From 294ac097d65f34251754ead4ed720b7b3a9ad4c3 Mon Sep 17 00:00:00 2001
From: Martin Willi <martin@strongswan.org>
Date: Thu, 19 May 2016 11:13:24 +0200
Subject: [PATCH] af-alg: Silently skip probing algorithms if AF_ALG is not
 supported

If the af-alg plugin is enabled, but kernel support is missing, we get
an error line during startup for each probed algorithm. This is way too
verbose, so just skip probing if AF_ALG is unsupported.
---
 .../plugins/af_alg/af_alg_plugin.c            | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/libstrongswan/plugins/af_alg/af_alg_plugin.c b/src/libstrongswan/plugins/af_alg/af_alg_plugin.c
index 445667507..571882cec 100644
--- a/src/libstrongswan/plugins/af_alg/af_alg_plugin.c
+++ b/src/libstrongswan/plugins/af_alg/af_alg_plugin.c
@@ -22,6 +22,8 @@
 #include "af_alg_prf.h"
 #include "af_alg_crypter.h"
 
+#include <unistd.h>
+
 typedef struct private_af_alg_plugin_t private_af_alg_plugin_t;
 
 /**
@@ -41,6 +43,19 @@ METHOD(plugin_t, get_name, char*,
 	return "af-alg";
 }
 
+static bool af_alg_supported()
+{
+	int fd;
+
+	fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
+	if (fd != -1)
+	{
+		close(fd);
+		return true;
+	}
+	return false;
+}
+
 METHOD(plugin_t, get_features, int,
 	private_af_alg_plugin_t *this, plugin_feature_t *features[])
 {
@@ -50,6 +65,10 @@ METHOD(plugin_t, get_features, int,
 
 	if (!count)
 	{	/* initialize only once */
+		if (!af_alg_supported())
+		{
+			return 0;
+		}
 		f[count++] = PLUGIN_REGISTER(HASHER, af_alg_hasher_create);
 		af_alg_hasher_probe(f, &count);
 		f[count++] = PLUGIN_REGISTER(SIGNER, af_alg_signer_create);