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author | Thomas Voss <mail@thomasvoss.com> | 2024-11-27 20:54:24 +0100 |
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committer | Thomas Voss <mail@thomasvoss.com> | 2024-11-27 20:54:24 +0100 |
commit | 4bfd864f10b68b71482b35c818559068ef8d5797 (patch) | |
tree | e3989f47a7994642eb325063d46e8f08ffa681dc /doc/rfc/rfc2254.txt | |
parent | ea76e11061bda059ae9f9ad130a9895cc85607db (diff) |
doc: Add RFC documents
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diff --git a/doc/rfc/rfc2254.txt b/doc/rfc/rfc2254.txt new file mode 100644 index 0000000..323fdb0 --- /dev/null +++ b/doc/rfc/rfc2254.txt @@ -0,0 +1,451 @@ + + + + + + +Network Working Group T. Howes +Request for Comments: 2254 Netscape Communications Corp. +Category: Standards Track December 1997 + + + The String Representation of LDAP Search Filters + +1. Status of this Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (1997). All Rights Reserved. + +IESG Note + + This document describes a directory access protocol that provides + both read and update access. Update access requires secure + authentication, but this document does not mandate implementation of + any satisfactory authentication mechanisms. + + In accordance with RFC 2026, section 4.4.1, this specification is + being approved by IESG as a Proposed Standard despite this + limitation, for the following reasons: + + a. to encourage implementation and interoperability testing of + these protocols (with or without update access) before they + are deployed, and + + b. to encourage deployment and use of these protocols in read-only + applications. (e.g. applications where LDAPv3 is used as + a query language for directories which are updated by some + secure mechanism other than LDAP), and + + c. to avoid delaying the advancement and deployment of other Internet + standards-track protocols which require the ability to query, but + not update, LDAPv3 directory servers. + + + + + + + + + +Howes Standards Track [Page 1] + +RFC 2254 String Representation of LDAP December 1997 + + + Readers are hereby warned that until mandatory authentication + mechanisms are standardized, clients and servers written according to + this specification which make use of update functionality are + UNLIKELY TO INTEROPERATE, or MAY INTEROPERATE ONLY IF AUTHENTICATION + IS REDUCED TO AN UNACCEPTABLY WEAK LEVEL. + + Implementors are hereby discouraged from deploying LDAPv3 clients or + servers which implement the update functionality, until a Proposed + Standard for mandatory authentication in LDAPv3 has been approved and + published as an RFC. + +2. Abstract + + The Lightweight Directory Access Protocol (LDAP) [1] defines a + network representation of a search filter transmitted to an LDAP + server. Some applications may find it useful to have a common way of + representing these search filters in a human-readable form. This + document defines a human-readable string format for representing LDAP + search filters. + + This document replaces RFC 1960, extending the string LDAP filter + definition to include support for LDAP version 3 extended match + filters, and including support for representing the full range of + possible LDAP search filters. + + + + + + + + + + + + + + + + + + + + + + + + + + + +Howes Standards Track [Page 2] + +RFC 2254 String Representation of LDAP December 1997 + + +3. LDAP Search Filter Definition + + An LDAPv3 search filter is defined in Section 4.5.1 of [1] as + follows: + + Filter ::= CHOICE { + and [0] SET OF Filter, + or [1] SET OF Filter, + not [2] Filter, + equalityMatch [3] AttributeValueAssertion, + substrings [4] SubstringFilter, + greaterOrEqual [5] AttributeValueAssertion, + lessOrEqual [6] AttributeValueAssertion, + present [7] AttributeDescription, + approxMatch [8] AttributeValueAssertion, + extensibleMatch [9] MatchingRuleAssertion + } + + SubstringFilter ::= SEQUENCE { + type AttributeDescription, + SEQUENCE OF CHOICE { + initial [0] LDAPString, + any [1] LDAPString, + final [2] LDAPString + } + } + + AttributeValueAssertion ::= SEQUENCE { + attributeDesc AttributeDescription, + attributeValue AttributeValue + } + + MatchingRuleAssertion ::= SEQUENCE { + matchingRule [1] MatchingRuleID OPTIONAL, + type [2] AttributeDescription OPTIONAL, + matchValue [3] AssertionValue, + dnAttributes [4] BOOLEAN DEFAULT FALSE + } + + AttributeDescription ::= LDAPString + + AttributeValue ::= OCTET STRING + + MatchingRuleID ::= LDAPString + + AssertionValue ::= OCTET STRING + + LDAPString ::= OCTET STRING + + + +Howes Standards Track [Page 3] + +RFC 2254 String Representation of LDAP December 1997 + + + where the LDAPString above is limited to the UTF-8 encoding of the + ISO 10646 character set [4]. The AttributeDescription is a string + representation of the attribute description and is defined in [1]. + The AttributeValue and AssertionValue OCTET STRING have the form + defined in [2]. The Filter is encoded for transmission over a + network using the Basic Encoding Rules defined in [3], with + simplifications described in [1]. + +4. String Search Filter Definition + + The string representation of an LDAP search filter is defined by the + following grammar, following the ABNF notation defined in [5]. The + filter format uses a prefix notation. + + filter = "(" filtercomp ")" + filtercomp = and / or / not / item + and = "&" filterlist + or = "|" filterlist + not = "!" filter + filterlist = 1*filter + item = simple / present / substring / extensible + simple = attr filtertype value + filtertype = equal / approx / greater / less + equal = "=" + approx = "~=" + greater = ">=" + less = "<=" + extensible = attr [":dn"] [":" matchingrule] ":=" value + / [":dn"] ":" matchingrule ":=" value + present = attr "=*" + substring = attr "=" [initial] any [final] + initial = value + any = "*" *(value "*") + final = value + attr = AttributeDescription from Section 4.1.5 of [1] + matchingrule = MatchingRuleId from Section 4.1.9 of [1] + value = AttributeValue from Section 4.1.6 of [1] + + The attr, matchingrule, and value constructs are as described in the + corresponding section of [1] given above. + + + + + + + + + + + +Howes Standards Track [Page 4] + +RFC 2254 String Representation of LDAP December 1997 + + + If a value should contain any of the following characters + + Character ASCII value + --------------------------- + * 0x2a + ( 0x28 + ) 0x29 + \ 0x5c + NUL 0x00 + + the character must be encoded as the backslash '\' character (ASCII + 0x5c) followed by the two hexadecimal digits representing the ASCII + value of the encoded character. The case of the two hexadecimal + digits is not significant. + + This simple escaping mechanism eliminates filter-parsing ambiguities + and allows any filter that can be represented in LDAP to be + represented as a NUL-terminated string. Other characters besides the + ones listed above may be escaped using this mechanism, for example, + non-printing characters. + + For example, the filter checking whether the "cn" attribute contained + a value with the character "*" anywhere in it would be represented as + "(cn=*\2a*)". + + Note that although both the substring and present productions in the + grammar above can produce the "attr=*" construct, this construct is + used only to denote a presence filter. + +5. Examples + + This section gives a few examples of search filters written using + this notation. + + (cn=Babs Jensen) + (!(cn=Tim Howes)) + (&(objectClass=Person)(|(sn=Jensen)(cn=Babs J*))) + (o=univ*of*mich*) + + The following examples illustrate the use of extensible matching. + + (cn:1.2.3.4.5:=Fred Flintstone) + (sn:dn:2.4.6.8.10:=Barney Rubble) + (o:dn:=Ace Industry) + (:dn:2.4.6.8.10:=Dino) + + + + + + +Howes Standards Track [Page 5] + +RFC 2254 String Representation of LDAP December 1997 + + + The second example illustrates the use of the ":dn" notation to + indicate that matching rule "2.4.6.8.10" should be used when making + comparisons, and that the attributes of an entry's distinguished name + should be considered part of the entry when evaluating the match. + + The third example denotes an equality match, except that DN + components should be considered part of the entry when doing the + match. + + The fourth example is a filter that should be applied to any + attribute supporting the matching rule given (since the attr has been + left off). Attributes supporting the matching rule contained in the + DN should also be considered. + + The following examples illustrate the use of the escaping mechanism. + + (o=Parens R Us \28for all your parenthetical needs\29) + (cn=*\2A*) + (filename=C:\5cMyFile) + (bin=\00\00\00\04) + (sn=Lu\c4\8di\c4\87) + + The first example shows the use of the escaping mechanism to + represent parenthesis characters. The second shows how to represent a + "*" in a value, preventing it from being interpreted as a substring + indicator. The third illustrates the escaping of the backslash + character. + + The fourth example shows a filter searching for the four-byte value + 0x00000004, illustrating the use of the escaping mechanism to + represent arbitrary data, including NUL characters. + + The final example illustrates the use of the escaping mechanism to + represent various non-ASCII UTF-8 characters. + +6. Security Considerations + + This memo describes a string representation of LDAP search filters. + While the representation itself has no known security implications, + LDAP search filters do. They are interpreted by LDAP servers to + select entries from which data is retrieved. LDAP servers should + take care to protect the data they maintain from unauthorized access. + + + + + + + + + +Howes Standards Track [Page 6] + +RFC 2254 String Representation of LDAP December 1997 + + +7. References + + [1] Wahl, M., Howes, T., and S. Kille, "Lightweight Directory Access + Protocol (v3)", RFC 2251, December 1997. + + [2] Wahl, M., Coulbeck, A., Howes, T., and S. Kille, "Lightweight + Directory Access Protocol (v3): Attribute Syntax Definitions", RFC + 2252, December 1997. + + [3] Specification of ASN.1 encoding rules: Basic, Canonical, and + Distinguished Encoding Rules, ITU-T Recommendation X.690, 1994. + + [4] Yergeau, F., "UTF-8, a transformation format of Unicode and ISO + 10646", RFC 2044, October 1996. + + [5] Crocker, D., "Standard for the Format of ARPA Internet Text + Messages", STD 11, RFC 822, August 1982. + +8. Author's Address + + Tim Howes + Netscape Communications Corp. + 501 E. Middlefield Road + Mountain View, CA 94043 + USA + + Phone: +1 415 937-3419 + EMail: howes@netscape.com + + + + + + + + + + + + + + + + + + + + + + + +Howes Standards Track [Page 7] + +RFC 2254 String Representation of LDAP December 1997 + + +9. Full Copyright Statement + + Copyright (C) The Internet Society (1997). All Rights Reserved. + + This document and translations of it may be copied and furnished to + others, and derivative works that comment on or otherwise explain it + or assist in its implementation may be prepared, copied, published + and distributed, in whole or in part, without restriction of any + kind, provided that the above copyright notice and this paragraph are + included on all such copies and derivative works. However, this + document itself may not be modified in any way, such as by removing + the copyright notice or references to the Internet Society or other + Internet organizations, except as needed for the purpose of + developing Internet standards in which case the procedures for + copyrights defined in the Internet Standards process must be + followed, or as required to translate it into languages other than + English. + + The limited permissions granted above are perpetual and will not be + revoked by the Internet Society or its successors or assigns. + + This document and the information contained herein is provided on an + "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING + BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION + HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF + MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + + + + + + + + + + + + + + + + + + + + + + + + +Howes Standards Track [Page 8] + |