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    //! SMIME implementation using CMS
    //!
    //! CMS (PKCS#7) is an encyption standard.  It allows signing and ecrypting data using
    //! X.509 certificates.  The OpenSSL implementation of CMS is used in email encryption
    //! generated from a `Vec` of bytes.  This `Vec` follows the smime protocol standards.
    //! Data accepted by this module will be smime type `enveloped-data`.

    use ffi;
    use foreign_types::{ForeignType, ForeignTypeRef};
    use std::ptr;

    use bio::{MemBio, MemBioSlice};
    use error::ErrorStack;
    use libc::c_uint;
    use pkey::{HasPrivate, PKeyRef};
    use stack::StackRef;
    use symm::Cipher;
    use x509::{X509Ref, X509};
    use {cvt, cvt_p};

    bitflags! {
        pub struct CMSOptions : c_uint {
            const TEXT = ffi::CMS_TEXT;
            const CMS_NOCERTS = ffi::CMS_NOCERTS;
            const NO_CONTENT_VERIFY = ffi::CMS_NO_CONTENT_VERIFY;
            const NO_ATTR_VERIFY = ffi::CMS_NO_ATTR_VERIFY;
            const NOSIGS = ffi::CMS_NOSIGS;
            const NOINTERN = ffi::CMS_NOINTERN;
            const NO_SIGNER_CERT_VERIFY = ffi::CMS_NO_SIGNER_CERT_VERIFY;
            const NOVERIFY = ffi::CMS_NOVERIFY;
            const DETACHED = ffi::CMS_DETACHED;
            const BINARY = ffi::CMS_BINARY;
            const NOATTR = ffi::CMS_NOATTR;
            const NOSMIMECAP = ffi::CMS_NOSMIMECAP;
            const NOOLDMIMETYPE = ffi::CMS_NOOLDMIMETYPE;
            const CRLFEOL = ffi::CMS_CRLFEOL;
            const STREAM = ffi::CMS_STREAM;
            const NOCRL = ffi::CMS_NOCRL;
            const PARTIAL = ffi::CMS_PARTIAL;
            const REUSE_DIGEST = ffi::CMS_REUSE_DIGEST;
            const USE_KEYID = ffi::CMS_USE_KEYID;
            const DEBUG_DECRYPT = ffi::CMS_DEBUG_DECRYPT;
            #[cfg(all(not(libressl), not(ossl101)))]
            const KEY_PARAM = ffi::CMS_KEY_PARAM;
            #[cfg(all(not(libressl), not(ossl101), not(ossl102)))]
            const ASCIICRLF = ffi::CMS_ASCIICRLF;
        }
    }

    foreign_type_and_impl_send_sync! {
        type CType = ffi::CMS_ContentInfo;
        fn drop = ffi::CMS_ContentInfo_free;

        /// High level CMS wrapper
        ///
        /// CMS supports nesting various types of data, including signatures, certificates,
        /// encrypted data, smime messages (encrypted email), and data digest.  The ContentInfo
        /// content type is the encapsulation of all those content types.  [`RFC 5652`] describes
        /// CMS and OpenSSL follows this RFC's implmentation.
        ///
        /// [`RFC 5652`]: https://tools.ietf.org/html/rfc5652#page-6
        pub struct CmsContentInfo;
        /// Reference to [`CMSContentInfo`]
        ///
        /// [`CMSContentInfo`]:struct.CmsContentInfo.html
        pub struct CmsContentInfoRef;
    }

    impl CmsContentInfoRef {
        /// Given the sender's private key, `pkey` and the recipient's certificiate, `cert`,
        /// decrypt the data in `self`.
        ///
        /// OpenSSL documentation at [`CMS_decrypt`]
        ///
        /// [`CMS_decrypt`]: https://www.openssl.org/docs/man1.1.0/crypto/CMS_decrypt.html
        pub fn decrypt<T>(&self, pkey: &PKeyRef<T>, cert: &X509) -> Result<Vec<u8>, ErrorStack>
        where
            T: HasPrivate,
        {
            unsafe {
                let pkey = pkey.as_ptr();
                let cert = cert.as_ptr();
                let out = MemBio::new()?;

                cvt(ffi::CMS_decrypt(
                    self.as_ptr(),
                    pkey,
                    cert,
                    ptr::null_mut(),
                    out.as_ptr(),
                    0,
                ))?;

                Ok(out.get_buf().to_owned())
            }
        }

        to_der! {
            /// Serializes this CmsContentInfo using DER.
            ///
            /// OpenSSL documentation at [`i2d_CMS_ContentInfo`]
            ///
            /// [`i2d_CMS_ContentInfo`]: https://www.openssl.org/docs/man1.0.2/crypto/i2d_CMS_ContentInfo.html
            to_der,
            ffi::i2d_CMS_ContentInfo
        }

        to_pem! {
            /// Serializes this CmsContentInfo using DER.
            ///
            /// OpenSSL documentation at [`PEM_write_bio_CMS`]
            ///
            /// [`PEM_write_bio_CMS`]: https://www.openssl.org/docs/man1.1.0/man3/PEM_write_bio_CMS.html
            to_pem,
            ffi::PEM_write_bio_CMS
        }
    }

    impl CmsContentInfo {
        /// Parses a smime formatted `vec` of bytes into a `CmsContentInfo`.
        ///
        /// OpenSSL documentation at [`SMIME_read_CMS`]
        ///
        /// [`SMIME_read_CMS`]: https://www.openssl.org/docs/man1.0.2/crypto/SMIME_read_CMS.html
        pub fn smime_read_cms(smime: &[u8]) -> Result<CmsContentInfo, ErrorStack> {
            unsafe {
                let bio = MemBioSlice::new(smime)?;

                let cms = cvt_p(ffi::SMIME_read_CMS(bio.as_ptr(), ptr::null_mut()))?;

                Ok(CmsContentInfo::from_ptr(cms))
            }
        }

        from_der! {
            /// Deserializes a DER-encoded ContentInfo structure.
            ///
            /// This corresponds to [`d2i_CMS_ContentInfo`].
            ///
            /// [`d2i_CMS_ContentInfo`]: https://www.openssl.org/docs/manmaster/man3/d2i_X509.html
            from_der,
            CmsContentInfo,
            ffi::d2i_CMS_ContentInfo
        }

        from_pem! {
            /// Deserializes a PEM-encoded ContentInfo structure.
            ///
            /// This corresponds to [`PEM_read_bio_CMS`].
            ///
            /// [`PEM_read_bio_CMS`]: https://www.openssl.org/docs/man1.1.0/man3/PEM_read_bio_CMS.html
            from_pem,
            CmsContentInfo,
            ffi::PEM_read_bio_CMS
        }

        /// Given a signing cert `signcert`, private key `pkey`, a certificate stack `certs`,
        /// data `data` and flags `flags`, create a CmsContentInfo struct.
        ///
        /// All arguments are optional.
        ///
        /// OpenSSL documentation at [`CMS_sign`]
        ///
        /// [`CMS_sign`]: https://www.openssl.org/docs/manmaster/man3/CMS_sign.html
        pub fn sign<T>(
            signcert: Option<&X509Ref>,
            pkey: Option<&PKeyRef<T>>,
            certs: Option<&StackRef<X509>>,
            data: Option<&[u8]>,
            flags: CMSOptions,
        ) -> Result<CmsContentInfo, ErrorStack>
        where
            T: HasPrivate,
        {
            unsafe {
                let signcert = signcert.map_or(ptr::null_mut(), |p| p.as_ptr());
                let pkey = pkey.map_or(ptr::null_mut(), |p| p.as_ptr());
                let data_bio = match data {
                    Some(data) => Some(MemBioSlice::new(data)?),
                    None => None,
                };
                let data_bio_ptr = data_bio.as_ref().map_or(ptr::null_mut(), |p| p.as_ptr());
                let certs = certs.map_or(ptr::null_mut(), |p| p.as_ptr());

                let cms = cvt_p(ffi::CMS_sign(
                    signcert,
                    pkey,
                    certs,
                    data_bio_ptr,
                    flags.bits(),
                ))?;

                Ok(CmsContentInfo::from_ptr(cms))
            }
        }

        /// Given a certificate stack `certs`, data `data`, cipher `cipher` and flags `flags`,
        /// create a CmsContentInfo struct.
        ///
        /// OpenSSL documentation at [`CMS_encrypt`]
        ///
        /// [`CMS_encrypt`]: https://www.openssl.org/docs/manmaster/man3/CMS_encrypt.html
        pub fn encrypt(
            certs: &StackRef<X509>,
            data: &[u8],
            cipher: Cipher,
            flags: CMSOptions,
        ) -> Result<CmsContentInfo, ErrorStack> {
            unsafe {
                let data_bio = MemBioSlice::new(data)?;

                let cms = cvt_p(ffi::CMS_encrypt(
                    certs.as_ptr(),
                    data_bio.as_ptr(),
                    cipher.as_ptr(),
                    flags.bits(),
                ))?;

                Ok(CmsContentInfo::from_ptr(cms))
            }
        }
    }

    #[cfg(test)]
    mod test {
        use super::*;
        use pkcs12::Pkcs12;
        use stack::Stack;
        use x509::X509;

        #[test]
        fn cms_encrypt_decrypt() {
            // load cert with public key only
            let pub_cert_bytes = include_bytes!("../test/cms_pubkey.der");
            let pub_cert = X509::from_der(pub_cert_bytes).expect("failed to load pub cert");

            // load cert with private key
            let priv_cert_bytes = include_bytes!("../test/cms.p12");
            let priv_cert = Pkcs12::from_der(priv_cert_bytes).expect("failed to load priv cert");
            let priv_cert = priv_cert
                .parse("mypass")
                .expect("failed to parse priv cert");

            // encrypt cms message using public key cert
            let input = String::from("My Message");
            let mut cert_stack = Stack::new().expect("failed to create stack");
            cert_stack
                .push(pub_cert)
                .expect("failed to add pub cert to stack");

            let encrypt = CmsContentInfo::encrypt(
                &cert_stack,
                &input.as_bytes(),
                Cipher::des_ede3_cbc(),
                CMSOptions::empty(),
            )
            .expect("failed create encrypted cms");

            // decrypt cms message using private key cert (DER)
            {
                let encrypted_der = encrypt.to_der().expect("failed to create der from cms");
                let decrypt =
                    CmsContentInfo::from_der(&encrypted_der).expect("failed read cms from der");
                let decrypt = decrypt
                    .decrypt(&priv_cert.pkey, &priv_cert.cert)
                    .expect("failed to decrypt cms");
                let decrypt =
                    String::from_utf8(decrypt).expect("failed to create string from cms content");
                assert_eq!(input, decrypt);
            }

            // decrypt cms message using private key cert (PEM)
            {
                let encrypted_pem = encrypt.to_pem().expect("failed to create pem from cms");
                let decrypt =
                    CmsContentInfo::from_pem(&encrypted_pem).expect("failed read cms from pem");
                let decrypt = decrypt
                    .decrypt(&priv_cert.pkey, &priv_cert.cert)
                    .expect("failed to decrypt cms");
                let decrypt =
                    String::from_utf8(decrypt).expect("failed to create string from cms content");
                assert_eq!(input, decrypt);
            }
        }
    }