lib/repo-finder: Add Avahi based OstreeRepoFinder implementation

This is a more complex implementation of OstreeRepoFinder which resolves
ref names to remote URIs by looking for refs advertised by peers on the
local network using DNS-SD records and mDNS (Avahi). The idea is to
allow OS and app updates to be propagated over local networks, without
the internet.

It requires an OSTree server and code to generate the DNS-SD adverts in
order to be fully functional — support for this will be added
separately.

Unit tests are included.

Includes fixes by Krzesimir Nowak <krzesimir@kinvolk.io>.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Closes: #924
Approved by: cgwalters

1 files changed, 228 insertions, 0 deletions

diff --git a/tests/test-repo-finder-avahi.c b/tests/test-repo-finder-avahi.c
new file mode 100644
index 00000000..b2fddf70
--- /dev/null
+++ b/tests/test-repo-finder-avahi.c
@@ -0,0 +1,228 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright © 2017 Endless Mobile, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Authors:
+ *  - Philip Withnall <withnall@endlessm.com>
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+#include <glib.h>
+#include <glib-object.h>
+#include <locale.h>
+#include <string.h>
+
+#include "ostree-autocleanups.h"
+#include "ostree-repo-finder.h"
+#include "ostree-repo-finder-avahi.h"
+#include "ostree-repo-finder-avahi-private.h"
+
+/* FIXME: Upstream this */
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (AvahiStringList, avahi_string_list_free)
+
+/* Test the object constructor works at a basic level. */
+static void
+test_repo_finder_avahi_init (void)
+{
+  g_autoptr(OstreeRepoFinderAvahi) finder = NULL;
+  g_autoptr(GMainContext) context = NULL;
+
+  /* Default main context. */
+  finder = ostree_repo_finder_avahi_new (NULL);
+  g_clear_object (&finder);
+
+  /* Explicit main context. */
+  context = g_main_context_new ();
+  finder = ostree_repo_finder_avahi_new (context);
+  g_clear_object (&finder);
+}
+
+/* Test parsing valid and invalid TXT records. */
+static void
+test_repo_finder_avahi_txt_records_parse (void)
+{
+  struct
+    {
+      const guint8 *txt;
+      gsize txt_len;
+      const gchar *expected_key;  /* (nullable) to indicate parse failure */
+      const guint8 *expected_value;  /* (nullable) to allow for valueless keys */
+      gsize expected_value_len;
+    }
+  vectors[] =
+    {
+      { (const guint8 *) "", 0, NULL, NULL, 0 },
+      { (const guint8 *) "\x00", 1, NULL, NULL, 0 },
+      { (const guint8 *) "\xff", 1, NULL, NULL, 0 },
+      { (const guint8 *) "k\x00", 2, NULL, NULL, 0 },
+      { (const guint8 *) "k\xff", 2, NULL, NULL, 0 },
+      { (const guint8 *) "=", 1, NULL, NULL, 0 },
+      { (const guint8 *) "=value", 6, NULL, NULL, 0 },
+      { (const guint8 *) "k=v", 3, "k", (const guint8 *) "v", 1 },
+      { (const guint8 *) "key=value", 9, "key", (const guint8 *) "value", 5 },
+      { (const guint8 *) "k=v=", 4, "k", (const guint8 *) "v=", 2 },
+      { (const guint8 *) "k=", 2, "k", (const guint8 *) "", 0 },
+      { (const guint8 *) "k", 1, "k", NULL, 0 },
+      { (const guint8 *) "k==", 3, "k", (const guint8 *) "=", 1 },
+      { (const guint8 *) "k=\x00\x01\x02", 5, "k", (const guint8 *) "\x00\x01\x02", 3 },
+    };
+  gsize i;
+
+  for (i = 0; i < G_N_ELEMENTS (vectors); i++)
+    {
+      g_autoptr(AvahiStringList) string_list = NULL;
+      g_autoptr(GHashTable) attributes = NULL;
+
+      g_test_message ("Vector %" G_GSIZE_FORMAT, i);
+
+      string_list = avahi_string_list_add_arbitrary (NULL, vectors[i].txt, vectors[i].txt_len);
+
+      attributes = _ostree_txt_records_parse (string_list);
+
+      if (vectors[i].expected_key != NULL)
+        {
+          GBytes *value;
+          g_autoptr(GBytes) expected_value = NULL;
+
+          g_assert_true (g_hash_table_lookup_extended (attributes,
+                                                       vectors[i].expected_key,
+                                                       NULL,
+                                                       (gpointer *) &value));
+          g_assert_cmpuint (g_hash_table_size (attributes), ==, 1);
+
+          if (vectors[i].expected_value != NULL)
+            {
+              g_assert_nonnull (value);
+              expected_value = g_bytes_new_static (vectors[i].expected_value, vectors[i].expected_value_len);
+              g_assert_true (g_bytes_equal (value, expected_value));
+            }
+          else
+            {
+              g_assert_null (value);
+            }
+        }
+      else
+        {
+          g_assert_cmpuint (g_hash_table_size (attributes), ==, 0);
+        }
+    }
+}
+
+/* Test that the first value for a set of duplicate records is returned.
+ * See RFC 6763, §6.4. */
+static void
+test_repo_finder_avahi_txt_records_duplicates (void)
+{
+  g_autoptr(AvahiStringList) string_list = NULL;
+  g_autoptr(GHashTable) attributes = NULL;
+  GBytes *value;
+  g_autoptr(GBytes) expected_value = NULL;
+
+  /* Reverse the list before using it, as they are built in reverse order.
+   * (See the #AvahiStringList documentation.) */
+  string_list = avahi_string_list_new ("k=value1", "k=value2", "k=value3", NULL);
+  string_list = avahi_string_list_reverse (string_list);
+  attributes = _ostree_txt_records_parse (string_list);
+
+  g_assert_cmpuint (g_hash_table_size (attributes), ==, 1);
+  value = g_hash_table_lookup (attributes, "k");
+  g_assert_nonnull (value);
+
+  expected_value = g_bytes_new_static ("value1", strlen ("value1"));
+  g_assert_true (g_bytes_equal (value, expected_value));
+}
+
+/* Test that keys are parsed and looked up case insensitively.
+ * See RFC 6763, §6.4. */
+static void
+test_repo_finder_avahi_txt_records_case_sensitivity (void)
+{
+  g_autoptr(AvahiStringList) string_list = NULL;
+  g_autoptr(GHashTable) attributes = NULL;
+  GBytes *value1, *value2;
+  g_autoptr(GBytes) expected_value1 = NULL, expected_value2 = NULL;
+
+  /* Reverse the list before using it, as they are built in reverse order.
+   * (See the #AvahiStringList documentation.) */
+  string_list = avahi_string_list_new ("k=value1",
+                                       "K=value2",
+                                       "KeY2=v",
+                                       NULL);
+  string_list = avahi_string_list_reverse (string_list);
+  attributes = _ostree_txt_records_parse (string_list);
+
+  g_assert_cmpuint (g_hash_table_size (attributes), ==, 2);
+
+  value1 = g_hash_table_lookup (attributes, "k");
+  g_assert_nonnull (value1);
+  expected_value1 = g_bytes_new_static ("value1", strlen ("value1"));
+  g_assert_true (g_bytes_equal (value1, expected_value1));
+
+  g_assert_null (g_hash_table_lookup (attributes, "K"));
+
+  value2 = g_hash_table_lookup (attributes, "key2");
+  g_assert_nonnull (value2);
+  expected_value2 = g_bytes_new_static ("v", 1);
+  g_assert_true (g_bytes_equal (value2, expected_value2));
+
+  g_assert_null (g_hash_table_lookup (attributes, "KeY2"));
+}
+
+/* Test that keys which have an empty value can be distinguished from those
+ * which have no value. See RFC 6763, §6.4. */
+static void
+test_repo_finder_avahi_txt_records_empty_and_missing (void)
+{
+  g_autoptr(AvahiStringList) string_list = NULL;
+  g_autoptr(GHashTable) attributes = NULL;
+  GBytes *value1, *value2;
+  g_autoptr(GBytes) expected_value1 = NULL;
+
+  string_list = avahi_string_list_new ("empty=",
+                                       "missing",
+                                       NULL);
+  attributes = _ostree_txt_records_parse (string_list);
+
+  g_assert_cmpuint (g_hash_table_size (attributes), ==, 2);
+
+  value1 = g_hash_table_lookup (attributes, "empty");
+  g_assert_nonnull (value1);
+  expected_value1 = g_bytes_new_static ("", 0);
+  g_assert_true (g_bytes_equal (value1, expected_value1));
+
+  g_assert_true (g_hash_table_lookup_extended (attributes, "missing", NULL, (gpointer *) &value2));
+  g_assert_null (value2);
+}
+
+int main (int argc, char **argv)
+{
+  setlocale (LC_ALL, "");
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/repo-finder-avahi/init", test_repo_finder_avahi_init);
+  g_test_add_func ("/repo-finder-avahi/txt-records/parse", test_repo_finder_avahi_txt_records_parse);
+  g_test_add_func ("/repo-finder-avahi/txt-records/duplicates", test_repo_finder_avahi_txt_records_duplicates);
+  g_test_add_func ("/repo-finder-avahi/txt-records/case-sensitivity", test_repo_finder_avahi_txt_records_case_sensitivity);
+  g_test_add_func ("/repo-finder-avahi/txt-records/empty-and-missing", test_repo_finder_avahi_txt_records_empty_and_missing);
+  /* FIXME: Add tests for service processing, probably by splitting the
+   * code in OstreeRepoFinderAvahi around found_services. */
+
+  return g_test_run();
+}