lwsws/http.c

   1 /*
   2  * libwebsockets web server application
   3  *
   4  * Copyright (C) 2010-2016 Andy Green <andy@warmcat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU 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  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU 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 #include "lwsws.h"
  22
  23 /* http server gets files from this path */
  24 #define LOCAL_RESOURCE_PATH INSTALL_DATADIR"/libwebsockets-test-server"
  25 char *resource_path = LOCAL_RESOURCE_PATH;
  26
  27
  28
  29 /*
  30  * We take a strict whitelist approach to stop ../ attacks
  31  */
  32 struct serveable {
  33         const char *urlpath;
  34         const char *mimetype;
  35 };
  36
  37 const char * get_mimetype(const char *file)
  38 {
  39         int n = strlen(file);
  40
  41         if (n < 5)
  42                 return NULL;
  43
  44         if (!strcmp(&file[n - 4], ".ico"))
  45                 return "image/x-icon";
  46
  47         if (!strcmp(&file[n - 4], ".png"))
  48                 return "image/png";
  49
  50         if (!strcmp(&file[n - 4], ".jpg"))
  51                 return "image/jpeg";
  52
  53         if (!strcmp(&file[n - 5], ".html"))
  54                 return "text/html";
  55
  56         if (!strcmp(&file[n - 4], ".css"))
  57                 return "text/css";
  58
  59         return NULL;
  60 }
  61
  62 /* this protocol server (always the first one) handles HTTP,
  63  *
  64  * Some misc callbacks that aren't associated with a protocol also turn up only
  65  * here on the first protocol server.
  66  */
  67
  68 int callback_http(struct lws *wsi, enum lws_callback_reasons reason, void *user,
  69                   void *in, size_t len)
  70 {
  71         struct per_session_data__http *pss =
  72                         (struct per_session_data__http *)user;
  73         unsigned char buffer[4096 + LWS_PRE];
  74         unsigned long amount, file_len, sent;
  75         char leaf_path[1024];
  76         const char *mimetype;
  77         char *other_headers;
  78         unsigned char *end;
  79         struct timeval tv;
  80         unsigned char *p;
  81 #ifndef LWS_NO_CLIENT
  82         struct per_session_data__http *pss1;
  83         struct lws *wsi1;
  84 #endif
  85         char buf[256];
  86         char b64[64];
  87         int n, m;
  88 #ifdef EXTERNAL_POLL
  89         struct lws_pollargs *pa = (struct lws_pollargs *)in;
  90 #endif
  91
  92 //      lwsl_err("%s: reason %d\n", __func__, reason);
  93
  94         switch (reason) {
  95         case LWS_CALLBACK_HTTP:
  96
  97                 {
  98                         char name[100], rip[50];
  99                         lws_get_peer_addresses(wsi, lws_get_socket_fd(wsi), name,
 100                                                sizeof(name), rip, sizeof(rip));
 101                         sprintf(buf, "%s (%s)", name, rip);
 102                         lwsl_notice("HTTP connect from %s\n", buf);
 103                 }
 104
 105                 if (len < 1) {
 106                         lws_return_http_status(wsi,
 107                                                 HTTP_STATUS_BAD_REQUEST, NULL);
 108                         goto try_to_reuse;
 109                 }
 110
 111 #ifndef LWS_NO_CLIENT
 112                 if (!strncmp(in, "/proxytest", 10)) {
 113                         struct lws_client_connect_info i;
 114                         char *rootpath = "/";
 115                         const char *p = (const char *)in;
 116
 117                         if (lws_get_child(wsi))
 118                                 break;
 119
 120                         pss->client_finished = 0;
 121                         memset(&i,0, sizeof(i));
 122                         i.context = lws_get_context(wsi);
 123                         i.address = "git.libwebsockets.org";
 124                         i.port = 80;
 125                         i.ssl_connection = 0;
 126                         if (p[10])
 127                                 i.path = (char *)in + 10;
 128                         else
 129                                 i.path = rootpath;
 130                         i.host = "git.libwebsockets.org";
 131                         i.origin = NULL;
 132                         i.method = "GET";
 133                         i.parent_wsi = wsi;
 134                         i.uri_replace_from = "git.libwebsockets.org/";
 135                         i.uri_replace_to = "/proxytest/";
 136                         if (!lws_client_connect_via_info(&i)) {
 137                                 lwsl_err("proxy connect fail\n");
 138                                 break;
 139                         }
 140
 141
 142
 143                         break;
 144                 }
 145 #endif
 146
 147 #if 1
 148                 /* this example server has no concept of directories */
 149                 if (strchr((const char *)in + 1, '/')) {
 150                         lws_return_http_status(wsi, HTTP_STATUS_FORBIDDEN, NULL);
 151                         goto try_to_reuse;
 152                 }
 153 #endif
 154
 155                 /* if a legal POST URL, let it continue and accept data */
 156                 if (lws_hdr_total_length(wsi, WSI_TOKEN_POST_URI))
 157                         return 0;
 158
 159                 /* check for the "send a big file by hand" example case */
 160                 lwsl_notice("%s\n", in);
 161                 if (!strcmp((const char *)in, "/leaf.jpg")) {
 162                         if (strlen(resource_path) > sizeof(leaf_path) - 10)
 163                                 return -1;
 164                         sprintf(leaf_path, "%s/leaf.jpg", resource_path);
 165
 166                         /* well, let's demonstrate how to send the hard way */
 167
 168                         p = buffer + LWS_PRE;
 169                         end = p + sizeof(buffer) - LWS_PRE;
 170
 171                         pss->fd = lws_plat_file_open(wsi, leaf_path, &file_len,
 172                                                      LWS_O_RDONLY);
 173
 174                         if (pss->fd == LWS_INVALID_FILE) {
 175                                 lwsl_err("faild to open file %s\n", leaf_path);
 176                                 return -1;
 177                         }
 178
 179                         /*
 180                          * we will send a big jpeg file, but it could be
 181                          * anything.  Set the Content-Type: appropriately
 182                          * so the browser knows what to do with it.
 183                          *
 184                          * Notice we use the APIs to build the header, which
 185                          * will do the right thing for HTTP 1/1.1 and HTTP2
 186                          * depending on what connection it happens to be working
 187                          * on
 188                          */
 189                         if (lws_add_http_header_status(wsi, 200, &p, end))
 190                                 return 1;
 191                         if (lws_add_http_header_by_token(wsi, WSI_TOKEN_HTTP_SERVER,
 192                                         (unsigned char *)"libwebsockets",
 193                                         13, &p, end))
 194                                 return 1;
 195                         if (lws_add_http_header_by_token(wsi,
 196                                         WSI_TOKEN_HTTP_CONTENT_TYPE,
 197                                         (unsigned char *)"image/jpeg",
 198                                         10, &p, end))
 199                                 return 1;
 200                         if (lws_add_http_header_content_length(wsi,
 201                                                                file_len, &p,
 202                                                                end))
 203                                 return 1;
 204                         if (lws_finalize_http_header(wsi, &p, end))
 205                                 return 1;
 206
 207                         /*
 208                          * send the http headers...
 209                          * this won't block since it's the first payload sent
 210                          * on the connection since it was established
 211                          * (too small for partial)
 212                          *
 213                          * Notice they are sent using LWS_WRITE_HTTP_HEADERS
 214                          * which also means you can't send body too in one step,
 215                          * this is mandated by changes in HTTP2
 216                          */
 217
 218                         *p = '\0';
 219                         lwsl_info("%s\n", buffer + LWS_PRE);
 220
 221                         n = lws_write(wsi, buffer + LWS_PRE,
 222                                       p - (buffer + LWS_PRE),
 223                                       LWS_WRITE_HTTP_HEADERS);
 224                         if (n < 0) {
 225                                 lws_plat_file_close(wsi, pss->fd);
 226                                 return -1;
 227                         }
 228                         /*
 229                          * book us a LWS_CALLBACK_HTTP_WRITEABLE callback
 230                          */
 231                         lws_callback_on_writable(wsi);
 232                         break;
 233                 }
 234
 235                 /* if not, send a file the easy way */
 236                 if (!strncmp(in, "/cgit-data/", 11)) {
 237                         in = (char *)in + 11;
 238                         strcpy(buf, "/usr/share/cgit");
 239                 } else
 240                         strcpy(buf, resource_path);
 241
 242                 if (strcmp(in, "/")) {
 243                         if (*((const char *)in) != '/')
 244                                 strcat(buf, "/");
 245                         strncat(buf, in, sizeof(buf) - strlen(buf) - 1);
 246                 } else /* default file to serve */
 247                         strcat(buf, "/test.html");
 248                 buf[sizeof(buf) - 1] = '\0';
 249
 250                 /* refuse to serve files we don't understand */
 251                 mimetype = get_mimetype(buf);
 252                 if (!mimetype) {
 253                         lwsl_err("Unknown mimetype for %s\n", buf);
 254                         lws_return_http_status(wsi,
 255                                       HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE, NULL);
 256                         return -1;
 257                 }
 258
 259                 /* demonstrates how to set a cookie on / */
 260
 261                 other_headers = leaf_path;
 262                 p = (unsigned char *)leaf_path;
 263                 if (!strcmp((const char *)in, "/") &&
 264                            !lws_hdr_total_length(wsi, WSI_TOKEN_HTTP_COOKIE)) {
 265                         /* this isn't very unguessable but it'll do for us */
 266                         gettimeofday(&tv, NULL);
 267                         n = sprintf(b64, "test=LWS_%u_%u_COOKIE;Max-Age=360000",
 268                                 (unsigned int)tv.tv_sec,
 269                                 (unsigned int)tv.tv_usec);
 270
 271                         if (lws_add_http_header_by_name(wsi,
 272                                 (unsigned char *)"set-cookie:",
 273                                 (unsigned char *)b64, n, &p,
 274                                 (unsigned char *)leaf_path + sizeof(leaf_path)))
 275                                 return 1;
 276                 }
 277                 if (lws_is_ssl(wsi) && lws_add_http_header_by_name(wsi,
 278                                                 (unsigned char *)
 279                                                 "Strict-Transport-Security:",
 280                                                 (unsigned char *)
 281                                                 "max-age=15768000 ; "
 282                                                 "includeSubDomains", 36, &p,
 283                                                 (unsigned char *)leaf_path +
 284                                                         sizeof(leaf_path)))
 285                         return 1;
 286                 n = (char *)p - leaf_path;
 287
 288                 n = lws_serve_http_file(wsi, buf, mimetype, other_headers, n);
 289                 if (n < 0 || ((n > 0) && lws_http_transaction_completed(wsi)))
 290                         return -1; /* error or can't reuse connection: close the socket */
 291
 292                 /*
 293                  * notice that the sending of the file completes asynchronously,
 294                  * we'll get a LWS_CALLBACK_HTTP_FILE_COMPLETION callback when
 295                  * it's done
 296                  */
 297                 break;
 298
 299         case LWS_CALLBACK_HTTP_BODY:
 300                 strncpy(buf, in, 20);
 301                 buf[20] = '\0';
 302                 if (len < 20)
 303                         buf[len] = '\0';
 304
 305                 lwsl_notice("LWS_CALLBACK_HTTP_BODY: %s... len %d\n",
 306                                 (const char *)buf, (int)len);
 307
 308                 break;
 309
 310         case LWS_CALLBACK_HTTP_BODY_COMPLETION:
 311                 lwsl_notice("LWS_CALLBACK_HTTP_BODY_COMPLETION\n");
 312                 /* the whole of the sent body arrived, close or reuse the connection */
 313                 lws_return_http_status(wsi, HTTP_STATUS_OK, NULL);
 314                 goto try_to_reuse;
 315
 316         case LWS_CALLBACK_HTTP_FILE_COMPLETION:
 317                 goto try_to_reuse;
 318
 319         case LWS_CALLBACK_HTTP_WRITEABLE:
 320                 lwsl_info("LWS_CALLBACK_HTTP_WRITEABLE\n");
 321
 322                 if (pss->client_finished)
 323                         return -1;
 324
 325                 if (pss->fd == LWS_INVALID_FILE)
 326                         goto try_to_reuse;
 327 #ifdef LWS_WITH_CGI
 328                 if (pss->reason_bf & 1) {
 329                         if (lws_cgi_write_split_stdout_headers(wsi) < 0)
 330                                 goto bail;
 331
 332                         pss->reason_bf &= ~1;
 333                         break;
 334                 }
 335 #endif
 336 #ifndef LWS_NO_CLIENT
 337                 if (pss->reason_bf & 2) {
 338                         char *px = buf + LWS_PRE;
 339                         int lenx = sizeof(buf) - LWS_PRE;
 340                         /*
 341                          * our sink is writeable and our source has something
 342                          * to read.  So read a lump of source material of
 343                          * suitable size to send or what's available, whichever
 344                          * is the smaller.
 345                          */
 346                         pss->reason_bf &= ~2;
 347                         wsi1 = lws_get_child(wsi);
 348                         if (!wsi1)
 349                                 break;
 350                         if (lws_http_client_read(wsi1, &px, &lenx) < 0)
 351                                 goto bail;
 352
 353                         if (pss->client_finished)
 354                                 return -1;
 355                         break;
 356                 }
 357 #endif
 358                 /*
 359                  * we can send more of whatever it is we were sending
 360                  */
 361                 sent = 0;
 362                 do {
 363                         /* we'd like the send this much */
 364                         n = sizeof(buffer) - LWS_PRE;
 365
 366                         /* but if the peer told us he wants less, we can adapt */
 367                         m = lws_get_peer_write_allowance(wsi);
 368
 369                         /* -1 means not using a protocol that has this info */
 370                         if (m == 0)
 371                                 /* right now, peer can't handle anything */
 372                                 goto later;
 373
 374                         if (m != -1 && m < n)
 375                                 /* he couldn't handle that much */
 376                                 n = m;
 377
 378                         n = lws_plat_file_read(wsi, pss->fd,
 379                                                &amount, buffer + LWS_PRE, n);
 380                         /* problem reading, close conn */
 381                         if (n < 0) {
 382                                 lwsl_err("problem reading file\n");
 383                                 goto bail;
 384                         }
 385                         n = (int)amount;
 386                         /* sent it all, close conn */
 387                         if (n == 0)
 388                                 goto penultimate;
 389                         /*
 390                          * To support HTTP2, must take care about preamble space
 391                          *
 392                          * identification of when we send the last payload frame
 393                          * is handled by the library itself if you sent a
 394                          * content-length header
 395                          */
 396                         m = lws_write(wsi, buffer + LWS_PRE, n, LWS_WRITE_HTTP);
 397                         if (m < 0) {
 398                                 lwsl_err("write failed\n");
 399                                 /* write failed, close conn */
 400                                 goto bail;
 401                         }
 402                         if (m) /* while still active, extend timeout */
 403                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT, 5);
 404                         sent += m;
 405
 406                 } while (!lws_send_pipe_choked(wsi) && (sent < 1024 * 1024));
 407 later:
 408                 lws_callback_on_writable(wsi);
 409                 break;
 410 penultimate:
 411                 lws_plat_file_close(wsi, pss->fd);
 412                 pss->fd = LWS_INVALID_FILE;
 413                 goto try_to_reuse;
 414
 415 bail:
 416                 lws_plat_file_close(wsi, pss->fd);
 417
 418                 return -1;
 419
 420         /*
 421          * callback for confirming to continue with client IP appear in
 422          * protocol 0 callback since no websocket protocol has been agreed
 423          * yet.  You can just ignore this if you won't filter on client IP
 424          * since the default unhandled callback return is 0 meaning let the
 425          * connection continue.
 426          */
 427         case LWS_CALLBACK_FILTER_NETWORK_CONNECTION:
 428                 /* if we returned non-zero from here, we kill the connection */
 429                 break;
 430
 431 #ifndef LWS_NO_CLIENT
 432         case LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP: {
 433                 char ctype[64], ctlen = 0;
 434                 lwsl_err("LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP\n");
 435                 p = buffer + LWS_PRE;
 436                 end = p + sizeof(buffer) - LWS_PRE;
 437                 if (lws_add_http_header_status(lws_get_parent(wsi), 200, &p, end))
 438                         return 1;
 439                 if (lws_add_http_header_by_token(lws_get_parent(wsi),
 440                                 WSI_TOKEN_HTTP_SERVER,
 441                                 (unsigned char *)"libwebsockets",
 442                                 13, &p, end))
 443                         return 1;
 444
 445                 ctlen = lws_hdr_copy(wsi, ctype, sizeof(ctype), WSI_TOKEN_HTTP_CONTENT_TYPE);
 446                 if (ctlen > 0) {
 447                         if (lws_add_http_header_by_token(lws_get_parent(wsi),
 448                                 WSI_TOKEN_HTTP_CONTENT_TYPE,
 449                                 (unsigned char *)ctype, ctlen, &p, end))
 450                                 return 1;
 451                 }
 452 #if 0
 453                 if (lws_add_http_header_content_length(lws_get_parent(wsi),
 454                                                        file_len, &p, end))
 455                         return 1;
 456 #endif
 457                 if (lws_finalize_http_header(lws_get_parent(wsi), &p, end))
 458                         return 1;
 459
 460                 *p = '\0';
 461                 lwsl_info("%s\n", buffer + LWS_PRE);
 462
 463                 n = lws_write(lws_get_parent(wsi), buffer + LWS_PRE,
 464                               p - (buffer + LWS_PRE),
 465                               LWS_WRITE_HTTP_HEADERS);
 466                 if (n < 0)
 467                         return -1;
 468
 469                 break; }
 470         case LWS_CALLBACK_CLOSED_CLIENT_HTTP:
 471                 //lwsl_err("LWS_CALLBACK_CLOSED_CLIENT_HTTP\n");
 472                 return -1;
 473                 break;
 474         case LWS_CALLBACK_RECEIVE_CLIENT_HTTP:
 475                 //lwsl_err("LWS_CALLBACK_RECEIVE_CLIENT_HTTP: wsi %p\n", wsi);
 476                 assert(lws_get_parent(wsi));
 477                 if (!lws_get_parent(wsi))
 478                         break;
 479                 // lwsl_err("LWS_CALLBACK_RECEIVE_CLIENT_HTTP: wsi %p: sock: %d, parent_wsi: %p, parent_sock:%d,  len %d\n",
 480                 //              wsi, lws_get_socket_fd(wsi),
 481                 //              lws_get_parent(wsi),
 482                 //              lws_get_socket_fd(lws_get_parent(wsi)), len);
 483                 pss1 = lws_wsi_user(lws_get_parent(wsi));
 484                 pss1->reason_bf |= 2;
 485                 lws_callback_on_writable(lws_get_parent(wsi));
 486                 break;
 487         case LWS_CALLBACK_RECEIVE_CLIENT_HTTP_READ:
 488                 //lwsl_err("LWS_CALLBACK_RECEIVE_CLIENT_HTTP_READ len %d\n", len);
 489                 assert(lws_get_parent(wsi));
 490                 m = lws_write(lws_get_parent(wsi), (unsigned char *)in,
 491                                 len, LWS_WRITE_HTTP);
 492                 if (m < 0)
 493                         return -1;
 494                 break;
 495         case LWS_CALLBACK_COMPLETED_CLIENT_HTTP:
 496                 //lwsl_err("LWS_CALLBACK_COMPLETED_CLIENT_HTTP\n");
 497                 assert(lws_get_parent(wsi));
 498                 if (!lws_get_parent(wsi))
 499                         break;
 500                 pss1 = lws_wsi_user(lws_get_parent(wsi));
 501                 pss1->client_finished = 1;
 502                 break;
 503 #endif
 504
 505 #ifdef LWS_WITH_CGI
 506         /* CGI IO events (POLLIN/OUT) appear here our demo user code policy is
 507          *
 508          *  - POST data goes on subprocess stdin
 509          *  - subprocess stdout goes on http via writeable callback
 510          *  - subprocess stderr goes to the logs
 511          */
 512         case LWS_CALLBACK_CGI:
 513                 pss->args = *((struct lws_cgi_args *)in);
 514                 //lwsl_notice("LWS_CALLBACK_CGI: ch %d\n", pss->args.ch);
 515                 switch (pss->args.ch) { /* which of stdin/out/err ? */
 516                 case LWS_STDIN:
 517                         /* TBD stdin rx flow control */
 518                         break;
 519                 case LWS_STDOUT:
 520                         pss->reason_bf |= 1;
 521                         /* when writing to MASTER would not block */
 522                         lws_callback_on_writable(wsi);
 523                         break;
 524                 case LWS_STDERR:
 525                         n = read(lws_get_socket_fd(pss->args.stdwsi[LWS_STDERR]),
 526                                         buf, 127);
 527                         //lwsl_notice("stderr reads %d\n", n);
 528                         if (n > 0) {
 529                                 if (buf[n - 1] != '\n')
 530                                         buf[n++] = '\n';
 531                                 buf[n] = '\0';
 532                                 lwsl_notice("CGI-stderr: %s\n", buf);
 533                         }
 534                         break;
 535                 }
 536                 break;
 537
 538         case LWS_CALLBACK_CGI_TERMINATED:
 539                 //lwsl_notice("LWS_CALLBACK_CGI_TERMINATED\n");
 540                 /* because we sent on openended http, close the connection */
 541                 return -1;
 542
 543         case LWS_CALLBACK_CGI_STDIN_DATA:  /* POST body for stdin */
 544                 //lwsl_notice("LWS_CALLBACK_CGI_STDIN_DATA\n");
 545                 pss->args = *((struct lws_cgi_args *)in);
 546                 n = write(lws_get_socket_fd(pss->args.stdwsi[LWS_STDIN]),
 547                           pss->args.data, pss->args.len);
 548                 //lwsl_notice("LWS_CALLBACK_CGI_STDIN_DATA: write says %d", n);
 549                 if (n < pss->args.len)
 550                         lwsl_notice("LWS_CALLBACK_CGI_STDIN_DATA: sent %d only %d went",
 551                                         n, pss->args.len);
 552                 return n;
 553 #endif
 554
 555         /*
 556          * callbacks for managing the external poll() array appear in
 557          * protocol 0 callback
 558          */
 559
 560         case LWS_CALLBACK_LOCK_POLL:
 561                 /*
 562                  * lock mutex to protect pollfd state
 563                  * called before any other POLL related callback
 564                  * if protecting wsi lifecycle change, len == 1
 565                  */
 566                 test_server_lock(len);
 567                 break;
 568
 569         case LWS_CALLBACK_UNLOCK_POLL:
 570                 /*
 571                  * unlock mutex to protect pollfd state when
 572                  * called after any other POLL related callback
 573                  * if protecting wsi lifecycle change, len == 1
 574                  */
 575                 test_server_unlock(len);
 576                 break;
 577
 578 #ifdef EXTERNAL_POLL
 579         case LWS_CALLBACK_ADD_POLL_FD:
 580
 581                 if (count_pollfds >= max_poll_elements) {
 582                         lwsl_err("LWS_CALLBACK_ADD_POLL_FD: too many sockets to track\n");
 583                         return 1;
 584                 }
 585
 586                 fd_lookup[pa->fd] = count_pollfds;
 587                 pollfds[count_pollfds].fd = pa->fd;
 588                 pollfds[count_pollfds].events = pa->events;
 589                 pollfds[count_pollfds++].revents = 0;
 590                 break;
 591
 592         case LWS_CALLBACK_DEL_POLL_FD:
 593                 if (!--count_pollfds)
 594                         break;
 595                 m = fd_lookup[pa->fd];
 596                 /* have the last guy take up the vacant slot */
 597                 pollfds[m] = pollfds[count_pollfds];
 598                 fd_lookup[pollfds[count_pollfds].fd] = m;
 599                 break;
 600
 601         case LWS_CALLBACK_CHANGE_MODE_POLL_FD:
 602                 pollfds[fd_lookup[pa->fd]].events = pa->events;
 603                 break;
 604 #endif
 605
 606         case LWS_CALLBACK_GET_THREAD_ID:
 607                 /*
 608                  * if you will call "lws_callback_on_writable"
 609                  * from a different thread, return the caller thread ID
 610                  * here so lws can use this information to work out if it
 611                  * should signal the poll() loop to exit and restart early
 612                  */
 613
 614                 /* return pthread_getthreadid_np(); */
 615
 616                 break;
 617
 618         default:
 619                 break;
 620         }
 621
 622         return 0;
 623
 624         /* if we're on HTTP1.1 or 2.0, will keep the idle connection alive */
 625 try_to_reuse:
 626         if (lws_http_transaction_completed(wsi))
 627                 return -1;
 628
 629         return 0;
 630 }