irc: basic implementation of PLAIN SASL auth #8 (#28)

Reviewed-on: lavina/lavina#28

Cargo.lock

@@ -163,9 +163,9 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bitflags"
-version = "2.4.0"
+version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
+checksum = "327762f6e5a765692301e5bb513e0d9fef63be86bbc14528052b1cd3e6f03e07"
 dependencies = [
  "serde",
 ]
@@ -1264,14 +1264,17 @@ name = "projection-irc"
 version = "0.0.2-dev"
 dependencies = [
  "anyhow",
+ "bitflags 2.4.1",
  "futures-util",
  "lavina-core",
  "nonempty",
  "prometheus",
  "proto-irc",
+ "sasl",
  "serde",
  "tokio",
  "tracing",
+ "tracing-subscriber",
 ]
 
 [[package]]
@@ -1515,7 +1518,7 @@ version = "0.38.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f25469e9ae0f3d0047ca8b93fc56843f38e6774f0914a107ff8b41be8be8e0b7"
 dependencies = [
- "bitflags 2.4.0",
+ "bitflags 2.4.1",
  "errno",
  "libc",
  "linux-raw-sys",
@@ -1858,7 +1861,7 @@ checksum = "864b869fdf56263f4c95c45483191ea0af340f9f3e3e7b4d57a61c7c87a970db"
 dependencies = [
  "atoi",
  "base64",
- "bitflags 2.4.0",
+ "bitflags 2.4.1",
  "byteorder",
  "bytes",
  "crc",
@@ -1900,7 +1903,7 @@ checksum = "eb7ae0e6a97fb3ba33b23ac2671a5ce6e3cabe003f451abd5a56e7951d975624"
 dependencies = [
  "atoi",
  "base64",
- "bitflags 2.4.0",
+ "bitflags 2.4.1",
  "byteorder",
  "crc",
  "dotenvy",

crates/projection-irc/Cargo.toml

@@ -11,6 +11,10 @@ serde.workspace = true
 tokio.workspace = true
 prometheus.workspace = true
 futures-util.workspace = true
-
 nonempty.workspace = true
+bitflags = "2.4.1"
 proto-irc = { path = "../proto-irc" }
+sasl = { path = "../sasl" }
+
+[dev-dependencies]
+tracing-subscriber.workspace = true

crates/projection-irc/src/cap.rs

@@ -0,0 +1,9 @@
+use bitflags::bitflags;
+
+bitflags! {
+    #[derive(Debug)]
+    pub struct Capabilities: u32 {
+        const None = 0;
+        const Sasl = 1 << 0;
+    }
+}

crates/projection-irc/src/lib.rs

@@ -18,10 +18,17 @@ use lavina_core::prelude::*;
 use lavina_core::repo::Storage;
 use lavina_core::room::{RoomId, RoomInfo, RoomRegistry};
 use lavina_core::terminator::Terminator;
+use proto_irc::client::CapabilitySubcommand;
 use proto_irc::client::{client_message, ClientMessage};
+use proto_irc::server::CapSubBody;
 use proto_irc::server::{AwayStatus, ServerMessage, ServerMessageBody};
 use proto_irc::user::PrefixedNick;
 use proto_irc::{Chan, Recipient};
+use sasl::AuthBody;
+
+mod cap;
+
+use crate::cap::Capabilities;
 
 #[derive(Deserialize, Debug, Clone)]
 pub struct ServerConfig {
@@ -55,28 +62,16 @@ async fn handle_socket(
     let mut reader: BufReader<ReadHalf> = BufReader::new(reader);
     let mut writer = BufWriter::new(writer);
 
-    ServerMessage {
+    let registered_user: Result<RegisteredUser> =
-        tags: vec![],
+        handle_registration(&mut reader, &mut writer, &mut storage, &config).await;
-        sender: Some(config.server_name.clone().into()),
-        body: ServerMessageBody::Notice {
-            first_target: "*".into(),
-            rest_targets: vec![],
-            text: "Welcome to my server!".into(),
-        },
-    }
-    .write_async(&mut writer)
-    .await?;
-    writer.flush().await?;
-
-    let registered_user: Result<RegisteredUser> = handle_registration(&mut reader, &mut writer, &mut storage).await;
 
     match registered_user {
         Ok(user) => {
             log::debug!("User registered");
             handle_registered_socket(config, players, rooms, &mut reader, &mut writer, user).await?;
         }
-        Err(_) => {
+        Err(err) => {
-            log::debug!("Registration failed");
+            log::debug!("Registration failed: {err}");
         }
     }
 
@@ -88,93 +83,239 @@ async fn handle_registration<'a>(
     reader: &mut BufReader<ReadHalf<'a>>,
     writer: &mut BufWriter<WriteHalf<'a>>,
     storage: &mut Storage,
+    config: &ServerConfig,
 ) -> Result<RegisteredUser> {
     let mut buffer = vec![];
 
     let mut future_nickname: Option<Str> = None;
     let mut future_username: Option<(Str, Str)> = None;
+    let mut enabled_capabilities = Capabilities::None;
+    let mut cap_negotiation_in_progress = false; // if true, expect `CAP END` to complete registration
 
     let mut pass: Option<Str> = None;
+    let mut authentication_started = false;
+    let mut validated_user = None;
 
     let user = loop {
         let res = read_irc_message(reader, &mut buffer).await;
-        let res = match res {
+        tracing::trace!("Received message: {:?}", res);
-            Ok(len) => {
+        let len = match res {
-                if len == 0 {
+            Ok(len) => len,
-                    log::info!("Terminating socket");
-                    break Err(anyhow::Error::msg("EOF"));
-                }
-                match std::str::from_utf8(&buffer[..len - 2]) {
-                    Ok(res) => res,
-                    Err(e) => break Err(e.into()),
-                }
-            }
             Err(err) => {
                 log::warn!("Failed to read from socket: {err}");
                 break Err(err.into());
             }
         };
-        log::debug!("Incoming raw IRC message: '{res}'");
+        if len == 0 {
+            log::info!("Terminating socket");
+            break Err(anyhow::Error::msg("EOF"));
+        }
+        let res = match std::str::from_utf8(&buffer[..len - 2]) {
+            Ok(res) => res,
+            Err(e) => break Err(e.into()),
+        };
+        tracing::trace!("Incoming raw IRC message: '{res}'");
         let parsed = client_message(res);
-        match parsed {
+        let msg = match parsed {
-            Ok(msg) => {
+            Ok(msg) => msg,
-                log::debug!("Incoming IRC message: {msg:?}");
+            Err(err) => {
-                match msg {
+                tracing::warn!("Failed to parse IRC message: {err}");
-                    ClientMessage::Pass { password } => {
+                buffer.clear();
-                        pass = Some(password);
+                continue;
+            }
+        };
+        tracing::debug!("Incoming IRC message: {msg:?}");
+        match msg {
+            ClientMessage::Pass { password } => {
+                pass = Some(password);
+            }
+            ClientMessage::Capability { subcommand } => match subcommand {
+                CapabilitySubcommand::List { code: _ } => {
+                    cap_negotiation_in_progress = true;
+                    ServerMessage {
+                        tags: vec![],
+                        sender: Some(config.server_name.clone().into()),
+                        body: ServerMessageBody::Cap {
+                            target: future_nickname.clone().unwrap_or_else(|| "*".into()),
+                            subcmd: CapSubBody::Ls("sasl=PLAIN".into()),
+                        },
                     }
-                    ClientMessage::Nick { nickname } => {
+                    .write_async(writer)
-                        if let Some((username, realname)) = future_username {
+                    .await?;
-                            break Ok(RegisteredUser {
+                    writer.flush().await?;
-                                nickname,
+                }
-                                username,
+                CapabilitySubcommand::Req(caps) => {
-                                realname,
+                    cap_negotiation_in_progress = true;
-                            });
+                    let mut acked = vec![];
+                    let mut naked = vec![];
+                    for cap in caps {
+                        if &*cap.name == "sasl" {
+                            if cap.to_disable {
+                                enabled_capabilities &= !Capabilities::Sasl;
+                            } else {
+                                enabled_capabilities |= Capabilities::Sasl;
+                            }
+                            acked.push(cap);
                         } else {
-                            future_nickname = Some(nickname);
+                            naked.push(cap);
                         }
                     }
-                    ClientMessage::User { username, realname } => {
+                    let mut ack_body = String::new();
-                        if let Some(nickname) = future_nickname {
+                    for cap in acked {
-                            break Ok(RegisteredUser {
+                        if cap.to_disable {
-                                nickname,
+                            ack_body.push('-');
-                                username,
-                                realname,
-                            });
-                        } else {
-                            future_username = Some((username, realname));
                         }
+                        ack_body += &*cap.name;
                     }
-                    _ => {}
+                    ServerMessage {
+                        tags: vec![],
+                        sender: Some(config.server_name.clone().into()),
+                        body: ServerMessageBody::Cap {
+                            target: future_nickname.clone().unwrap_or_else(|| "*".into()),
+                            subcmd: CapSubBody::Ack(ack_body.into()),
+                        },
+                    }
+                    .write_async(writer)
+                    .await?;
+                    writer.flush().await?;
+                }
+                CapabilitySubcommand::End => {
+                    let Some((username, realname)) = future_username else {
+                        todo!()
+                    };
+                    let Some(nickname) = future_nickname.clone() else {
+                        todo!()
+                    };
+                    let candidate_user = RegisteredUser {
+                        nickname,
+                        username,
+                        realname,
+                    };
+                    if enabled_capabilities.contains(Capabilities::Sasl)
+                        && validated_user.as_ref() == Some(&candidate_user.nickname)
+                    {
+                        break Ok(candidate_user);
+                    } else {
+                        let Some(candidate_password) = pass else {
+                            todo!();
+                        };
+                        auth_user(storage, &*candidate_user.nickname, &*candidate_password).await?;
+                        break Ok(candidate_user);
+                    }
+                }
+            },
+            ClientMessage::Nick { nickname } => {
+                if cap_negotiation_in_progress {
+                    future_nickname = Some(nickname);
+                } else if let Some((username, realname)) = future_username.clone() {
+                    let candidate_user = RegisteredUser {
+                        nickname,
+                        username,
+                        realname,
+                    };
+                    let Some(candidate_password) = pass else {
+                        todo!();
+                    };
+                    auth_user(storage, &*candidate_user.nickname, &*candidate_password).await?;
+                    break Ok(candidate_user);
+                } else {
+                    future_nickname = Some(nickname);
                 }
             }
-            Err(err) => {
+            ClientMessage::User { username, realname } => {
-                log::warn!("Failed to parse IRC message: {err}");
+                if cap_negotiation_in_progress {
+                    future_username = Some((username, realname));
+                } else if let Some(nickname) = future_nickname.clone() {
+                    let candidate_user = RegisteredUser {
+                        nickname,
+                        username,
+                        realname,
+                    };
+                    let Some(candidate_password) = pass else {
+                        todo!();
+                    };
+                    auth_user(storage, &*candidate_user.nickname, &*candidate_password).await?;
+                    break Ok(candidate_user);
+                } else {
+                    future_username = Some((username, realname));
+                }
             }
+            ClientMessage::Authenticate(body) => {
+                if !authentication_started {
+                    tracing::debug!("Received authentication request");
+                    if &*body == "PLAIN" {
+                        tracing::debug!("Authentication request with method PLAIN");
+                        authentication_started = true;
+                        ServerMessage {
+                            tags: vec![],
+                            sender: Some(config.server_name.clone().into()),
+                            body: ServerMessageBody::Authenticate("+".into()),
+                        }
+                        .write_async(writer)
+                        .await?;
+                        writer.flush().await?;
+                    } else {
+                        // TODO respond with 904
+                        todo!();
+                    }
+                } else {
+                    let body = AuthBody::from_str(body.as_bytes())?;
+                    auth_user(storage, &body.login, &body.password).await?;
+                    let login: Str = body.login.into();
+                    validated_user = Some(login.clone());
+                    ServerMessage {
+                        tags: vec![],
+                        sender: Some(config.server_name.clone().into()),
+                        body: ServerMessageBody::N900LoggedIn {
+                            nick: login.clone(),
+                            address: login.clone(),
+                            account: login.clone(),
+                            message: format!("You are now logged in as {}", login).into(),
+                        },
+                    }
+                    .write_async(writer)
+                    .await?;
+                    ServerMessage {
+                        tags: vec![],
+                        sender: Some(config.server_name.clone().into()),
+                        body: ServerMessageBody::N903SaslSuccess {
+                            nick: login.clone(),
+                            message: "SASL authentication successful".into(),
+                        },
+                    }
+                    .write_async(writer)
+                    .await?;
+                    writer.flush().await?;
+                }
+                // TODO handle abortion of authentication
+            }
+            _ => {}
         }
         buffer.clear();
     }?;
+    // TODO properly implement session temination
+    Ok(user)
+}
 
-    let stored_user = storage.retrieve_user_by_name(&*user.nickname).await?;
+async fn auth_user(storage: &mut Storage, login: &str, plain_password: &str) -> Result<()> {
+    let stored_user = storage.retrieve_user_by_name(login).await?;
 
     let stored_user = match stored_user {
         Some(u) => u,
         None => {
-            log::info!("User '{}' not found", user.nickname);
+            log::info!("User '{}' not found", login);
             return Err(anyhow!("no user found"));
         }
     };
-    if stored_user.password.is_none() {
+    let Some(expected_password) = stored_user.password else {
-        log::info!("Password not defined for user '{}'", user.nickname);
+        log::info!("Password not defined for user '{}'", login);
         return Err(anyhow!("password is not defined"));
-    }
+    };
-    if stored_user.password.as_deref() != pass.as_deref() {
+    if expected_password != plain_password {
-        log::info!("Incorrect password supplied for user '{}'", user.nickname);
+        log::info!("Incorrect password supplied for user '{}'", login);
         return Err(anyhow!("passwords do not match"));
     }
-    // TODO properly implement session temination
+    Ok(())
-
-    Ok(user)
 }
 
 async fn handle_registered_socket<'a>(

crates/projection-irc/tests/lib.rs

@@ -39,6 +39,7 @@ impl<'a> TestScope<'a> {
     }
 
     async fn expect(&mut self, str: &str) -> Result<()> {
+        tracing::debug!("Expecting {}", str);
         let len = tokio::time::timeout(self.timeout, read_irc_message(&mut self.reader, &mut self.buffer)).await??;
         assert_eq!(std::str::from_utf8(&self.buffer[..len - 2])?, str);
         self.buffer.clear();
@@ -72,6 +73,7 @@ struct TestServer {
 }
 impl TestServer {
     async fn start() -> Result<TestServer> {
+        let _ = tracing_subscriber::fmt::try_init();
         let config = ServerConfig {
             listen_on: "127.0.0.1:0".parse().unwrap(),
             server_name: "testserver".into(),
@@ -109,7 +111,96 @@ async fn scenario_basic() -> Result<()> {
     s.send("PASS password").await?;
     s.send("NICK tester").await?;
     s.send("USER UserName 0 * :Real Name").await?;
-    s.expect(":testserver NOTICE * :Welcome to my server!").await?;
+    s.expect(":testserver 001 tester :Welcome to Kek Server").await?;
+    s.expect(":testserver 002 tester :Welcome to Kek Server").await?;
+    s.expect(":testserver 003 tester :Welcome to Kek Server").await?;
+    s.expect(":testserver 004 tester testserver kek-0.1.alpha.3 r CFILPQbcefgijklmnopqrstvz").await?;
+    s.expect(":testserver 005 tester CHANTYPES=# :are supported by this server").await?;
+    s.expect_nothing().await?;
+    s.send("QUIT :Leaving").await?;
+    s.expect(":testserver ERROR :Leaving the server").await?;
+    s.expect_eof().await?;
+
+    stream.shutdown().await?;
+
+    // wrap up
+
+    server.server.terminate().await?;
+    Ok(())
+}
+
+/*
+IRC SASL doc: https://ircv3.net/specs/extensions/sasl-3.1.html
+AUTHENTICATE doc: https://modern.ircdocs.horse/#authenticate-message
+*/
+#[tokio::test]
+async fn scenario_cap_full_negotiation() -> Result<()> {
+    let mut server = TestServer::start().await?;
+
+    // test scenario
+
+    server.storage.create_user("tester").await?;
+    server.storage.set_password("tester", "password").await?;
+
+    let mut stream = TcpStream::connect(server.server.addr).await?;
+    let mut s = TestScope::new(&mut stream);
+
+    s.send("CAP LS 302").await?;
+    s.send("NICK tester").await?;
+    s.send("USER UserName 0 * :Real Name").await?;
+    s.expect(":testserver CAP * LS :sasl=PLAIN").await?;
+    s.send("CAP REQ :sasl").await?;
+    s.expect(":testserver CAP tester ACK :sasl").await?;
+    s.send("AUTHENTICATE PLAIN").await?;
+    s.expect(":testserver AUTHENTICATE +").await?;
+    s.send("AUTHENTICATE dGVzdGVyAHRlc3RlcgBwYXNzd29yZA==").await?; // base64-encoded 'tester\x00tester\x00password'
+    s.expect(":testserver 900 tester tester tester :You are now logged in as tester").await?;
+    s.expect(":testserver 903 tester :SASL authentication successful").await?;
+
+    s.send("CAP END").await?;
+
+    s.expect(":testserver 001 tester :Welcome to Kek Server").await?;
+    s.expect(":testserver 002 tester :Welcome to Kek Server").await?;
+    s.expect(":testserver 003 tester :Welcome to Kek Server").await?;
+    s.expect(":testserver 004 tester testserver kek-0.1.alpha.3 r CFILPQbcefgijklmnopqrstvz").await?;
+    s.expect(":testserver 005 tester CHANTYPES=# :are supported by this server").await?;
+    s.expect_nothing().await?;
+    s.send("QUIT :Leaving").await?;
+    s.expect(":testserver ERROR :Leaving the server").await?;
+    s.expect_eof().await?;
+
+    stream.shutdown().await?;
+
+    // wrap up
+
+    server.server.terminate().await?;
+    Ok(())
+}
+
+#[tokio::test]
+async fn scenario_cap_short_negotiation() -> Result<()> {
+    let mut server = TestServer::start().await?;
+
+    // test scenario
+
+    server.storage.create_user("tester").await?;
+    server.storage.set_password("tester", "password").await?;
+
+    let mut stream = TcpStream::connect(server.server.addr).await?;
+    let mut s = TestScope::new(&mut stream);
+
+    s.send("NICK tester").await?;
+    s.send("CAP REQ :sasl").await?;
+    s.send("USER UserName 0 * :Real Name").await?;
+    s.expect(":testserver CAP tester ACK :sasl").await?;
+    s.send("AUTHENTICATE PLAIN").await?;
+    s.expect(":testserver AUTHENTICATE +").await?;
+    s.send("AUTHENTICATE dGVzdGVyAHRlc3RlcgBwYXNzd29yZA==").await?; // base64-encoded 'tester\x00tester\x00password'
+    s.expect(":testserver 900 tester tester tester :You are now logged in as tester").await?;
+    s.expect(":testserver 903 tester :SASL authentication successful").await?;
+
+    s.send("CAP END").await?;
+
     s.expect(":testserver 001 tester :Welcome to Kek Server").await?;
     s.expect(":testserver 002 tester :Welcome to Kek Server").await?;
     s.expect(":testserver 003 tester :Welcome to Kek Server").await?;

crates/proto-irc/src/client.rs

@@ -2,6 +2,7 @@ use super::*;
 
 use anyhow::{anyhow, Result};
 use nom::combinator::{all_consuming, opt};
+use nonempty::NonEmpty;
 
 /// Client-to-server command.
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -59,6 +60,7 @@ pub enum ClientMessage {
     Quit {
         reason: Str,
     },
+    Authenticate(Str),
 }
 
 pub fn client_message(input: &str) -> Result<ClientMessage> {
@@ -76,6 +78,7 @@ pub fn client_message(input: &str) -> Result<ClientMessage> {
         client_message_part,
         client_message_privmsg,
         client_message_quit,
+        client_message_authenticate,
     )))(input);
     match res {
         Ok((_, e)) => Ok(e),
@@ -223,16 +226,29 @@ fn client_message_quit(input: &str) -> IResult<&str, ClientMessage> {
     Ok((input, ClientMessage::Quit { reason: reason.into() }))
 }
 
+fn client_message_authenticate(input: &str) -> IResult<&str, ClientMessage> {
+    let (input, _) = tag("AUTHENTICATE ")(input)?;
+    let (input, body) = token(input)?;
+
+    Ok((input, ClientMessage::Authenticate(body.into())))
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum CapabilitySubcommand {
     /// CAP LS {code}
     List { code: [u8; 3] },
+    /// CAP REQ :...
+    Req(NonEmpty<CapReq>),
     /// CAP END
     End,
 }
 
 fn capability_subcommand(input: &str) -> IResult<&str, CapabilitySubcommand> {
-    alt((capability_subcommand_ls, capability_subcommand_end))(input)
+    alt((
+        capability_subcommand_ls,
+        capability_subcommand_end,
+        capability_subcommand_req,
+    ))(input)
 }
 
 fn capability_subcommand_ls(input: &str) -> IResult<&str, CapabilitySubcommand> {
@@ -247,14 +263,46 @@ fn capability_subcommand_ls(input: &str) -> IResult<&str, CapabilitySubcommand>
     ))
 }
 
+fn capability_subcommand_req(input: &str) -> IResult<&str, CapabilitySubcommand> {
+    let (input, _) = tag("REQ ")(input)?;
+    let (input, r) = opt(tag(":"))(input)?;
+    let (input, body) = match r {
+        Some(_) => token(input)?,
+        None => receiver(input)?,
+    };
+
+    let caps = body
+        .split(' ')
+        .map(|cap| {
+            let to_disable = cap.starts_with('-');
+            let name = if to_disable { &cap[1..] } else { &cap[..] };
+            CapReq {
+                to_disable,
+                name: name.into(),
+            }
+        })
+        .collect::<Vec<_>>();
+
+    let caps = NonEmpty::from_vec(caps).ok_or_else(|| todo!())?;
+
+    Ok((input, CapabilitySubcommand::Req(caps)))
+}
+
 fn capability_subcommand_end(input: &str) -> IResult<&str, CapabilitySubcommand> {
     let (input, _) = tag("END")(input)?;
     Ok((input, CapabilitySubcommand::End))
 }
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CapReq {
+    pub to_disable: bool,
+    pub name: Str,
+}
+
 #[cfg(test)]
 mod test {
     use assert_matches::*;
+    use nonempty::nonempty;
 
     use super::*;
     #[test]
@@ -324,6 +372,25 @@ mod test {
             message: "Pokasiki !!!".into(),
         };
 
+        let result = client_message(input);
+        assert_matches!(result, Ok(result) => assert_eq!(expected, result));
+    }
+    #[test]
+    fn test_client_cap_req() {
+        let input = "CAP REQ :multi-prefix -sasl";
+        let expected = ClientMessage::Capability {
+            subcommand: CapabilitySubcommand::Req(nonempty![
+                CapReq {
+                    to_disable: false,
+                    name: "multi-prefix".into()
+                },
+                CapReq {
+                    to_disable: true,
+                    name: "sasl".into()
+                }
+            ]),
+        };
+
         let result = client_message(input);
         assert_matches!(result, Ok(result) => assert_eq!(expected, result));
     }

crates/proto-irc/src/server.rs

@@ -66,6 +66,11 @@ pub enum ServerMessageBody {
     Error {
         reason: Str,
     },
+    Cap {
+        target: Str,
+        subcmd: CapSubBody,
+    },
+    Authenticate(Str),
     N001Welcome {
         client: Str,
         text: Str,
@@ -138,6 +143,16 @@ pub enum ServerMessageBody {
         client: Str,
         message: Str,
     },
+    N900LoggedIn {
+        nick: Str,
+        address: Str,
+        account: Str,
+        message: Str,
+    },
+    N903SaslSuccess {
+        nick: Str,
+        message: Str,
+    }
 }
 
 impl ServerMessageBody {
@@ -181,6 +196,24 @@ impl ServerMessageBody {
                 writer.write_all(b"ERROR :").await?;
                 writer.write_all(reason.as_bytes()).await?;
             }
+            ServerMessageBody::Cap { target, subcmd } => {
+                writer.write_all(b"CAP ").await?;
+                writer.write_all(target.as_bytes()).await?;
+                match subcmd {
+                    CapSubBody::Ls(caps) => {
+                        writer.write_all(b" LS :").await?;
+                        writer.write_all(caps.as_bytes()).await?;
+                    }
+                    CapSubBody::Ack(caps) => {
+                        writer.write_all(b" ACK :").await?;
+                        writer.write_all(caps.as_bytes()).await?;
+                    }
+                }
+            }
+            ServerMessageBody::Authenticate(body) => {
+                writer.write_all(b"AUTHENTICATE ").await?;
+                writer.write_all(body.as_bytes()).await?;
+            }
             ServerMessageBody::N001Welcome { client, text } => {
                 writer.write_all(b"001 ").await?;
                 writer.write_all(client.as_bytes()).await?;
@@ -320,11 +353,33 @@ impl ServerMessageBody {
                 writer.write_all(b" :").await?;
                 writer.write_all(message.as_bytes()).await?;
             }
+            ServerMessageBody::N900LoggedIn { nick, address, account, message } => {
+                writer.write_all(b"900 ").await?;
+                writer.write_all(nick.as_bytes()).await?;
+                writer.write_all(b" ").await?;
+                writer.write_all(address.as_bytes()).await?;
+                writer.write_all(b" ").await?;
+                writer.write_all(account.as_bytes()).await?;
+                writer.write_all(b" :").await?;
+                writer.write_all(message.as_bytes()).await?;
+            }
+            ServerMessageBody::N903SaslSuccess { nick, message } => {
+                writer.write_all(b"903 ").await?;
+                writer.write_all(nick.as_bytes()).await?;
+                writer.write_all(b" :").await?;
+                writer.write_all(message.as_bytes()).await?;
+            }
         }
         Ok(())
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum CapSubBody {
+    Ls(Str),
+    Ack(Str),
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum AwayStatus {
     Here,
@@ -336,6 +391,7 @@ fn server_message_body(input: &str) -> IResult<&str, ServerMessageBody> {
         server_message_body_notice,
         server_message_body_ping,
         server_message_body_pong,
+        server_message_body_cap,
     ))(input)
 }
 
@@ -361,12 +417,7 @@ fn server_message_body_ping(input: &str) -> IResult<&str, ServerMessageBody> {
     let (input, _) = tag("PING ")(input)?;
     let (input, token) = token(input)?;
 
-    Ok((
+    Ok((input, ServerMessageBody::Ping { token: token.into() }))
-        input,
-        ServerMessageBody::Ping {
-            token: token.into(),
-        },
-    ))
 }
 
 fn server_message_body_pong(input: &str) -> IResult<&str, ServerMessageBody> {
@@ -384,6 +435,21 @@ fn server_message_body_pong(input: &str) -> IResult<&str, ServerMessageBody> {
     ))
 }
 
+fn server_message_body_cap(input: &str) -> IResult<&str, ServerMessageBody> {
+    let (input, _) = tag("CAP ")(input)?;
+    let (input, from) = receiver(input)?;
+    let (input, _) = tag(" LS :")(input)?;
+    let (input, token) = token(input)?;
+
+    Ok((
+        input,
+        ServerMessageBody::Cap {
+            target: from.into(),
+            subcmd: CapSubBody::Ls(token.into()),
+        },
+    ))
+}
+
 #[cfg(test)]
 mod test {
     use assert_matches::*;
@@ -408,9 +474,7 @@ mod test {
         assert_matches!(result, Ok((_, result)) => assert_eq!(expected, result));
 
         let mut bytes = vec![];
-        sync_future(expected.write_async(&mut bytes))
+        sync_future(expected.write_async(&mut bytes)).unwrap().unwrap();
-            .unwrap()
-            .unwrap();
         assert_eq!(bytes, input.as_bytes());
     }
 
@@ -430,9 +494,27 @@ mod test {
         assert_matches!(result, Ok((_, result)) => assert_eq!(expected, result));
 
         let mut bytes = vec![];
-        sync_future(expected.write_async(&mut bytes))
+        sync_future(expected.write_async(&mut bytes)).unwrap().unwrap();
-            .unwrap()
+        assert_eq!(bytes, input.as_bytes());
-            .unwrap();
+    }
+
+    #[test]
+    fn test_server_message_cap_ls() {
+        let input = "CAP * LS :sasl\r\n";
+        let expected = ServerMessage {
+            tags: vec![],
+            sender: None,
+            body: ServerMessageBody::Cap {
+                target: "*".into(),
+                subcmd: CapSubBody::Ls("sasl".into()),
+            },
+        };
+
+        let result = server_message(input);
+        assert_matches!(result, Ok((_, result)) => assert_eq!(expected, result));
+
+        let mut bytes = vec![];
+        sync_future(expected.write_async(&mut bytes)).unwrap().unwrap();
         assert_eq!(bytes, input.as_bytes());
     }
 }