net: getaddrinfow: The specified class was not found.

[jeffkayser2]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

D:\Users\jeff.kayser\Desktop>go version
go version go1.10.2 windows/amd64

D:\Users\jeff.kayser\Desktop>

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

D:\Users\jeff.kayser\Desktop>go env
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\jeff.kayser\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=d:\users\jeff.kayser\workspace\gobook
set GORACE=
set GOROOT=C:\Go
set GOTMPDIR=
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fm
e-length=0 -fdebug-prefix-map=C:\Users\JEFF~1.KAY\AppData\Local\Temp\go-bui
424142=/tmp/go-build -gno-record-gcc-switches

D:\Users\jeff.kayser\Desktop>

What did you do?

Tried to write an IMAP client based on:
https://github.com/emersion/go-imap

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

package main

import (
"bufio"
"fmt"
"log"
"os"

    "github.com/emersion/go-imap/client"
    "github.com/emersion/go-imap"

)

func main() {

    var serverport, username, password string

    reader := bufio.NewReader(os.Stdin)

    log.Println("Connecting to server...")
    // Connect to server
    // c, err := client.DialTLS("mail.example.org:993", nil)
    fmt.Printf("server:port> ")
    serverport, _ = reader.ReadString('\n')
    fmt.Printf("connecting to: %s...\n", serverport)
    c, err := client.DialTLS(serverport, nil)
    if err != nil {
            log.Fatal(err)
    }
    log.Println("Connected")

    // Don't forget to logout
    defer c.Logout()

    // Login
    // if err := c.Login("username", "password"); err != nil {
    fmt.Printf("username: ")
    username, _ = reader.ReadString('\n')
    fmt.Printf("password: ")
    password, _ = reader.ReadString('\n')
    fmt.Printf("logging in as: %s...\n", username)
    if err := c.Login(username, password); err != nil {
            log.Fatal(err)
    }
    log.Println("Logged in")

    // List mailboxes
    mailboxes := make(chan *imap.MailboxInfo, 10)
    done := make(chan error, 1)
    go func () {
            done <- c.List("", "*", mailboxes)
    }()

    log.Println("Mailboxes:")
    for m := range mailboxes {
            log.Println("* " + m.Name)
    }

    if err := <-done; err != nil {
            log.Fatal(err)
    }

    // Select INBOX
    mbox, err := c.Select("INBOX", false)
    if err != nil {
            log.Fatal(err)
    }
    log.Println("Flags for INBOX:", mbox.Flags)

    // Get the last 4 messages
    from := uint32(1)
    to := mbox.Messages
    if mbox.Messages > 3 {
            // We're using unsigned integers here, only substract if the result is > 0
            from = mbox.Messages - 3
    }
    seqset := new(imap.SeqSet)
    seqset.AddRange(from, to)

    messages := make(chan *imap.Message, 10)
    done = make(chan error, 1)
    go func() {
            done <- c.Fetch(seqset, []imap.FetchItem{imap.FetchEnvelope}, messages)
    }()

    log.Println("Last 4 messages:")
    for msg := range messages {
            log.Println("* " + msg.Envelope.Subject)
    }

    if err := <-done; err != nil {
            log.Fatal(err)
    }

    log.Println("Done!")

}

What did you expect to see?

I expected the program to connect to the IMAP server.

What did you see instead?

D:\Users\jeff.kayser\Desktop>main.exe
2018/05/24 17:03:46 Connecting to server...
server:port> mail.jibeconsulting.com:143
connecting to: mail.jibeconsulting.com:143
...
2018/05/24 17:03:55 dial tcp: lookup tcp/143
: getaddrinfow: The specified class was not found.

D:\Users\jeff.kayser\Desktop>

[mattn]

I don't make sure but probably, the serverport contain spaces or \r.

[andybons]

This seems like a better question for the https://github.com/emersion/go-imap project. Closing for now. Please let me know if I should re-open due to a Go-specific issue.

[Dextroz]

Issue: "getaddrinfow: The specified class was not found."

I believe the error might possibly be related to net.Dial("tcp", address string)
I am passing in a var called "addr_port" (which would be a string) into net.Dial() like so: net.Dial("tcp", addr_port) and am receiving this error. I have checked the variable and it is of type string so I am confused as to why this error is occurring. When I place the string directly into net.Dial("tcp", "www.hackthissite.org:80") is works as expected.
Am I missing something strikingly obvious here or is this some sort of bug?

My Code:

https://github.com/Dextroz/pscan.go/blob/master/pscan.go

Go Version

go version go1.10.2 windows/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\danie\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=C:\Users\danie\go
set GORACE=
set GOROOT=C:\Go
set GOTMPDIR=
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=C:\Users\danie\AppData\Local\Temp\go-build886849918=/tmp/go-build -gno-record-gcc-switches

[andybons]

Indeed @mattn is correct. According to the ReadString documentation:

ReadString reads until the first occurrence of delim in the input, returning a string containing the data up to and including the delimiter.

This means that if you enter google.com:80 and press return then addr_port will be google.com:80\n. You have to trim off the newline to get your desired behavior.

[Dextroz]

@mattn @andybons Ahh, this makes complete sense. I will rectify my code. Thank you your the help and insight guys!