libostree: Add Avahi-file 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.

This commit is unpolished and not ready to be merged. It is intended as
a strawman for feedback.

Unit tests are included.

Signed-off-by: Philip Withnall <[email protected]>

Makefile-libostree.am

@@ -156,6 +156,13 @@ libostree_1_la_SOURCES += \
 	src/libostree/ostree-tls-cert-interaction.h \
 	$(NULL)
 endif
+if USE_AVAHI
+libostree_1_la_SOURCES += \
+	src/libostree/ostree-repo-finder-avahi.c \
+	src/libostree/ostree-repo-finder-avahi.h \
+	src/libostree/ostree-repo-finder-avahi-private.h \
+	$(NULL)
+endif
 
 libostree_1_la_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/bsdiff -I$(srcdir)/libglnx -I$(srcdir)/src/libotutil -I$(srcdir)/src/libostree -I$(builddir)/src/libostree \
 	$(OT_INTERNAL_GIO_UNIX_CFLAGS) $(OT_INTERNAL_GPGME_CFLAGS) $(OT_DEP_LZMA_CFLAGS) $(OT_DEP_ZLIB_CFLAGS) $(OT_DEP_OPENSSL_CFLAGS) \
@@ -173,6 +180,11 @@ libostree_1_la_CFLAGS += $(OT_DEP_LIBARCHIVE_CFLAGS)
 libostree_1_la_LIBADD += $(OT_DEP_LIBARCHIVE_LIBS)
 endif
 
+if USE_AVAHI
+libostree_1_la_CFLAGS += $(OT_DEP_AVAHI_CFLAGS)
+libostree_1_la_LIBADD += $(OT_DEP_AVAHI_LIBS)
+endif
+
 if BUILDOPT_LIBSYSTEMD
 libostree_1_la_CFLAGS += $(LIBSYSTEMD_CFLAGS)
 libostree_1_la_LIBADD += $(LIBSYSTEMD_LIBS)

Makefile-tests.am

@@ -186,6 +186,10 @@ test_programs = tests/test-varint tests/test-ot-unix-utils tests/test-bsdiff tes
 	tests/test-basic-c tests/test-sysroot-c tests/test-pull-c tests/test-bloom \
 	tests/test-repo-finder-config tests/test-repo-finder-mount
 
+if USE_AVAHI
+test_programs += tests/test-repo-finder-avahi
+endif
+
 # An interactive tool
 noinst_PROGRAMS += tests/test-rollsum-cli
 
@@ -216,6 +220,12 @@ tests_test_bloom_SOURCES = src/libostree/ostree-bloom.c tests/test-bloom.c
 tests_test_bloom_CFLAGS = $(TESTS_CFLAGS)
 tests_test_bloom_LDADD = $(TESTS_LDADD)
 
+if USE_AVAHI
+tests_test_repo_finder_avahi_SOURCES = src/libostree/ostree-bloom.c src/libostree/ostree-repo-finder-avahi.c tests/test-repo-finder-avahi.c
+tests_test_repo_finder_avahi_CFLAGS = $(TESTS_CFLAGS) $(OT_INTERNAL_SOUP_CFLAGS)
+tests_test_repo_finder_avahi_LDADD = $(TESTS_LDADD) $(OT_INTERNAL_SOUP_LIBS)
+endif
+
 tests_test_repo_finder_config_SOURCES = tests/test-repo-finder-config.c
 tests_test_repo_finder_config_CFLAGS = $(TESTS_CFLAGS)
 tests_test_repo_finder_config_LDADD = $(TESTS_LDADD)

apidoc/ostree-sections.txt

@@ -468,6 +468,16 @@ ostree_repo_finder_result_compare
 ostree_repo_finder_get_type
 </SECTION>
 
+<SECTION>
+<FILE>ostree-repo-finder-avahi</FILE>
+OstreeRepoFinderAvahi
+ostree_repo_finder_avahi_new
+ostree_repo_finder_avahi_start
+ostree_repo_finder_avahi_stop
+<SUBSECTION Standard>
+ostree_repo_finder_avahi_get_type
+</SECTION>
+
 <SECTION>
 <FILE>ostree-repo-finder-config</FILE>
 OstreeRepoFinderConfig

configure.ac

@@ -316,6 +316,31 @@ if test x$with_openssl != xno; then OSTREE_FEATURES="$OSTREE_FEATURES openssl";
 AM_CONDITIONAL(USE_OPENSSL, test $with_openssl != no)
 dnl end openssl
 
+dnl Avahi dependency for finding repos
+AVAHI_DEPENDENCY="avahi-client >= 0.6.31 avahi-glib >= 0.6.31"
+
+AC_ARG_WITH(avahi,
+            AS_HELP_STRING([--without-avahi], [Do not use Avahi]),
+            :, with_avahi=maybe)
+
+AS_IF([ test x$with_avahi != xno ], [
+    AC_MSG_CHECKING([for $AVAHI_DEPENDENCY])
+    PKG_CHECK_EXISTS($AVAHI_DEPENDENCY, have_avahi=yes, have_avahi=no)
+    AC_MSG_RESULT([$have_avahi])
+    AS_IF([ test x$have_avahi = xno && test x$with_avahi != xmaybe ], [
+       AC_MSG_ERROR([Avahi is enabled but could not be found])
+    ])
+    AS_IF([ test x$have_avahi = xyes], [
+        AC_DEFINE([HAVE_AVAHI], 1, [Define if we have avahi-client.pc and avahi-glib.pc])
+        PKG_CHECK_MODULES(OT_DEP_AVAHI, $AVAHI_DEPENDENCY)
+        with_avahi=yes
+    ], [
+        with_avahi=no
+    ])
+], [ with_avahi=no ])
+if test x$with_avahi != xno; then OSTREE_FEATURES="$OSTREE_FEATURES avahi"; fi
+AM_CONDITIONAL(USE_AVAHI, test $with_avahi != no)
+
 dnl This is what is in RHEL7.2 right now, picking it arbitrarily
 LIBMOUNT_DEPENDENCY="mount >= 2.23.0"
 

src/libostree/libostree.sym

@@ -405,6 +405,11 @@ global:
   ostree_remote_unref;
   ostree_repo_find_remotes_async;
   ostree_repo_find_remotes_finish;
+  /* TODO: What if we compile without Avahi? */
+  ostree_repo_finder_avahi_get_type;
+  ostree_repo_finder_avahi_new;
+  ostree_repo_finder_avahi_start;
+  ostree_repo_finder_avahi_stop;
   ostree_repo_finder_config_get_type;
   ostree_repo_finder_config_new;
   ostree_repo_finder_get_type;

src/libostree/ostree-repo-finder-avahi-private.h

@@ -0,0 +1,39 @@
+/* -*- 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 <[email protected]>
+ */
+
+#pragma once
+
+#include <avahi-common/strlst.h>
+#include <gio/gio.h>
+#include <glib.h>
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+GHashTable *_ostree_txt_records_parse (AvahiStringList *txt);
+
+GVariant *_ostree_txt_records_lookup_variant (GHashTable         *attributes,
+                                              const gchar        *key,
+                                              const GVariantType *value_type);
+
+G_END_DECLS