From a9e2bfab0477d9f73026a14b4b53ab8fb5b8eb72 Mon Sep 17 00:00:00 2001
From: Michal Simon <michal.simon@cern.ch>
Date: Wed, 17 Jan 2018 17:13:14 +0100
Subject: [PATCH] [XrdCl] Try all IP addresses in case posix connect fails.

---
 docs/man/xrdcp.1             |  5 +++++
 src/XrdCl/XrdClConstants.hh  |  1 +
 src/XrdCl/XrdClDefaultEnv.cc |  1 +
 src/XrdCl/XrdClStream.cc     | 37 ++++++++++++++++++++++++++----------
 4 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/docs/man/xrdcp.1 b/docs/man/xrdcp.1
index e65a0209dbe..92d041e11cc 100644
--- a/docs/man/xrdcp.1
+++ b/docs/man/xrdcp.1
@@ -456,6 +456,11 @@ XRD_NODELAY
 Disables the Nagle algorithm if set to 1 (default), enables it if set to 0.
 .RE
 
+XRD_PREFERIPV4
+.RS 5
+If set the client tries first IPv4 address (turned off by default).
+.RE
+
 .SH NOTES
 Documentation for all components associated with \fBxrdcp\fR can be found at
 http://xrootd.org/docs.html
diff --git a/src/XrdCl/XrdClConstants.hh b/src/XrdCl/XrdClConstants.hh
index 3cb6c9daaea..9fa5b8cef78 100644
--- a/src/XrdCl/XrdClConstants.hh
+++ b/src/XrdCl/XrdClConstants.hh
@@ -69,6 +69,7 @@ namespace XrdCl
   const int DefaultXCpBlockSize         = 134217728; // DefaultCPChunkSize * DefaultCPParallelChunks * 2
   const int DefaultNoDelay              = 1;
   const int DefaultAioSignal            = 1;
+  const int DefaultPreferIPv4           = 0;
 
   const char * const DefaultPollerPreference   = "built-in";
   const char * const DefaultNetworkStack       = "IPAuto";
diff --git a/src/XrdCl/XrdClDefaultEnv.cc b/src/XrdCl/XrdClDefaultEnv.cc
index 0e91c1ebc79..298c37fee1b 100644
--- a/src/XrdCl/XrdClDefaultEnv.cc
+++ b/src/XrdCl/XrdClDefaultEnv.cc
@@ -289,6 +289,7 @@ namespace XrdCl
     REGISTER_VAR_INT( varsInt, "XCpBlockSize",         DefaultXCpBlockSize         );
     REGISTER_VAR_INT( varsInt, "NoDelay",              DefaultNoDelay              );
     REGISTER_VAR_INT( varsInt, "AioSignal",            DefaultAioSignal            );
+    REGISTER_VAR_INT( varsInt, "PreferIPv4",           DefaultPreferIPv4           );
 
     REGISTER_VAR_STR( varsStr, "PollerPreference",     DefaultPollerPreference     );
     REGISTER_VAR_STR( varsStr, "ClientMonitor",        DefaultClientMonitor        );
diff --git a/src/XrdCl/XrdClStream.cc b/src/XrdCl/XrdClStream.cc
index 979f9aa006c..0f67643832f 100644
--- a/src/XrdCl/XrdClStream.cc
+++ b/src/XrdCl/XrdClStream.cc
@@ -240,7 +240,6 @@ namespace XrdCl
       return pLastFatalError;
 
     gettimeofday( &pConnectionStarted, 0 );
-    pConnectionInitTime = now;
     ++pConnectionCount;
 
     //--------------------------------------------------------------------------
@@ -265,12 +264,23 @@ namespace XrdCl
     // It's more efficient to remove addresses from the back of a vector
     // so we reverse the it.
     //--------------------------------------------------------------------------
-    std::reverse( pAddresses.begin(), pAddresses.end() );
-    pSubStreams[0]->socket->SetAddress( pAddresses.back() );
-    pAddresses.pop_back();
-    st = pSubStreams[0]->socket->Connect( pConnectionWindow );
-    if( st.IsOK() )
-      pSubStreams[0]->status = Socket::Connecting;
+    int preferIPv4 = DefaultPreferIPv4;
+    DefaultEnv::GetEnv()->GetInt( "PreferIPv4", preferIPv4 );
+    if( !preferIPv4 )
+      std::reverse( pAddresses.begin(), pAddresses.end() );
+
+    while( !pAddresses.empty() )
+    {
+      pSubStreams[0]->socket->SetAddress( pAddresses.back() );
+      pAddresses.pop_back();
+      pConnectionInitTime = ::time( 0 );
+      st = pSubStreams[0]->socket->Connect( pConnectionWindow );
+      if( st.IsOK() )
+      {
+        pSubStreams[0]->status = Socket::Connecting;
+        break;
+      }
+    }
     return st;
   }
 
@@ -676,12 +686,19 @@ namespace XrdCl
     //------------------------------------------------------------------------
     if( !pAddresses.empty() )
     {
-      pSubStreams[0]->socket->SetAddress( pAddresses.back() );
-      pAddresses.pop_back();
+      Status st;
+      do
+      {
+        pSubStreams[0]->socket->SetAddress( pAddresses.back() );
+        pAddresses.pop_back();
+        pConnectionInitTime = ::time( 0 );
+        st = pSubStreams[0]->socket->Connect( pConnectionWindow );
+      }
+      while( !pAddresses.empty() && !st.IsOK() );
 
-      Status st = pSubStreams[0]->socket->Connect( pConnectionWindow-elapsed );
       if( !st.IsOK() )
         OnFatalError( subStream, st, scopedLock );
+
       return;
     }
     //------------------------------------------------------------------------