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    //! Registry authentication support.

    mod asymmetric;

    use crate::util::{config, config::ConfigKey, CanonicalUrl, CargoResult, Config, IntoUrl};
    use anyhow::{bail, format_err, Context as _};
    use cargo_util::ProcessError;
    use core::fmt;
    use serde::Deserialize;
    use std::collections::HashMap;
    use std::error::Error;
    use std::io::{Read, Write};
    use std::ops::Deref;
    use std::path::PathBuf;
    use std::process::{Command, Stdio};
    use url::Url;

    use crate::core::SourceId;
    use crate::ops::RegistryCredentialConfig;

    pub use self::asymmetric::paserk_public_from_paserk_secret;

    use super::config::CredentialCacheValue;

    /// A wrapper for values that should not be printed.
    ///
    /// This type does not implement `Display`, and has a `Debug` impl that hides
    /// the contained value.
    ///
    /// ```
    /// # use cargo::util::auth::Secret;
    /// let token = Secret::from("super secret string");
    /// assert_eq!(format!("{:?}", token), "Secret { inner: \"REDACTED\" }");
    /// ```
    ///
    /// Currently, we write a borrowed `Secret<T>` as `Secret<&T>`.
    /// The [`as_deref`](Secret::as_deref) and [`owned`](Secret::owned) methods can
    /// be used to convert back and forth between `Secret<String>` and `Secret<&str>`.
    #[derive(Default, Clone, PartialEq, Eq)]
    pub struct Secret<T> {
        inner: T,
    }

    impl<T> Secret<T> {
        /// Unwraps the contained value.
        ///
        /// Use of this method marks the boundary of where the contained value is
        /// hidden.
        pub fn expose(self) -> T {
            self.inner
        }

        /// Converts a `Secret<T>` to a `Secret<&T::Target>`.
        /// ```
        /// # use cargo::util::auth::Secret;
        /// let owned: Secret<String> = Secret::from(String::from("token"));
        /// let borrowed: Secret<&str> = owned.as_deref();
        /// ```
        pub fn as_deref(&self) -> Secret<&<T as Deref>::Target>
        where
            T: Deref,
        {
            Secret::from(self.inner.deref())
        }

        /// Converts a `Secret<T>` to a `Secret<&T>`.
        pub fn as_ref(&self) -> Secret<&T> {
            Secret::from(&self.inner)
        }

        /// Converts a `Secret<T>` to a `Secret<U>` by applying `f` to the contained value.
        pub fn map<U, F>(self, f: F) -> Secret<U>
        where
            F: FnOnce(T) -> U,
        {
            Secret::from(f(self.inner))
        }
    }

    impl<T: ToOwned + ?Sized> Secret<&T> {
        /// Converts a `Secret` containing a borrowed type to a `Secret` containing the
        /// corresponding owned type.
        /// ```
        /// # use cargo::util::auth::Secret;
        /// let borrowed: Secret<&str> = Secret::from("token");
        /// let owned: Secret<String> = borrowed.owned();
        /// ```
        pub fn owned(&self) -> Secret<<T as ToOwned>::Owned> {
            Secret::from(self.inner.to_owned())
        }
    }

    impl<T, E> Secret<Result<T, E>> {
        /// Converts a `Secret<Result<T, E>>` to a `Result<Secret<T>, E>`.
        pub fn transpose(self) -> Result<Secret<T>, E> {
            self.inner.map(|v| Secret::from(v))
        }
    }

    impl<T: AsRef<str>> Secret<T> {
        /// Checks if the contained value is empty.
        pub fn is_empty(&self) -> bool {
            self.inner.as_ref().is_empty()
        }
    }

    impl<T> From<T> for Secret<T> {
        fn from(inner: T) -> Self {
            Self { inner }
        }
    }

    impl<T> fmt::Debug for Secret<T> {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            f.debug_struct("Secret")
                .field("inner", &"REDACTED")
                .finish()
        }
    }

    /// Get the credential configuration for a `SourceId`.
    pub fn registry_credential_config(
        config: &Config,
        sid: &SourceId,
    ) -> CargoResult<RegistryCredentialConfig> {
        #[derive(Deserialize)]
        #[serde(rename_all = "kebab-case")]
        struct RegistryConfig {
            index: Option<String>,
            token: Option<String>,
            credential_process: Option<config::PathAndArgs>,
            secret_key: Option<String>,
            secret_key_subject: Option<String>,
            #[serde(rename = "default")]
            _default: Option<String>,
            #[serde(rename = "protocol")]
            _protocol: Option<String>,
        }

        log::trace!("loading credential config for {}", sid);
        config.load_credentials()?;
        if !sid.is_remote_registry() {
            bail!(
                "{} does not support API commands.\n\
                 Check for a source-replacement in .cargo/config.",
                sid
            );
        }

        // Handle crates.io specially, since it uses different configuration keys.
        if sid.is_crates_io() {
            config.check_registry_index_not_set()?;
            let RegistryConfig {
                token,
                credential_process,
                secret_key,
                secret_key_subject,
                ..
            } = config.get::<RegistryConfig>("registry")?;
            return registry_credential_config_inner(
                true,
                None,
                token.map(Secret::from),
                credential_process,
                secret_key.map(Secret::from),
                secret_key_subject,
                config,
            );
        }

        // Find the SourceId's name by its index URL. If environment variables
        // are available they will be preferred over configuration values.
        //
        // The fundamental problem is that we only know the index url of the registry
        // for certain. For example, an unnamed registry source can come from the `--index`
        // command line argument, or from a Cargo.lock file. For this reason, we always
        // attempt to discover the name by looking it up by the index URL.
        //
        // This also allows the authorization token for a registry to be set
        // without knowing the registry name by using the _INDEX and _TOKEN
        // environment variables.
        let name = {
            // Discover names from environment variables.
            let index = sid.canonical_url();
            let mut names: Vec<_> = config
                .env()
                .filter_map(|(k, v)| {
                    Some((
                        k.strip_prefix("CARGO_REGISTRIES_")?
                            .strip_suffix("_INDEX")?,
                        v,
                    ))
                })
                .filter_map(|(k, v)| Some((k, CanonicalUrl::new(&v.into_url().ok()?).ok()?)))
                .filter(|(_, v)| v == index)
                .map(|(k, _)| k.to_lowercase())
                .collect();

            // Discover names from the configuration only if none were found in the environment.
            if names.len() == 0 {
                names = config
                    .get::<HashMap<String, RegistryConfig>>("registries")?
                    .iter()
                    .filter_map(|(k, v)| Some((k, v.index.as_deref()?)))
                    .filter_map(|(k, v)| Some((k, CanonicalUrl::new(&v.into_url().ok()?).ok()?)))
                    .filter(|(_, v)| v == index)
                    .map(|(k, _)| k.to_string())
                    .collect();
            }
            names.sort();
            match names.len() {
                0 => None,
                1 => Some(std::mem::take(&mut names[0])),
                _ => anyhow::bail!(
                    "multiple registries are configured with the same index url '{}': {}",
                    &sid.as_url(),
                    names.join(", ")
                ),
            }
        };

        // It's possible to have a registry configured in a Cargo config file,
        // then override it with configuration from environment variables.
        // If the name doesn't match, leave a note to help the user understand
        // the potentially confusing situation.
        if let Some(name) = name.as_deref() {
            if Some(name) != sid.alt_registry_key() {
                config.shell().note(format!(
                    "name of alternative registry `{}` set to `{name}`",
                    sid.url()
                ))?
            }
        }

        let (token, credential_process, secret_key, secret_key_subject) = if let Some(name) = &name {
            log::debug!("found alternative registry name `{name}` for {sid}");
            let RegistryConfig {
                token,
                secret_key,
                secret_key_subject,
                credential_process,
                ..
            } = config.get::<RegistryConfig>(&format!("registries.{name}"))?;
            (token, credential_process, secret_key, secret_key_subject)
        } else {
            log::debug!("no registry name found for {sid}");
            (None, None, None, None)
        };

        registry_credential_config_inner(
            false,
            name.as_deref(),
            token.map(Secret::from),
            credential_process,
            secret_key.map(Secret::from),
            secret_key_subject,
            config,
        )
    }

    fn registry_credential_config_inner(
        is_crates_io: bool,
        name: Option<&str>,
        token: Option<Secret<String>>,
        credential_process: Option<config::PathAndArgs>,
        secret_key: Option<Secret<String>>,
        secret_key_subject: Option<String>,
        config: &Config,
    ) -> CargoResult<RegistryCredentialConfig> {
        let credential_process =
            credential_process.filter(|_| config.cli_unstable().credential_process);
        let secret_key = secret_key.filter(|_| config.cli_unstable().registry_auth);
        let secret_key_subject = secret_key_subject.filter(|_| config.cli_unstable().registry_auth);
        let err_both = |token_key: &str, proc_key: &str| {
            let registry = if is_crates_io {
                "".to_string()
            } else {
                format!(" for registry `{}`", name.unwrap_or("UN-NAMED"))
            };
            Err(format_err!(
                "both `{token_key}` and `{proc_key}` \
                were specified in the config{registry}.\n\
                Only one of these values may be set, remove one or the other to proceed.",
            ))
        };
        Ok(
            match (token, credential_process, secret_key, secret_key_subject) {
                (Some(_), Some(_), _, _) => return err_both("token", "credential-process"),
                (Some(_), _, Some(_), _) => return err_both("token", "secret-key"),
                (_, Some(_), Some(_), _) => return err_both("credential-process", "secret-key"),
                (_, _, None, Some(_)) => {
                    let registry = if is_crates_io {
                        "".to_string()
                    } else {
                        format!(" for registry `{}`", name.as_ref().unwrap())
                    };
                    return Err(format_err!(
                        "`secret-key-subject` was set but `secret-key` was not in the config{}.\n\
                        Either set the `secret-key` or remove the `secret-key-subject`.",
                        registry
                    ));
                }
                (Some(token), _, _, _) => RegistryCredentialConfig::Token(token),
                (_, Some(process), _, _) => RegistryCredentialConfig::Process((
                    process.path.resolve_program(config),
                    process.args,
                )),
                (None, None, Some(key), subject) => {
                    RegistryCredentialConfig::AsymmetricKey((key, subject))
                }
                (None, None, None, _) => {
                    if !is_crates_io {
                        // If we couldn't find a registry-specific credential, try the global credential process.
                        if let Some(process) = config
                            .get::<Option<config::PathAndArgs>>("registry.credential-process")?
                            .filter(|_| config.cli_unstable().credential_process)
                        {
                            return Ok(RegistryCredentialConfig::Process((
                                process.path.resolve_program(config),
                                process.args,
                            )));
                        }
                    }
                    RegistryCredentialConfig::None
                }
            },
        )
    }

    #[derive(Debug, PartialEq)]
    pub enum AuthorizationErrorReason {
        TokenMissing,
        TokenRejected,
    }

    impl fmt::Display for AuthorizationErrorReason {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            match self {
                AuthorizationErrorReason::TokenMissing => write!(f, "no token found"),
                AuthorizationErrorReason::TokenRejected => write!(f, "token rejected"),
            }
        }
    }

    /// An authorization error from accessing a registry.
    #[derive(Debug)]
    pub struct AuthorizationError {
        /// Url that was attempted
        pub sid: SourceId,
        /// The `registry.default` config value.
        pub default_registry: Option<String>,
        /// Url where the user could log in.
        pub login_url: Option<Url>,
        /// Specific reason indicating what failed
        pub reason: AuthorizationErrorReason,
    }
    impl Error for AuthorizationError {}
    impl fmt::Display for AuthorizationError {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            if self.sid.is_crates_io() {
                let args = if self.default_registry.is_some() {
                    " --registry crates-io"
                } else {
                    ""
                };
                write!(
                    f,
                    "{}, please run `cargo login{args}`\nor use environment variable CARGO_REGISTRY_TOKEN",
                    self.reason
                )
            } else if let Some(name) = self.sid.alt_registry_key() {
                let key = ConfigKey::from_str(&format!("registries.{name}.token"));
                write!(
                    f,
                    "{} for `{}`, please run `cargo login --registry {name}`\nor use environment variable {}",
                    self.reason,
                    self.sid.display_registry_name(),
                    key.as_env_key(),
                )
            } else if self.reason == AuthorizationErrorReason::TokenMissing {
                write!(
                    f,
                    r#"{} for `{}`
    consider setting up an alternate registry in Cargo's configuration
    as described by https://doc.rust-lang.org/cargo/reference/registries.html

    [registries]
    my-registry = {{ index = "{}" }}
    "#,
                    self.reason,
                    self.sid.display_registry_name(),
                    self.sid.url()
                )
            } else {
                write!(
                    f,
                    r#"{} for `{}`"#,
                    self.reason,
                    self.sid.display_registry_name(),
                )
            }
        }
    }

    // Store a token in the cache for future calls.
    pub fn cache_token(config: &Config, sid: &SourceId, token: Secret<&str>) {
        let url = sid.canonical_url();
        config.credential_cache().insert(
            url.clone(),
            CredentialCacheValue {
                from_commandline: true,
                independent_of_endpoint: true,
                token_value: token.owned(),
            },
        );
    }

    /// Returns the token to use for the given registry.
    /// If a `login_url` is provided and a token is not available, the
    /// login_url will be included in the returned error.
    pub fn auth_token(
        config: &Config,
        sid: &SourceId,
        login_url: Option<&Url>,
        mutation: Option<Mutation<'_>>,
    ) -> CargoResult<String> {
        match auth_token_optional(config, sid, mutation.as_ref())? {
            Some(token) => Ok(token.expose()),
            None => Err(AuthorizationError {
                sid: sid.clone(),
                default_registry: config.default_registry()?,
                login_url: login_url.cloned(),
                reason: AuthorizationErrorReason::TokenMissing,
            }
            .into()),
        }
    }

    /// Returns the token to use for the given registry.
    fn auth_token_optional(
        config: &Config,
        sid: &SourceId,
        mutation: Option<&'_ Mutation<'_>>,
    ) -> CargoResult<Option<Secret<String>>> {
        let mut cache = config.credential_cache();
        let url = sid.canonical_url();

        if let Some(cache_token_value) = cache.get(url) {
            // Tokens for endpoints that do not involve a mutation can always be reused.
            // If the value is put in the cache by the command line, then we reuse it without looking at the configuration.
            if cache_token_value.from_commandline
                || cache_token_value.independent_of_endpoint
                || mutation.is_none()
            {
                return Ok(Some(cache_token_value.token_value.clone()));
            }
        }

        let credential = registry_credential_config(config, sid)?;
        let (independent_of_endpoint, token) = match credential {
            RegistryCredentialConfig::None => return Ok(None),
            RegistryCredentialConfig::Token(config_token) => (true, config_token),
            RegistryCredentialConfig::Process(process) => {
                // todo: PASETO with process
                let (independent_of_endpoint, token) =
                    run_command(config, &process, sid, Action::Get)?.unwrap();
                (independent_of_endpoint, Secret::from(token))
            }
            cred @ RegistryCredentialConfig::AsymmetricKey(..) => {
                let token = asymmetric::public_token_from_credential(cred, sid, mutation)?;
                (false, token)
            }
        };

        if independent_of_endpoint || mutation.is_none() {
            cache.insert(
                url.clone(),
                CredentialCacheValue {
                    from_commandline: false,
                    independent_of_endpoint,
                    token_value: token.clone(),
                },
            );
        }
        Ok(Some(token))
    }

    /// A record of what kind of operation is happening that we should generate a token for.
    pub enum Mutation<'a> {
        /// Before we generate a crate file for the users attempt to publish,
        /// we need to check if we are configured correctly to generate a token.
        /// This variant is used to make sure that we can generate a token,
        /// to error out early if the token is not configured correctly.
        PrePublish,
        /// The user is attempting to publish a crate.
        Publish {
            /// The name of the crate
            name: &'a str,
            /// The version of the crate
            vers: &'a str,
            /// The checksum of the crate file being uploaded
            cksum: &'a str,
        },
        /// The user is attempting to yank a crate.
        Yank {
            /// The name of the crate
            name: &'a str,
            /// The version of the crate
            vers: &'a str,
        },
        /// The user is attempting to unyank a crate.
        Unyank {
            /// The name of the crate
            name: &'a str,
            /// The version of the crate
            vers: &'a str,
        },
        /// The user is attempting to modify the owners of a crate.
        Owners {
            /// The name of the crate
            name: &'a str,
        },
    }

    enum Action {
        Get,
        Store(String),
        Erase,
    }

    /// Saves the given token.
    pub fn login(config: &Config, sid: &SourceId, token: RegistryCredentialConfig) -> CargoResult<()> {
        match registry_credential_config(config, sid)? {
            RegistryCredentialConfig::Process(process) => {
                let token = token
                    .as_token()
                    .expect("credential_process cannot use login with a secret_key")
                    .expose()
                    .to_owned();
                run_command(config, &process, sid, Action::Store(token))?;
            }
            _ => {
                config::save_credentials(config, Some(token), &sid)?;
            }
        };
        Ok(())
    }

    /// Removes the token for the given registry.
    pub fn logout(config: &Config, sid: &SourceId) -> CargoResult<()> {
        match registry_credential_config(config, sid)? {
            RegistryCredentialConfig::Process(process) => {
                run_command(config, &process, sid, Action::Erase)?;
            }
            _ => {
                config::save_credentials(config, None, &sid)?;
            }
        };
        Ok(())
    }

    fn run_command(
        config: &Config,
        process: &(PathBuf, Vec<String>),
        sid: &SourceId,
        action: Action,
    ) -> CargoResult<Option<(bool, String)>> {
        let index_url = sid.url().as_str();
        let cred_proc;
        let (exe, args) = if process.0.to_str().unwrap_or("").starts_with("cargo:") {
            cred_proc = sysroot_credential(config, process)?;
            &cred_proc
        } else {
            process
        };
        if !args.iter().any(|arg| arg.contains("{action}")) {
            let msg = |which| {
                format!(
                    "credential process `{}` cannot be used to {}, \
                     the credential-process configuration value must pass the \
                     `{{action}}` argument in the config to support this command",
                    exe.display(),
                    which
                )
            };
            match action {
                Action::Get => {}
                Action::Store(_) => bail!(msg("log in")),
                Action::Erase => bail!(msg("log out")),
            }
        }
        // todo: PASETO with process
        let independent_of_endpoint = true;
        let action_str = match action {
            Action::Get => "get",
            Action::Store(_) => "store",
            Action::Erase => "erase",
        };
        let args: Vec<_> = args
            .iter()
            .map(|arg| {
                arg.replace("{action}", action_str)
                    .replace("{index_url}", index_url)
            })
            .collect();

        let mut cmd = Command::new(&exe);
        cmd.args(args)
            .env(crate::CARGO_ENV, config.cargo_exe()?)
            .env("CARGO_REGISTRY_INDEX_URL", index_url);
        if sid.is_crates_io() {
            cmd.env("CARGO_REGISTRY_NAME_OPT", "crates-io");
        } else if let Some(name) = sid.alt_registry_key() {
            cmd.env("CARGO_REGISTRY_NAME_OPT", name);
        }
        match action {
            Action::Get => {
                cmd.stdout(Stdio::piped());
            }
            Action::Store(_) => {
                cmd.stdin(Stdio::piped());
            }
            Action::Erase => {}
        }
        let mut child = cmd.spawn().with_context(|| {
            let verb = match action {
                Action::Get => "fetch",
                Action::Store(_) => "store",
                Action::Erase => "erase",
            };
            format!(
                "failed to execute `{}` to {} authentication token for registry `{}`",
                exe.display(),
                verb,
                sid.display_registry_name(),
            )
        })?;
        let mut token = None;
        match &action {
            Action::Get => {
                let mut buffer = String::new();
                log::debug!("reading into buffer");
                child
                    .stdout
                    .as_mut()
                    .unwrap()
                    .read_to_string(&mut buffer)
                    .with_context(|| {
                        format!(
                            "failed to read token from registry credential process `{}`",
                            exe.display()
                        )
                    })?;
                if let Some(end) = buffer.find('\n') {
                    if buffer.len() > end + 1 {
                        bail!(
                            "credential process `{}` returned more than one line of output; \
                             expected a single token",
                            exe.display()
                        );
                    }
                    buffer.truncate(end);
                }
                token = Some((independent_of_endpoint, buffer));
            }
            Action::Store(token) => {
                writeln!(child.stdin.as_ref().unwrap(), "{}", token).with_context(|| {
                    format!(
                        "failed to send token to registry credential process `{}`",
                        exe.display()
                    )
                })?;
            }
            Action::Erase => {}
        }
        let status = child.wait().with_context(|| {
            format!(
                "registry credential process `{}` exit failure",
                exe.display()
            )
        })?;
        if !status.success() {
            let msg = match action {
                Action::Get => "failed to authenticate to registry",
                Action::Store(_) => "failed to store token to registry",
                Action::Erase => "failed to erase token from registry",
            };
            return Err(ProcessError::new(
                &format!(
                    "registry credential process `{}` {} `{}`",
                    exe.display(),
                    msg,
                    sid.display_registry_name()
                ),
                Some(status),
                None,
            )
            .into());
        }
        Ok(token)
    }

    /// Gets the path to the libexec processes in the sysroot.
    fn sysroot_credential(
        config: &Config,
        process: &(PathBuf, Vec<String>),
    ) -> CargoResult<(PathBuf, Vec<String>)> {
        let cred_name = process.0.to_str().unwrap().strip_prefix("cargo:").unwrap();
        let cargo = config.cargo_exe()?;
        let root = cargo
            .parent()
            .and_then(|p| p.parent())
            .ok_or_else(|| format_err!("expected cargo path {}", cargo.display()))?;
        let exe = root.join("libexec").join(format!(
            "cargo-credential-{}{}",
            cred_name,
            std::env::consts::EXE_SUFFIX
        ));
        let mut args = process.1.clone();
        if !args.iter().any(|arg| arg == "{action}") {
            args.push("{action}".to_string());
        }
        Ok((exe, args))
    }