src/modules/extra/m_ssl_gnutls.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
   5  *   Copyright (C) 2008 John Brooks <john.brooks@dereferenced.net>
   6  *   Copyright (C) 2006-2008 Craig Edwards <craigedwards@brainbox.cc>
   7  *   Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
   8  *   Copyright (C) 2006 Oliver Lupton <oliverlupton@gmail.com>
   9  *
  10  * This file is part of InspIRCd.  InspIRCd is free software: you can
  11  * redistribute it and/or modify it under the terms of the GNU General Public
  12  * License as published by the Free Software Foundation, version 2.
  13  *
  14  * This program is distributed in the hope that it will be useful, but WITHOUT
  15  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  16  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  17  * details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23
  24 #include "inspircd.h"
  25 #include <gnutls/gnutls.h>
  26 #include <gnutls/x509.h>
  27 #include <gcrypt.h>
  28 #include "ssl.h"
  29 #include "m_cap.h"
  30
  31 #ifdef _WIN32
  32 # pragma comment(lib, "libgnutls.lib")
  33 # pragma comment(lib, "libgcrypt.lib")
  34 # pragma comment(lib, "libgpg-error.lib")
  35 # pragma comment(lib, "user32.lib")
  36 # pragma comment(lib, "advapi32.lib")
  37 # pragma comment(lib, "libgcc.lib")
  38 # pragma comment(lib, "libmingwex.lib")
  39 # pragma comment(lib, "gdi32.lib")
  40 #endif
  41
  42 /* $ModDesc: Provides SSL support for clients */
  43 /* $CompileFlags: pkgconfincludes("gnutls","/gnutls/gnutls.h","") */
  44 /* $LinkerFlags: rpath("pkg-config --libs gnutls") pkgconflibs("gnutls","/libgnutls.so","-lgnutls") -lgcrypt */
  45
  46 // These don't exist in older GnuTLS versions
  47 #if(GNUTLS_VERSION_MAJOR < 2)
  48 typedef gnutls_certificate_credentials_t gnutls_certificate_credentials;
  49 typedef gnutls_dh_params_t gnutls_dh_params;
  50 #endif
  51
  52 enum issl_status { ISSL_NONE, ISSL_HANDSHAKING_READ, ISSL_HANDSHAKING_WRITE, ISSL_HANDSHAKEN, ISSL_CLOSING, ISSL_CLOSED };
  53
  54 static std::vector<gnutls_x509_crt_t> x509_certs;
  55 static gnutls_x509_privkey_t x509_key;
  56 #if(GNUTLS_VERSION_MAJOR < 2 || ( GNUTLS_VERSION_MAJOR == 2 && GNUTLS_VERSION_MINOR < 12 ) )
  57 static int cert_callback (gnutls_session_t session, const gnutls_datum_t * req_ca_rdn, int nreqs,
  58         const gnutls_pk_algorithm_t * sign_algos, int sign_algos_length, gnutls_retr_st * st) {
  59
  60         st->type = GNUTLS_CRT_X509;
  61 #else
  62 static int cert_callback (gnutls_session_t session, const gnutls_datum_t * req_ca_rdn, int nreqs,
  63         const gnutls_pk_algorithm_t * sign_algos, int sign_algos_length, gnutls_retr2_st * st) {
  64         st->cert_type = GNUTLS_CRT_X509;
  65         st->key_type = GNUTLS_PRIVKEY_X509;
  66 #endif
  67         st->ncerts = x509_certs.size();
  68         st->cert.x509 = &x509_certs[0];
  69         st->key.x509 = x509_key;
  70         st->deinit_all = 0;
  71
  72         return 0;
  73 }
  74
  75 static ssize_t gnutls_pull_wrapper(gnutls_transport_ptr_t user_wrap, void* buffer, size_t size)
  76 {
  77         StreamSocket* user = reinterpret_cast<StreamSocket*>(user_wrap);
  78         if (user->GetEventMask() & FD_READ_WILL_BLOCK)
  79         {
  80                 errno = EAGAIN;
  81                 return -1;
  82         }
  83         int rv = ServerInstance->SE->Recv(user, reinterpret_cast<char *>(buffer), size, 0);
  84         if (rv < (int)size)
  85                 ServerInstance->SE->ChangeEventMask(user, FD_READ_WILL_BLOCK);
  86         return rv;
  87 }
  88
  89 static ssize_t gnutls_push_wrapper(gnutls_transport_ptr_t user_wrap, const void* buffer, size_t size)
  90 {
  91         StreamSocket* user = reinterpret_cast<StreamSocket*>(user_wrap);
  92         if (user->GetEventMask() & FD_WRITE_WILL_BLOCK)
  93         {
  94                 errno = EAGAIN;
  95                 return -1;
  96         }
  97         int rv = ServerInstance->SE->Send(user, reinterpret_cast<const char *>(buffer), size, 0);
  98         if (rv < (int)size)
  99                 ServerInstance->SE->ChangeEventMask(user, FD_WRITE_WILL_BLOCK);
 100         return rv;
 101 }
 102
 103 class RandGen : public HandlerBase2<void, char*, size_t>
 104 {
 105  public:
 106         RandGen() {}
 107         void Call(char* buffer, size_t len)
 108         {
 109                 gcry_randomize(buffer, len, GCRY_STRONG_RANDOM);
 110         }
 111 };
 112
 113 /** Represents an SSL user's extra data
 114  */
 115 class issl_session
 116 {
 117 public:
 118         gnutls_session_t sess;
 119         issl_status status;
 120         reference<ssl_cert> cert;
 121         issl_session() : sess(NULL) {}
 122 };
 123
 124 class CommandStartTLS : public SplitCommand
 125 {
 126  public:
 127         bool enabled;
 128         CommandStartTLS (Module* mod) : SplitCommand(mod, "STARTTLS")
 129         {
 130                 enabled = true;
 131                 works_before_reg = true;
 132         }
 133
 134         CmdResult HandleLocal(const std::vector<std::string> &parameters, LocalUser *user)
 135         {
 136                 if (!enabled)
 137                 {
 138                         user->WriteNumeric(691, "%s :STARTTLS is not enabled", user->nick.c_str());
 139                         return CMD_FAILURE;
 140                 }
 141
 142                 if (user->registered == REG_ALL)
 143                 {
 144                         user->WriteNumeric(691, "%s :STARTTLS is not permitted after client registration is complete", user->nick.c_str());
 145                 }
 146                 else
 147                 {
 148                         if (!user->eh.GetIOHook())
 149                         {
 150                                 user->WriteNumeric(670, "%s :STARTTLS successful, go ahead with TLS handshake", user->nick.c_str());
 151                                 /* We need to flush the write buffer prior to adding the IOHook,
 152                                  * otherwise we'll be sending this line inside the SSL session - which
 153                                  * won't start its handshake until the client gets this line. Currently,
 154                                  * we assume the write will not block here; this is usually safe, as
 155                                  * STARTTLS is sent very early on in the registration phase, where the
 156                                  * user hasn't built up much sendq. Handling a blocked write here would
 157                                  * be very annoying.
 158                                  */
 159                                 user->eh.DoWrite();
 160                                 user->eh.AddIOHook(creator);
 161                                 creator->OnStreamSocketAccept(&user->eh, NULL, NULL);
 162                         }
 163                         else
 164                                 user->WriteNumeric(691, "%s :STARTTLS failure", user->nick.c_str());
 165                 }
 166
 167                 return CMD_FAILURE;
 168         }
 169 };
 170
 171 class ModuleSSLGnuTLS : public Module
 172 {
 173         issl_session* sessions;
 174
 175         gnutls_certificate_credentials_t x509_cred;
 176         gnutls_dh_params_t dh_params;
 177         gnutls_digest_algorithm_t hash;
 178         gnutls_priority_t priority;
 179
 180         std::string sslports;
 181         int dh_bits;
 182
 183         bool cred_alloc;
 184         bool dh_alloc;
 185
 186         RandGen randhandler;
 187         CommandStartTLS starttls;
 188
 189         GenericCap capHandler;
 190         ServiceProvider iohook;
 191  public:
 192
 193         ModuleSSLGnuTLS()
 194                 : starttls(this), capHandler(this, "tls"), iohook(this, "ssl/gnutls", SERVICE_IOHOOK)
 195         {
 196                 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
 197
 198                 sessions = new issl_session[ServerInstance->SE->GetMaxFds()];
 199
 200                 gnutls_global_init(); // This must be called once in the program
 201                 gnutls_x509_privkey_init(&x509_key);
 202                 // Init this here so it's always initialized, avoids an extra boolean
 203                 gnutls_priority_init(&priority, "NORMAL", NULL);
 204
 205                 cred_alloc = false;
 206                 dh_alloc = false;
 207         }
 208
 209         void init()
 210         {
 211                 // Needs the flag as it ignores a plain /rehash
 212                 OnModuleRehash(NULL,"ssl");
 213
 214                 ServerInstance->GenRandom = &randhandler;
 215
 216                 // Void return, guess we assume success
 217                 gnutls_certificate_set_dh_params(x509_cred, dh_params);
 218                 Implementation eventlist[] = { I_On005Numeric, I_OnRehash, I_OnModuleRehash, I_OnUserConnect,
 219                         I_OnEvent, I_OnHookIO };
 220                 ServerInstance->Modules->Attach(eventlist, this, sizeof(eventlist)/sizeof(Implementation));
 221
 222                 ServerInstance->Modules->AddService(iohook);
 223                 ServerInstance->AddCommand(&starttls);
 224         }
 225
 226         void OnRehash(User* user)
 227         {
 228                 sslports.clear();
 229
 230                 ConfigTag* Conf = ServerInstance->Config->ConfValue("gnutls");
 231                 starttls.enabled = Conf->getBool("starttls", true);
 232
 233                 if (Conf->getBool("showports", true))
 234                 {
 235                         sslports = Conf->getString("advertisedports");
 236                         if (!sslports.empty())
 237                                 return;
 238
 239                         for (size_t i = 0; i < ServerInstance->ports.size(); i++)
 240                         {
 241                                 ListenSocket* port = ServerInstance->ports[i];
 242                                 if (port->bind_tag->getString("ssl") != "gnutls")
 243                                         continue;
 244
 245                                 const std::string& portid = port->bind_desc;
 246                                 ServerInstance->Logs->Log("m_ssl_gnutls", DEFAULT, "m_ssl_gnutls.so: Enabling SSL for port %s", portid.c_str());
 247
 248                                 if (port->bind_tag->getString("type", "clients") == "clients" && port->bind_addr != "127.0.0.1")
 249                                 {
 250                                         /*
 251                                          * Found an SSL port for clients that is not bound to 127.0.0.1 and handled by us, display
 252                                          * the IP:port in ISUPPORT.
 253                                          *
 254                                          * We used to advertise all ports seperated by a ';' char that matched the above criteria,
 255                                          * but this resulted in too long ISUPPORT lines if there were lots of ports to be displayed.
 256                                          * To solve this by default we now only display the first IP:port found and let the user
 257                                          * configure the exact value for the 005 token, if necessary.
 258                                          */
 259                                         sslports = portid;
 260                                         break;
 261                                 }
 262                         }
 263                 }
 264         }
 265
 266         void OnModuleRehash(User* user, const std::string &param)
 267         {
 268                 if(param != "ssl")
 269                         return;
 270
 271                 std::string keyfile;
 272                 std::string certfile;
 273                 std::string cafile;
 274                 std::string crlfile;
 275                 OnRehash(user);
 276
 277                 ConfigTag* Conf = ServerInstance->Config->ConfValue("gnutls");
 278
 279                 cafile = Conf->getString("cafile", CONFIG_PATH "/ca.pem");
 280                 crlfile = Conf->getString("crlfile", CONFIG_PATH "/crl.pem");
 281                 certfile = Conf->getString("certfile", CONFIG_PATH "/cert.pem");
 282                 keyfile = Conf->getString("keyfile", CONFIG_PATH "/key.pem");
 283                 dh_bits = Conf->getInt("dhbits");
 284                 std::string hashname = Conf->getString("hash", "md5");
 285
 286                 // The GnuTLS manual states that the gnutls_set_default_priority()
 287                 // call we used previously when initializing the session is the same
 288                 // as setting the "NORMAL" priority string.
 289                 // Thus if the setting below is not in the config we will behave exactly
 290                 // the same as before, when the priority setting wasn't available.
 291                 std::string priorities = Conf->getString("priority", "NORMAL");
 292
 293                 if((dh_bits != 768) && (dh_bits != 1024) && (dh_bits != 2048) && (dh_bits != 3072) && (dh_bits != 4096))
 294                         dh_bits = 1024;
 295
 296                 if (hashname == "md5")
 297                         hash = GNUTLS_DIG_MD5;
 298                 else if (hashname == "sha1")
 299                         hash = GNUTLS_DIG_SHA1;
 300                 else
 301                         throw ModuleException("Unknown hash type " + hashname);
 302
 303
 304                 int ret;
 305
 306                 if (dh_alloc)
 307                 {
 308                         gnutls_dh_params_deinit(dh_params);
 309                         dh_alloc = false;
 310                 }
 311
 312                 if (cred_alloc)
 313                 {
 314                         // Deallocate the old credentials
 315                         gnutls_certificate_free_credentials(x509_cred);
 316
 317                         for(unsigned int i=0; i < x509_certs.size(); i++)
 318                                 gnutls_x509_crt_deinit(x509_certs[i]);
 319                         x509_certs.clear();
 320                 }
 321
 322                 ret = gnutls_certificate_allocate_credentials(&x509_cred);
 323                 cred_alloc = (ret >= 0);
 324                 if (!cred_alloc)
 325                         ServerInstance->Logs->Log("m_ssl_gnutls",DEBUG, "m_ssl_gnutls.so: Failed to allocate certificate credentials: %s", gnutls_strerror(ret));
 326
 327                 if((ret =gnutls_certificate_set_x509_trust_file(x509_cred, cafile.c_str(), GNUTLS_X509_FMT_PEM)) < 0)
 328                         ServerInstance->Logs->Log("m_ssl_gnutls",DEBUG, "m_ssl_gnutls.so: Failed to set X.509 trust file '%s': %s", cafile.c_str(), gnutls_strerror(ret));
 329
 330                 if((ret = gnutls_certificate_set_x509_crl_file (x509_cred, crlfile.c_str(), GNUTLS_X509_FMT_PEM)) < 0)
 331                         ServerInstance->Logs->Log("m_ssl_gnutls",DEBUG, "m_ssl_gnutls.so: Failed to set X.509 CRL file '%s': %s", crlfile.c_str(), gnutls_strerror(ret));
 332
 333                 FileReader reader;
 334
 335                 reader.LoadFile(certfile);
 336                 std::string cert_string = reader.Contents();
 337                 gnutls_datum_t cert_datum = { (unsigned char*)cert_string.data(), static_cast<unsigned int>(cert_string.length()) };
 338
 339                 reader.LoadFile(keyfile);
 340                 std::string key_string = reader.Contents();
 341                 gnutls_datum_t key_datum = { (unsigned char*)key_string.data(), static_cast<unsigned int>(key_string.length()) };
 342
 343                 // If this fails, no SSL port will work. At all. So, do the smart thing - throw a ModuleException
 344                 unsigned int certcount = Conf->getInt("certcount", 3);
 345                 x509_certs.resize(certcount);
 346                 ret = gnutls_x509_crt_list_import(&x509_certs[0], &certcount, &cert_datum, GNUTLS_X509_FMT_PEM, GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED);
 347                 if (ret < 0)
 348                         throw ModuleException("Unable to load GnuTLS server certificate (" + certfile + "): " + std::string(gnutls_strerror(ret)));
 349                 x509_certs.resize(certcount);
 350
 351                 if((ret = gnutls_x509_privkey_import(x509_key, &key_datum, GNUTLS_X509_FMT_PEM)) < 0)
 352                         throw ModuleException("Unable to load GnuTLS server private key (" + keyfile + "): " + std::string(gnutls_strerror(ret)));
 353
 354                 if((ret = gnutls_certificate_set_x509_key(x509_cred, &x509_certs[0], certcount, x509_key)) < 0)
 355                         throw ModuleException("Unable to set GnuTLS cert/key pair: " + std::string(gnutls_strerror(ret)));
 356
 357                 // It's safe to call this every time as we cannot have this uninitialized, see constructor and below.
 358                 gnutls_priority_deinit(priority);
 359
 360                 // Try to set the priorities for ciphers, kex methods etc. to the user supplied string
 361                 // If the user did not supply anything then the string is already set to "NORMAL"
 362                 const char* priocstr = priorities.c_str();
 363                 const char* prioerror;
 364
 365                 if ((ret = gnutls_priority_init(&priority, priocstr, &prioerror)) < 0)
 366                 {
 367                         // gnutls did not understand the user supplied string, log and fall back to the default priorities
 368                         ServerInstance->Logs->Log("m_ssl_gnutls",DEFAULT, "m_ssl_gnutls.so: Failed to set priorities to \"%s\": %s Syntax error at position %u, falling back to default (NORMAL)", priorities.c_str(), gnutls_strerror(ret), (unsigned int) (prioerror - priocstr));
 369                         gnutls_priority_init(&priority, "NORMAL", NULL);
 370                 }
 371
 372                 #if(GNUTLS_VERSION_MAJOR < 2 || ( GNUTLS_VERSION_MAJOR == 2 && GNUTLS_VERSION_MINOR < 12 ) )
 373                 gnutls_certificate_client_set_retrieve_function (x509_cred, cert_callback);
 374                 #else
 375                 gnutls_certificate_set_retrieve_function (x509_cred, cert_callback);
 376                 #endif
 377                 ret = gnutls_dh_params_init(&dh_params);
 378                 dh_alloc = (ret >= 0);
 379                 if (!dh_alloc)
 380                         ServerInstance->Logs->Log("m_ssl_gnutls",DEFAULT, "m_ssl_gnutls.so: Failed to initialise DH parameters: %s", gnutls_strerror(ret));
 381
 382                 // This may be on a large (once a day or week) timer eventually.
 383                 GenerateDHParams();
 384         }
 385
 386         void GenerateDHParams()
 387         {
 388                 // Generate Diffie Hellman parameters - for use with DHE
 389                 // kx algorithms. These should be discarded and regenerated
 390                 // once a day, once a week or once a month. Depending on the
 391                 // security requirements.
 392
 393                 if (!dh_alloc)
 394                         return;
 395
 396                 int ret;
 397
 398                 if((ret = gnutls_dh_params_generate2(dh_params, dh_bits)) < 0)
 399                         ServerInstance->Logs->Log("m_ssl_gnutls",DEFAULT, "m_ssl_gnutls.so: Failed to generate DH parameters (%d bits): %s", dh_bits, gnutls_strerror(ret));
 400         }
 401
 402         ~ModuleSSLGnuTLS()
 403         {
 404                 for(unsigned int i=0; i < x509_certs.size(); i++)
 405                         gnutls_x509_crt_deinit(x509_certs[i]);
 406
 407                 gnutls_x509_privkey_deinit(x509_key);
 408                 gnutls_priority_deinit(priority);
 409
 410                 if (dh_alloc)
 411                         gnutls_dh_params_deinit(dh_params);
 412                 if (cred_alloc)
 413                         gnutls_certificate_free_credentials(x509_cred);
 414
 415                 gnutls_global_deinit();
 416                 delete[] sessions;
 417                 ServerInstance->GenRandom = &ServerInstance->HandleGenRandom;
 418         }
 419
 420         void OnCleanup(int target_type, void* item)
 421         {
 422                 if(target_type == TYPE_USER)
 423                 {
 424                         LocalUser* user = IS_LOCAL(static_cast<User*>(item));
 425
 426                         if (user && user->eh.GetIOHook() == this)
 427                         {
 428                                 // User is using SSL, they're a local user, and they're using one of *our* SSL ports.
 429                                 // Potentially there could be multiple SSL modules loaded at once on different ports.
 430                                 ServerInstance->Users->QuitUser(user, "SSL module unloading");
 431                         }
 432                 }
 433         }
 434
 435         Version GetVersion()
 436         {
 437                 return Version("Provides SSL support for clients", VF_VENDOR);
 438         }
 439
 440
 441         void On005Numeric(std::string &output)
 442         {
 443                 if (!sslports.empty())
 444                         output.append(" SSL=" + sslports);
 445                 if (starttls.enabled)
 446                         output.append(" STARTTLS");
 447         }
 448
 449         void OnHookIO(StreamSocket* user, ListenSocket* lsb)
 450         {
 451                 if (!user->GetIOHook() && lsb->bind_tag->getString("ssl") == "gnutls")
 452                 {
 453                         /* Hook the user with our module */
 454                         user->AddIOHook(this);
 455                 }
 456         }
 457
 458         void OnRequest(Request& request)
 459         {
 460                 if (strcmp("GET_SSL_CERT", request.id) == 0)
 461                 {
 462                         SocketCertificateRequest& req = static_cast<SocketCertificateRequest&>(request);
 463                         int fd = req.sock->GetFd();
 464                         issl_session* session = &sessions[fd];
 465
 466                         req.cert = session->cert;
 467                 }
 468         }
 469
 470         void InitSession(StreamSocket* user, bool me_server)
 471         {
 472                 issl_session* session = &sessions[user->GetFd()];
 473
 474                 gnutls_init(&session->sess, me_server ? GNUTLS_SERVER : GNUTLS_CLIENT);
 475
 476                 gnutls_priority_set(session->sess, priority);
 477                 gnutls_credentials_set(session->sess, GNUTLS_CRD_CERTIFICATE, x509_cred);
 478                 gnutls_dh_set_prime_bits(session->sess, dh_bits);
 479                 gnutls_transport_set_ptr(session->sess, reinterpret_cast<gnutls_transport_ptr_t>(user));
 480                 gnutls_transport_set_push_function(session->sess, gnutls_push_wrapper);
 481                 gnutls_transport_set_pull_function(session->sess, gnutls_pull_wrapper);
 482
 483                 if (me_server)
 484                         gnutls_certificate_server_set_request(session->sess, GNUTLS_CERT_REQUEST); // Request client certificate if any.
 485
 486                 Handshake(session, user);
 487         }
 488
 489         void OnStreamSocketAccept(StreamSocket* user, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server)
 490         {
 491                 issl_session* session = &sessions[user->GetFd()];
 492
 493                 /* For STARTTLS: Don't try and init a session on a socket that already has a session */
 494                 if (session->sess)
 495                         return;
 496
 497                 InitSession(user, true);
 498         }
 499
 500         void OnStreamSocketConnect(StreamSocket* user)
 501         {
 502                 InitSession(user, false);
 503         }
 504
 505         void OnStreamSocketClose(StreamSocket* user)
 506         {
 507                 CloseSession(&sessions[user->GetFd()]);
 508         }
 509
 510         int OnStreamSocketRead(StreamSocket* user, std::string& recvq)
 511         {
 512                 issl_session* session = &sessions[user->GetFd()];
 513
 514                 if (!session->sess)
 515                 {
 516                         CloseSession(session);
 517                         user->SetError("No SSL session");
 518                         return -1;
 519                 }
 520
 521                 if (session->status == ISSL_HANDSHAKING_READ || session->status == ISSL_HANDSHAKING_WRITE)
 522                 {
 523                         // The handshake isn't finished, try to finish it.
 524
 525                         if(!Handshake(session, user))
 526                         {
 527                                 if (session->status != ISSL_CLOSING)
 528                                         return 0;
 529                                 return -1;
 530                         }
 531                 }
 532
 533                 // If we resumed the handshake then session->status will be ISSL_HANDSHAKEN.
 534
 535                 if (session->status == ISSL_HANDSHAKEN)
 536                 {
 537                         char* buffer = ServerInstance->GetReadBuffer();
 538                         size_t bufsiz = ServerInstance->Config->NetBufferSize;
 539                         int ret = gnutls_record_recv(session->sess, buffer, bufsiz);
 540                         if (ret > 0)
 541                         {
 542                                 recvq.append(buffer, ret);
 543                                 return 1;
 544                         }
 545                         else if (ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED)
 546                         {
 547                                 return 0;
 548                         }
 549                         else if (ret == 0)
 550                         {
 551                                 user->SetError("SSL Connection closed");
 552                                 CloseSession(session);
 553                                 return -1;
 554                         }
 555                         else
 556                         {
 557                                 user->SetError(gnutls_strerror(ret));
 558                                 CloseSession(session);
 559                                 return -1;
 560                         }
 561                 }
 562                 else if (session->status == ISSL_CLOSING)
 563                         return -1;
 564
 565                 return 0;
 566         }
 567
 568         int OnStreamSocketWrite(StreamSocket* user, std::string& sendq)
 569         {
 570                 issl_session* session = &sessions[user->GetFd()];
 571
 572                 if (!session->sess)
 573                 {
 574                         CloseSession(session);
 575                         user->SetError("No SSL session");
 576                         return -1;
 577                 }
 578
 579                 if (session->status == ISSL_HANDSHAKING_WRITE || session->status == ISSL_HANDSHAKING_READ)
 580                 {
 581                         // The handshake isn't finished, try to finish it.
 582                         Handshake(session, user);
 583                         if (session->status != ISSL_CLOSING)
 584                                 return 0;
 585                         return -1;
 586                 }
 587
 588                 int ret = 0;
 589
 590                 if (session->status == ISSL_HANDSHAKEN)
 591                 {
 592                         ret = gnutls_record_send(session->sess, sendq.data(), sendq.length());
 593
 594                         if (ret == (int)sendq.length())
 595                         {
 596                                 ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_WRITE);
 597                                 return 1;
 598                         }
 599                         else if (ret > 0)
 600                         {
 601                                 sendq = sendq.substr(ret);
 602                                 ServerInstance->SE->ChangeEventMask(user, FD_WANT_SINGLE_WRITE);
 603                                 return 0;
 604                         }
 605                         else if (ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED || ret == 0)
 606                         {
 607                                 ServerInstance->SE->ChangeEventMask(user, FD_WANT_SINGLE_WRITE);
 608                                 return 0;
 609                         }
 610                         else // (ret < 0)
 611                         {
 612                                 user->SetError(gnutls_strerror(ret));
 613                                 CloseSession(session);
 614                                 return -1;
 615                         }
 616                 }
 617
 618                 return 0;
 619         }
 620
 621         bool Handshake(issl_session* session, StreamSocket* user)
 622         {
 623                 int ret = gnutls_handshake(session->sess);
 624
 625                 if (ret < 0)
 626                 {
 627                         if(ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED)
 628                         {
 629                                 // Handshake needs resuming later, read() or write() would have blocked.
 630
 631                                 if(gnutls_record_get_direction(session->sess) == 0)
 632                                 {
 633                                         // gnutls_handshake() wants to read() again.
 634                                         session->status = ISSL_HANDSHAKING_READ;
 635                                         ServerInstance->SE->ChangeEventMask(user, FD_WANT_POLL_READ | FD_WANT_NO_WRITE);
 636                                 }
 637                                 else
 638                                 {
 639                                         // gnutls_handshake() wants to write() again.
 640                                         session->status = ISSL_HANDSHAKING_WRITE;
 641                                         ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE);
 642                                 }
 643                         }
 644                         else
 645                         {
 646                                 user->SetError("Handshake Failed - " + std::string(gnutls_strerror(ret)));
 647                                 CloseSession(session);
 648                                 session->status = ISSL_CLOSING;
 649                         }
 650
 651                         return false;
 652                 }
 653                 else
 654                 {
 655                         // Change the seesion state
 656                         session->status = ISSL_HANDSHAKEN;
 657
 658                         VerifyCertificate(session,user);
 659
 660                         // Finish writing, if any left
 661                         ServerInstance->SE->ChangeEventMask(user, FD_WANT_POLL_READ | FD_WANT_NO_WRITE | FD_ADD_TRIAL_WRITE);
 662
 663                         return true;
 664                 }
 665         }
 666
 667         void OnUserConnect(LocalUser* user)
 668         {
 669                 if (user->eh.GetIOHook() == this)
 670                 {
 671                         if (sessions[user->eh.GetFd()].sess)
 672                         {
 673                                 ssl_cert* cert = sessions[user->eh.GetFd()].cert;
 674                                 std::string cipher = gnutls_kx_get_name(gnutls_kx_get(sessions[user->eh.GetFd()].sess));
 675                                 cipher.append("-").append(gnutls_cipher_get_name(gnutls_cipher_get(sessions[user->eh.GetFd()].sess))).append("-");
 676                                 cipher.append(gnutls_mac_get_name(gnutls_mac_get(sessions[user->eh.GetFd()].sess)));
 677                                 if (cert->fingerprint.empty())
 678                                         user->WriteServ("NOTICE %s :*** You are connected using SSL cipher \"%s\"", user->nick.c_str(), cipher.c_str());
 679                                 else
 680                                         user->WriteServ("NOTICE %s :*** You are connected using SSL cipher \"%s\""
 681                                                 " and your SSL fingerprint is %s", user->nick.c_str(), cipher.c_str(), cert->fingerprint.c_str());
 682                         }
 683                 }
 684         }
 685
 686         void CloseSession(issl_session* session)
 687         {
 688                 if (session->sess)
 689                 {
 690                         gnutls_bye(session->sess, GNUTLS_SHUT_WR);
 691                         gnutls_deinit(session->sess);
 692                 }
 693                 session->sess = NULL;
 694                 session->cert = NULL;
 695                 session->status = ISSL_NONE;
 696         }
 697
 698         void VerifyCertificate(issl_session* session, StreamSocket* user)
 699         {
 700                 if (!session->sess || !user)
 701                         return;
 702
 703                 unsigned int status;
 704                 const gnutls_datum_t* cert_list;
 705                 int ret;
 706                 unsigned int cert_list_size;
 707                 gnutls_x509_crt_t cert;
 708                 char name[MAXBUF];
 709                 unsigned char digest[MAXBUF];
 710                 size_t digest_size = sizeof(digest);
 711                 size_t name_size = sizeof(name);
 712                 ssl_cert* certinfo = new ssl_cert;
 713                 session->cert = certinfo;
 714
 715                 /* This verification function uses the trusted CAs in the credentials
 716                  * structure. So you must have installed one or more CA certificates.
 717                  */
 718                 ret = gnutls_certificate_verify_peers2(session->sess, &status);
 719
 720                 if (ret < 0)
 721                 {
 722                         certinfo->error = std::string(gnutls_strerror(ret));
 723                         return;
 724                 }
 725
 726                 certinfo->invalid = (status & GNUTLS_CERT_INVALID);
 727                 certinfo->unknownsigner = (status & GNUTLS_CERT_SIGNER_NOT_FOUND);
 728                 certinfo->revoked = (status & GNUTLS_CERT_REVOKED);
 729                 certinfo->trusted = !(status & GNUTLS_CERT_SIGNER_NOT_CA);
 730
 731                 /* Up to here the process is the same for X.509 certificates and
 732                  * OpenPGP keys. From now on X.509 certificates are assumed. This can
 733                  * be easily extended to work with openpgp keys as well.
 734                  */
 735                 if (gnutls_certificate_type_get(session->sess) != GNUTLS_CRT_X509)
 736                 {
 737                         certinfo->error = "No X509 keys sent";
 738                         return;
 739                 }
 740
 741                 ret = gnutls_x509_crt_init(&cert);
 742                 if (ret < 0)
 743                 {
 744                         certinfo->error = gnutls_strerror(ret);
 745                         return;
 746                 }
 747
 748                 cert_list_size = 0;
 749                 cert_list = gnutls_certificate_get_peers(session->sess, &cert_list_size);
 750                 if (cert_list == NULL)
 751                 {
 752                         certinfo->error = "No certificate was found";
 753                         goto info_done_dealloc;
 754                 }
 755
 756                 /* This is not a real world example, since we only check the first
 757                  * certificate in the given chain.
 758                  */
 759
 760                 ret = gnutls_x509_crt_import(cert, &cert_list[0], GNUTLS_X509_FMT_DER);
 761                 if (ret < 0)
 762                 {
 763                         certinfo->error = gnutls_strerror(ret);
 764                         goto info_done_dealloc;
 765                 }
 766
 767                 gnutls_x509_crt_get_dn(cert, name, &name_size);
 768                 certinfo->dn = name;
 769
 770                 gnutls_x509_crt_get_issuer_dn(cert, name, &name_size);
 771                 certinfo->issuer = name;
 772
 773                 if ((ret = gnutls_x509_crt_get_fingerprint(cert, hash, digest, &digest_size)) < 0)
 774                 {
 775                         certinfo->error = gnutls_strerror(ret);
 776                 }
 777                 else
 778                 {
 779                         certinfo->fingerprint = irc::hex(digest, digest_size);
 780                 }
 781
 782                 /* Beware here we do not check for errors.
 783                  */
 784                 if ((gnutls_x509_crt_get_expiration_time(cert) < ServerInstance->Time()) || (gnutls_x509_crt_get_activation_time(cert) > ServerInstance->Time()))
 785                 {
 786                         certinfo->error = "Not activated, or expired certificate";
 787                 }
 788
 789 info_done_dealloc:
 790                 gnutls_x509_crt_deinit(cert);
 791         }
 792
 793         void OnEvent(Event& ev)
 794         {
 795                 if (starttls.enabled)
 796                         capHandler.HandleEvent(ev);
 797         }
 798 };
 799
 800 MODULE_INIT(ModuleSSLGnuTLS)