1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
use std::net::SocketAddr;
use anyhow::{Result, anyhow};
use tokio::{
io::{AsyncBufReadExt, AsyncWriteExt, BufReader},
net::{TcpSocket, TcpStream},
};
use crate::model::User;
const CLIENT_NAME: &str = "poul-list";
pub struct SmtpClientConnection {
pub stream: TcpStream,
}
impl Drop for SmtpClientConnection {
fn drop(&mut self) {
let _ = self.stream.try_write(b"QUIT");
}
}
impl SmtpClientConnection {
/// Returns the hostname of the SMTP server
async fn init(&mut self) -> Result<String> {
let mut buffer = String::new();
let (r, mut w) = self.stream.split();
let mut reader = BufReader::new(r);
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("220") {
return Err(anyhow!(
"server '{}' is not ready (not 220)",
self.stream.peer_addr()?
));
}
w.write_all(format!("HELO {}\r\n", CLIENT_NAME).as_bytes())
.await?;
buffer.clear();
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("250") {
return Err(anyhow!(
"could not start SMTP connection with '{}' (not 250 on HELO)",
self.stream.peer_addr()?
));
}
let mut ris = String::new();
match buffer.split(' ').nth(1) {
Some(x) => ris.push_str(x),
None => (),
}
Ok(ris)
}
/// Returns an error if it could not reset the buffers. In that the caller should just drop the
/// connection as the server is in an unreliable state.
async fn reset(&mut self) -> Result<Option<anyhow::Error>> {
let (r, mut w) = self.stream.split();
let mut reader = BufReader::new(r);
let mut buffer = String::new();
w.write_all(b"RSET\r\n").await?;
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("250") {
return Ok(Some(anyhow!(
"could not reset buffers with '{}'. Connection should be terminated\r\n",
self.stream.peer_addr()?
)));
}
Ok(None)
}
async fn send_email(&mut self, data: &str, recipients: &[User], sender: &str) -> Result<()> {
let (r, mut w) = self.stream.split();
let mut reader = BufReader::new(r);
let mut buffer = String::new();
w.write_all(format!("MAIL FROM:<{}>\r\n", sender).as_bytes())
.await?;
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("250") {
self.reset().await?;
return Err(anyhow!(
"could not initiate a mail transfer with '{}' (not 250)",
self.stream.peer_addr()?
));
}
for recp in recipients {
w.write_all(format!("RCPT TO:<{}>\r\n", recp.email).as_bytes())
.await?;
buffer.clear();
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("250") {
self.reset().await?;
return Err(anyhow!(
"'{}' rejected RCTP command (not 250)",
self.stream.peer_addr()?
));
}
}
w.write_all(b"DATA\r\n").await?;
buffer.clear();
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("354") {
self.reset().await?;
return Err(anyhow!(
"'{}' not ready to receive DATA (not 354)",
self.stream.peer_addr()?
));
}
w.write_all(data.as_bytes()).await?;
if !data.ends_with("\r\n") {
w.write_all(b"\r\n").await?;
}
w.write_all(b".\r\n").await?;
buffer.clear();
reader.read_line(&mut buffer).await?;
if !buffer.starts_with("250") {
self.reset().await?;
return Err(anyhow!(
"'{}' refused to queue (not 250)",
self.stream.peer_addr()?
));
}
Ok(())
}
}
pub async fn connect(server: &str) -> Result<SmtpClientConnection> {
let remote_peer: SocketAddr = server.parse()?;
let sock = if remote_peer.is_ipv4() {
TcpSocket::new_v4()?
} else {
TcpSocket::new_v6()?
};
let mut conn = SmtpClientConnection {
stream: sock.connect(remote_peer).await?,
};
conn.init().await?;
Ok(conn)
}
#[cfg(test)]
mod tests {
use tokio::{spawn, sync::mpsc::channel};
use crate::{model::User, smtp_client::connect, smtp_server::SmtpServer};
#[tokio::test]
async fn send_email() {
let (tx, mut rx) = channel(5);
let mut server = SmtpServer::new([127, 0, 0, 1], 9090, "testerino")
.await
.expect("init server");
let j = spawn(async move {
server.run(tx).await.expect("start server");
});
let mut connection = connect("127.0.0.1:9090").await.expect("connect to server");
let lines = [
"Date: 29 Jun 2026 15:18:58 -0000",
"From: Mroik <mroik@delayed.space>",
"To: testerino@example.org",
"Subject: This is a test",
"",
"Please ignore this, thanks.",
"",
"Mroik",
];
connection
.send_email(
lines.join("\r\n").as_str(),
&[User {
name: Some(String::from("testerino")),
email: String::from("testerino@example.org"),
}],
"mroik@delayed.space",
)
.await
.expect("send email");
let message = rx.recv().await.expect("retrieve from channel");
assert_eq!(message.data.trim(), lines.join("\r\n").trim());
j.abort();
}
}
|
