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Avoid segfault on weird timeout during name lookup.

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If an evdns_getaddrinfo timeout happens while pending_cb is set, and
a callback is about to run, but we get a call to
evdns_getaddrinfo_gotresolve before it finishes.

Github issue #60. Thanks to Greg Hazel for patch and patience.
This commit is contained in:
Greg Hazel 2012-07-30 16:52:55 -04:00 committed by Nick Mathewson
parent a0912e3206
commit dc3207767d
1 changed files with 15 additions and 0 deletions
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15
evdns.c
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@ -4214,6 +4214,8 @@ evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
/* Cancel any pending requests, and note which one */
if (data->ipv4_request.r) {
/* XXXX This does nothing if the request's callback is already
* running (pending_cb is set). */
evdns_cancel_request(NULL, data->ipv4_request.r);
v4_timedout = 1;
EVDNS_LOCK(data->evdns_base);
@ -4221,6 +4223,8 @@ evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
EVDNS_UNLOCK(data->evdns_base);
}
if (data->ipv6_request.r) {
/* XXXX This does nothing if the request's callback is already
* running (pending_cb is set). */
evdns_cancel_request(NULL, data->ipv6_request.r);
v6_timedout = 1;
EVDNS_LOCK(data->evdns_base);
@ -4244,6 +4248,10 @@ evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr)
data->user_cb(e, NULL, data->user_data);
}
data->user_cb = NULL; /* prevent double-call if evdns callbacks are
* in-progress. XXXX It would be better if this
* weren't necessary. */
if (!v4_timedout && !v6_timedout) {
/* should be impossible? XXXX */
free_getaddrinfo_request(data);
@ -4314,6 +4322,13 @@ evdns_getaddrinfo_gotresolve(int result, char type, int count,
return;
}
if (data->user_cb == NULL) {
/* We already answered. XXXX This shouldn't be needed; see
* comments in evdns_getaddrinfo_timeout_cb */
free_getaddrinfo_request(data);
return;
}
if (result == DNS_ERR_NONE) {
if (count == 0)
err = EVUTIL_EAI_NODATA;