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 /*
  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 libwebsocket_read(struct libwebsocket_context *context,
  62                      struct libwebsocket *wsi, unsigned char *buf, size_t len)
  63 {
  64         size_t n;
  65         int body_chunk_len;
  66         unsigned char *last_char;
  67
  68         switch (wsi->state) {
  69 http_new:
  70         case WSI_STATE_HTTP:
  71                 wsi->hdr_parsing_completed = 0;
  72                 /* fallthru */
  73         case WSI_STATE_HTTP_ISSUING_FILE:
  74                 wsi->state = WSI_STATE_HTTP_HEADERS;
  75                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
  76                 wsi->u.hdr.lextable_pos = 0;
  77                 /* fallthru */
  78         case WSI_STATE_HTTP_HEADERS:
  79                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
  80
  81                 if (lws_handshake_client(wsi, &buf, len))
  82                         goto bail;
  83
  84                 last_char = buf;
  85                 if (lws_handshake_server(context, wsi, &buf, len))
  86                         /* Handshake indicates this session is done. */
  87                         goto bail;
  88
  89                 /* It's possible that we've exhausted our data already, but
  90                  * lws_handshake_server doesn't update len for us. Figure out how
  91                  * much was read, so that we can proceed appropriately: */
  92                 len -= (buf - last_char);
  93
  94                 if (!wsi->hdr_parsing_completed)
  95                         /* More header content on the way */
  96                         goto read_ok;
  97
  98                 switch (wsi->state) {
  99                         case WSI_STATE_HTTP:
 100                         case WSI_STATE_HTTP_HEADERS:
 101                                 goto http_complete;
 102                         case WSI_STATE_HTTP_ISSUING_FILE:
 103                                 goto read_ok;
 104                         case WSI_STATE_HTTP_BODY:
 105                                 wsi->u.http.content_remain = wsi->u.http.content_length;
 106                                 goto http_postbody;
 107                         default:
 108                                 break;
 109                 }
 110                 break;
 111
 112         case WSI_STATE_HTTP_BODY:
 113 http_postbody:
 114                 while (len && wsi->u.http.content_remain) {
 115                         /* Copy as much as possible, up to the limit of:
 116                          * what we have in the read buffer (len)
 117                          * remaining portion of the POST body (content_remain)
 118                          */
 119                         body_chunk_len = min(wsi->u.http.content_remain,len);
 120                         wsi->u.http.content_remain -= body_chunk_len;
 121                         len -= body_chunk_len;
 122
 123                         if (wsi->protocol->callback) {
 124                                 n = wsi->protocol->callback(
 125                                         wsi->protocol->owning_server, wsi,
 126                                         LWS_CALLBACK_HTTP_BODY, wsi->user_space,
 127                                         buf, body_chunk_len);
 128                                 if (n)
 129                                         goto bail;
 130                         }
 131                         buf += body_chunk_len;
 132
 133                         if (!wsi->u.http.content_remain)  {
 134                                 /* he sent the content in time */
 135                                 libwebsocket_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 136                                 if (wsi->protocol->callback) {
 137                                         n = wsi->protocol->callback(
 138                                                 wsi->protocol->owning_server, wsi,
 139                                                 LWS_CALLBACK_HTTP_BODY_COMPLETION,
 140                                                 wsi->user_space, NULL, 0);
 141                                         if (n)
 142                                                 goto bail;
 143                                 }
 144                                 goto http_complete;
 145                         }
 146                 }
 147                 break;
 148
 149         case WSI_STATE_ESTABLISHED:
 150         case WSI_STATE_AWAITING_CLOSE_ACK:
 151                 if (lws_handshake_client(wsi, &buf, len))
 152                         goto bail;
 153                 switch (wsi->mode) {
 154                 case LWS_CONNMODE_WS_SERVING:
 155
 156                         if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 157                                 lwsl_info("interpret_incoming_packet has bailed\n");
 158                                 goto bail;
 159                         }
 160                         break;
 161                 }
 162                 break;
 163         default:
 164                 lwsl_err("libwebsocket_read: Unhandled state\n");
 165                 break;
 166         }
 167
 168 read_ok:
 169         /* Nothing more to do for now. */
 170         lwsl_debug("libwebsocket_read: read_ok\n");
 171
 172         return 0;
 173
 174 http_complete:
 175         lwsl_debug("libwebsocket_read: http_complete\n");
 176         /* Handle keep-alives, by preparing for a new request: */
 177         if (wsi->u.http.connection_type == HTTP_CONNECTION_KEEP_ALIVE) {
 178                 lwsl_debug("libwebsocket_read: keep-alive\n");
 179                 wsi->state = WSI_STATE_HTTP;
 180                 wsi->mode = LWS_CONNMODE_HTTP_SERVING;
 181                 /* We might be streaming HTTP content, so leave the connection open.*/
 182                 libwebsocket_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 183
 184                 if (lws_allocate_header_table(wsi))
 185                         goto bail;
 186
 187                 /* If we have more data, loop back around: */
 188                 if (len)
 189                         goto http_new;
 190
 191                 return 0;
 192         }
 193
 194 bail:
 195         lwsl_debug("closing connection at libwebsocket_read bail:\n");
 196
 197         libwebsocket_close_and_free_session(context, wsi,
 198                                                      LWS_CLOSE_STATUS_NOSTATUS);
 199
 200         return -1;
 201 }