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/* Copyright (c) 2001-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file relay_find_addr.c
* \brief Implement mechanism for a relay to find its address.
**/
#include "core/or/or.h"
#include "app/config/config.h"
#include "app/config/resolve_addr.h"
#include "core/mainloop/mainloop.h"
#include "feature/control/control_events.h"
#include "feature/dircommon/dir_connection_st.h"
#include "feature/nodelist/dirlist.h"
#include "feature/relay/relay_find_addr.h"
#include "feature/relay/router.h"
#include "feature/relay/routermode.h"
/** The most recently guessed value of our IP address, based on directory
* headers. */
static tor_addr_t last_guessed_ip = TOR_ADDR_NULL;
/** We failed to resolve our address locally, but we'd like to build
* a descriptor and publish / test reachability. If we have a guess
* about our address based on directory headers, answer it and return
* 0; else return -1. */
static int
router_guess_address_from_dir_headers(uint32_t *guess)
{
if (!tor_addr_is_null(&last_guessed_ip)) {
*guess = tor_addr_to_ipv4h(&last_guessed_ip);
return 0;
}
return -1;
}
/** Consider the address suggestion suggested_addr as a possible one to use as
* our address.
*
* This is called when a valid NETINFO cell is recevied containing a candidate
* for our address.
*
* The suggested address is ignored if it does NOT come from a trusted source.
* At the moment, we only look a trusted directory authorities.
*
* The suggested address is ignored if it is internal or it is the same as the
* given peer_addr which is the address from the endpoint that sent the
* NETINFO cell.
*
* The suggested address is set in our suggested address cache if everything
* passes. */
void
relay_address_new_suggestion(const tor_addr_t *suggested_addr,
const tor_addr_t *peer_addr,
const char *identity_digest)
{
const or_options_t *options = get_options();
tor_assert(suggested_addr);
tor_assert(peer_addr);
tor_assert(identity_digest);
/* This should never be called on a non Tor relay. */
if (BUG(!server_mode(options))) {
return;
}
/* Is the peer a trusted source? Ignore anything coming from non trusted
* source. In this case, we only look at trusted directory authorities. */
if (!router_addr_is_trusted_dir(peer_addr) ||
!router_digest_is_trusted_dir(identity_digest)) {
return;
}
/* Ignore a suggestion that is an internal address or the same as the one
* the peer address. */
if (tor_addr_is_internal(suggested_addr, 0)) {
/* Do not believe anyone who says our address is internal. */
return;
}
if (tor_addr_eq(suggested_addr, peer_addr)) {
/* Do not believe anyone who says our address is their address. */
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"A relay endpoint %s is telling us that their address is ours.",
fmt_addr(peer_addr));
return;
}
/* Save the suggestion in our cache. */
resolved_addr_set_suggested(suggested_addr);
}
/** A directory server <b>d_conn</b> told us our IP address is
* <b>suggestion</b>.
* If this address is different from the one we think we are now, and
* if our computer doesn't actually know its IP address, then switch. */
void
router_new_address_suggestion(const char *suggestion,
const dir_connection_t *d_conn)
{
tor_addr_t addr, my_addr, last_resolved_addr;
const or_options_t *options = get_options();
/* first, learn what the IP address actually is */
if (tor_addr_parse(&addr, suggestion) == -1) {
log_debug(LD_DIR, "Malformed X-Your-Address-Is header %s. Ignoring.",
escaped(suggestion));
return;
}
log_debug(LD_DIR, "Got X-Your-Address-Is: %s.", suggestion);
if (!server_mode(options)) {
tor_addr_copy(&last_guessed_ip, &addr);
return;
}
/* XXXX ipv6 */
resolved_addr_get_last(AF_INET, &last_resolved_addr);
if (!tor_addr_is_null(&last_resolved_addr)) {
/* Lets use this one. */
tor_addr_copy(&last_guessed_ip, &last_resolved_addr);
return;
}
/* Attempt to find our address. */
if (find_my_address(options, AF_INET, LOG_INFO, &my_addr, NULL, NULL)) {
/* We're all set -- we already know our address. Great. */
tor_addr_copy(&last_guessed_ip, &my_addr); /* store it in case we
need it later */
return;
}
/* Consider the suggestion from the directory. */
if (tor_addr_is_internal(&addr, 0)) {
/* Don't believe anybody who says our IP is, say, 127.0.0.1. */
return;
}
if (tor_addr_eq(&d_conn->base_.addr, &addr)) {
/* Don't believe anybody who says our IP is their IP. */
log_debug(LD_DIR, "A directory server told us our IP address is %s, "
"but they are just reporting their own IP address. Ignoring.",
suggestion);
return;
}
/* Okay. We can't resolve our own address, and X-Your-Address-Is is giving
* us an answer different from what we had the last time we managed to
* resolve it. */
if (!tor_addr_eq(&last_guessed_ip, &addr)) {
control_event_server_status(LOG_NOTICE,
"EXTERNAL_ADDRESS ADDRESS=%s METHOD=DIRSERV",
suggestion);
log_addr_has_changed(LOG_NOTICE, &last_guessed_ip, &addr,
d_conn->base_.address);
ip_address_changed(0);
tor_addr_copy(&last_guessed_ip, &addr); /* router_rebuild_descriptor()
will fetch it */
}
}
/** Make a current best guess at our address, either because
* it's configured in torrc, or because we've learned it from
* dirserver headers. Place the answer in *<b>addr</b> and return
* 0 on success, else return -1 if we have no guess.
*
* If <b>cache_only</b> is true, just return any cached answers, and
* don't try to get any new answers.
*/
MOCK_IMPL(int,
router_pick_published_address, (const or_options_t *options, uint32_t *addr,
int cache_only))
{
tor_addr_t last_resolved_addr;
/* First, check the cached output from find_my_address(). */
resolved_addr_get_last(AF_INET, &last_resolved_addr);
if (!tor_addr_is_null(&last_resolved_addr)) {
*addr = tor_addr_to_ipv4h(&last_resolved_addr);
return 0;
}
/* Second, consider doing a resolve attempt right here. */
if (!cache_only) {
tor_addr_t my_addr;
if (find_my_address(options, AF_INET, LOG_INFO, &my_addr, NULL, NULL)) {
log_info(LD_CONFIG,"Success: chose address '%s'.", fmt_addr(&my_addr));
*addr = tor_addr_to_ipv4h(&my_addr);
return 0;
}
}
/* Third, check the cached output from router_new_address_suggestion(). */
if (router_guess_address_from_dir_headers(addr) >= 0)
return 0;
/* We have no useful cached answers. Return failure. */
return -1;
}
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