/// <summary>
/// Discovers agents of the specified version in a specific time interval.
/// </summary>
/// <param name="version">The version.</param>
/// <param name="broadcastAddress">The broadcast address.</param>
/// <param name="community">The community.</param>
/// <param name="interval">The discovering time interval, in milliseconds.</param>
/// <remarks><paramref name="broadcastAddress"/> must be an IPv4 address. IPv6 is not yet supported here.</remarks>
public void Discover(VersionCode version, IPEndPoint broadcastAddress, OctetString community, int interval)
{
if (broadcastAddress == null)
{
throw new ArgumentNullException(nameof(broadcastAddress));
}
if (version != VersionCode.V3 && community == null)
{
throw new ArgumentNullException(nameof(community));
}
AddressFamily addressFamily = broadcastAddress.AddressFamily;
if (addressFamily == AddressFamily.InterNetworkV6)
{
throw new ArgumentException("IP v6 is not yet supported.", nameof(broadcastAddress));
}
byte[] bytes;
_requestId = Messenger.NextRequestId;
if (version == VersionCode.V3)
{
// throw new NotSupportedException("SNMP v3 is not supported");
Discovery discovery = new Discovery(Messenger.NextMessageId, _requestId, Messenger.MaxMessageSize);
bytes = discovery.ToBytes();
}
else
{
GetRequestMessage message = new GetRequestMessage(_requestId, version, community, _defaultVariables);
bytes = message.ToBytes();
}
using (UdpClient udp = new UdpClient(addressFamily))
{
#if (!CF)
udp.EnableBroadcast = true;
#endif
#if NET471
udp.Send(bytes, bytes.Length, broadcastAddress);
#else
AsyncHelper.RunSync(() => udp.SendAsync(bytes, bytes.Length, broadcastAddress));
#endif
int activeBefore = Interlocked.CompareExchange(ref _active, Active, Inactive);
if (activeBefore == Active)
{
// If already started, we've nothing to do.
return;
}
_bufferSize = udp.Client.ReceiveBufferSize = Messenger.MaxMessageSize;
#if ASYNC
Task.Factory.StartNew(() => AsyncBeginReceive(udp.Client));
#else
Task.Factory.StartNew(() => AsyncReceive(udp.Client));
#endif
Thread.Sleep(interval);
Interlocked.CompareExchange(ref _active, Inactive, Active);
#if NET471
udp.Close();
#endif
}
}
/// <summary>
/// Discovers agents of the specified version in a specific time interval.
/// </summary>
/// <param name="version">The version.</param>
/// <param name="broadcastAddress">The broadcast address.</param>
/// <param name="community">The community.</param>
/// <param name="interval">The discovering time interval, in milliseconds.</param>
/// <remarks><paramref name="broadcastAddress"/> must be an IPv4 address. IPv6 is not yet supported here.</remarks>
public async Task DiscoverAsync(VersionCode version, IPEndPoint broadcastAddress, OctetString community, int interval)
{
if (broadcastAddress == null)
{
throw new ArgumentNullException(nameof(broadcastAddress));
}
if (version != VersionCode.V3 && community == null)
{
throw new ArgumentNullException(nameof(community));
}
AddressFamily addressFamily = broadcastAddress.AddressFamily;
if (addressFamily == AddressFamily.InterNetworkV6)
{
throw new ArgumentException("IP v6 is not yet supported.", nameof(broadcastAddress));
}
byte[] bytes;
_requestId = Messenger.NextRequestId;
if (version == VersionCode.V3)
{
// throw new NotSupportedException("SNMP v3 is not supported");
Discovery discovery = new Discovery(Messenger.NextMessageId, _requestId, Messenger.MaxMessageSize);
bytes = discovery.ToBytes();
}
else
{
GetRequestMessage message = new GetRequestMessage(_requestId, version, community, _defaultVariables);
bytes = message.ToBytes();
}
using (Socket udp = new Socket(addressFamily, SocketType.Dgram, ProtocolType.Udp))
{
udp.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, true);
SocketAsyncEventArgs info = SocketExtension.EventArgsFactory.Create();
info.RemoteEndPoint = broadcastAddress;
info.SetBuffer(bytes, 0, bytes.Length);
using (SocketAwaitable awaitable1 = new SocketAwaitable(info))
{
await udp.SendToAsync(awaitable1);
}
int activeBefore = Interlocked.CompareExchange(ref _active, Active, Inactive);
if (activeBefore == Active)
{
// If already started, we've nothing to do.
return;
}
_bufferSize = udp.ReceiveBufferSize;
await Task.WhenAny(
ReceiveAsync(udp),
Task.Delay(interval));
Interlocked.CompareExchange(ref _active, Inactive, Active);
try
{
udp.Shutdown(SocketShutdown.Both);
}
catch (SocketException ex)
{
// This exception is thrown in .NET Core <=2.1.4 on non-Windows systems.
// However, the shutdown call is necessary to release the socket binding.
if (!SnmpMessageExtension.IsRunningOnWindows && ex.SocketErrorCode == SocketError.NotConnected)
{
}
}
}
}