lib/handshake.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010-2015 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 /*
  25  * -04 of the protocol (actually the 80th version) has a radically different
  26  * handshake.  The 04 spec gives the following idea
  27  *
  28  *    The handshake from the client looks as follows:
  29  *
  30  *      GET /chat HTTP/1.1
  31  *      Host: server.example.com
  32  *      Upgrade: websocket
  33  *      Connection: Upgrade
  34  *      Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
  35  *      Sec-WebSocket-Origin: http://example.com
  36  *      Sec-WebSocket-Protocol: chat, superchat
  37  *      Sec-WebSocket-Version: 4
  38  *
  39  *  The handshake from the server looks as follows:
  40  *
  41  *       HTTP/1.1 101 Switching Protocols
  42  *       Upgrade: websocket
  43  *       Connection: Upgrade
  44  *       Sec-WebSocket-Accept: me89jWimTRKTWwrS3aRrL53YZSo=
  45  *       Sec-WebSocket-Nonce: AQIDBAUGBwgJCgsMDQ4PEC==
  46  *       Sec-WebSocket-Protocol: chat
  47  */
  48
  49 #ifndef min
  50 #define min(a, b) ((a) < (b) ? (a) : (b))
  51 #endif
  52
  53 /*
  54  * We have to take care about parsing because the headers may be split
  55  * into multiple fragments.  They may contain unknown headers with arbitrary
  56  * argument lengths.  So, we parse using a single-character at a time state
  57  * machine that is completely independent of packet size.
  58  *
  59  * Returns <0 for error or length of chars consumed from buf (up to len)
  60  */
  61
  62 LWS_VISIBLE int
  63 lws_read(struct lws *wsi, unsigned char *buf, size_t len)
  64 {
  65         unsigned char *last_char, *oldbuf = buf;
  66         int body_chunk_len;
  67         size_t n;
  68
  69         lwsl_debug("%s: incoming len %d  state %d\n", __func__, (int)len, wsi->state);
  70
  71         switch (wsi->state) {
  72 #ifdef LWS_USE_HTTP2
  73         case LWSS_HTTP2_AWAIT_CLIENT_PREFACE:
  74         case LWSS_HTTP2_ESTABLISHED_PRE_SETTINGS:
  75         case LWSS_HTTP2_ESTABLISHED:
  76                 n = 0;
  77                 while (n < len) {
  78                         /*
  79                          * we were accepting input but now we stopped doing so
  80                          */
  81                         if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
  82                                 lws_rxflow_cache(wsi, buf, n, len);
  83
  84                                 return 1;
  85                         }
  86
  87                         /* account for what we're using in rxflow buffer */
  88                         if (wsi->rxflow_buffer)
  89                                 wsi->rxflow_pos++;
  90                         if (lws_http2_parser(wsi, buf[n++])) {
  91                                 lwsl_debug("%s: http2_parser bailed\n", __func__);
  92                                 goto bail;
  93                         }
  94                 }
  95                 break;
  96 #endif
  97
  98         case LWSS_CLIENT_HTTP_ESTABLISHED:
  99                 break;
 100
 101         case LWSS_HTTP:
 102                 wsi->hdr_parsing_completed = 0;
 103                 /* fallthru */
 104         case LWSS_HTTP_ISSUING_FILE:
 105                 wsi->state = LWSS_HTTP_HEADERS;
 106                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
 107                 wsi->u.hdr.lextable_pos = 0;
 108                 /* fallthru */
 109         case LWSS_HTTP_HEADERS:
 110
 111                 assert(wsi->u.hdr.ah);
 112                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 113
 114                 if (lws_handshake_client(wsi, &buf, len))
 115                         goto bail;
 116
 117                 last_char = buf;
 118                 if (lws_handshake_server(wsi, &buf, len))
 119                         /* Handshake indicates this session is done. */
 120                         goto bail;
 121
 122                 /*
 123                  * It's possible that we've exhausted our data already, or
 124                  * rx flow control has stopped us dealing with this early,
 125                  * but lws_handshake_server doesn't update len for us.
 126                  * Figure out how much was read, so that we can proceed
 127                  * appropriately:
 128                  */
 129                 len -= (buf - last_char);
 130                 lwsl_debug("%s: thinks we have used %d\n", __func__, len);
 131
 132                 if (!wsi->hdr_parsing_completed)
 133                         /* More header content on the way */
 134                         goto read_ok;
 135
 136                 switch (wsi->state) {
 137                         case LWSS_HTTP:
 138                         case LWSS_HTTP_HEADERS:
 139                                 goto read_ok;
 140                         case LWSS_HTTP_ISSUING_FILE:
 141                                 goto read_ok;
 142                         case LWSS_HTTP_BODY:
 143                                 wsi->u.http.content_remain =
 144                                                 wsi->u.http.content_length;
 145                                 if (wsi->u.http.content_remain)
 146                                         goto http_postbody;
 147
 148                                 /* there is no POST content */
 149                                 goto postbody_completion;
 150                         default:
 151                                 break;
 152                 }
 153                 break;
 154
 155         case LWSS_HTTP_BODY:
 156 http_postbody:
 157                 while (len && wsi->u.http.content_remain) {
 158                         /* Copy as much as possible, up to the limit of:
 159                          * what we have in the read buffer (len)
 160                          * remaining portion of the POST body (content_remain)
 161                          */
 162                         body_chunk_len = min(wsi->u.http.content_remain,len);
 163                         wsi->u.http.content_remain -= body_chunk_len;
 164                         len -= body_chunk_len;
 165 #ifdef LWS_WITH_CGI
 166                         if (wsi->cgi) {
 167                                 struct lws_cgi_args args;
 168
 169                                 args.ch = LWS_STDIN;
 170                                 args.stdwsi = &wsi->cgi->stdwsi[0];
 171                                 args.data = buf;
 172                                 args.len = body_chunk_len;
 173
 174                                 /* returns how much used */
 175                                 n = user_callback_handle_rxflow(
 176                                         wsi->protocol->callback,
 177                                         wsi, LWS_CALLBACK_CGI_STDIN_DATA,
 178                                         wsi->user_space,
 179                                         (void *)&args, 0);
 180                                 if ((int)n < 0)
 181                                         goto bail;
 182                         } else {
 183 #endif
 184                                 n = wsi->protocol->callback(wsi,
 185                                         LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 186                                         buf, body_chunk_len);
 187                                 if (n)
 188                                         goto bail;
 189                                 n = body_chunk_len;
 190 #ifdef LWS_WITH_CGI
 191                         }
 192 #endif
 193                         buf += n;
 194
 195                         if (wsi->u.http.content_remain)  {
 196                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 197                                                 wsi->context->timeout_secs);
 198                                 break;
 199                         }
 200                         /* he sent all the content in time */
 201 postbody_completion:
 202                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 203 #ifdef LWS_WITH_CGI
 204                         if (!wsi->cgi)
 205 #endif
 206                         {
 207                                 n = wsi->protocol->callback(wsi,
 208                                         LWS_CALLBACK_HTTP_BODY_COMPLETION,
 209                                         wsi->user_space, NULL, 0);
 210                                 if (n)
 211                                         goto bail;
 212                         }
 213
 214                         goto http_complete;
 215                 }
 216                 break;
 217
 218         case LWSS_ESTABLISHED:
 219         case LWSS_AWAITING_CLOSE_ACK:
 220         case LWSS_SHUTDOWN:
 221                 if (lws_handshake_client(wsi, &buf, len))
 222                         goto bail;
 223                 switch (wsi->mode) {
 224                 case LWSCM_WS_SERVING:
 225
 226                         if (lws_interpret_incoming_packet(wsi, &buf, len) < 0) {
 227                                 lwsl_info("interpret_incoming_packet has bailed\n");
 228                                 goto bail;
 229                         }
 230                         break;
 231                 }
 232                 break;
 233         default:
 234                 lwsl_err("%s: Unhandled state %d\n", __func__, wsi->state);
 235                 break;
 236         }
 237
 238 read_ok:
 239         /* Nothing more to do for now */
 240         lwsl_info("%s: read_ok, used %d\n", __func__, buf - oldbuf);
 241
 242         return buf - oldbuf;
 243
 244 http_complete:
 245         lwsl_debug("%s: http_complete\n", __func__);
 246
 247 #ifndef LWS_NO_SERVER
 248         /* Did the client want to keep the HTTP connection going? */
 249         if (lws_http_transaction_completed(wsi))
 250                 goto bail;
 251 #endif
 252         /* we may have next header set already, but return to event loop first
 253          * so a heaily-pipelined http/1.1 connection cannot monopolize the
 254          * service thread with GET hugefile.bin GET hugefile.bin etc
 255          */
 256         goto read_ok;
 257
 258 bail:
 259         lwsl_debug("closing connection at lws_read bail:\n");
 260         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 261
 262         return -1;
 263 }