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// Copyright 2011 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 a filter compiler/decompiler
package ldap
import (
"errors"
"fmt"
"github.com/tmfkams/asn1-ber"
)
const (
FilterAnd = 0
FilterOr = 1
FilterNot = 2
FilterEqualityMatch = 3
FilterSubstrings = 4
FilterGreaterOrEqual = 5
FilterLessOrEqual = 6
FilterPresent = 7
FilterApproxMatch = 8
FilterExtensibleMatch = 9
)
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",
}
const (
FilterSubstringsInitial = 0
FilterSubstringsAny = 1
FilterSubstringsFinal = 2
)
var FilterSubstringsMap = map[uint64]string{
FilterSubstringsInitial: "Substrings Initial",
FilterSubstringsAny: "Substrings Any",
FilterSubstringsFinal: "Substrings Final",
}
func CompileFilter(filter string) (*ber.Packet, *Error) {
if len(filter) == 0 || filter[0] != '(' {
return nil, NewError(ErrorFilterCompile, errors.New("Filter does not start with an '('"))
}
packet, pos, err := compileFilter(filter, 1)
if err != nil {
return nil, err
}
if pos != len(filter) {
return nil, NewError(ErrorFilterCompile, errors.New("Finished compiling filter with extra at end.\n"+fmt.Sprint(filter[pos:])))
}
return packet, nil
}
func DecompileFilter(packet *ber.Packet) (ret string, err *Error) {
defer func() {
if r := recover(); r != nil {
err = NewError(ErrorFilterDecompile, errors.New("Error decompiling filter"))
}
}()
ret = "("
err = nil
child_str := ""
switch packet.Tag {
case FilterAnd:
ret += "&"
for _, child := range packet.Children {
child_str, err = DecompileFilter(child)
if err != nil {
return
}
ret += child_str
}
case FilterOr:
ret += "|"
for _, child := range packet.Children {
child_str, err = DecompileFilter(child)
if err != nil {
return
}
ret += child_str
}
case FilterNot:
ret += "!"
child_str, err = DecompileFilter(packet.Children[0])
if err != nil {
return
}
ret += child_str
case FilterSubstrings:
ret += ber.DecodeString(packet.Children[0].Data.Bytes())
ret += "="
switch packet.Children[1].Children[0].Tag {
case FilterSubstringsInitial:
ret += ber.DecodeString(packet.Children[1].Children[0].Data.Bytes()) + "*"
case FilterSubstringsAny:
ret += "*" + ber.DecodeString(packet.Children[1].Children[0].Data.Bytes()) + "*"
case FilterSubstringsFinal:
ret += "*" + ber.DecodeString(packet.Children[1].Children[0].Data.Bytes())
}
case FilterEqualityMatch:
ret += ber.DecodeString(packet.Children[0].Data.Bytes())
ret += "="
ret += ber.DecodeString(packet.Children[1].Data.Bytes())
case FilterGreaterOrEqual:
ret += ber.DecodeString(packet.Children[0].Data.Bytes())
ret += ">="
ret += ber.DecodeString(packet.Children[1].Data.Bytes())
case FilterLessOrEqual:
ret += ber.DecodeString(packet.Children[0].Data.Bytes())
ret += "<="
ret += ber.DecodeString(packet.Children[1].Data.Bytes())
case FilterPresent:
ret += ber.DecodeString(packet.Children[0].Data.Bytes())
ret += "=*"
case FilterApproxMatch:
ret += ber.DecodeString(packet.Children[0].Data.Bytes())
ret += "~="
ret += ber.DecodeString(packet.Children[1].Data.Bytes())
}
ret += ")"
return
}
func compileFilterSet(filter string, pos int, parent *ber.Packet) (int, *Error) {
for pos < len(filter) && filter[pos] == '(' {
child, new_pos, err := compileFilter(filter, pos+1)
if err != nil {
return pos, err
}
pos = new_pos
parent.AppendChild(child)
}
if pos == len(filter) {
return pos, NewError(ErrorFilterCompile, errors.New("Unexpected end of filter"))
}
return pos + 1, nil
}
func compileFilter(filter string, pos int) (p *ber.Packet, new_pos int, err *Error) {
defer func() {
if r := recover(); r != nil {
err = NewError(ErrorFilterCompile, errors.New("Error compiling filter"))
}
}()
p = nil
new_pos = pos
err = nil
switch filter[pos] {
case '(':
p, new_pos, err = compileFilter(filter, pos+1)
new_pos++
return
case '&':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterAnd, nil, FilterMap[FilterAnd])
new_pos, err = compileFilterSet(filter, pos+1, p)
return
case '|':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterOr, nil, FilterMap[FilterOr])
new_pos, err = compileFilterSet(filter, pos+1, p)
return
case '!':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterNot, nil, FilterMap[FilterNot])
var child *ber.Packet
child, new_pos, err = compileFilter(filter, pos+1)
p.AppendChild(child)
return
default:
attribute := ""
condition := ""
for new_pos < len(filter) && filter[new_pos] != ')' {
switch {
case p != nil:
condition += fmt.Sprintf("%c", filter[new_pos])
case filter[new_pos] == '=':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterEqualityMatch, nil, FilterMap[FilterEqualityMatch])
case filter[new_pos] == '>' && filter[new_pos+1] == '=':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterGreaterOrEqual, nil, FilterMap[FilterGreaterOrEqual])
new_pos++
case filter[new_pos] == '<' && filter[new_pos+1] == '=':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterLessOrEqual, nil, FilterMap[FilterLessOrEqual])
new_pos++
case filter[new_pos] == '~' && filter[new_pos+1] == '=':
p = ber.Encode(ber.ClassContext, ber.TypeConstructed, FilterApproxMatch, nil, FilterMap[FilterLessOrEqual])
new_pos++
case p == nil:
attribute += fmt.Sprintf("%c", filter[new_pos])
}
new_pos++
}
if new_pos == len(filter) {
err = NewError(ErrorFilterCompile, errors.New("Unexpected end of filter"))
return
}
if p == nil {
err = NewError(ErrorFilterCompile, errors.New("Error parsing filter"))
return
}
p.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimative, ber.TagOctetString, attribute, "Attribute"))
switch {
case p.Tag == FilterEqualityMatch && condition == "*":
p.Tag = FilterPresent
p.Description = FilterMap[uint64(p.Tag)]
case p.Tag == FilterEqualityMatch && condition[0] == '*' && condition[len(condition)-1] == '*':
// Any
p.Tag = FilterSubstrings
p.Description = FilterMap[uint64(p.Tag)]
seq := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "Substrings")
seq.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimative, FilterSubstringsAny, condition[1:len(condition)-1], "Any Substring"))
p.AppendChild(seq)
case p.Tag == FilterEqualityMatch && condition[0] == '*':
// Final
p.Tag = FilterSubstrings
p.Description = FilterMap[uint64(p.Tag)]
seq := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "Substrings")
seq.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimative, FilterSubstringsFinal, condition[1:], "Final Substring"))
p.AppendChild(seq)
case p.Tag == FilterEqualityMatch && condition[len(condition)-1] == '*':
// Initial
p.Tag = FilterSubstrings
p.Description = FilterMap[uint64(p.Tag)]
seq := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "Substrings")
seq.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimative, FilterSubstringsInitial, condition[:len(condition)-1], "Initial Substring"))
p.AppendChild(seq)
default:
p.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimative, ber.TagOctetString, condition, "Condition"))
}
new_pos++
return
}
err = NewError(ErrorFilterCompile, errors.New("Reached end of filter without closing parens"))
return
}
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