Use LAN name from Avahi instead of assuming it's the D-Bus machine id.
This way p2p works as intended with any LAN name and also works if
it's changed on the fly via D-Bus using e.g. the gdbus command like
this:
# gdbus call --system --dest org.freedesktop.Avahi --object-path / \
--method org.freedesktop.Avahi.Server.SetHostName some-new-lan-name
Notably, this change allows us to delete all the code dealing with
obtaining the D-Bus machine-id.
BUG=chromium:245758
TEST=Unit tests pass + Changed LAN name (via the gdbus command) while
avahi-daemon and p2p-server was running and checked (via the
p2p-client command) that other devices could still see files
exported by the devices, under the new name.
Change-Id: Idb1d47ff5feadd0e51eb0be39e906aa3ad659952
Reviewed-on: https://chromium-review.googlesource.com/171480
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
Tested-by: David Zeuthen <zeuthen@chromium.org>
diff --git a/client/service_finder.cc b/client/service_finder.cc
index 5f4b9ff..f88ba0c 100644
--- a/client/service_finder.cc
+++ b/client/service_finder.cc
@@ -287,9 +287,7 @@
}
bool ServiceFinderAvahi::IsOwnService(const char *name) {
- // Here we rely on the implementation detail that the DNS-SD name
- // used is the D-Bus machine-id.
- return g_strcmp0(name, p2p::util::GetDBusMachineId()) == 0;
+ return g_strcmp0(name, avahi_client_get_host_name(client_)) == 0;
}
static string ToString(AvahiBrowserEvent event) {
diff --git a/common/util.cc b/common/util.cc
index fef9293..e338f09 100644
--- a/common/util.cc
+++ b/common/util.cc
@@ -66,52 +66,6 @@
logging::SetLogMessageHandler(SyslogFunc);
}
-// The encoding of the D-Bus machine-id plus a NUL terminator is 33
-// bytes. See http://dbus.freedesktop.org/doc/dbus-specification.html
-const size_t kDBusMachineIdPlusNulSize = 33;
-
-// Reads the D-Bus machine-id into |buf| and ensures that it's
-// NUL-terminated. It is a programming error to pass a |buf|
-// that is not at least |kDBusMachineIdPlusNulSize| bytes long.
-static void ReadMachineId(char *buf) {
- size_t num_read = 0;
- FILE* f = NULL;
-
- // NUL-terminate ahead of time.
- buf[kDBusMachineIdPlusNulSize - 1] = '\0';
-
- f = fopen("/var/lib/dbus/machine-id", "r");
- if (f == NULL) {
- LOG(ERROR) << "Error opening /var/lib/dbus/machine-id: " << strerror(errno);
- return;
- }
-
- // The machine-id file may include a newline so only request 32 bytes.
- num_read = fread(buf, 1, kDBusMachineIdPlusNulSize - 1, f);
- if (num_read != kDBusMachineIdPlusNulSize - 1) {
- LOG(ERROR) << "Error reading from /var/lib/dbus/machine-id, num_read="
- << num_read;
- fclose(f);
- return;
- }
-
- VLOG(1) << "Read machine-id " << buf;
-
- fclose(f);
-}
-
-const char* GetDBusMachineId() {
- static char machine_id[kDBusMachineIdPlusNulSize] = { 0 };
-
- if (machine_id[0] == '\0') {
- G_STATIC_ASSERT(sizeof machine_id == kDBusMachineIdPlusNulSize);
- ReadMachineId(machine_id);
- }
-
- return const_cast<const char *>(machine_id);
-}
-
-
bool IsXAttrSupported(const base::FilePath& dir_path) {
char *path = strdup(dir_path.Append("xattr_test_XXXXXX").value().c_str());
diff --git a/common/util.h b/common/util.h
index 30973ac..e95a9fa 100644
--- a/common/util.h
+++ b/common/util.h
@@ -17,12 +17,6 @@
// |program_name| and, if |include_pid| is true, the process id.
void SetupSyslog(const char* program_name, bool include_pid);
-// Gets the D-Bus machine id.
-//
-// This is not thread safe and blocks the calling thread the first
-// time it is called.
-const char* GetDBusMachineId();
-
// Checks if xattr is supported in the directory specified by
// |dir_path| which must be writable. Returns true if the feature is
// supported, false if not or if an error occured.
diff --git a/server/service_publisher.cc b/server/service_publisher.cc
index a061f1e..17a9094 100644
--- a/server/service_publisher.cc
+++ b/server/service_publisher.cc
@@ -68,9 +68,9 @@
// The TCP port of the HTTP server.
uint16_t http_port_;
- // The D-Bus/systemd machine-id. This is used as the identifier
- // of the DNS-SD service being exported via mDNS.
- string machine_id_;
+ // The LAN name currently used by Avahi. This is used as the
+ // identifier of the DNS-SD service being exported via mDNS.
+ string lan_name_;
// Object used for integrating Avahi with the GLib mainloop.
AvahiGLibPoll* poll_;
@@ -179,7 +179,7 @@
AVAHI_IF_UNSPEC,
AVAHI_PROTO_UNSPEC,
(AvahiPublishFlags) 0,
- machine_id_.c_str(),
+ lan_name_.c_str(),
"_cros_p2p._tcp",
/* service type */
NULL, /* domain */
@@ -203,7 +203,7 @@
AVAHI_IF_UNSPEC,
AVAHI_PROTO_UNSPEC,
(AvahiPublishFlags) 0,
- machine_id_.c_str(),
+ lan_name_.c_str(),
"_cros_p2p._tcp",
/* service type */
NULL, /* domain */
@@ -226,7 +226,15 @@
VLOG(1) << "OnAvahiChanged, state=" << state;
if (state == AVAHI_CLIENT_S_RUNNING) {
- VLOG(1) << "Server running, publishing services";
+ // Free the existing group, if there is one. This can happen if
+ // e.g. the LAN name used by Avahi changes.
+ if (publisher->group_ != NULL) {
+ avahi_entry_group_free(publisher->group_);
+ publisher->group_ = NULL;
+ }
+ publisher->lan_name_ = string(avahi_client_get_host_name(client));
+ VLOG(1) << "Server running, publishing services using LAN name '"
+ << publisher->lan_name_ << "'";
publisher->Publish(false);
}
}
@@ -234,8 +242,6 @@
bool ServicePublisherAvahi::Init() {
int error;
- machine_id_ = p2p::util::GetDBusMachineId();
-
poll_ = avahi_glib_poll_new(NULL, G_PRIORITY_DEFAULT);
client_ = avahi_client_new(avahi_glib_poll_get(poll_),
(AvahiClientFlags) 0,
