/// <summary>
/// Adds contact points as hosts and resolving host names if necessary.
/// </summary>
/// <exception cref="NoHostAvailableException">When no host can be resolved and no other contact point is an address</exception>
private async Task AddHosts(IEnumerable <object> contactPoints)
{
var resolvedContactPoints = new Dictionary <string, ICollection <IPEndPoint> >();
var hostNames = new List <string>();
foreach (var contactPoint in contactPoints)
{
if (contactPoint is IPEndPoint endpoint)
{
resolvedContactPoints.CreateOrAdd(endpoint.ToString(), endpoint);
_metadata.AddHost(endpoint);
continue;
}
if (!(contactPoint is string contactPointText))
{
throw new InvalidOperationException("Contact points should be either string or IPEndPoint instances");
}
if (IPAddress.TryParse(contactPointText, out var ipAddress))
{
var ipEndpoint = new IPEndPoint(ipAddress, Configuration.ProtocolOptions.Port);
resolvedContactPoints.CreateOrAdd(contactPointText, ipEndpoint);
_metadata.AddHost(ipEndpoint);
continue;
}
hostNames.Add(contactPointText);
IPHostEntry hostEntry = null;
try
{
hostEntry = await Dns.GetHostEntryAsync(contactPointText).ConfigureAwait(false);
}
catch (Exception)
{
_logger.Warning($"Host '{contactPointText}' could not be resolved");
}
if (hostEntry != null && hostEntry.AddressList.Length > 0)
{
foreach (var resolvedAddress in hostEntry.AddressList)
{
var ipEndpoint = new IPEndPoint(resolvedAddress, Configuration.ProtocolOptions.Port);
_metadata.AddHost(ipEndpoint);
resolvedContactPoints.CreateOrAdd(contactPointText, ipEndpoint);
}
}
else
{
resolvedContactPoints.CreateIfDoesNotExist(contactPointText);
}
}
_metadata.SetResolvedContactPoints(resolvedContactPoints.ToDictionary(kvp => kvp.Key, kvp => kvp.Value.AsEnumerable()));
if (_metadata.Hosts.Count == 0)
{
throw new NoHostAvailableException($"No host name could be resolved, attempted: {string.Join(", ", hostNames)}");
}
}
