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Fix a potentially very annoying evdns bug that we found in Tor.

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Generally speaking, it way better to event_assign() an event when you
allocate it than to assign it before every time you event_add it: if
it is already event_add()ed, the assign will mess it up so that it
doesn't _look_ added, and event_add() will insert a second copy.
Later, event_del() will only delete the second copy.  Eventually, the
event_base will have a dangling pointer to freed memory.  Ouch!

svn:r1307
This commit is contained in:
Nick Mathewson 2009-05-22 18:20:59 +00:00
parent 7a844735d5
commit 7289d7f800
1 changed files with 4 additions and 6 deletions
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10
evdns.c
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@ -559,8 +559,6 @@ nameserver_probe_failed(struct nameserver *const ns) {
global_nameserver_timeouts_length - 1)]; global_nameserver_timeouts_length - 1)];
ns->failed_times++; ns->failed_times++;
evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) { if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) {
log(EVDNS_LOG_WARN, log(EVDNS_LOG_WARN,
"Error from libevent when adding timer event for %s", "Error from libevent when adding timer event for %s",
@ -593,8 +591,6 @@ nameserver_failed(struct nameserver *const ns, const char *msg) {
ns->state = 0; ns->state = 0;
ns->failed_times = 1; ns->failed_times = 1;
evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) { if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) {
log(EVDNS_LOG_WARN, log(EVDNS_LOG_WARN,
"Error from libevent when adding timer event for %s", "Error from libevent when adding timer event for %s",
@ -2191,8 +2187,6 @@ evdns_request_transmit(struct evdns_request *req) {
/* all ok */ /* all ok */
log(EVDNS_LOG_DEBUG, log(EVDNS_LOG_DEBUG,
"Setting timeout for request %lx", (unsigned long) req); "Setting timeout for request %lx", (unsigned long) req);
evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) { if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) {
log(EVDNS_LOG_WARN, log(EVDNS_LOG_WARN,
"Error from libevent when adding timer for request %lx", "Error from libevent when adding timer for request %lx",
@ -2411,6 +2405,8 @@ _evdns_nameserver_add_impl(struct evdns_base *base, const struct sockaddr *addre
memset(ns, 0, sizeof(struct nameserver)); memset(ns, 0, sizeof(struct nameserver));
ns->base = base; ns->base = base;
evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns);
ns->socket = socket(PF_INET, SOCK_DGRAM, 0); ns->socket = socket(PF_INET, SOCK_DGRAM, 0);
if (ns->socket < 0) { err = 1; goto out1; } if (ns->socket < 0) { err = 1; goto out1; }
evutil_make_socket_nonblocking(ns->socket); evutil_make_socket_nonblocking(ns->socket);
@ -2600,6 +2596,8 @@ request_new(struct evdns_base *base, int type, const char *name, int flags,
memset(req, 0, sizeof(struct evdns_request)); memset(req, 0, sizeof(struct evdns_request));
req->base = base; req->base = base;
evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req);
if (base->global_randomize_case) { if (base->global_randomize_case) {
unsigned i; unsigned i;
char randbits[(sizeof(namebuf)+7)/8]; char randbits[(sizeof(namebuf)+7)/8];