From aa963100ba764676a96149d3475694b04302915a Mon Sep 17 00:00:00 2001
From: Reyk Floeter <contact@reykfloeter.com>
Date: Sun, 2 Jun 2019 02:41:36 +0200
Subject: [PATCH] Fall back to 169.254.169.254 if DHCP endpoint does not work
 (unbreak OpenStack)

---
 agent/cloudinit.c | 51 +++++++++++++++++++++++++++++++++++++----------
 agent/main.h      |  4 ++++
 agent/openstack.c | 14 ++-----------
 3 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/agent/cloudinit.c b/agent/cloudinit.c
index 807d784..aff28d6 100644
--- a/agent/cloudinit.c
+++ b/agent/cloudinit.c
@@ -31,31 +31,60 @@
 
 static int	 cloudinit_fetch(struct system_config *);
 
+int
+tryendpoint(struct system_config *sc,
+    int (fetch)(struct system_config *),
+    int (next)(struct system_config *))
+{
+	free(sc->sc_endpoint);
+	sc->sc_endpoint = NULL;
+
+	switch (sc->sc_dhcpendpoint) {
+	case 0:
+		sc->sc_dhcpendpoint = 1;
+		if (dhcp_getendpoint(sc) == -1)
+			return tryendpoint(sc, fetch, next);
+		break;
+	case 1:
+		sc->sc_dhcpendpoint = 2;
+		if ((sc->sc_endpoint = strdup(DEFAULT_ENDPOINT)) == NULL) {
+			log_warnx("failed to set defaults");
+			return (-1);
+		}
+		break;
+	default:
+		if (next == NULL)
+			return (-1);
+		sc->sc_dhcpendpoint = 0;
+		return (*next)(sc);
+	}
+
+	if ((*fetch)(sc) != 0)
+		return tryendpoint(sc, fetch, next);
+
+	return (0);
+}
+
 int
 ec2(struct system_config *sc)
 {
 	free(sc->sc_username);
-	if ((sc->sc_username = strdup("ec2-user")) == NULL ||
-	    (sc->sc_endpoint = strdup(DEFAULT_ENDPOINT)) == NULL) {
-		log_warnx("failed to set defaults");
+	if ((sc->sc_username = strdup("ec2-user")) == NULL) {
+		log_warnx("failed to set default user");
 		return (-1);
 	}
 
 	sc->sc_stack = "ec2";
-	return (cloudinit_fetch(sc));
+	sc->sc_dhcpendpoint = 1;
+	return tryendpoint(sc, cloudinit_fetch, NULL);
 }
 
 int
 cloudinit(struct system_config *sc)
 {
-	if ((dhcp_getendpoint(sc) == -1) &&
-	    (sc->sc_endpoint = strdup(DEFAULT_ENDPOINT)) == NULL) {
-		log_warnx("failed to set defaults");
-		return (-1);
-	}
-
 	sc->sc_stack = "cloudinit";
-	return (cloudinit_fetch(sc));
+	sc->sc_dhcpendpoint = 0;
+	return tryendpoint(sc, cloudinit_fetch, NULL);
 }
 
 static int
diff --git a/agent/main.h b/agent/main.h
index 29a59ec..3ae86f7 100644
--- a/agent/main.h
+++ b/agent/main.h
@@ -76,6 +76,7 @@ struct system_config {
 	char			*sc_pubkey;
 	char			*sc_userdata;
 	char			*sc_endpoint;
+	int			 sc_dhcpendpoint;
 	char			*sc_instance;
 	int			 sc_timeout;
 
@@ -123,6 +124,9 @@ int	 azure(struct system_config *);
 /* cloudinit.c */
 int	 ec2(struct system_config *);
 int	 cloudinit(struct system_config *);
+int	 tryendpoint(struct system_config *,
+	    int (fetch)(struct system_config *),
+	    int (next)(struct system_config *));
 
 /* opennebula.c */
 int	 opennebula(struct system_config *);
diff --git a/agent/openstack.c b/agent/openstack.c
index 9c84d34..c60acd1 100644
--- a/agent/openstack.c
+++ b/agent/openstack.c
@@ -31,21 +31,11 @@
 
 static int	 openstack_fetch(struct system_config *);
 
+
 int
 openstack(struct system_config *sc)
 {
-	if ((dhcp_getendpoint(sc) == -1) &&
-	    (sc->sc_endpoint = strdup(DEFAULT_ENDPOINT)) == NULL) {
-		log_warnx("failed to set defaults");
-		return (-1);
-	}
-
-	if (openstack_fetch(sc) != 0) {
-		free(sc->sc_endpoint);
-		return (cloudinit(sc));
-	}
-
-	return (0);
+	return tryendpoint(sc, openstack_fetch, cloudinit);
 }
 
 static int