/// <summary>
/// Resolves the contact point according to its type. If it is not an IP address, then considers it a hostname and
/// attempts to resolve it with DNS.
/// </summary>
private async Task <IEnumerable <IConnectionEndPoint> > ResolveContactPointAsync(bool refreshCache)
{
if (!refreshCache && !_keepContactPointsUnresolved && _cachedEndpoints.Any())
{
return(_cachedEndpoints);
}
IPHostEntry hostEntry = null;
try
{
hostEntry = await _dns.GetHostEntryAsync(_hostname).ConfigureAwait(false);
}
catch (Exception)
{
Cluster.Logger.Warning("Contact point '{0}' could not be resolved.", _hostname);
}
var connectionEndPoints = new List <IConnectionEndPoint>();
if (hostEntry != null && hostEntry.AddressList.Length > 0)
{
Cluster.Logger.Info("Contact point '{0}' resolved to multiple addresses. Will attempt to use them all if necessary: '{1}'",
_hostname,
string.Join(",", hostEntry.AddressList.Select(resolvedAddress => resolvedAddress.ToString())));
connectionEndPoints.AddRange(
hostEntry.AddressList.Select(resolvedAddress =>
new ConnectionEndPoint(new IPEndPoint(resolvedAddress, _protocolOptions.Port), _serverNameResolver, this)));
}
_cachedEndpoints = connectionEndPoints;
return(_cachedEndpoints);
}
private async Task RefreshProxyResolutionAsync()
{
if (_endPoint != null)
{
return;
}
IPHostEntry hostEntry = null;
Exception exception = null;
try
{
hostEntry = await _dns.GetHostEntryAsync(_sniOptions.Name).ConfigureAwait(false);
}
catch (Exception ex)
{
exception = ex;
}
if (hostEntry != null && hostEntry.AddressList.Length > 0)
{
_resolvedProxyEndPoints =
hostEntry.AddressList
.Where(address => address.AddressFamily != AddressFamily.InterNetworkV6 || address.IsIPv4MappedToIPv6)
.Select(address => address.IsIPv4MappedToIPv6
? new IPEndPoint(address.MapToIPv4(), _sniOptions.Port)
: new IPEndPoint(address, _sniOptions.Port))
.OrderBy(e => _random.Next()) // shuffle
.ToList();
_index = 0;
return;
}
if (_resolvedProxyEndPoints != null)
{
var logMsg =
exception == null
? $"DNS resolution of endpoint \"{_sniOptions.Name}\" did not return any host entries. " +
"Falling back to the result of the previous DNS resolution."
: $"Could not resolve endpoint \"{_sniOptions.Name}\". " +
"Falling back to the result of the previous DNS resolution.";
SniEndPointResolver.Logger.Error(logMsg, exception);
_index = 0;
return;
}
var error = exception == null
? new DriverInternalError($"DNS resolution of endpoint \"{_sniOptions.Name}\" did not return any host entries.")
: new DriverInternalError($"Could not resolve endpoint \"{_sniOptions.Name}\"", exception);
throw error;
}
/// <summary>
/// Resolves the contact point according to its type. If it is not an IP address, then considers it a hostname and
/// attempts to resolve it with DNS.
/// </summary>
private async Task <IEnumerable <IConnectionEndPoint> > ResolveContactPointAsync(string contactPointText)
{
if (_resolvedContactPoints.TryGetValue(contactPointText, out var ipEndPoints))
{
return(ipEndPoints);
}
if (IPAddress.TryParse(contactPointText, out var ipAddress))
{
var ipEndpoint = new IPEndPoint(ipAddress, _protocolOptions.Port);
var connectionEndPoint = new ConnectionEndPoint(ipEndpoint, GetServerName);
var listOfConnectionEndPoints = new List <IConnectionEndPoint> {
connectionEndPoint
};
_resolvedContactPoints.AddOrUpdate(
contactPointText,
key => listOfConnectionEndPoints,
(key, list) => listOfConnectionEndPoints);
return(listOfConnectionEndPoints);
}
IPHostEntry hostEntry = null;
try
{
hostEntry = await _dns.GetHostEntryAsync(contactPointText).ConfigureAwait(false);
}
catch (Exception)
{
Cluster.Logger.Warning($"Host '{contactPointText}' could not be resolved");
}
var connectionEndPoints = new List <IConnectionEndPoint>();
if (hostEntry != null && hostEntry.AddressList.Length > 0)
{
connectionEndPoints.AddRange(
hostEntry.AddressList.Select(resolvedAddress =>
new ConnectionEndPoint(new IPEndPoint(resolvedAddress, _protocolOptions.Port), GetServerName)));
}
_resolvedContactPoints.AddOrUpdate(
contactPointText,
key => connectionEndPoints,
(key, list) => connectionEndPoints);
return(connectionEndPoints);
}