pdk_contracts_lib/api/

validator.rs

// Copyright (c) 2026, Salesforce, Inc.,
// All rights reserved.
// For full license text, see the LICENSE.txt file

use super::authentication::authenticate;
use super::authorization::authorize;
use super::credentials::{ClientId, ClientSecret};
use super::error::UpdateError;
use super::error::{AuthenticationError, AuthorizationError};
use crate::api::ClientData;
use crate::implementation::constants::{
    ACCEPT_HASH_ALGORITHM_VALUE, CONTRACTS_CACHE_EXPIRATION, CONTRACTS_FETCHING_INTERVAL,
    LOCK_TIMEOUT_DURATION, PRIMARY_BACKUP_INTERVAL, PRIMARY_INACTIVE_TIMEOUT,
};
use crate::implementation::model::contracts_storage::{ContractsLocalStorage, ContractsStorage};
use crate::implementation::model::distributed_storage::ContractsCache;
use crate::implementation::model::session_storage::{SessionSharedDataStorage, SessionStorage};
use crate::implementation::platform::client::HttpPlatformClient;
use crate::implementation::platform::responses::{
    contract_from_event, ContractsResponse, LoginResponse,
};
use crate::implementation::platform::shared::{AccessToken, ContractsRequestParams};
use data_storage_lib::DataStorageBuilder;
use lock_lib::{Lock, LockBuilder, TryLock};
use pdk_core::classy::extract::context::ConfigureContext;
use pdk_core::classy::extract::{Extract, FromContext};
use pdk_core::classy::hl::HttpClientError;
use pdk_core::classy::proxy_wasm::types::Status;
use pdk_core::classy::{Clock, SharedData};
use pdk_core::logger;
use pdk_core::logger::debug;
use pdk_core::policy_context::api::Metadata;
use std::rc::Rc;
use std::time::Duration;
use thiserror::Error;

/// The object that will collect the contracts and provide the functionality to validate incoming
/// requests.
pub struct ContractValidator {
    api_id: String,
    client: HttpPlatformClient,
    session_lock: TryLock,
    api_lock: TryLock,
    session_storage: SessionSharedDataStorage,
    contract_storage: Rc<ContractsLocalStorage>,
    contracts_cache: ContractsCache,
    clock: Rc<dyn Clock>,
}

#[derive(Error, Debug)]
enum InternalUpdateError {
    #[error("Http client error: {0}")]
    HttpClientError(#[from] HttpClientError),
    #[error("Parsing error: {0}")]
    Serde(#[from] serde_json::error::Error),
    #[error("Lost the lock while executing async function.")]
    LostLock,
    #[error("Upstream returned unexpected status code {0}")]
    UnexpectedResponse(u32),
}

enum PollContractsResponse {
    Continue,
    Renegotiate,
    Finish,
}

pub(crate) enum PollerType {
    Primary,
    Secondary,
}

pub(crate) enum PollerError {
    LostLock,
    DataStorageError,
}

impl ContractValidator {
    fn new(
        client: HttpPlatformClient,
        api_id: String,
        clock: Rc<dyn Clock>,
        shared_data: Rc<dyn SharedData>,
        lock_builder: LockBuilder,
        data_storage_builder: DataStorageBuilder,
    ) -> Self {
        // The session storage and the session lock only use two entries in total despite the amount
        // of Apis/policies deployed. We can safely not remove them without fear of a leak.
        let session_storage =
            SessionSharedDataStorage::new(Rc::clone(&clock), Rc::clone(&shared_data));

        let session_lock = lock_builder
            .new(session_storage.session_lock_key())
            .expiration(LOCK_TIMEOUT_DURATION)
            .shared()
            .build();

        let contract_storage = Rc::new(ContractsLocalStorage::new(
            &api_id,
            Rc::clone(&clock),
            shared_data,
        ));
        let api_lock = lock_builder
            .new(contract_storage.api_lock_key())
            .expiration(LOCK_TIMEOUT_DURATION)
            .shared()
            .build();

        let contracts_cache = ContractsCache::new(
            Rc::clone(&clock),
            data_storage_builder
                .shared()
                .remote(format!("{api_id}-CONTRACTS"), CONTRACTS_CACHE_EXPIRATION),
            Rc::clone(&contract_storage),
        );

        Self {
            api_id,
            client,
            session_lock,
            api_lock,
            session_storage,
            contract_storage,
            clock,
            contracts_cache,
        }
    }

    /// Initial updating interval for calling [ContractValidator::update_contracts()].
    pub const INITIALIZATION_PERIOD: Duration = Duration::from_millis(100);

    /// Remaining updating interval for calling [ContractValidator::update_contracts()].
    pub const UPDATE_PERIOD: Duration = CONTRACTS_FETCHING_INTERVAL;

    /// Validates if `client_id` credential can be authorized in the current API contract.
    /// If the validation is succesful, this method returns the [ClientData] of `client_id`.
    /// Otherwise an [AuthorizationError] is returned.
    pub fn authorize(&self, client_id: &ClientId) -> Result<ClientData, AuthorizationError> {
        authorize(self.contract_storage.as_ref(), client_id)
    }

    /// Validates if `client_id` and `client_secret` credentials can be authenticated
    /// in the current API contract.
    /// If the validation is succesful, this method returns the [ClientData] of `client_id`.
    /// Otherwise an [AuthenticationError] is returned.
    pub fn authenticate(
        &self,
        client_id: &ClientId,
        client_secret: &ClientSecret,
    ) -> Result<ClientData, AuthenticationError> {
        authenticate(self.contract_storage.as_ref(), client_id, client_secret)
    }

    /// Returns `true` if contracts have been pulled and are available locally.
    /// This method can be used to determine if the [`ContractValidator`] is ready
    /// for authorization and authentication operations.
    pub fn is_ready(&self) -> bool {
        self.contract_storage.last_update().is_some()
    }

    /// Updates local contracts database.
    /// This method is intended to be called periodically in order to keep
    /// the local contracts database up to date.
    /// During initialization time, this method should be invoked in a period of
    /// [ContractValidator::INITIALIZATION_PERIOD].
    /// After initialization, this method should be invoked in a period of
    /// [ContractValidator::UPDATE_PERIOD].
    pub async fn update_contracts(&self) -> Result<(), UpdateError> {
        if !self.should_update() {
            debug!("Contracts update skipped since update period hasn't elapsed.");
            return Ok(());
        }

        debug!("Fetching contracts for API {}", self.api_id);
        let Some(api_lock) = self.api_lock.try_lock() else {
            debug!(
                "Other worker has the lock for API {}. Skipping update.",
                self.api_id
            );
            return Ok(());
        };

        if self.first_cycle() {
            let _ = self.cache_contracts_poll(&api_lock).await;
            if !api_lock.refresh_lock() {
                return Ok(());
            }
        }

        // Re-check if the update period has elapsed after backup restore
        if !self.should_update() {
            debug!("Contracts update skipped since update period hasn't elapsed.");
            return Ok(());
        }

        let result = self.platform_contracts_poll(&api_lock).await;

        if self.contract_storage.last_update().is_none() {
            debug!("No successfully poll registered will not try to backup contracts");
            return result.map(|_| ());
        }

        match self.poller_type(&api_lock).await {
            Ok(PollerType::Primary) => {
                self.backup_contracts(&api_lock, result.as_ref().map(|r| *r).unwrap_or_default())
                    .await;
            }
            Ok(PollerType::Secondary) => {
                debug!("No update backup since we are a secondary node.");
            }
            Err(PollerError::LostLock) => {
                debug!("Lost the api_lock while trying to become primary, skipping update.");
            }
            Err(PollerError::DataStorageError) => {
                debug!("Unexpected error communicating with the data storage.");
            }
        };

        result.map(|_| ())
    }

    async fn platform_contracts_poll(&self, api_lock: &'_ Lock<'_>) -> Result<bool, UpdateError> {
        let mut updates = false;
        debug!(
            "Fetching contracts for API {} from contracts service",
            self.api_id
        );

        let Some(token) = self.session_token().await else {
            return Ok(updates);
        };

        if !api_lock.refresh_lock() {
            debug!("Lost the api lock while fetching session token.");
            return Ok(updates);
        }

        let mut token_data = token;
        loop {
            match self.poll_contracts(&token_data, api_lock).await {
                Ok(PollContractsResponse::Continue) => {
                    debug!("Contract polling request successful. Chaining next request");
                    updates = true;
                }
                Ok(PollContractsResponse::Renegotiate) => {
                    let Some(token) = self.renegotiate_token(token_data).await else {
                        // Could not renegotiate the token
                        return Ok(updates);
                    };
                    token_data = token;
                    if !api_lock.refresh_lock() {
                        debug!("Lost the api lock while refreshing the session lock.");
                        return Ok(updates);
                    }
                }
                Ok(PollContractsResponse::Finish) => {
                    return Ok(updates);
                }
                Err(error) => {
                    debug!("Error while polling contracts: {error}");
                    return Ok(updates);
                }
            }
        }
    }

    async fn cache_contracts_poll(&self, api_lock: &'_ Lock<'_>) -> Result<(), UpdateError> {
        debug!("Fetching contracts for API {} from cache.", self.api_id);

        let result = self.contracts_cache.get_state().await;

        if !api_lock.refresh_lock() {
            debug!("Lost the api lock while recovering state from remote storage.");
            return Ok(());
        }

        result
            .into_iter()
            .for_each(|state| self.contract_storage.set_state(state));

        Ok(())
    }

    async fn poller_type(&self, api_lock: &'_ Lock<'_>) -> Result<PollerType, PollerError> {
        let Some(primary) = self.contract_storage.is_primary() else {
            debug!("No information regarding primary node.");
            return self.contracts_cache.try_primary(api_lock).await;
        };

        let primary_expired = self
            .contract_storage
            .last_primary_update()
            .map(|last| last + PRIMARY_INACTIVE_TIMEOUT < self.clock.get_current_time())
            .unwrap_or(true);

        if primary_expired && !primary {
            debug!("Secondary node trying to become primary due to timeout.");
            return self.contracts_cache.try_primary(api_lock).await;
        } else if primary_expired {
            debug!("We lost the primary status. We'll become secondary for at least one polling cycle.");
            self.contract_storage.set_primary(false);
            return Ok(PollerType::Secondary);
        }

        match primary {
            true => Ok(PollerType::Primary),
            false => Ok(PollerType::Secondary),
        }
    }

    fn first_cycle(&self) -> bool {
        self.contract_storage.last_update().is_none()
    }

    fn should_update(&self) -> bool {
        self.contract_storage
            .last_update()
            .map(|last| last + CONTRACTS_FETCHING_INTERVAL < self.clock.get_current_time())
            .unwrap_or(true)
    }

    async fn backup_contracts(&self, api_lock: &'_ Lock<'_>, has_updates: bool) {
        if !self.should_update_backup(has_updates) {
            return;
        }

        let time = self.clock.get_current_time();
        let mut update = self.contract_storage.get_state();
        update.update_primary(time);
        if self.contracts_cache.save_state(update).await {
            self.contract_storage.set_primary_update(time);
        }

        if !api_lock.refresh_lock() {
            debug!("Lost the api lock while backing data to cache.");
        }
    }

    fn should_update_backup(&self, has_updates: bool) -> bool {
        let Some(last_update) = self.contract_storage.last_update() else {
            debug!("Skipping cache backup since no data to backup.");
            return false;
        };

        if has_updates {
            debug!("Will backup contracts since new updates are available.");
            return true;
        }

        let Some(last_primary_update) = self.contract_storage.last_primary_update() else {
            debug!("No local records of a primary node.");
            return true;
        };

        if last_update < last_primary_update {
            debug!("Skipping cache backup since no updates since last save.");
            return false; // No data to back up. This can happen when connection to the platform fails.
        }

        let result = last_primary_update + PRIMARY_BACKUP_INTERVAL < self.clock.get_current_time();
        if !result {
            debug!("Skipping cache backup since the elapsed time is less than the refresh rate.");
        }
        result
    }

    async fn session_token(&self) -> Option<AccessToken> {
        match self.session_storage.get_token() {
            Some(token) => Some(token),
            None => {
                let Some(session_lock) = self.session_lock.try_lock() else {
                    debug!("Other worker has the session lock. Skipping update.");
                    return None;
                };

                // Re check if the token was already set before obtaining the lock.
                // Since the lock is "not blocking" the changes are quite slim, but not null.
                if let Some(token) = self.session_storage.get_token() {
                    return Some(token);
                }

                self.fetch_session_token(&session_lock).await
            }
        }
    }

    async fn renegotiate_token(&self, old_token: AccessToken) -> Option<AccessToken> {
        // Validate that the token was not renegotiated by someone else.
        if let Some(token) = self.session_storage.get_token() {
            if token != old_token {
                return Some(token);
            }
        };

        // Acquire the lock
        let Some(session_lock) = self.session_lock.try_lock() else {
            debug!("Other worker has the session lock. Aborting token renegotiation");
            return None;
        };

        // Validate Again that the token was not renegotiated by someone else.
        // Since the lock is "not blocking" the changes are quite slim, but not null.
        if let Some(token) = self.session_storage.get_token() {
            if token != old_token {
                return Some(token);
            }
        };

        self.fetch_session_token(&session_lock).await
    }

    async fn fetch_session_token(&self, session_lock: &'_ Lock<'_>) -> Option<AccessToken> {
        match self.perform_login_request().await {
            Ok(login) => {
                if !session_lock.refresh_lock() {
                    debug!("Lost the session lock. Aborting update.");
                    return None;
                }
                let token = login.get_token();
                let token_data = AccessToken::new(token.to_string(), login.get_type().to_string());
                debug!("Obtained the session token.");
                self.session_storage.save_token(token_data.clone());
                Some(token_data)
            }
            Err(e) => {
                logger::warn!(
                    "Unexpected error while performing login request {e}. Skipping update."
                );
                None
            }
        }
    }

    async fn perform_login_request(&self) -> Result<LoginResponse, InternalUpdateError> {
        debug!("Getting platform token...");
        match self.client.login().await? {
            r if r.status_code() == 200 => Ok(serde_json::from_slice::<LoginResponse>(r.body())?),
            r => {
                debug!(
                    "Fetching contracts failed with status code: {} and body:\n {}",
                    r.status_code(),
                    String::from_utf8_lossy(r.body())
                );
                Err(InternalUpdateError::UnexpectedResponse(r.status_code()))
            }
        }
    }

    async fn poll_contracts(
        &self,
        access_token: &AccessToken,
        api_lock: &'_ Lock<'_>,
    ) -> Result<PollContractsResponse, InternalUpdateError> {
        let token = access_token.get_access_token();
        let response = self
            .client
            .contracts(
                token,
                self.api_id.as_str(),
                ACCEPT_HASH_ALGORITHM_VALUE,
                self.next_url(),
            )
            .await?;

        if !api_lock.refresh_lock() {
            return Err(InternalUpdateError::LostLock);
        }

        match response.status_code() {
            200 => {
                let contracts: ContractsResponse = serde_json::from_slice(response.body())
                    .map_err(|_| HttpClientError::Status(Status::InternalFailure))?;

                if self.no_updates(&contracts) {
                    self.finish_polling();
                    Ok(PollContractsResponse::Finish)
                } else {
                    self.log_invalid_contracts(&contracts);
                    self.update_data(&contracts);
                    self.update_links(&contracts);
                    Ok(PollContractsResponse::Continue)
                }
            }
            401 => Ok(PollContractsResponse::Renegotiate),
            n => {
                debug!(
                    "Fetching contracts failed with status code: {} and body:\n {}",
                    n,
                    String::from_utf8_lossy(response.body())
                );
                Err(InternalUpdateError::UnexpectedResponse(n))
            }
        }
    }

    fn log_invalid_contracts(&self, response: &ContractsResponse) {
        for invalid_contract_error_msg in response.verify_contracts().err().unwrap_or_default() {
            logger::warn!("{invalid_contract_error_msg}")
        }
    }

    fn no_updates(&self, response: &ContractsResponse) -> bool {
        let links = response.get_links();
        links.self_link() == links.next_link()
    }

    fn finish_polling(&self) {
        self.contract_storage.update_last();
        debug!(
            "No more contracts updates for API {}, polling in next tick.",
            self.api_id
        );
    }

    fn update_data(&self, response: &ContractsResponse) {
        let data = response.get_data();
        for contract_event in data {
            match contract_event.removed.unwrap_or(false) {
                true => self
                    .contract_storage
                    .remove_contract(&contract_event.client_id),
                false => self
                    .contract_storage
                    .save_contract(contract_from_event(contract_event)),
            }
        }
        self.contract_storage.update_last();
        debug!(
            "{} contract events processed for API {}",
            data.len(),
            self.api_id
        );
    }

    fn update_links(&self, response: &ContractsResponse) {
        let links = response.get_links();
        let params = ContractsRequestParams::new(
            Some(links.next_link().to_string()),
            ACCEPT_HASH_ALGORITHM_VALUE.to_string(),
        );
        self.contract_storage.save_contracts_request_params(params);
    }

    fn next_url(&self) -> Option<String> {
        self.contract_storage
            .get_contracts_request_params()
            .and_then(|x| x.next_url)
    }
}

#[derive(thiserror::Error, Debug)]
pub enum ExtractionError {
    #[error("Api metadata is unavailable.")]
    ApiMetadata,

    #[error("Environment Context is unavailable.")]
    EnvironmentContext,

    #[error("Anypoint Context is unavailable.")]
    AnypointContext,
}

impl FromContext<ConfigureContext> for ContractValidator {
    type Error = ExtractionError;

    fn from_context(context: &ConfigureContext) -> Result<Self, Self::Error> {
        let metadata: Metadata = context.extract_always();
        let api_id = metadata
            .api_metadata
            .id
            .ok_or(ExtractionError::ApiMetadata)?;
        let client = context.extract()?;
        let clock = context.extract_always();
        let shared_data = context.extract_always();
        let lock_builder = context.extract_always();
        let storage_builder: DataStorageBuilder = context
            .extract()
            .map_err(|_| ExtractionError::EnvironmentContext)?;

        Ok(Self::new(
            client,
            api_id,
            clock,
            shared_data,
            lock_builder,
            storage_builder,
        ))
    }
}