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         struct allocated_headers *ah;
  62         char *uri_ptr;
  63         int uri_len;
  64
  65         switch (wsi->state) {
  66         case WSI_STATE_HTTP_ISSUING_FILE:
  67         case WSI_STATE_HTTP:
  68                 wsi->state = WSI_STATE_HTTP_HEADERS;
  69                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
  70                 wsi->u.hdr.lextable_pos = 0;
  71                 /* fallthru */
  72         case WSI_STATE_HTTP_HEADERS:
  73
  74                 lwsl_parser("issuing %d bytes to parser\n", (int)len);
  75
  76 #ifndef LWS_NO_CLIENT
  77                 switch (wsi->mode) {
  78                 case LWS_CONNMODE_WS_CLIENT_WAITING_PROXY_REPLY:
  79                 case LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE:
  80                 case LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY:
  81                 case LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT:
  82                 case LWS_CONNMODE_WS_CLIENT:
  83                         for (n = 0; n < len; n++)
  84                                 if (libwebsocket_client_rx_sm(wsi, *buf++)) {
  85                                         lwsl_info("client_rx_sm failed\n");
  86                                         goto bail;
  87                                 }
  88                         return 0;
  89                 default:
  90                         break;
  91                 }
  92 #endif
  93 #ifndef LWS_NO_SERVER
  94                 /* LWS_CONNMODE_WS_SERVING */
  95
  96                 for (n = 0; n < len; n++)
  97                         if (libwebsocket_parse(wsi, *buf++)) {
  98                                 lwsl_info("libwebsocket_parse failed\n");
  99                                 goto bail;
 100                         }
 101
 102                 if (wsi->u.hdr.parser_state != WSI_PARSING_COMPLETE)
 103                         break;
 104
 105                 lwsl_parser("libwebsocket_parse sees parsing complete\n");
 106
 107                 /* is this websocket protocol or normal http 1.0? */
 108
 109                 if (!lws_hdr_total_length(wsi, WSI_TOKEN_UPGRADE) ||
 110                              !lws_hdr_total_length(wsi, WSI_TOKEN_CONNECTION)) {
 111
 112                         /* it's not websocket.... shall we accept it as http? */
 113
 114                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI)) {
 115                                 lwsl_warn("Missing URI in HTTP request\n");
 116                                 /* drop the header info */
 117                                 if (wsi->u.hdr.ah)
 118                                         free(wsi->u.hdr.ah);
 119                                 goto bail;
 120                         }
 121
 122                         lwsl_info("HTTP request for '%s'\n",
 123                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI));
 124
 125                         if (libwebsocket_ensure_user_space(wsi) == NULL) {
 126                                 /* drop the header info */
 127                                 if (wsi->u.hdr.ah)
 128                                         free(wsi->u.hdr.ah);
 129                                 goto bail;
 130                         }
 131
 132                         /*
 133                          * Hm we still need the headers so the
 134                          * callback can look at leaders like the URI, but we
 135                          * need to transition to http union state.... hold a
 136                          * copy of u.hdr.ah and deallocate afterwards
 137                          */
 138
 139                         ah = wsi->u.hdr.ah;
 140                         uri_ptr = lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI);
 141                         uri_len = lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI);
 142
 143                         /* union transition */
 144                         memset(&wsi->u, 0, sizeof(wsi->u));
 145
 146                         wsi->state = WSI_STATE_HTTP;
 147                         n = 0;
 148                         if (wsi->protocol->callback)
 149                                 n = wsi->protocol->callback(context, wsi,
 150                                     LWS_CALLBACK_HTTP,
 151                                     wsi->user_space, uri_ptr, uri_len);
 152
 153                         /* now drop the header info we kept a pointer to */
 154                         if (ah)
 155                                 free(ah);
 156
 157                         if (n) {
 158                                 lwsl_info("LWS_CALLBACK_HTTP closing\n");
 159                                 goto bail;
 160                         }
 161
 162                         return 0;
 163                 }
 164
 165                 if (!wsi->protocol)
 166                         lwsl_err("NULL protocol at libwebsocket_read\n");
 167
 168                 /*
 169                  * It's websocket
 170                  *
 171                  * Make sure user side is happy about protocol
 172                  */
 173
 174                 while (wsi->protocol->callback) {
 175
 176                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL)) {
 177                                 if (wsi->protocol->name == NULL)
 178                                         break;
 179                         } else
 180                                 if (wsi->protocol->name && strcmp(
 181                                         lws_hdr_simple_ptr(wsi,
 182                                                 WSI_TOKEN_PROTOCOL),
 183                                                       wsi->protocol->name) == 0)
 184                                         break;
 185
 186                         wsi->protocol++;
 187                 }
 188
 189                 /* we didn't find a protocol he wanted? */
 190
 191                 if (wsi->protocol->callback == NULL) {
 192                         if (lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL) ==
 193                                                                          NULL) {
 194                                 lwsl_info("no protocol -> prot 0 handler\n");
 195                                 wsi->protocol = &context->protocols[0];
 196                         } else {
 197                                 lwsl_err("Req protocol %s not supported\n",
 198                                    lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL));
 199                                 goto bail;
 200                         }
 201                 }
 202
 203                 /*
 204                  * Give the user code a chance to study the request and
 205                  * have the opportunity to deny it
 206                  */
 207
 208                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 209                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 210                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL),
 211                                                                      NULL, 0)) {
 212                         lwsl_warn("User code denied connection\n");
 213                         goto bail;
 214                 }
 215
 216
 217                 /*
 218                  * Perform the handshake according to the protocol version the
 219                  * client announced
 220                  */
 221
 222                 switch (wsi->ietf_spec_revision) {
 223                 case 13:
 224                         lwsl_parser("lws_parse calling handshake_04\n");
 225                         if (handshake_0405(context, wsi)) {
 226                                 lwsl_info("hs0405 has failed the connection\n");
 227                                 goto bail;
 228                         }
 229                         break;
 230
 231                 default:
 232                         lwsl_warn("Unknown client spec version %d\n",
 233                                                        wsi->ietf_spec_revision);
 234                         goto bail;
 235                 }
 236
 237                 /* drop the header info */
 238
 239                 if (wsi->u.hdr.ah)
 240                         free(wsi->u.hdr.ah);
 241
 242                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 243
 244                 /* union transition */
 245                 memset(&wsi->u, 0, sizeof(wsi->u));
 246
 247                 /*
 248                  * create the frame buffer for this connection according to the
 249                  * size mentioned in the protocol definition.  If 0 there, use
 250                  * a big default for compatibility
 251                  */
 252
 253                 n = wsi->protocol->rx_buffer_size;
 254                 if (!n)
 255                         n = LWS_MAX_SOCKET_IO_BUF;
 256                 n += LWS_SEND_BUFFER_PRE_PADDING + LWS_SEND_BUFFER_POST_PADDING;
 257                 wsi->u.ws.rx_user_buffer = malloc(n);
 258                 if (!wsi->u.ws.rx_user_buffer) {
 259                         lwsl_err("Out of Mem allocating rx buffer %d\n", n);
 260                         goto bail;
 261                 }
 262                 lwsl_info("Allocating RX buffer %d\n", n);
 263
 264                 lwsl_parser("accepted v%02d connection\n",
 265                                                        wsi->ietf_spec_revision);
 266 #endif
 267                 break;
 268
 269         case WSI_STATE_AWAITING_CLOSE_ACK:
 270         case WSI_STATE_ESTABLISHED:
 271 #ifndef LWS_NO_CLIENT
 272                 switch (wsi->mode) {
 273                 case LWS_CONNMODE_WS_CLIENT:
 274                         for (n = 0; n < len; n++)
 275                                 if (libwebsocket_client_rx_sm(
 276                                                              wsi, *buf++) < 0) {
 277                                         lwsl_info("client rx has bailed\n");
 278                                         goto bail;
 279                                 }
 280
 281                         return 0;
 282                 default:
 283                         break;
 284                 }
 285 #endif
 286 #ifndef LWS_NO_SERVER
 287                 /* LWS_CONNMODE_WS_SERVING */
 288
 289                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 290                         lwsl_info("interpret_incoming_packet has bailed\n");
 291                         goto bail;
 292                 }
 293 #endif
 294                 break;
 295         default:
 296                 lwsl_err("libwebsocket_read: Unhandled state\n");
 297                 break;
 298         }
 299
 300         return 0;
 301
 302 bail:
 303         lwsl_info("closing connection at libwebsocket_read bail:\n");
 304
 305         libwebsocket_close_and_free_session(context, wsi,
 306                                                      LWS_CLOSE_STATUS_NOSTATUS);
 307
 308         return -1;
 309 }