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 (!lws_hdr_total_length(wsi, WSI_TOKEN_UPGRADE) ||
 117                              !lws_hdr_total_length(wsi, WSI_TOKEN_CONNECTION)) {
 118                         wsi->state = WSI_STATE_HTTP;
 119                         n = 0;
 120                         if (wsi->protocol->callback)
 121                                 n = wsi->protocol->callback(context, wsi,
 122                                                 LWS_CALLBACK_HTTP,
 123                                                 wsi->user_space,
 124                                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI),
 125                                                 lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI));
 126
 127                         /* drop the header info */
 128                         if (wsi->u.hdr.ah)
 129                                 free(wsi->u.hdr.ah);
 130
 131                         if (n) {
 132                                 lwsl_info("LWS_CALLBACK_HTTP wanted to close\n");
 133                                 goto bail;
 134                         }
 135
 136                         return 0;
 137                 }
 138
 139                 if (!wsi->protocol)
 140                         lwsl_err("NULL protocol at libwebsocket_read\n");
 141
 142                 /*
 143                  * It's websocket
 144                  *
 145                  * Make sure user side is happy about protocol
 146                  */
 147
 148                 while (wsi->protocol->callback) {
 149
 150                         if (!lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL)) {
 151                                 if (wsi->protocol->name == NULL)
 152                                         break;
 153                         } else
 154                                 if (wsi->protocol->name && strcmp(
 155                                         lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL),
 156                                                       wsi->protocol->name) == 0)
 157                                         break;
 158
 159                         wsi->protocol++;
 160                 }
 161
 162                 /* we didn't find a protocol he wanted? */
 163
 164                 if (wsi->protocol->callback == NULL) {
 165                         if (lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL) == NULL) {
 166                                 lwsl_info("[no protocol] "
 167                                         "mapped to protocol 0 handler\n");
 168                                 wsi->protocol = &context->protocols[0];
 169                         } else {
 170                                 lwsl_err("Requested protocol %s "
 171                                                 "not supported\n",
 172                                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL));
 173                                 goto bail;
 174                         }
 175                 }
 176
 177                 /*
 178                  * Give the user code a chance to study the request and
 179                  * have the opportunity to deny it
 180                  */
 181
 182                 if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
 183                                 LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
 184                                 lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL),
 185                                                                      NULL, 0)) {
 186                         lwsl_warn("User code denied connection\n");
 187                         goto bail;
 188                 }
 189
 190
 191                 /*
 192                  * Perform the handshake according to the protocol version the
 193                  * client announced
 194                  */
 195
 196                 switch (wsi->ietf_spec_revision) {
 197                 case 13:
 198                         lwsl_parser("libwebsocket_parse calling handshake_04\n");
 199                         if (handshake_0405(context, wsi)) {
 200                                 lwsl_info("handshake_0405 xor 05 has failed the connection\n");
 201                                 goto bail;
 202                         }
 203                         break;
 204
 205                 default:
 206                         lwsl_warn("Unknown client spec version %d\n",
 207                                                        wsi->ietf_spec_revision);
 208                         goto bail;
 209                 }
 210
 211                 /* drop the header info */
 212
 213                 if (wsi->u.hdr.ah)
 214                         free(wsi->u.hdr.ah);
 215
 216                 wsi->mode = LWS_CONNMODE_WS_SERVING;
 217
 218                 /* union transition */
 219                 memset(&wsi->u, 0, sizeof wsi->u);
 220
 221                 /*
 222                  * create the frame buffer for this connection according to the
 223                  * size mentioned in the protocol definition.  If 0 there, use
 224                  * a big default for compatibility
 225                  */
 226
 227                 n = wsi->protocol->rx_buffer_size;
 228                 if (!n)
 229                         n = LWS_MAX_SOCKET_IO_BUF;
 230                 n += LWS_SEND_BUFFER_PRE_PADDING + LWS_SEND_BUFFER_POST_PADDING;
 231                 wsi->u.ws.rx_user_buffer = malloc(n);
 232                 if (!wsi->u.ws.rx_user_buffer) {
 233                         lwsl_err("Out of Mem allocating rx buffer %d\n", n);
 234                         goto bail;
 235                 }
 236                 lwsl_info("Allocating RX buffer %d\n", n);
 237
 238                 lwsl_parser("accepted v%02d connection\n",
 239                                                        wsi->ietf_spec_revision);
 240 #endif
 241                 break;
 242
 243         case WSI_STATE_AWAITING_CLOSE_ACK:
 244         case WSI_STATE_ESTABLISHED:
 245 #ifndef LWS_NO_CLIENT
 246                 switch (wsi->mode) {
 247                 case LWS_CONNMODE_WS_CLIENT:
 248                         for (n = 0; n < len; n++)
 249                                 if (libwebsocket_client_rx_sm(wsi, *buf++) < 0) {
 250                                         lwsl_info("client rx has bailed\n");
 251                                         goto bail;
 252                                 }
 253
 254                         return 0;
 255                 default:
 256                         break;
 257                 }
 258 #endif
 259 #ifndef LWS_NO_SERVER
 260                 /* LWS_CONNMODE_WS_SERVING */
 261
 262                 if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0) {
 263                         lwsl_info("interpret_incoming_packet has bailed\n");
 264                         goto bail;
 265                 }
 266 #endif
 267                 break;
 268         default:
 269                 lwsl_err("libwebsocket_read: Unhandled state\n");
 270                 break;
 271         }
 272
 273         return 0;
 274
 275 bail:
 276         lwsl_info("closing connection at libwebsocket_read bail:\n");
 277
 278         libwebsocket_close_and_free_session(context, wsi,
 279                                                      LWS_CLOSE_STATUS_NOSTATUS);
 280
 281         return -1;
 282 }