bluetooth: ofono: Use Acquire method if available

Attempt to use Acquire method if available since it directly returns
the fd in the reply or an error if that the connection could not be
created while Connect offer neither of these and depend on
NewConnection to deliver the fd.

src/modules/bluetooth/backend-ofono.c

@@ -67,7 +67,7 @@ struct hf_audio_card {
 
     bool connecting;
     int fd;
-    uint8_t codec;
+    int (*acquire)(struct hf_audio_card *card);
 
     pa_bluetooth_transport *transport;
 };
@@ -99,12 +99,95 @@ static pa_dbus_pending* hf_dbus_send_and_add_to_pending(pa_bluetooth_backend *ba
     return p;
 }
 
+static DBusMessage *card_send(struct hf_audio_card *card, const char *method, DBusError *err)
+{
+    pa_bluetooth_transport *t = card->transport;
+    DBusMessage *m, *r;
+
+    pa_assert_se(m = dbus_message_new_method_call(t->owner, t->path, "org.ofono.HandsfreeAudioCard", method));
+    r = dbus_connection_send_with_reply_and_block(pa_dbus_connection_get(card->backend->connection), m, -1, err);
+    dbus_message_unref(m);
+
+    return r;
+}
+
+static int card_connect(struct hf_audio_card *card) {
+    DBusMessage *r;
+    DBusError err;
+
+    if (card->connecting)
+        return -EAGAIN;
+
+    card->connecting = true;
+
+    dbus_error_init(&err);
+    r = card_send(card, "Connect", &err);
+
+    if (!r) {
+        pa_log_error("Failed to connect %s: %s", err.name, err.message);
+        card->connecting = false;
+        dbus_error_free(&err);
+        return -1;
+    }
+
+    dbus_message_unref(r);
+
+    if (card->connecting)
+        return -EAGAIN;
+
+    return 0;
+}
+
+static int card_acquire(struct hf_audio_card *card) {
+    int fd;
+    uint8_t codec;
+    DBusMessage *r;
+    DBusError err;
+
+    /* Try acquiring the stream first which was introduced in 1.21 */
+    dbus_error_init(&err);
+    r = card_send(card, "Acquire", &err);
+
+    if (!r) {
+        if (!pa_streq(err.name, DBUS_ERROR_UNKNOWN_METHOD)) {
+            pa_log_error("Failed to acquire %s: %s", err.name, err.message);
+            dbus_error_free(&err);
+            return -1;
+        }
+        dbus_error_free(&err);
+        /* Fallback to Connect as this might be an old version of ofono */
+        card->acquire = card_connect;
+        return card_connect(card);
+    }
+
+    if ((dbus_message_get_args(r, NULL, DBUS_TYPE_UNIX_FD, &fd,
+                                      DBUS_TYPE_BYTE, &codec,
+                                      DBUS_TYPE_INVALID) == true)) {
+        dbus_message_unref(r);
+        if (codec != HFP_AUDIO_CODEC_CVSD) {
+            pa_log_error("Invalid codec: %u", codec);
+            /* shutdown to make sure connection is dropped immediately */
+            shutdown(fd, SHUT_RDWR);
+            close(fd);
+            return -1;
+        }
+        card->transport->codec = codec;
+        card->fd = fd;
+        return 0;
+    }
+
+    pa_log_error("Unable to acquire");
+    dbus_message_unref(r);
+    return -1;
+}
+
 static struct hf_audio_card *hf_audio_card_new(pa_bluetooth_backend *backend, const char *path) {
     struct hf_audio_card *card = pa_xnew0(struct hf_audio_card, 1);
 
     card->path = pa_xstrdup(path);
     card->backend = backend;
     card->fd = -1;
+    card->acquire = card_acquire;
 
     return card;
 }
@@ -157,28 +240,9 @@ static int hf_audio_agent_transport_acquire(pa_bluetooth_transport *t, bool opti
     pa_assert(card);
 
     if (!optional && card->fd < 0) {
-        DBusMessage *m, *r;
+        err = card->acquire(card);
-        DBusError derr;
+        if (err < 0)
-
+            return err;
-        if (card->connecting)
-            return -EAGAIN;
-
-        card->connecting = true;
-
-        dbus_error_init(&derr);
-        pa_assert_se(m = dbus_message_new_method_call(t->owner, t->path, "org.ofono.HandsfreeAudioCard", "Connect"));
-        r = dbus_connection_send_with_reply_and_block(pa_dbus_connection_get(card->backend->connection), m, -1, &derr);
-        dbus_message_unref(m);
-        m = NULL;
-
-        if (!r)
-            return -1;
-
-        dbus_message_unref(r);
-        r = NULL;
-
-        if (card->connecting)
-            return -EAGAIN;
     }
 
     /* The correct block size should take into account the SCO MTU from
@@ -191,8 +255,6 @@ static int hf_audio_agent_transport_acquire(pa_bluetooth_transport *t, bool opti
     if (omtu)
         *omtu = 48;
 
-    t->codec = card->codec;
-
     err = socket_accept(card->fd);
     if (err < 0) {
         pa_log_error("Deferred setup failed on fd %d: %s", card->fd, pa_cstrerror(-err));