Commit 85a25c8a authored by Nick Mathewson's avatar Nick Mathewson 🏃
Browse files

Make dns.c use eventdns.c -- but only when you pass the --enable-eventdns...

Make dns.c use eventdns.c -- but only when you pass the --enable-eventdns argument to configure.in.  This will *so* not work on Windows yet.


svn:r6525
parent 7cb3232a
......@@ -21,6 +21,9 @@ const char dns_c_id[] =
#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
......@@ -39,12 +42,14 @@ const char dns_c_id[] =
#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;
#endif
/** Linked list of connections waiting for a DNS answer. */
typedef struct pending_connection_t {
......@@ -71,13 +76,17 @@ typedef struct cached_resolve_t {
} cached_resolve_t;
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 void dns_found_answer(char *address, uint32_t addr, char outcome,
uint32_t ttl);
static void send_resolved_cell(connection_t *conn, uint8_t answer_type,
uint32_t ttl);
static int assign_to_dnsworker(connection_t *exitconn);
#ifndef USE_EVENTDNS
static int dnsworker_main(void *data);
static int spawn_dnsworker(void);
static int spawn_enough_dnsworkers(void);
static void send_resolved_cell(connection_t *conn, uint8_t answer_type);
#endif
/** Hash table of cached_resolve objects. */
static HT_HEAD(cache_map, cached_resolve_t) cache_root;
......@@ -115,6 +124,10 @@ dns_init(void)
{
init_cache_map();
dnsworkers_rotate();
#ifdef USE_EVENTDNS
eventdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS|DNS_OPTION_MISC,
"/etc/resolv.conf");
#endif
}
/** Helper: free storage held by an entry in the DNS cache. */
......@@ -199,7 +212,7 @@ purge_expired_resolves(uint32_t now)
/** 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(connection_t *conn, uint8_t answer_type)
send_resolved_cell(connection_t *conn, uint8_t answer_type, uint32_t ttl)
{
char buf[RELAY_PAYLOAD_SIZE];
size_t buflen;
......@@ -211,7 +224,7 @@ send_resolved_cell(connection_t *conn, uint8_t answer_type)
case RESOLVED_TYPE_IPV4:
buf[1] = 4;
set_uint32(buf+2, htonl(conn->addr));
set_uint32(buf+6, htonl(MAX_DNS_ENTRY_AGE)); /*XXXX send a real TTL*/
set_uint32(buf+6, htonl(ttl));
buflen = 10;
break;
case RESOLVED_TYPE_ERROR_TRANSIENT:
......@@ -219,10 +232,10 @@ send_resolved_cell(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((uint32_t)ttl));
set_uint32(buf+2+msglen, htonl(ttl));
buflen = 6+msglen;
break;
}
......@@ -277,7 +290,7 @@ dns_resolve(connection_t *exitconn)
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);
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4, MAX_DNS_ENTRY_AGE);
return 1;
}
......@@ -291,7 +304,10 @@ dns_resolve(connection_t *exitconn)
/* now check the hash table to see if 'address' is already there. */
strlcpy(search.address, exitconn->address, sizeof(search.address));
resolve = HT_FIND(cache_map, &cache_root, &search);
if (resolve) { /* already there */
if (resolve && resolve->expire > now) { /* already there */
// XXXX Security problem: this leaks a time at which somebody asked for
// XXXX the address. That's a problem.
unsigned int ttl = (unsigned int) resolve->expire - now;
switch (resolve->state) {
case CACHE_STATE_PENDING:
/* add us to the pending list */
......@@ -310,13 +326,13 @@ dns_resolve(connection_t *exitconn)
log_debug(LD_EXIT,"Connection (fd %d) found cached answer for %s",
exitconn->s, escaped_safe_str(exitconn->address));
if (exitconn->purpose == EXIT_PURPOSE_RESOLVE)
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4, ttl);
return 1;
case CACHE_STATE_FAILED:
log_debug(LD_EXIT,"Connection (fd %d) found cached error for %s",
exitconn->s, escaped_safe_str(exitconn->address));
if (exitconn->purpose == EXIT_PURPOSE_RESOLVE)
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR, ttl);
circ = circuit_get_by_edge_conn(exitconn);
if (circ)
circuit_detach_stream(circ, exitconn);
......@@ -344,51 +360,40 @@ dns_resolve(connection_t *exitconn)
return assign_to_dnsworker(exitconn);
}
/** Find or spawn a dns worker process to handle resolving
* <b>exitconn</b>-\>address; tell that dns worker to begin resolving.
/** Log an error and abort if conn is waiting for a DNS resolve.
*/
static int
assign_to_dnsworker(connection_t *exitconn)
void
assert_connection_edge_not_dns_pending(connection_t *conn)
{
connection_t *dnsconn;
unsigned char len;
tor_assert(exitconn->state == EXIT_CONN_STATE_RESOLVING);
tor_assert(exitconn->s == -1);
pending_connection_t *pend;
cached_resolve_t **resolve;
/* respawn here, to be sure there are enough */
if (spawn_enough_dnsworkers() < 0) {
goto err;
HT_FOREACH(resolve, cache_map, &cache_root) {
for (pend = (*resolve)->pending_connections;
pend;
pend = pend->next) {
tor_assert(pend->conn != conn);
}
}
}
dnsconn = connection_get_by_type_state(CONN_TYPE_DNSWORKER,
DNSWORKER_STATE_IDLE);
/** 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;
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;
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));
}
}
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;
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.
......@@ -440,42 +445,6 @@ connection_dns_remove(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.
......@@ -570,7 +539,7 @@ dns_purge_resolve(cached_resolve_t *resolve)
* DNS_RESOLVE_{FAILED_TRANSIENT|FAILED_PERMANENT|SUCCEEDED}.
*/
static void
dns_found_answer(char *address, uint32_t addr, char outcome)
dns_found_answer(char *address, uint32_t addr, char outcome, uint32_t ttl)
{
pending_connection_t *pend;
cached_resolve_t search;
......@@ -588,7 +557,7 @@ dns_found_answer(char *address, uint32_t addr, char outcome)
resolve->state = (outcome == DNS_RESOLVE_SUCCEEDED) ?
CACHE_STATE_VALID : CACHE_STATE_FAILED;
resolve->addr = addr;
resolve->expire = time(NULL) + MAX_DNS_ENTRY_AGE;
resolve->expire = time(NULL) + ttl;
insert_resolve(resolve);
return;
}
......@@ -608,6 +577,7 @@ dns_found_answer(char *address, uint32_t addr, char outcome)
/* tor_assert(resolve->state == CACHE_STATE_PENDING); */
resolve->addr = addr;
resolve->expire = time(NULL) + ttl;
if (outcome == DNS_RESOLVE_SUCCEEDED)
resolve->state = CACHE_STATE_VALID;
else
......@@ -629,7 +599,7 @@ dns_found_answer(char *address, uint32_t addr, char outcome)
/* 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);
send_resolved_cell(pendconn, RESOLVED_TYPE_ERROR, ttl);
/* This detach must happen after we send the resolved cell. */
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
}
......@@ -653,7 +623,7 @@ dns_found_answer(char *address, uint32_t addr, char outcome)
/* prevent double-remove. This isn't really an accurate state,
* but it does the right thing. */
pendconn->state = EXIT_CONN_STATE_RESOLVEFAILED;
send_resolved_cell(pendconn, RESOLVED_TYPE_IPV4);
send_resolved_cell(pendconn, RESOLVED_TYPE_IPV4, ttl);
circ = circuit_get_by_edge_conn(pendconn);
tor_assert(circ);
circuit_detach_stream(circ, pendconn);
......@@ -669,6 +639,54 @@ dns_found_answer(char *address, uint32_t addr, char outcome)
}
}
#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
assign_to_dnsworker(connection_t *exitconn)
{
connection_t *dnsconn;
unsigned char len;
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;
}
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->purpose == EXIT_PURPOSE_RESOLVE)
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT, 0);
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;
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;
}
/******************************************************************/
/*
......@@ -709,6 +727,7 @@ connection_dns_process_inbuf(connection_t *conn)
{
char success;
uint32_t addr;
int ttl;
tor_assert(conn);
tor_assert(conn->type == CONN_TYPE_DNSWORKER);
......@@ -744,7 +763,9 @@ connection_dns_process_inbuf(connection_t *conn)
tor_assert(success >= DNS_RESOLVE_FAILED_TRANSIENT);
tor_assert(success <= DNS_RESOLVE_SUCCEEDED);
dns_found_answer(conn->address, ntohl(addr), success);
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>");
......@@ -989,4 +1010,85 @@ spawn_enough_dnsworkers(void)
return 0;
}
#else /* !USE_EVENTDNS */
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;
}
}
void
dnsworkers_rotate(void)
{
}
int
connection_dns_finished_flushing(connection_t *conn)
{
tor_assert(0);
return 0;
}
int
connection_dns_process_inbuf(connection_t *conn)
{
tor_assert(0);
return 0;
}
int
connection_dns_reached_eof(connection_t *conn)
{
tor_assert(0);
return 0;
}
static void
eventdns_callback(int result, char type, int count, int ttl, void *addresses,
void *arg)
{
char *string_address = arg;
if (result == DNS_ERR_NONE) {
if (type == DNS_IPv4_A && count) {
uint32_t *addrs = addresses;
dns_found_answer(string_address, addrs[0], DNS_RESOLVE_SUCCEEDED, ttl);
} else if (count) {
log_warn(LD_EXIT, "eventdns returned only non-IPv4 answers for %s.",
escaped_safe_str(string_address));
dns_found_answer(string_address, 0, DNS_RESOLVE_FAILED_PERMANENT, ttl);
} else {
log_warn(LD_BUG, "eventdns returned no addresses or error for %s!",
escaped_safe_str(string_address));
dns_found_answer(string_address, 0, DNS_RESOLVE_FAILED_PERMANENT, ttl);
}
} else {
int err = eventdns_err_is_transient(result)
? DNS_RESOLVE_FAILED_TRANSIENT : DNS_RESOLVE_FAILED_PERMANENT;
dns_found_answer(string_address, 0, err, ttl);
}
tor_free(string_address);
}
static int assign_to_dnsworker(connection_t *exitconn)
{
char *addr = tor_strdup(exitconn->address);
int r = eventdns_resolve(exitconn->address, DNS_QUERY_NO_SEARCH,
eventdns_callback, addr);
if (r) {
log_warn(LD_EXIT, "eventdns rejected address %s: error %d.",
escaped_safe_str(addr), r);
if (exitconn->purpose == EXIT_PURPOSE_RESOLVE) {
if (eventdns_err_is_transient(r))
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT, 0);
else
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR, MAX_DNS_ENTRY_AGE);
}
dns_cancel_pending_resolve(addr);/* also sends end and frees */
tor_free(addr);
}
return r ? -1 : 0;
}
#endif /* USE_EVENTDNS */
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