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#![doc = include_str!("../Readme.md")]
mod codec;
mod milter;
#[cfg(feature = "_fuzzing")]
pub mod fuzzing;
use asynchronous_codec::Framed;
pub use milter::{Error, Milter};
use futures::{AsyncRead, AsyncWrite, Future, SinkExt, StreamExt};
use miltr_common::{
actions::Action,
decoding::ClientCommand,
encoding::ServerMessage,
optneg::{Capability, OptNeg},
};
use miltr_utils::debug;
#[cfg(feature = "tracing")]
use tracing::instrument;
pub(crate) use self::codec::MilterCodec;
/// The entry point to host a milter server
#[derive(Debug)]
pub struct Server<'m, M: Milter> {
milter: &'m mut M,
codec: MilterCodec,
quit_on_abort: bool,
}
impl<'m, M: Milter> Server<'m, M> {
/// Create a new Server to handle connections
pub fn new(milter: &'m mut M, quit_on_abort: bool, max_buffer_size: usize) -> Self {
let codec = MilterCodec::new(max_buffer_size);
Self {
milter,
codec,
quit_on_abort,
}
}
/// Create a server with defaults working with postfix.
///
/// AFAIK, originally there where three use cases individual methods:
/// 1. Abort
///
/// The current smtp client that is connected to the milter client
/// has finished. Next mail arrives.
/// 2. Quit
///
/// The current smtp client that was connected to the milter client
/// has quit it's connection and the milter client will now quit this
/// connection.
/// 3. Quit NC
///
/// The current smtp client that was connected to the milter client
/// has quit it's connection but the milter client would like to re-use
/// this connection for someone else.
///
/// Different implementation mix them up, making e.g. postfix just always
/// opening up a new connection for every milter conversation.
///
/// [c]: https://github.com/vdukhovni/postfix/blob/17dbfb9b8b9b483a23ea84dcd272c6d4010ad74b/postfix/src/milter/milter8.c#L387-L392
#[must_use]
pub fn default_postfix(milter: &'m mut M) -> Self {
Self::new(milter, false, 2_usize.pow(16))
}
/// Handle a single milter connection.
///
/// # Arguments
/// - milter: the object implementing [`crate::Milter`]. It's methods will
/// be called at the appropriate times.
///
/// # Errors
/// This basically errors for three cases: Io Problems, Codec Problems and
/// problems returned by the milter implementation.
///
/// Have a look at [`enum@crate::Error`] for more information.
#[cfg_attr(feature = "tracing", instrument(skip_all))]
pub async fn handle_connection<RW: AsyncRead + AsyncWrite + Unpin + Send>(
&mut self,
socket: RW,
) -> Result<(), Error<M::Error>> {
let mut framed = Framed::new(socket, &mut self.codec);
let mut options: Option<OptNeg> = Option::None;
while let Some(command) = framed.next().await {
let command = command?;
debug!("Received {}", command);
match command {
// First, all the regular smtp related commands
ClientCommand::Helo(helo) => {
Self::notify_respond_answer(self.milter.helo(helo), &mut framed).await?;
}
ClientCommand::Connect(connect) => {
Self::notify_respond_answer(self.milter.connect(connect), &mut framed).await?;
}
ClientCommand::Mail(mail) => {
Self::notify_respond_answer(self.milter.mail(mail), &mut framed).await?;
}
ClientCommand::Recipient(rcpt) => {
Self::notify_respond_answer(self.milter.rcpt(rcpt), &mut framed).await?;
}
ClientCommand::Data(_v) => {
Self::notify_respond_answer(self.milter.data(), &mut framed).await?;
}
ClientCommand::Header(header) => {
Self::notify_respond_answer(self.milter.header(header), &mut framed).await?;
}
ClientCommand::EndOfHeader(_v) => {
Self::notify_respond_answer(self.milter.end_of_header(), &mut framed).await?;
}
ClientCommand::Body(body) => {
Self::notify_respond_answer(self.milter.body(body), &mut framed).await?;
}
ClientCommand::Unknown(unknown) => {
Self::notify_respond_answer(self.milter.unknown(unknown), &mut framed).await?;
}
// Regular smtp session related commands that need special responses
ClientCommand::EndOfBody(_v) => {
// Notify the milter trait implementation
let mut responses = self
.milter
.end_of_body()
.await
.map_err(Error::from_app_error)?;
// Filter those returned mod requests, keep only those
// which have been set by the current capabilities.
responses.filter_mods_by_caps(
options
.as_ref()
.map_or(Capability::all(), |o| o.capabilities),
);
// And send them back
let responses: Vec<ServerMessage> = responses.into();
for response in responses {
debug!("Sending response");
framed.send(&response).await?;
}
}
ClientCommand::Macro(macro_) => {
self.milter
.macro_(macro_)
.await
.map_err(Error::from_app_error)?;
}
// Control flow cases
// Option Negotiation
ClientCommand::OptNeg(opt_neg) => {
let response = self.milter.option_negotiation(opt_neg).await?;
options = Some(response.clone());
framed.send(&response.into()).await?;
}
// Abort the current smtp session handling
ClientCommand::Abort(_v) => {
self.milter.abort().await.map_err(Error::from_app_error)?;
if self.quit_on_abort {
self.milter.quit().await.map_err(Error::from_app_error)?;
return Ok(());
}
}
// Quit this connection
ClientCommand::Quit(_v) => {
self.milter.quit().await.map_err(Error::from_app_error)?;
return Ok(());
}
// Quit and re-use this connection
ClientCommand::QuitNc(_v) => {
self.milter.quit_nc().await.map_err(Error::from_app_error)?;
}
}
}
Ok(())
}
/// Helper function to notify the milter, handle errors and respond
async fn notify_respond_answer<RW: AsyncRead + AsyncWrite + Unpin>(
milter_fn: impl Future<Output = Result<impl Into<Action>, M::Error>>,
framed: &mut Framed<RW, &mut MilterCodec>,
) -> Result<(), milter::Error<M::Error>> {
let response = milter_fn.await.map_err(Error::from_app_error)?;
let response: Action = response.into();
framed.send(&response.into()).await?;
Ok(())
}
}