From baeb2a666e5321765ec8c7d155f42d630078cdca Mon Sep 17 00:00:00 2001
From: imaginos <imaginos@726aef4b-f618-498e-8847-2d620e286838>
Date: Fri, 15 Jan 2010 19:45:58 +0000
Subject: [PATCH] added workaround for a canonical name that points to ipv6 and
 ipv4 ip's, the ipv6 ip is tried first, followed up by a final try on ipv4 in
 the event the ipv6 connect results in a network unreachable. I wonder what
 this will break ...

git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1712 726aef4b-f618-498e-8847-2d620e286838
---
 Csocket.cpp | 20 ++++++++++++++++++++
 Csocket.h   |  1 +
 2 files changed, 21 insertions(+)

diff --git a/Csocket.cpp b/Csocket.cpp
index ebc7196c..43ee295f 100644
--- a/Csocket.cpp
+++ b/Csocket.cpp
@@ -2154,6 +2154,26 @@ int Csock::GetAddrInfo( const CS_STRING & sHostname, CSSockAddr & csSockAddr )
 		{ // this means its finished
 			FreeAres();
 #ifdef HAVE_IPV6
+			if( m_iARESStatus == ARES_SUCCESS && csSockAddr.GetAFRequire() == CSSockAddr::RAF_ANY && GetIPv6() )
+			{
+				// this means that ares_host returned an ipv6 host, so try a connect right away
+				if( CreateSocksFD() && Connect( GetBindHost(), true ) )
+				{
+					SetSkipConnect( true );
+				}
+				else if( GetSockError() == ENETUNREACH )
+				{
+					// the Connect() failed, so throw a retry back in with ipv4, and let it process normally
+					CS_DEBUG( "Failed ipv6 connection with PF_UNSPEC, falling back to ipv4" );
+					m_iARESStatus = -1;
+					if( m_iReadSock != m_iWriteSock )
+						CS_CLOSE( m_iWriteSock );
+					CS_CLOSE( m_iReadSock );
+					m_iReadSock = m_iWriteSock = CS_INVALID_SOCK;
+					SetAFRequire( CSSockAddr::RAF_INET );
+					return( GetAddrInfo( sHostname, csSockAddr ) );
+				}
+			}
 #if ARES_VERSION < CREATE_ARES_VER( 1, 5, 3 )
 			if( m_iARESStatus != ARES_SUCCESS && csSockAddr.GetAFRequire() == CSSockAddr::RAF_ANY )
 			{ // this is a workaround for ares < 1.5.3 where the builtin retry on failed AF_INET6 isn't there yet
diff --git a/Csocket.h b/Csocket.h
index 6847cba2..71273452 100644
--- a/Csocket.h
+++ b/Csocket.h
@@ -58,6 +58,7 @@
 #define ETIMEDOUT WSAETIMEDOUT
 #define EADDRNOTAVAIL WSAEADDRNOTAVAIL
 #define ECONNABORTED WSAECONNABORTED
+#define ENETUNREACH WSAENETUNREACH
 
 #endif /* _WIN32 */