Program exiting with a panic when trying to do a simplebind with controls.

[krishtk]

I wrote a test program to check the password controls feature for my LDAP directory but it is failing when I am trying to run the code.

Some more info on this bug:
This happens only when the authentication is successful and when I am expecting to get some info on the pasword policy.

The same setup works when I use python library. It gives proper info but with this library I always end up with a panic.

If someone who understands the issue can point me in the right direction that would be more than enough.

My code:

var ldapServer = "acmewapp.stage.acme.com"
var ldapPort = uint16(636)

l, err := ldap.DialTLS("tcp", fmt.Sprintf("%s:%d", ldapServer, ldapPort), &tls.Config{InsecureSkipVerify: true})
//l, err := ldap.Dial("tcp", fmt.Sprintf("%s:%d", ldapServer, ldapPort))
if err != nil {
	fmt.Printf(err.Error())
	return
}
defer l.Close()

controls := []ldap.Control{}
controls = append(controls, ldap.NewControlBeheraPasswordPolicy())
bindRequest := ldap.NewSimpleBindRequest("cn=acmewapp,dc=stage,dc=acme,dc=com", "password!@#", controls)
r, err := l.SimpleBind(bindRequest)

ppolicyControl := ldap.FindControl(r.Controls, ldap.ControlTypeBeheraPasswordPolicy)
var ppolicy *ldap.ControlBeheraPasswordPolicy
if ppolicyControl != nil {
	ppolicy = ppolicyControl.(*ldap.ControlBeheraPasswordPolicy)
} else {
	fmt.Println("ppolicyControl response not available.\n")
}
if err != nil {
	fmt.Println("err simplebind request %s", err.Error())
	if ppolicy != nil && ppolicy.Error >= 0 {
		fmt.Println("ppolicy string %s", ppolicy.ErrorString)
	}
}

Error that I am seeing:

go run main.go
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x460e9d]

goroutine 1 [running]:
runtime.panic(0x5b11e0, 0x7dbee8)
	/usr/lib/go/src/pkg/runtime/panic.c:266 +0xb6
gopkg.in/ldap%2ev2.DecodeControl(0xc2100798c0, 0x0, 0x0)
	/opt/wapp/golang/src/gopkg.in/ldap.v2/control.go:339 +0x97d
gopkg.in/ldap%2ev2.(*Conn).SimpleBind(0xc21000f640, 0xc210051480, 0x0, 0x0, 0x0)
	/opt/wapp/golang/src/gopkg.in/ldap.v2/bind.go:88 +0x5ba
main.main()
	/opt/wapp/golang/testproj/main.go:26 +0x46b

goroutine 6 [runnable]:
net.runtime_pollWait(0x7fb34da06180, 0x72, 0x0)
	/usr/lib/go/src/pkg/runtime/netpoll.goc:116 +0x6a
net.(*pollDesc).Wait(0xc210047140, 0x72, 0x7fb34da050c0, 0xb)
	/usr/lib/go/src/pkg/net/fd_poll_runtime.go:81 +0x34
net.(*pollDesc).WaitRead(0xc210047140, 0xb, 0x7fb34da050c0)
	/usr/lib/go/src/pkg/net/fd_poll_runtime.go:86 +0x30
net.(*netFD).Read(0xc2100470e0, 0xc210070000, 0x800, 0x800, 0x0, ...)
	/usr/lib/go/src/pkg/net/fd_unix.go:204 +0x2a0
net.(*conn).Read(0xc210000078, 0xc210070000, 0x800, 0x800, 0x47cd81, ...)
	/usr/lib/go/src/pkg/net/net.go:122 +0xc5
crypto/tls.(*block).readFromUntil(0xc21001e840, 0x7fb34da06278, 0xc210000078, 0x5, 0xc210000078, ...)
	/usr/lib/go/src/pkg/crypto/tls/conn.go:459 +0xb6
crypto/tls.(*Conn).readRecord(0xc210052780, 0x17, 0x0, 0xc2100007e0)
	/usr/lib/go/src/pkg/crypto/tls/conn.go:539 +0x107
crypto/tls.(*Conn).Read(0xc210052780, 0xc2100007e0, 0x1, 0x1, 0x0, ...)
	/usr/lib/go/src/pkg/crypto/tls/conn.go:897 +0x135
io.ReadAtLeast(0x7fb34da06608, 0xc210052780, 0xc2100007e0, 0x1, 0x1, ...)
	/usr/lib/go/src/pkg/io/io.go:288 +0xf6
io.ReadFull(0x7fb34da06608, 0xc210052780, 0xc2100007e0, 0x1, 0x1, ...)
	/usr/lib/go/src/pkg/io/io.go:306 +0x71
gopkg.in/asn1-ber%2ev1.readByte(0x7fb34da06608, 0xc210052780, 0x41f558, 0x7f3780, 0xa)
	/opt/wapp/golang/src/gopkg.in/asn1-ber.v1/util.go:7 +0x78
gopkg.in/asn1-ber%2ev1.readIdentifier(0x7fb34da06608, 0xc210052780, 0x4669f7, 0x56cea0, 0x2, ...)
	/opt/wapp/golang/src/gopkg.in/asn1-ber.v1/identifier.go:15 +0x6c
gopkg.in/asn1-ber%2ev1.readHeader(0x7fb34da06608, 0xc210052780, 0x0, 0x0, 0xc21000f000, ...)
	/opt/wapp/golang/src/gopkg.in/asn1-ber.v1/header.go:9 +0x6d
gopkg.in/asn1-ber%2ev1.readPacket(0x7fb34da06608, 0xc210052780, 0x5a1820, 0x5d6a60, 0xc200000000, ...)
	/opt/wapp/golang/src/gopkg.in/asn1-ber.v1/ber.go:276 +0x42
gopkg.in/asn1-ber%2ev1.ReadPacket(0x7fb34da06608, 0xc210052780, 0xc210052780, 0x7fb34da06608, 0xc210052780)
	/opt/wapp/golang/src/gopkg.in/asn1-ber.v1/ber.go:199 +0x31
gopkg.in/ldap%2ev2.(*Conn).reader(0xc21000f640)
	/opt/wapp/golang/src/gopkg.in/ldap.v2/conn.go:442 +0x111
created by gopkg.in/ldap%2ev2.(*Conn).Start
	/opt/wapp/golang/src/gopkg.in/ldap.v2/conn.go:155 +0x2e

goroutine 5 [syscall]:
runtime.goexit()
	/usr/lib/go/src/pkg/runtime/proc.c:1394
exit status 2

Any info on this would be helpful.

Thanks.

[zhunxun]

How to solve this problem?

[krishnatejak]

No solution yet.

[vetinari]

which version are you running?

cd $GOPATH/go/src/gopkg.in/ldap.v2 && git tag -l

[krishnatejak]

I was using the latest v2.5.1

[vetinari]

ok... this may happen when the server sends a mis-encoded control:
https://github.com/go-ldap/ldap/blob/v2.5.1/control.go#L338-L339
the ber.DecodePacket() returns nil when there's an error decoding. We should switch to DecodePacketErr probably

[vetinari]

Can you check if this works for you
vetinari@760755c

[zhunxun]

[vetinari]

please check #166

[krishnatejak]

Hey Vetinari the solutions above will solve the problem of the program exiting but it won't address the issue of me not getting the cotrols back. I have tried those changes myself before and it works. I will try the fix 166 and update you on my results.

[zhunxun]

yet,can not getting the cotrols back.

[stefanmcshane]

Closing as release v3.2.3 should address