libftp/
proxy.rs

1use std::{
2    io::{BufReader, BufWriter, Read},
3    net::{SocketAddr, TcpStream},
4    thread::spawn,
5};
6
7use crate::serializer::Serializer;
8use nom::{IResult, Needed};
9
10use crate::{
11    parser::{parse_command, parse_reply},
12    serializer::CommandSerializer,
13    serializer::ReplySerializer,
14};
15
16const BUFFER_SIZE: usize = 1024 * 16;
17
18pub fn proxy_connection(downstream: TcpStream, target: &SocketAddr) -> std::io::Result<()> {
19    let upstream = TcpStream::connect(target)?;
20
21    let (downstream_reader, downstream_writer) = tcp_stream_pair(downstream)?;
22    let (upstream_reader, upstream_writer) = tcp_stream_pair(upstream)?;
23
24    // Pipe from downstream to upstream and vice versa.
25    let forward = spawn(move || {
26        pipe(
27            downstream_reader,
28            parse_command,
29            |command| command,
30            CommandSerializer::new(upstream_writer),
31        )
32    });
33    let backward = spawn(move || {
34        pipe(
35            upstream_reader,
36            parse_reply,
37            |reply| reply,
38            ReplySerializer::new(downstream_writer),
39        )
40    });
41
42    forward.join().unwrap()?;
43    backward.join().unwrap()?;
44
45    Ok(())
46}
47
48fn tcp_stream_pair(
49    stream: TcpStream,
50) -> std::io::Result<(BufReader<TcpStream>, BufWriter<TcpStream>)> {
51    let cloned = stream.try_clone()?;
52    Ok((BufReader::new(stream), BufWriter::new(cloned)))
53}
54
55fn pipe<O, R, P, H, S>(mut reader: R, parser: P, hook: H, mut serializer: S) -> std::io::Result<()>
56where
57    R: Read,
58    P: Fn(&[u8]) -> IResult<&[u8], O>,
59    H: Fn(O) -> O,
60    S: Serializer<O>,
61{
62    let mut buffer = [0u8; BUFFER_SIZE];
63    let mut buffer_index = 0;
64    loop {
65        parse_stream(&mut buffer, &mut buffer_index, &mut reader, &parser)
66            .and_then(|parsed| Ok(hook(parsed)))
67            .and_then(|parsed| serializer.serialize(&parsed))?;
68    }
69}
70
71fn parse_stream<O, R, P>(
72    buffer: &mut [u8],
73    buffer_index: &mut usize,
74    reader: &mut R,
75    parser: &P,
76) -> std::io::Result<O>
77where
78    R: Read,
79    P: Fn(&[u8]) -> IResult<&[u8], O>,
80{
81    loop {
82        let read_buffer = &buffer[..*buffer_index];
83        let parse_result = parser(read_buffer);
84        match parse_result {
85            Ok((unparsed, parsed)) => {
86                // Reset buffer.
87                let unparsed_amount = unparsed.len();
88                if unparsed_amount > 0 {
89                    // Index of the unparsed data slice inside the buffer.
90                    let unparsed_index = (unparsed.as_ptr() as usize) - (buffer.as_ptr() as usize);
91
92                    // Get a range that represents the unparsed data slice inside the buffer.
93                    let unparsed_range = unparsed_index..unparsed_index + unparsed_amount;
94
95                    // Reset buffer with unparsed data.
96                    buffer.copy_within(unparsed_range, 0);
97                    *buffer_index = unparsed_amount;
98                } else {
99                    // Reset buffer back to the beginning.
100                    *buffer_index = 0;
101                }
102
103                return Ok(parsed);
104            }
105            Err(nom::Err::Incomplete(Needed::Size(amount))) => {
106                let amount = amount.get();
107                reader.read_exact(&mut buffer[*buffer_index..(*buffer_index + amount)])?;
108                *buffer_index += amount;
109            }
110            Err(nom::Err::Incomplete(Needed::Unknown)) => {
111                let read_amount = reader.read(&mut buffer[*buffer_index..])?;
112                if read_amount == 0 {
113                    return Err(std::io::Error::from(std::io::ErrorKind::UnexpectedEof));
114                }
115
116                *buffer_index += read_amount;
117            }
118            Err(error) => {
119                dbg!(error);
120                panic!();
121            }
122        };
123    }
124}
libftp/proxy.rs

libftp/
proxy.rs
