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
  60 LWS_VISIBLE int
  61 lws_read(struct lws_context *context, struct lws *wsi, unsigned char *buf,
  62          size_t len)
  63 {
  64         unsigned char *last_char;
  65         int body_chunk_len;
  66         size_t n;
  67
  68         switch (wsi->state) {
  69 #ifdef LWS_USE_HTTP2
  70         case WSI_STATE_HTTP2_AWAIT_CLIENT_PREFACE:
  71         case WSI_STATE_HTTP2_ESTABLISHED_PRE_SETTINGS:
  72         case WSI_STATE_HTTP2_ESTABLISHED:
  73                 n = 0;
  74                 while (n < len) {
  75                         /*
  76                          * we were accepting input but now we stopped doing so
  77                          */
  78                         if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
  79                                 lws_rxflow_cache(wsi, buf, n, len);
  80
  81                                 return 1;
  82                         }
  83
  84                         /* account for what we're using in rxflow buffer */
  85                         if (wsi->rxflow_buffer)
  86                                 wsi->rxflow_pos++;
  87                         if (lws_http2_parser(context, wsi, buf[n++]))
  88                                 goto bail;
  89                 }
  90                 break;
  91 #endif
  92 http_new:
  93         case WSI_STATE_HTTP:
  94                 wsi->hdr_parsing_completed = 0;
  95                 /* fallthru */
  96         case WSI_STATE_HTTP_ISSUING_FILE:
  97                 wsi->state = WSI_STATE_HTTP_HEADERS;
  98                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
  99                 wsi->u.hdr.lextable_pos = 0;
 100                 /* fallthru */
 101         case WSI_STATE_HTTP_HEADERS:
 102                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 103
 104                 if (lws_handshake_client(wsi, &buf, len))
 105                         goto bail;
 106
 107                 last_char = buf;
 108                 if (lws_handshake_server(context, wsi, &buf, len))
 109                         /* Handshake indicates this session is done. */
 110                         goto bail;
 111
 112                 /* It's possible that we've exhausted our data already, but
 113                  * lws_handshake_server doesn't update len for us. Figure out how
 114                  * much was read, so that we can proceed appropriately: */
 115                 len -= (buf - last_char);
 116
 117                 if (!wsi->hdr_parsing_completed)
 118                         /* More header content on the way */
 119                         goto read_ok;
 120
 121                 switch (wsi->state) {
 122                         case WSI_STATE_HTTP:
 123                         case WSI_STATE_HTTP_HEADERS:
 124                                 goto http_complete;
 125                         case WSI_STATE_HTTP_ISSUING_FILE:
 126                                 goto read_ok;
 127                         case WSI_STATE_HTTP_BODY:
 128                                 wsi->u.http.content_remain =
 129                                                 wsi->u.http.content_length;
 130                                 if (wsi->u.http.content_remain)
 131                                         goto http_postbody;
 132
 133                                 /* there is no POST content */
 134                                 goto postbody_completion;
 135                         default:
 136                                 break;
 137                 }
 138                 break;
 139
 140         case WSI_STATE_HTTP_BODY:
 141 http_postbody:
 142                 while (len && wsi->u.http.content_remain) {
 143                         /* Copy as much as possible, up to the limit of:
 144                          * what we have in the read buffer (len)
 145                          * remaining portion of the POST body (content_remain)
 146                          */
 147                         body_chunk_len = min(wsi->u.http.content_remain,len);
 148                         wsi->u.http.content_remain -= body_chunk_len;
 149                         len -= body_chunk_len;
 150
 151                         n = wsi->protocol->callback(
 152                                 lws_get_ctx(wsi), wsi,
 153                                 LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 154                                 buf, body_chunk_len);
 155                         if (n)
 156                                 goto bail;
 157
 158                         buf += body_chunk_len;
 159
 160                         if (wsi->u.http.content_remain)  {
 161                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 162                                                 AWAITING_TIMEOUT);
 163                                 break;
 164                         }
 165                         /* he sent all the content in time */
 166 postbody_completion:
 167                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 168                         n = wsi->protocol->callback(
 169                                 lws_get_ctx(wsi), wsi,
 170                                 LWS_CALLBACK_HTTP_BODY_COMPLETION,
 171                                 wsi->user_space, NULL, 0);
 172                         if (n)
 173                                 goto bail;
 174
 175                         goto http_complete;
 176                 }
 177                 break;
 178
 179         case WSI_STATE_ESTABLISHED:
 180         case WSI_STATE_AWAITING_CLOSE_ACK:
 181                 if (lws_handshake_client(wsi, &buf, len))
 182                         goto bail;
 183                 switch (wsi->mode) {
 184                 case LWS_CONNMODE_WS_SERVING:
 185
 186                         if (lws_interpret_incoming_packet(wsi, buf, len) < 0) {
 187                                 lwsl_info("interpret_incoming_packet has bailed\n");
 188                                 goto bail;
 189                         }
 190                         break;
 191                 }
 192                 break;
 193         default:
 194                 lwsl_err("lws_read: Unhandled state\n");
 195                 break;
 196         }
 197
 198 read_ok:
 199         /* Nothing more to do for now */
 200         lwsl_debug("lws_read: read_ok\n");
 201
 202         return 0;
 203
 204 http_complete:
 205         lwsl_debug("lws_read: http_complete\n");
 206
 207 #ifndef LWS_NO_SERVER
 208         /* Did the client want to keep the HTTP connection going? */
 209         if (lws_http_transaction_completed(wsi))
 210                 goto bail;
 211 #endif
 212         /* If we have more data, loop back around: */
 213         if (len)
 214                 goto http_new;
 215
 216         return 0;
 217
 218 bail:
 219         lwsl_debug("closing connection at lws_read bail:\n");
 220         lws_close_and_free_session(context, wsi, LWS_CLOSE_STATUS_NOSTATUS);
 221
 222         return -1;
 223 }