Fix Socket array length to avoid possible out of bounds errors (#1031)

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SNITcpHandle.cs

@@ -327,7 +327,13 @@ private static Socket Connect(string serverName, int port, TimeSpan timeout, boo
  string IPv4String = null;
  string IPv6String = null;
 
- Socket[] sockets = new Socket[2];
+ // Returning null socket is handled by the caller function.
+ if(ipAddresses == null || ipAddresses.Length == 0)
+ {
+ return null;
+ }
+
+ Socket[] sockets = new Socket[ipAddresses.Length];
  AddressFamily[] preferedIPFamilies = new AddressFamily[] { AddressFamily.InterNetwork, AddressFamily.InterNetworkV6 };
 
  CancellationTokenSource cts = null;
@@ -360,6 +366,8 @@ void Cancel()
  Socket availableSocket = null;
  try
  {
+ int n = 0; // Socket index
+
  // 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].
@@ -371,18 +379,18 @@ void Cancel()
  {
  if (ipAddress != null && ipAddress.AddressFamily == preferedIPFamilies[i])
  {
- sockets[i] = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
+ sockets[n] = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
 
  // enable keep-alive on socket
- SetKeepAliveValues(ref sockets[i]);
+ SetKeepAliveValues(ref sockets[n]);
 
  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()
+ sockets[n].Connect(ipAddress, port);
+ if (sockets[n] != null) // sockets[i] can be null if cancel callback is executed during connect()
  {
- if (sockets[i].Connected)
+ if (sockets[n].Connected)
  {
- availableSocket = sockets[i];
+ availableSocket = sockets[n];
 
  if (ipAddress.AddressFamily == AddressFamily.InterNetwork)
  {
@@ -397,10 +405,11 @@ void Cancel()
  }
  else
  {
- sockets[i].Dispose();
- sockets[i] = null;
+ sockets[n].Dispose();
+ sockets[n] = null;
  }
  }
+ n++;
  }
  }
  catch (Exception e)