Merging upstream version 1.70.0+dfsg2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4131 insertions, 0 deletions

diff --git a/vendor/openssl/src/ssl/mod.rs b/vendor/openssl/src/ssl/mod.rs
new file mode 100644
index 000000000..6ef356d36
--- /dev/null
+++ b/vendor/openssl/src/ssl/mod.rs
@@ -0,0 +1,4131 @@
+//! SSL/TLS support.
+//!
+//! `SslConnector` and `SslAcceptor` should be used in most cases - they handle
+//! configuration of the OpenSSL primitives for you.
+//!
+//! # Examples
+//!
+//! To connect as a client to a remote server:
+//!
+//! ```no_run
+//! use openssl::ssl::{SslMethod, SslConnector};
+//! use std::io::{Read, Write};
+//! use std::net::TcpStream;
+//!
+//! let connector = SslConnector::builder(SslMethod::tls()).unwrap().build();
+//!
+//! 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:
+//!
+//! ```no_run
+//! use openssl::ssl::{SslMethod, SslAcceptor, SslStream, SslFiletype};
+//! use std::net::{TcpListener, TcpStream};
+//! use std::sync::Arc;
+//! use std::thread;
+//!
+//!
+//! let mut acceptor = SslAcceptor::mozilla_intermediate(SslMethod::tls()).unwrap();
+//! acceptor.set_private_key_file("key.pem", SslFiletype::PEM).unwrap();
+//! acceptor.set_certificate_chain_file("certs.pem").unwrap();
+//! acceptor.check_private_key().unwrap();
+//! let acceptor = Arc::new(acceptor.build());
+//!
+//! let listener = TcpListener::bind("0.0.0.0:8443").unwrap();
+//!
+//! fn handle_client(stream: SslStream<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 */ }
+//!     }
+//! }
+//! ```
+use crate::dh::{Dh, DhRef};
+#[cfg(all(ossl101, not(ossl110)))]
+use crate::ec::EcKey;
+use crate::ec::EcKeyRef;
+use crate::error::ErrorStack;
+use crate::ex_data::Index;
+#[cfg(ossl111)]
+use crate::hash::MessageDigest;
+#[cfg(any(ossl110, libressl270))]
+use crate::nid::Nid;
+use crate::pkey::{HasPrivate, PKeyRef, Params, Private};
+use crate::srtp::{SrtpProtectionProfile, SrtpProtectionProfileRef};
+use crate::ssl::bio::BioMethod;
+use crate::ssl::callbacks::*;
+use crate::ssl::error::InnerError;
+use crate::stack::{Stack, StackRef};
+use crate::util::{ForeignTypeExt, ForeignTypeRefExt};
+use crate::x509::store::{X509Store, X509StoreBuilderRef, X509StoreRef};
+#[cfg(any(ossl102, libressl261))]
+use crate::x509::verify::X509VerifyParamRef;
+use crate::x509::{X509Name, X509Ref, X509StoreContextRef, X509VerifyResult, X509};
+use crate::{cvt, cvt_n, cvt_p, init};
+use bitflags::bitflags;
+use cfg_if::cfg_if;
+use foreign_types::{ForeignType, ForeignTypeRef, Opaque};
+use libc::{c_char, c_int, c_long, c_uchar, c_uint, c_void};
+use once_cell::sync::{Lazy, OnceCell};
+use openssl_macros::corresponds;
+use std::any::TypeId;
+use std::cmp;
+use std::collections::HashMap;
+use std::ffi::{CStr, CString};
+use std::fmt;
+use std::io;
+use std::io::prelude::*;
+use std::marker::PhantomData;
+use std::mem::{self, ManuallyDrop};
+use std::ops::{Deref, DerefMut};
+use std::panic::resume_unwind;
+use std::path::Path;
+use std::ptr;
+use std::slice;
+use std::str;
+use std::sync::{Arc, Mutex};
+
+pub use crate::ssl::connector::{
+    ConnectConfiguration, SslAcceptor, SslAcceptorBuilder, SslConnector, SslConnectorBuilder,
+};
+pub use crate::ssl::error::{Error, ErrorCode, HandshakeError};
+
+mod bio;
+mod callbacks;
+mod connector;
+mod error;
+#[cfg(test)]
+mod test;
+
+/// Returns the OpenSSL name of a cipher corresponding to an RFC-standard cipher name.
+///
+/// If the cipher has no corresponding OpenSSL name, the string `(NONE)` is returned.
+///
+/// Requires OpenSSL 1.1.1 or newer.
+#[corresponds(OPENSSL_cipher_name)]
+#[cfg(ossl111)]
+pub fn cipher_name(std_name: &str) -> &'static str {
+    unsafe {
+        ffi::init();
+
+        let s = CString::new(std_name).unwrap();
+        let ptr = ffi::OPENSSL_cipher_name(s.as_ptr());
+        CStr::from_ptr(ptr).to_str().unwrap()
+    }
+}
+
+cfg_if! {
+    if #[cfg(ossl300)] {
+        type SslOptionsRepr = u64;
+    } else if #[cfg(boringssl)] {
+        type SslOptionsRepr = u32;
+    } else {
+        type SslOptionsRepr = libc::c_ulong;
+    }
+}
+
+bitflags! {
+    /// Options controlling the behavior of an `SslContext`.
+    pub struct SslOptions: SslOptionsRepr {
+        /// Disables a countermeasure against an SSLv3/TLSv1.0 vulnerability affecting CBC ciphers.
+        const DONT_INSERT_EMPTY_FRAGMENTS = ffi::SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS as SslOptionsRepr;
+
+        /// A "reasonable default" set of options which enables compatibility flags.
+        #[cfg(not(boringssl))]
+        const ALL = ffi::SSL_OP_ALL as SslOptionsRepr;
+
+        /// Do not query the MTU.
+        ///
+        /// Only affects DTLS connections.
+        const NO_QUERY_MTU = ffi::SSL_OP_NO_QUERY_MTU as SslOptionsRepr;
+
+        /// Enables Cookie Exchange as described in [RFC 4347 Section 4.2.1].
+        ///
+        /// Only affects DTLS connections.
+        ///
+        /// [RFC 4347 Section 4.2.1]: https://tools.ietf.org/html/rfc4347#section-4.2.1
+        #[cfg(not(boringssl))]
+        const COOKIE_EXCHANGE = ffi::SSL_OP_COOKIE_EXCHANGE as SslOptionsRepr;
+
+        /// Disables the use of session tickets for session resumption.
+        const NO_TICKET = ffi::SSL_OP_NO_TICKET as SslOptionsRepr;
+
+        /// Always start a new session when performing a renegotiation on the server side.
+        #[cfg(not(boringssl))]
+        const NO_SESSION_RESUMPTION_ON_RENEGOTIATION =
+            ffi::SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION as SslOptionsRepr;
+
+        /// Disables the use of TLS compression.
+        #[cfg(not(boringssl))]
+        const NO_COMPRESSION = ffi::SSL_OP_NO_COMPRESSION as SslOptionsRepr;
+
+        /// Allow legacy insecure renegotiation with servers or clients that do not support secure
+        /// renegotiation.
+        const ALLOW_UNSAFE_LEGACY_RENEGOTIATION =
+            ffi::SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION as SslOptionsRepr;
+
+        /// Creates a new key for each session when using ECDHE.
+        ///
+        /// This is always enabled in OpenSSL 1.1.0.
+        const SINGLE_ECDH_USE = ffi::SSL_OP_SINGLE_ECDH_USE as SslOptionsRepr;
+
+        /// Creates a new key for each session when using DHE.
+        ///
+        /// This is always enabled in OpenSSL 1.1.0.
+        const SINGLE_DH_USE = ffi::SSL_OP_SINGLE_DH_USE as SslOptionsRepr;
+
+        /// Use the server's preferences rather than the client's when selecting a cipher.
+        ///
+        /// This has no effect on the client side.
+        const CIPHER_SERVER_PREFERENCE = ffi::SSL_OP_CIPHER_SERVER_PREFERENCE as SslOptionsRepr;
+
+        /// Disables version rollback attach detection.
+        const TLS_ROLLBACK_BUG = ffi::SSL_OP_TLS_ROLLBACK_BUG as SslOptionsRepr;
+
+        /// Disables the use of SSLv2.
+        const NO_SSLV2 = ffi::SSL_OP_NO_SSLv2 as SslOptionsRepr;
+
+        /// Disables the use of SSLv3.
+        const NO_SSLV3 = ffi::SSL_OP_NO_SSLv3 as SslOptionsRepr;
+
+        /// Disables the use of TLSv1.0.
+        const NO_TLSV1 = ffi::SSL_OP_NO_TLSv1 as SslOptionsRepr;
+
+        /// Disables the use of TLSv1.1.
+        const NO_TLSV1_1 = ffi::SSL_OP_NO_TLSv1_1 as SslOptionsRepr;
+
+        /// Disables the use of TLSv1.2.
+        const NO_TLSV1_2 = ffi::SSL_OP_NO_TLSv1_2 as SslOptionsRepr;
+
+        /// Disables the use of TLSv1.3.
+        ///
+        /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+        #[cfg(any(boringssl, ossl111, libressl340))]
+        const NO_TLSV1_3 = ffi::SSL_OP_NO_TLSv1_3 as SslOptionsRepr;
+
+        /// Disables the use of DTLSv1.0
+        ///
+        /// Requires OpenSSL 1.0.2 or LibreSSL 3.3.2 or newer.
+        #[cfg(any(boringssl, ossl102, ossl110, libressl332))]
+        const NO_DTLSV1 = ffi::SSL_OP_NO_DTLSv1 as SslOptionsRepr;
+
+        /// Disables the use of DTLSv1.2.
+        ///
+        /// Requires OpenSSL 1.0.2 or LibreSSL 3.3.2 or newer.
+        #[cfg(any(boringssl, ossl102, ossl110, libressl332))]
+        const NO_DTLSV1_2 = ffi::SSL_OP_NO_DTLSv1_2 as SslOptionsRepr;
+
+        /// Disables the use of all (D)TLS protocol versions.
+        ///
+        /// This can be used as a mask when whitelisting protocol versions.
+        ///
+        /// Requires OpenSSL 1.0.2 or newer.
+        ///
+        /// # Examples
+        ///
+        /// Only support TLSv1.2:
+        ///
+        /// ```rust
+        /// use openssl::ssl::SslOptions;
+        ///
+        /// let options = SslOptions::NO_SSL_MASK & !SslOptions::NO_TLSV1_2;
+        /// ```
+        #[cfg(any(ossl102, ossl110))]
+        const NO_SSL_MASK = ffi::SSL_OP_NO_SSL_MASK as SslOptionsRepr;
+
+        /// Disallow all renegotiation in TLSv1.2 and earlier.
+        ///
+        /// Requires OpenSSL 1.1.0h or newer.
+        #[cfg(any(boringssl, ossl110h))]
+        const NO_RENEGOTIATION = ffi::SSL_OP_NO_RENEGOTIATION as SslOptionsRepr;
+
+        /// Enable TLSv1.3 Compatibility mode.
+        ///
+        /// Requires OpenSSL 1.1.1 or newer. This is on by default in 1.1.1, but a future version
+        /// may have this disabled by default.
+        #[cfg(ossl111)]
+        const ENABLE_MIDDLEBOX_COMPAT = ffi::SSL_OP_ENABLE_MIDDLEBOX_COMPAT as SslOptionsRepr;
+
+        /// Prioritize ChaCha ciphers when preferred by clients.
+        ///
+        /// Temporarily reprioritize ChaCha20-Poly1305 ciphers to the top of the server cipher list
+        /// if a ChaCha20-Poly1305 cipher is at the top of the client cipher list. This helps those
+        /// clients (e.g. mobile) use ChaCha20-Poly1305 if that cipher is anywhere in the server
+        /// cipher list; but still allows other clients to use AES and other ciphers.
+        ///
+        /// Requires enable [`SslOptions::CIPHER_SERVER_PREFERENCE`].
+        /// Requires OpenSSL 1.1.1 or newer.
+        ///
+        /// [`SslOptions::CIPHER_SERVER_PREFERENCE`]: struct.SslOptions.html#associatedconstant.CIPHER_SERVER_PREFERENCE
+        #[cfg(ossl111)]
+        const PRIORITIZE_CHACHA = ffi::SSL_OP_PRIORITIZE_CHACHA as SslOptionsRepr;
+    }
+}
+
+bitflags! {
+    /// Options controlling the behavior of an `SslContext`.
+    pub struct SslMode: SslBitType {
+        /// Enables "short writes".
+        ///
+        /// Normally, a write in OpenSSL will always write out all of the requested data, even if it
+        /// requires more than one TLS record or write to the underlying stream. This option will
+        /// cause a write to return after writing a single TLS record instead.
+        const ENABLE_PARTIAL_WRITE = ffi::SSL_MODE_ENABLE_PARTIAL_WRITE;
+
+        /// Disables a check that the data buffer has not moved between calls when operating in a
+        /// non-blocking context.
+        const ACCEPT_MOVING_WRITE_BUFFER = ffi::SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER;
+
+        /// Enables automatic retries after TLS session events such as renegotiations or heartbeats.
+        ///
+        /// By default, OpenSSL will return a `WantRead` error after a renegotiation or heartbeat.
+        /// This option will cause OpenSSL to automatically continue processing the requested
+        /// operation instead.
+        ///
+        /// Note that `SslStream::read` and `SslStream::write` will automatically retry regardless
+        /// of the state of this option. It only affects `SslStream::ssl_read` and
+        /// `SslStream::ssl_write`.
+        const AUTO_RETRY = ffi::SSL_MODE_AUTO_RETRY;
+
+        /// Disables automatic chain building when verifying a peer's certificate.
+        ///
+        /// TLS peers are responsible for sending the entire certificate chain from the leaf to a
+        /// trusted root, but some will incorrectly not do so. OpenSSL will try to build the chain
+        /// out of certificates it knows of, and this option will disable that behavior.
+        const NO_AUTO_CHAIN = ffi::SSL_MODE_NO_AUTO_CHAIN;
+
+        /// Release memory buffers when the session does not need them.
+        ///
+        /// This saves ~34 KiB of memory for idle streams.
+        const RELEASE_BUFFERS = ffi::SSL_MODE_RELEASE_BUFFERS;
+
+        /// Sends the fake `TLS_FALLBACK_SCSV` cipher suite in the ClientHello message of a
+        /// handshake.
+        ///
+        /// This should only be enabled if a client has failed to connect to a server which
+        /// attempted to downgrade the protocol version of the session.
+        ///
+        /// Do not use this unless you know what you're doing!
+        #[cfg(not(libressl))]
+        const SEND_FALLBACK_SCSV = ffi::SSL_MODE_SEND_FALLBACK_SCSV;
+    }
+}
+
+/// A type specifying the kind of protocol an `SslContext` will speak.
+#[derive(Copy, Clone)]
+pub struct SslMethod(*const ffi::SSL_METHOD);
+
+impl SslMethod {
+    /// Support all versions of the TLS protocol.
+    #[corresponds(TLS_method)]
+    pub fn tls() -> SslMethod {
+        unsafe { SslMethod(TLS_method()) }
+    }
+
+    /// Support all versions of the DTLS protocol.
+    #[corresponds(DTLS_method)]
+    pub fn dtls() -> SslMethod {
+        unsafe { SslMethod(DTLS_method()) }
+    }
+
+    /// Support all versions of the TLS protocol, explicitly as a client.
+    #[corresponds(TLS_client_method)]
+    pub fn tls_client() -> SslMethod {
+        unsafe { SslMethod(TLS_client_method()) }
+    }
+
+    /// Support all versions of the TLS protocol, explicitly as a server.
+    #[corresponds(TLS_server_method)]
+    pub fn tls_server() -> SslMethod {
+        unsafe { SslMethod(TLS_server_method()) }
+    }
+
+    /// Constructs an `SslMethod` from a pointer to the underlying OpenSSL value.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure the pointer is valid.
+    pub unsafe fn from_ptr(ptr: *const ffi::SSL_METHOD) -> SslMethod {
+        SslMethod(ptr)
+    }
+
+    /// Returns a pointer to the underlying OpenSSL value.
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn as_ptr(&self) -> *const ffi::SSL_METHOD {
+        self.0
+    }
+}
+
+unsafe impl Sync for SslMethod {}
+unsafe impl Send for SslMethod {}
+
+bitflags! {
+    /// Options controlling the behavior of certificate verification.
+    pub struct SslVerifyMode: i32 {
+        /// Verifies that the peer's certificate is trusted.
+        ///
+        /// On the server side, this will cause OpenSSL to request a certificate from the client.
+        const PEER = ffi::SSL_VERIFY_PEER;
+
+        /// Disables verification of the peer's certificate.
+        ///
+        /// On the server side, this will cause OpenSSL to not request a certificate from the
+        /// client. On the client side, the certificate will be checked for validity, but the
+        /// negotiation will continue regardless of the result of that check.
+        const NONE = ffi::SSL_VERIFY_NONE;
+
+        /// On the server side, abort the handshake if the client did not send a certificate.
+        ///
+        /// This should be paired with `SSL_VERIFY_PEER`. It has no effect on the client side.
+        const FAIL_IF_NO_PEER_CERT = ffi::SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
+    }
+}
+
+#[cfg(boringssl)]
+type SslBitType = c_int;
+#[cfg(not(boringssl))]
+type SslBitType = c_long;
+
+#[cfg(boringssl)]
+type SslTimeTy = u64;
+#[cfg(not(boringssl))]
+type SslTimeTy = c_long;
+
+bitflags! {
+    /// Options controlling the behavior of session caching.
+    pub struct SslSessionCacheMode: SslBitType {
+        /// No session caching for the client or server takes place.
+        const OFF = ffi::SSL_SESS_CACHE_OFF;
+
+        /// Enable session caching on the client side.
+        ///
+        /// OpenSSL has no way of identifying the proper session to reuse automatically, so the
+        /// application is responsible for setting it explicitly via [`SslRef::set_session`].
+        ///
+        /// [`SslRef::set_session`]: struct.SslRef.html#method.set_session
+        const CLIENT = ffi::SSL_SESS_CACHE_CLIENT;
+
+        /// Enable session caching on the server side.
+        ///
+        /// This is the default mode.
+        const SERVER = ffi::SSL_SESS_CACHE_SERVER;
+
+        /// Enable session caching on both the client and server side.
+        const BOTH = ffi::SSL_SESS_CACHE_BOTH;
+
+        /// Disable automatic removal of expired sessions from the session cache.
+        const NO_AUTO_CLEAR = ffi::SSL_SESS_CACHE_NO_AUTO_CLEAR;
+
+        /// Disable use of the internal session cache for session lookups.
+        const NO_INTERNAL_LOOKUP = ffi::SSL_SESS_CACHE_NO_INTERNAL_LOOKUP;
+
+        /// Disable use of the internal session cache for session storage.
+        const NO_INTERNAL_STORE = ffi::SSL_SESS_CACHE_NO_INTERNAL_STORE;
+
+        /// Disable use of the internal session cache for storage and lookup.
+        const NO_INTERNAL = ffi::SSL_SESS_CACHE_NO_INTERNAL;
+    }
+}
+
+#[cfg(ossl111)]
+bitflags! {
+    /// Which messages and under which conditions an extension should be added or expected.
+    pub struct ExtensionContext: c_uint {
+        /// This extension is only allowed in TLS
+        const TLS_ONLY = ffi::SSL_EXT_TLS_ONLY;
+        /// This extension is only allowed in DTLS
+        const DTLS_ONLY = ffi::SSL_EXT_DTLS_ONLY;
+        /// Some extensions may be allowed in DTLS but we don't implement them for it
+        const TLS_IMPLEMENTATION_ONLY = ffi::SSL_EXT_TLS_IMPLEMENTATION_ONLY;
+        /// Most extensions are not defined for SSLv3 but EXT_TYPE_renegotiate is
+        const SSL3_ALLOWED = ffi::SSL_EXT_SSL3_ALLOWED;
+        /// Extension is only defined for TLS1.2 and below
+        const TLS1_2_AND_BELOW_ONLY = ffi::SSL_EXT_TLS1_2_AND_BELOW_ONLY;
+        /// Extension is only defined for TLS1.3 and above
+        const TLS1_3_ONLY = ffi::SSL_EXT_TLS1_3_ONLY;
+        /// Ignore this extension during parsing if we are resuming
+        const IGNORE_ON_RESUMPTION = ffi::SSL_EXT_IGNORE_ON_RESUMPTION;
+        const CLIENT_HELLO = ffi::SSL_EXT_CLIENT_HELLO;
+        /// Really means TLS1.2 or below
+        const TLS1_2_SERVER_HELLO = ffi::SSL_EXT_TLS1_2_SERVER_HELLO;
+        const TLS1_3_SERVER_HELLO = ffi::SSL_EXT_TLS1_3_SERVER_HELLO;
+        const TLS1_3_ENCRYPTED_EXTENSIONS = ffi::SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS;
+        const TLS1_3_HELLO_RETRY_REQUEST = ffi::SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST;
+        const TLS1_3_CERTIFICATE = ffi::SSL_EXT_TLS1_3_CERTIFICATE;
+        const TLS1_3_NEW_SESSION_TICKET = ffi::SSL_EXT_TLS1_3_NEW_SESSION_TICKET;
+        const TLS1_3_CERTIFICATE_REQUEST = ffi::SSL_EXT_TLS1_3_CERTIFICATE_REQUEST;
+    }
+}
+
+/// An identifier of the format of a certificate or key file.
+#[derive(Copy, Clone)]
+pub struct SslFiletype(c_int);
+
+impl SslFiletype {
+    /// The PEM format.
+    ///
+    /// This corresponds to `SSL_FILETYPE_PEM`.
+    pub const PEM: SslFiletype = SslFiletype(ffi::SSL_FILETYPE_PEM);
+
+    /// The ASN1 format.
+    ///
+    /// This corresponds to `SSL_FILETYPE_ASN1`.
+    pub const ASN1: SslFiletype = SslFiletype(ffi::SSL_FILETYPE_ASN1);
+
+    /// Constructs an `SslFiletype` from a raw OpenSSL value.
+    pub fn from_raw(raw: c_int) -> SslFiletype {
+        SslFiletype(raw)
+    }
+
+    /// Returns the raw OpenSSL value represented by this type.
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn as_raw(&self) -> c_int {
+        self.0
+    }
+}
+
+/// An identifier of a certificate status type.
+#[derive(Copy, Clone)]
+pub struct StatusType(c_int);
+
+impl StatusType {
+    /// An OSCP status.
+    pub const OCSP: StatusType = StatusType(ffi::TLSEXT_STATUSTYPE_ocsp);
+
+    /// Constructs a `StatusType` from a raw OpenSSL value.
+    pub fn from_raw(raw: c_int) -> StatusType {
+        StatusType(raw)
+    }
+
+    /// Returns the raw OpenSSL value represented by this type.
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn as_raw(&self) -> c_int {
+        self.0
+    }
+}
+
+/// An identifier of a session name type.
+#[derive(Copy, Clone)]
+pub struct NameType(c_int);
+
+impl NameType {
+    /// A host name.
+    pub const HOST_NAME: NameType = NameType(ffi::TLSEXT_NAMETYPE_host_name);
+
+    /// Constructs a `StatusType` from a raw OpenSSL value.
+    pub fn from_raw(raw: c_int) -> StatusType {
+        StatusType(raw)
+    }
+
+    /// Returns the raw OpenSSL value represented by this type.
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn as_raw(&self) -> c_int {
+        self.0
+    }
+}
+
+static INDEXES: Lazy<Mutex<HashMap<TypeId, c_int>>> = Lazy::new(|| Mutex::new(HashMap::new()));
+static SSL_INDEXES: Lazy<Mutex<HashMap<TypeId, c_int>>> = Lazy::new(|| Mutex::new(HashMap::new()));
+static SESSION_CTX_INDEX: OnceCell<Index<Ssl, SslContext>> = OnceCell::new();
+
+fn try_get_session_ctx_index() -> Result<&'static Index<Ssl, SslContext>, ErrorStack> {
+    SESSION_CTX_INDEX.get_or_try_init(Ssl::new_ex_index)
+}
+
+unsafe extern "C" fn free_data_box<T>(
+    _parent: *mut c_void,
+    ptr: *mut c_void,
+    _ad: *mut ffi::CRYPTO_EX_DATA,
+    _idx: c_int,
+    _argl: c_long,
+    _argp: *mut c_void,
+) {
+    if !ptr.is_null() {
+        let _ = Box::<T>::from_raw(ptr as *mut T);
+    }
+}
+
+/// An error returned from the SNI callback.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct SniError(c_int);
+
+impl SniError {
+    /// Abort the handshake with a fatal alert.
+    pub const ALERT_FATAL: SniError = SniError(ffi::SSL_TLSEXT_ERR_ALERT_FATAL);
+
+    /// Send a warning alert to the client and continue the handshake.
+    pub const ALERT_WARNING: SniError = SniError(ffi::SSL_TLSEXT_ERR_ALERT_WARNING);
+
+    pub const NOACK: SniError = SniError(ffi::SSL_TLSEXT_ERR_NOACK);
+}
+
+/// An SSL/TLS alert.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct SslAlert(c_int);
+
+impl SslAlert {
+    /// Alert 112 - `unrecognized_name`.
+    pub const UNRECOGNIZED_NAME: SslAlert = SslAlert(ffi::SSL_AD_UNRECOGNIZED_NAME);
+    pub const ILLEGAL_PARAMETER: SslAlert = SslAlert(ffi::SSL_AD_ILLEGAL_PARAMETER);
+    pub const DECODE_ERROR: SslAlert = SslAlert(ffi::SSL_AD_DECODE_ERROR);
+}
+
+/// An error returned from an ALPN selection callback.
+///
+/// Requires OpenSSL 1.0.2 or LibreSSL 2.6.1 or newer.
+#[cfg(any(ossl102, libressl261))]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct AlpnError(c_int);
+
+#[cfg(any(ossl102, libressl261))]
+impl AlpnError {
+    /// Terminate the handshake with a fatal alert.
+    ///
+    /// Requires OpenSSL 1.1.0 or newer.
+    #[cfg(any(ossl110))]
+    pub const ALERT_FATAL: AlpnError = AlpnError(ffi::SSL_TLSEXT_ERR_ALERT_FATAL);
+
+    /// Do not select a protocol, but continue the handshake.
+    pub const NOACK: AlpnError = AlpnError(ffi::SSL_TLSEXT_ERR_NOACK);
+}
+
+/// The result of a client hello callback.
+///
+/// Requires OpenSSL 1.1.1 or newer.
+#[cfg(ossl111)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct ClientHelloResponse(c_int);
+
+#[cfg(ossl111)]
+impl ClientHelloResponse {
+    /// Continue the handshake.
+    pub const SUCCESS: ClientHelloResponse = ClientHelloResponse(ffi::SSL_CLIENT_HELLO_SUCCESS);
+
+    /// Return from the handshake with an `ErrorCode::WANT_CLIENT_HELLO_CB` error.
+    pub const RETRY: ClientHelloResponse = ClientHelloResponse(ffi::SSL_CLIENT_HELLO_RETRY);
+}
+
+/// An SSL/TLS protocol version.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct SslVersion(c_int);
+
+impl SslVersion {
+    /// SSLv3
+    pub const SSL3: SslVersion = SslVersion(ffi::SSL3_VERSION);
+
+    /// TLSv1.0
+    pub const TLS1: SslVersion = SslVersion(ffi::TLS1_VERSION);
+
+    /// TLSv1.1
+    pub const TLS1_1: SslVersion = SslVersion(ffi::TLS1_1_VERSION);
+
+    /// TLSv1.2
+    pub const TLS1_2: SslVersion = SslVersion(ffi::TLS1_2_VERSION);
+
+    /// TLSv1.3
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[cfg(any(ossl111, libressl340))]
+    pub const TLS1_3: SslVersion = SslVersion(ffi::TLS1_3_VERSION);
+}
+
+cfg_if! {
+    if #[cfg(boringssl)] {
+        type SslCacheTy = i64;
+        type SslCacheSize = libc::c_ulong;
+        type MtuTy = u32;
+        type SizeTy = usize;
+    } else {
+        type SslCacheTy = i64;
+        type SslCacheSize = c_long;
+        type MtuTy = c_long;
+        type SizeTy = u32;
+    }
+}
+
+/// A standard implementation of protocol selection for Application Layer Protocol Negotiation
+/// (ALPN).
+///
+/// `server` should contain the server's list of supported protocols and `client` the client's. They
+/// must both be in the ALPN wire format. See the documentation for
+/// [`SslContextBuilder::set_alpn_protos`] for details.
+///
+/// It will select the first protocol supported by the server which is also supported by the client.
+///
+/// [`SslContextBuilder::set_alpn_protos`]: struct.SslContextBuilder.html#method.set_alpn_protos
+#[corresponds(SSL_select_next_proto)]
+pub fn select_next_proto<'a>(server: &[u8], client: &'a [u8]) -> Option<&'a [u8]> {
+    unsafe {
+        let mut out = ptr::null_mut();
+        let mut outlen = 0;
+        let r = ffi::SSL_select_next_proto(
+            &mut out,
+            &mut outlen,
+            server.as_ptr(),
+            server.len() as c_uint,
+            client.as_ptr(),
+            client.len() as c_uint,
+        );
+        if r == ffi::OPENSSL_NPN_NEGOTIATED {
+            Some(slice::from_raw_parts(out as *const u8, outlen as usize))
+        } else {
+            None
+        }
+    }
+}
+
+/// A builder for `SslContext`s.
+pub struct SslContextBuilder(SslContext);
+
+impl SslContextBuilder {
+    /// Creates a new `SslContextBuilder`.
+    #[corresponds(SSL_CTX_new)]
+    pub fn new(method: SslMethod) -> Result<SslContextBuilder, ErrorStack> {
+        unsafe {
+            init();
+            let ctx = cvt_p(ffi::SSL_CTX_new(method.as_ptr()))?;
+
+            Ok(SslContextBuilder::from_ptr(ctx))
+        }
+    }
+
+    /// Creates an `SslContextBuilder` from a pointer to a raw OpenSSL value.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that the pointer is valid and uniquely owned by the builder.
+    pub unsafe fn from_ptr(ctx: *mut ffi::SSL_CTX) -> SslContextBuilder {
+        SslContextBuilder(SslContext::from_ptr(ctx))
+    }
+
+    /// Returns a pointer to the raw OpenSSL value.
+    pub fn as_ptr(&self) -> *mut ffi::SSL_CTX {
+        self.0.as_ptr()
+    }
+
+    /// Configures the certificate verification method for new connections.
+    #[corresponds(SSL_CTX_set_verify)]
+    pub fn set_verify(&mut self, mode: SslVerifyMode) {
+        unsafe {
+            ffi::SSL_CTX_set_verify(self.as_ptr(), mode.bits as c_int, None);
+        }
+    }
+
+    /// Configures the certificate verification method for new connections and
+    /// registers a verification callback.
+    ///
+    /// The callback is passed a boolean indicating if OpenSSL's internal verification succeeded as
+    /// well as a reference to the `X509StoreContext` which can be used to examine the certificate
+    /// chain. It should return a boolean indicating if verification succeeded.
+    #[corresponds(SSL_CTX_set_verify)]
+    pub fn set_verify_callback<F>(&mut self, mode: SslVerifyMode, verify: F)
+    where
+        F: Fn(bool, &mut X509StoreContextRef) -> bool + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), verify);
+            ffi::SSL_CTX_set_verify(self.as_ptr(), mode.bits as c_int, Some(raw_verify::<F>));
+        }
+    }
+
+    /// Configures the server name indication (SNI) callback for new connections.
+    ///
+    /// SNI is used to allow a single server to handle requests for multiple domains, each of which
+    /// has its own certificate chain and configuration.
+    ///
+    /// Obtain the server name with the `servername` method and then set the corresponding context
+    /// with `set_ssl_context`
+    #[corresponds(SSL_CTX_set_tlsext_servername_callback)]
+    // FIXME tlsext prefix?
+    pub fn set_servername_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &mut SslAlert) -> Result<(), SniError> + 'static + Sync + Send,
+    {
+        unsafe {
+            // The SNI callback is somewhat unique in that the callback associated with the original
+            // context associated with an SSL can be used even if the SSL's context has been swapped
+            // out. When that happens, we wouldn't be able to look up the callback's state in the
+            // context's ex data. Instead, pass the pointer directly as the servername arg. It's
+            // still stored in ex data to manage the lifetime.
+            let arg = self.set_ex_data_inner(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_tlsext_servername_arg(self.as_ptr(), arg);
+            #[cfg(boringssl)]
+            ffi::SSL_CTX_set_tlsext_servername_callback(self.as_ptr(), Some(raw_sni::<F>));
+            #[cfg(not(boringssl))]
+            ffi::SSL_CTX_set_tlsext_servername_callback__fixed_rust(
+                self.as_ptr(),
+                Some(raw_sni::<F>),
+            );
+        }
+    }
+
+    /// Sets the certificate verification depth.
+    ///
+    /// If the peer's certificate chain is longer than this value, verification will fail.
+    #[corresponds(SSL_CTX_set_verify_depth)]
+    pub fn set_verify_depth(&mut self, depth: u32) {
+        unsafe {
+            ffi::SSL_CTX_set_verify_depth(self.as_ptr(), depth as c_int);
+        }
+    }
+
+    /// Sets a custom certificate store for verifying peer certificates.
+    ///
+    /// Requires OpenSSL 1.0.2 or newer.
+    #[corresponds(SSL_CTX_set0_verify_cert_store)]
+    #[cfg(ossl102)]
+    pub fn set_verify_cert_store(&mut self, cert_store: X509Store) -> Result<(), ErrorStack> {
+        unsafe {
+            let ptr = cert_store.as_ptr();
+            cvt(ffi::SSL_CTX_set0_verify_cert_store(self.as_ptr(), ptr) as c_int)?;
+            mem::forget(cert_store);
+
+            Ok(())
+        }
+    }
+
+    /// Replaces the context's certificate store.
+    #[corresponds(SSL_CTX_set_cert_store)]
+    pub fn set_cert_store(&mut self, cert_store: X509Store) {
+        unsafe {
+            ffi::SSL_CTX_set_cert_store(self.as_ptr(), cert_store.as_ptr());
+            mem::forget(cert_store);
+        }
+    }
+
+    /// Controls read ahead behavior.
+    ///
+    /// If enabled, OpenSSL will read as much data as is available from the underlying stream,
+    /// instead of a single record at a time.
+    ///
+    /// It has no effect when used with DTLS.
+    #[corresponds(SSL_CTX_set_read_ahead)]
+    pub fn set_read_ahead(&mut self, read_ahead: bool) {
+        unsafe {
+            ffi::SSL_CTX_set_read_ahead(self.as_ptr(), read_ahead as SslBitType);
+        }
+    }
+
+    /// Sets the mode used by the context, returning the previous mode.
+    #[corresponds(SSL_CTX_set_mode)]
+    pub fn set_mode(&mut self, mode: SslMode) -> SslMode {
+        unsafe {
+            let bits = ffi::SSL_CTX_set_mode(self.as_ptr(), mode.bits() as MtuTy) as SslBitType;
+            SslMode { bits }
+        }
+    }
+
+    /// Sets the parameters to be used during ephemeral Diffie-Hellman key exchange.
+    #[corresponds(SSL_CTX_set_tmp_dh)]
+    pub fn set_tmp_dh(&mut self, dh: &DhRef<Params>) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_set_tmp_dh(self.as_ptr(), dh.as_ptr()) as c_int).map(|_| ()) }
+    }
+
+    /// Sets the callback which will generate parameters to be used during ephemeral Diffie-Hellman
+    /// key exchange.
+    ///
+    /// The callback is provided with a reference to the `Ssl` for the session, as well as a boolean
+    /// indicating if the selected cipher is export-grade, and the key length. The export and key
+    /// length options are archaic and should be ignored in almost all cases.
+    #[corresponds(SSL_CTX_set_tmp_dh_callback)]
+    pub fn set_tmp_dh_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, bool, u32) -> Result<Dh<Params>, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+
+            #[cfg(not(boringssl))]
+            ffi::SSL_CTX_set_tmp_dh_callback__fixed_rust(self.as_ptr(), Some(raw_tmp_dh::<F>));
+            #[cfg(boringssl)]
+            ffi::SSL_CTX_set_tmp_dh_callback(self.as_ptr(), Some(raw_tmp_dh::<F>));
+        }
+    }
+
+    /// Sets the parameters to be used during ephemeral elliptic curve Diffie-Hellman key exchange.
+    #[corresponds(SSL_CTX_set_tmp_ecdh)]
+    pub fn set_tmp_ecdh(&mut self, key: &EcKeyRef<Params>) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_set_tmp_ecdh(self.as_ptr(), key.as_ptr()) as c_int).map(|_| ()) }
+    }
+
+    /// Sets the callback which will generate parameters to be used during ephemeral elliptic curve
+    /// Diffie-Hellman key exchange.
+    ///
+    /// The callback is provided with a reference to the `Ssl` for the session, as well as a boolean
+    /// indicating if the selected cipher is export-grade, and the key length. The export and key
+    /// length options are archaic and should be ignored in almost all cases.
+    ///
+    /// Requires OpenSSL 1.0.1 or 1.0.2.
+    #[corresponds(SSL_CTX_set_tmp_ecdh_callback)]
+    #[cfg(all(ossl101, not(ossl110)))]
+    #[deprecated(note = "this function leaks memory and does not exist on newer OpenSSL versions")]
+    pub fn set_tmp_ecdh_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, bool, u32) -> Result<EcKey<Params>, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_tmp_ecdh_callback__fixed_rust(self.as_ptr(), Some(raw_tmp_ecdh::<F>));
+        }
+    }
+
+    /// Use the default locations of trusted certificates for verification.
+    ///
+    /// These locations are read from the `SSL_CERT_FILE` and `SSL_CERT_DIR` environment variables
+    /// if present, or defaults specified at OpenSSL build time otherwise.
+    #[corresponds(SSL_CTX_set_default_verify_paths)]
+    pub fn set_default_verify_paths(&mut self) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_set_default_verify_paths(self.as_ptr())).map(|_| ()) }
+    }
+
+    /// Loads trusted root certificates from a file.
+    ///
+    /// The file should contain a sequence of PEM-formatted CA certificates.
+    #[corresponds(SSL_CTX_load_verify_locations)]
+    pub fn set_ca_file<P: AsRef<Path>>(&mut self, file: P) -> Result<(), ErrorStack> {
+        let file = CString::new(file.as_ref().as_os_str().to_str().unwrap()).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_load_verify_locations(
+                self.as_ptr(),
+                file.as_ptr() as *const _,
+                ptr::null(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the list of CA names sent to the client.
+    ///
+    /// The CA certificates must still be added to the trust root - they are not automatically set
+    /// as trusted by this method.
+    #[corresponds(SSL_CTX_set_client_CA_list)]
+    pub fn set_client_ca_list(&mut self, list: Stack<X509Name>) {
+        unsafe {
+            ffi::SSL_CTX_set_client_CA_list(self.as_ptr(), list.as_ptr());
+            mem::forget(list);
+        }
+    }
+
+    /// Add the provided CA certificate to the list sent by the server to the client when
+    /// requesting client-side TLS authentication.
+    #[corresponds(SSL_CTX_add_client_CA)]
+    pub fn add_client_ca(&mut self, cacert: &X509Ref) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_add_client_CA(self.as_ptr(), cacert.as_ptr())).map(|_| ()) }
+    }
+
+    /// Set the context identifier for sessions.
+    ///
+    /// This value identifies the server's session cache to clients, telling them when they're
+    /// able to reuse sessions. It should be set to a unique value per server, unless multiple
+    /// servers share a session cache.
+    ///
+    /// This value should be set when using client certificates, or each request will fail its
+    /// handshake and need to be restarted.
+    #[corresponds(SSL_CTX_set_session_id_context)]
+    pub fn set_session_id_context(&mut self, sid_ctx: &[u8]) -> Result<(), ErrorStack> {
+        unsafe {
+            assert!(sid_ctx.len() <= c_uint::max_value() as usize);
+            cvt(ffi::SSL_CTX_set_session_id_context(
+                self.as_ptr(),
+                sid_ctx.as_ptr(),
+                sid_ctx.len() as SizeTy,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Loads a leaf certificate from a file.
+    ///
+    /// Only a single certificate will be loaded - use `add_extra_chain_cert` to add the remainder
+    /// of the certificate chain, or `set_certificate_chain_file` to load the entire chain from a
+    /// single file.
+    #[corresponds(SSL_CTX_use_certificate_file)]
+    pub fn set_certificate_file<P: AsRef<Path>>(
+        &mut self,
+        file: P,
+        file_type: SslFiletype,
+    ) -> Result<(), ErrorStack> {
+        let file = CString::new(file.as_ref().as_os_str().to_str().unwrap()).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_use_certificate_file(
+                self.as_ptr(),
+                file.as_ptr() as *const _,
+                file_type.as_raw(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Loads a certificate chain from a file.
+    ///
+    /// The file should contain a sequence of PEM-formatted certificates, the first being the leaf
+    /// certificate, and the remainder forming the chain of certificates up to and including the
+    /// trusted root certificate.
+    #[corresponds(SSL_CTX_use_certificate_chain_file)]
+    pub fn set_certificate_chain_file<P: AsRef<Path>>(
+        &mut self,
+        file: P,
+    ) -> Result<(), ErrorStack> {
+        let file = CString::new(file.as_ref().as_os_str().to_str().unwrap()).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_use_certificate_chain_file(
+                self.as_ptr(),
+                file.as_ptr() as *const _,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the leaf certificate.
+    ///
+    /// Use `add_extra_chain_cert` to add the remainder of the certificate chain.
+    #[corresponds(SSL_CTX_use_certificate)]
+    pub fn set_certificate(&mut self, cert: &X509Ref) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_use_certificate(self.as_ptr(), cert.as_ptr())).map(|_| ()) }
+    }
+
+    /// Appends a certificate to the certificate chain.
+    ///
+    /// This chain should contain all certificates necessary to go from the certificate specified by
+    /// `set_certificate` to a trusted root.
+    #[corresponds(SSL_CTX_add_extra_chain_cert)]
+    pub fn add_extra_chain_cert(&mut self, cert: X509) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_CTX_add_extra_chain_cert(self.as_ptr(), cert.as_ptr()) as c_int)?;
+            mem::forget(cert);
+            Ok(())
+        }
+    }
+
+    /// Loads the private key from a file.
+    #[corresponds(SSL_CTX_use_PrivateKey_file)]
+    pub fn set_private_key_file<P: AsRef<Path>>(
+        &mut self,
+        file: P,
+        file_type: SslFiletype,
+    ) -> Result<(), ErrorStack> {
+        let file = CString::new(file.as_ref().as_os_str().to_str().unwrap()).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_use_PrivateKey_file(
+                self.as_ptr(),
+                file.as_ptr() as *const _,
+                file_type.as_raw(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the private key.
+    #[corresponds(SSL_CTX_use_PrivateKey)]
+    pub fn set_private_key<T>(&mut self, key: &PKeyRef<T>) -> Result<(), ErrorStack>
+    where
+        T: HasPrivate,
+    {
+        unsafe { cvt(ffi::SSL_CTX_use_PrivateKey(self.as_ptr(), key.as_ptr())).map(|_| ()) }
+    }
+
+    /// Sets the list of supported ciphers for protocols before TLSv1.3.
+    ///
+    /// The `set_ciphersuites` method controls the cipher suites for TLSv1.3.
+    ///
+    /// See [`ciphers`] for details on the format.
+    ///
+    /// [`ciphers`]: https://www.openssl.org/docs/manmaster/apps/ciphers.html
+    #[corresponds(SSL_CTX_set_cipher_list)]
+    pub fn set_cipher_list(&mut self, cipher_list: &str) -> Result<(), ErrorStack> {
+        let cipher_list = CString::new(cipher_list).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_set_cipher_list(
+                self.as_ptr(),
+                cipher_list.as_ptr() as *const _,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the list of supported ciphers for the TLSv1.3 protocol.
+    ///
+    /// The `set_cipher_list` method controls the cipher suites for protocols before TLSv1.3.
+    ///
+    /// The format consists of TLSv1.3 cipher suite names separated by `:` characters in order of
+    /// preference.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_CTX_set_ciphersuites)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn set_ciphersuites(&mut self, cipher_list: &str) -> Result<(), ErrorStack> {
+        let cipher_list = CString::new(cipher_list).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_set_ciphersuites(
+                self.as_ptr(),
+                cipher_list.as_ptr() as *const _,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Enables ECDHE key exchange with an automatically chosen curve list.
+    ///
+    /// Requires OpenSSL 1.0.2.
+    #[corresponds(SSL_CTX_set_ecdh_auto)]
+    #[cfg(any(libressl, all(ossl102, not(ossl110))))]
+    pub fn set_ecdh_auto(&mut self, onoff: bool) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_set_ecdh_auto(self.as_ptr(), onoff as c_int)).map(|_| ()) }
+    }
+
+    /// Sets the options used by the context, returning the old set.
+    ///
+    /// # Note
+    ///
+    /// This *enables* the specified options, but does not disable unspecified options. Use
+    /// `clear_options` for that.
+    #[corresponds(SSL_CTX_set_options)]
+    pub fn set_options(&mut self, option: SslOptions) -> SslOptions {
+        let bits =
+            unsafe { ffi::SSL_CTX_set_options(self.as_ptr(), option.bits()) } as SslOptionsRepr;
+        SslOptions { bits }
+    }
+
+    /// Returns the options used by the context.
+    #[corresponds(SSL_CTX_get_options)]
+    pub fn options(&self) -> SslOptions {
+        let bits = unsafe { ffi::SSL_CTX_get_options(self.as_ptr()) } as SslOptionsRepr;
+        SslOptions { bits }
+    }
+
+    /// Clears the options used by the context, returning the old set.
+    #[corresponds(SSL_CTX_clear_options)]
+    pub fn clear_options(&mut self, option: SslOptions) -> SslOptions {
+        let bits =
+            unsafe { ffi::SSL_CTX_clear_options(self.as_ptr(), option.bits()) } as SslOptionsRepr;
+        SslOptions { bits }
+    }
+
+    /// Sets the minimum supported protocol version.
+    ///
+    /// A value of `None` will enable protocol versions down to the lowest version supported by
+    /// OpenSSL.
+    ///
+    /// Requires OpenSSL 1.1.0 or LibreSSL 2.6.1 or newer.
+    #[corresponds(SSL_CTX_set_min_proto_version)]
+    #[cfg(any(ossl110, libressl261))]
+    pub fn set_min_proto_version(&mut self, version: Option<SslVersion>) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_CTX_set_min_proto_version(
+                self.as_ptr(),
+                version.map_or(0, |v| v.0 as _),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the maximum supported protocol version.
+    ///
+    /// A value of `None` will enable protocol versions up to the highest version supported by
+    /// OpenSSL.
+    ///
+    /// Requires OpenSSL 1.1.0 or or LibreSSL 2.6.1 or newer.
+    #[corresponds(SSL_CTX_set_max_proto_version)]
+    #[cfg(any(ossl110, libressl261))]
+    pub fn set_max_proto_version(&mut self, version: Option<SslVersion>) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_CTX_set_max_proto_version(
+                self.as_ptr(),
+                version.map_or(0, |v| v.0 as _),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Gets the minimum supported protocol version.
+    ///
+    /// A value of `None` indicates that all versions down to the lowest version supported by
+    /// OpenSSL are enabled.
+    ///
+    /// Requires OpenSSL 1.1.0g or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_CTX_get_min_proto_version)]
+    #[cfg(any(ossl110g, libressl270))]
+    pub fn min_proto_version(&mut self) -> Option<SslVersion> {
+        unsafe {
+            let r = ffi::SSL_CTX_get_min_proto_version(self.as_ptr());
+            if r == 0 {
+                None
+            } else {
+                Some(SslVersion(r))
+            }
+        }
+    }
+
+    /// Gets the maximum supported protocol version.
+    ///
+    /// A value of `None` indicates that all versions up to the highest version supported by
+    /// OpenSSL are enabled.
+    ///
+    /// Requires OpenSSL 1.1.0g or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_CTX_get_max_proto_version)]
+    #[cfg(any(ossl110g, libressl270))]
+    pub fn max_proto_version(&mut self) -> Option<SslVersion> {
+        unsafe {
+            let r = ffi::SSL_CTX_get_max_proto_version(self.as_ptr());
+            if r == 0 {
+                None
+            } else {
+                Some(SslVersion(r))
+            }
+        }
+    }
+
+    /// Sets the protocols to sent to the server for Application Layer Protocol Negotiation (ALPN).
+    ///
+    /// The input must be in ALPN "wire format". It consists of a sequence of supported protocol
+    /// names prefixed by their byte length. For example, the protocol list consisting of `spdy/1`
+    /// and `http/1.1` is encoded as `b"\x06spdy/1\x08http/1.1"`. The protocols are ordered by
+    /// preference.
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL 2.6.1 or newer.
+    #[corresponds(SSL_CTX_set_alpn_protos)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn set_alpn_protos(&mut self, protocols: &[u8]) -> Result<(), ErrorStack> {
+        unsafe {
+            assert!(protocols.len() <= c_uint::max_value() as usize);
+            let r = ffi::SSL_CTX_set_alpn_protos(
+                self.as_ptr(),
+                protocols.as_ptr(),
+                protocols.len() as c_uint,
+            );
+            // fun fact, SSL_CTX_set_alpn_protos has a reversed return code D:
+            if r == 0 {
+                Ok(())
+            } else {
+                Err(ErrorStack::get())
+            }
+        }
+    }
+
+    /// Enables the DTLS extension "use_srtp" as defined in RFC5764.
+    #[corresponds(SSL_CTX_set_tlsext_use_srtp)]
+    pub fn set_tlsext_use_srtp(&mut self, protocols: &str) -> Result<(), ErrorStack> {
+        unsafe {
+            let cstr = CString::new(protocols).unwrap();
+
+            let r = ffi::SSL_CTX_set_tlsext_use_srtp(self.as_ptr(), cstr.as_ptr());
+            // fun fact, set_tlsext_use_srtp has a reversed return code D:
+            if r == 0 {
+                Ok(())
+            } else {
+                Err(ErrorStack::get())
+            }
+        }
+    }
+
+    /// Sets the callback used by a server to select a protocol for Application Layer Protocol
+    /// Negotiation (ALPN).
+    ///
+    /// The callback is provided with the client's protocol list in ALPN wire format. See the
+    /// documentation for [`SslContextBuilder::set_alpn_protos`] for details. It should return one
+    /// of those protocols on success. The [`select_next_proto`] function implements the standard
+    /// protocol selection algorithm.
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL 2.6.1 or newer.
+    ///
+    /// [`SslContextBuilder::set_alpn_protos`]: struct.SslContextBuilder.html#method.set_alpn_protos
+    /// [`select_next_proto`]: fn.select_next_proto.html
+    #[corresponds(SSL_CTX_set_alpn_select_cb)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn set_alpn_select_callback<F>(&mut self, callback: F)
+    where
+        F: for<'a> Fn(&mut SslRef, &'a [u8]) -> Result<&'a [u8], AlpnError> + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_alpn_select_cb__fixed_rust(
+                self.as_ptr(),
+                Some(callbacks::raw_alpn_select::<F>),
+                ptr::null_mut(),
+            );
+        }
+    }
+
+    /// Checks for consistency between the private key and certificate.
+    #[corresponds(SSL_CTX_check_private_key)]
+    pub fn check_private_key(&self) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_check_private_key(self.as_ptr())).map(|_| ()) }
+    }
+
+    /// Returns a shared reference to the context's certificate store.
+    #[corresponds(SSL_CTX_get_cert_store)]
+    pub fn cert_store(&self) -> &X509StoreBuilderRef {
+        unsafe { X509StoreBuilderRef::from_ptr(ffi::SSL_CTX_get_cert_store(self.as_ptr())) }
+    }
+
+    /// Returns a mutable reference to the context's certificate store.
+    #[corresponds(SSL_CTX_get_cert_store)]
+    pub fn cert_store_mut(&mut self) -> &mut X509StoreBuilderRef {
+        unsafe { X509StoreBuilderRef::from_ptr_mut(ffi::SSL_CTX_get_cert_store(self.as_ptr())) }
+    }
+
+    /// Returns a reference to the X509 verification configuration.
+    ///
+    /// Requires OpenSSL 1.0.2 or newer.
+    #[corresponds(SSL_CTX_get0_param)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn verify_param(&self) -> &X509VerifyParamRef {
+        unsafe { X509VerifyParamRef::from_ptr(ffi::SSL_CTX_get0_param(self.as_ptr())) }
+    }
+
+    /// Returns a mutable reference to the X509 verification configuration.
+    ///
+    /// Requires OpenSSL 1.0.2 or newer.
+    #[corresponds(SSL_CTX_get0_param)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn verify_param_mut(&mut self) -> &mut X509VerifyParamRef {
+        unsafe { X509VerifyParamRef::from_ptr_mut(ffi::SSL_CTX_get0_param(self.as_ptr())) }
+    }
+
+    /// Sets the callback dealing with OCSP stapling.
+    ///
+    /// On the client side, this callback is responsible for validating the OCSP status response
+    /// returned by the server. The status may be retrieved with the `SslRef::ocsp_status` method.
+    /// A response of `Ok(true)` indicates that the OCSP status is valid, and a response of
+    /// `Ok(false)` indicates that the OCSP status is invalid and the handshake should be
+    /// terminated.
+    ///
+    /// On the server side, this callback is responsible for setting the OCSP status response to be
+    /// returned to clients. The status may be set with the `SslRef::set_ocsp_status` method. A
+    /// response of `Ok(true)` indicates that the OCSP status should be returned to the client, and
+    /// `Ok(false)` indicates that the status should not be returned to the client.
+    #[corresponds(SSL_CTX_set_tlsext_status_cb)]
+    pub fn set_status_callback<F>(&mut self, callback: F) -> Result<(), ErrorStack>
+    where
+        F: Fn(&mut SslRef) -> Result<bool, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            cvt(
+                ffi::SSL_CTX_set_tlsext_status_cb(self.as_ptr(), Some(raw_tlsext_status::<F>))
+                    as c_int,
+            )
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the callback for providing an identity and pre-shared key for a TLS-PSK client.
+    ///
+    /// The callback will be called with the SSL context, an identity hint if one was provided
+    /// by the server, a mutable slice for each of the identity and pre-shared key bytes. The
+    /// identity must be written as a null-terminated C string.
+    #[corresponds(SSL_CTX_set_psk_client_callback)]
+    #[cfg(not(osslconf = "OPENSSL_NO_PSK"))]
+    pub fn set_psk_client_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, Option<&[u8]>, &mut [u8], &mut [u8]) -> Result<usize, ErrorStack>
+            + 'static
+            + Sync
+            + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_psk_client_callback(self.as_ptr(), Some(raw_client_psk::<F>));
+        }
+    }
+
+    #[deprecated(since = "0.10.10", note = "renamed to `set_psk_client_callback`")]
+    #[cfg(not(osslconf = "OPENSSL_NO_PSK"))]
+    pub fn set_psk_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, Option<&[u8]>, &mut [u8], &mut [u8]) -> Result<usize, ErrorStack>
+            + 'static
+            + Sync
+            + Send,
+    {
+        self.set_psk_client_callback(callback)
+    }
+
+    /// Sets the callback for providing an identity and pre-shared key for a TLS-PSK server.
+    ///
+    /// The callback will be called with the SSL context, an identity provided by the client,
+    /// and, a mutable slice for the pre-shared key bytes. The callback returns the number of
+    /// bytes in the pre-shared key.
+    #[corresponds(SSL_CTX_set_psk_server_callback)]
+    #[cfg(not(osslconf = "OPENSSL_NO_PSK"))]
+    pub fn set_psk_server_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, Option<&[u8]>, &mut [u8]) -> Result<usize, ErrorStack>
+            + 'static
+            + Sync
+            + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_psk_server_callback(self.as_ptr(), Some(raw_server_psk::<F>));
+        }
+    }
+
+    /// Sets the callback which is called when new sessions are negotiated.
+    ///
+    /// This can be used by clients to implement session caching. While in TLSv1.2 the session is
+    /// available to access via [`SslRef::session`] immediately after the handshake completes, this
+    /// is not the case for TLSv1.3. There, a session is not generally available immediately, and
+    /// the server may provide multiple session tokens to the client over a single session. The new
+    /// session callback is a portable way to deal with both cases.
+    ///
+    /// Note that session caching must be enabled for the callback to be invoked, and it defaults
+    /// off for clients. [`set_session_cache_mode`] controls that behavior.
+    ///
+    /// [`SslRef::session`]: struct.SslRef.html#method.session
+    /// [`set_session_cache_mode`]: #method.set_session_cache_mode
+    #[corresponds(SSL_CTX_sess_set_new_cb)]
+    pub fn set_new_session_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, SslSession) + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_sess_set_new_cb(self.as_ptr(), Some(callbacks::raw_new_session::<F>));
+        }
+    }
+
+    /// Sets the callback which is called when sessions are removed from the context.
+    ///
+    /// Sessions can be removed because they have timed out or because they are considered faulty.
+    #[corresponds(SSL_CTX_sess_set_remove_cb)]
+    pub fn set_remove_session_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&SslContextRef, &SslSessionRef) + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_sess_set_remove_cb(
+                self.as_ptr(),
+                Some(callbacks::raw_remove_session::<F>),
+            );
+        }
+    }
+
+    /// Sets the callback which is called when a client proposed to resume a session but it was not
+    /// found in the internal cache.
+    ///
+    /// The callback is passed a reference to the session ID provided by the client. It should
+    /// return the session corresponding to that ID if available. This is only used for servers, not
+    /// clients.
+    ///
+    /// # Safety
+    ///
+    /// The returned `SslSession` must not be associated with a different `SslContext`.
+    #[corresponds(SSL_CTX_sess_set_get_cb)]
+    pub unsafe fn set_get_session_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &[u8]) -> Option<SslSession> + 'static + Sync + Send,
+    {
+        self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+        ffi::SSL_CTX_sess_set_get_cb(self.as_ptr(), Some(callbacks::raw_get_session::<F>));
+    }
+
+    /// Sets the TLS key logging callback.
+    ///
+    /// The callback is invoked whenever TLS key material is generated, and is passed a line of NSS
+    /// SSLKEYLOGFILE-formatted text. This can be used by tools like Wireshark to decrypt message
+    /// traffic. The line does not contain a trailing newline.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CTX_set_keylog_callback)]
+    #[cfg(ossl111)]
+    pub fn set_keylog_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&SslRef, &str) + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_keylog_callback(self.as_ptr(), Some(callbacks::raw_keylog::<F>));
+        }
+    }
+
+    /// Sets the session caching mode use for connections made with the context.
+    ///
+    /// Returns the previous session caching mode.
+    #[corresponds(SSL_CTX_set_session_cache_mode)]
+    pub fn set_session_cache_mode(&mut self, mode: SslSessionCacheMode) -> SslSessionCacheMode {
+        unsafe {
+            let bits = ffi::SSL_CTX_set_session_cache_mode(self.as_ptr(), mode.bits());
+            SslSessionCacheMode { bits }
+        }
+    }
+
+    /// Sets the callback for generating an application cookie for TLS1.3
+    /// stateless handshakes.
+    ///
+    /// The callback will be called with the SSL context and a slice into which the cookie
+    /// should be written. The callback should return the number of bytes written.
+    #[corresponds(SSL_CTX_set_stateless_cookie_generate_cb)]
+    #[cfg(ossl111)]
+    pub fn set_stateless_cookie_generate_cb<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &mut [u8]) -> Result<usize, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_stateless_cookie_generate_cb(
+                self.as_ptr(),
+                Some(raw_stateless_cookie_generate::<F>),
+            );
+        }
+    }
+
+    /// Sets the callback for verifying an application cookie for TLS1.3
+    /// stateless handshakes.
+    ///
+    /// The callback will be called with the SSL context and the cookie supplied by the
+    /// client. It should return true if and only if the cookie is valid.
+    ///
+    /// Note that the OpenSSL implementation independently verifies the integrity of
+    /// application cookies using an HMAC before invoking the supplied callback.
+    #[corresponds(SSL_CTX_set_stateless_cookie_verify_cb)]
+    #[cfg(ossl111)]
+    pub fn set_stateless_cookie_verify_cb<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &[u8]) -> bool + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_stateless_cookie_verify_cb(
+                self.as_ptr(),
+                Some(raw_stateless_cookie_verify::<F>),
+            )
+        }
+    }
+
+    /// Sets the callback for generating a DTLSv1 cookie
+    ///
+    /// The callback will be called with the SSL context and a slice into which the cookie
+    /// should be written. The callback should return the number of bytes written.
+    #[corresponds(SSL_CTX_set_cookie_generate_cb)]
+    #[cfg(not(boringssl))]
+    pub fn set_cookie_generate_cb<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &mut [u8]) -> Result<usize, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_cookie_generate_cb(self.as_ptr(), Some(raw_cookie_generate::<F>));
+        }
+    }
+
+    /// Sets the callback for verifying a DTLSv1 cookie
+    ///
+    /// The callback will be called with the SSL context and the cookie supplied by the
+    /// client. It should return true if and only if the cookie is valid.
+    #[corresponds(SSL_CTX_set_cookie_verify_cb)]
+    #[cfg(not(boringssl))]
+    pub fn set_cookie_verify_cb<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &[u8]) -> bool + 'static + Sync + Send,
+    {
+        unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_cookie_verify_cb(self.as_ptr(), Some(raw_cookie_verify::<F>));
+        }
+    }
+
+    /// Sets the extra data at the specified index.
+    ///
+    /// This can be used to provide data to callbacks registered with the context. Use the
+    /// `SslContext::new_ex_index` method to create an `Index`.
+    #[corresponds(SSL_CTX_set_ex_data)]
+    pub fn set_ex_data<T>(&mut self, index: Index<SslContext, T>, data: T) {
+        self.set_ex_data_inner(index, data);
+    }
+
+    fn set_ex_data_inner<T>(&mut self, index: Index<SslContext, T>, data: T) -> *mut c_void {
+        unsafe {
+            let data = Box::into_raw(Box::new(data)) as *mut c_void;
+            ffi::SSL_CTX_set_ex_data(self.as_ptr(), index.as_raw(), data);
+            data
+        }
+    }
+
+    /// Adds a custom extension for a TLS/DTLS client or server for all supported protocol versions.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CTX_add_custom_ext)]
+    #[cfg(ossl111)]
+    pub fn add_custom_ext<AddFn, ParseFn, T>(
+        &mut self,
+        ext_type: u16,
+        context: ExtensionContext,
+        add_cb: AddFn,
+        parse_cb: ParseFn,
+    ) -> Result<(), ErrorStack>
+    where
+        AddFn: Fn(
+                &mut SslRef,
+                ExtensionContext,
+                Option<(usize, &X509Ref)>,
+            ) -> Result<Option<T>, SslAlert>
+            + 'static
+            + Sync
+            + Send,
+        T: AsRef<[u8]> + 'static + Sync + Send,
+        ParseFn: Fn(
+                &mut SslRef,
+                ExtensionContext,
+                &[u8],
+                Option<(usize, &X509Ref)>,
+            ) -> Result<(), SslAlert>
+            + 'static
+            + Sync
+            + Send,
+    {
+        let ret = unsafe {
+            self.set_ex_data(SslContext::cached_ex_index::<AddFn>(), add_cb);
+            self.set_ex_data(SslContext::cached_ex_index::<ParseFn>(), parse_cb);
+
+            ffi::SSL_CTX_add_custom_ext(
+                self.as_ptr(),
+                ext_type as c_uint,
+                context.bits(),
+                Some(raw_custom_ext_add::<AddFn, T>),
+                Some(raw_custom_ext_free::<T>),
+                ptr::null_mut(),
+                Some(raw_custom_ext_parse::<ParseFn>),
+                ptr::null_mut(),
+            )
+        };
+        if ret == 1 {
+            Ok(())
+        } else {
+            Err(ErrorStack::get())
+        }
+    }
+
+    /// Sets the maximum amount of early data that will be accepted on incoming connections.
+    ///
+    /// Defaults to 0.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_CTX_set_max_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn set_max_early_data(&mut self, bytes: u32) -> Result<(), ErrorStack> {
+        if unsafe { ffi::SSL_CTX_set_max_early_data(self.as_ptr(), bytes) } == 1 {
+            Ok(())
+        } else {
+            Err(ErrorStack::get())
+        }
+    }
+
+    /// Sets a callback which will be invoked just after the client's hello message is received.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CTX_set_client_hello_cb)]
+    #[cfg(ossl111)]
+    pub fn set_client_hello_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &mut SslAlert) -> Result<ClientHelloResponse, ErrorStack>
+            + 'static
+            + Sync
+            + Send,
+    {
+        unsafe {
+            let ptr = self.set_ex_data_inner(SslContext::cached_ex_index::<F>(), callback);
+            ffi::SSL_CTX_set_client_hello_cb(
+                self.as_ptr(),
+                Some(callbacks::raw_client_hello::<F>),
+                ptr,
+            );
+        }
+    }
+
+    /// Sets the context's session cache size limit, returning the previous limit.
+    ///
+    /// A value of 0 means that the cache size is unbounded.
+    #[corresponds(SSL_CTX_sess_set_cache_size)]
+    #[allow(clippy::useless_conversion)]
+    pub fn set_session_cache_size(&mut self, size: i32) -> i64 {
+        unsafe {
+            ffi::SSL_CTX_sess_set_cache_size(self.as_ptr(), size as SslCacheSize) as SslCacheTy
+        }
+    }
+
+    /// Sets the context's supported signature algorithms.
+    ///
+    /// Requires OpenSSL 1.0.2 or newer.
+    #[corresponds(SSL_CTX_set1_sigalgs_list)]
+    #[cfg(ossl102)]
+    pub fn set_sigalgs_list(&mut self, sigalgs: &str) -> Result<(), ErrorStack> {
+        let sigalgs = CString::new(sigalgs).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_set1_sigalgs_list(self.as_ptr(), sigalgs.as_ptr()) as c_int)
+                .map(|_| ())
+        }
+    }
+
+    /// Sets the context's supported elliptic curve groups.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 2.5.1 or newer.
+    #[corresponds(SSL_CTX_set1_groups_list)]
+    #[cfg(any(ossl111, libressl251))]
+    pub fn set_groups_list(&mut self, groups: &str) -> Result<(), ErrorStack> {
+        let groups = CString::new(groups).unwrap();
+        unsafe {
+            cvt(ffi::SSL_CTX_set1_groups_list(self.as_ptr(), groups.as_ptr()) as c_int).map(|_| ())
+        }
+    }
+
+    /// Sets the number of TLS 1.3 session tickets that will be sent to a client after a full
+    /// handshake.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CTX_set_num_tickets)]
+    #[cfg(ossl111)]
+    pub fn set_num_tickets(&mut self, num_tickets: usize) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_CTX_set_num_tickets(self.as_ptr(), num_tickets)).map(|_| ()) }
+    }
+
+    /// Consumes the builder, returning a new `SslContext`.
+    pub fn build(self) -> SslContext {
+        self.0
+    }
+}
+
+foreign_type_and_impl_send_sync! {
+    type CType = ffi::SSL_CTX;
+    fn drop = ffi::SSL_CTX_free;
+
+    /// A context object for TLS streams.
+    ///
+    /// Applications commonly configure a single `SslContext` that is shared by all of its
+    /// `SslStreams`.
+    pub struct SslContext;
+
+    /// Reference to [`SslContext`]
+    ///
+    /// [`SslContext`]: struct.SslContext.html
+    pub struct SslContextRef;
+}
+
+impl Clone for SslContext {
+    fn clone(&self) -> Self {
+        (**self).to_owned()
+    }
+}
+
+impl ToOwned for SslContextRef {
+    type Owned = SslContext;
+
+    fn to_owned(&self) -> Self::Owned {
+        unsafe {
+            SSL_CTX_up_ref(self.as_ptr());
+            SslContext::from_ptr(self.as_ptr())
+        }
+    }
+}
+
+// TODO: add useful info here
+impl fmt::Debug for SslContext {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "SslContext")
+    }
+}
+
+impl SslContext {
+    /// Creates a new builder object for an `SslContext`.
+    pub fn builder(method: SslMethod) -> Result<SslContextBuilder, ErrorStack> {
+        SslContextBuilder::new(method)
+    }
+
+    /// Returns a new extra data index.
+    ///
+    /// Each invocation of this function is guaranteed to return a distinct index. These can be used
+    /// to store data in the context that can be retrieved later by callbacks, for example.
+    #[corresponds(SSL_CTX_get_ex_new_index)]
+    pub fn new_ex_index<T>() -> Result<Index<SslContext, T>, ErrorStack>
+    where
+        T: 'static + Sync + Send,
+    {
+        unsafe {
+            ffi::init();
+            #[cfg(boringssl)]
+            let idx = cvt_n(get_new_idx(Some(free_data_box::<T>)))?;
+            #[cfg(not(boringssl))]
+            let idx = cvt_n(get_new_idx(free_data_box::<T>))?;
+            Ok(Index::from_raw(idx))
+        }
+    }
+
+    // FIXME should return a result?
+    fn cached_ex_index<T>() -> Index<SslContext, T>
+    where
+        T: 'static + Sync + Send,
+    {
+        unsafe {
+            let idx = *INDEXES
+                .lock()
+                .unwrap_or_else(|e| e.into_inner())
+                .entry(TypeId::of::<T>())
+                .or_insert_with(|| SslContext::new_ex_index::<T>().unwrap().as_raw());
+            Index::from_raw(idx)
+        }
+    }
+}
+
+impl SslContextRef {
+    /// Returns the certificate associated with this `SslContext`, if present.
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_CTX_get0_certificate)]
+    #[cfg(any(ossl102, libressl270))]
+    pub fn certificate(&self) -> Option<&X509Ref> {
+        unsafe {
+            let ptr = ffi::SSL_CTX_get0_certificate(self.as_ptr());
+            X509Ref::from_const_ptr_opt(ptr)
+        }
+    }
+
+    /// Returns the private key associated with this `SslContext`, if present.
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_CTX_get0_privatekey)]
+    #[cfg(any(ossl102, libressl340))]
+    pub fn private_key(&self) -> Option<&PKeyRef<Private>> {
+        unsafe {
+            let ptr = ffi::SSL_CTX_get0_privatekey(self.as_ptr());
+            PKeyRef::from_const_ptr_opt(ptr)
+        }
+    }
+
+    /// Returns a shared reference to the certificate store used for verification.
+    #[corresponds(SSL_CTX_get_cert_store)]
+    pub fn cert_store(&self) -> &X509StoreRef {
+        unsafe { X509StoreRef::from_ptr(ffi::SSL_CTX_get_cert_store(self.as_ptr())) }
+    }
+
+    /// Returns a shared reference to the stack of certificates making up the chain from the leaf.
+    #[corresponds(SSL_CTX_get_extra_chain_certs)]
+    pub fn extra_chain_certs(&self) -> &StackRef<X509> {
+        unsafe {
+            let mut chain = ptr::null_mut();
+            ffi::SSL_CTX_get_extra_chain_certs(self.as_ptr(), &mut chain);
+            StackRef::from_const_ptr_opt(chain).expect("extra chain certs must not be null")
+        }
+    }
+
+    /// Returns a reference to the extra data at the specified index.
+    #[corresponds(SSL_CTX_get_ex_data)]
+    pub fn ex_data<T>(&self, index: Index<SslContext, T>) -> Option<&T> {
+        unsafe {
+            let data = ffi::SSL_CTX_get_ex_data(self.as_ptr(), index.as_raw());
+            if data.is_null() {
+                None
+            } else {
+                Some(&*(data as *const T))
+            }
+        }
+    }
+
+    /// Gets the maximum amount of early data that will be accepted on incoming connections.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_CTX_get_max_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn max_early_data(&self) -> u32 {
+        unsafe { ffi::SSL_CTX_get_max_early_data(self.as_ptr()) }
+    }
+
+    /// Adds a session to the context's cache.
+    ///
+    /// Returns `true` if the session was successfully added to the cache, and `false` if it was already present.
+    ///
+    /// # Safety
+    ///
+    /// The caller of this method is responsible for ensuring that the session has never been used with another
+    /// `SslContext` than this one.
+    #[corresponds(SSL_CTX_add_session)]
+    pub unsafe fn add_session(&self, session: &SslSessionRef) -> bool {
+        ffi::SSL_CTX_add_session(self.as_ptr(), session.as_ptr()) != 0
+    }
+
+    /// Removes a session from the context's cache and marks it as non-resumable.
+    ///
+    /// Returns `true` if the session was successfully found and removed, and `false` otherwise.
+    ///
+    /// # Safety
+    ///
+    /// The caller of this method is responsible for ensuring that the session has never been used with another
+    /// `SslContext` than this one.
+    #[corresponds(SSL_CTX_remove_session)]
+    pub unsafe fn remove_session(&self, session: &SslSessionRef) -> bool {
+        ffi::SSL_CTX_remove_session(self.as_ptr(), session.as_ptr()) != 0
+    }
+
+    /// Returns the context's session cache size limit.
+    ///
+    /// A value of 0 means that the cache size is unbounded.
+    #[corresponds(SSL_CTX_sess_get_cache_size)]
+    #[allow(clippy::unnecessary_cast)]
+    pub fn session_cache_size(&self) -> i64 {
+        unsafe { ffi::SSL_CTX_sess_get_cache_size(self.as_ptr()) as i64 }
+    }
+
+    /// Returns the verify mode that was set on this context from [`SslContextBuilder::set_verify`].
+    ///
+    /// [`SslContextBuilder::set_verify`]: struct.SslContextBuilder.html#method.set_verify
+    #[corresponds(SSL_CTX_get_verify_mode)]
+    pub fn verify_mode(&self) -> SslVerifyMode {
+        let mode = unsafe { ffi::SSL_CTX_get_verify_mode(self.as_ptr()) };
+        SslVerifyMode::from_bits(mode).expect("SSL_CTX_get_verify_mode returned invalid mode")
+    }
+
+    /// Gets the number of TLS 1.3 session tickets that will be sent to a client after a full
+    /// handshake.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CTX_get_num_tickets)]
+    #[cfg(ossl111)]
+    pub fn num_tickets(&self) -> usize {
+        unsafe { ffi::SSL_CTX_get_num_tickets(self.as_ptr()) }
+    }
+}
+
+/// Information about the state of a cipher.
+pub struct CipherBits {
+    /// The number of secret bits used for the cipher.
+    pub secret: i32,
+
+    /// The number of bits processed by the chosen algorithm.
+    pub algorithm: i32,
+}
+
+/// Information about a cipher.
+pub struct SslCipher(*mut ffi::SSL_CIPHER);
+
+impl ForeignType for SslCipher {
+    type CType = ffi::SSL_CIPHER;
+    type Ref = SslCipherRef;
+
+    #[inline]
+    unsafe fn from_ptr(ptr: *mut ffi::SSL_CIPHER) -> SslCipher {
+        SslCipher(ptr)
+    }
+
+    #[inline]
+    fn as_ptr(&self) -> *mut ffi::SSL_CIPHER {
+        self.0
+    }
+}
+
+impl Deref for SslCipher {
+    type Target = SslCipherRef;
+
+    fn deref(&self) -> &SslCipherRef {
+        unsafe { SslCipherRef::from_ptr(self.0) }
+    }
+}
+
+impl DerefMut for SslCipher {
+    fn deref_mut(&mut self) -> &mut SslCipherRef {
+        unsafe { SslCipherRef::from_ptr_mut(self.0) }
+    }
+}
+
+/// Reference to an [`SslCipher`].
+///
+/// [`SslCipher`]: struct.SslCipher.html
+pub struct SslCipherRef(Opaque);
+
+impl ForeignTypeRef for SslCipherRef {
+    type CType = ffi::SSL_CIPHER;
+}
+
+impl SslCipherRef {
+    /// Returns the name of the cipher.
+    #[corresponds(SSL_CIPHER_get_name)]
+    pub fn name(&self) -> &'static str {
+        unsafe {
+            let ptr = ffi::SSL_CIPHER_get_name(self.as_ptr());
+            CStr::from_ptr(ptr).to_str().unwrap()
+        }
+    }
+
+    /// Returns the RFC-standard name of the cipher, if one exists.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CIPHER_standard_name)]
+    #[cfg(ossl111)]
+    pub fn standard_name(&self) -> Option<&'static str> {
+        unsafe {
+            let ptr = ffi::SSL_CIPHER_standard_name(self.as_ptr());
+            if ptr.is_null() {
+                None
+            } else {
+                Some(CStr::from_ptr(ptr).to_str().unwrap())
+            }
+        }
+    }
+
+    /// Returns the SSL/TLS protocol version that first defined the cipher.
+    #[corresponds(SSL_CIPHER_get_version)]
+    pub fn version(&self) -> &'static str {
+        let version = unsafe {
+            let ptr = ffi::SSL_CIPHER_get_version(self.as_ptr());
+            CStr::from_ptr(ptr as *const _)
+        };
+
+        str::from_utf8(version.to_bytes()).unwrap()
+    }
+
+    /// Returns the number of bits used for the cipher.
+    #[corresponds(SSL_CIPHER_get_bits)]
+    #[allow(clippy::useless_conversion)]
+    pub fn bits(&self) -> CipherBits {
+        unsafe {
+            let mut algo_bits = 0;
+            let secret_bits = ffi::SSL_CIPHER_get_bits(self.as_ptr(), &mut algo_bits);
+            CipherBits {
+                secret: secret_bits.into(),
+                algorithm: algo_bits.into(),
+            }
+        }
+    }
+
+    /// Returns a textual description of the cipher.
+    #[corresponds(SSL_CIPHER_description)]
+    pub fn description(&self) -> String {
+        unsafe {
+            // SSL_CIPHER_description requires a buffer of at least 128 bytes.
+            let mut buf = [0; 128];
+            let ptr = ffi::SSL_CIPHER_description(self.as_ptr(), buf.as_mut_ptr(), 128);
+            String::from_utf8(CStr::from_ptr(ptr as *const _).to_bytes().to_vec()).unwrap()
+        }
+    }
+
+    /// Returns the handshake digest of the cipher.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_CIPHER_get_handshake_digest)]
+    #[cfg(ossl111)]
+    pub fn handshake_digest(&self) -> Option<MessageDigest> {
+        unsafe {
+            let ptr = ffi::SSL_CIPHER_get_handshake_digest(self.as_ptr());
+            if ptr.is_null() {
+                None
+            } else {
+                Some(MessageDigest::from_ptr(ptr))
+            }
+        }
+    }
+
+    /// Returns the NID corresponding to the cipher.
+    ///
+    /// Requires OpenSSL 1.1.0 or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_CIPHER_get_cipher_nid)]
+    #[cfg(any(ossl110, libressl270))]
+    pub fn cipher_nid(&self) -> Option<Nid> {
+        let n = unsafe { ffi::SSL_CIPHER_get_cipher_nid(self.as_ptr()) };
+        if n == 0 {
+            None
+        } else {
+            Some(Nid::from_raw(n))
+        }
+    }
+}
+
+foreign_type_and_impl_send_sync! {
+    type CType = ffi::SSL_SESSION;
+    fn drop = ffi::SSL_SESSION_free;
+
+    /// An encoded SSL session.
+    ///
+    /// These can be cached to share sessions across connections.
+    pub struct SslSession;
+
+    /// Reference to [`SslSession`].
+    ///
+    /// [`SslSession`]: struct.SslSession.html
+    pub struct SslSessionRef;
+}
+
+impl Clone for SslSession {
+    fn clone(&self) -> SslSession {
+        SslSessionRef::to_owned(self)
+    }
+}
+
+impl SslSession {
+    from_der! {
+        /// Deserializes a DER-encoded session structure.
+        #[corresponds(d2i_SSL_SESSION)]
+        from_der,
+        SslSession,
+        ffi::d2i_SSL_SESSION
+    }
+}
+
+impl ToOwned for SslSessionRef {
+    type Owned = SslSession;
+
+    fn to_owned(&self) -> SslSession {
+        unsafe {
+            SSL_SESSION_up_ref(self.as_ptr());
+            SslSession(self.as_ptr())
+        }
+    }
+}
+
+impl SslSessionRef {
+    /// Returns the SSL session ID.
+    #[corresponds(SSL_SESSION_get_id)]
+    pub fn id(&self) -> &[u8] {
+        unsafe {
+            let mut len = 0;
+            let p = ffi::SSL_SESSION_get_id(self.as_ptr(), &mut len);
+            slice::from_raw_parts(p as *const u8, len as usize)
+        }
+    }
+
+    /// Returns the length of the master key.
+    #[corresponds(SSL_SESSION_get_master_key)]
+    pub fn master_key_len(&self) -> usize {
+        unsafe { SSL_SESSION_get_master_key(self.as_ptr(), ptr::null_mut(), 0) }
+    }
+
+    /// Copies the master key into the provided buffer.
+    ///
+    /// Returns the number of bytes written, or the size of the master key if the buffer is empty.
+    #[corresponds(SSL_SESSION_get_master_key)]
+    pub fn master_key(&self, buf: &mut [u8]) -> usize {
+        unsafe { SSL_SESSION_get_master_key(self.as_ptr(), buf.as_mut_ptr(), buf.len()) }
+    }
+
+    /// Gets the maximum amount of early data that can be sent on this session.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_SESSION_get_max_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn max_early_data(&self) -> u32 {
+        unsafe { ffi::SSL_SESSION_get_max_early_data(self.as_ptr()) }
+    }
+
+    /// Returns the time at which the session was established, in seconds since the Unix epoch.
+    #[corresponds(SSL_SESSION_get_time)]
+    #[allow(clippy::useless_conversion)]
+    pub fn time(&self) -> SslTimeTy {
+        unsafe { ffi::SSL_SESSION_get_time(self.as_ptr()) }
+    }
+
+    /// Returns the sessions timeout, in seconds.
+    ///
+    /// A session older than this time should not be used for session resumption.
+    #[corresponds(SSL_SESSION_get_timeout)]
+    #[allow(clippy::useless_conversion)]
+    pub fn timeout(&self) -> i64 {
+        unsafe { ffi::SSL_SESSION_get_timeout(self.as_ptr()).into() }
+    }
+
+    /// Returns the session's TLS protocol version.
+    ///
+    /// Requires OpenSSL 1.1.0 or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_SESSION_get_protocol_version)]
+    #[cfg(any(ossl110, libressl270))]
+    pub fn protocol_version(&self) -> SslVersion {
+        unsafe {
+            let version = ffi::SSL_SESSION_get_protocol_version(self.as_ptr());
+            SslVersion(version)
+        }
+    }
+
+    to_der! {
+        /// Serializes the session into a DER-encoded structure.
+        #[corresponds(i2d_SSL_SESSION)]
+        to_der,
+        ffi::i2d_SSL_SESSION
+    }
+}
+
+foreign_type_and_impl_send_sync! {
+    type CType = ffi::SSL;
+    fn drop = ffi::SSL_free;
+
+    /// The state of an SSL/TLS session.
+    ///
+    /// `Ssl` objects are created from an [`SslContext`], which provides configuration defaults.
+    /// These defaults can be overridden on a per-`Ssl` basis, however.
+    ///
+    /// [`SslContext`]: struct.SslContext.html
+    pub struct Ssl;
+
+    /// Reference to an [`Ssl`].
+    ///
+    /// [`Ssl`]: struct.Ssl.html
+    pub struct SslRef;
+}
+
+impl fmt::Debug for Ssl {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, fmt)
+    }
+}
+
+impl Ssl {
+    /// Returns a new extra data index.
+    ///
+    /// Each invocation of this function is guaranteed to return a distinct index. These can be used
+    /// to store data in the context that can be retrieved later by callbacks, for example.
+    #[corresponds(SSL_get_ex_new_index)]
+    pub fn new_ex_index<T>() -> Result<Index<Ssl, T>, ErrorStack>
+    where
+        T: 'static + Sync + Send,
+    {
+        unsafe {
+            ffi::init();
+            #[cfg(boringssl)]
+            let idx = cvt_n(get_new_ssl_idx(Some(free_data_box::<T>)))?;
+            #[cfg(not(boringssl))]
+            let idx = cvt_n(get_new_ssl_idx(free_data_box::<T>))?;
+            Ok(Index::from_raw(idx))
+        }
+    }
+
+    // FIXME should return a result?
+    fn cached_ex_index<T>() -> Index<Ssl, T>
+    where
+        T: 'static + Sync + Send,
+    {
+        unsafe {
+            let idx = *SSL_INDEXES
+                .lock()
+                .unwrap_or_else(|e| e.into_inner())
+                .entry(TypeId::of::<T>())
+                .or_insert_with(|| Ssl::new_ex_index::<T>().unwrap().as_raw());
+            Index::from_raw(idx)
+        }
+    }
+
+    /// Creates a new `Ssl`.
+    ///
+    /// This corresponds to [`SSL_new`].
+    ///
+    /// [`SSL_new`]: https://www.openssl.org/docs/manmaster/ssl/SSL_new.html
+    #[corresponds(SSL_new)]
+    pub fn new(ctx: &SslContextRef) -> Result<Ssl, ErrorStack> {
+        let session_ctx_index = try_get_session_ctx_index()?;
+        unsafe {
+            let ptr = cvt_p(ffi::SSL_new(ctx.as_ptr()))?;
+            let mut ssl = Ssl::from_ptr(ptr);
+            ssl.set_ex_data(*session_ctx_index, ctx.to_owned());
+
+            Ok(ssl)
+        }
+    }
+
+    /// Initiates a client-side TLS handshake.
+    ///
+    /// This corresponds to [`SSL_connect`].
+    ///
+    /// # Warning
+    ///
+    /// OpenSSL's default configuration is insecure. It is highly recommended to use
+    /// `SslConnector` rather than `Ssl` directly, as it manages that configuration.
+    ///
+    /// [`SSL_connect`]: https://www.openssl.org/docs/manmaster/man3/SSL_connect.html
+    #[corresponds(SSL_connect)]
+    #[allow(deprecated)]
+    pub fn connect<S>(self, stream: S) -> Result<SslStream<S>, HandshakeError<S>>
+    where
+        S: Read + Write,
+    {
+        SslStreamBuilder::new(self, stream).connect()
+    }
+
+    /// Initiates a server-side TLS handshake.
+    ///
+    /// This corresponds to [`SSL_accept`].
+    ///
+    /// # Warning
+    ///
+    /// OpenSSL's default configuration is insecure. It is highly recommended to use
+    /// `SslAcceptor` rather than `Ssl` directly, as it manages that configuration.
+    ///
+    /// [`SSL_accept`]: https://www.openssl.org/docs/manmaster/man3/SSL_accept.html
+    #[corresponds(SSL_accept)]
+    #[allow(deprecated)]
+    pub fn accept<S>(self, stream: S) -> Result<SslStream<S>, HandshakeError<S>>
+    where
+        S: Read + Write,
+    {
+        SslStreamBuilder::new(self, stream).accept()
+    }
+}
+
+impl fmt::Debug for SslRef {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("Ssl")
+            .field("state", &self.state_string_long())
+            .field("verify_result", &self.verify_result())
+            .finish()
+    }
+}
+
+impl SslRef {
+    fn get_raw_rbio(&self) -> *mut ffi::BIO {
+        unsafe { ffi::SSL_get_rbio(self.as_ptr()) }
+    }
+
+    fn read(&mut self, buf: &mut [u8]) -> c_int {
+        let len = cmp::min(c_int::max_value() as usize, buf.len()) as c_int;
+        unsafe { ffi::SSL_read(self.as_ptr(), buf.as_ptr() as *mut c_void, len) }
+    }
+
+    fn peek(&mut self, buf: &mut [u8]) -> c_int {
+        let len = cmp::min(c_int::max_value() as usize, buf.len()) as c_int;
+        unsafe { ffi::SSL_peek(self.as_ptr(), buf.as_ptr() as *mut c_void, len) }
+    }
+
+    fn write(&mut self, buf: &[u8]) -> c_int {
+        let len = cmp::min(c_int::max_value() as usize, buf.len()) as c_int;
+        unsafe { ffi::SSL_write(self.as_ptr(), buf.as_ptr() as *const c_void, len) }
+    }
+
+    fn get_error(&self, ret: c_int) -> ErrorCode {
+        unsafe { ErrorCode::from_raw(ffi::SSL_get_error(self.as_ptr(), ret)) }
+    }
+
+    /// Configure as an outgoing stream from a client.
+    #[corresponds(SSL_set_connect_state)]
+    pub fn set_connect_state(&mut self) {
+        unsafe { ffi::SSL_set_connect_state(self.as_ptr()) }
+    }
+
+    /// Configure as an incoming stream to a server.
+    #[corresponds(SSL_set_accept_state)]
+    pub fn set_accept_state(&mut self) {
+        unsafe { ffi::SSL_set_accept_state(self.as_ptr()) }
+    }
+
+    /// Like [`SslContextBuilder::set_verify`].
+    ///
+    /// [`SslContextBuilder::set_verify`]: struct.SslContextBuilder.html#method.set_verify
+    #[corresponds(SSL_set_verify)]
+    pub fn set_verify(&mut self, mode: SslVerifyMode) {
+        unsafe { ffi::SSL_set_verify(self.as_ptr(), mode.bits as c_int, None) }
+    }
+
+    /// Returns the verify mode that was set using `set_verify`.
+    #[corresponds(SSL_set_verify_mode)]
+    pub fn verify_mode(&self) -> SslVerifyMode {
+        let mode = unsafe { ffi::SSL_get_verify_mode(self.as_ptr()) };
+        SslVerifyMode::from_bits(mode).expect("SSL_get_verify_mode returned invalid mode")
+    }
+
+    /// Like [`SslContextBuilder::set_verify_callback`].
+    ///
+    /// [`SslContextBuilder::set_verify_callback`]: struct.SslContextBuilder.html#method.set_verify_callback
+    #[corresponds(SSL_set_verify)]
+    pub fn set_verify_callback<F>(&mut self, mode: SslVerifyMode, verify: F)
+    where
+        F: Fn(bool, &mut X509StoreContextRef) -> bool + 'static + Sync + Send,
+    {
+        unsafe {
+            // this needs to be in an Arc since the callback can register a new callback!
+            self.set_ex_data(Ssl::cached_ex_index(), Arc::new(verify));
+            ffi::SSL_set_verify(self.as_ptr(), mode.bits as c_int, Some(ssl_raw_verify::<F>));
+        }
+    }
+
+    /// Like [`SslContextBuilder::set_tmp_dh`].
+    ///
+    /// [`SslContextBuilder::set_tmp_dh`]: struct.SslContextBuilder.html#method.set_tmp_dh
+    #[corresponds(SSL_set_tmp_dh)]
+    pub fn set_tmp_dh(&mut self, dh: &DhRef<Params>) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_set_tmp_dh(self.as_ptr(), dh.as_ptr()) as c_int).map(|_| ()) }
+    }
+
+    /// Like [`SslContextBuilder::set_tmp_dh_callback`].
+    ///
+    /// [`SslContextBuilder::set_tmp_dh_callback`]: struct.SslContextBuilder.html#method.set_tmp_dh_callback
+    #[corresponds(SSL_set_tmp_dh_callback)]
+    pub fn set_tmp_dh_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, bool, u32) -> Result<Dh<Params>, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            // this needs to be in an Arc since the callback can register a new callback!
+            self.set_ex_data(Ssl::cached_ex_index(), Arc::new(callback));
+            #[cfg(boringssl)]
+            ffi::SSL_set_tmp_dh_callback(self.as_ptr(), Some(raw_tmp_dh_ssl::<F>));
+            #[cfg(not(boringssl))]
+            ffi::SSL_set_tmp_dh_callback__fixed_rust(self.as_ptr(), Some(raw_tmp_dh_ssl::<F>));
+        }
+    }
+
+    /// Like [`SslContextBuilder::set_tmp_ecdh`].
+    ///
+    /// [`SslContextBuilder::set_tmp_ecdh`]: struct.SslContextBuilder.html#method.set_tmp_ecdh
+    #[corresponds(SSL_set_tmp_ecdh)]
+    pub fn set_tmp_ecdh(&mut self, key: &EcKeyRef<Params>) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_set_tmp_ecdh(self.as_ptr(), key.as_ptr()) as c_int).map(|_| ()) }
+    }
+
+    /// Like [`SslContextBuilder::set_tmp_ecdh_callback`].
+    ///
+    /// Requires OpenSSL 1.0.1 or 1.0.2.
+    #[corresponds(SSL_set_tmp_ecdh_callback)]
+    #[cfg(any(all(ossl101, not(ossl110))))]
+    #[deprecated(note = "this function leaks memory and does not exist on newer OpenSSL versions")]
+    pub fn set_tmp_ecdh_callback<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, bool, u32) -> Result<EcKey<Params>, ErrorStack> + 'static + Sync + Send,
+    {
+        unsafe {
+            // this needs to be in an Arc since the callback can register a new callback!
+            self.set_ex_data(Ssl::cached_ex_index(), Arc::new(callback));
+            ffi::SSL_set_tmp_ecdh_callback__fixed_rust(self.as_ptr(), Some(raw_tmp_ecdh_ssl::<F>));
+        }
+    }
+
+    /// Like [`SslContextBuilder::set_ecdh_auto`].
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL.
+    ///
+    /// [`SslContextBuilder::set_tmp_ecdh`]: struct.SslContextBuilder.html#method.set_tmp_ecdh
+    #[corresponds(SSL_set_ecdh_auto)]
+    #[cfg(any(all(ossl102, not(ossl110)), libressl))]
+    pub fn set_ecdh_auto(&mut self, onoff: bool) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_set_ecdh_auto(self.as_ptr(), onoff as c_int)).map(|_| ()) }
+    }
+
+    /// Like [`SslContextBuilder::set_alpn_protos`].
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL 2.6.1 or newer.
+    ///
+    /// [`SslContextBuilder::set_alpn_protos`]: struct.SslContextBuilder.html#method.set_alpn_protos
+    #[corresponds(SSL_set_alpn_protos)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn set_alpn_protos(&mut self, protocols: &[u8]) -> Result<(), ErrorStack> {
+        unsafe {
+            assert!(protocols.len() <= c_uint::max_value() as usize);
+            let r = ffi::SSL_set_alpn_protos(
+                self.as_ptr(),
+                protocols.as_ptr(),
+                protocols.len() as c_uint,
+            );
+            // fun fact, SSL_set_alpn_protos has a reversed return code D:
+            if r == 0 {
+                Ok(())
+            } else {
+                Err(ErrorStack::get())
+            }
+        }
+    }
+
+    /// Returns the current cipher if the session is active.
+    #[corresponds(SSL_get_current_cipher)]
+    pub fn current_cipher(&self) -> Option<&SslCipherRef> {
+        unsafe {
+            let ptr = ffi::SSL_get_current_cipher(self.as_ptr());
+
+            SslCipherRef::from_const_ptr_opt(ptr)
+        }
+    }
+
+    /// Returns a short string describing the state of the session.
+    #[corresponds(SSL_state_string)]
+    pub fn state_string(&self) -> &'static str {
+        let state = unsafe {
+            let ptr = ffi::SSL_state_string(self.as_ptr());
+            CStr::from_ptr(ptr as *const _)
+        };
+
+        str::from_utf8(state.to_bytes()).unwrap()
+    }
+
+    /// Returns a longer string describing the state of the session.
+    #[corresponds(SSL_state_string_long)]
+    pub fn state_string_long(&self) -> &'static str {
+        let state = unsafe {
+            let ptr = ffi::SSL_state_string_long(self.as_ptr());
+            CStr::from_ptr(ptr as *const _)
+        };
+
+        str::from_utf8(state.to_bytes()).unwrap()
+    }
+
+    /// Sets the host name to be sent to the server for Server Name Indication (SNI).
+    ///
+    /// It has no effect for a server-side connection.
+    #[corresponds(SSL_set_tlsext_host_name)]
+    pub fn set_hostname(&mut self, hostname: &str) -> Result<(), ErrorStack> {
+        let cstr = CString::new(hostname).unwrap();
+        unsafe {
+            cvt(ffi::SSL_set_tlsext_host_name(self.as_ptr(), cstr.as_ptr() as *mut _) as c_int)
+                .map(|_| ())
+        }
+    }
+
+    /// Returns the peer's certificate, if present.
+    #[corresponds(SSL_get_peer_certificate)]
+    pub fn peer_certificate(&self) -> Option<X509> {
+        unsafe {
+            let ptr = SSL_get1_peer_certificate(self.as_ptr());
+            X509::from_ptr_opt(ptr)
+        }
+    }
+
+    /// Returns the certificate chain of the peer, if present.
+    ///
+    /// On the client side, the chain includes the leaf certificate, but on the server side it does
+    /// not. Fun!
+    #[corresponds(SSL_get_peer_cert_chain)]
+    pub fn peer_cert_chain(&self) -> Option<&StackRef<X509>> {
+        unsafe {
+            let ptr = ffi::SSL_get_peer_cert_chain(self.as_ptr());
+            StackRef::from_const_ptr_opt(ptr)
+        }
+    }
+
+    /// Returns the verified certificate chain of the peer, including the leaf certificate.
+    ///
+    /// If verification was not successful (i.e. [`verify_result`] does not return
+    /// [`X509VerifyResult::OK`]), this chain may be incomplete or invalid.
+    ///
+    /// Requires OpenSSL 1.1.0 or newer.
+    ///
+    /// [`verify_result`]: #method.verify_result
+    /// [`X509VerifyResult::OK`]: ../x509/struct.X509VerifyResult.html#associatedconstant.OK
+    #[corresponds(SSL_get0_verified_chain)]
+    #[cfg(ossl110)]
+    pub fn verified_chain(&self) -> Option<&StackRef<X509>> {
+        unsafe {
+            let ptr = ffi::SSL_get0_verified_chain(self.as_ptr());
+            StackRef::from_const_ptr_opt(ptr)
+        }
+    }
+
+    /// Like [`SslContext::certificate`].
+    #[corresponds(SSL_get_certificate)]
+    pub fn certificate(&self) -> Option<&X509Ref> {
+        unsafe {
+            let ptr = ffi::SSL_get_certificate(self.as_ptr());
+            X509Ref::from_const_ptr_opt(ptr)
+        }
+    }
+
+    /// Like [`SslContext::private_key`].
+    ///
+    /// [`SslContext::private_key`]: struct.SslContext.html#method.private_key
+    #[corresponds(SSL_get_privatekey)]
+    pub fn private_key(&self) -> Option<&PKeyRef<Private>> {
+        unsafe {
+            let ptr = ffi::SSL_get_privatekey(self.as_ptr());
+            PKeyRef::from_const_ptr_opt(ptr)
+        }
+    }
+
+    #[deprecated(since = "0.10.5", note = "renamed to `version_str`")]
+    pub fn version(&self) -> &str {
+        self.version_str()
+    }
+
+    /// Returns the protocol version of the session.
+    #[corresponds(SSL_version)]
+    pub fn version2(&self) -> Option<SslVersion> {
+        unsafe {
+            let r = ffi::SSL_version(self.as_ptr());
+            if r == 0 {
+                None
+            } else {
+                Some(SslVersion(r))
+            }
+        }
+    }
+
+    /// Returns a string describing the protocol version of the session.
+    #[corresponds(SSL_get_version)]
+    pub fn version_str(&self) -> &'static str {
+        let version = unsafe {
+            let ptr = ffi::SSL_get_version(self.as_ptr());
+            CStr::from_ptr(ptr as *const _)
+        };
+
+        str::from_utf8(version.to_bytes()).unwrap()
+    }
+
+    /// Returns the protocol selected via Application Layer Protocol Negotiation (ALPN).
+    ///
+    /// The protocol's name is returned is an opaque sequence of bytes. It is up to the client
+    /// to interpret it.
+    ///
+    /// Requires OpenSSL 1.0.2 or LibreSSL 2.6.1 or newer.
+    #[corresponds(SSL_get0_alpn_selected)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn selected_alpn_protocol(&self) -> Option<&[u8]> {
+        unsafe {
+            let mut data: *const c_uchar = ptr::null();
+            let mut len: c_uint = 0;
+            // Get the negotiated protocol from the SSL instance.
+            // `data` will point at a `c_uchar` array; `len` will contain the length of this array.
+            ffi::SSL_get0_alpn_selected(self.as_ptr(), &mut data, &mut len);
+
+            if data.is_null() {
+                None
+            } else {
+                Some(slice::from_raw_parts(data, len as usize))
+            }
+        }
+    }
+
+    /// Enables the DTLS extension "use_srtp" as defined in RFC5764.
+    ///
+    /// This corresponds to [`SSL_set_tlsext_use_srtp`].
+    ///
+    /// [`SSL_set_tlsext_use_srtp`]: https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_tlsext_use_srtp.html
+    #[corresponds(SSL_set_tlsext_use_srtp)]
+    pub fn set_tlsext_use_srtp(&mut self, protocols: &str) -> Result<(), ErrorStack> {
+        unsafe {
+            let cstr = CString::new(protocols).unwrap();
+
+            let r = ffi::SSL_set_tlsext_use_srtp(self.as_ptr(), cstr.as_ptr());
+            // fun fact, set_tlsext_use_srtp has a reversed return code D:
+            if r == 0 {
+                Ok(())
+            } else {
+                Err(ErrorStack::get())
+            }
+        }
+    }
+
+    /// Gets all SRTP profiles that are enabled for handshake via set_tlsext_use_srtp
+    ///
+    /// DTLS extension "use_srtp" as defined in RFC5764 has to be enabled.
+    ///
+    /// This corresponds to [`SSL_get_srtp_profiles`].
+    ///
+    /// [`SSL_get_srtp_profiles`]: https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_tlsext_use_srtp.html
+    #[corresponds(SSL_get_srtp_profiles)]
+    pub fn srtp_profiles(&self) -> Option<&StackRef<SrtpProtectionProfile>> {
+        unsafe {
+            let chain = ffi::SSL_get_srtp_profiles(self.as_ptr());
+
+            StackRef::from_const_ptr_opt(chain)
+        }
+    }
+
+    /// Gets the SRTP profile selected by handshake.
+    ///
+    /// DTLS extension "use_srtp" as defined in RFC5764 has to be enabled.
+    #[corresponds(SSL_get_selected_srtp_profile)]
+    pub fn selected_srtp_profile(&self) -> Option<&SrtpProtectionProfileRef> {
+        unsafe {
+            let profile = ffi::SSL_get_selected_srtp_profile(self.as_ptr());
+
+            SrtpProtectionProfileRef::from_const_ptr_opt(profile)
+        }
+    }
+
+    /// Returns the number of bytes remaining in the currently processed TLS record.
+    ///
+    /// If this is greater than 0, the next call to `read` will not call down to the underlying
+    /// stream.
+    #[corresponds(SSL_pending)]
+    pub fn pending(&self) -> usize {
+        unsafe { ffi::SSL_pending(self.as_ptr()) as usize }
+    }
+
+    /// Returns the servername sent by the client via Server Name Indication (SNI).
+    ///
+    /// It is only useful on the server side.
+    ///
+    /// # Note
+    ///
+    /// While the SNI specification requires that servernames be valid domain names (and therefore
+    /// ASCII), OpenSSL does not enforce this restriction. If the servername provided by the client
+    /// is not valid UTF-8, this function will return `None`. The `servername_raw` method returns
+    /// the raw bytes and does not have this restriction.
+    ///
+    /// [`SSL_get_servername`]: https://www.openssl.org/docs/manmaster/man3/SSL_get_servername.html
+    #[corresponds(SSL_get_servername)]
+    // FIXME maybe rethink in 0.11?
+    pub fn servername(&self, type_: NameType) -> Option<&str> {
+        self.servername_raw(type_)
+            .and_then(|b| str::from_utf8(b).ok())
+    }
+
+    /// Returns the servername sent by the client via Server Name Indication (SNI).
+    ///
+    /// It is only useful on the server side.
+    ///
+    /// # Note
+    ///
+    /// Unlike `servername`, this method does not require the name be valid UTF-8.
+    #[corresponds(SSL_get_servername)]
+    pub fn servername_raw(&self, type_: NameType) -> Option<&[u8]> {
+        unsafe {
+            let name = ffi::SSL_get_servername(self.as_ptr(), type_.0);
+            if name.is_null() {
+                None
+            } else {
+                Some(CStr::from_ptr(name as *const _).to_bytes())
+            }
+        }
+    }
+
+    /// Changes the context corresponding to the current connection.
+    ///
+    /// It is most commonly used in the Server Name Indication (SNI) callback.
+    #[corresponds(SSL_set_SSL_CTX)]
+    pub fn set_ssl_context(&mut self, ctx: &SslContextRef) -> Result<(), ErrorStack> {
+        unsafe { cvt_p(ffi::SSL_set_SSL_CTX(self.as_ptr(), ctx.as_ptr())).map(|_| ()) }
+    }
+
+    /// Returns the context corresponding to the current connection.
+    #[corresponds(SSL_get_SSL_CTX)]
+    pub fn ssl_context(&self) -> &SslContextRef {
+        unsafe {
+            let ssl_ctx = ffi::SSL_get_SSL_CTX(self.as_ptr());
+            SslContextRef::from_ptr(ssl_ctx)
+        }
+    }
+
+    /// Returns a mutable reference to the X509 verification configuration.
+    ///
+    /// Requires OpenSSL 1.0.2 or newer.
+    #[corresponds(SSL_get0_param)]
+    #[cfg(any(ossl102, libressl261))]
+    pub fn param_mut(&mut self) -> &mut X509VerifyParamRef {
+        unsafe { X509VerifyParamRef::from_ptr_mut(ffi::SSL_get0_param(self.as_ptr())) }
+    }
+
+    /// Returns the certificate verification result.
+    #[corresponds(SSL_get_verify_result)]
+    pub fn verify_result(&self) -> X509VerifyResult {
+        unsafe { X509VerifyResult::from_raw(ffi::SSL_get_verify_result(self.as_ptr()) as c_int) }
+    }
+
+    /// Returns a shared reference to the SSL session.
+    #[corresponds(SSL_get_session)]
+    pub fn session(&self) -> Option<&SslSessionRef> {
+        unsafe {
+            let p = ffi::SSL_get_session(self.as_ptr());
+            SslSessionRef::from_const_ptr_opt(p)
+        }
+    }
+
+    /// Copies the `client_random` value sent by the client in the TLS handshake into a buffer.
+    ///
+    /// Returns the number of bytes copied, or if the buffer is empty, the size of the `client_random`
+    /// value.
+    ///
+    /// Requires OpenSSL 1.1.0 or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_get_client_random)]
+    #[cfg(any(ossl110, libressl270))]
+    pub fn client_random(&self, buf: &mut [u8]) -> usize {
+        unsafe {
+            ffi::SSL_get_client_random(self.as_ptr(), buf.as_mut_ptr() as *mut c_uchar, buf.len())
+        }
+    }
+
+    /// Copies the `server_random` value sent by the server in the TLS handshake into a buffer.
+    ///
+    /// Returns the number of bytes copied, or if the buffer is empty, the size of the `server_random`
+    /// value.
+    ///
+    /// Requires OpenSSL 1.1.0 or LibreSSL 2.7.0 or newer.
+    #[corresponds(SSL_get_server_random)]
+    #[cfg(any(ossl110, libressl270))]
+    pub fn server_random(&self, buf: &mut [u8]) -> usize {
+        unsafe {
+            ffi::SSL_get_server_random(self.as_ptr(), buf.as_mut_ptr() as *mut c_uchar, buf.len())
+        }
+    }
+
+    /// Derives keying material for application use in accordance to RFC 5705.
+    #[corresponds(SSL_export_keying_material)]
+    pub fn export_keying_material(
+        &self,
+        out: &mut [u8],
+        label: &str,
+        context: Option<&[u8]>,
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            let (context, contextlen, use_context) = match context {
+                Some(context) => (context.as_ptr() as *const c_uchar, context.len(), 1),
+                None => (ptr::null(), 0, 0),
+            };
+            cvt(ffi::SSL_export_keying_material(
+                self.as_ptr(),
+                out.as_mut_ptr() as *mut c_uchar,
+                out.len(),
+                label.as_ptr() as *const c_char,
+                label.len(),
+                context,
+                contextlen,
+                use_context,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Derives keying material for application use in accordance to RFC 5705.
+    ///
+    /// This function is only usable with TLSv1.3, wherein there is no distinction between an empty context and no
+    /// context. Therefore, unlike `export_keying_material`, `context` must always be supplied.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_export_keying_material_early)]
+    #[cfg(ossl111)]
+    pub fn export_keying_material_early(
+        &self,
+        out: &mut [u8],
+        label: &str,
+        context: &[u8],
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_export_keying_material_early(
+                self.as_ptr(),
+                out.as_mut_ptr() as *mut c_uchar,
+                out.len(),
+                label.as_ptr() as *const c_char,
+                label.len(),
+                context.as_ptr() as *const c_uchar,
+                context.len(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the session to be used.
+    ///
+    /// This should be called before the handshake to attempt to reuse a previously established
+    /// session. If the server is not willing to reuse the session, a new one will be transparently
+    /// negotiated.
+    ///
+    /// # Safety
+    ///
+    /// The caller of this method is responsible for ensuring that the session is associated
+    /// with the same `SslContext` as this `Ssl`.
+    #[corresponds(SSL_set_session)]
+    pub unsafe fn set_session(&mut self, session: &SslSessionRef) -> Result<(), ErrorStack> {
+        cvt(ffi::SSL_set_session(self.as_ptr(), session.as_ptr())).map(|_| ())
+    }
+
+    /// Determines if the session provided to `set_session` was successfully reused.
+    #[corresponds(SSL_session_reused)]
+    pub fn session_reused(&self) -> bool {
+        unsafe { ffi::SSL_session_reused(self.as_ptr()) != 0 }
+    }
+
+    /// Sets the status response a client wishes the server to reply with.
+    #[corresponds(SSL_set_tlsext_status_type)]
+    pub fn set_status_type(&mut self, type_: StatusType) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_set_tlsext_status_type(self.as_ptr(), type_.as_raw()) as c_int).map(|_| ())
+        }
+    }
+
+    /// Determines if current session used Extended Master Secret
+    ///
+    /// Returns `None` if the handshake is still in-progress.
+    #[corresponds(SSL_get_extms_support)]
+    #[cfg(ossl110)]
+    pub fn extms_support(&self) -> Option<bool> {
+        unsafe {
+            match ffi::SSL_get_extms_support(self.as_ptr()) {
+                -1 => None,
+                ret => Some(ret != 0),
+            }
+        }
+    }
+
+    /// Returns the server's OCSP response, if present.
+    #[corresponds(SSL_get_tlsext_status_ocsp_resp)]
+    #[cfg(not(boringssl))]
+    pub fn ocsp_status(&self) -> Option<&[u8]> {
+        unsafe {
+            let mut p = ptr::null_mut();
+            let len = ffi::SSL_get_tlsext_status_ocsp_resp(self.as_ptr(), &mut p);
+
+            if len < 0 {
+                None
+            } else {
+                Some(slice::from_raw_parts(p as *const u8, len as usize))
+            }
+        }
+    }
+
+    /// Sets the OCSP response to be returned to the client.
+    #[corresponds(SSL_set_tlsext_status_oscp_resp)]
+    #[cfg(not(boringssl))]
+    pub fn set_ocsp_status(&mut self, response: &[u8]) -> Result<(), ErrorStack> {
+        unsafe {
+            assert!(response.len() <= c_int::max_value() as usize);
+            let p = cvt_p(ffi::OPENSSL_malloc(response.len() as _))?;
+            ptr::copy_nonoverlapping(response.as_ptr(), p as *mut u8, response.len());
+            cvt(ffi::SSL_set_tlsext_status_ocsp_resp(
+                self.as_ptr(),
+                p as *mut c_uchar,
+                response.len() as c_long,
+            ) as c_int)
+            .map(|_| ())
+            .map_err(|e| {
+                ffi::OPENSSL_free(p);
+                e
+            })
+        }
+    }
+
+    /// Determines if this `Ssl` is configured for server-side or client-side use.
+    #[corresponds(SSL_is_server)]
+    pub fn is_server(&self) -> bool {
+        unsafe { SSL_is_server(self.as_ptr()) != 0 }
+    }
+
+    /// Sets the extra data at the specified index.
+    ///
+    /// This can be used to provide data to callbacks registered with the context. Use the
+    /// `Ssl::new_ex_index` method to create an `Index`.
+    #[corresponds(SSL_set_ex_data)]
+    pub fn set_ex_data<T>(&mut self, index: Index<Ssl, T>, data: T) {
+        unsafe {
+            let data = Box::new(data);
+            ffi::SSL_set_ex_data(
+                self.as_ptr(),
+                index.as_raw(),
+                Box::into_raw(data) as *mut c_void,
+            );
+        }
+    }
+
+    /// Returns a reference to the extra data at the specified index.
+    #[corresponds(SSL_get_ex_data)]
+    pub fn ex_data<T>(&self, index: Index<Ssl, T>) -> Option<&T> {
+        unsafe {
+            let data = ffi::SSL_get_ex_data(self.as_ptr(), index.as_raw());
+            if data.is_null() {
+                None
+            } else {
+                Some(&*(data as *const T))
+            }
+        }
+    }
+
+    /// Returns a mutable reference to the extra data at the specified index.
+    #[corresponds(SSL_get_ex_data)]
+    pub fn ex_data_mut<T>(&mut self, index: Index<Ssl, T>) -> Option<&mut T> {
+        unsafe {
+            let data = ffi::SSL_get_ex_data(self.as_ptr(), index.as_raw());
+            if data.is_null() {
+                None
+            } else {
+                Some(&mut *(data as *mut T))
+            }
+        }
+    }
+
+    /// Sets the maximum amount of early data that will be accepted on this connection.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_set_max_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn set_max_early_data(&mut self, bytes: u32) -> Result<(), ErrorStack> {
+        if unsafe { ffi::SSL_set_max_early_data(self.as_ptr(), bytes) } == 1 {
+            Ok(())
+        } else {
+            Err(ErrorStack::get())
+        }
+    }
+
+    /// Gets the maximum amount of early data that can be sent on this connection.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_get_max_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn max_early_data(&self) -> u32 {
+        unsafe { ffi::SSL_get_max_early_data(self.as_ptr()) }
+    }
+
+    /// Copies the contents of the last Finished message sent to the peer into the provided buffer.
+    ///
+    /// The total size of the message is returned, so this can be used to determine the size of the
+    /// buffer required.
+    #[corresponds(SSL_get_finished)]
+    pub fn finished(&self, buf: &mut [u8]) -> usize {
+        unsafe { ffi::SSL_get_finished(self.as_ptr(), buf.as_mut_ptr() as *mut c_void, buf.len()) }
+    }
+
+    /// Copies the contents of the last Finished message received from the peer into the provided
+    /// buffer.
+    ///
+    /// The total size of the message is returned, so this can be used to determine the size of the
+    /// buffer required.
+    #[corresponds(SSL_get_peer_finished)]
+    pub fn peer_finished(&self, buf: &mut [u8]) -> usize {
+        unsafe {
+            ffi::SSL_get_peer_finished(self.as_ptr(), buf.as_mut_ptr() as *mut c_void, buf.len())
+        }
+    }
+
+    /// Determines if the initial handshake has been completed.
+    #[corresponds(SSL_is_init_finished)]
+    #[cfg(ossl110)]
+    pub fn is_init_finished(&self) -> bool {
+        unsafe { ffi::SSL_is_init_finished(self.as_ptr()) != 0 }
+    }
+
+    /// Determines if the client's hello message is in the SSLv2 format.
+    ///
+    /// This can only be used inside of the client hello callback. Otherwise, `false` is returned.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_client_hello_isv2)]
+    #[cfg(ossl111)]
+    pub fn client_hello_isv2(&self) -> bool {
+        unsafe { ffi::SSL_client_hello_isv2(self.as_ptr()) != 0 }
+    }
+
+    /// Returns the legacy version field of the client's hello message.
+    ///
+    /// This can only be used inside of the client hello callback. Otherwise, `None` is returned.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_client_hello_get0_legacy_version)]
+    #[cfg(ossl111)]
+    pub fn client_hello_legacy_version(&self) -> Option<SslVersion> {
+        unsafe {
+            let version = ffi::SSL_client_hello_get0_legacy_version(self.as_ptr());
+            if version == 0 {
+                None
+            } else {
+                Some(SslVersion(version as c_int))
+            }
+        }
+    }
+
+    /// Returns the random field of the client's hello message.
+    ///
+    /// This can only be used inside of the client hello callback. Otherwise, `None` is returned.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_client_hello_get0_random)]
+    #[cfg(ossl111)]
+    pub fn client_hello_random(&self) -> Option<&[u8]> {
+        unsafe {
+            let mut ptr = ptr::null();
+            let len = ffi::SSL_client_hello_get0_random(self.as_ptr(), &mut ptr);
+            if len == 0 {
+                None
+            } else {
+                Some(slice::from_raw_parts(ptr, len))
+            }
+        }
+    }
+
+    /// Returns the session ID field of the client's hello message.
+    ///
+    /// This can only be used inside of the client hello callback. Otherwise, `None` is returned.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_client_hello_get0_session_id)]
+    #[cfg(ossl111)]
+    pub fn client_hello_session_id(&self) -> Option<&[u8]> {
+        unsafe {
+            let mut ptr = ptr::null();
+            let len = ffi::SSL_client_hello_get0_session_id(self.as_ptr(), &mut ptr);
+            if len == 0 {
+                None
+            } else {
+                Some(slice::from_raw_parts(ptr, len))
+            }
+        }
+    }
+
+    /// Returns the ciphers field of the client's hello message.
+    ///
+    /// This can only be used inside of the client hello callback. Otherwise, `None` is returned.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_client_hello_get0_ciphers)]
+    #[cfg(ossl111)]
+    pub fn client_hello_ciphers(&self) -> Option<&[u8]> {
+        unsafe {
+            let mut ptr = ptr::null();
+            let len = ffi::SSL_client_hello_get0_ciphers(self.as_ptr(), &mut ptr);
+            if len == 0 {
+                None
+            } else {
+                Some(slice::from_raw_parts(ptr, len))
+            }
+        }
+    }
+
+    /// Returns the compression methods field of the client's hello message.
+    ///
+    /// This can only be used inside of the client hello callback. Otherwise, `None` is returned.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_client_hello_get0_compression_methods)]
+    #[cfg(ossl111)]
+    pub fn client_hello_compression_methods(&self) -> Option<&[u8]> {
+        unsafe {
+            let mut ptr = ptr::null();
+            let len = ffi::SSL_client_hello_get0_compression_methods(self.as_ptr(), &mut ptr);
+            if len == 0 {
+                None
+            } else {
+                Some(slice::from_raw_parts(ptr, len))
+            }
+        }
+    }
+
+    /// Sets the MTU used for DTLS connections.
+    #[corresponds(SSL_set_mtu)]
+    pub fn set_mtu(&mut self, mtu: u32) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_set_mtu(self.as_ptr(), mtu as MtuTy) as c_int).map(|_| ()) }
+    }
+
+    /// Returns the PSK identity hint used during connection setup.
+    ///
+    /// May return `None` if no PSK identity hint was used during the connection setup.
+    #[corresponds(SSL_get_psk_identity_hint)]
+    #[cfg(not(osslconf = "OPENSSL_NO_PSK"))]
+    pub fn psk_identity_hint(&self) -> Option<&[u8]> {
+        unsafe {
+            let ptr = ffi::SSL_get_psk_identity_hint(self.as_ptr());
+            if ptr.is_null() {
+                None
+            } else {
+                Some(CStr::from_ptr(ptr).to_bytes())
+            }
+        }
+    }
+
+    /// Returns the PSK identity used during connection setup.
+    #[corresponds(SSL_get_psk_identity)]
+    #[cfg(not(osslconf = "OPENSSL_NO_PSK"))]
+    pub fn psk_identity(&self) -> Option<&[u8]> {
+        unsafe {
+            let ptr = ffi::SSL_get_psk_identity(self.as_ptr());
+            if ptr.is_null() {
+                None
+            } else {
+                Some(CStr::from_ptr(ptr).to_bytes())
+            }
+        }
+    }
+
+    #[corresponds(SSL_add0_chain_cert)]
+    #[cfg(ossl102)]
+    pub fn add_chain_cert(&mut self, chain: X509) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_add0_chain_cert(self.as_ptr(), chain.as_ptr()) as c_int).map(|_| ())?;
+            mem::forget(chain);
+        }
+        Ok(())
+    }
+
+    /// Sets a new default TLS/SSL method for SSL objects
+    #[cfg(not(boringssl))]
+    pub fn set_method(&mut self, method: SslMethod) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_set_ssl_method(self.as_ptr(), method.as_ptr()))?;
+        };
+        Ok(())
+    }
+
+    /// Loads the private key from a file.
+    #[corresponds(SSL_use_Private_Key_file)]
+    pub fn set_private_key_file<P: AsRef<Path>>(
+        &mut self,
+        path: P,
+        ssl_file_type: SslFiletype,
+    ) -> Result<(), ErrorStack> {
+        let p = path.as_ref().as_os_str().to_str().unwrap();
+        let key_file = CString::new(p).unwrap();
+        unsafe {
+            cvt(ffi::SSL_use_PrivateKey_file(
+                self.as_ptr(),
+                key_file.as_ptr(),
+                ssl_file_type.as_raw(),
+            ))?;
+        };
+        Ok(())
+    }
+
+    /// Sets the private key.
+    #[corresponds(SSL_use_PrivateKey)]
+    pub fn set_private_key(&mut self, pkey: &PKeyRef<Private>) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_use_PrivateKey(self.as_ptr(), pkey.as_ptr()))?;
+        };
+        Ok(())
+    }
+
+    /// Sets the certificate
+    #[corresponds(SSL_use_certificate)]
+    pub fn set_certificate(&mut self, cert: &X509Ref) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_use_certificate(self.as_ptr(), cert.as_ptr()))?;
+        };
+        Ok(())
+    }
+
+    /// Loads a certificate chain from a file.
+    ///
+    /// The file should contain a sequence of PEM-formatted certificates, the first being the leaf
+    /// certificate, and the remainder forming the chain of certificates up to and including the
+    /// trusted root certificate.
+    #[corresponds(SSL_use_certificate_chain_file)]
+    #[cfg(any(ossl110, libressl332))]
+    pub fn set_certificate_chain_file<P: AsRef<Path>>(
+        &mut self,
+        path: P,
+    ) -> Result<(), ErrorStack> {
+        let p = path.as_ref().as_os_str().to_str().unwrap();
+        let cert_file = CString::new(p).unwrap();
+        unsafe {
+            cvt(ffi::SSL_use_certificate_chain_file(
+                self.as_ptr(),
+                cert_file.as_ptr(),
+            ))?;
+        };
+        Ok(())
+    }
+
+    /// Sets ca certificate that client trusted
+    #[corresponds(SSL_add_client_CA)]
+    pub fn add_client_ca(&mut self, cacert: &X509Ref) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_add_client_CA(self.as_ptr(), cacert.as_ptr()))?;
+        };
+        Ok(())
+    }
+
+    // Sets the list of CAs sent to the client when requesting a client certificate for the chosen ssl
+    #[corresponds(SSL_set_client_CA_list)]
+    pub fn set_client_ca_list(&mut self, list: Stack<X509Name>) {
+        unsafe { ffi::SSL_set_client_CA_list(self.as_ptr(), list.as_ptr()) }
+        mem::forget(list);
+    }
+
+    /// Sets the minimum supported protocol version.
+    ///
+    /// A value of `None` will enable protocol versions down to the lowest version supported by
+    /// OpenSSL.
+    ///
+    /// Requires OpenSSL 1.1.0 or LibreSSL 2.6.1 or newer.
+    #[corresponds(SSL_set_min_proto_version)]
+    #[cfg(any(ossl110, libressl261))]
+    pub fn set_min_proto_version(&mut self, version: Option<SslVersion>) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_set_min_proto_version(
+                self.as_ptr(),
+                version.map_or(0, |v| v.0 as _),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the maximum supported protocol version.
+    ///
+    /// A value of `None` will enable protocol versions up to the highest version supported by
+    /// OpenSSL.
+    ///
+    /// Requires OpenSSL 1.1.0 or or LibreSSL 2.6.1 or newer.
+    #[corresponds(SSL_set_max_proto_version)]
+    #[cfg(any(ossl110, libressl261))]
+    pub fn set_max_proto_version(&mut self, version: Option<SslVersion>) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_set_max_proto_version(
+                self.as_ptr(),
+                version.map_or(0, |v| v.0 as _),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the list of supported ciphers for the TLSv1.3 protocol.
+    ///
+    /// The `set_cipher_list` method controls the cipher suites for protocols before TLSv1.3.
+    ///
+    /// The format consists of TLSv1.3 cipher suite names separated by `:` characters in order of
+    /// preference.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_set_ciphersuites)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn set_ciphersuites(&mut self, cipher_list: &str) -> Result<(), ErrorStack> {
+        let cipher_list = CString::new(cipher_list).unwrap();
+        unsafe {
+            cvt(ffi::SSL_set_ciphersuites(
+                self.as_ptr(),
+                cipher_list.as_ptr() as *const _,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Sets the list of supported ciphers for protocols before TLSv1.3.
+    ///
+    /// The `set_ciphersuites` method controls the cipher suites for TLSv1.3.
+    ///
+    /// See [`ciphers`] for details on the format.
+    ///
+    /// [`ciphers`]: https://www.openssl.org/docs/manmaster/apps/ciphers.html
+    #[corresponds(SSL_set_cipher_list)]
+    pub fn set_cipher_list(&mut self, cipher_list: &str) -> Result<(), ErrorStack> {
+        let cipher_list = CString::new(cipher_list).unwrap();
+        unsafe {
+            cvt(ffi::SSL_set_cipher_list(
+                self.as_ptr(),
+                cipher_list.as_ptr() as *const _,
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Set the certificate store used for certificate verification
+    #[corresponds(SSL_set_cert_store)]
+    #[cfg(ossl102)]
+    pub fn set_verify_cert_store(&mut self, cert_store: X509Store) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_set0_verify_cert_store(self.as_ptr(), cert_store.as_ptr()) as c_int)?;
+            mem::forget(cert_store);
+            Ok(())
+        }
+    }
+
+    /// Sets the number of TLS 1.3 session tickets that will be sent to a client after a full
+    /// handshake.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_set_num_tickets)]
+    #[cfg(ossl111)]
+    pub fn set_num_tickets(&mut self, num_tickets: usize) -> Result<(), ErrorStack> {
+        unsafe { cvt(ffi::SSL_set_num_tickets(self.as_ptr(), num_tickets)).map(|_| ()) }
+    }
+
+    /// Gets the number of TLS 1.3 session tickets that will be sent to a client after a full
+    /// handshake.
+    ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    #[corresponds(SSL_get_num_tickets)]
+    #[cfg(ossl111)]
+    pub fn num_tickets(&self) -> usize {
+        unsafe { ffi::SSL_get_num_tickets(self.as_ptr()) }
+    }
+}
+
+/// An SSL stream midway through the handshake process.
+#[derive(Debug)]
+pub struct MidHandshakeSslStream<S> {
+    stream: SslStream<S>,
+    error: Error,
+}
+
+impl<S> MidHandshakeSslStream<S> {
+    /// Returns a shared reference to the inner stream.
+    pub fn get_ref(&self) -> &S {
+        self.stream.get_ref()
+    }
+
+    /// Returns a mutable reference to the inner stream.
+    pub fn get_mut(&mut self) -> &mut S {
+        self.stream.get_mut()
+    }
+
+    /// Returns a shared reference to the `Ssl` of the stream.
+    pub fn ssl(&self) -> &SslRef {
+        self.stream.ssl()
+    }
+
+    /// Returns the underlying error which interrupted this handshake.
+    pub fn error(&self) -> &Error {
+        &self.error
+    }
+
+    /// Consumes `self`, returning its error.
+    pub fn into_error(self) -> Error {
+        self.error
+    }
+}
+
+impl<S> MidHandshakeSslStream<S>
+where
+    S: Read + Write,
+{
+    /// Restarts the handshake process.
+    ///
+    /// This corresponds to [`SSL_do_handshake`].
+    ///
+    /// [`SSL_do_handshake`]: https://www.openssl.org/docs/manmaster/man3/SSL_do_handshake.html
+    pub fn handshake(mut self) -> Result<SslStream<S>, HandshakeError<S>> {
+        match self.stream.do_handshake() {
+            Ok(()) => Ok(self.stream),
+            Err(error) => {
+                self.error = error;
+                match self.error.code() {
+                    ErrorCode::WANT_READ | ErrorCode::WANT_WRITE => {
+                        Err(HandshakeError::WouldBlock(self))
+                    }
+                    _ => Err(HandshakeError::Failure(self)),
+                }
+            }
+        }
+    }
+}
+
+/// A TLS session over a stream.
+pub struct SslStream<S> {
+    ssl: ManuallyDrop<Ssl>,
+    method: ManuallyDrop<BioMethod>,
+    _p: PhantomData<S>,
+}
+
+impl<S> Drop for SslStream<S> {
+    fn drop(&mut self) {
+        // ssl holds a reference to method internally so it has to drop first
+        unsafe {
+            ManuallyDrop::drop(&mut self.ssl);
+            ManuallyDrop::drop(&mut self.method);
+        }
+    }
+}
+
+impl<S> fmt::Debug for SslStream<S>
+where
+    S: fmt::Debug,
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("SslStream")
+            .field("stream", &self.get_ref())
+            .field("ssl", &self.ssl())
+            .finish()
+    }
+}
+
+impl<S: Read + Write> SslStream<S> {
+    /// Creates a new `SslStream`.
+    ///
+    /// This function performs no IO; the stream will not have performed any part of the handshake
+    /// with the peer. If the `Ssl` was configured with [`SslRef::set_connect_state`] or
+    /// [`SslRef::set_accept_state`], the handshake can be performed automatically during the first
+    /// call to read or write. Otherwise the `connect` and `accept` methods can be used to
+    /// explicitly perform the handshake.
+    #[corresponds(SSL_set_bio)]
+    pub fn new(ssl: Ssl, stream: S) -> Result<Self, ErrorStack> {
+        let (bio, method) = bio::new(stream)?;
+        unsafe {
+            ffi::SSL_set_bio(ssl.as_ptr(), bio, bio);
+        }
+
+        Ok(SslStream {
+            ssl: ManuallyDrop::new(ssl),
+            method: ManuallyDrop::new(method),
+            _p: PhantomData,
+        })
+    }
+
+    /// Constructs an `SslStream` from a pointer to the underlying OpenSSL `SSL` struct.
+    ///
+    /// This is useful if the handshake has already been completed elsewhere.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure the pointer is valid.
+    #[deprecated(
+        since = "0.10.32",
+        note = "use Ssl::from_ptr and SslStream::new instead"
+    )]
+    pub unsafe fn from_raw_parts(ssl: *mut ffi::SSL, stream: S) -> Self {
+        let ssl = Ssl::from_ptr(ssl);
+        Self::new(ssl, stream).unwrap()
+    }
+
+    /// Read application data transmitted by a client before handshake completion.
+    ///
+    /// Useful for reducing latency, but vulnerable to replay attacks. Call
+    /// [`SslRef::set_accept_state`] first.
+    ///
+    /// Returns `Ok(0)` if all early data has been read.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_read_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn read_early_data(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
+        let mut read = 0;
+        let ret = unsafe {
+            ffi::SSL_read_early_data(
+                self.ssl.as_ptr(),
+                buf.as_ptr() as *mut c_void,
+                buf.len(),
+                &mut read,
+            )
+        };
+        match ret {
+            ffi::SSL_READ_EARLY_DATA_ERROR => Err(self.make_error(ret)),
+            ffi::SSL_READ_EARLY_DATA_SUCCESS => Ok(read),
+            ffi::SSL_READ_EARLY_DATA_FINISH => Ok(0),
+            _ => unreachable!(),
+        }
+    }
+
+    /// Send data to the server without blocking on handshake completion.
+    ///
+    /// Useful for reducing latency, but vulnerable to replay attacks. Call
+    /// [`SslRef::set_connect_state`] first.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    #[corresponds(SSL_write_early_data)]
+    #[cfg(any(ossl111, libressl340))]
+    pub fn write_early_data(&mut self, buf: &[u8]) -> Result<usize, Error> {
+        let mut written = 0;
+        let ret = unsafe {
+            ffi::SSL_write_early_data(
+                self.ssl.as_ptr(),
+                buf.as_ptr() as *const c_void,
+                buf.len(),
+                &mut written,
+            )
+        };
+        if ret > 0 {
+            Ok(written)
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Initiates a client-side TLS handshake.
+    ///
+    /// # Warning
+    ///
+    /// OpenSSL's default configuration is insecure. It is highly recommended to use
+    /// `SslConnector` rather than `Ssl` directly, as it manages that configuration.
+    #[corresponds(SSL_connect)]
+    pub fn connect(&mut self) -> Result<(), Error> {
+        let ret = unsafe { ffi::SSL_connect(self.ssl.as_ptr()) };
+        if ret > 0 {
+            Ok(())
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Initiates a server-side TLS handshake.
+    ///
+    /// # Warning
+    ///
+    /// OpenSSL's default configuration is insecure. It is highly recommended to use
+    /// `SslAcceptor` rather than `Ssl` directly, as it manages that configuration.
+    #[corresponds(SSL_accept)]
+    pub fn accept(&mut self) -> Result<(), Error> {
+        let ret = unsafe { ffi::SSL_accept(self.ssl.as_ptr()) };
+        if ret > 0 {
+            Ok(())
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Initiates the handshake.
+    ///
+    /// This will fail if `set_accept_state` or `set_connect_state` was not called first.
+    #[corresponds(SSL_do_handshake)]
+    pub fn do_handshake(&mut self) -> Result<(), Error> {
+        let ret = unsafe { ffi::SSL_do_handshake(self.ssl.as_ptr()) };
+        if ret > 0 {
+            Ok(())
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Perform a stateless server-side handshake.
+    ///
+    /// Requires that cookie generation and verification callbacks were
+    /// set on the SSL context.
+    ///
+    /// Returns `Ok(true)` if a complete ClientHello containing a valid cookie
+    /// was read, in which case the handshake should be continued via
+    /// `accept`. If a HelloRetryRequest containing a fresh cookie was
+    /// transmitted, `Ok(false)` is returned instead. If the handshake cannot
+    /// proceed at all, `Err` is returned.
+    #[corresponds(SSL_stateless)]
+    #[cfg(ossl111)]
+    pub fn stateless(&mut self) -> Result<bool, ErrorStack> {
+        match unsafe { ffi::SSL_stateless(self.ssl.as_ptr()) } {
+            1 => Ok(true),
+            0 => Ok(false),
+            -1 => Err(ErrorStack::get()),
+            _ => unreachable!(),
+        }
+    }
+
+    /// Like `read`, but returns an `ssl::Error` rather than an `io::Error`.
+    ///
+    /// It is particularly useful with a non-blocking socket, where the error value will identify if
+    /// OpenSSL is waiting on read or write readiness.
+    #[corresponds(SSL_read)]
+    pub fn ssl_read(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
+        // The interpretation of the return code here is a little odd with a
+        // zero-length write. OpenSSL will likely correctly report back to us
+        // that it read zero bytes, but zero is also the sentinel for "error".
+        // To avoid that confusion short-circuit that logic and return quickly
+        // if `buf` has a length of zero.
+        if buf.is_empty() {
+            return Ok(0);
+        }
+
+        let ret = self.ssl.read(buf);
+        if ret > 0 {
+            Ok(ret as usize)
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Like `write`, but returns an `ssl::Error` rather than an `io::Error`.
+    ///
+    /// It is particularly useful with a non-blocking socket, where the error value will identify if
+    /// OpenSSL is waiting on read or write readiness.
+    #[corresponds(SSL_write)]
+    pub fn ssl_write(&mut self, buf: &[u8]) -> Result<usize, Error> {
+        // See above for why we short-circuit on zero-length buffers
+        if buf.is_empty() {
+            return Ok(0);
+        }
+
+        let ret = self.ssl.write(buf);
+        if ret > 0 {
+            Ok(ret as usize)
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Reads data from the stream, without removing it from the queue.
+    #[corresponds(SSL_peek)]
+    pub fn ssl_peek(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
+        // See above for why we short-circuit on zero-length buffers
+        if buf.is_empty() {
+            return Ok(0);
+        }
+
+        let ret = self.ssl.peek(buf);
+        if ret > 0 {
+            Ok(ret as usize)
+        } else {
+            Err(self.make_error(ret))
+        }
+    }
+
+    /// Shuts down the session.
+    ///
+    /// The shutdown process consists of two steps. The first step sends a close notify message to
+    /// the peer, after which `ShutdownResult::Sent` is returned. The second step awaits the receipt
+    /// of a close notify message from the peer, after which `ShutdownResult::Received` is returned.
+    ///
+    /// While the connection may be closed after the first step, it is recommended to fully shut the
+    /// session down. In particular, it must be fully shut down if the connection is to be used for
+    /// further communication in the future.
+    #[corresponds(SSL_shutdown)]
+    pub fn shutdown(&mut self) -> Result<ShutdownResult, Error> {
+        match unsafe { ffi::SSL_shutdown(self.ssl.as_ptr()) } {
+            0 => Ok(ShutdownResult::Sent),
+            1 => Ok(ShutdownResult::Received),
+            n => Err(self.make_error(n)),
+        }
+    }
+
+    /// Returns the session's shutdown state.
+    #[corresponds(SSL_get_shutdown)]
+    pub fn get_shutdown(&mut self) -> ShutdownState {
+        unsafe {
+            let bits = ffi::SSL_get_shutdown(self.ssl.as_ptr());
+            ShutdownState { bits }
+        }
+    }
+
+    /// Sets the session's shutdown state.
+    ///
+    /// This can be used to tell OpenSSL that the session should be cached even if a full two-way
+    /// shutdown was not completed.
+    #[corresponds(SSL_set_shutdown)]
+    pub fn set_shutdown(&mut self, state: ShutdownState) {
+        unsafe { ffi::SSL_set_shutdown(self.ssl.as_ptr(), state.bits()) }
+    }
+}
+
+impl<S> SslStream<S> {
+    fn make_error(&mut self, ret: c_int) -> Error {
+        self.check_panic();
+
+        let code = self.ssl.get_error(ret);
+
+        let cause = match code {
+            ErrorCode::SSL => Some(InnerError::Ssl(ErrorStack::get())),
+            ErrorCode::SYSCALL => {
+                let errs = ErrorStack::get();
+                if errs.errors().is_empty() {
+                    self.get_bio_error().map(InnerError::Io)
+                } else {
+                    Some(InnerError::Ssl(errs))
+                }
+            }
+            ErrorCode::ZERO_RETURN => None,
+            ErrorCode::WANT_READ | ErrorCode::WANT_WRITE => {
+                self.get_bio_error().map(InnerError::Io)
+            }
+            _ => None,
+        };
+
+        Error { code, cause }
+    }
+
+    fn check_panic(&mut self) {
+        if let Some(err) = unsafe { bio::take_panic::<S>(self.ssl.get_raw_rbio()) } {
+            resume_unwind(err)
+        }
+    }
+
+    fn get_bio_error(&mut self) -> Option<io::Error> {
+        unsafe { bio::take_error::<S>(self.ssl.get_raw_rbio()) }
+    }
+
+    /// Returns a shared reference to the underlying stream.
+    pub fn get_ref(&self) -> &S {
+        unsafe {
+            let bio = self.ssl.get_raw_rbio();
+            bio::get_ref(bio)
+        }
+    }
+
+    /// Returns a mutable reference to the underlying stream.
+    ///
+    /// # Warning
+    ///
+    /// It is inadvisable to read from or write to the underlying stream as it
+    /// will most likely corrupt the SSL session.
+    pub fn get_mut(&mut self) -> &mut S {
+        unsafe {
+            let bio = self.ssl.get_raw_rbio();
+            bio::get_mut(bio)
+        }
+    }
+
+    /// Returns a shared reference to the `Ssl` object associated with this stream.
+    pub fn ssl(&self) -> &SslRef {
+        &self.ssl
+    }
+}
+
+impl<S: Read + Write> Read for SslStream<S> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        loop {
+            match self.ssl_read(buf) {
+                Ok(n) => return Ok(n),
+                Err(ref e) if e.code() == ErrorCode::ZERO_RETURN => return Ok(0),
+                Err(ref e) if e.code() == ErrorCode::SYSCALL && e.io_error().is_none() => {
+                    return Ok(0);
+                }
+                Err(ref e) if e.code() == ErrorCode::WANT_READ && e.io_error().is_none() => {}
+                Err(e) => {
+                    return Err(e
+                        .into_io_error()
+                        .unwrap_or_else(|e| io::Error::new(io::ErrorKind::Other, e)));
+                }
+            }
+        }
+    }
+}
+
+impl<S: Read + Write> Write for SslStream<S> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        loop {
+            match self.ssl_write(buf) {
+                Ok(n) => return Ok(n),
+                Err(ref e) if e.code() == ErrorCode::WANT_READ && e.io_error().is_none() => {}
+                Err(e) => {
+                    return Err(e
+                        .into_io_error()
+                        .unwrap_or_else(|e| io::Error::new(io::ErrorKind::Other, e)));
+                }
+            }
+        }
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.get_mut().flush()
+    }
+}
+
+/// A partially constructed `SslStream`, useful for unusual handshakes.
+#[deprecated(
+    since = "0.10.32",
+    note = "use the methods directly on Ssl/SslStream instead"
+)]
+pub struct SslStreamBuilder<S> {
+    inner: SslStream<S>,
+}
+
+#[allow(deprecated)]
+impl<S> SslStreamBuilder<S>
+where
+    S: Read + Write,
+{
+    /// Begin creating an `SslStream` atop `stream`
+    pub fn new(ssl: Ssl, stream: S) -> Self {
+        Self {
+            inner: SslStream::new(ssl, stream).unwrap(),
+        }
+    }
+
+    /// Perform a stateless server-side handshake
+    ///
+    /// Requires that cookie generation and verification callbacks were
+    /// set on the SSL context.
+    ///
+    /// Returns `Ok(true)` if a complete ClientHello containing a valid cookie
+    /// was read, in which case the handshake should be continued via
+    /// `accept`. If a HelloRetryRequest containing a fresh cookie was
+    /// transmitted, `Ok(false)` is returned instead. If the handshake cannot
+    /// proceed at all, `Err` is returned.
+    ///
+    /// This corresponds to [`SSL_stateless`]
+    ///
+    /// [`SSL_stateless`]: https://www.openssl.org/docs/manmaster/man3/SSL_stateless.html
+    #[cfg(ossl111)]
+    pub fn stateless(&mut self) -> Result<bool, ErrorStack> {
+        match unsafe { ffi::SSL_stateless(self.inner.ssl.as_ptr()) } {
+            1 => Ok(true),
+            0 => Ok(false),
+            -1 => Err(ErrorStack::get()),
+            _ => unreachable!(),
+        }
+    }
+
+    /// Configure as an outgoing stream from a client.
+    ///
+    /// This corresponds to [`SSL_set_connect_state`].
+    ///
+    /// [`SSL_set_connect_state`]: https://www.openssl.org/docs/manmaster/man3/SSL_set_connect_state.html
+    pub fn set_connect_state(&mut self) {
+        unsafe { ffi::SSL_set_connect_state(self.inner.ssl.as_ptr()) }
+    }
+
+    /// Configure as an incoming stream to a server.
+    ///
+    /// This corresponds to [`SSL_set_accept_state`].
+    ///
+    /// [`SSL_set_accept_state`]: https://www.openssl.org/docs/manmaster/man3/SSL_set_accept_state.html
+    pub fn set_accept_state(&mut self) {
+        unsafe { ffi::SSL_set_accept_state(self.inner.ssl.as_ptr()) }
+    }
+
+    /// See `Ssl::connect`
+    pub fn connect(mut self) -> Result<SslStream<S>, HandshakeError<S>> {
+        match self.inner.connect() {
+            Ok(()) => Ok(self.inner),
+            Err(error) => match error.code() {
+                ErrorCode::WANT_READ | ErrorCode::WANT_WRITE => {
+                    Err(HandshakeError::WouldBlock(MidHandshakeSslStream {
+                        stream: self.inner,
+                        error,
+                    }))
+                }
+                _ => Err(HandshakeError::Failure(MidHandshakeSslStream {
+                    stream: self.inner,
+                    error,
+                })),
+            },
+        }
+    }
+
+    /// See `Ssl::accept`
+    pub fn accept(mut self) -> Result<SslStream<S>, HandshakeError<S>> {
+        match self.inner.accept() {
+            Ok(()) => Ok(self.inner),
+            Err(error) => match error.code() {
+                ErrorCode::WANT_READ | ErrorCode::WANT_WRITE => {
+                    Err(HandshakeError::WouldBlock(MidHandshakeSslStream {
+                        stream: self.inner,
+                        error,
+                    }))
+                }
+                _ => Err(HandshakeError::Failure(MidHandshakeSslStream {
+                    stream: self.inner,
+                    error,
+                })),
+            },
+        }
+    }
+
+    /// Initiates the handshake.
+    ///
+    /// This will fail if `set_accept_state` or `set_connect_state` was not called first.
+    ///
+    /// This corresponds to [`SSL_do_handshake`].
+    ///
+    /// [`SSL_do_handshake`]: https://www.openssl.org/docs/manmaster/man3/SSL_do_handshake.html
+    pub fn handshake(mut self) -> Result<SslStream<S>, HandshakeError<S>> {
+        match self.inner.do_handshake() {
+            Ok(()) => Ok(self.inner),
+            Err(error) => match error.code() {
+                ErrorCode::WANT_READ | ErrorCode::WANT_WRITE => {
+                    Err(HandshakeError::WouldBlock(MidHandshakeSslStream {
+                        stream: self.inner,
+                        error,
+                    }))
+                }
+                _ => Err(HandshakeError::Failure(MidHandshakeSslStream {
+                    stream: self.inner,
+                    error,
+                })),
+            },
+        }
+    }
+
+    /// Read application data transmitted by a client before handshake
+    /// completion.
+    ///
+    /// Useful for reducing latency, but vulnerable to replay attacks. Call
+    /// `set_accept_state` first.
+    ///
+    /// Returns `Ok(0)` if all early data has been read.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    ///
+    /// This corresponds to [`SSL_read_early_data`].
+    ///
+    /// [`SSL_read_early_data`]: https://www.openssl.org/docs/manmaster/man3/SSL_read_early_data.html
+    #[cfg(any(ossl111, libressl340))]
+    pub fn read_early_data(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
+        self.inner.read_early_data(buf)
+    }
+
+    /// Send data to the server without blocking on handshake completion.
+    ///
+    /// Useful for reducing latency, but vulnerable to replay attacks. Call
+    /// `set_connect_state` first.
+    ///
+    /// Requires OpenSSL 1.1.1 or LibreSSL 3.4.0 or newer.
+    ///
+    /// This corresponds to [`SSL_write_early_data`].
+    ///
+    /// [`SSL_write_early_data`]: https://www.openssl.org/docs/manmaster/man3/SSL_write_early_data.html
+    #[cfg(any(ossl111, libressl340))]
+    pub fn write_early_data(&mut self, buf: &[u8]) -> Result<usize, Error> {
+        self.inner.write_early_data(buf)
+    }
+}
+
+#[allow(deprecated)]
+impl<S> SslStreamBuilder<S> {
+    /// Returns a shared reference to the underlying stream.
+    pub fn get_ref(&self) -> &S {
+        unsafe {
+            let bio = self.inner.ssl.get_raw_rbio();
+            bio::get_ref(bio)
+        }
+    }
+
+    /// Returns a mutable reference to the underlying stream.
+    ///
+    /// # Warning
+    ///
+    /// It is inadvisable to read from or write to the underlying stream as it
+    /// will most likely corrupt the SSL session.
+    pub fn get_mut(&mut self) -> &mut S {
+        unsafe {
+            let bio = self.inner.ssl.get_raw_rbio();
+            bio::get_mut(bio)
+        }
+    }
+
+    /// Returns a shared reference to the `Ssl` object associated with this builder.
+    pub fn ssl(&self) -> &SslRef {
+        &self.inner.ssl
+    }
+
+    /// Set the DTLS MTU size.
+    ///
+    /// It will be ignored if the value is smaller than the minimum packet size
+    /// the DTLS protocol requires.
+    ///
+    /// # Panics
+    /// This function panics if the given mtu size can't be represented in a positive `c_long` range
+    #[deprecated(note = "Use SslRef::set_mtu instead", since = "0.10.30")]
+    pub fn set_dtls_mtu_size(&mut self, mtu_size: usize) {
+        unsafe {
+            let bio = self.inner.ssl.get_raw_rbio();
+            bio::set_dtls_mtu_size::<S>(bio, mtu_size);
+        }
+    }
+}
+
+/// The result of a shutdown request.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum ShutdownResult {
+    /// A close notify message has been sent to the peer.
+    Sent,
+
+    /// A close notify response message has been received from the peer.
+    Received,
+}
+
+bitflags! {
+    /// The shutdown state of a session.
+    pub struct ShutdownState: c_int {
+        /// A close notify message has been sent to the peer.
+        const SENT = ffi::SSL_SENT_SHUTDOWN;
+        /// A close notify message has been received from the peer.
+        const RECEIVED = ffi::SSL_RECEIVED_SHUTDOWN;
+    }
+}
+
+cfg_if! {
+    if #[cfg(any(boringssl, ossl110, libressl273))] {
+        use ffi::{SSL_CTX_up_ref, SSL_SESSION_get_master_key, SSL_SESSION_up_ref, SSL_is_server};
+    } else {
+        #[allow(bad_style)]
+        pub unsafe fn SSL_CTX_up_ref(ssl: *mut ffi::SSL_CTX) -> c_int {
+            ffi::CRYPTO_add_lock(
+                &mut (*ssl).references,
+                1,
+                ffi::CRYPTO_LOCK_SSL_CTX,
+                "mod.rs\0".as_ptr() as *const _,
+                line!() as c_int,
+            );
+            0
+        }
+
+        #[allow(bad_style)]
+        pub unsafe fn SSL_SESSION_get_master_key(
+            session: *const ffi::SSL_SESSION,
+            out: *mut c_uchar,
+            mut outlen: usize,
+        ) -> usize {
+            if outlen == 0 {
+                return (*session).master_key_length as usize;
+            }
+            if outlen > (*session).master_key_length as usize {
+                outlen = (*session).master_key_length as usize;
+            }
+            ptr::copy_nonoverlapping((*session).master_key.as_ptr(), out, outlen);
+            outlen
+        }
+
+        #[allow(bad_style)]
+        pub unsafe fn SSL_is_server(s: *mut ffi::SSL) -> c_int {
+            (*s).server
+        }
+
+        #[allow(bad_style)]
+        pub unsafe fn SSL_SESSION_up_ref(ses: *mut ffi::SSL_SESSION) -> c_int {
+            ffi::CRYPTO_add_lock(
+                &mut (*ses).references,
+                1,
+                ffi::CRYPTO_LOCK_SSL_CTX,
+                "mod.rs\0".as_ptr() as *const _,
+                line!() as c_int,
+            );
+            0
+        }
+    }
+}
+
+cfg_if! {
+    if #[cfg(ossl300)] {
+        use ffi::SSL_get1_peer_certificate;
+    } else {
+        use ffi::SSL_get_peer_certificate as SSL_get1_peer_certificate;
+    }
+}
+cfg_if! {
+    if #[cfg(any(boringssl, ossl110, libressl291))] {
+        use ffi::{TLS_method, DTLS_method, TLS_client_method, TLS_server_method};
+    } else {
+        use ffi::{
+            SSLv23_method as TLS_method, DTLSv1_method as DTLS_method, SSLv23_client_method as TLS_client_method,
+            SSLv23_server_method as TLS_server_method,
+        };
+    }
+}
+cfg_if! {
+    if #[cfg(ossl110)] {
+        unsafe fn get_new_idx(f: ffi::CRYPTO_EX_free) -> c_int {
+            ffi::CRYPTO_get_ex_new_index(
+                ffi::CRYPTO_EX_INDEX_SSL_CTX,
+                0,
+                ptr::null_mut(),
+                None,
+                None,
+                Some(f),
+            )
+        }
+
+        unsafe fn get_new_ssl_idx(f: ffi::CRYPTO_EX_free) -> c_int {
+            ffi::CRYPTO_get_ex_new_index(
+                ffi::CRYPTO_EX_INDEX_SSL,
+                0,
+                ptr::null_mut(),
+                None,
+                None,
+                Some(f),
+            )
+        }
+    } else {
+        use std::sync::Once;
+
+        unsafe fn get_new_idx(f: ffi::CRYPTO_EX_free) -> c_int {
+            // hack around https://rt.openssl.org/Ticket/Display.html?id=3710&user=guest&pass=guest
+            static ONCE: Once = Once::new();
+            ONCE.call_once(|| {
+                cfg_if! {
+                    if #[cfg(not(boringssl))] {
+                        ffi::SSL_CTX_get_ex_new_index(0, ptr::null_mut(), None, None, None);
+                    } else {
+                        ffi::SSL_CTX_get_ex_new_index(0, ptr::null_mut(), ptr::null_mut(), None, None);
+                    }
+                }
+            });
+
+            cfg_if! {
+                if #[cfg(not(boringssl))] {
+                    ffi::SSL_CTX_get_ex_new_index(0, ptr::null_mut(), None, None, Some(f))
+                } else {
+                    ffi::SSL_CTX_get_ex_new_index(0, ptr::null_mut(), ptr::null_mut(), None, f)
+                }
+            }
+        }
+
+        unsafe fn get_new_ssl_idx(f: ffi::CRYPTO_EX_free) -> c_int {
+            // hack around https://rt.openssl.org/Ticket/Display.html?id=3710&user=guest&pass=guest
+            static ONCE: Once = Once::new();
+            ONCE.call_once(|| {
+                #[cfg(not(boringssl))]
+                ffi::SSL_get_ex_new_index(0, ptr::null_mut(), None, None, None);
+                #[cfg(boringssl)]
+                ffi::SSL_get_ex_new_index(0, ptr::null_mut(), ptr::null_mut(), None, None);
+            });
+
+            #[cfg(not(boringssl))]
+            return ffi::SSL_get_ex_new_index(0, ptr::null_mut(), None, None, Some(f));
+            #[cfg(boringssl)]
+            return ffi::SSL_get_ex_new_index(0, ptr::null_mut(), ptr::null_mut(), None, f);
+        }
+    }
+}