ssh/config/
version.rs

1use std::io::{Read, Write};
2use std::time::Duration;
3use tracing::*;
4
5use crate::{
6    constant::{self, CLIENT_VERSION, SSH_MAGIC},
7    error::{SshError, SshResult},
8    model::Timeout,
9};
10
11#[derive(Debug, Clone)]
12pub(crate) struct SshVersion {
13    pub client_ver: String,
14    pub server_ver: String,
15}
16
17impl Default for SshVersion {
18    fn default() -> Self {
19        Self {
20            client_ver: CLIENT_VERSION.to_owned(),
21            server_ver: String::new(),
22        }
23    }
24}
25
26/// <https://www.rfc-editor.org/rfc/rfc4253#section-4.2>
27
28// When the connection has been established, both sides MUST send an
29// identification string.  This identification string MUST be
30
31//    SSH-protoversion-softwareversion SP comments CR LF
32
33// Since the protocol being defined in this set of documents is version
34// 2.0, the 'protoversion' MUST be "2.0".  The 'comments' string is
35// OPTIONAL.  If the 'comments' string is included, a 'space' character
36// (denoted above as SP, ASCII 32) MUST separate the 'softwareversion'
37// and 'comments' strings.  The identification MUST be terminated by a
38// single Carriage Return (CR) and a single Line Feed (LF) character
39// (ASCII 13 and 10, respectively).
40fn read_version<S>(stream: &mut S, tm: Option<Duration>) -> SshResult<Vec<u8>>
41where
42    S: Read,
43{
44    let mut ch = vec![0; 1];
45    const LF: u8 = 0xa;
46    let crlf = vec![0xd, 0xa];
47    let mut outbuf = vec![];
48    let mut timeout = Timeout::new(tm);
49    loop {
50        match stream.read(&mut ch) {
51            Ok(i) => {
52                if 0 == i {
53                    // eof got, return
54                    return Ok(outbuf);
55                }
56
57                outbuf.extend_from_slice(&ch);
58
59                if LF == ch[0] && outbuf.len() > 1 && outbuf.ends_with(&crlf) {
60                    // The server MAY send other lines of data before sending the version
61                    // string.  Each line SHOULD be terminated by a Carriage Return and Line
62                    // Feed.  Such lines MUST NOT begin with "SSH-", and SHOULD be encoded
63                    // in ISO-10646 UTF-8 [RFC3629] (language is not specified).  Clients
64                    // MUST be able to process such lines.  Such lines MAY be silently
65                    // ignored, or MAY be displayed to the client user.
66                    if outbuf.len() < 4 || &outbuf[0..4] != SSH_MAGIC {
67                        // skip other lines
68                        // and start read for another line
69                        outbuf.clear();
70                        continue;
71                    }
72                    return Ok(outbuf);
73                }
74                timeout.renew();
75            }
76            Err(e) => {
77                if let std::io::ErrorKind::WouldBlock = e.kind() {
78                    timeout.till_next_tick()?;
79                    continue;
80                } else {
81                    return Err(e.into());
82                }
83            }
84        };
85    }
86}
87
88impl SshVersion {
89    pub fn read_server_version<S>(
90        &mut self,
91        stream: &mut S,
92        timeout: Option<Duration>,
93    ) -> SshResult<()>
94    where
95        S: Read,
96    {
97        let buf = read_version(stream, timeout)?;
98        if buf.len() < 4 || &buf[0..4] != SSH_MAGIC {
99            error!("SSH version magic doesn't match");
100            error!("Probably not an ssh server");
101        }
102        let from_utf8 = String::from_utf8(buf)?;
103        let version_str = from_utf8.trim();
104        info!("server version: [{}]", version_str);
105
106        self.server_ver = version_str.to_owned();
107        Ok(())
108    }
109
110    pub fn send_our_version<S>(&self, stream: &mut S) -> SshResult<()>
111    where
112        S: Write,
113    {
114        info!("client version: [{}]", self.client_ver);
115        let ver_string = format!("{}\r\n", self.client_ver);
116        let _ = stream.write(ver_string.as_bytes())?;
117        Ok(())
118    }
119
120    pub fn validate(&self) -> SshResult<()> {
121        if self.server_ver.contains("SSH-2.0") {
122            Ok(())
123        } else {
124            error!("error in version negotiation, version mismatch.");
125            Err(SshError::VersionDismatchError {
126                our: constant::CLIENT_VERSION.to_owned(),
127                their: self.server_ver.clone(),
128            })
129        }
130    }
131}
ssh/config/version.rs

ssh/config/
version.rs
