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-rw-r--r--mpd.c645
1 files changed, 645 insertions, 0 deletions
diff --git a/mpd.c b/mpd.c
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--- /dev/null
+++ b/mpd.c
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+// Copied from desktop-tools, should go to liberty if it proves useful
+
+// --- MPD client interface ----------------------------------------------------
+
+// This is a rather thin MPD client interface intended for basic tasks
+
+#define MPD_SUBSYSTEM_TABLE(XX) \
+ XX (DATABASE, 0, "database") \
+ XX (UPDATE, 1, "update") \
+ XX (STORED_PLAYLIST, 2, "stored_playlist") \
+ XX (PLAYLIST, 3, "playlist") \
+ XX (PLAYER, 4, "player") \
+ XX (MIXER, 5, "mixer") \
+ XX (OUTPUT, 6, "output") \
+ XX (OPTIONS, 7, "options") \
+ XX (STICKER, 8, "sticker") \
+ XX (SUBSCRIPTION, 9, "subscription") \
+ XX (MESSAGE, 10, "message")
+
+enum mpd_subsystem
+{
+#define XX(a, b, c) MPD_SUBSYSTEM_ ## a = (1 << b),
+ MPD_SUBSYSTEM_TABLE (XX)
+#undef XX
+ MPD_SUBSYSTEM_MAX
+};
+
+static const char *mpd_subsystem_names[] =
+{
+#define XX(a, b, c) [b] = c,
+ MPD_SUBSYSTEM_TABLE (XX)
+#undef XX
+};
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+enum mpd_client_state
+{
+ MPD_DISCONNECTED, ///< Not connected
+ MPD_CONNECTING, ///< Currently connecting
+ MPD_CONNECTED ///< Connected
+};
+
+struct mpd_response
+{
+ bool success; ///< OK or ACK
+
+ // ACK-only fields:
+
+ int error; ///< Numeric error value (ack.h)
+ int list_offset; ///< Offset of command in list
+ char *current_command; ///< Name of the erroring command
+ char *message_text; ///< Error message
+};
+
+/// Task completion callback
+typedef void (*mpd_client_task_cb) (const struct mpd_response *response,
+ const struct str_vector *data, void *user_data);
+
+struct mpd_client_task
+{
+ LIST_HEADER (struct mpd_client_task)
+
+ mpd_client_task_cb callback; ///< Callback on completion
+ void *user_data; ///< User data
+};
+
+struct mpd_client
+{
+ struct poller *poller; ///< Poller
+
+ // Connection:
+
+ enum mpd_client_state state; ///< Connection state
+ struct connector *connector; ///< Connection establisher
+
+ int socket; ///< MPD socket
+ struct str read_buffer; ///< Input yet to be processed
+ struct str write_buffer; ///< Outut yet to be be sent out
+ struct poller_fd socket_event; ///< We can read from the socket
+
+ struct poller_timer timeout_timer; ///< Connection seems to be dead
+
+ // Protocol:
+
+ bool got_hello; ///< Got the OK MPD hello message
+
+ bool idling; ///< Sent idle as the last command
+ unsigned idling_subsystems; ///< Subsystems we're idling for
+ bool in_list; ///< We're inside a command list
+
+ struct mpd_client_task *tasks; ///< Task queue
+ struct mpd_client_task *tasks_tail; ///< Tail of task queue
+ struct str_vector data; ///< Data from last command
+
+ // User configuration:
+
+ void *user_data; ///< User data for callbacks
+
+ /// Callback after connection has been successfully established
+ void (*on_connected) (void *user_data);
+
+ /// Callback for general failures or even normal disconnection;
+ /// the interface is reinitialized
+ void (*on_failure) (void *user_data);
+
+ /// Callback to receive "idle" updates.
+ /// Remember to restart the idle if needed.
+ void (*on_event) (unsigned subsystems, void *user_data);
+};
+
+static void mpd_client_reset (struct mpd_client *self);
+static void mpd_client_destroy_connector (struct mpd_client *self);
+
+static void
+mpd_client_init (struct mpd_client *self, struct poller *poller)
+{
+ memset (self, 0, sizeof *self);
+
+ self->poller = poller;
+ self->socket = -1;
+
+ str_init (&self->read_buffer);
+ str_init (&self->write_buffer);
+
+ str_vector_init (&self->data);
+
+ poller_fd_init (&self->socket_event, poller, -1);
+ poller_timer_init (&self->timeout_timer, poller);
+}
+
+static void
+mpd_client_free (struct mpd_client *self)
+{
+ // So that we don't have to repeat most of the stuff
+ mpd_client_reset (self);
+
+ str_free (&self->read_buffer);
+ str_free (&self->write_buffer);
+
+ str_vector_free (&self->data);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+/// Reinitialize the interface so that you can reconnect anew
+static void
+mpd_client_reset (struct mpd_client *self)
+{
+ if (self->state == MPD_CONNECTING)
+ mpd_client_destroy_connector (self);
+
+ if (self->socket != -1)
+ xclose (self->socket);
+ self->socket = -1;
+
+ self->socket_event.closed = true;
+ poller_fd_reset (&self->socket_event);
+ poller_timer_reset (&self->timeout_timer);
+
+ str_reset (&self->read_buffer);
+ str_reset (&self->write_buffer);
+
+ str_vector_reset (&self->data);
+
+ self->got_hello = false;
+ self->idling = false;
+ self->idling_subsystems = 0;
+ self->in_list = false;
+
+ LIST_FOR_EACH (struct mpd_client_task, iter, self->tasks)
+ free (iter);
+ self->tasks = self->tasks_tail = NULL;
+
+ self->state = MPD_DISCONNECTED;
+}
+
+static void
+mpd_client_fail (struct mpd_client *self)
+{
+ mpd_client_reset (self);
+ if (self->on_failure)
+ self->on_failure (self->user_data);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+mpd_client_parse_response (const char *p, struct mpd_response *response)
+{
+ if (!strcmp (p, "OK"))
+ return response->success = true;
+ if (!strcmp (p, "list_OK"))
+ // TODO: either implement this or fail the connection properly
+ hard_assert (!"command_list_ok_begin not implemented");
+
+ char *end = NULL;
+ if (*p++ != 'A' || *p++ != 'C' || *p++ != 'K' || *p++ != ' ' || *p++ != '[')
+ return false;
+
+ errno = 0;
+ response->error = strtoul (p, &end, 10);
+ if (errno != 0 || end == p)
+ return false;
+ p = end;
+ if (*p++ != '@')
+ return false;
+
+ errno = 0;
+ response->list_offset = strtoul (p, &end, 10);
+ if (errno != 0 || end == p)
+ return false;
+ p = end;
+ if (*p++ != ']' || *p++ != ' ' || *p++ != '{' || !(end = strchr (p, '}')))
+ return false;
+
+ response->current_command = xstrndup (p, end - p);
+ p = end + 1;
+
+ if (*p++ != ' ')
+ return false;
+
+ response->message_text = xstrdup (p);
+ response->success = false;
+ return true;
+}
+
+static void
+mpd_client_dispatch (struct mpd_client *self, struct mpd_response *response)
+{
+ struct mpd_client_task *task;
+ if (!(task = self->tasks))
+ return;
+
+ if (task->callback)
+ task->callback (response, &self->data, task->user_data);
+ str_vector_reset (&self->data);
+
+ LIST_UNLINK_WITH_TAIL (self->tasks, self->tasks_tail, task);
+ free (task);
+}
+
+static bool
+mpd_client_parse_hello (struct mpd_client *self, const char *line)
+{
+ const char hello[] = "OK MPD ";
+ if (strncmp (line, hello, sizeof hello - 1))
+ {
+ print_debug ("invalid MPD hello message");
+ return false;
+ }
+
+ // TODO: call "on_connected" now. We should however also set up a timer
+ // so that we don't wait on this message forever.
+ return self->got_hello = true;
+}
+
+static bool
+mpd_client_parse_line (struct mpd_client *self, const char *line)
+{
+ print_debug ("MPD >> %s", line);
+
+ if (!self->got_hello)
+ return mpd_client_parse_hello (self, line);
+
+ struct mpd_response response;
+ memset (&response, 0, sizeof response);
+ if (mpd_client_parse_response (line, &response))
+ {
+ mpd_client_dispatch (self, &response);
+ free (response.current_command);
+ free (response.message_text);
+ }
+ else
+ str_vector_add (&self->data, line);
+ return true;
+}
+
+/// All output from MPD commands seems to be in a trivial "key: value" format
+static char *
+mpd_client_parse_kv (char *line, char **value)
+{
+ char *sep;
+ if (!(sep = strstr (line, ": ")))
+ return NULL;
+
+ *sep = 0;
+ *value = sep + 2;
+ return line;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+mpd_client_update_poller (struct mpd_client *self)
+{
+ poller_fd_set (&self->socket_event,
+ self->write_buffer.len ? (POLLIN | POLLOUT) : POLLIN);
+}
+
+static bool
+mpd_client_process_input (struct mpd_client *self)
+{
+ // Split socket input at newlines and process them separately
+ struct str *rb = &self->read_buffer;
+ char *start = rb->str, *end = start + rb->len;
+ for (char *p = start; p < end; p++)
+ {
+ if (*p != '\n')
+ continue;
+
+ *p = 0;
+ if (!mpd_client_parse_line (self, start))
+ return false;
+ start = p + 1;
+ }
+
+ str_remove_slice (rb, 0, start - rb->str);
+ return true;
+}
+
+static void
+mpd_client_on_ready (const struct pollfd *pfd, void *user_data)
+{
+ (void) pfd;
+
+ struct mpd_client *self = user_data;
+ if (socket_io_try_read (self->socket, &self->read_buffer) != SOCKET_IO_OK
+ || !mpd_client_process_input (self)
+ || socket_io_try_write (self->socket, &self->write_buffer) != SOCKET_IO_OK)
+ mpd_client_fail (self);
+ else
+ mpd_client_update_poller (self);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+mpd_client_must_quote_char (char c)
+{
+ return (unsigned char) c <= ' ' || c == '"' || c == '\'';
+}
+
+static bool
+mpd_client_must_quote (const char *s)
+{
+ if (!*s)
+ return true;
+ for (; *s; s++)
+ if (mpd_client_must_quote_char (*s))
+ return true;
+ return false;
+}
+
+static void
+mpd_client_quote (const char *s, struct str *output)
+{
+ str_append_c (output, '"');
+ for (; *s; s++)
+ {
+ if (mpd_client_must_quote_char (*s))
+ str_append_c (output, '\\');
+ str_append_c (output, *s);
+ }
+ str_append_c (output, '"');
+}
+
+/// Beware that delivery of the event isn't deferred and you musn't make
+/// changes to the interface while processing the event!
+static void
+mpd_client_add_task
+ (struct mpd_client *self, mpd_client_task_cb cb, void *user_data)
+{
+ // This only has meaning with command_list_ok_begin, and then it requires
+ // special handling (all in-list tasks need to be specially marked and
+ // later flushed if an early ACK or OK arrives).
+ hard_assert (!self->in_list);
+
+ struct mpd_client_task *task = xcalloc (1, sizeof *self);
+ task->callback = cb;
+ task->user_data = user_data;
+ LIST_APPEND_WITH_TAIL (self->tasks, self->tasks_tail, task);
+}
+
+/// Send a command. Remember to call mpd_client_add_task() to handle responses,
+/// unless the command is being sent in a list.
+static void mpd_client_send_command
+ (struct mpd_client *self, const char *command, ...) ATTRIBUTE_SENTINEL;
+
+static void
+mpd_client_send_commandv (struct mpd_client *self, char **commands)
+{
+ // Automatically interrupt idle mode
+ if (self->idling)
+ {
+ poller_timer_reset (&self->timeout_timer);
+
+ self->idling = false;
+ self->idling_subsystems = 0;
+ mpd_client_send_command (self, "noidle", NULL);
+ }
+
+ struct str line;
+ str_init (&line);
+
+ for (; *commands; commands++)
+ {
+ if (line.len)
+ str_append_c (&line, ' ');
+
+ if (mpd_client_must_quote (*commands))
+ mpd_client_quote (*commands, &line);
+ else
+ str_append (&line, *commands);
+ }
+
+ print_debug ("MPD << %s", line.str);
+ str_append_c (&line, '\n');
+ str_append_str (&self->write_buffer, &line);
+ str_free (&line);
+
+ mpd_client_update_poller (self);
+}
+
+static void
+mpd_client_send_command (struct mpd_client *self, const char *command, ...)
+{
+ struct str_vector v;
+ str_vector_init (&v);
+
+ va_list ap;
+ va_start (ap, command);
+ for (; command; command = va_arg (ap, const char *))
+ str_vector_add (&v, command);
+ va_end (ap);
+
+ mpd_client_send_commandv (self, v.vector);
+ str_vector_free (&v);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+mpd_client_list_begin (struct mpd_client *self)
+{
+ hard_assert (!self->in_list);
+ mpd_client_send_command (self, "command_list_begin", NULL);
+ self->in_list = true;
+}
+
+/// End a list of commands. Remember to call mpd_client_add_task()
+/// to handle the summary response.
+static void
+mpd_client_list_end (struct mpd_client *self)
+{
+ hard_assert (self->in_list);
+ mpd_client_send_command (self, "command_list_end", NULL);
+ self->in_list = false;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+mpd_resolve_subsystem (const char *name, unsigned *output)
+{
+ for (size_t i = 0; i < N_ELEMENTS (mpd_subsystem_names); i++)
+ if (!strcasecmp_ascii (name, mpd_subsystem_names[i]))
+ {
+ *output |= 1 << i;
+ return true;
+ }
+ return false;
+}
+
+static void
+mpd_client_on_idle_return (const struct mpd_response *response,
+ const struct str_vector *data, void *user_data)
+{
+ (void) response;
+
+ struct mpd_client *self = user_data;
+ unsigned subsystems = 0;
+ for (size_t i = 0; i < data->len; i++)
+ {
+ char *value, *key;
+ if (!(key = mpd_client_parse_kv (data->vector[i], &value)))
+ print_debug ("%s: %s", "erroneous MPD output", data->vector[i]);
+ else if (strcasecmp_ascii (key, "changed"))
+ print_debug ("%s: %s", "unexpected idle key", key);
+ else if (!mpd_resolve_subsystem (value, &subsystems))
+ print_debug ("%s: %s", "unknown subsystem", value);
+ }
+
+ // Not resetting "idling" here, we may send an extra "noidle" no problem
+ if (self->on_event && subsystems)
+ self->on_event (subsystems, self->user_data);
+}
+
+static void mpd_client_idle (struct mpd_client *self, unsigned subsystems);
+
+static void
+mpd_client_on_timeout (void *user_data)
+{
+ struct mpd_client *self = user_data;
+ unsigned subsystems = self->idling_subsystems;
+
+ // Just sending this out should bring a dead connection down over TCP
+ // TODO: set another timer to make sure the ping reply arrives
+ mpd_client_send_command (self, "ping", NULL);
+ mpd_client_add_task (self, NULL, NULL);
+
+ // Restore the incriminating idle immediately
+ mpd_client_idle (self, subsystems);
+}
+
+/// When not expecting to send any further commands, you should call this
+/// in order to keep the connection alive. Or to receive updates.
+static void
+mpd_client_idle (struct mpd_client *self, unsigned subsystems)
+{
+ hard_assert (!self->in_list);
+
+ struct str_vector v;
+ str_vector_init (&v);
+
+ str_vector_add (&v, "idle");
+ for (size_t i = 0; i < N_ELEMENTS (mpd_subsystem_names); i++)
+ if (subsystems & (1 << i))
+ str_vector_add (&v, mpd_subsystem_names[i]);
+
+ mpd_client_send_commandv (self, v.vector);
+ str_vector_free (&v);
+
+ self->timeout_timer.dispatcher = mpd_client_on_timeout;
+ self->timeout_timer.user_data = self;
+ poller_timer_set (&self->timeout_timer, 5 * 60 * 1000);
+
+ mpd_client_add_task (self, mpd_client_on_idle_return, self);
+ self->idling = true;
+ self->idling_subsystems = subsystems;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+mpd_client_finish_connection (struct mpd_client *self, int socket)
+{
+ set_blocking (socket, false);
+ self->socket = socket;
+ self->state = MPD_CONNECTED;
+
+ poller_fd_init (&self->socket_event, self->poller, self->socket);
+ self->socket_event.dispatcher = mpd_client_on_ready;
+ self->socket_event.user_data = self;
+
+ mpd_client_update_poller (self);
+
+ if (self->on_connected)
+ self->on_connected (self->user_data);
+}
+
+static void
+mpd_client_destroy_connector (struct mpd_client *self)
+{
+ if (self->connector)
+ connector_free (self->connector);
+ free (self->connector);
+ self->connector = NULL;
+
+ // Not connecting anymore
+ self->state = MPD_DISCONNECTED;
+}
+
+static void
+mpd_client_on_connector_failure (void *user_data)
+{
+ struct mpd_client *self = user_data;
+ mpd_client_destroy_connector (self);
+ mpd_client_fail (self);
+}
+
+static void
+mpd_client_on_connector_connected
+ (void *user_data, int socket, const char *host)
+{
+ (void) host;
+
+ struct mpd_client *self = user_data;
+ mpd_client_destroy_connector (self);
+ mpd_client_finish_connection (self, socket);
+}
+
+static bool
+mpd_client_connect_unix (struct mpd_client *self, const char *address,
+ struct error **e)
+{
+ int fd = socket (AF_UNIX, SOCK_STREAM, 0);
+ if (fd == -1)
+ {
+ error_set (e, "%s: %s", "socket", strerror (errno));
+ return false;
+ }
+
+ // Expand tilde if needed
+ char *expanded = resolve_filename (address, xstrdup);
+
+ struct sockaddr_un sun;
+ sun.sun_family = AF_UNIX;
+ strncpy (sun.sun_path, expanded, sizeof sun.sun_path);
+ sun.sun_path[sizeof sun.sun_path - 1] = 0;
+
+ free (expanded);
+
+ if (connect (fd, (struct sockaddr *) &sun, sizeof sun))
+ {
+ error_set (e, "%s: %s", "connect", strerror (errno));
+ return false;
+ }
+
+ mpd_client_finish_connection (self, fd);
+ return true;
+}
+
+static bool
+mpd_client_connect (struct mpd_client *self, const char *address,
+ const char *service, struct error **e)
+{
+ hard_assert (self->state == MPD_DISCONNECTED);
+
+ // If it looks like a path, assume it's a UNIX socket
+ if (strchr (address, '/'))
+ return mpd_client_connect_unix (self, address, e);
+
+ struct connector *connector = xmalloc (sizeof *connector);
+ connector_init (connector, self->poller);
+ self->connector = connector;
+
+ connector->user_data = self;
+ connector->on_connected = mpd_client_on_connector_connected;
+ connector->on_failure = mpd_client_on_connector_failure;
+
+ connector_add_target (connector, address, service);
+ self->state = MPD_CONNECTING;
+ return true;
+}