/* Copyright (c) 2016-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file hs_cache.h
 * \brief Header file for hs_cache.c
 **/

#ifndef TOR_HS_CACHE_H
#define TOR_HS_CACHE_H

#include <stdint.h>

#include "lib/crypt_ops/crypto_ed25519.h"
#include "or/hs_common.h"
#include "or/hs_descriptor.h"
#include "or/rendcommon.h"
#include "or/torcert.h"

/* This is the maximum time an introduction point state object can stay in the
 * client cache in seconds (2 mins or 120 seconds). */
#define HS_CACHE_CLIENT_INTRO_STATE_MAX_AGE (2 * 60)

/* Introduction point state. */
typedef struct hs_cache_intro_state_t {
  /* When this entry was created and put in the cache. */
  time_t created_ts;

  /* Did it suffered a generic error? */
  unsigned int error : 1;

  /* Did it timed out? */
  unsigned int timed_out : 1;

  /* How many times we tried to reached it and it was unreachable. */
  uint32_t unreachable_count;
} hs_cache_intro_state_t;

typedef struct hs_cache_client_intro_state_t {
  /* Contains hs_cache_intro_state_t object indexed by introduction point
   * authentication key. */
  digest256map_t *intro_points;
} hs_cache_client_intro_state_t;

/* Descriptor representation on the directory side which is a subset of
 * information that the HSDir can decode and serve it. */
typedef struct hs_cache_dir_descriptor_t {
  /* This object is indexed using the blinded pubkey located in the plaintext
   * data which is populated only once the descriptor has been successfully
   * decoded and validated. This simply points to that pubkey. */
  const uint8_t *key;

  /* When does this entry has been created. Used to expire entries. */
  time_t created_ts;

  /* Descriptor plaintext information. Obviously, we can't decrypt the
   * encrypted part of the descriptor. */
  hs_desc_plaintext_data_t *plaintext_data;

  /* Encoded descriptor which is basically in text form. It's a NUL terminated
   * string thus safe to strlen(). */
  char *encoded_desc;
} hs_cache_dir_descriptor_t;

/* Public API */

void hs_cache_init(void);
void hs_cache_free_all(void);
void hs_cache_clean_as_dir(time_t now);
size_t hs_cache_handle_oom(time_t now, size_t min_remove_bytes);

unsigned int hs_cache_get_max_descriptor_size(void);

/* Store and Lookup function. They are version agnostic that is depending on
 * the requested version of the descriptor, it will be re-routed to the
 * right function. */
int hs_cache_store_as_dir(const char *desc);
int hs_cache_lookup_as_dir(uint32_t version, const char *query,
                           const char **desc_out);

const hs_descriptor_t *
hs_cache_lookup_as_client(const ed25519_public_key_t *key);
const char *
hs_cache_lookup_encoded_as_client(const ed25519_public_key_t *key);
int hs_cache_store_as_client(const char *desc_str,
                             const ed25519_public_key_t *identity_pk);
void hs_cache_clean_as_client(time_t now);
void hs_cache_purge_as_client(void);

/* Client failure cache. */
void hs_cache_client_intro_state_note(const ed25519_public_key_t *service_pk,
                                      const ed25519_public_key_t *auth_key,
                                      rend_intro_point_failure_t failure);
const hs_cache_intro_state_t *hs_cache_client_intro_state_find(
                                       const ed25519_public_key_t *service_pk,
                                       const ed25519_public_key_t *auth_key);
void hs_cache_client_intro_state_clean(time_t now);
void hs_cache_client_intro_state_purge(void);

#ifdef HS_CACHE_PRIVATE

/** Represents a locally cached HS descriptor on a hidden service client. */
typedef struct hs_cache_client_descriptor_t {
  /* This object is indexed using the service identity public key */
  ed25519_public_key_t key;

  /* When will this entry expire? We expire cached client descriptors in the
   * start of the next time period, since that's when clients need to start
   * using the next blinded key of the service. */
  time_t expiration_ts;

  /* The cached descriptor, this object is the owner. It can't be NULL. A
   * cache object without a valid descriptor is not possible. */
  hs_descriptor_t *desc;

  /* Encoded descriptor in string form. Can't be NULL. */
  char *encoded_desc;
} hs_cache_client_descriptor_t;

STATIC size_t cache_clean_v3_as_dir(time_t now, time_t global_cutoff);

STATIC hs_cache_client_descriptor_t *
lookup_v3_desc_as_client(const uint8_t *key);

#endif /* defined(HS_CACHE_PRIVATE) */

#endif /* !defined(TOR_HS_CACHE_H) */

