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circuitbuild: Allow relays to send IPv6 extend cells

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Allow relays and bridges to send IPv4 or IPv6 extend cells.
But keep restricting clients to IPv4 extend cells, because sending IPv6
extend cells would be an obvious version distinguisher.

Part of 33222.
This commit is contained in:
teor 2020-04-30 22:55:52 +10:00
parent 4969dee102
commit 4a36dfebee
1 changed files with 25 additions and 6 deletions
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31
src/core/or/circuitbuild.c
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@ -1075,14 +1075,25 @@ circuit_send_intermediate_onion_skin(origin_circuit_t *circ,
crypt_path_t *hop)
{
int len;
int family = tor_addr_family(&hop->extend_info->addr);
extend_cell_t ec;
memset(&ec, 0, sizeof(ec));
log_debug(LD_CIRC,"starting to send subsequent skin.");
if (tor_addr_family(&hop->extend_info->addr) != AF_INET) {
log_warn(LD_BUG, "Trying to extend to a non-IPv4 address.");
return - END_CIRC_REASON_INTERNAL;
/* Relays and bridges can send IPv6 extends. But for clients, it's an
* obvious version distinguisher. */
if (server_mode(get_options())) {
if (family != AF_INET && family != AF_INET6) {
log_warn(LD_BUG, "Server trying to extend to an invalid address "
"family.");
return - END_CIRC_REASON_INTERNAL;
}
} else {
if (family != AF_INET) {
log_warn(LD_BUG, "Client trying to extend to a non-IPv4 address.");
return - END_CIRC_REASON_INTERNAL;
}
}
circuit_pick_extend_handshake(&ec.cell_type,
@ -1090,9 +1101,17 @@ circuit_send_intermediate_onion_skin(origin_circuit_t *circ,
&ec.create_cell.handshake_type,
hop->extend_info);
tor_addr_copy(&ec.orport_ipv4.addr, &hop->extend_info->addr);
ec.orport_ipv4.port = hop->extend_info->port;
tor_addr_make_unspec(&ec.orport_ipv6.addr);
/* At the moment, extend_info only has one ORPort address. We'll add a
* second address in #34069, to support dual-stack extend cells. */
if (family == AF_INET) {
tor_addr_copy(&ec.orport_ipv4.addr, &hop->extend_info->addr);
ec.orport_ipv4.port = hop->extend_info->port;
tor_addr_make_unspec(&ec.orport_ipv6.addr);
} else {
tor_addr_copy(&ec.orport_ipv6.addr, &hop->extend_info->addr);
ec.orport_ipv6.port = hop->extend_info->port;
tor_addr_make_unspec(&ec.orport_ipv4.addr);
}
memcpy(ec.node_id, hop->extend_info->identity_digest, DIGEST_LEN);
/* Set the ED25519 identity too -- it will only get included
* in the extend2 cell if we're configured to use it, though. */