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
  73 #ifndef LWS_NO_CLIENT
  74                 switch (wsi->mode) {
  75                 case LWS_CONNMODE_WS_CLIENT_WAITING_PROXY_REPLY:
  76                 case LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE:
  77                 case LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY:
  78                 case LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT:
  79                 case LWS_CONNMODE_WS_CLIENT:
  80                         for (n = 0; n < len; n++)
  81                                 if (libwebsocket_client_rx_sm(wsi, *buf++)) {
  82                                         lwsl_info("client_rx_sm failed\n");
  83                                         goto bail;
  84                                 }
  85                         return 0;
  86                 default:
  87                         break;
  88                 }
  89 #endif
  90 #ifndef LWS_NO_SERVER
  91                 /* LWS_CONNMODE_WS_SERVING */
  92
  93                 for (n = 0; n < len; n++)
  94                         if (libwebsocket_parse(wsi, *buf++)) {
  95                                 lwsl_info("libwebsocket_parse failed\n");
  96                                 goto bail;
  97                         }
  98
  99                 if (wsi->u.hdr.parser_state != WSI_PARSING_COMPLETE)
 100                         break;
 101
 102                 lwsl_parser("libwebsocket_parse sees parsing complete\n");
 103
 104                 /* is this websocket protocol or normal http 1.0? */
 105
 106                 if (!lws_hdr_total_length(wsi, WSI_TOKEN_UPGRADE) ||
 107                              !lws_hdr_total_length(wsi, WSI_TOKEN_CONNECTION)) {
 108
 109                         /* it's not websocket.... shall we accept it as http? */
 110
 111                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI)) {
 112                                 lwsl_warn("Missing URI in HTTP request\n");
 113                                 /* drop the header info */
 114                                 if (wsi->u.hdr.ah)
 115                                         free(wsi->u.hdr.ah);
 116                                 goto bail;
 117                         }
 118
 119                         lwsl_info("HTTP request for '%s'\n", lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI));
 120
 121                         if (libwebsocket_ensure_user_space(wsi) == NULL) {
 122                                 /* drop the header info */
 123                                 if (wsi->u.hdr.ah)
 124                                         free(wsi->u.hdr.ah);
 125                                 goto bail;
 126                         }
 127
 128                         wsi->state = WSI_STATE_HTTP;
 129                         n = 0;
 130                         if (wsi->protocol->callback)
 131                                 n = wsi->protocol->callback(context, wsi,
 132                                     LWS_CALLBACK_HTTP,
 133                                     wsi->user_space,
 134                                     lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI),
 135                                   lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI));
 136
 137                         /* drop the header info */
 138                         if (wsi->u.hdr.ah)
 139                                 free(wsi->u.hdr.ah);
 140
 141                         if (n) {
 142                                 lwsl_info("LWS_CALLBACK_HTTP closing\n");
 143                                 goto bail;
 144                         }
 145
 146                         return 0;
 147                 }
 148
 149                 if (!wsi->protocol)
 150                         lwsl_err("NULL protocol at libwebsocket_read\n");
 151
 152                 /*
 153                  * It's websocket
 154                  *
 155                  * Make sure user side is happy about protocol
 156                  */
 157
 158                 while (wsi->protocol->callback) {
 159
 160                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL)) {
 161                                 if (wsi->protocol->name == NULL)
 162                                         break;
 163                         } else
 164                                 if (wsi->protocol->name && strcmp(
 165                                         lws_hdr_simple_ptr(wsi,
 166                                                 WSI_TOKEN_PROTOCOL),
 167                                                       wsi->protocol->name) == 0)
 168                                         break;
 169
 170                         wsi->protocol++;
 171                 }
 172
 173                 /* we didn't find a protocol he wanted? */
 174
 175                 if (wsi->protocol->callback == NULL) {
 176                         if (lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL) ==
 177                                                                          NULL) {
 178                                 lwsl_info("no protocol -> prot 0 handler\n");
 179                                 wsi->protocol = &context->protocols[0];
 180                         } else {
 181                                 lwsl_err("Req protocol %s not supported\n",
 182                                    lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL));
 183                                 goto bail;
 184                         }
 185                 }
 186
 187                 /*
 188                  * Give the user code a chance to study the request and
 189                  * have the opportunity to deny it
 190                  */
 191
 192                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 193                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 194                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL),
 195                                                                      NULL, 0)) {
 196                         lwsl_warn("User code denied connection\n");
 197                         goto bail;
 198                 }
 199
 200
 201                 /*
 202                  * Perform the handshake according to the protocol version the
 203                  * client announced
 204                  */
 205
 206                 switch (wsi->ietf_spec_revision) {
 207                 case 13:
 208                         lwsl_parser("lws_parse calling handshake_04\n");
 209                         if (handshake_0405(context, wsi)) {
 210                                 lwsl_info("hs0405 has failed the connection\n");
 211                                 goto bail;
 212                         }
 213                         break;
 214
 215                 default:
 216                         lwsl_warn("Unknown client spec version %d\n",
 217                                                        wsi->ietf_spec_revision);
 218                         goto bail;
 219                 }
 220
 221                 /* drop the header info */
 222
 223                 if (wsi->u.hdr.ah)
 224                         free(wsi->u.hdr.ah);
 225
 226                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 227
 228                 /* union transition */
 229                 memset(&wsi->u, 0, sizeof(wsi->u));
 230
 231                 /*
 232                  * create the frame buffer for this connection according to the
 233                  * size mentioned in the protocol definition.  If 0 there, use
 234                  * a big default for compatibility
 235                  */
 236
 237                 n = wsi->protocol->rx_buffer_size;
 238                 if (!n)
 239                         n = LWS_MAX_SOCKET_IO_BUF;
 240                 n += LWS_SEND_BUFFER_PRE_PADDING + LWS_SEND_BUFFER_POST_PADDING;
 241                 wsi->u.ws.rx_user_buffer = malloc(n);
 242                 if (!wsi->u.ws.rx_user_buffer) {
 243                         lwsl_err("Out of Mem allocating rx buffer %d\n", n);
 244                         goto bail;
 245                 }
 246                 lwsl_info("Allocating RX buffer %d\n", n);
 247
 248                 lwsl_parser("accepted v%02d connection\n",
 249                                                        wsi->ietf_spec_revision);
 250 #endif
 251                 break;
 252
 253         case WSI_STATE_AWAITING_CLOSE_ACK:
 254         case WSI_STATE_ESTABLISHED:
 255 #ifndef LWS_NO_CLIENT
 256                 switch (wsi->mode) {
 257                 case LWS_CONNMODE_WS_CLIENT:
 258                         for (n = 0; n < len; n++)
 259                                 if (libwebsocket_client_rx_sm(
 260                                                              wsi, *buf++) < 0) {
 261                                         lwsl_info("client rx has bailed\n");
 262                                         goto bail;
 263                                 }
 264
 265                         return 0;
 266                 default:
 267                         break;
 268                 }
 269 #endif
 270 #ifndef LWS_NO_SERVER
 271                 /* LWS_CONNMODE_WS_SERVING */
 272
 273                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 274                         lwsl_info("interpret_incoming_packet has bailed\n");
 275                         goto bail;
 276                 }
 277 #endif
 278                 break;
 279         default:
 280                 lwsl_err("libwebsocket_read: Unhandled state\n");
 281                 break;
 282         }
 283
 284         return 0;
 285
 286 bail:
 287         lwsl_info("closing connection at libwebsocket_read bail:\n");
 288
 289         libwebsocket_close_and_free_session(context, wsi,
 290                                                      LWS_CLOSE_STATUS_NOSTATUS);
 291
 292         return -1;
 293 }