gatekeep-sqlx 5.0.0

//! Dovecote-backed decision audit event construction.
//!
//! Gatekeep owns the typed decision value; Dovecote owns durable SQL event and
//! delivery state. This module only validates the application source and
//! serializes one complete [`gatekeep::AuditEntry`] into Dovecote's event
//! shape. It deliberately contains no Gatekeep-owned audit tables or paging
//! model.

mod attempt;
pub use attempt::{ATTEMPT_AUDIT_EVENT_TYPE, AttemptAuditEventError, decode_authorization_attempt};

use gatekeep::{AuditEntry, AuditEntryError, DecisionAuditId, GatekeepError, LegacyAuditEntry};
use serde_json::Error as JsonError;
use thiserror::Error;
use url::Url;

use dovecote::{ContentType, EventData, EventId, EventSource, EventType, NewEvent, StreamName};

#[cfg(feature = "mysql")]
mod mysql;
#[cfg(feature = "postgres")]
mod postgres;
#[cfg(feature = "sqlite")]
mod sqlite;

#[cfg(feature = "mysql")]
pub use self::mysql::{MySqlDovecoteAudit, MySqlDovecoteAuditError};
#[cfg(feature = "postgres")]
pub use self::postgres::{PgDovecoteAudit, PgDovecoteAuditError};
#[cfg(feature = "sqlite")]
pub use self::sqlite::{SqliteDovecoteAudit, SqliteDovecoteAuditError};

/// The default Dovecote stream for Gatekeep decision audit events.
pub const DEFAULT_AUDIT_STREAM: &str = "gatekeep-audit";
/// The durable event type for Gatekeep decision audit events.
pub const DECISION_AUDIT_EVENT_TYPE: &str = "gatekeep.decision_audit_recorded";
/// The explicit JSON content type used for every decision audit event.
pub const DECISION_AUDIT_CONTENT_TYPE: &str = "application/json";
const MAX_AUDIT_PAYLOAD_BYTES: usize = 1_048_576;

/// Configuration required to write Gatekeep audit events.
///
/// The source is application-owned and must be an absolute URI. Gatekeep does
/// not invent an identity for the application or use a process-local default.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct DecisionAuditConfig {
    source: EventSource,
    stream: StreamName,
    event_type: EventType,
    content_type: ContentType,
}

impl DecisionAuditConfig {
    /// Creates configuration using Gatekeep's stable stream, event type, and
    /// JSON content type defaults.
    ///
    /// # Errors
    ///
    /// Returns [`DecisionAuditConfigError::Source`] when `source` is not an
    /// absolute URI accepted by `CloudEvents`.
    pub fn new(source: impl Into<String>) -> Result<Self, DecisionAuditConfigError> {
        let source = source.into();
        let parsed = Url::parse(&source).map_err(|_| DecisionAuditConfigError::Source {
            value: source.clone(),
        })?;
        if parsed.scheme().is_empty() {
            return Err(DecisionAuditConfigError::Source { value: source });
        }

        Ok(Self {
            source: EventSource::new(source)
                .map_err(|source| DecisionAuditConfigError::SourceValue { source })?,
            stream: StreamName::new(DEFAULT_AUDIT_STREAM)
                .map_err(|source| DecisionAuditConfigError::Stream { source })?,
            event_type: EventType::new(DECISION_AUDIT_EVENT_TYPE)
                .map_err(|source| DecisionAuditConfigError::EventType { source })?,
            content_type: ContentType::new(DECISION_AUDIT_CONTENT_TYPE)
                .map_err(|source| DecisionAuditConfigError::ContentType { source })?,
        })
    }

    /// Returns the configured absolute event source.
    #[must_use]
    pub const fn source(&self) -> &EventSource {
        &self.source
    }

    /// Returns the fixed Gatekeep audit stream.
    #[must_use]
    pub const fn stream(&self) -> &StreamName {
        &self.stream
    }

    /// Returns the fixed Gatekeep audit event type.
    #[must_use]
    pub const fn event_type(&self) -> &EventType {
        &self.event_type
    }
}

/// Errors while validating the application-owned audit source.
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum DecisionAuditConfigError {
    /// The source was not an absolute URI.
    #[error("decision audit source must be an absolute URI: {value}")]
    Source {
        /// Rejected source value.
        value: String,
    },
    /// Dovecote rejected the source URI.
    #[error("invalid decision audit source: {source}")]
    SourceValue {
        /// Validation failure from Dovecote.
        #[source]
        source: dovecote::ValidationError,
    },
    /// The built-in stream default was rejected by Dovecote.
    #[error("invalid decision audit stream: {source}")]
    Stream {
        /// Validation failure from Dovecote.
        #[source]
        source: dovecote::ValidationError,
    },
    /// The built-in event type was rejected by Dovecote.
    #[error("invalid decision audit event type: {source}")]
    EventType {
        /// Validation failure from Dovecote.
        #[source]
        source: dovecote::ValidationError,
    },
    /// The built-in content type was rejected by Dovecote.
    #[error("invalid decision audit content type: {source}")]
    ContentType {
        /// Validation failure from Dovecote.
        #[source]
        source: dovecote::ValidationError,
    },
}

/// Errors while converting a typed Gatekeep entry into a validated Dovecote
/// event.
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum DecisionAuditEventError {
    /// Encoded evidence exceeds the supported one MiB payload bound.
    #[error("decision audit payload exceeds size limit")]
    PayloadTooLarge,
    /// The entry is not a valid current decision record.
    #[error(transparent)]
    Entry(#[from] AuditEntryError),
    /// The typed entry could not be serialized as JSON.
    #[error("serialize decision audit entry")]
    Json(#[source] JsonError),
    /// The entry uses the migration-only legacy identity namespace.
    #[error("validate decision audit identity")]
    Identity(#[source] GatekeepError),
    /// The generated event identity or event content failed Dovecote
    /// validation.
    #[error("validate decision audit event")]
    Validation(#[source] dovecote::ValidationError),
}

/// Errors returned while decoding a Dovecote event as a Gatekeep decision
/// audit entry.
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum DecisionAuditDecodeError {
    /// The payload represented a current entry but failed its tenant-binding
    /// invariants.
    #[error(transparent)]
    Entry(#[from] AuditEntryError),
    /// A required Dovecote event attribute did not match Gatekeep's contract.
    #[error("unexpected Gatekeep decision audit event {field}")]
    UnexpectedShape {
        /// Attribute that did not match.
        field: &'static str,
    },
    /// The event did not carry JSON data.
    #[error("decision audit event has no JSON payload")]
    MissingPayload,
    /// The event payload was not a valid typed entry.
    #[error("decode decision audit payload")]
    Json(#[source] JsonError),
    /// The event identity suffix was not a valid typed decision identity.
    #[error("decode decision audit identity")]
    Identity(#[source] GatekeepError),
}

/// Errors returned while decoding a historical audit event explicitly.
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum LegacyDecisionAuditDecodeError {
    /// A required Dovecote event attribute did not match Gatekeep's contract.
    #[error("unexpected Gatekeep legacy decision audit event {field}")]
    UnexpectedShape {
        /// Attribute that did not match.
        field: &'static str,
    },
    /// The event did not carry JSON data.
    #[error("legacy decision audit event has no JSON payload")]
    MissingPayload,
    /// The event payload was not a valid historical typed entry.
    #[error("decode legacy decision audit payload")]
    Json(#[source] JsonError),
    /// The event identity did not match the historical payload identity.
    #[error("legacy decision audit identity does not match the event")]
    Identity,
    /// The storage tenant differs from the historical payload tenant.
    #[error("legacy decision audit tenant does not match the storage row")]
    Tenant,
}

/// Decodes a tenant-scoped Dovecote page item into a typed Gatekeep audit
/// entry.
///
/// The storage tenant is checked against the payload tenant before the entry
/// is returned. This check is essential for exports that combine pages from
/// more than one tenant.
///
/// # Errors
///
/// Returns [`DecisionAuditDecodeError`] when the event shape, payload, or
/// storage tenant does not match Gatekeep's audit contract.
pub fn decode_decision_audit(
    config: &DecisionAuditConfig,
    paged: &dovecote::PagedEvent,
) -> Result<AuditEntry, DecisionAuditDecodeError> {
    let entry = decode_event(config, paged.event())?;
    if paged.tenant_id().as_str() != entry.tenant().as_str() {
        return Err(DecisionAuditDecodeError::UnexpectedShape { field: "tenant" });
    }
    // The current decoder never returns a pre-4.0 representation. Historical
    // records must be migrated through an explicit, separately versioned
    // importer that can prove their shape and provenance.
    entry.validate_current()?;
    Ok(entry)
}

/// Decodes a historical Gatekeep audit event without treating it as current.
///
/// The returned [`LegacyAuditEntry`] retains the pre-4.0 optional fields and
/// must be explicitly mapped by migration code before it can reach an
/// [`gatekeep::AuditSink`].
///
/// # Errors
///
/// Returns [`LegacyDecisionAuditDecodeError`] when event attributes, payload
/// identity, or tenant routing do not match the historical contract.
pub fn decode_legacy_decision_audit(
    config: &DecisionAuditConfig,
    paged: &dovecote::PagedEvent,
) -> Result<LegacyAuditEntry, LegacyDecisionAuditDecodeError> {
    let event = paged.event();
    if event.stream() != config.stream()
        || event.source() != config.source()
        || event.event_type() != config.event_type()
        || event.datacontenttype().map(dovecote::ContentType::as_str)
            != Some(DECISION_AUDIT_CONTENT_TYPE)
    {
        return Err(LegacyDecisionAuditDecodeError::UnexpectedShape {
            field: "attributes",
        });
    }

    let Some(dovecote::EventData::Json(payload)) = event.data() else {
        return Err(LegacyDecisionAuditDecodeError::MissingPayload);
    };

    let entry: LegacyAuditEntry =
        serde_json::from_slice(payload.as_bytes()).map_err(LegacyDecisionAuditDecodeError::Json)?;
    if event.id().as_str() != format!("gatekeep-audit-{}", entry.decision_audit_id)
        || event.time() != Some(entry.occurred_at)
    {
        return Err(LegacyDecisionAuditDecodeError::Identity);
    }

    if paged.tenant_id().as_str() != entry.tenant.as_str() {
        return Err(LegacyDecisionAuditDecodeError::Tenant);
    }

    Ok(entry)
}

fn decode_event(
    config: &DecisionAuditConfig,
    event: &dovecote::StoredEvent,
) -> Result<AuditEntry, DecisionAuditDecodeError> {
    if event.stream() != config.stream()
        || event.source() != config.source()
        || event.event_type() != config.event_type()
        || event.datacontenttype().map(dovecote::ContentType::as_str)
            != Some(DECISION_AUDIT_CONTENT_TYPE)
    {
        return Err(DecisionAuditDecodeError::UnexpectedShape {
            field: "attributes",
        });
    }

    let Some(dovecote::EventData::Json(payload)) = event.data() else {
        return Err(DecisionAuditDecodeError::MissingPayload);
    };

    let entry = decode_payload(payload.as_bytes())?;
    let expected_id = format!("gatekeep-audit-{}", entry.decision_audit_id().as_str());
    if event.id().as_str() != expected_id || event.time() != Some(entry.occurred_at()) {
        return Err(DecisionAuditDecodeError::UnexpectedShape {
            field: "identity or occurrence time",
        });
    }
    // Deserialization already validates this field. Reconstructing it here
    // makes the identity boundary explicit and keeps this check future-proof
    // if AuditEntry's representation ever becomes more permissive.
    DecisionAuditId::new(entry.decision_audit_id().as_str().to_owned())
        .map_err(DecisionAuditDecodeError::Identity)?;
    Ok(entry)
}

/// Decodes payloads through the ordinary current-entry serde contract. Missing
/// binding/evidence is rejected by [`decode_decision_audit`] rather than being
/// silently treated as legacy history.
fn decode_payload(payload: &[u8]) -> Result<AuditEntry, DecisionAuditDecodeError> {
    if payload.len() > MAX_AUDIT_PAYLOAD_BYTES {
        return Err(DecisionAuditDecodeError::UnexpectedShape {
            field: "payload size",
        });
    }
    serde_json::from_slice(payload).map_err(DecisionAuditDecodeError::Json)
}

fn event_from_entry(
    config: &DecisionAuditConfig,
    entry: &AuditEntry,
) -> Result<(dovecote::TenantId, NewEvent), DecisionAuditEventError> {
    entry.validate_current()?;
    // Ordinary enqueue must never create an event in the migration namespace;
    // historical records require an explicit versioned importer.
    DecisionAuditId::new(entry.decision_audit_id().as_str().to_owned())
        .map_err(DecisionAuditEventError::Identity)?;
    let event_id = EventId::new(format!(
        "gatekeep-audit-{}",
        entry.decision_audit_id().as_str()
    ))
    .map_err(DecisionAuditEventError::Validation)?;
    let payload = serde_json::to_vec(entry).map_err(DecisionAuditEventError::Json)?;
    if payload.len() > MAX_AUDIT_PAYLOAD_BYTES {
        return Err(DecisionAuditEventError::PayloadTooLarge);
    }

    let event = NewEvent::builder(
        config.stream.clone(),
        event_id,
        config.source.clone(),
        config.event_type.clone(),
    )
    .time(entry.occurred_at())
    .datacontenttype(config.content_type.clone())
    .data(EventData::json(payload).map_err(DecisionAuditEventError::Validation)?)
    .build()
    .map_err(DecisionAuditEventError::Validation)?;
    let tenant = dovecote::TenantId::new(entry.tenant().as_str().to_owned())
        .map_err(DecisionAuditEventError::Validation)?;
    Ok((tenant, event))
}