/*
 * This contains the definition of the INTRODUCE1 and INTRODUCE_ACK cell for
 * onion service version 3 and onward. The following format is specified in
 * proposal 224 section 3.2.
 */

/* From cell_common.trunnel. */
extern struct trn_extension;
/* From ed25519_cert.trunnel. */
extern struct link_specifier;

const TRUNNEL_SHA1_LEN = 20;
const TRUNNEL_REND_COOKIE_LEN = 20;

/* Introduce ACK status code. */
const TRUNNEL_HS_INTRO_ACK_STATUS_SUCCESS    = 0x0000;
const TRUNNEL_HS_INTRO_ACK_STATUS_UNKNOWN_ID = 0x0001;
const TRUNNEL_HS_INTRO_ACK_STATUS_BAD_FORMAT = 0x0002;

/* Authentication key type. */
const TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY0 = 0x00;
const TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY1 = 0x01;
const TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_ED25519 = 0x02;

/* Onion key type. */
const TRUNNEL_HS_INTRO_ONION_KEY_TYPE_NTOR = 0x01;

/* INTRODUCE1 payload. See details in section 3.2.1. */
struct trn_cell_introduce1 {
  /* Always zeroed. MUST be checked explicitly by the caller. */
  u8 legacy_key_id[TRUNNEL_SHA1_LEN];

  /* Authentication key material. */
  u8 auth_key_type IN [TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY0,
                       TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY1,
                       TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_ED25519];
  u16 auth_key_len;
  u8 auth_key[auth_key_len];

  /* Extension(s). Reserved fields. */
  struct trn_extension extensions;

  /* Variable length, up to the end of cell. */
  u8 encrypted[];
};

/* INTRODUCE_ACK payload. See details in section 3.2.2. */
struct trn_cell_introduce_ack {
  /* Status of introduction. */
  u16 status;

  /* Extension(s). Reserved fields. */
  struct trn_extension extensions;
};

/* Encrypted section of the INTRODUCE1/INTRODUCE2 cell. */
struct trn_cell_introduce_encrypted {
  /* Rendezvous cookie. */
  u8 rend_cookie[TRUNNEL_REND_COOKIE_LEN];

  /* Extension(s). Reserved fields. */
  struct trn_extension extensions;

  /* Onion key material. */
  u8 onion_key_type IN [TRUNNEL_HS_INTRO_ONION_KEY_TYPE_NTOR];
  u16 onion_key_len;
  u8 onion_key[onion_key_len];

  /* Link specifiers(s) */
  u8 nspec;
  struct link_specifier nspecs[nspec];

  /* Optional padding. This might be empty or not. */
  u8 pad[];
};

/*
 * INTRODUCE1 cell (encrypted section) extensions.
 */

/* Cell extenstion type Congestion Control Request. */
const TRUNNEL_EXT_TYPE_CC_REQUEST = 0x01;
/* Cell extension type PoW. */
const TRUNNEL_EXT_TYPE_POW = 0x02;

/*
 * PoW Solution Extension. Proposal 327.
 */

const TRUNNEL_POW_NONCE_LEN = 16;
const TRUNNEL_POW_SOLUTION_LEN = 16;
const TRUNNEL_POW_SEED_HEAD_LEN = 4;

/* Version 1 is based on Equi-X scheme. */
const TRUNNEL_POW_VERSION_EQUIX = 0x01;

struct trn_cell_extension_pow {
  /* Type of PoW system used. */
  u8 pow_version IN [0x01];

  /* Nonce */
  u8 pow_nonce[TRUNNEL_POW_NONCE_LEN];

  /* Effort */
  u32 pow_effort;

  /* Identifiable prefix from the seed. */
  u8 pow_seed[TRUNNEL_POW_SEED_HEAD_LEN];

  /* Solution. */
  u8 pow_solution[TRUNNEL_POW_SOLUTION_LEN];
};
