evdns: export cancel via callbacks in util (like async lib core/extra…

… issues)

evdns.c

@@ -3908,6 +3908,7 @@ evdns_base_new(struct event_base *event_base, int flags)
 	 * functionality.  We can't just call evdns_getaddrinfo directly or
 	 * else libevent-core will depend on libevent-extras. */
 	evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo);
+	evutil_set_evdns_getaddrinfo_cancel_fn_(evdns_getaddrinfo_cancel);
 
 	base = mm_malloc(sizeof(struct evdns_base));
 	if (base == NULL)

evutil.c

@@ -1546,34 +1546,48 @@ evutil_freeaddrinfo(struct evutil_addrinfo *ai)
 }
 
 static evdns_getaddrinfo_fn evdns_getaddrinfo_impl = NULL;
+static evdns_getaddrinfo_cancel_fn evdns_getaddrinfo_cancel_impl = NULL;
 
 void
 evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo_fn fn)
 {
 	if (!evdns_getaddrinfo_impl)
 		evdns_getaddrinfo_impl = fn;
 }
+void
+evutil_set_evdns_getaddrinfo_cancel_fn_(evdns_getaddrinfo_cancel_fn fn)
+{
+	if (!evdns_getaddrinfo_cancel_impl)
+		evdns_getaddrinfo_cancel_impl = fn;
+}
 
 /* Internal helper function: act like evdns_getaddrinfo if dns_base is set;
  * otherwise do a blocking resolve and pass the result to the callback in the
  * way that evdns_getaddrinfo would.
  */
-int
-evutil_getaddrinfo_async_(struct evdns_base *dns_base,
+struct evdns_getaddrinfo_request *evutil_getaddrinfo_async_(
+    struct evdns_base *dns_base,
     const char *nodename, const char *servname,
     const struct evutil_addrinfo *hints_in,
     void (*cb)(int, struct evutil_addrinfo *, void *), void *arg)
 {
 	if (dns_base && evdns_getaddrinfo_impl) {
-		evdns_getaddrinfo_impl(
+		return evdns_getaddrinfo_impl(
 			dns_base, nodename, servname, hints_in, cb, arg);
 	} else {
 		struct evutil_addrinfo *ai=NULL;
 		int err;
 		err = evutil_getaddrinfo(nodename, servname, hints_in, &ai);
 		cb(err, ai, arg);
+		return NULL;
+	}
+}
+
+void evutil_getaddrinfo_cancel_async_(struct evdns_getaddrinfo_request *data)
+{
+	if (evdns_getaddrinfo_cancel_impl && data) {
+		evdns_getaddrinfo_cancel_impl(data);
 	}
-	return 0;
 }
 
 const char *

util-internal.h

@@ -357,8 +357,10 @@ typedef struct evdns_getaddrinfo_request* (*evdns_getaddrinfo_fn)(
     const char *nodename, const char *servname,
     const struct evutil_addrinfo *hints_in,
     void (*cb)(int, struct evutil_addrinfo *, void *), void *arg);
-
 void evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo_fn fn);
+typedef void (*evdns_getaddrinfo_cancel_fn)(
+    struct evdns_getaddrinfo_request *req);
+void evutil_set_evdns_getaddrinfo_cancel_fn_(evdns_getaddrinfo_cancel_fn fn);
 
 struct evutil_addrinfo *evutil_new_addrinfo_(struct sockaddr *sa,
     ev_socklen_t socklen, const struct evutil_addrinfo *hints);
@@ -368,10 +370,12 @@ void evutil_adjust_hints_for_addrconfig_(struct evutil_addrinfo *hints);
 int evutil_getaddrinfo_common_(const char *nodename, const char *servname,
     struct evutil_addrinfo *hints, struct evutil_addrinfo **res, int *portnum);
 
-int evutil_getaddrinfo_async_(struct evdns_base *dns_base,
+struct evdns_getaddrinfo_request *evutil_getaddrinfo_async_(
+    struct evdns_base *dns_base,
     const char *nodename, const char *servname,
     const struct evutil_addrinfo *hints_in,
     void (*cb)(int, struct evutil_addrinfo *, void *), void *arg);
+void evutil_getaddrinfo_cancel_async_(struct evdns_getaddrinfo_request *data);
 
 /** Return true iff sa is a looback address. (That is, it is 127.0.0.1/8, or
  * ::1). */