modules/control/netsync.c

   1 /*****************************************************************************
   2  * netsync.c: synchronization between several network clients.
   3  *****************************************************************************
   4  * Copyright (C) 2004-2009 the VideoLAN team
   5  *
   6  * Authors: Gildas Bazin <gbazin@videolan.org>
   7  *          Jean-Paul Saman <jpsaman@videolan.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30 #include <assert.h>
  31
  32 #define VLC_MODULE_LICENSE VLC_LICENSE_GPL_2_PLUS
  33 #include <vlc_common.h>
  34 #include <vlc_plugin.h>
  35 #include <vlc_interface.h>
  36 #include <vlc_input.h>
  37 #include <vlc_playlist_legacy.h>
  38
  39 #include <sys/types.h>
  40 #include <unistd.h>
  41 #ifdef HAVE_POLL
  42 #   include <poll.h>
  43 #endif
  44
  45 #include <vlc_network.h>
  46
  47 #define NETSYNC_PORT 9875
  48
  49 /*****************************************************************************
  50  * Module descriptor
  51  *****************************************************************************/
  52 static int  Open (vlc_object_t *);
  53 static void Close(vlc_object_t *);
  54
  55 #define NETSYNC_TEXT N_("Network master clock")
  56 #define NETSYNC_LONGTEXT N_("When set, " \
  57   "this VLC instance will act as the master clock for synchronization " \
  58   "for clients listening")
  59
  60 #define MIP_TEXT N_("Master server IP address")
  61 #define MIP_LONGTEXT N_("The IP address of " \
  62   "the network master clock to use for clock synchronization.")
  63
  64 #define NETSYNC_TIMEOUT_TEXT N_("UDP timeout (in ms)")
  65 #define NETSYNC_TIMEOUT_LONGTEXT N_("Length of time (in ms) " \
  66   "until aborting data reception.")
  67
  68 vlc_module_begin()
  69     set_shortname(N_("Network Sync"))
  70     set_description(N_("Network synchronization"))
  71     set_category(CAT_ADVANCED)
  72     set_subcategory(SUBCAT_ADVANCED_MISC)
  73
  74     add_bool("netsync-master", false,
  75               NETSYNC_TEXT, NETSYNC_LONGTEXT, true)
  76     add_string("netsync-master-ip", NULL, MIP_TEXT, MIP_LONGTEXT,
  77                 true)
  78     add_integer("netsync-timeout", 500,
  79                  NETSYNC_TIMEOUT_TEXT, NETSYNC_TIMEOUT_LONGTEXT, true)
  80
  81     set_capability("interface", 0)
  82     set_callbacks(Open, Close)
  83 vlc_module_end()
  84
  85 /*****************************************************************************
  86  * Local prototypes
  87  *****************************************************************************/
  88 struct intf_sys_t {
  89     int            fd;
  90     int            timeout;
  91     bool           is_master;
  92     playlist_t     *playlist;
  93
  94     /* */
  95     input_thread_t *input;
  96     vlc_thread_t   thread;
  97 };
  98
  99 static int PlaylistEvent(vlc_object_t *, char const *cmd,
 100                          vlc_value_t oldval, vlc_value_t newval, void *data);
 101
 102 /*****************************************************************************
 103  * Activate: initialize and create stuff
 104  *****************************************************************************/
 105 static int Open(vlc_object_t *object)
 106 {
 107     intf_thread_t *intf = (intf_thread_t*)object;
 108     intf_sys_t    *sys;
 109     int fd;
 110
 111     if (!var_InheritBool(intf, "netsync-master")) {
 112         char *psz_master = var_InheritString(intf, "netsync-master-ip");
 113         if (psz_master == NULL) {
 114             msg_Err(intf, "master address not specified");
 115             return VLC_EGENERIC;
 116         }
 117         fd = net_ConnectUDP(VLC_OBJECT(intf), psz_master, NETSYNC_PORT, -1);
 118         free(psz_master);
 119     } else {
 120         fd = net_ListenUDP1(VLC_OBJECT(intf), NULL, NETSYNC_PORT);
 121     }
 122
 123     if (fd == -1) {
 124         msg_Err(intf, "Netsync socket failure");
 125         return VLC_EGENERIC;
 126     }
 127
 128     intf->p_sys = sys = malloc(sizeof(*sys));
 129     if (!sys) {
 130         net_Close(fd);
 131         return VLC_ENOMEM;
 132     }
 133
 134     sys->fd = fd;
 135     sys->is_master = var_InheritBool(intf, "netsync-master");
 136     sys->timeout = var_InheritInteger(intf, "netsync-timeout");
 137     if (sys->timeout < 500)
 138         sys->timeout = 500;
 139     sys->playlist = pl_Get(intf);
 140     sys->input = NULL;
 141
 142     var_AddCallback(sys->playlist, "input-current", PlaylistEvent, intf);
 143     return VLC_SUCCESS;
 144 }
 145
 146 /*****************************************************************************
 147  * Close: destroy interface
 148  *****************************************************************************/
 149 void Close(vlc_object_t *object)
 150 {
 151     intf_thread_t *intf = (intf_thread_t*)object;
 152     intf_sys_t *sys = intf->p_sys;
 153
 154     var_DelCallback(sys->playlist, "input-current", PlaylistEvent, intf);
 155
 156     if (sys->input != NULL) {
 157         vlc_cancel(sys->thread);
 158         vlc_join(sys->thread, NULL);
 159     }
 160
 161     net_Close(sys->fd);
 162     free(sys);
 163 }
 164
 165 static vlc_tick_t GetPcrSystem(input_thread_t *input)
 166 {
 167     int canc = vlc_savecancel();
 168     /* TODO use the delay */
 169     vlc_tick_t system;
 170     if (input_GetPcrSystem(input, &system, NULL))
 171         system = -1;
 172     vlc_restorecancel(canc);
 173
 174     return system;
 175 }
 176
 177 static void *Master(void *handle)
 178 {
 179     intf_thread_t *intf = handle;
 180     intf_sys_t *sys = intf->p_sys;
 181     for (;;) {
 182         struct pollfd ufd = { .fd = sys->fd, .events = POLLIN, };
 183         uint64_t data[2];
 184
 185         if (poll(&ufd, 1, -1) < 0)
 186             continue;
 187
 188         /* We received something */
 189         struct sockaddr_storage from;
 190         socklen_t fromlen = sizeof (from);
 191
 192         if (recvfrom(sys->fd, data, 8, 0,
 193                      (struct sockaddr *)&from, &fromlen) < 8)
 194             continue;
 195
 196         vlc_tick_t master_system = GetPcrSystem(sys->input);
 197         if (master_system < 0)
 198             continue;
 199
 200         data[0] = hton64(vlc_tick_now());
 201         data[1] = hton64(master_system);
 202
 203         /* Reply to the sender */
 204         sendto(sys->fd, data, 16, 0,
 205                (struct sockaddr *)&from, fromlen);
 206 #if 0
 207         /* not sure we need the client information to sync,
 208            since we are the master anyway */
 209         vlc_tick_t client_system = ntoh64(data[0]);
 210         msg_Dbg(intf, "Master clockref: %"PRId64" -> %"PRId64", from %s "
 211                  "(date: %"PRId64")", client_system, master_system,
 212                  (from.ss_family == AF_INET) ? inet_ntoa(((struct sockaddr_in *)&from)->sin_addr)
 213                  : "non-IPv4", /*date*/ 0);
 214 #endif
 215     }
 216     return NULL;
 217 }
 218
 219 static void *Slave(void *handle)
 220 {
 221     intf_thread_t *intf = handle;
 222     intf_sys_t *sys = intf->p_sys;
 223
 224     for (;;) {
 225         struct pollfd ufd = { .fd = sys->fd, .events = POLLIN, };
 226         uint64_t data[2];
 227
 228         vlc_tick_t system = GetPcrSystem(sys->input);
 229         if (system < 0)
 230             goto wait;
 231
 232         /* Send clock request to the master */
 233         const vlc_tick_t send_date = vlc_tick_now();
 234
 235         data[0] = hton64(system);
 236         send(sys->fd, data, 8, 0);
 237
 238         /* Don't block */
 239         if (poll(&ufd, 1, sys->timeout) <= 0)
 240             continue;
 241
 242         const vlc_tick_t receive_date = vlc_tick_now();
 243         if (recv(sys->fd, data, 16, 0) < 16)
 244             goto wait;
 245
 246         const vlc_tick_t master_date   = ntoh64(data[0]);
 247         const vlc_tick_t master_system = ntoh64(data[1]);
 248         const vlc_tick_t diff_date = receive_date -
 249                                   ((receive_date - send_date) / 2 + master_date);
 250
 251         if (master_system > 0) {
 252             int canc = vlc_savecancel();
 253
 254             vlc_tick_t client_system;
 255             if (!input_GetPcrSystem(sys->input, &client_system, NULL)) {
 256                 const vlc_tick_t diff_system = client_system - master_system - diff_date;
 257                 if (diff_system != 0) {
 258                     input_ModifyPcrSystem(sys->input, true, master_system - diff_date);
 259 #if 0
 260                     msg_Dbg(intf, "Slave clockref: %"PRId64" -> %"PRId64" -> %"PRId64","
 261                              " clock diff: %"PRId64", diff: %"PRId64"",
 262                              system, master_system, client_system,
 263                              diff_system, diff_date);
 264 #endif
 265                 }
 266             }
 267             vlc_restorecancel(canc);
 268         }
 269     wait:
 270         vlc_tick_sleep(INTF_IDLE_SLEEP);
 271     }
 272     return NULL;
 273 }
 274
 275 static int PlaylistEvent(vlc_object_t *object, char const *cmd,
 276                          vlc_value_t oldval, vlc_value_t newval, void *data)
 277 {
 278     VLC_UNUSED(cmd); VLC_UNUSED(object);
 279     intf_thread_t  *intf = data;
 280     intf_sys_t     *sys = intf->p_sys;
 281     input_thread_t *input = newval.p_address;
 282
 283     if (sys->input != NULL) {
 284         msg_Err(intf, "InputEvent DEAD");
 285         assert(oldval.p_address == sys->input);
 286
 287         vlc_cancel(sys->thread);
 288         vlc_join(sys->thread, NULL);
 289     }
 290
 291     sys->input = input;
 292
 293     if (input != NULL) {
 294         if (vlc_clone(&sys->thread, sys->is_master ? Master : Slave, intf,
 295                       VLC_THREAD_PRIORITY_INPUT))
 296             sys->input = NULL;
 297     }
 298     return VLC_SUCCESS;
 299 }
 300