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
|
// -*- coding: utf-8 -*-
//
// Copyright (C) 2024 Michael Büsch <m@bues.ch>
//
// Licensed under the Apache License version 2.0
// or the MIT license, at your option.
// SPDX-License-Identifier: Apache-2.0 OR MIT
use crate::{firewall::FirewallOpen, server::ConnectionOps, ConfigRef};
use anyhow::{self as ah, format_err as err};
use letmein_conf::Resource;
use letmein_proto::{Message, Operation};
use std::sync::Arc;
use tokio::sync::Mutex;
pub struct Processor<'a, C, F> {
conn: C,
conf: &'a ConfigRef<'a>,
fw: Arc<Mutex<F>>,
user_id: Option<u32>,
resource_id: Option<u32>,
}
impl<'a, C: ConnectionOps, F: FirewallOpen> Processor<'a, C, F> {
pub fn new(conn: C, conf: &'a ConfigRef<'a>, fw: Arc<Mutex<F>>) -> Self {
Self {
conn,
conf,
fw,
user_id: None,
resource_id: None,
}
}
async fn recv_msg(&mut self, expect_operation: Operation) -> ah::Result<Message> {
if let Some(msg) = self.conn.recv_msg().await? {
if msg.operation() != expect_operation {
let _ = self.send_go_away().await;
return Err(err!(
"Invalid reply message operation. Expected {:?}, got {:?}",
expect_operation,
msg.operation()
));
}
if let Some(user_id) = self.user_id {
if msg.user() != user_id {
let _ = self.send_go_away().await;
return Err(err!("Received message user mismatch"));
}
}
if let Some(resource_id) = self.resource_id {
if msg.resource() != resource_id {
let _ = self.send_go_away().await;
return Err(err!("Received message resource mismatch"));
}
}
Ok(msg)
} else {
Err(err!("Disconnected."))
}
}
async fn send_msg(&mut self, msg: Message) -> ah::Result<()> {
self.conn.send_msg(msg).await
}
async fn send_go_away(&mut self) -> ah::Result<()> {
self.send_msg(Message::new(
Operation::GoAway,
self.user_id.unwrap_or(u32::MAX),
self.resource_id.unwrap_or(u32::MAX),
))
.await
}
pub async fn run(&mut self) -> ah::Result<()> {
let knock = self.recv_msg(Operation::Knock).await?;
let user_id = knock.user();
self.user_id = Some(user_id);
let resource_id = knock.resource();
self.resource_id = Some(resource_id);
// Get the shared key.
let Some(key) = self.conf.key(user_id) else {
let _ = self.send_go_away().await;
return Err(err!("Unknown user: {user_id:X}"));
};
// Authenticate the received message.
// This check is not replay-safe. But that's fine.
if !knock.check_auth_ok_no_challenge(key) {
let _ = self.send_go_away().await;
return Err(err!("Knock: Authentication failed"));
}
// Get the requested resource from the configuration.
let Some(resource) = self.conf.resource(resource_id) else {
let _ = self.send_go_away().await;
return Err(err!("Unknown resource: {resource_id:X}"));
};
// Generate and send a challenge.
let mut challenge = Message::new(Operation::Challenge, user_id, resource_id);
challenge.generate_challenge();
self.send_msg(challenge.clone()).await?;
// Receive the response.
let response = self.recv_msg(Operation::Response).await?;
// Authenticate the challenge-response.
if !response.check_auth_ok(key, challenge) {
let _ = self.send_go_away().await;
return Err(err!("Response: Authentication failed"));
}
// Reconfigure the firewall.
match resource {
Resource::Port(port) => {
let mut fw = self.fw.lock().await;
fw.open_port(self.conf, self.conn.addr().ip(), *port)
.await?;
}
}
// Send a come-in message.
let comein = Message::new(Operation::ComeIn, user_id, resource_id);
self.send_msg(comein).await?;
Ok(())
}
}
// vim: ts=4 sw=4 expandtab
|
