From 125dc9525b34089903ccd4402a2e9bf8c6c7f801 Mon Sep 17 00:00:00 2001
From: David Lamparter <equinox@diac24.net>
Date: Wed, 11 Dec 2019 12:27:05 +0100
Subject: [PATCH] lib/resolver: support/bypass IP literals

libc-ares doesn't do IP literals, so we have to do that before running
off to do DNS.  Since this isn't BMP specific, move to lib/ so NHRP can
benefit too.

Signed-off-by: David Lamparter <equinox@diac24.net>
---
 bgpd/bgp_bmp.c | 31 +++++++++++++------------------
 lib/resolver.c | 32 +++++++++++++++++++++++++++++++-
 lib/resolver.h |  4 ++++
 3 files changed, 48 insertions(+), 19 deletions(-)

diff --git a/bgpd/bgp_bmp.c b/bgpd/bgp_bmp.c
index b8862c6049..b376d51a1c 100644
--- a/bgpd/bgp_bmp.c
+++ b/bgpd/bgp_bmp.c
@@ -1669,27 +1669,22 @@ static void bmp_active_resolved(struct resolver_query *resq, int numaddrs,
 	unsigned i;
 
 	if (numaddrs <= 0) {
-		int ret;
-
-		ba->addrpos = 0;
-		ba->addrtotal = 1;
-		ret = str2sockunion(ba->hostname, &ba->addrs[0]);
-		if (ret < 0) {
-			ba->addrtotal = 0;
-			ba->curretry += ba->curretry / 2;
-			bmp_active_setup(ba);
-			return;
-		}
-	} else {
-		if (numaddrs > (int)array_size(ba->addrs))
-			numaddrs = array_size(ba->addrs);
-
+		zlog_warn("bmp[%s]: hostname resolution failed", ba->hostname);
+		ba->curretry += ba->curretry / 2;
 		ba->addrpos = 0;
-		ba->addrtotal = numaddrs;
-		for (i = 0; i < ba->addrtotal; i++)
-			memcpy(&ba->addrs[i], &addr[i], sizeof(ba->addrs[0]));
+		ba->addrtotal = 0;
+		bmp_active_setup(ba);
+		return;
 	}
 
+	if (numaddrs > (int)array_size(ba->addrs))
+		numaddrs = array_size(ba->addrs);
+
+	ba->addrpos = 0;
+	ba->addrtotal = numaddrs;
+	for (i = 0; i < ba->addrtotal; i++)
+		memcpy(&ba->addrs[i], &addr[i], sizeof(ba->addrs[0]));
+
 	bmp_active_connect(ba);
 }
 
diff --git a/lib/resolver.c b/lib/resolver.c
index fb8aeed92f..938ebd4143 100644
--- a/lib/resolver.c
+++ b/lib/resolver.c
@@ -180,11 +180,25 @@ static void ares_address_cb(void *arg, int status, int timeouts,
 	callback(query, i, &addr[0]);
 }
 
+static int resolver_cb_literal(struct thread *t)
+{
+	struct resolver_query *query = THREAD_ARG(t);
+	void (*callback)(struct resolver_query *, int, union sockunion *);
+
+	callback = query->callback;
+	query->callback = NULL;
+
+	callback(query, 1, &query->literal_addr);
+	return 0;
+}
+
 void resolver_resolve(struct resolver_query *query, int af,
 		      const char *hostname,
 		      void (*callback)(struct resolver_query *, int,
 				       union sockunion *))
 {
+	int ret;
+
 	if (query->callback != NULL) {
 		flog_err(
 			EC_LIB_RESOLVER,
@@ -193,10 +207,26 @@ void resolver_resolve(struct resolver_query *query, int af,
 		return;
 	}
 
+	query->callback = callback;
+	query->literal_cb = NULL;
+
+	ret = str2sockunion(hostname, &query->literal_addr);
+	if (ret == 0) {
+		if (resolver_debug)
+			zlog_debug("[%p] Resolving '%s' (IP literal)",
+				   query, hostname);
+
+		/* for consistency with proper name lookup, don't call the
+		 * callback immediately; defer to thread loop
+		 */
+		thread_add_timer_msec(state.master, resolver_cb_literal,
+				      query, 0, &query->literal_cb);
+		return;
+	}
+
 	if (resolver_debug)
 		zlog_debug("[%p] Resolving '%s'", query, hostname);
 
-	query->callback = callback;
 	ares_gethostbyname(state.channel, hostname, af, ares_address_cb, query);
 	resolver_update_timeouts(&state);
 }
diff --git a/lib/resolver.h b/lib/resolver.h
index bc6326edaa..a418377a29 100644
--- a/lib/resolver.h
+++ b/lib/resolver.h
@@ -15,6 +15,10 @@
 
 struct resolver_query {
 	void (*callback)(struct resolver_query *, int n, union sockunion *);
+
+	/* used to immediate provide the result if IP literal is passed in */
+	union sockunion literal_addr;
+	struct thread *literal_cb;
 };
 
 void resolver_init(struct thread_master *tm);
-- 
2.39.5