Add SMTP DATA command for mail input

Forwarding and storing are yet to be implemented, but this commit does
implement the handling of the DATA command.

Signed-off-by: Mroik <mroik@delayed.space>

1 files changed, 55 insertions, 3 deletions

diff --git a/src/smtp.rs b/src/smtp.rs
index 00e2ae8..30cf490 100644
--- a/src/smtp.rs
+++ b/src/smtp.rs
@@ -32,6 +32,7 @@ impl SmtpServer {
                 client_host: String::new(),
                 from: None,
                 to: Vec::new(),
+                data: String::new(),
             };
             spawn(session.run(stream));
         }
@@ -45,6 +46,7 @@ struct SessionHandler {
     client_host: String,
     from: Option<String>,
     to: Vec<String>,
+    data: String,
 }
 
 impl SessionHandler {
@@ -60,11 +62,24 @@ impl SessionHandler {
         )?;
 
         loop {
+            buffer.clear();
             if r.read_line(&mut buffer)? == 0 {
                 break;
             }
             log::debug!("Received '{}' from '{}'", buffer.trim(), self.addr);
 
+            // In this state the server is not expecting commands as the input is part of the email
+            // message
+            if self.state == SessionState::AwaitingMailInput {
+                if buffer.starts_with(".\r\n") {
+                    self.process_mail().await?;
+                    continue;
+                }
+
+                self.data.push_str(&buffer);
+                continue;
+            }
+
             let command = match Command::try_from(buffer.as_str()) {
                 Err(_) => {
                     writer.write_all(Reply::InvalidCommand.to_string().as_bytes())?;
@@ -74,8 +89,6 @@ impl SessionHandler {
             };
             let res = self.apply(command).await?;
             writer.write_all(res.to_string().as_bytes())?;
-
-            buffer.clear();
         }
 
         log::info!("Connection closed by {}", self.addr);
@@ -87,6 +100,7 @@ impl SessionHandler {
             Command::HELO(hostname) => self.helo(hostname).await,
             Command::MAIL(from) => self.mail(from).await,
             Command::RCPT(to) => self.rcpt(to).await,
+            Command::DATA => self.start_data().await,
         }
     }
 
@@ -127,12 +141,43 @@ impl SessionHandler {
         self.to.push(String::from(to));
         Ok(Reply::Completed(String::from("Ok")))
     }
+
+    /// Only after having started a mail transaction
+    async fn start_data(&mut self) -> std::result::Result<Reply, anyhow::Error> {
+        if self.state != SessionState::MailTransaction {
+            return Ok(Reply::BadSequence);
+        }
+
+        // Should I return a more meaningful string with this error code?
+        if self.from.is_none() || self.to.is_empty() {
+            return Ok(Reply::InvalidCommand);
+        }
+
+        self.state = SessionState::AwaitingMailInput;
+
+        Ok(Reply::StartMailInput)
+    }
+
+    // TODO: Forward and store email
+    async fn process_mail(&mut self) -> Result<Reply> {
+        if self.from.is_none() || self.to.is_empty() || self.data.trim().is_empty() {
+            return Ok(Reply::InvalidCommand);
+        }
+
+        self.state = SessionState::Normal;
+        self.from = None;
+        self.to.clear();
+        self.data.clear();
+
+        todo!()
+    }
 }
 
 #[derive(PartialEq)]
 enum SessionState {
     WaitingHelo,
     MailTransaction,
+    AwaitingMailInput,
     Normal,
 }
 
@@ -145,6 +190,7 @@ impl Default for SessionState {
 enum Reply {
     Ready(String),
     Completed(String),
+    StartMailInput,
     InvalidCommand,
     InvalidParameter,
     BadSequence,
@@ -155,9 +201,10 @@ impl ToString for Reply {
         match self {
             Reply::Ready(hostname) => format!("220 {}", hostname),
             Reply::Completed(hostname) => format!("250 {}", hostname),
-            Reply::InvalidCommand => format!("500 Command not recognized"),
+            Reply::InvalidCommand => format!("500 Invalid command"),
             Reply::InvalidParameter => format!("501 Parameter error"),
             Reply::BadSequence => format!("503 Bad sequence of commands"),
+            Reply::StartMailInput => format!("354 <CRLF>.<CRLF>"),
         }
     }
 }
@@ -166,6 +213,7 @@ enum Command {
     HELO(String),
     MAIL(String),
     RCPT(String),
+    DATA,
 }
 
 impl TryFrom<&str> for Command {
@@ -190,6 +238,10 @@ impl TryFrom<&str> for Command {
             return Ok(Command::RCPT(String::from(to)));
         }
 
+        if value.to_lowercase().starts_with("data") {
+            return Ok(Command::DATA);
+        }
+
         Err(anyhow::format_err!("Invalid command"))
     }
 }