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