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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// File contains DN parsing functionallity
//
// https://tools.ietf.org/html/rfc4514
//
// distinguishedName = [ relativeDistinguishedName
// *( COMMA relativeDistinguishedName ) ]
// relativeDistinguishedName = attributeTypeAndValue
// *( PLUS attributeTypeAndValue )
// attributeTypeAndValue = attributeType EQUALS attributeValue
// attributeType = descr / numericoid
// attributeValue = string / hexstring
//
// ; The following characters are to be escaped when they appear
// ; in the value to be encoded: ESC, one of <escaped>, leading
// ; SHARP or SPACE, trailing SPACE, and NULL.
// string = [ ( leadchar / pair ) [ *( stringchar / pair )
// ( trailchar / pair ) ] ]
//
// leadchar = LUTF1 / UTFMB
// LUTF1 = %x01-1F / %x21 / %x24-2A / %x2D-3A /
// %x3D / %x3F-5B / %x5D-7F
//
// trailchar = TUTF1 / UTFMB
// TUTF1 = %x01-1F / %x21 / %x23-2A / %x2D-3A /
// %x3D / %x3F-5B / %x5D-7F
//
// stringchar = SUTF1 / UTFMB
// SUTF1 = %x01-21 / %x23-2A / %x2D-3A /
// %x3D / %x3F-5B / %x5D-7F
//
// pair = ESC ( ESC / special / hexpair )
// special = escaped / SPACE / SHARP / EQUALS
// escaped = DQUOTE / PLUS / COMMA / SEMI / LANGLE / RANGLE
// hexstring = SHARP 1*hexpair
// hexpair = HEX HEX
//
// where the productions <descr>, <numericoid>, <COMMA>, <DQUOTE>,
// <EQUALS>, <ESC>, <HEX>, <LANGLE>, <NULL>, <PLUS>, <RANGLE>, <SEMI>,
// <SPACE>, <SHARP>, and <UTFMB> are defined in [RFC4512].
//
package ldap
import (
"bytes"
enchex "encoding/hex"
"errors"
"fmt"
"strings"
ber "gopkg.in/asn1-ber.v1"
)
// AttributeTypeAndValue represents an attributeTypeAndValue from https://tools.ietf.org/html/rfc4514
type AttributeTypeAndValue struct {
// Type is the attribute type
Type string
// Value is the attribute value
Value string
}
// RelativeDN represents a relativeDistinguishedName from https://tools.ietf.org/html/rfc4514
type RelativeDN struct {
Attributes []*AttributeTypeAndValue
}
// DN represents a distinguishedName from https://tools.ietf.org/html/rfc4514
type DN struct {
RDNs []*RelativeDN
}
// ParseDN returns a distinguishedName or an error
func ParseDN(str string) (*DN, error) {
dn := new(DN)
dn.RDNs = make([]*RelativeDN, 0)
rdn := new(RelativeDN)
rdn.Attributes = make([]*AttributeTypeAndValue, 0)
buffer := bytes.Buffer{}
attribute := new(AttributeTypeAndValue)
escaping := false
for i := 0; i < len(str); i++ {
char := str[i]
if escaping {
escaping = false
switch char {
case ' ', '"', '#', '+', ',', ';', '<', '=', '>', '\\':
buffer.WriteByte(char)
continue
}
// Not a special character, assume hex encoded octet
if len(str) == i+1 {
return nil, errors.New("Got corrupted escaped character")
}
dst := []byte{0}
n, err := enchex.Decode([]byte(dst), []byte(str[i:i+2]))
if err != nil {
return nil, fmt.Errorf("Failed to decode escaped character: %s", err)
} else if n != 1 {
return nil, fmt.Errorf("Expected 1 byte when un-escaping, got %d", n)
}
buffer.WriteByte(dst[0])
i++
} else if char == '\\' {
escaping = true
} else if char == '=' {
attribute.Type = buffer.String()
buffer.Reset()
// Special case: If the first character in the value is # the
// following data is BER encoded so we can just fast forward
// and decode.
if len(str) > i+1 && str[i+1] == '#' {
i += 2
index := strings.IndexAny(str[i:], ",+")
data := str
if index > 0 {
data = str[i : i+index]
} else {
data = str[i:]
}
rawBER, err := enchex.DecodeString(data)
if err != nil {
return nil, fmt.Errorf("Failed to decode BER encoding: %s", err)
}
packet := ber.DecodePacket(rawBER)
buffer.WriteString(packet.Data.String())
i += len(data) - 1
}
} else if char == ',' || char == '+' {
// We're done with this RDN or value, push it
attribute.Value = buffer.String()
rdn.Attributes = append(rdn.Attributes, attribute)
attribute = new(AttributeTypeAndValue)
if char == ',' {
dn.RDNs = append(dn.RDNs, rdn)
rdn = new(RelativeDN)
rdn.Attributes = make([]*AttributeTypeAndValue, 0)
}
buffer.Reset()
} else {
buffer.WriteByte(char)
}
}
if buffer.Len() > 0 {
if len(attribute.Type) == 0 {
return nil, errors.New("DN ended with incomplete type, value pair")
}
attribute.Value = buffer.String()
rdn.Attributes = append(rdn.Attributes, attribute)
dn.RDNs = append(dn.RDNs, rdn)
}
return dn, nil
}
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