// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

/*!

Synchronous DNS Resolution

Contains the functionality to perform DNS resolution in a style related to
getaddrinfo()

*/

use option::{Option, Some, None};
use result::{Ok, Err};
use io::{io_error};
use io::net::ip::{SocketAddr, IpAddr};
use rt::rtio::{IoFactory, LocalIo};
use vec::ImmutableVector;

/// Hints to the types of sockets that are desired when looking up hosts
pub enum SocketType {
    Stream, Datagram, Raw
}

/// Flags which can be or'd into the `flags` field of a `Hint`. These are used
/// to manipulate how a query is performed.
///
/// The meaning of each of these flags can be found with `man -s 3 getaddrinfo`
pub enum Flag {
    AddrConfig,
    All,
    CanonName,
    NumericHost,
    NumericServ,
    Passive,
    V4Mapped,
}

/// A transport protocol associated with either a hint or a return value of
/// `lookup`
pub enum Protocol {
    TCP, UDP
}

/// This structure is used to provide hints when fetching addresses for a
/// remote host to control how the lookup is performed.
///
/// For details on these fields, see their corresponding definitions via
/// `man -s 3 getaddrinfo`
pub struct Hint {
    family: uint,
    socktype: Option<SocketType>,
    protocol: Option<Protocol>,
    flags: uint,
}

pub struct Info {
    address: SocketAddr,
    family: uint,
    socktype: Option<SocketType>,
    protocol: Option<Protocol>,
    flags: uint,
}

/// Easy name resolution. Given a hostname, returns the list of IP addresses for
/// that hostname.
///
/// # Failure
///
/// On failure, this will raise on the `io_error` condition.
pub fn get_host_addresses(host: &str) -> Option<~[IpAddr]> {
    lookup(Some(host), None, None).map(|a| a.map(|i| i.address.ip))
}

/// Full-fleged resolution. This function will perform a synchronous call to
/// getaddrinfo, controlled by the parameters
///
/// # Arguments
///
/// * hostname - an optional hostname to lookup against
/// * servname - an optional service name, listed in the system services
/// * hint - see the hint structure, and "man -s 3 getaddrinfo", for how this
///          controls lookup
///
/// # Failure
///
/// On failure, this will raise on the `io_error` condition.
///
/// XXX: this is not public because the `Hint` structure is not ready for public
///      consumption just yet.
fn lookup(hostname: Option<&str>, servname: Option<&str>, hint: Option<Hint>)
          -> Option<~[Info]> {
    let mut io = LocalIo::borrow();
    match io.get().get_host_addresses(hostname, servname, hint) {
        Ok(i) => Some(i),
        Err(ioerr) => {
            io_error::cond.raise(ioerr);
            None
        }
    }
}

#[cfg(test)]
mod test {
    use option::Some;
    use io::net::ip::Ipv4Addr;
    use super::*;

    #[test]
    #[ignore(cfg(target_os="android"))] // cannot give tcp/ip permission without help of apk
    fn dns_smoke_test() {
        let ipaddrs = get_host_addresses("localhost").unwrap();
        let mut found_local = false;
        let local_addr = &Ipv4Addr(127, 0, 0, 1);
        for addr in ipaddrs.iter() {
            found_local = found_local || addr == local_addr;
        }
        assert!(found_local);
    }
}