lib/handshake.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010-2013 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  * We have to take care about parsing because the headers may be split
  54  * into multiple fragments.  They may contain unknown headers with arbitrary
  55  * argument lengths.  So, we parse using a single-character at a time state
  56  * machine that is completely independent of packet size.
  57  */
  58
  59 LWS_VISIBLE int
  60 lws_read(struct lws_context *context,
  61          struct lws *wsi, unsigned char *buf, size_t len)
  62 {
  63         size_t n;
  64         int body_chunk_len;
  65         unsigned char *last_char;
  66
  67         switch (wsi->state) {
  68 #ifdef LWS_USE_HTTP2
  69         case WSI_STATE_HTTP2_AWAIT_CLIENT_PREFACE:
  70         case WSI_STATE_HTTP2_ESTABLISHED_PRE_SETTINGS:
  71         case WSI_STATE_HTTP2_ESTABLISHED:
  72                 n = 0;
  73                 while (n < len) {
  74                         /*
  75                          * we were accepting input but now we stopped doing so
  76                          */
  77                         if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
  78                                 lws_rxflow_cache(wsi, buf, n, len);
  79
  80                                 return 1;
  81                         }
  82
  83                         /* account for what we're using in rxflow buffer */
  84                         if (wsi->rxflow_buffer)
  85                                 wsi->rxflow_pos++;
  86                         if (lws_http2_parser(context, wsi, buf[n++]))
  87                                 goto bail;
  88                 }
  89                 break;
  90 #endif
  91 http_new:
  92         case WSI_STATE_HTTP:
  93                 wsi->hdr_parsing_completed = 0;
  94                 /* fallthru */
  95         case WSI_STATE_HTTP_ISSUING_FILE:
  96                 wsi->state = WSI_STATE_HTTP_HEADERS;
  97                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
  98                 wsi->u.hdr.lextable_pos = 0;
  99                 /* fallthru */
 100         case WSI_STATE_HTTP_HEADERS:
 101                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 102
 103                 if (lws_handshake_client(wsi, &buf, len))
 104                         goto bail;
 105
 106                 last_char = buf;
 107                 if (lws_handshake_server(context, wsi, &buf, len))
 108                         /* Handshake indicates this session is done. */
 109                         goto bail;
 110
 111                 /* It's possible that we've exhausted our data already, but
 112                  * lws_handshake_server doesn't update len for us. Figure out how
 113                  * much was read, so that we can proceed appropriately: */
 114                 len -= (buf - last_char);
 115
 116                 if (!wsi->hdr_parsing_completed)
 117                         /* More header content on the way */
 118                         goto read_ok;
 119
 120                 switch (wsi->state) {
 121                         case WSI_STATE_HTTP:
 122                         case WSI_STATE_HTTP_HEADERS:
 123                                 goto http_complete;
 124                         case WSI_STATE_HTTP_ISSUING_FILE:
 125                                 goto read_ok;
 126                         case WSI_STATE_HTTP_BODY:
 127                                 wsi->u.http.content_remain =
 128                                                 wsi->u.http.content_length;
 129                                 if (wsi->u.http.content_remain)
 130                                         goto http_postbody;
 131
 132                                 /* there is no POST content */
 133                                 goto postbody_completion;
 134                         default:
 135                                 break;
 136                 }
 137                 break;
 138
 139         case WSI_STATE_HTTP_BODY:
 140 http_postbody:
 141                 while (len && wsi->u.http.content_remain) {
 142                         /* Copy as much as possible, up to the limit of:
 143                          * what we have in the read buffer (len)
 144                          * remaining portion of the POST body (content_remain)
 145                          */
 146                         body_chunk_len = min(wsi->u.http.content_remain,len);
 147                         wsi->u.http.content_remain -= body_chunk_len;
 148                         len -= body_chunk_len;
 149
 150                         n = wsi->protocol->callback(
 151                                 wsi->protocol->owning_server, wsi,
 152                                 LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 153                                 buf, body_chunk_len);
 154                         if (n)
 155                                 goto bail;
 156
 157                         buf += body_chunk_len;
 158
 159                         if (wsi->u.http.content_remain)  {
 160                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 161                                                 AWAITING_TIMEOUT);
 162                                 break;
 163                         }
 164                         /* he sent all the content in time */
 165 postbody_completion:
 166                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 167                         n = wsi->protocol->callback(
 168                                 wsi->protocol->owning_server, wsi,
 169                                 LWS_CALLBACK_HTTP_BODY_COMPLETION,
 170                                 wsi->user_space, NULL, 0);
 171                         if (n)
 172                                 goto bail;
 173
 174                         goto http_complete;
 175                 }
 176                 break;
 177
 178         case WSI_STATE_ESTABLISHED:
 179         case WSI_STATE_AWAITING_CLOSE_ACK:
 180                 if (lws_handshake_client(wsi, &buf, len))
 181                         goto bail;
 182                 switch (wsi->mode) {
 183                 case LWS_CONNMODE_WS_SERVING:
 184
 185                         if (lws_interpret_incoming_packet(wsi, buf, len) < 0) {
 186                                 lwsl_info("interpret_incoming_packet has bailed\n");
 187                                 goto bail;
 188                         }
 189                         break;
 190                 }
 191                 break;
 192         default:
 193                 lwsl_err("lws_read: Unhandled state\n");
 194                 break;
 195         }
 196
 197 read_ok:
 198         /* Nothing more to do for now */
 199         lwsl_debug("lws_read: read_ok\n");
 200
 201         return 0;
 202
 203 http_complete:
 204         lwsl_debug("lws_read: http_complete\n");
 205
 206 #ifndef LWS_NO_SERVER
 207         /* Did the client want to keep the HTTP connection going? */
 208         if (lws_http_transaction_completed(wsi))
 209                 goto bail;
 210 #endif
 211         /* If we have more data, loop back around: */
 212         if (len)
 213                 goto http_new;
 214
 215         return 0;
 216
 217 bail:
 218         lwsl_debug("closing connection at lws_read bail:\n");
 219         lws_close_and_free_session(context, wsi, LWS_CLOSE_STATUS_NOSTATUS);
 220
 221         return -1;
 222 }