2200 lines
75 KiB
C
2200 lines
75 KiB
C
/* Copyright (c) 2003-2004, Roger Dingledine.
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* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
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* Copyright (c) 2007-2013, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file dns.c
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* \brief Implements a local cache for DNS results for Tor servers.
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* This is implemented as a wrapper around Adam Langley's eventdns.c code.
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* (We can't just use gethostbyname() and friends because we really need to
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* be nonblocking.)
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**/
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#include "or.h"
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#include "circuitlist.h"
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#include "circuituse.h"
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#include "config.h"
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#include "connection.h"
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#include "connection_edge.h"
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#include "control.h"
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#include "dns.h"
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#include "main.h"
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#include "policies.h"
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#include "relay.h"
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#include "router.h"
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#include "ht.h"
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#ifdef HAVE_EVENT2_DNS_H
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#include <event2/event.h>
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#include <event2/dns.h>
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#else
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#include <event.h>
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#include "eventdns.h"
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#ifndef HAVE_EVDNS_SET_DEFAULT_OUTGOING_BIND_ADDRESS
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#define HAVE_EVDNS_SET_DEFAULT_OUTGOING_BIND_ADDRESS
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#endif
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#endif
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#ifndef HAVE_EVENT2_DNS_H
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struct evdns_base;
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struct evdns_request;
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#define evdns_base_new(x,y) tor_malloc(1)
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#define evdns_base_clear_nameservers_and_suspend(base) \
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evdns_clear_nameservers_and_suspend()
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#define evdns_base_search_clear(base) evdns_search_clear()
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#define evdns_base_set_default_outgoing_bind_address(base, a, len) \
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evdns_set_default_outgoing_bind_address((a),(len))
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#define evdns_base_resolv_conf_parse(base, options, fname) \
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evdns_resolv_conf_parse((options), (fname))
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#define evdns_base_count_nameservers(base) \
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evdns_count_nameservers()
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#define evdns_base_resume(base) \
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evdns_resume()
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#define evdns_base_config_windows_nameservers(base) \
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evdns_config_windows_nameservers()
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#define evdns_base_set_option_(base, opt, val) \
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evdns_set_option((opt),(val),DNS_OPTIONS_ALL)
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/* Note: our internal eventdns.c, plus Libevent 1.4, used a 1 return to
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* signify failure to launch a resolve. Libevent 2.0 uses a -1 return to
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* signify a failure on a resolve, though if we're on Libevent 2.0, we should
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* have event2/dns.h and never hit these macros. Regardless, 0 is success. */
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#define evdns_base_resolve_ipv4(base, addr, options, cb, ptr) \
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((evdns_resolve_ipv4((addr), (options), (cb), (ptr))!=0) \
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? NULL : ((void*)1))
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#define evdns_base_resolve_ipv6(base, addr, options, cb, ptr) \
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((evdns_resolve_ipv6((addr), (options), (cb), (ptr))!=0) \
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? NULL : ((void*)1))
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#define evdns_base_resolve_reverse(base, addr, options, cb, ptr) \
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((evdns_resolve_reverse((addr), (options), (cb), (ptr))!=0) \
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? NULL : ((void*)1))
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#define evdns_base_resolve_reverse_ipv6(base, addr, options, cb, ptr) \
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((evdns_resolve_reverse_ipv6((addr), (options), (cb), (ptr))!=0) \
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? NULL : ((void*)1))
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#elif defined(LIBEVENT_VERSION_NUMBER) && LIBEVENT_VERSION_NUMBER < 0x02000303
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#define evdns_base_set_option_(base, opt, val) \
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evdns_base_set_option((base), (opt),(val),DNS_OPTIONS_ALL)
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#else
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#define evdns_base_set_option_ evdns_base_set_option
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#endif
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/** Longest hostname we're willing to resolve. */
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#define MAX_ADDRESSLEN 256
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/** How long will we wait for an answer from the resolver before we decide
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* that the resolver is wedged? */
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#define RESOLVE_MAX_TIMEOUT 300
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/** Our evdns_base; this structure handles all our name lookups. */
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static struct evdns_base *the_evdns_base = NULL;
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/** Have we currently configured nameservers with eventdns? */
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static int nameservers_configured = 0;
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/** Did our most recent attempt to configure nameservers with eventdns fail? */
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static int nameserver_config_failed = 0;
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/** What was the resolv_conf fname we last used when configuring the
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* nameservers? Used to check whether we need to reconfigure. */
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static char *resolv_conf_fname = NULL;
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/** What was the mtime on the resolv.conf file we last used when configuring
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* the nameservers? Used to check whether we need to reconfigure. */
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static time_t resolv_conf_mtime = 0;
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/** Linked list of connections waiting for a DNS answer. */
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typedef struct pending_connection_t {
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edge_connection_t *conn;
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struct pending_connection_t *next;
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} pending_connection_t;
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/** Value of 'magic' field for cached_resolve_t. Used to try to catch bad
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* pointers and memory stomping. */
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#define CACHED_RESOLVE_MAGIC 0x1234F00D
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/* Possible states for a cached resolve_t */
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/** We are waiting for the resolver system to tell us an answer here.
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* When we get one, or when we time out, the state of this cached_resolve_t
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* will become "DONE" and we'll possibly add a CACHED
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* entry. This cached_resolve_t will be in the hash table so that we will
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* know not to launch more requests for this addr, but rather to add more
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* connections to the pending list for the addr. */
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#define CACHE_STATE_PENDING 0
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/** This used to be a pending cached_resolve_t, and we got an answer for it.
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* Now we're waiting for this cached_resolve_t to expire. This should
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* have no pending connections, and should not appear in the hash table. */
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#define CACHE_STATE_DONE 1
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/** We are caching an answer for this address. This should have no pending
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* connections, and should appear in the hash table. */
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#define CACHE_STATE_CACHED 2
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/** @name status values for a single DNS request.
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*
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* @{ */
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/** The DNS request is in progress. */
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#define RES_STATUS_INFLIGHT 1
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/** The DNS request finished and gave an answer */
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#define RES_STATUS_DONE_OK 2
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/** The DNS request finished and gave an error */
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#define RES_STATUS_DONE_ERR 3
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/**@}*/
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/** A DNS request: possibly completed, possibly pending; cached_resolve
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* structs are stored at the OR side in a hash table, and as a linked
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* list from oldest to newest.
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*/
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typedef struct cached_resolve_t {
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HT_ENTRY(cached_resolve_t) node;
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uint32_t magic; /**< Must be CACHED_RESOLVE_MAGIC */
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char address[MAX_ADDRESSLEN]; /**< The hostname to be resolved. */
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union {
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uint32_t addr_ipv4; /**< IPv4 addr for <b>address</b>, if successful.
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* (In host order.) */
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int err_ipv4; /**< One of DNS_ERR_*, if IPv4 lookup failed. */
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} result_ipv4; /**< Outcome of IPv4 lookup */
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union {
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struct in6_addr addr_ipv6; /**< IPv6 addr for <b>address</b>, if
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* successful */
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int err_ipv6; /**< One of DNS_ERR_*, if IPv6 lookup failed. */
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} result_ipv6; /**< Outcome of IPv6 lookup, if any */
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union {
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char *hostname; /** A hostname, if PTR lookup happened successfully*/
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int err_hostname; /** One of DNS_ERR_*, if PTR lookup failed. */
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} result_ptr;
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/** @name Status fields
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*
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* These take one of the RES_STATUS_* values, depending on the state
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* of the corresponding lookup.
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*
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* @{ */
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unsigned int res_status_ipv4 : 2;
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unsigned int res_status_ipv6 : 2;
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unsigned int res_status_hostname : 2;
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/**@}*/
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uint8_t state; /**< Is this cached entry pending/done/informative? */
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time_t expire; /**< Remove items from cache after this time. */
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uint32_t ttl_ipv4; /**< What TTL did the nameserver tell us? */
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uint32_t ttl_ipv6; /**< What TTL did the nameserver tell us? */
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uint32_t ttl_hostname; /**< What TTL did the nameserver tell us? */
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/** Connections that want to know when we get an answer for this resolve. */
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pending_connection_t *pending_connections;
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/** Position of this element in the heap*/
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int minheap_idx;
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} cached_resolve_t;
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static void purge_expired_resolves(time_t now);
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static void dns_found_answer(const char *address, uint8_t query_type,
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int dns_answer,
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const tor_addr_t *addr,
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const char *hostname,
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uint32_t ttl);
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static void send_resolved_cell(edge_connection_t *conn, uint8_t answer_type,
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const cached_resolve_t *resolve);
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static int launch_resolve(cached_resolve_t *resolve);
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static void add_wildcarded_test_address(const char *address);
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static int configure_nameservers(int force);
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static int answer_is_wildcarded(const char *ip);
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static int dns_resolve_impl(edge_connection_t *exitconn, int is_resolve,
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or_circuit_t *oncirc, char **resolved_to_hostname,
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int *made_connection_pending_out,
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cached_resolve_t **resolve_out);
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static int set_exitconn_info_from_resolve(edge_connection_t *exitconn,
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const cached_resolve_t *resolve,
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char **hostname_out);
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static int evdns_err_is_transient(int err);
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static void inform_pending_connections(cached_resolve_t *resolve);
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static void make_pending_resolve_cached(cached_resolve_t *cached);
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#ifdef DEBUG_DNS_CACHE
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static void assert_cache_ok_(void);
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#define assert_cache_ok() assert_cache_ok_()
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#else
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#define assert_cache_ok() STMT_NIL
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#endif
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static void assert_resolve_ok(cached_resolve_t *resolve);
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/** Hash table of cached_resolve objects. */
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static HT_HEAD(cache_map, cached_resolve_t) cache_root;
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/** Global: how many IPv6 requests have we made in all? */
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static uint64_t n_ipv6_requests_made = 0;
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/** Global: how many IPv6 requests have timed out? */
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static uint64_t n_ipv6_timeouts = 0;
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/** Global: Do we think that IPv6 DNS is broken? */
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static int dns_is_broken_for_ipv6 = 0;
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/** Function to compare hashed resolves on their addresses; used to
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* implement hash tables. */
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static INLINE int
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cached_resolves_eq(cached_resolve_t *a, cached_resolve_t *b)
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{
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/* make this smarter one day? */
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assert_resolve_ok(a); // Not b; b may be just a search.
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return !strncmp(a->address, b->address, MAX_ADDRESSLEN);
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}
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/** Hash function for cached_resolve objects */
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static INLINE unsigned int
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cached_resolve_hash(cached_resolve_t *a)
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{
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return ht_string_hash(a->address);
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}
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HT_PROTOTYPE(cache_map, cached_resolve_t, node, cached_resolve_hash,
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cached_resolves_eq)
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HT_GENERATE(cache_map, cached_resolve_t, node, cached_resolve_hash,
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cached_resolves_eq, 0.6, malloc, realloc, free)
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/** Initialize the DNS cache. */
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static void
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init_cache_map(void)
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{
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HT_INIT(cache_map, &cache_root);
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}
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/** Helper: called by eventdns when eventdns wants to log something. */
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static void
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evdns_log_cb(int warn, const char *msg)
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{
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const char *cp;
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static int all_down = 0;
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int severity = warn ? LOG_WARN : LOG_INFO;
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if (!strcmpstart(msg, "Resolve requested for") &&
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get_options()->SafeLogging) {
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log_info(LD_EXIT, "eventdns: Resolve requested.");
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return;
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} else if (!strcmpstart(msg, "Search: ")) {
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return;
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}
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if (!strcmpstart(msg, "Nameserver ") && (cp=strstr(msg, " has failed: "))) {
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char *ns = tor_strndup(msg+11, cp-(msg+11));
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const char *err = strchr(cp, ':')+2;
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tor_assert(err);
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/* Don't warn about a single failed nameserver; we'll warn with 'all
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* nameservers have failed' if we're completely out of nameservers;
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* otherwise, the situation is tolerable. */
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severity = LOG_INFO;
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control_event_server_status(LOG_NOTICE,
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"NAMESERVER_STATUS NS=%s STATUS=DOWN ERR=%s",
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ns, escaped(err));
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tor_free(ns);
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} else if (!strcmpstart(msg, "Nameserver ") &&
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(cp=strstr(msg, " is back up"))) {
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char *ns = tor_strndup(msg+11, cp-(msg+11));
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severity = (all_down && warn) ? LOG_NOTICE : LOG_INFO;
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all_down = 0;
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control_event_server_status(LOG_NOTICE,
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"NAMESERVER_STATUS NS=%s STATUS=UP", ns);
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tor_free(ns);
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} else if (!strcmp(msg, "All nameservers have failed")) {
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control_event_server_status(LOG_WARN, "NAMESERVER_ALL_DOWN");
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all_down = 1;
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}
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tor_log(severity, LD_EXIT, "eventdns: %s", msg);
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}
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/** Helper: passed to eventdns.c as a callback so it can generate random
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* numbers for transaction IDs and 0x20-hack coding. */
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static void
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dns_randfn_(char *b, size_t n)
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{
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crypto_rand(b,n);
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}
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/** Initialize the DNS subsystem; called by the OR process. */
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int
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dns_init(void)
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{
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init_cache_map();
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evdns_set_random_bytes_fn(dns_randfn_);
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if (server_mode(get_options())) {
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int r = configure_nameservers(1);
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return r;
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}
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return 0;
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}
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/** Called when DNS-related options change (or may have changed). Returns -1
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* on failure, 0 on success. */
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int
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dns_reset(void)
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{
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const or_options_t *options = get_options();
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if (! server_mode(options)) {
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if (!the_evdns_base) {
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if (!(the_evdns_base = evdns_base_new(tor_libevent_get_base(), 0))) {
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log_err(LD_BUG, "Couldn't create an evdns_base");
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return -1;
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}
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}
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evdns_base_clear_nameservers_and_suspend(the_evdns_base);
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evdns_base_search_clear(the_evdns_base);
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nameservers_configured = 0;
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tor_free(resolv_conf_fname);
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resolv_conf_mtime = 0;
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} else {
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if (configure_nameservers(0) < 0) {
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return -1;
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}
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}
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return 0;
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}
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/** Return true iff the most recent attempt to initialize the DNS subsystem
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* failed. */
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int
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has_dns_init_failed(void)
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{
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return nameserver_config_failed;
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}
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/** Helper: Given a TTL from a DNS response, determine what TTL to give the
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* OP that asked us to resolve it. */
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uint32_t
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dns_clip_ttl(uint32_t ttl)
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{
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if (ttl < MIN_DNS_TTL)
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return MIN_DNS_TTL;
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else if (ttl > MAX_DNS_TTL)
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return MAX_DNS_TTL;
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else
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return ttl;
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}
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/** Helper: Given a TTL from a DNS response, determine how long to hold it in
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* our cache. */
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static uint32_t
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dns_get_expiry_ttl(uint32_t ttl)
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{
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if (ttl < MIN_DNS_TTL)
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return MIN_DNS_TTL;
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else if (ttl > MAX_DNS_ENTRY_AGE)
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return MAX_DNS_ENTRY_AGE;
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else
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return ttl;
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}
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/** Helper: free storage held by an entry in the DNS cache. */
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static void
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free_cached_resolve_(cached_resolve_t *r)
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{
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if (!r)
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return;
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while (r->pending_connections) {
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pending_connection_t *victim = r->pending_connections;
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r->pending_connections = victim->next;
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tor_free(victim);
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}
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if (r->res_status_hostname == RES_STATUS_DONE_OK)
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tor_free(r->result_ptr.hostname);
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r->magic = 0xFF00FF00;
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tor_free(r);
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}
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/** Compare two cached_resolve_t pointers by expiry time, and return
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* less-than-zero, zero, or greater-than-zero as appropriate. Used for
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* the priority queue implementation. */
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static int
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compare_cached_resolves_by_expiry_(const void *_a, const void *_b)
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{
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const cached_resolve_t *a = _a, *b = _b;
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if (a->expire < b->expire)
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return -1;
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else if (a->expire == b->expire)
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return 0;
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else
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return 1;
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}
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/** Priority queue of cached_resolve_t objects to let us know when they
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* will expire. */
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static smartlist_t *cached_resolve_pqueue = NULL;
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static void
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cached_resolve_add_answer(cached_resolve_t *resolve,
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int query_type,
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int dns_result,
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const tor_addr_t *answer_addr,
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const char *answer_hostname,
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uint32_t ttl)
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{
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if (query_type == DNS_PTR) {
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if (resolve->res_status_hostname != RES_STATUS_INFLIGHT)
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return;
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if (dns_result == DNS_ERR_NONE && answer_hostname) {
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resolve->result_ptr.hostname = tor_strdup(answer_hostname);
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resolve->res_status_hostname = RES_STATUS_DONE_OK;
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} else {
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resolve->result_ptr.err_hostname = dns_result;
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resolve->res_status_hostname = RES_STATUS_DONE_ERR;
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}
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resolve->ttl_hostname = ttl;
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} else if (query_type == DNS_IPv4_A) {
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if (resolve->res_status_ipv4 != RES_STATUS_INFLIGHT)
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return;
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if (dns_result == DNS_ERR_NONE && answer_addr &&
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tor_addr_family(answer_addr) == AF_INET) {
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resolve->result_ipv4.addr_ipv4 = tor_addr_to_ipv4h(answer_addr);
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resolve->res_status_ipv4 = RES_STATUS_DONE_OK;
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} else {
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resolve->result_ipv4.err_ipv4 = dns_result;
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resolve->res_status_ipv4 = RES_STATUS_DONE_ERR;
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}
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|
|
} else if (query_type == DNS_IPv6_AAAA) {
|
|
if (resolve->res_status_ipv6 != RES_STATUS_INFLIGHT)
|
|
return;
|
|
|
|
if (dns_result == DNS_ERR_NONE && answer_addr &&
|
|
tor_addr_family(answer_addr) == AF_INET6) {
|
|
memcpy(&resolve->result_ipv6.addr_ipv6,
|
|
tor_addr_to_in6(answer_addr),
|
|
sizeof(struct in6_addr));
|
|
resolve->res_status_ipv6 = RES_STATUS_DONE_OK;
|
|
} else {
|
|
resolve->result_ipv6.err_ipv6 = dns_result;
|
|
resolve->res_status_ipv6 = RES_STATUS_DONE_ERR;
|
|
}
|
|
}
|
|
}
|
|
|
|
/** Return true iff there are no in-flight requests for <b>resolve</b>. */
|
|
static int
|
|
cached_resolve_have_all_answers(const cached_resolve_t *resolve)
|
|
{
|
|
return (resolve->res_status_ipv4 != RES_STATUS_INFLIGHT &&
|
|
resolve->res_status_ipv6 != RES_STATUS_INFLIGHT &&
|
|
resolve->res_status_hostname != RES_STATUS_INFLIGHT);
|
|
}
|
|
|
|
/** Set an expiry time for a cached_resolve_t, and add it to the expiry
|
|
* priority queue */
|
|
static void
|
|
set_expiry(cached_resolve_t *resolve, time_t expires)
|
|
{
|
|
tor_assert(resolve && resolve->expire == 0);
|
|
if (!cached_resolve_pqueue)
|
|
cached_resolve_pqueue = smartlist_new();
|
|
resolve->expire = expires;
|
|
smartlist_pqueue_add(cached_resolve_pqueue,
|
|
compare_cached_resolves_by_expiry_,
|
|
STRUCT_OFFSET(cached_resolve_t, minheap_idx),
|
|
resolve);
|
|
}
|
|
|
|
/** Free all storage held in the DNS cache and related structures. */
|
|
void
|
|
dns_free_all(void)
|
|
{
|
|
cached_resolve_t **ptr, **next, *item;
|
|
assert_cache_ok();
|
|
if (cached_resolve_pqueue) {
|
|
SMARTLIST_FOREACH(cached_resolve_pqueue, cached_resolve_t *, res,
|
|
{
|
|
if (res->state == CACHE_STATE_DONE)
|
|
free_cached_resolve_(res);
|
|
});
|
|
}
|
|
for (ptr = HT_START(cache_map, &cache_root); ptr != NULL; ptr = next) {
|
|
item = *ptr;
|
|
next = HT_NEXT_RMV(cache_map, &cache_root, ptr);
|
|
free_cached_resolve_(item);
|
|
}
|
|
HT_CLEAR(cache_map, &cache_root);
|
|
smartlist_free(cached_resolve_pqueue);
|
|
cached_resolve_pqueue = NULL;
|
|
tor_free(resolv_conf_fname);
|
|
}
|
|
|
|
/** Remove every cached_resolve whose <b>expire</b> time is before or
|
|
* equal to <b>now</b> from the cache. */
|
|
static void
|
|
purge_expired_resolves(time_t now)
|
|
{
|
|
cached_resolve_t *resolve, *removed;
|
|
pending_connection_t *pend;
|
|
edge_connection_t *pendconn;
|
|
|
|
assert_cache_ok();
|
|
if (!cached_resolve_pqueue)
|
|
return;
|
|
|
|
while (smartlist_len(cached_resolve_pqueue)) {
|
|
resolve = smartlist_get(cached_resolve_pqueue, 0);
|
|
if (resolve->expire > now)
|
|
break;
|
|
smartlist_pqueue_pop(cached_resolve_pqueue,
|
|
compare_cached_resolves_by_expiry_,
|
|
STRUCT_OFFSET(cached_resolve_t, minheap_idx));
|
|
|
|
if (resolve->state == CACHE_STATE_PENDING) {
|
|
log_debug(LD_EXIT,
|
|
"Expiring a dns resolve %s that's still pending. Forgot to "
|
|
"cull it? DNS resolve didn't tell us about the timeout?",
|
|
escaped_safe_str(resolve->address));
|
|
} else if (resolve->state == CACHE_STATE_CACHED) {
|
|
log_debug(LD_EXIT,
|
|
"Forgetting old cached resolve (address %s, expires %lu)",
|
|
escaped_safe_str(resolve->address),
|
|
(unsigned long)resolve->expire);
|
|
tor_assert(!resolve->pending_connections);
|
|
} else {
|
|
tor_assert(resolve->state == CACHE_STATE_DONE);
|
|
tor_assert(!resolve->pending_connections);
|
|
}
|
|
|
|
if (resolve->pending_connections) {
|
|
log_debug(LD_EXIT,
|
|
"Closing pending connections on timed-out DNS resolve!");
|
|
while (resolve->pending_connections) {
|
|
pend = resolve->pending_connections;
|
|
resolve->pending_connections = pend->next;
|
|
/* Connections should only be pending if they have no socket. */
|
|
tor_assert(!SOCKET_OK(pend->conn->base_.s));
|
|
pendconn = pend->conn;
|
|
/* Prevent double-remove */
|
|
pendconn->base_.state = EXIT_CONN_STATE_RESOLVEFAILED;
|
|
if (!pendconn->base_.marked_for_close) {
|
|
connection_edge_end(pendconn, END_STREAM_REASON_TIMEOUT);
|
|
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
|
|
connection_free(TO_CONN(pendconn));
|
|
}
|
|
tor_free(pend);
|
|
}
|
|
}
|
|
|
|
if (resolve->state == CACHE_STATE_CACHED ||
|
|
resolve->state == CACHE_STATE_PENDING) {
|
|
removed = HT_REMOVE(cache_map, &cache_root, resolve);
|
|
if (removed != resolve) {
|
|
log_err(LD_BUG, "The expired resolve we purged didn't match any in"
|
|
" the cache. Tried to purge %s (%p); instead got %s (%p).",
|
|
resolve->address, (void*)resolve,
|
|
removed ? removed->address : "NULL", (void*)removed);
|
|
}
|
|
tor_assert(removed == resolve);
|
|
} else {
|
|
/* This should be in state DONE. Make sure it's not in the cache. */
|
|
cached_resolve_t *tmp = HT_FIND(cache_map, &cache_root, resolve);
|
|
tor_assert(tmp != resolve);
|
|
}
|
|
if (resolve->res_status_hostname == RES_STATUS_DONE_OK)
|
|
tor_free(resolve->result_ptr.hostname);
|
|
resolve->magic = 0xF0BBF0BB;
|
|
tor_free(resolve);
|
|
}
|
|
|
|
assert_cache_ok();
|
|
}
|
|
|
|
/* argument for send_resolved_cell only, meaning "let the answer type be ipv4
|
|
* or ipv6 depending on the connection's address". */
|
|
#define RESOLVED_TYPE_AUTO 0xff
|
|
|
|
/** Send a response to the RESOLVE request of a connection.
|
|
* <b>answer_type</b> must be one of
|
|
* RESOLVED_TYPE_(AUTO|ERROR|ERROR_TRANSIENT|).
|
|
*
|
|
* If <b>circ</b> is provided, and we have a cached answer, send the
|
|
* answer back along circ; otherwise, send the answer back along
|
|
* <b>conn</b>'s attached circuit.
|
|
*/
|
|
static void
|
|
send_resolved_cell(edge_connection_t *conn, uint8_t answer_type,
|
|
const cached_resolve_t *resolved)
|
|
{
|
|
char buf[RELAY_PAYLOAD_SIZE], *cp = buf;
|
|
size_t buflen = 0;
|
|
uint32_t ttl;
|
|
|
|
buf[0] = answer_type;
|
|
ttl = dns_clip_ttl(conn->address_ttl);
|
|
|
|
switch (answer_type)
|
|
{
|
|
case RESOLVED_TYPE_AUTO:
|
|
if (resolved && resolved->res_status_ipv4 == RES_STATUS_DONE_OK) {
|
|
cp[0] = RESOLVED_TYPE_IPV4;
|
|
cp[1] = 4;
|
|
set_uint32(cp+2, htonl(resolved->result_ipv4.addr_ipv4));
|
|
set_uint32(cp+6, htonl(ttl));
|
|
cp += 10;
|
|
}
|
|
if (resolved && resolved->res_status_ipv6 == RES_STATUS_DONE_OK) {
|
|
const uint8_t *bytes = resolved->result_ipv6.addr_ipv6.s6_addr;
|
|
cp[0] = RESOLVED_TYPE_IPV6;
|
|
cp[1] = 16;
|
|
memcpy(cp+2, bytes, 16);
|
|
set_uint32(cp+18, htonl(ttl));
|
|
cp += 22;
|
|
}
|
|
if (cp != buf) {
|
|
buflen = cp - buf;
|
|
break;
|
|
} else {
|
|
answer_type = RESOLVED_TYPE_ERROR;
|
|
/* fall through. */
|
|
}
|
|
case RESOLVED_TYPE_ERROR_TRANSIENT:
|
|
case RESOLVED_TYPE_ERROR:
|
|
{
|
|
const char *errmsg = "Error resolving hostname";
|
|
size_t msglen = strlen(errmsg);
|
|
|
|
buf[0] = answer_type;
|
|
buf[1] = msglen;
|
|
strlcpy(buf+2, errmsg, sizeof(buf)-2);
|
|
set_uint32(buf+2+msglen, htonl(ttl));
|
|
buflen = 6+msglen;
|
|
break;
|
|
}
|
|
default:
|
|
tor_assert(0);
|
|
return;
|
|
}
|
|
// log_notice(LD_EXIT, "Sending a regular RESOLVED reply: ");
|
|
|
|
connection_edge_send_command(conn, RELAY_COMMAND_RESOLVED, buf, buflen);
|
|
}
|
|
|
|
/** Send a response to the RESOLVE request of a connection for an in-addr.arpa
|
|
* address on connection <b>conn</b> which yielded the result <b>hostname</b>.
|
|
* The answer type will be RESOLVED_HOSTNAME.
|
|
*
|
|
* If <b>circ</b> is provided, and we have a cached answer, send the
|
|
* answer back along circ; otherwise, send the answer back along
|
|
* <b>conn</b>'s attached circuit.
|
|
*/
|
|
static void
|
|
send_resolved_hostname_cell(edge_connection_t *conn, const char *hostname)
|
|
{
|
|
char buf[RELAY_PAYLOAD_SIZE];
|
|
size_t buflen;
|
|
uint32_t ttl;
|
|
size_t namelen = strlen(hostname);
|
|
tor_assert(hostname);
|
|
|
|
tor_assert(namelen < 256);
|
|
ttl = dns_clip_ttl(conn->address_ttl);
|
|
|
|
buf[0] = RESOLVED_TYPE_HOSTNAME;
|
|
buf[1] = (uint8_t)namelen;
|
|
memcpy(buf+2, hostname, namelen);
|
|
set_uint32(buf+2+namelen, htonl(ttl));
|
|
buflen = 2+namelen+4;
|
|
|
|
// log_notice(LD_EXIT, "Sending a reply RESOLVED reply: %s", hostname);
|
|
connection_edge_send_command(conn, RELAY_COMMAND_RESOLVED, buf, buflen);
|
|
// log_notice(LD_EXIT, "Sent");
|
|
}
|
|
|
|
/** See if we have a cache entry for <b>exitconn</b>-\>address. If so,
|
|
* if resolve valid, put it into <b>exitconn</b>-\>addr and return 1.
|
|
* If resolve failed, free exitconn and return -1.
|
|
*
|
|
* (For EXIT_PURPOSE_RESOLVE connections, send back a RESOLVED error cell
|
|
* on returning -1. For EXIT_PURPOSE_CONNECT connections, there's no
|
|
* need to send back an END cell, since connection_exit_begin_conn will
|
|
* do that for us.)
|
|
*
|
|
* If we have a cached answer, send the answer back along <b>exitconn</b>'s
|
|
* circuit.
|
|
*
|
|
* Else, if seen before and pending, add conn to the pending list,
|
|
* and return 0.
|
|
*
|
|
* Else, if not seen before, add conn to pending list, hand to
|
|
* dns farm, and return 0.
|
|
*
|
|
* Exitconn's on_circuit field must be set, but exitconn should not
|
|
* yet be linked onto the n_streams/resolving_streams list of that circuit.
|
|
* On success, link the connection to n_streams if it's an exit connection.
|
|
* On "pending", link the connection to resolving streams. Otherwise,
|
|
* clear its on_circuit field.
|
|
*/
|
|
int
|
|
dns_resolve(edge_connection_t *exitconn)
|
|
{
|
|
or_circuit_t *oncirc = TO_OR_CIRCUIT(exitconn->on_circuit);
|
|
int is_resolve, r;
|
|
int made_connection_pending = 0;
|
|
char *hostname = NULL;
|
|
cached_resolve_t *resolve = NULL;
|
|
is_resolve = exitconn->base_.purpose == EXIT_PURPOSE_RESOLVE;
|
|
|
|
r = dns_resolve_impl(exitconn, is_resolve, oncirc, &hostname,
|
|
&made_connection_pending, &resolve);
|
|
|
|
switch (r) {
|
|
case 1:
|
|
/* We got an answer without a lookup -- either the answer was
|
|
* cached, or it was obvious (like an IP address). */
|
|
if (is_resolve) {
|
|
/* Send the answer back right now, and detach. */
|
|
if (hostname)
|
|
send_resolved_hostname_cell(exitconn, hostname);
|
|
else
|
|
send_resolved_cell(exitconn, RESOLVED_TYPE_AUTO, resolve);
|
|
exitconn->on_circuit = NULL;
|
|
} else {
|
|
/* Add to the n_streams list; the calling function will send back a
|
|
* connected cell. */
|
|
exitconn->next_stream = oncirc->n_streams;
|
|
oncirc->n_streams = exitconn;
|
|
}
|
|
break;
|
|
case 0:
|
|
/* The request is pending: add the connection into the linked list of
|
|
* resolving_streams on this circuit. */
|
|
exitconn->base_.state = EXIT_CONN_STATE_RESOLVING;
|
|
exitconn->next_stream = oncirc->resolving_streams;
|
|
oncirc->resolving_streams = exitconn;
|
|
break;
|
|
case -2:
|
|
case -1:
|
|
/* The request failed before it could start: cancel this connection,
|
|
* and stop everybody waiting for the same connection. */
|
|
if (is_resolve) {
|
|
send_resolved_cell(exitconn,
|
|
(r == -1) ? RESOLVED_TYPE_ERROR : RESOLVED_TYPE_ERROR_TRANSIENT,
|
|
NULL);
|
|
}
|
|
|
|
exitconn->on_circuit = NULL;
|
|
|
|
dns_cancel_pending_resolve(exitconn->base_.address);
|
|
|
|
if (!made_connection_pending && !exitconn->base_.marked_for_close) {
|
|
/* If we made the connection pending, then we freed it already in
|
|
* dns_cancel_pending_resolve(). If we marked it for close, it'll
|
|
* get freed from the main loop. Otherwise, can free it now. */
|
|
connection_free(TO_CONN(exitconn));
|
|
}
|
|
break;
|
|
default:
|
|
tor_assert(0);
|
|
}
|
|
|
|
tor_free(hostname);
|
|
return r;
|
|
}
|
|
|
|
/** Helper function for dns_resolve: same functionality, but does not handle:
|
|
* - marking connections on error and clearing their on_circuit
|
|
* - linking connections to n_streams/resolving_streams,
|
|
* - sending resolved cells if we have an answer/error right away,
|
|
*
|
|
* Return -2 on a transient error. If it's a reverse resolve and it's
|
|
* successful, sets *<b>hostname_out</b> to a newly allocated string
|
|
* holding the cached reverse DNS value.
|
|
*
|
|
* Set *<b>made_connection_pending_out</b> to true if we have placed
|
|
* <b>exitconn</b> on the list of pending connections for some resolve; set it
|
|
* to false otherwise.
|
|
*
|
|
* Set *<b>resolve_out</b> to a cached resolve, if we found one.
|
|
*/
|
|
static int
|
|
dns_resolve_impl(edge_connection_t *exitconn, int is_resolve,
|
|
or_circuit_t *oncirc, char **hostname_out,
|
|
int *made_connection_pending_out,
|
|
cached_resolve_t **resolve_out)
|
|
{
|
|
cached_resolve_t *resolve;
|
|
cached_resolve_t search;
|
|
pending_connection_t *pending_connection;
|
|
int is_reverse = 0;
|
|
tor_addr_t addr;
|
|
time_t now = time(NULL);
|
|
int r;
|
|
assert_connection_ok(TO_CONN(exitconn), 0);
|
|
tor_assert(!SOCKET_OK(exitconn->base_.s));
|
|
assert_cache_ok();
|
|
tor_assert(oncirc);
|
|
*made_connection_pending_out = 0;
|
|
|
|
/* first check if exitconn->base_.address is an IP. If so, we already
|
|
* know the answer. */
|
|
if (tor_addr_parse(&addr, exitconn->base_.address) >= 0) {
|
|
if (tor_addr_family(&addr) == AF_INET ||
|
|
tor_addr_family(&addr) == AF_INET6) {
|
|
tor_addr_copy(&exitconn->base_.addr, &addr);
|
|
exitconn->address_ttl = DEFAULT_DNS_TTL;
|
|
return 1;
|
|
} else {
|
|
/* XXXX unspec? Bogus? */
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/* If we're a non-exit, don't even do DNS lookups. */
|
|
if (router_my_exit_policy_is_reject_star())
|
|
return -1;
|
|
|
|
if (address_is_invalid_destination(exitconn->base_.address, 0)) {
|
|
tor_log(LOG_PROTOCOL_WARN, LD_EXIT,
|
|
"Rejecting invalid destination address %s",
|
|
escaped_safe_str(exitconn->base_.address));
|
|
return -1;
|
|
}
|
|
|
|
/* then take this opportunity to see if there are any expired
|
|
* resolves in the hash table. */
|
|
purge_expired_resolves(now);
|
|
|
|
/* lower-case exitconn->base_.address, so it's in canonical form */
|
|
tor_strlower(exitconn->base_.address);
|
|
|
|
/* Check whether this is a reverse lookup. If it's malformed, or it's a
|
|
* .in-addr.arpa address but this isn't a resolve request, kill the
|
|
* connection.
|
|
*/
|
|
if ((r = tor_addr_parse_PTR_name(&addr, exitconn->base_.address,
|
|
AF_UNSPEC, 0)) != 0) {
|
|
if (r == 1) {
|
|
is_reverse = 1;
|
|
if (tor_addr_is_internal(&addr, 0)) /* internal address? */
|
|
return -1;
|
|
}
|
|
|
|
if (!is_reverse || !is_resolve) {
|
|
if (!is_reverse)
|
|
log_info(LD_EXIT, "Bad .in-addr.arpa address \"%s\"; sending error.",
|
|
escaped_safe_str(exitconn->base_.address));
|
|
else if (!is_resolve)
|
|
log_info(LD_EXIT,
|
|
"Attempt to connect to a .in-addr.arpa address \"%s\"; "
|
|
"sending error.",
|
|
escaped_safe_str(exitconn->base_.address));
|
|
|
|
return -1;
|
|
}
|
|
//log_notice(LD_EXIT, "Looks like an address %s",
|
|
//exitconn->base_.address);
|
|
}
|
|
exitconn->is_reverse_dns_lookup = is_reverse;
|
|
|
|
/* now check the hash table to see if 'address' is already there. */
|
|
strlcpy(search.address, exitconn->base_.address, sizeof(search.address));
|
|
resolve = HT_FIND(cache_map, &cache_root, &search);
|
|
if (resolve && resolve->expire > now) { /* already there */
|
|
switch (resolve->state) {
|
|
case CACHE_STATE_PENDING:
|
|
/* add us to the pending list */
|
|
pending_connection = tor_malloc_zero(
|
|
sizeof(pending_connection_t));
|
|
pending_connection->conn = exitconn;
|
|
pending_connection->next = resolve->pending_connections;
|
|
resolve->pending_connections = pending_connection;
|
|
*made_connection_pending_out = 1;
|
|
log_debug(LD_EXIT,"Connection (fd "TOR_SOCKET_T_FORMAT") waiting "
|
|
"for pending DNS resolve of %s", exitconn->base_.s,
|
|
escaped_safe_str(exitconn->base_.address));
|
|
return 0;
|
|
case CACHE_STATE_CACHED:
|
|
log_debug(LD_EXIT,"Connection (fd "TOR_SOCKET_T_FORMAT") found "
|
|
"cached answer for %s",
|
|
exitconn->base_.s,
|
|
escaped_safe_str(resolve->address));
|
|
|
|
*resolve_out = resolve;
|
|
|
|
return set_exitconn_info_from_resolve(exitconn, resolve, hostname_out);
|
|
case CACHE_STATE_DONE:
|
|
log_err(LD_BUG, "Found a 'DONE' dns resolve still in the cache.");
|
|
tor_fragile_assert();
|
|
}
|
|
tor_assert(0);
|
|
}
|
|
tor_assert(!resolve);
|
|
/* not there, need to add it */
|
|
resolve = tor_malloc_zero(sizeof(cached_resolve_t));
|
|
resolve->magic = CACHED_RESOLVE_MAGIC;
|
|
resolve->state = CACHE_STATE_PENDING;
|
|
resolve->minheap_idx = -1;
|
|
strlcpy(resolve->address, exitconn->base_.address, sizeof(resolve->address));
|
|
|
|
/* add this connection to the pending list */
|
|
pending_connection = tor_malloc_zero(sizeof(pending_connection_t));
|
|
pending_connection->conn = exitconn;
|
|
resolve->pending_connections = pending_connection;
|
|
*made_connection_pending_out = 1;
|
|
|
|
/* Add this resolve to the cache and priority queue. */
|
|
HT_INSERT(cache_map, &cache_root, resolve);
|
|
set_expiry(resolve, now + RESOLVE_MAX_TIMEOUT);
|
|
|
|
log_debug(LD_EXIT,"Launching %s.",
|
|
escaped_safe_str(exitconn->base_.address));
|
|
assert_cache_ok();
|
|
|
|
return launch_resolve(resolve);
|
|
}
|
|
|
|
/** Given an exit connection <b>exitconn</b>, and a cached_resolve_t
|
|
* <b>resolve</b> whose DNS lookups have all succeeded or failed, update the
|
|
* appropriate fields (address_ttl and addr) of <b>exitconn</b>.
|
|
*
|
|
* If this is a reverse lookup, set *<b>hostname_out</b> to a newly allocated
|
|
* copy of the name resulting hostname.
|
|
*
|
|
* Return -2 on a transient error, -1 on a permenent error, and 1 on
|
|
* a successful lookup.
|
|
*/
|
|
static int
|
|
set_exitconn_info_from_resolve(edge_connection_t *exitconn,
|
|
const cached_resolve_t *resolve,
|
|
char **hostname_out)
|
|
{
|
|
int ipv4_ok, ipv6_ok, answer_with_ipv4, r;
|
|
uint32_t begincell_flags;
|
|
const int is_resolve = exitconn->base_.purpose == EXIT_PURPOSE_RESOLVE;
|
|
tor_assert(exitconn);
|
|
tor_assert(resolve);
|
|
|
|
if (exitconn->is_reverse_dns_lookup) {
|
|
exitconn->address_ttl = resolve->ttl_hostname;
|
|
if (resolve->res_status_hostname == RES_STATUS_DONE_OK) {
|
|
*hostname_out = tor_strdup(resolve->result_ptr.hostname);
|
|
return 1;
|
|
} else {
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/* If we're here then the connection wants one or either of ipv4, ipv6, and
|
|
* we can give it one or both. */
|
|
if (is_resolve) {
|
|
begincell_flags = BEGIN_FLAG_IPV6_OK;
|
|
} else {
|
|
begincell_flags = exitconn->begincell_flags;
|
|
}
|
|
|
|
ipv4_ok = (resolve->res_status_ipv4 == RES_STATUS_DONE_OK) &&
|
|
! (begincell_flags & BEGIN_FLAG_IPV4_NOT_OK);
|
|
ipv6_ok = (resolve->res_status_ipv6 == RES_STATUS_DONE_OK) &&
|
|
(begincell_flags & BEGIN_FLAG_IPV6_OK) &&
|
|
get_options()->IPv6Exit;
|
|
|
|
/* Now decide which one to actually give. */
|
|
if (ipv4_ok && ipv6_ok && is_resolve) {
|
|
answer_with_ipv4 = 1;
|
|
} else if (ipv4_ok && ipv6_ok) {
|
|
/* If we have both, see if our exit policy has an opinion. */
|
|
const uint16_t port = exitconn->base_.port;
|
|
int ipv4_allowed, ipv6_allowed;
|
|
tor_addr_t a4, a6;
|
|
tor_addr_from_ipv4h(&a4, resolve->result_ipv4.addr_ipv4);
|
|
tor_addr_from_in6(&a6, &resolve->result_ipv6.addr_ipv6);
|
|
ipv4_allowed = !router_compare_to_my_exit_policy(&a4, port);
|
|
ipv6_allowed = !router_compare_to_my_exit_policy(&a6, port);
|
|
if (ipv4_allowed && !ipv6_allowed) {
|
|
answer_with_ipv4 = 1;
|
|
} else if (ipv6_allowed && !ipv4_allowed) {
|
|
answer_with_ipv4 = 0;
|
|
} else {
|
|
/* Our exit policy would permit both. Answer with whichever the user
|
|
* prefers */
|
|
answer_with_ipv4 = !(begincell_flags &
|
|
BEGIN_FLAG_IPV6_PREFERRED);
|
|
}
|
|
} else {
|
|
/* Otherwise if one is okay, send it back. */
|
|
if (ipv4_ok) {
|
|
answer_with_ipv4 = 1;
|
|
} else if (ipv6_ok) {
|
|
answer_with_ipv4 = 0;
|
|
} else {
|
|
/* Neither one was okay. Choose based on user preference. */
|
|
answer_with_ipv4 = !(begincell_flags &
|
|
BEGIN_FLAG_IPV6_PREFERRED);
|
|
}
|
|
}
|
|
|
|
/* Finally, we write the answer back. */
|
|
r = 1;
|
|
if (answer_with_ipv4) {
|
|
if (resolve->res_status_ipv4 == RES_STATUS_DONE_OK) {
|
|
tor_addr_from_ipv4h(&exitconn->base_.addr,
|
|
resolve->result_ipv4.addr_ipv4);
|
|
} else {
|
|
r = evdns_err_is_transient(resolve->result_ipv4.err_ipv4) ? -2 : -1;
|
|
}
|
|
|
|
exitconn->address_ttl = resolve->ttl_ipv4;
|
|
} else {
|
|
if (resolve->res_status_ipv6 == RES_STATUS_DONE_OK) {
|
|
tor_addr_from_in6(&exitconn->base_.addr,
|
|
&resolve->result_ipv6.addr_ipv6);
|
|
} else {
|
|
r = evdns_err_is_transient(resolve->result_ipv6.err_ipv6) ? -2 : -1;
|
|
}
|
|
|
|
exitconn->address_ttl = resolve->ttl_ipv6;
|
|
}
|
|
|
|
return r;
|
|
}
|
|
|
|
/** Log an error and abort if conn is waiting for a DNS resolve.
|
|
*/
|
|
void
|
|
assert_connection_edge_not_dns_pending(edge_connection_t *conn)
|
|
{
|
|
pending_connection_t *pend;
|
|
cached_resolve_t search;
|
|
|
|
#if 1
|
|
cached_resolve_t *resolve;
|
|
strlcpy(search.address, conn->base_.address, sizeof(search.address));
|
|
resolve = HT_FIND(cache_map, &cache_root, &search);
|
|
if (!resolve)
|
|
return;
|
|
for (pend = resolve->pending_connections; pend; pend = pend->next) {
|
|
tor_assert(pend->conn != conn);
|
|
}
|
|
#else
|
|
cached_resolve_t **resolve;
|
|
HT_FOREACH(resolve, cache_map, &cache_root) {
|
|
for (pend = (*resolve)->pending_connections; pend; pend = pend->next) {
|
|
tor_assert(pend->conn != conn);
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/** Log an error and abort if any connection waiting for a DNS resolve is
|
|
* corrupted. */
|
|
void
|
|
assert_all_pending_dns_resolves_ok(void)
|
|
{
|
|
pending_connection_t *pend;
|
|
cached_resolve_t **resolve;
|
|
|
|
HT_FOREACH(resolve, cache_map, &cache_root) {
|
|
for (pend = (*resolve)->pending_connections;
|
|
pend;
|
|
pend = pend->next) {
|
|
assert_connection_ok(TO_CONN(pend->conn), 0);
|
|
tor_assert(!SOCKET_OK(pend->conn->base_.s));
|
|
tor_assert(!connection_in_array(TO_CONN(pend->conn)));
|
|
}
|
|
}
|
|
}
|
|
|
|
/** Remove <b>conn</b> from the list of connections waiting for conn-\>address.
|
|
*/
|
|
void
|
|
connection_dns_remove(edge_connection_t *conn)
|
|
{
|
|
pending_connection_t *pend, *victim;
|
|
cached_resolve_t search;
|
|
cached_resolve_t *resolve;
|
|
|
|
tor_assert(conn->base_.type == CONN_TYPE_EXIT);
|
|
tor_assert(conn->base_.state == EXIT_CONN_STATE_RESOLVING);
|
|
|
|
strlcpy(search.address, conn->base_.address, sizeof(search.address));
|
|
|
|
resolve = HT_FIND(cache_map, &cache_root, &search);
|
|
if (!resolve) {
|
|
log_notice(LD_BUG, "Address %s is not pending. Dropping.",
|
|
escaped_safe_str(conn->base_.address));
|
|
return;
|
|
}
|
|
|
|
tor_assert(resolve->pending_connections);
|
|
assert_connection_ok(TO_CONN(conn),0);
|
|
|
|
pend = resolve->pending_connections;
|
|
|
|
if (pend->conn == conn) {
|
|
resolve->pending_connections = pend->next;
|
|
tor_free(pend);
|
|
log_debug(LD_EXIT, "First connection (fd "TOR_SOCKET_T_FORMAT") no "
|
|
"longer waiting for resolve of %s",
|
|
conn->base_.s,
|
|
escaped_safe_str(conn->base_.address));
|
|
return;
|
|
} else {
|
|
for ( ; pend->next; pend = pend->next) {
|
|
if (pend->next->conn == conn) {
|
|
victim = pend->next;
|
|
pend->next = victim->next;
|
|
tor_free(victim);
|
|
log_debug(LD_EXIT,
|
|
"Connection (fd "TOR_SOCKET_T_FORMAT") no longer waiting "
|
|
"for resolve of %s",
|
|
conn->base_.s, escaped_safe_str(conn->base_.address));
|
|
return; /* more are pending */
|
|
}
|
|
}
|
|
log_warn(LD_BUG, "Connection (fd "TOR_SOCKET_T_FORMAT") was not waiting "
|
|
"for a resolve of %s, but we tried to remove it.",
|
|
conn->base_.s, escaped_safe_str(conn->base_.address));
|
|
}
|
|
}
|
|
|
|
/** Mark all connections waiting for <b>address</b> for close. Then cancel
|
|
* the resolve for <b>address</b> itself, and remove any cached results for
|
|
* <b>address</b> from the cache.
|
|
*/
|
|
void
|
|
dns_cancel_pending_resolve(const char *address)
|
|
{
|
|
pending_connection_t *pend;
|
|
cached_resolve_t search;
|
|
cached_resolve_t *resolve, *tmp;
|
|
edge_connection_t *pendconn;
|
|
circuit_t *circ;
|
|
|
|
strlcpy(search.address, address, sizeof(search.address));
|
|
|
|
resolve = HT_FIND(cache_map, &cache_root, &search);
|
|
if (!resolve)
|
|
return;
|
|
|
|
if (resolve->state != CACHE_STATE_PENDING) {
|
|
/* We can get into this state if we never actually created the pending
|
|
* resolve, due to finding an earlier cached error or something. Just
|
|
* ignore it. */
|
|
if (resolve->pending_connections) {
|
|
log_warn(LD_BUG,
|
|
"Address %s is not pending but has pending connections!",
|
|
escaped_safe_str(address));
|
|
tor_fragile_assert();
|
|
}
|
|
return;
|
|
}
|
|
|
|
if (!resolve->pending_connections) {
|
|
log_warn(LD_BUG,
|
|
"Address %s is pending but has no pending connections!",
|
|
escaped_safe_str(address));
|
|
tor_fragile_assert();
|
|
return;
|
|
}
|
|
tor_assert(resolve->pending_connections);
|
|
|
|
/* mark all pending connections to fail */
|
|
log_debug(LD_EXIT,
|
|
"Failing all connections waiting on DNS resolve of %s",
|
|
escaped_safe_str(address));
|
|
while (resolve->pending_connections) {
|
|
pend = resolve->pending_connections;
|
|
pend->conn->base_.state = EXIT_CONN_STATE_RESOLVEFAILED;
|
|
pendconn = pend->conn;
|
|
assert_connection_ok(TO_CONN(pendconn), 0);
|
|
tor_assert(!SOCKET_OK(pendconn->base_.s));
|
|
if (!pendconn->base_.marked_for_close) {
|
|
connection_edge_end(pendconn, END_STREAM_REASON_RESOLVEFAILED);
|
|
}
|
|
circ = circuit_get_by_edge_conn(pendconn);
|
|
if (circ)
|
|
circuit_detach_stream(circ, pendconn);
|
|
if (!pendconn->base_.marked_for_close)
|
|
connection_free(TO_CONN(pendconn));
|
|
resolve->pending_connections = pend->next;
|
|
tor_free(pend);
|
|
}
|
|
|
|
tmp = HT_REMOVE(cache_map, &cache_root, resolve);
|
|
if (tmp != resolve) {
|
|
log_err(LD_BUG, "The cancelled resolve we purged didn't match any in"
|
|
" the cache. Tried to purge %s (%p); instead got %s (%p).",
|
|
resolve->address, (void*)resolve,
|
|
tmp ? tmp->address : "NULL", (void*)tmp);
|
|
}
|
|
tor_assert(tmp == resolve);
|
|
|
|
resolve->state = CACHE_STATE_DONE;
|
|
}
|
|
|
|
/** Return true iff <b>address</b> is one of the addresses we use to verify
|
|
* that well-known sites aren't being hijacked by our DNS servers. */
|
|
static INLINE int
|
|
is_test_address(const char *address)
|
|
{
|
|
const or_options_t *options = get_options();
|
|
return options->ServerDNSTestAddresses &&
|
|
smartlist_contains_string_case(options->ServerDNSTestAddresses, address);
|
|
}
|
|
|
|
/** Called on the OR side when the eventdns library tells us the outcome of a
|
|
* single DNS resolve: remember the answer, and tell all pending connections
|
|
* about the result of the lookup if the lookup is now done. (<b>address</b>
|
|
* is a NUL-terminated string containing the address to look up;
|
|
* <b>query_type</b> is one of DNS_{IPv4_A,IPv6_AAAA,PTR}; <b>dns_answer</b>
|
|
* is DNS_OK or one of DNS_ERR_*, <b>addr</b> is an IPv4 or IPv6 address if we
|
|
* got one; <b>hostname</b> is a hostname fora PTR request if we got one, and
|
|
* <b>ttl</b> is the time-to-live of this answer, in seconds.)
|
|
*/
|
|
static void
|
|
dns_found_answer(const char *address, uint8_t query_type,
|
|
int dns_answer,
|
|
const tor_addr_t *addr,
|
|
const char *hostname, uint32_t ttl)
|
|
{
|
|
cached_resolve_t search;
|
|
cached_resolve_t *resolve;
|
|
|
|
assert_cache_ok();
|
|
|
|
strlcpy(search.address, address, sizeof(search.address));
|
|
|
|
resolve = HT_FIND(cache_map, &cache_root, &search);
|
|
if (!resolve) {
|
|
int is_test_addr = is_test_address(address);
|
|
if (!is_test_addr)
|
|
log_info(LD_EXIT,"Resolved unasked address %s; ignoring.",
|
|
escaped_safe_str(address));
|
|
return;
|
|
}
|
|
assert_resolve_ok(resolve);
|
|
|
|
if (resolve->state != CACHE_STATE_PENDING) {
|
|
/* XXXX Maybe update addr? or check addr for consistency? Or let
|
|
* VALID replace FAILED? */
|
|
int is_test_addr = is_test_address(address);
|
|
if (!is_test_addr)
|
|
log_notice(LD_EXIT,
|
|
"Resolved %s which was already resolved; ignoring",
|
|
escaped_safe_str(address));
|
|
tor_assert(resolve->pending_connections == NULL);
|
|
return;
|
|
}
|
|
|
|
cached_resolve_add_answer(resolve, query_type, dns_answer,
|
|
addr, hostname, ttl);
|
|
|
|
if (cached_resolve_have_all_answers(resolve)) {
|
|
inform_pending_connections(resolve);
|
|
|
|
make_pending_resolve_cached(resolve);
|
|
}
|
|
}
|
|
|
|
/** Given a pending cached_resolve_t that we just finished resolving,
|
|
* inform every connection that was waiting for the outcome of that
|
|
* resolution. */
|
|
static void
|
|
inform_pending_connections(cached_resolve_t *resolve)
|
|
{
|
|
pending_connection_t *pend;
|
|
edge_connection_t *pendconn;
|
|
int r;
|
|
|
|
while (resolve->pending_connections) {
|
|
char *hostname = NULL;
|
|
pend = resolve->pending_connections;
|
|
pendconn = pend->conn; /* don't pass complex things to the
|
|
connection_mark_for_close macro */
|
|
assert_connection_ok(TO_CONN(pendconn),time(NULL));
|
|
|
|
if (pendconn->base_.marked_for_close) {
|
|
/* prevent double-remove. */
|
|
pendconn->base_.state = EXIT_CONN_STATE_RESOLVEFAILED;
|
|
resolve->pending_connections = pend->next;
|
|
tor_free(pend);
|
|
continue;
|
|
}
|
|
|
|
r = set_exitconn_info_from_resolve(pendconn,
|
|
resolve,
|
|
&hostname);
|
|
|
|
if (r < 0) {
|
|
/* prevent double-remove. */
|
|
pendconn->base_.state = EXIT_CONN_STATE_RESOLVEFAILED;
|
|
if (pendconn->base_.purpose == EXIT_PURPOSE_CONNECT) {
|
|
connection_edge_end(pendconn, END_STREAM_REASON_RESOLVEFAILED);
|
|
/* This detach must happen after we send the end cell. */
|
|
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
|
|
} else {
|
|
send_resolved_cell(pendconn, r == -1 ?
|
|
RESOLVED_TYPE_ERROR : RESOLVED_TYPE_ERROR_TRANSIENT,
|
|
NULL);
|
|
/* This detach must happen after we send the resolved cell. */
|
|
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
|
|
}
|
|
connection_free(TO_CONN(pendconn));
|
|
} else {
|
|
circuit_t *circ;
|
|
if (pendconn->base_.purpose == EXIT_PURPOSE_CONNECT) {
|
|
/* prevent double-remove. */
|
|
pend->conn->base_.state = EXIT_CONN_STATE_CONNECTING;
|
|
|
|
circ = circuit_get_by_edge_conn(pend->conn);
|
|
tor_assert(circ);
|
|
tor_assert(!CIRCUIT_IS_ORIGIN(circ));
|
|
/* unlink pend->conn from resolving_streams, */
|
|
circuit_detach_stream(circ, pend->conn);
|
|
/* and link it to n_streams */
|
|
pend->conn->next_stream = TO_OR_CIRCUIT(circ)->n_streams;
|
|
pend->conn->on_circuit = circ;
|
|
TO_OR_CIRCUIT(circ)->n_streams = pend->conn;
|
|
|
|
connection_exit_connect(pend->conn);
|
|
} else {
|
|
/* prevent double-remove. This isn't really an accurate state,
|
|
* but it does the right thing. */
|
|
pendconn->base_.state = EXIT_CONN_STATE_RESOLVEFAILED;
|
|
if (pendconn->is_reverse_dns_lookup)
|
|
send_resolved_hostname_cell(pendconn, hostname);
|
|
else
|
|
send_resolved_cell(pendconn, RESOLVED_TYPE_AUTO, resolve);
|
|
circ = circuit_get_by_edge_conn(pendconn);
|
|
tor_assert(circ);
|
|
circuit_detach_stream(circ, pendconn);
|
|
connection_free(TO_CONN(pendconn));
|
|
}
|
|
}
|
|
resolve->pending_connections = pend->next;
|
|
tor_free(pend);
|
|
tor_free(hostname);
|
|
}
|
|
}
|
|
|
|
/** Remove a pending cached_resolve_t from the hashtable, and add a
|
|
* corresponding cached cached_resolve_t.
|
|
*
|
|
* This function is only necessary because of the perversity of our
|
|
* cache timeout code; see inline comment for ideas on eliminating it.
|
|
**/
|
|
static void
|
|
make_pending_resolve_cached(cached_resolve_t *resolve)
|
|
{
|
|
cached_resolve_t *removed;
|
|
|
|
resolve->state = CACHE_STATE_DONE;
|
|
removed = HT_REMOVE(cache_map, &cache_root, resolve);
|
|
if (removed != resolve) {
|
|
log_err(LD_BUG, "The pending resolve we found wasn't removable from"
|
|
" the cache. Tried to purge %s (%p); instead got %s (%p).",
|
|
resolve->address, (void*)resolve,
|
|
removed ? removed->address : "NULL", (void*)removed);
|
|
}
|
|
assert_resolve_ok(resolve);
|
|
assert_cache_ok();
|
|
/* The resolve will eventually just hit the time-out in the expiry queue and
|
|
* expire. See fd0bafb0dedc7e2 for a brief explanation of how this got that
|
|
* way. XXXXX we could do better!*/
|
|
|
|
{
|
|
cached_resolve_t *new_resolve = tor_memdup(resolve,
|
|
sizeof(cached_resolve_t));
|
|
uint32_t ttl = UINT32_MAX;
|
|
new_resolve->expire = 0; /* So that set_expiry won't croak. */
|
|
if (resolve->res_status_hostname == RES_STATUS_DONE_OK)
|
|
new_resolve->result_ptr.hostname =
|
|
tor_strdup(resolve->result_ptr.hostname);
|
|
|
|
new_resolve->state = CACHE_STATE_CACHED;
|
|
|
|
assert_resolve_ok(new_resolve);
|
|
HT_INSERT(cache_map, &cache_root, new_resolve);
|
|
|
|
if ((resolve->res_status_ipv4 == RES_STATUS_DONE_OK ||
|
|
resolve->res_status_ipv4 == RES_STATUS_DONE_ERR) &&
|
|
resolve->ttl_ipv4 < ttl)
|
|
ttl = resolve->ttl_ipv4;
|
|
|
|
if ((resolve->res_status_ipv6 == RES_STATUS_DONE_OK ||
|
|
resolve->res_status_ipv6 == RES_STATUS_DONE_ERR) &&
|
|
resolve->ttl_ipv6 < ttl)
|
|
ttl = resolve->ttl_ipv6;
|
|
|
|
if ((resolve->res_status_hostname == RES_STATUS_DONE_OK ||
|
|
resolve->res_status_hostname == RES_STATUS_DONE_ERR) &&
|
|
resolve->ttl_hostname < ttl)
|
|
ttl = resolve->ttl_hostname;
|
|
|
|
set_expiry(new_resolve, time(NULL) + dns_get_expiry_ttl(ttl));
|
|
}
|
|
|
|
assert_cache_ok();
|
|
}
|
|
|
|
/** Eventdns helper: return true iff the eventdns result <b>err</b> is
|
|
* a transient failure. */
|
|
static int
|
|
evdns_err_is_transient(int err)
|
|
{
|
|
switch (err)
|
|
{
|
|
case DNS_ERR_SERVERFAILED:
|
|
case DNS_ERR_TRUNCATED:
|
|
case DNS_ERR_TIMEOUT:
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/** Configure eventdns nameservers if force is true, or if the configuration
|
|
* has changed since the last time we called this function, or if we failed on
|
|
* our last attempt. On Unix, this reads from /etc/resolv.conf or
|
|
* options->ServerDNSResolvConfFile; on Windows, this reads from
|
|
* options->ServerDNSResolvConfFile or the registry. Return 0 on success or
|
|
* -1 on failure. */
|
|
static int
|
|
configure_nameservers(int force)
|
|
{
|
|
const or_options_t *options;
|
|
const char *conf_fname;
|
|
struct stat st;
|
|
int r;
|
|
options = get_options();
|
|
conf_fname = options->ServerDNSResolvConfFile;
|
|
#ifndef _WIN32
|
|
if (!conf_fname)
|
|
conf_fname = "/etc/resolv.conf";
|
|
#endif
|
|
|
|
if (!the_evdns_base) {
|
|
if (!(the_evdns_base = evdns_base_new(tor_libevent_get_base(), 0))) {
|
|
log_err(LD_BUG, "Couldn't create an evdns_base");
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
#ifdef HAVE_EVDNS_SET_DEFAULT_OUTGOING_BIND_ADDRESS
|
|
if (! tor_addr_is_null(&options->OutboundBindAddressIPv4_)) {
|
|
int socklen;
|
|
struct sockaddr_storage ss;
|
|
socklen = tor_addr_to_sockaddr(&options->OutboundBindAddressIPv4_, 0,
|
|
(struct sockaddr *)&ss, sizeof(ss));
|
|
if (socklen <= 0) {
|
|
log_warn(LD_BUG, "Couldn't convert outbound bind address to sockaddr."
|
|
" Ignoring.");
|
|
} else {
|
|
evdns_base_set_default_outgoing_bind_address(the_evdns_base,
|
|
(struct sockaddr *)&ss,
|
|
socklen);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
evdns_set_log_fn(evdns_log_cb);
|
|
if (conf_fname) {
|
|
if (stat(conf_fname, &st)) {
|
|
log_warn(LD_EXIT, "Unable to stat resolver configuration in '%s': %s",
|
|
conf_fname, strerror(errno));
|
|
goto err;
|
|
}
|
|
if (!force && resolv_conf_fname && !strcmp(conf_fname,resolv_conf_fname)
|
|
&& st.st_mtime == resolv_conf_mtime) {
|
|
log_info(LD_EXIT, "No change to '%s'", conf_fname);
|
|
return 0;
|
|
}
|
|
if (nameservers_configured) {
|
|
evdns_base_search_clear(the_evdns_base);
|
|
evdns_base_clear_nameservers_and_suspend(the_evdns_base);
|
|
}
|
|
log_info(LD_EXIT, "Parsing resolver configuration in '%s'", conf_fname);
|
|
if ((r = evdns_base_resolv_conf_parse(the_evdns_base,
|
|
DNS_OPTIONS_ALL, conf_fname))) {
|
|
log_warn(LD_EXIT, "Unable to parse '%s', or no nameservers in '%s' (%d)",
|
|
conf_fname, conf_fname, r);
|
|
goto err;
|
|
}
|
|
if (evdns_base_count_nameservers(the_evdns_base) == 0) {
|
|
log_warn(LD_EXIT, "Unable to find any nameservers in '%s'.", conf_fname);
|
|
goto err;
|
|
}
|
|
tor_free(resolv_conf_fname);
|
|
resolv_conf_fname = tor_strdup(conf_fname);
|
|
resolv_conf_mtime = st.st_mtime;
|
|
if (nameservers_configured)
|
|
evdns_base_resume(the_evdns_base);
|
|
}
|
|
#ifdef _WIN32
|
|
else {
|
|
if (nameservers_configured) {
|
|
evdns_base_search_clear(the_evdns_base);
|
|
evdns_base_clear_nameservers_and_suspend(the_evdns_base);
|
|
}
|
|
if (evdns_base_config_windows_nameservers(the_evdns_base)) {
|
|
log_warn(LD_EXIT,"Could not config nameservers.");
|
|
goto err;
|
|
}
|
|
if (evdns_base_count_nameservers(the_evdns_base) == 0) {
|
|
log_warn(LD_EXIT, "Unable to find any platform nameservers in "
|
|
"your Windows configuration.");
|
|
goto err;
|
|
}
|
|
if (nameservers_configured)
|
|
evdns_base_resume(the_evdns_base);
|
|
tor_free(resolv_conf_fname);
|
|
resolv_conf_mtime = 0;
|
|
}
|
|
#endif
|
|
|
|
#define SET(k,v) evdns_base_set_option_(the_evdns_base, (k), (v))
|
|
|
|
if (evdns_base_count_nameservers(the_evdns_base) == 1) {
|
|
SET("max-timeouts:", "16");
|
|
SET("timeout:", "10");
|
|
} else {
|
|
SET("max-timeouts:", "3");
|
|
SET("timeout:", "5");
|
|
}
|
|
|
|
if (options->ServerDNSRandomizeCase)
|
|
SET("randomize-case:", "1");
|
|
else
|
|
SET("randomize-case:", "0");
|
|
|
|
#undef SET
|
|
|
|
dns_servers_relaunch_checks();
|
|
|
|
nameservers_configured = 1;
|
|
if (nameserver_config_failed) {
|
|
nameserver_config_failed = 0;
|
|
/* XXX the three calls to republish the descriptor might be producing
|
|
* descriptors that are only cosmetically different, especially on
|
|
* non-exit relays! -RD */
|
|
mark_my_descriptor_dirty("dns resolvers back");
|
|
}
|
|
return 0;
|
|
err:
|
|
nameservers_configured = 0;
|
|
if (! nameserver_config_failed) {
|
|
nameserver_config_failed = 1;
|
|
mark_my_descriptor_dirty("dns resolvers failed");
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
/** For eventdns: Called when we get an answer for a request we launched.
|
|
* See eventdns.h for arguments; 'arg' holds the address we tried to resolve.
|
|
*/
|
|
static void
|
|
evdns_callback(int result, char type, int count, int ttl, void *addresses,
|
|
void *arg)
|
|
{
|
|
char *arg_ = arg;
|
|
uint8_t orig_query_type = arg_[0];
|
|
char *string_address = arg_ + 1;
|
|
tor_addr_t addr;
|
|
const char *hostname = NULL;
|
|
int was_wildcarded = 0;
|
|
|
|
tor_addr_make_unspec(&addr);
|
|
|
|
/* Keep track of whether IPv6 is working */
|
|
if (type == DNS_IPv6_AAAA) {
|
|
if (result == DNS_ERR_TIMEOUT) {
|
|
++n_ipv6_timeouts;
|
|
}
|
|
|
|
if (n_ipv6_timeouts > 10 &&
|
|
n_ipv6_timeouts > n_ipv6_requests_made / 2) {
|
|
if (! dns_is_broken_for_ipv6) {
|
|
log_notice(LD_EXIT, "More than half of our IPv6 requests seem to "
|
|
"have timed out. I'm going to assume I can't get AAAA "
|
|
"responses.");
|
|
dns_is_broken_for_ipv6 = 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (result == DNS_ERR_NONE) {
|
|
if (type == DNS_IPv4_A && count) {
|
|
char answer_buf[INET_NTOA_BUF_LEN+1];
|
|
char *escaped_address;
|
|
uint32_t *addrs = addresses;
|
|
tor_addr_from_ipv4n(&addr, addrs[0]);
|
|
|
|
tor_addr_to_str(answer_buf, &addr, sizeof(answer_buf), 0);
|
|
escaped_address = esc_for_log(string_address);
|
|
|
|
if (answer_is_wildcarded(answer_buf)) {
|
|
log_debug(LD_EXIT, "eventdns said that %s resolves to ISP-hijacked "
|
|
"address %s; treating as a failure.",
|
|
safe_str(escaped_address),
|
|
escaped_safe_str(answer_buf));
|
|
was_wildcarded = 1;
|
|
tor_addr_make_unspec(&addr);
|
|
result = DNS_ERR_NOTEXIST;
|
|
} else {
|
|
log_debug(LD_EXIT, "eventdns said that %s resolves to %s",
|
|
safe_str(escaped_address),
|
|
escaped_safe_str(answer_buf));
|
|
}
|
|
tor_free(escaped_address);
|
|
} else if (type == DNS_IPv6_AAAA && count) {
|
|
char answer_buf[TOR_ADDR_BUF_LEN];
|
|
char *escaped_address;
|
|
struct in6_addr *addrs = addresses;
|
|
tor_addr_from_in6(&addr, &addrs[0]);
|
|
tor_inet_ntop(AF_INET6, &addrs[0], answer_buf, sizeof(answer_buf));
|
|
escaped_address = esc_for_log(string_address);
|
|
|
|
if (answer_is_wildcarded(answer_buf)) {
|
|
log_debug(LD_EXIT, "eventdns said that %s resolves to ISP-hijacked "
|
|
"address %s; treating as a failure.",
|
|
safe_str(escaped_address),
|
|
escaped_safe_str(answer_buf));
|
|
was_wildcarded = 1;
|
|
tor_addr_make_unspec(&addr);
|
|
result = DNS_ERR_NOTEXIST;
|
|
} else {
|
|
log_debug(LD_EXIT, "eventdns said that %s resolves to %s",
|
|
safe_str(escaped_address),
|
|
escaped_safe_str(answer_buf));
|
|
}
|
|
tor_free(escaped_address);
|
|
} else if (type == DNS_PTR && count) {
|
|
char *escaped_address;
|
|
hostname = ((char**)addresses)[0];
|
|
escaped_address = esc_for_log(string_address);
|
|
log_debug(LD_EXIT, "eventdns said that %s resolves to %s",
|
|
safe_str(escaped_address),
|
|
escaped_safe_str(hostname));
|
|
tor_free(escaped_address);
|
|
} else if (count) {
|
|
log_warn(LD_EXIT, "eventdns returned only non-IPv4 answers for %s.",
|
|
escaped_safe_str(string_address));
|
|
} else {
|
|
log_warn(LD_BUG, "eventdns returned no addresses or error for %s!",
|
|
escaped_safe_str(string_address));
|
|
}
|
|
}
|
|
if (was_wildcarded) {
|
|
if (is_test_address(string_address)) {
|
|
/* Ick. We're getting redirected on known-good addresses. Our DNS
|
|
* server must really hate us. */
|
|
add_wildcarded_test_address(string_address);
|
|
}
|
|
}
|
|
|
|
if (orig_query_type && type && orig_query_type != type) {
|
|
log_warn(LD_BUG, "Weird; orig_query_type == %d but type == %d",
|
|
(int)orig_query_type, (int)type);
|
|
}
|
|
if (result != DNS_ERR_SHUTDOWN)
|
|
dns_found_answer(string_address, orig_query_type,
|
|
result, &addr, hostname, ttl);
|
|
|
|
tor_free(arg_);
|
|
}
|
|
|
|
/** Start a single DNS resolve for <b>address</b> (if <b>query_type</b> is
|
|
* DNS_IPv4_A or DNS_IPv6_AAAA) <b>ptr_address</b> (if <b>query_type</b> is
|
|
* DNS_PTR). Return 0 if we launched the request, -1 otherwise. */
|
|
static int
|
|
launch_one_resolve(const char *address, uint8_t query_type,
|
|
const tor_addr_t *ptr_address)
|
|
{
|
|
const int options = get_options()->ServerDNSSearchDomains ? 0
|
|
: DNS_QUERY_NO_SEARCH;
|
|
const size_t addr_len = strlen(address);
|
|
struct evdns_request *req = 0;
|
|
char *addr = tor_malloc(addr_len + 2);
|
|
addr[0] = (char) query_type;
|
|
memcpy(addr+1, address, addr_len + 1);
|
|
|
|
switch (query_type) {
|
|
case DNS_IPv4_A:
|
|
req = evdns_base_resolve_ipv4(the_evdns_base,
|
|
address, options, evdns_callback, addr);
|
|
break;
|
|
case DNS_IPv6_AAAA:
|
|
req = evdns_base_resolve_ipv6(the_evdns_base,
|
|
address, options, evdns_callback, addr);
|
|
++n_ipv6_requests_made;
|
|
break;
|
|
case DNS_PTR:
|
|
if (tor_addr_family(ptr_address) == AF_INET)
|
|
req = evdns_base_resolve_reverse(the_evdns_base,
|
|
tor_addr_to_in(ptr_address),
|
|
DNS_QUERY_NO_SEARCH,
|
|
evdns_callback, addr);
|
|
else if (tor_addr_family(ptr_address) == AF_INET6)
|
|
req = evdns_base_resolve_reverse_ipv6(the_evdns_base,
|
|
tor_addr_to_in6(ptr_address),
|
|
DNS_QUERY_NO_SEARCH,
|
|
evdns_callback, addr);
|
|
else
|
|
log_warn(LD_BUG, "Called with PTR query and unexpected address family");
|
|
break;
|
|
default:
|
|
log_warn(LD_BUG, "Called with unexpectd query type %d", (int)query_type);
|
|
break;
|
|
}
|
|
|
|
if (req) {
|
|
return 0;
|
|
} else {
|
|
tor_free(addr);
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/** For eventdns: start resolving as necessary to find the target for
|
|
* <b>exitconn</b>. Returns -1 on error, -2 on transient error,
|
|
* 0 on "resolve launched." */
|
|
static int
|
|
launch_resolve(cached_resolve_t *resolve)
|
|
{
|
|
tor_addr_t a;
|
|
int r;
|
|
|
|
if (get_options()->DisableNetwork)
|
|
return -1;
|
|
|
|
/* What? Nameservers not configured? Sounds like a bug. */
|
|
if (!nameservers_configured) {
|
|
log_warn(LD_EXIT, "(Harmless.) Nameservers not configured, but resolve "
|
|
"launched. Configuring.");
|
|
if (configure_nameservers(1) < 0) {
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
r = tor_addr_parse_PTR_name(
|
|
&a, resolve->address, AF_UNSPEC, 0);
|
|
|
|
tor_assert(the_evdns_base);
|
|
if (r == 0) {
|
|
log_info(LD_EXIT, "Launching eventdns request for %s",
|
|
escaped_safe_str(resolve->address));
|
|
resolve->res_status_ipv4 = RES_STATUS_INFLIGHT;
|
|
if (get_options()->IPv6Exit)
|
|
resolve->res_status_ipv6 = RES_STATUS_INFLIGHT;
|
|
|
|
if (launch_one_resolve(resolve->address, DNS_IPv4_A, NULL) < 0) {
|
|
resolve->res_status_ipv4 = 0;
|
|
r = -1;
|
|
}
|
|
|
|
if (r==0 && get_options()->IPv6Exit) {
|
|
/* We ask for an IPv6 address for *everything*. */
|
|
if (launch_one_resolve(resolve->address, DNS_IPv6_AAAA, NULL) < 0) {
|
|
resolve->res_status_ipv6 = 0;
|
|
r = -1;
|
|
}
|
|
}
|
|
} else if (r == 1) {
|
|
r = 0;
|
|
log_info(LD_EXIT, "Launching eventdns reverse request for %s",
|
|
escaped_safe_str(resolve->address));
|
|
resolve->res_status_hostname = RES_STATUS_INFLIGHT;
|
|
if (launch_one_resolve(resolve->address, DNS_PTR, &a) < 0) {
|
|
resolve->res_status_hostname = 0;
|
|
r = -1;
|
|
}
|
|
} else if (r == -1) {
|
|
log_warn(LD_BUG, "Somehow a malformed in-addr.arpa address reached here.");
|
|
}
|
|
|
|
if (r < 0) {
|
|
log_fn(LOG_PROTOCOL_WARN, LD_EXIT, "eventdns rejected address %s.",
|
|
escaped_safe_str(resolve->address));
|
|
}
|
|
return r;
|
|
}
|
|
|
|
/** How many requests for bogus addresses have we launched so far? */
|
|
static int n_wildcard_requests = 0;
|
|
|
|
/** Map from dotted-quad IP address in response to an int holding how many
|
|
* times we've seen it for a randomly generated (hopefully bogus) address. It
|
|
* would be easier to use definitely-invalid addresses (as specified by
|
|
* RFC2606), but see comment in dns_launch_wildcard_checks(). */
|
|
static strmap_t *dns_wildcard_response_count = NULL;
|
|
|
|
/** If present, a list of dotted-quad IP addresses that we are pretty sure our
|
|
* nameserver wants to return in response to requests for nonexistent domains.
|
|
*/
|
|
static smartlist_t *dns_wildcard_list = NULL;
|
|
/** True iff we've logged about a single address getting wildcarded.
|
|
* Subsequent warnings will be less severe. */
|
|
static int dns_wildcard_one_notice_given = 0;
|
|
/** True iff we've warned that our DNS server is wildcarding too many failures.
|
|
*/
|
|
static int dns_wildcard_notice_given = 0;
|
|
|
|
/** List of supposedly good addresses that are getting wildcarded to the
|
|
* same addresses as nonexistent addresses. */
|
|
static smartlist_t *dns_wildcarded_test_address_list = NULL;
|
|
/** True iff we've warned about a test address getting wildcarded */
|
|
static int dns_wildcarded_test_address_notice_given = 0;
|
|
/** True iff all addresses seem to be getting wildcarded. */
|
|
static int dns_is_completely_invalid = 0;
|
|
|
|
/** Called when we see <b>id</b> (a dotted quad or IPv6 address) in response
|
|
* to a request for a hopefully bogus address. */
|
|
static void
|
|
wildcard_increment_answer(const char *id)
|
|
{
|
|
int *ip;
|
|
if (!dns_wildcard_response_count)
|
|
dns_wildcard_response_count = strmap_new();
|
|
|
|
ip = strmap_get(dns_wildcard_response_count, id); // may be null (0)
|
|
if (!ip) {
|
|
ip = tor_malloc_zero(sizeof(int));
|
|
strmap_set(dns_wildcard_response_count, id, ip);
|
|
}
|
|
++*ip;
|
|
|
|
if (*ip > 5 && n_wildcard_requests > 10) {
|
|
if (!dns_wildcard_list) dns_wildcard_list = smartlist_new();
|
|
if (!smartlist_contains_string(dns_wildcard_list, id)) {
|
|
tor_log(dns_wildcard_notice_given ? LOG_INFO : LOG_NOTICE, LD_EXIT,
|
|
"Your DNS provider has given \"%s\" as an answer for %d different "
|
|
"invalid addresses. Apparently they are hijacking DNS failures. "
|
|
"I'll try to correct for this by treating future occurrences of "
|
|
"\"%s\" as 'not found'.", id, *ip, id);
|
|
smartlist_add(dns_wildcard_list, tor_strdup(id));
|
|
}
|
|
if (!dns_wildcard_notice_given)
|
|
control_event_server_status(LOG_NOTICE, "DNS_HIJACKED");
|
|
dns_wildcard_notice_given = 1;
|
|
}
|
|
}
|
|
|
|
/** Note that a single test address (one believed to be good) seems to be
|
|
* getting redirected to the same IP as failures are. */
|
|
static void
|
|
add_wildcarded_test_address(const char *address)
|
|
{
|
|
int n, n_test_addrs;
|
|
if (!dns_wildcarded_test_address_list)
|
|
dns_wildcarded_test_address_list = smartlist_new();
|
|
|
|
if (smartlist_contains_string_case(dns_wildcarded_test_address_list,
|
|
address))
|
|
return;
|
|
|
|
n_test_addrs = get_options()->ServerDNSTestAddresses ?
|
|
smartlist_len(get_options()->ServerDNSTestAddresses) : 0;
|
|
|
|
smartlist_add(dns_wildcarded_test_address_list, tor_strdup(address));
|
|
n = smartlist_len(dns_wildcarded_test_address_list);
|
|
if (n > n_test_addrs/2) {
|
|
tor_log(dns_wildcarded_test_address_notice_given ? LOG_INFO : LOG_NOTICE,
|
|
LD_EXIT, "Your DNS provider tried to redirect \"%s\" to a junk "
|
|
"address. It has done this with %d test addresses so far. I'm "
|
|
"going to stop being an exit node for now, since our DNS seems so "
|
|
"broken.", address, n);
|
|
if (!dns_is_completely_invalid) {
|
|
dns_is_completely_invalid = 1;
|
|
mark_my_descriptor_dirty("dns hijacking confirmed");
|
|
}
|
|
if (!dns_wildcarded_test_address_notice_given)
|
|
control_event_server_status(LOG_WARN, "DNS_USELESS");
|
|
dns_wildcarded_test_address_notice_given = 1;
|
|
}
|
|
}
|
|
|
|
/** Callback function when we get an answer (possibly failing) for a request
|
|
* for a (hopefully) nonexistent domain. */
|
|
static void
|
|
evdns_wildcard_check_callback(int result, char type, int count, int ttl,
|
|
void *addresses, void *arg)
|
|
{
|
|
(void)ttl;
|
|
++n_wildcard_requests;
|
|
if (result == DNS_ERR_NONE && count) {
|
|
char *string_address = arg;
|
|
int i;
|
|
if (type == DNS_IPv4_A) {
|
|
const uint32_t *addrs = addresses;
|
|
for (i = 0; i < count; ++i) {
|
|
char answer_buf[INET_NTOA_BUF_LEN+1];
|
|
struct in_addr in;
|
|
in.s_addr = addrs[i];
|
|
tor_inet_ntoa(&in, answer_buf, sizeof(answer_buf));
|
|
wildcard_increment_answer(answer_buf);
|
|
}
|
|
} else if (type == DNS_IPv6_AAAA) {
|
|
const struct in6_addr *addrs = addresses;
|
|
for (i = 0; i < count; ++i) {
|
|
char answer_buf[TOR_ADDR_BUF_LEN+1];
|
|
tor_inet_ntop(AF_INET6, &addrs[i], answer_buf, sizeof(answer_buf));
|
|
wildcard_increment_answer(answer_buf);
|
|
}
|
|
}
|
|
|
|
tor_log(dns_wildcard_one_notice_given ? LOG_INFO : LOG_NOTICE, LD_EXIT,
|
|
"Your DNS provider gave an answer for \"%s\", which "
|
|
"is not supposed to exist. Apparently they are hijacking "
|
|
"DNS failures. Trying to correct for this. We've noticed %d "
|
|
"possibly bad address%s so far.",
|
|
string_address, strmap_size(dns_wildcard_response_count),
|
|
(strmap_size(dns_wildcard_response_count) == 1) ? "" : "es");
|
|
dns_wildcard_one_notice_given = 1;
|
|
}
|
|
tor_free(arg);
|
|
}
|
|
|
|
/** Launch a single request for a nonexistent hostname consisting of between
|
|
* <b>min_len</b> and <b>max_len</b> random (plausible) characters followed by
|
|
* <b>suffix</b> */
|
|
static void
|
|
launch_wildcard_check(int min_len, int max_len, int is_ipv6,
|
|
const char *suffix)
|
|
{
|
|
char *addr;
|
|
struct evdns_request *req;
|
|
|
|
addr = crypto_random_hostname(min_len, max_len, "", suffix);
|
|
log_info(LD_EXIT, "Testing whether our DNS server is hijacking nonexistent "
|
|
"domains with request for bogus hostname \"%s\"", addr);
|
|
|
|
tor_assert(the_evdns_base);
|
|
if (is_ipv6)
|
|
req = evdns_base_resolve_ipv6(
|
|
the_evdns_base,
|
|
/* This "addr" tells us which address to resolve */
|
|
addr,
|
|
DNS_QUERY_NO_SEARCH, evdns_wildcard_check_callback,
|
|
/* This "addr" is an argument to the callback*/ addr);
|
|
else
|
|
req = evdns_base_resolve_ipv4(
|
|
the_evdns_base,
|
|
/* This "addr" tells us which address to resolve */
|
|
addr,
|
|
DNS_QUERY_NO_SEARCH, evdns_wildcard_check_callback,
|
|
/* This "addr" is an argument to the callback*/ addr);
|
|
if (!req) {
|
|
/* There is no evdns request in progress; stop addr from getting leaked */
|
|
tor_free(addr);
|
|
}
|
|
}
|
|
|
|
/** Launch attempts to resolve a bunch of known-good addresses (configured in
|
|
* ServerDNSTestAddresses). [Callback for a libevent timer] */
|
|
static void
|
|
launch_test_addresses(evutil_socket_t fd, short event, void *args)
|
|
{
|
|
const or_options_t *options = get_options();
|
|
(void)fd;
|
|
(void)event;
|
|
(void)args;
|
|
|
|
if (options->DisableNetwork)
|
|
return;
|
|
|
|
log_info(LD_EXIT, "Launching checks to see whether our nameservers like to "
|
|
"hijack *everything*.");
|
|
/* This situation is worse than the failure-hijacking situation. When this
|
|
* happens, we're no good for DNS requests at all, and we shouldn't really
|
|
* be an exit server.*/
|
|
if (options->ServerDNSTestAddresses) {
|
|
|
|
tor_assert(the_evdns_base);
|
|
SMARTLIST_FOREACH_BEGIN(options->ServerDNSTestAddresses,
|
|
const char *, address) {
|
|
if (launch_one_resolve(address, DNS_IPv4_A, NULL) < 0) {
|
|
log_info(LD_EXIT, "eventdns rejected test address %s",
|
|
escaped_safe_str(address));
|
|
}
|
|
|
|
if (launch_one_resolve(address, DNS_IPv6_AAAA, NULL) < 0) {
|
|
log_info(LD_EXIT, "eventdns rejected test address %s",
|
|
escaped_safe_str(address));
|
|
}
|
|
} SMARTLIST_FOREACH_END(address);
|
|
}
|
|
}
|
|
|
|
#define N_WILDCARD_CHECKS 2
|
|
|
|
/** Launch DNS requests for a few nonexistent hostnames and a few well-known
|
|
* hostnames, and see if we can catch our nameserver trying to hijack them and
|
|
* map them to a stupid "I couldn't find ggoogle.com but maybe you'd like to
|
|
* buy these lovely encyclopedias" page. */
|
|
static void
|
|
dns_launch_wildcard_checks(void)
|
|
{
|
|
int i, ipv6;
|
|
log_info(LD_EXIT, "Launching checks to see whether our nameservers like "
|
|
"to hijack DNS failures.");
|
|
for (ipv6 = 0; ipv6 <= 1; ++ipv6) {
|
|
for (i = 0; i < N_WILDCARD_CHECKS; ++i) {
|
|
/* RFC2606 reserves these. Sadly, some DNS hijackers, in a silly
|
|
* attempt to 'comply' with rfc2606, refrain from giving A records for
|
|
* these. This is the standards-compliance equivalent of making sure
|
|
* that your crackhouse's elevator inspection certificate is up to date.
|
|
*/
|
|
launch_wildcard_check(2, 16, ipv6, ".invalid");
|
|
launch_wildcard_check(2, 16, ipv6, ".test");
|
|
|
|
/* These will break specs if there are ever any number of
|
|
* 8+-character top-level domains. */
|
|
launch_wildcard_check(8, 16, ipv6, "");
|
|
|
|
/* Try some random .com/org/net domains. This will work fine so long as
|
|
* not too many resolve to the same place. */
|
|
launch_wildcard_check(8, 16, ipv6, ".com");
|
|
launch_wildcard_check(8, 16, ipv6, ".org");
|
|
launch_wildcard_check(8, 16, ipv6, ".net");
|
|
}
|
|
}
|
|
}
|
|
|
|
/** If appropriate, start testing whether our DNS servers tend to lie to
|
|
* us. */
|
|
void
|
|
dns_launch_correctness_checks(void)
|
|
{
|
|
static struct event *launch_event = NULL;
|
|
struct timeval timeout;
|
|
if (!get_options()->ServerDNSDetectHijacking)
|
|
return;
|
|
dns_launch_wildcard_checks();
|
|
|
|
/* Wait a while before launching requests for test addresses, so we can
|
|
* get the results from checking for wildcarding. */
|
|
if (! launch_event)
|
|
launch_event = tor_evtimer_new(tor_libevent_get_base(),
|
|
launch_test_addresses, NULL);
|
|
timeout.tv_sec = 30;
|
|
timeout.tv_usec = 0;
|
|
if (evtimer_add(launch_event, &timeout)<0) {
|
|
log_warn(LD_BUG, "Couldn't add timer for checking for dns hijacking");
|
|
}
|
|
}
|
|
|
|
/** Return true iff our DNS servers lie to us too much to be trusted. */
|
|
int
|
|
dns_seems_to_be_broken(void)
|
|
{
|
|
return dns_is_completely_invalid;
|
|
}
|
|
|
|
/** Return true iff we think that IPv6 hostname lookup is broken */
|
|
int
|
|
dns_seems_to_be_broken_for_ipv6(void)
|
|
{
|
|
return dns_is_broken_for_ipv6;
|
|
}
|
|
|
|
/** Forget what we've previously learned about our DNS servers' correctness. */
|
|
void
|
|
dns_reset_correctness_checks(void)
|
|
{
|
|
strmap_free(dns_wildcard_response_count, tor_free_);
|
|
dns_wildcard_response_count = NULL;
|
|
|
|
n_wildcard_requests = 0;
|
|
|
|
n_ipv6_requests_made = n_ipv6_timeouts = 0;
|
|
|
|
if (dns_wildcard_list) {
|
|
SMARTLIST_FOREACH(dns_wildcard_list, char *, cp, tor_free(cp));
|
|
smartlist_clear(dns_wildcard_list);
|
|
}
|
|
if (dns_wildcarded_test_address_list) {
|
|
SMARTLIST_FOREACH(dns_wildcarded_test_address_list, char *, cp,
|
|
tor_free(cp));
|
|
smartlist_clear(dns_wildcarded_test_address_list);
|
|
}
|
|
dns_wildcard_one_notice_given = dns_wildcard_notice_given =
|
|
dns_wildcarded_test_address_notice_given = dns_is_completely_invalid =
|
|
dns_is_broken_for_ipv6 = 0;
|
|
}
|
|
|
|
/** Return true iff we have noticed that the dotted-quad <b>ip</b> has been
|
|
* returned in response to requests for nonexistent hostnames. */
|
|
static int
|
|
answer_is_wildcarded(const char *ip)
|
|
{
|
|
return dns_wildcard_list && smartlist_contains_string(dns_wildcard_list, ip);
|
|
}
|
|
|
|
/** Exit with an assertion if <b>resolve</b> is corrupt. */
|
|
static void
|
|
assert_resolve_ok(cached_resolve_t *resolve)
|
|
{
|
|
tor_assert(resolve);
|
|
tor_assert(resolve->magic == CACHED_RESOLVE_MAGIC);
|
|
tor_assert(strlen(resolve->address) < MAX_ADDRESSLEN);
|
|
tor_assert(tor_strisnonupper(resolve->address));
|
|
if (resolve->state != CACHE_STATE_PENDING) {
|
|
tor_assert(!resolve->pending_connections);
|
|
}
|
|
if (resolve->state == CACHE_STATE_PENDING ||
|
|
resolve->state == CACHE_STATE_DONE) {
|
|
#if 0
|
|
tor_assert(!resolve->ttl);
|
|
if (resolve->is_reverse)
|
|
tor_assert(!resolve->hostname);
|
|
else
|
|
tor_assert(!resolve->result_ipv4.addr_ipv4);
|
|
#endif
|
|
/*XXXXX ADD MORE */
|
|
}
|
|
}
|
|
|
|
/** Return the number of DNS cache entries as an int */
|
|
static int
|
|
dns_cache_entry_count(void)
|
|
{
|
|
return HT_SIZE(&cache_root);
|
|
}
|
|
|
|
/** Log memory information about our internal DNS cache at level 'severity'. */
|
|
void
|
|
dump_dns_mem_usage(int severity)
|
|
{
|
|
/* This should never be larger than INT_MAX. */
|
|
int hash_count = dns_cache_entry_count();
|
|
size_t hash_mem = sizeof(struct cached_resolve_t) * hash_count;
|
|
hash_mem += HT_MEM_USAGE(&cache_root);
|
|
|
|
/* Print out the count and estimated size of our &cache_root. It undercounts
|
|
hostnames in cached reverse resolves.
|
|
*/
|
|
tor_log(severity, LD_MM, "Our DNS cache has %d entries.", hash_count);
|
|
tor_log(severity, LD_MM, "Our DNS cache size is approximately %u bytes.",
|
|
(unsigned)hash_mem);
|
|
}
|
|
|
|
#ifdef DEBUG_DNS_CACHE
|
|
/** Exit with an assertion if the DNS cache is corrupt. */
|
|
static void
|
|
assert_cache_ok_(void)
|
|
{
|
|
cached_resolve_t **resolve;
|
|
int bad_rep = _cache_map_HT_REP_IS_BAD(&cache_root);
|
|
if (bad_rep) {
|
|
log_err(LD_BUG, "Bad rep type %d on dns cache hash table", bad_rep);
|
|
tor_assert(!bad_rep);
|
|
}
|
|
|
|
HT_FOREACH(resolve, cache_map, &cache_root) {
|
|
assert_resolve_ok(*resolve);
|
|
tor_assert((*resolve)->state != CACHE_STATE_DONE);
|
|
}
|
|
if (!cached_resolve_pqueue)
|
|
return;
|
|
|
|
smartlist_pqueue_assert_ok(cached_resolve_pqueue,
|
|
compare_cached_resolves_by_expiry_,
|
|
STRUCT_OFFSET(cached_resolve_t, minheap_idx));
|
|
|
|
SMARTLIST_FOREACH(cached_resolve_pqueue, cached_resolve_t *, res,
|
|
{
|
|
if (res->state == CACHE_STATE_DONE) {
|
|
cached_resolve_t *found = HT_FIND(cache_map, &cache_root, res);
|
|
tor_assert(!found || found != res);
|
|
} else {
|
|
cached_resolve_t *found = HT_FIND(cache_map, &cache_root, res);
|
|
tor_assert(found);
|
|
}
|
|
});
|
|
}
|
|
#endif
|
|
|