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         --context->fds_count;
  82
  83         if (wsi->sock > context->max_fds) {
  84                 lwsl_err("Socket fd %d too high (%d)\n",
  85                                                    wsi->sock, context->max_fds);
  86                 return 1;
  87         }
  88
  89         lwsl_info("%s: wsi=%p, sock=%d, fds pos=%d\n", __func__,
  90                                     wsi, wsi->sock, wsi->position_in_fds_table);
  91
  92         context->protocols[0].callback(context, wsi,
  93                 LWS_CALLBACK_LOCK_POLL,
  94                 wsi->user_space, (void *)&pa, 0);
  95
  96         m = wsi->position_in_fds_table; /* replace the contents for this */
  97
  98         /* have the last guy take up the vacant slot */
  99         context->fds[m] = context->fds[context->fds_count];
 100
 101         lws_plat_delete_socket_from_fds(context, wsi, m);
 102
 103         /*
 104          * end guy's fds_lookup entry remains unchanged
 105          * (still same fd pointing to same wsi)
 106          */
 107         /* end guy's "position in fds table" changed */
 108         wsi_from_fd(context,context->fds[context->fds_count].fd)->
 109                                         position_in_fds_table = m;
 110         /* deletion guy's lws_lookup entry needs nuking */
 111         delete_from_fd(context,wsi->sock);
 112         /* removed wsi has no position any more */
 113         wsi->position_in_fds_table = -1;
 114
 115         /* remove also from external POLL support via protocol 0 */
 116         if (wsi->sock) {
 117                 context->protocols[0].callback(context, wsi,
 118                     LWS_CALLBACK_DEL_POLL_FD, wsi->user_space,
 119                     (void *) &pa, 0);
 120         }
 121         context->protocols[0].callback(context, wsi,
 122                                        LWS_CALLBACK_UNLOCK_POLL,
 123                                        wsi->user_space, (void *) &pa, 0);
 124         return 0;
 125 }
 126
 127 int
 128 lws_change_pollfd(struct libwebsocket *wsi, int _and, int _or)
 129 {
 130         struct libwebsocket_context *context;
 131         int tid;
 132         int sampled_tid;
 133         struct libwebsocket_pollfd *pfd;
 134         struct libwebsocket_pollargs pa;
 135
 136         if (!wsi || !wsi->protocol || wsi->position_in_fds_table < 0)
 137                 return 1;
 138
 139         context = wsi->protocol->owning_server;
 140         if (!context)
 141                 return 1;
 142
 143         pfd = &context->fds[wsi->position_in_fds_table];
 144         pa.fd = wsi->sock;
 145
 146         context->protocols[0].callback(context, wsi,
 147                 LWS_CALLBACK_LOCK_POLL, wsi->user_space,  (void *) &pa, 0);
 148
 149         pa.prev_events = pfd->events;
 150         pa.events = pfd->events = (pfd->events & ~_and) | _or;
 151
 152         context->protocols[0].callback(context, wsi,
 153                         LWS_CALLBACK_CHANGE_MODE_POLL_FD,
 154                                 wsi->user_space, (void *) &pa, 0);
 155
 156         /*
 157          * if we changed something in this pollfd...
 158          *   ... and we're running in a different thread context
 159          *     than the service thread...
 160          *       ... and the service thread is waiting ...
 161          *         then cancel it to force a restart with our changed events
 162          */
 163         if (pa.prev_events != pa.events) {
 164
 165                 if (lws_plat_change_pollfd(context, wsi, pfd)) {
 166                         lwsl_info("%s failed\n", __func__);
 167                         return 1;
 168                 }
 169
 170                 sampled_tid = context->service_tid;
 171                 if (sampled_tid) {
 172                         tid = context->protocols[0].callback(context, NULL,
 173                                      LWS_CALLBACK_GET_THREAD_ID, NULL, NULL, 0);
 174                         if (tid != sampled_tid)
 175                                 libwebsocket_cancel_service(context);
 176                 }
 177         }
 178
 179         context->protocols[0].callback(context, wsi,
 180                 LWS_CALLBACK_UNLOCK_POLL, wsi->user_space, (void *) &pa, 0);
 181
 182         return 0;
 183 }
 184
 185
 186 /**
 187  * libwebsocket_callback_on_writable() - Request a callback when this socket
 188  *                                       becomes able to be written to without
 189  *                                       blocking
 190  *
 191  * @context:    libwebsockets context
 192  * @wsi:        Websocket connection instance to get callback for
 193  */
 194
 195 LWS_VISIBLE int
 196 libwebsocket_callback_on_writable(struct libwebsocket_context *context,
 197                                                       struct libwebsocket *wsi)
 198 {
 199 #ifdef LWS_USE_HTTP2
 200         struct libwebsocket *network_wsi, *wsi2;
 201         int already;
 202
 203         lwsl_info("%s: %p\n", __func__, wsi);
 204
 205         if (wsi->mode != LWS_CONNMODE_HTTP2_SERVING)
 206                 goto network_sock;
 207
 208         if (wsi->u.http2.requested_POLLOUT) {
 209                 lwsl_info("already pending writable\n");
 210                 return 1;
 211         }
 212
 213         if (wsi->u.http2.tx_credit <= 0) {
 214                 /*
 215                  * other side is not able to cope with us sending
 216                  * anything so no matter if we have POLLOUT on our side.
 217                  *
 218                  * Delay waiting for our POLLOUT until peer indicates he has
 219                  * space for more using tx window command in http2 layer
 220                  */
 221                 lwsl_info("%s: %p: waiting_tx_credit (%d)\n", __func__, wsi, wsi->u.http2.tx_credit);
 222                 wsi->u.http2.waiting_tx_credit = 1;
 223                 return 0;
 224         }
 225
 226         network_wsi = lws_http2_get_network_wsi(wsi);
 227         already = network_wsi->u.http2.requested_POLLOUT;
 228
 229         /* mark everybody above him as requesting pollout */
 230
 231         wsi2 = wsi;
 232         while (wsi2) {
 233                 wsi2->u.http2.requested_POLLOUT = 1;
 234                 lwsl_info("mark %p pending writable\n", wsi2);
 235                 wsi2 = wsi2->u.http2.parent_wsi;
 236         }
 237
 238         /* for network action, act only on the network wsi */
 239
 240         wsi = network_wsi;
 241         if (already)
 242                 return 1;
 243 network_sock:
 244 #endif
 245
 246         if (lws_ext_callback_for_each_active(wsi,
 247                                 LWS_EXT_CALLBACK_REQUEST_ON_WRITEABLE, NULL, 0))
 248                 return 1;
 249
 250         if (wsi->position_in_fds_table < 0) {
 251                 lwsl_err("%s: failed to find socket %d\n", __func__, wsi->sock);
 252                 return -1;
 253         }
 254
 255         if (lws_change_pollfd(wsi, 0, LWS_POLLOUT))
 256                 return -1;
 257
 258         lws_libev_io(context, wsi, LWS_EV_START | LWS_EV_WRITE);
 259
 260         return 1;
 261 }
 262
 263 /**
 264  * libwebsocket_callback_on_writable_all_protocol() - Request a callback for
 265  *                      all connections using the given protocol when it
 266  *                      becomes possible to write to each socket without
 267  *                      blocking in turn.
 268  *
 269  * @protocol:   Protocol whose connections will get callbacks
 270  */
 271
 272 LWS_VISIBLE int
 273 libwebsocket_callback_on_writable_all_protocol(
 274                                   const struct libwebsocket_protocols *protocol)
 275 {
 276         struct libwebsocket_context *context = protocol->owning_server;
 277         int n;
 278         struct libwebsocket *wsi;
 279
 280         for (n = 0; n < context->fds_count; n++) {
 281                 wsi = wsi_from_fd(context,context->fds[n].fd);
 282                 if (!wsi)
 283                         continue;
 284                 if (wsi->protocol == protocol)
 285                         libwebsocket_callback_on_writable(context, wsi);
 286         }
 287
 288         return 0;
 289 }