/* Copyright (c) 2016-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file hs_service.h
 * \brief Header file containing service data for the HS subsytem.
 **/

#ifndef TOR_HS_SERVICE_H
#define TOR_HS_SERVICE_H

#include "crypto_curve25519.h"
#include "crypto_ed25519.h"
#include "hs_descriptor.h"
#include "hs_intropoint.h"
#include "replaycache.h"

/* Trunnel */
#include "hs/cell_establish_intro.h"

/* When loading and configuring a service, this is the default version it will
 * be configured for as it is possible that no HiddenServiceVersion is
 * present. */
#define HS_SERVICE_DEFAULT_VERSION HS_VERSION_TWO

/* Service side introduction point. */
typedef struct hs_service_intro_point_t {
  /* Top level intropoint "shared" data between client/service. */
  hs_intropoint_t base;

  /* Authentication keypair used to create the authentication certificate
   * which is published in the descriptor. */
  ed25519_keypair_t auth_key_kp;

  /* Encryption private key. */
  curve25519_secret_key_t enc_key_sk;

  /* Amount of INTRODUCE2 cell accepted from this intro point. */
  uint64_t introduce2_count;

  /* Maximum number of INTRODUCE2 cell this intro point should accept. */
  uint64_t introduce2_max;

  /* The time at which this intro point should expire and stop being used. */
  time_t time_to_expire;

  /* The amount of circuit creation we've made to this intro point. This is
   * incremented every time we do a circuit relaunch on this intro point which
   * is triggered when the circuit dies but the node is still in the
   * consensus. After MAX_INTRO_POINT_CIRCUIT_RETRIES, we give up on it. */
  uint32_t circuit_retries;

  /* Set if this intro point has an established circuit. */
  unsigned int circuit_established : 1;

  /* Replay cache recording the encrypted part of an INTRODUCE2 cell that the
   * circuit associated with this intro point has received. This is used to
   * prevent replay attacks. */
  replaycache_t *replay_cache;
} hs_service_intro_point_t;

/* Object handling introduction points of a service. */
typedef struct hs_service_intropoints_t {
  /* The time at which we've started our retry period to build circuits. We
   * don't want to stress circuit creation so we can only retry for a certain
   * time and then after we stop and wait. */
  time_t retry_period_started;

  /* Number of circuit we've launched during a single retry period. */
  unsigned int num_circuits_launched;

  /* Contains the current hs_service_intro_point_t objects indexed by
   * authentication public key. */
  digest256map_t *map;
} hs_service_intropoints_t;

/* Representation of a service descriptor. */
typedef struct hs_service_descriptor_t {
  /* Decoded descriptor. This object is used for encoding when the service
   * publishes the descriptor. */
  hs_descriptor_t *desc;

  /* Descriptor signing keypair. */
  ed25519_keypair_t signing_kp;

  /* Blinded keypair derived from the master identity public key. */
  ed25519_keypair_t blinded_kp;

  /* When is the next time when we should upload the descriptor. */
  time_t next_upload_time;

  /* Introduction points assign to this descriptor which contains
   * hs_service_intropoints_t object indexed by authentication key (the RSA
   * key if the node is legacy). */
  hs_service_intropoints_t intro_points;
} hs_service_descriptor_t;

/* Service key material. */
typedef struct hs_service_keys_t {
  /* Master identify public key. */
  ed25519_public_key_t identity_pk;
  /* Master identity private key. */
  ed25519_secret_key_t identity_sk;
  /* True iff the key is kept offline which means the identity_sk MUST not be
   * used in that case. */
  unsigned int is_identify_key_offline : 1;
} hs_service_keys_t;

/* Service configuration. The following are set from the torrc options either
 * set by the configuration file or by the control port. Nothing else should
 * change those values. */
typedef struct hs_service_config_t {
  /* List of rend_service_port_config_t */
  smartlist_t *ports;

  /* Path on the filesystem where the service persistent data is stored. NULL
   * if the service is ephemeral. Specified by HiddenServiceDir option. */
  char *directory_path;

  /* The time period after which a descriptor is uploaded to the directories
   * in seconds. Specified by RendPostPeriod option. */
  uint32_t descriptor_post_period;

  /* The maximum number of simultaneous streams per rendezvous circuit that
   * are allowed to be created. No limit if 0. Specified by
   * HiddenServiceMaxStreams option. */
  uint64_t max_streams_per_rdv_circuit;

  /* If true, we close circuits that exceed the max_streams_per_rdv_circuit
   * limit. Specified by HiddenServiceMaxStreamsCloseCircuit option. */
  unsigned int max_streams_close_circuit : 1;

  /* How many introduction points this service has. Specified by
   * HiddenServiceNumIntroductionPoints option. */
  unsigned int num_intro_points;

  /* True iff we allow request made on unknown ports. Specified by
   * HiddenServiceAllowUnknownPorts option. */
  unsigned int allow_unknown_ports : 1;

  /* If true, this service is a Single Onion Service. Specified by
   * HiddenServiceSingleHopMode and HiddenServiceNonAnonymousMode options. */
  unsigned int is_single_onion : 1;

  /* If true, allow group read permissions on the directory_path. Specified by
   * HiddenServiceDirGroupReadable option. */
  unsigned int dir_group_readable : 1;

  /* Is this service ephemeral? */
  unsigned int is_ephemeral : 1;
} hs_service_config_t;

/* Service state. */
typedef struct hs_service_state_t {
  /* The time at which we've started our retry period to build circuits. We
   * don't want to stress circuit creation so we can only retry for a certain
   * time and then after we stop and wait. */
  time_t intro_circ_retry_started_time;

  /* Number of circuit we've launched during a single retry period. This
   * should never go over MAX_INTRO_CIRCS_PER_PERIOD. */
  unsigned int num_intro_circ_launched;

  /* Indicate that the service has entered the overlap period. We use this
   * flag to check for descriptor rotation. */
  unsigned int in_overlap_period : 1;
} hs_service_state_t;

/* Representation of a service running on this tor instance. */
typedef struct hs_service_t {
  /* Protocol version of the service. Specified by HiddenServiceVersion. */
  uint32_t version;

  /* Service state which contains various flags and counters. */
  hs_service_state_t state;

  /* Key material of the service. */
  hs_service_keys_t keys;

  /* Configuration of the service. */
  hs_service_config_t config;

  /* Current descriptor. */
  hs_service_descriptor_t *desc_current;
  /* Next descriptor that we need for the overlap period for which we have to
   * keep two sets of opened introduction point circuits. */
  hs_service_descriptor_t *desc_next;

  /* XXX: Credential (client auth.) #20700. */

} hs_service_t;

/* API */

/* These functions are only used by unit tests and we need to expose them else
 * hs_service.o ends up with no symbols in libor.a which makes clang throw a
 * warning at compile time. See #21825. */

trn_cell_establish_intro_t *
generate_establish_intro_cell(const uint8_t *circuit_key_material,
                              size_t circuit_key_material_len);
ssize_t
get_establish_intro_payload(uint8_t *buf, size_t buf_len,
                            const trn_cell_establish_intro_t *cell);

#endif /* TOR_HS_SERVICE_H */