dns_lookup/
nameinfo.rs

1use socket2::SockAddr;
2use std::ffi::CStr;
3use std::io;
4use std::net::SocketAddr;
5use std::os::raw::c_char;
6use std::str;
7
8#[cfg(unix)]
9use libc::{c_char as libc_c_char, getnameinfo as c_getnameinfo};
10
11#[cfg(windows)]
12#[allow(non_camel_case_types)]
13type libc_c_char = u8;
14#[cfg(windows)]
15use windows_sys::Win32::Networking::WinSock::getnameinfo as c_getnameinfo;
16
17use crate::err::LookupError;
18
19/// Retrieve the name for a given IP and Service. Acts as a thin wrapper around
20/// the libc getnameinfo.
21///
22/// Returned names may be encoded in puny code for Interational Domain Names
23/// (UTF8 DNS names). You can use the `idna` crate to decode these to their
24/// actual UTF8 representation.
25///
26/// Retrieving names or services that contain non-UTF8 locales is currently not
27/// supported (as String is returned). Raise an issue if this is a concern for
28/// you.
29pub fn getnameinfo(sock: &SocketAddr, flags: i32) -> Result<(String, String), LookupError> {
30    // Convert the socket into our type, so we can get a sockaddr_in{,6} ptr.
31    let sock: SockAddr = (*sock).into();
32    let c_sock = sock.as_ptr();
33    let c_sock_len = sock.len();
34
35    // Hard code maximums, as they aren't defined in libc/windows-sys.
36
37    // Allocate buffers for name and service strings.
38    let mut c_host = [0 as u8; 1024_usize];
39    // No NI_MAXSERV, so use suggested value.
40    let mut c_service = [0 as u8; 32_usize];
41
42    // Prime windows.
43    #[cfg(windows)]
44    crate::win::init_winsock();
45
46    unsafe {
47        LookupError::match_gai_error(c_getnameinfo(
48            c_sock as *const _,
49            c_sock_len,
50            c_host.as_mut_ptr() as *mut libc_c_char,
51            c_host.len() as _,
52            c_service.as_mut_ptr() as *mut libc_c_char,
53            c_service.len() as _,
54            flags,
55        ))?;
56    }
57
58    let host = unsafe { CStr::from_ptr(c_host.as_ptr() as *const c_char) };
59    let service = unsafe { CStr::from_ptr(c_service.as_ptr() as *const c_char) };
60
61    let host = match str::from_utf8(host.to_bytes()) {
62        Ok(name) => Ok(name.to_owned()),
63        Err(_) => Err(io::Error::new(
64            io::ErrorKind::Other,
65            "Host UTF8 parsing failed",
66        )),
67    }?;
68
69    let service = match str::from_utf8(service.to_bytes()) {
70        Ok(service) => Ok(service.to_owned()),
71        Err(_) => Err(io::Error::new(
72            io::ErrorKind::Other,
73            "Service UTF8 parsing failed",
74        )),
75    }?;
76
77    Ok((host, service))
78}
79
80#[test]
81fn test_getnameinfo() {
82    use std::net::{IpAddr, SocketAddr};
83
84    let ip: IpAddr = "127.0.0.1".parse().unwrap();
85    let port = 22;
86    let socket: SocketAddr = (ip, port).into();
87
88    let (name, service) = match getnameinfo(&socket, 0) {
89        Ok((n, s)) => (n, s),
90        Err(e) => panic!("Failed to lookup socket {:?}", e),
91    };
92
93    assert_eq!(service, "ssh");
94
95    #[cfg(unix)]
96    {
97        assert_eq!(name, "localhost");
98    }
99
100    #[cfg(windows)]
101    {
102        let hostname = crate::hostname::get_hostname().unwrap();
103        assert_eq!(name, hostname);
104    }
105}
dns_lookup/nameinfo.rs

dns_lookup/
nameinfo.rs
