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fix: packet referral decoding #413

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merged 2 commits into from
Feb 9, 2023
Merged

fix: packet referral decoding #413

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55184a9
fix: packet referral decoding
james-d-elliott Jan 21, 2023
b5be576
docs: add documentation to the changes
james-d-elliott Feb 9, 2023
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6 changes: 1 addition & 5 deletions modify.go
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Original file line number Diff line number Diff line change
Expand Up @@ -160,11 +160,7 @@ func (l *Conn) ModifyWithResult(modifyRequest *ModifyRequest) (*ModifyResult, er
switch packet.Children[1].Tag {
case ApplicationModifyResponse:
if err = GetLDAPError(packet); err != nil {
if referral, referralErr := getReferral(err, packet); referralErr != nil {
return result, referralErr
} else {
result.Referral = referral
}
result.Referral = getReferral(err, packet)

return result, err
}
Expand Down
7 changes: 1 addition & 6 deletions passwdmodify.go
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,6 @@ func (req *PasswordModifyRequest) appendTo(envelope *ber.Packet) error {
// newPassword is the desired user's password. If empty the server can return
// an error or generate a new password that will be available in the
// PasswordModifyResult.GeneratedPassword
//
func NewPasswordModifyRequest(userIdentity string, oldPassword string, newPassword string) *PasswordModifyRequest {
return &PasswordModifyRequest{
UserIdentity: userIdentity,
Expand All @@ -96,11 +95,7 @@ func (l *Conn) PasswordModify(passwordModifyRequest *PasswordModifyRequest) (*Pa

if packet.Children[1].Tag == ApplicationExtendedResponse {
if err = GetLDAPError(packet); err != nil {
if referral, referralErr := getReferral(err, packet); referralErr != nil {
return result, referralErr
} else {
result.Referral = referral
}
result.Referral = getReferral(err, packet)

return result, err
}
Expand Down
33 changes: 22 additions & 11 deletions request.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ package ldap

import (
"errors"
"fmt"

ber "github.com/go-asn1-ber/asn1-ber"
)
Expand Down Expand Up @@ -71,28 +70,40 @@ func (l *Conn) readPacket(msgCtx *messageContext) (*ber.Packet, error) {
return packet, nil
}

func getReferral(err error, packet *ber.Packet) (referral string, e error) {
func getReferral(err error, packet *ber.Packet) (referral string) {
if !IsErrorWithCode(err, LDAPResultReferral) {
return "", nil
return ""
}

if len(packet.Children) < 2 {
return "", fmt.Errorf("ldap: returned error indicates the packet contains a referral but it doesn't have sufficient child nodes: %w", err)
return ""
}

if packet.Children[1].Tag != ber.TagObjectDescriptor {
return "", fmt.Errorf("ldap: returned error indicates the packet contains a referral but the relevant child node isn't an object descriptor: %w", err)
// The packet Tag itself (of child 2) is generally a ber.TagObjectDescriptor with referrals however OpenLDAP
// seemingly returns a ber.Tag.GeneralizedTime. Every currently tested LDAP server which returns referrals returns
// an ASN.1 BER packet with the Type of ber.TypeConstructed and Class of ber.ClassApplication however. Thus this
// check expressly checks these fields instead.
//
// Related Issues:
// - https://github.com/authelia/authelia/issues/4199 (downstream)
if len(packet.Children[1].Children) == 0 || (packet.Children[1].TagType != ber.TypeConstructed || packet.Children[1].ClassType != ber.ClassApplication) {
return ""
}

var ok bool

for _, child := range packet.Children[1].Children {
if child.Tag == ber.TagBitString && len(child.Children) >= 1 {
if referral, ok = child.Children[0].Value.(string); ok {
return referral, nil
}
// The referral URI itself should be contained within a child which has a Tag of ber.BitString or
// ber.TagPrintableString, and the Type of ber.TypeConstructed and the Class of ClassContext. As soon as any of
// these conditions is not true we can skip this child.
if (child.Tag != ber.TagBitString && child.Tag != ber.TagPrintableString) || child.TagType != ber.TypeConstructed || child.ClassType != ber.ClassContext {
continue
}

if referral, ok = child.Children[0].Value.(string); ok {
return referral
}
}

return "", fmt.Errorf("ldap: returned error indicates the packet contains a referral but the referral couldn't be decoded: %w", err)
return ""
}
6 changes: 1 addition & 5 deletions v3/modify.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,11 +160,7 @@ func (l *Conn) ModifyWithResult(modifyRequest *ModifyRequest) (*ModifyResult, er
switch packet.Children[1].Tag {
case ApplicationModifyResponse:
if err = GetLDAPError(packet); err != nil {
if referral, referralErr := getReferral(err, packet); referralErr != nil {
return result, referralErr
} else {
result.Referral = referral
}
result.Referral = getReferral(err, packet)

return result, err
}
Expand Down
7 changes: 1 addition & 6 deletions v3/passwdmodify.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,6 @@ func (req *PasswordModifyRequest) appendTo(envelope *ber.Packet) error {
// newPassword is the desired user's password. If empty the server can return
// an error or generate a new password that will be available in the
// PasswordModifyResult.GeneratedPassword
//
func NewPasswordModifyRequest(userIdentity string, oldPassword string, newPassword string) *PasswordModifyRequest {
return &PasswordModifyRequest{
UserIdentity: userIdentity,
Expand All @@ -96,11 +95,7 @@ func (l *Conn) PasswordModify(passwordModifyRequest *PasswordModifyRequest) (*Pa

if packet.Children[1].Tag == ApplicationExtendedResponse {
if err = GetLDAPError(packet); err != nil {
if referral, referralErr := getReferral(err, packet); referralErr != nil {
return result, referralErr
} else {
result.Referral = referral
}
result.Referral = getReferral(err, packet)

return result, err
}
Expand Down
33 changes: 22 additions & 11 deletions v3/request.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ package ldap

import (
"errors"
"fmt"

ber "github.com/go-asn1-ber/asn1-ber"
)
Expand Down Expand Up @@ -71,28 +70,40 @@ func (l *Conn) readPacket(msgCtx *messageContext) (*ber.Packet, error) {
return packet, nil
}

func getReferral(err error, packet *ber.Packet) (referral string, e error) {
func getReferral(err error, packet *ber.Packet) (referral string) {
if !IsErrorWithCode(err, LDAPResultReferral) {
return "", nil
return ""
}

if len(packet.Children) < 2 {
return "", fmt.Errorf("ldap: returned error indicates the packet contains a referral but it doesn't have sufficient child nodes: %w", err)
return ""
}

if packet.Children[1].Tag != ber.TagObjectDescriptor {
return "", fmt.Errorf("ldap: returned error indicates the packet contains a referral but the relevant child node isn't an object descriptor: %w", err)
// The packet Tag itself (of child 2) is generally a ber.TagObjectDescriptor with referrals however OpenLDAP
// seemingly returns a ber.Tag.GeneralizedTime. Every currently tested LDAP server which returns referrals returns
// an ASN.1 BER packet with the Type of ber.TypeConstructed and Class of ber.ClassApplication however. Thus this
// check expressly checks these fields instead.
//
// Related Issues:
// - https://github.com/authelia/authelia/issues/4199 (downstream)
if len(packet.Children[1].Children) == 0 || (packet.Children[1].TagType != ber.TypeConstructed || packet.Children[1].ClassType != ber.ClassApplication) {
return ""
}

var ok bool

for _, child := range packet.Children[1].Children {
if child.Tag == ber.TagBitString && len(child.Children) >= 1 {
if referral, ok = child.Children[0].Value.(string); ok {
return referral, nil
}
// The referral URI itself should be contained within a child which has a Tag of ber.BitString or
// ber.TagPrintableString, and the Type of ber.TypeConstructed and the Class of ClassContext. As soon as any of
// these conditions is not true we can skip this child.
if (child.Tag != ber.TagBitString && child.Tag != ber.TagPrintableString) || child.TagType != ber.TypeConstructed || child.ClassType != ber.ClassContext {
continue
}

if referral, ok = child.Children[0].Value.(string); ok {
return referral
}
}

return "", fmt.Errorf("ldap: returned error indicates the packet contains a referral but the referral couldn't be decoded: %w", err)
return ""
}