Select A2DP codec configuration with CLI tool

configure.ac

@@ -85,7 +85,7 @@ PKG_CHECK_MODULES([ALSA], [alsa])
 PKG_CHECK_MODULES([BLUEZ], [bluez >= 5.0])
 PKG_CHECK_MODULES([DBUS1], [dbus-1 >= 1.6])
 PKG_CHECK_MODULES([GIO2], [gio-unix-2.0])
-PKG_CHECK_MODULES([GLIB2], [glib-2.0 >= 2.30])
+PKG_CHECK_MODULES([GLIB2], [glib-2.0 >= 2.32])
 PKG_CHECK_MODULES([SBC], [sbc >= 1.2])
 
 PKG_CHECK_MODULES([LIBBSD], [libbsd >= 0.8],

doc/bluealsa-cli.1.rst

@@ -6,7 +6,7 @@ bluealsa-cli
 a simple command line interface for the BlueALSA D-Bus API
 ----------------------------------------------------------
 
-:Date: February 2021
+:Date: July 2021
 :Manual section: 1
 :Manual group: General Commands Manual
 :Version: $VERSION$
@@ -61,13 +61,18 @@ info *PCM_PATH*
 
     The list of available codecs requires BlueZ SEP support (BlueZ >= 5.52)
 
-codec *PCM_PATH* [*CODEC*]
+codec *PCM_PATH* [*CODEC*] [*CONFIG*]
     If *CODEC* is given, change the codec to be used by the given PCM. This
     command will terminate the PCM if it is currently running.
 
     If *CODEC* is not given, print a list of additional codecs supported by the
     given PCM and the currently selected codec.
 
+    Optionally, for A2DP codecs, one can specify A2DP codec configuration which
+    should be selected. The *CONFIG* shall be given as a hexadecimal string. If
+    this parameter is omitted, BlueALSA will select default configuration based
+    on codec capabilities of connected Bluetooth device.
+
     Selecting a codec and listing available codecs requires BlueZ SEP support
     (BlueZ >= 5.52).
 

src/bluealsa-dbus.c

@@ -176,15 +176,8 @@ static bool ba_variant_populate_sep(GVariantBuilder *props, const struct a2dp_se
 	}
 
 	g_variant_builder_init(props, G_VARIANT_TYPE("a{sv}"));
-
-	GVariantBuilder vcaps;
-	g_variant_builder_init(&vcaps, G_VARIANT_TYPE("ay"));
-
-	size_t i;
-	for (i = 0; i < size; i++)
-		g_variant_builder_add(&vcaps, "y", caps[i]);
-
-	g_variant_builder_add(props, "{sv}", "Capabilities", g_variant_builder_end(&vcaps));
+	g_variant_builder_add(props, "{sv}", "Capabilities", g_variant_new_fixed_array(
+				G_VARIANT_TYPE_BYTE, caps, size, sizeof(uint8_t)));
 
 	switch (codec->codec_id) {
 	case A2DP_CODEC_SBC:
@@ -556,13 +549,13 @@ static void bluealsa_pcm_select_codec(GDBusMethodInvocation *inv) {
 	GVariantIter *properties;
 	GVariant *value = NULL;
 	const char *errmsg = NULL;
+	const char *codec_name;
 	const char *property;
-	const char *codec;
 
-	void *a2dp_configuration = NULL;
+	a2dp_t a2dp_configuration = {};
 	size_t a2dp_configuration_size = 0;
 
-	g_variant_get(params, "(sa{sv})", &codec, &properties);
+	g_variant_get(params, "(sa{sv})", &codec_name, &properties);
 	while (g_variant_iter_next(properties, "{&sv}", &property, &value)) {
 
 		if (strcmp(property, "Configuration") == 0 &&
@@ -571,8 +564,13 @@ static void bluealsa_pcm_select_codec(GDBusMethodInvocation *inv) {
 			const void *data = g_variant_get_fixed_array(value,
 					&a2dp_configuration_size, sizeof(char));
 
-			g_free(a2dp_configuration);
-			a2dp_configuration = g_memdup(data, a2dp_configuration_size);
+			if (a2dp_configuration_size > sizeof(a2dp_configuration)) {
+				warn("Configuration blob size exceeded: %zu > %zu",
+						a2dp_configuration_size, sizeof(a2dp_configuration));
+				a2dp_configuration_size = sizeof(a2dp_configuration);
+			}
+
+			memcpy(&a2dp_configuration, data, a2dp_configuration_size);
 
 		}
 
@@ -588,7 +586,7 @@ static void bluealsa_pcm_select_codec(GDBusMethodInvocation *inv) {
 			goto fail;
 		}
 
-		uint16_t codec_id = ba_transport_codecs_a2dp_from_string(codec);
+		uint16_t codec_id = ba_transport_codecs_a2dp_from_string(codec_name);
 		enum a2dp_dir dir = !t->a2dp.codec->dir;
 		const GArray *seps = t->d->seps;
 		struct a2dp_sep *sep = NULL;
@@ -619,13 +617,13 @@ static void bluealsa_pcm_select_codec(GDBusMethodInvocation *inv) {
 			goto fail;
 
 		/* use codec configuration blob provided by user */
-		if (a2dp_configuration != NULL) {
-			if (a2dp_check_configuration(codec, a2dp_configuration,
+		if (a2dp_configuration_size != 0) {
+			if (a2dp_check_configuration(codec, &a2dp_configuration,
 						a2dp_configuration_size) != A2DP_CHECK_OK) {
 				errmsg = "Invalid configuration blob";
 				goto fail;
 			}
-			memcpy(sep->configuration, a2dp_configuration, sep->capabilities_size);
+			memcpy(sep->configuration, &a2dp_configuration, sep->capabilities_size);
 		}
 
 		if (ba_transport_select_codec_a2dp(t, sep) == -1)
@@ -634,7 +632,7 @@ static void bluealsa_pcm_select_codec(GDBusMethodInvocation *inv) {
 	}
 	else {
 
-		uint16_t codec_id = ba_transport_codecs_hfp_from_string(codec);
+		uint16_t codec_id = ba_transport_codecs_hfp_from_string(codec_name);
 		if (ba_transport_select_codec_sco(t, codec_id) == -1)
 			goto fail;
 
@@ -646,13 +644,12 @@ static void bluealsa_pcm_select_codec(GDBusMethodInvocation *inv) {
 fail:
 	if (errmsg == NULL)
 		errmsg = strerror(errno);
-	error("Couldn't select codec: %s: %s", codec, errmsg);
+	error("Couldn't select codec: %s: %s", codec_name, errmsg);
 	g_dbus_method_invocation_return_error(inv, G_DBUS_ERROR,
 			G_DBUS_ERROR_FAILED, "%s", errmsg);
 
 final:
 	ba_transport_pcm_unref(pcm);
-	g_free(a2dp_configuration);
 	g_variant_iter_free(properties);
 	if (value != NULL)
 		g_variant_unref(value);

src/bluez.c

@@ -151,15 +151,9 @@ static void bluez_endpoint_select_configuration(GDBusMethodInvocation *inv) {
 	if (a2dp_select_configuration(codec, &capabilities, size) == -1)
 		goto fail;
 
-	GVariantBuilder caps;
-	size_t i;
-
-	g_variant_builder_init(&caps, G_VARIANT_TYPE("ay"));
-	for (i = 0; i < size; i++)
-		g_variant_builder_add(&caps, "y", ((char *)&capabilities)[i]);
-
-	g_dbus_method_invocation_return_value(inv, g_variant_new("(ay)", &caps));
-	g_variant_builder_clear(&caps);
+	GVariant *rv[] = {
+		g_variant_new_fixed_array(G_VARIANT_TYPE_BYTE, &capabilities, size, sizeof(uint8_t)) };
+	g_dbus_method_invocation_return_value(inv, g_variant_new_tuple(rv, 1));
 
 	return;
 
@@ -404,26 +398,20 @@ static int bluez_register_media_endpoint(
 	const struct a2dp_codec *codec = dbus_obj->codec;
 	GDBusMessage *msg = NULL, *rep = NULL;
 	int ret = 0;
-	size_t i;
 
 	debug("Registering media endpoint: %s", dbus_obj->path);
 
 	msg = g_dbus_message_new_method_call(BLUEZ_SERVICE, adapter->bluez_dbus_path,
 			BLUEZ_IFACE_MEDIA, "RegisterEndpoint");
 
-	GVariantBuilder caps;
 	GVariantBuilder properties;
-
-	g_variant_builder_init(&caps, G_VARIANT_TYPE("ay"));
 	g_variant_builder_init(&properties, G_VARIANT_TYPE("a{sv}"));
 
-	for (i = 0; i < codec->capabilities_size; i++)
-		g_variant_builder_add(&caps, "y", ((char *)&codec->capabilities)[i]);
-
 	g_variant_builder_add(&properties, "{sv}", "UUID", g_variant_new_string(uuid));
 	g_variant_builder_add(&properties, "{sv}", "DelayReporting", g_variant_new_boolean(TRUE));
 	g_variant_builder_add(&properties, "{sv}", "Codec", g_variant_new_byte(codec->codec_id));
-	g_variant_builder_add(&properties, "{sv}", "Capabilities", g_variant_builder_end(&caps));
+	g_variant_builder_add(&properties, "{sv}", "Capabilities", g_variant_new_fixed_array(
+				G_VARIANT_TYPE_BYTE, &codec->capabilities, codec->capabilities_size, sizeof(uint8_t)));
 
 	g_dbus_message_set_body(msg, g_variant_new("(oa{sv})", dbus_obj->path, &properties));
 	g_variant_builder_clear(&properties);
@@ -1273,16 +1261,10 @@ bool bluez_a2dp_set_configuration(
 		goto fail;
 	}
 
-	GVariantBuilder caps;
-	g_variant_builder_init(&caps, G_VARIANT_TYPE("ay"));
-
-	size_t i;
-	for (i = 0; i < sep->capabilities_size; i++)
-		g_variant_builder_add(&caps, "y", ((char *)sep->configuration)[i]);
-
 	GVariantBuilder props;
 	g_variant_builder_init(&props, G_VARIANT_TYPE("a{sv}"));
-	g_variant_builder_add(&props, "{sv}", "Capabilities", g_variant_builder_end(&caps));
+	g_variant_builder_add(&props, "{sv}", "Capabilities", g_variant_new_fixed_array(
+				G_VARIANT_TYPE_BYTE, sep->configuration, sep->capabilities_size, sizeof(uint8_t)));
 
 	msg = g_dbus_message_new_method_call(BLUEZ_SERVICE,
 			sep->bluez_dbus_path, BLUEZ_IFACE_MEDIA_ENDPOINT, "SetConfiguration");

src/shared/hex.c

@@ -0,0 +1,59 @@
+/*
+ * BlueALSA - hex.c
+ * Copyright (c) 2016-2021 Arkadiusz Bokowy
+ *
+ * This file is a part of bluez-alsa.
+ *
+ * This project is licensed under the terms of the MIT license.
+ *
+ */
+
+#include "shared/hex.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+static const int hextable[255] = {
+	['0'] = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+	['A'] = 10, 11, 12, 13, 14, 15,
+	['a'] = 10, 11, 12, 13, 14, 15,
+};
+
+/**
+ * Encode a binary data into a hex string.
+ *
+ * @param bin A buffer with binary data.
+ * @param hex A buffer where null-terminated hexadecimal string will be
+ *   stored. This buffer has to be big enough to store n*2 + 1 bytes of
+ *   data.
+ * @param n The length of the binary buffer which shall be encoded.
+ * @return This function returns length of the hex string. */
+ssize_t bin2hex(const void *bin, char *hex, size_t n) {
+	for (size_t i = 0; i < n; i++)
+		sprintf(&hex[i * 2], "%.2x", ((unsigned char *)bin)[i]);
+	return n * 2;
+}
+
+/**
+ * Decode a hex string into a binary data.
+ *
+ * @param hex A buffer with hexadecimal string.
+ * @param bin A buffer where decoded data will be stored. This buffer has to
+ *   be big enough to store n/2 bytes of data.
+ * @param n The length of the string which shall be decoded.
+ * @return On success this function returns the size of the binary data. If
+ *   an error has occurred, -1 is returned and errno is set to indicate the
+ *   error. */
+ssize_t hex2bin(const char *hex, void *bin, size_t n) {
+
+	if (n % 2 != 0)
+		return errno = EINVAL, -1;
+
+	n /= 2;
+	for (size_t i = 0; i < n; i++) {
+		((char *)bin)[i] = hextable[(int)hex[i * 2]] << 4;
+		((char *)bin)[i] |= hextable[(int)hex[i * 2 + 1]];
+	}
+
+	return n;
+}

src/shared/hex.h

@@ -0,0 +1,24 @@
+/*
+ * BlueALSA - hex.h
+ * Copyright (c) 2016-2021 Arkadiusz Bokowy
+ *
+ * This file is a part of bluez-alsa.
+ *
+ * This project is licensed under the terms of the MIT license.
+ *
+ */
+
+#pragma once
+#ifndef BLUEALSA_SHARED_HEX_H_
+#define BLUEALSA_SHARED_HEX_H_
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <sys/types.h>
+
+ssize_t bin2hex(const void *bin, char *hex, size_t n);
+ssize_t hex2bin(const char *hex, void *bin, size_t n);
+
+#endif

utils/Makefile.am

@@ -7,6 +7,9 @@ bin_PROGRAMS =
 
 if ENABLE_A2DPCONF
 bin_PROGRAMS += a2dpconf
+a2dpconf_SOURCES = \
+	../src/shared/hex.c \
+	a2dpconf.c
 a2dpconf_CFLAGS = \
 	-I$(top_srcdir)/src
 a2dpconf_LDADD = \