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- /*
- * Copyright (c) 2019, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file crypt_path.c
- *
- * \brief Functions dealing with layered circuit encryption. This file aims to
- * provide an API around the crypt_path_t structure which holds crypto
- * information about a specific hop of a circuit.
- *
- * TODO: We should eventually move all functions dealing and manipulating
- * crypt_path_t to this file, so that eventually we encapsulate more and more
- * of crypt_path_t. Here are some more functions that can be moved here with
- * some more effort:
- *
- * - circuit_list_path_impl()
- * - Functions dealing with cpaths in HSv2 create_rend_cpath() and
- * create_rend_cpath_legacy()
- * - The cpath related parts of rend_service_receive_introduction() and
- * rend_client_send_introduction().
- **/
- #define CRYPT_PATH_PRIVATE
- #include "core/or/or.h"
- #include "core/or/crypt_path.h"
- #include "core/crypto/relay_crypto.h"
- #include "core/crypto/onion_crypto.h"
- #include "core/or/circuitbuild.h"
- #include "core/or/circuitlist.h"
- #include "lib/crypt_ops/crypto_dh.h"
- #include "lib/crypt_ops/crypto_util.h"
- #include "core/or/crypt_path_st.h"
- #include "core/or/cell_st.h"
- /** Add <b>new_hop</b> to the end of the doubly-linked-list <b>head_ptr</b>.
- * This function is used to extend cpath by another hop.
- */
- void
- cpath_extend_linked_list(crypt_path_t **head_ptr, crypt_path_t *new_hop)
- {
- if (*head_ptr) {
- new_hop->next = (*head_ptr);
- new_hop->prev = (*head_ptr)->prev;
- (*head_ptr)->prev->next = new_hop;
- (*head_ptr)->prev = new_hop;
- } else {
- *head_ptr = new_hop;
- new_hop->prev = new_hop->next = new_hop;
- }
- }
- /** Create a new hop, annotate it with information about its
- * corresponding router <b>choice</b>, and append it to the
- * end of the cpath <b>head_ptr</b>. */
- int
- cpath_append_hop(crypt_path_t **head_ptr, extend_info_t *choice)
- {
- crypt_path_t *hop = tor_malloc_zero(sizeof(crypt_path_t));
- /* link hop into the cpath, at the end. */
- cpath_extend_linked_list(head_ptr, hop);
- hop->magic = CRYPT_PATH_MAGIC;
- hop->state = CPATH_STATE_CLOSED;
- hop->extend_info = extend_info_dup(choice);
- hop->package_window = circuit_initial_package_window();
- hop->deliver_window = CIRCWINDOW_START;
- return 0;
- }
- /** Verify that cpath <b>cp</b> has all of its invariants
- * correct. Trigger an assert if anything is invalid.
- */
- void
- cpath_assert_ok(const crypt_path_t *cp)
- {
- const crypt_path_t *start = cp;
- do {
- cpath_assert_layer_ok(cp);
- /* layers must be in sequence of: "open* awaiting? closed*" */
- if (cp != start) {
- if (cp->state == CPATH_STATE_AWAITING_KEYS) {
- tor_assert(cp->prev->state == CPATH_STATE_OPEN);
- } else if (cp->state == CPATH_STATE_OPEN) {
- tor_assert(cp->prev->state == CPATH_STATE_OPEN);
- }
- }
- cp = cp->next;
- tor_assert(cp);
- } while (cp != start);
- }
- /** Verify that cpath layer <b>cp</b> has all of its invariants
- * correct. Trigger an assert if anything is invalid.
- */
- void
- cpath_assert_layer_ok(const crypt_path_t *cp)
- {
- // tor_assert(cp->addr); /* these are zero for rendezvous extra-hops */
- // tor_assert(cp->port);
- tor_assert(cp);
- tor_assert(cp->magic == CRYPT_PATH_MAGIC);
- switch (cp->state)
- {
- case CPATH_STATE_OPEN:
- relay_crypto_assert_ok(&cp->pvt_crypto);
- /* fall through */
- case CPATH_STATE_CLOSED:
- /*XXXX Assert that there's no handshake_state either. */
- tor_assert(!cp->rend_dh_handshake_state);
- break;
- case CPATH_STATE_AWAITING_KEYS:
- /* tor_assert(cp->dh_handshake_state); */
- break;
- default:
- log_fn(LOG_ERR, LD_BUG, "Unexpected state %d", cp->state);
- tor_assert(0);
- }
- tor_assert(cp->package_window >= 0);
- tor_assert(cp->deliver_window >= 0);
- }
- /** Initialize cpath-\>{f|b}_{crypto|digest} from the key material in key_data.
- *
- * If <b>is_hs_v3</b> is set, this cpath will be used for next gen hidden
- * service circuits and <b>key_data</b> must be at least
- * HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN bytes in length.
- *
- * If <b>is_hs_v3</b> is not set, key_data must contain CPATH_KEY_MATERIAL_LEN
- * bytes, which are used as follows:
- * - 20 to initialize f_digest
- * - 20 to initialize b_digest
- * - 16 to key f_crypto
- * - 16 to key b_crypto
- *
- * (If 'reverse' is true, then f_XX and b_XX are swapped.)
- *
- * Return 0 if init was successful, else -1 if it failed.
- */
- int
- cpath_init_circuit_crypto(crypt_path_t *cpath,
- const char *key_data, size_t key_data_len,
- int reverse, int is_hs_v3)
- {
- tor_assert(cpath);
- return relay_crypto_init(&cpath->pvt_crypto, key_data, key_data_len,
- reverse, is_hs_v3);
- }
- /** Deallocate space associated with the cpath node <b>victim</b>. */
- void
- cpath_free(crypt_path_t *victim)
- {
- if (!victim)
- return;
- relay_crypto_clear(&victim->pvt_crypto);
- onion_handshake_state_release(&victim->handshake_state);
- crypto_dh_free(victim->rend_dh_handshake_state);
- extend_info_free(victim->extend_info);
- memwipe(victim, 0xBB, sizeof(crypt_path_t)); /* poison memory */
- tor_free(victim);
- }
- /********************** cpath crypto API *******************************/
- /** Encrypt or decrypt <b>payload</b> using the crypto of <b>cpath</b>. Actual
- * operation decided by <b>is_decrypt</b>. */
- void
- cpath_crypt_cell(const crypt_path_t *cpath, uint8_t *payload, bool is_decrypt)
- {
- if (is_decrypt) {
- relay_crypt_one_payload(cpath->pvt_crypto.b_crypto, payload);
- } else {
- relay_crypt_one_payload(cpath->pvt_crypto.f_crypto, payload);
- }
- }
- /** Getter for the incoming digest of <b>cpath</b>. */
- struct crypto_digest_t *
- cpath_get_incoming_digest(const crypt_path_t *cpath)
- {
- return cpath->pvt_crypto.b_digest;
- }
- /** Set the right integrity digest on the outgoing <b>cell</b> based on the
- * cell payload and update the forward digest of <b>cpath</b>. */
- void
- cpath_set_cell_forward_digest(crypt_path_t *cpath, cell_t *cell)
- {
- relay_set_digest(cpath->pvt_crypto.f_digest, cell);
- }
- /************ cpath sendme API ***************************/
- /** Return the sendme_digest of this <b>cpath</b>. */
- uint8_t *
- cpath_get_sendme_digest(crypt_path_t *cpath)
- {
- return relay_crypto_get_sendme_digest(&cpath->pvt_crypto);
- }
- /** Record the cell digest, indicated by is_foward_digest or not, as the
- * SENDME cell digest. */
- void
- cpath_sendme_record_cell_digest(crypt_path_t *cpath, bool is_foward_digest)
- {
- tor_assert(cpath);
- relay_crypto_record_sendme_digest(&cpath->pvt_crypto, is_foward_digest);
- }
- /************ other cpath functions ***************************/
- /** Return the first non-open hop in cpath, or return NULL if all
- * hops are open. */
- crypt_path_t *
- cpath_get_next_non_open_hop(crypt_path_t *cpath)
- {
- crypt_path_t *hop = cpath;
- do {
- if (hop->state != CPATH_STATE_OPEN)
- return hop;
- hop = hop->next;
- } while (hop != cpath);
- return NULL;
- }
- #ifdef TOR_UNIT_TESTS
- /** Unittest helper function: Count number of hops in cpath linked list. */
- unsigned int
- cpath_get_n_hops(crypt_path_t **head_ptr)
- {
- unsigned int n_hops = 0;
- crypt_path_t *tmp;
- if (!*head_ptr) {
- return 0;
- }
- tmp = *head_ptr;
- do {
- n_hops++;
- tmp = tmp->next;
- } while (tmp != *head_ptr);
- return n_hops;
- }
- #endif /* defined(TOR_UNIT_TESTS) */
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