From 2a15b1de700eb4e20c6bebb9742c8e20fffc9687 Mon Sep 17 00:00:00 2001 From: Přemysl Janouch Date: Tue, 11 Oct 2016 09:37:22 +0200 Subject: Import an MPD client interface --- liberty-proto.c | 649 +++++++++++++++++++++++++++++++++++++++++++++++++++++++- tests/proto.c | 6 +- 2 files changed, 653 insertions(+), 2 deletions(-) diff --git a/liberty-proto.c b/liberty-proto.c index 602cde6..33bb29d 100644 --- a/liberty-proto.c +++ b/liberty-proto.c @@ -1,7 +1,7 @@ /* * liberty-proto.c: the ultimate C unlibrary: protocols * - * Copyright (c) 2014 - 2015, Přemysl Janouch + * Copyright (c) 2014 - 2016, Přemysl Janouch * All rights reserved. * * Permission to use, copy, modify, and/or distribute this software for any @@ -1300,3 +1300,650 @@ fail: } #endif + +#ifdef LIBERTY_WANT_PROTO_MPD + +#include + +// --- 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); + + /// Callback to trace protocol I/O + void (*on_io_hook) (void *user_data, bool outgoing, const char *line); +}; + +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) +{ + if (self->on_io_hook) + self->on_io_hook (self->user_data, false, 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); + } + + if (self->on_io_hook) + self->on_io_hook (self->user_data, true, 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; + + // Abort and immediately restore the current idle so that MPD doesn't + // disconnect us, even though the documentation says this won't happen. + // Just sending this out should bring a dead connection down over TCP. + // TODO: set another timer to make sure we get a reply + mpd_client_idle (self, self->idling_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) + return error_set (e, "%s: %s", "socket", strerror (errno)); + + // 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)) + return error_set (e, "%s: %s", "connect", strerror (errno)); + + 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; +} + +#endif diff --git a/tests/proto.c b/tests/proto.c index 8a3b1a9..b00f78f 100644 --- a/tests/proto.c +++ b/tests/proto.c @@ -22,12 +22,16 @@ #define PROGRAM_VERSION "0" #define LIBERTY_WANT_SSL +// The MPD client is a full wrapper and needs the network +#define LIBERTY_WANT_POLLER +#define LIBERTY_WANT_ASYNC #define LIBERTY_WANT_PROTO_IRC #define LIBERTY_WANT_PROTO_HTTP #define LIBERTY_WANT_PROTO_SCGI #define LIBERTY_WANT_PROTO_FASTCGI #define LIBERTY_WANT_PROTO_WS +#define LIBERTY_WANT_PROTO_MPD #include "../liberty.c" @@ -201,7 +205,7 @@ main (int argc, char *argv[]) test_add_simple (&test, "/http-parser", NULL, test_http_parser); test_add_simple (&test, "/scgi-parser", NULL, test_scgi_parser); test_add_simple (&test, "/websockets", NULL, test_websockets); - // TODO: test FastCGI + // TODO: test FastCGI and MPD return test_run (&test); } -- cgit v1.2.3-70-g09d2