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prop224: Add INTRODUCE1 cell relay support
Closes #20029 Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
parent
cacfd82c8d
commit
e1497744c8
@ -9,6 +9,7 @@
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#define HS_INTROPOINT_PRIVATE
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#include "or.h"
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#include "config.h"
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#include "circuitlist.h"
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#include "circuituse.h"
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#include "config.h"
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@ -16,27 +17,52 @@
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#include "rendmid.h"
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#include "rephist.h"
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#include "hs/cell_establish_intro.h"
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/* Trunnel */
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#include "ed25519_cert.h"
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#include "hs/cell_common.h"
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#include "hs/cell_establish_intro.h"
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#include "hs/cell_introduce1.h"
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#include "hs_circuitmap.h"
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#include "hs_intropoint.h"
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#include "hs_common.h"
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/** Extract the authentication key from an ESTABLISH_INTRO <b>cell</b> and
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* place it in <b>auth_key_out</b>. */
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/** Extract the authentication key from an ESTABLISH_INTRO or INTRODUCE1 using
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* the given <b>cell_type</b> from <b>cell</b> and place it in
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* <b>auth_key_out</b>. */
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STATIC void
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get_auth_key_from_establish_intro_cell(ed25519_public_key_t *auth_key_out,
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const hs_cell_establish_intro_t *cell)
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get_auth_key_from_cell(ed25519_public_key_t *auth_key_out,
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unsigned int cell_type, const void *cell)
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{
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size_t auth_key_len;
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const uint8_t *key_array;
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tor_assert(auth_key_out);
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tor_assert(cell);
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const uint8_t *key_array =
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hs_cell_establish_intro_getconstarray_auth_key(cell);
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switch (cell_type) {
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case RELAY_COMMAND_ESTABLISH_INTRO:
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{
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const hs_cell_establish_intro_t *c_cell = cell;
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key_array = hs_cell_establish_intro_getconstarray_auth_key(c_cell);
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auth_key_len = hs_cell_establish_intro_getlen_auth_key(c_cell);
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break;
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}
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case RELAY_COMMAND_INTRODUCE1:
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{
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const hs_cell_introduce1_t *c_cell = cell;
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key_array = hs_cell_introduce1_getconstarray_auth_key(cell);
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auth_key_len = hs_cell_introduce1_getlen_auth_key(c_cell);
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break;
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}
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default:
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/* Getting here is really bad as it means we got a unknown cell type from
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* this file where every call has an hardcoded value. */
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tor_assert(0);
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}
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tor_assert(key_array);
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tor_assert(hs_cell_establish_intro_getlen_auth_key(cell) ==
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sizeof(auth_key_out->pubkey));
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memcpy(auth_key_out->pubkey, key_array, cell->auth_key_len);
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tor_assert(auth_key_len == sizeof(auth_key_out->pubkey));
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memcpy(auth_key_out->pubkey, key_array, auth_key_len);
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}
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/** We received an ESTABLISH_INTRO <b>cell</b>. Verify its signature and MAC,
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@ -79,7 +105,7 @@ verify_establish_intro_cell(const hs_cell_establish_intro_t *cell,
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memcpy(sig_struct.sig, sig_array, cell->sig_len);
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ed25519_public_key_t auth_key;
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get_auth_key_from_establish_intro_cell(&auth_key, cell);
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get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO, cell);
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const size_t sig_msg_len = cell->end_sig_fields - msg;
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int sig_mismatch = ed25519_checksig_prefixed(&sig_struct,
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@ -154,7 +180,8 @@ handle_verified_establish_intro_cell(or_circuit_t *circ,
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{
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/* Get the auth key of this intro point */
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ed25519_public_key_t auth_key;
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get_auth_key_from_establish_intro_cell(&auth_key, parsed_cell);
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get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO,
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parsed_cell);
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/* Then notify the hidden service that the intro point is established by
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sending an INTRO_ESTABLISHED cell */
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@ -232,26 +259,38 @@ handle_establish_intro(or_circuit_t *circ, const uint8_t *request,
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return retval;
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}
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/* Return True if circuit is suitable for becoming an intro circuit. */
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int
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hs_intro_circuit_is_suitable(const or_circuit_t *circ)
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/* Return True if circuit is suitable for being an intro circuit. */
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static int
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circuit_is_suitable_intro_point(const or_circuit_t *circ,
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const char *log_cell_type_str)
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{
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tor_assert(circ);
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tor_assert(log_cell_type_str);
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/* Basic circuit state sanity checks. */
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if (circ->base_.purpose != CIRCUIT_PURPOSE_OR) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"Rejecting ESTABLISH_INTRO on non-OR circuit.");
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"Rejecting %s on non-OR circuit.", log_cell_type_str);
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return 0;
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}
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if (circ->base_.n_chan) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"Rejecting ESTABLISH_INTRO on non-edge circuit.");
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"Rejecting %s on non-edge circuit.", log_cell_type_str);
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return 0;
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}
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/* Suitable. */
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return 1;
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}
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/* Return True if circuit is suitable for becoming an intro circuit. */
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int
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hs_intro_circuit_is_suitable(const or_circuit_t *circ)
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{
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return circuit_is_suitable_intro_point(circ, "ESTABLISH_INTRO");
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}
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/* We just received an ESTABLISH_INTRO cell in <b>circ</b>. Figure out of it's
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* a legacy or a next gen cell, and pass it to the appropriate handler. */
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int
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@ -286,3 +325,266 @@ hs_intro_received_establish_intro(or_circuit_t *circ, const uint8_t *request,
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return -1;
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}
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/* Send an INTRODUCE_ACK cell onto the circuit <b>circ</b> with the status
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* value in <b>status</b>. Depending on the status, it can be ACK or a NACK.
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* Return 0 on success else a negative value on error which will close the
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* circuit. */
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static int
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send_introduce_ack_cell(or_circuit_t *circ, hs_intro_ack_status_t status)
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{
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int ret = -1;
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uint8_t *encoded_cell = NULL;
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ssize_t encoded_len, result_len;
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hs_cell_introduce_ack_t *cell;
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cell_extension_t *ext;
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tor_assert(circ);
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/* Setup the INTRODUCE_ACK cell. We have no extensions so the N_EXTENSIONS
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* field is set to 0 by default with a new object. */
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cell = hs_cell_introduce_ack_new();
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ret = hs_cell_introduce_ack_set_status(cell, status);
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/* We have no cell extensions in an INTRODUCE_ACK cell. */
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ext = cell_extension_new();
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cell_extension_set_num(ext, 0);
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hs_cell_introduce_ack_set_extensions(cell, ext);
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/* A wrong status is a very bad code flow error as this value is controlled
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* by the code in this file and not an external input. This means we use a
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* code that is not known by the trunnel ABI. */
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tor_assert(ret == 0);
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/* Encode the payload. We should never fail to get the encoded length. */
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encoded_len = hs_cell_introduce_ack_encoded_len(cell);
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tor_assert(encoded_len > 0);
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encoded_cell = tor_malloc_zero(encoded_len);
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result_len = hs_cell_introduce_ack_encode(encoded_cell, encoded_len, cell);
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tor_assert(encoded_len == result_len);
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ret = relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ),
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RELAY_COMMAND_INTRODUCE_ACK,
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(char *) encoded_cell, encoded_len,
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NULL);
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/* On failure, the above function will close the circuit. */
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hs_cell_introduce_ack_free(cell);
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tor_free(encoded_cell);
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return ret;
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}
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/* Validate a parsed INTRODUCE1 <b>cell</b>. Return 0 if valid or else a
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* negative value for an invalid cell that should be NACKed. */
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static int
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validate_introduce1_parsed_cell(const hs_cell_introduce1_t *cell)
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{
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size_t legacy_key_id_len;
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const uint8_t *legacy_key_id;
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tor_assert(cell);
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/* This code path SHOULD NEVER be reached if the cell is a legacy type so
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* safety net here. The legacy ID must be zeroes in this case. */
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legacy_key_id_len = hs_cell_introduce1_getlen_legacy_key_id(cell);
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legacy_key_id = hs_cell_introduce1_getconstarray_legacy_key_id(cell);
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if (BUG(!tor_mem_is_zero((char *) legacy_key_id, legacy_key_id_len))) {
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goto invalid;
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}
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/* The auth key of an INTRODUCE1 should be of type ed25519 thus leading to a
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* known fixed length as well. */
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if (hs_cell_introduce1_get_auth_key_type(cell) !=
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HS_INTRO_AUTH_KEY_TYPE_ED25519) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"Rejecting invalid INTRODUCE1 cell auth key type. "
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"Responding with NACK.");
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goto invalid;
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}
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if (hs_cell_introduce1_get_auth_key_len(cell) != ED25519_PUBKEY_LEN ||
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hs_cell_introduce1_getlen_auth_key(cell) != ED25519_PUBKEY_LEN) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"Rejecting invalid INTRODUCE1 cell auth key length. "
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"Responding with NACK.");
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goto invalid;
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}
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if (hs_cell_introduce1_getlen_encrypted(cell) == 0) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"Rejecting invalid INTRODUCE1 cell encrypted length. "
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"Responding with NACK.");
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goto invalid;
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}
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return 0;
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invalid:
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return -1;
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}
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/* We just received a non legacy INTRODUCE1 cell on <b>client_circ</b> with
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* the payload in <b>request</b> of size <b>request_len</b>. Return 0 if
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* everything went well, or -1 if an error occured. This function is in charge
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* of sending back an INTRODUCE_ACK cell and will close client_circ on error.
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*/
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static int
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handle_introduce1(or_circuit_t *client_circ, const uint8_t *request,
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size_t request_len)
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{
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int ret = -1;
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or_circuit_t *service_circ;
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hs_cell_introduce1_t *parsed_cell;
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hs_intro_ack_status_t status = HS_INTRO_ACK_STATUS_SUCCESS;
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tor_assert(client_circ);
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tor_assert(request);
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/* Parse cell. Note that we can only parse the non encrypted section for
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* which we'll use the authentication key to find the service introduction
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* circuit and relay the cell on it. */
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ssize_t cell_size = hs_cell_introduce1_parse(&parsed_cell, request,
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request_len);
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if (cell_size < 0) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"Rejecting %s INTRODUCE1 cell. Responding with NACK.",
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cell_size == -1 ? "invalid" : "truncated");
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/* Inform client that the INTRODUCE1 has a bad format. */
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status = HS_INTRO_ACK_STATUS_BAD_FORMAT;
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goto send_ack;
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}
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/* Once parsed, validate the cell expected format once parsed. */
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if (validate_introduce1_parsed_cell(parsed_cell) < 0) {
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/* Inform client that the INTRODUCE1 has bad format. */
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status = HS_INTRO_ACK_STATUS_BAD_FORMAT;
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goto send_ack;
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}
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/* Find introduction circuit through our circuit map. */
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{
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ed25519_public_key_t auth_key;
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get_auth_key_from_cell(&auth_key, RELAY_COMMAND_INTRODUCE1, parsed_cell);
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service_circ = hs_circuitmap_get_intro_circ_v3(&auth_key);
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if (service_circ == NULL) {
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char b64_key[ED25519_BASE64_LEN + 1];
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ed25519_public_to_base64(b64_key, &auth_key);
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log_info(LD_REND, "No intro circuit found for INTRODUCE1 cell "
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"with auth key %s from circuit %" PRIu32 ". "
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"Responding with NACK.",
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safe_str(b64_key), client_circ->p_circ_id);
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/* Inform the client that we don't know the requested service ID. */
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status = HS_INTRO_ACK_STATUS_UNKNOWN_ID;
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goto send_ack;
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}
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}
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/* Relay the cell to the service on its intro circuit with an INTRODUCE2
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* cell which is the same exact payload. */
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if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(service_circ),
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RELAY_COMMAND_INTRODUCE2,
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(char *) request, request_len, NULL)) {
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log_warn(LD_REND, "Unable to send INTRODUCE2 cell to the service.");
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/* Inform the client that we can't relay the cell. */
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status = HS_INTRO_ACK_STATUS_CANT_RELAY;
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goto send_ack;
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}
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/* Success! Send an INTRODUCE_ACK success status onto the client circuit. */
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status = HS_INTRO_ACK_STATUS_SUCCESS;
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ret = 0;
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send_ack:
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/* Send the INTRODUCE_ACK cell to the client with a specific status. */
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if (send_introduce_ack_cell(client_circ, status) < 0) {
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log_warn(LD_REND, "Unable to send an INTRODUCE ACK status %d to client.",
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status);
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/* Circuit has been closed on failure of transmission. */
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goto done;
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}
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if (status != HS_INTRO_ACK_STATUS_SUCCESS) {
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/* We just sent a NACK that is a non success status code so close the
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* circuit because it's not useful to keep it open. Remember, a client can
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* only send one INTRODUCE1 cell on a circuit. */
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circuit_mark_for_close(TO_CIRCUIT(client_circ), END_CIRC_REASON_INTERNAL);
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}
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done:
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hs_cell_introduce1_free(parsed_cell);
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return ret;
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}
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/* Identify if the encoded cell we just received is a legacy one or not. The
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* <b>request</b> should be at least DIGEST_LEN bytes long. */
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static int
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introduce1_cell_is_legacy(const uint8_t *request)
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{
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tor_assert(request);
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/* If the first 20 bytes of the cell (DIGEST_LEN) are NOT zeroes, it
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* indicates a legacy cell (v2). */
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if (!tor_mem_is_zero((const char *) request, DIGEST_LEN)) {
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/* Legacy cell. */
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return 1;
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}
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/* Not a legacy cell. */
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return 0;
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}
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/* Return true iff the circuit <b>circ</b> is suitable for receiving an
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* INTRODUCE1 cell. */
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static int
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circuit_is_suitable_for_introduce1(const or_circuit_t *circ)
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{
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tor_assert(circ);
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/* First of all, do we have a valid circuit to be an introduction point? */
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if (!circuit_is_suitable_intro_point(circ, "INTRODUCE1")) {
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return 0;
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}
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if (circ->already_received_introduce1) {
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log_fn(LOG_PROTOCOL_WARN, LD_REND,
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"Blocking multiple introductions on the same circuit. "
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"Someone might be trying to attack a hidden service through "
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"this relay.");
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return 0;
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}
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return 1;
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}
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/* We just received an INTRODUCE1 cell on <b>circ</b>. Figure out which type
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* it is and pass it to the appropriate handler. Return 0 on success else a
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* negative value and the circuit is closed. */
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int
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hs_intro_received_introduce1(or_circuit_t *circ, const uint8_t *request,
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size_t request_len)
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{
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int ret;
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tor_assert(circ);
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tor_assert(request);
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/* A cell that can't hold a DIGEST_LEN is invalid as we need to check if
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* it's a legacy cell or not using the first DIGEST_LEN bytes. */
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if (request_len < DIGEST_LEN) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Invalid INTRODUCE1 cell length.");
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goto err;
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}
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/* Make sure we have a circuit that can have an INTRODUCE1 cell on it. */
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if (!circuit_is_suitable_for_introduce1(circ)) {
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/* We do not send a NACK because the circuit is not suitable for any kind
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* of response or transmission as it's a violation of the protocol. */
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goto err;
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}
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/* Mark the circuit that we got this cell. None are allowed after this as a
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* DoS mitigation since one circuit with one client can hammer a service. */
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circ->already_received_introduce1 = 1;
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/* We are sure here to have at least DIGEST_LEN bytes. */
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if (introduce1_cell_is_legacy(request)) {
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/* Handle a legacy cell. */
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ret = rend_mid_introduce(circ, request, request_len);
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} else {
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/* Handle a non legacy cell. */
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ret = handle_introduce1(circ, request, request_len);
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}
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return ret;
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err:
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circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
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return -1;
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}
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@ -16,9 +16,19 @@ enum hs_intro_auth_key_type {
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HS_INTRO_AUTH_KEY_TYPE_ED25519 = 0x02,
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};
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/* INTRODUCE_ACK status code. */
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typedef enum {
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HS_INTRO_ACK_STATUS_SUCCESS = 0x0000,
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HS_INTRO_ACK_STATUS_UNKNOWN_ID = 0x0001,
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HS_INTRO_ACK_STATUS_BAD_FORMAT = 0x0002,
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HS_INTRO_ACK_STATUS_CANT_RELAY = 0x0003,
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} hs_intro_ack_status_t;
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int hs_intro_received_establish_intro(or_circuit_t *circ,
|
||||
const uint8_t *request,
|
||||
size_t request_len);
|
||||
int hs_intro_received_introduce1(or_circuit_t *circ, const uint8_t *request,
|
||||
size_t request_len);
|
||||
|
||||
MOCK_DECL(int, hs_intro_send_intro_established_cell,(or_circuit_t *circ));
|
||||
|
||||
@ -33,8 +43,8 @@ verify_establish_intro_cell(const hs_cell_establish_intro_t *out,
|
||||
size_t circuit_key_material_len);
|
||||
|
||||
STATIC void
|
||||
get_auth_key_from_establish_intro_cell(ed25519_public_key_t *auth_key_out,
|
||||
const hs_cell_establish_intro_t *cell);
|
||||
get_auth_key_from_cell(ed25519_public_key_t *auth_key_out,
|
||||
unsigned int cell_type, const void *cell);
|
||||
|
||||
#endif /* HS_INTROPOINT_PRIVATE */
|
||||
|
||||
|
@ -771,7 +771,7 @@ rend_process_relay_cell(circuit_t *circ, const crypt_path_t *layer_hint,
|
||||
break;
|
||||
case RELAY_COMMAND_INTRODUCE1:
|
||||
if (or_circ)
|
||||
r = rend_mid_introduce(or_circ,payload,length);
|
||||
r = hs_intro_received_introduce1(or_circ,payload,length);
|
||||
break;
|
||||
case RELAY_COMMAND_INTRODUCE2:
|
||||
if (origin_circ)
|
||||
|
@ -294,7 +294,8 @@ test_intro_point_registration(void *arg)
|
||||
the_hs_circuitmap = get_hs_circuitmap();
|
||||
tt_assert(the_hs_circuitmap);
|
||||
tt_int_op(1, ==, HT_SIZE(the_hs_circuitmap));
|
||||
get_auth_key_from_establish_intro_cell(&auth_key, establish_intro_cell);
|
||||
get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO,
|
||||
establish_intro_cell);
|
||||
returned_intro_circ = hs_circuitmap_get_intro_circ_v3(&auth_key);
|
||||
tt_ptr_op(intro_circ, ==, returned_intro_circ);
|
||||
}
|
||||
|
Loading…
Reference in New Issue
Block a user