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使用F＃中的原始套接字编写异步Ping以使用尽可能少的线程启用并行请求。不使用“System.Net.NetworkInformation.Ping”，因为它似乎为每个请求分配一个线程。我也对使用F＃异步工作流感兴趣。如何检测使用异步Socket.BeginReceive时的超时？
下面的同步版本正确超时目标主机不存在/响应，但异步版本挂起。两者都在主机确实响应时工作。不知道这是一个.NET的问题，或一个F＃之一...
任何想法？
（注：该过程必须以管理员身份运行，让原始套接字的访问）
这将引发超时：
let result = Ping.Ping (IPAddress.Parse("192.168.33.22"), 1000)
然而，这种挂起：
let result = Ping.AsyncPing (IPAddress.Parse("192.168.33.22"), 1000)
|> Async.RunSynchronously
下面的代码...
module Ping
open System
open System.Net
open System.Net.Sockets
open System.Threading
//---- ICMP Packet Classes
type IcmpMessage (t : byte) =
let mutable m_type = t
let mutable m_code = 0uy
let mutable m_checksum = 0us
member this.Type
with get() = m_type
member this.Code
with get() = m_code
member this.Checksum = m_checksum
abstract Bytes : byte array
default this.Bytes
with get() =
[|
m_type
m_code
byte(m_checksum)
byte(m_checksum >>> 8)
|]
member this.GetChecksum() =
let mutable sum = 0ul
let bytes = this.Bytes
let mutable i = 0
// Sum up uint16s
while i < bytes.Length - 1 do
sum <- sum + uint32(BitConverter.ToUInt16(bytes, i))
i <- i + 2
// Add in last byte, if an odd size buffer
if i <> bytes.Length then
sum <- sum + uint32(bytes.[i])
// Shuffle the bits
sum <- (sum >>> 16) + (sum &&& 0xFFFFul)
sum <- sum + (sum >>> 16)
sum <- ~~~sum
uint16(sum)
member this.UpdateChecksum() =
m_checksum <- this.GetChecksum()
type InformationMessage (t : byte) =
inherit IcmpMessage(t)
let mutable m_identifier = 0us
let mutable m_sequenceNumber = 0us
member this.Identifier = m_identifier
member this.SequenceNumber = m_sequenceNumber
override this.Bytes
with get() =
Array.append (base.Bytes)
[|
byte(m_identifier)
byte(m_identifier >>> 8)
byte(m_sequenceNumber)
byte(m_sequenceNumber >>> 8)
|]
type EchoMessage() =
inherit InformationMessage(8uy)
let mutable m_data = Array.create 32 32uy
do base.UpdateChecksum()
member this.Data
with get() = m_data
and set(d) = m_data <- d
this.UpdateChecksum()
override this.Bytes
with get() =
Array.append (base.Bytes)
(this.Data)
//---- Synchronous Ping
let Ping (host : IPAddress, timeout : int) =
let mutable ep = new IPEndPoint(host, 0)
let socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp)
socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout)
socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout)
let packet = EchoMessage()
let mutable buffer = packet.Bytes
try
if socket.SendTo(buffer, ep) <= 0 then
raise (SocketException())
buffer <- Array.create (buffer.Length + 20) 0uy
let mutable epr = ep :> EndPoint
if socket.ReceiveFrom(buffer, &epr) <= 0 then
raise (SocketException())
finally
socket.Close()
buffer
//---- Entensions to the F# Async class to allow up to 5 paramters (not just 3)
type Async with
static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async<'T> =
Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction)
static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async<'T> =
Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction)
//---- Extensions to the Socket class to provide async SendTo and ReceiveFrom
type System.Net.Sockets.Socket with
member this.AsyncSendTo(buffer, offset, size, socketFlags, remoteEP) =
Async.FromBeginEnd(buffer, offset, size, socketFlags, remoteEP,
this.BeginSendTo,
this.EndSendTo)
member this.AsyncReceiveFrom(buffer, offset, size, socketFlags, remoteEP) =
Async.FromBeginEnd(buffer, offset, size, socketFlags, remoteEP,
this.BeginReceiveFrom,
(fun asyncResult -> this.EndReceiveFrom(asyncResult, remoteEP)))
//---- Asynchronous Ping
let AsyncPing (host : IPAddress, timeout : int) =
async {
let ep = IPEndPoint(host, 0)
use socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp)
socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout)
socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout)
let packet = EchoMessage()
let outbuffer = packet.Bytes
try
let! result = socket.AsyncSendTo(outbuffer, 0, outbuffer.Length, SocketFlags.None, ep)
if result <= 0 then
raise (SocketException())
let epr = ref (ep :> EndPoint)
let inbuffer = Array.create (outbuffer.Length + 256) 0uy
let! result = socket.AsyncReceiveFrom(inbuffer, 0, inbuffer.Length, SocketFlags.None, epr)
if result <= 0 then
raise (SocketException())
return inbuffer
finally
socket.Close()
}
有要重新发明System.Net.NetworkInformation.Ping.SendAsync（）什么特别的原因？它已经支持超时。 – 2010-04-03 17:32:20
SendAsync/SendToAsync与上面的AsyncSendTo不一样...前者不与F＃异步工作流集成（极大地简化了编写异步代码）。 – 2010-04-03 18:12:02
呃，重点是你不必写它。 – 2010-04-03 18:44:15