TPSocket.cxx

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// @(#)root/net:$Id$
// Author: Fons Rademakers   22/1/2001
 
/*************************************************************************
 * Copyright (C) 1995-2001, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
/**
\file TPSocket.cxx
\class TPSocket
\brief This class implements parallel server sockets.
\note This class deals with sockets: the user is entirely responsible for the security of their usage, for example, but
not limited to, the management of the connections to said sockets.
 
A parallel socket is an endpoint for communication between two machines. It is parallel
because several TSockets are open at the same time to the same
destination. This especially speeds up communication over Big Fat
Pipes (i.e. high bandwidth, high latency WAN connections).
 
**/
 
#include "TPSocket.h"
#include "TUrl.h"
#include "TServerSocket.h"
#include "TMonitor.h"
#include "TSystem.h"
#include "TMessage.h"
#include "Bytes.h"
#include "TROOT.h"
#include "TError.h"
#include "TVirtualMutex.h"
 
 
ClassImp(TPSocket);
#include <limits>
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket. Connect to the named service at address addr.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Returns when connection has been accepted by remote side. Use IsValid()
/// to check the validity of the socket. Every socket is added to the TROOT
/// sockets list which will make sure that any open sockets are properly
/// closed on program termination.
 
TPSocket::TPSocket(TInetAddress addr, const char *service, Int_t size,
                   Int_t tcpwindowsize) : TSocket(addr, service)
{
   fSize = size;
   Init(tcpwindowsize);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket. Connect to the specified port # at address addr.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Returns when connection has been accepted by remote side. Use IsValid()
/// to check the validity of the socket. Every socket is added to the TROOT
/// sockets list which will make sure that any open sockets are properly
/// closed on program termination.
 
TPSocket::TPSocket(TInetAddress addr, Int_t port, Int_t size,
                   Int_t tcpwindowsize) : TSocket(addr, port)
{
   fSize = size;
   Init(tcpwindowsize);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket. Connect to named service on the remote host.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Returns when connection has been accepted by remote side. Use IsValid()
/// to check the validity of the socket. Every socket is added to the TROOT
/// sockets list which will make sure that any open sockets are properly
/// closed on program termination.
 
TPSocket::TPSocket(const char *host, const char *service, Int_t size,
                   Int_t tcpwindowsize) : TSocket(host, service)
{
   fSize = size;
   Init(tcpwindowsize);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket. Connect to specified port # on the remote host.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Returns when connection has been accepted by remote side. Use IsValid()
/// to check the validity of the socket. Every socket is added to the TROOT
/// sockets list which will make sure that any open sockets are properly
/// closed on program termination.
 
TPSocket::TPSocket(const char *host, Int_t port, Int_t size,
                   Int_t tcpwindowsize)
                  : TSocket(host, port, (Int_t)(size > 1 ? -1 : tcpwindowsize))
{
   // set to the real value only at end (except for old servers)
   fSize           = 1;
 
   // to control the flow
   Bool_t valid = TSocket::IsValid();
 
   // check if we are called from CreateAuthSocket()
   Bool_t authreq = kFALSE;
   char *pauth = (char *)strstr(host, "?A");
   if (pauth) {
      authreq = kTRUE;
   }
 
   // perhaps we can use fServType here ... to be checked
   Bool_t rootdSrv = (strstr(host,"rootd")) ? kTRUE : kFALSE;
 
   // try authentication , if required
   if (authreq) {
      if (valid) {
         if (!Authenticate(TUrl(host).GetUser())) {
            if (rootdSrv && (fRemoteProtocol > 0 && fRemoteProtocol < 10)) {
               // We failed because we are talking to an old
               // server: we need to re-open the connection
               // and communicate the size first
               Int_t tcpw = (size > 1 ? -1 : tcpwindowsize);
               TSocket *ns = new TSocket(host, port, tcpw);
               if (ns->IsValid()) {
                  R__LOCKGUARD(gROOTMutex);
                  gROOT->GetListOfSockets()->Remove(ns);
                  fSocket = ns->GetDescriptor();
                  fSize = size;
                  Init(tcpwindowsize);
               }
               if ((valid = IsValid())) {
                  if (!Authenticate(TUrl(host).GetUser())) {
                     TSocket::Close();
                     valid = kFALSE;
                  }
               }
            } else {
               TSocket::Close();
               valid = kFALSE;
            }
         }
      }
      // reset url to the original state
      *pauth = '\0';
      SetUrl(host);
   }
 
   // open the sockets ...
   if (!rootdSrv || fRemoteProtocol > 9) {
      if (valid) {
         fSize = size;
         Init(tcpwindowsize);
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket on a connection already opened via
/// TSocket sock.
/// This constructor is provided to optimize TNetFile opening when
/// instatiated via a call to TNetXNGFile.
/// Returns when connection has been accepted by remote side. Use IsValid()
/// to check the validity of the socket. Every socket is added to the TROOT
/// sockets list which will make sure that any open sockets are properly
/// closed on program termination.
 
TPSocket::TPSocket(const char *host, Int_t port, Int_t size, TSocket *sock)
{
   // To avoid uninitialization problems when Init is not called ...
   fSockets        = 0;
   fWriteMonitor   = 0;
   fReadMonitor    = 0;
   fWriteBytesLeft = 0;
   fReadBytesLeft  = 0;
   fWritePtr       = 0;
   fReadPtr        = 0;
 
   // set to the real value only at end (except for old servers)
   fSize           = 1;
 
   // We need a opened connection
   if (!sock) return;
 
   // Now import existing socket info
   fSocket         = sock->GetDescriptor();
   fService        = sock->GetService();
   fAddress        = sock->GetInetAddress();
   fLocalAddress   = sock->GetLocalInetAddress();
   fBytesSent      = sock->GetBytesSent();
   fBytesRecv      = sock->GetBytesRecv();
   fCompress       = sock->GetCompressionSettings();
   fSecContext     = sock->GetSecContext();
   fRemoteProtocol = sock->GetRemoteProtocol();
   fServType       = (TSocket::EServiceType)sock->GetServType();
   fTcpWindowSize  = sock->GetTcpWindowSize();
 
   // to control the flow
   Bool_t valid = sock->IsValid();
 
   // check if we are called from CreateAuthSocket()
   Bool_t authreq = kFALSE;
   char *pauth = (char *)strstr(host, "?A");
   if (pauth) {
      authreq = kTRUE;
   }
 
   // perhaps we can use fServType here ... to be checked
   Bool_t rootdSrv = (strstr(host,"rootd")) ? kTRUE : kFALSE;
 
   // try authentication , if required
   if (authreq) {
      if (valid) {
         if (!Authenticate(TUrl(host).GetUser())) {
            if (rootdSrv && (fRemoteProtocol > 0 && fRemoteProtocol < 10)) {
               // We failed because we are talking to an old
               // server: we need to re-open the connection
               // and communicate the size first
               Int_t tcpw = (size > 1 ? -1 : fTcpWindowSize);
               TSocket *ns = new TSocket(host, port, tcpw);
               if (ns->IsValid()) {
                  R__LOCKGUARD(gROOTMutex);
                  gROOT->GetListOfSockets()->Remove(ns);
                  fSocket = ns->GetDescriptor();
                  fSize = size;
                  Init(fTcpWindowSize);
               }
               if ((valid = IsValid())) {
                  if (!Authenticate(TUrl(host).GetUser())) {
                     TSocket::Close();
                     valid = kFALSE;
                  }
               }
            } else {
               TSocket::Close();
               valid = kFALSE;
            }
         }
      }
      // reset url to the original state
      *pauth = '\0';
      SetUrl(host);
   }
 
   // open the sockets ...
   if (!rootdSrv || fRemoteProtocol > 9) {
      if (valid) {
         fSize = size;
         Init(fTcpWindowSize, sock);
      }
   }
 
   // Add to the list if everything OK
   if (IsValid()) {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfSockets()->Add(this);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket. This ctor is called by TPServerSocket.
 
TPSocket::TPSocket(TSocket *pSockets[], Int_t size)
{
   fSockets = pSockets;
   fSize    = size;
 
   // set descriptor if simple socket (needed when created
   // by TPServerSocket)
   if (fSize <= 1)
      fSocket = fSockets[0]->GetDescriptor();
 
   // set socket options (no blocking and no delay)
   SetOption(kNoDelay, 1);
   if (fSize > 1)
      SetOption(kNoBlock, 1);
 
   fWriteMonitor   = new TMonitor;
   fReadMonitor    = new TMonitor;
   fWriteBytesLeft = new Int_t[fSize];
   fReadBytesLeft  = new Int_t[fSize];
   fWritePtr       = new char*[fSize];
   fReadPtr        = new char*[fSize];
 
   for (int i = 0; i < fSize; i++) {
      fWriteMonitor->Add(fSockets[i], TMonitor::kWrite);
      fReadMonitor->Add(fSockets[i], TMonitor::kRead);
   }
   fWriteMonitor->DeActivateAll();
   fReadMonitor->DeActivateAll();
 
   SetName(fSockets[0]->GetName());
   SetTitle(fSockets[0]->GetTitle());
   fAddress = fSockets[0]->GetInetAddress();
 
   {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfSockets()->Add(this);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Cleanup the parallel socket.
 
TPSocket::~TPSocket()
{
   Close();
 
   delete fWriteMonitor;
   delete fReadMonitor;
   delete [] fWriteBytesLeft;
   delete [] fReadBytesLeft;
   delete [] fWritePtr;
   delete [] fReadPtr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close a parallel socket. If option is "force", calls shutdown(id,2) to
/// shut down the connection. This will close the connection also
/// for the parent of this process. Also called via the dtor (without
/// option "force", call explicitly Close("force") if this is desired).
 
void TPSocket::Close(Option_t *option)
{
 
   if (!IsValid()) {
      // if closing happens too early (e.g. timeout) the underlying
      // socket may still be open
      TSocket::Close(option);
      return;
   }
 
   if (fSize <= 1) {
      TSocket::Close(option);
   } else {
      for (int i = 0; i < fSize; i++) {
         fSockets[i]->Close(option);
         delete fSockets[i];
      }
   }
   delete [] fSockets;
   fSockets = 0;
 
   {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfSockets()->Remove(this);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a parallel socket to the specified host.
 
void TPSocket::Init(Int_t tcpwindowsize, TSocket *sock)
{
   fSockets        = 0;
   fWriteMonitor   = 0;
   fReadMonitor    = 0;
   fWriteBytesLeft = 0;
   fReadBytesLeft  = 0;
   fWritePtr       = 0;
   fReadPtr        = 0;
 
   if ((sock && !sock->IsValid()) || !TSocket::IsValid())
      return;
 
   Int_t i = 0;
 
   if (fSize <= 1) {
      // check if single mode
      fSize = 1;
 
      // set socket options (no delay)
      if (sock)
         sock->SetOption(kNoDelay, 1);
      else
         TSocket::SetOption(kNoDelay, 1);
 
      // if yes, communicate this to server
      // (size = 0 for backward compatibility)
      if (sock) {
         if (sock->Send((Int_t)0, (Int_t)0) < 0)
            Warning("Init", "%p: problems sending (0,0)", sock);
      } else {
         if (TSocket::Send((Int_t)0, (Int_t)0) < 0)
            Warning("Init", "problems sending (0,0)");
      }
 
      // needs to fill additional private members
      fSockets = new TSocket*[1];
      fSockets[0]= (TSocket *)this;
 
   } else {
 
      // create server that will be used to accept the parallel sockets from
      // the remote host, use port=0 to scan for a free port
      TServerSocket ss(0, kFALSE, fSize, tcpwindowsize);
 
      // send the local port number of the just created server socket and the
      // number of desired parallel sockets
      if (sock) {
         if (sock->Send(ss.GetLocalPort(), fSize) < 0)
            Warning("Init", "%p: problems sending size", sock);
      } else {
         if (TSocket::Send(ss.GetLocalPort(), fSize) < 0)
            Warning("Init", "problems sending size");
      }
 
      fSockets = new TSocket*[fSize];
 
      // establish fSize parallel socket connections between client and server
      for (i = 0; i < fSize; i++) {
         fSockets[i] = ss.Accept();
         R__LOCKGUARD(gROOTMutex);
         gROOT->GetListOfSockets()->Remove(fSockets[i]);
      }
 
      // set socket options (no blocking and no delay)
      SetOption(kNoDelay, 1);
      SetOption(kNoBlock, 1);
 
      // close original socket
      if (sock)
         sock->Close();
      else
         gSystem->CloseConnection(fSocket, kFALSE);
      fSocket = -1;
   }
 
   fWriteMonitor   = new TMonitor;
   fReadMonitor    = new TMonitor;
   fWriteBytesLeft = new Int_t[fSize];
   fReadBytesLeft  = new Int_t[fSize];
   fWritePtr       = new char*[fSize];
   fReadPtr        = new char*[fSize];
 
   for (i = 0; i < fSize; i++) {
      fWriteMonitor->Add(fSockets[i], TMonitor::kWrite);
      fReadMonitor->Add(fSockets[i], TMonitor::kRead);
   }
   fWriteMonitor->DeActivateAll();
   fReadMonitor->DeActivateAll();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return internet address of local host to which the socket is bound.
/// In case of error TInetAddress::IsValid() returns kFALSE.
 
TInetAddress TPSocket::GetLocalInetAddress()
{
   if (fSize<= 1)
      return TSocket::GetLocalInetAddress();
 
   if (IsValid()) {
      if (fLocalAddress.GetPort() == -1)
         fLocalAddress = gSystem->GetSockName(fSockets[0]->GetDescriptor());
      return fLocalAddress;
   }
   return TInetAddress();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return socket descriptor
 
Int_t TPSocket::GetDescriptor() const
{
   if (fSize <= 1)
      return TSocket::GetDescriptor();
 
   return fSockets ? fSockets[0]->GetDescriptor() : -1;
 
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send a TMessage object. Returns the number of bytes in the TMessage
/// that were sent and -1 in case of error. In case the TMessage::What
/// has been or'ed with kMESS_ACK, the call will only return after having
/// received an acknowledgement, making the sending process synchronous.
/// Returns -4 in case of kNoBlock and errno == EWOULDBLOCK.
 
Int_t TPSocket::Send(const TMessage &mess)
{
   if (!fSockets || fSize <= 1)
      return TSocket::Send(mess);  // only the case when called via Init()
 
   if (!IsValid()) {
      return -1;
   }
 
   if (mess.IsReading()) {
      Error("Send", "cannot send a message used for reading");
      return -1;
   }
 
   // send streamer infos in case schema evolution is enabled in the TMessage
   SendStreamerInfos(mess);
 
   // send the process id's so TRefs work
   SendProcessIDs(mess);
 
   mess.SetLength();   //write length in first word of buffer
 
   if (GetCompressionLevel() > 0 && mess.GetCompressionLevel() == 0)
      const_cast<TMessage&>(mess).SetCompressionSettings(fCompress);
 
   if (mess.GetCompressionLevel() > 0)
      const_cast<TMessage&>(mess).Compress();
 
   char *mbuf = mess.Buffer();
   Int_t mlen = mess.Length();
   if (mess.CompBuffer()) {
      mbuf = mess.CompBuffer();
      mlen = mess.CompLength();
   }
 
   Int_t nsent, ulen = (Int_t) sizeof(UInt_t);
   // send length
   if ((nsent = SendRaw(mbuf, ulen, kDefault)) <= 0)
      return nsent;
 
   // send buffer (this might go in parallel)
   if ((nsent = SendRaw(mbuf+ulen, mlen-ulen, kDefault)) <= 0)
      return nsent;
 
   // if acknowledgement is desired, wait for it
   if (mess.What() & kMESS_ACK) {
      char buf[2];
      if (RecvRaw(buf, sizeof(buf), kDefault) < 0)
         return -1;
      if (strncmp(buf, "ok", 2)) {
         Error("Send", "bad acknowledgement");
         return -1;
      }
   }
 
   return nsent;  //length - length header
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send a raw buffer of specified length. Returns the number of bytes
/// send and -1 in case of error.
 
Int_t TPSocket::SendRaw(const void *buffer, Int_t length, ESendRecvOptions opt)
{
   if (fSize == 1)
      return TSocket::SendRaw(buffer,length,opt);
 
   if (!fSockets) return -1;
 
   // if data buffer size < 4K use only one socket
   Int_t i, nsocks = fSize, len = length;
   if (len < 4096)
      nsocks = 1;
 
   ESendRecvOptions sendopt = kDontBlock;
   if (nsocks == 1)
      sendopt = kDefault;
 
   if (opt != kDefault) {
      nsocks  = 1;
      sendopt = opt;
   }
 
   if (nsocks == 1)
      fSockets[0]->SetOption(kNoBlock, 0);
   else
      fSockets[0]->SetOption(kNoBlock, 1);
 
   // setup pointer appropriately for transferring data equally on the
   // parallel sockets
   for (i = 0; i < nsocks; i++) {
      fWriteBytesLeft[i] = len/nsocks;
      fWritePtr[i] = (char *)buffer + (i*fWriteBytesLeft[i]);
      fWriteMonitor->Activate(fSockets[i]);
   }
   fWriteBytesLeft[nsocks-1] += len%nsocks;
 
   // send the data on the parallel sockets
   while (len > 0) {
      TSocket *s = fWriteMonitor->Select();
      for (int is = 0; is < nsocks; is++) {
         if (s == fSockets[is]) {
            if (fWriteBytesLeft[is] > 0) {
               Int_t nsent;
again:
               ResetBit(TSocket::kBrokenConn);
               if ((nsent = fSockets[is]->SendRaw(fWritePtr[is],
                                                  fWriteBytesLeft[is],
                                                  sendopt)) <= 0) {
                  if (nsent == -4) {
                     // got EAGAIN/EWOULDBLOCK error, keep trying...
                     goto again;
                  }
                  fWriteMonitor->DeActivateAll();
                  if (nsent == -5) {
                     // connection reset by peer or broken ...
                     SetBit(TSocket::kBrokenConn);
                     Close();
                  }
                  return -1;
               }
               if (opt == kDontBlock) {
                  fWriteMonitor->DeActivateAll();
                  return nsent;
               }
               fWriteBytesLeft[is] -= nsent;
               fWritePtr[is] += nsent;
               len -= nsent;
            }
         }
      }
   }
   fWriteMonitor->DeActivateAll();
 
   return length;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Receive a TMessage object. The user must delete the TMessage object.
/// Returns length of message in bytes (can be 0 if other side of connection
/// is closed) or -1 in case of error or -4 in case a non-blocking socket would
/// block (i.e. there is nothing to be read). In those case mess == 0.
 
Int_t TPSocket::Recv(TMessage *&mess)
{
   if (fSize <= 1)
      return TSocket::Recv(mess);
 
   if (!IsValid()) {
      mess = 0;
      return -1;
   }
 
oncemore:
   Int_t  n;
   UInt_t len;
   if ((n = RecvRaw(&len, sizeof(UInt_t), kDefault)) <= 0) {
      mess = 0;
      return n;
   }
   len = net2host(len);  //from network to host byte order
 
   if (len > (std::numeric_limits<decltype(len)>::max() - sizeof(decltype(len)))) {
      Error("Recv", "Buffer length is %u and %u+sizeof(UInt_t) cannot be represented as an UInt_t.", len, len);
      return -1;
   }
 
   char *buf = new char[len+sizeof(UInt_t)];
   if ((n = RecvRaw(buf+sizeof(UInt_t), len, kDefault)) <= 0) {
      delete [] buf;
      mess = 0;
      return n;
   }
 
   mess = new TMessage(buf, len+sizeof(UInt_t));
 
   // receive any streamer infos
   if (RecvStreamerInfos(mess))
      goto oncemore;
 
   // receive any process ids
   if (RecvProcessIDs(mess))
      goto oncemore;
 
   if (mess->What() & kMESS_ACK) {
      char ok[2] = { 'o', 'k' };
      if (SendRaw(ok, sizeof(ok), kDefault) < 0) {
         delete mess;
         mess = 0;
         return -1;
      }
      mess->SetWhat(mess->What() & ~kMESS_ACK);
   }
 
   return n;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send a raw buffer of specified length. Returns the number of bytes
/// sent or -1 in case of error.
 
Int_t TPSocket::RecvRaw(void *buffer, Int_t length, ESendRecvOptions opt)
{
   if (fSize <= 1)
      return TSocket::RecvRaw(buffer,length,opt);
 
   if (!fSockets) return -1;
 
   // if data buffer size < 4K use only one socket
   Int_t i, nsocks = fSize, len = length;
   if (len < 4096)
      nsocks = 1;
 
   ESendRecvOptions recvopt = kDontBlock;
   if (nsocks == 1)
      recvopt = kDefault;
 
   if (opt != kDefault) {
      nsocks  = 1;
      recvopt = opt;
   }
 
   if (nsocks == 1)
      fSockets[0]->SetOption(kNoBlock, 0);
   else
      fSockets[0]->SetOption(kNoBlock, 1);
 
   // setup pointer appropriately for transferring data equally on the
   // parallel sockets
   for (i = 0; i < nsocks; i++) {
      fReadBytesLeft[i] = len/nsocks;
      fReadPtr[i] = (char *)buffer + (i*fReadBytesLeft[i]);
      fReadMonitor->Activate(fSockets[i]);
   }
   fReadBytesLeft[nsocks-1] += len%nsocks;
 
   // start receiving data on all sockets. Receive data as and when
   // they are available on a socket by by using select.
   // Exit the loop as soon as all data has been received.
   while (len > 0) {
      TSocket *s = fReadMonitor->Select();
      for (int is = 0; is < nsocks; is++) {
         if (s == fSockets[is]) {
            if (fReadBytesLeft[is] > 0) {
               Int_t nrecv;
               ResetBit(TSocket::kBrokenConn);
               if ((nrecv = fSockets[is]->RecvRaw(fReadPtr[is],
                                                  fReadBytesLeft[is],
                                                  recvopt)) <= 0) {
                  fReadMonitor->DeActivateAll();
                  if (nrecv == -5) {
                     // connection reset by peer or broken ...
                     SetBit(TSocket::kBrokenConn);
                     Close();
                  }
                  return -1;
               }
               if (opt == kDontBlock) {
                  fReadMonitor->DeActivateAll();
                  return nrecv;
               }
               fReadBytesLeft[is] -= nrecv;
               fReadPtr[is] += nrecv;
               len -= nrecv;
            }
         }
      }
   }
   fReadMonitor->DeActivateAll();
 
   return length;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set socket options.
 
Int_t TPSocket::SetOption(ESockOptions opt, Int_t val)
{
   if (fSize <= 1)
      return TSocket::SetOption(opt,val);
 
   Int_t ret = 0;
   for (int i = 0; i < fSize; i++)
      ret = fSockets[i]->SetOption(opt, val);
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get socket options. Returns -1 in case of error.
 
Int_t TPSocket::GetOption(ESockOptions opt, Int_t &val)
{
   if (fSize <= 1)
      return TSocket::GetOption(opt,val);
 
   Int_t ret = 0;
   for (int i = 0; i < fSize; i++)
      ret = fSockets[i]->GetOption(opt, val);
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns error code. Meaning depends on context where it is called.
/// If no error condition returns 0 else a value < 0.
 
Int_t TPSocket::GetErrorCode() const
{
   if (fSize <= 1)
      return TSocket::GetErrorCode();
 
   return fSockets[0] ? fSockets[0]->GetErrorCode() : 0;
}