tor_socksproto/handshake/
proxy.rs

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1//! Types to implement the SOCKS handshake.
2
3use super::framework::{HandshakeImpl, ImplNextStep};
4use crate::msg::{SocksAddr, SocksAuth, SocksCmd, SocksRequest, SocksStatus, SocksVersion};
5use crate::{Error, Result};
6
7use tor_bytes::{EncodeResult, Error as BytesError};
8use tor_bytes::{Reader, Writer};
9use tor_error::internal;
10
11use derive_deftly::Deftly;
12
13use std::net::IpAddr;
14
15/// The Proxy (responder) side of an ongoing SOCKS handshake.
16///
17/// Create you have one of these with [`SocksProxyHandshake::new()`],
18/// and then use [`Handshake::step`](crate::Handshake::step) to drive it.
19///
20/// Eventually you will hopefully obtain a [`SocksRequest`],
21/// on which you should call [`.reply()`](SocksRequest::reply),
22/// and send the resulting data to the peer.
23#[derive(Clone, Debug, Deftly)]
24#[derive_deftly(Handshake)]
25pub struct SocksProxyHandshake {
26    /// Current state of the handshake. Each completed message
27    /// advances the state.
28    state: State,
29    /// SOCKS5 authentication that has been received (but not yet put
30    /// in a SocksRequest object.)
31    socks5_auth: Option<SocksAuth>,
32    /// Completed SOCKS handshake.
33    #[deftly(handshake(output))]
34    handshake: Option<SocksRequest>,
35}
36
37/// Possible state for a Socks connection.
38///
39/// Each completed message advances the state.
40#[derive(Clone, Debug, Copy, PartialEq, Eq)]
41enum State {
42    /// Starting state: no messages have been handled yet.
43    Initial,
44    /// SOCKS5: we've negotiated Username/Password authentication, and
45    /// are waiting for the client to send it.
46    Socks5Username,
47    /// SOCKS5: we've finished the authentication (if any), and
48    /// we're waiting for the actual request.
49    Socks5Wait,
50    /// Ending (successful) state: the client has sent all its messages.
51    ///
52    /// (Note that we still need to send a reply.)
53    Done,
54    /// Ending (failed) state: the handshake has failed and cannot continue.
55    Failed,
56}
57
58impl HandshakeImpl for SocksProxyHandshake {
59    fn handshake_impl(&mut self, input: &mut Reader<'_>) -> Result<ImplNextStep> {
60        match (self.state, input.peek(1)?[0]) {
61            (State::Initial, 4) => self.s4(input),
62            (State::Initial, 5) => self.s5_initial(input),
63            (State::Initial, v) => Err(Error::BadProtocol(v)),
64            (State::Socks5Username, 1) => self.s5_uname(input),
65            (State::Socks5Wait, 5) => self.s5(input),
66            (State::Done, _) => Err(Error::AlreadyFinished(internal!(
67                "called handshake() after handshaking was done"
68            ))),
69            (State::Failed, _) => Err(Error::AlreadyFinished(internal!(
70                "called handshake() after handshaking failed"
71            ))),
72            (_, _) => Err(Error::Syntax),
73        }
74    }
75}
76
77impl SocksProxyHandshake {
78    /// Construct a new SocksProxyHandshake in its initial state
79    pub fn new() -> Self {
80        SocksProxyHandshake {
81            state: State::Initial,
82            socks5_auth: None,
83            handshake: None,
84        }
85    }
86
87    /// Complete a socks4 or socks4a handshake.
88    fn s4(&mut self, r: &mut Reader<'_>) -> Result<ImplNextStep> {
89        let version = r.take_u8()?.try_into()?;
90        if version != SocksVersion::V4 {
91            return Err(internal!("called s4 on wrong type {:?}", version).into());
92        }
93
94        let cmd: SocksCmd = r.take_u8()?.into();
95        let port = r.take_u16()?;
96        let ip = r.take_u32()?;
97        let username: Vec<u8> = r.take_until(0)?.into();
98        let auth = if username.is_empty() {
99            SocksAuth::NoAuth
100        } else {
101            SocksAuth::Socks4(username)
102        };
103
104        let addr = if ip != 0 && (ip >> 8) == 0 {
105            // Socks4a; a hostname is given.
106            let hostname = r.take_until(0)?;
107            let hostname = std::str::from_utf8(hostname)
108                .map_err(|_| Error::Syntax)?
109                .to_string();
110            let hostname = hostname
111                .try_into()
112                .map_err(|_| BytesError::InvalidMessage("hostname too long".into()))?;
113            SocksAddr::Hostname(hostname)
114        } else {
115            let ip4: std::net::Ipv4Addr = ip.into();
116            SocksAddr::Ip(ip4.into())
117        };
118
119        let request = SocksRequest::new(version, cmd, addr, port, auth)?;
120
121        self.state = State::Done;
122        self.handshake = Some(request);
123
124        Ok(ImplNextStep::Finished)
125    }
126
127    /// Socks5: initial handshake to negotiate authentication method.
128    fn s5_initial(&mut self, r: &mut Reader<'_>) -> Result<ImplNextStep> {
129        use super::{NO_AUTHENTICATION, USERNAME_PASSWORD};
130        let version: SocksVersion = r.take_u8()?.try_into()?;
131        if version != SocksVersion::V5 {
132            return Err(internal!("called on wrong handshake type {:?}", version).into());
133        }
134
135        let nmethods = r.take_u8()?;
136        let methods = r.take(nmethods as usize)?;
137
138        // Prefer username/password, then none.
139        let (next, reply) = if methods.contains(&USERNAME_PASSWORD) {
140            (State::Socks5Username, [5, USERNAME_PASSWORD])
141        } else if methods.contains(&NO_AUTHENTICATION) {
142            self.socks5_auth = Some(SocksAuth::NoAuth);
143            (State::Socks5Wait, [5, NO_AUTHENTICATION])
144        } else {
145            // In theory we should reply with "NO ACCEPTABLE METHODS".
146            return Err(Error::NotImplemented("authentication methods".into()));
147        };
148
149        self.state = next;
150        Ok(ImplNextStep::Reply {
151            reply: reply.into(),
152        })
153    }
154
155    /// Socks5: second step for username/password authentication.
156    fn s5_uname(&mut self, r: &mut Reader<'_>) -> Result<ImplNextStep> {
157        let ver = r.take_u8()?;
158        if ver != 1 {
159            return Err(Error::NotImplemented(
160                format!("username/password version {}", ver).into(),
161            ));
162        }
163
164        let ulen = r.take_u8()?;
165        let username = r.take(ulen as usize)?;
166        let plen = r.take_u8()?;
167        let passwd = r.take(plen as usize)?;
168
169        self.socks5_auth = Some(SocksAuth::Username(username.into(), passwd.into()));
170        self.state = State::Socks5Wait;
171        Ok(ImplNextStep::Reply { reply: vec![1, 0] })
172    }
173
174    /// Socks5: final step, to receive client's request.
175    fn s5(&mut self, r: &mut Reader<'_>) -> Result<ImplNextStep> {
176        let version: SocksVersion = r.take_u8()?.try_into()?;
177        if version != SocksVersion::V5 {
178            return Err(
179                internal!("called s5 on non socks5 handshake with type {:?}", version).into(),
180            );
181        }
182        let cmd = r.take_u8()?.into();
183        let _ignore = r.take_u8()?;
184        let addr = r.extract()?;
185        let port = r.take_u16()?;
186
187        let auth = self
188            .socks5_auth
189            .take()
190            .ok_or_else(|| internal!("called s5 without negotiating auth"))?;
191
192        let request = SocksRequest::new(version, cmd, addr, port, auth)?;
193
194        self.state = State::Done;
195        self.handshake = Some(request);
196
197        Ok(ImplNextStep::Finished)
198    }
199
200    /// Return true if this handshake is finished.
201    pub fn finished(&self) -> bool {
202        self.state == State::Done
203    }
204
205    /// Consume this handshake's state; if it finished successfully,
206    /// return a SocksRequest.
207    pub fn into_request(self) -> Option<SocksRequest> {
208        self.handshake
209    }
210}
211
212impl Default for SocksProxyHandshake {
213    fn default() -> Self {
214        Self::new()
215    }
216}
217
218impl SocksRequest {
219    /// Format a reply to this request, indicating success or failure.
220    ///
221    /// Note that an address should be provided only when the request
222    /// was for a RESOLVE.
223    pub fn reply(&self, status: SocksStatus, addr: Option<&SocksAddr>) -> EncodeResult<Vec<u8>> {
224        match self.version() {
225            SocksVersion::V4 => self.s4(status, addr),
226            SocksVersion::V5 => self.s5(status, addr),
227        }
228    }
229
230    /// Format a SOCKS4 reply.
231    fn s4(&self, status: SocksStatus, addr: Option<&SocksAddr>) -> EncodeResult<Vec<u8>> {
232        let mut w = Vec::new();
233        w.write_u8(0);
234        w.write_u8(status.into_socks4_status());
235        match addr {
236            Some(SocksAddr::Ip(IpAddr::V4(ip))) => {
237                w.write_u16(self.port());
238                w.write(ip)?;
239            }
240            _ => {
241                w.write_u16(0);
242                w.write_u32(0);
243            }
244        }
245        Ok(w)
246    }
247
248    /// Format a SOCKS5 reply.
249    fn s5(&self, status: SocksStatus, addr: Option<&SocksAddr>) -> EncodeResult<Vec<u8>> {
250        let mut w = Vec::new();
251        w.write_u8(5);
252        w.write_u8(status.into());
253        w.write_u8(0); // reserved.
254        if let Some(a) = addr {
255            w.write(a)?;
256            w.write_u16(self.port());
257        } else {
258            // TODO: sometimes I think we want to answer with ::, not 0.0.0.0
259            w.write(&SocksAddr::Ip(std::net::Ipv4Addr::UNSPECIFIED.into()))?;
260            w.write_u16(0);
261        }
262        Ok(w)
263    }
264}
265
266#[cfg(test)]
267mod test {
268    // @@ begin test lint list maintained by maint/add_warning @@
269    #![allow(clippy::bool_assert_comparison)]
270    #![allow(clippy::clone_on_copy)]
271    #![allow(clippy::dbg_macro)]
272    #![allow(clippy::mixed_attributes_style)]
273    #![allow(clippy::print_stderr)]
274    #![allow(clippy::print_stdout)]
275    #![allow(clippy::single_char_pattern)]
276    #![allow(clippy::unwrap_used)]
277    #![allow(clippy::unchecked_duration_subtraction)]
278    #![allow(clippy::useless_vec)]
279    #![allow(clippy::needless_pass_by_value)]
280    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
281    use super::*;
282    use crate::{Handshake as _, Truncated};
283    use hex_literal::hex;
284
285    #[test]
286    fn socks4_good() {
287        let mut h = SocksProxyHandshake::default();
288        let a = h
289            .handshake_for_tests(&hex!("04 01 0050 CB007107 00")[..])
290            .unwrap()
291            .unwrap();
292        assert!(a.finished);
293        assert!(h.finished());
294        assert_eq!(a.drain, 9);
295        assert!(a.reply.is_empty()); // no reply -- waiting to see how it goes
296
297        let req = h.into_request().unwrap();
298        assert_eq!(req.port(), 80);
299        assert_eq!(req.addr().to_string(), "203.0.113.7");
300        assert_eq!(req.command(), SocksCmd::CONNECT);
301
302        assert_eq!(
303            req.reply(
304                SocksStatus::GENERAL_FAILURE,
305                Some(&SocksAddr::Ip("127.0.0.1".parse().unwrap()))
306            )
307            .unwrap(),
308            hex!("00 5B 0050 7f000001")
309        );
310    }
311
312    #[test]
313    fn socks4a_good() {
314        let mut h = SocksProxyHandshake::new();
315        let msg = hex!(
316            "04 01 01BB 00000001 73776f72646669736800
317                        7777772e6578616d706c652e636f6d00 99"
318        );
319        let a = h.handshake_for_tests(&msg[..]).unwrap().unwrap();
320        assert!(a.finished);
321        assert!(h.finished());
322        assert_eq!(a.drain, msg.len() - 1);
323        assert!(a.reply.is_empty()); // no reply -- waiting to see how it goes
324
325        let req = h.into_request().unwrap();
326        assert_eq!(req.port(), 443);
327        assert_eq!(req.addr().to_string(), "www.example.com");
328        assert_eq!(req.auth(), &SocksAuth::Socks4(b"swordfish".to_vec()));
329        assert_eq!(req.command(), SocksCmd::CONNECT);
330
331        assert_eq!(
332            req.reply(SocksStatus::SUCCEEDED, None).unwrap(),
333            hex!("00 5A 0000 00000000")
334        );
335    }
336
337    #[test]
338    fn socks5_init_noauth() {
339        let mut h = SocksProxyHandshake::new();
340        let a = h
341            .handshake_for_tests(&hex!("05 01 00")[..])
342            .unwrap()
343            .unwrap();
344        assert!(!a.finished);
345        assert_eq!(a.drain, 3);
346        assert_eq!(a.reply, &[5, 0]);
347        assert_eq!(h.state, State::Socks5Wait);
348    }
349
350    #[test]
351    fn socks5_init_username() {
352        let mut h = SocksProxyHandshake::new();
353        let a = h
354            .handshake_for_tests(&hex!("05 04 00023031")[..])
355            .unwrap()
356            .unwrap();
357        assert!(!a.finished);
358        assert_eq!(a.drain, 6);
359        assert_eq!(a.reply, &[5, 2]);
360        assert_eq!(h.state, State::Socks5Username);
361    }
362
363    #[test]
364    fn socks5_init_nothing_works() {
365        let mut h = SocksProxyHandshake::new();
366        let a = h.handshake_for_tests(&hex!("05 02 9988")[..]);
367        assert!(matches!(a, Ok(Err(Error::NotImplemented(_)))));
368    }
369
370    #[test]
371    fn socks5_username_ok() {
372        let mut h = SocksProxyHandshake::new();
373        let _a = h.handshake_for_tests(&hex!("05 02 9902")).unwrap().unwrap();
374        let a = h
375            .handshake_for_tests(&hex!("01 08 5761677374616666 09 24776f726466693568"))
376            .unwrap()
377            .unwrap();
378        assert_eq!(a.drain, 20);
379        assert_eq!(a.reply, &[1, 0]);
380        assert_eq!(h.state, State::Socks5Wait);
381        assert_eq!(
382            h.socks5_auth.unwrap(),
383            // _Horse Feathers_, 1932
384            SocksAuth::Username(b"Wagstaff".to_vec(), b"$wordfi5h".to_vec())
385        );
386    }
387
388    #[test]
389    fn socks5_request_ok_ipv4() {
390        let mut h = SocksProxyHandshake::new();
391        let _a = h.handshake_for_tests(&hex!("05 01 00")).unwrap().unwrap();
392        let a = h
393            .handshake_for_tests(&hex!("05 01 00 01 7f000007 1f90"))
394            .unwrap()
395            .unwrap();
396        assert_eq!(a.drain, 10);
397        assert!(a.finished);
398        assert!(a.reply.is_empty());
399        assert_eq!(h.state, State::Done);
400
401        let req = h.into_request().unwrap();
402        assert_eq!(req.version(), SocksVersion::V5);
403        assert_eq!(req.command(), SocksCmd::CONNECT);
404        assert_eq!(req.addr().to_string(), "127.0.0.7");
405        assert_eq!(req.port(), 8080);
406        assert_eq!(req.auth(), &SocksAuth::NoAuth);
407
408        assert_eq!(
409            req.reply(
410                SocksStatus::HOST_UNREACHABLE,
411                Some(&SocksAddr::Hostname(
412                    "foo.example.com".to_string().try_into().unwrap()
413                ))
414            )
415            .unwrap(),
416            hex!("05 04 00 03 0f 666f6f2e6578616d706c652e636f6d 1f90")
417        );
418    }
419
420    #[test]
421    fn socks5_request_ok_ipv6() {
422        let mut h = SocksProxyHandshake::new();
423        let _a = h.handshake_for_tests(&hex!("05 01 00")).unwrap().unwrap();
424        let a = h
425            .handshake_for_tests(&hex!(
426                "05 01 00 04 f000 0000 0000 0000 0000 0000 0000 ff11 1f90"
427            ))
428            .unwrap()
429            .unwrap();
430        assert_eq!(a.drain, 22);
431        assert!(a.finished);
432        assert!(a.reply.is_empty());
433        assert_eq!(h.state, State::Done);
434
435        let req = h.into_request().unwrap();
436        assert_eq!(req.version(), SocksVersion::V5);
437        assert_eq!(req.command(), SocksCmd::CONNECT);
438        assert_eq!(req.addr().to_string(), "f000::ff11");
439        assert_eq!(req.port(), 8080);
440        assert_eq!(req.auth(), &SocksAuth::NoAuth);
441
442        assert_eq!(
443            req.reply(SocksStatus::GENERAL_FAILURE, Some(req.addr()))
444                .unwrap(),
445            hex!("05 01 00 04 f000 0000 0000 0000 0000 0000 0000 ff11 1f90")
446        );
447    }
448
449    #[test]
450    fn socks5_request_ok_hostname() {
451        let mut h = SocksProxyHandshake::new();
452        let _a = h.handshake_for_tests(&hex!("05 01 00")).unwrap().unwrap();
453        let a = h
454            .handshake_for_tests(&hex!("05 01 00 03 0f 666f6f2e6578616d706c652e636f6d 1f90"))
455            .unwrap()
456            .unwrap();
457        assert_eq!(a.drain, 22);
458        assert!(a.finished);
459        assert!(a.reply.is_empty());
460        assert_eq!(h.state, State::Done);
461
462        let req = h.into_request().unwrap();
463        assert_eq!(req.version(), SocksVersion::V5);
464        assert_eq!(req.command(), SocksCmd::CONNECT);
465        assert_eq!(req.addr().to_string(), "foo.example.com");
466        assert_eq!(req.port(), 8080);
467        assert_eq!(req.auth(), &SocksAuth::NoAuth);
468
469        assert_eq!(
470            req.reply(SocksStatus::SUCCEEDED, None).unwrap(),
471            hex!("05 00 00 01 00000000 0000")
472        );
473    }
474
475    #[test]
476    fn empty_handshake() {
477        let r = SocksProxyHandshake::new().handshake_for_tests(&[]);
478        assert!(matches!(r, Err(Truncated { .. })));
479    }
480
481    #[test]
482    fn bad_version() {
483        let mut h = SocksProxyHandshake::new();
484        let r = h.handshake_for_tests(&hex!("06 01 00"));
485        assert!(matches!(r, Ok(Err(Error::BadProtocol(6)))));
486
487        let mut h = SocksProxyHandshake::new();
488        let _a = h.handshake_for_tests(&hex!("05 01 00")).unwrap();
489        let r = h.handshake_for_tests(&hex!("06 01 00"));
490        assert!(r.unwrap().is_err());
491    }
492
493    #[test]
494    fn fused_result() {
495        let good_socks4a = &hex!("04 01 0050 CB007107 00")[..];
496
497        // Can't try again after failure.
498        let mut h = SocksProxyHandshake::new();
499        let r = h.handshake_for_tests(&hex!("06 01 00"));
500        assert!(r.unwrap().is_err());
501        let r = h.handshake_for_tests(good_socks4a);
502        assert!(matches!(r, Ok(Err(Error::AlreadyFinished(_)))));
503
504        // Can't try again after success
505        let mut h = SocksProxyHandshake::new();
506        let r = h.handshake_for_tests(good_socks4a);
507        assert!(r.is_ok());
508        let r = h.handshake_for_tests(good_socks4a);
509        assert!(matches!(r, Ok(Err(Error::AlreadyFinished(_)))));
510    }
511}
tor_socksproto/handshake/proxy.rs

tor_socksproto/handshake/
proxy.rs
