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 /*
  50  * We have to take care about parsing because the headers may be split
  51  * into multiple fragments.  They may contain unknown headers with arbitrary
  52  * argument lengths.  So, we parse using a single-character at a time state
  53  * machine that is completely independent of packet size.
  54  */
  55
  56 int
  57 libwebsocket_read(struct libwebsocket_context *context,
  58                      struct libwebsocket *wsi, unsigned char * buf, size_t len)
  59 {
  60         size_t n;
  61
  62         switch (wsi->state) {
  63         case WSI_STATE_HTTP_ISSUING_FILE:
  64         case WSI_STATE_HTTP:
  65                 wsi->state = WSI_STATE_HTTP_HEADERS;
  66                 wsi->parser_state = WSI_TOKEN_NAME_PART;
  67                 wsi->lextable_pos = 0;
  68                 /* fallthru */
  69         case WSI_STATE_HTTP_HEADERS:
  70
  71                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
  72 #ifdef _DEBUG
  73                 //fwrite(buf, 1, len, stderr);
  74 #endif
  75
  76 #ifndef LWS_NO_CLIENT
  77
  78 //              lwsl_info("mode=%d\n", wsi->mode);
  79
  80                 switch (wsi->mode) {
  81                 case LWS_CONNMODE_WS_CLIENT_WAITING_PROXY_REPLY:
  82                 case LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE:
  83                 case LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY:
  84                 case LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT:
  85                 case LWS_CONNMODE_WS_CLIENT:
  86                         for (n = 0; n < len; n++)
  87                                 libwebsocket_client_rx_sm(wsi, *buf++);
  88
  89                         return 0;
  90                 default:
  91                         break;
  92                 }
  93 #endif
  94 #ifndef LWS_NO_SERVER
  95                 /* LWS_CONNMODE_WS_SERVING */
  96
  97                 extern int handshake_00(struct libwebsocket_context *context, struct libwebsocket *wsi);
  98                 extern int handshake_0405(struct libwebsocket_context *context, struct libwebsocket *wsi);
  99
 100                 for (n = 0; n < len; n++)
 101                         libwebsocket_parse(wsi, *buf++);
 102
 103                 if (wsi->parser_state != WSI_PARSING_COMPLETE)
 104                         break;
 105
 106                 lwsl_parser("seem to be serving, mode is %d\n", wsi->mode);
 107
 108                 lwsl_parser("libwebsocket_parse sees parsing complete\n");
 109
 110                 /* is this websocket protocol or normal http 1.0? */
 111
 112                 if (!wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
 113                              !wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len) {
 114                         wsi->state = WSI_STATE_HTTP;
 115                         if (wsi->protocol->callback)
 116                                 if (wsi->protocol->callback(context, wsi,
 117                                                                 LWS_CALLBACK_HTTP, wsi->user_space,
 118                                                                 wsi->utf8_token[WSI_TOKEN_GET_URI].token,
 119                                                                 wsi->utf8_token[WSI_TOKEN_GET_URI].token_len))
 120                                         goto bail;
 121                         return 0;
 122                 }
 123
 124                 if (!wsi->protocol)
 125                         lwsl_err("NULL protocol at libwebsocket_read\n");
 126
 127                 /*
 128                  * It's websocket
 129                  *
 130                  * Make sure user side is happy about protocol
 131                  */
 132
 133                 while (wsi->protocol->callback) {
 134
 135                         if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL) {
 136                                 if (wsi->protocol->name == NULL)
 137                                         break;
 138                         } else
 139                                 if (wsi->protocol->name && strcmp(
 140                                      wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 141                                                       wsi->protocol->name) == 0)
 142                                         break;
 143
 144                         wsi->protocol++;
 145                 }
 146
 147                 /* we didn't find a protocol he wanted? */
 148
 149                 if (wsi->protocol->callback == NULL) {
 150                         if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL)
 151                                 lwsl_err("[no protocol] "
 152                                         "not supported (use NULL .name)\n");
 153                         else
 154                                 lwsl_err("Requested protocol %s "
 155                                                 "not supported\n",
 156                                      wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 157                         goto bail;
 158                 }
 159
 160                 /*
 161                  * find out which spec version the client is using
 162                  * if this header is not given, we default to 00 (aka 76)
 163                  */
 164
 165                 if (wsi->utf8_token[WSI_TOKEN_VERSION].token_len)
 166                         wsi->ietf_spec_revision =
 167                                  atoi(wsi->utf8_token[WSI_TOKEN_VERSION].token);
 168
 169                 /*
 170                  * Give the user code a chance to study the request and
 171                  * have the opportunity to deny it
 172                  */
 173
 174                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 175                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 176                                                 &wsi->utf8_token[0], NULL, 0)) {
 177                         lwsl_warn("User code denied connection\n");
 178                         goto bail;
 179                 }
 180
 181
 182                 /*
 183                  * Perform the handshake according to the protocol version the
 184                  * client announced
 185                  */
 186
 187                 switch (wsi->ietf_spec_revision) {
 188                 case 0: /* applies to 76 and 00 */
 189                         wsi->xor_mask = xor_no_mask;
 190                         if (handshake_00(context, wsi))
 191                                 goto bail;
 192                         break;
 193                 case 4: /* 04 */
 194                         wsi->xor_mask = xor_mask_04;
 195                         lwsl_parser("libwebsocket_parse calling handshake_04\n");
 196                         if (handshake_0405(context, wsi))
 197                                 goto bail;
 198                         break;
 199                 case 5:
 200                 case 6:
 201                 case 7:
 202                 case 8:
 203                 case 13:
 204                         wsi->xor_mask = xor_mask_05;
 205                         lwsl_parser("libwebsocket_parse calling handshake_04\n");
 206                         if (handshake_0405(context, wsi))
 207                                 goto bail;
 208                         break;
 209
 210                 default:
 211                         lwsl_warn("Unknown client spec version %d\n",
 212                                                        wsi->ietf_spec_revision);
 213                         goto bail;
 214                 }
 215
 216                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 217
 218                 lwsl_parser("accepted v%02d connection\n",
 219                                                        wsi->ietf_spec_revision);
 220 #endif
 221                 break;
 222
 223         case WSI_STATE_AWAITING_CLOSE_ACK:
 224         case WSI_STATE_ESTABLISHED:
 225 #ifndef LWS_NO_CLIENT
 226                 switch (wsi->mode) {
 227                 case LWS_CONNMODE_WS_CLIENT:
 228                         for (n = 0; n < len; n++)
 229                                 if (libwebsocket_client_rx_sm(wsi, *buf++) < 0)
 230                                         goto bail;
 231
 232                         return 0;
 233                 default:
 234                         break;
 235                 }
 236 #endif
 237 #ifndef LWS_NO_SERVER
 238                 /* LWS_CONNMODE_WS_SERVING */
 239
 240                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0)
 241                         goto bail;
 242 #endif
 243                 break;
 244         default:
 245                 lwsl_err("libwebsocket_read: Unhandled state\n");
 246                 break;
 247         }
 248
 249         return 0;
 250
 251 bail:
 252         libwebsocket_close_and_free_session(context, wsi,
 253                                                      LWS_CLOSE_STATUS_NOSTATUS);
 254
 255         return -1;
 256 }