panic: runtime error: send on closed channel

[zealws]

I'm building a web-application that uses an LDAP server for authentication.

All the server needs to do is login using the LDAP server, no authorizations are made beyond that.

When I use the library to login once, it works fine, however, on a second try, it will panic.

A very minimal example that reproduces this problem is:

package main

import (
    "fmt"
    "github.com/mmitton/ldap"
    "log"
)

const (
    ADDR   = "WWWW"
    DOMAIN = "XXXX"
    USER   = "YYYY"
    PASS   = "ZZZZ"
)

func main() {
    fmt.Println("Try 1...")
    doLDAP()

    fmt.Println("\nTry 2...")
    doLDAP()
}

func doLDAP() {
    conn, err := ldap.Dial("tcp", ADDR)
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()

    fmt.Println("Connected successfully")

    err = conn.Bind(DOMAIN+"\\"+USER, PASS)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println("Logged in successfully")
}

Note that the constants are modified to working values for the LDAP server I am using.

The output is:

Try 1...
Connected successfully
Logged in successfully

Try 2...
closeAllChannels
panic: runtime error: send on closed channel

goroutine 25 [running]:
runtime.panic(0x5cd8e0, 0x71b19e)
    /tmp/go/src/pkg/runtime/panic.c:279 +0xf5
github.com/mmitton/ldap.func·003()
    /home/zeal/go/src/github.com/mmitton/ldap/conn.go:299 +0x4c
created by github.com/mmitton/ldap.(*Conn).sendProcessMessage
    /home/zeal/go/src/github.com/mmitton/ldap/conn.go:299 +0xa0

[sivel]

I can confirm this as well. Everything works well up until the point when Close is called in my tests.

[sivel]

FWIW, It looks like someone else has this fixed in their fork:

vanackere@3f715a8

[zealws]

FWIW, I wound up using cgo and openldap. Not quite as straight-forward but far more reliable.

I may open source the code I wrote in the future, but it's hard to write automated tests for an LDAP library since it requires posting test account credentials to GitHub.