diff --git a/Makefile.am b/Makefile.am
index 92bd0173d..d4fec31ff 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -285,6 +285,10 @@ src_mpd_SOURCES = \
src/client_process.c \
src/client_read.c \
src/client_write.c \
+ src/client_message.h \
+ src/client_message.c \
+ src/client_subscribe.h \
+ src/client_subscribe.c \
src/server_socket.c \
src/listen.c \
src/log.c \
diff --git a/NEWS b/NEWS
index 178250304..9106eb82e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,6 @@
ver 0.17 (2011/??/??)
+* protocol:
+ - support client-to-client communication
* input:
- cdio_paranoia: new input plugin to play audio CDs
- curl: enable CURLOPT_NETRC
diff --git a/doc/protocol.xml b/doc/protocol.xml
index a02a94e32..cf4de27c1 100644
--- a/doc/protocol.xml
+++ b/doc/protocol.xml
@@ -204,6 +204,19 @@
has been modified.
+
+
+ subscription: a client
+ has subscribed or unsubscribed to a channel
+
+
+
+
+ message: a message was
+ received on a channel this client is subscribed to;
+ this event is only emitted when the queue is empty
+
+
While a client is waiting for idle
@@ -1676,5 +1689,105 @@ suffix: mpc
+
+
+ Client to client
+
+
+ Clients can communicate with each others over "channels". A
+ channel is created by a client subscribing to it. More than
+ one client can be subscribed to a channel at a time; all of
+ them will receive the messages which get sent to it.
+
+
+
+ Each time a client subscribes or unsubscribes, the global idle
+ event subscription is generated. In
+ conjunction with the channels command, this
+ may be used to auto-detect clients providing additional
+ services.
+
+
+
+ A new messages is indicated by the message
+ idle event.
+
+
+
+
+
+
+ subscribe
+ NAME
+
+
+
+
+ Subscribe to a channel. The channel is created if it
+ does not exist already. The name may consist of
+ alphanumeric ASCII characters plus underscore, dash, dot
+ and colon.
+
+
+
+
+
+
+
+ unsubscribe
+ NAME
+
+
+
+
+ Unsubscribe from a channel.
+
+
+
+
+
+
+
+ channels
+
+
+
+
+ Obtain a list of all channels. The response is a list
+ of "channel:" lines.
+
+
+
+
+
+
+
+ readmessages
+
+
+
+
+ Reads messages for this client. The response is a list
+ of "channel:" and "message:" lines.
+
+
+
+
+
+
+
+ sendmessage
+ CHANNEL
+ TEXT
+
+
+
+
+ Send a message to the specified channel.
+
+
+
+
+
diff --git a/src/client_internal.h b/src/client_internal.h
index d675ed7c6..ba97e4b8f 100644
--- a/src/client_internal.h
+++ b/src/client_internal.h
@@ -21,11 +21,17 @@
#define MPD_CLIENT_INTERNAL_H
#include "client.h"
+#include "client_message.h"
#include "command.h"
#undef G_LOG_DOMAIN
#define G_LOG_DOMAIN "client"
+enum {
+ CLIENT_MAX_SUBSCRIPTIONS = 16,
+ CLIENT_MAX_MESSAGES = 64,
+};
+
struct deferred_buffer {
size_t size;
char data[sizeof(long)];
@@ -69,6 +75,28 @@ struct client {
/** idle flags that the client wants to receive */
unsigned idle_subscriptions;
+
+ /**
+ * A list of channel names this client is subscribed to.
+ */
+ GSList *subscriptions;
+
+ /**
+ * The number of subscriptions in #subscriptions. Used to
+ * limit the number of subscriptions.
+ */
+ unsigned num_subscriptions;
+
+ /**
+ * A list of messages this client has received in reverse
+ * order (latest first).
+ */
+ GSList *messages;
+
+ /**
+ * The number of messages in #messages.
+ */
+ unsigned num_messages;
};
extern unsigned int client_max_connections;
diff --git a/src/client_message.c b/src/client_message.c
new file mode 100644
index 000000000..b681b4e7f
--- /dev/null
+++ b/src/client_message.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_message.h"
+
+#include
+#include
+
+G_GNUC_PURE
+static bool
+valid_channel_char(const char ch)
+{
+ return g_ascii_isalnum(ch) ||
+ ch == '_' || ch == '-' || ch == '.' || ch == ':';
+}
+
+bool
+client_message_valid_channel_name(const char *name)
+{
+ do {
+ if (!valid_channel_char(*name))
+ return false;
+ } while (*++name != 0);
+
+ return true;
+}
+
+void
+client_message_init_null(struct client_message *msg)
+{
+ assert(msg != NULL);
+
+ msg->channel = NULL;
+ msg->message = NULL;
+}
+
+void
+client_message_init(struct client_message *msg,
+ const char *channel, const char *message)
+{
+ assert(msg != NULL);
+
+ msg->channel = g_strdup(channel);
+ msg->message = g_strdup(message);
+}
+
+void
+client_message_copy(struct client_message *dest,
+ const struct client_message *src)
+{
+ assert(dest != NULL);
+ assert(src != NULL);
+ assert(client_message_defined(src));
+
+ client_message_init(dest, src->channel, src->message);
+}
+
+struct client_message *
+client_message_dup(const struct client_message *src)
+{
+ struct client_message *dest = g_slice_new(struct client_message);
+ client_message_copy(dest, src);
+ return dest;
+}
+
+void
+client_message_deinit(struct client_message *msg)
+{
+ assert(msg != NULL);
+
+ g_free(msg->channel);
+ g_free(msg->message);
+}
+
+void
+client_message_free(struct client_message *msg)
+{
+ client_message_deinit(msg);
+ g_slice_free(struct client_message, msg);
+}
diff --git a/src/client_message.h b/src/client_message.h
new file mode 100644
index 000000000..5c7e86c15
--- /dev/null
+++ b/src/client_message.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_CLIENT_MESSAGE_H
+#define MPD_CLIENT_MESSAGE_H
+
+#include
+#include
+#include
+#include
+
+/**
+ * A client-to-client message.
+ */
+struct client_message {
+ char *channel;
+
+ char *message;
+};
+
+G_GNUC_PURE
+bool
+client_message_valid_channel_name(const char *name);
+
+G_GNUC_PURE
+static inline bool
+client_message_defined(const struct client_message *msg)
+{
+ assert(msg != NULL);
+ assert((msg->channel == NULL) == (msg->message == NULL));
+
+ return msg->channel != NULL;
+}
+
+void
+client_message_init_null(struct client_message *msg);
+
+void
+client_message_init(struct client_message *msg,
+ const char *channel, const char *message);
+
+void
+client_message_copy(struct client_message *dest,
+ const struct client_message *src);
+
+G_GNUC_MALLOC G_GNUC_PURE
+struct client_message *
+client_message_dup(const struct client_message *src);
+
+void
+client_message_deinit(struct client_message *msg);
+
+void
+client_message_free(struct client_message *msg);
+
+#endif
diff --git a/src/client_new.c b/src/client_new.c
index ffe7c7ce6..5b2dfde65 100644
--- a/src/client_new.c
+++ b/src/client_new.c
@@ -121,6 +121,10 @@ client_new(struct player_control *player_control,
client->send_buf_used = 0;
+ client->subscriptions = NULL;
+ client->messages = NULL;
+ client->num_messages = 0;
+
(void)send(fd, GREETING, sizeof(GREETING) - 1, 0);
client_list_add(client);
diff --git a/src/client_subscribe.c b/src/client_subscribe.c
new file mode 100644
index 000000000..c65a7ed31
--- /dev/null
+++ b/src/client_subscribe.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_subscribe.h"
+#include "client_internal.h"
+#include "client_idle.h"
+#include "idle.h"
+
+#include
+
+G_GNUC_PURE
+static GSList *
+client_find_subscription(const struct client *client, const char *channel)
+{
+ for (GSList *i = client->subscriptions; i != NULL; i = g_slist_next(i))
+ if (strcmp((const char *)i->data, channel) == 0)
+ return i;
+
+ return NULL;
+}
+
+enum client_subscribe_result
+client_subscribe(struct client *client, const char *channel)
+{
+ assert(client != NULL);
+ assert(channel != NULL);
+
+ if (!client_message_valid_channel_name(channel))
+ return CLIENT_SUBSCRIBE_INVALID;
+
+ if (client_find_subscription(client, channel) != NULL)
+ return CLIENT_SUBSCRIBE_ALREADY;
+
+ if (client->num_subscriptions >= CLIENT_MAX_SUBSCRIPTIONS)
+ return CLIENT_SUBSCRIBE_FULL;
+
+ client->subscriptions = g_slist_prepend(client->subscriptions,
+ g_strdup(channel));
+ ++client->num_subscriptions;
+
+ idle_add(IDLE_SUBSCRIPTION);
+
+ return CLIENT_SUBSCRIBE_OK;
+}
+
+bool
+client_unsubscribe(struct client *client, const char *channel)
+{
+ GSList *i = client_find_subscription(client, channel);
+ if (i == NULL)
+ return false;
+
+ assert(client->num_subscriptions > 0);
+
+ client->subscriptions = g_slist_remove(client->subscriptions, i->data);
+ --client->num_subscriptions;
+
+ idle_add(IDLE_SUBSCRIPTION);
+
+ assert((client->num_subscriptions == 0) ==
+ (client->subscriptions == NULL));
+
+ return true;
+}
+
+void
+client_unsubscribe_all(struct client *client)
+{
+ for (GSList *i = client->subscriptions; i != NULL; i = g_slist_next(i))
+ g_free(i->data);
+
+ g_slist_free(client->subscriptions);
+ client->subscriptions = NULL;
+ client->num_subscriptions = 0;
+}
+
+bool
+client_push_message(struct client *client, const struct client_message *msg)
+{
+ assert(client != NULL);
+ assert(msg != NULL);
+ assert(client_message_defined(msg));
+
+ if (client->num_messages >= CLIENT_MAX_MESSAGES ||
+ client_find_subscription(client, msg->channel) == NULL)
+ return false;
+
+ if (client->messages == NULL)
+ client_idle_add(client, IDLE_MESSAGE);
+
+ client->messages = g_slist_prepend(client->messages,
+ client_message_dup(msg));
+ ++client->num_messages;
+
+ return true;
+}
+
+GSList *
+client_read_messages(struct client *client)
+{
+ GSList *messages = g_slist_reverse(client->messages);
+
+ client->messages = NULL;
+ client->num_messages = 0;
+
+ return messages;
+}
diff --git a/src/client_subscribe.h b/src/client_subscribe.h
new file mode 100644
index 000000000..09f864417
--- /dev/null
+++ b/src/client_subscribe.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_CLIENT_SUBSCRIBE_H
+#define MPD_CLIENT_SUBSCRIBE_H
+
+#include
+#include
+
+struct client;
+struct client_message;
+
+enum client_subscribe_result {
+ /** success */
+ CLIENT_SUBSCRIBE_OK,
+
+ /** invalid channel name */
+ CLIENT_SUBSCRIBE_INVALID,
+
+ /** already subscribed to this channel */
+ CLIENT_SUBSCRIBE_ALREADY,
+
+ /** too many subscriptions */
+ CLIENT_SUBSCRIBE_FULL,
+};
+
+enum client_subscribe_result
+client_subscribe(struct client *client, const char *channel);
+
+bool
+client_unsubscribe(struct client *client, const char *channel);
+
+void
+client_unsubscribe_all(struct client *client);
+
+bool
+client_push_message(struct client *client, const struct client_message *msg);
+
+G_GNUC_MALLOC
+GSList *
+client_read_messages(struct client *client);
+
+#endif
diff --git a/src/command.c b/src/command.c
index 354bf85f5..aeed55a1b 100644
--- a/src/command.c
+++ b/src/command.c
@@ -46,6 +46,7 @@
#include "client.h"
#include "client_idle.h"
#include "client_internal.h"
+#include "client_subscribe.h"
#include "tag_print.h"
#include "path.h"
#include "replay_gain_config.h"
@@ -1837,6 +1838,172 @@ handle_sticker(struct client *client, int argc, char *argv[])
}
#endif
+static enum command_return
+handle_subscribe(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
+{
+ assert(argc == 2);
+
+ switch (client_subscribe(client, argv[1])) {
+ case CLIENT_SUBSCRIBE_OK:
+ return COMMAND_RETURN_OK;
+
+ case CLIENT_SUBSCRIBE_INVALID:
+ command_error(client, ACK_ERROR_ARG,
+ "invalid channel name");
+ return COMMAND_RETURN_ERROR;
+
+ case CLIENT_SUBSCRIBE_ALREADY:
+ command_error(client, ACK_ERROR_EXIST,
+ "already subscribed to this channel");
+ return COMMAND_RETURN_ERROR;
+
+ case CLIENT_SUBSCRIBE_FULL:
+ command_error(client, ACK_ERROR_EXIST,
+ "subscription list is full");
+ return COMMAND_RETURN_ERROR;
+ }
+
+ /* unreachable */
+ return COMMAND_RETURN_OK;
+}
+
+static enum command_return
+handle_unsubscribe(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
+{
+ assert(argc == 2);
+
+ if (client_unsubscribe(client, argv[1]))
+ return COMMAND_RETURN_OK;
+ else {
+ command_error(client, ACK_ERROR_NO_EXIST,
+ "not subscribed to this channel");
+ return COMMAND_RETURN_ERROR;
+ }
+}
+
+struct channels_context {
+ GStringChunk *chunk;
+
+ GHashTable *channels;
+};
+
+static void
+collect_channels(gpointer data, gpointer user_data)
+{
+ struct channels_context *context = user_data;
+ const struct client *client = data;
+
+ for (GSList *i = client->subscriptions; i != NULL;
+ i = g_slist_next(i)) {
+ const char *channel = i->data;
+
+ if (g_hash_table_lookup(context->channels, channel) == NULL) {
+ char *channel2 = g_string_chunk_insert(context->chunk,
+ channel);
+ g_hash_table_insert(context->channels, channel2,
+ context);
+ }
+ }
+}
+
+static void
+print_channel(gpointer key, G_GNUC_UNUSED gpointer value, gpointer user_data)
+{
+ struct client *client = user_data;
+ const char *channel = key;
+
+ client_printf(client, "channel: %s\n", channel);
+}
+
+static enum command_return
+handle_channels(struct client *client,
+ G_GNUC_UNUSED int argc, G_GNUC_UNUSED char *argv[])
+{
+ assert(argc == 1);
+
+ struct channels_context context = {
+ .chunk = g_string_chunk_new(1024),
+ .channels = g_hash_table_new(g_str_hash, g_str_equal),
+ };
+
+ client_list_foreach(collect_channels, &context);
+
+ g_hash_table_foreach(context.channels, print_channel, client);
+
+ g_hash_table_destroy(context.channels);
+ g_string_chunk_free(context.chunk);
+
+ return COMMAND_RETURN_OK;
+}
+
+static enum command_return
+handle_read_messages(struct client *client,
+ G_GNUC_UNUSED int argc, G_GNUC_UNUSED char *argv[])
+{
+ assert(argc == 1);
+
+ GSList *messages = client_read_messages(client);
+
+ for (GSList *i = messages; i != NULL; i = g_slist_next(i)) {
+ struct client_message *msg = i->data;
+
+ client_printf(client, "channel: %s\nmessage: %s\n",
+ msg->channel, msg->message);
+ client_message_free(msg);
+ }
+
+ g_slist_free(messages);
+
+ return COMMAND_RETURN_OK;
+}
+
+struct send_message_context {
+ struct client_message msg;
+
+ bool sent;
+};
+
+static void
+send_message(gpointer data, gpointer user_data)
+{
+ struct send_message_context *context = user_data;
+ struct client *client = data;
+
+ if (client_push_message(client, &context->msg))
+ context->sent = true;
+}
+
+static enum command_return
+handle_send_message(struct client *client,
+ G_GNUC_UNUSED int argc, G_GNUC_UNUSED char *argv[])
+{
+ assert(argc == 3);
+
+ if (!client_message_valid_channel_name(argv[1])) {
+ command_error(client, ACK_ERROR_ARG,
+ "invalid channel name");
+ return COMMAND_RETURN_ERROR;
+ }
+
+ struct send_message_context context = {
+ .sent = false,
+ };
+
+ client_message_init(&context.msg, argv[1], argv[2]);
+
+ client_list_foreach(send_message, &context);
+
+ client_message_deinit(&context.msg);
+
+ if (context.sent)
+ return COMMAND_RETURN_OK;
+ else {
+ command_error(client, ACK_ERROR_NO_EXIST,
+ "nobody is subscribed to this channel");
+ return COMMAND_RETURN_ERROR;
+ }
+}
+
/**
* The command registry.
*
@@ -1845,6 +2012,7 @@ handle_sticker(struct client *client, int argc, char *argv[])
static const struct command commands[] = {
{ "add", PERMISSION_ADD, 1, 1, handle_add },
{ "addid", PERMISSION_ADD, 1, 2, handle_addid },
+ { "channels", PERMISSION_READ, 0, 0, handle_channels },
{ "clear", PERMISSION_CONTROL, 0, 0, handle_clear },
{ "clearerror", PERMISSION_CONTROL, 0, 0, handle_clearerror },
{ "close", PERMISSION_NONE, -1, -1, handle_close },
@@ -1895,6 +2063,7 @@ static const struct command commands[] = {
{ "plchangesposid", PERMISSION_READ, 1, 1, handle_plchangesposid },
{ "previous", PERMISSION_CONTROL, 0, 0, handle_previous },
{ "random", PERMISSION_CONTROL, 1, 1, handle_random },
+ { "readmessages", PERMISSION_READ, 0, 0, handle_read_messages },
{ "rename", PERMISSION_CONTROL, 2, 2, handle_rename },
{ "repeat", PERMISSION_CONTROL, 1, 1, handle_repeat },
{ "replay_gain_mode", PERMISSION_CONTROL, 1, 1,
@@ -1907,6 +2076,7 @@ static const struct command commands[] = {
{ "search", PERMISSION_READ, 2, -1, handle_search },
{ "seek", PERMISSION_CONTROL, 2, 2, handle_seek },
{ "seekid", PERMISSION_CONTROL, 2, 2, handle_seekid },
+ { "sendmessage", PERMISSION_CONTROL, 2, 2, handle_send_message },
{ "setvol", PERMISSION_CONTROL, 1, 1, handle_setvol },
{ "shuffle", PERMISSION_CONTROL, 0, 1, handle_shuffle },
{ "single", PERMISSION_CONTROL, 1, 1, handle_single },
@@ -1916,9 +2086,11 @@ static const struct command commands[] = {
{ "sticker", PERMISSION_ADMIN, 3, -1, handle_sticker },
#endif
{ "stop", PERMISSION_CONTROL, 0, 0, handle_stop },
+ { "subscribe", PERMISSION_READ, 1, 1, handle_subscribe },
{ "swap", PERMISSION_CONTROL, 2, 2, handle_swap },
{ "swapid", PERMISSION_CONTROL, 2, 2, handle_swapid },
{ "tagtypes", PERMISSION_READ, 0, 0, handle_tagtypes },
+ { "unsubscribe", PERMISSION_READ, 1, 1, handle_unsubscribe },
{ "update", PERMISSION_ADMIN, 0, 1, handle_update },
{ "urlhandlers", PERMISSION_READ, 0, 0, handle_urlhandlers },
};
diff --git a/src/idle.c b/src/idle.c
index 7b9f658c6..2d174d78a 100644
--- a/src/idle.c
+++ b/src/idle.c
@@ -42,6 +42,8 @@ static const char *const idle_names[] = {
"options",
"sticker",
"update",
+ "subscription",
+ "message",
NULL
};
diff --git a/src/idle.h b/src/idle.h
index 52adc4d6e..0156933c0 100644
--- a/src/idle.h
+++ b/src/idle.h
@@ -53,6 +53,12 @@ enum {
/** a database update has started or finished. */
IDLE_UPDATE = 0x100,
+
+ /** a client has subscribed or unsubscribed to/from a channel */
+ IDLE_SUBSCRIPTION = 0x200,
+
+ /** a message on the subscribed channel was receivedd */
+ IDLE_MESSAGE = 0x400,
};
/**