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    //! An abstraction over platform-specific TLS implementations.
    //!
    //! Many applications require TLS/SSL communication in one form or another as
    //! part of their implementation, but finding a library for this isn't always
    //! trivial! The purpose of this crate is to provide a seamless integration
    //! experience on all platforms with a cross-platform API that deals with all
    //! the underlying details for you.
    //!
    //! # How is this implemented?
    //!
    //! This crate uses SChannel on Windows (via the `schannel` crate), Secure
    //! Transport on OSX (via the `security-framework` crate), and OpenSSL (via the
    //! `openssl` crate) on all other platforms. Future futures may also enable
    //! other TLS frameworks as well, but these initial libraries are likely to
    //! remain as the defaults.
    //!
    //! Note that this crate also strives to be secure-by-default. For example when
    //! using OpenSSL it will configure validation callbacks to ensure that
    //! hostnames match certificates, use strong ciphers, etc. This implies that
    //! this crate is *not* just a thin abstraction around the underlying libraries,
    //! but also an implementation that strives to strike reasonable defaults.
    //!
    //! # Supported features
    //!
    //! This crate supports the following features out of the box:
    //!
    //! * TLS/SSL client communication
    //! * TLS/SSL server communication
    //! * PKCS#12 encoded identities
    //! * Secure-by-default for client and server
    //!     * Includes hostname verification for clients
    //! * Supports asynchronous I/O for both the server and the client
    //!
    //! # Cargo Features
    //!
    //! * `vendored` - If enabled, the crate will compile and statically link to a
    //!     vendored copy of OpenSSL. This feature has no effect on Windows and
    //!     macOS, where OpenSSL is not used.
    //!
    //! # Examples
    //!
    //! To connect as a client to a remote server:
    //!
    //! ```rust
    //! use native_tls::TlsConnector;
    //! use std::io::{Read, Write};
    //! use std::net::TcpStream;
    //!
    //! let connector = TlsConnector::new().unwrap();
    //!
    //! let stream = TcpStream::connect("google.com:443").unwrap();
    //! let mut stream = connector.connect("google.com", stream).unwrap();
    //!
    //! stream.write_all(b"GET / HTTP/1.0\r\n\r\n").unwrap();
    //! let mut res = vec![];
    //! stream.read_to_end(&mut res).unwrap();
    //! println!("{}", String::from_utf8_lossy(&res));
    //! ```
    //!
    //! To accept connections as a server from remote clients:
    //!
    //! ```rust,no_run
    //! use native_tls::{Identity, TlsAcceptor, TlsStream};
    //! use std::fs::File;
    //! use std::io::{Read};
    //! use std::net::{TcpListener, TcpStream};
    //! use std::sync::Arc;
    //! use std::thread;
    //!
    //! let mut file = File::open("identity.pfx").unwrap();
    //! let mut identity = vec![];
    //! file.read_to_end(&mut identity).unwrap();
    //! let identity = Identity::from_pkcs12(&identity, "hunter2").unwrap();
    //!
    //! let listener = TcpListener::bind("0.0.0.0:8443").unwrap();
    //! let acceptor = TlsAcceptor::new(identity).unwrap();
    //! let acceptor = Arc::new(acceptor);
    //!
    //! fn handle_client(stream: TlsStream<TcpStream>) {
    //!     // ...
    //! }
    //!
    //! for stream in listener.incoming() {
    //!     match stream {
    //!         Ok(stream) => {
    //!             let acceptor = acceptor.clone();
    //!             thread::spawn(move || {
    //!                 let stream = acceptor.accept(stream).unwrap();
    //!                 handle_client(stream);
    //!             });
    //!         }
    //!         Err(e) => { /* connection failed */ }
    //!     }
    //! }
    //! ```
    #![doc(html_root_url = "https://docs.rs/native-tls/0.2")]
    #![warn(missing_docs)]
    #![cfg_attr(docsrs, feature(doc_cfg))]

    #[macro_use]
    #[cfg(any(target_os = "macos", target_os = "ios"))]
    extern crate lazy_static;

    use std::any::Any;
    use std::error;
    use std::fmt;
    use std::io;
    use std::result;

    #[cfg(not(any(target_os = "macos", target_os = "windows", target_os = "ios")))]
    #[macro_use]
    extern crate log;
    #[cfg(any(target_os = "macos", target_os = "ios"))]
    #[path = "imp/security_framework.rs"]
    mod imp;
    #[cfg(target_os = "windows")]
    #[path = "imp/schannel.rs"]
    mod imp;
    #[cfg(not(any(target_os = "macos", target_os = "windows", target_os = "ios")))]
    #[path = "imp/openssl.rs"]
    mod imp;

    #[cfg(test)]
    mod test;

    /// A typedef of the result-type returned by many methods.
    pub type Result<T> = result::Result<T, Error>;

    /// An error returned from the TLS implementation.
    pub struct Error(imp::Error);

    impl error::Error for Error {
        fn source(&self) -> Option<&(dyn error::Error + 'static)> {
            error::Error::source(&self.0)
        }
    }

    impl fmt::Display for Error {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            fmt::Display::fmt(&self.0, fmt)
        }
    }

    impl fmt::Debug for Error {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            fmt::Debug::fmt(&self.0, fmt)
        }
    }

    impl From<imp::Error> for Error {
        fn from(err: imp::Error) -> Error {
            Error(err)
        }
    }

    /// A cryptographic identity.
    ///
    /// An identity is an X509 certificate along with its corresponding private key and chain of certificates to a trusted
    /// root.
    #[derive(Clone)]
    pub struct Identity(imp::Identity);

    impl Identity {
        /// Parses a DER-formatted PKCS #12 archive, using the specified password to decrypt the key.
        ///
        /// The archive should contain a leaf certificate and its private key, as well any intermediate
        /// certificates that should be sent to clients to allow them to build a chain to a trusted
        /// root. The chain certificates should be in order from the leaf certificate towards the root.
        ///
        /// PKCS #12 archives typically have the file extension `.p12` or `.pfx`, and can be created
        /// with the OpenSSL `pkcs12` tool:
        ///
        /// ```bash
        /// openssl pkcs12 -export -out identity.pfx -inkey key.pem -in cert.pem -certfile chain_certs.pem
        /// ```
        pub fn from_pkcs12(der: &[u8], password: &str) -> Result<Identity> {
            let identity = imp::Identity::from_pkcs12(der, password)?;
            Ok(Identity(identity))
        }
    }

    /// An X509 certificate.
    #[derive(Clone)]
    pub struct Certificate(imp::Certificate);

    impl Certificate {
        /// Parses a DER-formatted X509 certificate.
        pub fn from_der(der: &[u8]) -> Result<Certificate> {
            let cert = imp::Certificate::from_der(der)?;
            Ok(Certificate(cert))
        }

        /// Parses a PEM-formatted X509 certificate.
        pub fn from_pem(pem: &[u8]) -> Result<Certificate> {
            let cert = imp::Certificate::from_pem(pem)?;
            Ok(Certificate(cert))
        }

        /// Returns the DER-encoded representation of this certificate.
        pub fn to_der(&self) -> Result<Vec<u8>> {
            let der = self.0.to_der()?;
            Ok(der)
        }
    }

    /// A TLS stream which has been interrupted midway through the handshake process.
    pub struct MidHandshakeTlsStream<S>(imp::MidHandshakeTlsStream<S>);

    impl<S> fmt::Debug for MidHandshakeTlsStream<S>
    where
        S: fmt::Debug,
    {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            fmt::Debug::fmt(&self.0, fmt)
        }
    }

    impl<S> MidHandshakeTlsStream<S> {
        /// Returns a shared reference to the inner stream.
        pub fn get_ref(&self) -> &S {
            self.0.get_ref()
        }

        /// Returns a mutable reference to the inner stream.
        pub fn get_mut(&mut self) -> &mut S {
            self.0.get_mut()
        }
    }

    impl<S> MidHandshakeTlsStream<S>
    where
        S: io::Read + io::Write,
    {
        /// Restarts the handshake process.
        ///
        /// If the handshake completes successfully then the negotiated stream is
        /// returned. If there is a problem, however, then an error is returned.
        /// Note that the error may not be fatal. For example if the underlying
        /// stream is an asynchronous one then `HandshakeError::WouldBlock` may
        /// just mean to wait for more I/O to happen later.
        pub fn handshake(self) -> result::Result<TlsStream<S>, HandshakeError<S>> {
            match self.0.handshake() {
                Ok(s) => Ok(TlsStream(s)),
                Err(e) => Err(e.into()),
            }
        }
    }

    /// An error returned from `ClientBuilder::handshake`.
    #[derive(Debug)]
    pub enum HandshakeError<S> {
        /// A fatal error.
        Failure(Error),

        /// A stream interrupted midway through the handshake process due to a
        /// `WouldBlock` error.
        ///
        /// Note that this is not a fatal error and it should be safe to call
        /// `handshake` at a later time once the stream is ready to perform I/O
        /// again.
        WouldBlock(MidHandshakeTlsStream<S>),
    }

    impl<S> error::Error for HandshakeError<S>
    where
        S: Any + fmt::Debug,
    {
        fn source(&self) -> Option<&(dyn error::Error + 'static)> {
            match *self {
                HandshakeError::Failure(ref e) => Some(e),
                HandshakeError::WouldBlock(_) => None,
            }
        }
    }

    impl<S> fmt::Display for HandshakeError<S>
    where
        S: Any + fmt::Debug,
    {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            match *self {
                HandshakeError::Failure(ref e) => fmt::Display::fmt(e, fmt),
                HandshakeError::WouldBlock(_) => fmt.write_str("the handshake process was interrupted"),
            }
        }
    }

    impl<S> From<imp::HandshakeError<S>> for HandshakeError<S> {
        fn from(e: imp::HandshakeError<S>) -> HandshakeError<S> {
            match e {
                imp::HandshakeError::Failure(e) => HandshakeError::Failure(Error(e)),
                imp::HandshakeError::WouldBlock(s) => {
                    HandshakeError::WouldBlock(MidHandshakeTlsStream(s))
                }
            }
        }
    }

    /// SSL/TLS protocol versions.
    #[derive(Debug, Copy, Clone)]
    pub enum Protocol {
        /// The SSL 3.0 protocol.
        ///
        /// # Warning
        ///
        /// SSL 3.0 has severe security flaws, and should not be used unless absolutely necessary. If
        /// you are not sure if you need to enable this protocol, you should not.
        Sslv3,
        /// The TLS 1.0 protocol.
        Tlsv10,
        /// The TLS 1.1 protocol.
        Tlsv11,
        /// The TLS 1.2 protocol.
        Tlsv12,
        #[doc(hidden)]
        __NonExhaustive,
    }

    /// A builder for `TlsConnector`s.
    pub struct TlsConnectorBuilder {
        identity: Option<Identity>,
        min_protocol: Option<Protocol>,
        max_protocol: Option<Protocol>,
        root_certificates: Vec<Certificate>,
        accept_invalid_certs: bool,
        accept_invalid_hostnames: bool,
        use_sni: bool,
        disable_built_in_roots: bool,
        #[cfg(feature = "alpn")]
        alpn: Vec<String>,
    }

    impl TlsConnectorBuilder {
        /// Sets the identity to be used for client certificate authentication.
        pub fn identity(&mut self, identity: Identity) -> &mut TlsConnectorBuilder {
            self.identity = Some(identity);
            self
        }

        /// Sets the minimum supported protocol version.
        ///
        /// A value of `None` enables support for the oldest protocols supported by the implementation.
        ///
        /// Defaults to `Some(Protocol::Tlsv10)`.
        pub fn min_protocol_version(&mut self, protocol: Option<Protocol>) -> &mut TlsConnectorBuilder {
            self.min_protocol = protocol;
            self
        }

        /// Sets the maximum supported protocol version.
        ///
        /// A value of `None` enables support for the newest protocols supported by the implementation.
        ///
        /// Defaults to `None`.
        pub fn max_protocol_version(&mut self, protocol: Option<Protocol>) -> &mut TlsConnectorBuilder {
            self.max_protocol = protocol;
            self
        }

        /// Adds a certificate to the set of roots that the connector will trust.
        ///
        /// The connector will use the system's trust root by default. This method can be used to add
        /// to that set when communicating with servers not trusted by the system.
        ///
        /// Defaults to an empty set.
        pub fn add_root_certificate(&mut self, cert: Certificate) -> &mut TlsConnectorBuilder {
            self.root_certificates.push(cert);
            self
        }

        /// Controls the use of built-in system certificates during certificate validation.
        ///
        /// Defaults to `false` -- built-in system certs will be used.
        pub fn disable_built_in_roots(&mut self, disable: bool) -> &mut TlsConnectorBuilder {
            self.disable_built_in_roots = disable;
            self
        }

        /// Request specific protocols through ALPN (Application-Layer Protocol Negotiation).
        ///
        /// Defaults to no protocols.
        #[cfg(feature = "alpn")]
        #[cfg_attr(docsrs, doc(cfg(feature = "alpn")))]
        pub fn request_alpns(&mut self, protocols: &[&str]) -> &mut TlsConnectorBuilder {
            self.alpn = protocols.iter().map(|s| (*s).to_owned()).collect();
            self
        }

        /// Controls the use of certificate validation.
        ///
        /// Defaults to `false`.
        ///
        /// # Warning
        ///
        /// You should think very carefully before using this method. If invalid certificates are trusted, *any*
        /// certificate for *any* site will be trusted for use. This includes expired certificates. This introduces
        /// significant vulnerabilities, and should only be used as a last resort.
        pub fn danger_accept_invalid_certs(
            &mut self,
            accept_invalid_certs: bool,
        ) -> &mut TlsConnectorBuilder {
            self.accept_invalid_certs = accept_invalid_certs;
            self
        }

        /// Controls the use of Server Name Indication (SNI).
        ///
        /// Defaults to `true`.
        pub fn use_sni(&mut self, use_sni: bool) -> &mut TlsConnectorBuilder {
            self.use_sni = use_sni;
            self
        }

        /// Controls the use of hostname verification.
        ///
        /// Defaults to `false`.
        ///
        /// # Warning
        ///
        /// You should think very carefully before using this method. If invalid hostnames are trusted, *any* valid
        /// certificate for *any* site will be trusted for use. This introduces significant vulnerabilities, and should
        /// only be used as a last resort.
        pub fn danger_accept_invalid_hostnames(
            &mut self,
            accept_invalid_hostnames: bool,
        ) -> &mut TlsConnectorBuilder {
            self.accept_invalid_hostnames = accept_invalid_hostnames;
            self
        }

        /// Creates a new `TlsConnector`.
        pub fn build(&self) -> Result<TlsConnector> {
            let connector = imp::TlsConnector::new(self)?;
            Ok(TlsConnector(connector))
        }
    }

    /// A builder for client-side TLS connections.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use native_tls::TlsConnector;
    /// use std::io::{Read, Write};
    /// use std::net::TcpStream;
    ///
    /// let connector = TlsConnector::new().unwrap();
    ///
    /// let stream = TcpStream::connect("google.com:443").unwrap();
    /// let mut stream = connector.connect("google.com", stream).unwrap();
    ///
    /// stream.write_all(b"GET / HTTP/1.0\r\n\r\n").unwrap();
    /// let mut res = vec![];
    /// stream.read_to_end(&mut res).unwrap();
    /// println!("{}", String::from_utf8_lossy(&res));
    /// ```
    #[derive(Clone, Debug)]
    pub struct TlsConnector(imp::TlsConnector);

    impl TlsConnector {
        /// Returns a new connector with default settings.
        pub fn new() -> Result<TlsConnector> {
            TlsConnector::builder().build()
        }

        /// Returns a new builder for a `TlsConnector`.
        pub fn builder() -> TlsConnectorBuilder {
            TlsConnectorBuilder {
                identity: None,
                min_protocol: Some(Protocol::Tlsv10),
                max_protocol: None,
                root_certificates: vec![],
                use_sni: true,
                accept_invalid_certs: false,
                accept_invalid_hostnames: false,
                disable_built_in_roots: false,
                #[cfg(feature = "alpn")]
                alpn: vec![],
            }
        }

        /// Initiates a TLS handshake.
        ///
        /// The provided domain will be used for both SNI and certificate hostname
        /// validation.
        ///
        /// If the socket is nonblocking and a `WouldBlock` error is returned during
        /// the handshake, a `HandshakeError::WouldBlock` error will be returned
        /// which can be used to restart the handshake when the socket is ready
        /// again.
        ///
        /// The domain is ignored if both SNI and hostname verification are
        /// disabled.
        pub fn connect<S>(
            &self,
            domain: &str,
            stream: S,
        ) -> result::Result<TlsStream<S>, HandshakeError<S>>
        where
            S: io::Read + io::Write,
        {
            let s = self.0.connect(domain, stream)?;
            Ok(TlsStream(s))
        }
    }

    /// A builder for `TlsAcceptor`s.
    pub struct TlsAcceptorBuilder {
        identity: Identity,
        min_protocol: Option<Protocol>,
        max_protocol: Option<Protocol>,
    }

    impl TlsAcceptorBuilder {
        /// Sets the minimum supported protocol version.
        ///
        /// A value of `None` enables support for the oldest protocols supported by the implementation.
        ///
        /// Defaults to `Some(Protocol::Tlsv10)`.
        pub fn min_protocol_version(&mut self, protocol: Option<Protocol>) -> &mut TlsAcceptorBuilder {
            self.min_protocol = protocol;
            self
        }

        /// Sets the maximum supported protocol version.
        ///
        /// A value of `None` enables support for the newest protocols supported by the implementation.
        ///
        /// Defaults to `None`.
        pub fn max_protocol_version(&mut self, protocol: Option<Protocol>) -> &mut TlsAcceptorBuilder {
            self.max_protocol = protocol;
            self
        }

        /// Creates a new `TlsAcceptor`.
        pub fn build(&self) -> Result<TlsAcceptor> {
            let acceptor = imp::TlsAcceptor::new(self)?;
            Ok(TlsAcceptor(acceptor))
        }
    }

    /// A builder for server-side TLS connections.
    ///
    /// # Examples
    ///
    /// ```rust,no_run
    /// use native_tls::{Identity, TlsAcceptor, TlsStream};
    /// use std::fs::File;
    /// use std::io::{Read};
    /// use std::net::{TcpListener, TcpStream};
    /// use std::sync::Arc;
    /// use std::thread;
    ///
    /// let mut file = File::open("identity.pfx").unwrap();
    /// let mut identity = vec![];
    /// file.read_to_end(&mut identity).unwrap();
    /// let identity = Identity::from_pkcs12(&identity, "hunter2").unwrap();
    ///
    /// let listener = TcpListener::bind("0.0.0.0:8443").unwrap();
    /// let acceptor = TlsAcceptor::new(identity).unwrap();
    /// let acceptor = Arc::new(acceptor);
    ///
    /// fn handle_client(stream: TlsStream<TcpStream>) {
    ///     // ...
    /// }
    ///
    /// for stream in listener.incoming() {
    ///     match stream {
    ///         Ok(stream) => {
    ///             let acceptor = acceptor.clone();
    ///             thread::spawn(move || {
    ///                 let stream = acceptor.accept(stream).unwrap();
    ///                 handle_client(stream);
    ///             });
    ///         }
    ///         Err(e) => { /* connection failed */ }
    ///     }
    /// }
    /// ```
    #[derive(Clone)]
    pub struct TlsAcceptor(imp::TlsAcceptor);

    impl TlsAcceptor {
        /// Creates a acceptor with default settings.
        ///
        /// The identity acts as the server's private key/certificate chain.
        pub fn new(identity: Identity) -> Result<TlsAcceptor> {
            TlsAcceptor::builder(identity).build()
        }

        /// Returns a new builder for a `TlsAcceptor`.
        ///
        /// The identity acts as the server's private key/certificate chain.
        pub fn builder(identity: Identity) -> TlsAcceptorBuilder {
            TlsAcceptorBuilder {
                identity,
                min_protocol: Some(Protocol::Tlsv10),
                max_protocol: None,
            }
        }

        /// Initiates a TLS handshake.
        ///
        /// If the socket is nonblocking and a `WouldBlock` error is returned during
        /// the handshake, a `HandshakeError::WouldBlock` error will be returned
        /// which can be used to restart the handshake when the socket is ready
        /// again.
        pub fn accept<S>(&self, stream: S) -> result::Result<TlsStream<S>, HandshakeError<S>>
        where
            S: io::Read + io::Write,
        {
            match self.0.accept(stream) {
                Ok(s) => Ok(TlsStream(s)),
                Err(e) => Err(e.into()),
            }
        }
    }

    /// A stream managing a TLS session.
    pub struct TlsStream<S>(imp::TlsStream<S>);

    impl<S: fmt::Debug> fmt::Debug for TlsStream<S> {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            fmt::Debug::fmt(&self.0, fmt)
        }
    }

    impl<S> TlsStream<S> {
        /// Returns a shared reference to the inner stream.
        pub fn get_ref(&self) -> &S {
            self.0.get_ref()
        }

        /// Returns a mutable reference to the inner stream.
        pub fn get_mut(&mut self) -> &mut S {
            self.0.get_mut()
        }
    }

    impl<S: io::Read + io::Write> TlsStream<S> {
        /// Returns the number of bytes that can be read without resulting in any
        /// network calls.
        pub fn buffered_read_size(&self) -> Result<usize> {
            Ok(self.0.buffered_read_size()?)
        }

        /// Returns the peer's leaf certificate, if available.
        pub fn peer_certificate(&self) -> Result<Option<Certificate>> {
            Ok(self.0.peer_certificate()?.map(Certificate))
        }

        /// Returns the tls-server-end-point channel binding data as defined in [RFC 5929].
        ///
        /// [RFC 5929]: https://tools.ietf.org/html/rfc5929
        pub fn tls_server_end_point(&self) -> Result<Option<Vec<u8>>> {
            Ok(self.0.tls_server_end_point()?)
        }

        /// Returns the negotiated ALPN protocol.
        #[cfg(feature = "alpn")]
        #[cfg_attr(docsrs, doc(cfg(feature = "alpn")))]
        pub fn negotiated_alpn(&self) -> Result<Option<Vec<u8>>> {
            Ok(self.0.negotiated_alpn()?)
        }

        /// Shuts down the TLS session.
        pub fn shutdown(&mut self) -> io::Result<()> {
            self.0.shutdown()?;
            Ok(())
        }
    }

    impl<S: io::Read + io::Write> io::Read for TlsStream<S> {
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.0.read(buf)
        }
    }

    impl<S: io::Read + io::Write> io::Write for TlsStream<S> {
        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
            self.0.write(buf)
        }

        fn flush(&mut self) -> io::Result<()> {
            self.0.flush()
        }
    }

    fn _check_kinds() {
        use std::net::TcpStream;

        fn is_sync<T: Sync>() {}
        fn is_send<T: Send>() {}
        is_sync::<Error>();
        is_send::<Error>();
        is_sync::<TlsConnectorBuilder>();
        is_send::<TlsConnectorBuilder>();
        is_sync::<TlsConnector>();
        is_send::<TlsConnector>();
        is_sync::<TlsAcceptorBuilder>();
        is_send::<TlsAcceptorBuilder>();
        is_sync::<TlsAcceptor>();
        is_send::<TlsAcceptor>();
        is_sync::<TlsStream<TcpStream>>();
        is_send::<TlsStream<TcpStream>>();
        is_sync::<MidHandshakeTlsStream<TcpStream>>();
        is_send::<MidHandshakeTlsStream<TcpStream>>();
    }