Make evdns_getaddrinfo_cancel threadsafe

diff --git a/evdns.c b/evdns.c
index 85b54c666ada64e481eefbefbf84c48a78e71fa8..b357606d28f67e935e8a05d2bcbac2d5586780af 100644 (file)
--- a/evdns.c
+++ b/evdns.c
@@ -4060,6 +4060,9 @@ struct evdns_getaddrinfo_request {
        int pending_error;
        /* If this is set, the user canceled this request. */
        unsigned user_canceled : 1;
+       /* If this is set, the user can no longer cancel this request; we're
+        * just waiting for the free. */
+       unsigned request_done : 1;
 };
 
 /* Convert an evdns errors to the equivalent getaddrinfo error. */
@@ -4189,29 +4192,32 @@ evdns_getaddrinfo_gotresolve(int result, char type, int count,
        int socklen, addrlen;
        void *addrp;
        int err;
+       int user_canceled;
 
        EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA);
        if (req->type == DNS_IPv4_A) {
                data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request);
                other_req = &data->ipv6_request;
-               if (evdns_result_is_answer(result)) {
-                       EVDNS_LOCK(data->evdns_base);
-                       ++data->evdns_base->getaddrinfo_ipv4_answered;
-                       EVDNS_UNLOCK(data->evdns_base);
-               }
        } else {
                data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request);
                other_req = &data->ipv4_request;
-               if (evdns_result_is_answer(result)) {
-                       EVDNS_LOCK(data->evdns_base);
+       }
+
+       EVDNS_LOCK(data->evdns_base);
+       if (evdns_result_is_answer(result)) {
+               if (req->type == DNS_IPv4_A)
+                       ++data->evdns_base->getaddrinfo_ipv4_answered;
+               else
                        ++data->evdns_base->getaddrinfo_ipv6_answered;
-                       EVDNS_UNLOCK(data->evdns_base);
-               }
        }
+       user_canceled = data->user_canceled;
+       if (other_req->r == NULL)
+               data->request_done = 1;
+       EVDNS_UNLOCK(data->evdns_base);
 
        req->r = NULL;
 
-       if (result == DNS_ERR_CANCEL && ! data->user_canceled) {
+       if (result == DNS_ERR_CANCEL && ! user_canceled) {
                /* Internal cancel request from timeout or internal error.
                 * we already answered the user. */
                if (other_req->r == NULL)
@@ -4239,7 +4245,7 @@ evdns_getaddrinfo_gotresolve(int result, char type, int count,
                        return;
                }
 
-               if (data->user_canceled) {
+               if (user_canceled) {
                        data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data);
                } else if (data->pending_result) {
                        /* If we have an answer waiting, and we weren't
@@ -4255,7 +4261,7 @@ evdns_getaddrinfo_gotresolve(int result, char type, int count,
                }
                free_getaddrinfo_request(data);
                return;
-       } else if (data->user_canceled) {
+       } else if (user_canceled) {
                if (other_req->r) {
                        /* The other request is still working; let it hit this
                         * callback with EVUTIL_EAI_CANCEL callback and report
@@ -4524,10 +4530,16 @@ evdns_getaddrinfo(struct evdns_base *dns_base,
 void
 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data)
 {
+       EVDNS_LOCK(data->evdns_base);
+       if (data->request_done) {
+               EVDNS_UNLOCK(data->evdns_base);
+               return;
+       }
        event_del(&data->timeout);
        data->user_canceled = 1;
        if (data->ipv4_request.r)
                evdns_cancel_request(data->evdns_base, data->ipv4_request.r);
        if (data->ipv6_request.r)
                evdns_cancel_request(data->evdns_base, data->ipv6_request.r);
+       EVDNS_UNLOCK(data->evdns_base);
 }