src/modules/m_websocket.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2016 Attila Molnar <attilamolnar@hush.com>
   5  *
   6  * This file is part of InspIRCd.  InspIRCd is free software: you can
   7  * redistribute it and/or modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation, version 2.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  13  * details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 /// $CompilerFlags: -Ivendor_directory("utfcpp")
  20
  21
  22 #include "inspircd.h"
  23 #include "iohook.h"
  24 #include "modules/hash.h"
  25
  26 #include <utf8.h>
  27
  28 typedef std::vector<std::string> OriginList;
  29
  30 static const char MagicGUID[] = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
  31 static const char whitespace[] = " \t\r\n";
  32 static dynamic_reference_nocheck<HashProvider>* sha1;
  33
  34 struct WebSocketConfig
  35 {
  36         // The HTTP origins that can connect to the server.
  37         OriginList allowedorigins;
  38
  39         // Whether to trust the X-Real-IP or X-Forwarded-For headers.
  40         bool behindproxy;
  41
  42         // Whether to send as UTF-8 text instead of binary data.
  43         bool sendastext;
  44 };
  45
  46 class WebSocketHookProvider : public IOHookProvider
  47 {
  48  public:
  49         WebSocketConfig config;
  50         WebSocketHookProvider(Module* mod)
  51                 : IOHookProvider(mod, "websocket", IOHookProvider::IOH_UNKNOWN, true)
  52         {
  53         }
  54
  55         void OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server) CXX11_OVERRIDE;
  56
  57         void OnConnect(StreamSocket* sock) CXX11_OVERRIDE
  58         {
  59         }
  60 };
  61
  62 class WebSocketHook : public IOHookMiddle
  63 {
  64         class HTTPHeaderFinder
  65         {
  66                 std::string::size_type bpos;
  67                 std::string::size_type len;
  68
  69          public:
  70                 bool Find(const std::string& req, const char* header, std::string::size_type headerlen, std::string::size_type maxpos)
  71                 {
  72                         std::string::size_type keybegin = req.find(header);
  73                         if ((keybegin == std::string::npos) || (keybegin > maxpos) || (keybegin == 0) || (req[keybegin-1] != '\n'))
  74                                 return false;
  75
  76                         keybegin += headerlen;
  77
  78                         bpos = req.find_first_not_of(whitespace, keybegin, sizeof(whitespace)-1);
  79                         if ((bpos == std::string::npos) || (bpos > maxpos))
  80                                 return false;
  81
  82                         const std::string::size_type epos = req.find_first_of(whitespace, bpos, sizeof(whitespace)-1);
  83                         len = epos - bpos;
  84
  85                         return true;
  86                 }
  87
  88                 std::string ExtractValue(const std::string& req) const
  89                 {
  90                         return std::string(req, bpos, len);
  91                 }
  92         };
  93
  94         enum OpCode
  95         {
  96                 OP_CONTINUATION = 0x00,
  97                 OP_TEXT = 0x01,
  98                 OP_BINARY = 0x02,
  99                 OP_CLOSE = 0x08,
 100                 OP_PING = 0x09,
 101                 OP_PONG = 0x0a
 102         };
 103
 104         enum State
 105         {
 106                 STATE_HTTPREQ,
 107                 STATE_ESTABLISHED
 108         };
 109
 110         static const unsigned char WS_MASKBIT = (1 << 7);
 111         static const unsigned char WS_FINBIT = (1 << 7);
 112         static const unsigned char WS_PAYLOAD_LENGTH_MAGIC_LARGE = 126;
 113         static const unsigned char WS_PAYLOAD_LENGTH_MAGIC_HUGE = 127;
 114         static const size_t WS_MAX_PAYLOAD_LENGTH_SMALL = 125;
 115         static const size_t WS_MAX_PAYLOAD_LENGTH_LARGE = 65535;
 116         static const size_t MAXHEADERSIZE = sizeof(uint64_t) + 2;
 117
 118         // Clients sending ping or pong frames faster than this are killed
 119         static const time_t MINPINGPONGDELAY = 10;
 120
 121         State state;
 122         time_t lastpingpong;
 123         WebSocketConfig& config;
 124
 125         static size_t FillHeader(unsigned char* outbuf, size_t sendlength, OpCode opcode)
 126         {
 127                 size_t pos = 0;
 128                 outbuf[pos++] = WS_FINBIT | opcode;
 129
 130                 if (sendlength <= WS_MAX_PAYLOAD_LENGTH_SMALL)
 131                 {
 132                         outbuf[pos++] = sendlength;
 133                 }
 134                 else if (sendlength <= WS_MAX_PAYLOAD_LENGTH_LARGE)
 135                 {
 136                         outbuf[pos++] = WS_PAYLOAD_LENGTH_MAGIC_LARGE;
 137                         outbuf[pos++] = (sendlength >> 8) & 0xff;
 138                         outbuf[pos++] = sendlength & 0xff;
 139                 }
 140                 else
 141                 {
 142                         outbuf[pos++] = WS_PAYLOAD_LENGTH_MAGIC_HUGE;
 143                         const uint64_t len = sendlength;
 144                         for (int i = sizeof(uint64_t)-1; i >= 0; i--)
 145                                 outbuf[pos++] = ((len >> i*8) & 0xff);
 146                 }
 147
 148                 return pos;
 149         }
 150
 151         static StreamSocket::SendQueue::Element PrepareSendQElem(size_t size, OpCode opcode)
 152         {
 153                 unsigned char header[MAXHEADERSIZE];
 154                 const size_t n = FillHeader(header, size, opcode);
 155
 156                 return StreamSocket::SendQueue::Element(reinterpret_cast<const char*>(header), n);
 157         }
 158
 159         int HandleAppData(StreamSocket* sock, std::string& appdataout, bool allowlarge)
 160         {
 161                 std::string& myrecvq = GetRecvQ();
 162                 // Need 1 byte opcode, minimum 1 byte len, 4 bytes masking key
 163                 if (myrecvq.length() < 6)
 164                         return 0;
 165
 166                 const std::string& cmyrecvq = myrecvq;
 167                 unsigned char len1 = (unsigned char)cmyrecvq[1];
 168                 if (!(len1 & WS_MASKBIT))
 169                 {
 170                         sock->SetError("WebSocket protocol violation: unmasked client frame");
 171                         return -1;
 172                 }
 173
 174                 len1 &= ~WS_MASKBIT;
 175
 176                 // Assume the length is a single byte, if not, update values later
 177                 unsigned int len = len1;
 178                 unsigned int payloadstartoffset = 6;
 179                 const unsigned char* maskkey = reinterpret_cast<const unsigned char*>(&cmyrecvq[2]);
 180
 181                 if (len1 == WS_PAYLOAD_LENGTH_MAGIC_LARGE)
 182                 {
 183                         // allowlarge is false for control frames according to the RFC meaning large pings, etc. are not allowed
 184                         if (!allowlarge)
 185                         {
 186                                 sock->SetError("WebSocket protocol violation: large control frame");
 187                                 return -1;
 188                         }
 189
 190                         // Large frame, has 2 bytes len after the magic byte indicating the length
 191                         // Need 1 byte opcode, 3 bytes len, 4 bytes masking key
 192                         if (myrecvq.length() < 8)
 193                                 return 0;
 194
 195                         unsigned char len2 = (unsigned char)cmyrecvq[2];
 196                         unsigned char len3 = (unsigned char)cmyrecvq[3];
 197                         len = (len2 << 8) | len3;
 198
 199                         if (len <= WS_MAX_PAYLOAD_LENGTH_SMALL)
 200                         {
 201                                 sock->SetError("WebSocket protocol violation: non-minimal length encoding used");
 202                                 return -1;
 203                         }
 204
 205                         maskkey += 2;
 206                         payloadstartoffset += 2;
 207                 }
 208                 else if (len1 == WS_PAYLOAD_LENGTH_MAGIC_HUGE)
 209                 {
 210                         sock->SetError("WebSocket: Huge frames are not supported");
 211                         return -1;
 212                 }
 213
 214                 if (myrecvq.length() < payloadstartoffset + len)
 215                         return 0;
 216
 217                 unsigned int maskkeypos = 0;
 218                 const std::string::iterator endit = myrecvq.begin() + payloadstartoffset + len;
 219                 for (std::string::const_iterator i = myrecvq.begin() + payloadstartoffset; i != endit; ++i)
 220                 {
 221                         const unsigned char c = (unsigned char)*i;
 222                         appdataout.push_back(c ^ maskkey[maskkeypos++]);
 223                         maskkeypos %= 4;
 224                 }
 225
 226                 myrecvq.erase(myrecvq.begin(), endit);
 227                 return 1;
 228         }
 229
 230         int HandlePingPongFrame(StreamSocket* sock, bool isping)
 231         {
 232                 if (lastpingpong + MINPINGPONGDELAY >= ServerInstance->Time())
 233                 {
 234                         sock->SetError("WebSocket: Ping/pong flood");
 235                         return -1;
 236                 }
 237
 238                 lastpingpong = ServerInstance->Time();
 239
 240                 std::string appdata;
 241                 const int result = HandleAppData(sock, appdata, false);
 242                 // If it's a pong stop here regardless of the result so we won't generate a reply
 243                 if ((result <= 0) || (!isping))
 244                         return result;
 245
 246                 StreamSocket::SendQueue::Element elem = PrepareSendQElem(appdata.length(), OP_PONG);
 247                 elem.append(appdata);
 248                 GetSendQ().push_back(elem);
 249
 250                 SocketEngine::ChangeEventMask(sock, FD_ADD_TRIAL_WRITE);
 251                 return 1;
 252         }
 253
 254         int HandleWS(StreamSocket* sock, std::string& destrecvq)
 255         {
 256                 if (GetRecvQ().empty())
 257                         return 0;
 258
 259                 unsigned char opcode = (unsigned char)GetRecvQ().c_str()[0];
 260                 switch (opcode & ~WS_FINBIT)
 261                 {
 262                         case OP_CONTINUATION:
 263                         case OP_TEXT:
 264                         case OP_BINARY:
 265                         {
 266                                 std::string appdata;
 267                                 const int result = HandleAppData(sock, appdata, true);
 268                                 if (result != 1)
 269                                         return result;
 270
 271                                 // Strip out any CR+LF which may have been erroneously sent.
 272                                 for (std::string::const_iterator iter = appdata.begin(); iter != appdata.end(); ++iter)
 273                                 {
 274                                         if (*iter != '\r' && *iter != '\n')
 275                                                 destrecvq.push_back(*iter);
 276                                 }
 277
 278                                 // If we are on the final message of this block append a line terminator.
 279                                 if (opcode & WS_FINBIT)
 280                                         destrecvq.append("\r\n");
 281
 282                                 return 1;
 283                         }
 284
 285                         case OP_PING:
 286                         {
 287                                 return HandlePingPongFrame(sock, true);
 288                         }
 289
 290                         case OP_PONG:
 291                         {
 292                                 // A pong frame may be sent unsolicited, so we have to handle it.
 293                                 // It may carry application data which we need to remove from the recvq as well.
 294                                 return HandlePingPongFrame(sock, false);
 295                         }
 296
 297                         case OP_CLOSE:
 298                         {
 299                                 sock->SetError("Connection closed");
 300                                 return -1;
 301                         }
 302
 303                         default:
 304                         {
 305                                 sock->SetError("WebSocket: Invalid opcode");
 306                                 return -1;
 307                         }
 308                 }
 309         }
 310
 311         void FailHandshake(StreamSocket* sock, const char* httpreply, const char* sockerror)
 312         {
 313                 GetSendQ().push_back(StreamSocket::SendQueue::Element(httpreply));
 314                 sock->DoWrite();
 315                 sock->SetError(sockerror);
 316         }
 317
 318         int HandleHTTPReq(StreamSocket* sock)
 319         {
 320                 std::string& recvq = GetRecvQ();
 321                 const std::string::size_type reqend = recvq.find("\r\n\r\n");
 322                 if (reqend == std::string::npos)
 323                         return 0;
 324
 325                 bool allowedorigin = false;
 326                 HTTPHeaderFinder originheader;
 327                 if (originheader.Find(recvq, "Origin:", 7, reqend))
 328                 {
 329                         const std::string origin = originheader.ExtractValue(recvq);
 330                         for (OriginList::const_iterator iter = config.allowedorigins.begin(); iter != config.allowedorigins.end(); ++iter)
 331                         {
 332                                 if (InspIRCd::Match(origin, *iter, ascii_case_insensitive_map))
 333                                 {
 334                                         allowedorigin = true;
 335                                         break;
 336                                 }
 337                         }
 338                 }
 339
 340                 if (!allowedorigin)
 341                 {
 342                         FailHandshake(sock, "HTTP/1.1 403 Forbidden\r\nConnection: close\r\n\r\n", "WebSocket: Received HTTP request from a non-whitelisted origin");
 343                         return -1;
 344                 }
 345
 346                 if (config.behindproxy && sock->type == StreamSocket::SS_USER)
 347                 {
 348                         LocalUser* luser = static_cast<UserIOHandler*>(sock)->user;
 349                         irc::sockets::sockaddrs realsa(luser->client_sa);
 350
 351                         HTTPHeaderFinder proxyheader;
 352                         if (proxyheader.Find(recvq, "X-Real-IP:", 10, reqend)
 353                                 && irc::sockets::aptosa(proxyheader.ExtractValue(recvq), realsa.port(), realsa))
 354                         {
 355                                 // Nothing to do here.
 356                         }
 357                         else if (proxyheader.Find(recvq, "X-Forwarded-For:", 16, reqend)
 358                                 && irc::sockets::aptosa(proxyheader.ExtractValue(recvq), realsa.port(), realsa))
 359                         {
 360                                 // Nothing to do here.
 361                         }
 362
 363                         // Give the user their real IP address.
 364                         if (realsa != luser->client_sa)
 365                                 luser->SetClientIP(realsa);
 366                 }
 367
 368
 369                 HTTPHeaderFinder keyheader;
 370                 if (!keyheader.Find(recvq, "Sec-WebSocket-Key:", 18, reqend))
 371                 {
 372                         FailHandshake(sock, "HTTP/1.1 501 Not Implemented\r\nConnection: close\r\n\r\n", "WebSocket: Received HTTP request which is not a websocket upgrade");
 373                         return -1;
 374                 }
 375
 376                 if (!*sha1)
 377                 {
 378                         FailHandshake(sock, "HTTP/1.1 503 Service Unavailable\r\nConnection: close\r\n\r\n", "WebSocket: SHA-1 provider missing");
 379                         return -1;
 380                 }
 381
 382                 state = STATE_ESTABLISHED;
 383
 384                 std::string key = keyheader.ExtractValue(recvq);
 385                 key.append(MagicGUID);
 386
 387                 std::string reply = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: ";
 388                 reply.append(BinToBase64((*sha1)->GenerateRaw(key), NULL, '=')).append("\r\n\r\n");
 389                 GetSendQ().push_back(StreamSocket::SendQueue::Element(reply));
 390
 391                 SocketEngine::ChangeEventMask(sock, FD_ADD_TRIAL_WRITE);
 392
 393                 recvq.erase(0, reqend + 4);
 394
 395                 return 1;
 396         }
 397
 398  public:
 399         WebSocketHook(IOHookProvider* Prov, StreamSocket* sock, WebSocketConfig& cfg)
 400                 : IOHookMiddle(Prov)
 401                 , state(STATE_HTTPREQ)
 402                 , lastpingpong(0)
 403                 , config(cfg)
 404         {
 405                 sock->AddIOHook(this);
 406         }
 407
 408         int OnStreamSocketWrite(StreamSocket* sock, StreamSocket::SendQueue& uppersendq) CXX11_OVERRIDE
 409         {
 410                 StreamSocket::SendQueue& mysendq = GetSendQ();
 411
 412                 // Return 1 to allow sending back an error HTTP response
 413                 if (state != STATE_ESTABLISHED)
 414                         return (mysendq.empty() ? 0 : 1);
 415
 416                 std::string message;
 417                 for (StreamSocket::SendQueue::const_iterator elem = uppersendq.begin(); elem != uppersendq.end(); ++elem)
 418                 {
 419                         for (StreamSocket::SendQueue::Element::const_iterator chr = elem->begin(); chr != elem->end(); ++chr)
 420                         {
 421                                 if (*chr == '\n')
 422                                 {
 423                                         // We have found an entire message. Send it in its own frame.
 424                                         if (config.sendastext)
 425                                         {
 426                                                 // If we send messages as text then we need to ensure they are valid UTF-8.
 427                                                 std::string encoded;
 428                                                 utf8::replace_invalid(message.begin(), message.end(), std::back_inserter(encoded));
 429
 430                                                 mysendq.push_back(PrepareSendQElem(encoded.length(), OP_TEXT));
 431                                                 mysendq.push_back(encoded);
 432                                         }
 433                                         else
 434                                         {
 435                                                 // Otherwise, send the raw message as a binary frame.
 436                                                 mysendq.push_back(PrepareSendQElem(message.length(), OP_BINARY));
 437                                                 mysendq.push_back(message);
 438                                         }
 439                                         message.clear();
 440                                 }
 441                                 else if (*chr != '\r')
 442                                 {
 443                                         message.push_back(*chr);
 444                                 }
 445                         }
 446                 }
 447
 448                 // Empty the upper send queue and push whatever is left back onto it.
 449                 uppersendq.clear();
 450                 if (!message.empty())
 451                 {
 452                         uppersendq.push_back(message);
 453                         return 0;
 454                 }
 455
 456                 return 1;
 457         }
 458
 459         int OnStreamSocketRead(StreamSocket* sock, std::string& destrecvq) CXX11_OVERRIDE
 460         {
 461                 if (state == STATE_HTTPREQ)
 462                 {
 463                         int httpret = HandleHTTPReq(sock);
 464                         if (httpret <= 0)
 465                                 return httpret;
 466                 }
 467
 468                 int wsret;
 469                 do
 470                 {
 471                         wsret = HandleWS(sock, destrecvq);
 472                 }
 473                 while ((!GetRecvQ().empty()) && (wsret > 0));
 474
 475                 return wsret;
 476         }
 477
 478         void OnStreamSocketClose(StreamSocket* sock) CXX11_OVERRIDE
 479         {
 480         }
 481 };
 482
 483 void WebSocketHookProvider::OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server)
 484 {
 485         new WebSocketHook(this, sock, config);
 486 }
 487
 488 class ModuleWebSocket : public Module
 489 {
 490         dynamic_reference_nocheck<HashProvider> hash;
 491         reference<WebSocketHookProvider> hookprov;
 492
 493  public:
 494         ModuleWebSocket()
 495                 : hash(this, "hash/sha1")
 496                 , hookprov(new WebSocketHookProvider(this))
 497         {
 498                 sha1 = &hash;
 499         }
 500
 501         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 502         {
 503                 ConfigTagList tags = ServerInstance->Config->ConfTags("wsorigin");
 504                 if (tags.first == tags.second)
 505                         throw ModuleException("You have loaded the websocket module but not configured any allowed origins!");
 506
 507                 WebSocketConfig config;
 508                 for (ConfigIter i = tags.first; i != tags.second; ++i)
 509                 {
 510                         ConfigTag* tag = i->second;
 511
 512                         // Ensure that we have the <wsorigin:allow> parameter.
 513                         const std::string allow = tag->getString("allow");
 514                         if (allow.empty())
 515                                 throw ModuleException("<wsorigin:allow> is a mandatory field, at " + tag->getTagLocation());
 516
 517                         config.allowedorigins.push_back(allow);
 518                 }
 519
 520                 ConfigTag* tag = ServerInstance->Config->ConfValue("websocket");
 521                 config.behindproxy = tag->getBool("behindproxy");
 522                 config.sendastext = tag->getBool("sendastext", true);
 523
 524                 // Everything is okay; apply the new config.
 525                 hookprov->config = config;
 526         }
 527
 528         void OnCleanup(ExtensionItem::ExtensibleType type, Extensible* item) CXX11_OVERRIDE
 529         {
 530                 if (type != ExtensionItem::EXT_USER)
 531                         return;
 532
 533                 LocalUser* user = IS_LOCAL(static_cast<User*>(item));
 534                 if ((user) && (user->eh.GetModHook(this)))
 535                         ServerInstance->Users.QuitUser(user, "WebSocket module unloading");
 536         }
 537
 538         Version GetVersion() CXX11_OVERRIDE
 539         {
 540                 return Version("Provides RFC 6455 WebSocket support", VF_VENDOR);
 541         }
 542 };
 543
 544 MODULE_INIT(ModuleWebSocket)