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 *wsi, unsigned char *buf, size_t len)
  62 {
  63         unsigned char *last_char;
  64         int body_chunk_len;
  65         size_t n;
  66
  67         lwsl_debug("%s: incoming len %d\n", __func__, (int)len);
  68
  69         switch (wsi->state) {
  70 #ifdef LWS_USE_HTTP2
  71         case LWSS_HTTP2_AWAIT_CLIENT_PREFACE:
  72         case LWSS_HTTP2_ESTABLISHED_PRE_SETTINGS:
  73         case LWSS_HTTP2_ESTABLISHED:
  74                 n = 0;
  75                 while (n < len) {
  76                         /*
  77                          * we were accepting input but now we stopped doing so
  78                          */
  79                         if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
  80                                 lws_rxflow_cache(wsi, buf, n, len);
  81
  82                                 return 1;
  83                         }
  84
  85                         /* account for what we're using in rxflow buffer */
  86                         if (wsi->rxflow_buffer)
  87                                 wsi->rxflow_pos++;
  88                         if (lws_http2_parser(wsi, buf[n++]))
  89                                 goto bail;
  90                 }
  91                 break;
  92 #endif
  93 http_new:
  94         case LWSS_HTTP:
  95                 wsi->hdr_parsing_completed = 0;
  96                 /* fallthru */
  97         case LWSS_HTTP_ISSUING_FILE:
  98                 wsi->state = LWSS_HTTP_HEADERS;
  99                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
 100                 wsi->u.hdr.lextable_pos = 0;
 101                 /* fallthru */
 102         case LWSS_HTTP_HEADERS:
 103                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 104
 105                 if (lws_handshake_client(wsi, &buf, len))
 106                         goto bail;
 107
 108                 last_char = buf;
 109                 if (lws_handshake_server(wsi, &buf, len))
 110                         /* Handshake indicates this session is done. */
 111                         goto bail;
 112
 113                 /*
 114                  * It's possible that we've exhausted our data already, or
 115                  * rx flow control has stopped us dealing with this early,
 116                  * but lws_handshake_server doesn't update len for us.
 117                  * Figure out how much was read, so that we can proceed
 118                  * appropriately:
 119                  */
 120                 len -= (buf - last_char);
 121                 lwsl_debug("%s: thinks we have used %d\n", __func__, len);
 122
 123                 if (!wsi->hdr_parsing_completed)
 124                         /* More header content on the way */
 125                         goto read_ok;
 126
 127                 switch (wsi->state) {
 128                         case LWSS_HTTP:
 129                         case LWSS_HTTP_HEADERS:
 130                                 goto http_complete;
 131                         case LWSS_HTTP_ISSUING_FILE:
 132                                 goto read_ok;
 133                         case LWSS_HTTP_BODY:
 134                                 wsi->u.http.content_remain =
 135                                                 wsi->u.http.content_length;
 136                                 if (wsi->u.http.content_remain)
 137                                         goto http_postbody;
 138
 139                                 /* there is no POST content */
 140                                 goto postbody_completion;
 141                         default:
 142                                 break;
 143                 }
 144                 break;
 145
 146         case LWSS_HTTP_BODY:
 147 http_postbody:
 148                 while (len && wsi->u.http.content_remain) {
 149                         /* Copy as much as possible, up to the limit of:
 150                          * what we have in the read buffer (len)
 151                          * remaining portion of the POST body (content_remain)
 152                          */
 153                         body_chunk_len = min(wsi->u.http.content_remain,len);
 154                         wsi->u.http.content_remain -= body_chunk_len;
 155                         len -= body_chunk_len;
 156
 157                         n = wsi->protocol->callback(wsi,
 158                                 LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 159                                 buf, body_chunk_len);
 160                         if (n)
 161                                 goto bail;
 162
 163                         buf += body_chunk_len;
 164
 165                         if (wsi->u.http.content_remain)  {
 166                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 167                                                 AWAITING_TIMEOUT);
 168                                 break;
 169                         }
 170                         /* he sent all the content in time */
 171 postbody_completion:
 172                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 173                         n = wsi->protocol->callback(wsi,
 174                                 LWS_CALLBACK_HTTP_BODY_COMPLETION,
 175                                 wsi->user_space, NULL, 0);
 176                         if (n)
 177                                 goto bail;
 178
 179                         goto http_complete;
 180                 }
 181                 break;
 182
 183         case LWSS_ESTABLISHED:
 184         case LWSS_AWAITING_CLOSE_ACK:
 185                 if (lws_handshake_client(wsi, &buf, len))
 186                         goto bail;
 187                 switch (wsi->mode) {
 188                 case LWSCM_WS_SERVING:
 189
 190                         if (lws_interpret_incoming_packet(wsi, &buf, len) < 0) {
 191                                 lwsl_info("interpret_incoming_packet has bailed\n");
 192                                 goto bail;
 193                         }
 194                         break;
 195                 }
 196                 break;
 197         default:
 198                 lwsl_err("%s: Unhandled state\n", __func__);
 199                 break;
 200         }
 201
 202 read_ok:
 203         /* Nothing more to do for now */
 204         lwsl_debug("%s: read_ok\n", __func__);
 205
 206         return 0;
 207
 208 http_complete:
 209         lwsl_debug("%s: http_complete\n", __func__);
 210
 211 #ifndef LWS_NO_SERVER
 212         /* Did the client want to keep the HTTP connection going? */
 213         if (lws_http_transaction_completed(wsi))
 214                 goto bail;
 215 #endif
 216         /* If we have more data, loop back around: */
 217         if (len)
 218                 goto http_new;
 219
 220         return 0;
 221
 222 bail:
 223         lwsl_debug("closing connection at lws_read bail:\n");
 224         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 225
 226         return -1;
 227 }