// 测试此模块
#[cfg(all(test, not(target_os = "emscripten")))]
mod tests;

use crate::cmp::Ordering;
use crate::fmt::{self, Write as FmtWrite};
use crate::hash;
use crate::io::Write as IoWrite;
use crate::mem::transmute;
use crate::sys::net::netc as c;
use crate::sys_common::{AsInner, FromInner, IntoInner};

/// IP 地址，IPv4 或 IPv6。
///
/// 该枚举可以包含 [`Ipv4Addr`] 或 [`Ipv6Addr`]，有关更多详细信息，请参见其各自的文档。
///
///
/// `IpAddr` 实例的大小可能会因目标操作系统而异。
///
/// # Examples
///
/// ```
/// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
///
/// let localhost_v4 = IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1));
/// let localhost_v6 = IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
///
/// assert_eq!("127.0.0.1".parse(), Ok(localhost_v4));
/// assert_eq!("::1".parse(), Ok(localhost_v6));
///
/// assert_eq!(localhost_v4.is_ipv6(), false);
/// assert_eq!(localhost_v4.is_ipv4(), true);
/// ```
///
#[stable(feature = "ip_addr", since = "1.7.0")]
#[derive(Copy, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
pub enum IpAddr {
    /// IPv4 地址。
    #[stable(feature = "ip_addr", since = "1.7.0")]
    V4(#[stable(feature = "ip_addr", since = "1.7.0")] Ipv4Addr),
    /// IPv6 地址。
    #[stable(feature = "ip_addr", since = "1.7.0")]
    V6(#[stable(feature = "ip_addr", since = "1.7.0")] Ipv6Addr),
}

/// IPv4 地址。
///
/// IPv4 地址在 [IETF RFC 791] 中定义为 32 位整数。
/// 它们通常表示为四个八位位组。
///
/// 有关同时包含 IPv4 和 IPv6 地址的类型，请参见 [`IpAddr`]。
///
/// `Ipv4Addr` 结构体的大小可能会因目标操作系统而异。
///
/// [IETF RFC 791]: https://tools.ietf.org/html/rfc791
///
/// # 文字表达
///
/// `Ipv4Addr` 提供了 [`FromStr`] 的实现。
/// 四个八位位组用十进制表示法除以 `.` (称为 "dot-decimal notation")。
///
/// 值得注意的是，每个 [IETF RFC 6943] 不允许使用八进制数和十六进制数。
///
/// [IETF RFC 6943]: https://tools.ietf.org/html/rfc6943#section-3.1.1
/// [`FromStr`]: crate::str::FromStr
///
/// # Examples
///
/// ```
/// use std::net::Ipv4Addr;
///
/// let localhost = Ipv4Addr::new(127, 0, 0, 1);
/// assert_eq!("127.0.0.1".parse(), Ok(localhost));
/// assert_eq!(localhost.is_loopback(), true);
/// ```
#[derive(Copy)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Ipv4Addr {
    inner: c::in_addr,
}

/// IPv6 地址。
///
/// IPv6 [IETF RFC 4291] 中将地址定义为 128 位整数。
/// 它们通常表示为八个 16 位段。
///
/// 有关同时包含 IPv4 和 IPv6 地址的类型，请参见 [`IpAddr`]。
///
/// `Ipv6Addr` 结构体的大小可能会因目标操作系统而异。
///
/// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
///
/// # 文字表达
///
/// `Ipv6Addr` 提供了 [`FromStr`] 的实现。
/// 有多种方法可以用文本表示 IPv6 地址，但通常，每个段都以十六进制表示法，并且段之间用 `:` 分隔。
///
/// 有关更多信息，请参见 [IETF RFC 5952]。
///
/// [`FromStr`]: crate::str::FromStr
/// [IETF RFC 5952]: https://tools.ietf.org/html/rfc5952
///
/// # Examples
///
/// ```
/// use std::net::Ipv6Addr;
///
/// let localhost = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
/// assert_eq!("::1".parse(), Ok(localhost));
/// assert_eq!(localhost.is_loopback(), true);
/// ```
///
#[derive(Copy)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Ipv6Addr {
    inner: c::in6_addr,
}

#[allow(missing_docs)]
#[derive(Copy, PartialEq, Eq, Clone, Hash, Debug)]
#[unstable(feature = "ip", issue = "27709")]
pub enum Ipv6MulticastScope {
    InterfaceLocal,
    LinkLocal,
    RealmLocal,
    AdminLocal,
    SiteLocal,
    OrganizationLocal,
    Global,
}

impl IpAddr {
    /// 返回 [`true`] 作为特殊的 'unspecified' 地址。
    ///
    /// 有关更多详细信息，请参见 [`Ipv4Addr::is_unspecified()`] 和 [`Ipv6Addr::is_unspecified()`] 的文档。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)).is_unspecified(), true);
    /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0)).is_unspecified(), true);
    /// ```
    #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
    #[stable(feature = "ip_shared", since = "1.12.0")]
    #[inline]
    pub const fn is_unspecified(&self) -> bool {
        match self {
            IpAddr::V4(ip) => ip.is_unspecified(),
            IpAddr::V6(ip) => ip.is_unspecified(),
        }
    }

    /// 如果这是一个回环地址，则返回 [`true`]。
    ///
    /// 有关更多详细信息，请参见 [`Ipv4Addr::is_loopback()`] 和 [`Ipv6Addr::is_loopback()`] 的文档。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)).is_loopback(), true);
    /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0x1)).is_loopback(), true);
    /// ```
    #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
    #[stable(feature = "ip_shared", since = "1.12.0")]
    #[inline]
    pub const fn is_loopback(&self) -> bool {
        match self {
            IpAddr::V4(ip) => ip.is_loopback(),
            IpAddr::V6(ip) => ip.is_loopback(),
        }
    }

    /// 如果该地址似乎是可全局路由的，则返回 [`true`]。
    ///
    /// 有关更多详细信息，请参见 [`Ipv4Addr::is_global()`] 和 [`Ipv6Addr::is_global()`] 的文档。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(80, 9, 12, 3)).is_global(), true);
    /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1)).is_global(), true);
    /// ```
    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_global(&self) -> bool {
        match self {
            IpAddr::V4(ip) => ip.is_global(),
            IpAddr::V6(ip) => ip.is_global(),
        }
    }

    /// 如果这是一个多播地址，则返回 [`true`]。
    ///
    /// 有关更多详细信息，请参见 [`Ipv4Addr::is_multicast()`] 和 [`Ipv6Addr::is_multicast()`] 的文档。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(224, 254, 0, 0)).is_multicast(), true);
    /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0)).is_multicast(), true);
    /// ```
    #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
    #[stable(feature = "ip_shared", since = "1.12.0")]
    #[inline]
    pub const fn is_multicast(&self) -> bool {
        match self {
            IpAddr::V4(ip) => ip.is_multicast(),
            IpAddr::V6(ip) => ip.is_multicast(),
        }
    }

    /// 如果此地址在文档指定的范围内，则返回 [`true`]。
    ///
    /// 有关更多详细信息，请参见 [`Ipv4Addr::is_documentation()`] 和 [`Ipv6Addr::is_documentation()`] 的文档。
    ///
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(203, 0, 113, 6)).is_documentation(), true);
    /// assert_eq!(
    ///     IpAddr::V6(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0)).is_documentation(),
    ///     true
    /// );
    /// ```
    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_documentation(&self) -> bool {
        match self {
            IpAddr::V4(ip) => ip.is_documentation(),
            IpAddr::V6(ip) => ip.is_documentation(),
        }
    }

    /// 如果此地址是 [`IPv4` address]，则返回 [`true`]，否则返回 [`false`]。
    ///
    ///
    /// [`IPv4` address]: IpAddr::V4
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(203, 0, 113, 6)).is_ipv4(), true);
    /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0)).is_ipv4(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
    #[stable(feature = "ipaddr_checker", since = "1.16.0")]
    #[inline]
    pub const fn is_ipv4(&self) -> bool {
        matches!(self, IpAddr::V4(_))
    }

    /// 如果此地址是 [`IPv6` address]，则返回 [`true`]，否则返回 [`false`]。
    ///
    ///
    /// [`IPv6` address]: IpAddr::V6
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(203, 0, 113, 6)).is_ipv6(), false);
    /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0)).is_ipv6(), true);
    /// ```
    #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
    #[stable(feature = "ipaddr_checker", since = "1.16.0")]
    #[inline]
    pub const fn is_ipv6(&self) -> bool {
        matches!(self, IpAddr::V6(_))
    }
}

impl Ipv4Addr {
    /// 从四个八位八位字节创建一个新的 IPv4 地址。
    ///
    /// 结果将代表 IP 地址 `a`.`b`.`c`.`d`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::new(127, 0, 0, 1);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.32.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn new(a: u8, b: u8, c: u8, d: u8) -> Ipv4Addr {
        // `s_addr` 在所有计算机上都存储为 BE，并且阵列按 BE 顺序排列。
        // 因此，使用了本地字节序转换方法，因此它永远不会被交换。
        Ipv4Addr { inner: c::in_addr { s_addr: u32::from_ne_bytes([a, b, c, d]) } }
    }

    /// 一个 IPv4 地址，该地址指向 localhost: `127.0.0.1`
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::LOCALHOST;
    /// assert_eq!(addr, Ipv4Addr::new(127, 0, 0, 1));
    /// ```
    #[stable(feature = "ip_constructors", since = "1.30.0")]
    pub const LOCALHOST: Self = Ipv4Addr::new(127, 0, 0, 1);

    /// 代表未指定地址的 IPv4 地址: `0.0.0.0`
    ///
    /// 这对应于其他语言中的常量 `INADDR_ANY`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::UNSPECIFIED;
    /// assert_eq!(addr, Ipv4Addr::new(0, 0, 0, 0));
    /// ```
    #[doc(alias = "INADDR_ANY")]
    #[stable(feature = "ip_constructors", since = "1.30.0")]
    pub const UNSPECIFIED: Self = Ipv4Addr::new(0, 0, 0, 0);

    /// 表示广播地址的 IPv4 地址: `255.255.255.255`
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::BROADCAST;
    /// assert_eq!(addr, Ipv4Addr::new(255, 255, 255, 255));
    /// ```
    #[stable(feature = "ip_constructors", since = "1.30.0")]
    pub const BROADCAST: Self = Ipv4Addr::new(255, 255, 255, 255);

    /// 返回组成该地址的四个八位整数。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::new(127, 0, 0, 1);
    /// assert_eq!(addr.octets(), [127, 0, 0, 1]);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn octets(&self) -> [u8; 4] {
        // 这将返回我们想要的顺序，因为 s_addr 存储在 big-endian 中。
        self.inner.s_addr.to_ne_bytes()
    }

    /// 为特殊的 'unspecified' 地址 (`0.0.0.0`) 返回 [`true`]。
    ///
    /// 此属性在 _UNIX Network Programming, Second Edition_，W 中定义。理查德・史蒂文斯 (Richard Stevens)，第
    /// 891; 另请参见 [ip7]。
    ///
    /// [ip7]: https://man7.org/linux/man-pages/man7/ip.7.html
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(0, 0, 0, 0).is_unspecified(), true);
    /// assert_eq!(Ipv4Addr::new(45, 22, 13, 197).is_unspecified(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.32.0")]
    #[stable(feature = "ip_shared", since = "1.12.0")]
    #[inline]
    pub const fn is_unspecified(&self) -> bool {
        self.inner.s_addr == 0
    }

    /// 如果这是回环地址 (`127.0.0.0/8`)，则返回 [`true`]。
    ///
    /// 此属性由 [IETF RFC 1122] 定义。
    ///
    /// [IETF RFC 1122]: https://tools.ietf.org/html/rfc1122
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(127, 0, 0, 1).is_loopback(), true);
    /// assert_eq!(Ipv4Addr::new(45, 22, 13, 197).is_loopback(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_loopback(&self) -> bool {
        self.octets()[0] == 127
    }

    /// 如果这是一个专用地址，则返回 [`true`]。
    ///
    /// 专用地址范围在 [IETF RFC 1918] 中定义，包括:
    ///
    ///  - `10.0.0.0/8`
    ///  - `172.16.0.0/12`
    ///  - `192.168.0.0/16`
    ///
    /// [IETF RFC 1918]: https://tools.ietf.org/html/rfc1918
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(10, 0, 0, 1).is_private(), true);
    /// assert_eq!(Ipv4Addr::new(10, 10, 10, 10).is_private(), true);
    /// assert_eq!(Ipv4Addr::new(172, 16, 10, 10).is_private(), true);
    /// assert_eq!(Ipv4Addr::new(172, 29, 45, 14).is_private(), true);
    /// assert_eq!(Ipv4Addr::new(172, 32, 0, 2).is_private(), false);
    /// assert_eq!(Ipv4Addr::new(192, 168, 0, 2).is_private(), true);
    /// assert_eq!(Ipv4Addr::new(192, 169, 0, 2).is_private(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_private(&self) -> bool {
        match self.octets() {
            [10, ..] => true,
            [172, b, ..] if b >= 16 && b <= 31 => true,
            [192, 168, ..] => true,
            _ => false,
        }
    }

    /// 如果地址是本地链接 (`169.254.0.0/16`)，则返回 [`true`]。
    ///
    /// 此属性由 [IETF RFC 3927] 定义。
    ///
    /// [IETF RFC 3927]: https://tools.ietf.org/html/rfc3927
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(169, 254, 0, 0).is_link_local(), true);
    /// assert_eq!(Ipv4Addr::new(169, 254, 10, 65).is_link_local(), true);
    /// assert_eq!(Ipv4Addr::new(16, 89, 10, 65).is_link_local(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_link_local(&self) -> bool {
        matches!(self.octets(), [169, 254, ..])
    }

    /// 如果该地址似乎是可全局路由的，则返回 [`true`]。
    /// 请参见 [iana-ipv4-special-registry][ipv4-sr]。
    ///
    /// 以下返回 [`false`]:
    ///
    /// - 专用地址 (请参见 [`Ipv4Addr::is_private()`])
    /// - 回环地址 (请参见 [`Ipv4Addr::is_loopback()`])
    /// - 链接本地地址 (请参见 [`Ipv4Addr::is_link_local()`])
    /// - 广播地址 (请参见 [`Ipv4Addr::is_broadcast()`])
    /// - 用于文档的地址 (请参见 [`Ipv4Addr::is_documentation()`])
    /// - 未指定的地址 (请参见 [`Ipv4Addr::is_unspecified()`])，以及整个 `0.0.0.0/8` 块
    /// - 为 future 协议保留的地址 (请参见 [`Ipv4Addr::is_ietf_protocol_assignment()`]，但 `192.0.0.9/32` 和 `192.0.0.10/32` 除外，它们可以全局路由
    ///
    /// - 保留供 future 使用的地址 (请参见 [`Ipv4Addr::is_reserved()`]
    /// - 为网络设备基准测试保留的地址 (请参见 [`Ipv4Addr::is_benchmarking()`])
    ///
    /// [ipv4-sr]: https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv4Addr;
    ///
    /// // private 地址不是
    /// assert_eq!(Ipv4Addr::new(10, 254, 0, 0).is_global(), false);
    /// assert_eq!(Ipv4Addr::new(192, 168, 10, 65).is_global(), false);
    /// assert_eq!(Ipv4Addr::new(172, 16, 10, 65).is_global(), false);
    ///
    /// // 0.0.0.0/8 块不是
    /// assert_eq!(Ipv4Addr::new(0, 1, 2, 3).is_global(), false);
    /// // 特别是，未指定的地址不是
    /// assert_eq!(Ipv4Addr::new(0, 0, 0, 0).is_global(), false);
    ///
    /// // 回环地址不是整体
    /// assert_eq!(Ipv4Addr::new(127, 0, 0, 1).is_global(), false);
    ///
    /// // 链接本地地址不是
    /// assert_eq!(Ipv4Addr::new(169, 254, 45, 1).is_global(), false);
    ///
    /// // 广播地址不是
    /// assert_eq!(Ipv4Addr::new(255, 255, 255, 255).is_global(), false);
    ///
    /// // 指定用于文档的地址空间不是
    /// assert_eq!(Ipv4Addr::new(192, 0, 2, 255).is_global(), false);
    /// assert_eq!(Ipv4Addr::new(198, 51, 100, 65).is_global(), false);
    /// assert_eq!(Ipv4Addr::new(203, 0, 113, 6).is_global(), false);
    ///
    /// // 共享地址不是
    /// assert_eq!(Ipv4Addr::new(100, 100, 0, 0).is_global(), false);
    ///
    /// // 保留用于协议分配的地址不是
    /// assert_eq!(Ipv4Addr::new(192, 0, 0, 0).is_global(), false);
    /// assert_eq!(Ipv4Addr::new(192, 0, 0, 255).is_global(), false);
    ///
    /// // 保留供 future 使用的地址不是整数
    /// assert_eq!(Ipv4Addr::new(250, 10, 20, 30).is_global(), false);
    ///
    /// // 为网络设备基准测试保留的地址不是
    /// assert_eq!(Ipv4Addr::new(198, 18, 0, 0).is_global(), false);
    ///
    /// // 所有其他地址均为
    /// assert_eq!(Ipv4Addr::new(1, 1, 1, 1).is_global(), true);
    /// assert_eq!(Ipv4Addr::new(80, 9, 12, 3).is_global(), true);
    /// ```
    ///
    ///
    ///
    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_global(&self) -> bool {
        // 检查此地址是 192.0.0.9 还是 192.0.0.10。
        // 这些地址是 192.0.0.0/24 范围内仅有的两个全局可路由地址。
        if u32::from_be_bytes(self.octets()) == 0xc0000009
            || u32::from_be_bytes(self.octets()) == 0xc000000a
        {
            return true;
        }
        !self.is_private()
            && !self.is_loopback()
            && !self.is_link_local()
            && !self.is_broadcast()
            && !self.is_documentation()
            && !self.is_shared()
            && !self.is_ietf_protocol_assignment()
            && !self.is_reserved()
            && !self.is_benchmarking()
            // 确保地址不在 0.0.0.0/8 中
            && self.octets()[0] != 0
    }

    /// 如果此地址是 [IETF RFC 6598] (`100.64.0.0/10`) 中定义的共享地址空间的一部分，则返回 [`true`]。
    ///
    ///
    /// [IETF RFC 6598]: https://tools.ietf.org/html/rfc6598
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(100, 64, 0, 0).is_shared(), true);
    /// assert_eq!(Ipv4Addr::new(100, 127, 255, 255).is_shared(), true);
    /// assert_eq!(Ipv4Addr::new(100, 128, 0, 0).is_shared(), false);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_shared(&self) -> bool {
        self.octets()[0] == 100 && (self.octets()[1] & 0b1100_0000 == 0b0100_0000)
    }

    /// 如果此地址是 `192.0.0.0/24` 的一部分，则返回 [`true`]，如 [IETF RFC 6890] 中所述，该地址保留给 IANA 用于 IETF 协议分配。
    ///
    ///
    /// 请注意，此块的某些部分正在使用中:
    ///
    /// - `192.0.0.8/32` 是 "IPv4 dummy address" (请参见 [IETF RFC 7600])
    /// - `192.0.0.9/32` 是 "Port Control Protocol Anycast" (请参见 [IETF RFC 7723])
    /// - `192.0.0.10/32` 用于 NAT 遍历 (请参见 [IETF RFC 8155])
    ///
    /// [IETF RFC 6890]: https://tools.ietf.org/html/rfc6890
    /// [IETF RFC 7600]: https://tools.ietf.org/html/rfc7600
    /// [IETF RFC 7723]: https://tools.ietf.org/html/rfc7723
    /// [IETF RFC 8155]: https://tools.ietf.org/html/rfc8155
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(192, 0, 0, 0).is_ietf_protocol_assignment(), true);
    /// assert_eq!(Ipv4Addr::new(192, 0, 0, 8).is_ietf_protocol_assignment(), true);
    /// assert_eq!(Ipv4Addr::new(192, 0, 0, 9).is_ietf_protocol_assignment(), true);
    /// assert_eq!(Ipv4Addr::new(192, 0, 0, 255).is_ietf_protocol_assignment(), true);
    /// assert_eq!(Ipv4Addr::new(192, 0, 1, 0).is_ietf_protocol_assignment(), false);
    /// assert_eq!(Ipv4Addr::new(191, 255, 255, 255).is_ietf_protocol_assignment(), false);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_ietf_protocol_assignment(&self) -> bool {
        self.octets()[0] == 192 && self.octets()[1] == 0 && self.octets()[2] == 0
    }

    /// 如果此地址属于 `198.18.0.0/15` 范围 (为网络设备基准测试保留)，则返回 [`true`]。
    /// [IETF RFC 2544] 将该范围定义为 `192.18.0.0` 至 `198.19.255.255`，但 [errata 423] 将其更正为 `198.18.0.0/15`。
    ///
    ///
    /// [IETF RFC 2544]: https://tools.ietf.org/html/rfc2544
    /// [errata 423]: https://www.rfc-editor.org/errata/eid423
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(198, 17, 255, 255).is_benchmarking(), false);
    /// assert_eq!(Ipv4Addr::new(198, 18, 0, 0).is_benchmarking(), true);
    /// assert_eq!(Ipv4Addr::new(198, 19, 255, 255).is_benchmarking(), true);
    /// assert_eq!(Ipv4Addr::new(198, 20, 0, 0).is_benchmarking(), false);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_benchmarking(&self) -> bool {
        self.octets()[0] == 198 && (self.octets()[1] & 0xfe) == 18
    }

    /// 如果此地址由 IANA 保留供 future 使用，则返回 [`true`]。[IETF RFC 1112] 将保留地址块定义为 `240.0.0.0/4`。
    /// 此范围通常包括广播地址 `255.255.255.255`，但是此实现方案明确将其排除在外，因为它显然不保留供 future 使用。
    ///
    ///
    /// [IETF RFC 1112]: https://tools.ietf.org/html/rfc1112
    ///
    /// # Warning
    ///
    /// 随着 IANA 分配新地址，此方法将被更新。
    /// 这可能会导致未保留的地址被视为依赖于此方法的过时版本的代码中的保留地址。
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(240, 0, 0, 0).is_reserved(), true);
    /// assert_eq!(Ipv4Addr::new(255, 255, 255, 254).is_reserved(), true);
    ///
    /// assert_eq!(Ipv4Addr::new(239, 255, 255, 255).is_reserved(), false);
    /// // 此实现不将广播地址视为保留给 future 使用
    /// assert_eq!(Ipv4Addr::new(255, 255, 255, 255).is_reserved(), false);
    /// ```
    ///
    ///
    ///
    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_reserved(&self) -> bool {
        self.octets()[0] & 240 == 240 && !self.is_broadcast()
    }

    /// 如果这是多播地址 (`224.0.0.0/4`)，则返回 [`true`]。
    ///
    /// 多播地址在 `224` 和 `239` 之间有一个最重要的八位字节，由 [IETF RFC 5771] 定义。
    ///
    ///
    /// [IETF RFC 5771]: https://tools.ietf.org/html/rfc5771
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(224, 254, 0, 0).is_multicast(), true);
    /// assert_eq!(Ipv4Addr::new(236, 168, 10, 65).is_multicast(), true);
    /// assert_eq!(Ipv4Addr::new(172, 16, 10, 65).is_multicast(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_multicast(&self) -> bool {
        self.octets()[0] >= 224 && self.octets()[0] <= 239
    }

    /// 如果这是广播地址 (`255.255.255.255`)，则返回 [`true`]。
    ///
    /// 广播地址的所有八位字节都设置为 `255`，如 [IETF RFC 919] 中所定义。
    ///
    /// [IETF RFC 919]: https://tools.ietf.org/html/rfc919
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(255, 255, 255, 255).is_broadcast(), true);
    /// assert_eq!(Ipv4Addr::new(236, 168, 10, 65).is_broadcast(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_broadcast(&self) -> bool {
        u32::from_be_bytes(self.octets()) == u32::from_be_bytes(Self::BROADCAST.octets())
    }

    /// 如果此地址在文档指定的范围内，则返回 [`true`]。
    ///
    /// 这在 [IETF RFC 5737] 中定义:
    ///
    /// - `192.0.2.0/24` (TEST-NET-1)
    /// - `198.51.100.0/24` (TEST-NET-2)
    /// - `203.0.113.0/24` (TEST-NET-3)
    ///
    /// [IETF RFC 5737]: https://tools.ietf.org/html/rfc5737
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// assert_eq!(Ipv4Addr::new(192, 0, 2, 255).is_documentation(), true);
    /// assert_eq!(Ipv4Addr::new(198, 51, 100, 65).is_documentation(), true);
    /// assert_eq!(Ipv4Addr::new(203, 0, 113, 6).is_documentation(), true);
    /// assert_eq!(Ipv4Addr::new(193, 34, 17, 19).is_documentation(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_documentation(&self) -> bool {
        match self.octets() {
            [192, 0, 2, _] => true,
            [198, 51, 100, _] => true,
            [203, 0, 113, _] => true,
            _ => false,
        }
    }

    /// 将该地址转换为兼容 IPv4 的 [`IPv6` address]。
    ///
    /// `a.b.c.d` 变成 `::a.b.c.d`
    ///
    /// 这通常不是您想要的方法。这些地址通常在现代系统上不起作用。
    /// 请改用 `to_ipv6_mapped`。
    ///
    /// [`IPv6` address]: Ipv6Addr
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(
    ///     Ipv4Addr::new(192, 0, 2, 255).to_ipv6_compatible(),
    ///     Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0xc000, 0x2ff)
    /// );
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn to_ipv6_compatible(&self) -> Ipv6Addr {
        let [a, b, c, d] = self.octets();
        Ipv6Addr {
            inner: c::in6_addr { s6_addr: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, a, b, c, d] },
        }
    }

    /// 将此地址转换为 IPv4 映射的 [`IPv6` address]。
    ///
    /// `a.b.c.d` 变成 `::ffff:a.b.c.d`
    ///
    /// [`IPv6` address]: Ipv6Addr
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(Ipv4Addr::new(192, 0, 2, 255).to_ipv6_mapped(),
    ///            Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc000, 0x2ff));
    /// ```
    #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn to_ipv6_mapped(&self) -> Ipv6Addr {
        let [a, b, c, d] = self.octets();
        Ipv6Addr {
            inner: c::in6_addr { s6_addr: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, a, b, c, d] },
        }
    }
}

#[stable(feature = "ip_addr", since = "1.7.0")]
impl fmt::Display for IpAddr {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            IpAddr::V4(ip) => ip.fmt(fmt),
            IpAddr::V6(ip) => ip.fmt(fmt),
        }
    }
}

#[stable(feature = "ip_addr", since = "1.7.0")]
impl fmt::Debug for IpAddr {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(self, fmt)
    }
}

#[stable(feature = "ip_from_ip", since = "1.16.0")]
impl From<Ipv4Addr> for IpAddr {
    /// 将此地址复制到新的 `IpAddr::V4`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr};
    ///
    /// let addr = Ipv4Addr::new(127, 0, 0, 1);
    ///
    /// assert_eq!(
    ///     IpAddr::V4(addr),
    ///     IpAddr::from(addr)
    /// )
    /// ```
    #[inline]
    fn from(ipv4: Ipv4Addr) -> IpAddr {
        IpAddr::V4(ipv4)
    }
}

#[stable(feature = "ip_from_ip", since = "1.16.0")]
impl From<Ipv6Addr> for IpAddr {
    /// 将此地址复制到新的 `IpAddr::V6`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv6Addr};
    ///
    /// let addr = Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff);
    ///
    /// assert_eq!(
    ///     IpAddr::V6(addr),
    ///     IpAddr::from(addr)
    /// );
    /// ```
    #[inline]
    fn from(ipv6: Ipv6Addr) -> IpAddr {
        IpAddr::V6(ipv6)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Display for Ipv4Addr {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        let octets = self.octets();
        // 快速路径: 如果没有对齐内容，则直接写入缓冲区
        if fmt.precision().is_none() && fmt.width().is_none() {
            write!(fmt, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3])
        } else {
            const IPV4_BUF_LEN: usize = 15; // 足够长以可能的最长 IPv4 地址
            let mut buf = [0u8; IPV4_BUF_LEN];
            let mut buf_slice = &mut buf[..];

            // Note: 调用应该永远不会失败，因此解开包装
            write!(buf_slice, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3]).unwrap();
            let len = IPV4_BUF_LEN - buf_slice.len();

            // 这种不安全的行为是可以的，因为我们知道正在将什么内容写入缓冲区
            let buf = unsafe { crate::str::from_utf8_unchecked(&buf[..len]) };
            fmt.pad(buf)
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for Ipv4Addr {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(self, fmt)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Clone for Ipv4Addr {
    #[inline]
    fn clone(&self) -> Ipv4Addr {
        *self
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialEq for Ipv4Addr {
    #[inline]
    fn eq(&self, other: &Ipv4Addr) -> bool {
        self.inner.s_addr == other.inner.s_addr
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialEq<Ipv4Addr> for IpAddr {
    #[inline]
    fn eq(&self, other: &Ipv4Addr) -> bool {
        match self {
            IpAddr::V4(v4) => v4 == other,
            IpAddr::V6(_) => false,
        }
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialEq<IpAddr> for Ipv4Addr {
    #[inline]
    fn eq(&self, other: &IpAddr) -> bool {
        match other {
            IpAddr::V4(v4) => self == v4,
            IpAddr::V6(_) => false,
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Eq for Ipv4Addr {}

#[stable(feature = "rust1", since = "1.0.0")]
impl hash::Hash for Ipv4Addr {
    #[inline]
    fn hash<H: hash::Hasher>(&self, s: &mut H) {
        // NOTE:
        // * 按大端顺序的哈希
        // * 在 netbsd 中，`in_addr` 具有 `repr(packed)`，我们需要复制 `s_addr` 以避免不安全的借用
        //
        { self.inner.s_addr }.hash(s)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for Ipv4Addr {
    #[inline]
    fn partial_cmp(&self, other: &Ipv4Addr) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialOrd<Ipv4Addr> for IpAddr {
    #[inline]
    fn partial_cmp(&self, other: &Ipv4Addr) -> Option<Ordering> {
        match self {
            IpAddr::V4(v4) => v4.partial_cmp(other),
            IpAddr::V6(_) => Some(Ordering::Greater),
        }
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialOrd<IpAddr> for Ipv4Addr {
    #[inline]
    fn partial_cmp(&self, other: &IpAddr) -> Option<Ordering> {
        match other {
            IpAddr::V4(v4) => self.partial_cmp(v4),
            IpAddr::V6(_) => Some(Ordering::Less),
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for Ipv4Addr {
    #[inline]
    fn cmp(&self, other: &Ipv4Addr) -> Ordering {
        // 比较为本地字节序
        u32::from_be(self.inner.s_addr).cmp(&u32::from_be(other.inner.s_addr))
    }
}

impl IntoInner<c::in_addr> for Ipv4Addr {
    #[inline]
    fn into_inner(self) -> c::in_addr {
        self.inner
    }
}

#[stable(feature = "ip_u32", since = "1.1.0")]
impl From<Ipv4Addr> for u32 {
    /// 将 `Ipv4Addr` 转换为主机字节顺序 `u32`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::new(0xca, 0xfe, 0xba, 0xbe);
    /// assert_eq!(0xcafebabe, u32::from(addr));
    /// ```
    #[inline]
    fn from(ip: Ipv4Addr) -> u32 {
        let ip = ip.octets();
        u32::from_be_bytes(ip)
    }
}

#[stable(feature = "ip_u32", since = "1.1.0")]
impl From<u32> for Ipv4Addr {
    /// 将主机字节顺序 `u32` 转换为 `Ipv4Addr`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::from(0xcafebabe);
    /// assert_eq!(Ipv4Addr::new(0xca, 0xfe, 0xba, 0xbe), addr);
    /// ```
    #[inline]
    fn from(ip: u32) -> Ipv4Addr {
        Ipv4Addr::from(ip.to_be_bytes())
    }
}

#[stable(feature = "from_slice_v4", since = "1.9.0")]
impl From<[u8; 4]> for Ipv4Addr {
    /// 从一个四元素字节数组创建一个 `Ipv4Addr`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv4Addr;
    ///
    /// let addr = Ipv4Addr::from([13u8, 12u8, 11u8, 10u8]);
    /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
    /// ```
    #[inline]
    fn from(octets: [u8; 4]) -> Ipv4Addr {
        Ipv4Addr::new(octets[0], octets[1], octets[2], octets[3])
    }
}

#[stable(feature = "ip_from_slice", since = "1.17.0")]
impl From<[u8; 4]> for IpAddr {
    /// 从一个四元素字节数组创建一个 `IpAddr::V4`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv4Addr};
    ///
    /// let addr = IpAddr::from([13u8, 12u8, 11u8, 10u8]);
    /// assert_eq!(IpAddr::V4(Ipv4Addr::new(13, 12, 11, 10)), addr);
    /// ```
    #[inline]
    fn from(octets: [u8; 4]) -> IpAddr {
        IpAddr::V4(Ipv4Addr::from(octets))
    }
}

impl Ipv6Addr {
    /// 从八个 16 位段创建一个新的 IPv6 地址。
    ///
    /// 结果将代表 IP 地址 `a:b:c:d:e:f:g:h`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff);
    /// ```
    #[rustc_allow_const_fn_unstable(const_fn_transmute)]
    #[rustc_const_stable(feature = "const_ipv6", since = "1.32.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn new(a: u16, b: u16, c: u16, d: u16, e: u16, f: u16, g: u16, h: u16) -> Ipv6Addr {
        let addr16 = [
            a.to_be(),
            b.to_be(),
            c.to_be(),
            d.to_be(),
            e.to_be(),
            f.to_be(),
            g.to_be(),
            h.to_be(),
        ];
        Ipv6Addr {
            inner: c::in6_addr {
                // `addr16` 中的所有元素均为大端。
                // SAFETY: `[u16; 8]` 始终可以安全地转换为 `[u8; 16]`。
                // rustc_allow_const_fn_unstable: 该 transmute 可以编写为稳定的 const 代码，但这会导致更糟糕的代码生成 (#75085)
                //
                s6_addr: unsafe { transmute::<_, [u8; 16]>(addr16) },
            },
        }
    }

    /// 表示本地主机的 IPv6 地址: `::1`.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::LOCALHOST;
    /// assert_eq!(addr, Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
    /// ```
    #[stable(feature = "ip_constructors", since = "1.30.0")]
    pub const LOCALHOST: Self = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);

    /// 表示未指定地址的 IPv6 地址: `::`
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::UNSPECIFIED;
    /// assert_eq!(addr, Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0));
    /// ```
    #[stable(feature = "ip_constructors", since = "1.30.0")]
    pub const UNSPECIFIED: Self = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0);

    /// 返回组成该地址的八个 16 位段。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).segments(),
    ///            [0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff]);
    /// ```
    #[rustc_allow_const_fn_unstable(const_fn_transmute)]
    #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn segments(&self) -> [u16; 8] {
        // `s6_addr` 中的所有元素必须为大端。
        // SAFETY: `[u8; 16]` 始终可以安全地转换为 `[u16; 8]`。
        // rustc_allow_const_fn_unstable: 该 transmute 可以编写为稳定的 const 代码，但这会导致更糟糕的代码生成 (#75085)
        //
        let [a, b, c, d, e, f, g, h] = unsafe { transmute::<_, [u16; 8]>(self.inner.s6_addr) };
        // 我们想要本地字节序 u16
        [
            u16::from_be(a),
            u16::from_be(b),
            u16::from_be(c),
            u16::from_be(d),
            u16::from_be(e),
            u16::from_be(f),
            u16::from_be(g),
            u16::from_be(h),
        ]
    }

    /// 为特殊的 'unspecified' 地址 (`::`) 返回 [`true`]。
    ///
    /// 此属性在 [IETF RFC 4291] 中定义。
    ///
    /// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unspecified(), false);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0).is_unspecified(), true);
    /// ```
    #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_unspecified(&self) -> bool {
        u128::from_be_bytes(self.octets()) == u128::from_be_bytes(Ipv6Addr::UNSPECIFIED.octets())
    }

    /// 如果这是一个回环地址 (::1)，则返回 [`true`]。
    ///
    /// 此属性在 [IETF RFC 4291] 中定义。
    ///
    /// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_loopback(), false);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0x1).is_loopback(), true);
    /// ```
    #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_loopback(&self) -> bool {
        u128::from_be_bytes(self.octets()) == u128::from_be_bytes(Ipv6Addr::LOCALHOST.octets())
    }

    /// 如果该地址似乎是可全局路由的，则返回 [`true`]。
    ///
    /// 以下返回 [`false`]:
    ///
    /// - 回环地址
    /// - 本地链接和唯一本地单播地址
    /// - 接口，链接，领域，管理和站点本地多播地址
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_global(), true);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0x1).is_global(), false);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1).is_global(), true);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_global(&self) -> bool {
        match self.multicast_scope() {
            Some(Ipv6MulticastScope::Global) => true,
            None => self.is_unicast_global(),
            _ => false,
        }
    }

    /// 如果这是唯一的本地地址 (`fc00::/7`)，则返回 [`true`]。
    ///
    /// 此属性在 [IETF RFC 4193] 中定义。
    ///
    /// [IETF RFC 4193]: https://tools.ietf.org/html/rfc4193
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unique_local(), false);
    /// assert_eq!(Ipv6Addr::new(0xfc02, 0, 0, 0, 0, 0, 0, 0).is_unique_local(), true);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_unique_local(&self) -> bool {
        (self.segments()[0] & 0xfe00) == 0xfc00
    }

    /// 如果这是 [IETF RFC 4291] 定义的单播地址，则返回 [`true`]。
    /// 任何不是 [multicast address] (`ff00::/8`) 的地址都是单播的。
    ///
    /// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
    /// [multicast address]: Ipv6Addr::is_multicast
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv6Addr;
    ///
    /// // 未指定地址和回环地址是单播的。
    /// assert_eq!(Ipv6Addr::UNSPECIFIED.is_unicast(), true);
    /// assert_eq!(Ipv6Addr::LOCALHOST.is_unicast(), true);
    ///
    /// // 任何不是多播地址 (`ff00::/8`) 的地址都是单播的。
    /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast(), true);
    /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).is_unicast(), false);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_unicast(&self) -> bool {
        !self.is_multicast()
    }

    /// 如果地址是具有链接本地作用域的单播地址，则返回 `true`，如 [RFC 4291] 中所定义。
    ///
    /// 如果单播地址具有前缀 `fe80::/10`，则它具有链路本地作用域，如 [RFC 4291 section 2.4]。
    /// 请注意，这包含比 [RFC 4291 section 2.5.6] 中定义的地址更多的地址，[RFC 4291 section 2.5.6] 将 "Link-Local IPv6 Unicast Addresses" 描述为具有以下更严格的格式:
    ///
    /// ```text
    /// | 10 bits  |         54 bits         |          64 bits           |
    /// +----------+-------------------------+----------------------------+
    /// |1111111010|           0             |       interface ID         |
    /// +----------+-------------------------+----------------------------+
    /// ```
    /// 因此，虽然目前应用程序将遇到的唯一具有本地链接作用域的地址都在 `fe80::/64` 中，但随着新标准的发布，这可能会在 future 中发生变化。
    /// `fe80::/10` 中可以分配更多的地址，这些地址将具有本地链接作用域。
    ///
    /// 另请注意，虽然 [RFC 4291 section 2.5.3] 提到 "它被视为具有 Link-Local 作用域" 的 [loopback address] (`::1`)，但这并不意味着回环地址实际上具有链接本地作用域，并且此方法将在其上返回 `false`。
    ///
    ///
    /// [RFC 4291]: https://tools.ietf.org/html/rfc4291
    /// [RFC 4291 section 2.4]: https://tools.ietf.org/html/rfc4291#section-2.4
    /// [RFC 4291 section 2.5.3]: https://tools.ietf.org/html/rfc4291#section-2.5.3
    /// [RFC 4291 section 2.5.6]: https://tools.ietf.org/html/rfc4291#section-2.5.6
    /// [loopback address]: Ipv6Addr::LOCALHOST
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv6Addr;
    ///
    /// // 回环地址 (`::1`) 实际上并没有链接本地作用域。
    /// assert_eq!(Ipv6Addr::LOCALHOST.is_unicast_link_local(), false);
    ///
    /// // 只有 `fe80::/10` 中的地址具有本地链接作用域。
    /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), false);
    /// assert_eq!(Ipv6Addr::new(0xfe80, 0, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), true);
    ///
    /// // 更严格的 `fe80::/64` 之外的地址也具有链接本地作用域。
    /// assert_eq!(Ipv6Addr::new(0xfe80, 0, 0, 1, 0, 0, 0, 0).is_unicast_link_local(), true);
    /// assert_eq!(Ipv6Addr::new(0xfe81, 0, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), true);
    /// ```
    ///
    ///
    ///
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_unicast_link_local(&self) -> bool {
        (self.segments()[0] & 0xffc0) == 0xfe80
    }

    /// 如果这是为文档 (`2001:db8::/32`) 保留的地址，则返回 [`true`]。
    ///
    ///
    /// 此属性在 [IETF RFC 3849] 中定义。
    ///
    /// [IETF RFC 3849]: https://tools.ietf.org/html/rfc3849
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_documentation(), false);
    /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_documentation(), true);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_documentation(&self) -> bool {
        (self.segments()[0] == 0x2001) && (self.segments()[1] == 0xdb8)
    }

    /// 如果该地址是全局可路由的单播地址，则返回 [`true`]。
    ///
    /// 以下返回 false:
    ///
    /// - 回环地址
    /// - 链接本地地址
    /// - 唯一的本地地址
    /// - 未指定地址
    /// - 保留用于文档的地址范围
    ///
    /// 此方法根据 [RFC 4291 section 2.5.7] 返回 [`true`] 作为站点本地地址
    ///
    /// ```no_rust
    /// The special behavior of [the site-local unicast] prefix defined in [RFC3513] must no longer
    /// be supported in new implementations (i.e., new implementations must treat this prefix as
    /// Global Unicast).
    /// ```
    ///
    /// [RFC 4291 section 2.5.7]: https://tools.ietf.org/html/rfc4291#section-2.5.7
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast_global(), false);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unicast_global(), true);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn is_unicast_global(&self) -> bool {
        self.is_unicast()
            && !self.is_loopback()
            && !self.is_unicast_link_local()
            && !self.is_unique_local()
            && !self.is_unspecified()
            && !self.is_documentation()
    }

    /// 如果该地址是多播的，则返回该地址的多播作用域。
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::{Ipv6Addr, Ipv6MulticastScope};
    ///
    /// assert_eq!(
    ///     Ipv6Addr::new(0xff0e, 0, 0, 0, 0, 0, 0, 0).multicast_scope(),
    ///     Some(Ipv6MulticastScope::Global)
    /// );
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).multicast_scope(), None);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn multicast_scope(&self) -> Option<Ipv6MulticastScope> {
        if self.is_multicast() {
            match self.segments()[0] & 0x000f {
                1 => Some(Ipv6MulticastScope::InterfaceLocal),
                2 => Some(Ipv6MulticastScope::LinkLocal),
                3 => Some(Ipv6MulticastScope::RealmLocal),
                4 => Some(Ipv6MulticastScope::AdminLocal),
                5 => Some(Ipv6MulticastScope::SiteLocal),
                8 => Some(Ipv6MulticastScope::OrganizationLocal),
                14 => Some(Ipv6MulticastScope::Global),
                _ => None,
            }
        } else {
            None
        }
    }

    /// 如果这是多播地址 (`ff00::/8`)，则返回 [`true`]。
    ///
    /// 此属性由 [IETF RFC 4291] 定义。
    ///
    /// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).is_multicast(), true);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_multicast(), false);
    /// ```
    #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
    #[stable(since = "1.7.0", feature = "ip_17")]
    #[inline]
    pub const fn is_multicast(&self) -> bool {
        (self.segments()[0] & 0xff00) == 0xff00
    }

    /// 如果它是 [IETF RFC 4291 section 2.5.5.2] 中定义的 "IPv4-mapped IPv6 address"，则将该地址转换为 [`IPv4` address]，否则返回 [`None`]。
    ///
    ///
    /// `::ffff:a.b.c.d` 变为 `a.b.c.d`。
    /// 所有非以 `::ffff` 开头的地址都将返回 `None`。
    ///
    /// [`IPv4` address]: Ipv4Addr
    /// [IETF RFC 4291 section 2.5.5.2]: https://tools.ietf.org/html/rfc4291#section-2.5.5.2
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ip)]
    ///
    /// use std::net::{Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).to_ipv4_mapped(), None);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).to_ipv4_mapped(),
    ///            Some(Ipv4Addr::new(192, 10, 2, 255)));
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4_mapped(), None);
    /// ```
    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
    #[unstable(feature = "ip", issue = "27709")]
    #[inline]
    pub const fn to_ipv4_mapped(&self) -> Option<Ipv4Addr> {
        match self.octets() {
            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, a, b, c, d] => {
                Some(Ipv4Addr::new(a, b, c, d))
            }
            _ => None,
        }
    }

    /// 将此地址转换为 [`IPv4` address]。
    /// 如果此地址既不是 IPv4 兼容的也不是 IPv4 映射的，则返回 [`None`]。
    ///
    /// `::a.b.c.d` `::ffff:a.b.c.d` 变成 `a.b.c.d`
    ///
    /// [`IPv4` address]: Ipv4Addr
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{Ipv4Addr, Ipv6Addr};
    ///
    /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).to_ipv4(), None);
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).to_ipv4(),
    ///            Some(Ipv4Addr::new(192, 10, 2, 255)));
    /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4(),
    ///            Some(Ipv4Addr::new(0, 0, 0, 1)));
    /// ```
    #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
    #[stable(feature = "rust1", since = "1.0.0")]
    #[inline]
    pub const fn to_ipv4(&self) -> Option<Ipv4Addr> {
        if let [0, 0, 0, 0, 0, 0 | 0xffff, ab, cd] = self.segments() {
            let [a, b] = ab.to_be_bytes();
            let [c, d] = cd.to_be_bytes();
            Some(Ipv4Addr::new(a, b, c, d))
        } else {
            None
        }
    }

    /// 返回 IPv6 地址组成的 16 个八位整数。
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).octets(),
    ///            [255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
    /// ```
    #[rustc_const_stable(feature = "const_ipv6", since = "1.32.0")]
    #[stable(feature = "ipv6_to_octets", since = "1.12.0")]
    #[inline]
    pub const fn octets(&self) -> [u8; 16] {
        self.inner.s6_addr
    }
}

/// 编写一个符合 [RFC 5952](https://tools.ietf.org/html/rfc5952) 描述的规范样式的 Ivv6Addr。
///
#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Display for Ipv6Addr {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // 如果没有对齐要求，则将 IP 地址写出到 f。
        // 否则，将其写入本地缓冲区，然后使用 f.pad。
        if f.precision().is_none() && f.width().is_none() {
            let segments = self.segments();

            // :: 和 ::1 的特殊情况; 否则，它们将使用 IPv4 格式化程序编写
            //
            if self.is_unspecified() {
                f.write_str("::")
            } else if self.is_loopback() {
                f.write_str("::1")
            } else if let Some(ipv4) = self.to_ipv4() {
                match segments[5] {
                    // IPv4 兼容地址
                    0 => write!(f, "::{}", ipv4),
                    // IPv4 对应的地址
                    0xffff => write!(f, "::ffff:{}", ipv4),
                    _ => unreachable!(),
                }
            } else {
                #[derive(Copy, Clone, Default)]
                struct Span {
                    start: usize,
                    len: usize,
                }

                // 找出内部 0 跨度
                let zeroes = {
                    let mut longest = Span::default();
                    let mut current = Span::default();

                    for (i, &segment) in segments.iter().enumerate() {
                        if segment == 0 {
                            if current.len == 0 {
                                current.start = i;
                            }

                            current.len += 1;

                            if current.len > longest.len {
                                longest = current;
                            }
                        } else {
                            current = Span::default();
                        }
                    }

                    longest
                };

                /// 写一个用冒号分隔的地址部分
                #[inline]
                fn fmt_subslice(f: &mut fmt::Formatter<'_>, chunk: &[u16]) -> fmt::Result {
                    if let Some((first, tail)) = chunk.split_first() {
                        write!(f, "{:x}", first)?;
                        for segment in tail {
                            f.write_char(':')?;
                            write!(f, "{:x}", segment)?;
                        }
                    }
                    Ok(())
                }

                if zeroes.len > 1 {
                    fmt_subslice(f, &segments[..zeroes.start])?;
                    f.write_str("::")?;
                    fmt_subslice(f, &segments[zeroes.start + zeroes.len..])
                } else {
                    fmt_subslice(f, &segments)
                }
            }
        } else {
            // 慢路径: 将地址写入本地缓冲区，使用 f.pad。
            // 通过使用快速路径来递归定义来写入缓冲区。
            //

            // 这是 IPv6 地址的最大可能大小
            const IPV6_BUF_LEN: usize = (4 * 8) + 7;
            let mut buf = [0u8; IPV6_BUF_LEN];
            let mut buf_slice = &mut buf[..];

            // Note: 这种调用应该永远不会失败，所以可以拆包。
            write!(buf_slice, "{}", self).unwrap();
            let len = IPV6_BUF_LEN - buf_slice.len();

            // 这是安全的，因为我们确切知道此缓冲区中可以包含的内容
            let buf = unsafe { crate::str::from_utf8_unchecked(&buf[..len]) };
            f.pad(buf)
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for Ipv6Addr {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(self, fmt)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Clone for Ipv6Addr {
    #[inline]
    fn clone(&self) -> Ipv6Addr {
        *self
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialEq for Ipv6Addr {
    #[inline]
    fn eq(&self, other: &Ipv6Addr) -> bool {
        self.inner.s6_addr == other.inner.s6_addr
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialEq<IpAddr> for Ipv6Addr {
    #[inline]
    fn eq(&self, other: &IpAddr) -> bool {
        match other {
            IpAddr::V4(_) => false,
            IpAddr::V6(v6) => self == v6,
        }
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialEq<Ipv6Addr> for IpAddr {
    #[inline]
    fn eq(&self, other: &Ipv6Addr) -> bool {
        match self {
            IpAddr::V4(_) => false,
            IpAddr::V6(v6) => v6 == other,
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Eq for Ipv6Addr {}

#[stable(feature = "rust1", since = "1.0.0")]
impl hash::Hash for Ipv6Addr {
    #[inline]
    fn hash<H: hash::Hasher>(&self, s: &mut H) {
        self.inner.s6_addr.hash(s)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for Ipv6Addr {
    #[inline]
    fn partial_cmp(&self, other: &Ipv6Addr) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialOrd<Ipv6Addr> for IpAddr {
    #[inline]
    fn partial_cmp(&self, other: &Ipv6Addr) -> Option<Ordering> {
        match self {
            IpAddr::V4(_) => Some(Ordering::Less),
            IpAddr::V6(v6) => v6.partial_cmp(other),
        }
    }
}

#[stable(feature = "ip_cmp", since = "1.16.0")]
impl PartialOrd<IpAddr> for Ipv6Addr {
    #[inline]
    fn partial_cmp(&self, other: &IpAddr) -> Option<Ordering> {
        match other {
            IpAddr::V4(_) => Some(Ordering::Greater),
            IpAddr::V6(v6) => self.partial_cmp(v6),
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for Ipv6Addr {
    #[inline]
    fn cmp(&self, other: &Ipv6Addr) -> Ordering {
        self.segments().cmp(&other.segments())
    }
}

impl AsInner<c::in6_addr> for Ipv6Addr {
    #[inline]
    fn as_inner(&self) -> &c::in6_addr {
        &self.inner
    }
}
impl FromInner<c::in6_addr> for Ipv6Addr {
    #[inline]
    fn from_inner(addr: c::in6_addr) -> Ipv6Addr {
        Ipv6Addr { inner: addr }
    }
}

#[stable(feature = "i128", since = "1.26.0")]
impl From<Ipv6Addr> for u128 {
    /// 将 `Ipv6Addr` 转换为主机字节顺序 `u128`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::new(
    ///     0x1020, 0x3040, 0x5060, 0x7080,
    ///     0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
    /// );
    /// assert_eq!(0x102030405060708090A0B0C0D0E0F00D_u128, u128::from(addr));
    /// ```
    #[inline]
    fn from(ip: Ipv6Addr) -> u128 {
        let ip = ip.octets();
        u128::from_be_bytes(ip)
    }
}
#[stable(feature = "i128", since = "1.26.0")]
impl From<u128> for Ipv6Addr {
    /// 将主机字节顺序 `u128` 转换为 `Ipv6Addr`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::from(0x102030405060708090A0B0C0D0E0F00D_u128);
    /// assert_eq!(
    ///     Ipv6Addr::new(
    ///         0x1020, 0x3040, 0x5060, 0x7080,
    ///         0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
    ///     ),
    ///     addr);
    /// ```
    #[inline]
    fn from(ip: u128) -> Ipv6Addr {
        Ipv6Addr::from(ip.to_be_bytes())
    }
}

#[stable(feature = "ipv6_from_octets", since = "1.9.0")]
impl From<[u8; 16]> for Ipv6Addr {
    /// 从 16 个元素的字节数组创建 `Ipv6Addr`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::from([
    ///     25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8,
    ///     17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8,
    /// ]);
    /// assert_eq!(
    ///     Ipv6Addr::new(
    ///         0x1918, 0x1716,
    ///         0x1514, 0x1312,
    ///         0x1110, 0x0f0e,
    ///         0x0d0c, 0x0b0a
    ///     ),
    ///     addr
    /// );
    /// ```
    #[inline]
    fn from(octets: [u8; 16]) -> Ipv6Addr {
        let inner = c::in6_addr { s6_addr: octets };
        Ipv6Addr::from_inner(inner)
    }
}

#[stable(feature = "ipv6_from_segments", since = "1.16.0")]
impl From<[u16; 8]> for Ipv6Addr {
    /// 从 8 个元素的 16 位数组创建 `Ipv6Addr`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::Ipv6Addr;
    ///
    /// let addr = Ipv6Addr::from([
    ///     525u16, 524u16, 523u16, 522u16,
    ///     521u16, 520u16, 519u16, 518u16,
    /// ]);
    /// assert_eq!(
    ///     Ipv6Addr::new(
    ///         0x20d, 0x20c,
    ///         0x20b, 0x20a,
    ///         0x209, 0x208,
    ///         0x207, 0x206
    ///     ),
    ///     addr
    /// );
    /// ```
    #[inline]
    fn from(segments: [u16; 8]) -> Ipv6Addr {
        let [a, b, c, d, e, f, g, h] = segments;
        Ipv6Addr::new(a, b, c, d, e, f, g, h)
    }
}

#[stable(feature = "ip_from_slice", since = "1.17.0")]
impl From<[u8; 16]> for IpAddr {
    /// 从 16 个元素的字节数组创建 `IpAddr::V6`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv6Addr};
    ///
    /// let addr = IpAddr::from([
    ///     25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8,
    ///     17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8,
    /// ]);
    /// assert_eq!(
    ///     IpAddr::V6(Ipv6Addr::new(
    ///         0x1918, 0x1716,
    ///         0x1514, 0x1312,
    ///         0x1110, 0x0f0e,
    ///         0x0d0c, 0x0b0a
    ///     )),
    ///     addr
    /// );
    /// ```
    #[inline]
    fn from(octets: [u8; 16]) -> IpAddr {
        IpAddr::V6(Ipv6Addr::from(octets))
    }
}

#[stable(feature = "ip_from_slice", since = "1.17.0")]
impl From<[u16; 8]> for IpAddr {
    /// 从 8 个元素的 16 位数组创建 `IpAddr::V6`。
    ///
    /// # Examples
    ///
    /// ```
    /// use std::net::{IpAddr, Ipv6Addr};
    ///
    /// let addr = IpAddr::from([
    ///     525u16, 524u16, 523u16, 522u16,
    ///     521u16, 520u16, 519u16, 518u16,
    /// ]);
    /// assert_eq!(
    ///     IpAddr::V6(Ipv6Addr::new(
    ///         0x20d, 0x20c,
    ///         0x20b, 0x20a,
    ///         0x209, 0x208,
    ///         0x207, 0x206
    ///     )),
    ///     addr
    /// );
    /// ```
    #[inline]
    fn from(segments: [u16; 8]) -> IpAddr {
        IpAddr::V6(Ipv6Addr::from(segments))
    }
}