英文:
What is the meaning of "ConnectEx tcp: The semaphore timeout period has expired."
问题
我写了一个简单的Go程序，在Windows上运行，测试远程端口是否活动：
package main
import (
"fmt"
"net"
)
func main(){
conn, err := net.Dial("tcp", "192.168.23.191:3403")
if err != nil {
fmt.Println(err)
} else {
conn.Close()
}
}
现在，远程端口是关闭的。第一次运行时，出现了错误：
dial tcp 192.168.23.191:3403: ConnectEx tcp: 远程计算机拒绝了网络连接。
然后我继续运行它，错误变成了：
dial tcp 192.168.23.191:3403: ConnectEx tcp: 信号量超时期已过。
为什么Dial返回"ConnectEx tcp: 信号量超时期已过"？这个错误的含义是什么？
英文:
I write a simple go program which runs on windows and tests whether the remote port is active:
package main
import (
"fmt"
"net"
)
func main(){
conn, err := net.Dial("tcp", "192.168.23.191:3403")
if err != nil {
fmt.Println(err)
} else {
conn.Close()
}
}
Now, the remote port is closed. I run it first time, and the error is:
dial tcp 192.168.23.191:3403: ConnectEx tcp: The remote computer refused the network connection.
Then I continue to run it, the error is changed to:
dial tcp 192.168.23.191:3403: ConnectEx tcp: The semaphore timeout period has expired.
Why the Dial returns "ConnectEx tcp: The semaphore timeout period has expired."? And what is the meaning of this error?
答案1
得分: 1
net.Dial()的调用超时了。
如这里所示，Dialer结构体有一个Timeout字段，它定义了*Dial()等待连接完成的最长时间*。
英文:
The call to net.Dial() has a timeout which expired.
As seen here, the Dialer struct has a Timeout field which defines the maximum amount of time that a Dial() will wait for a connect to complete.
答案2
得分: 0
net.Dial（以及一些中间函数）最终调用了ConnectEx，这是Windows特定的BSD套接字扩展。如果连接无法建立（Windows遵循RFC 1122第4.2.3.5节并尝试多次），ConnectEx将失败并返回ERROR_SEM_TIMEOUT（据我所知，这并没有正式记录，人们可能期望得到类似WSAETIMEDOUT的错误）。因此，这个错误意味着端口关闭了。
在Windows 8及更高版本的Windows中，可以更改单个套接字的连接设置，如果你想在Go中进行这样的操作，你需要自己进行版本检查和调用。
英文:
net.Dial (with some intermediate functions) ends up calling ConnectEx, a Windows specific extension to BSD Sockets.
If the connection cannot be established (Windows conforms to RFC 1122 Section 4.2.3.5 and tries multiple times) ConnectEx fails with ERROR_SEM_TIMEOUT (AFAIK that isn't officially documented, one would expect an error like WSAETIMEDOUT).
So that error means that the port is closed.
On Windows 8 and newer Versions of Windows it is possible to change the connections settings for a single socket, if you want to do this in Go you have to do the version check and calls for yourself.
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