lib/pollfd.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010-2014 Andy Green <andy@warmcat.com>
   5  *
   6  *  This library is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU Lesser General Public
   8  *  License as published by the Free Software Foundation:
   9  *  version 2.1 of the License.
  10  *
  11  *  This library is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  Lesser General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU Lesser General Public
  17  *  License along with this library; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  19  *  MA  02110-1301  USA
  20  */
  21
  22 #include "private-libwebsockets.h"
  23
  24 int
  25 insert_wsi_socket_into_fds(struct libwebsocket_context *context,
  26                                                        struct libwebsocket *wsi)
  27 {
  28         struct libwebsocket_pollargs pa = { wsi->sock, LWS_POLLIN, 0 };
  29
  30         if (context->fds_count >= context->max_fds) {
  31                 lwsl_err("Too many fds (%d)\n", context->max_fds);
  32                 return 1;
  33         }
  34
  35 #ifndef _WIN32
  36         if (wsi->sock >= context->max_fds) {
  37                 lwsl_err("Socket fd %d is too high (%d)\n",
  38                                                 wsi->sock, context->max_fds);
  39                 return 1;
  40         }
  41 #endif
  42
  43         assert(wsi);
  44         assert(wsi->sock >= 0);
  45
  46         lwsl_info("insert_wsi_socket_into_fds: wsi=%p, sock=%d, fds pos=%d\n",
  47                                             wsi, wsi->sock, context->fds_count);
  48
  49         context->protocols[0].callback(context, wsi,
  50                 LWS_CALLBACK_LOCK_POLL,
  51                 wsi->user_space, (void *) &pa, 0);
  52
  53         insert_wsi(context, wsi);
  54         wsi->position_in_fds_table = context->fds_count;
  55         context->fds[context->fds_count].fd = wsi->sock;
  56         context->fds[context->fds_count].events = LWS_POLLIN;
  57
  58         lws_plat_insert_socket_into_fds(context, wsi);
  59
  60         /* external POLL support via protocol 0 */
  61         context->protocols[0].callback(context, wsi,
  62                 LWS_CALLBACK_ADD_POLL_FD,
  63                 wsi->user_space, (void *) &pa, 0);
  64
  65         context->protocols[0].callback(context, wsi,
  66                 LWS_CALLBACK_UNLOCK_POLL,
  67                 wsi->user_space, (void *)&pa, 0);
  68
  69         return 0;
  70 }
  71
  72 int
  73 remove_wsi_socket_from_fds(struct libwebsocket_context *context,
  74                                                       struct libwebsocket *wsi)
  75 {
  76         int m;
  77         struct libwebsocket_pollargs pa = { wsi->sock, 0, 0 };
  78
  79         lws_libev_io(context, wsi, LWS_EV_STOP | LWS_EV_READ | LWS_EV_WRITE);
  80
  81         if (!--context->fds_count) {
  82                 context->protocols[0].callback(context, wsi,
  83                         LWS_CALLBACK_LOCK_POLL,
  84                         wsi->user_space, (void *) &pa, 0);
  85                 goto do_ext;
  86         }
  87
  88         if (wsi->sock > context->max_fds) {
  89                 lwsl_err("Socket fd %d too high (%d)\n",
  90                                                    wsi->sock, context->max_fds);
  91                 return 1;
  92         }
  93
  94         lwsl_info("%s: wsi=%p, sock=%d, fds pos=%d\n", __func__,
  95                                     wsi, wsi->sock, wsi->position_in_fds_table);
  96
  97         context->protocols[0].callback(context, wsi,
  98                 LWS_CALLBACK_LOCK_POLL,
  99                 wsi->user_space, (void *)&pa, 0);
 100
 101         m = wsi->position_in_fds_table; /* replace the contents for this */
 102
 103         /* have the last guy take up the vacant slot */
 104         context->fds[m] = context->fds[context->fds_count];
 105
 106         lws_plat_delete_socket_from_fds(context, wsi, m);
 107
 108         /*
 109          * end guy's fds_lookup entry remains unchanged
 110          * (still same fd pointing to same wsi)
 111          */
 112         /* end guy's "position in fds table" changed */
 113         wsi_from_fd(context,context->fds[context->fds_count].fd)->
 114                                         position_in_fds_table = m;
 115         /* deletion guy's lws_lookup entry needs nuking */
 116         delete_from_fd(context,wsi->sock);
 117         /* removed wsi has no position any more */
 118         wsi->position_in_fds_table = -1;
 119
 120 do_ext:
 121         /* remove also from external POLL support via protocol 0 */
 122         if (wsi->sock) {
 123                 context->protocols[0].callback(context, wsi,
 124                     LWS_CALLBACK_DEL_POLL_FD, wsi->user_space,
 125                     (void *) &pa, 0);
 126         }
 127         context->protocols[0].callback(context, wsi,
 128                                        LWS_CALLBACK_UNLOCK_POLL,
 129                                        wsi->user_space, (void *) &pa, 0);
 130         return 0;
 131 }
 132
 133 int
 134 lws_change_pollfd(struct libwebsocket *wsi, int _and, int _or)
 135 {
 136         struct libwebsocket_context *context;
 137         int tid;
 138         int sampled_tid;
 139         struct libwebsocket_pollfd *pfd;
 140         struct libwebsocket_pollargs pa;
 141
 142         if (!wsi || !wsi->protocol || wsi->position_in_fds_table < 0)
 143                 return 1;
 144
 145         context = wsi->protocol->owning_server;
 146         if (!context)
 147                 return 1;
 148
 149         pfd = &context->fds[wsi->position_in_fds_table];
 150         pa.fd = wsi->sock;
 151
 152         context->protocols[0].callback(context, wsi,
 153                 LWS_CALLBACK_LOCK_POLL, wsi->user_space,  (void *) &pa, 0);
 154
 155         pa.prev_events = pfd->events;
 156         pa.events = pfd->events = (pfd->events & ~_and) | _or;
 157
 158         context->protocols[0].callback(context, wsi,
 159                         LWS_CALLBACK_CHANGE_MODE_POLL_FD,
 160                                 wsi->user_space, (void *) &pa, 0);
 161
 162         /*
 163          * if we changed something in this pollfd...
 164          *   ... and we're running in a different thread context
 165          *     than the service thread...
 166          *       ... and the service thread is waiting ...
 167          *         then cancel it to force a restart with our changed events
 168          */
 169         if (pa.prev_events != pa.events) {
 170
 171                 if (lws_plat_change_pollfd(context, wsi, pfd)) {
 172                         lwsl_info("%s failed\n", __func__);
 173                         return 1;
 174                 }
 175
 176                 sampled_tid = context->service_tid;
 177                 if (sampled_tid) {
 178                         tid = context->protocols[0].callback(context, NULL,
 179                                      LWS_CALLBACK_GET_THREAD_ID, NULL, NULL, 0);
 180                         if (tid != sampled_tid)
 181                                 libwebsocket_cancel_service(context);
 182                 }
 183         }
 184
 185         context->protocols[0].callback(context, wsi,
 186                 LWS_CALLBACK_UNLOCK_POLL, wsi->user_space, (void *) &pa, 0);
 187
 188         return 0;
 189 }
 190
 191
 192 /**
 193  * libwebsocket_callback_on_writable() - Request a callback when this socket
 194  *                                       becomes able to be written to without
 195  *                                       blocking
 196  *
 197  * @context:    libwebsockets context
 198  * @wsi:        Websocket connection instance to get callback for
 199  */
 200
 201 LWS_VISIBLE int
 202 libwebsocket_callback_on_writable(struct libwebsocket_context *context,
 203                                                       struct libwebsocket *wsi)
 204 {
 205 #ifdef LWS_USE_HTTP2
 206         struct libwebsocket *network_wsi, *wsi2;
 207         int already;
 208
 209         lwsl_info("%s: %p\n", __func__, wsi);
 210
 211         if (wsi->mode != LWS_CONNMODE_HTTP2_SERVING)
 212                 goto network_sock;
 213
 214         if (wsi->u.http2.requested_POLLOUT) {
 215                 lwsl_info("already pending writable\n");
 216                 return 1;
 217         }
 218
 219         if (wsi->u.http2.tx_credit <= 0) {
 220                 /*
 221                  * other side is not able to cope with us sending
 222                  * anything so no matter if we have POLLOUT on our side.
 223                  *
 224                  * Delay waiting for our POLLOUT until peer indicates he has
 225                  * space for more using tx window command in http2 layer
 226                  */
 227                 lwsl_info("%s: %p: waiting_tx_credit (%d)\n", __func__, wsi, wsi->u.http2.tx_credit);
 228                 wsi->u.http2.waiting_tx_credit = 1;
 229                 return 0;
 230         }
 231
 232         network_wsi = lws_http2_get_network_wsi(wsi);
 233         already = network_wsi->u.http2.requested_POLLOUT;
 234
 235         /* mark everybody above him as requesting pollout */
 236
 237         wsi2 = wsi;
 238         while (wsi2) {
 239                 wsi2->u.http2.requested_POLLOUT = 1;
 240                 lwsl_info("mark %p pending writable\n", wsi2);
 241                 wsi2 = wsi2->u.http2.parent_wsi;
 242         }
 243
 244         /* for network action, act only on the network wsi */
 245
 246         wsi = network_wsi;
 247         if (already)
 248                 return 1;
 249 network_sock:
 250 #endif
 251
 252         if (lws_ext_callback_for_each_active(wsi,
 253                                 LWS_EXT_CALLBACK_REQUEST_ON_WRITEABLE, NULL, 0))
 254                 return 1;
 255
 256         if (wsi->position_in_fds_table < 0) {
 257                 lwsl_err("%s: failed to find socket %d\n", __func__, wsi->sock);
 258                 return -1;
 259         }
 260
 261         if (lws_change_pollfd(wsi, 0, LWS_POLLOUT))
 262                 return -1;
 263
 264         lws_libev_io(context, wsi, LWS_EV_START | LWS_EV_WRITE);
 265
 266         return 1;
 267 }
 268
 269 /**
 270  * libwebsocket_callback_on_writable_all_protocol() - Request a callback for
 271  *                      all connections using the given protocol when it
 272  *                      becomes possible to write to each socket without
 273  *                      blocking in turn.
 274  *
 275  * @protocol:   Protocol whose connections will get callbacks
 276  */
 277
 278 LWS_VISIBLE int
 279 libwebsocket_callback_on_writable_all_protocol(
 280                                   const struct libwebsocket_protocols *protocol)
 281 {
 282         struct libwebsocket_context *context = protocol->owning_server;
 283         int n;
 284         struct libwebsocket *wsi;
 285
 286         for (n = 0; n < context->fds_count; n++) {
 287                 wsi = wsi_from_fd(context,context->fds[n].fd);
 288                 if (!wsi)
 289                         continue;
 290                 if (wsi->protocol == protocol)
 291                         libwebsocket_callback_on_writable(context, wsi);
 292         }
 293
 294         return 0;
 295 }