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