src/modules/m_websocket.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2019 iwalkalone <iwalkalone69@gmail.com>
   5  *   Copyright (C) 2017-2020 Sadie Powell <sadie@witchery.services>
   6  *   Copyright (C) 2016-2017 Attila Molnar <attilamolnar@hush.com>
   7  *
   8  * This file is part of InspIRCd.  InspIRCd is free software: you can
   9  * redistribute it and/or modify it under the terms of the GNU General Public
  10  * License as published by the Free Software Foundation, version 2.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  14  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  15  * details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 /// $CompilerFlags: -Ivendor_directory("utfcpp")
  22
  23
  24 #include "inspircd.h"
  25 #include "iohook.h"
  26 #include "modules/hash.h"
  27
  28 #include <utf8.h>
  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         typedef std::vector<std::string> OriginList;
  37         typedef std::vector<std::string> ProxyRanges;
  38
  39         // The HTTP origins that can connect to the server.
  40         OriginList allowedorigins;
  41
  42         // The IP ranges which send trustworthy X-Real-IP or X-Forwarded-For headers.
  43         ProxyRanges proxyranges;
  44
  45         // Whether to send as UTF-8 text instead of binary data.
  46         bool sendastext;
  47 };
  48
  49 class WebSocketHookProvider : public IOHookProvider
  50 {
  51  public:
  52         WebSocketConfig config;
  53         WebSocketHookProvider(Module* mod)
  54                 : IOHookProvider(mod, "websocket", IOHookProvider::IOH_UNKNOWN, true)
  55         {
  56         }
  57
  58         void OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server) CXX11_OVERRIDE;
  59
  60         void OnConnect(StreamSocket* sock) CXX11_OVERRIDE
  61         {
  62         }
  63 };
  64
  65 class WebSocketHook : public IOHookMiddle
  66 {
  67         class HTTPHeaderFinder
  68         {
  69                 std::string::size_type bpos;
  70                 std::string::size_type len;
  71
  72          public:
  73                 bool Find(const std::string& req, const char* header, std::string::size_type headerlen, std::string::size_type maxpos)
  74                 {
  75                         std::string::size_type keybegin = req.find(header);
  76                         if ((keybegin == std::string::npos) || (keybegin > maxpos) || (keybegin == 0) || (req[keybegin-1] != '\n'))
  77                                 return false;
  78
  79                         keybegin += headerlen;
  80
  81                         bpos = req.find_first_not_of(whitespace, keybegin, sizeof(whitespace)-1);
  82                         if ((bpos == std::string::npos) || (bpos > maxpos))
  83                                 return false;
  84
  85                         const std::string::size_type epos = req.find_first_of(whitespace, bpos, sizeof(whitespace)-1);
  86                         len = epos - bpos;
  87
  88                         return true;
  89                 }
  90
  91                 std::string ExtractValue(const std::string& req) const
  92                 {
  93                         return std::string(req, bpos, len);
  94                 }
  95         };
  96
  97         enum OpCode
  98         {
  99                 OP_CONTINUATION = 0x00,
 100                 OP_TEXT = 0x01,
 101                 OP_BINARY = 0x02,
 102                 OP_CLOSE = 0x08,
 103                 OP_PING = 0x09,
 104                 OP_PONG = 0x0a
 105         };
 106
 107         enum State
 108         {
 109                 STATE_HTTPREQ,
 110                 STATE_ESTABLISHED
 111         };
 112
 113         static const unsigned char WS_MASKBIT = (1 << 7);
 114         static const unsigned char WS_FINBIT = (1 << 7);
 115         static const unsigned char WS_PAYLOAD_LENGTH_MAGIC_LARGE = 126;
 116         static const unsigned char WS_PAYLOAD_LENGTH_MAGIC_HUGE = 127;
 117         static const size_t WS_MAX_PAYLOAD_LENGTH_SMALL = 125;
 118         static const size_t WS_MAX_PAYLOAD_LENGTH_LARGE = 65535;
 119         static const size_t MAXHEADERSIZE = sizeof(uint64_t) + 2;
 120
 121         // Clients sending ping or pong frames faster than this are killed
 122         static const time_t MINPINGPONGDELAY = 10;
 123
 124         State state;
 125         time_t lastpingpong;
 126         WebSocketConfig& config;
 127
 128         static size_t FillHeader(unsigned char* outbuf, size_t sendlength, OpCode opcode)
 129         {
 130                 size_t pos = 0;
 131                 outbuf[pos++] = WS_FINBIT | opcode;
 132
 133                 if (sendlength <= WS_MAX_PAYLOAD_LENGTH_SMALL)
 134                 {
 135                         outbuf[pos++] = sendlength;
 136                 }
 137                 else if (sendlength <= WS_MAX_PAYLOAD_LENGTH_LARGE)
 138                 {
 139                         outbuf[pos++] = WS_PAYLOAD_LENGTH_MAGIC_LARGE;
 140                         outbuf[pos++] = (sendlength >> 8) & 0xff;
 141                         outbuf[pos++] = sendlength & 0xff;
 142                 }
 143                 else
 144                 {
 145                         outbuf[pos++] = WS_PAYLOAD_LENGTH_MAGIC_HUGE;
 146                         const uint64_t len = sendlength;
 147                         for (int i = sizeof(uint64_t)-1; i >= 0; i--)
 148                                 outbuf[pos++] = ((len >> i*8) & 0xff);
 149                 }
 150
 151                 return pos;
 152         }
 153
 154         static StreamSocket::SendQueue::Element PrepareSendQElem(size_t size, OpCode opcode)
 155         {
 156                 unsigned char header[MAXHEADERSIZE];
 157                 const size_t n = FillHeader(header, size, opcode);
 158
 159                 return StreamSocket::SendQueue::Element(reinterpret_cast<const char*>(header), n);
 160         }
 161
 162         int HandleAppData(StreamSocket* sock, std::string& appdataout, bool allowlarge)
 163         {
 164                 std::string& myrecvq = GetRecvQ();
 165                 // Need 1 byte opcode, minimum 1 byte len, 4 bytes masking key
 166                 if (myrecvq.length() < 6)
 167                         return 0;
 168
 169                 const std::string& cmyrecvq = myrecvq;
 170                 unsigned char len1 = (unsigned char)cmyrecvq[1];
 171                 if (!(len1 & WS_MASKBIT))
 172                 {
 173                         sock->SetError("WebSocket protocol violation: unmasked client frame");
 174                         return -1;
 175                 }
 176
 177                 len1 &= ~WS_MASKBIT;
 178
 179                 // Assume the length is a single byte, if not, update values later
 180                 unsigned int len = len1;
 181                 unsigned int payloadstartoffset = 6;
 182                 const unsigned char* maskkey = reinterpret_cast<const unsigned char*>(&cmyrecvq[2]);
 183
 184                 if (len1 == WS_PAYLOAD_LENGTH_MAGIC_LARGE)
 185                 {
 186                         // allowlarge is false for control frames according to the RFC meaning large pings, etc. are not allowed
 187                         if (!allowlarge)
 188                         {
 189                                 sock->SetError("WebSocket protocol violation: large control frame");
 190                                 return -1;
 191                         }
 192
 193                         // Large frame, has 2 bytes len after the magic byte indicating the length
 194                         // Need 1 byte opcode, 3 bytes len, 4 bytes masking key
 195                         if (myrecvq.length() < 8)
 196                                 return 0;
 197
 198                         unsigned char len2 = (unsigned char)cmyrecvq[2];
 199                         unsigned char len3 = (unsigned char)cmyrecvq[3];
 200                         len = (len2 << 8) | len3;
 201
 202                         if (len <= WS_MAX_PAYLOAD_LENGTH_SMALL)
 203                         {
 204                                 sock->SetError("WebSocket protocol violation: non-minimal length encoding used");
 205                                 return -1;
 206                         }
 207
 208                         maskkey += 2;
 209                         payloadstartoffset += 2;
 210                 }
 211                 else if (len1 == WS_PAYLOAD_LENGTH_MAGIC_HUGE)
 212                 {
 213                         sock->SetError("WebSocket: Huge frames are not supported");
 214                         return -1;
 215                 }
 216
 217                 if (myrecvq.length() < payloadstartoffset + len)
 218                         return 0;
 219
 220                 unsigned int maskkeypos = 0;
 221                 const std::string::iterator endit = myrecvq.begin() + payloadstartoffset + len;
 222                 for (std::string::const_iterator i = myrecvq.begin() + payloadstartoffset; i != endit; ++i)
 223                 {
 224                         const unsigned char c = (unsigned char)*i;
 225                         appdataout.push_back(c ^ maskkey[maskkeypos++]);
 226                         maskkeypos %= 4;
 227                 }
 228
 229                 myrecvq.erase(myrecvq.begin(), endit);
 230                 return 1;
 231         }
 232
 233         int HandlePingPongFrame(StreamSocket* sock, bool isping)
 234         {
 235                 if (lastpingpong + MINPINGPONGDELAY >= ServerInstance->Time())
 236                 {
 237                         sock->SetError("WebSocket: Ping/pong flood");
 238                         return -1;
 239                 }
 240
 241                 lastpingpong = ServerInstance->Time();
 242
 243                 std::string appdata;
 244                 const int result = HandleAppData(sock, appdata, false);
 245                 // If it's a pong stop here regardless of the result so we won't generate a reply
 246                 if ((result <= 0) || (!isping))
 247                         return result;
 248
 249                 StreamSocket::SendQueue::Element elem = PrepareSendQElem(appdata.length(), OP_PONG);
 250                 elem.append(appdata);
 251                 GetSendQ().push_back(elem);
 252
 253                 SocketEngine::ChangeEventMask(sock, FD_ADD_TRIAL_WRITE);
 254                 return 1;
 255         }
 256
 257         int HandleWS(StreamSocket* sock, std::string& destrecvq)
 258         {
 259                 if (GetRecvQ().empty())
 260                         return 0;
 261
 262                 unsigned char opcode = (unsigned char)GetRecvQ().c_str()[0];
 263                 switch (opcode & ~WS_FINBIT)
 264                 {
 265                         case OP_CONTINUATION:
 266                         case OP_TEXT:
 267                         case OP_BINARY:
 268                         {
 269                                 std::string appdata;
 270                                 const int result = HandleAppData(sock, appdata, true);
 271                                 if (result != 1)
 272                                         return result;
 273
 274                                 // Strip out any CR+LF which may have been erroneously sent.
 275                                 for (std::string::const_iterator iter = appdata.begin(); iter != appdata.end(); ++iter)
 276                                 {
 277                                         if (*iter != '\r' && *iter != '\n')
 278                                                 destrecvq.push_back(*iter);
 279                                 }
 280
 281                                 // If we are on the final message of this block append a line terminator.
 282                                 if (opcode & WS_FINBIT)
 283                                         destrecvq.append("\r\n");
 284
 285                                 return 1;
 286                         }
 287
 288                         case OP_PING:
 289                         {
 290                                 return HandlePingPongFrame(sock, true);
 291                         }
 292
 293                         case OP_PONG:
 294                         {
 295                                 // A pong frame may be sent unsolicited, so we have to handle it.
 296                                 // It may carry application data which we need to remove from the recvq as well.
 297                                 return HandlePingPongFrame(sock, false);
 298                         }
 299
 300                         case OP_CLOSE:
 301                         {
 302                                 sock->SetError("Connection closed");
 303                                 return -1;
 304                         }
 305
 306                         default:
 307                         {
 308                                 sock->SetError("WebSocket: Invalid opcode");
 309                                 return -1;
 310                         }
 311                 }
 312         }
 313
 314         void FailHandshake(StreamSocket* sock, const char* httpreply, const char* sockerror)
 315         {
 316                 GetSendQ().push_back(StreamSocket::SendQueue::Element(httpreply));
 317                 sock->DoWrite();
 318                 sock->SetError(sockerror);
 319         }
 320
 321         int HandleHTTPReq(StreamSocket* sock)
 322         {
 323                 std::string& recvq = GetRecvQ();
 324                 const std::string::size_type reqend = recvq.find("\r\n\r\n");
 325                 if (reqend == std::string::npos)
 326                         return 0;
 327
 328                 bool allowedorigin = false;
 329                 HTTPHeaderFinder originheader;
 330                 if (originheader.Find(recvq, "Origin:", 7, reqend))
 331                 {
 332                         const std::string origin = originheader.ExtractValue(recvq);
 333                         for (WebSocketConfig::OriginList::const_iterator iter = config.allowedorigins.begin(); iter != config.allowedorigins.end(); ++iter)
 334                         {
 335                                 if (InspIRCd::Match(origin, *iter, ascii_case_insensitive_map))
 336                                 {
 337                                         allowedorigin = true;
 338                                         break;
 339                                 }
 340                         }
 341                 }
 342
 343                 if (!allowedorigin)
 344                 {
 345                         FailHandshake(sock, "HTTP/1.1 403 Forbidden\r\nConnection: close\r\n\r\n", "WebSocket: Received HTTP request from a non-whitelisted origin");
 346                         return -1;
 347                 }
 348
 349                 if (!config.proxyranges.empty() && sock->type == StreamSocket::SS_USER)
 350                 {
 351                         LocalUser* luser = static_cast<UserIOHandler*>(sock)->user;
 352                         irc::sockets::sockaddrs realsa(luser->client_sa);
 353
 354                         HTTPHeaderFinder proxyheader;
 355                         if (proxyheader.Find(recvq, "X-Real-IP:", 10, reqend)
 356                                 && irc::sockets::aptosa(proxyheader.ExtractValue(recvq), realsa.port(), realsa))
 357                         {
 358                                 // Nothing to do here.
 359                         }
 360                         else if (proxyheader.Find(recvq, "X-Forwarded-For:", 16, reqend)
 361                                 && irc::sockets::aptosa(proxyheader.ExtractValue(recvq), realsa.port(), realsa))
 362                         {
 363                                 // Nothing to do here.
 364                         }
 365
 366                         for (WebSocketConfig::ProxyRanges::const_iterator iter = config.proxyranges.begin(); iter != config.proxyranges.end(); ++iter)
 367                         {
 368                                 if (InspIRCd::MatchCIDR(luser->GetIPString(), *iter, ascii_case_insensitive_map))
 369                                 {
 370                                         // Give the user their real IP address.
 371                                         if (realsa != luser->client_sa)
 372                                                 luser->SetClientIP(realsa);
 373
 374                                         // Error if changing their IP gets them banned.
 375                                         if (luser->quitting)
 376                                                 return -1;
 377                                         break;
 378                                 }
 379                         }
 380                 }
 381
 382
 383                 HTTPHeaderFinder keyheader;
 384                 if (!keyheader.Find(recvq, "Sec-WebSocket-Key:", 18, reqend))
 385                 {
 386                         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");
 387                         return -1;
 388                 }
 389
 390                 if (!*sha1)
 391                 {
 392                         FailHandshake(sock, "HTTP/1.1 503 Service Unavailable\r\nConnection: close\r\n\r\n", "WebSocket: SHA-1 provider missing");
 393                         return -1;
 394                 }
 395
 396                 state = STATE_ESTABLISHED;
 397
 398                 std::string key = keyheader.ExtractValue(recvq);
 399                 key.append(MagicGUID);
 400
 401                 std::string reply = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: ";
 402                 reply.append(BinToBase64((*sha1)->GenerateRaw(key), NULL, '=')).append("\r\n\r\n");
 403                 GetSendQ().push_back(StreamSocket::SendQueue::Element(reply));
 404
 405                 SocketEngine::ChangeEventMask(sock, FD_ADD_TRIAL_WRITE);
 406
 407                 recvq.erase(0, reqend + 4);
 408
 409                 return 1;
 410         }
 411
 412  public:
 413         WebSocketHook(IOHookProvider* Prov, StreamSocket* sock, WebSocketConfig& cfg)
 414                 : IOHookMiddle(Prov)
 415                 , state(STATE_HTTPREQ)
 416                 , lastpingpong(0)
 417                 , config(cfg)
 418         {
 419                 sock->AddIOHook(this);
 420         }
 421
 422         int OnStreamSocketWrite(StreamSocket* sock, StreamSocket::SendQueue& uppersendq) CXX11_OVERRIDE
 423         {
 424                 StreamSocket::SendQueue& mysendq = GetSendQ();
 425
 426                 // Return 1 to allow sending back an error HTTP response
 427                 if (state != STATE_ESTABLISHED)
 428                         return (mysendq.empty() ? 0 : 1);
 429
 430                 std::string message;
 431                 for (StreamSocket::SendQueue::const_iterator elem = uppersendq.begin(); elem != uppersendq.end(); ++elem)
 432                 {
 433                         for (StreamSocket::SendQueue::Element::const_iterator chr = elem->begin(); chr != elem->end(); ++chr)
 434                         {
 435                                 if (*chr == '\n')
 436                                 {
 437                                         // We have found an entire message. Send it in its own frame.
 438                                         if (config.sendastext)
 439                                         {
 440                                                 // If we send messages as text then we need to ensure they are valid UTF-8.
 441                                                 std::string encoded;
 442                                                 utf8::replace_invalid(message.begin(), message.end(), std::back_inserter(encoded));
 443
 444                                                 mysendq.push_back(PrepareSendQElem(encoded.length(), OP_TEXT));
 445                                                 mysendq.push_back(encoded);
 446                                         }
 447                                         else
 448                                         {
 449                                                 // Otherwise, send the raw message as a binary frame.
 450                                                 mysendq.push_back(PrepareSendQElem(message.length(), OP_BINARY));
 451                                                 mysendq.push_back(message);
 452                                         }
 453                                         message.clear();
 454                                 }
 455                                 else if (*chr != '\r')
 456                                 {
 457                                         message.push_back(*chr);
 458                                 }
 459                         }
 460                 }
 461
 462                 // Empty the upper send queue and push whatever is left back onto it.
 463                 uppersendq.clear();
 464                 if (!message.empty())
 465                 {
 466                         uppersendq.push_back(message);
 467                         return 0;
 468                 }
 469
 470                 return 1;
 471         }
 472
 473         int OnStreamSocketRead(StreamSocket* sock, std::string& destrecvq) CXX11_OVERRIDE
 474         {
 475                 if (state == STATE_HTTPREQ)
 476                 {
 477                         int httpret = HandleHTTPReq(sock);
 478                         if (httpret <= 0)
 479                                 return httpret;
 480                 }
 481
 482                 int wsret;
 483                 do
 484                 {
 485                         wsret = HandleWS(sock, destrecvq);
 486                 }
 487                 while ((!GetRecvQ().empty()) && (wsret > 0));
 488
 489                 return wsret;
 490         }
 491
 492         void OnStreamSocketClose(StreamSocket* sock) CXX11_OVERRIDE
 493         {
 494         }
 495 };
 496
 497 void WebSocketHookProvider::OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server)
 498 {
 499         new WebSocketHook(this, sock, config);
 500 }
 501
 502 class ModuleWebSocket : public Module
 503 {
 504         dynamic_reference_nocheck<HashProvider> hash;
 505         reference<WebSocketHookProvider> hookprov;
 506
 507  public:
 508         ModuleWebSocket()
 509                 : hash(this, "hash/sha1")
 510                 , hookprov(new WebSocketHookProvider(this))
 511         {
 512                 sha1 = &hash;
 513         }
 514
 515         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 516         {
 517                 ConfigTagList tags = ServerInstance->Config->ConfTags("wsorigin");
 518                 if (tags.first == tags.second)
 519                         throw ModuleException("You have loaded the websocket module but not configured any allowed origins!");
 520
 521                 WebSocketConfig config;
 522                 for (ConfigIter i = tags.first; i != tags.second; ++i)
 523                 {
 524                         ConfigTag* tag = i->second;
 525
 526                         // Ensure that we have the <wsorigin:allow> parameter.
 527                         const std::string allow = tag->getString("allow");
 528                         if (allow.empty())
 529                                 throw ModuleException("<wsorigin:allow> is a mandatory field, at " + tag->getTagLocation());
 530
 531                         config.allowedorigins.push_back(allow);
 532                 }
 533
 534                 ConfigTag* tag = ServerInstance->Config->ConfValue("websocket");
 535                 config.sendastext = tag->getBool("sendastext", true);
 536
 537                 irc::spacesepstream proxyranges(tag->getString("proxyranges"));
 538                 for (std::string proxyrange; proxyranges.GetToken(proxyrange); )
 539                         config.proxyranges.push_back(proxyrange);
 540
 541                 // Everything is okay; apply the new config.
 542                 hookprov->config = config;
 543         }
 544
 545         void OnCleanup(ExtensionItem::ExtensibleType type, Extensible* item) CXX11_OVERRIDE
 546         {
 547                 if (type != ExtensionItem::EXT_USER)
 548                         return;
 549
 550                 LocalUser* user = IS_LOCAL(static_cast<User*>(item));
 551                 if ((user) && (user->eh.GetModHook(this)))
 552                         ServerInstance->Users.QuitUser(user, "WebSocket module unloading");
 553         }
 554
 555         Version GetVersion() CXX11_OVERRIDE
 556         {
 557                 return Version("Allows WebSocket clients to connect to the IRC server.", VF_VENDOR);
 558         }
 559 };
 560
 561 MODULE_INIT(ModuleWebSocket)