tcp_socket_handler.cpp 17.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111
#include <network/tcp_socket_handler.hpp>
#include <network/dns_handler.hpp>

#include <utils/timed_events.hpp>
#include <utils/scopeguard.hpp>
#include <network/poller.hpp>

#include <logger/logger.hpp>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdexcept>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include <cstring>
#include <fcntl.h>

#include <iostream>

#ifdef BOTAN_FOUND
# include <botan/hex.h>

Botan::AutoSeeded_RNG TCPSocketHandler::rng;
Permissive_Credentials_Manager TCPSocketHandler::credential_manager;
Botan::TLS::Policy TCPSocketHandler::policy;
Botan::TLS::Session_Manager_In_Memory TCPSocketHandler::session_manager(TCPSocketHandler::rng);

#endif

#ifndef UIO_FASTIOV
# define UIO_FASTIOV 8
#endif

using namespace std::string_literals;
using namespace std::chrono_literals;

namespace ph = std::placeholders;

TCPSocketHandler::TCPSocketHandler(std::shared_ptr<Poller> poller):
  SocketHandler(poller, -1),
  use_tls(false),
  connected(false),
  connecting(false)
#ifdef CARES_FOUND
  ,resolving(false),
  resolved(false),
  resolved4(false),
  resolved6(false),
  cares_addrinfo(nullptr),
  cares_error()
#endif
{}

TCPSocketHandler::~TCPSocketHandler()
{
#ifdef CARES_FOUND
  this->free_cares_addrinfo();
#endif
}

void TCPSocketHandler::init_socket(const struct addrinfo* rp)
{
  if ((this->socket = ::socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol)) == -1)
    throw std::runtime_error("Could not create socket: "s + strerror(errno));
  int optval = 1;
  if (::setsockopt(this->socket, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval)) == -1)
    log_warning("Failed to enable TCP keepalive on socket: " << strerror(errno));
  // Set the socket on non-blocking mode.  This is useful to receive a EAGAIN
  // error when connect() would block, to not block the whole process if a
  // remote is not responsive.
  const int existing_flags = ::fcntl(this->socket, F_GETFL, 0);
  if ((existing_flags == -1) ||
      (::fcntl(this->socket, F_SETFL, existing_flags | O_NONBLOCK) == -1))
    throw std::runtime_error("Could not initialize socket: "s + strerror(errno));
}

void TCPSocketHandler::connect(const std::string& address, const std::string& port, const bool tls)
{
  this->address = address;
  this->port = port;
  this->use_tls = tls;

  utils::ScopeGuard sg;

  struct addrinfo* addr_res;

  if (!this->connecting)
    {
      // Get the addrinfo from getaddrinfo (or ares_gethostbyname), only if
      // this is the first call of this function.
#ifdef CARES_FOUND
      if (!this->resolved)
        {
          log_info("Trying to connect to " << address << ":" << port);
          // Start the asynchronous process of resolving the hostname. Once
          // the addresses have been found and `resolved` has been set to true
          // (but connecting will still be false), TCPSocketHandler::connect()
          // needs to be called, again.
          this->resolving = true;
          DNSHandler::instance.gethostbyname(address, this, AF_INET6);
          DNSHandler::instance.gethostbyname(address, this, AF_INET);
          return;
        }
      else
        {
          // The c-ares resolved the hostname and the available addresses
          // where saved in the cares_addrinfo linked list. Now, just use
          // this list to try to connect.
          addr_res = this->cares_addrinfo;
          if (!addr_res)
            {
112
              const auto msg = this->cares_error;
113
              this->close();
114
              this->on_connection_failed(msg);
115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591
              return ;
            }
        }
#else
      log_info("Trying to connect to " << address << ":" << port);
      struct addrinfo hints;
      memset(&hints, 0, sizeof(struct addrinfo));
      hints.ai_flags = 0;
      hints.ai_family = AF_UNSPEC;
      hints.ai_socktype = SOCK_STREAM;
      hints.ai_protocol = 0;

      const int res = ::getaddrinfo(address.c_str(), port.c_str(), &hints, &addr_res);

      if (res != 0)
        {
          log_warning("getaddrinfo failed: "s + gai_strerror(res));
          this->close();
          this->on_connection_failed(gai_strerror(res));
          return ;
        }
      // Make sure the alloced structure is always freed at the end of the
      // function
      sg.add_callback([&addr_res](){ freeaddrinfo(addr_res); });
#endif
    }
  else
    { // This function is called again, use the saved addrinfo structure,
      // instead of re-doing the whole getaddrinfo process.
      addr_res = &this->addrinfo;
    }

  for (struct addrinfo* rp = addr_res; rp; rp = rp->ai_next)
    {
      if (!this->connecting)
        {
          try {
            this->init_socket(rp);
          }
          catch (const std::runtime_error& error) {
            log_error("Failed to init socket: " << error.what());
            break;
          }
        }
      if (::connect(this->socket, rp->ai_addr, rp->ai_addrlen) == 0
          || errno == EISCONN)
        {
          log_info("Connection success.");
          TimedEventsManager::instance().cancel("connection_timeout"s +
                                                std::to_string(this->socket));
          this->poller->add_socket_handler(this);
          this->connected = true;
          this->connecting = false;
#ifdef BOTAN_FOUND
          if (this->use_tls)
            this->start_tls();
#endif
          this->on_connected();
          return ;
        }
      else if (errno == EINPROGRESS || errno == EALREADY)
        {   // retry this process later, when the socket
            // is ready to be written on.
          this->connecting = true;
          this->poller->add_socket_handler(this);
          this->poller->watch_send_events(this);
          // Save the addrinfo structure, to use it on the next call
          this->ai_addrlen = rp->ai_addrlen;
          memcpy(&this->ai_addr, rp->ai_addr, this->ai_addrlen);
          memcpy(&this->addrinfo, rp, sizeof(struct addrinfo));
          this->addrinfo.ai_addr = reinterpret_cast<struct sockaddr*>(&this->ai_addr);
          this->addrinfo.ai_next = nullptr;
          // If the connection has not succeeded or failed in 5s, we consider
          // it to have failed
          TimedEventsManager::instance().add_event(
                                                   TimedEvent(std::chrono::steady_clock::now() + 5s,
                                                              std::bind(&TCPSocketHandler::on_connection_timeout, this),
                                                              "connection_timeout"s + std::to_string(this->socket)));
          return ;
        }
      log_info("Connection failed:" << strerror(errno));
    }
  log_error("All connection attempts failed.");
  this->close();
  this->on_connection_failed(strerror(errno));
  return ;
}

void TCPSocketHandler::on_connection_timeout()
{
  this->close();
  this->on_connection_failed("connection timed out");
}

void TCPSocketHandler::connect()
{
  this->connect(this->address, this->port, this->use_tls);
}

void TCPSocketHandler::on_recv()
{
#ifdef BOTAN_FOUND
  if (this->use_tls)
    this->tls_recv();
  else
#endif
    this->plain_recv();
}

void TCPSocketHandler::plain_recv()
{
  static constexpr size_t buf_size = 4096;
  char buf[buf_size];
  void* recv_buf = this->get_receive_buffer(buf_size);

  if (recv_buf == nullptr)
    recv_buf = buf;

  const ssize_t size = this->do_recv(recv_buf, buf_size);

  if (size > 0)
    {
      if (buf == recv_buf)
        {
          // data needs to be placed in the in_buf string, because no buffer
          // was provided to receive that data directly. The in_buf buffer
          // will be handled in parse_in_buffer()
          this->in_buf += std::string(buf, size);
        }
      this->parse_in_buffer(size);
    }
}

ssize_t TCPSocketHandler::do_recv(void* recv_buf, const size_t buf_size)
{
  ssize_t size = ::recv(this->socket, recv_buf, buf_size, 0);
  if (0 == size)
    {
      this->on_connection_close("");
      this->close();
    }
  else if (-1 == size)
    {
      log_warning("Error while reading from socket: " << strerror(errno));
      // Remember if we were connecting, or already connected when this
      // happened, because close() sets this->connecting to false
      const auto were_connecting = this->connecting;
      this->close();
      if (were_connecting)
        this->on_connection_failed(strerror(errno));
      else
        this->on_connection_close(strerror(errno));
    }
  return size;
}

void TCPSocketHandler::on_send()
{
  struct iovec msg_iov[UIO_FASTIOV] = {};
  struct msghdr msg{nullptr, 0,
      msg_iov,
      0, nullptr, 0, 0};
  for (std::string& s: this->out_buf)
    {
      // unconsting the content of s is ok, sendmsg will never modify it
      msg_iov[msg.msg_iovlen].iov_base = const_cast<char*>(s.data());
      msg_iov[msg.msg_iovlen].iov_len = s.size();
      if (++msg.msg_iovlen == UIO_FASTIOV)
        break;
    }
  ssize_t res = ::sendmsg(this->socket, &msg, MSG_NOSIGNAL);
  if (res < 0)
    {
      log_error("sendmsg failed: " << strerror(errno));
      this->on_connection_close(strerror(errno));
      this->close();
    }
  else
    {
      // remove all the strings that were successfully sent.
      for (auto it = this->out_buf.begin();
           it != this->out_buf.end();)
        {
          if (static_cast<size_t>(res) >= (*it).size())
            {
              res -= (*it).size();
              it = this->out_buf.erase(it);
            }
          else
            {
              // If one string has partially been sent, we use substr to
              // crop it
              if (res > 0)
                (*it) = (*it).substr(res, std::string::npos);
              break;
            }
        }
      if (this->out_buf.empty())
        this->poller->stop_watching_send_events(this);
    }
}

void TCPSocketHandler::close()
{
  TimedEventsManager::instance().cancel("connection_timeout"s +
                                        std::to_string(this->socket));
  if (this->connected || this->connecting)
    this->poller->remove_socket_handler(this->get_socket());
  if (this->socket != -1)
    {
      ::close(this->socket);
      this->socket = -1;
    }
  this->connected = false;
  this->connecting = false;
#ifdef CARES_FOUND
  this->resolving = false;
  this->resolved = false;
  this->resolved4 = false;
  this->resolved6 = false;
  this->free_cares_addrinfo();
  this->cares_error.clear();
#endif
  this->in_buf.clear();
  this->out_buf.clear();
  this->port.clear();
}

void TCPSocketHandler::send_data(std::string&& data)
{
#ifdef BOTAN_FOUND
  if (this->use_tls)
    this->tls_send(std::move(data));
  else
#endif
    this->raw_send(std::move(data));
}

void TCPSocketHandler::raw_send(std::string&& data)
{
  if (data.empty())
    return ;
  this->out_buf.emplace_back(std::move(data));
  if (this->connected)
    this->poller->watch_send_events(this);
}

void TCPSocketHandler::send_pending_data()
{
  if (this->connected && !this->out_buf.empty())
    this->poller->watch_send_events(this);
}

bool TCPSocketHandler::is_connected() const
{
  return this->connected;
}

bool TCPSocketHandler::is_connecting() const
{
#ifdef CARES_FOUND
  return this->connecting || this->resolving;
#else
  return this->connecting;
#endif
}

void* TCPSocketHandler::get_receive_buffer(const size_t) const
{
  return nullptr;
}

#ifdef BOTAN_FOUND
void TCPSocketHandler::start_tls()
{
  Botan::TLS::Server_Information server_info(this->address, "irc", std::stoul(this->port));
  this->tls = std::make_unique<Botan::TLS::Client>(
      std::bind(&TCPSocketHandler::tls_output_fn, this, ph::_1, ph::_2),
      std::bind(&TCPSocketHandler::tls_data_cb, this, ph::_1, ph::_2),
      std::bind(&TCPSocketHandler::tls_alert_cb, this, ph::_1, ph::_2, ph::_3),
      std::bind(&TCPSocketHandler::tls_handshake_cb, this, ph::_1),
      session_manager, credential_manager, policy,
      rng, server_info, Botan::TLS::Protocol_Version::latest_tls_version());
}

void TCPSocketHandler::tls_recv()
{
  static constexpr size_t buf_size = 4096;
  char recv_buf[buf_size];

  const ssize_t size = this->do_recv(recv_buf, buf_size);
  if (size > 0)
    {
      const bool was_active = this->tls->is_active();
      this->tls->received_data(reinterpret_cast<const Botan::byte*>(recv_buf),
                              static_cast<size_t>(size));
      if (!was_active && this->tls->is_active())
        this->on_tls_activated();
    }
}

void TCPSocketHandler::tls_send(std::string&& data)
{
  if (this->tls->is_active())
    {
      const bool was_active = this->tls->is_active();
      if (!this->pre_buf.empty())
        {
          this->tls->send(reinterpret_cast<const Botan::byte*>(this->pre_buf.data()),
                         this->pre_buf.size());
          this->pre_buf = "";
        }
      if (!data.empty())
        this->tls->send(reinterpret_cast<const Botan::byte*>(data.data()),
                       data.size());
      if (!was_active && this->tls->is_active())
        this->on_tls_activated();
    }
  else
    this->pre_buf += data;
}

void TCPSocketHandler::tls_data_cb(const Botan::byte* data, size_t size)
{
  this->in_buf += std::string(reinterpret_cast<const char*>(data),
                              size);
  if (!this->in_buf.empty())
    this->parse_in_buffer(size);
}

void TCPSocketHandler::tls_output_fn(const Botan::byte* data, size_t size)
{
  this->raw_send(std::string(reinterpret_cast<const char*>(data), size));
}

void TCPSocketHandler::tls_alert_cb(Botan::TLS::Alert alert, const Botan::byte*, size_t)
{
  log_debug("tls_alert: " << alert.type_string());
}

bool TCPSocketHandler::tls_handshake_cb(const Botan::TLS::Session& session)
{
  log_debug("Handshake with " << session.server_info().hostname() << " complete."
            << " Version: " << session.version().to_string()
            << " using " << session.ciphersuite().to_string());
  if (!session.session_id().empty())
    log_debug("Session ID " << Botan::hex_encode(session.session_id()));
  if (!session.session_ticket().empty())
    log_debug("Session ticket " << Botan::hex_encode(session.session_ticket()));
  return true;
}

void TCPSocketHandler::on_tls_activated()
{
  this->send_data("");
}

void Permissive_Credentials_Manager::verify_certificate_chain(const std::string& type,
                                                const std::string& purported_hostname,
                                                const std::vector<Botan::X509_Certificate>&)
{ // TODO: Offer the admin to disallow connection on untrusted
  // certificates
  log_debug("Checking remote certificate (" << type << ") for hostname " << purported_hostname);
}

#endif // BOTAN_FOUND

#ifdef CARES_FOUND

void TCPSocketHandler::on_hostname4_resolved(int status, struct hostent* hostent)
{
  this->resolved4 = true;
  if (status == ARES_SUCCESS)
    this->fill_ares_addrinfo4(hostent);
  else
    this->cares_error = ::ares_strerror(status);

  if (this->resolved4 && this->resolved6)
    {
      this->resolved = true;
      this->resolving = false;
      this->connect();
    }
}

void TCPSocketHandler::on_hostname6_resolved(int status, struct hostent* hostent)
{
  this->resolved6 = true;
  if (status == ARES_SUCCESS)
    this->fill_ares_addrinfo6(hostent);
  else
    this->cares_error = ::ares_strerror(status);

  if (this->resolved4 && this->resolved6)
    {
      this->resolved = true;
      this->resolving = false;
      this->connect();
    }
}

void TCPSocketHandler::fill_ares_addrinfo4(const struct hostent* hostent)
{
  struct addrinfo* prev = this->cares_addrinfo;
  struct in_addr** address = reinterpret_cast<struct in_addr**>(hostent->h_addr_list);

  while (*address)
    {
       // Create a new addrinfo list element, and fill it
      struct addrinfo* current = new struct addrinfo;
      current->ai_flags = 0;
      current->ai_family = hostent->h_addrtype;
      current->ai_socktype = SOCK_STREAM;
      current->ai_protocol = 0;
      current->ai_addrlen = sizeof(struct sockaddr_in);

      struct sockaddr_in* addr = new struct sockaddr_in;
      addr->sin_family = hostent->h_addrtype;
      addr->sin_port = htons(strtoul(this->port.data(), nullptr, 10));
      addr->sin_addr.s_addr = (*address)->s_addr;

      current->ai_addr = reinterpret_cast<struct sockaddr*>(addr);
      current->ai_next = nullptr;
      current->ai_canonname = nullptr;

      current->ai_next = prev;
      this->cares_addrinfo = current;
      prev = current;
      ++address;
    }
}

void TCPSocketHandler::fill_ares_addrinfo6(const struct hostent* hostent)
{
  struct addrinfo* prev = this->cares_addrinfo;
  struct in6_addr** address = reinterpret_cast<struct in6_addr**>(hostent->h_addr_list);

  while (*address)
    {
       // Create a new addrinfo list element, and fill it
      struct addrinfo* current = new struct addrinfo;
      current->ai_flags = 0;
      current->ai_family = hostent->h_addrtype;
      current->ai_socktype = SOCK_STREAM;
      current->ai_protocol = 0;
      current->ai_addrlen = sizeof(struct sockaddr_in6);

      struct sockaddr_in6* addr = new struct sockaddr_in6;
      addr->sin6_family = hostent->h_addrtype;
      addr->sin6_port = htons(strtoul(this->port.data(), nullptr, 10));
      ::memcpy(addr->sin6_addr.s6_addr, (*address)->s6_addr, 16);
      addr->sin6_flowinfo = 0;
      addr->sin6_scope_id = 0;

      current->ai_addr = reinterpret_cast<struct sockaddr*>(addr);
      current->ai_next = nullptr;
      current->ai_canonname = nullptr;

      current->ai_next = prev;
      this->cares_addrinfo = current;
      prev = current;
      ++address;
    }
}

void TCPSocketHandler::free_cares_addrinfo()
{
  while (this->cares_addrinfo)
    {
      delete this->cares_addrinfo->ai_addr;
      auto next = this->cares_addrinfo->ai_next;
      delete this->cares_addrinfo;
      this->cares_addrinfo = next;
    }
}

#endif  // CARES_FOUND