hyperhive/hive-c0re/src/forge/reader.rs

//! The credential this hive reads the forge with: its own read-only account,
//! whose token `swarm-controller` mints into the store at
//! `swarm/hives/<hive>/forge/token`, and the core token file where the store
//! holds none.
//!
//! The file is the fallback so a hive deployed before the controller mints its
//! token keeps the reads it had: the forge host holds the file, no other hive
//! does.

use super::{basic_auth_header, core_token};

/// The basic-auth user [`ReaderToken::auth_header`] names for the core token.
const CORE_LOGIN: &str = "core";

/// A forge token and the account it belongs to.
///
/// No `Debug` derive: `value` is a live forge credential.
pub struct ReaderToken {
    login: String,
    value: String,
}

impl std::fmt::Debug for ReaderToken {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ReaderToken")
            .field("login", &self.login)
            .field("value", &"<redacted>")
            .finish()
    }
}

impl ReaderToken {
    /// The token itself, for an API client.
    pub fn value(&self) -> &str {
        &self.value
    }

    /// The `http.extraHeader` value for git; see [`basic_auth_header`].
    pub fn auth_header(&self) -> String {
        basic_auth_header(&self.login, &self.value)
    }
}

/// The token to read the forge with, or `None` when this hive has neither.
///
/// 🩸 Logs the store path and which source won, never a value.
pub async fn reader_token() -> Option<ReaderToken> {
    pick(stored_reader_token().await, core_token())
}

/// The store's token wins over the core file's.
fn pick(stored: Option<ReaderToken>, core: Option<String>) -> Option<ReaderToken> {
    let picked = stored.or_else(|| {
        core.map(|value| ReaderToken {
            login: CORE_LOGIN.to_owned(),
            value,
        })
    });
    if let Some(t) = &picked {
        tracing::debug!(login = %t.login, "forge: reading as this account");
    } else {
        tracing::debug!("forge: no read token in the store or the core token file");
    }
    picked
}

/// This hive's token from the store, under the hive's own identity.
///
/// `None`, never an error, for every way it can come up empty — no hive name,
/// no `BAO_*` identity, an unreachable store, nothing at the path — the same
/// as `matrix::stored_sender_token`, and for the same reason: each sends the
/// caller to the fallback.
async fn stored_reader_token() -> Option<ReaderToken> {
    let hive = std::env::var("HYPERHIVE_HIVE_NAME")
        .ok()
        .filter(|h| !h.is_empty())?;
    let path = match swarm_secret_client::forge::hive_token_path(&hive) {
        Ok(path) => path,
        Err(e) => {
            tracing::warn!(error = %e, "forge: this hive's name does not form a store path");
            return None;
        }
    };
    let store = match swarm_secret_client::SecretStore::from_env(&hive).await {
        Ok(store) => store,
        Err(e) => {
            tracing::debug!(error = %e, "forge: no swarm secret store to read the hive token from");
            return None;
        }
    };
    match store
        .read::<swarm_secret_client::forge::Credential>(&path)
        .await
    {
        Ok(credential) if !credential.value.trim().is_empty() => Some(ReaderToken {
            login: swarm_secret_client::forge::hive_login(&hive),
            value: credential.value.trim().to_owned(),
        }),
        Ok(_) => {
            tracing::warn!(%path, "forge: the stored hive token is empty");
            None
        }
        Err(e) => {
            tracing::debug!(%path, error = %e, "forge: no hive token in the store");
            None
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn stored() -> ReaderToken {
        ReaderToken {
            login: "hive-alpha".to_owned(),
            value: "from-the-store".to_owned(),
        }
    }

    #[test]
    fn the_store_wins_over_the_core_file() {
        let t = pick(Some(stored()), Some("from-the-file".to_owned())).expect("a token");
        assert_eq!(t.value(), "from-the-store");
        assert_eq!(t.login, "hive-alpha");
    }

    #[test]
    fn the_core_file_is_the_fallback() {
        let t = pick(None, Some("from-the-file".to_owned())).expect("a token");
        assert_eq!(t.value(), "from-the-file");
        assert_eq!(t.login, CORE_LOGIN);
    }

    #[test]
    fn neither_is_none() {
        assert!(pick(None, None).is_none());
    }

    #[test]
    fn the_header_names_the_tokens_own_account() {
        use base64::Engine as _;
        let header = stored().auth_header();
        let encoded = header
            .strip_prefix("Authorization: Basic ")
            .expect("a basic auth header");
        let decoded = base64::engine::general_purpose::STANDARD
            .decode(encoded)
            .expect("base64");
        assert_eq!(decoded, b"hive-alpha:from-the-store");
    }

    #[test]
    fn debug_never_prints_the_value() {
        let shown = format!("{:?}", stored());
        assert!(!shown.contains("from-the-store"), "{shown}");
        assert!(shown.contains("hive-alpha"), "{shown}");
    }
}