[tor-commits] [tor/maint-0.3.5] Merge branch 'tor-github/pr/487' into maint-0.3.5
dgoulet at torproject.org
dgoulet at torproject.org
Tue Nov 13 15:46:21 UTC 2018
commit 6f2151be9a3e8b535bff4477a17f9c41d3f1d7f4
Merge: ae4c94bb6 f89f14802
Author: David Goulet <dgoulet at torproject.org>
Date: Tue Nov 13 10:37:25 2018 -0500
Merge branch 'tor-github/pr/487' into maint-0.3.5
changes/bug27841 | 7 +++++++
src/feature/hs/hs_intropoint.c | 6 ------
2 files changed, 7 insertions(+), 6 deletions(-)
diff --cc src/feature/hs/hs_intropoint.c
index c716447c9,000000000..2ea53af6a
mode 100644,000000..100644
--- a/src/feature/hs/hs_intropoint.c
+++ b/src/feature/hs/hs_intropoint.c
@@@ -1,614 -1,0 +1,608 @@@
+/* Copyright (c) 2016-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file hs_intropoint.c
+ * \brief Implement next generation introductions point functionality
+ **/
+
+#define HS_INTROPOINT_PRIVATE
+
+#include "core/or/or.h"
+#include "app/config/config.h"
+#include "core/or/circuitlist.h"
+#include "core/or/circuituse.h"
+#include "core/or/relay.h"
+#include "feature/rend/rendmid.h"
+#include "feature/stats/rephist.h"
+#include "lib/crypt_ops/crypto_format.h"
+
+/* Trunnel */
+#include "trunnel/ed25519_cert.h"
+#include "trunnel/hs/cell_common.h"
+#include "trunnel/hs/cell_establish_intro.h"
+#include "trunnel/hs/cell_introduce1.h"
+
+#include "feature/hs/hs_circuitmap.h"
+#include "feature/hs/hs_descriptor.h"
+#include "feature/hs/hs_intropoint.h"
+#include "feature/hs/hs_common.h"
+
+#include "core/or/or_circuit_st.h"
+
+/** Extract the authentication key from an ESTABLISH_INTRO or INTRODUCE1 using
+ * the given <b>cell_type</b> from <b>cell</b> and place it in
+ * <b>auth_key_out</b>. */
+STATIC void
+get_auth_key_from_cell(ed25519_public_key_t *auth_key_out,
+ unsigned int cell_type, const void *cell)
+{
+ size_t auth_key_len;
+ const uint8_t *key_array;
+
+ tor_assert(auth_key_out);
+ tor_assert(cell);
+
+ switch (cell_type) {
+ case RELAY_COMMAND_ESTABLISH_INTRO:
+ {
+ const trn_cell_establish_intro_t *c_cell = cell;
+ key_array = trn_cell_establish_intro_getconstarray_auth_key(c_cell);
+ auth_key_len = trn_cell_establish_intro_getlen_auth_key(c_cell);
+ break;
+ }
+ case RELAY_COMMAND_INTRODUCE1:
+ {
+ const trn_cell_introduce1_t *c_cell = cell;
+ key_array = trn_cell_introduce1_getconstarray_auth_key(cell);
+ auth_key_len = trn_cell_introduce1_getlen_auth_key(c_cell);
+ break;
+ }
+ default:
+ /* Getting here is really bad as it means we got a unknown cell type from
+ * this file where every call has an hardcoded value. */
+ tor_assert_unreached(); /* LCOV_EXCL_LINE */
+ }
+ tor_assert(key_array);
+ tor_assert(auth_key_len == sizeof(auth_key_out->pubkey));
+ memcpy(auth_key_out->pubkey, key_array, auth_key_len);
+}
+
+/** We received an ESTABLISH_INTRO <b>cell</b>. Verify its signature and MAC,
+ * given <b>circuit_key_material</b>. Return 0 on success else -1 on error. */
+STATIC int
+verify_establish_intro_cell(const trn_cell_establish_intro_t *cell,
+ const uint8_t *circuit_key_material,
+ size_t circuit_key_material_len)
+{
+ /* We only reach this function if the first byte of the cell is 0x02 which
+ * means that auth_key_type is of ed25519 type, hence this check should
+ * always pass. See hs_intro_received_establish_intro(). */
+ if (BUG(cell->auth_key_type != HS_INTRO_AUTH_KEY_TYPE_ED25519)) {
+ return -1;
+ }
+
+ /* Make sure the auth key length is of the right size for this type. For
+ * EXTRA safety, we check both the size of the array and the length which
+ * must be the same. Safety first!*/
+ if (trn_cell_establish_intro_getlen_auth_key(cell) != ED25519_PUBKEY_LEN ||
+ trn_cell_establish_intro_get_auth_key_len(cell) != ED25519_PUBKEY_LEN) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "ESTABLISH_INTRO auth key length is invalid");
+ return -1;
+ }
+
+ const uint8_t *msg = cell->start_cell;
+
+ /* Verify the sig */
+ {
+ ed25519_signature_t sig_struct;
+ const uint8_t *sig_array =
+ trn_cell_establish_intro_getconstarray_sig(cell);
+
+ /* Make sure the signature length is of the right size. For EXTRA safety,
+ * we check both the size of the array and the length which must be the
+ * same. Safety first!*/
+ if (trn_cell_establish_intro_getlen_sig(cell) != sizeof(sig_struct.sig) ||
+ trn_cell_establish_intro_get_sig_len(cell) != sizeof(sig_struct.sig)) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "ESTABLISH_INTRO sig len is invalid");
+ return -1;
+ }
+ /* We are now sure that sig_len is of the right size. */
+ memcpy(sig_struct.sig, sig_array, cell->sig_len);
+
+ ed25519_public_key_t auth_key;
+ get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO, cell);
+
+ const size_t sig_msg_len = cell->end_sig_fields - msg;
+ int sig_mismatch = ed25519_checksig_prefixed(&sig_struct,
+ msg, sig_msg_len,
+ ESTABLISH_INTRO_SIG_PREFIX,
+ &auth_key);
+ if (sig_mismatch) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "ESTABLISH_INTRO signature not as expected");
+ return -1;
+ }
+ }
+
+ /* Verify the MAC */
+ {
+ const size_t auth_msg_len = cell->end_mac_fields - msg;
+ uint8_t mac[DIGEST256_LEN];
+ crypto_mac_sha3_256(mac, sizeof(mac),
+ circuit_key_material, circuit_key_material_len,
+ msg, auth_msg_len);
+ if (tor_memneq(mac, cell->handshake_mac, sizeof(mac))) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "ESTABLISH_INTRO handshake_auth not as expected");
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/* Send an INTRO_ESTABLISHED cell to <b>circ</b>. */
+MOCK_IMPL(int,
+hs_intro_send_intro_established_cell,(or_circuit_t *circ))
+{
+ int ret;
+ uint8_t *encoded_cell = NULL;
+ ssize_t encoded_len, result_len;
+ trn_cell_intro_established_t *cell;
+ trn_cell_extension_t *ext;
+
+ tor_assert(circ);
+
+ /* Build the cell payload. */
+ cell = trn_cell_intro_established_new();
+ ext = trn_cell_extension_new();
+ trn_cell_extension_set_num(ext, 0);
+ trn_cell_intro_established_set_extensions(cell, ext);
+ /* Encode the cell to binary format. */
+ encoded_len = trn_cell_intro_established_encoded_len(cell);
+ tor_assert(encoded_len > 0);
+ encoded_cell = tor_malloc_zero(encoded_len);
+ result_len = trn_cell_intro_established_encode(encoded_cell, encoded_len,
+ cell);
+ tor_assert(encoded_len == result_len);
+
+ ret = relay_send_command_from_edge(0, TO_CIRCUIT(circ),
+ RELAY_COMMAND_INTRO_ESTABLISHED,
+ (char *) encoded_cell, encoded_len,
+ NULL);
+ /* On failure, the above function will close the circuit. */
+ trn_cell_intro_established_free(cell);
+ tor_free(encoded_cell);
+ return ret;
+}
+
+/** We received an ESTABLISH_INTRO <b>parsed_cell</b> on <b>circ</b>. It's
+ * well-formed and passed our verifications. Perform appropriate actions to
+ * establish an intro point. */
+static int
+handle_verified_establish_intro_cell(or_circuit_t *circ,
+ const trn_cell_establish_intro_t *parsed_cell)
+{
+ /* Get the auth key of this intro point */
+ ed25519_public_key_t auth_key;
+ get_auth_key_from_cell(&auth_key, RELAY_COMMAND_ESTABLISH_INTRO,
+ parsed_cell);
+
+ /* Then notify the hidden service that the intro point is established by
+ sending an INTRO_ESTABLISHED cell */
+ if (hs_intro_send_intro_established_cell(circ)) {
+ log_warn(LD_PROTOCOL, "Couldn't send INTRO_ESTABLISHED cell.");
+ return -1;
+ }
+
+ /* Associate intro point auth key with this circuit. */
+ hs_circuitmap_register_intro_circ_v3_relay_side(circ, &auth_key);
+ /* Repurpose this circuit into an intro circuit. */
+ circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT);
+
+ return 0;
+}
+
+/** We just received an ESTABLISH_INTRO cell in <b>circ</b> with payload in
+ * <b>request</b>. Handle it by making <b>circ</b> an intro circuit. Return 0
+ * if everything went well, or -1 if there were errors. */
+static int
+handle_establish_intro(or_circuit_t *circ, const uint8_t *request,
+ size_t request_len)
+{
+ int cell_ok, retval = -1;
+ trn_cell_establish_intro_t *parsed_cell = NULL;
+
+ tor_assert(circ);
+ tor_assert(request);
+
+ log_info(LD_REND, "Received an ESTABLISH_INTRO request on circuit %" PRIu32,
+ circ->p_circ_id);
+
+ /* Check that the circuit is in shape to become an intro point */
+ if (!hs_intro_circuit_is_suitable_for_establish_intro(circ)) {
+ goto err;
+ }
+
+ /* Parse the cell */
+ ssize_t parsing_result = trn_cell_establish_intro_parse(&parsed_cell,
+ request, request_len);
+ if (parsing_result < 0) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting %s ESTABLISH_INTRO cell.",
+ parsing_result == -1 ? "invalid" : "truncated");
+ goto err;
+ }
+
+ cell_ok = verify_establish_intro_cell(parsed_cell,
+ (uint8_t *) circ->rend_circ_nonce,
+ sizeof(circ->rend_circ_nonce));
+ if (cell_ok < 0) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Failed to verify ESTABLISH_INTRO cell.");
+ goto err;
+ }
+
+ /* This cell is legit. Take the appropriate actions. */
+ cell_ok = handle_verified_establish_intro_cell(circ, parsed_cell);
+ if (cell_ok < 0) {
+ goto err;
+ }
+
+ /* We are done! */
+ retval = 0;
+ goto done;
+
+ err:
+ /* When sending the intro establish ack, on error the circuit can be marked
+ * as closed so avoid a double close. */
+ if (!TO_CIRCUIT(circ)->marked_for_close) {
+ circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
+ }
+
+ done:
+ trn_cell_establish_intro_free(parsed_cell);
+ return retval;
+}
+
+/* Return True if circuit is suitable for being an intro circuit. */
+static int
+circuit_is_suitable_intro_point(const or_circuit_t *circ,
+ const char *log_cell_type_str)
+{
+ tor_assert(circ);
+ tor_assert(log_cell_type_str);
+
+ /* Basic circuit state sanity checks. */
+ if (circ->base_.purpose != CIRCUIT_PURPOSE_OR) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting %s on non-OR circuit.", log_cell_type_str);
+ return 0;
+ }
+
+ if (circ->base_.n_chan) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting %s on non-edge circuit.", log_cell_type_str);
+ return 0;
+ }
+
+ /* Suitable. */
+ return 1;
+}
+
+/* Return True if circuit is suitable for being service-side intro circuit. */
+int
+hs_intro_circuit_is_suitable_for_establish_intro(const or_circuit_t *circ)
+{
+ return circuit_is_suitable_intro_point(circ, "ESTABLISH_INTRO");
+}
+
+/* We just received an ESTABLISH_INTRO cell in <b>circ</b>. Figure out of it's
+ * a legacy or a next gen cell, and pass it to the appropriate handler. */
+int
+hs_intro_received_establish_intro(or_circuit_t *circ, const uint8_t *request,
+ size_t request_len)
+{
+ tor_assert(circ);
+ tor_assert(request);
+
+ if (request_len == 0) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Empty ESTABLISH_INTRO cell.");
+ goto err;
+ }
+
+ /* Using the first byte of the cell, figure out the version of
+ * ESTABLISH_INTRO and pass it to the appropriate cell handler */
+ const uint8_t first_byte = request[0];
+ switch (first_byte) {
+ case HS_INTRO_AUTH_KEY_TYPE_LEGACY0:
+ case HS_INTRO_AUTH_KEY_TYPE_LEGACY1:
+ return rend_mid_establish_intro_legacy(circ, request, request_len);
+ case HS_INTRO_AUTH_KEY_TYPE_ED25519:
+ return handle_establish_intro(circ, request, request_len);
+ default:
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Unrecognized AUTH_KEY_TYPE %u.", first_byte);
+ goto err;
+ }
+
+ err:
+ circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
+ return -1;
+}
+
+/* Send an INTRODUCE_ACK cell onto the circuit <b>circ</b> with the status
+ * value in <b>status</b>. Depending on the status, it can be ACK or a NACK.
+ * Return 0 on success else a negative value on error which will close the
+ * circuit. */
+static int
+send_introduce_ack_cell(or_circuit_t *circ, hs_intro_ack_status_t status)
+{
+ int ret = -1;
+ uint8_t *encoded_cell = NULL;
+ ssize_t encoded_len, result_len;
+ trn_cell_introduce_ack_t *cell;
+ trn_cell_extension_t *ext;
+
+ tor_assert(circ);
+
+ /* Setup the INTRODUCE_ACK cell. We have no extensions so the N_EXTENSIONS
+ * field is set to 0 by default with a new object. */
+ cell = trn_cell_introduce_ack_new();
+ ret = trn_cell_introduce_ack_set_status(cell, status);
+ /* We have no cell extensions in an INTRODUCE_ACK cell. */
+ ext = trn_cell_extension_new();
+ trn_cell_extension_set_num(ext, 0);
+ trn_cell_introduce_ack_set_extensions(cell, ext);
+ /* A wrong status is a very bad code flow error as this value is controlled
+ * by the code in this file and not an external input. This means we use a
+ * code that is not known by the trunnel ABI. */
+ tor_assert(ret == 0);
+ /* Encode the payload. We should never fail to get the encoded length. */
+ encoded_len = trn_cell_introduce_ack_encoded_len(cell);
+ tor_assert(encoded_len > 0);
+ encoded_cell = tor_malloc_zero(encoded_len);
+ result_len = trn_cell_introduce_ack_encode(encoded_cell, encoded_len, cell);
+ tor_assert(encoded_len == result_len);
+
+ ret = relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ),
+ RELAY_COMMAND_INTRODUCE_ACK,
+ (char *) encoded_cell, encoded_len,
+ NULL);
+ /* On failure, the above function will close the circuit. */
+ trn_cell_introduce_ack_free(cell);
+ tor_free(encoded_cell);
+ return ret;
+}
+
+/* Validate a parsed INTRODUCE1 <b>cell</b>. Return 0 if valid or else a
+ * negative value for an invalid cell that should be NACKed. */
+STATIC int
+validate_introduce1_parsed_cell(const trn_cell_introduce1_t *cell)
+{
+ size_t legacy_key_id_len;
+ const uint8_t *legacy_key_id;
+
+ tor_assert(cell);
+
+ /* This code path SHOULD NEVER be reached if the cell is a legacy type so
+ * safety net here. The legacy ID must be zeroes in this case. */
+ legacy_key_id_len = trn_cell_introduce1_getlen_legacy_key_id(cell);
+ legacy_key_id = trn_cell_introduce1_getconstarray_legacy_key_id(cell);
+ if (BUG(!tor_mem_is_zero((char *) legacy_key_id, legacy_key_id_len))) {
+ goto invalid;
+ }
+
+ /* The auth key of an INTRODUCE1 should be of type ed25519 thus leading to a
+ * known fixed length as well. */
+ if (trn_cell_introduce1_get_auth_key_type(cell) !=
+ HS_INTRO_AUTH_KEY_TYPE_ED25519) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting invalid INTRODUCE1 cell auth key type. "
+ "Responding with NACK.");
+ goto invalid;
+ }
+ if (trn_cell_introduce1_get_auth_key_len(cell) != ED25519_PUBKEY_LEN ||
+ trn_cell_introduce1_getlen_auth_key(cell) != ED25519_PUBKEY_LEN) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting invalid INTRODUCE1 cell auth key length. "
+ "Responding with NACK.");
+ goto invalid;
+ }
+ if (trn_cell_introduce1_getlen_encrypted(cell) == 0) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting invalid INTRODUCE1 cell encrypted length. "
+ "Responding with NACK.");
+ goto invalid;
+ }
+
+ return 0;
+ invalid:
+ return -1;
+}
+
+/* We just received a non legacy INTRODUCE1 cell on <b>client_circ</b> with
+ * the payload in <b>request</b> of size <b>request_len</b>. Return 0 if
+ * everything went well, or -1 if an error occurred. This function is in charge
+ * of sending back an INTRODUCE_ACK cell and will close client_circ on error.
+ */
+STATIC int
+handle_introduce1(or_circuit_t *client_circ, const uint8_t *request,
+ size_t request_len)
+{
+ int ret = -1;
+ or_circuit_t *service_circ;
+ trn_cell_introduce1_t *parsed_cell;
+ hs_intro_ack_status_t status = HS_INTRO_ACK_STATUS_SUCCESS;
+
+ tor_assert(client_circ);
+ tor_assert(request);
+
+ /* Parse cell. Note that we can only parse the non encrypted section for
+ * which we'll use the authentication key to find the service introduction
+ * circuit and relay the cell on it. */
+ ssize_t cell_size = trn_cell_introduce1_parse(&parsed_cell, request,
+ request_len);
+ if (cell_size < 0) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+ "Rejecting %s INTRODUCE1 cell. Responding with NACK.",
+ cell_size == -1 ? "invalid" : "truncated");
+ /* Inform client that the INTRODUCE1 has a bad format. */
+ status = HS_INTRO_ACK_STATUS_BAD_FORMAT;
+ goto send_ack;
+ }
+
+ /* Once parsed validate the cell format. */
+ if (validate_introduce1_parsed_cell(parsed_cell) < 0) {
+ /* Inform client that the INTRODUCE1 has bad format. */
+ status = HS_INTRO_ACK_STATUS_BAD_FORMAT;
+ goto send_ack;
+ }
+
+ /* Find introduction circuit through our circuit map. */
+ {
+ ed25519_public_key_t auth_key;
+ get_auth_key_from_cell(&auth_key, RELAY_COMMAND_INTRODUCE1, parsed_cell);
+ service_circ = hs_circuitmap_get_intro_circ_v3_relay_side(&auth_key);
+ if (service_circ == NULL) {
+ char b64_key[ED25519_BASE64_LEN + 1];
+ ed25519_public_to_base64(b64_key, &auth_key);
+ log_info(LD_REND, "No intro circuit found for INTRODUCE1 cell "
+ "with auth key %s from circuit %" PRIu32 ". "
+ "Responding with NACK.",
+ safe_str(b64_key), client_circ->p_circ_id);
+ /* Inform the client that we don't know the requested service ID. */
+ status = HS_INTRO_ACK_STATUS_UNKNOWN_ID;
+ goto send_ack;
+ }
+ }
+
+ /* Relay the cell to the service on its intro circuit with an INTRODUCE2
+ * cell which is the same exact payload. */
+ if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(service_circ),
+ RELAY_COMMAND_INTRODUCE2,
+ (char *) request, request_len, NULL)) {
+ log_warn(LD_PROTOCOL, "Unable to send INTRODUCE2 cell to the service.");
+ /* Inform the client that we can't relay the cell. */
+ status = HS_INTRO_ACK_STATUS_CANT_RELAY;
+ goto send_ack;
+ }
+
+ /* Success! Send an INTRODUCE_ACK success status onto the client circuit. */
+ status = HS_INTRO_ACK_STATUS_SUCCESS;
+ ret = 0;
+
+ send_ack:
+ /* Send INTRODUCE_ACK or INTRODUCE_NACK to client */
+ if (send_introduce_ack_cell(client_circ, status) < 0) {
+ log_warn(LD_PROTOCOL, "Unable to send an INTRODUCE ACK status %d "
+ "to client.", status);
+ /* Circuit has been closed on failure of transmission. */
+ goto done;
+ }
- if (status != HS_INTRO_ACK_STATUS_SUCCESS) {
- /* We just sent a NACK that is a non success status code so close the
- * circuit because it's not useful to keep it open. Remember, a client can
- * only send one INTRODUCE1 cell on a circuit. */
- circuit_mark_for_close(TO_CIRCUIT(client_circ), END_CIRC_REASON_INTERNAL);
- }
+ done:
+ trn_cell_introduce1_free(parsed_cell);
+ return ret;
+}
+
+/* Identify if the encoded cell we just received is a legacy one or not. The
+ * <b>request</b> should be at least DIGEST_LEN bytes long. */
+STATIC int
+introduce1_cell_is_legacy(const uint8_t *request)
+{
+ tor_assert(request);
+
+ /* If the first 20 bytes of the cell (DIGEST_LEN) are NOT zeroes, it
+ * indicates a legacy cell (v2). */
+ if (!tor_mem_is_zero((const char *) request, DIGEST_LEN)) {
+ /* Legacy cell. */
+ return 1;
+ }
+ /* Not a legacy cell. */
+ return 0;
+}
+
+/* Return true iff the circuit <b>circ</b> is suitable for receiving an
+ * INTRODUCE1 cell. */
+STATIC int
+circuit_is_suitable_for_introduce1(const or_circuit_t *circ)
+{
+ tor_assert(circ);
+
+ /* Is this circuit an intro point circuit? */
+ if (!circuit_is_suitable_intro_point(circ, "INTRODUCE1")) {
+ return 0;
+ }
+
+ if (circ->already_received_introduce1) {
+ log_fn(LOG_PROTOCOL_WARN, LD_REND,
+ "Blocking multiple introductions on the same circuit. "
+ "Someone might be trying to attack a hidden service through "
+ "this relay.");
+ return 0;
+ }
+
+ return 1;
+}
+
+/* We just received an INTRODUCE1 cell on <b>circ</b>. Figure out which type
+ * it is and pass it to the appropriate handler. Return 0 on success else a
+ * negative value and the circuit is closed. */
+int
+hs_intro_received_introduce1(or_circuit_t *circ, const uint8_t *request,
+ size_t request_len)
+{
+ int ret;
+
+ tor_assert(circ);
+ tor_assert(request);
+
+ /* A cell that can't hold a DIGEST_LEN is invalid as we need to check if
+ * it's a legacy cell or not using the first DIGEST_LEN bytes. */
+ if (request_len < DIGEST_LEN) {
+ log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, "Invalid INTRODUCE1 cell length.");
+ goto err;
+ }
+
+ /* Make sure we have a circuit that can have an INTRODUCE1 cell on it. */
+ if (!circuit_is_suitable_for_introduce1(circ)) {
+ /* We do not send a NACK because the circuit is not suitable for any kind
+ * of response or transmission as it's a violation of the protocol. */
+ goto err;
+ }
+ /* Mark the circuit that we got this cell. None are allowed after this as a
+ * DoS mitigation since one circuit with one client can hammer a service. */
+ circ->already_received_introduce1 = 1;
+
+ /* We are sure here to have at least DIGEST_LEN bytes. */
+ if (introduce1_cell_is_legacy(request)) {
+ /* Handle a legacy cell. */
+ ret = rend_mid_introduce_legacy(circ, request, request_len);
+ } else {
+ /* Handle a non legacy cell. */
+ ret = handle_introduce1(circ, request, request_len);
+ }
+ return ret;
+
+ err:
+ circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
+ return -1;
+}
+
+/* Clear memory allocated by the given intropoint object ip (but don't free the
+ * object itself). */
+void
+hs_intropoint_clear(hs_intropoint_t *ip)
+{
+ if (ip == NULL) {
+ return;
+ }
+ tor_cert_free(ip->auth_key_cert);
+ SMARTLIST_FOREACH(ip->link_specifiers, hs_desc_link_specifier_t *, ls,
+ hs_desc_link_specifier_free(ls));
+ smartlist_free(ip->link_specifiers);
+ memset(ip, 0, sizeof(hs_intropoint_t));
+}
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