kcode-k1-access-profile-store 0.1.0

Rebuildable SQLite projection for K1 saved access profiles
Documentation
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use std::{
    fs,
    io::ErrorKind,
    path::{Path, PathBuf},
    sync::{
        Arc, Mutex,
        atomic::{AtomicBool, Ordering},
    },
    time::{Duration, Instant},
};

use kcode_k1_access_profile_types::{decode_profile, encode_profile};
use kcode_k1_transaction::Transaction;
use kcode_k1_txn_ordering::K1TxnOrdering;
use rusqlite::{
    Connection, ErrorCode, OpenFlags, OptionalExtension, Row, TransactionBehavior, params,
};

pub use kcode_k1_access_profile_types::{
    AuthorizationProfile, ProfileId, ProfileRevision, TxId, UserId,
};

const DATABASE_FILE: &str = "profiles.sqlite3";
const SUBSYSTEM: &str = "k1-profile-subsystem";
const METADATA_SQL: &str = "CREATE TABLE metadata(schema_version INTEGER NOT NULL CHECK(schema_version=1), last_applied_txid BLOB CHECK(last_applied_txid IS NULL OR (typeof(last_applied_txid)='blob' AND length(last_applied_txid)=12)))";
const PROFILES_SQL: &str = "CREATE TABLE profiles(profile_id BLOB PRIMARY KEY NOT NULL CHECK(typeof(profile_id)='blob' AND length(profile_id)=12), owner BLOB NOT NULL CHECK(typeof(owner)='blob' AND length(owner)=12), revision BLOB NOT NULL CHECK(typeof(revision)='blob' AND length(revision)=12), profile BLOB NOT NULL CHECK(typeof(profile)='blob')) WITHOUT ROWID";
const OWNER_INDEX_SQL: &str = "CREATE INDEX profiles_owner ON profiles(owner)";
const CREATE_SCHEMA: &str = "BEGIN IMMEDIATE;
CREATE TABLE metadata(schema_version INTEGER NOT NULL CHECK(schema_version=1), last_applied_txid BLOB CHECK(last_applied_txid IS NULL OR (typeof(last_applied_txid)='blob' AND length(last_applied_txid)=12)));
CREATE TABLE profiles(profile_id BLOB PRIMARY KEY NOT NULL CHECK(typeof(profile_id)='blob' AND length(profile_id)=12), owner BLOB NOT NULL CHECK(typeof(owner)='blob' AND length(owner)=12), revision BLOB NOT NULL CHECK(typeof(revision)='blob' AND length(revision)=12), profile BLOB NOT NULL CHECK(typeof(profile)='blob')) WITHOUT ROWID;
CREATE INDEX profiles_owner ON profiles(owner);
INSERT INTO metadata(schema_version, last_applied_txid) VALUES(1, NULL);
COMMIT;";

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SavedProfile {
    profile_id: ProfileId,
    owner: UserId,
    revision: ProfileRevision,
    profile: AuthorizationProfile,
}

impl SavedProfile {
    pub const fn profile_id(&self) -> ProfileId {
        self.profile_id
    }

    pub const fn owner(&self) -> UserId {
        self.owner
    }

    pub const fn revision(&self) -> ProfileRevision {
        self.revision
    }

    pub fn profile(&self) -> &AuthorizationProfile {
        &self.profile
    }
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ProfileAction {
    Create {
        owner: UserId,
        profile: AuthorizationProfile,
    },
    Replace {
        profile_id: ProfileId,
        actor: UserId,
        profile: AuthorizationProfile,
    },
    Delete {
        profile_id: ProfileId,
        actor: UserId,
    },
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ApplyOutcome {
    Applied(ProfileRevision),
    Unchanged(ProfileRevision),
    Rejected(String),
}

pub struct ProfileStore {
    database: PathBuf,
    ordering: Arc<K1TxnOrdering>,
    apply_connection: Mutex<Connection>,
    available: AtomicBool,
}

impl ProfileStore {
    pub fn open(root: &Path, ordering: Arc<K1TxnOrdering>) -> Result<(Self, Option<TxId>), String> {
        let started = Instant::now();
        let result = Self::open_inner(root, ordering);
        if started.elapsed() > Duration::from_millis(100) {
            let outcome = if result.is_ok() { "ready" } else { "error" };
            eprintln!(
                "level=warn module=kcode-k1-access-profile-store operation=open elapsed_us={} outcome={outcome}",
                started.elapsed().as_micros()
            );
        }
        result
    }

    fn open_inner(
        root: &Path,
        ordering: Arc<K1TxnOrdering>,
    ) -> Result<(Self, Option<TxId>), String> {
        fs::create_dir_all(root)
            .map_err(|error| format!("profile root is unavailable: {error}"))?;
        let database = root.join(DATABASE_FILE);
        let loaded = load_database(&database, &ordering);
        let (connection, cursor) = match loaded {
            Ok(value) => value,
            Err(OpenIssue::Fatal(error)) => return Err(error),
            Err(OpenIssue::Corrupt) => {
                remove_database(root)?;
                match load_database(&database, &ordering) {
                    Ok(value) => value,
                    Err(OpenIssue::Fatal(error)) => return Err(error),
                    Err(OpenIssue::Corrupt) => {
                        return Err("profile database rebuild failed".to_owned());
                    }
                }
            }
        };
        Ok((
            Self {
                database,
                ordering,
                apply_connection: Mutex::new(connection),
                available: AtomicBool::new(true),
            },
            cursor,
        ))
    }

    pub fn apply(
        &self,
        callback_txid: TxId,
        action: ProfileAction,
    ) -> Result<ApplyOutcome, String> {
        self.require_available()?;
        match validate_transaction(&self.ordering, callback_txid) {
            Ok(()) => {}
            Err(OpenIssue::Corrupt) => {
                return self.disable("profile callback contradicts KTO");
            }
            Err(OpenIssue::Fatal(error)) => return self.disable(error),
        }
        let encoded_profile = match &action {
            ProfileAction::Create { profile, .. } | ProfileAction::Replace { profile, .. } => {
                Some(encode_profile(profile)?)
            }
            ProfileAction::Delete { .. } => None,
        };
        let mut connection = match self.apply_connection.lock() {
            Ok(connection) => connection,
            Err(_) => return self.disable("profile apply lane is unavailable"),
        };
        self.require_available()?;
        let transaction = match connection.transaction_with_behavior(TransactionBehavior::Immediate)
        {
            Ok(transaction) => transaction,
            Err(error) => return self.disable(format!("profile persistence failed: {error}")),
        };
        let outcome = match apply_action(&transaction, callback_txid, action, encoded_profile) {
            Ok(outcome) => outcome,
            Err(error) => return self.disable(error),
        };
        if let Err(error) = transaction.commit() {
            return self.disable(format!("profile persistence failed: {error}"));
        }
        Ok(outcome)
    }

    pub fn get_for_user(
        &self,
        user: UserId,
        profile_id: ProfileId,
    ) -> Result<Option<SavedProfile>, String> {
        self.require_available()?;
        match query_profile(&self.database, user, profile_id) {
            Ok(profile) => Ok(profile),
            Err(error) => self.disable(error),
        }
    }

    pub fn list_for_user(&self, user: UserId) -> Result<Vec<SavedProfile>, String> {
        self.require_available()?;
        match query_profiles(&self.database, user) {
            Ok(profiles) => Ok(profiles),
            Err(error) => self.disable(error),
        }
    }

    pub fn clear(&self) -> Result<(), String> {
        self.require_available()?;
        let mut connection = match self.apply_connection.lock() {
            Ok(connection) => connection,
            Err(_) => return self.disable("profile apply lane is unavailable"),
        };
        self.require_available()?;
        let transaction = match connection.transaction_with_behavior(TransactionBehavior::Immediate)
        {
            Ok(transaction) => transaction,
            Err(error) => return self.disable(format!("profile persistence failed: {error}")),
        };
        if let Err(error) = transaction.execute("DELETE FROM profiles", []) {
            return self.disable(format!("profile persistence failed: {error}"));
        }
        match transaction.execute("UPDATE metadata SET last_applied_txid=NULL", []) {
            Ok(1) => {}
            Ok(_) => return self.disable("profile persistence contradiction"),
            Err(error) => return self.disable(format!("profile persistence failed: {error}")),
        }
        if let Err(error) = transaction.commit() {
            return self.disable(format!("profile persistence failed: {error}"));
        }
        Ok(())
    }

    fn require_available(&self) -> Result<(), String> {
        if self.available.load(Ordering::Acquire) {
            Ok(())
        } else {
            Err("profile store is unavailable".to_owned())
        }
    }

    fn disable<T>(&self, error: impl Into<String>) -> Result<T, String> {
        self.available.store(false, Ordering::Release);
        Err(error.into())
    }
}

fn apply_action(
    transaction: &rusqlite::Transaction<'_>,
    callback_txid: TxId,
    action: ProfileAction,
    encoded_profile: Option<Vec<u8>>,
) -> Result<ApplyOutcome, String> {
    let outcome = match action {
        ProfileAction::Create { owner, .. } => {
            let profile_id = ProfileId::new(callback_txid);
            if load_saved(transaction, profile_id)?.is_some() {
                ApplyOutcome::Rejected("profile already exists".to_owned())
            } else {
                let profile = encoded_profile
                    .as_deref()
                    .ok_or("profile encoding is unavailable")?;
                let profile_id_bytes = callback_txid.into_bytes();
                let owner_bytes = owner.as_tx_id().into_bytes();
                let changed = transaction
                    .execute(
                        "INSERT INTO profiles(profile_id, owner, revision, profile) VALUES(?1, ?2, ?3, ?4)",
                        params![profile_id_bytes.as_slice(), owner_bytes.as_slice(), profile_id_bytes.as_slice(), profile],
                    )
                    .map_err(|error| format!("profile persistence failed: {error}"))?;
                if changed != 1 {
                    return Err("profile persistence contradiction".to_owned());
                }
                ApplyOutcome::Applied(ProfileRevision::new(profile_id, callback_txid))
            }
        }
        ProfileAction::Replace {
            profile_id,
            actor,
            profile,
        } => match load_saved(transaction, profile_id)? {
            Some(current) if current.owner() == actor => {
                if current.profile() == &profile {
                    ApplyOutcome::Unchanged(current.revision())
                } else {
                    let profile = encoded_profile
                        .as_deref()
                        .ok_or("profile encoding is unavailable")?;
                    let profile_id_bytes = profile_id.txid().into_bytes();
                    let revision_bytes = callback_txid.into_bytes();
                    let changed = transaction
                        .execute(
                            "UPDATE profiles SET revision=?1, profile=?2 WHERE profile_id=?3",
                            params![
                                revision_bytes.as_slice(),
                                profile,
                                profile_id_bytes.as_slice()
                            ],
                        )
                        .map_err(|error| format!("profile persistence failed: {error}"))?;
                    if changed != 1 {
                        return Err("profile persistence contradiction".to_owned());
                    }
                    ApplyOutcome::Applied(ProfileRevision::new(profile_id, callback_txid))
                }
            }
            _ => ApplyOutcome::Rejected("profile is unavailable".to_owned()),
        },
        ProfileAction::Delete { profile_id, actor } => match load_saved(transaction, profile_id)? {
            Some(current) if current.owner() == actor => {
                let profile_id_bytes = profile_id.txid().into_bytes();
                let changed = transaction
                    .execute(
                        "DELETE FROM profiles WHERE profile_id=?1",
                        params![profile_id_bytes.as_slice()],
                    )
                    .map_err(|error| format!("profile persistence failed: {error}"))?;
                if changed != 1 {
                    return Err("profile persistence contradiction".to_owned());
                }
                ApplyOutcome::Applied(ProfileRevision::new(profile_id, callback_txid))
            }
            _ => ApplyOutcome::Rejected("profile is unavailable".to_owned()),
        },
    };
    let cursor = callback_txid.into_bytes();
    let changed = transaction
        .execute(
            "UPDATE metadata SET last_applied_txid=?1",
            params![cursor.as_slice()],
        )
        .map_err(|error| format!("profile persistence failed: {error}"))?;
    if changed != 1 {
        return Err("profile persistence contradiction".to_owned());
    }
    Ok(outcome)
}

fn load_saved(
    transaction: &rusqlite::Transaction<'_>,
    profile_id: ProfileId,
) -> Result<Option<SavedProfile>, String> {
    let profile_id_bytes = profile_id.txid().into_bytes();
    let raw = transaction
        .query_row(
            "SELECT profile_id, owner, revision, profile FROM profiles WHERE profile_id=?1",
            params![profile_id_bytes.as_slice()],
            raw_profile,
        )
        .optional()
        .map_err(|error| format!("profile persistence failed: {error}"))?;
    raw.map(decode_saved).transpose()
}

fn query_profile(
    database: &Path,
    user: UserId,
    profile_id: ProfileId,
) -> Result<Option<SavedProfile>, String> {
    let connection = open_query(database)?;
    let user_bytes = user.as_tx_id().into_bytes();
    let profile_id_bytes = profile_id.txid().into_bytes();
    let raw = connection
        .query_row(
            "SELECT profile_id, owner, revision, profile FROM profiles WHERE profile_id=?1 AND owner=?2",
            params![profile_id_bytes.as_slice(), user_bytes.as_slice()],
            raw_profile,
        )
        .optional()
        .map_err(|error| format!("profile query failed: {error}"))?;
    raw.map(decode_saved).transpose()
}

fn query_profiles(database: &Path, user: UserId) -> Result<Vec<SavedProfile>, String> {
    let connection = open_query(database)?;
    let user_bytes = user.as_tx_id().into_bytes();
    let mut statement = connection
        .prepare("SELECT profile_id, owner, revision, profile FROM profiles WHERE owner=?1")
        .map_err(|error| format!("profile query failed: {error}"))?;
    let mut rows = statement
        .query(params![user_bytes.as_slice()])
        .map_err(|error| format!("profile query failed: {error}"))?;
    let mut profiles = Vec::new();
    while let Some(row) = rows
        .next()
        .map_err(|error| format!("profile query failed: {error}"))?
    {
        let raw = raw_profile(row).map_err(|error| format!("profile query failed: {error}"))?;
        profiles.push(decode_saved(raw)?);
    }
    Ok(profiles)
}

fn open_query(database: &Path) -> Result<Connection, String> {
    let connection = Connection::open_with_flags(
        database,
        OpenFlags::SQLITE_OPEN_READ_ONLY | OpenFlags::SQLITE_OPEN_NO_MUTEX,
    )
    .map_err(|error| format!("profile query failed: {error}"))?;
    connection
        .busy_timeout(Duration::ZERO)
        .map_err(|error| format!("profile query failed: {error}"))?;
    Ok(connection)
}

struct RawProfile {
    profile_id: Vec<u8>,
    owner: Vec<u8>,
    revision: Vec<u8>,
    profile: Vec<u8>,
}

fn raw_profile(row: &Row<'_>) -> rusqlite::Result<RawProfile> {
    Ok(RawProfile {
        profile_id: row.get(0)?,
        owner: row.get(1)?,
        revision: row.get(2)?,
        profile: row.get(3)?,
    })
}

fn decode_saved(raw: RawProfile) -> Result<SavedProfile, String> {
    let profile_id = ProfileId::new(TxId::from_bytes(bytes_12(raw.profile_id)?));
    let owner = UserId::from_tx_id(TxId::from_bytes(bytes_12(raw.owner)?));
    let revision_txid = TxId::from_bytes(bytes_12(raw.revision)?);
    let profile = decode_profile(&raw.profile).map_err(|_| "profile persistence contradiction")?;
    Ok(SavedProfile {
        profile_id,
        owner,
        revision: ProfileRevision::new(profile_id, revision_txid),
        profile,
    })
}

fn bytes_12(bytes: Vec<u8>) -> Result<[u8; 12], String> {
    bytes
        .try_into()
        .map_err(|_| "profile persistence contradiction".to_owned())
}

enum OpenIssue {
    Corrupt,
    Fatal(String),
}

fn load_database(
    database: &Path,
    ordering: &K1TxnOrdering,
) -> Result<(Connection, Option<TxId>), OpenIssue> {
    let connection = connect(database)?;
    let object_count: i64 = connection
        .query_row(
            "SELECT count(*) FROM sqlite_schema WHERE name NOT LIKE 'sqlite_%'",
            [],
            |row| row.get(0),
        )
        .map_err(sql_issue)?;
    if object_count == 0 {
        connection.execute_batch(CREATE_SCHEMA).map_err(sql_issue)?;
    }
    validate_schema(&connection)?;
    let cursor = validate_rows(&connection, ordering)?;
    Ok((connection, cursor))
}

fn connect(database: &Path) -> Result<Connection, OpenIssue> {
    let connection = Connection::open(database).map_err(sql_issue)?;
    connection.busy_timeout(Duration::ZERO).map_err(sql_issue)?;
    let journal: String = connection
        .query_row("PRAGMA journal_mode=WAL", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if !journal.eq_ignore_ascii_case("wal") {
        return Err(OpenIssue::Fatal("SQLite WAL is unavailable".to_owned()));
    }
    connection
        .execute_batch("PRAGMA synchronous=FULL;")
        .map_err(sql_issue)?;
    let synchronous: i64 = connection
        .query_row("PRAGMA synchronous", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if synchronous != 2 {
        return Err(OpenIssue::Fatal(
            "SQLite FULL synchronization is unavailable".to_owned(),
        ));
    }
    Ok(connection)
}

fn validate_schema(connection: &Connection) -> Result<(), OpenIssue> {
    let integrity: String = connection
        .query_row("PRAGMA integrity_check", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if integrity != "ok" {
        return Err(OpenIssue::Corrupt);
    }
    let mut statement = connection
        .prepare("SELECT name, sql FROM sqlite_schema WHERE name NOT LIKE 'sqlite_%'")
        .map_err(sql_issue)?;
    let mut rows = statement.query([]).map_err(sql_issue)?;
    let mut metadata = false;
    let mut profiles = false;
    let mut owner_index = false;
    let mut count = 0;
    while let Some(row) = rows.next().map_err(sql_issue)? {
        let name: String = row.get(0).map_err(|_| OpenIssue::Corrupt)?;
        let sql: String = row.get(1).map_err(|_| OpenIssue::Corrupt)?;
        count += 1;
        match name.as_str() {
            "metadata" if sql == METADATA_SQL => metadata = true,
            "profiles" if sql == PROFILES_SQL => profiles = true,
            "profiles_owner" if sql == OWNER_INDEX_SQL => owner_index = true,
            _ => return Err(OpenIssue::Corrupt),
        }
    }
    if count != 3 || !metadata || !profiles || !owner_index {
        return Err(OpenIssue::Corrupt);
    }
    Ok(())
}

fn validate_rows(
    connection: &Connection,
    ordering: &K1TxnOrdering,
) -> Result<Option<TxId>, OpenIssue> {
    let metadata_count: i64 = connection
        .query_row("SELECT count(*) FROM metadata", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if metadata_count != 1 {
        return Err(OpenIssue::Corrupt);
    }
    let (version, cursor_bytes): (i64, Option<Vec<u8>>) = connection
        .query_row(
            "SELECT schema_version, last_applied_txid FROM metadata",
            [],
            |row| Ok((row.get(0)?, row.get(1)?)),
        )
        .map_err(|_| OpenIssue::Corrupt)?;
    if version != 1 {
        return Err(OpenIssue::Corrupt);
    }
    let cursor = cursor_bytes
        .map(|bytes| bytes_12(bytes).map(TxId::from_bytes))
        .transpose()
        .map_err(|_| OpenIssue::Corrupt)?;
    if let Some(id) = cursor {
        validate_transaction(ordering, id)?;
    }
    let mut statement = connection
        .prepare("SELECT profile_id, owner, revision, profile FROM profiles")
        .map_err(sql_issue)?;
    let mut rows = statement.query([]).map_err(sql_issue)?;
    let mut any_profile = false;
    while let Some(row) = rows.next().map_err(sql_issue)? {
        any_profile = true;
        let raw = raw_profile(row).map_err(|_| OpenIssue::Corrupt)?;
        let saved = decode_saved(raw).map_err(|_| OpenIssue::Corrupt)?;
        validate_transaction(ordering, saved.profile_id().txid())?;
        validate_transaction(ordering, saved.revision().txid())?;
    }
    if any_profile && cursor.is_none() {
        return Err(OpenIssue::Corrupt);
    }
    Ok(cursor)
}

fn validate_transaction(ordering: &K1TxnOrdering, id: TxId) -> Result<(), OpenIssue> {
    let bytes = ordering
        .get_txn(id)
        .map_err(|error| OpenIssue::Fatal(format!("KTO query failed: {error}")))?
        .ok_or(OpenIssue::Corrupt)?;
    if !id.verify(&bytes) {
        return Err(OpenIssue::Corrupt);
    }
    let transaction = Transaction::parse(&bytes).map_err(|_| OpenIssue::Corrupt)?;
    if transaction.subsystem().as_str() != SUBSYSTEM {
        return Err(OpenIssue::Corrupt);
    }
    Ok(())
}

fn sql_issue(error: rusqlite::Error) -> OpenIssue {
    match error.sqlite_error_code() {
        Some(ErrorCode::DatabaseCorrupt | ErrorCode::NotADatabase) => OpenIssue::Corrupt,
        _ => OpenIssue::Fatal(format!("SQLite is unavailable: {error}")),
    }
}

fn remove_database(root: &Path) -> Result<(), String> {
    for file in [
        "profiles.sqlite3-wal",
        "profiles.sqlite3-shm",
        DATABASE_FILE,
    ] {
        match fs::remove_file(root.join(file)) {
            Ok(()) => {}
            Err(error) if error.kind() == ErrorKind::NotFound => {}
            Err(error) => return Err(format!("profile database cannot be rebuilt: {error}")),
        }
    }
    Ok(())
}