From 38537339ab4e5959dbaf9f85af35d798a149bddc Mon Sep 17 00:00:00 2001
From: Ariadne Conill <ariadne@dereferenced.org>
Date: Fri, 24 Jul 2020 03:42:34 -0600
Subject: [PATCH] lifecycle: implement requires keyword

---
 cmd/ifupdown.c          |  8 +++---
 libifupdown/interface.h |  2 ++
 libifupdown/lifecycle.c | 64 +++++++++++++++++++++++++++++++++++++++--
 libifupdown/lifecycle.h |  2 +-
 4 files changed, 68 insertions(+), 8 deletions(-)

diff --git a/cmd/ifupdown.c b/cmd/ifupdown.c
index 24bd70b..e9de1b7 100644
--- a/cmd/ifupdown.c
+++ b/cmd/ifupdown.c
@@ -60,7 +60,7 @@ is_ifdown()
 }
 
 bool
-change_interface(struct lif_interface *iface, struct lif_dict *state, const char *ifname)
+change_interface(struct lif_interface *iface, struct lif_dict *collection, struct lif_dict *state, const char *ifname)
 {
 	if (exec_opts.verbose)
 	{
@@ -68,7 +68,7 @@ change_interface(struct lif_interface *iface, struct lif_dict *state, const char
 			argv0, ifname, up ? "up" : "down");
 	}
 
-	if (!lif_lifecycle_run(&exec_opts, iface, state, ifname, up))
+	if (!lif_lifecycle_run(&exec_opts, iface, collection, state, ifname, up))
 	{
 		fprintf(stderr, "%s: failed to change interface %s state to '%s'\n",
 			argv0, ifname, up ? "up" : "down");
@@ -99,7 +99,7 @@ change_auto_interfaces(struct lif_dict *collection, struct lif_dict *state, stru
 		    fnmatch(opts->include_pattern, iface->ifname, 0))
 			continue;
 
-		if (!change_interface(iface, state, iface->ifname))
+		if (!change_interface(iface, collection, state, iface->ifname))
 			return false;
 	}
 
@@ -220,7 +220,7 @@ ifupdown_main(int argc, char *argv[])
 			iface = entry->data;
 		}
 
-		if (!change_interface(iface, &state, ifname))
+		if (!change_interface(iface, &collection, &state, ifname))
 			return EXIT_FAILURE;
 	}
 
diff --git a/libifupdown/interface.h b/libifupdown/interface.h
index 37c6151..6d811c8 100644
--- a/libifupdown/interface.h
+++ b/libifupdown/interface.h
@@ -52,6 +52,8 @@ struct lif_interface {
 	bool is_auto;
 
 	struct lif_dict vars;
+
+	bool is_up;
 };
 
 #define LIF_INTERFACE_COLLECTION_FOREACH(iter, collection) \
diff --git a/libifupdown/lifecycle.c b/libifupdown/lifecycle.c
index 8892fc3..b25e0d3 100644
--- a/libifupdown/lifecycle.c
+++ b/libifupdown/lifecycle.c
@@ -264,16 +264,66 @@ on_error:
 	return false;
 }
 
+static char *
+next_token(char **buf)
+{
+	char *out = *buf;
+
+	while (*out && isspace(*out))
+		out++;
+
+	char *end = out;
+	while (*end && !isspace(*end))
+		end++;
+
+	*end++ = '\0';
+	*buf = end;
+
+	return out;
+}
+
+static bool
+handle_dependents(const struct lif_execute_opts *opts, struct lif_interface *parent, struct lif_dict *collection, struct lif_dict *state, bool up)
+{
+	struct lif_dict_entry *requires = lif_dict_find(&parent->vars, "requires");
+
+	/* no dependents, nothing to worry about */
+	if (requires == NULL)
+		return true;
+
+	char require_ifs[4096];
+	strlcpy(require_ifs, requires->data, sizeof require_ifs);
+	char *bufp = require_ifs;
+
+	for (char *tokenp = next_token(&bufp); *tokenp; tokenp = next_token(&bufp))
+	{
+		fprintf(stderr, "next iface: %s\n", tokenp);
+
+		struct lif_interface *iface = lif_interface_collection_find(collection, tokenp);
+
+		/* already up or down, skip */
+		if (up == iface->is_up)
+			continue;
+
+		if (!lif_lifecycle_run(opts, iface, collection, state, iface->ifname, up))
+			return false;
+	}
+
+	return true;
+}
+
 bool
-lif_lifecycle_run(const struct lif_execute_opts *opts, struct lif_interface *iface, struct lif_dict *state, const char *lifname, bool up)
+lif_lifecycle_run(const struct lif_execute_opts *opts, struct lif_interface *iface, struct lif_dict *collection, struct lif_dict *state, const char *lifname, bool up)
 {
 	if (lifname == NULL)
 		lifname = iface->ifname;
 
-	/* XXX: actually handle dependents here */
-
 	if (up)
 	{
+		/* when going up, dependents go up first. */
+		if (!handle_dependents(opts, iface, collection, state, up))
+			return false;
+
 		/* XXX: we should try to recover (take the iface down) if bringing it up fails.
 		 * but, right now neither debian ifupdown or busybox ifupdown do any recovery,
 		 * so we wont right now.
@@ -288,6 +338,8 @@ lif_lifecycle_run(const struct lif_execute_opts *opts, struct lif_interface *ifa
 			return false;
 
 		lif_state_upsert(state, lifname, iface);
+
+		iface->is_up = true;
 	}
 	else
 	{
@@ -300,7 +352,13 @@ lif_lifecycle_run(const struct lif_execute_opts *opts, struct lif_interface *ifa
 		if (!lif_lifecycle_run_phase(opts, iface, "post-down", lifname, up))
 			return false;
 
+		/* when going up, dependents go down last. */
+		if (!handle_dependents(opts, iface, collection, state, up))
+			return false;
+
 		lif_state_delete(state, lifname);
+
+		iface->is_up = false;
 	}
 
 	return true;
diff --git a/libifupdown/lifecycle.h b/libifupdown/lifecycle.h
index fd4cb3a..e5b0adc 100644
--- a/libifupdown/lifecycle.h
+++ b/libifupdown/lifecycle.h
@@ -20,7 +20,7 @@
 #include "libifupdown/execute.h"
 
 extern bool lif_lifecycle_run_phase(const struct lif_execute_opts *opts, struct lif_interface *iface, const char *phase, const char *lifname, bool up);
-extern bool lif_lifecycle_run(const struct lif_execute_opts *opts, struct lif_interface *iface, struct lif_dict *state, const char *lifname, bool up);
+extern bool lif_lifecycle_run(const struct lif_execute_opts *opts, struct lif_interface *iface, struct lif_dict *collection, struct lif_dict *state, const char *lifname, bool up);
 
 #endif