aria2/src/SocketCore.cc

/* <!-- copyright */
/*
 * aria2 - The high speed download utility
 *
 * Copyright (C) 2006 Tatsuhiro Tsujikawa
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 * You must obey the GNU General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
 * version of the file(s), but you are not obligated to do so.  If you
 * do not wish to do so, delete this exception statement from your
 * version.  If you delete this exception statement from all source
 * files in the program, then also delete it here.
 */
/* copyright --> */
#include "SocketCore.h"

#ifdef HAVE_IPHLPAPI_H
# include <iphlpapi.h>
#endif // HAVE_IPHLPAPI_H

#include <unistd.h>
#ifdef HAVE_IFADDRS_H
# include <ifaddrs.h>
#endif // HAVE_IFADDRS_H

#include <cerrno>
#include <cstring>

#include "message.h"
#include "DlRetryEx.h"
#include "DlAbortEx.h"
#include "fmt.h"
#include "util.h"
#include "TimeA2.h"
#include "a2functional.h"
#include "LogFactory.h"
#include "A2STR.h"
#ifdef ENABLE_SSL
# include "TLSContext.h"
# include "TLSSession.h"
#endif // ENABLE_SSL

namespace aria2 {

#ifndef __MINGW32__
# define SOCKET_ERRNO (errno)
#else
# define SOCKET_ERRNO (WSAGetLastError())
#endif // __MINGW32__

#ifdef __MINGW32__
# define A2_EINPROGRESS WSAEWOULDBLOCK
# define A2_EWOULDBLOCK WSAEWOULDBLOCK
# define A2_EINTR WSAEINTR
# define A2_WOULDBLOCK(e) (e == WSAEWOULDBLOCK)
#else // !__MINGW32__
# define A2_EINPROGRESS EINPROGRESS
# ifndef EWOULDBLOCK
#  define EWOULDBLOCK EAGAIN
# endif // EWOULDBLOCK
# define A2_EWOULDBLOCK EWOULDBLOCK
# define A2_EINTR EINTR
# if EWOULDBLOCK == EAGAIN
#  define A2_WOULDBLOCK(e) (e == EWOULDBLOCK)
# else // EWOULDBLOCK != EAGAIN
#  define A2_WOULDBLOCK(e) (e == EWOULDBLOCK || e == EAGAIN)
# endif // EWOULDBLOCK != EAGAIN
#endif // !__MINGW32__

#ifdef __MINGW32__
# define CLOSE(X) ::closesocket(X)
#else
# define CLOSE(X) close(X)
#endif // __MINGW32__

namespace {
std::string errorMsg(int errNum)
{
#ifndef __MINGW32__
  return util::safeStrerror(errNum);
#else
  static char buf[256];
  if (FormatMessage(
                    FORMAT_MESSAGE_FROM_SYSTEM |
                    FORMAT_MESSAGE_IGNORE_INSERTS,
                    NULL,
                    errNum,
                    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
                    (LPTSTR) &buf,
                    sizeof(buf),
                    NULL
                    ) == 0) {
    snprintf(buf, sizeof(buf), EX_SOCKET_UNKNOWN_ERROR, errNum, errNum);
  }
  return buf;
#endif // __MINGW32__
}
} // namespace

namespace {
enum TlsState {
  // TLS object is not initialized.
  A2_TLS_NONE = 0,
  // TLS object is now handshaking.
  A2_TLS_HANDSHAKING = 2,
  // TLS object is now connected.
  A2_TLS_CONNECTED = 3
};
} // namespace

int SocketCore::protocolFamily_ = AF_UNSPEC;

std::vector<std::pair<sockaddr_union, socklen_t> >
SocketCore::bindAddrs_;

#ifdef ENABLE_SSL
SharedHandle<TLSContext> SocketCore::clTlsContext_;
SharedHandle<TLSContext> SocketCore::svTlsContext_;

void SocketCore::setClientTLSContext
(const SharedHandle<TLSContext>& tlsContext)
{
  clTlsContext_ = tlsContext;
}

void SocketCore::setServerTLSContext
(const SharedHandle<TLSContext>& tlsContext)
{
  svTlsContext_ = tlsContext;
}
#endif // ENABLE_SSL

SocketCore::SocketCore(int sockType)
  : sockType_(sockType),
    sockfd_(-1)
{
  init();
}

SocketCore::SocketCore(sock_t sockfd, int sockType)
  : sockType_(sockType),
    sockfd_(sockfd)
{
  init();
}

void SocketCore::init()
{
  blocking_ = true;
  secure_ = A2_TLS_NONE;

  wantRead_ = false;
  wantWrite_ = false;
}

SocketCore::~SocketCore() {
  closeConnection();
}

void SocketCore::create(int family, int protocol)
{
  int errNum;
  closeConnection();
  sock_t fd = socket(family, sockType_, protocol);
  errNum = SOCKET_ERRNO;
  if(fd == (sock_t) -1) {
    throw DL_ABORT_EX
      (fmt("Failed to create socket. Cause:%s", errorMsg(errNum).c_str()));
  }
  int sockopt = 1;
  if(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
                (a2_sockopt_t) &sockopt, sizeof(sockopt)) < 0) {
    errNum = SOCKET_ERRNO;
    CLOSE(fd);
    throw DL_ABORT_EX
      (fmt("Failed to create socket. Cause:%s", errorMsg(errNum).c_str()));
  }
  sockfd_ = fd;
}

static sock_t bindInternal
(int family, int socktype, int protocol,
 const struct sockaddr* addr, socklen_t addrlen,
 std::string& error)
{
  int errNum;
  sock_t fd = socket(family, socktype, protocol);
  errNum = SOCKET_ERRNO;
  if(fd == (sock_t) -1) {
    error = errorMsg(errNum);
    return -1;
  }
  int sockopt = 1;
  if(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (a2_sockopt_t) &sockopt,
                sizeof(sockopt)) < 0) {
    errNum = SOCKET_ERRNO;
    error = errorMsg(errNum);
    CLOSE(fd);
    return -1;
  }
#ifdef IPV6_V6ONLY
  if(family == AF_INET6) {
    int sockopt = 1;
    if(setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, (a2_sockopt_t) &sockopt,
                  sizeof(sockopt)) < 0) {
      errNum = SOCKET_ERRNO;
      error = errorMsg(errNum);
      CLOSE(fd);
      return -1;
    }
  }
#endif // IPV6_V6ONLY
  if(::bind(fd, addr, addrlen) == -1) {
    errNum = SOCKET_ERRNO;
    error = errorMsg(errNum);
    CLOSE(fd);
    return -1;
  }
  return fd;
}

static sock_t bindTo
(const char* host, uint16_t port, int family, int sockType,
 int getaddrinfoFlags, std::string& error)
{
  struct addrinfo* res;
  int s = callGetaddrinfo(&res, host, util::uitos(port).c_str(),
                          family, sockType, getaddrinfoFlags, 0);
  if(s) {
    error = gai_strerror(s);
    return -1;
  }
  WSAAPI_AUTO_DELETE<struct addrinfo*> resDeleter(res, freeaddrinfo);
  struct addrinfo* rp;
  for(rp = res; rp; rp = rp->ai_next) {
    sock_t fd = bindInternal(rp->ai_family, rp->ai_socktype, rp->ai_protocol,
                             rp->ai_addr, rp->ai_addrlen, error);
    if(fd != (sock_t)-1) {
      return fd;
    }
  }
  return -1;
}

void SocketCore::bindWithFamily(uint16_t port, int family, int flags)
{
  closeConnection();
  std::string error;
  sock_t fd = bindTo(0, port, family, sockType_, flags, error);
  if(fd == (sock_t) -1) {
    throw DL_ABORT_EX(fmt(EX_SOCKET_BIND, error.c_str()));
  } else {
    sockfd_ = fd;
  }
}

void SocketCore::bind
(const char* addr, uint16_t port, int family, int flags)
{
  closeConnection();
  std::string error;
  const char* addrp;
  if(addr && addr[0]) {
    addrp = addr;
  } else {
    addrp = 0;
  }
  if(!(flags&AI_PASSIVE) || bindAddrs_.empty()) {
    sock_t fd = bindTo(addrp, port, family, sockType_, flags, error);
    if(fd != (sock_t) -1) {
      sockfd_ = fd;
    }
  } else {
    for(std::vector<std::pair<sockaddr_union, socklen_t> >::
          const_iterator i = bindAddrs_.begin(), eoi = bindAddrs_.end();
        i != eoi; ++i) {
      char host[NI_MAXHOST];
      int s;
      s = getnameinfo(&(*i).first.sa, (*i).second, host, NI_MAXHOST, 0, 0,
                      NI_NUMERICHOST);
      if(s) {
        error = gai_strerror(s);
        continue;
      }
      if(addrp && strcmp(host, addrp) != 0) {
        error = "Given address and resolved address do not match.";
        continue;
      }
      sock_t fd = bindTo(host, port, family, sockType_, flags, error);
      if(fd != (sock_t)-1) {
        sockfd_ = fd;
        break;
      }
    }
  }
  if(sockfd_ == (sock_t) -1) {
    throw DL_ABORT_EX(fmt(EX_SOCKET_BIND, error.c_str()));
  }
}

void SocketCore::bind(uint16_t port, int flags)
{
  bind(0, port, protocolFamily_, flags);
}

void SocketCore::bind(const struct sockaddr* addr, socklen_t addrlen)
{
  closeConnection();
  std::string error;
  sock_t fd = bindInternal(addr->sa_family, sockType_, 0, addr, addrlen, error);
  if(fd != (sock_t)-1) {
    sockfd_ = fd;
  } else {
    throw DL_ABORT_EX(fmt(EX_SOCKET_BIND, error.c_str()));
  }
}

void SocketCore::beginListen()
{
  if(listen(sockfd_, 1) == -1) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX(fmt(EX_SOCKET_LISTEN, errorMsg(errNum).c_str()));
  }
  setNonBlockingMode();
}

SharedHandle<SocketCore> SocketCore::acceptConnection() const
{
  sockaddr_union sockaddr;
  socklen_t len = sizeof(sockaddr);
  sock_t fd;
  while((fd = accept(sockfd_, &sockaddr.sa, &len)) == (sock_t) -1 &&
        SOCKET_ERRNO == A2_EINTR);
  int errNum = SOCKET_ERRNO;
  if(fd == (sock_t) -1) {
    throw DL_ABORT_EX(fmt(EX_SOCKET_ACCEPT, errorMsg(errNum).c_str()));
  }
  SharedHandle<SocketCore> sock(new SocketCore(fd, sockType_));
  sock->setNonBlockingMode();
  return sock;
}

int SocketCore::getAddrInfo(std::pair<std::string, uint16_t>& addrinfo) const
{
  sockaddr_union sockaddr;
  socklen_t len = sizeof(sockaddr);
  getAddrInfo(sockaddr, len);
  addrinfo = util::getNumericNameInfo(&sockaddr.sa, len);
  return sockaddr.storage.ss_family;
}

void SocketCore::getAddrInfo(sockaddr_union& sockaddr, socklen_t& len) const
{
  if(getsockname(sockfd_, &sockaddr.sa, &len) == -1) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX(fmt(EX_SOCKET_GET_NAME, errorMsg(errNum).c_str()));
  }
}

int SocketCore::getAddressFamily() const
{
  sockaddr_union sockaddr;
  socklen_t len = sizeof(sockaddr);
  getAddrInfo(sockaddr, len);
  return sockaddr.storage.ss_family;
}

int SocketCore::getPeerInfo(std::pair<std::string, uint16_t>& peerinfo) const
{
  sockaddr_union sockaddr;
  socklen_t len = sizeof(sockaddr);
  if(getpeername(sockfd_, &sockaddr.sa, &len) == -1) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX(fmt(EX_SOCKET_GET_NAME, errorMsg(errNum).c_str()));
  }
  peerinfo = util::getNumericNameInfo(&sockaddr.sa, len);
  return sockaddr.storage.ss_family;
}

void SocketCore::establishConnection(const std::string& host, uint16_t port,
                                     bool tcpNodelay)
{
  closeConnection();
  std::string error;
  struct addrinfo* res;
  int s;
  s = callGetaddrinfo(&res, host.c_str(), util::uitos(port).c_str(),
                      protocolFamily_, sockType_, 0, 0);
  if(s) {
    throw DL_ABORT_EX(fmt(EX_RESOLVE_HOSTNAME, host.c_str(), gai_strerror(s)));
  }
  WSAAPI_AUTO_DELETE<struct addrinfo*> resDeleter(res, freeaddrinfo);
  struct addrinfo* rp;
  int errNum;
  for(rp = res; rp; rp = rp->ai_next) {
    sock_t fd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
    errNum = SOCKET_ERRNO;
    if(fd == (sock_t) -1) {
      error = errorMsg(errNum);
      continue;
    }
    int sockopt = 1;
    if(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (a2_sockopt_t) &sockopt,
                  sizeof(sockopt)) < 0) {
      errNum = SOCKET_ERRNO;
      error = errorMsg(errNum);
      CLOSE(fd);
      continue;
    }
    if(!bindAddrs_.empty()) {
      bool bindSuccess = false;
      for(std::vector<std::pair<sockaddr_union, socklen_t> >::
            const_iterator i = bindAddrs_.begin(), eoi = bindAddrs_.end();
          i != eoi; ++i) {
        if(::bind(fd, &(*i).first.sa, (*i).second) == -1) {
          errNum = SOCKET_ERRNO;
          error = errorMsg(errNum);
          A2_LOG_DEBUG(fmt(EX_SOCKET_BIND, error.c_str()));
        } else {
          bindSuccess = true;
          break;
        }
      }
      if(!bindSuccess) {
        CLOSE(fd);
        continue;
      }
    }

    sockfd_ = fd;
    // make socket non-blocking mode
    setNonBlockingMode();
    if(tcpNodelay) {
      setTcpNodelay(true);
    }
    if(connect(fd, rp->ai_addr, rp->ai_addrlen) == -1 &&
       SOCKET_ERRNO != A2_EINPROGRESS) {
      errNum = SOCKET_ERRNO;
      error = errorMsg(errNum);
      CLOSE(sockfd_);
      sockfd_ = (sock_t) -1;
      continue;
    }
    // TODO at this point, connection may not be established and it may fail
    // later. In such case, next ai_addr should be tried.
    break;
  }
  if(sockfd_ == (sock_t) -1) {
    throw DL_ABORT_EX(fmt(EX_SOCKET_CONNECT, host.c_str(), error.c_str()));
  }
}

void SocketCore::setSockOpt
(int level, int optname, void* optval, socklen_t optlen)
{
  if(setsockopt(sockfd_, level, optname, (a2_sockopt_t)optval, optlen) < 0) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX(fmt(EX_SOCKET_SET_OPT, errorMsg(errNum).c_str()));
  }
}

void SocketCore::setMulticastInterface(const std::string& localAddr)
{
  in_addr addr;
  if(localAddr.empty()) {
    addr.s_addr = htonl(INADDR_ANY);
  } else {
    if(inetPton(AF_INET, localAddr.c_str(), &addr) != 0) {
      throw DL_ABORT_EX(fmt("%s is not valid IPv4 numeric address",
                            localAddr.c_str()));
    }
  }
  setSockOpt(IPPROTO_IP, IP_MULTICAST_IF, &addr, sizeof(addr));
}

void SocketCore::setMulticastTtl(unsigned char ttl)
{
  setSockOpt(IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
}

void SocketCore::setMulticastLoop(unsigned char loop)
{
  setSockOpt(IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop));
}

void SocketCore::joinMulticastGroup
(const std::string& multicastAddr, uint16_t multicastPort,
 const std::string& localAddr)
{
  in_addr multiAddr;
  if(inetPton(AF_INET, multicastAddr.c_str(), &multiAddr) != 0) {
    throw DL_ABORT_EX(fmt("%s is not valid IPv4 numeric address",
                          multicastAddr.c_str()));
  }
  in_addr ifAddr;
  if(localAddr.empty()) {
    ifAddr.s_addr = htonl(INADDR_ANY);
  } else {
    if(inetPton(AF_INET, localAddr.c_str(), &ifAddr) != 0) {
      throw DL_ABORT_EX(fmt("%s is not valid IPv4 numeric address",
                            localAddr.c_str()));
    }
  }
  struct ip_mreq mreq;
  memset(&mreq, 0, sizeof(mreq));
  mreq.imr_multiaddr = multiAddr;
  mreq.imr_interface = ifAddr;
  setSockOpt(IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
}

void SocketCore::setTcpNodelay(bool f)
{
  int val = f;
  setSockOpt(IPPROTO_TCP, TCP_NODELAY, &val, sizeof(val));
}

void SocketCore::setNonBlockingMode()
{
#ifdef __MINGW32__
  static u_long flag = 1;
  if (::ioctlsocket(sockfd_, FIONBIO, &flag) == -1) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX(fmt(EX_SOCKET_NONBLOCKING, errorMsg(errNum).c_str()));
  }
#else
  int flags;
  while((flags = fcntl(sockfd_, F_GETFL, 0)) == -1 && errno == EINTR);
  // TODO add error handling
  while(fcntl(sockfd_, F_SETFL, flags|O_NONBLOCK) == -1 && errno == EINTR);
#endif // __MINGW32__
  blocking_ = false;
}

void SocketCore::setBlockingMode()
{
#ifdef __MINGW32__
  static u_long flag = 0;
  if (::ioctlsocket(sockfd_, FIONBIO, &flag) == -1) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX(fmt(EX_SOCKET_BLOCKING, errorMsg(errNum).c_str()));
  }
#else
  int flags;
  while((flags = fcntl(sockfd_, F_GETFL, 0)) == -1 && errno == EINTR);
  // TODO add error handling
  while(fcntl(sockfd_, F_SETFL, flags&(~O_NONBLOCK)) == -1 && errno == EINTR);
#endif // __MINGW32__
  blocking_ = true;
}

void SocketCore::closeConnection()
{
  if(tlsSession_) {
    tlsSession_->closeConnection();
    tlsSession_.reset();
  }
  if(sockfd_ != (sock_t) -1) {
    shutdown(sockfd_, SHUT_WR);
    CLOSE(sockfd_);
    sockfd_ = -1;
  }
}

#ifndef __MINGW32__
# define CHECK_FD(fd)                                                   \
  if(fd < 0 || FD_SETSIZE <= fd) {                                      \
    logger_->warn("Detected file descriptor >= FD_SETSIZE or < 0. "     \
                  "Download may slow down or fail.");                   \
    return false;                                                       \
  }
#endif // !__MINGW32__

bool SocketCore::isWritable(time_t timeout)
{
#ifdef HAVE_POLL
  struct pollfd p;
  p.fd = sockfd_;
  p.events = POLLOUT;
  int r;
  while((r = poll(&p, 1, timeout*1000)) == -1 && errno == EINTR);
  int errNum = SOCKET_ERRNO;
  if(r > 0) {
    return p.revents&(POLLOUT|POLLHUP|POLLERR);
  } else if(r == 0) {
    return false;
  } else {
    throw DL_RETRY_EX(fmt(EX_SOCKET_CHECK_WRITABLE, errorMsg(errNum).c_str()));
  }
#else // !HAVE_POLL
# ifndef __MINGW32__
  CHECK_FD(sockfd_);
# endif // !__MINGW32__
  fd_set fds;
  FD_ZERO(&fds);
  FD_SET(sockfd_, &fds);

  struct timeval tv;
  tv.tv_sec = timeout;
  tv.tv_usec = 0;

  int r = select(sockfd_+1, NULL, &fds, NULL, &tv);
  int errNum = SOCKET_ERRNO;
  if(r == 1) {
    return true;
  } else if(r == 0) {
    // time out
    return false;
  } else {
    if(errNum == A2_EINPROGRESS || errNum == A2_EINTR) {
      return false;
    } else {
      throw DL_RETRY_EX
        (fmt(EX_SOCKET_CHECK_WRITABLE, errorMsg(errNum).c_str()));
    }
  }
#endif // !HAVE_POLL
}

bool SocketCore::isReadable(time_t timeout)
{
#ifdef HAVE_POLL
  struct pollfd p;
  p.fd = sockfd_;
  p.events = POLLIN;
  int r;
  while((r = poll(&p, 1, timeout*1000)) == -1 && errno == EINTR);
  int errNum = SOCKET_ERRNO;
  if(r > 0) {
    return p.revents&(POLLIN|POLLHUP|POLLERR);
  } else if(r == 0) {
    return false;
  } else {
    throw DL_RETRY_EX(fmt(EX_SOCKET_CHECK_READABLE, errorMsg(errNum).c_str()));
  }
#else // !HAVE_POLL
# ifndef __MINGW32__
  CHECK_FD(sockfd_);
# endif // !__MINGW32__
  fd_set fds;
  FD_ZERO(&fds);
  FD_SET(sockfd_, &fds);

  struct timeval tv;
  tv.tv_sec = timeout;
  tv.tv_usec = 0;

  int r = select(sockfd_+1, &fds, NULL, NULL, &tv);
  int errNum = SOCKET_ERRNO;
  if(r == 1) {
    return true;
  } else if(r == 0) {
    // time out
    return false;
  } else {
    if(errNum == A2_EINPROGRESS || errNum == A2_EINTR) {
      return false;
    } else {
      throw DL_RETRY_EX
        (fmt(EX_SOCKET_CHECK_READABLE, errorMsg(errNum).c_str()));
    }
  }
#endif // !HAVE_POLL
}

ssize_t SocketCore::writeVector(a2iovec *iov, size_t iovcnt)
{
  ssize_t ret = 0;
  wantRead_ = false;
  wantWrite_ = false;
  if(!secure_) {
#ifdef __MINGW32__
    DWORD nsent;
    int rv = WSASend(sockfd_, iov, iovcnt, &nsent, 0, 0, 0);
    if(rv == 0) {
      ret = nsent;
    } else {
      ret = -1;
    }
#else // !__MINGW32__
    while((ret = writev(sockfd_, iov, iovcnt)) == -1 &&
          SOCKET_ERRNO == A2_EINTR);
#endif // !__MINGW32__
    int errNum = SOCKET_ERRNO;
    if(ret == -1) {
      if(A2_WOULDBLOCK(errNum)) {
        wantWrite_ = true;
        ret = 0;
      } else {
        throw DL_RETRY_EX(fmt(EX_SOCKET_SEND, errorMsg(errNum).c_str()));
      }
    }
  } else {
    // For SSL/TLS, we could not use writev, so just iterate vector
    // and write the data in normal way.
    for(size_t i = 0; i < iovcnt; ++i) {
      ssize_t rv = writeData(iov[i].A2IOVEC_BASE, iov[i].A2IOVEC_LEN);
      if(rv == 0) {
        break;
      }
      ret += rv;
    }
  }
  return ret;
}

ssize_t SocketCore::writeData(const void* data, size_t len)
{
  ssize_t ret = 0;
  wantRead_ = false;
  wantWrite_ = false;

  if(!secure_) {
    // Cast for Windows send()
    while((ret = send(sockfd_, reinterpret_cast<const char*>(data),
                      len, 0)) == -1 && SOCKET_ERRNO == A2_EINTR);
    int errNum = SOCKET_ERRNO;
    if(ret == -1) {
      if(A2_WOULDBLOCK(errNum)) {
        wantWrite_ = true;
        ret = 0;
      } else {
        throw DL_RETRY_EX(fmt(EX_SOCKET_SEND, errorMsg(errNum).c_str()));
      }
    }
  } else {
    ret = tlsSession_->writeData(data, len);
    if(ret < 0) {
      if(ret == TLS_ERR_WOULDBLOCK) {
        if(tlsSession_->checkDirection() == TLS_WANT_READ) {
          wantRead_ = true;
        } else {
          wantWrite_ = true;
        }
        ret = 0;
      } else {
        throw DL_RETRY_EX(fmt(EX_SOCKET_SEND,
                              tlsSession_->getLastErrorString().c_str()));
      }
    }
  }
  return ret;
}

void SocketCore::readData(void* data, size_t& len)
{
  ssize_t ret = 0;
  wantRead_ = false;
  wantWrite_ = false;

  if(!secure_) {
    // Cast for Windows recv()
    while((ret = recv(sockfd_, reinterpret_cast<char*>(data), len, 0)) == -1 &&
          SOCKET_ERRNO == A2_EINTR);
    int errNum = SOCKET_ERRNO;
    if(ret == -1) {
      if(A2_WOULDBLOCK(errNum)) {
        wantRead_ = true;
        ret = 0;
      } else {
        throw DL_RETRY_EX(fmt(EX_SOCKET_RECV, errorMsg(errNum).c_str()));
      }
    }
  } else {
    ret = tlsSession_->readData(data, len);
    if(ret < 0) {
      if(ret == TLS_ERR_WOULDBLOCK) {
        if(tlsSession_->checkDirection() == TLS_WANT_READ) {
          wantRead_ = true;
        } else {
          wantWrite_ = true;
        }
        ret = 0;
      } else {
        throw DL_RETRY_EX(fmt(EX_SOCKET_SEND,
                              tlsSession_->getLastErrorString().c_str()));
      }
    }
  }
  len = ret;
}

#ifdef ENABLE_SSL

bool SocketCore::tlsAccept()
{
  return tlsHandshake(svTlsContext_.get(), A2STR::NIL);
}

bool SocketCore::tlsConnect(const std::string& hostname)
{
  return tlsHandshake(clTlsContext_.get(), hostname);
}

bool SocketCore::tlsHandshake(TLSContext* tlsctx, const std::string& hostname)
{
  int rv = 0;
  std::string handshakeError;
  wantRead_ = false;
  wantWrite_ = false;
  switch(secure_) {
  case A2_TLS_NONE:
    tlsSession_.reset(new TLSSession(tlsctx));
    rv = tlsSession_->init(sockfd_);
    if(rv != TLS_ERR_OK) {
      std::string error = tlsSession_->getLastErrorString();
      tlsSession_.reset();
      throw DL_ABORT_EX(fmt(EX_SSL_INIT_FAILURE, error.c_str()));
    }
    // Check hostname is not numeric and it includes ".". Setting
    // "localhost" will produce TLS alert with GNUTLS.
    if(tlsctx->getSide() == TLS_CLIENT &&
       !util::isNumericHost(hostname) &&
       hostname.find(".") != std::string::npos) {
      rv = tlsSession_->setSNIHostname(hostname);
      if(rv != TLS_ERR_OK) {
        throw DL_ABORT_EX(fmt(EX_SSL_INIT_FAILURE,
                              tlsSession_->getLastErrorString().c_str()));
      }
    }
    secure_ = A2_TLS_HANDSHAKING;
    // Fall through
  case A2_TLS_HANDSHAKING:
    if(tlsctx->getSide() == TLS_CLIENT) {
      rv = tlsSession_->tlsConnect(hostname, handshakeError);
    } else {
      rv = tlsSession_->tlsAccept();
    }
    if(rv == TLS_ERR_OK) {
      secure_ = A2_TLS_CONNECTED;
    } else if(rv == TLS_ERR_WOULDBLOCK) {
      if(tlsSession_->checkDirection() == TLS_WANT_READ) {
        wantRead_ = true;
      } else {
        wantWrite_ = true;
      }
      return false;
    } else {
      throw DL_ABORT_EX(fmt("SSL/TLS handshake failure: %s",
                            handshakeError.empty() ?
                            tlsSession_->getLastErrorString().c_str() :
                            handshakeError.c_str()));
    }
    break;
  default:
    break;
  }
  return true;
}

#endif // ENABLE_SSL

ssize_t SocketCore::writeData(const void* data, size_t len,
                              const std::string& host, uint16_t port)
{
  wantRead_ = false;
  wantWrite_ = false;

  struct addrinfo* res;
  int s;
  s = callGetaddrinfo(&res, host.c_str(), util::uitos(port).c_str(),
                      protocolFamily_, sockType_, 0, 0);
  if(s) {
    throw DL_ABORT_EX(fmt(EX_SOCKET_SEND, gai_strerror(s)));
  }
  WSAAPI_AUTO_DELETE<struct addrinfo*> resDeleter(res, freeaddrinfo);
  struct addrinfo* rp;
  ssize_t r = -1;
  int errNum = 0;
  for(rp = res; rp; rp = rp->ai_next) {
    // Cast for Windows sendto()
    while((r = sendto(sockfd_, reinterpret_cast<const char*>(data), len, 0,
                      rp->ai_addr, rp->ai_addrlen)) == -1
          && A2_EINTR == SOCKET_ERRNO);
    errNum = SOCKET_ERRNO;
    if(r == static_cast<ssize_t>(len)) {
      break;
    }
    if(r == -1 && A2_WOULDBLOCK(errNum)) {
      wantWrite_ = true;
      r = 0;
      break;
    }
  }
  if(r == -1) {
    throw DL_ABORT_EX(fmt(EX_SOCKET_SEND, errorMsg(errNum).c_str()));
  }
  return r;
}

ssize_t SocketCore::readDataFrom(void* data, size_t len,
                                 std::pair<std::string /* numerichost */,
                                 uint16_t /* port */>& sender)
{
  wantRead_ = false;
  wantWrite_ = false;
  sockaddr_union sockaddr;
  socklen_t sockaddrlen = sizeof(sockaddr);
  ssize_t r;
  // Cast for Windows recvfrom()
  while((r = recvfrom(sockfd_, reinterpret_cast<char*>(data), len, 0,
                      &sockaddr.sa, &sockaddrlen)) == -1
        && A2_EINTR == SOCKET_ERRNO);
  int errNum = SOCKET_ERRNO;
  if(r == -1) {
    if(A2_WOULDBLOCK(errNum)) {
      wantRead_ = true;
      r = 0;
    } else {
      throw DL_RETRY_EX(fmt(EX_SOCKET_RECV, errorMsg(errNum).c_str()));
    }
  } else {
    sender = util::getNumericNameInfo(&sockaddr.sa, sockaddrlen);
  }

  return r;
}

std::string SocketCore::getSocketError() const
{
  int error;
  socklen_t optlen = sizeof(error);

  if(getsockopt(sockfd_, SOL_SOCKET, SO_ERROR,
                (a2_sockopt_t) &error, &optlen) == -1) {
    int errNum = SOCKET_ERRNO;
    throw DL_ABORT_EX
      (fmt("Failed to get socket error: %s", errorMsg(errNum).c_str()));
  }
  if(error != 0) {
    return errorMsg(error);
  } else {
    return "";
  }
}

bool SocketCore::wantRead() const
{
  return wantRead_;
}

bool SocketCore::wantWrite() const
{
  return wantWrite_;
}

void SocketCore::bindAddress(const std::string& iface)
{
  std::vector<std::pair<sockaddr_union, socklen_t> > bindAddrs;
  getInterfaceAddress(bindAddrs, iface, protocolFamily_);
  if(bindAddrs.empty()) {
    throw DL_ABORT_EX
      (fmt(MSG_INTERFACE_NOT_FOUND, iface.c_str(), "not available"));
  } else {
    bindAddrs_.swap(bindAddrs);
    for(std::vector<std::pair<sockaddr_union, socklen_t> >::
          const_iterator i = bindAddrs_.begin(), eoi = bindAddrs_.end();
        i != eoi; ++i) {
      char host[NI_MAXHOST];
      int s;
      s = getnameinfo(&(*i).first.sa, (*i).second, host, NI_MAXHOST, 0, 0,
                      NI_NUMERICHOST);
      if(s == 0) {
        A2_LOG_DEBUG(fmt("Sockets will bind to %s", host));
      }
    }
  }
}

void getInterfaceAddress
(std::vector<std::pair<sockaddr_union, socklen_t> >& ifAddrs,
 const std::string& iface, int family, int aiFlags)
{
  A2_LOG_DEBUG(fmt("Finding interface %s", iface.c_str()));
#ifdef HAVE_GETIFADDRS
  // First find interface in interface addresses
  struct ifaddrs* ifaddr = 0;
  if(getifaddrs(&ifaddr) == -1) {
    int errNum = SOCKET_ERRNO;
    A2_LOG_INFO(fmt(MSG_INTERFACE_NOT_FOUND,
                    iface.c_str(), errorMsg(errNum).c_str()));
  } else {
    auto_delete<ifaddrs*> ifaddrDeleter(ifaddr, freeifaddrs);
    for(ifaddrs* ifa = ifaddr; ifa; ifa = ifa->ifa_next) {
      if(!ifa->ifa_addr) {
        continue;
      }
      int iffamily = ifa->ifa_addr->sa_family;
      if(family == AF_UNSPEC) {
        if(iffamily != AF_INET && iffamily != AF_INET6) {
          continue;
        }
      } else if(family == AF_INET) {
        if(iffamily != AF_INET) {
          continue;
        }
      } else if(family == AF_INET6) {
        if(iffamily != AF_INET6) {
          continue;
        }
      } else {
        continue;
      }
      if(strcmp(iface.c_str(), ifa->ifa_name) == 0) {
        socklen_t bindAddrLen =
          iffamily == AF_INET ? sizeof(sockaddr_in) : sizeof(sockaddr_in6);
        sockaddr_union bindAddr;
        memset(&bindAddr, 0, sizeof(bindAddr));
        memcpy(&bindAddr.storage, ifa->ifa_addr, bindAddrLen);
        ifAddrs.push_back(std::make_pair(bindAddr, bindAddrLen));
      }
    }
  }
#endif // HAVE_GETIFADDRS
  if(ifAddrs.empty()) {
    addrinfo* res;
    int s;
    s = callGetaddrinfo(&res, iface.c_str(), 0, family, SOCK_STREAM, aiFlags,0);
    if(s) {
      A2_LOG_INFO(fmt(MSG_INTERFACE_NOT_FOUND, iface.c_str(), gai_strerror(s)));
    } else {
      WSAAPI_AUTO_DELETE<addrinfo*> resDeleter(res, freeaddrinfo);
      addrinfo* rp;
      for(rp = res; rp; rp = rp->ai_next) {
        // Try to bind socket with this address. If it fails, the
        // address is not for this machine.
        try {
          SocketCore socket;
          socket.bind(rp->ai_addr, rp->ai_addrlen);
          sockaddr_union bindAddr;
          memset(&bindAddr, 0, sizeof(bindAddr));
          memcpy(&bindAddr.storage, rp->ai_addr, rp->ai_addrlen);
          ifAddrs.push_back(std::make_pair(bindAddr, rp->ai_addrlen));
        } catch(RecoverableException& e) {
          continue;
        }
      }
    }
  }
}

namespace {

int defaultAIFlags = DEFAULT_AI_FLAGS;

int getDefaultAIFlags()
{
  return defaultAIFlags;
}

} // namespace

void setDefaultAIFlags(int flags)
{
  defaultAIFlags = flags;
}

int callGetaddrinfo
(struct addrinfo** resPtr, const char* host, const char* service, int family,
 int sockType, int flags, int protocol)
{
  struct addrinfo hints;
  memset(&hints, 0, sizeof(hints));
  hints.ai_family = family;
  hints.ai_socktype = sockType;
  hints.ai_flags = getDefaultAIFlags();
  hints.ai_flags |= flags;
  hints.ai_protocol = protocol;
  return getaddrinfo(host, service, &hints, resPtr);
}

int inetNtop(int af, const void* src, char* dst, socklen_t size)
{
  int s;
  sockaddr_union su;
  memset(&su, 0, sizeof(su));
  if(af == AF_INET) {
    su.in.sin_family = AF_INET;
#ifdef HAVE_SOCKADDR_IN_SIN_LEN
    su.in.sin_len = sizeof(su.in);
#endif // HAVE_SOCKADDR_IN_SIN_LEN
    memcpy(&su.in.sin_addr, src, sizeof(su.in.sin_addr));
    s = getnameinfo(&su.sa, sizeof(su.in),
                    dst, size, 0, 0, NI_NUMERICHOST);
  } else if(af == AF_INET6) {
    su.in6.sin6_family = AF_INET6;
#ifdef HAVE_SOCKADDR_IN6_SIN6_LEN
    su.in6.sin6_len = sizeof(su.in6);
#endif // HAVE_SOCKADDR_IN6_SIN6_LEN
    memcpy(&su.in6.sin6_addr, src, sizeof(su.in6.sin6_addr));
    s = getnameinfo(&su.sa, sizeof(su.in6),
                    dst, size, 0, 0, NI_NUMERICHOST);
  } else {
    s = EAI_FAMILY;
  }
  return s;
}

int inetPton(int af, const char* src, void* dst)
{
  union {
    uint32_t ipv4_addr;
    unsigned char ipv6_addr[16];
  } binaddr;
  size_t len = net::getBinAddr(binaddr.ipv6_addr, src);
  if(af == AF_INET) {
    if(len != 4) {
      return -1;
    }
    in_addr* addr = reinterpret_cast<in_addr*>(dst);
    addr->s_addr = binaddr.ipv4_addr;
  } else if(af == AF_INET6) {
    if(len != 16) {
      return -1;
    }
    in6_addr* addr = reinterpret_cast<in6_addr*>(dst);
    memcpy(addr->s6_addr, binaddr.ipv6_addr, sizeof(addr->s6_addr));
  } else {
    return -1;
  }
  return 0;
}

namespace net {

size_t getBinAddr(void* dest, const std::string& ip)
{
  size_t len = 0;
  addrinfo* res;
  if(callGetaddrinfo(&res, ip.c_str(), 0, AF_UNSPEC,
                     0, AI_NUMERICHOST, 0) != 0) {
    return len;
  }
  WSAAPI_AUTO_DELETE<addrinfo*> resDeleter(res, freeaddrinfo);
  for(addrinfo* rp = res; rp; rp = rp->ai_next) {
    sockaddr_union su;
    memcpy(&su, rp->ai_addr, rp->ai_addrlen);
    if(rp->ai_family == AF_INET) {
      len = sizeof(in_addr);
      memcpy(dest, &(su.in.sin_addr), len);
      break;
    } else if(rp->ai_family == AF_INET6) {
      len = sizeof(in6_addr);
      memcpy(dest, &(su.in6.sin6_addr), len);
      break;
    }
  }
  return len;
}

bool verifyHostname(const std::string& hostname,
                    const std::vector<std::string>& dnsNames,
                    const std::vector<std::string>& ipAddrs,
                    const std::string& commonName)
{
  if(util::isNumericHost(hostname)) {
    if(ipAddrs.empty()) {
      return commonName == hostname;
    }
    // We need max 16 bytes to store IPv6 address.
    unsigned char binAddr[16];
    size_t addrLen = getBinAddr(binAddr, hostname);
    if(addrLen == 0) {
      return false;
    }
    for(std::vector<std::string>::const_iterator i = ipAddrs.begin(),
          eoi = ipAddrs.end(); i != eoi; ++i) {
      if(addrLen == (*i).size() &&
         memcmp(binAddr, (*i).c_str(), addrLen) == 0) {
        return true;
      }
    }
  } else {
    if(dnsNames.empty()) {
      return util::tlsHostnameMatch(commonName, hostname);
    }
    for(std::vector<std::string>::const_iterator i = dnsNames.begin(),
          eoi = dnsNames.end(); i != eoi; ++i) {
      if(util::tlsHostnameMatch(*i, hostname)) {
        return true;
      }
    }
  }
  return false;
}

namespace {
bool ipv4AddrConfigured = true;
bool ipv6AddrConfigured = true;
} // namespace

#ifdef __MINGW32__
namespace {
const uint32_t APIPA_IPV4_BEGIN = 2851995649u; // 169.254.0.1
const uint32_t APIPA_IPV4_END = 2852061183u; // 169.254.255.255
} // namespace
#endif // __MINGW32__

void checkAddrconfig()
{
#ifdef __MINGW32__
  A2_LOG_INFO("Checking configured addresses");
  ULONG bufsize = 15*1024;
  ULONG retval = 0;
  IP_ADAPTER_ADDRESSES* buf = 0;
  int numTry = 0;
  const int MAX_TRY = 3;
  do {
    buf = reinterpret_cast<IP_ADAPTER_ADDRESSES*>(malloc(bufsize));
    retval = GetAdaptersAddresses(AF_UNSPEC, 0, 0, buf, &bufsize);
    if(retval == ERROR_BUFFER_OVERFLOW) {
      free(buf);
      buf = 0;
    } else {
      break;
    }
  } while(retval == ERROR_BUFFER_OVERFLOW && numTry < MAX_TRY);
  if(retval != NO_ERROR) {
    A2_LOG_INFO("GetAdaptersAddresses failed. Assume both IPv4 and IPv6 "
                " addresses are configured.");
    return;
  }
  ipv4AddrConfigured = false;
  ipv6AddrConfigured = false;
  char host[NI_MAXHOST];
  sockaddr_union ad;
  int rv;
  for(IP_ADAPTER_ADDRESSES* p = buf; p; p = p->Next) {
    if(p->IfType == IF_TYPE_TUNNEL) {
      // Skip tunnel interface because Windows7 automatically setup
      // this for IPv6.
      continue;
    }
    PIP_ADAPTER_UNICAST_ADDRESS ucaddr = p->FirstUnicastAddress;
    if(ucaddr) {
      for(PIP_ADAPTER_UNICAST_ADDRESS i = ucaddr; i; i = i->Next) {
        bool found = false;
        switch(i->Address.iSockaddrLength) {
        case sizeof(sockaddr_in): {
          memcpy(&ad.storage, i->Address.lpSockaddr,
                 i->Address.iSockaddrLength);
          uint32_t haddr = ntohl(ad.in.sin_addr.s_addr);
          if(haddr != INADDR_LOOPBACK &&
             (haddr < APIPA_IPV4_BEGIN || APIPA_IPV4_END <= haddr)) {
            ipv4AddrConfigured = true;
            found = true;
          }
          break;
        }
        case sizeof(sockaddr_in6):
          memcpy(&ad.storage, i->Address.lpSockaddr,
                 i->Address.iSockaddrLength);
          if(!IN6_IS_ADDR_LOOPBACK(&ad.in6.sin6_addr) &&
             !IN6_IS_ADDR_LINKLOCAL(&ad.in6.sin6_addr)) {
            ipv6AddrConfigured = true;
            found = true;
          }
          break;
        }
        rv = getnameinfo(i->Address.lpSockaddr, i->Address.iSockaddrLength,
                         host, NI_MAXHOST, 0, 0, NI_NUMERICHOST);
        if(rv == 0) {
          if(found) {
            A2_LOG_INFO(fmt("Found configured address: %s", host));
          } else {
            A2_LOG_INFO(fmt("Not considered: %s", host));
          }
        }
      }
    }
  }
  free(buf);
  A2_LOG_INFO(fmt("IPv4 configured=%d, IPv6 configured=%d",
                  ipv4AddrConfigured, ipv6AddrConfigured));
#elif defined(HAVE_GETIFADDRS)
  A2_LOG_INFO("Checking configured addresses");
  ipv4AddrConfigured = false;
  ipv6AddrConfigured = false;
  ifaddrs* ifaddr = 0;
  int rv;
  rv = getifaddrs(&ifaddr);
  if(rv == -1) {
    int errNum = SOCKET_ERRNO;
    A2_LOG_INFO(fmt("getifaddrs failed. Cause: %s", errorMsg(errNum).c_str()));
    return;
  }
  auto_delete<ifaddrs*> ifaddrDeleter(ifaddr, freeifaddrs);
  char host[NI_MAXHOST];
  sockaddr_union ad;
  for(ifaddrs* ifa = ifaddr; ifa; ifa = ifa->ifa_next) {
    if(!ifa->ifa_addr) {
      continue;
    }
    bool found = false;
    size_t addrlen = 0;
    switch(ifa->ifa_addr->sa_family) {
    case AF_INET: {
      addrlen = sizeof(sockaddr_in);
      memcpy(&ad.storage, ifa->ifa_addr, addrlen);
      if(ad.in.sin_addr.s_addr != htonl(INADDR_LOOPBACK)) {
        ipv4AddrConfigured = true;
        found = true;
      }
      break;
    }
    case AF_INET6: {
      addrlen = sizeof(sockaddr_in6);
      memcpy(&ad.storage, ifa->ifa_addr, addrlen);
      if(!IN6_IS_ADDR_LOOPBACK(&ad.in6.sin6_addr) &&
         !IN6_IS_ADDR_LINKLOCAL(&ad.in6.sin6_addr)) {
        ipv6AddrConfigured = true;
        found = true;
      }
      break;
    }
    default:
      continue;
    }
    rv = getnameinfo(ifa->ifa_addr, addrlen, host, NI_MAXHOST, 0, 0,
                     NI_NUMERICHOST);
    if(rv == 0) {
      if(found) {
        A2_LOG_INFO(fmt("Found configured address: %s", host));
      } else {
        A2_LOG_INFO(fmt("Not considered: %s", host));
      }
    }
  }
  A2_LOG_INFO(fmt("IPv4 configured=%d, IPv6 configured=%d",
                  ipv4AddrConfigured, ipv6AddrConfigured));
#else // !HAVE_GETIFADDRS
  A2_LOG_INFO("getifaddrs is not available. Assume IPv4 and IPv6 addresses"
              " are configured.");
#endif // !HAVE_GETIFADDRS
}

bool getIPv4AddrConfigured()
{
  return ipv4AddrConfigured;
}

bool getIPv6AddrConfigured()
{
  return ipv6AddrConfigured;
}

} // namespace net

} // namespace aria2