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, size_t len)
  64 {
  65         unsigned char *last_char, *oldbuf = buf;
  66         int body_chunk_len;
  67         size_t n;
  68
  69         lwsl_debug("%s: incoming len %d\n", __func__, (int)len);
  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                                 goto bail;
  92                 }
  93                 break;
  94 #endif
  95
  96         case LWSS_HTTP:
  97                 wsi->hdr_parsing_completed = 0;
  98                 /* fallthru */
  99         case LWSS_HTTP_ISSUING_FILE:
 100                 wsi->state = LWSS_HTTP_HEADERS;
 101                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
 102                 wsi->u.hdr.lextable_pos = 0;
 103                 /* fallthru */
 104         case LWSS_HTTP_HEADERS:
 105                 assert(wsi->u.hdr.ah);
 106                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
 107
 108                 if (lws_handshake_client(wsi, &buf, len))
 109                         goto bail;
 110
 111                 last_char = buf;
 112                 if (lws_handshake_server(wsi, &buf, len))
 113                         /* Handshake indicates this session is done. */
 114                         goto bail;
 115
 116                 /*
 117                  * It's possible that we've exhausted our data already, or
 118                  * rx flow control has stopped us dealing with this early,
 119                  * but lws_handshake_server doesn't update len for us.
 120                  * Figure out how much was read, so that we can proceed
 121                  * appropriately:
 122                  */
 123                 len -= (buf - last_char);
 124                 lwsl_debug("%s: thinks we have used %d\n", __func__, len);
 125
 126                 if (!wsi->hdr_parsing_completed)
 127                         /* More header content on the way */
 128                         goto read_ok;
 129
 130                 switch (wsi->state) {
 131                         case LWSS_HTTP:
 132                         case LWSS_HTTP_HEADERS:
 133                                 goto read_ok;
 134                         case LWSS_HTTP_ISSUING_FILE:
 135                                 goto read_ok;
 136                         case LWSS_HTTP_BODY:
 137                                 wsi->u.http.content_remain =
 138                                                 wsi->u.http.content_length;
 139                                 if (wsi->u.http.content_remain)
 140                                         goto http_postbody;
 141
 142                                 /* there is no POST content */
 143                                 goto postbody_completion;
 144                         default:
 145                                 break;
 146                 }
 147                 break;
 148
 149         case LWSS_HTTP_BODY:
 150 http_postbody:
 151                 while (len && wsi->u.http.content_remain) {
 152                         /* Copy as much as possible, up to the limit of:
 153                          * what we have in the read buffer (len)
 154                          * remaining portion of the POST body (content_remain)
 155                          */
 156                         body_chunk_len = min(wsi->u.http.content_remain,len);
 157                         wsi->u.http.content_remain -= body_chunk_len;
 158                         len -= body_chunk_len;
 159 #ifdef LWS_WITH_CGI
 160                         if (wsi->cgi) {
 161                                 struct lws_cgi_args args;
 162
 163                                 args.ch = LWS_STDIN;
 164                                 args.stdwsi = &wsi->cgi->stdwsi[0];
 165                                 args.data = buf;
 166                                 args.len = body_chunk_len;
 167
 168                                 /* returns how much used */
 169                                 n = user_callback_handle_rxflow(
 170                                         wsi->protocol->callback,
 171                                         wsi, LWS_CALLBACK_CGI_STDIN_DATA,
 172                                         wsi->user_space,
 173                                         (void *)&args, 0);
 174                                 if (n < 0)
 175                                         goto bail;
 176                         } else {
 177 #endif
 178                                 n = wsi->protocol->callback(wsi,
 179                                         LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 180                                         buf, body_chunk_len);
 181                                 if (n)
 182                                         goto bail;
 183                                 n = body_chunk_len;
 184 #ifdef LWS_WITH_CGI
 185                         }
 186 #endif
 187                         buf += n;
 188
 189                         if (wsi->u.http.content_remain)  {
 190                                 lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
 191                                                 wsi->context->timeout_secs);
 192                                 break;
 193                         }
 194                         /* he sent all the content in time */
 195 postbody_completion:
 196                         lws_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 197 #ifdef LWS_WITH_CGI
 198                         if (!wsi->cgi)
 199 #endif
 200                         {
 201                                 n = wsi->protocol->callback(wsi,
 202                                         LWS_CALLBACK_HTTP_BODY_COMPLETION,
 203                                         wsi->user_space, NULL, 0);
 204                                 if (n)
 205                                         goto bail;
 206                         }
 207
 208                         goto http_complete;
 209                 }
 210                 break;
 211
 212         case LWSS_ESTABLISHED:
 213         case LWSS_AWAITING_CLOSE_ACK:
 214         case LWSS_SHUTDOWN:
 215                 if (lws_handshake_client(wsi, &buf, len))
 216                         goto bail;
 217                 switch (wsi->mode) {
 218                 case LWSCM_WS_SERVING:
 219
 220                         if (lws_interpret_incoming_packet(wsi, &buf, len) < 0) {
 221                                 lwsl_info("interpret_incoming_packet has bailed\n");
 222                                 goto bail;
 223                         }
 224                         break;
 225                 }
 226                 break;
 227         default:
 228                 lwsl_err("%s: Unhandled state\n", __func__);
 229                 break;
 230         }
 231
 232 read_ok:
 233         /* Nothing more to do for now */
 234         lwsl_info("%s: read_ok, used %d\n", __func__, buf - oldbuf);
 235
 236         return buf - oldbuf;
 237
 238 http_complete:
 239         lwsl_debug("%s: http_complete\n", __func__);
 240
 241 #ifndef LWS_NO_SERVER
 242         /* Did the client want to keep the HTTP connection going? */
 243         if (lws_http_transaction_completed(wsi))
 244                 goto bail;
 245 #endif
 246         /* we may have next header set already, but return to event loop first
 247          * so a heaily-pipelined http/1.1 connection cannot monopolize the
 248          * service thread with GET hugefile.bin GET hugefile.bin etc
 249          */
 250         goto read_ok;
 251
 252 bail:
 253         lwsl_debug("closing connection at lws_read bail:\n");
 254         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 255
 256         return -1;
 257 }