INTERNET-DRAFT Charles H. Lindsey
Usenet Format Working Group University of Manchester
July 2001
5.6.2. Adding a path-identity to the Path header
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5.6.2. Adding a path-identity to the Path header
When an injecting, relaying or serving agent receives an article, it
MUST prepend its own path-identity followed by a delimiter to the
beginning of the Path-content. In addition, it SHOULD then add CRLF
and WSP if it would otherwise result in a line longer than 79
characters.
The path-identity added MUST be unique to that agent. To this end it
SHOULD be one of:
1. A fully qualified domain name (FQDN) associated (by the Internet
DNS service [RFC 1034]) with an A record, which SHOULD identify
the actual machine prepending this path-identity. Ideally, this
FQDN should also be "mailable" in the sense that it enables the
construction of a valid E-mail address of the form "usenet@"
or "news@" [RFC 2142] whereby the administrators of that
agent may be reached.
2. A fully qualified domain name (FQDN) associated (by the Internet
DNS service) with an MX record which MUST then enable the
construction of a valid E-mail address of the form "usenet@"
or "news@" whereby the administrators of that agent may be
reached.
3. An arbitrary name believed to be unique and registered at least
with all sites immediately downstream from the given site.
4. An encoding of an IP address - [RFC 820] or [RFC 2373] (the requirement to be able to use an is the reason for including ':' as an allowed character
within a path-identity).
Of the above options, nos. 1 to 3 are much to be preferred, unless
there are strong technical reasons dictating otherwise. In
particular, the injecting agent's path-identity MUST, as a special
case, be an FQDN mailable address in the sense defined under option
1, or with an associated MX record as in option 2.
The injecting agent's path-identity MUST be followed by the special
delimiter '%' which serves to separate the pre-injection and post-
injection regions of the Path-content (see 5.6.3).
In the case of a relaying or serving agent, the delimiter is chosen
as follows. When such an agent receives an article, it MUST
establish the identity of the source and compare it with the leftmost
path-identity of the Path-content. If it matches, a '/' should be
used as the delimiter when prepending the agent's own path-identity.
If it does not match then the agent should prepend two entries to the
Path-content; firstly the true established path-identity of the
source followed by a '?' delimiter, and then, to the left of that,
the agent's own path-identity followed by a '/' delimiter as usual.
This prepending of two entries SHOULD NOT be done if the provided and
established identities match.
Any method of establishing the identity of the source may be used
(but see 5.6.5 below), with the consideration that, in the event of
problems, the agent concerned may be called upon to justify it.
NOTE: The use of the '%' delimiter marks the position of the
injecting agent in the chain. In normal circumstances there
should therefore be only one `%` delimiter present, and
injecting agents MAY choose to reject proto-articles with a '%'
already in them. If, for whatever reason, more than one '%' is
found, then the path-identity in front of the leftmost '%' is to
be regarded as the true injecting agent.
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Previous draft (04): 5.6.2. Adding a path-identity to the Path header
Diffs to previous draft
--- {draft-04} Wed Jul 11 21:55:26 2001
+++ {draft-05} Wed Jul 11 21:55:27 2001
@@ -22,19 +22,13 @@
or "news@<FQDN>" whereby the administrators of that agent may be
reached.
-
-
- 3. A name registered previously in the UUCP maps database (found in
- the newsgroup comp.mail.maps), containing no '.' character.
+ 3. An arbitrary name believed to be unique and registered at least
+ with all sites immediately downstream from the given site.
4. An encoding of an IP address - <dotted-quad> [RFC 820] or <ipv6-
numeric> [RFC 2373] (the requirement to be able to use an <ipv6-
numeric> is the reason for including ':' as an allowed character
within a path-identity).
-
- 5. A '.' followed by an arbitrary name not in the UUCP maps database,
- but believed to be unique and registered at least with all sites
- immediately downstream from the given site.
Of the above options, nos. 1 to 3 are much to be preferred, unless
there are strong technical reasons dictating otherwise. In