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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/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;
}
/** 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;
uint32_t cur = 0; /* Current IPv4 address. */
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 */
cur = get_last_resolved_addr();
if (cur ||
resolve_my_address(LOG_INFO, options, &cur, NULL, NULL) >= 0) {
/* We're all set -- we already know our address. Great. */
tor_addr_from_ipv4h(&last_guessed_ip, cur); /* store it in case we
need it later */
return;
}
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))
{
/* First, check the cached output from resolve_my_address(). */
*addr = get_last_resolved_addr();
if (*addr)
return 0;
/* Second, consider doing a resolve attempt right here. */
if (!cache_only) {
if (resolve_my_address(LOG_INFO, options, addr, NULL, NULL) >= 0) {
log_info(LD_CONFIG,"Success: chose address '%s'.", fmt_addr32(*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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