//! Traits for converting keys to and from OpenSSH format.

//

// TODO #902: OpenSSH keys can have passphrases. While the current implementation isn't able to

// handle such keys, we will eventually need to support them (this will be a breaking API change).

use tor_error::internal;

use tor_key_forge::{ErasedKey, KeyType, SshKeyAlgorithm, SshKeyData};

use crate::Result;

use crate::keystore::arti::err::ArtiNativeKeystoreError;

use std::path::PathBuf;

use zeroize::Zeroizing;

/// An unparsed OpenSSH key.

///

/// Note: This is a wrapper around the contents of a file we think is an OpenSSH key. The inner

/// value is unchecked/unvalidated, and might not actually be a valid OpenSSH key.

///

/// The inner value is zeroed on drop.

pub(super) struct UnparsedOpenSshKey {

    /// The contents of an OpenSSH key file.

    inner: Zeroizing<String>,

    /// The path of the file (for error reporting).

    path: PathBuf,

}

/// Parse an OpenSSH key, returning its corresponding [`SshKeyData`].

macro_rules! parse_openssh {

    (PRIVATE $key:expr, $key_type:expr) => {{

        SshKeyData::try_from_keypair_data(parse_openssh!(

            $key,

            $key_type,

            ssh_key::private::PrivateKey::from_openssh

        ).key_data().clone())?

    }};

    (PUBLIC $key:expr, $key_type:expr) => {{

        SshKeyData::try_from_key_data(parse_openssh!(

            $key,

            $key_type,

            ssh_key::public::PublicKey::from_openssh

        ).key_data().clone())?

    }};

    ($key:expr, $key_type:expr, $parse_fn:path) => {{

        let wanted_key_algo = ssh_algorithm($key_type)?;

        if SshKeyAlgorithm::from(key.algorithm()) != wanted_key_algo {

            return Err(ArtiNativeKeystoreError::UnexpectedSshKeyType {

                path: $key.path,

                wanted_key_algo,

                found_key_algo: key.algorithm().into(),

            }.into());

        }

        key

    }};

}

/// Get the algorithm of this key type.

        &_ => {

        }

    }

impl UnparsedOpenSshKey {

    /// Create a new [`UnparsedOpenSshKey`].

    ///

    /// The contents of `inner` are erased on drop.

    /// Parse an OpenSSH key, convert the key material into a known key type, and return the

    /// type-erased value.

    ///

    /// The caller is expected to downcast the value returned to a concrete type.

            KeyType::Ed25519Keypair

            | KeyType::X25519StaticKeypair

            | KeyType::Ed25519ExpandedKeypair

            KeyType::Ed25519PublicKey | KeyType::X25519PublicKey | KeyType::RsaPublicKey => {

            }

        }

}

#[cfg(test)]

mod tests {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_time_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use crate::test_utils::ssh_keys::*;

    use crate::test_utils::sshkeygen_ed25519_strings;

    use tor_key_forge::{EncodableItem, KeystoreItem};

    use tor_llcrypto::pk::{curve25519, ed25519};

    use super::*;

    /// Comments used for the various keys. Should be kept in sync with the comments

    /// used in `maint/keygen-openssh-test/generate`, the fallback comment used in

    /// `maint/keygen-openssh-test/src/main.rs: make_openssh_key! {}`, and the

    /// comment used in `crate::test_utils::sshkeygen_ed25519_strings()`.

    const ED25519_OPENSSH_COMMENT: &str = "armadillo@example.com";

    const ED25519_EXPANDED_OPENSSH_COMMENT: &str = "armadillo@example.com";

    const X25519_OPENSSH_COMMENT: &str = "test-key";

    const ED25519_SSHKEYGEN_COMMENT: &str = "";

    /// Convenience trait for getting the underlying bytes for key types.

    trait ToBytes {

        type Bytes;

        fn to_bytes(&self) -> Self::Bytes;

    }

    impl ToBytes for ed25519::Keypair {

        type Bytes = [u8; 32];

        fn to_bytes(&self) -> Self::Bytes {

            self.to_bytes()

        }

    }

    impl ToBytes for ed25519::PublicKey {

        type Bytes = [u8; 32];

        fn to_bytes(&self) -> Self::Bytes {

            self.to_bytes()

        }

    }

    impl ToBytes for ed25519::ExpandedKeypair {

        type Bytes = [u8; 64];

        fn to_bytes(&self) -> Self::Bytes {

            self.to_secret_key_bytes()

        }

    }

    impl ToBytes for curve25519::StaticKeypair {

        type Bytes = [u8; 32];

        fn to_bytes(&self) -> Self::Bytes {

            self.secret.to_bytes()

        }

    }

    impl ToBytes for curve25519::PublicKey {

        type Bytes = [u8; 32];

        fn to_bytes(&self) -> Self::Bytes {

            self.to_bytes()

        }

    }

    /// In-memory mangling. Pass private or public ED25519 key.

    fn mangle_ed25519(key: &mut String) {

        if key.len() > 150 {

            // private

            key.replace_range(107..178, "hello");

        } else {

            // public

            key.insert_str(12, "garbage");

        }

    }

    /// This macro checks if the passed encoded key can be successfully parsed or not. For the

    /// encoded<1> keys that are successfully parsed and decoded<2>, the decoded<2> keys are

    /// re-encoded<3>, and these re-encoded<3> keys are re-decoded<4>. Then, it asserts that:

    ///

    /// * Encoded<1> and re-encoded<3> keys are the same.

    /// * Decoded<2> and re-decoded<4> keys are the same.

    macro_rules! test_parse_ssh_format_erased {

        ($key_ty:tt, $key:expr, err = $expect_err:expr) => {{

            let key_type = KeyType::$key_ty;

            let key = UnparsedOpenSshKey::new($key.into(), PathBuf::from("/dummy/path"));

            let err = key

                .parse_ssh_format_erased(&key_type)

                .map(|_| "<type erased key>")

                .unwrap_err();

            assert_eq!(err.to_string(), $expect_err);

        }};

        ($key_ty:tt, $enc1:expr, $expected_ty:path, $comment:expr) => {{

            let enc1 = $enc1.trim();

            let key_type = KeyType::$key_ty;

            let key = UnparsedOpenSshKey::new(enc1.into(), PathBuf::from("/test/path"));

            let erased_key = key.parse_ssh_format_erased(&key_type).unwrap();

            let Ok(dec1) = erased_key.downcast::<$expected_ty>() else {

                panic!("failed to downcast");

            };

            let keystore_item = EncodableItem::as_keystore_item(&*dec1).unwrap();

            let enc2 = match keystore_item {

                KeystoreItem::Key(key) => key.to_openssh_string($comment).unwrap(),

                _ => panic!("unexpected keystore item type {keystore_item:?}"),

            };

            let enc2 = enc2.trim();

            // TODO: From

            // https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/2873#note_3178959:

            // > the problem is that the two keys have different checkint values. When a PrivateKey is

            // > parsed, its checkint is saved, and used when reencoding the key, so technically the

            // > checkints should be the same. However, arti only actually stores the underlying

            // > KeypairData and not the actual PrivateKey, so in SshKeyData::to_openssh_string, we

            // > create a brand new PrivateKey from that KeypairData, which winds up with a None

            // > checkint. When that PrivateKey then gets serialized, the checkint is taken from

            // > KeypairData::checkint, which isn't the same as the checkint ssh-keygen put in the

            // > original key. It's a weird implementation detail, but technically not a bug.

            match key_type {

                KeyType::Ed25519Keypair |

                KeyType::X25519StaticKeypair |

                KeyType::Ed25519ExpandedKeypair => (),

                _ => assert_eq!(enc1, enc2),

            }

            let key = UnparsedOpenSshKey::new(enc2.into(), PathBuf::from("/test/path"));

            let erased_key = key.parse_ssh_format_erased(&key_type).unwrap();

            let Ok(dec2) = erased_key.downcast::<$expected_ty>() else {

                panic!("failed to downcast");

            };

            assert_eq!(dec1.to_bytes(), dec2.to_bytes());

        }};

    }

    #[test]

    fn wrong_key_type() {

        let key_type = KeyType::Ed25519Keypair;

        let key = UnparsedOpenSshKey::new(DSA_OPENSSH.into(), PathBuf::from("/test/path"));

        let err = key

            .parse_ssh_format_erased(&key_type)

            .map(|_| "<type erased key>")

            .unwrap_err();

        assert_eq!(

            err.to_string(),

            format!(

                "Unexpected OpenSSH key type: wanted {}, found {}",

                SshKeyAlgorithm::Ed25519,

                SshKeyAlgorithm::Dsa

            )

        );

        test_parse_ssh_format_erased!(

            Ed25519Keypair,

            DSA_OPENSSH,

            err = format!(

                "Unexpected OpenSSH key type: wanted {}, found {}",

                SshKeyAlgorithm::Ed25519,

                SshKeyAlgorithm::Dsa

            )

        );

    }

    #[test]

    fn invalid_ed25519_key() {

        test_parse_ssh_format_erased!(

            Ed25519Keypair,

            ED25519_OPENSSH_BAD,

            err = "Failed to parse OpenSSH with type Ed25519Keypair"

        );

        test_parse_ssh_format_erased!(

            Ed25519Keypair,

            ED25519_OPENSSH_BAD_PUB,

            err = "Failed to parse OpenSSH with type Ed25519Keypair"

        );

        test_parse_ssh_format_erased!(

            Ed25519PublicKey,

            ED25519_OPENSSH_BAD_PUB,

            err = "Failed to parse OpenSSH with type Ed25519PublicKey"

        );

        if let Ok((mut bad, mut bad_pub)) = sshkeygen_ed25519_strings() {

            mangle_ed25519(&mut bad);

            mangle_ed25519(&mut bad_pub);

            test_parse_ssh_format_erased!(

                Ed25519Keypair,

                &bad,

                err = "Failed to parse OpenSSH with type Ed25519Keypair"

            );

            test_parse_ssh_format_erased!(

                Ed25519Keypair,

                &bad_pub,

                err = "Failed to parse OpenSSH with type Ed25519Keypair"

            );

            test_parse_ssh_format_erased!(

                Ed25519PublicKey,

                &bad_pub,

                err = "Failed to parse OpenSSH with type Ed25519PublicKey"

            );

        }

    }

    #[test]

    fn ed25519_key() {

        test_parse_ssh_format_erased!(

            Ed25519Keypair,

            ED25519_OPENSSH,

            ed25519::Keypair,

            ED25519_OPENSSH_COMMENT

        );

        test_parse_ssh_format_erased!(

            Ed25519PublicKey,

            ED25519_OPENSSH_PUB,

            ed25519::PublicKey,

            ED25519_OPENSSH_COMMENT

        );

        if let Ok((enc1, enc1_pub)) = sshkeygen_ed25519_strings() {

            test_parse_ssh_format_erased!(

                Ed25519Keypair,

                enc1,

                ed25519::Keypair,

                ED25519_SSHKEYGEN_COMMENT

            );

            test_parse_ssh_format_erased!(

                Ed25519PublicKey,

                enc1_pub,

                ed25519::PublicKey,

                ED25519_SSHKEYGEN_COMMENT

            );

        }

    }

    #[test]

    fn invalid_expanded_ed25519_key() {

        test_parse_ssh_format_erased!(

            Ed25519ExpandedKeypair,

            ED25519_EXPANDED_OPENSSH_BAD,

            err = "Failed to parse OpenSSH with type Ed25519ExpandedKeypair"

        );

    }

    #[test]

    fn expanded_ed25519_key() {

        test_parse_ssh_format_erased!(

            Ed25519ExpandedKeypair,

            ED25519_EXPANDED_OPENSSH,

            ed25519::ExpandedKeypair,

            ED25519_EXPANDED_OPENSSH_COMMENT

        );

        test_parse_ssh_format_erased!(

            Ed25519PublicKey,

            ED25519_EXPANDED_OPENSSH_PUB, // using ed25519-expanded for public keys doesn't make sense

            err = "Failed to parse OpenSSH with type Ed25519PublicKey"

        );

    }

    #[test]

    fn x25519_key() {

        test_parse_ssh_format_erased!(

            X25519StaticKeypair,

            X25519_OPENSSH,

            curve25519::StaticKeypair,

            X25519_OPENSSH_COMMENT

        );

        test_parse_ssh_format_erased!(

            X25519PublicKey,

            X25519_OPENSSH_PUB,

            curve25519::PublicKey,

            X25519_OPENSSH_COMMENT

        );

    }

    #[test]

    fn invalid_x25519_key() {

        test_parse_ssh_format_erased!(

            X25519StaticKeypair,

            X25519_OPENSSH_UNKNOWN_ALGORITHM,

            err = "Unexpected OpenSSH key type: wanted X25519, found pangolin@torproject.org"

        );

        test_parse_ssh_format_erased!(

            X25519PublicKey,

            X25519_OPENSSH_UNKNOWN_ALGORITHM, // Note: this is a private key

            err = "Failed to parse OpenSSH with type X25519PublicKey"

        );

        test_parse_ssh_format_erased!(

            X25519PublicKey,

            X25519_OPENSSH_UNKNOWN_ALGORITHM_PUB,

            err = "Unexpected OpenSSH key type: wanted X25519, found armadillo@torproject.org"

        );

    }

}