_connect()); self.with_reconnect(|mut state| -> Result<(), NatsError> { try!(state.stream_writer.write_all(cmd.as_bytes())); try!(wait_ok(&mut state, verbose)); Ok(()) }) } pub fn unsubscribe_after(&mut self, channel: Channel, max: u64) -> Result<(), NatsError> { let cmd = format!("UNSUB {} {}\r\n", channel.sid, max); let verbose = self.verbose; try!(self.maybe_connect()); self.with_reconnect(|mut state| -> Result<(), NatsError> { try!(state.stream_writer.write_all(cmd.as_bytes())); try!(wait_ok(&mut state, verbose)); Ok(()) }) } pub fn publish(&mut self, subject: &str, msg: &[u8]) -> Result<(), NatsError> { self.publish_with_optional_inbox(subject, msg, None) } pub fn make_request(&mut self, subject: &str, msg: &[u8]) -> Result<String, NatsError> { let mut rng = rand::thread_rng(); let inbox: String = rng.gen_ascii_chars().take(16).collect(); let sid = try!(self.subscribe(&inbox, None)); try!(self.unsubscribe_after(sid, 1)); try!(self.publish_with_optional_inbox(subject, msg, Some(&inbox))); Ok(inbox) } pub fn wait(&mut self) -> Result<Event, NatsError> { try!(self.maybe_connect()); self.with_reconnect(|mut state| -> Result<Event, NatsError> { let mut buf_reader = &mut state.buf_reader; loop { let mut line = String::new(); match buf_reader.read_line(&mut line) { Ok(line_len) if line_len < "PING\r\n".len() => return Err(NatsError::from((ErrorKind::ServerProtocolError, "Incomplete server response"))), Err(e) => return Err(NatsError::from(e)), Ok(_) => { } }; if line.starts_with("MSG ") { return wait_read_msg(line, buf_reader) } if line != "PING\r\n" { return Err(NatsError::from((ErrorKind::ServerProtocolError, "Server sent an unexpected response", line))); } let cmd = "PONG\r\n"; try!(state.stream_writer.write_all(cmd.as_bytes())); } }) } pub fn events(&mut self) -> Events { Events { client: self } } fn try_connect(&mut self) -> io::Result<()> { let server_info = &mut self.servers_info[self.server_idx]; let stream_reader = try!(TcpStream::connect((&server_info.host as &str, server_info.port))); let mut stream_writer = try!(stream_reader.try_clone()); let mut buf_reader = BufReader::new(stream_reader); let mut line = String::new(); match buf_reader.read_line(&mut line) { Ok(line_len) if line_len < "INFO {}".len() => return Err(io::Error::new(io::ErrorKind::InvalidInput, "Unexpected EOF")), Err(e) => return Err(e), Ok(_) => { } }; if line.starts_with("INFO ") == false { return Err(io::Error::new(io::ErrorKind::InvalidInput, "Server INFO not received")); } let obj: Value = try!(de::from_str(&line[5..]). or(Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid JSON object sent by the server")))); let obj = try!(obj.as_object(). ok_or(io::Error::new(io::ErrorKind::InvalidInput, "Invalid JSON object sent by the server"))); let max_payload = try!(try!(obj.get("max_payload"). ok_or(io::Error::new(io::ErrorKind::InvalidInput, "Server didn't send the max payload size"))). as_u64().ok_or(io::Error::new(io::ErrorKind::InvalidInput, "Received payload size is not a u64"))); if max_payload < 1 { return Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid max payload size received")); } server_info.max_payload = max_payload as usize; let auth_required = try!(try!(obj.get("auth_required"). ok_or(io::Error::new(io::ErrorKind::InvalidInput, "Server didn't send auth_required"))). as_boolean().ok_or(io::Error::new(io::ErrorKind::InvalidInput, "Received auth_required is not a boolean"))); let connect_json = match (auth_required, &server_info.credentials) { (true, &Some(ref credentials)) => { let connect = ConnectWithCredentials { verbose: self.verbose, pedantic: self.pedantic, name: self.name.clone(), user: credentials.username.clone(), pass: credentials.password.clone() }; try!(serde_json::to_string(&connect).or(Err(io::Error::new(io::ErrorKind::InvalidInput, "Received auth_required is not a boolean")))) } (false, _) | (_, &None) => { let connect = ConnectNoCredentials { verbose: self.verbose, pedantic: self.pedantic, name: self.name.clone() }; serde_json::to_string(&connect).unwrap() } }; let connect_string = format!("CONNECT {}\nPING\n", connect_json); let connect_bytes = connect_string.as_bytes(); stream_writer.write_all(connect_bytes).unwrap(); if self.verbose { let mut line = String::new(); match buf_reader.read_line(&mut line) { Ok(line_len) if line_len != "+OK\r\n".len() => return Err(io::Error::new(io::ErrorKind::InvalidInput, "Unexpected EOF")), Err(e) => return Err(e), Ok(_) => { } }; if line != "+OK\r\n" { return Err(io::Error::new(io::ErrorKind::InvalidInput, "Server +OK not received")); } } let mut line = String::new(); match buf_reader.read_line(&mut line) { Ok(line_len) if line_len != "PONG\r\n".len() => return Err(io::Error::new(io::ErrorKind::InvalidInput, "Unexpected EOF")), Err(e) => return Err(e), Ok(_) => { } }; if line != "PONG\r\n" { return Err(io::Error::new(io::ErrorKind::InvalidInput, "Server PONG not received")); } let state = ClientState { stream_writer: stream_writer, buf_reader: buf_reader, max_payload: max_payload as usize }; self.state = Some(state); Ok(()) } fn connect(&mut self) -> Result<(), NatsError> { if let Some(circuit_breaker) = self.circuit_breaker { if circuit_breaker.elapsed() < Duration::from_millis(CIRCUIT_BREAKER_WAIT_AFTER_BREAKING_MS) { return Err(NatsError::from((ErrorKind::ServerProtocolError, "Cluster down - Connections are temporarily suspended"))); } self.circuit_breaker = None; } self.state = None; let servers_count = self.servers_info.len(); for _ in 0..CIRCUIT_BREAKER_ROUNDS_BEFORE_BREAKING { for _ in 0..servers_count { if self.try_connect().is_ok() { if self.state.is_none() { panic!("Inconsistent state"); } return Ok(()); } self.server_idx = (self.server_idx + 1) % servers_count; } thread::sleep(Duration::from_millis(CIRCUIT_BREAKER_WAIT_BETWEEN_ROUNDS_MS)); } self.circuit_breaker = Some(Instant::now()); Err(NatsError::from((ErrorKind::ServerProtocolError, "The entire cluster is down or unreachable"))) } fn reconnect(&mut self) -> Result<(), NatsError> { if let Some(mut state) = self.state.take() { let _ = state.stream_writer.flush(); } self.connect() } fn maybe_connect(&mut self) -> Result<(), NatsError> { if self.state.is_none() { return self.connect() } Ok(()) } fn with_reconnect<F, T>(&mut self, f: F) -> Result<T, NatsError> where F: Fn(&mut ClientState) -> Result<T, NatsError> { let mut res: Result<T, NatsError> = Err(NatsError::from((ErrorKind::IoError, "I/O error"))); for _ in 0..RETRIES_MAX { let mut state = self.state.take().unwrap(); res = match f(&mut state) { e @ Err(_) => match self.reconnect() { Err(e) => return Err(e), Ok(_) => e }, res @ Ok(_) => { self.state = Some(state); return res; } }; } res } fn publish_with_optional_inbox(&mut self, subject: &str, msg: &[u8], inbox: Option<&str>) -> Result<(), NatsError> { try!(subject_check(subject)); let msg_len = msg.len(); let cmd = match inbox { None => format!("PUB {} {}\r\n", subject, msg_len), Some(inbox) => { try!(inbox_check(inbox)); format!("PUB {} {} {}\r\n", subject, inbox, msg_len) } }; let mut cmd: Vec<u8> = cmd.as_bytes().to_owned(); let cmd_len0 = cmd.len(); cmd.reserve(cmd_len0 + msg_len + 2); cmd.extend_from_slice(msg); cmd.push(0x0d); cmd.push(0x0a); let verbose = self.verbose; try!(self.maybe_connect()); self.with_reconnect(|mut state| -> Result<(), NatsError> { let max_payload = state.max_payload; if cmd.len() > max_payload { return Err(NatsError::from((ErrorKind::ClientProtocolError, "Message too large", format!("Maximum payload size is {} bytes", max_payload)))); } try!(state.stream_writer.write_all(&cmd)); try!(wait_ok(&mut state, verbose)); Ok(()) }) } } impl<'t> Iterator for Events<'t> { type Item = Event; fn next(&mut self) -> Option<Event> { let mut client = &mut self.client; match client.wait() { Ok(event) => Some(event), Err(_) => None } } } pub trait ToStringVec { fn to_string_vec(self) -> Vec<String>; } impl ToStringVec for String { fn to_string_vec(self) -> Vec<String> { vec!(self) } } impl<'t> ToStringVec for &'t str { fn to_string_vec(self) -> Vec<String> { vec!(self.to_owned()) } } impl ToStringVec for Vec<String> { fn to_string_vec(self) -> Vec<String> { self } } impl<'t> ToStringVec for Vec<&'t str> { fn to_string_vec(self) -> Vec<String> { self.iter().map(|&x| x.to_owned()).collect() } } fn space_check(name: &str, errmsg: &'static str) -> Result<(), NatsError> { if name.contains(' ') { return Err(NatsError::from((ErrorKind::ClientProtocolError, errmsg))); } Ok(()) } fn subject_check(subject: &str) -> Result<(), NatsError> { space_check(subject, "A subject cannot contain spaces") } fn inbox_check(inbox: &str) -> Result<(), NatsError> { space_check(inbox, "An inbox name cannot contain spaces") } fn queue_check(queue: &str) -> Result<(), NatsError> { space_check(queue, "A queue name cannot contain spaces") } fn parse_nats_uri(uri: &str) -> Result<Url, NatsError> { let url = try!(Url::parse(uri)); if url.scheme() != URI_SCHEME { Err(NatsError::from((ErrorKind::InvalidSchemeError, "Unsupported scheme"))) } else { Ok(url) } } fn read_exact<R: BufRead + ?Sized>(reader: &mut R, buf: &mut Vec<u8>) -> io::Result<usize> { let len = buf.len(); let mut to_read = len; buf.clear(); while to_read > 0 { let used = { let buffer = match reader.fill_buf() { Ok(buffer) => buffer, Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue, Err(e) => return Err(e) }; let used = cmp::min(buffer.len(), to_read); buf.extend_from_slice(&buffer[..used]); used }; reader.consume(used); to_read -= used; } Ok(len) } fn wait_ok(state: &mut ClientState, verbose: bool) -> Result<(), NatsError> { if verbose == false { return Ok(()); } let mut buf_reader = &mut state.buf_reader; let mut line = String::new(); match buf_reader.read_line(&mut line) { Ok(line_len) if line_len < "OK\r\n".len() => return Err(NatsError::from((ErrorKind::ServerProtocolError, "Incomplete server response"))), Err(e) => return Err(NatsError::from(e)), Ok(_) => { } }; match line.as_ref() { "+OK\r\n" => { }, "PING\r\n" => { let pong = "PONG\r\n".as_bytes(); try!(state.stream_writer.write_all(pong)); }, _ => return Err(NatsError::from((ErrorKind::ServerProtocolError, "Received unexpected response from the server", line))) } Ok(()) } fn wait_read_msg(line: String, buf_reader: &mut BufReader<TcpStream>) -> Result<Event, NatsError> { if line.len() < "MSG _ _ _\r\n".len() { return Err(NatsError::from((ErrorKind::ServerProtocolError, "Incomplete server response", line.clone()))); } let line = line.trim_right(); let mut parts = line[4..].split(' '); let subject = try!(parts.next(). ok_or(NatsError::from((ErrorKind::ServerProtocolError, "Unsupported server response", line.to_owned())))); let sid: u64 = try!(parts.next(). ok_or(NatsError::from((ErrorKind::ServerProtocolError, "Unsupported server response", line.to_owned())))). parse().unwrap_or(0); let inbox_or_len_s = try!(parts.next(). ok_or(NatsError::from((ErrorKind::ServerProtocolError, "Unsupported server response", line.to_owned())))); let mut inbox: Option<String> = None; let len_s = match parts.next() { None => inbox_or_len_s, Some(len_s) => { inbox = Some(inbox_or_len_s.to_owned()); len_s } }; let len: usize = try!(len_s.parse().ok(). ok_or(NatsError::from((ErrorKind::ServerProtocolError, "Suspicous message length", format!("{} (len: [{}])", line, len_s))))); let mut msg: Vec<u8> = vec![0; len]; try!(read_exact(buf_reader, &mut msg)); let mut crlf: Vec<u8> = vec![0; 2]; try!(read_exact(buf_reader, &mut crlf)); if crlf[0] != 0x0d || crlf[1] != 0x0a { return Err(NatsError::from((ErrorKind::ServerProtocolError, "Missing CRLF after a message", line.to_owned()))) } let event = Event { subject: subject.to_owned(), channel: Channel { sid: sid }, msg: msg, inbox: inbox }; Ok(event) } #[test] fn client_test() { let mut client = Client::new(vec!("nats://user:password@127.0.0.1")).unwrap(); client.set_synchronous(false); client.set_name("test"); client.subscribe("chan", None).unwrap(); client.publish("chan", "test".as_bytes()).unwrap(); client.wait().unwrap(); let s = client.subscribe("chan2", Some("queue")).unwrap(); client.unsubscribe(s).unwrap(); client.make_request("chan", "test".as_bytes()).unwrap(); client.wait().unwrap(); client.subscribe("chan.*", None).unwrap(); client.publish("chan", "test1".as_bytes()).unwrap(); client.publish("chan", "test2".as_bytes()).unwrap(); client.publish("chan", "test3".as_bytes()).unwrap(); client.publish("chan.last", "test4".as_bytes()).unwrap(); client.events().find(|event| event.subject == "chan.last").unwrap(); }