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
|
// -*- 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::{
client::Client,
resolver::{is_ipv4_addr, is_ipv6_addr, ResMode},
};
use anyhow::{self as ah, format_err as err, Context as _};
use letmein_conf::Config;
use letmein_proto::{Key, Message, Operation, ResourceId, UserId};
use std::{path::Path, sync::Arc};
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub enum AddrMode {
#[default]
TryBoth,
Both,
Ipv6,
Ipv4,
}
impl From<(bool, bool)> for AddrMode {
fn from(ipv4_ipv6: (bool, bool)) -> Self {
match ipv4_ipv6 {
(false, false) => AddrMode::TryBoth,
(true, true) => AddrMode::Both,
(false, true) => AddrMode::Ipv6,
(true, false) => AddrMode::Ipv4,
}
}
}
struct KnockSeq<'a> {
pub verbose: bool,
pub addr: &'a str,
pub server_port: u16,
pub user: UserId,
pub resource: ResourceId,
pub key: &'a Key,
}
impl<'a> KnockSeq<'a> {
fn check_reply(&self, msg: &Message) -> ah::Result<()> {
if msg.user() != self.user {
eprintln!(
"Warning: The server replied with a different user identifier. \
Expected {}, but received {}.",
self.user,
msg.user(),
);
}
if msg.resource() != self.resource {
eprintln!(
"Warning: The server replied with a different resource identifier. \
Expected {}, but received {}.",
self.resource,
msg.resource(),
);
}
Ok(())
}
pub async fn knock_sequence(&self, resolver_mode: ResMode) -> ah::Result<()> {
if self.verbose {
println!(
"Connecting to letmein server '{}:{}'.",
self.addr, self.server_port
);
}
let mut client = Client::new(self.addr, self.server_port, resolver_mode)
.await
.context("Client init")?;
if self.verbose {
println!("Sending 'Knock' packet.");
}
let mut knock = Message::new(Operation::Knock, self.user, self.resource);
knock.generate_auth_no_challenge(self.key);
client.send_msg(knock).await.context("Send knock")?;
if self.verbose {
println!("Receiving 'Challenge' packet.");
}
let challenge = client.recv_specific_msg(Operation::Challenge).await?;
self.check_reply(&challenge)?;
if self.verbose {
println!("Sending 'Response' packet.");
}
let mut response = Message::new(Operation::Response, self.user, self.resource);
response.generate_auth(self.key, challenge);
client.send_msg(response).await.context("Send response")?;
if self.verbose {
println!("Receiving 'ComeIn' packet.");
}
let comein = client.recv_specific_msg(Operation::ComeIn).await?;
self.check_reply(&comein)?;
if self.verbose {
println!("Knock sequence successful.");
}
Ok(())
}
}
pub async fn run_knock(
conf: Arc<Config>,
verbose: bool,
addr: &str,
addr_mode: AddrMode,
server_port: Option<u16>,
knock_port: u16,
user: Option<UserId>,
) -> ah::Result<()> {
let confpath = conf.get_path().unwrap_or(Path::new(""));
let user = user.unwrap_or_else(|| conf.default_user());
let Some(key) = conf.key(user) else {
return Err(err!("No key found in {confpath:?} for user {user}"));
};
let Some(resource) = conf.resource_id_by_port(knock_port, Some(user)) else {
return Err(err!(
"Port {knock_port} is not mapped to a resource in {confpath:?}"
));
};
let server_port = server_port.unwrap_or_else(|| conf.port());
let seq = KnockSeq {
verbose,
addr,
server_port,
user,
resource,
key,
};
match addr_mode {
AddrMode::TryBoth => {
if verbose {
println!("Trying to knock on '{addr}:{knock_port}' IPv6 and IPv4.");
}
if is_ipv4_addr(addr) {
// For a raw IPv4 address only knock IPv4.
seq.knock_sequence(ResMode::Ipv4).await?;
} else if is_ipv6_addr(addr) {
// For a raw IPv6 address only knock IPv6.
seq.knock_sequence(ResMode::Ipv6).await?;
} else {
// For host names try both.
let res6 = seq.knock_sequence(ResMode::Ipv6).await;
let res4 = seq.knock_sequence(ResMode::Ipv4).await;
if res6.is_err() && res4.is_err() {
return res6;
}
}
}
AddrMode::Both => {
if verbose {
println!("Knocking on '{addr}:{knock_port}' IPv6 and IPv4.");
}
seq.knock_sequence(ResMode::Ipv6).await?;
seq.knock_sequence(ResMode::Ipv4).await?;
}
AddrMode::Ipv6 => {
if verbose {
println!("Knocking on '{addr}:{knock_port}' IPv6.");
}
seq.knock_sequence(ResMode::Ipv6).await?;
}
AddrMode::Ipv4 => {
if verbose {
println!("Knocking on '{addr}:{knock_port}' IPv4.");
}
seq.knock_sequence(ResMode::Ipv4).await?;
}
}
Ok(())
}
// vim: ts=4 sw=4 expandtab
|
