c-ares 12.0.0

A Rust wrapper for the c-ares library, for asynchronous DNS requests.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

use std::fmt;
use std::os::raw::{c_int, c_uchar, c_void};
use std::ptr;
use std::slice;

use itertools::Itertools;

use crate::error::{Error, Result};
use crate::hostent::{HasHostent, HostAliasResultsIter, HostentOwned};
use crate::panic;

/// The result of a successful PTR lookup.
#[derive(Debug)]
pub struct PTRResults {
    hostent: HostentOwned,
}

impl PTRResults {
    /// Obtain a `PTRResults` from the response to a PTR lookup.
    pub fn parse_from(data: &[u8]) -> Result<PTRResults> {
        let mut hostent: *mut c_types::hostent = ptr::null_mut();
        let dummy_ip = [0, 0, 0, 0];
        let parse_status = unsafe {
            #[allow(clippy::useless_conversion)]
            c_ares_sys::ares_parse_ptr_reply(
                data.as_ptr(),
                data.len() as c_int,
                dummy_ip.as_ptr().cast(),
                dummy_ip.len() as c_int,
                c_types::AF_INET.into(),
                &mut hostent,
            )
        };
        if parse_status == c_ares_sys::ares_status_t::ARES_SUCCESS as i32 {
            let result = PTRResults::new(hostent);
            Ok(result)
        } else {
            Err(Error::from(parse_status))
        }
    }

    fn new(hostent: *mut c_types::hostent) -> Self {
        PTRResults {
            hostent: HostentOwned::new(hostent),
        }
    }

    /// Returns the hostname from this `PTRResults`.
    pub fn hostname(&self) -> &str {
        self.hostent.hostname()
    }

    /// Returns an iterator over the host aliases in this `PTRResults`.
    pub fn aliases(&self) -> HostAliasResultsIter<'_> {
        self.hostent.aliases()
    }
}

impl fmt::Display for PTRResults {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        write!(fmt, "Hostname: {}, ", self.hostname())?;
        let aliases = self.aliases().format(", ");
        write!(fmt, "Aliases: [{aliases}]")
    }
}

pub(crate) unsafe extern "C" fn query_ptr_callback<F>(
    arg: *mut c_void,
    status: c_int,
    _timeouts: c_int,
    abuf: *mut c_uchar,
    alen: c_int,
) where
    F: FnOnce(Result<PTRResults>) + Send + 'static,
{
    ares_callback!(arg.cast::<F>(), status, abuf, alen, PTRResults::parse_from);
}