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                 assert(wsi->u.hdr.ah);
 104                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 105
 106                 if (lws_handshake_client(wsi, &buf, len))
 107                         goto bail;
 108
 109                 last_char = buf;
 110                 if (lws_handshake_server(wsi, &buf, len))
 111                         /* Handshake indicates this session is done. */
 112                         goto bail;
 113
 114                 /*
 115                  * It's possible that we've exhausted our data already, or
 116                  * rx flow control has stopped us dealing with this early,
 117                  * but lws_handshake_server doesn't update len for us.
 118                  * Figure out how much was read, so that we can proceed
 119                  * appropriately:
 120                  */
 121                 len -= (buf - last_char);
 122                 lwsl_debug("%s: thinks we have used %d\n", __func__, len);
 123
 124                 if (!wsi->hdr_parsing_completed)
 125                         /* More header content on the way */
 126                         goto read_ok;
 127
 128                 switch (wsi->state) {
 129                         case LWSS_HTTP:
 130                         case LWSS_HTTP_HEADERS:
 131                                 goto http_complete;
 132                         case LWSS_HTTP_ISSUING_FILE:
 133                                 goto read_ok;
 134                         case LWSS_HTTP_BODY:
 135                                 wsi->u.http.content_remain =
 136                                                 wsi->u.http.content_length;
 137                                 if (wsi->u.http.content_remain)
 138                                         goto http_postbody;
 139
 140                                 /* there is no POST content */
 141                                 goto postbody_completion;
 142                         default:
 143                                 break;
 144                 }
 145                 break;
 146
 147         case LWSS_HTTP_BODY:
 148 http_postbody:
 149                 while (len && wsi->u.http.content_remain) {
 150                         /* Copy as much as possible, up to the limit of:
 151                          * what we have in the read buffer (len)
 152                          * remaining portion of the POST body (content_remain)
 153                          */
 154                         body_chunk_len = min(wsi->u.http.content_remain,len);
 155                         wsi->u.http.content_remain -= body_chunk_len;
 156                         len -= body_chunk_len;
 157
 158                         n = wsi->protocol->callback(wsi,
 159                                 LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 160                                 buf, body_chunk_len);
 161                         if (n)
 162                                 goto bail;
 163
 164                         buf += body_chunk_len;
 165
 166                         if (wsi->u.http.content_remain)  {
 167                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 168                                                 AWAITING_TIMEOUT);
 169                                 break;
 170                         }
 171                         /* he sent all the content in time */
 172 postbody_completion:
 173                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 174                         n = wsi->protocol->callback(wsi,
 175                                 LWS_CALLBACK_HTTP_BODY_COMPLETION,
 176                                 wsi->user_space, NULL, 0);
 177                         if (n)
 178                                 goto bail;
 179
 180                         goto http_complete;
 181                 }
 182                 break;
 183
 184         case LWSS_ESTABLISHED:
 185         case LWSS_AWAITING_CLOSE_ACK:
 186         case LWSS_SHUTDOWN:
 187                 if (lws_handshake_client(wsi, &buf, len))
 188                         goto bail;
 189                 switch (wsi->mode) {
 190                 case LWSCM_WS_SERVING:
 191
 192                         if (lws_interpret_incoming_packet(wsi, &buf, len) < 0) {
 193                                 lwsl_info("interpret_incoming_packet has bailed\n");
 194                                 goto bail;
 195                         }
 196                         break;
 197                 }
 198                 break;
 199         default:
 200                 lwsl_err("%s: Unhandled state\n", __func__);
 201                 break;
 202         }
 203
 204 read_ok:
 205         /* Nothing more to do for now */
 206         lwsl_debug("%s: read_ok\n", __func__);
 207
 208         return 0;
 209
 210 http_complete:
 211         lwsl_debug("%s: http_complete\n", __func__);
 212
 213 #ifndef LWS_NO_SERVER
 214         /* Did the client want to keep the HTTP connection going? */
 215         if (lws_http_transaction_completed(wsi))
 216                 goto bail;
 217 #endif
 218         /* If we have more data, loop back around: */
 219         if (len)
 220                 goto http_new;
 221
 222         return 0;
 223
 224 bail:
 225         lwsl_debug("closing connection at lws_read bail:\n");
 226         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 227
 228         return -1;
 229 }