Allow http connections to use evdns for hostname looksups.

This was as simple as using bufferevent_connect_hostname instead of
calling connect() ourself, which already knows how to use an
evdns_base if it gets one.

Untangling the bind code might be a little trickier.

http-internal.h

@@ -97,6 +97,7 @@ struct evhttp_connection {
 	void *closecb_arg;
 
 	struct event_base *base;
+	struct evdns_base *dns_base;
 };
 
 struct evhttp_cb {

http.c

@@ -155,7 +155,6 @@ fake_getnameinfo(const struct sockaddr *sa, size_t salen, char *host,
 
 extern int debug;
 
-static int socket_connect(evutil_socket_t kefd, const char *address, unsigned short port);
 static evutil_socket_t bind_socket_ai(struct evutil_addrinfo *, int reuse);
 static evutil_socket_t bind_socket(const char *, ev_uint16_t, int reuse);
 static void name_from_addr(struct sockaddr *, ev_socklen_t, char **, char **);
@@ -1149,16 +1148,26 @@ evhttp_error_cb(struct bufferevent *bufev, short what, void *arg)
 }
 
 /*
- * Call back for asynchronous connection attempt.
+ * Event callback for asynchronous connection attempt.
  */
-
 static void
-evhttp_connection_cb(struct bufferevent *bufev, void *arg)
+evhttp_connection_cb(struct bufferevent *bufev, short what, void *arg)
 {
 	struct evhttp_connection *evcon = arg;
 	int error;
 	ev_socklen_t errsz = sizeof(error);
 
+	if (!(what & BEV_EVENT_CONNECTED)) {
+		/* some operating systems return ECONNREFUSED immediately
+		 * when connecting to a local address.  the cleanup is going
+		 * to reschedule this function call.
+		 */
+		if (errno == ECONNREFUSED)
+			goto cleanup;
+		evhttp_error_cb(bufev, what, arg);
+		return;
+	}
+
 	/* Check if the connection completed */
 	if (getsockopt(evcon->fd, SOL_SOCKET, SO_ERROR, (void*)&error,
 		       &errsz) == -1) {
@@ -1784,6 +1793,14 @@ evhttp_connection_base_new(struct event_base *base,
 	return (NULL);
 }
 
+void
+evhttp_connection_set_evdns_base(struct evhttp_connection *evcon,
+    struct evdns_base *base)
+{
+	EVUTIL_ASSERT(evcon->dns_base == NULL);
+	evcon->dns_base = base;
+}
+
 void
 evhttp_connection_set_base(struct evhttp_connection *evcon,
     struct event_base *base)
@@ -1850,7 +1867,20 @@ evhttp_connection_connect(struct evhttp_connection *evcon)
 		return (-1);
 	}
 
-	if (socket_connect(evcon->fd, evcon->address, evcon->port) == -1) {
+	/* Set up a callback for successful connection setup */
+	bufferevent_setfd(evcon->bufev, evcon->fd);
+	bufferevent_setcb(evcon->bufev,
+	    NULL /* evhttp_read_cb */,
+	    NULL /* evhttp_write_cb */,
+	    evhttp_connection_cb,
+	    evcon);
+	bufferevent_settimeout(evcon->bufev, 0,
+	    evcon->timeout != -1 ? evcon->timeout : HTTP_CONNECT_TIMEOUT);
+	/* make sure that we get a write callback */
+	bufferevent_enable(evcon->bufev, EV_WRITE);
+
+	if (bufferevent_socket_connect_hostname(evcon->bufev, evcon->dns_base,
+		AF_UNSPEC, evcon->address, evcon->port) < 0) {
 		event_sock_warn(evcon->fd, "%s: connection to \"%s\" failed",
 		    __func__, evcon->address);
 		/* some operating systems return ECONNREFUSED immediately
@@ -1861,17 +1891,6 @@ evhttp_connection_connect(struct evhttp_connection *evcon)
 		return (0);
 	}
 
-	/* Set up a callback for successful connection setup */
-	bufferevent_setfd(evcon->bufev, evcon->fd);
-	bufferevent_setcb(evcon->bufev,
-	    NULL /* evhttp_read_cb */,
-	    evhttp_connection_cb,
-	    evhttp_error_cb, evcon);
-	bufferevent_settimeout(evcon->bufev, 0,
-	    evcon->timeout != -1 ? evcon->timeout : HTTP_CONNECT_TIMEOUT);
-	/* make sure that we get a write callback */
-	bufferevent_enable(evcon->bufev, EV_WRITE);
-
 	evcon->state = EVCON_CONNECTING;
 
 	return (0);
@@ -3114,29 +3133,3 @@ bind_socket(const char *address, ev_uint16_t port, int reuse)
 	return (fd);
 }
 
-static int
-socket_connect(evutil_socket_t fd, const char *address, unsigned short port)
-{
-	struct evutil_addrinfo *ai = make_addrinfo(address, port);
-	int res = -1;
-
-	if (ai == NULL) {
-		event_debug(("%s: make_addrinfo: \"%s:%d\"",
-			__func__, address, port));
-		return (-1);
-	}
-
-	if (connect(fd, ai->ai_addr, ai->ai_addrlen) == -1) {
-		int err = evutil_socket_geterror(fd);
-		if (! EVUTIL_ERR_CONNECT_RETRIABLE(err))
-			goto out;
-	}
-
-	/* everything is fine */
-	res = 0;
-
-out:
-	evutil_freeaddrinfo(ai);
-
-	return (res);
-}

include/event2/http.h

@@ -355,12 +355,20 @@ void evhttp_request_free(struct evhttp_request *req);
 
 /**
  * A connection object that can be used to for making HTTP requests.  The
- * connection object tries to establish the connection when it is given an
+ * connection object tries to resolve address and establish the connection
- * http request object.
+ * when it is given an http request object.
  */
 struct evhttp_connection *evhttp_connection_base_new(
 	struct event_base *base, const char *address, unsigned short port);
 
+struct evdns_base;
+/**
+ * Tell the connection object to use evdns_base when resolving hostnames.
+ * If no base is set, it will block when resolving hostnames.
+ */
+void evhttp_connection_set_evdns_base(struct evhttp_connection *evcon,
+	struct evdns_base *base);
+
 /** Takes ownership of the request object
  *
  * Can be used in a request callback to keep onto the request until