From c0cbfd2d23384f97a0f146090544c5c8bad516ed Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 25 Mar 2019 15:12:34 -0700
Subject: [PATCH] ircd::net: Add util to detect usable ipv6 interface.

---
 include/ircd/net/addrs.h |  2 ++
 ircd/net.cc              | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/ircd/net/addrs.h b/include/ircd/net/addrs.h
index a5066f43a..6913a43fe 100644
--- a/include/ircd/net/addrs.h
+++ b/include/ircd/net/addrs.h
@@ -24,6 +24,8 @@ namespace ircd::net::addrs
 
 	bool for_each(const raw_closure &);
 	bool for_each(const closure &);
+
+	bool has_usable_ipv6_interface();
 }
 
 struct ircd::net::addrs::addr
diff --git a/ircd/net.cc b/ircd/net.cc
index 94b50ecbd..133645f96 100644
--- a/ircd/net.cc
+++ b/ircd/net.cc
@@ -690,6 +690,28 @@ ircd::net::open(socket &socket,
 // net/addrs.h
 //
 
+bool
+ircd::net::addrs::has_usable_ipv6_interface()
+{
+	return !for_each([](const addr &a)
+	{
+		if(a.family != AF_INET6)
+			return true;
+
+		if(a.scope_id != 0) // global scope
+			return true;
+
+		if(~a.flags & IFF_UP) // not up
+			return true;
+
+		if(a.flags & IFF_LOOPBACK) // not usable
+			return true;
+
+		// return false to break
+		return false;
+	});
+}
+
 bool
 ircd::net::addrs::for_each(const closure &closure)
 {