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prop224: Add a function to find an intro point by legacy ID

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The client needs to find the right intro point object from the circuit
identity digest it is opened to. This new function does that.

Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2017-08-22 14:51:27 -04:00
parent 7c543412fc
commit a16627db1f
1 changed files with 45 additions and 19 deletions
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64
src/or/hs_client.c
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@ -214,6 +214,42 @@ find_desc_intro_point_by_ident(const hs_ident_circuit_t *ident,
return intro_point;
}
/* Find a descriptor intro point object from the descriptor object desc that
* matches the given legacy identity digest in legacy_id. Return NULL if not
* found. */
static hs_desc_intro_point_t *
find_desc_intro_point_by_legacy_id(const char *legacy_id,
const hs_descriptor_t *desc)
{
hs_desc_intro_point_t *ret_ip = NULL;
tor_assert(legacy_id);
tor_assert(desc);
/* We will go over every intro point and try to find which one is linked to
* that circuit. Those lists are small so it's not that expensive. */
SMARTLIST_FOREACH_BEGIN(desc->encrypted_data.intro_points,
hs_desc_intro_point_t *, ip) {
SMARTLIST_FOREACH_BEGIN(ip->link_specifiers,
const hs_desc_link_specifier_t *, lspec) {
/* Not all tor node have an ed25519 identity key so we still rely on the
* legacy identity digest. */
if (lspec->type != LS_LEGACY_ID) {
continue;
}
if (fast_memneq(legacy_id, lspec->u.legacy_id, DIGEST_LEN)) {
break;
}
/* Found it. */
ret_ip = ip;
goto end;
} SMARTLIST_FOREACH_END(lspec);
} SMARTLIST_FOREACH_END(ip);
end:
return ret_ip;
}
/* Send an INTRODUCE1 cell along the intro circuit and populate the rend
* circuit identifier with the needed key material for the e2e encryption.
* Return 0 on success, -1 if there is a transient error such that an action
@ -319,6 +355,7 @@ static void
setup_intro_circ_auth_key(origin_circuit_t *circ)
{
const hs_descriptor_t *desc;
const hs_desc_intro_point_t *ip;
tor_assert(circ);
@ -330,25 +367,14 @@ setup_intro_circ_auth_key(origin_circuit_t *circ)
/* We will go over every intro point and try to find which one is linked to
* that circuit. Those lists are small so it's not that expensive. */
SMARTLIST_FOREACH_BEGIN(desc->encrypted_data.intro_points,
const hs_desc_intro_point_t *, ip) {
SMARTLIST_FOREACH_BEGIN(ip->link_specifiers,
const hs_desc_link_specifier_t *, lspec) {
/* Not all tor node have an ed25519 identity key so we still rely on the
* legacy identity digest. */
if (lspec->type != LS_LEGACY_ID) {
continue;
}
if (fast_memneq(circ->build_state->chosen_exit->identity_digest,
lspec->u.legacy_id, DIGEST_LEN)) {
break;
}
/* We got it, copy its authentication key to the identifier. */
ed25519_pubkey_copy(&circ->hs_ident->intro_auth_pk,
&ip->auth_key_cert->signed_key);
goto end;
} SMARTLIST_FOREACH_END(lspec);
} SMARTLIST_FOREACH_END(ip);
ip = find_desc_intro_point_by_legacy_id(
circ->build_state->chosen_exit->identity_digest, desc);
if (ip) {
/* We got it, copy its authentication key to the identifier. */
ed25519_pubkey_copy(&circ->hs_ident->intro_auth_pk,
&ip->auth_key_cert->signed_key);
goto end;
}
/* Reaching this point means we didn't find any intro point for this circuit
* which is not suppose to happen. */