tor/src/trunnel/hs/cell_establish_intro.trunnel

/*
 * This contains the definition of the ESTABLISH_INTRO and INTRO_ESTABLISHED
 * cell for onion service version 3 and onward. The following format is
 * specified in proposal 224 section 3.1.
 */

extern struct trn_cell_extension;

const TRUNNEL_SHA3_256_LEN = 32;

/* ESTABLISH_INTRO payload. See details in section 3.1.1 */
struct trn_cell_establish_intro {
  /* Indicate the start of the handshake authentication data. */
  @ptr start_cell;

  /* Authentication key material. */
  u8 auth_key_type IN [0x00, 0x01, 0x02];
  u16 auth_key_len;
  u8 auth_key[auth_key_len];

  /* Extension(s). Reserved fields. */
  struct trn_cell_extension extensions;
  @ptr end_mac_fields;

  /* Handshake MAC. */
  u8 handshake_mac[TRUNNEL_SHA3_256_LEN];

  /* Signature */
  /* Indicate the end of the handshake authentication data. */
  @ptr end_sig_fields;
  u16 sig_len;
  u8 sig[sig_len];
};

/* INTRO_ESTABLISHED payload which is an acknowledge of the ESTABLISH_INTRO
 * cell. For legacy node, this payload is empty so the following only applies
 * to version >= 3. */
struct trn_cell_intro_established {
  /* Extension(s). Reserved fields. */
  struct trn_cell_extension extensions;
};