mirror of
https://gitlab.torproject.org/tpo/core/tor.git
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8138d1c0a4
I bet real programmers even have programs that compile. svn:r8278
1431 lines
46 KiB
C
1431 lines
46 KiB
C
/* Copyright 2003-2004 Roger Dingledine.
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* Copyright 2004-2006 Roger Dingledine, Nick Mathewson. */
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/* See LICENSE for licensing information */
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/* $Id$ */
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const char dns_c_id[] =
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"$Id$";
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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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* We provide two asynchronous backend implementations:
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* 1) A farm of 'DNS worker' threads or processes to perform DNS lookups for
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* onion routers and cache the results.
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* 2) A wrapper around Adam Langley's eventdns.c code, to send requests
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* to the nameservers asynchronously.
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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 "../common/ht.h"
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#ifdef USE_EVENTDNS
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#include "eventdns.h"
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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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/** Maximum DNS processes to spawn. */
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#define MAX_DNSWORKERS 100
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/** Minimum DNS processes to spawn. */
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#define MIN_DNSWORKERS 3
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/** If more than this many processes are idle, shut down the extras. */
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#define MAX_IDLE_DNSWORKERS 10
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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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/** Possible outcomes from hostname lookup: permanent failure,
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* transient (retryable) failure, and success. */
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#define DNS_RESOLVE_FAILED_TRANSIENT 1
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#define DNS_RESOLVE_FAILED_PERMANENT 2
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#define DNS_RESOLVE_SUCCEEDED 3
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#ifndef USE_EVENTDNS
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/** How many dnsworkers we have running right now. */
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static int num_dnsworkers=0;
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/** How many of the running dnsworkers have an assigned task right now. */
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static int num_dnsworkers_busy=0;
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/** When did we last rotate the dnsworkers? */
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static time_t last_rotation_time=0;
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#else
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/** Have we currently configured nameservers with eventdns? */
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static int nameservers_configured = 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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#endif
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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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#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_VALID or a CACHED_FAILED
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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_VALID 2
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/** We are caching a failure 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_FAILED 3
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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;
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char address[MAX_ADDRESSLEN]; /**< The hostname to be resolved. */
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uint32_t addr; /**< IPv4 addr for <b>address</b>. */
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uint8_t state; /**< Is this cached entry pending/done/valid/failed? */
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time_t expire; /**< Remove items from cache after this time. */
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uint32_t ttl; /**< 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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} 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, uint32_t addr, char outcome,
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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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static int launch_resolve(edge_connection_t *exitconn);
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#ifndef USE_EVENTDNS
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static void dnsworkers_rotate(void);
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static int dnsworker_main(void *data);
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static int spawn_dnsworker(void);
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static int spawn_enough_dnsworkers(void);
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#else
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static int configure_nameservers(int force);
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#endif
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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() do {} while (0)
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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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/** 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_root);
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}
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#ifdef USE_EVENTDNS
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/** Helper: called by eventdns when eventdns wants to log something. */
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static void
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eventdns_log_cb(int warn, const char *msg)
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{
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if (!strcmpstart(msg, "Resolve requested for") &&
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get_options()->SafeLogging) {
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log(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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log(warn?LOG_WARN:LOG_INFO, LD_EXIT, "eventdns: %s", msg);
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}
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#endif
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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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#ifdef USE_EVENTDNS
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if (server_mode(get_options()))
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return configure_nameservers(1);
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#else
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dnsworkers_rotate();
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#endif
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return 0;
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}
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/** Called when DNS-related options change (or may have changed) */
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void
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dns_reset(void)
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{
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#ifdef USE_EVENTDNS
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or_options_t *options = get_options();
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if (! server_mode(options)) {
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eventdns_clear_nameservers_and_suspend();
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eventdns_search_clear();
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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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/* XXXX */
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return;
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}
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#else
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dnsworkers_rotate();
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#endif
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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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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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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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return a->expire - b->expire;
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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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/** Set an expiry time for a cached_resolve_t, and add it to the expiry
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* priority queue */
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static void
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set_expiry(cached_resolve_t *resolve, time_t expires)
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{
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tor_assert(resolve && resolve->expire == 0);
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if (!cached_resolve_pqueue)
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cached_resolve_pqueue = smartlist_create();
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resolve->expire = expires;
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smartlist_pqueue_add(cached_resolve_pqueue,
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_compare_cached_resolves_by_expiry,
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resolve);
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}
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/** Free all storage held in the DNS cache and related structures. */
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void
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dns_free_all(void)
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{
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cached_resolve_t **ptr, **next, *item;
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for (ptr = HT_START(cache_map, &cache_root); ptr != NULL; ptr = next) {
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item = *ptr;
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next = HT_NEXT_RMV(cache_map, &cache_root, ptr);
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_free_cached_resolve(item);
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}
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HT_CLEAR(cache_map, &cache_root);
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if (cached_resolve_pqueue)
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smartlist_free(cached_resolve_pqueue);
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cached_resolve_pqueue = NULL;
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#ifdef USE_EVENTDNS
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tor_free(resolv_conf_fname);
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#endif
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}
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/** Remove every cached_resolve whose <b>expire</b> time is before <b>now</b>
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* from the cache. */
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static void
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purge_expired_resolves(time_t now)
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{
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cached_resolve_t *resolve, *removed;
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pending_connection_t *pend;
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edge_connection_t *pendconn;
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assert_cache_ok();
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if (!cached_resolve_pqueue)
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return;
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while (smartlist_len(cached_resolve_pqueue)) {
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resolve = smartlist_get(cached_resolve_pqueue, 0);
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if (resolve->expire > now)
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break;
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smartlist_pqueue_pop(cached_resolve_pqueue,
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_compare_cached_resolves_by_expiry);
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if (resolve->state == CACHE_STATE_PENDING) {
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log_debug(LD_EXIT,
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"Expiring a dns resolve %s that's still pending. Forgot to "
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"cull it? DNS resolve didn't tell us about the timeout?",
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escaped_safe_str(resolve->address));
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} else if (resolve->state == CACHE_STATE_CACHED_VALID ||
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resolve->state == CACHE_STATE_CACHED_FAILED) {
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log_debug(LD_EXIT,
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"Forgetting old cached resolve (address %s, expires %lu)",
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escaped_safe_str(resolve->address),
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(unsigned long)resolve->expire);
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tor_assert(!resolve->pending_connections);
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} else {
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tor_assert(resolve->state == CACHE_STATE_DONE);
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tor_assert(!resolve->pending_connections);
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}
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if (resolve->pending_connections) {
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log_debug(LD_EXIT,
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"Closing pending connections on timed-out DNS resolve!");
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tor_fragile_assert();
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while (resolve->pending_connections) {
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pend = resolve->pending_connections;
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resolve->pending_connections = pend->next;
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/* Connections should only be pending if they have no socket. */
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tor_assert(pend->conn->_base.s == -1);
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pendconn = pend->conn;
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connection_edge_end(pendconn, END_STREAM_REASON_TIMEOUT,
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pendconn->cpath_layer);
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circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
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connection_free(TO_CONN(pendconn));
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tor_free(pend);
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}
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}
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if (resolve->state == CACHE_STATE_CACHED_VALID ||
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resolve->state == CACHE_STATE_CACHED_FAILED ||
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resolve->state == CACHE_STATE_PENDING) {
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removed = HT_REMOVE(cache_map, &cache_root, resolve);
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if (removed != resolve) {
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log_err(LD_BUG, "The expired resolve we purged didn't match any in"
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" the cache. Tried to purge %s (%p); instead got %s (%p).",
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resolve->address, (void*)resolve,
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removed ? removed->address : "NULL", (void*)remove);
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}
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tor_assert(removed == resolve);
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resolve->magic = 0xF0BBF0BB;
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tor_free(resolve);
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} else {
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/* This should be in state DONE. Make sure it's not in the cache. */
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cached_resolve_t *tmp = HT_FIND(cache_map, &cache_root, resolve);
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tor_assert(tmp != resolve);
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}
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}
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assert_cache_ok();
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}
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/** Send a response to the RESOLVE request of a connection. answer_type must
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* be one of RESOLVED_TYPE_(IPV4|ERROR|ERROR_TRANSIENT) */
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static void
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send_resolved_cell(edge_connection_t *conn, uint8_t answer_type)
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{
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char buf[RELAY_PAYLOAD_SIZE];
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size_t buflen;
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uint32_t ttl;
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buf[0] = answer_type;
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ttl = dns_clip_ttl(conn->address_ttl);
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switch (answer_type)
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{
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case RESOLVED_TYPE_IPV4:
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buf[1] = 4;
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set_uint32(buf+2, htonl(conn->_base.addr));
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set_uint32(buf+6, htonl(ttl));
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buflen = 10;
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break;
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case RESOLVED_TYPE_ERROR_TRANSIENT:
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case RESOLVED_TYPE_ERROR:
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{
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const char *errmsg = "Error resolving hostname";
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int msglen = strlen(errmsg);
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buf[1] = msglen;
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strlcpy(buf+2, errmsg, sizeof(buf)-2);
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set_uint32(buf+2+msglen, htonl(ttl));
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buflen = 6+msglen;
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break;
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}
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default:
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tor_assert(0);
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return;
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}
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connection_edge_send_command(conn, circuit_get_by_edge_conn(conn),
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RELAY_COMMAND_RESOLVED, buf, buflen,
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conn->cpath_layer);
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}
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/** See if we have a cache entry for <b>exitconn</b>-\>address. if so,
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* if resolve valid, put it into <b>exitconn</b>-\>addr and return 1.
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* If resolve failed, unlink exitconn if needed, free it, and return -1.
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*
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* Else, if seen before and pending, add conn to the pending list,
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* and return 0.
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*
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* Else, if not seen before, add conn to pending list, hand to
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* dns farm, and return 0.
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*/
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int
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dns_resolve(edge_connection_t *exitconn)
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{
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cached_resolve_t *resolve;
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cached_resolve_t search;
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pending_connection_t *pending_connection;
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struct in_addr in;
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circuit_t *circ;
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time_t now = time(NULL);
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assert_connection_ok(TO_CONN(exitconn), 0);
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tor_assert(exitconn->_base.s == -1);
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assert_cache_ok();
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/* first check if exitconn->_base.address is an IP. If so, we already
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* know the answer. */
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if (tor_inet_aton(exitconn->_base.address, &in) != 0) {
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exitconn->_base.addr = ntohl(in.s_addr);
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exitconn->address_ttl = DEFAULT_DNS_TTL;
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if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
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send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
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return 1;
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}
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/* then take this opportunity to see if there are any expired
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* resolves in the hash table. */
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purge_expired_resolves(now);
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/* lower-case exitconn->_base.address, so it's in canonical form */
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tor_strlower(exitconn->_base.address);
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/* now check the hash table to see if 'address' is already there. */
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strlcpy(search.address, exitconn->_base.address, sizeof(search.address));
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resolve = HT_FIND(cache_map, &cache_root, &search);
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if (resolve && resolve->expire > now) { /* already there */
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switch (resolve->state) {
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case CACHE_STATE_PENDING:
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/* add us to the pending list */
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pending_connection = tor_malloc_zero(
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sizeof(pending_connection_t));
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pending_connection->conn = exitconn;
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pending_connection->next = resolve->pending_connections;
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resolve->pending_connections = pending_connection;
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log_debug(LD_EXIT,"Connection (fd %d) waiting for pending DNS "
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"resolve of %s", exitconn->_base.s,
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escaped_safe_str(exitconn->_base.address));
|
|
exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
|
|
return 0;
|
|
case CACHE_STATE_CACHED_VALID:
|
|
exitconn->_base.addr = resolve->addr;
|
|
exitconn->address_ttl = resolve->ttl;
|
|
log_debug(LD_EXIT,"Connection (fd %d) found cached answer for %s",
|
|
exitconn->_base.s,
|
|
escaped_safe_str(exitconn->_base.address));
|
|
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
|
|
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
|
|
return 1;
|
|
case CACHE_STATE_CACHED_FAILED:
|
|
log_debug(LD_EXIT,"Connection (fd %d) found cached error for %s",
|
|
exitconn->_base.s,
|
|
escaped_safe_str(exitconn->_base.address));
|
|
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
|
|
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
|
|
circ = circuit_get_by_edge_conn(exitconn);
|
|
if (circ)
|
|
circuit_detach_stream(circ, exitconn);
|
|
if (!exitconn->_base.marked_for_close)
|
|
connection_free(TO_CONN(exitconn));
|
|
return -1;
|
|
case CACHE_STATE_DONE:
|
|
log_err(LD_BUG, "Found a 'DONE' dns resolve still in the cache.");
|
|
tor_fragile_assert();
|
|
}
|
|
tor_assert(0);
|
|
}
|
|
/* not there, need to add it */
|
|
resolve = tor_malloc_zero(sizeof(cached_resolve_t));
|
|
resolve->magic = CACHED_RESOLVE_MAGIC;
|
|
resolve->state = CACHE_STATE_PENDING;
|
|
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;
|
|
exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
|
|
|
|
/* 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(exitconn);
|
|
}
|
|
|
|
/** 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 **resolve;
|
|
|
|
HT_FOREACH(resolve, cache_map, &cache_root) {
|
|
for (pend = (*resolve)->pending_connections;
|
|
pend;
|
|
pend = pend->next) {
|
|
tor_assert(pend->conn != conn);
|
|
}
|
|
}
|
|
}
|
|
|
|
/** 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(pend->conn->_base.s == -1);
|
|
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 %d) 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 %d) no longer waiting for resolve of %s",
|
|
conn->_base.s, escaped_safe_str(conn->_base.address));
|
|
return; /* more are pending */
|
|
}
|
|
}
|
|
tor_assert(0); /* not reachable unless onlyconn not in pending list */
|
|
}
|
|
}
|
|
|
|
/** 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(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 || resolve->state != CACHE_STATE_PENDING) {
|
|
log_notice(LD_BUG,"Address %s is not pending. Dropping.",
|
|
escaped_safe_str(address));
|
|
return;
|
|
}
|
|
|
|
if (!resolve->pending_connections) {
|
|
/* XXX this should never trigger, but sometimes it does */
|
|
log_warn(LD_BUG,
|
|
"Bug: Address %s is pending but has no pending connections!",
|
|
escaped_safe_str(address));
|
|
tor_fragile_assert();
|
|
return;
|
|
}
|
|
tor_assert(resolve->pending_connections);
|
|
tor_assert(! resolve->expire);
|
|
|
|
/* 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(pendconn->_base.s == -1);
|
|
if (!pendconn->_base.marked_for_close) {
|
|
connection_edge_end(pendconn, END_STREAM_REASON_RESOURCELIMIT,
|
|
pendconn->cpath_layer);
|
|
}
|
|
circ = circuit_get_by_edge_conn(pendconn);
|
|
if (circ)
|
|
circuit_detach_stream(circ, pendconn);
|
|
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->magic = 0xABABABAB;
|
|
tor_free(resolve);
|
|
}
|
|
|
|
/** Helper: adds an entry to the DNS cache mapping <b>address</b> to the ipv4
|
|
* address 'addr'. 'ttl is a cache ttl; 'outcome' is one of
|
|
* DNS_RESOLVE_{FAILED_TRANSIENT|FAILED_PERMANENT|SUCCEEDED}. */
|
|
static void
|
|
add_answer_to_cache(const char *address, uint32_t addr, char outcome,
|
|
uint32_t ttl)
|
|
{
|
|
cached_resolve_t *resolve;
|
|
if (outcome == DNS_RESOLVE_FAILED_TRANSIENT)
|
|
return;
|
|
|
|
resolve = tor_malloc_zero(sizeof(cached_resolve_t));
|
|
resolve->magic = CACHED_RESOLVE_MAGIC;
|
|
resolve->state = (outcome == DNS_RESOLVE_SUCCEEDED) ?
|
|
CACHE_STATE_CACHED_VALID : CACHE_STATE_CACHED_FAILED;
|
|
strlcpy(resolve->address, address, sizeof(resolve->address));
|
|
resolve->addr = addr;
|
|
resolve->ttl = ttl;
|
|
assert_resolve_ok(resolve);
|
|
HT_INSERT(cache_map, &cache_root, resolve);
|
|
set_expiry(resolve, time(NULL) + dns_get_expiry_ttl(ttl));
|
|
}
|
|
|
|
/** Called on the OR side when a DNS worker or the eventdns library tells us
|
|
* the outcome of a DNS resolve: tell all pending connections about the result
|
|
* of the lookup, and cache the value. (<b>address</b> is a NUL-terminated
|
|
* string containing the address to look up; <b>addr</b> is an IPv4 address in
|
|
* host order; <b>outcome</b> is one of
|
|
* DNS_RESOLVE_{FAILED_TRANSIENT|FAILED_PERMANENT|SUCCEEDED}.
|
|
*/
|
|
static void
|
|
dns_found_answer(const char *address, uint32_t addr, char outcome,
|
|
uint32_t ttl)
|
|
{
|
|
pending_connection_t *pend;
|
|
cached_resolve_t search;
|
|
cached_resolve_t *resolve, *removed;
|
|
edge_connection_t *pendconn;
|
|
circuit_t *circ;
|
|
|
|
assert_cache_ok();
|
|
|
|
strlcpy(search.address, address, sizeof(search.address));
|
|
|
|
resolve = HT_FIND(cache_map, &cache_root, &search);
|
|
if (!resolve) {
|
|
log_info(LD_EXIT,"Resolved unasked address %s; caching anyway.",
|
|
escaped_safe_str(address));
|
|
add_answer_to_cache(address, addr, outcome, ttl);
|
|
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? */
|
|
log_notice(LD_EXIT, "Resolved %s which was already resolved; ignoring",
|
|
escaped_safe_str(address));
|
|
tor_assert(resolve->pending_connections == NULL);
|
|
return;
|
|
}
|
|
/* Removed this assertion: in fact, we'll sometimes get a double answer
|
|
* to the same question. This can happen when we ask one worker to resolve
|
|
* X.Y.Z., then we cancel the request, and then we ask another worker to
|
|
* resolve X.Y.Z. */
|
|
/* tor_assert(resolve->state == CACHE_STATE_PENDING); */
|
|
|
|
while (resolve->pending_connections) {
|
|
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));
|
|
pendconn->_base.addr = addr;
|
|
pendconn->address_ttl = ttl;
|
|
|
|
if (outcome != DNS_RESOLVE_SUCCEEDED) {
|
|
/* 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,
|
|
pendconn->cpath_layer);
|
|
/* 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, RESOLVED_TYPE_ERROR);
|
|
/* 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 {
|
|
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;
|
|
send_resolved_cell(pendconn, RESOLVED_TYPE_IPV4);
|
|
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);
|
|
}
|
|
|
|
resolve->state = CACHE_STATE_DONE;
|
|
removed = HT_REMOVE(cache_map, &cache_root, &search);
|
|
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();
|
|
|
|
add_answer_to_cache(address, addr, outcome, ttl);
|
|
assert_cache_ok();
|
|
}
|
|
|
|
#ifndef USE_EVENTDNS
|
|
/** Find or spawn a dns worker process to handle resolving
|
|
* <b>exitconn</b>-\>address; tell that dns worker to begin resolving.
|
|
*/
|
|
static int
|
|
launch_resolve(edge_connection_t *exitconn)
|
|
{
|
|
connection_t *dnsconn;
|
|
unsigned char len;
|
|
|
|
tor_assert(exitconn->_base.state == EXIT_CONN_STATE_RESOLVING);
|
|
assert_connection_ok(TO_CONN(exitconn), 0);
|
|
tor_assert(exitconn->_base.s == -1);
|
|
|
|
/* respawn here, to be sure there are enough */
|
|
if (spawn_enough_dnsworkers() < 0) {
|
|
goto err;
|
|
}
|
|
|
|
dnsconn = connection_get_by_type_state(CONN_TYPE_DNSWORKER,
|
|
DNSWORKER_STATE_IDLE);
|
|
|
|
if (!dnsconn) {
|
|
log_warn(LD_EXIT,"no idle dns workers. Failing.");
|
|
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
|
|
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT);
|
|
goto err;
|
|
}
|
|
|
|
log_debug(LD_EXIT,
|
|
"Connection (fd %d) needs to resolve %s; assigning "
|
|
"to DNSWorker (fd %d)", exitconn->_base.s,
|
|
escaped_safe_str(exitconn->_base.address), dnsconn->s);
|
|
|
|
tor_free(dnsconn->address);
|
|
dnsconn->address = tor_strdup(exitconn->_base.address);
|
|
dnsconn->state = DNSWORKER_STATE_BUSY;
|
|
/* touch the lastwritten timestamp, since that's how we check to
|
|
* see how long it's been since we asked the question, and sometimes
|
|
* we check before the first call to connection_handle_write(). */
|
|
dnsconn->timestamp_lastwritten = time(NULL);
|
|
num_dnsworkers_busy++;
|
|
|
|
len = strlen(dnsconn->address);
|
|
connection_write_to_buf((char*)&len, 1, dnsconn);
|
|
connection_write_to_buf(dnsconn->address, len, dnsconn);
|
|
|
|
return 0;
|
|
err:
|
|
/* also sends end and frees */
|
|
dns_cancel_pending_resolve(exitconn->_base.address);
|
|
return -1;
|
|
}
|
|
|
|
/******************************************************************/
|
|
|
|
/*
|
|
* Connection between OR and dnsworker
|
|
*/
|
|
|
|
/** Write handler: called when we've pushed a request to a dnsworker. */
|
|
int
|
|
connection_dns_finished_flushing(connection_t *conn)
|
|
{
|
|
tor_assert(conn);
|
|
tor_assert(conn->type == CONN_TYPE_DNSWORKER);
|
|
connection_stop_writing(conn);
|
|
return 0;
|
|
}
|
|
|
|
/** Called when a connection to a dnsworker hits an EOF; this only happens
|
|
* when a dnsworker dies unexpectedly. */
|
|
int
|
|
connection_dns_reached_eof(connection_t *conn)
|
|
{
|
|
log_warn(LD_EXIT,"Read eof. Worker died unexpectedly.");
|
|
if (conn->state == DNSWORKER_STATE_BUSY) {
|
|
/* don't cancel the resolve here -- it would be cancelled in
|
|
* connection_about_to_close_connection(), since conn is still
|
|
* in state BUSY
|
|
*/
|
|
num_dnsworkers_busy--;
|
|
}
|
|
num_dnsworkers--;
|
|
connection_mark_for_close(conn);
|
|
return 0;
|
|
}
|
|
|
|
/** Read handler: called when we get data from a dnsworker. See
|
|
* if we have a complete answer. If so, call dns_found_answer on the
|
|
* result. If not, wait. Returns 0. */
|
|
int
|
|
connection_dns_process_inbuf(connection_t *conn)
|
|
{
|
|
char success;
|
|
uint32_t addr;
|
|
int ttl;
|
|
|
|
tor_assert(conn);
|
|
tor_assert(conn->type == CONN_TYPE_DNSWORKER);
|
|
|
|
if (conn->state != DNSWORKER_STATE_BUSY && buf_datalen(conn->inbuf)) {
|
|
log_warn(LD_BUG,
|
|
"Bug: read data (%d bytes) from an idle dns worker (fd %d, "
|
|
"address %s). Please report.", (int)buf_datalen(conn->inbuf),
|
|
conn->s, escaped_safe_str(conn->address));
|
|
tor_fragile_assert();
|
|
|
|
/* Pull it off the buffer anyway, or it will just stay there.
|
|
* Keep pulling things off because sometimes we get several
|
|
* answers at once (!). */
|
|
while (buf_datalen(conn->inbuf)) {
|
|
connection_fetch_from_buf(&success,1,conn);
|
|
connection_fetch_from_buf((char *)&addr,sizeof(uint32_t),conn);
|
|
log_warn(LD_EXIT,"Discarding idle dns answer (success %d, addr %d.)",
|
|
success, addr);
|
|
}
|
|
return 0;
|
|
}
|
|
if (buf_datalen(conn->inbuf) < 5) /* entire answer available? */
|
|
return 0; /* not yet */
|
|
tor_assert(conn->state == DNSWORKER_STATE_BUSY);
|
|
tor_assert(buf_datalen(conn->inbuf) == 5);
|
|
|
|
connection_fetch_from_buf(&success,1,conn);
|
|
connection_fetch_from_buf((char *)&addr,sizeof(uint32_t),conn);
|
|
|
|
log_debug(LD_EXIT, "DNSWorker (fd %d) returned answer for %s",
|
|
conn->s, escaped_safe_str(conn->address));
|
|
|
|
tor_assert(success >= DNS_RESOLVE_FAILED_TRANSIENT);
|
|
tor_assert(success <= DNS_RESOLVE_SUCCEEDED);
|
|
|
|
ttl = (success == DNS_RESOLVE_FAILED_TRANSIENT) ? 0 : MAX_DNS_ENTRY_AGE;
|
|
dns_found_answer(conn->address, ntohl(addr), success, ttl);
|
|
|
|
tor_free(conn->address);
|
|
conn->address = tor_strdup("<idle>");
|
|
conn->state = DNSWORKER_STATE_IDLE;
|
|
num_dnsworkers_busy--;
|
|
if (conn->timestamp_created < last_rotation_time) {
|
|
connection_mark_for_close(conn);
|
|
num_dnsworkers--;
|
|
spawn_enough_dnsworkers();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/** Close and re-open all idle dnsworkers; schedule busy ones to be closed
|
|
* and re-opened once they're no longer busy.
|
|
**/
|
|
static void
|
|
dnsworkers_rotate(void)
|
|
{
|
|
connection_t *dnsconn;
|
|
while ((dnsconn = connection_get_by_type_state(CONN_TYPE_DNSWORKER,
|
|
DNSWORKER_STATE_IDLE))) {
|
|
connection_mark_for_close(dnsconn);
|
|
num_dnsworkers--;
|
|
}
|
|
last_rotation_time = time(NULL);
|
|
if (server_mode(get_options()))
|
|
spawn_enough_dnsworkers();
|
|
}
|
|
|
|
/** Implementation for DNS workers; this code runs in a separate
|
|
* execution context. It takes as its argument an fdarray as returned
|
|
* by socketpair(), and communicates via fdarray[1]. The protocol is
|
|
* as follows:
|
|
* - The OR says:
|
|
* - ADDRESSLEN [1 byte]
|
|
* - ADDRESS [ADDRESSLEN bytes]
|
|
* - The DNS worker does the lookup, and replies:
|
|
* - OUTCOME [1 byte]
|
|
* - IP [4 bytes]
|
|
*
|
|
* OUTCOME is one of DNS_RESOLVE_{FAILED_TRANSIENT|FAILED_PERMANENT|SUCCEEDED}.
|
|
* IP is in host order.
|
|
*
|
|
* The dnsworker runs indefinitely, until its connection is closed or an error
|
|
* occurs.
|
|
*/
|
|
static int
|
|
dnsworker_main(void *data)
|
|
{
|
|
char address[MAX_ADDRESSLEN+1]; /* Plus a byte for a final '.' */
|
|
unsigned char address_len;
|
|
char *log_address;
|
|
char answer[5];
|
|
uint32_t ip;
|
|
int *fdarray = data;
|
|
int fd;
|
|
int result;
|
|
int search = get_options()->SearchDomains;
|
|
|
|
/* log_fn(LOG_NOTICE,"After spawn: fdarray @%d has %d:%d", (int)fdarray,
|
|
* fdarray[0],fdarray[1]); */
|
|
|
|
fd = fdarray[1]; /* this side is ours */
|
|
#ifndef TOR_IS_MULTITHREADED
|
|
tor_close_socket(fdarray[0]); /* this is the side of the socketpair the
|
|
* parent uses */
|
|
tor_free_all(1); /* so the child doesn't hold the parent's fd's open */
|
|
handle_signals(0); /* ignore interrupts from the keyboard, etc */
|
|
#endif
|
|
tor_free(data);
|
|
|
|
for (;;) {
|
|
int r;
|
|
|
|
if ((r = recv(fd, &address_len, 1, 0)) != 1) {
|
|
if (r == 0) {
|
|
log_info(LD_EXIT,"DNS worker exiting because Tor process closed "
|
|
"connection (either pruned idle dnsworker or died).");
|
|
} else {
|
|
log_info(LD_EXIT,"DNS worker exiting because of error on connection "
|
|
"to Tor process.");
|
|
log_info(LD_EXIT,"(Error on %d was %s)", fd,
|
|
tor_socket_strerror(tor_socket_errno(fd)));
|
|
}
|
|
tor_close_socket(fd);
|
|
crypto_thread_cleanup();
|
|
spawn_exit();
|
|
}
|
|
|
|
if (address_len && read_all(fd, address, address_len, 1) != address_len) {
|
|
log_err(LD_BUG,"read hostname failed. Child exiting.");
|
|
tor_close_socket(fd);
|
|
crypto_thread_cleanup();
|
|
spawn_exit();
|
|
}
|
|
/* Add a period to prevent local domain search, and NUL-terminate. */
|
|
if (address[address_len-1] != '.' && !search) {
|
|
address[address_len] = '.';
|
|
address[address_len+1] = '\0';
|
|
} else {
|
|
address[address_len] = '\0';
|
|
}
|
|
|
|
log_address = esc_for_log(safe_str(address));
|
|
result = tor_lookup_hostname(address, &ip);
|
|
/* Make 0.0.0.0 an error, so that we can use "0" to mean "no addr") */
|
|
if (!ip)
|
|
result = -1;
|
|
switch (result) {
|
|
case 1:
|
|
/* XXX result can never be 1, because we set it to -1 above on error */
|
|
log_info(LD_NET,"Could not resolve dest addr %s (transient)",
|
|
log_address);
|
|
answer[0] = DNS_RESOLVE_FAILED_TRANSIENT;
|
|
break;
|
|
case -1:
|
|
log_info(LD_NET,"Could not resolve dest addr %s (permanent)",
|
|
log_address);
|
|
answer[0] = DNS_RESOLVE_FAILED_PERMANENT;
|
|
break;
|
|
case 0:
|
|
log_info(LD_NET,"Resolved address %s", log_address);
|
|
answer[0] = DNS_RESOLVE_SUCCEEDED;
|
|
break;
|
|
}
|
|
tor_free(log_address);
|
|
set_uint32(answer+1, ip);
|
|
if (write_all(fd, answer, 5, 1) != 5) {
|
|
log_err(LD_NET,"writing answer failed. Child exiting.");
|
|
tor_close_socket(fd);
|
|
crypto_thread_cleanup();
|
|
spawn_exit();
|
|
}
|
|
}
|
|
return 0; /* windows wants this function to return an int */
|
|
}
|
|
|
|
/** Launch a new DNS worker; return 0 on success, -1 on failure.
|
|
*/
|
|
static int
|
|
spawn_dnsworker(void)
|
|
{
|
|
int *fdarray;
|
|
int fd;
|
|
connection_t *conn;
|
|
int err;
|
|
|
|
fdarray = tor_malloc(sizeof(int)*2);
|
|
if ((err = tor_socketpair(AF_UNIX, SOCK_STREAM, 0, fdarray)) < 0) {
|
|
log_warn(LD_NET, "Couldn't construct socketpair: %s",
|
|
tor_socket_strerror(-err));
|
|
tor_free(fdarray);
|
|
return -1;
|
|
}
|
|
|
|
tor_assert(fdarray[0] >= 0);
|
|
tor_assert(fdarray[1] >= 0);
|
|
|
|
/* log_fn(LOG_NOTICE,"Before spawn: fdarray @%d has %d:%d",
|
|
(int)fdarray, fdarray[0],fdarray[1]); */
|
|
|
|
fd = fdarray[0]; /* We copy this out here, since dnsworker_main may free
|
|
* fdarray */
|
|
spawn_func(dnsworker_main, (void*)fdarray);
|
|
log_debug(LD_EXIT,"just spawned a dns worker.");
|
|
#ifndef TOR_IS_MULTITHREADED
|
|
tor_close_socket(fdarray[1]); /* don't need the worker's side of the pipe */
|
|
tor_free(fdarray);
|
|
#endif
|
|
|
|
conn = connection_new(CONN_TYPE_DNSWORKER);
|
|
|
|
set_socket_nonblocking(fd);
|
|
|
|
/* set up conn so it's got all the data we need to remember */
|
|
conn->s = fd;
|
|
conn->address = tor_strdup("<unused>");
|
|
|
|
if (connection_add(conn) < 0) { /* no space, forget it */
|
|
log_warn(LD_NET,"connection_add failed. Giving up.");
|
|
connection_free(conn); /* this closes fd */
|
|
return -1;
|
|
}
|
|
|
|
conn->state = DNSWORKER_STATE_IDLE;
|
|
connection_start_reading(conn);
|
|
|
|
return 0; /* success */
|
|
}
|
|
|
|
/** If we have too many or too few DNS workers, spawn or kill some.
|
|
* Return 0 if we are happy, return -1 if we tried to spawn more but
|
|
* we couldn't.
|
|
*/
|
|
static int
|
|
spawn_enough_dnsworkers(void)
|
|
{
|
|
int num_dnsworkers_needed; /* aim to have 1 more than needed,
|
|
* but no less than min and no more than max */
|
|
connection_t *dnsconn;
|
|
|
|
/* XXX This may not be the best strategy. Maybe we should queue pending
|
|
* requests until the old ones finish or time out: otherwise, if the
|
|
* connection requests come fast enough, we never get any DNS done. -NM
|
|
*
|
|
* XXX But if we queue them, then the adversary can pile even more
|
|
* queries onto us, blocking legitimate requests for even longer. Maybe
|
|
* we should compromise and only kill if it's been at it for more than,
|
|
* e.g., 2 seconds. -RD
|
|
*/
|
|
if (num_dnsworkers_busy == MAX_DNSWORKERS) {
|
|
/* We always want at least one worker idle.
|
|
* So find the oldest busy worker and kill it.
|
|
*/
|
|
dnsconn = connection_get_by_type_state_lastwritten(CONN_TYPE_DNSWORKER,
|
|
DNSWORKER_STATE_BUSY);
|
|
tor_assert(dnsconn);
|
|
|
|
log_warn(LD_EXIT, "%d DNS workers are spawned; all are busy. Killing one.",
|
|
MAX_DNSWORKERS);
|
|
|
|
connection_mark_for_close(dnsconn);
|
|
num_dnsworkers_busy--;
|
|
num_dnsworkers--;
|
|
}
|
|
|
|
if (num_dnsworkers_busy >= MIN_DNSWORKERS)
|
|
num_dnsworkers_needed = num_dnsworkers_busy+1;
|
|
else
|
|
num_dnsworkers_needed = MIN_DNSWORKERS;
|
|
|
|
while (num_dnsworkers < num_dnsworkers_needed) {
|
|
if (spawn_dnsworker() < 0) {
|
|
log_warn(LD_EXIT,"Spawn failed. Will try again later.");
|
|
return -1;
|
|
}
|
|
num_dnsworkers++;
|
|
}
|
|
|
|
while (num_dnsworkers > num_dnsworkers_busy+MAX_IDLE_DNSWORKERS) {
|
|
/* too many idle? */
|
|
/* cull excess workers */
|
|
log_info(LD_EXIT,"%d of %d dnsworkers are idle. Killing one.",
|
|
num_dnsworkers-num_dnsworkers_busy, num_dnsworkers);
|
|
dnsconn = connection_get_by_type_state(CONN_TYPE_DNSWORKER,
|
|
DNSWORKER_STATE_IDLE);
|
|
tor_assert(dnsconn);
|
|
connection_mark_for_close(dnsconn);
|
|
num_dnsworkers--;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#else /* !USE_EVENTDNS */
|
|
|
|
/** Eventdns helper: return true iff the eventdns result <b>err</b> is
|
|
* a transient failure. */
|
|
static int
|
|
eventdns_err_is_transient(int err)
|
|
{
|
|
switch (err)
|
|
{
|
|
case DNS_ERR_SERVERFAILED:
|
|
case DNS_ERR_TRUNCATED:
|
|
case DNS_ERR_TIMEOUT:
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
/* Dummy function; never called with eventdns enabled. */
|
|
int
|
|
connection_dns_finished_flushing(connection_t *conn)
|
|
{
|
|
(void)conn;
|
|
tor_assert(0);
|
|
return 0;
|
|
}
|
|
/* Dummy function; never called with eventdns enabled. */
|
|
int
|
|
connection_dns_process_inbuf(connection_t *conn)
|
|
{
|
|
(void)conn;
|
|
tor_assert(0);
|
|
return 0;
|
|
}
|
|
/* Dummy function; never called with eventdns enabled. */
|
|
int
|
|
connection_dns_reached_eof(connection_t *conn)
|
|
{
|
|
(void)conn;
|
|
tor_assert(0);
|
|
return 0;
|
|
}
|
|
|
|
/** Configure eventdns nameservers if force is true, or if the configuration
|
|
* has changed since the last time we called this function. On Unix, this
|
|
* reads from options->ResolvConf or /etc/resolv.conf; on Windows, this reads
|
|
* from options->ResolvConf or the registry. Return 0 on success or -1 on
|
|
* failure. */
|
|
static int
|
|
configure_nameservers(int force)
|
|
{
|
|
or_options_t *options;
|
|
const char *conf_fname;
|
|
struct stat st;
|
|
options = get_options();
|
|
conf_fname = options->ResolvConf;
|
|
#ifndef MS_WINDOWS
|
|
if (!conf_fname)
|
|
conf_fname = "/etc/resolv.conf";
|
|
#endif
|
|
|
|
eventdns_set_log_fn(eventdns_log_cb);
|
|
if (conf_fname) {
|
|
if (stat(conf_fname, &st)) {
|
|
log_warn(LD_EXIT, "Unable to stat resolver configuration in '%s'",
|
|
conf_fname);
|
|
return -1;
|
|
}
|
|
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) {
|
|
eventdns_search_clear();
|
|
eventdns_clear_nameservers_and_suspend();
|
|
}
|
|
log_info(LD_EXIT, "Parsing resolver configuration in '%s'", conf_fname);
|
|
if (eventdns_resolv_conf_parse(DNS_OPTIONS_ALL, conf_fname))
|
|
return -1;
|
|
if (eventdns_count_nameservers() == 0) {
|
|
log_warn(LD_EXIT, "Unable to find any nameservers in '%s'.", conf_fname);
|
|
return -1;
|
|
}
|
|
tor_free(resolv_conf_fname);
|
|
resolv_conf_fname = tor_strdup(conf_fname);
|
|
resolv_conf_mtime = st.st_mtime;
|
|
if (nameservers_configured)
|
|
eventdns_resume();
|
|
}
|
|
#ifdef MS_WINDOWS
|
|
else {
|
|
if (nameservers_configured) {
|
|
eventdns_search_clear();
|
|
eventdns_clear_nameservers_and_suspend();
|
|
}
|
|
if (eventdns_config_windows_nameservers())
|
|
return -1;
|
|
if (eventdns_count_nameservers() == 0) {
|
|
log_warn(LD_EXIT, "Unable to find any platform nameservers in "
|
|
"your Windows configuration. Perhaps you should list a "
|
|
"ResolvConf file in your torrc?");
|
|
return -1;
|
|
}
|
|
if (nameservers_configured)
|
|
eventdns_resume();
|
|
tor_free(resolv_conf_fname);
|
|
resolv_conf_mtime = 0;
|
|
}
|
|
#endif
|
|
|
|
nameservers_configured = 1;
|
|
return 0;
|
|
}
|
|
|
|
/** 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
|
|
eventdns_callback(int result, char type, int count, int ttl, void *addresses,
|
|
void *arg)
|
|
{
|
|
char *string_address = arg;
|
|
int status = DNS_RESOLVE_FAILED_PERMANENT;
|
|
uint32_t addr = 0;
|
|
if (result == DNS_ERR_NONE) {
|
|
if (type == DNS_IPv4_A && count) {
|
|
char answer_buf[INET_NTOA_BUF_LEN+1];
|
|
struct in_addr in;
|
|
uint32_t *addrs = addresses;
|
|
in.s_addr = addrs[0];
|
|
addr = ntohl(addrs[0]);
|
|
status = DNS_RESOLVE_SUCCEEDED;
|
|
tor_inet_ntoa(&in, answer_buf, sizeof(answer_buf));
|
|
log_debug(LD_EXIT, "eventdns said that %s resolves to %s",
|
|
escaped_safe_str(string_address),
|
|
escaped_safe_str(answer_buf));
|
|
} 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));
|
|
}
|
|
} else {
|
|
if (eventdns_err_is_transient(result))
|
|
status = DNS_RESOLVE_FAILED_TRANSIENT;
|
|
}
|
|
dns_found_answer(string_address, addr, status, ttl);
|
|
tor_free(string_address);
|
|
}
|
|
|
|
/** For eventdns: start resolving as necessary to find the target for
|
|
* <b>exitconn</b> */
|
|
static int
|
|
launch_resolve(edge_connection_t *exitconn)
|
|
{
|
|
char *addr = tor_strdup(exitconn->_base.address);
|
|
int r;
|
|
int options = get_options()->SearchDomains ? 0 : DNS_QUERY_NO_SEARCH;
|
|
/* What? Nameservers not configured? Sounds like a bug. */
|
|
if (!nameservers_configured) {
|
|
log_warn(LD_EXIT, "Harmless bug: nameservers not configured, but resolve "
|
|
"launched. Configuring.");
|
|
if (configure_nameservers(1) < 0)
|
|
return -1;
|
|
}
|
|
log_info(LD_EXIT, "Launching eventdns request for %s",
|
|
escaped_safe_str(exitconn->_base.address));
|
|
r = eventdns_resolve_ipv4(exitconn->_base.address, options,
|
|
eventdns_callback, addr);
|
|
if (r) {
|
|
log_warn(LD_EXIT, "eventdns rejected address %s: error %d.",
|
|
escaped_safe_str(addr), r);
|
|
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE) {
|
|
if (eventdns_err_is_transient(r))
|
|
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT);
|
|
else {
|
|
exitconn->address_ttl = DEFAULT_DNS_TTL;
|
|
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
|
|
}
|
|
}
|
|
dns_cancel_pending_resolve(addr); /* also sends end and frees */
|
|
tor_free(addr);
|
|
}
|
|
return r ? -1 : 0;
|
|
}
|
|
#endif /* USE_EVENTDNS */
|
|
|
|
/** 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) {
|
|
tor_assert(!resolve->ttl);
|
|
tor_assert(!resolve->addr);
|
|
}
|
|
}
|
|
|
|
#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);
|
|
}
|
|
#endif
|
|
|