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filter.go
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filter.go
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package ldap
import (
"bytes"
hexpac "encoding/hex"
"errors"
"fmt"
"io"
"strings"
"unicode"
"unicode/utf8"
ber "github.com/go-asn1-ber/asn1-ber"
)
// Filter choices
const (
FilterAnd = 0
FilterOr = 1
FilterNot = 2
FilterEqualityMatch = 3
FilterSubstrings = 4
FilterGreaterOrEqual = 5
FilterLessOrEqual = 6
FilterPresent = 7
FilterApproxMatch = 8
FilterExtensibleMatch = 9
)
// FilterMap contains human readable descriptions of Filter choices
var FilterMap = map[uint64]string{
FilterAnd: "And",
FilterOr: "Or",
FilterNot: "Not",
FilterEqualityMatch: "Equality Match",
FilterSubstrings: "Substrings",
FilterGreaterOrEqual: "Greater Or Equal",
FilterLessOrEqual: "Less Or Equal",
FilterPresent: "Present",
FilterApproxMatch: "Approx Match",
FilterExtensibleMatch: "Extensible Match",
}
// SubstringFilter options
const (
FilterSubstringsInitial = 0
FilterSubstringsAny = 1
FilterSubstringsFinal = 2
)
// FilterSubstringsMap contains human readable descriptions of SubstringFilter choices
var FilterSubstringsMap = map[uint64]string{
FilterSubstringsInitial: "Substrings Initial",
FilterSubstringsAny: "Substrings Any",
FilterSubstringsFinal: "Substrings Final",
}
// MatchingRuleAssertion choices
const (
MatchingRuleAssertionMatchingRule = 1
MatchingRuleAssertionType = 2
MatchingRuleAssertionMatchValue = 3
MatchingRuleAssertionDNAttributes = 4
)
// MatchingRuleAssertionMap contains human readable descriptions of MatchingRuleAssertion choices
var MatchingRuleAssertionMap = map[uint64]string{
MatchingRuleAssertionMatchingRule: "Matching Rule Assertion Matching Rule",
MatchingRuleAssertionType: "Matching Rule Assertion Type",
MatchingRuleAssertionMatchValue: "Matching Rule Assertion Match Value",
MatchingRuleAssertionDNAttributes: "Matching Rule Assertion DN Attributes",
}
var _SymbolAny = []byte{'*'}
// CompileFilter converts a string representation of a filter into a BER-encoded packet
func CompileFilter(filter string) (*ber.Packet, error) {
if len(filter) == 0 || filter[0] != '(' {
return nil, NewError(ErrorFilterCompile, errors.New("ldap: filter does not start with an '('"))
}
packet, pos, err := compileFilter(filter, 1)
if err != nil {
return nil, err
}
switch {
case pos > len(filter):
return nil, NewError(ErrorFilterCompile, errors.New("ldap: unexpected end of filter"))
case pos < len(filter):
return nil, NewError(ErrorFilterCompile, errors.New("ldap: finished compiling filter with extra at end: "+fmt.Sprint(filter[pos:])))
}
return packet, nil
}
// DecompileFilter converts a packet representation of a filter into a string representation
func DecompileFilter(packet *ber.Packet) (_ string, err error) {
defer func() {
if r := recover(); r != nil {
err = NewError(ErrorFilterDecompile, errors.New("ldap: error decompiling filter"))
}
}()
buf := bytes.NewBuffer(nil)
buf.WriteByte('(')
childStr := ""
switch packet.Tag {
case FilterAnd:
buf.WriteByte('&')
for _, child := range packet.Children {
childStr, err = DecompileFilter(child)
if err != nil {
return
}
buf.WriteString(childStr)
}
case FilterOr:
buf.WriteByte('|')
for _, child := range packet.Children {
childStr, err = DecompileFilter(child)
if err != nil {
return
}
buf.WriteString(childStr)
}
case FilterNot:
buf.WriteByte('!')
childStr, err = DecompileFilter(packet.Children[0])
if err != nil {
return
}
buf.WriteString(childStr)
case FilterSubstrings:
buf.WriteString(ber.DecodeString(packet.Children[0].Data.Bytes()))
buf.WriteByte('=')
for i, child := range packet.Children[1].Children {
if i == 0 && child.Tag != FilterSubstringsInitial {
buf.Write(_SymbolAny)
}
buf.WriteString(EscapeFilter(ber.DecodeString(child.Data.Bytes())))
if child.Tag != FilterSubstringsFinal {
buf.Write(_SymbolAny)
}
}
case FilterEqualityMatch:
buf.WriteString(ber.DecodeString(packet.Children[0].Data.Bytes()))
buf.WriteByte('=')
buf.WriteString(EscapeFilter(ber.DecodeString(packet.Children[1].Data.Bytes())))
case FilterGreaterOrEqual:
buf.WriteString(ber.DecodeString(packet.Children[0].Data.Bytes()))
buf.WriteString(">=")
buf.WriteString(EscapeFilter(ber.DecodeString(packet.Children[1].Data.Bytes())))
case FilterLessOrEqual:
buf.WriteString(ber.DecodeString(packet.Children[0].Data.Bytes()))
buf.WriteString("<=")
buf.WriteString(EscapeFilter(ber.DecodeString(packet.Children[1].Data.Bytes())))
case FilterPresent:
buf.WriteString(ber.DecodeString(packet.Data.Bytes()))
buf.WriteString("=*")
case FilterApproxMatch:
buf.WriteString(ber.DecodeString(packet.Children[0].Data.Bytes()))
buf.WriteString("~=")
buf.WriteString(EscapeFilter(ber.DecodeString(packet.Children[1].Data.Bytes())))
case FilterExtensibleMatch:
attr := ""
dnAttributes := false
matchingRule := ""
value := ""
for _, child := range packet.Children {
switch child.Tag {
case MatchingRuleAssertionMatchingRule:
matchingRule = ber.DecodeString(child.Data.Bytes())
case MatchingRuleAssertionType:
attr = ber.DecodeString(child.Data.Bytes())
case MatchingRuleAssertionMatchValue:
value = ber.DecodeString(child.Data.Bytes())
case MatchingRuleAssertionDNAttributes:
dnAttributes = child.Value.(bool)
}
}
if len(attr) > 0 {
buf.WriteString(attr)
}
if dnAttributes {
buf.WriteString(":dn")
}
if len(matchingRule) > 0 {
buf.WriteString(":")
buf.WriteString(matchingRule)
}
buf.WriteString(":=")
buf.WriteString(EscapeFilter(value))
}
buf.WriteByte(')')
return buf.String(), nil
}
func compileFilterSet(filter string, pos int, parent *ber.Packet) (int, error) {
for pos < len(filter) && filter[pos] == '(' {
child, newPos, err := compileFilter(filter, pos+1)
if err != nil {
return pos, err
}
pos = newPos
parent.AppendChild(child)
}
if pos == len(filter) {
return pos, NewError(ErrorFilterCompile, errors.New("ldap: unexpected end of filter"))
}
return pos + 1, nil
}
func compileFilter(filter string, pos int) (*ber.Packet, int, error) {
var (
packet *ber.Packet
err error
)
defer func() {
if r := recover(); r != nil {
err = NewError(ErrorFilterCompile, errors.New("ldap: error compiling filter"))
}
}()
newPos := pos
currentRune, currentWidth := utf8.DecodeRuneInString(filter[newPos:])
switch currentRune {
case utf8.RuneError:
return nil, 0, NewError(ErrorFilterCompile, fmt.Errorf("ldap: error reading rune at position %d", newPos))
case '(':
packet, newPos, err = compileFilter(filter, pos+currentWidth)
newPos++
return packet, newPos, err
case '&':
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterAnd, nil, FilterMap[FilterAnd])
newPos, err = compileFilterSet(filter, pos+currentWidth, packet)
return packet, newPos, err
case '|':
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterOr, nil, FilterMap[FilterOr])
newPos, err = compileFilterSet(filter, pos+currentWidth, packet)
return packet, newPos, err
case '!':
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterNot, nil, FilterMap[FilterNot])
var child *ber.Packet
child, newPos, err = compileFilter(filter, pos+currentWidth)
packet.AppendChild(child)
return packet, newPos, err
default:
const (
stateReadingAttr = 0
stateReadingExtensibleMatchingRule = 1
stateReadingCondition = 2
)
state := stateReadingAttr
attribute := bytes.NewBuffer(nil)
extensibleDNAttributes := false
extensibleMatchingRule := bytes.NewBuffer(nil)
condition := bytes.NewBuffer(nil)
for newPos < len(filter) {
remainingFilter := filter[newPos:]
currentRune, currentWidth = utf8.DecodeRuneInString(remainingFilter)
if currentRune == ')' {
break
}
if currentRune == utf8.RuneError {
return packet, newPos, NewError(ErrorFilterCompile, fmt.Errorf("ldap: error reading rune at position %d", newPos))
}
switch state {
case stateReadingAttr:
switch {
// Extensible rule, with only DN-matching
case currentRune == ':' && strings.HasPrefix(remainingFilter, ":dn:="):
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterExtensibleMatch, nil, FilterMap[FilterExtensibleMatch])
extensibleDNAttributes = true
state = stateReadingCondition
newPos += 5
// Extensible rule, with DN-matching and a matching OID
case currentRune == ':' && strings.HasPrefix(remainingFilter, ":dn:"):
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterExtensibleMatch, nil, FilterMap[FilterExtensibleMatch])
extensibleDNAttributes = true
state = stateReadingExtensibleMatchingRule
newPos += 4
// Extensible rule, with attr only
case currentRune == ':' && strings.HasPrefix(remainingFilter, ":="):
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterExtensibleMatch, nil, FilterMap[FilterExtensibleMatch])
state = stateReadingCondition
newPos += 2
// Extensible rule, with no DN attribute matching
case currentRune == ':':
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterExtensibleMatch, nil, FilterMap[FilterExtensibleMatch])
state = stateReadingExtensibleMatchingRule
newPos++
// Equality condition
case currentRune == '=':
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterEqualityMatch, nil, FilterMap[FilterEqualityMatch])
state = stateReadingCondition
newPos++
// Greater-than or equal
case currentRune == '>' && strings.HasPrefix(remainingFilter, ">="):
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterGreaterOrEqual, nil, FilterMap[FilterGreaterOrEqual])
state = stateReadingCondition
newPos += 2
// Less-than or equal
case currentRune == '<' && strings.HasPrefix(remainingFilter, "<="):
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterLessOrEqual, nil, FilterMap[FilterLessOrEqual])
state = stateReadingCondition
newPos += 2
// Approx
case currentRune == '~' && strings.HasPrefix(remainingFilter, "~="):
packet = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterApproxMatch, nil, FilterMap[FilterApproxMatch])
state = stateReadingCondition
newPos += 2
// Still reading the attribute name
default:
attribute.WriteRune(currentRune)
newPos += currentWidth
}
case stateReadingExtensibleMatchingRule:
switch {
// Matching rule OID is done
case currentRune == ':' && strings.HasPrefix(remainingFilter, ":="):
state = stateReadingCondition
newPos += 2
// Still reading the matching rule oid
default:
extensibleMatchingRule.WriteRune(currentRune)
newPos += currentWidth
}
case stateReadingCondition:
// append to the condition
condition.WriteRune(currentRune)
newPos += currentWidth
}
}
if newPos == len(filter) {
err = NewError(ErrorFilterCompile, errors.New("ldap: unexpected end of filter"))
return packet, newPos, err
}
if packet == nil {
err = NewError(ErrorFilterCompile, errors.New("ldap: error parsing filter"))
return packet, newPos, err
}
switch {
case packet.Tag == FilterExtensibleMatch:
// MatchingRuleAssertion ::= SEQUENCE {
// matchingRule [1] MatchingRuleID OPTIONAL,
// type [2] AttributeDescription OPTIONAL,
// matchValue [3] AssertionValue,
// dnAttributes [4] BOOLEAN DEFAULT FALSE
// }
// Include the matching rule oid, if specified
if extensibleMatchingRule.Len() > 0 {
packet.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, MatchingRuleAssertionMatchingRule, extensibleMatchingRule.String(), MatchingRuleAssertionMap[MatchingRuleAssertionMatchingRule]))
}
// Include the attribute, if specified
if attribute.Len() > 0 {
packet.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, MatchingRuleAssertionType, attribute.String(), MatchingRuleAssertionMap[MatchingRuleAssertionType]))
}
// Add the value (only required child)
encodedString, encodeErr := decodeEscapedSymbols(condition.Bytes())
if encodeErr != nil {
return packet, newPos, encodeErr
}
packet.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, MatchingRuleAssertionMatchValue, encodedString, MatchingRuleAssertionMap[MatchingRuleAssertionMatchValue]))
// Defaults to false, so only include in the sequence if true
if extensibleDNAttributes {
packet.AppendChild(ber.NewBoolean(ber.ClassContext, ber.TypePrimitive, MatchingRuleAssertionDNAttributes, extensibleDNAttributes, MatchingRuleAssertionMap[MatchingRuleAssertionDNAttributes]))
}
case packet.Tag == FilterEqualityMatch && bytes.Equal(condition.Bytes(), _SymbolAny):
packet = ber.NewString(ber.ClassContext, ber.TypePrimitive, FilterPresent, attribute.String(), FilterMap[FilterPresent])
case packet.Tag == FilterEqualityMatch && bytes.Index(condition.Bytes(), _SymbolAny) > -1:
packet.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, attribute.String(), "Attribute"))
packet.Tag = FilterSubstrings
packet.Description = FilterMap[uint64(packet.Tag)]
seq := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "Substrings")
parts := bytes.Split(condition.Bytes(), _SymbolAny)
for i, part := range parts {
if len(part) == 0 {
continue
}
var tag ber.Tag
switch i {
case 0:
tag = FilterSubstringsInitial
case len(parts) - 1:
tag = FilterSubstringsFinal
default:
tag = FilterSubstringsAny
}
encodedString, encodeErr := decodeEscapedSymbols(part)
if encodeErr != nil {
return packet, newPos, encodeErr
}
seq.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, tag, encodedString, FilterSubstringsMap[uint64(tag)]))
}
packet.AppendChild(seq)
default:
encodedString, encodeErr := decodeEscapedSymbols(condition.Bytes())
if encodeErr != nil {
return packet, newPos, encodeErr
}
packet.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, attribute.String(), "Attribute"))
packet.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, encodedString, "Condition"))
}
newPos += currentWidth
return packet, newPos, err
}
}
// Convert from "ABC\xx\xx\xx" form to literal bytes for transport
func decodeEscapedSymbols(src []byte) (string, error) {
var (
buffer bytes.Buffer
offset int
reader = bytes.NewReader(src)
byteHex []byte
byteVal []byte
)
for {
runeVal, runeSize, err := reader.ReadRune()
if err == io.EOF {
return buffer.String(), nil
} else if err != nil {
return "", NewError(ErrorFilterCompile, fmt.Errorf("ldap: failed to read filter: %v", err))
} else if runeVal == unicode.ReplacementChar {
return "", NewError(ErrorFilterCompile, fmt.Errorf("ldap: error reading rune at position %d", offset))
}
if runeVal == '\\' {
// http://tools.ietf.org/search/rfc4515
// \ (%x5C) is not a valid character unless it is followed by two HEX characters due to not
// being a member of UTF1SUBSET.
if byteHex == nil {
byteHex = make([]byte, 2)
byteVal = make([]byte, 1)
}
if _, err := io.ReadFull(reader, byteHex); err != nil {
if err == io.ErrUnexpectedEOF {
return "", NewError(ErrorFilterCompile, errors.New("ldap: missing characters for escape in filter"))
}
return "", NewError(ErrorFilterCompile, fmt.Errorf("ldap: invalid characters for escape in filter: %v", err))
}
if _, err := hexpac.Decode(byteVal, byteHex); err != nil {
return "", NewError(ErrorFilterCompile, fmt.Errorf("ldap: invalid characters for escape in filter: %v", err))
}
buffer.Write(byteVal)
} else {
buffer.WriteRune(runeVal)
}
offset += runeSize
}
}