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, lws_filepos_t len)
  64 {
  65         unsigned char *last_char, *oldbuf = buf;
  66         lws_filepos_t 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_HTTP_ISSUING_FILE:
  99                 return 0;
 100
 101         case LWSS_CLIENT_HTTP_ESTABLISHED:
 102                 break;
 103
 104         case LWSS_HTTP:
 105                 wsi->hdr_parsing_completed = 0;
 106                 /* fallthru */
 107
 108         case LWSS_HTTP_HEADERS:
 109                 if (!wsi->u.hdr.ah) {
 110                         lwsl_err("%s: LWSS_HTTP_HEADERS: NULL ah\n", __func__);
 111                         assert(0);
 112                 }
 113                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 114
 115                 if (lws_handshake_client(wsi, &buf, (size_t)len))
 116                         goto bail;
 117
 118                 last_char = buf;
 119                 if (lws_handshake_server(wsi, &buf, (size_t)len))
 120                         /* Handshake indicates this session is done. */
 121                         goto bail;
 122
 123                 /* we might have transitioned to RAW */
 124                 if (wsi->mode == LWSCM_RAW)
 125                          /* we gave the read buffer to RAW handler already */
 126                         goto read_ok;
 127
 128                 /*
 129                  * It's possible that we've exhausted our data already, or
 130                  * rx flow control has stopped us dealing with this early,
 131                  * but lws_handshake_server doesn't update len for us.
 132                  * Figure out how much was read, so that we can proceed
 133                  * appropriately:
 134                  */
 135                 len -= (buf - last_char);
 136                 lwsl_debug("%s: thinks we have used %ld\n", __func__, (long)len);
 137
 138                 if (!wsi->hdr_parsing_completed)
 139                         /* More header content on the way */
 140                         goto read_ok;
 141
 142                 switch (wsi->state) {
 143                         case LWSS_HTTP:
 144                         case LWSS_HTTP_HEADERS:
 145                                 goto read_ok;
 146                         case LWSS_HTTP_ISSUING_FILE:
 147                                 goto read_ok;
 148                         case LWSS_HTTP_BODY:
 149                                 wsi->u.http.content_remain =
 150                                                 wsi->u.http.content_length;
 151                                 if (wsi->u.http.content_remain)
 152                                         goto http_postbody;
 153
 154                                 /* there is no POST content */
 155                                 goto postbody_completion;
 156                         default:
 157                                 break;
 158                 }
 159                 break;
 160
 161         case LWSS_HTTP_BODY:
 162 http_postbody:
 163                 while (len && wsi->u.http.content_remain) {
 164                         /* Copy as much as possible, up to the limit of:
 165                          * what we have in the read buffer (len)
 166                          * remaining portion of the POST body (content_remain)
 167                          */
 168                         body_chunk_len = min(wsi->u.http.content_remain,len);
 169                         wsi->u.http.content_remain -= body_chunk_len;
 170                         len -= body_chunk_len;
 171 #ifdef LWS_WITH_CGI
 172                         if (wsi->cgi) {
 173                                 struct lws_cgi_args args;
 174
 175                                 args.ch = LWS_STDIN;
 176                                 args.stdwsi = &wsi->cgi->stdwsi[0];
 177                                 args.data = buf;
 178                                 args.len = body_chunk_len;
 179
 180                                 /* returns how much used */
 181                                 n = user_callback_handle_rxflow(
 182                                         wsi->protocol->callback,
 183                                         wsi, LWS_CALLBACK_CGI_STDIN_DATA,
 184                                         wsi->user_space,
 185                                         (void *)&args, 0);
 186                                 if ((int)n < 0)
 187                                         goto bail;
 188                         } else {
 189 #endif
 190                                 n = wsi->protocol->callback(wsi,
 191                                         LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 192                                         buf, (size_t)body_chunk_len);
 193                                 if (n)
 194                                         goto bail;
 195                                 n = (size_t)body_chunk_len;
 196 #ifdef LWS_WITH_CGI
 197                         }
 198 #endif
 199                         buf += n;
 200
 201                         if (wsi->u.http.content_remain)  {
 202                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 203                                                 wsi->context->timeout_secs);
 204                                 break;
 205                         }
 206                         /* he sent all the content in time */
 207 postbody_completion:
 208 #ifdef LWS_WITH_CGI
 209                         /* if we're running a cgi, we can't let him off the hook just because he sent his POST data */
 210                         if (wsi->cgi)
 211                                 lws_set_timeout(wsi, PENDING_TIMEOUT_CGI, wsi->context->timeout_secs);
 212                         else
 213 #endif
 214                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 215 #ifdef LWS_WITH_CGI
 216                         if (!wsi->cgi)
 217 #endif
 218                         {
 219                                 n = wsi->protocol->callback(wsi,
 220                                         LWS_CALLBACK_HTTP_BODY_COMPLETION,
 221                                         wsi->user_space, NULL, 0);
 222                                 if (n)
 223                                         goto bail;
 224                         }
 225
 226                         break;
 227                 }
 228                 break;
 229
 230         case LWSS_ESTABLISHED:
 231         case LWSS_AWAITING_CLOSE_ACK:
 232         case LWSS_SHUTDOWN:
 233                 if (lws_handshake_client(wsi, &buf, (size_t)len))
 234                         goto bail;
 235                 switch (wsi->mode) {
 236                 case LWSCM_WS_SERVING:
 237
 238                         if (lws_interpret_incoming_packet(wsi, &buf, (size_t)len) < 0) {
 239                                 lwsl_info("interpret_incoming_packet has bailed\n");
 240                                 goto bail;
 241                         }
 242                         break;
 243                 }
 244                 break;
 245         default:
 246                 lwsl_err("%s: Unhandled state %d\n", __func__, wsi->state);
 247                 break;
 248         }
 249
 250 read_ok:
 251         /* Nothing more to do for now */
 252         lwsl_info("%s: read_ok, used %ld\n", __func__, (long)(buf - oldbuf));
 253
 254         return buf - oldbuf;
 255
 256 bail:
 257         //lwsl_notice("closing connection at lws_read bail:\n");
 258         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 259
 260         return -1;
 261 }