diff options
Diffstat (limited to 'src/or/dns.c')
| -rw-r--r-- | src/or/dns.c | 1308 |
1 files changed, 266 insertions, 1042 deletions
diff --git a/src/or/dns.c b/src/or/dns.c index adfadb6f13..5303ced78a 100644 --- a/src/or/dns.c +++ b/src/or/dns.c @@ -7,21 +7,20 @@ const char dns_c_id[] = /** * \file dns.c - * \brief Implements a local cache for DNS results for Tor servers. - * We provide two asynchronous backend implementations: - * 1) A farm of 'DNS worker' threads or processes to perform DNS lookups for - * onion routers and cache the results. - * 2) A wrapper around Adam Langley's eventdns.c code, to send requests - * to the nameservers asynchronously. - * (We can't just use gethostbyname() and friends because we really need to - * be nonblocking.) + * \brief Implements a farm of 'DNS worker' threads or processes to + * perform DNS lookups for onion routers and cache the results. + * [This needs to be done in the background because of the lack of a + * good, ubiquitous asynchronous DNS implementation.] **/ +/* See + * http://elvin.dstc.com/ListArchive/elvin-dev/archive/2001/09/msg00027.html + * for some approaches to asynchronous dns. We will want to switch once one of + * them becomes more commonly available. + */ + #include "or.h" #include "../common/ht.h" -#ifdef USE_EVENTDNS -#include "eventdns.h" -#endif /** Longest hostname we're willing to resolve. */ #define MAX_ADDRESSLEN 256 @@ -34,103 +33,51 @@ const char dns_c_id[] = /** If more than this many processes are idle, shut down the extras. */ #define MAX_IDLE_DNSWORKERS 10 -/** How long will we wait for an answer from the resolver before we decide - * that the resolver is wedged? */ -#define RESOLVE_MAX_TIMEOUT 300 - /** Possible outcomes from hostname lookup: permanent failure, * transient (retryable) failure, and success. */ #define DNS_RESOLVE_FAILED_TRANSIENT 1 #define DNS_RESOLVE_FAILED_PERMANENT 2 #define DNS_RESOLVE_SUCCEEDED 3 -#ifndef USE_EVENTDNS /** How many dnsworkers we have running right now. */ static int num_dnsworkers=0; /** How many of the running dnsworkers have an assigned task right now. */ static int num_dnsworkers_busy=0; /** When did we last rotate the dnsworkers? */ static time_t last_rotation_time=0; -#else -/** Have we currently configured nameservers with eventdns? */ -static int nameservers_configured = 0; -/** What was the resolv_conf fname we last used when configuring the - * nameservers? Used to check whether we need to reconfigure. */ -static char *resolv_conf_fname = NULL; -/** What was the mtime on the resolv.conf file we last used when configuring - * the nameservers? Used to check whether we need to reconfigure. */ -static time_t resolv_conf_mtime = 0; -#endif /** Linked list of connections waiting for a DNS answer. */ typedef struct pending_connection_t { - edge_connection_t *conn; + connection_t *conn; struct pending_connection_t *next; } pending_connection_t; -#define CACHED_RESOLVE_MAGIC 0x1234F00D - -/* Possible states for a cached resolve_t */ -/** We are waiting for the resolver system to tell us an answer here. - * When we get one, or when we time out, the state of this cached_resolve_t - * will become "DONE" and we'll possibly add a CACHED_VALID or a CACHED_FAILED - * entry. This cached_resolve_t will be in the hash table so that we will - * know not to launch more requests for this addr, but rather to add more - * connections to the pending list for the addr. */ -#define CACHE_STATE_PENDING 0 -/** This used to be a pending cached_resolve_t, and we got an answer for it. - * Now we're waiting for this cached_resolve_t to expire. This should - * have no pending connections, and should not appear in the hash table. */ -#define CACHE_STATE_DONE 1 -/** We are caching an answer for this address. This should have no pending - * connections, and should appear in the hash table. */ -#define CACHE_STATE_CACHED_VALID 2 -/** We are caching a failure for this address. This should have no pending - * connections, and should appear in the hash table */ -#define CACHE_STATE_CACHED_FAILED 3 - /** A DNS request: possibly completed, possibly pending; cached_resolve * structs are stored at the OR side in a hash table, and as a linked * list from oldest to newest. */ typedef struct cached_resolve_t { HT_ENTRY(cached_resolve_t) node; - uint32_t magic; char address[MAX_ADDRESSLEN]; /**< The hostname to be resolved. */ - union { - uint32_t addr; /**< IPv4 addr for <b>address</b>. */ - char *hostname; /**< Hostname for <b>address</b> (if a reverse lookup) */ - } result; - uint8_t state; /**< Is this cached entry pending/done/valid/failed? */ - uint8_t is_reverse; /**< Is this a reverse (addr-to-hostname) lookup? */ - time_t expire; /**< Remove items from cache after this time. */ - uint32_t ttl; /**< What TTL did the nameserver tell us? */ - /** Connections that want to know when we get an answer for this resolve. */ + uint32_t addr; /**< IPv4 addr for <b>address</b>. */ + char state; /**< 0 is pending; 1 means answer is valid; 2 means resolve + * failed. */ +#define CACHE_STATE_PENDING 0 +#define CACHE_STATE_VALID 1 +#define CACHE_STATE_FAILED 2 + uint32_t expire; /**< Remove items from cache after this time. */ pending_connection_t *pending_connections; + struct cached_resolve_t *next; } cached_resolve_t; -static void purge_expired_resolves(time_t now); -static void dns_found_answer(const char *address, int is_reverse, - uint32_t addr, const char *hostname, char outcome, - uint32_t ttl); -static void send_resolved_cell(edge_connection_t *conn, uint8_t answer_type); -static int launch_resolve(edge_connection_t *exitconn); -#ifndef USE_EVENTDNS -static void dnsworkers_rotate(void); -static void dnsworker_main(void *data); +static void purge_expired_resolves(uint32_t now); +static int assign_to_dnsworker(connection_t *exitconn); +static void dns_purge_resolve(cached_resolve_t *resolve); +static void dns_found_answer(char *address, uint32_t addr, char outcome); +static int dnsworker_main(void *data); static int spawn_dnsworker(void); static int spawn_enough_dnsworkers(void); -#else -static int configure_nameservers(int force); -static int answer_is_wildcarded(const char *ip); -#endif -#ifdef DEBUG_DNS_CACHE -static void _assert_cache_ok(void); -#define assert_cache_ok() _assert_cache_ok() -#else -#define assert_cache_ok() do {} while (0) -#endif -static void assert_resolve_ok(cached_resolve_t *resolve); +static void send_resolved_cell(connection_t *conn, uint8_t answer_type); /** Hash table of cached_resolve objects. */ static HT_HEAD(cache_map, cached_resolve_t) cache_root; @@ -141,11 +88,9 @@ static INLINE int cached_resolves_eq(cached_resolve_t *a, cached_resolve_t *b) { /* make this smarter one day? */ - assert_resolve_ok(a); // Not b; b may be just a search. return !strncmp(a->address, b->address, MAX_ADDRESSLEN); } -/** Hash function for cached_resolve objects */ static INLINE unsigned int cached_resolve_hash(cached_resolve_t *a) { @@ -164,82 +109,12 @@ init_cache_map(void) HT_INIT(&cache_root); } -#ifdef USE_EVENTDNS -/** Helper: called by eventdns when eventdns wants to log something. */ -static void -eventdns_log_cb(int warn, const char *msg) -{ - if (!strcmpstart(msg, "Resolve requested for") && - get_options()->SafeLogging) { - log(LOG_INFO, LD_EXIT, "eventdns: Resolve requested."); - return; - } else if (!strcmpstart(msg, "Search: ")) { - return; - } - log(warn?LOG_WARN:LOG_INFO, LD_EXIT, "eventdns: %s", msg); -} -#endif - /** Initialize the DNS subsystem; called by the OR process. */ -int +void dns_init(void) { init_cache_map(); -#ifdef USE_EVENTDNS - if (server_mode(get_options())) - return configure_nameservers(1); -#else - dnsworkers_rotate(); -#endif - return 0; -} - -/** Called when DNS-related options change (or may have changed) */ -void -dns_reset(void) -{ -#ifdef USE_EVENTDNS - or_options_t *options = get_options(); - if (! server_mode(options)) { - eventdns_clear_nameservers_and_suspend(); - eventdns_search_clear(); - nameservers_configured = 0; - tor_free(resolv_conf_fname); - resolv_conf_mtime = 0; - } else { - if (configure_nameservers(0) < 0) - /* XXXX */ - return; - } -#else dnsworkers_rotate(); -#endif -} - -/** Helper: Given a TTL from a DNS response, determine what TTL to give the - * OP that asked us to resolve it. */ -uint32_t -dns_clip_ttl(uint32_t ttl) -{ - if (ttl < MIN_DNS_TTL) - return MIN_DNS_TTL; - else if (ttl > MAX_DNS_TTL) - return MAX_DNS_TTL; - else - return ttl; -} - -/** Helper: Given a TTL from a DNS response, determine how long to hold it in - * our cache. */ -static uint32_t -dns_get_expiry_ttl(uint32_t ttl) -{ - if (ttl < MIN_DNS_TTL) - return MIN_DNS_TTL; - else if (ttl > MAX_DNS_ENTRY_AGE) - return MAX_DNS_ENTRY_AGE; - else - return ttl; } /** Helper: free storage held by an entry in the DNS cache. */ @@ -251,41 +126,10 @@ _free_cached_resolve(cached_resolve_t *r) r->pending_connections = victim->next; tor_free(victim); } - if (r->is_reverse) - tor_free(r->result.hostname); - r->magic = 0xFF00FF00; tor_free(r); } -/** Compare two cached_resolve_t pointers by expiry time, and return - * less-than-zero, zero, or greater-than-zero as appropriate. Used for - * the priority queue implementation. */ -static int -_compare_cached_resolves_by_expiry(const void *_a, const void *_b) -{ - const cached_resolve_t *a = _a, *b = _b; - return a->expire - b->expire; -} - -/** Priority queue of cached_resolve_t objects to let us know when they - * will expire. */ -static smartlist_t *cached_resolve_pqueue = NULL; - -/** 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_create(); - resolve->expire = expires; - smartlist_pqueue_add(cached_resolve_pqueue, - _compare_cached_resolves_by_expiry, - resolve); -} - -/** Free all storage held in the DNS cache and related structures. */ +/** Free all storage held in the DNS cache */ void dns_free_all(void) { @@ -296,112 +140,78 @@ dns_free_all(void) _free_cached_resolve(item); } HT_CLEAR(cache_map, &cache_root); - if (cached_resolve_pqueue) - smartlist_free(cached_resolve_pqueue); - cached_resolve_pqueue = NULL; -#ifdef USE_EVENTDNS - tor_free(resolv_conf_fname); -#endif } +/** Linked list of resolved addresses, oldest to newest. */ +static cached_resolve_t *oldest_cached_resolve = NULL; +static cached_resolve_t *newest_cached_resolve = NULL; + /** Remove every cached_resolve whose <b>expire</b> time is before <b>now</b> * from the cache. */ static void -purge_expired_resolves(time_t now) +purge_expired_resolves(uint32_t now) { - cached_resolve_t *resolve, *removed; + cached_resolve_t *resolve; 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); + connection_t *pendconn; + /* this is fast because the linked list + * oldest_cached_resolve is ordered by when they came in. + */ + while (oldest_cached_resolve && (oldest_cached_resolve->expire < now)) { + resolve = oldest_cached_resolve; + log_debug(LD_EXIT, + "Forgetting old cached resolve (address %s, expires %lu)", + escaped_safe_str(resolve->address), + (unsigned long)resolve->expire); 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_VALID || - resolve->state == CACHE_STATE_CACHED_FAILED) { - 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); + "Bug: Expiring a dns resolve %s that's still pending." + " Forgot to cull it?", escaped_safe_str(resolve->address)); + tor_fragile_assert(); } - if (resolve->pending_connections) { log_debug(LD_EXIT, - "Closing pending connections on timed-out DNS resolve!"); + "Closing pending connections on expiring DNS resolve!"); tor_fragile_assert(); 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(pend->conn->_base.s == -1); + tor_assert(pend->conn->s == -1); pendconn = pend->conn; connection_edge_end(pendconn, END_STREAM_REASON_TIMEOUT, pendconn->cpath_layer); circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn); - connection_free(TO_CONN(pendconn)); + connection_free(pendconn); tor_free(pend); } } - - if (resolve->state == CACHE_STATE_CACHED_VALID || - resolve->state == CACHE_STATE_CACHED_FAILED || - 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*)remove); - } - tor_assert(removed == resolve); - if (resolve->is_reverse) - tor_free(resolve->result.hostname); - resolve->magic = 0xF0BBF0BB; - tor_free(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); - } + oldest_cached_resolve = resolve->next; + if (!oldest_cached_resolve) /* if there are no more, */ + newest_cached_resolve = NULL; /* then make sure the list's tail knows + * that too */ + HT_REMOVE(cache_map, &cache_root, resolve); + tor_free(resolve); } - - assert_cache_ok(); } -/** Send a response to the RESOLVE request of a connection. answer_type must +/** Send a response to the RESOVLE request of a connection. answer_type must * be one of RESOLVED_TYPE_(IPV4|ERROR|ERROR_TRANSIENT) */ static void -send_resolved_cell(edge_connection_t *conn, uint8_t answer_type) +send_resolved_cell(connection_t *conn, uint8_t answer_type) { char buf[RELAY_PAYLOAD_SIZE]; size_t buflen; - uint32_t ttl; buf[0] = answer_type; - ttl = dns_clip_ttl(conn->address_ttl); switch (answer_type) { case RESOLVED_TYPE_IPV4: buf[1] = 4; - set_uint32(buf+2, htonl(conn->_base.addr)); - set_uint32(buf+6, htonl(ttl)); + set_uint32(buf+2, htonl(conn->addr)); + set_uint32(buf+6, htonl(MAX_DNS_ENTRY_AGE)); /*XXXX send a real TTL*/ buflen = 10; break; case RESOLVED_TYPE_ERROR_TRANSIENT: @@ -409,91 +219,35 @@ send_resolved_cell(edge_connection_t *conn, uint8_t answer_type) { const char *errmsg = "Error resolving hostname"; int msglen = strlen(errmsg); - + int ttl = (answer_type == RESOLVED_TYPE_ERROR ? MAX_DNS_ENTRY_AGE : 0); buf[1] = msglen; strlcpy(buf+2, errmsg, sizeof(buf)-2); - set_uint32(buf+2+msglen, htonl(ttl)); + set_uint32(buf+2+msglen, htonl((uint32_t)ttl)); buflen = 6+msglen; break; } default: tor_assert(0); - return; } - // log_notice(LD_EXIT, "Sending a regular RESOLVED reply: "); connection_edge_send_command(conn, circuit_get_by_edge_conn(conn), RELAY_COMMAND_RESOLVED, buf, buflen, conn->cpath_layer); } -/** 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. - */ +/** Link <b>r</b> into the hash table of address-to-result mappings, and add it + * to the linked list of resolves-by-age. */ 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(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, circuit_get_by_edge_conn(conn), - RELAY_COMMAND_RESOLVED, buf, buflen, - conn->cpath_layer); - // log_notice(LD_EXIT, "Sent"); -} - -/** Given a lower-case <b>address</b>, check to see whether it's a - * 1.2.3.4.in-addr.arpa address used for reverse lookups. If so, - * parse it and place the address in <b>in</b> if present. Return 1 on success; - * 0 if the address is not in in-addr.arpa format, and -1 if the address is - * malformed. */ -static int -parse_inaddr_arpa_address(const char *address, struct in_addr *in) +insert_resolve(cached_resolve_t *r) { - char buf[INET_NTOA_BUF_LEN]; - char *cp; - size_t len; - struct in_addr inaddr; - - cp = strstr(address, ".in-addr.arpa"); - if (!cp || *(cp+strlen(".in-addr.arpa"))) - return 0; /* not an .in-addr.arpa address */ - - len = cp - address; - - if (len >= INET_NTOA_BUF_LEN) - return -1; /* Too long. */ - - memcpy(buf, address, len); - buf[len] = '\0'; - if (tor_inet_aton(buf, &inaddr) == 0) - return -1; /* malformed. */ - - if (in) { - uint32_t a; - /* reverse the bytes */ - a = ( ((inaddr.s_addr & 0x000000fful) << 24) - |((inaddr.s_addr & 0x0000ff00ul) << 8) - |((inaddr.s_addr & 0x00ff0000ul) >> 8) - |((inaddr.s_addr & 0xff000000ul) >> 24)); - inaddr.s_addr = a; - - memcpy(in, &inaddr, sizeof(inaddr)); + /* add us to the linked list of resolves */ + if (!oldest_cached_resolve) { + oldest_cached_resolve = r; + } else { + newest_cached_resolve->next = r; } + newest_cached_resolve = r; - return 1; + HT_INSERT(cache_map, &cache_root, r); } /** See if we have a cache entry for <b>exitconn</b>-\>address. if so, @@ -507,28 +261,22 @@ parse_inaddr_arpa_address(const char *address, struct in_addr *in) * dns farm, and return 0. */ int -dns_resolve(edge_connection_t *exitconn) +dns_resolve(connection_t *exitconn) { cached_resolve_t *resolve; cached_resolve_t search; pending_connection_t *pending_connection; - circuit_t *circ; struct in_addr in; - time_t now = time(NULL); - int is_reverse = 0, is_resolve, r; - assert_connection_ok(TO_CONN(exitconn), 0); - tor_assert(exitconn->_base.s == -1); - - assert_cache_ok(); - - is_resolve = exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE; + circuit_t *circ; + uint32_t now = time(NULL); + assert_connection_ok(exitconn, 0); + tor_assert(exitconn->s == -1); - /* first check if exitconn->_base.address is an IP. If so, we already + /* first check if exitconn->address is an IP. If so, we already * know the answer. */ - if (tor_inet_aton(exitconn->_base.address, &in) != 0) { - exitconn->_base.addr = ntohl(in.s_addr); - exitconn->address_ttl = DEFAULT_DNS_TTL; - if (is_resolve) + if (tor_inet_aton(exitconn->address, &in) != 0) { + exitconn->addr = ntohl(in.s_addr); + if (exitconn->purpose == EXIT_PURPOSE_RESOLVE) send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4); return 1; } @@ -537,51 +285,13 @@ dns_resolve(edge_connection_t *exitconn) * 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 - * connecction. - */ - if ((r = parse_inaddr_arpa_address(exitconn->_base.address, NULL)) != 0) { - if (r == 1) - is_reverse = 1; - -#ifdef USE_EVENTDNS - 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)); -#else - if (1) { - log_info(LD_PROTOCOL, "Dnsworker code does not support in-addr.arpa " - "domain, but received a request for \"%s\"; sending error.", - escaped_safe_str(exitconn->_base.address)); -#endif - - 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; - } - //log_notice(LD_EXIT, "Looks like an address %s", - // exitconn->_base.address); - } + /* lower-case exitconn->address, so it's in canonical form */ + tor_strlower(exitconn->address); /* now check the hash table to see if 'address' is already there. */ - strlcpy(search.address, exitconn->_base.address, sizeof(search.address)); + strlcpy(search.address, exitconn->address, sizeof(search.address)); resolve = HT_FIND(cache_map, &cache_root, &search); - if (resolve && resolve->expire > now) { /* already there */ + if (resolve) { /* already there */ switch (resolve->state) { case CACHE_STATE_PENDING: /* add us to the pending list */ @@ -591,124 +301,121 @@ dns_resolve(edge_connection_t *exitconn) pending_connection->next = resolve->pending_connections; resolve->pending_connections = pending_connection; log_debug(LD_EXIT,"Connection (fd %d) waiting for pending DNS " - "resolve of %s", exitconn->_base.s, - escaped_safe_str(exitconn->_base.address)); - exitconn->_base.state = EXIT_CONN_STATE_RESOLVING; + "resolve of %s", + exitconn->s, escaped_safe_str(exitconn->address)); + exitconn->state = EXIT_CONN_STATE_RESOLVING; return 0; - case CACHE_STATE_CACHED_VALID: + case CACHE_STATE_VALID: + exitconn->addr = resolve->addr; log_debug(LD_EXIT,"Connection (fd %d) found cached answer for %s", - exitconn->_base.s, - escaped_safe_str(resolve->address)); - exitconn->address_ttl = resolve->ttl; - if (resolve->is_reverse) { - tor_assert(is_resolve); - send_resolved_hostname_cell(exitconn, resolve->result.hostname); - } else { - exitconn->_base.addr = resolve->result.addr; - if (is_resolve) - send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4); - } + exitconn->s, escaped_safe_str(exitconn->address)); + if (exitconn->purpose == EXIT_PURPOSE_RESOLVE) + send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4); return 1; - case CACHE_STATE_CACHED_FAILED: + case CACHE_STATE_FAILED: log_debug(LD_EXIT,"Connection (fd %d) found cached error for %s", - exitconn->_base.s, - escaped_safe_str(exitconn->_base.address)); - if (is_resolve) + exitconn->s, escaped_safe_str(exitconn->address)); + if (exitconn->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)); + if (!exitconn->marked_for_close) + connection_free(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; - resolve->is_reverse = is_reverse; - strlcpy(resolve->address, exitconn->_base.address, sizeof(resolve->address)); + resolve->expire = now + MAX_DNS_ENTRY_AGE; + strlcpy(resolve->address, exitconn->address, sizeof(resolve->address)); - /* add this connection to the pending list */ + /* add us 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; + exitconn->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); + insert_resolve(resolve); + return assign_to_dnsworker(exitconn); } -/** Log an error and abort if conn is waiting for a DNS resolve. +/** Find or spawn a dns worker process to handle resolving + * <b>exitconn</b>-\>address; tell that dns worker to begin resolving. */ -void -assert_connection_edge_not_dns_pending(edge_connection_t *conn) +static int +assign_to_dnsworker(connection_t *exitconn) { - pending_connection_t *pend; - cached_resolve_t **resolve; + connection_t *dnsconn; + unsigned char len; - HT_FOREACH(resolve, cache_map, &cache_root) { - for (pend = (*resolve)->pending_connections; - pend; - pend = pend->next) { - tor_assert(pend->conn != conn); - } + tor_assert(exitconn->state == EXIT_CONN_STATE_RESOLVING); + tor_assert(exitconn->s == -1); + + /* respawn here, to be sure there are enough */ + if (spawn_enough_dnsworkers() < 0) { + goto err; } -} -/** 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; + dnsconn = connection_get_by_type_state(CONN_TYPE_DNSWORKER, + DNSWORKER_STATE_IDLE); - 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))); - } + if (!dnsconn) { + log_warn(LD_EXIT,"no idle dns workers. Failing."); + if (exitconn->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->s, + escaped_safe_str(exitconn->address), dnsconn->s); + + tor_free(dnsconn->address); + dnsconn->address = tor_strdup(exitconn->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: + dns_cancel_pending_resolve(exitconn->address); /* also sends end and frees */ + return -1; } /** Remove <b>conn</b> from the list of connections waiting for conn-\>address. */ void -connection_dns_remove(edge_connection_t *conn) +connection_dns_remove(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); + tor_assert(conn->type == CONN_TYPE_EXIT); + tor_assert(conn->state == EXIT_CONN_STATE_RESOLVING); - strlcpy(search.address, conn->_base.address, sizeof(search.address)); + strlcpy(search.address, conn->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)); + escaped_safe_str(conn->address)); return; } tor_assert(resolve->pending_connections); - assert_connection_ok(TO_CONN(conn),0); + assert_connection_ok(conn,0); pend = resolve->pending_connections; @@ -717,7 +424,7 @@ connection_dns_remove(edge_connection_t *conn) 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)); + conn->s, escaped_safe_str(conn->address)); return; } else { for ( ; pend->next; pend = pend->next) { @@ -727,7 +434,7 @@ connection_dns_remove(edge_connection_t *conn) 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)); + conn->s, escaped_safe_str(conn->address)); return; /* more are pending */ } } @@ -735,23 +442,59 @@ connection_dns_remove(edge_connection_t *conn) } } +/** Log an error and abort if conn is waiting for a DNS resolve. + */ +void +assert_connection_edge_not_dns_pending(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(pend->conn, 0); + tor_assert(pend->conn->s == -1); + tor_assert(!connection_in_array(pend->conn)); + } + } +} + /** 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) +dns_cancel_pending_resolve(char *address) { pending_connection_t *pend; cached_resolve_t search; - cached_resolve_t *resolve, *tmp; - edge_connection_t *pendconn; + cached_resolve_t *resolve; + 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) { + if (!resolve) { log_notice(LD_BUG,"Address %s is not pending. Dropping.", escaped_safe_str(address)); return; @@ -773,104 +516,84 @@ dns_cancel_pending_resolve(const char *address) escaped_safe_str(address)); while (resolve->pending_connections) { pend = resolve->pending_connections; - pend->conn->_base.state = EXIT_CONN_STATE_RESOLVEFAILED; + pend->conn->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) { + tor_assert(pendconn->s == -1); + if (!pendconn->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)); + connection_free(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; + dns_purge_resolve(resolve); } -/** Helper: adds an entry to the DNS cache mapping <b>address</b> to the ipv4 - * address <b>addr</b> (if is_reverse is 0) or the hostname <b>hostname</b> if - * (is_reverse is 1). <b>ttl</b> is a cache ttl; <b>outcome</b> is one of - * DNS_RESOLVE_{FAILED_TRANSIENT|FAILED_PERMANENT|SUCCEEDED}. - **/ +/** Remove <b>resolve</b> from the cache. + */ static void -add_answer_to_cache(const char *address, int is_reverse, uint32_t addr, - const char *hostname, char outcome, uint32_t ttl) +dns_purge_resolve(cached_resolve_t *resolve) { - cached_resolve_t *resolve; - if (outcome == DNS_RESOLVE_FAILED_TRANSIENT) - return; - - /* XXX This is dumb, but it seems to workaround a bug I can't find. We - * should nail this so we can cache reverse DNS answers. -NM */ - if (is_reverse) - return; + cached_resolve_t *tmp; - //log_notice(LD_EXIT, "Adding to cache: %s -> %s (%lx, %s), %d", - // address, is_reverse?"(reverse)":"", (unsigned long)addr, - // hostname?hostname:"NULL",(int)outcome); - - 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->is_reverse = is_reverse; - if (is_reverse) { - tor_assert(hostname); - resolve->result.hostname = tor_strdup(hostname); + /* remove resolve from the linked list */ + if (resolve == oldest_cached_resolve) { + oldest_cached_resolve = resolve->next; + if (oldest_cached_resolve == NULL) + newest_cached_resolve = NULL; } else { - tor_assert(!hostname); - resolve->result.addr = addr; + /* FFFF make it a doubly linked list if this becomes too slow */ + for (tmp=oldest_cached_resolve; tmp && tmp->next != resolve; tmp=tmp->next) + ; + tor_assert(tmp); /* it's got to be in the list, or we screwed up somewhere + * else */ + tmp->next = resolve->next; /* unlink it */ + + if (newest_cached_resolve == resolve) + newest_cached_resolve = tmp; } - resolve->ttl = ttl; - assert_resolve_ok(resolve); - HT_INSERT(cache_map, &cache_root, resolve); - set_expiry(resolve, time(NULL) + dns_get_expiry_ttl(ttl)); + + /* remove resolve from the map */ + HT_REMOVE(cache_map, &cache_root, resolve); + + tor_free(resolve); } -/** 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 +/** Called on the OR side when a DNS worker 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, int is_reverse, uint32_t addr, - const char *hostname, char outcome, uint32_t ttl) +dns_found_answer(char *address, uint32_t addr, char outcome) { pending_connection_t *pend; cached_resolve_t search; - cached_resolve_t *resolve, *removed; - edge_connection_t *pendconn; + cached_resolve_t *resolve; + 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, is_reverse, addr, hostname, outcome, ttl); + resolve = tor_malloc_zero(sizeof(cached_resolve_t)); + resolve->state = (outcome == DNS_RESOLVE_SUCCEEDED) ? + CACHE_STATE_VALID : CACHE_STATE_FAILED; + resolve->addr = addr; + resolve->expire = time(NULL) + MAX_DNS_ENTRY_AGE; + insert_resolve(resolve); return; } - assert_resolve_ok(resolve); if (resolve->state != CACHE_STATE_PENDING) { /* XXXX Maybe update addr? or check addr for consistency? Or let @@ -886,18 +609,23 @@ dns_found_answer(const char *address, int is_reverse, uint32_t addr, * resolve X.Y.Z. */ /* tor_assert(resolve->state == CACHE_STATE_PENDING); */ + resolve->addr = addr; + if (outcome == DNS_RESOLVE_SUCCEEDED) + resolve->state = CACHE_STATE_VALID; + else + resolve->state = CACHE_STATE_FAILED; + while (resolve->pending_connections) { pend = resolve->pending_connections; + assert_connection_ok(pend->conn,time(NULL)); + pend->conn->addr = resolve->addr; 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) { + if (resolve->state == CACHE_STATE_FAILED) { /* prevent double-remove. */ - pendconn->_base.state = EXIT_CONN_STATE_RESOLVEFAILED; - if (pendconn->_base.purpose == EXIT_PURPOSE_CONNECT) { + pendconn->state = EXIT_CONN_STATE_RESOLVEFAILED; + if (pendconn->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. */ @@ -907,109 +635,40 @@ dns_found_answer(const char *address, int is_reverse, uint32_t addr, /* 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)); + connection_free(pendconn); } else { - if (pendconn->_base.purpose == EXIT_PURPOSE_CONNECT) { - tor_assert(!is_reverse); + if (pendconn->purpose == EXIT_PURPOSE_CONNECT) { /* prevent double-remove. */ - pend->conn->_base.state = EXIT_CONN_STATE_CONNECTING; + pend->conn->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->next_stream = circ->n_streams; pend->conn->on_circuit = circ; - TO_OR_CIRCUIT(circ)->n_streams = pend->conn; + 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 (is_reverse) - send_resolved_hostname_cell(pendconn, hostname); - else - send_resolved_cell(pendconn, RESOLVED_TYPE_IPV4); + pendconn->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)); + connection_free(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); + if (outcome == DNS_RESOLVE_FAILED_TRANSIENT) { /* remove from cache */ + dns_purge_resolve(resolve); } - assert_resolve_ok(resolve); - assert_cache_ok(); - - add_answer_to_cache(address, is_reverse, addr, hostname, 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; } /******************************************************************/ @@ -1028,8 +687,6 @@ connection_dns_finished_flushing(connection_t *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) { @@ -1054,7 +711,6 @@ connection_dns_process_inbuf(connection_t *conn) { char success; uint32_t addr; - int ttl; tor_assert(conn); tor_assert(conn->type == CONN_TYPE_DNSWORKER); @@ -1090,9 +746,7 @@ connection_dns_process_inbuf(connection_t *conn) 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, 0, ntohl(addr), NULL, success, ttl); + dns_found_answer(conn->address, ntohl(addr), success); tor_free(conn->address); conn->address = tor_strdup("<idle>"); @@ -1109,7 +763,7 @@ connection_dns_process_inbuf(connection_t *conn) /** Close and re-open all idle dnsworkers; schedule busy ones to be closed * and re-opened once they're no longer busy. **/ -static void +void dnsworkers_rotate(void) { connection_t *dnsconn; @@ -1140,10 +794,10 @@ dnsworkers_rotate(void) * The dnsworker runs indefinitely, until its connection is closed or an error * occurs. */ -static void +static int dnsworker_main(void *data) { - char address[MAX_ADDRESSLEN+1]; /* Plus a byte for a final '.' */ + char address[MAX_ADDRESSLEN]; unsigned char address_len; char *log_address; char answer[5]; @@ -1151,7 +805,6 @@ dnsworker_main(void *data) int *fdarray = data; int fd; int result; - int search = get_options()->ServerDNSSearchDomains; /* log_fn(LOG_NOTICE,"After spawn: fdarray @%d has %d:%d", (int)fdarray, * fdarray[0],fdarray[1]); */ @@ -1189,13 +842,7 @@ dnsworker_main(void *data) 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'; - } + address[address_len] = 0; /* null terminate it */ log_address = esc_for_log(safe_str(address)); result = tor_lookup_hostname(address, &ip); @@ -1205,17 +852,17 @@ dnsworker_main(void *data) 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_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_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); + log_info(LD_NET,"Resolved address %s.", log_address); answer[0] = DNS_RESOLVE_SUCCEEDED; break; } @@ -1228,6 +875,7 @@ dnsworker_main(void *data) spawn_exit(); } } + return 0; /* windows wants this function to return an int */ } /** Launch a new DNS worker; return 0 on success, -1 on failure. @@ -1248,15 +896,12 @@ spawn_dnsworker(void) 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((void*) dnsworker_main, (void*)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 */ @@ -1347,424 +992,3 @@ spawn_enough_dnsworkers(void) return 0; } -void -dns_launch_wildcard_checks(void) -{ -} -#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->ServerDNSResolvConfFile or /etc/resolv.conf; on - * Windows, this reads from options->ServerDNSResolvConfFile 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->ServerDNSResolvConfFile; -#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()) { - log_warn(LD_EXIT,"Could not config 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 " - "ServerDNSResolvConfFile 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 is_reverse = 0; - int status = DNS_RESOLVE_FAILED_PERMANENT; - uint32_t addr = 0; - const char *hostname = NULL; - - if (result == DNS_ERR_NONE) { - if (type == DNS_IPv4_A && count) { - char answer_buf[INET_NTOA_BUF_LEN+1]; - struct in_addr in; - char *escaped_address; - 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)); - 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)); - addr = 0; - status = DNS_RESOLVE_FAILED_PERMANENT; - } 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; - is_reverse = 1; - hostname = ((char**)addresses)[0]; - status = DNS_RESOLVE_SUCCEEDED; - 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)); - } - } else { - if (eventdns_err_is_transient(result)) - status = DNS_RESOLVE_FAILED_TRANSIENT; - } - dns_found_answer(string_address, is_reverse, addr, hostname, 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); - struct in_addr in; - int r; - int options = get_options()->ServerDNSSearchDomains ? 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; - } - - r = parse_inaddr_arpa_address(exitconn->_base.address, &in); - if (r == 0) { - 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); - } else if (r == 1) { - log_info(LD_EXIT, "Launching eventdns reverse request for %s", - escaped_safe_str(exitconn->_base.address)); - r = eventdns_resolve_reverse(&in, DNS_QUERY_NO_SEARCH, - eventdns_callback, addr); - } else if (r == -1) { - log_warn(LD_BUG, "Somehow a malformed in-addr.arpa address reached here."); - } - - 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; -} - -/** 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; - -/** Called when we see <b>id</b> (a dotted quad) in response to a request for - * a hopefully bogus address. */ -static void -wildcard_increment_answer(const char *id) -{ - int *ip; - static int notice_given = 0; - 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_create(); - if (!smartlist_string_isin(dns_wildcard_list, id)) { - log(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 trying to correct for this by treating future occurrences of " - "\"%s\" as 'not found'.", id, *ip, id); - smartlist_add(dns_wildcard_list, tor_strdup(id)); - } - } -} - -/** Callback function when we get an answer (possibly failing) for a request - * for a (hopefully) nonexistent domain. */ -static void -eventdns_wildcard_check_callback(int result, char type, int count, int ttl, - void *addresses, void *arg) -{ - static int notice_given = 0; - (void)ttl; - ++n_wildcard_requests; - if (result == DNS_ERR_NONE && type == DNS_IPv4_A && count) { - uint32_t *addrs = addresses; - int i; - char *string_address = arg; - 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); - } - log(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 addresses so far.", - string_address, strmap_size(dns_wildcard_response_count)); - 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, const char *suffix) -{ - char random_bytes[20], name[64], *addr; - size_t len; - int r; - - len = min_len + crypto_rand_int(max_len-min_len+1); - if (crypto_rand(random_bytes, sizeof(random_bytes)) < 0) - return; - base32_encode(name, sizeof(name), random_bytes, sizeof(random_bytes)); - name[len] = '\0'; - strlcat(name, suffix, sizeof(name)); - - addr = tor_strdup(name); - r = eventdns_resolve_ipv4(name, DNS_QUERY_NO_SEARCH, - eventdns_wildcard_check_callback, addr); - if (r) - tor_free(addr); -} - -#define N_WILDCARD_CHECKS 2 - -/** Launch DNS requests for a few nonexistent 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. */ -void -dns_launch_wildcard_checks(void) -{ - int i; - if (!get_options()->ServerDNSDetectHijacking) - return; - log_info(LD_EXIT, "Launching checks to see whether our nameservers like " - "to hijack DNS failures."); - 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-complaince equivalent of making sure that your - * crackhouse's elevator inspection certificate is up to date. - */ - launch_wildcard_check(2, 16, "%s.invalid"); - launch_wildcard_check(2, 16, "%s.test"); - - /* Thy somese will break specs if there are ever any number of - * 8+-character top-level domains. */ - launch_wildcard_check(8, 16,""); - - /* 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, "%s.com"); - launch_wildcard_check(8, 16, "%s.org"); - launch_wildcard_check(8, 16, "%s.net"); - } -} - -/** 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_string_isin(dns_wildcard_list, ip); -} -#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); - if (resolve->is_reverse) - tor_assert(!resolve->result.hostname); - else - tor_assert(!resolve->result.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 - |