sync_filter.c

   1 /* Copyright (C) 2013 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file sync_filter.c Playback synchronization filter. */
   4
   5 #include <netinet/in.h>
   6 #include <sys/socket.h>
   7 #include <regex.h>
   8 #include <sys/types.h>
   9 #include <arpa/inet.h>
  10 #include <sys/un.h>
  11 #include <netdb.h>
  12 #include <lopsub.h>
  13
  14 #include "filter_cmd.lsg.h"
  15 #include "para.h"
  16 #include "list.h"
  17 #include "net.h"
  18 #include "sched.h"
  19 #include "buffer_tree.h"
  20 #include "filter.h"
  21 #include "string.h"
  22 #include "fd.h"
  23 #include "error.h"
  24
  25 struct sync_buddy_info {
  26         const char *url;
  27         char *host;
  28         int port;
  29         struct addrinfo *ai;
  30         bool disabled;
  31 };
  32
  33 /* One active buddy */
  34 struct sync_buddy {
  35         int fd;
  36         struct sync_buddy_info *sbi;
  37         bool ping_received;
  38         struct list_head node;
  39 };
  40
  41 /* Allocated in ->open(), stored in fn->private_data */
  42 struct sync_filter_context {
  43         int listen_fd;
  44         struct list_head buddies;
  45         struct timeval timeout;
  46         bool ping_sent;
  47 };
  48
  49 #define FOR_EACH_BUDDY(_buddy, _list) \
  50         list_for_each_entry(_buddy, _list, node)
  51 #define FOR_EACH_BUDDY_SAFE(_buddy, _tmp_buddy, _list) \
  52         list_for_each_entry_safe(_buddy, _tmp_buddy, _list, node)
  53
  54 static void sync_close_buddy(struct sync_buddy *buddy)
  55 {
  56         PARA_DEBUG_LOG("closing %s, fd %d\n", buddy->sbi->url, buddy->fd);
  57         close(buddy->fd);
  58         list_del(&buddy->node);
  59         free(buddy);
  60 }
  61
  62 static void sync_close_buddies(struct sync_filter_context *ctx)
  63 {
  64         struct sync_buddy *buddy, *tmp;
  65
  66         FOR_EACH_BUDDY_SAFE(buddy, tmp, &ctx->buddies)
  67                 sync_close_buddy(buddy);
  68 }
  69
  70 static void sync_close(struct filter_node *fn)
  71 {
  72         struct sync_filter_context *ctx = fn->private_data;
  73
  74         sync_close_buddies(ctx);
  75         if (ctx->listen_fd >= 0) {
  76                 close(ctx->listen_fd);
  77                 ctx->listen_fd = -1;
  78         }
  79         free(ctx);
  80         fn->private_data = NULL;
  81 }
  82
  83 static void sync_teardown(const struct lls_parse_result *lpr, void *conf)
  84 {
  85         struct sync_buddy_info *sbi = conf;
  86         int i, num_buddies = FILTER_CMD_OPT_GIVEN(SYNC, BUDDY, lpr);
  87
  88         for (i = 0; i < num_buddies; i++) {
  89                 free(sbi[i].host);
  90                 freeaddrinfo(sbi[i].ai);
  91         }
  92         free(sbi);
  93 }
  94
  95 static void sync_open(struct filter_node *fn)
  96 {
  97         int i, ret;
  98         struct sync_buddy *buddy;
  99         struct sync_filter_context *ctx;
 100         struct sync_buddy_info *sbi = fn->conf;
 101         uint32_t port = FILTER_CMD_OPT_UINT32_VAL(SYNC, PORT, fn->lpr);
 102         unsigned buddy_given;
 103         const struct lls_opt_result *r_b;
 104
 105         ctx = fn->private_data = para_calloc(sizeof(*ctx));
 106         INIT_LIST_HEAD(&ctx->buddies);
 107
 108         /* create socket to listen for incoming packets */
 109         ret = makesock(
 110                 IPPROTO_UDP,
 111                 true /* passive */,
 112                 NULL /* no host required */,
 113                 port,
 114                 NULL /* no flowopts */
 115         );
 116         if (ret < 0) {
 117                 PARA_ERROR_LOG("could not create UDP listening socket %u\n",
 118                         port);
 119                 return;
 120         }
 121         ctx->listen_fd = ret;
 122         PARA_INFO_LOG("listening on fd %d\n", ctx->listen_fd);
 123
 124         r_b = FILTER_CMD_OPT_RESULT(SYNC, BUDDY, fn->lpr);
 125         buddy_given = lls_opt_given(r_b);
 126         for (i = 0; i < buddy_given; i++) {
 127                 int fd;
 128                 const char *url = lls_string_val(i, r_b);
 129
 130                 /* make buddy udp socket from address info */
 131                 assert(sbi->ai);
 132                 ret = makesock_addrinfo(
 133                         IPPROTO_UDP,
 134                         false /* not passive */,
 135                         sbi[i].ai,
 136                         NULL /* no flowopts */
 137                 );
 138                 if (ret < 0) {
 139                         PARA_WARNING_LOG("could not make socket for %s\n",
 140                                 url);
 141                         goto fail;
 142                 }
 143                 fd = ret;
 144                 ret = mark_fd_nonblocking(fd);
 145                 if (ret < 0) {
 146                         PARA_ERROR_LOG("unable to set nonblock mode for %s\n",
 147                                 url);
 148                         close(fd);
 149                         goto fail;
 150                 }
 151                 buddy = para_malloc(sizeof(*buddy));
 152                 buddy->fd = fd;
 153                 buddy->sbi = sbi + i;
 154                 buddy->ping_received = false;
 155                 para_list_add(&buddy->node, &ctx->buddies);
 156
 157                 PARA_INFO_LOG("opened buddy %s on fd %d\n", url, fd);
 158                 continue;
 159 fail:
 160                 PARA_WARNING_LOG("%s\n", para_strerror(-ret));
 161         }
 162 }
 163
 164 /*
 165  * Build an array of struct sync_buddy_info with one entry for each buddy given
 166  * in the arguments. This array is not affected by sync_close(), so information
 167  * stored there can be used for multiple instances (para_audiod). We store the
 168  * resolved url and the ->disabled bit in this array.
 169  */
 170 static void *sync_setup(const struct lls_parse_result *lpr)
 171 {
 172         int i, ret;
 173         unsigned n;
 174         struct sync_buddy_info *sbi;
 175         const struct lls_opt_result *r_b;
 176
 177         r_b = FILTER_CMD_OPT_RESULT(SYNC, BUDDY, lpr);
 178         n = lls_opt_given(r_b);
 179         sbi = para_malloc(n * sizeof(*sbi));
 180         PARA_INFO_LOG("initializing buddy info array of length %u\n", n);
 181         for (i = 0; i < n; i++) {
 182                 const char *url = lls_string_val(i, r_b);
 183                 size_t len = strlen(url);
 184                 char *host = para_malloc(len + 1);
 185                 int port;
 186                 struct addrinfo *ai;
 187
 188                 if (!parse_url(url, host, len, &port)) {
 189                         PARA_ERROR_LOG("could not parse url %s\n", url);
 190                         exit(EXIT_FAILURE);
 191                 }
 192                 if (port < 0)
 193                         port = FILTER_CMD_OPT_UINT32_VAL(SYNC, PORT, lpr);
 194                 ret = lookup_address(IPPROTO_UDP, false /* not passive */,
 195                         host, port, &ai);
 196                 if (ret < 0) {
 197                         PARA_ERROR_LOG("host lookup failure for %s: %s\n",
 198                                 url, para_strerror(-ret));
 199                         exit(EXIT_FAILURE);
 200                 }
 201                 sbi[i].url = url;
 202                 sbi[i].host = host;
 203                 sbi[i].port = port;
 204                 sbi[i].ai = ai;
 205                 sbi[i].disabled = false;
 206                 PARA_DEBUG_LOG("buddy #%d: %s\n", i, url);
 207         }
 208         return sbi;
 209 }
 210
 211 /*
 212  * True if we sent a packet to all buddies and received a packet from each
 213  * enabled buddy.
 214  */
 215 static bool sync_complete(struct sync_filter_context *ctx)
 216 {
 217         struct sync_buddy *buddy;
 218
 219         if (!ctx->ping_sent)
 220                 return false;
 221         FOR_EACH_BUDDY(buddy, &ctx->buddies)
 222                 if (!buddy->sbi->disabled && !buddy->ping_received)
 223                         return false;
 224         return true;
 225 }
 226
 227 static void sync_disable_active_buddies(struct sync_filter_context *ctx)
 228 {
 229         struct sync_buddy *buddy;
 230
 231         FOR_EACH_BUDDY(buddy, &ctx->buddies) {
 232                 if (buddy->sbi->disabled)
 233                         continue;
 234                 if (buddy->ping_received == true)
 235                         continue;
 236                 PARA_NOTICE_LOG("disabling %s\n", buddy->sbi->url);
 237                 buddy->sbi->disabled = true;
 238         }
 239 }
 240
 241 static void sync_set_timeout(struct sync_filter_context *ctx,
 242                 struct lls_parse_result *lpr)
 243 {
 244         uint32_t ms = FILTER_CMD_OPT_UINT32_VAL(SYNC, TIMEOUT, lpr);
 245         struct timeval to;
 246
 247         ms2tv(ms, &to);
 248         tv_add(now, &to, &ctx->timeout);
 249 }
 250
 251 static void sync_pre_select(struct sched *s, void *context)
 252 {
 253         int ret;
 254         struct filter_node *fn = context;
 255         struct sync_filter_context *ctx = fn->private_data;
 256
 257         if (list_empty(&ctx->buddies))
 258                 return sched_min_delay(s);
 259         if (ctx->listen_fd < 0)
 260                 return sched_min_delay(s);
 261         ret = btr_node_status(fn->btrn, 0, BTR_NT_INTERNAL);
 262         if (ret < 0)
 263                 return sched_min_delay(s);
 264         para_fd_set(ctx->listen_fd, &s->rfds, &s->max_fileno);
 265         if (ret == 0)
 266                 return;
 267         if (ctx->timeout.tv_sec == 0) { /* must ping buddies */
 268                 sync_set_timeout(ctx, fn->lpr);
 269                 return sched_min_delay(s);
 270         }
 271         if (sync_complete(ctx)) /* push down what we have */
 272                 return sched_min_delay(s);
 273         sched_request_barrier_or_min_delay(&ctx->timeout, s);
 274 }
 275
 276 static struct sync_buddy *sync_find_buddy(struct sockaddr *addr,
 277                 struct list_head *list)
 278 {
 279         struct sync_buddy *buddy;
 280
 281         FOR_EACH_BUDDY(buddy, list)
 282                 if (sockaddr_equal(buddy->sbi->ai->ai_addr, addr))
 283                         return buddy;
 284         return NULL;
 285 }
 286
 287 static int sync_post_select(__a_unused struct sched *s, void *context)
 288 {
 289         int ret;
 290         struct filter_node *fn = context;
 291         struct sync_filter_context *ctx = fn->private_data;
 292         struct sync_buddy *buddy, *tmp;
 293
 294         if (list_empty(&ctx->buddies))
 295                 goto success;
 296         ret = -E_SYNC_LISTEN_FD;
 297         if (ctx->listen_fd < 0)
 298                 goto fail;
 299         ret = btr_node_status(fn->btrn, 0, BTR_NT_INTERNAL);
 300         if (ret < 0)
 301                 goto fail;
 302         if (ret == 0)
 303                 return 0;
 304         if (ctx->timeout.tv_sec == 0)
 305                 sync_set_timeout(ctx, fn->lpr);
 306         else {
 307                 if (tv_diff(&ctx->timeout, now, NULL) < 0) {
 308                         sync_disable_active_buddies(ctx);
 309                         goto success;
 310                 }
 311         }
 312         if (!ctx->ping_sent) {
 313                 FOR_EACH_BUDDY_SAFE(buddy, tmp, &ctx->buddies) {
 314                         char c = '\0';
 315                         PARA_INFO_LOG("pinging %s (%s)\n",
 316                                 buddy->sbi->url, buddy->sbi->disabled?
 317                                 "disabled" : "enabled");
 318                         ret = xwrite(buddy->fd, &c, 1);
 319                         if (ret < 0) {
 320                                 PARA_WARNING_LOG("failed to write to %s: %s\n",
 321                                         buddy->sbi->url, para_strerror(-ret));
 322                                 sync_close_buddy(buddy);
 323                         }
 324                 }
 325                 ctx->ping_sent = true;
 326         }
 327         if (FD_ISSET(ctx->listen_fd, &s->rfds)) {
 328                 char c;
 329                 for (;;) {
 330                         struct sockaddr src_addr;
 331                         socklen_t len = sizeof(src_addr);
 332                         ret = recvfrom(ctx->listen_fd, &c, 1, MSG_DONTWAIT,
 333                                 &src_addr, &len);
 334                         if (ret < 0) {
 335                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 336                                         break;
 337                                 ret = -ERRNO_TO_PARA_ERROR(errno);
 338                                 goto fail;
 339                         }
 340                         buddy = sync_find_buddy(&src_addr, &ctx->buddies);
 341                         if (!buddy) {
 342                                 PARA_NOTICE_LOG("pinged by unknown\n");
 343                                 continue;
 344                         }
 345                         PARA_DEBUG_LOG("pinged by %s\n", buddy->sbi->url);
 346                         if (buddy->sbi->disabled) {
 347                                 PARA_NOTICE_LOG("enabling %s\n",
 348                                         buddy->sbi->url);
 349                                 buddy->sbi->disabled = false;
 350                         }
 351                         buddy->ping_received = true;
 352                 }
 353         }
 354         if (!sync_complete(ctx))
 355                 return 1;
 356         /*
 357          * Although all enabled buddies are in sync we do not splice out
 358          * ourselves immediately. We rather wait until the timeout expires,
 359          * or the buddy list has become empty. This opens a time window
 360          * for disabled buddies to become enabled by sending us a packet.
 361          */
 362         btr_pushdown(fn->btrn);
 363         return 1;
 364 success:
 365         ret = -E_SYNC_COMPLETE; /* success */
 366         goto out;
 367 fail:
 368         PARA_WARNING_LOG("%s\n", para_strerror(-ret));
 369 out:
 370         sync_close_buddies(ctx);
 371         btr_splice_out_node(&fn->btrn);
 372         assert(ret < 0);
 373         return ret;
 374 }
 375
 376 const struct filter lsg_filter_cmd_com_sync_user_data = {
 377         .setup = sync_setup,
 378         .open = sync_open,
 379         .pre_select = sync_pre_select,
 380         .post_select = sync_post_select,
 381         .close = sync_close,
 382         .teardown = sync_teardown
 383 };