/* Return a heap allocated string that contains the given <b>srv</b> string
* representation formatted for a networkstatus document using the
* <b>key</b> as the start of the line. This doesn't return NULL. */
static char *
srv_to_ns_string(const sr_srv_t *srv, const char *key)
{
char *srv_str;
char srv_hash_encoded[SR_SRV_VALUE_BASE64_LEN + 1];
tor_assert(srv);
tor_assert(key);
sr_srv_encode(srv_hash_encoded, sizeof(srv_hash_encoded), srv);
tor_asprintf(&srv_str, "%s %" PRIu64 " %s\n", key,
srv->num_reveals, srv_hash_encoded);
log_debug(LD_DIR, "SR: Consensus SRV line: %s", srv_str);
return srv_str;
}
/* From a valid srv object and an allocated config line, set the line's
* value to the state string representation of a shared random value. */
static void
disk_state_put_srv_line(const sr_srv_t *srv, config_line_t *line)
{
char encoded[SR_SRV_VALUE_BASE64_LEN + 1];
tor_assert(line);
/* No SRV value thus don't add the line. This is possible since we might
* not have a current or previous SRV value in our state. */
if (srv == NULL) {
return;
}
sr_srv_encode(encoded, sizeof(encoded), srv);
tor_asprintf(&line->value, "%" PRIu64 " %s", srv->num_reveals, encoded);
}
/* Return a srv object that is built with the construction:
* SRV = SHA3-256("shared-random" | INT_8(reveal_num) |
* INT_4(version) | HASHED_REVEALS | previous_SRV)
* This function cannot fail. */
static sr_srv_t *
generate_srv(const char *hashed_reveals, uint64_t reveal_num,
const sr_srv_t *previous_srv)
{
char msg[DIGEST256_LEN + SR_SRV_MSG_LEN] = {0};
size_t offset = 0;
sr_srv_t *srv;
tor_assert(hashed_reveals);
/* Add the invariant token. */
memcpy(msg, SR_SRV_TOKEN, SR_SRV_TOKEN_LEN);
offset += SR_SRV_TOKEN_LEN;
set_uint64(msg + offset, tor_htonll(reveal_num));
offset += sizeof(uint64_t);
set_uint32(msg + offset, htonl(SR_PROTO_VERSION));
offset += sizeof(uint32_t);
memcpy(msg + offset, hashed_reveals, DIGEST256_LEN);
offset += DIGEST256_LEN;
if (previous_srv != NULL) {
memcpy(msg + offset, previous_srv->value, sizeof(previous_srv->value));
}
/* Ok we have our message and key for the HMAC computation, allocate our
* srv object and do the last step. */
srv = tor_malloc_zero(sizeof(*srv));
crypto_digest256((char *) srv->value, msg, sizeof(msg), SR_DIGEST_ALG);
srv->num_reveals = reveal_num;
{
/* Debugging. */
char srv_hash_encoded[SR_SRV_VALUE_BASE64_LEN + 1];
sr_srv_encode(srv_hash_encoded, sizeof(srv_hash_encoded), srv);
log_info(LD_DIR, "SR: Generated SRV: %s", srv_hash_encoded);
}
return srv;
}
