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 LWS_VISIBLE 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_nuke_ah;
 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                 wsi->mode = LWS_CONNMODE_PRE_WS_SERVING_ACCEPT;
 108
 109                 /* is this websocket protocol or normal http 1.0? */
 110
 111                 if (!lws_hdr_total_length(wsi, WSI_TOKEN_UPGRADE) ||
 112                              !lws_hdr_total_length(wsi, WSI_TOKEN_CONNECTION)) {
 113
 114                         /* it's not websocket.... shall we accept it as http? */
 115
 116                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI)) {
 117                                 lwsl_warn("Missing URI in HTTP request\n");
 118                                 goto bail_nuke_ah;
 119                         }
 120
 121                         lwsl_info("HTTP request for '%s'\n",
 122                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI));
 123
 124                         if (libwebsocket_ensure_user_space(wsi))
 125                                 goto bail_nuke_ah;
 126
 127                         /*
 128                          * Hm we still need the headers so the
 129                          * callback can look at leaders like the URI, but we
 130                          * need to transition to http union state.... hold a
 131                          * copy of u.hdr.ah and deallocate afterwards
 132                          */
 133
 134                         ah = wsi->u.hdr.ah;
 135                         uri_ptr = lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI);
 136                         uri_len = lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI);
 137
 138                         /* union transition */
 139                         memset(&wsi->u, 0, sizeof(wsi->u));
 140
 141                         wsi->mode = LWS_CONNMODE_HTTP_SERVING_ACCEPTED;
 142                         wsi->state = WSI_STATE_HTTP;
 143                         n = 0;
 144                         if (wsi->protocol->callback)
 145                                 n = wsi->protocol->callback(context, wsi,
 146                                     LWS_CALLBACK_HTTP,
 147                                     wsi->user_space, uri_ptr, uri_len);
 148
 149                         /* now drop the header info we kept a pointer to */
 150                         if (ah)
 151                                 free(ah);
 152
 153                         if (n) {
 154                                 lwsl_info("LWS_CALLBACK_HTTP closing\n");
 155                                 goto bail;
 156                         }
 157
 158                         return 0;
 159                 }
 160
 161                 if (!wsi->protocol)
 162                         lwsl_err("NULL protocol at libwebsocket_read\n");
 163
 164                 /*
 165                  * It's websocket
 166                  *
 167                  * Make sure user side is happy about protocol
 168                  */
 169
 170                 while (wsi->protocol->callback) {
 171
 172                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL)) {
 173                                 if (wsi->protocol->name == NULL)
 174                                         break;
 175                         } else
 176                                 if (wsi->protocol->name && strcmp(
 177                                         lws_hdr_simple_ptr(wsi,
 178                                                 WSI_TOKEN_PROTOCOL),
 179                                                       wsi->protocol->name) == 0)
 180                                         break;
 181
 182                         wsi->protocol++;
 183                 }
 184
 185                 /* we didn't find a protocol he wanted? */
 186
 187                 if (wsi->protocol->callback == NULL) {
 188                         if (lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL) ==
 189                                                                          NULL) {
 190                                 lwsl_info("no protocol -> prot 0 handler\n");
 191                                 wsi->protocol = &context->protocols[0];
 192                         } else {
 193                                 lwsl_err("Req protocol %s not supported\n",
 194                                    lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL));
 195                                 goto bail_nuke_ah;
 196                         }
 197                 }
 198
 199                 /*
 200                  * Give the user code a chance to study the request and
 201                  * have the opportunity to deny it
 202                  */
 203
 204                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 205                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 206                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL),
 207                                                                      NULL, 0)) {
 208                         lwsl_warn("User code denied connection\n");
 209                         goto bail;
 210                 }
 211
 212
 213                 /*
 214                  * Perform the handshake according to the protocol version the
 215                  * client announced
 216                  */
 217
 218                 switch (wsi->ietf_spec_revision) {
 219                 case 13:
 220                         lwsl_parser("lws_parse calling handshake_04\n");
 221                         if (handshake_0405(context, wsi)) {
 222                                 lwsl_info("hs0405 has failed the connection\n");
 223                                 goto bail;
 224                         }
 225                         break;
 226
 227                 default:
 228                         lwsl_warn("Unknown client spec version %d\n",
 229                                                        wsi->ietf_spec_revision);
 230                         goto bail;
 231                 }
 232
 233                 /* drop the header info */
 234
 235                 if (wsi->u.hdr.ah)
 236                         free(wsi->u.hdr.ah);
 237
 238                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 239
 240                 /* union transition */
 241                 memset(&wsi->u, 0, sizeof(wsi->u));
 242                 wsi->u.ws.rxflow_change_to = LWS_RXFLOW_ALLOW;
 243
 244                 /*
 245                  * create the frame buffer for this connection according to the
 246                  * size mentioned in the protocol definition.  If 0 there, use
 247                  * a big default for compatibility
 248                  */
 249
 250                 n = wsi->protocol->rx_buffer_size;
 251                 if (!n)
 252                         n = LWS_MAX_SOCKET_IO_BUF;
 253                 n += LWS_SEND_BUFFER_PRE_PADDING + LWS_SEND_BUFFER_POST_PADDING;
 254                 wsi->u.ws.rx_user_buffer = malloc(n);
 255                 if (!wsi->u.ws.rx_user_buffer) {
 256                         lwsl_err("Out of Mem allocating rx buffer %d\n", n);
 257                         goto bail;
 258                 }
 259                 lwsl_info("Allocating RX buffer %d\n", n);
 260
 261                 if (setsockopt(wsi->sock, SOL_SOCKET, SO_SNDBUF,  &n, sizeof n)) {
 262                         lwsl_warn("Failed to set SNDBUF to %d", n);
 263                         goto bail;
 264                 }
 265
 266                 lwsl_parser("accepted v%02d connection\n",
 267                                                        wsi->ietf_spec_revision);
 268 #endif
 269                 break;
 270
 271         case WSI_STATE_AWAITING_CLOSE_ACK:
 272         case WSI_STATE_ESTABLISHED:
 273 #ifndef LWS_NO_CLIENT
 274                 switch (wsi->mode) {
 275                 case LWS_CONNMODE_WS_CLIENT:
 276                         for (n = 0; n < len; n++)
 277                                 if (libwebsocket_client_rx_sm(
 278                                                              wsi, *buf++) < 0) {
 279                                         lwsl_info("client rx has bailed\n");
 280                                         goto bail;
 281                                 }
 282
 283                         return 0;
 284                 default:
 285                         break;
 286                 }
 287 #endif
 288 #ifndef LWS_NO_SERVER
 289                 /* LWS_CONNMODE_WS_SERVING */
 290
 291                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 292                         lwsl_info("interpret_incoming_packet has bailed\n");
 293                         goto bail;
 294                 }
 295 #endif
 296                 break;
 297         default:
 298                 lwsl_err("libwebsocket_read: Unhandled state\n");
 299                 break;
 300         }
 301
 302         return 0;
 303
 304 bail_nuke_ah:
 305         /* drop the header info */
 306         if (wsi->u.hdr.ah)
 307                 free(wsi->u.hdr.ah);
 308
 309 bail:
 310         lwsl_info("closing connection at libwebsocket_read bail:\n");
 311
 312         libwebsocket_close_and_free_session(context, wsi,
 313                                                      LWS_CLOSE_STATUS_NOSTATUS);
 314
 315         return -1;
 316 }