From: Marko Kreen <markokr@gmail.com>
Date: Wed, 17 Nov 2010 13:09:49 +0000 (+0200)
Subject: Support canceling ongoing DNS requests.
X-Git-Tag: pgbouncer_1_4_rc3~10
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c86cb165946e41ac534b9ca74b30b2555aca4c2b;p=pgbouncer

Support canceling ongoing DNS requests.

This should avoid problems when server_disconnect()
is called during DNS processing.
---

diff --git a/include/bouncer.h b/include/bouncer.h
index 0e59b4c..5d2727c 100644
--- a/include/bouncer.h
+++ b/include/bouncer.h
@@ -290,6 +290,8 @@ struct PgSocket {
 	PgAddr remote_addr;	/* ip:port for remote endpoint */
 	PgAddr local_addr;	/* ip:port for local endpoint */
 
+	struct DNSToken *dns_token;	/* ongoing request */
+
 	VarCache vars;		/* state of interesting server parameters */
 
 	SBuf sbuf;		/* stream buffer, must be last */
diff --git a/include/dnslookup.h b/include/dnslookup.h
index 38e529a..28459ff 100644
--- a/include/dnslookup.h
+++ b/include/dnslookup.h
@@ -35,6 +35,7 @@
 
 
 struct DNSContext;
+struct DNSToken;
 
 typedef void (*adns_callback_f)(void *arg, const struct sockaddr *sa, int salen);
 
@@ -42,5 +43,7 @@ struct DNSContext *adns_create_context(void);
 void adns_reload(struct DNSContext *ctx);
 void adns_free_context(struct DNSContext *ctx);
 
-void adns_resolve(struct DNSContext *ctx, const char *name, adns_callback_f cb_func, void *arg);
+struct DNSToken *adns_resolve(struct DNSContext *ctx, const char *name, adns_callback_f cb_func, void *arg);
+
+void adns_cancel(struct DNSContext *ctx, struct DNSToken *tk);
 
diff --git a/src/dnslookup.c b/src/dnslookup.c
index 0e9038e..245769e 100644
--- a/src/dnslookup.c
+++ b/src/dnslookup.c
@@ -42,7 +42,7 @@
 #endif
 
 
-struct UserCallback {
+struct DNSToken {
 	struct List node;
 	adns_callback_f cb_func;
 	void *cb_arg;
@@ -312,7 +312,7 @@ static void impl_release(struct DNSContext *ctx)
 
 static void deliver_info(struct DNSRequest *req)
 {
-	struct UserCallback *ucb;
+	struct DNSToken *ucb;
 	struct List *el;
 	const struct addrinfo *ai = req->current;
 	char sabuf[128];
@@ -322,7 +322,7 @@ loop:
 	el = list_pop(&req->ucb_list);
 	if (!el)
 		return;
-	ucb = container_of(el, struct UserCallback, node);
+	ucb = container_of(el, struct DNSToken, node);
 
 	/* launch callback */
 	log_noise("dns: deliver_info(%s) addr=%s", req->name,
@@ -359,12 +359,12 @@ static void req_reset(struct DNSRequest *req)
 
 static void req_free(struct AANode *node, void *arg)
 {
-	struct UserCallback *ucb;
+	struct DNSToken *ucb;
 	struct DNSRequest *req;
 	struct List *el;
 	req = container_of(node, struct DNSRequest, node);
 	while ((el = list_pop(&req->ucb_list)) != NULL) {
-		ucb = container_of(el, struct UserCallback, node);
+		ucb = container_of(el, struct DNSToken, node);
 		free(ucb);
 	}
 	req_reset(req);
@@ -395,11 +395,11 @@ void adns_free_context(struct DNSContext *ctx)
 	}
 }
 
-void adns_resolve(struct DNSContext *ctx, const char *name, adns_callback_f cb_func, void *cb_arg)
+struct DNSToken *adns_resolve(struct DNSContext *ctx, const char *name, adns_callback_f cb_func, void *cb_arg)
 {
 	int namelen = strlen(name);
 	struct DNSRequest *req;
-	struct UserCallback *ucb;
+	struct DNSToken *ucb;
 	struct AANode *node;
 
 	/* setup actual lookup */
@@ -441,10 +441,11 @@ void adns_resolve(struct DNSContext *ctx, const char *name, adns_callback_f cb_f
 		} else
 			deliver_info(req);
 	}
-	return;
+	return ucb;
 nomem:
 	log_warning("dns(%s): req failed, no mem", name);
 	cb_func(cb_arg, NULL, 0);
+	return NULL;
 }
 
 /* struct addrinfo -> deliver_info() */
@@ -468,3 +469,10 @@ static void got_result_gai(int result, struct addrinfo *res, void *arg)
 	deliver_info(req);
 }
 
+void adns_cancel(struct DNSContext *ctx, struct DNSToken *tk)
+{
+	list_del(&tk->node);
+	memset(tk, 0, sizeof(*tk));
+	free(tk);
+}
+
diff --git a/src/objects.c b/src/objects.c
index bd3521f..69b5dd4 100644
--- a/src/objects.c
+++ b/src/objects.c
@@ -750,6 +750,11 @@ void disconnect_server(PgSocket *server, bool notify, const char *reason, ...)
 			notify = false;
 	}
 
+	if (server->dns_token) {
+		adns_cancel(adns, server->dns_token);
+		server->dns_token = NULL;
+	}
+
 	change_server_state(server, SV_JUSTFREE);
 	if (!sbuf_close(&server->sbuf))
 		log_noise("sbuf_close failed, retry later");
@@ -842,6 +847,8 @@ static void dns_callback(void *arg, const struct sockaddr *sa, int salen)
 	struct PgDatabase *db = server->pool->db;
 	struct sockaddr_in sa_in;
 
+	server->dns_token = NULL;
+
 	if (!sa) {
 		disconnect_server(server, true, "server dns lookup failed");
 		return;
@@ -889,9 +896,12 @@ static void dns_connect(struct PgSocket *server)
 		sa = (struct sockaddr *)&sa_in;
 		sa_len = sizeof(sa_in);
 	} else {
+		struct DNSToken *tk;
 		slog_noise(server, "dns socket: %s", db->host);
 		/* launch dns lookup */
-		adns_resolve(adns, db->host, dns_callback, server);
+		tk = adns_resolve(adns, db->host, dns_callback, server);
+		if (tk)
+			server->dns_token = tk;
 		return;
 	}