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Fix | Change IP connection logic in SNITCPHandle #1016

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Apr 13, 2021
Merged

Fix | Change IP connection logic in SNITCPHandle #1016

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92 changes: 50 additions & 42 deletions src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SNITcpHandle.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -327,28 +327,8 @@ private static Socket Connect(string serverName, int port, TimeSpan timeout, boo
string IPv4String = null;
string IPv6String = null;

IPAddress serverIPv4 = null;
IPAddress serverIPv6 = null;
foreach (IPAddress ipAddress in ipAddresses)
{
if (ipAddress.AddressFamily == AddressFamily.InterNetwork)
{
serverIPv4 = ipAddress;
IPv4String = ipAddress.ToString();
}
else if (ipAddress.AddressFamily == AddressFamily.InterNetworkV6)
{
serverIPv6 = ipAddress;
IPv6String = ipAddress.ToString();
}
}
ipAddresses = new IPAddress[] { serverIPv4, serverIPv6 };
Socket[] sockets = new Socket[2];

if (IPv4String != null || IPv6String != null)
{
pendingDNSInfo = new SQLDNSInfo(cachedFQDN, IPv4String, IPv6String, port.ToString());
}
AddressFamily[] preferedIPFamilies = new AddressFamily[] { AddressFamily.InterNetwork, AddressFamily.InterNetworkV6 };

CancellationTokenSource cts = null;

Expand Down Expand Up @@ -380,45 +360,73 @@ void Cancel()
Socket availableSocket = null;
try
{
for (int i = 0; i < sockets.Length; ++i)
// We go through the IP list twice.
// In the first traversal, we only try to connect with the preferedIPFamilies[0].
// In the second traversal, we only try to connect with the preferedIPFamilies[1].
for (int i = 0; i < preferedIPFamilies.Length; ++i)
{
try
foreach (IPAddress ipAddress in ipAddresses)
{
if (ipAddresses[i] != null)
try
{
sockets[i] = new Socket(ipAddresses[i].AddressFamily, SocketType.Stream, ProtocolType.Tcp);
if (ipAddress != null && ipAddress.AddressFamily == preferedIPFamilies[i])
{
sockets[i] = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

// enable keep-alive on socket
SetKeepAliveValues(ref sockets[i]);
// enable keep-alive on socket
SetKeepAliveValues(ref sockets[i]);

SqlClientEventSource.Log.TrySNITraceEvent(s_className, EventType.INFO, "Connecting to IP address {0} and port {1}", args0: ipAddresses[i], args1: port);
sockets[i].Connect(ipAddresses[i], port);
if (sockets[i] != null) // sockets[i] can be null if cancel callback is executed during connect()
{
if (sockets[i].Connected)
SqlClientEventSource.Log.TrySNITraceEvent(s_className, EventType.INFO, "Connecting to IP address {0} and port {1}", args0: ipAddress, args1: port);
sockets[i].Connect(ipAddress, port);
if (sockets[i] != null) // sockets[i] can be null if cancel callback is executed during connect()
{
availableSocket = sockets[i];
break;
}
else
{
sockets[i].Dispose();
sockets[i] = null;
if (sockets[i].Connected)
{
availableSocket = sockets[i];

if (ipAddress.AddressFamily == AddressFamily.InterNetwork)
{
IPv4String = ipAddress.ToString();
}
else if (ipAddress.AddressFamily == AddressFamily.InterNetworkV6)
{
IPv6String = ipAddress.ToString();
}

break;
}
else
{
sockets[i].Dispose();
sockets[i] = null;
}
}
}
}
catch (Exception e)
{
SqlClientEventSource.Log.TrySNITraceEvent(s_className, EventType.ERR, "THIS EXCEPTION IS BEING SWALLOWED: {0}", args0: e?.Message);
}
}
catch (Exception e)

// If we have already got an valid Socket, we won't do the second traversal.
if (availableSocket != null)
{
SqlClientEventSource.Log.TrySNITraceEvent(s_className, EventType.ERR, "THIS EXCEPTION IS BEING SWALLOWED: {0}", args0: e?.Message);
}
break;
}
}
}
finally
{
cts?.Dispose();
}

// we only record the ip we can connect with successfully.
if (IPv4String != null || IPv6String != null)
{
pendingDNSInfo = new SQLDNSInfo(cachedFQDN, IPv4String, IPv6String, port.ToString());
}

return availableSocket;
}

Expand Down