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 #ifndef LWS_NO_SERVER
  57 extern int handshake_0405(struct libwebsocket_context *context, struct libwebsocket *wsi);
  58 #endif
  59
  60 int
  61 libwebsocket_read(struct libwebsocket_context *context,
  62                      struct libwebsocket *wsi, unsigned char * buf, size_t len)
  63 {
  64         size_t n;
  65
  66         switch (wsi->state) {
  67         case WSI_STATE_HTTP_ISSUING_FILE:
  68         case WSI_STATE_HTTP:
  69                 wsi->state = WSI_STATE_HTTP_HEADERS;
  70                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
  71                 wsi->u.hdr.lextable_pos = 0;
  72                 /* fallthru */
  73         case WSI_STATE_HTTP_HEADERS:
  74
  75                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
  76 #ifdef _DEBUG
  77                 //fwrite(buf, 1, len, stderr);
  78 #endif
  79
  80 #ifndef LWS_NO_CLIENT
  81
  82 //              lwsl_info("mode=%d\n", wsi->mode);
  83
  84                 switch (wsi->mode) {
  85                 case LWS_CONNMODE_WS_CLIENT_WAITING_PROXY_REPLY:
  86                 case LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE:
  87                 case LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY:
  88                 case LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT:
  89                 case LWS_CONNMODE_WS_CLIENT:
  90                         for (n = 0; n < len; n++)
  91                                 if (libwebsocket_client_rx_sm(wsi, *buf++)) {
  92                                         lwsl_info("libwebsocket_client_rx_sm failed\n");
  93                                         goto bail;
  94                                 }
  95                         return 0;
  96                 default:
  97                         break;
  98                 }
  99 #endif
 100 #ifndef LWS_NO_SERVER
 101                 /* LWS_CONNMODE_WS_SERVING */
 102
 103                 for (n = 0; n < len; n++)
 104                         if (libwebsocket_parse(wsi, *buf++)) {
 105                                 lwsl_info("libwebsocket_parse failed\n");
 106                                 goto bail;
 107                         }
 108
 109                 if (wsi->u.hdr.parser_state != WSI_PARSING_COMPLETE)
 110                         break;
 111
 112                 lwsl_parser("libwebsocket_parse sees parsing complete\n");
 113
 114                 /* is this websocket protocol or normal http 1.0? */
 115
 116                 if (!wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
 117                              !wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len) {
 118                         wsi->state = WSI_STATE_HTTP;
 119                         if (wsi->protocol->callback)
 120                                 if (wsi->protocol->callback(context, wsi,
 121                                                 LWS_CALLBACK_HTTP,
 122                                                 wsi->user_space,
 123                                                 wsi->utf8_token[WSI_TOKEN_GET_URI].token,
 124                                                 wsi->utf8_token[WSI_TOKEN_GET_URI].token_len)) {
 125                                         lwsl_info("LWS_CALLBACK_HTTP wanted to close\n");
 126                                         goto bail;
 127                                 }
 128                         return 0;
 129                 }
 130
 131                 if (!wsi->protocol)
 132                         lwsl_err("NULL protocol at libwebsocket_read\n");
 133
 134
 135                 /*
 136                  * It's websocket
 137                  *
 138                  * Make sure user side is happy about protocol
 139                  */
 140
 141                 while (wsi->protocol->callback) {
 142
 143                         if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL) {
 144                                 if (wsi->protocol->name == NULL)
 145                                         break;
 146                         } else
 147                                 if (wsi->protocol->name && strcmp(
 148                                      wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 149                                                       wsi->protocol->name) == 0)
 150                                         break;
 151
 152                         wsi->protocol++;
 153                 }
 154
 155                 /* we didn't find a protocol he wanted? */
 156
 157                 if (wsi->protocol->callback == NULL) {
 158                         if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL) {
 159                                 lwsl_info("[no protocol] "
 160                                         "mapped to protocol 0 handler\n");
 161                                 wsi->protocol = &context->protocols[0];
 162                         } else {
 163                                 lwsl_err("Requested protocol %s "
 164                                                 "not supported\n",
 165                                      wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 166                                 goto bail;
 167                         }
 168                 }
 169
 170                 /*
 171                  * find out which spec version the client is using
 172                  * if this header is not given, we default to 00 (aka 76)
 173                  */
 174
 175                 if (wsi->utf8_token[WSI_TOKEN_VERSION].token_len)
 176                         wsi->ietf_spec_revision =
 177                                  atoi(wsi->utf8_token[WSI_TOKEN_VERSION].token);
 178
 179                 /*
 180                  * Give the user code a chance to study the request and
 181                  * have the opportunity to deny it
 182                  */
 183
 184                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 185                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 186                                                 &wsi->utf8_token[0], NULL, 0)) {
 187                         lwsl_warn("User code denied connection\n");
 188                         goto bail;
 189                 }
 190
 191
 192                 /*
 193                  * Perform the handshake according to the protocol version the
 194                  * client announced
 195                  */
 196
 197                 switch (wsi->ietf_spec_revision) {
 198                 case 13:
 199                         lwsl_parser("libwebsocket_parse calling handshake_04\n");
 200                         if (handshake_0405(context, wsi)) {
 201                                 lwsl_info("handshake_0405 xor 05 has failed the connection\n");
 202                                 goto bail;
 203                         }
 204                         break;
 205
 206                 default:
 207                         lwsl_warn("Unknown client spec version %d\n",
 208                                                        wsi->ietf_spec_revision);
 209                         goto bail;
 210                 }
 211
 212                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 213
 214                 /* union transition */
 215                 memset(&wsi->u, 0, sizeof wsi->u);
 216
 217                 lwsl_parser("accepted v%02d connection\n",
 218                                                        wsi->ietf_spec_revision);
 219 #endif
 220                 break;
 221
 222         case WSI_STATE_AWAITING_CLOSE_ACK:
 223         case WSI_STATE_ESTABLISHED:
 224 #ifndef LWS_NO_CLIENT
 225                 switch (wsi->mode) {
 226                 case LWS_CONNMODE_WS_CLIENT:
 227                         for (n = 0; n < len; n++)
 228                                 if (libwebsocket_client_rx_sm(wsi, *buf++) < 0) {
 229                                         lwsl_info("client rx has bailed\n");
 230                                         goto bail;
 231                                 }
 232
 233                         return 0;
 234                 default:
 235                         break;
 236                 }
 237 #endif
 238 #ifndef LWS_NO_SERVER
 239                 /* LWS_CONNMODE_WS_SERVING */
 240
 241                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 242                         lwsl_info("interpret_incoming_packet has bailed\n");
 243                         goto bail;
 244                 }
 245 #endif
 246                 break;
 247         default:
 248                 lwsl_err("libwebsocket_read: Unhandled state\n");
 249                 break;
 250         }
 251
 252         return 0;
 253
 254 bail:
 255         lwsl_info("closing connection at libwebsocket_read bail:\n");
 256         libwebsocket_close_and_free_session(context, wsi,
 257                                                      LWS_CLOSE_STATUS_NOSTATUS);
 258
 259         return -1;
 260 }