private bool TryGetPingReply(
SocketConfig socketConfig, byte[] receiveBuffer, int bytesReceived, Stopwatch sw, ref int ipHeaderLength,
[NotNullWhen(true)] out PingReply?reply)
{
byte type, code;
reply = null;
if (socketConfig.IsIpv4)
{
// Determine actual size of IP header
byte ihl = (byte)(receiveBuffer[0] & 0x0f); // Internet Header Length
ipHeaderLength = 4 * ihl;
if (bytesReceived - ipHeaderLength < IcmpHeaderLengthInBytes)
{
return(false); // Not enough bytes to reconstruct actual IP header + ICMP header.
}
}
int icmpHeaderOffset = ipHeaderLength;
// Skip IP header.
IcmpHeader receivedHeader = MemoryMarshal.Read <IcmpHeader>(receiveBuffer.AsSpan(icmpHeaderOffset));
type = receivedHeader.Type;
code = receivedHeader.Code;
if (socketConfig.Identifier != receivedHeader.Identifier ||
type == (byte)IcmpV4MessageType.EchoRequest ||
type == (byte)IcmpV6MessageType.EchoRequest) // Echo Request, ignore
{
return(false);
}
sw.Stop();
long roundTripTime = sw.ElapsedMilliseconds;
int dataOffset = ipHeaderLength + IcmpHeaderLengthInBytes;
// We want to return a buffer with the actual data we sent out, not including the header data.
byte[] dataBuffer = new byte[bytesReceived - dataOffset];
Buffer.BlockCopy(receiveBuffer, dataOffset, dataBuffer, 0, dataBuffer.Length);
IPStatus status = socketConfig.IsIpv4
? IcmpV4MessageConstants.MapV4TypeToIPStatus(type, code)
: IcmpV6MessageConstants.MapV6TypeToIPStatus(type, code);
IPAddress address = ((IPEndPoint)socketConfig.EndPoint).Address;
reply = new PingReply(address, socketConfig.Options, status, roundTripTime, dataBuffer);
return(true);
}
private async Task <PingReply> SendIcmpEchoRequestOverRawSocket(IPAddress address, byte[] buffer, int timeout, PingOptions options)
{
EndPoint endPoint = new IPEndPoint(address, 0);
bool isIpv4 = address.AddressFamily == AddressFamily.InterNetwork;
ProtocolType protocolType = isIpv4 ? ProtocolType.Icmp : ProtocolType.IcmpV6;
// Use the current thread's ID as the identifier.
ushort identifier = (ushort)Environment.CurrentManagedThreadId;
IcmpHeader header = new IcmpHeader()
{
Type = isIpv4 ? (byte)IcmpV4MessageType.EchoRequest : (byte)IcmpV6MessageType.EchoRequest,
Code = 0,
HeaderChecksum = 0,
Identifier = identifier,
SequenceNumber = 0,
};
byte[] sendBuffer = CreateSendMessageBuffer(header, buffer);
using (Socket socket = new Socket(address.AddressFamily, SocketType.Raw, protocolType))
{
socket.ReceiveTimeout = timeout;
socket.SendTimeout = timeout;
// Setting Socket.DontFragment and .Ttl is not supported on Unix, so ignore the PingOptions parameter.
int ipHeaderLength = isIpv4 ? IpHeaderLengthInBytes : 0;
await socket.SendToAsync(new ArraySegment <byte>(sendBuffer), SocketFlags.None, endPoint).ConfigureAwait(false);
byte[] receiveBuffer = new byte[ipHeaderLength + IcmpHeaderLengthInBytes + buffer.Length];
long elapsed;
Stopwatch sw = Stopwatch.StartNew();
// Read from the socket in a loop. We may receive messages that are not echo replies, or that are not in response
// to the echo request we just sent. We need to filter such messages out, and continue reading until our timeout.
// For example, when pinging the local host, we need to filter out our own echo requests that the socket reads.
while ((elapsed = sw.ElapsedMilliseconds) < timeout)
{
Task <SocketReceiveFromResult> receiveTask = socket.ReceiveFromAsync(
new ArraySegment <byte>(receiveBuffer),
SocketFlags.None,
endPoint);
var cts = new CancellationTokenSource();
Task finished = await Task.WhenAny(receiveTask, Task.Delay(timeout - (int)elapsed, cts.Token)).ConfigureAwait(false);
cts.Cancel();
if (finished != receiveTask)
{
sw.Stop();
return(CreateTimedOutPingReply());
}
SocketReceiveFromResult receiveResult = receiveTask.GetAwaiter().GetResult();
int bytesReceived = receiveResult.ReceivedBytes;
if (bytesReceived - ipHeaderLength < IcmpHeaderLengthInBytes)
{
continue; // Not enough bytes to reconstruct IP header + ICMP header.
}
byte type, code;
unsafe
{
fixed(byte *bytesPtr = receiveBuffer)
{
int icmpHeaderOffset = ipHeaderLength;
IcmpHeader receivedHeader = *((IcmpHeader *)(bytesPtr + icmpHeaderOffset)); // Skip IP header.
type = receivedHeader.Type;
code = receivedHeader.Code;
if (identifier != receivedHeader.Identifier ||
type == (byte)IcmpV4MessageType.EchoRequest ||
type == (byte)IcmpV6MessageType.EchoRequest) // Echo Request, ignore
{
continue;
}
}
}
sw.Stop();
long roundTripTime = sw.ElapsedMilliseconds;
int dataOffset = ipHeaderLength + IcmpHeaderLengthInBytes;
// We want to return a buffer with the actual data we sent out, not including the header data.
byte[] dataBuffer = new byte[bytesReceived - dataOffset];
Buffer.BlockCopy(receiveBuffer, dataOffset, dataBuffer, 0, dataBuffer.Length);
IPStatus status = isIpv4
? IcmpV4MessageConstants.MapV4TypeToIPStatus(type, code)
: IcmpV6MessageConstants.MapV6TypeToIPStatus(type, code);
return(new PingReply(address, options, status, roundTripTime, dataBuffer));
}
// We have exceeded our timeout duration, and no reply has been received.
sw.Stop();
return(CreateTimedOutPingReply());
}
}
private bool TryGetPingReply(
SocketConfig socketConfig, byte[] receiveBuffer, int bytesReceived, Stopwatch sw, ref int ipHeaderLength,
[NotNullWhen(true)] out PingReply?reply)
{
byte type, code;
reply = null;
if (socketConfig.IsIpv4)
{
// Determine actual size of IP header
byte ihl = (byte)(receiveBuffer[0] & 0x0f); // Internet Header Length
ipHeaderLength = 4 * ihl;
if (bytesReceived - ipHeaderLength < IcmpHeaderLengthInBytes)
{
return(false); // Not enough bytes to reconstruct actual IP header + ICMP header.
}
}
int icmpHeaderOffset = ipHeaderLength;
int dataOffset = ipHeaderLength + IcmpHeaderLengthInBytes;
// Skip IP header.
IcmpHeader receivedHeader = MemoryMarshal.Read <IcmpHeader>(receiveBuffer.AsSpan(icmpHeaderOffset));
ushort identifier = 0;
type = receivedHeader.Type;
code = receivedHeader.Code;
// Validate the ICMP header and get the identifier
if (socketConfig.IsIpv4)
{
if (type == (byte)IcmpV4MessageType.EchoReply)
{
// Reply packet has the identifier in the ICMP header.
identifier = receivedHeader.Identifier;
}
else if (type == (byte)IcmpV4MessageType.DestinationUnreachable ||
type == (byte)IcmpV4MessageType.TimeExceeded ||
type == (byte)IcmpV4MessageType.ParameterProblemBadIPHeader ||
type == (byte)IcmpV4MessageType.SourceQuench ||
type == (byte)IcmpV4MessageType.RedirectMessage)
{
// Original IP+ICMP request is in the payload. Read the ICMP header from
// the payload to get identifier.
if (dataOffset + MinIpHeaderLengthInBytes + IcmpHeaderLengthInBytes > bytesReceived)
{
return(false);
}
byte ihl = (byte)(receiveBuffer[dataOffset] & 0x0f); // Internet Header Length
int payloadIpHeaderLength = 4 * ihl;
if (bytesReceived - dataOffset - payloadIpHeaderLength < IcmpHeaderLengthInBytes)
{
return(false); // Not enough bytes to reconstruct actual IP header + ICMP header.
}
IcmpHeader originalRequestHeader = MemoryMarshal.Read <IcmpHeader>(receiveBuffer.AsSpan(dataOffset + payloadIpHeaderLength));
identifier = originalRequestHeader.Identifier;
// Update the date offset to point past the payload IP+ICMP headers. While the specification
// doesn't indicate there should be any additional data the reality is that we often get the
// original packet data back.
dataOffset += payloadIpHeaderLength + IcmpHeaderLengthInBytes;
}
else
{
return(false);
}
}
else
{
if (type == (byte)IcmpV6MessageType.EchoReply)
{
// Reply packet has the identifier in the ICMP header.
identifier = receivedHeader.Identifier;
}
else if (type == (byte)IcmpV6MessageType.DestinationUnreachable ||
type == (byte)IcmpV6MessageType.TimeExceeded ||
type == (byte)IcmpV6MessageType.ParameterProblem ||
type == (byte)IcmpV6MessageType.PacketTooBig)
{
// Original IP+ICMP request is in the payload. Read the ICMP header from
// the payload to get identifier.
if (bytesReceived - dataOffset < IpV6HeaderLengthInBytes + IcmpHeaderLengthInBytes)
{
return(false); // Not enough bytes to reconstruct actual IP header + ICMP header.
}
IcmpHeader originalRequestHeader = MemoryMarshal.Read <IcmpHeader>(receiveBuffer.AsSpan(dataOffset + IpV6HeaderLengthInBytes));
identifier = originalRequestHeader.Identifier;
// Update the date offset to point past the payload IP+ICMP headers. While the specification
// doesn't indicate there should be any additional data the reality is that we often get the
// original packet data back.
dataOffset += IpV6HeaderLengthInBytes + IcmpHeaderLengthInBytes;
}
else
{
return(false);
}
}
if (socketConfig.Identifier != identifier)
{
return(false);
}
sw.Stop();
long roundTripTime = sw.ElapsedMilliseconds;
// We want to return a buffer with the actual data we sent out, not including the header data.
byte[] dataBuffer = new byte[bytesReceived - dataOffset];
Buffer.BlockCopy(receiveBuffer, dataOffset, dataBuffer, 0, dataBuffer.Length);
IPStatus status = socketConfig.IsIpv4
? IcmpV4MessageConstants.MapV4TypeToIPStatus(type, code)
: IcmpV6MessageConstants.MapV6TypeToIPStatus(type, code);
IPAddress address = ((IPEndPoint)socketConfig.EndPoint).Address;
reply = new PingReply(address, socketConfig.Options, status, roundTripTime, dataBuffer);
return(true);
}
