--- 1/draft-ietf-cbor-network-addresses-02.txt 2021-03-25 17:13:12.306652142 -0700 +++ 2/draft-ietf-cbor-network-addresses-03.txt 2021-03-25 17:13:12.322652542 -0700 @@ -1,18 +1,18 @@ CBOR Working Group M. Richardson Internet-Draft Sandelman Software Works -Intended status: Standards Track 9 March 2021 -Expires: 10 September 2021 +Intended status: Standards Track 25 March 2021 +Expires: 26 September 2021 CBOR tags for IPv4 and IPv6 addresses and prefixes - draft-ietf-cbor-network-addresses-02 + draft-ietf-cbor-network-addresses-03 Abstract This document describes two CBOR Tags to be used with IPv4 and IPv6 addresses and prefixes. RFC-EDITOR-please remove: This work is tracked at https://github.com/mcr/cbor-network-address.git Status of This Memo @@ -23,21 +23,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on 10 September 2021. + This Internet-Draft will expire on 26 September 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights @@ -48,24 +48,24 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3.1. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3.2. IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Encoder Consideration for prefixes . . . . . . . . . . . . . 3 5. Decoder Considerations for prefixes . . . . . . . . . . . . . 4 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 - 7.1. TBD1 - IPv6 . . . . . . . . . . . . . . . . . . . . . . . 5 - 7.2. TBD2 - IPv4 . . . . . . . . . . . . . . . . . . . . . . . 5 + 7.1. Tag 54 - IPv6 . . . . . . . . . . . . . . . . . . . . . . 5 + 7.2. Tag 52 - IPv4 . . . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 9. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 5 10. Normative References . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction [RFC8949] defines a number of CBOR Tags for common items. Not included are ones to indicate if the item is an IPv4 or IPv6 @@ -84,97 +84,87 @@ These tags can applied to byte strings to represent a single address. When applied to an array, the represent a CIDR-style prefix. When a byte string (without prefix) appears in a context where a prefix is expected, then it is to be assumed that all bits are relevant. That is, for IPv4, a /32 is implied, and for IPv6, a /128 is implied. 3.1. IPv6 - IANA has allocated tag TBD1 for IPv6 uses. - + IANA has allocated tag 54 for IPv6 uses. (Note that this is the + ASCII code for '6') An IPv6 address is to be encoded as a sixteen-byte byte string - ([RFC8949] section, 3.1, major type 2), prefixed with tag TBD1. + ([RFC8949] section, 3.1, major type 2), prefixed with Tag(54). An IPv6 prefix, such as 2001:db8:1234::/48 is to be encoded as a two element array, with the length of the prefix first. Trailing zero octets MUST be omitted. For example: - TBD1([ 48, h'20010db81234']) + 54([ 48, h'20010db81234']) 3.2. IPv4 - IANA has allocated tag TBD2 for IPv4 uses. + IANA has allocated tag 54 for IPv4 uses. (Note that this is the + ASCII code for '4') An IPv4 address is to be encoded as a four-byte byte string - ([RFC8949] section, 3.1, major type 2), prefixed with tag TBD2. + ([RFC8949] section, 3.1, major type 2), prefixed with Tag(52). An IPv4 prefix, such as 192.0.2.1/24 is to be encoded as a two element array, with the length of the prefix first. Trailing zero octets MUST be omitted. For example: - TBD2([ 24, h'C00002']) + 52([ 24, h'C00002']) 4. Encoder Consideration for prefixes An encoder may omit as many right-hand (trailing) bytes which are all zero as it wishes. There is no relationship between the number of bytes omitted and the prefix length. For instance, the prefix 2001:db8::/64 is optimally encoded as: - TBD1([64, h'20010db8']) + 54([64, h'20010db8']) An encoder MUST take care to set all trailing bits to zero. While decoders are expected to ignore them, such garbage entities could be used as a covert channel, or may reveal the state of what would otherewise be private memory contents. So for example, 2001:db8:1230::/44 MUST be encoded as: - TBD1([44, h'20010db81230']) + 52([44, h'20010db81230']) even though variations like: - TBD1([44, h'20010db81233']) WRONG - TBD1([45, h'20010db8123f']) WRONG + 54([44, h'20010db81233']) WRONG + 54([45, h'20010db8123f']) WRONG would be parsed in the exact same way. The same considerations apply to IPv4 prefixes. 5. Decoder Considerations for prefixes A decoder MUST consider all bits to the right of the prefix length to be zero. A decoder MUST handle the case where a prefix length specifies that more bits are relevant than are actually present in the byte-string. As a pathological case, ::/128 can be encoded as - TBD1([0, h'']) - - (EDNOTE: do we want to support: - - [0] - - or - - [0, null] - - (EDNOTE: what if the array has more than 2 members? Is this a - convert channel, or is this a possible extension point?) + 54([128, h'']) A recommendation for implementation is to first create an array of 16 (or 4) bytes in size, set it all to zero. Then looking at the length of the included byte-string, and of the prefix-length, rounded up to the next multiple of 8, and taking whichever is smaller, copy that many bytes from the byte-string into the array. Finally, looking at the last three bits of the prefix-length (that @@ -202,26 +192,26 @@ of this encoding. Such abuse would be detected by examination of the raw protocol bytes. Users of this encoding should be aware of this possibility. 7. IANA Considerations IANA is asked to allocate two tags from the Specification Required area of the Concise Binary Object Representation (CBOR) Tags, in the ("1+1") area. -7.1. TBD1 - IPv6 +7.1. Tag 54 - IPv6 Data Item: byte string and array Semantics: IPv6 or [prefixlen,IPv6] -7.2. TBD2 - IPv4 +7.2. Tag 52 - IPv4 Data Item: byte string and array Semantics: IPv4 or [prefixlen,IPv4] 8. Acknowledgements none yet 9. Changelog