draft-ietf-dnsop-extended-error-10.txt   draft-ietf-dnsop-extended-error-11.txt 
Network Working Group W. Kumari Network Working Group W. Kumari
Internet-Draft Google Internet-Draft Google
Intended status: Standards Track E. Hunt Intended status: Standards Track E. Hunt
Expires: March 30, 2020 ISC Expires: April 2, 2020 ISC
R. Arends R. Arends
ICANN ICANN
W. Hardaker W. Hardaker
USC/ISI USC/ISI
D. Lawrence D. Lawrence
Oracle + Dyn Oracle + Dyn
September 27, 2019 September 30, 2019
Extended DNS Errors Extended DNS Errors
draft-ietf-dnsop-extended-error-10 draft-ietf-dnsop-extended-error-11
Abstract Abstract
This document defines an extensible method to return additional This document defines an extensible method to return additional
information about the cause of DNS errors. Though created primarily information about the cause of DNS errors. Though created primarily
to extend SERVFAIL to provide additional information about the cause to extend SERVFAIL to provide additional information about the cause
of DNS and DNSSEC failures, the Extended DNS Errors option defined in of DNS and DNSSEC failures, the Extended DNS Errors option defined in
this document allows all response types to contain extended error this document allows all response types to contain extended error
information. Extended DNS Error information does not change the information. Extended DNS Error information does not change the
processing of RCODEs. processing of RCODEs.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 30, 2020. This Internet-Draft will expire on April 2, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 5 3.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 5
3.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 5 3.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 5
3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6 3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6
3.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6 3.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6
3.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6 3.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6
3.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6 3.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6
3.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 6 3.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 6
3.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 6 3.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 6
3.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 6 3.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 6
3.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 6 3.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 6
3.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 6 3.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 7
3.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7 3.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7
3.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7 3.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7
3.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7 3.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7
3.18. Extended DNS Error Code 17 - Filtered . . . . . . . . . . 7 3.18. Extended DNS Error Code 17 - Filtered . . . . . . . . . . 7
3.19. Extended DNS Error Code 17 - Prohibited . . . . . . . . . 7 3.19. Extended DNS Error Code 18 - Prohibited . . . . . . . . . 7
3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 7 3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 7
3.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 7 3.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 8
3.22. Extended DNS Error Code 21 - Deprecated . . . . . . . . . 8 3.22. Extended DNS Error Code 21 - Not Supported . . . . . . . 8
3.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8 3.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8
3.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8 3.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8
3.25. Extended DNS Error Code 24 - Invalid Data . . . . . . . . 8 3.25. Extended DNS Error Code 24 - Invalid Data . . . . . . . . 8
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
4.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 8 4.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 8
4.2. New Registry Table for Extended DNS Error Codes . . . . . 8 4.2. New Registry Table for Extended DNS Error Codes . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . 12
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There are many reasons that a DNS query may fail, some of them There are many reasons that a DNS query may fail, some of them
transient, some permanent; some can be resolved by querying another transient, some permanent; some can be resolved by querying another
server, some are likely best handled by stopping resolution. server, some are likely best handled by stopping resolution.
Unfortunately, the error signals that a DNS server can return are Unfortunately, the error signals that a DNS server can return are
very limited, and are not very expressive. This means that very limited, and are not very expressive. This means that
applications and resolvers often have to "guess" at what the issue is applications and resolvers often have to "guess" at what the issue is
- e.g. was the answer marked REFUSED because of a lame delegation, or - e.g. was the answer marked REFUSED because of a lame delegation, or
because the nameserver is still starting up and loading zones? Is a because the nameserver is still starting up and loading zones? Is a
SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing
some other failure? some other failure? What error messages should be presented to the
user or logged under these conditions?
A good example of issues that would benefit by additional error A good example of issues that would benefit by additional error
information are errors caused by DNSSEC validation issues. When a information are errors caused by DNSSEC validation issues. When a
stub resolver queries a name which is DNSSEC bogus (using a stub resolver queries a name which is DNSSEC bogus (using a
validating resolver), the stub resolver receives only a SERVFAIL in validating resolver), the stub resolver receives only a SERVFAIL in
response. Unfortunately, the SERVFAIL Response Code (RCODE) is used response. Unfortunately, the SERVFAIL Response Code (RCODE) is used
to signal many sorts of DNS errors, and so the stub resolvers only to signal many sorts of DNS errors, and so the stub resolvers only
option is to ask the next configured DNS resolver. The result of option is to ask the next configured DNS resolver. The result of
trying the next resolver is one of two outcomes: either the next trying the next resolver is one of two outcomes: either the next
resolver also validates, and a SERVFAIL is returned again or the next resolver also validates, and a SERVFAIL is returned again or the next
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and thus different systems (stub resolvers, recursive resolvers, and and thus different systems (stub resolvers, recursive resolvers, and
authoritative resolvers) might receive and use them. authoritative resolvers) might receive and use them.
This document does not allow or prohibit any particular extended This document does not allow or prohibit any particular extended
error codes and information to be matched with any particular RCODEs. error codes and information to be matched with any particular RCODEs.
Some combinations of extended error codes and RCODEs may seem Some combinations of extended error codes and RCODEs may seem
nonsensical (such as resolver-specific extended error codes in nonsensical (such as resolver-specific extended error codes in
responses from authoritative servers), so systems interpreting the responses from authoritative servers), so systems interpreting the
extended error codes MUST NOT assume that a combination will make extended error codes MUST NOT assume that a combination will make
sense. Receivers MUST be able to accept EDE codes and EXTRA-TEXT in sense. Receivers MUST be able to accept EDE codes and EXTRA-TEXT in
all messages, including those with a NOERROR RCODE. Receivers MUST all messages, including those with a NOERROR RCODE. Applications
NOT change the processing of RCODEs in messages based on extended MUST continue to follow requirements from applicable specs on how to
error codes. process RCODEs no matter what EDE values is also received
1.1. Requirements notation 1.1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Extended Error EDNS0 option format 2. Extended Error EDNS0 option format
This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS
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+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
2: | OPTION-LENGTH | 2: | OPTION-LENGTH |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
4: | INFO-CODE | 4: | INFO-CODE |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
6: / EXTRA-TEXT ... / 6: / EXTRA-TEXT ... /
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Field definition details: Field definition details:
o OPTION-CODE, 2 octets (defined in [RFC6891]]), for EDE is TBD. o OPTION-CODE, 2-octets/16-bits (defined in [RFC6891]]), for EDE is
[RFC Editor: change TBD to the proper code once assigned by IANA.] TBD. [RFC Editor: change TBD to the proper code once assigned by
o OPTION-LENGTH, 2 octets ((defined in [RFC6891]]) contains the IANA.]
length of the payload (everything after OPTION-LENGTH) in octets o OPTION-LENGTH, 2-octets/16-bits ((defined in [RFC6891]]) contains
and should be 4 plus the length of the EXTRA-TEXT section (which the length of the payload (everything after OPTION-LENGTH) in
may be a zero-length string). octets and should be 4 plus the length of the EXTRA-TEXT section
(which may be a zero-length string).
o INFO-CODE, 16-bits, which is the principal contribution of this o INFO-CODE, 16-bits, which is the principal contribution of this
document. This 16-bit value, encoded in network (MSB) byte order, document. This 16-bit value, encoded in network (MSB) byte order,
provides the additional context for the RESPONSE-CODE of the DNS provides the additional context for the RESPONSE-CODE of the DNS
message. The INFO-CODE serves as an index into the "Extended DNS message. The INFO-CODE serves as an index into the "Extended DNS
Errors" registry Section 4.1. Errors" registry Section 4.1.
o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may
hold additional textual information. Note: EXTRA-TEXT may be zero hold additional textual information. Note: EXTRA-TEXT may be zero
octets in length, indicating there is no EXTRA-TEXT included. octets in length, indicating there is no EXTRA-TEXT included.
Care should be taken not to leak private information that an Care should be taken not to leak private information that an
observer would not otherwise have access to, such as account observer would not otherwise have access to, such as account
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The resolver attempted to perform DNSSEC validation, but validation The resolver attempted to perform DNSSEC validation, but validation
ended in the Indeterminate state [RFC4035]. ended in the Indeterminate state [RFC4035].
3.7. Extended DNS Error Code 6 - DNSSEC Bogus 3.7. Extended DNS Error Code 6 - DNSSEC Bogus
The resolver attempted to perform DNSSEC validation, but validation The resolver attempted to perform DNSSEC validation, but validation
ended in the Bogus state. ended in the Bogus state.
3.8. Extended DNS Error Code 7 - Signature Expired 3.8. Extended DNS Error Code 7 - Signature Expired
The resolver attempted to perform DNSSEC validation, but all The resolver attempted to perform DNSSEC validation, but no
signatures in an RRset in the validation chain were expired. signatures are presently valid and some (often all) are expired.
3.9. Extended DNS Error Code 8 - Signature Not Yet Valid 3.9. Extended DNS Error Code 8 - Signature Not Yet Valid
The resolver attempted to perform DNSSEC validation, but all the The resolver attempted to perform DNSSEC validation, but but no
signatures received were not yet valid. signatures are presently valid and at least some are not yet valid.
3.10. Extended DNS Error Code 9 - DNSKEY Missing 3.10. Extended DNS Error Code 9 - DNSKEY Missing
A DS record existed at a parent, but no supported matching DNSKEY A DS record existed at a parent, but no supported matching DNSKEY
record could be found for the child. record could be found for the child.
3.11. Extended DNS Error Code 10 - RRSIGs Missing 3.11. Extended DNS Error Code 10 - RRSIGs Missing
The resolver attempted to perform DNSSEC validation, but no RRSIGs The resolver attempted to perform DNSSEC validation, but no RRSIGs
could be found for at least one RRset where RRSIGs were expected. could be found for at least one RRset where RRSIGs were expected.
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Bit was set in a DNSKEY. Bit was set in a DNSKEY.
3.13. Extended DNS Error Code 12 - NSEC Missing 3.13. Extended DNS Error Code 12 - NSEC Missing
The resolver attempted to perform DNSSEC validation, but the The resolver attempted to perform DNSSEC validation, but the
requested data was missing and a covering NSEC or NSEC3 was not requested data was missing and a covering NSEC or NSEC3 was not
provided. provided.
3.14. Extended DNS Error Code 13 - Cached Error 3.14. Extended DNS Error Code 13 - Cached Error
The resolver has Cached SERVFAIL for this query. The resolver is returning the SERVFAIL RCODE from its cache.
3.15. Extended DNS Error Code 14 - Not Ready 3.15. Extended DNS Error Code 14 - Not Ready
The server is unable to answer the query as it is not fully The server is unable to answer the query as it is not fully
functional (yet). functional (yet).
3.16. Extended DNS Error Code 15 - Blocked 3.16. Extended DNS Error Code 15 - Blocked
The server is unable to respond to the request because the domain is The server is unable to respond to the request because the domain is
blacklisted due to an internal security policy imposed by the blacklisted due to an internal security policy imposed by the
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blacklisted by a security policy imposed upon the server being talked blacklisted by a security policy imposed upon the server being talked
to by an external requirement. Note that how the imposed policy is to by an external requirement. Note that how the imposed policy is
applied is irrelevant (in-band DNS filtering, court order, etc). applied is irrelevant (in-band DNS filtering, court order, etc).
3.18. Extended DNS Error Code 17 - Filtered 3.18. Extended DNS Error Code 17 - Filtered
The server is unable to respond to the request because the domain is The server is unable to respond to the request because the domain is
blacklisted as requested by the client. Functionally, this amounts blacklisted as requested by the client. Functionally, this amounts
to "you requested that we filter domains like this one." to "you requested that we filter domains like this one."
3.19. Extended DNS Error Code 17 - Prohibited 3.19. Extended DNS Error Code 18 - Prohibited
An authoritative or recursive resolver that receives a query from an An authoritative or recursive resolver that receives a query from an
"unauthorized" client can annotate its REFUSED message with this "unauthorized" client can annotate its REFUSED message with this
code. Examples of "unauthorized" clients are recursive queries from code. Examples of "unauthorized" clients are recursive queries from
IP addresses outside the network, blacklisted IP addresses, local IP addresses outside the network, blacklisted IP addresses, local
policy, etc. policy, etc.
3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer 3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer
The resolver was unable to resolve an answer within its configured The resolver was unable to resolve an answer within its configured
time limits and decided to answer with a previously cached NXDOMAIN time limits and decided to answer with a previously cached NXDOMAIN
answer instead of answering with an error. This is typically caused answer instead of answering with an error. This is may be caused,
by problems communicating with an authoritative server, possibly as for example, by problems communicating with an authoritative server,
result of a DoS attack against another network. possibly as result of a DoS attack against another network.
3.21. Extended DNS Error Code 20 - Not Authoritative 3.21. Extended DNS Error Code 20 - Not Authoritative
An authoritative server that receives a query (with the RD bit clear, An authoritative server that receives a query (with the RD bit clear,
or when not configured for recursion) for a domain for which it is or when not configured for recursion) for a domain for which it is
not authoritative SHOULD include this EDE code in the REFUSED not authoritative SHOULD include this EDE code in the REFUSED
response. A resolver that receives a query (with the RD bit clear) response. A resolver that receives a query (with the RD bit clear)
SHOULD include this EDE code in the REFUSED response. SHOULD include this EDE code in the REFUSED response.
3.22. Extended DNS Error Code 21 - Deprecated 3.22. Extended DNS Error Code 21 - Not Supported
The requested operation or query is not supported as its use has been The requested operation or query is not supported as its use has been
deprecated. deprecated.
3.23. Extended DNS Error Code 22 - No Reachable Authority 3.23. Extended DNS Error Code 22 - No Reachable Authority
The resolver could not reach any of the authoritative name servers The resolver could not reach any of the authoritative name servers
(or they refused to reply). (or they refused to reply).
3.24. Extended DNS Error Code 23 - Network Error 3.24. Extended DNS Error Code 23 - Network Error
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INFO-CODE: 19 INFO-CODE: 19
Purpose: Stale NXDomain Answer Purpose: Stale NXDomain Answer
Reference: Section 3.20 Reference: Section 3.20
INFO-CODE: 20 INFO-CODE: 20
Purpose: Not Authoritative Purpose: Not Authoritative
Reference: Section 3.21 Reference: Section 3.21
INFO-CODE: 21 INFO-CODE: 21
Purpose: Deprecated Purpose: Not Supported
Reference: Section 3.22 Reference: Section 3.22
INFO-CODE: 22 INFO-CODE: 22
Purpose: No Reachable Authority Purpose: No Reachable Authority
Reference: Section 3.23 Reference: Section 3.23
INFO-CODE: 23 INFO-CODE: 23
Purpose: Network Error Purpose: Network Error
Reference: Section 3.24 Reference: Section 3.24
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would not trust any unauthenticated information, but until we live in would not trust any unauthenticated information, but until we live in
an era where all DNS answers are authenticated via DNSSEC or other an era where all DNS answers are authenticated via DNSSEC or other
mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an
example, an attacker who is able to insert the DNSSEC Bogus Extended example, an attacker who is able to insert the DNSSEC Bogus Extended
Error into a packet could instead simply reply with a fictitious Error into a packet could instead simply reply with a fictitious
address (A or AAAA) record. Note that DNS Response Codes also address (A or AAAA) record. Note that DNS Response Codes also
contain no authentication and can be just as easily manipulated. contain no authentication and can be just as easily manipulated.
6. Acknowledgements 6. Acknowledgements
The authors wish to thank Joe Abley, Mark Andrews, Vittorio Bertola, The authors wish to thank Joe Abley, Mark Andrews, Tim April,
Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans, Peter DeVries, Vittorio Bertola, Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans,
Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob Harold, Paul Peter DeVries, Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob
Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos M. Martinez, Harold, Paul Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos
George Michelson, Eric Orth, Michael Sheldon, Puneet Sood, Petr M. Martinez, George Michelson, Eric Orth, Michael Sheldon, Puneet
Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and Paul Vixie. Sood, Petr Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and
They also vaguely remember discussing this with a number of people Paul Vixie. They also vaguely remember discussing this with a number
over the years, but have forgotten who all they were -- if you were of people over the years, but have forgotten who all they were -- if
one of them, and are not listed, please let us know and we'll you were one of them, and are not listed, please let us know and
acknowledge you. we'll acknowledge you.
One author also wants to thank the band "Infected Mushroom" for One author also wants to thank the band "Infected Mushroom" for
providing a good background soundtrack (and to see if he can get away providing a good background soundtrack (and to see if he can get away
with this in an RFC!) Another author would like to thank the band with this in an RFC!) Another author would like to thank the band
"Mushroom Infectors". This was funny at the time we wrote it, but we "Mushroom Infectors". This was funny at the time we wrote it, but we
cannot remember why... cannot remember why...
7. References 7. References
7.1. Normative References 7.1. Normative References
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