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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License..

//! Networking primitives for TCP/UDP communication.
//!
//! This module provides networking functionality for the Transmission Control and User
//! Datagram Protocols, as well as types for IP and socket addresses.
//!

use crate::io::{self, Error, ErrorKind};

pub use self::ip::{IpAddr, Ipv4Addr, Ipv6Addr, Ipv6MulticastScope};
pub use self::addr::{SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
#[cfg(feature = "net")]
pub use self::tcp::TcpStream;
#[cfg(feature = "net")]
pub use self::tcp::TcpListener;
#[cfg(feature = "net")]
pub use self::udp::UdpSocket;
pub use self::parser::AddrParseError;

mod ip;
mod addr;
mod parser;
#[cfg(feature = "net")]
mod tcp;
#[cfg(feature = "net")]
mod udp;

/// Possible values which can be passed to the [`shutdown`] method of
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum Shutdown {
    /// The reading portion of the [`TcpStream`] should be shut down.
    ///
    /// All currently blocked and future [reads] will return [`Ok(0)`].
    ///
    Read,
    /// The writing portion of the [`TcpStream`] should be shut down.
    ///
    /// All currently blocked and future [writes] will return an error.
    ///
    Write,
    /// Both the reading and the writing portions of the [`TcpStream`] should be shut down.
    ///
    Both,
}

#[inline]
const fn htons(i: u16) -> u16 {
    i.to_be()
}
#[inline]
const fn ntohs(i: u16) -> u16 {
    u16::from_be(i)
}

fn each_addr<A: ToSocketAddrs, F, T>(addr: A, mut f: F) -> io::Result<T>
where
    F: FnMut(io::Result<&SocketAddr>) -> io::Result<T>,
{
    let addrs = match addr.to_socket_addrs() {
        Ok(addrs) => addrs,
        Err(e) => return f(Err(e)),
    };
    let mut last_err = None;
    for addr in addrs {
        match f(Ok(&addr)) {
            Ok(l) => return Ok(l),
            Err(e) => last_err = Some(e),
        }
    }
    Err(last_err.unwrap_or_else(|| {
        Error::new(ErrorKind::InvalidInput, "could not resolve to any addresses")
    }))
}