vls_proxy/
connection.rs

1use std::io::{IoSlice, IoSliceMut, Read, Result as SResult, Write};
2use std::os::unix::io::{FromRawFd, IntoRawFd, RawFd};
3use std::os::unix::net::UnixStream;
4use std::{fs, io};
5
6use log::{error, info, trace};
7use nix::cmsg_space;
8use nix::sys::socket::{recvmsg, sendmsg, ControlMessage, ControlMessageOwned, MsgFlags};
9
10use nix::libc;
11use nix::unistd::close;
12
13const PARENT_FD: u16 = 3;
14
15pub struct UnixConnection {
16    fd: RawFd,
17    stream: UnixStream,
18}
19
20impl UnixConnection {
21    pub fn new(fd: RawFd) -> Self {
22        UnixConnection { fd, stream: unsafe { UnixStream::from_raw_fd(fd) } }
23    }
24
25    pub fn try_clone(&self) -> SResult<Self> {
26        Ok(UnixConnection { fd: self.fd, stream: self.stream.try_clone()? })
27    }
28
29    pub(crate) fn id(&self) -> u64 {
30        self.fd as u64
31    }
32
33    pub(crate) fn send_fd(&self, fd: RawFd) {
34        info!("sending fd {}", fd);
35        let fds = [fd];
36        let fd_msg = ControlMessage::ScmRights(&fds);
37        let c = [0xff];
38        let x = IoSlice::new(&c);
39        sendmsg::<()>(self.fd, &[x], &[fd_msg], MsgFlags::empty(), None).unwrap();
40        close(fd).unwrap();
41    }
42
43    pub(crate) fn recv_fd(&self) -> Result<RawFd, ()> {
44        let mut cmsgs = cmsg_space!(RawFd);
45        let mut c = [0];
46        let mut io_slice = [IoSliceMut::new(&mut c)];
47        let result =
48            recvmsg::<()>(self.fd, &mut io_slice, Some(&mut cmsgs), MsgFlags::empty()).unwrap();
49        let mut iter = result.cmsgs();
50        let cmsg = iter.next().ok_or_else(|| {
51            error!("expected a control message");
52        })?;
53        if iter.next().is_some() {
54            error!("expected exactly one control message");
55            return Err(());
56        }
57        match cmsg {
58            ControlMessageOwned::ScmRights(r) =>
59                if r.len() != 1 {
60                    error!("expected exactly one fd");
61                    Err(())
62                } else {
63                    if c[0] != 0xff {
64                        error!("expected a 0xff byte ancillary byte, got {}", c[0]);
65                        return Err(());
66                    }
67                    Ok(r[0])
68                },
69            m => {
70                error!("unexpected cmsg {:?}", m);
71                Err(())
72            }
73        }
74    }
75}
76
77impl Read for UnixConnection {
78    fn read(&mut self, dest: &mut [u8]) -> SResult<usize> {
79        let mut cursor = 0;
80        if dest.is_empty() {
81            return Ok(0);
82        }
83        while cursor < dest.len() {
84            let res: io::Result<usize> = self.stream.read(&mut dest[cursor..]);
85            trace!("read {}: {:?} cursor={} expected={}", self.id(), res, cursor, dest.len());
86            match res {
87                Ok(n) => {
88                    if n == 0 {
89                        return Ok(cursor);
90                    }
91                    cursor = cursor + n;
92                }
93                Err(e) => return Err(e),
94            }
95        }
96        Ok(cursor)
97    }
98}
99
100impl Write for UnixConnection {
101    fn write(&mut self, buf: &[u8]) -> SResult<usize> {
102        self.stream.write(buf)
103    }
104
105    fn flush(&mut self) -> SResult<()> {
106        self.stream.flush()
107    }
108
109    fn write_all(&mut self, buf: &[u8]) -> SResult<()> {
110        self.stream.write_all(buf)
111    }
112}
113
114pub fn open_parent_fd() -> RawFd {
115    // Only use fd 3 if we are really running with a lightningd parent, so we don't conflict with future fd allocation
116    // Check this before opening any files or sockets!
117    let have_parent = unsafe { libc::fcntl(PARENT_FD as libc::c_int, libc::F_GETFD) } != -1;
118
119    let dummy_file = fs::File::open("/dev/null").unwrap().into_raw_fd();
120
121    let parent_fd = if have_parent {
122        close(dummy_file).expect("close dummy");
123        RawFd::from(PARENT_FD)
124    } else {
125        error!("no parent on {}, using /dev/null", PARENT_FD);
126        dummy_file
127    };
128    parent_fd
129}
vls_proxy/connection.rs

vls_proxy/
connection.rs
