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->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
  67                 wsi->u.hdr.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_0405(struct libwebsocket_context *context, struct libwebsocket *wsi);
  98
  99                 for (n = 0; n < len; n++)
 100                         libwebsocket_parse(wsi, *buf++);
 101
 102                 if (wsi->u.hdr.parser_state != WSI_PARSING_COMPLETE)
 103                         break;
 104
 105                 lwsl_parser("seem to be serving, mode is %d\n", wsi->mode);
 106
 107                 lwsl_parser("libwebsocket_parse sees parsing complete\n");
 108
 109                 /* is this websocket protocol or normal http 1.0? */
 110
 111                 if (!wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
 112                              !wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len) {
 113                         wsi->state = WSI_STATE_HTTP;
 114                         if (wsi->protocol->callback)
 115                                 if (wsi->protocol->callback(context, wsi,
 116                                                                 LWS_CALLBACK_HTTP, wsi->user_space,
 117                                                                 wsi->utf8_token[WSI_TOKEN_GET_URI].token,
 118                                                                 wsi->utf8_token[WSI_TOKEN_GET_URI].token_len)) {
 119                                         lwsl_info("LWS_CALLBACK_HTTP wanted to close\n");
 120                                         goto bail;
 121                                 }
 122                         return 0;
 123                 }
 124
 125                 if (!wsi->protocol)
 126                         lwsl_err("NULL protocol at libwebsocket_read\n");
 127
 128
 129                 /*
 130                  * It's websocket
 131                  *
 132                  * Make sure user side is happy about protocol
 133                  */
 134
 135                 while (wsi->protocol->callback) {
 136
 137                         if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL) {
 138                                 if (wsi->protocol->name == NULL)
 139                                         break;
 140                         } else
 141                                 if (wsi->protocol->name && strcmp(
 142                                      wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 143                                                       wsi->protocol->name) == 0)
 144                                         break;
 145
 146                         wsi->protocol++;
 147                 }
 148
 149                 /* we didn't find a protocol he wanted? */
 150
 151                 if (wsi->protocol->callback == NULL) {
 152                         if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL) {
 153                                 lwsl_info("[no protocol] "
 154                                         "mapped to protocol 0 handler\n");
 155                                 wsi->protocol = &context->protocols[0];
 156                         } else {
 157                                 lwsl_err("Requested protocol %s "
 158                                                 "not supported\n",
 159                                      wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 160                                 goto bail;
 161                         }
 162                 }
 163
 164                 /*
 165                  * find out which spec version the client is using
 166                  * if this header is not given, we default to 00 (aka 76)
 167                  */
 168
 169                 if (wsi->utf8_token[WSI_TOKEN_VERSION].token_len)
 170                         wsi->ietf_spec_revision =
 171                                  atoi(wsi->utf8_token[WSI_TOKEN_VERSION].token);
 172
 173                 /*
 174                  * Give the user code a chance to study the request and
 175                  * have the opportunity to deny it
 176                  */
 177
 178                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 179                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 180                                                 &wsi->utf8_token[0], NULL, 0)) {
 181                         lwsl_warn("User code denied connection\n");
 182                         goto bail;
 183                 }
 184
 185
 186                 /*
 187                  * Perform the handshake according to the protocol version the
 188                  * client announced
 189                  */
 190
 191                 switch (wsi->ietf_spec_revision) {
 192                 case 13:
 193                         lwsl_parser("libwebsocket_parse calling handshake_04\n");
 194                         if (handshake_0405(context, wsi)) {
 195                                 lwsl_info("handshake_0405 xor 05 has failed the connection\n");
 196                                 goto bail;
 197                         }
 198                         break;
 199
 200                 default:
 201                         lwsl_warn("Unknown client spec version %d\n",
 202                                                        wsi->ietf_spec_revision);
 203                         goto bail;
 204                 }
 205
 206                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 207
 208                 /* union transition */
 209                 memset(&wsi->u, 0, sizeof wsi->u);
 210
 211                 lwsl_parser("accepted v%02d connection\n",
 212                                                        wsi->ietf_spec_revision);
 213 #endif
 214                 break;
 215
 216         case WSI_STATE_AWAITING_CLOSE_ACK:
 217         case WSI_STATE_ESTABLISHED:
 218 #ifndef LWS_NO_CLIENT
 219                 switch (wsi->mode) {
 220                 case LWS_CONNMODE_WS_CLIENT:
 221                         for (n = 0; n < len; n++)
 222                                 if (libwebsocket_client_rx_sm(wsi, *buf++) < 0) {
 223                                         lwsl_info("client rx has bailed\n");
 224                                         goto bail;
 225                                 }
 226
 227                         return 0;
 228                 default:
 229                         break;
 230                 }
 231 #endif
 232 #ifndef LWS_NO_SERVER
 233                 /* LWS_CONNMODE_WS_SERVING */
 234
 235                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 236                         lwsl_info("interpret_incoming_packet has bailed\n");
 237                         goto bail;
 238                 }
 239 #endif
 240                 break;
 241         default:
 242                 lwsl_err("libwebsocket_read: Unhandled state\n");
 243                 break;
 244         }
 245
 246         return 0;
 247
 248 bail:
 249         lwsl_info("closing connection at libwebsocket_read bail:\n");
 250         libwebsocket_close_and_free_session(context, wsi,
 251                                                      LWS_CLOSE_STATUS_NOSTATUS);
 252
 253         return -1;
 254 }