Dynamic Host Configuration Protocol (DHCP) IPv4 and IPv6 Option for a Location Uniform Resource Identifier (URI)
draft-ietf-geopriv-dhcp-lbyr-uri-option-19

[Ballot comment]
  o A Location URI Option with a non-zero Valid-For field MUST NOT
    transmit the Location URI once the Valid-For field counts down to
    zero.

I don't know what the object of the MUST NOT here is, which is a problem in itself.  Also, the multiple meanings for a zero value are confusing here—it might be easier to state this in terms of calculating an absolute end to the valid lifetime by adding the valid time option to the current time.  Then you can just talk about when the recorded expiration time is earlier than the present time, and not confuse the different meanings of zero.

  o Receipt of the Location URI Option containing all zeros in the
    Valid-For field MUST NOT cause any error in handling the Location
    URI.

What is the object of the MUST NOT here?  Why is this text necessary since the previous bullet item already says what the meaning of a value of zero in this field is?


  o When the Valid-For timer reaches zero, the client MUST purge any
    location URI received via DHCP from its memory.

This is an implementation detail, and shouldn't be stated with normative language, if indeed it should be stated at all.  I think this is the repeat of the first bullet item in this series, stated a different way.  You shouldn't care how the client handles garbage collection—just what it *does*.  So simply saying that after the Valid-for timer has expired, the client MUST not continue to use the URI should suffice.

  o Clients receiving a Location URI Option start the Valid-For timer
    upon receipt of the DHCP message containing the Option.

  o Clients MUST NOT trigger an automatic DHCP refresh on expiry of
    the Valid-For timer; rather, they MUST follow normal DHCP
    mechanics.

I feel uncomfortable with this, and I think it's because you're really specifying implementation again rather than behavior.  If you take my advice about calculating absolute end times rather than having a countdown timer that triggers an event, I think you could really simplify this.

I realize that the second item is actually a response to a comment I made, but I would rather you said something like this:

  o The Valid-For time is independent of the DHCP client renewal
    process; if the URI's validity ends before the lease renews, the
    client will simply not be able to provide a URI during the period
    between the end of the valid time of the URI and the renewal of
    the DHCP lease.

That segues into this paragraph, which I am having difficulty making sense of:

  If the Valid-For timer is set to expire before the lease refresh,
  the client will not have the ability to hand out its location until
  the lease refresh, inadvertently allowing a gap of coverage. If the
  Valid-For timer is set to expire after the lease refresh, some
  wayward application on the client can divulge that location URI
  after it is no longer valid, meaning the location could be stale or
  just plain wrong.

This is why I argued that the location URI shouldn't have a separate lifetime.  You get bad behavior when it's shorter than the lease, and you get bad behavior when it's longer than the lease.  And it's difficult to even say what the bad behavior will be:

  o Servers SHOULD set the Valid-For timer to that of the lease
    refresh, or bad things can happen.

If servers SHOULD do this, what's the point of having a Valid-for timer at all?  What are the bad things that can happen?  What is the edge case that justifies a SHOULD here instead of a MUST?

[Ballot discuss]
Section 2.3 of this document significantly modifies the DHCP protocol, to the extent that if the language in this section remains, it would be necessary to say that this document updates RFC3315 and RFC2131.  Updating RFC3315 and RFC2131 is not part of the geopriv charter; if indeed the author intends to update these RFCs, this document would need to be moved to the DHC working group and would need to become a DHC working group document, and would need to pass last call in that working group (DHC working group /is/ chartered to extend the DHCP protocol).

Normally option specifications do not update RFC3315, RFC2131 or RFC2132 because they are purely additive.  The reason that the text in section 2.3 is a problem is that it doesn't document a new option—it documents new _behavior_ for DHCP servers and clients.  It is this that is out of scope for geopriv work.

To illustrate, consider the following text:

  o Implementation of the Location URI Option is REQUIRED on the DHCP
    server and client.

This updates the DHCP protocol by requiring that DHCP servers and clients implement this option; ordinarily implementation of new options is optional, and when done, is done by simply adding some new configuration boilerplate to the server configuration, and maybe a post-processing script on the client.

  o Clients SHOULD be expected to have to request the Location URI
    Option from servers. Although local policy can have servers
    perform an unsolicited push of a Location URI Option to a client.

This updates the DHCP protocol to supersede the statement in RFC3315 that DHCP servers MUST NOT send unsolicited options.  It skates the ragged edge of updating RFC2131 as well; RFC2131 does not forbid sending unsolicited options, but it doesn't require it either.

  o Servers SHOULD set the Valid-For timer to that of the lease
    refresh, or bad things can happen.

I talk about this below in the comments as well, but my DISCUSS-level objection to this is that since lease times are a negotiation, not a hard configuration on the server, in order to satisfy the SHOULD above, the server has to have special code for this option that derives the Valid-for time from the lease time.  This is another protocol change to DHCP, and hence out of scope for this document.  You haven't actually stated it as a requirement, so I suppose you could argue that it's the implementor's problem, but I think that would be splitting hairs—I think you really have updated RFC3315 and RFC2131 with this language.

[Ballot comment]
  o A Location URI Option with a non-zero Valid-For field MUST NOT
    transmit the Location URI once the Valid-For field counts down to
    zero.

I don't know what the object of the MUST NOT here is, which is a problem in itself.  Also, the multiple meanings for a zero value are confusing here—it might be easier to state this in terms of calculating an absolute end to the valid lifetime by adding the valid time option to the current time.  Then you can just talk about when the recorded expiration time is earlier than the present time, and not confuse the different meanings of zero.

  o Receipt of the Location URI Option containing all zeros in the
    Valid-For field MUST NOT cause any error in handling the Location
    URI.

What is the object of the MUST NOT here?  Why is this text necessary since the previous bullet item already says what the meaning of a value of zero in this field is?


  o When the Valid-For timer reaches zero, the client MUST purge any
    location URI received via DHCP from its memory.

This is an implementation detail, and shouldn't be stated with normative language, if indeed it should be stated at all.  I think this is the repeat of the first bullet item in this series, stated a different way.  You shouldn't care how the client handles garbage collection—just what it *does*.  So simply saying that after the Valid-for timer has expired, the client MUST not continue to use the URI should suffice.

  o Clients receiving a Location URI Option start the Valid-For timer
    upon receipt of the DHCP message containing the Option.

  o Clients MUST NOT trigger an automatic DHCP refresh on expiry of
    the Valid-For timer; rather, they MUST follow normal DHCP
    mechanics.

I feel uncomfortable with this, and I think it's because you're really specifying implementation again rather than behavior.  If you take my advice about calculating absolute end times rather than having a countdown timer that triggers an event, I think you could really simplify this.

I realize that the second item is actually a response to a comment I made, but I would rather you said something like this:

  o The Valid-For time is independent of the DHCP client renewal process;
    if the URI's validity ends before the lease renews, the client will simply
    not be able to provide a URI during the period between the end of the
    valid time of the URI and the renewal of the DHCP lease.

That segues into this paragraph, which I am having difficulty making sense of:

  If the Valid-For timer is set to expire before the lease refresh,
  the client will not have the ability to hand out its location until
  the lease refresh, inadvertently allowing a gap of coverage. If the
  Valid-For timer is set to expire after the lease refresh, some
  wayward application on the client can divulge that location URI
  after it is no longer valid, meaning the location could be stale or
  just plain wrong.

This is why I argued that the location URI shouldn't have a separate lifetime.  You get bad behavior when it's shorter than the lease, and you get bad behavior when it's longer than the lease.  And it's difficult to even say what the bad behavior will be:

  o Servers SHOULD set the Valid-For timer to that of the lease
    refresh, or bad things can happen.

If servers SHOULD do this, what's the point of having a Valid-for timer at all?  What are the bad things that can happen?  What is the edge case that justifies a SHOULD here instead of a MUST?

[Ballot discuss]
Section 2.3 of this document significantly modifies the DHCP protocol, to the extent that if the language in this section remains, it would be necessary to say that this document updates RFC3315 and RFC2131.  Updating RFC3315 and RFC2131 is not part of the geopriv charter; if indeed the author intends to update these RFCs, this document would need to be moved to the DHC working group and would need to become a DHC working group document, and would need to pass last call in that working group (DHC working group /is/ chartered to extend the DHCP protocol).

Normally option specifications do not update RFC3315, RFC2131 or RFC2132 because they are purely additive.  The reason that the text in section 2.3 is a problem is that it doesn't document a new option—it documents new _behavior_ for DHCP servers and clients.  It is this that is out of scope for geopriv work.

To illustrate, consider the following text:

  o Implementation of the Location URI Option is REQUIRED on the DHCP
    server and client.

This updates the DHCP protocol by requiring that DHCP servers and clients implement this option; ordinarily implementation of new options is optional, and when done, is done by simply adding some new configuration boilerplate to the server configuration, and maybe a post-processing script on the client.

  o Clients SHOULD be expected to have to request the Location URI
    Option from servers. Although local policy can have servers
    perform an unsolicited push of a Location URI Option to a client.

This updates the DHCP protocol to supersede the statement in RFC3315 that DHCP servers MUST NOT send unsolicited options.  It skates the ragged edge of updating RFC2131 as well; RFC2131 does not forbid sending unsolicited options, but it doesn't require it either.

(I will be adding more to this DISCUSS, but I've run out of time and need to save, so please don't feel obligated to respond yet—I'll trigger an email transmission when I'm finished.)

[Ballot comment]
  o A Location URI Option with a non-zero Valid-For field MUST NOT
    transmit the Location URI once the Valid-For field counts down to
    zero.

I don't know what the object of the MUST NOT here is, which is a problem in itself.  Also, the multiple meanings for a zero value are confusing here—it might be easier to state this in terms of calculating an absolute end to the valid lifetime by adding the valid time option to the current time.  Then you can just talk about when the recorded expiration time is earlier than the present time, and not confuse the different meanings of zero.

  o Receipt of the Location URI Option containing all zeros in the
    Valid-For field MUST NOT cause any error in handling the Location
    URI.

What is the object of the MUST NOT here?  Why is this text necessary since the previous bullet item already says what the meaning of a value of zero in this field is?

[Ballot discuss]
Section 2.3 really needs a lot of work. [There are a couple of editorial points embedded in here that are not things I need to DISCUSS; I've set those off in square brackets.]

OLD
  o Implementation of the Location URI Option is REQUIRED on the DHCP
    server and client.

I know you don't mean that as written. As written, it says that all DHCP servers and clients are now required to implement this option. If you really meant this, you'd need an "Updates: 2131", and I'm quite sure that's not right. I suspect you might mean something like: "The DHCP Location URI Option MUST NOT be used unless both the server and the client support it." But I don't think that's necessary. My recommendation is to simply strike this sentence.

OLD
  o Clients SHOULD be expected to have to request the Location URI
    Option from servers. Although local policy can have servers
    perform an unsolicited push of a Location URI Option to a client.

Aside from the second sentence being ungrammatical, this is overall not clear. Do you mean:

NEW
  o Clients normally send explicit requests for the Location URI
    Option. Servers SHOULD NOT send unsolicited Location URI
    Option responses to a client.

? I'm not even sure if that SHOULD NOT is correct. What are you trying to get across in this bullet?

OLD
  Applications on a client can use the Location URI (value) until the
  Valid-For value reaches zero. If there is no Valid-For Option value,
  then the counter did not ever start (a null value), and applications
  on a client continue to use the Location URI value until given a new
  Location URI Option  (with or without a Valid-For value) which
  overwrites any previous Location URI and Valid-For Option values.

[The first sentence is goofy, though I know what you mean: The "Valid-For value" is never going to "reach zero"; what you mean is:

NEW
  Applications on a client can use the returned Location URI for the
  number of seconds specified in Valid-For from the time it was
  received by the client.
]
 
But the second sentence is completely unwieldy and not clear. (Zero is not a "null value".) Simplify:

NEW
  If the Valid-For value is zero, it indicates that there is no time
  limit on the use of the returned Location URI. It may be used until
  the server returns a new Location URI.

OLD
  o Receipt of the Location URI Option containing all zeros in the
    Valid-For field MUST NOT cause any error in handling the Location
    URI.

I don't know what that is supposed to mean. Why do you think you need to call out that I MUST NOT cause an error in *any* event?

OLD
  o When the Valid-For timer reaches zero, the client MUST purge any
    location URI received via DHCP from its memory.

Aside from the "timer reaches zero" thing, I have to say: Baloney. I will *not* be purging any memory because you tell me to in this document, thank you very much. You can tell me not to use the thing, but you can't tell me how I have to do memory garbage collection. Please delete this.

OLD
  If the Valid-For timer is set to expire before the lease refresh,
  the client will not have the ability to hand out its location until
  the lease refresh, inadvertently allowing a gap of coverage. If the
  Valid-For timer is set to expire after the lease refresh, some
  wayward application on the client can divulge that location URI
  after it is no longer valid, meaning the location could be stale or
  just plain wrong.

[In the first sentence, change "hand out" to "use". Possible also change "the client" to "client applications". ]

The second sentence seems completely bogus to me: If the Valid-For time is longer than the lease time, it's the server's responsibility to hand me back the same URI when my lease expires. That URI *is* valid for the Valid-For time, and can never be stale or wrong. Therefore:

OLD
  o Servers SHOULD set the Valid-For timer to that of the lease
    refresh, or bad things can happen.

NEW
  o Servers SHOULD set Valid-For to greater than or equal to the lease
    refresh, or bad things can happen.
   
Section 4.2: "MUST have one of the following URI schemes"? Are you saying I need to write an update to this document if I want to use a different URI scheme for location information? Similarly:

Section 5.3: "IETF Review"

This all seems very heavy handed. Are we really in fear of people adding to this registry willy-nilly? Would not "Expert Review" or "Specification Required" not perfectly well suffice? Could we therefore not change 4.2 to say, "MUST be values registered in the Valid Location URI Schemes registry (defined in section 5.3)"?

[Ballot comment]
I agree with Barry that it would be good to have some further justification in the Intro for the usefulness of this mechanism.

Section 2.1:

OLD
  Valid-For:    The time, in seconds, the LocationURI is to be
                considered valid for dereferencing. The Valid-For is
                always represented as a four-byte unsigned integer.

I would add "in network byte order" just to be clear. Also: I believe that zero in this field means that there is no expiry; the URI is valid until replaced. You should say that here, not just in 2.3. So:

NEW
  Valid-For:    The time, in seconds, the LocationURI is to be
                considered valid for dereferencing. The Valid-For is
                always represented as a four-byte unsigned integer
                in network byte order. A value of 0 (zero) indicates
                that there is no valid time specified; the URI is
                valid until it is replaced.

Section 2.3:

OLD
  o A Location URI Option with a non-zero Valid-For field MUST NOT
    transmit the Location URI once the Valid-For field counts down to
    zero.

That's already said above. And "count down" assumes an implementation choice. (Me, I'd add the number of seconds to the current time to get expiration time and then compare it to current time thereafter.) But, it's redundant. Delete.

OLD
  o A received Location URI Option containing all zeros in the
    Valid-For field means that Location URI has no lifetime, and not
    "no lifetime left". All zeros in the Valid-For field equates to a
    null value.

Redundant. Delete.

OLD
  o Clients receiving a Location URI Option start the Valid-For timer
    upon receipt of the DHCP message containing the Option.
   
I had something like this in my replacement above, so now redundant.

Section 3: s/identity information/identifying information

Section 4.1 seems like a security consideration. Perhaps move it to section 6?

[Ballot discuss]
Updated for -19:

POINT 1:

I've expressed a basic problem I have with getting these URIs via insecure DHCP, and I'll refine that comment here, based on discussion that's so far been had.

Recognizing that in many cases getting URIs this way is an improvement over getting the location information itself, I'll note that that's not always true: the actual LI is a one-time thing, while the location URI can be dereferenced multiple times during its valid period, potentially allowing a snooper to track a moving user over time.

The general point is that a location URI has to be protected from snooping, protected from unauthorized use if it's snooped, or both.  Given that this can't do the former over DHCP, it needs to address the latter issue.  If one gets a URI that can only be used by an authorized entity, we're in much better shape.

That probably means a change to the Introduction to explain the situation, and something in the Security Considerations that addresses use of secure URIs (https or sips, rather than http or sip) and authentication on dereferencing.  I wouldn't want MUSTs here, but strong recommendations to secure this stuff.  I'm looking for something that makes the exposure clear and advises the use of acceptable mechanisms to protect the information, most likely as SHOULD.  Then if you think exposing your subscribers' location information is acceptable, that's between you and your subscribers.

In my conversation with James about this, James mentioned RFC 5606.  I'll note that, while 5606 is not addressing the same thing (5606 is primarily about dealing with "retransmissions", and its advice is only in that context), it actually does support the sorts of things I'm saying (see Section 2, paragraph 5, and Section 3.3.2).

POINT 2:

-- Section 5.3 --

Thanks for fixing the IANA Considerations section; this all now seems quite clear.  I have one question about the new registry:

Why did the working group select IETF Review for the registration policy? Did the working group discuss this? IETF Review requires an IETF-stream RFC (Standards Track, BCP, Informational, or Experimental), and is a fairly high bar. Why does the working group think that Expert Review is not appropriate for this registry?

(Note that I am *not* expecting you to just change this in response to my question.  I want to make sure we have the discussion.)

[Ballot discuss]
Updated for -19:

POINT 1:

I've expressed a basic problem I have with getting these URIs via insecure DHCP, and I'll refine that comment here, based on discussion that's so far been had.

Recognizing that in many cases getting URIs this way is an improvement over getting the location information itself, I'll note that that's not always true: the actual LI is a one-time thing, while the location URI can be dereferenced multiple times during its valid period, potentially allowing a snooper to track a moving user over time.

The general point is that a location URI has to be protected from snooping, protected from unauthorized use if it's snooped, or both.  Given that this can't do the former over DHCP, it needs to address the latter issue.  If one gets a URI that can only be used by an authorized entity, we're in much better shape.

That probably means a change to the Introduction to explain the situation, and something in the Security Considerations that addresses use of secure URIs (https or sips, rather than http or sip) and authentication on dereferencing.  I wouldn't want MUSTs here, but strong recommendations to secure this stuff.  I'm looking for something that makes the exposure clear and advises the use of acceptable mechanisms to protect the information, most likely as SHOULD.  Then if you think exposing your subscribers' location information is acceptable, that's between you and your subscribers.

In my conversation with James about this, James mentioned RFC 5606.  I'll note that, while 5606 is not addressing the same thing (5606 is primarily about dealing with "retransmissions", and its advice is only in that context), it actually does support the sorts of things I'm saying (see Section 2, paragraph 5, and Section 3.3.2).

POINT 2:

-- Section 5.3 --

Thanks for fixing the IANA Considerations section; this all now seems quite clear.  I have one question about the new registry:

Why did the working group select IETF Review for the registration policy?  Did the working group discuss this?  IETF Review requires an IETF-stream RFC (Standards Track, BCO, Informational, or Experimental), and is a fairly high bar.  Why does the working group think that Expert Review is not appropriate for this registry?

(Note that I am *not* expecting you to just change this in response to my question.  I want to make sure we have the discussion.)

[Ballot comment]
Updated for -19:

-- Section 2.3 --

  o Clients SHOULD be expected to have to request the Location URI
    Option from servers. Although local policy can have servers
    perform an unsolicited push of a Location URI Option to a client.

"SHOULD be expected to have to"?  That's pretty odd, and I don't think the whole paragraph is clear.  Does this reflect what you're trying to say?:

NEW
  o Clients will normally request the Location URI Option explicitly,
    though servers can include the option without such request,
    according to local policy/configuration.
END

(I don't think 2119 key words are needed there, because there are no interoperability issues involved.)

  Applications on a client can use the Location URI (value) until the
  Valid-For value reaches zero. If there is no Valid-For Option value,
  then the counter did not ever start (a null value), and applications
  on a client continue to use the Location URI value until given a new
  Location URI Option  (with or without a Valid-For value) which
  overwrites any previous Location URI and Valid-For Option values.

I know what you're saying here, but the Valid-For value is a fixed thing that's sent by the server, not something that, by itself, will ever reach zero.  So I think you need to say it a different way, and one that doesn't assume a particular implementation mechanism.  A number of the subsequent bullets also seem confused in similar ways.  Let me try a proposal to replace all of them (including my above proposal here):

NEW
2.3 Rules for the LocationURI Option

  The following rules apply to the LocationURI Option:

  o Implementation of the LocationURI Option is REQUIRED on the DHCP
    server and client.

  o The LocationURI and Valid-For values in a newly received
    LocationURI Option always replace any values received earlier.

  o A Valid-For value of zero means that the LocationURI can be
    used indefinitely (until it is replaced by a new LocationURI
    Option).

  o A LocationURI can be used until the time represented by the
    Valid-For value, or until it is replaced. It MUST NOT be used
    beyond those limits.

  o It is important that server implementations not send a
    LocationURI that is no longer valid.

  o It is important that client implementations discard any
    LocationURI that is no longer valid.  Retaining invalid URIs
    in memory can lead to privacy exposure.

  o Clients MUST NOT trigger an automatic DHCP refresh on expiry
    of the Valid-For timer; rather, they MUST follow normal DHCP
    mechanics.

  The following apply to setting the Valid-For value relative to
  the DHCP lease time:

  o If the Valid-For value is set to be shorter than the DHCP lease
    time, the client will not have a valid URI for its location
    until the lease refresh, leaving a gap in coverage. 
   
  o If the Valid-For value is set to be longer than the DHCP lease
    time, a wayward application on the client could divulge the
    location URI after it is no longer valid, in violation of the
    rules above.

  o Servers SHOULD, therefore, set the Valid-For value to match the
    DHCP lease time as closely as possible.
END

Do you think that works?  If not quite, tweak as appropriate.

-- Section 4.2 --

  URIs carried by this DHCP Option MUST have one of the following URI
  schemes:

I suggest this instead:

NEW
  URIs carried by this DHCP Option MUST have one of the URI schemes
  in the "Valid Location URI Schemes" registry (see Section 5.3).
  The initial schemes, registered here, are these:
END

I also suggest that the registrations in Section 5.3 use a reference of "[this document], Section 4.2", so that people can quickly find where this is discussed.

[Ballot discuss]

-19 doesn't seem to make changes related to this

1) I suspect there's an unfounded assumption built in to this
draft (and plenty of other IETF work) that runs counter to
good privacy practices and current reality.

The maybe unfounded assumption: Applications running on a
host can be considered to be acting in the interests of the
end-user or administrator of that host. 

If the above description of today's reality is true, (and I
think it is), then there is a missing privacy consideration
here which is that Targets or DHCP clients MUST provide the
end-user or administrator a way to override the actions that
applications might otherwise make related to the use of these
URLs. (In fact, I suspect this will be done anyway, but it'd
still be good to impose that requirement here regardless.)

2) RFC 6753 distinguishes between an authorization by
possession model and a model where (real:-) authorization can
be done via access control done during the HTTP exchange to
re-reference the URL. I would argue that only the latter
model ought be supported here since anyone can send a DHCP
request and see the associated response and (some) wireless
networks can span large areas so a bad actor can learn more
in seeing such a response. That also raises the question as
to what HTTP authentication and access controls a client
using these URIs MUST support. (I see that 3.1 says that the
"possession model" aka supposedly secret URI values, is the
default, but no justification is given for that.)

3) The intro (3rd last para) seems to suggest that home
routers be configured to set these options in responses but
says nothing about privacy. Personally, I think any such
router configuration would for privacy reasons be REQUIRED to
be off by default and only turned on if the user wishes.  I
can see that other opionions would be reasonable and have no
doubt that others will have other opinions. Did the WG
discuss that, if so, got a pointer to the archive?  If not,
maybe either drop the example or add some WG consensus text
about privacy for that case.

4) Why does this not provide an option for the DHCP client to
control the LS' behaviour? Can you point me at or summarise
the WG discussion of that? I'm a bit surprised about that not
being done, since I'd have thought it'd be good for both
privacy sensitive folks and their opposites (if you know what
I mean). While we ought not provide options for fun, this one
would seem quite reasonable and would seem to provide support
for those who do and don't care about privacy at the same
DHCP relay/server. (I note 3.1 says this is out of scope, but
I don't see why.)

5) Does repeated use of the same value for a URI constitute
identity information? Arguably it does, given that use of
such URIs will be correlated with identity information. The
"MUST NOT reveal" in section 3 5th para if interpreted
strictly seems very onerous. It may be better to have a
positive MUST statement about peudo-randomness and
unpredicatability.

6) How does the MUST NOT from discuss point 5 match the idea
that the location URI "indicate the residence's civic
address"? That seems plainly contradictory to me. Could be
this is just terminology, but I'd like to check.

7) I don't get how the valid URI schemes is in scope here but
the authorization model and other aspects of the
de-referencing UA are not. The DHCP client and server do not
have to do anything with the scheme, which is only relevant
to the de-referencing UA, but that UA also has to support (or
not) TLS or proxy authentication or OAUTH or whatever might
be needed for handling any real authorization.

8) The reliance on DHCP auth (3118) here seems to me to be
entirely bogus. In what circumstances do you expect 3118 to
be used? I think just deleting that reference to an almost
universally unused RFC would give a more accurate picture of
DHCP security. And I'm also unsure what threat is being
countered by 3118 in this context - I'm not sure having a
fake URI provided to the DHCP client is much of a threat.

[Ballot comment]
- I agree with Barry's first discuss point

- intro: Is the DHCP client really the Geopriv target? I
think that'd be better stated as the system on which the DHCP
client is running is the Geopriv target.

- intro: you call out the advantages of indirection, but in
fairness you should also admit the disadvantages, which might
include extra round-trips and infrastructure and additional
exposure of possible private information (current location).

- intro: p3, 3rd para: talking about UAs and DHCP clients as
if they were the same seems wrong, and I think this is done
here. The former is an application thing and the latter a
system thing.

- intro, p4, maybe expand LCI on 1st use

- 2.1, don't you need a reference to RFC 3986 for URI
encoding?

- section 3, 2nd last para: s/deference/de-reference/ I
assume:-)

- section 5: critical decisions will never be made on the
value of the URIs, but rather on the location value (when
renders the non-use of 3118 irrelevant I'd say)

- section 5: Saying that someone else ought look at 3552 in
your security considerations is bogus. The authors of this
document should do that here if its needed. In this case the
"that" is sending the location URI over a network between a
DHCP relay and DHCP server I guess.

[Ballot discuss]

1. (From Ted Lemon's review)  In section 2.5:

  o The Valid-For Option MUST NOT be sent from a server, and received
    by a client, without an accompanying Location URI Option.

This places special processing requirements on the DHCP server—it
would be as if an RFC said "for A records within the ORG. zone, the
DNS server MUST NOT return IP addresses within the 128.45 class B
network, which belongs to a commercial entity."

Just take this text out.

2. (Also from Ted) I would replace this text:

  The Valid-For Option offers no meaningful information to a client
  without an accompanying Location URI Option, and might be
  misunderstood or misapplied, therefore

  o The Valid-For Option MUST NOT be sent from a server, and received
    by a client, without an accompanying Location URI Option.

  o A client receiving a Valid-For Option without a Location URI
    Option MUST ignore the Valid-For Option.

  o The Valid-For Option MUST only be considered in relation to the
    Location URI Option. It has no other purpose in DHCP then in
    relation to the Location URI (i.e., there is no other Option in
    DHCP to which it has meaning).

  o The Valid-For Option MUST NOT cause any error in handling the
    Location URI, i.e., if not understood, it MUST be ignored.

  o Servers MUST assume that clients will overwrite any existing,
    previously sent values of Location URI Option and/or Valid-For
    Option.

  o Clients MUST overwrite any existing, previously sent values of
    Location URI Option and/or Valid-For Option when receiving the
    next instance of either Option.

With this:

  The Valid-For Option offers no meaningful information to a client
  without an accompanying LocationURI Option.  Clients receiving a
  Valid-for option without an accompanying Location URI option SHOULD
  silently ignore this option.  Valid-For options relate specifically
  to Location URI options within the same DHCP message, and do not
  apply to Location URI options received in other DHCP messages.

3. I'm writing this after Brian posted his review and we've started a
conversation about separating the LocationURI and Valid-For options.
There may have been some miscommunication about whether the Valid-For
option could be included in the LocationURI option.  I'll make the
suggestion that the Valid-For life be added as an initial 32-bit
fixed-size field at the beginning of the LocationURI option, with the
special value 0 meaning "no expiration time".

4. (Also from Ted) In section 3:

  It is RECOMMENDED to avoid building URIs, with any parameters,
  larger than what a single DHCP response can be.  However, if a
  message is larger than 255 bytes, concatenation is allowed, per
  RFC 3396 [RFC3396].

You should pick one position or the other.  Either:

  DHCP servers MUST NOT send URIs longer than 255 bytes.

or:

  The LocationURI option is a concatenation-requiring option as
  described in "Encoding Long Options in DHCPv4" [RFC3396], section
  4.  DHCP clients implementing this specification must also
  implement RFC3396.

5. The first few paragraphs of section 3 are DHCPv4-centric (and the
message names aren't given accurately).  This text should be edited
to discuss both DHCPv4 and DHCPv6 explicitly. 

6. The second paragraph of section 3 could be read to imply that a
server might put a Location URI option in a separate (additional)
message to a client.  That's not how DHCP works.  All the options have
to fit in a single response (DHCPOFFER, DHCPACK for DHCPv4, Advertise
or Reply for DHCPv6).  The fourth paragraph is potentially confusing
as well, without specifying if the Location URI option is a
concatenating option.  Does "subsequent LocationURI Options" refer to
option within one DHCP message or in distinct DHCP messages?

7. (From Ted Lemon's review) I'm not sure that the way you've
specified IANA considerations will work.  Normally we put text in the
option definition that's replaced by the RFC editor once the option
code has been assigned, like this:

+----------------+---------+--------------------+
| OPT_LURI4      | len    |      payload      |
+----------------+---------+--------------------+

option-code: OPT_LURI4 (TBD)

This gives the RFC editor a place to put the option code inline.
Rather than just following this recommendation, I would look at some
existing examples.  For example, compare section 3 here:
http://tools.ietf.org/html/draft-ietf-dhc-dhcpv6-relay-supplied-options-09
to section 3 here: http://tools.ietf.org/html/rfc6422 and feel free to
plagiarize the IANA considerations section from the draft (not the
RFC!).

Then in the IANA considerations section, you need to say:

The IANA is requested to assign option codes for OPT_LURI4 and
OPT_LURIVALID4 from the BOOTP Vendor Extensions and DHCP Options
registry at
http://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xml.
(You also need to say what to put in the Length and Meaning fields;
for LURI, I think it's N, and for LURIVALID it's probably 4.)

The IANA is requested to assign option codes for OPT_LURI6 and
OPT_LURIVALID6 from the DHCP Option Codes registry at
http://www.iana.org/assignments/dhcpv6-parameters/dhcpv6-parameters.xml.
(You don't need length and meaning fields for these—we eliminated that
in the DHCPv6 option registry.)

[Ballot comment]

1. The last paragraph of section 2.5 might be more clearly written as

  It is RECOMMENDED that the Valid-For lifetime always be greater
  than the expected maximum time before the DHCP client will contact
  the DHCP server as part of its normal operation.  Otherwise, there
  is a possibility that the host will not have a valid LocationURI
  for the interval between the Valid-For life expiration and the

2. (From Ted Lemon's review) You should really give the valid-for
option a name that references the location URI option—lURI valid-for,
or something like that.  This will minimize confusion for people
reading the option registry.

3. For consistency, use "LocationURI" or "Location URI" throughout the
document.

Editorial suggestion for organizing the document:

Paragraphs 1-4 and (perhaps) 9 (beginning with "This Option is used
only...") would fit better with section 2.5, which would be better
titled "DHCP Operational Considerations".  Section 3 should be
retitled something like "URI, URL and LS considerations".

[Ballot discuss]
Updated after a discussion with Robert...

I am having a hard time understanding a few things in this document...

1. Section 3 purports to discuss how DHCP will handle this option.  However, the text does not contain a sufficient level of detail to ensure interoperability.  Additionally, there are operational differences between DHCPv4 and DHCPv6 that are not considered in this section.  Is this information supposed to always be included by a server when an address is assigned to a requesting device?  Or should this option really only be returned when it is explicitly requested?  Here is one example of how this lack of clarity can cause problems.  A DHCP client implementation could assume that this option will be returned with any addresses assigned to the device.  The server implementation could assume that this option is only returned when a client requests additional information via an INFORM message.  I would suggest having a sub-section within section 3 for both DHCPv4 and DHCPv6 that spell out how the DHCP exchanges are to occur.

2. [Removed since the splitting of the information was a recommendation from DHC]

3. Sections 3.1-3.3 are not related to the operation of DHCP.  Is there a reason why they are lumped into section 3?

4. The last paragraph of section 2.5 (discussion of values for the Valid-for option) is quite confusing and may actually be wrong.  Given the lack of unity in the URI lifetime and the DHCP lease lifetime, shouldn't the guidance simply be that the URI lifetime should not be less than the DHCP lease lifetime?

[Ballot discuss]
I am having a hard time understanding a few things in this document...

1. Section 3 purports to discuss how DHCP will handle this option.  However, the text does not contain a sufficient level of detail to ensure interoperability.  Additionally, there are operational differences between DHCPv4 and DHCPv6 that are not considered in this section.  Is this information supposed to always be included by a server when an address is assigned to a requesting device?  Or should this option really only be returned when it is explicitly requested?  Here is one example of how this lack of clarity can cause problems.  A DHCP client implementation could assume that this option will be returned with any addresses assigned to the device.  The server implementation could assume that this option is only returned when a client requests additional information via an INFORM message.  I would suggest having a sub-section within section 3 for both DHCPv4 and DHCPv6 that spell out how the DHCP exchanges are to occur.

2. Why is there a separate option for the lifetime (Valid-for).  Since it is a fixed length field, why is it not a part of the LocationURI option?

3. Sections 3.1-3.3 are not related to the operation of DHCP.  Is there a reason why they are lumped into section 3?

4. The last paragraph of section 2.5 (discussion of values for the Valid-for option) is quite confusing and may actually be wrong.  Given the lack of unity in the URI lifetime and the DHCP lease lifetime, shouldn't the guidance simply be that the URI lifetime should not be less than the DHCP lease lifetime?

[Ballot discuss]
I am baffled by two things in 2.5:

  o Implementation of the Location URI Option is mandatory on the DHCP
    server and client, per this specification.

Why is this mandatory? You can't be saying that all DHCP servers are now required to implement this option, can you?

  o The Location URI Option MUST be sent from a server, and received
    by a client with or without an accompanying Valid-For Option.
   
I don't understand what this is trying to say that isn't stupidly obvious. As Martin says in his comment, are you simply trying to say that the Location URI MUST NOT be sent by a client? I don't get it.

[Ballot comment]
As I said in my reply to Barry's comments, I disagree with Barry's first DISCUSS point. I believe this can be a useful mechanism, but I think some more needs to be said in the intro regarding why it is useful. In addition, there should be some justification in the intro for why this would be at all interesting to fixed location devices (assuming there is one). It seems like passing the actual PIDF-LO instead of a URI would be *more*  efficient, if not safer, for fixed devices. But perhaps there are other operational reasons not to do so. Some explanation would be useful.

I agree with Barry's DISCUSS points regarding 2.5 and section 3.

The Valid-For option only applies to the Location-URI? Perhaps it should be named "Location-Valid-For" or "Location-URI-Valid-For". I can certainly imagine other expiring values appearing in DHCP messages that are not tied to the lease time. Seems like a poor choice for a name that is specific.

So, why is the Valid-For not simply included in the Location URI Option? Just put the 4 octets before the URI and the length is always length of URI + 4. Wouldn't that be easier?

[Ballot comment]
This document is scrutinized by Barry, Sean, Martin, and Stephen. I has enough attention, and I trust those ADs will do the right thing.

[Ballot discuss]
I have no general objections to this draft, but multiple points to be discussed. However, most of my DISCUSS worthy issues are already covered by parts of Barry's, Stephen's, and Sean's DISCUSS.

There is only a single point left:

Section 2.5, paragraph 11:

>    o Clients MUST overwrite any existing, previously sent values of
>      Location URI Option and/or Valid-For Option when receiving the
>      next instance of either Option.

  If a host has multiple interfaces that are used concurrently and the host receives the location URI from multiple DHCP server, how is this handled? This information is handed over to some application that probably doesn't care too much about multiple network locations. However, this is something that should be at least mentioned and discussed.

[Ballot comment]


Here are a few points for your consideration:

Section 7., paragraph 1:

>    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
>    "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
>    document are to be interpreted as described in [RFC2119].

  This part isn't right here, as it is not part of the ToC, but also
  not part of any section. Move it to the introduction.


Section 1., paragraph 6:

>    If the client was provided a location URI reference to retain and
>    hand out when it wants or needs to convey its location (in a
>    protocol other than DHCP), a location URI that would not change as
>    the client's location changes (within a domain).Scaling issues

  This sentence is not complete, isn't it? Or I cannot read and understand the meaning of it.


Section 2.1, paragraph 4:

>    Length=XX:    The length of this option, counted in bytes - not
>                  counting the Code and Length bytes. This is a variable
>                  length Option, therefore the length value will change
>                  based on the length of the URI within the Option.

  I would include a pointer to the datagram length discussion in
  Section 3, just for completeness and to be sure that everybody
  understands the issue.


Section 2.2, paragraph 5:

>    option-len:  The length of this option, counted in bytes - not
>                counting the option-code and option-len bytes. This is
>                a variable length Option, therefore the length value
>                will change based on the length of the URI within the
>                Option.

  I would include a pointer to the datagram length discussion in
  Section 3, just for completeness and to be sure that everybody
  understands the issue.


Section 2.5, paragraph 2:

>    o Implementation of the Location URI Option is mandatory on the DHCP
>      server and client, per this specification.

  'mandatory' is not a term per RFC 2119. Should this read 'MUST be
  implemented by the client and the server if they support ',
  as you use 'OPTIONAL' just one down?


Section 2.5, paragraph 4:

>    o The Location URI Option MUST be sent from a server, and received
>      by a client with or without an accompanying Valid-For Option.

  Doesn't this mean more 'The Location URI Option MUST be only be
  sent by a server. Clients MUST NOT sent it.'


Section 2.5, paragraph 6:

>    o The Valid-For Option MUST NOT be sent from a server, and received
>      by a client, without an accompanying Location URI Option.

  A proposal to improve readability: 'The Valid-For Option MUST be sent
  by a server together with an accompanying Location URI Option.' I
  would remove the client part, as it is anyhow described below. The
  client will receive any unwanted option anyhow, but it ignores it
  later on during the processing.


Section 3396, paragraph 8:

>    This Option is used only for communications between a DHCP client
>    and a DHCP server.  It can be solicited (requested) by the client,
>    or it can be pushed by the server without a request for it.  DHCP
>    Options not understood MUST be ignored [RFC2131].  A DHCP server

  I would make this a single paragraph, to improve readability, i.e., split it from the following rest..


Section 3396, paragraph 11:

>    In the case of residential gateways being DHCP servers, they usually
>    perform as DHCP clients in a hierarchical fashion up into a service
>    provider's network DHCP server(s), or learn what information to
>    provide via DHCP to residential clients through a protocol, such as
>    PPP.  In these cases, the location URI would likely indicate the
>    residence's civic address to all wired or wireless clients within
>    that residence.

  Not completely true, if there is also a VPN (or tunnel in general)
  gateway in that premise. How about: 'In these cases, the location
  URI would likely indicate the residence's civic address of the
  residential gateway.'


Section 3.2, paragraph 4:

>    o Section 3.3 IANA registers acceptable location URI schemes (or
>      types) for use by this specification. Clients MUST reject URI
>      schemes not currently registered in IANA.

  Isn't this 'MUST reject' a bit too strong? Given that somebody
  could have a new URI scheme, or one that is not public? A 'SHOULD'
  would be good enough.

[Ballot discuss]

1) I suspect there's an unfounded assumption built in to this
draft (and plenty of other IETF work) that runs counter to
good privacy practices and current reality.

The maybe unfounded assumption: Applications running on a
host can be considered to be acting in the interests of the
end-user or administrator of that host. 

If the above description of today's reality is true, (and I
think it is), then there is a missing privacy consideration
here which is that Targets or DHCP clients MUST provide the
end-user or administrator a way to override the actions that
applications might otherwise make related to the use of these
URLs. (In fact, I suspect this will be done anyway, but it'd
still be good to impose that requirement here regardless.)

2) RFC 6753 distinguishes between an authorization by
possession model and a model where (real:-) authorization can
be done via access control done during the HTTP exchange to
re-reference the URL. I would argue that only the latter
model ought be supported here since anyone can send a DHCP
request and see the associated response and (some) wireless
networks can span large areas so a bad actor can learn more
in seeing such a response. That also raises the question as
to what HTTP authentication and access controls a client
using these URIs MUST support. (I see that 3.1 says that the
"possession model" aka supposedly secret URI values, is the
default, but no justification is given for that.)

3) The intro (3rd last para) seems to suggest that home
routers be configured to set these options in responses but
says nothing about privacy. Personally, I think any such
router configuration would for privacy reasons be REQUIRED to
be off by default and only turned on if the user wishes.  I
can see that other opionions would be reasonable and have no
doubt that others will have other opinions. Did the WG
discuss that, if so, got a pointer to the archive?  If not,
maybe either drop the example or add some WG consensus text
about privacy for that case.

4) Why does this not provide an option for the DHCP client to
control the LS' behaviour? Can you point me at or summarise
the WG discussion of that? I'm a bit surprised about that not
being done, since I'd have thought it'd be good for both
privacy sensitive folks and their opposites (if you know what
I mean). While we ought not provide options for fun, this one
would seem quite reasonable and would seem to provide support
for those who do and don't care about privacy at the same
DHCP relay/server. (I note 3.1 says this is out of scope, but
I don't see why.)

5) Does repeated use of the same value for a URI constitute
identity information? Arguably it does, given that use of
such URIs will be correlated with identity information. The
"MUST NOT reveal" in section 3 5th para if interpreted
strictly seems very onerous. It may be better to have a
positive MUST statement about peudo-randomness and
unpredicatability.

6) How does the MUST NOT from discuss point 5 match the idea
that the location URI "indicate the residence's civic
address"? That seems plainly contradictory to me. Could be
this is just terminology, but I'd like to check.

7) I don't get how the valid URI schemes is in scope here but
the authorization model and other aspects of the
de-referencing UA are not. The DHCP client and server do not
have to do anything with the scheme, which is only relevant
to the de-referencing UA, but that UA also has to support (or
not) TLS or proxy authentication or OAUTH or whatever might
be needed for handling any real authorization.

8) The reliance on DHCP auth (3118) here seems to me to be
entirely bogus. In what circumstances do you expect 3118 to
be used? I think just deleting that reference to an almost
universally unused RFC would give a more accurate picture of
DHCP security. And I'm also unsure what threat is being
countered by 3118 in this context - I'm not sure having a
fake URI provided to the DHCP client is much of a threat.

[Ballot comment]

- I agree with Barry's first discuss point

- intro: Is the DHCP client really the Geopriv target? I
think that'd be better stated as the system on which the DHCP
client is running is the Geopriv target.

- intro: you call out the advantages of indirection, but in
fairness you should also admit the disadvantages, which might
include extra round-trips and infrastructure and additional
exposure of possible private information (current location).

- intro: p3, 3rd para: talking about UAs and DHCP clients as
if they were the same seems wrong, and I think this is done
here. The former is an application thing and the latter a
system thing.

- intro, p4, maybe expand LCI on 1st use

- 2.1, don't you need a reference to RFC 3986 for URI
encoding?

- section 3, 2nd last para: s/deference/de-reference/ I
assume:-)

- section 5: critical decisions will never be made on the
value of the URIs, but rather on the location value (when
renders the non-use of 3118 irrelevant I'd say)

- section 5: Saying that someone else ought look at 3552 in
your security considerations is bogus. The authors of this
document should do that here if its needed. In this case the
"that" is sending the location URI over a network between a
DHCP relay and DHCP server I guess.

[Ballot discuss]
Alert: This is a long DISCUSS, but don't be daunted; remember that DISCUSS means that I need to discuss stuff with the authors (et al).  The first item is fundamental, but is likely to be sorted out by whacking me over the head with some history and explanation.  I have already talked with Robert about it, and I think I might understand.  I'd like to hear what James can tell me about it. 

Something from Section 3 first:

  Location URIs MUST NOT reveal identity information of the user of
  the device, since DHCP is a cleartext delivery protocol.

This brings up a fundamental issue I have with this document: DHCP seems a particularly bad protocol to use for exchanging this sort of information, and you already have HTTP for the purpose.  I don't understand the need for retrieving these URIs over DHCP -- I don't understand the need at all, and I certainly don't understand why what need you might have would override the problems associated with it, compared with using HTTP.  Please explain this. 

-- Section 4 --

The IANA Considerations here seem entirely inadequate for figuring out what you're asking IANA to do where.  I see that Pearl complained about this during Last Call, 7 months and two draft versions ago, and that it's been changed...  but the changes do not address Pearl's questions.  In particular, the four subsections say that the document registers four values, but it doesn't make it clear in what registries those values are registered in.  Please update the document to be clear about that (check http://www.iana.org/protocols and use the correct registry name(s)). 

Section 3.2 says this:
  o Section 3.3 IANA registers acceptable location URI schemes (or
    types) for use by this specification. Clients MUST reject URI
    schemes not currently registered in IANA.

I don't see that this document creates a registry for these; Section 3.3 merely lists, statically, five acceptable URI schemes.  Do you still intend to have a registry for them? 

-----------------
The rest of these points are really editorial, but are points where I think the document lacks clarity sufficiently that I think they're likely to lead to confused implementations, especially by people who aren't deeply into this stuff:

-- Section 2.5 --
  o Clients MUST overwrite any existing, previously sent values of
    Location URI Option and/or Valid-For Option when receiving the
    next instance of either Option. 

I think this isn't specified quite right: if a client gets a Valid-For option without any Location URI option, it's supposed to ignore it, according to the 5th unnumbered bullet.  But this says it has to use it to overwrite the existing value. 

  o Clients MUST NOT trigger an automatic DHCP refresh on expiry of
    the Valid-For timer; rather, they SHOULD follow normal DHCP
    mechanics.

SHOULD?  Really?  Why is this not MUST?  What else might they do, and why?

-- Section 3 --

  Caution SHOULD always be used involving the creation of large
  Options, meaning that this Option MAY need to be in its own INFORM,
  OPTION or ACK message.

1.  What does that SHOULD really mean, and how can an implementor understand and fully weigh the implications of not doing this? 

2.  The "MAY" is completely wrong here, as a 2119 key word.  This is not describing optional behaviour, but, rather, is talking about a situation in which something specific might have to be done. 

  Per [RFC2131], subsequent LocationURI Options, which are
  non-concatenated, overwrite the previous value.

I'm really having trouble following this.  First, I don't know what it is in 2131 you're citing.  Can you give a more specific citation ("[RFC2131], Section 6.6.6") to help?  And your non-restrictive clause is throwing me: why, specifically, are they non-concatenated?  Or do you mean for it to be restrictive ("subsequent LocationURI Options that are not concatenated overwrite the previous value.") ? 

-- Section 3.3 --

  Responses to requests for URIs
  with other schemes ("sip", "sips", "http", and "https") MUST have
  MIME type 'application/pidf+xml'.

I don't know what it means for a DHCP response to have a MIME type (which, by the way, should be changed to "media type").  Please explain. 

In fact, this whole section confuses me, as it seems to refer to things that have nothing to do with getting URIs through DCHP.  This looks like stuff that's appropriate for HTTP.  Can you help me understand?  Maybe I'm just missing it.

[Ballot comment]
-- Section 1 --

  This location URI points a Location
  Server [RFC5808] which has the geolocation of the client (e.g.,
  uploaded into a wiremap database when the client attached wall-jack,
  or by means of 802.11 geolocation mechanisms).

Couple of typos in here; the second one makes it unclear:
1. "points TO a Location Server"
2. I can't figure out how to parse "uploaded into a wiremap database when the client attached wall-jack", and I don't know what you mean to say.

-- Section 2.5 --

  o Implementation of the Location URI Option is mandatory on the DHCP
    server and client, per this specification.

  o Implementation of the Valid-For Option is OPTIONAL on the DHCP
    server and client, per this specification.

Is there a reason these are not parallel in their use of 2119 keywords?  Maybe change "mandatory" in the first bullet to "REQUIRED"?  (And, by the way, I find the "per this specification" to be a bit silly, and unnecessary.)

  o The Location URI Option MUST be sent from a server, and received
    by a client with or without an accompanying Valid-For Option.

  o The Valid-For Option MUST NOT be sent from a server, and received
    by a client, without an accompanying Location URI Option.

I don't see how you can write 2119 language about what gets received, only about what gets sent.  Is there a reason not to remove ", and received by a client," from both of these? 

  o Servers MUST assume that clients will overwrite any existing,
    previously sent values of Location URI Option and/or Valid-For
    Option.

"MUST assume" sounds really odd, and, anyway, this item is entirely unnecessary, as it's covered by the next one, which is properly formed. 

-- Section 3 --
 
  It is RECOMMENDED to avoid building URIs, with any parameters,
  larger than what a single DHCP response can be.  However, if a
  message is larger than 255 bytes, concatenation is allowed, per RFC
  3396 [RFC3396].

I find the first sentence awkward, and it took me a few passes to get the right sense of it.  Further, again, what is the protocol problem that this is meant to address?  The second sentence already says that we can deal with longer messages.  I suggest getting rid of the 2119 language, and putting it this way:

NEW
  DHCP messages are limited in size, and long URIs will require the
  use of multiple messages and concatenation [RFC3396].  It is,
  therefore, best to limit the total length of a URI, including
  any parameters, to 220 bytes.

(I picked 220 so it will fit into a v6 message; adjust this text as appropriate.  If you really think you need to put in a SHOULD or RECOMMENDED, it'll go in the second sentence of my suggestion.)

-- Section 3.2 --

  o URIs received via this Option MUST NOT be automatically sent to a
    general-browser to connect to a web page, because they could have
    harmful scripts.

What if I have a browser that's set up to defend against harmful scripts?  What if I have a browser that doesn't run scripts automatically?  This seems a perfect place to have a SHOULD NOT, and simply to explain the threat. 

  o This Option MUST NOT contain "data:" URLs, because they could
    contain harmful scripts.

And I'm puzzled about this: http and data URIs can both get me to harmful scripts when they're dereferenced.  The former are allowed and the latter are forbidden.  Why is that?

[Ballot discuss]
1) s2.5 Valid-For:  I see where servers are configured to return values and it isn't understood it's ignored, but what's the default client behavior for an unknown or missing Valid-For time?  I.e., does it use it indefinitely or for an hour or local policy?  There's something in s3 about local timers but I thought that was DHCP timers.

2) s5: Because this option can be used with both DHVPv4 and DHCPv6 you need to also point to 3315.  Might I suggest the following (similar to text from RFC 6225):

Where critical decisions might be based on the value of this
location URI option, DHCP authentication as defined in
"Authentication for DHCP Messages" [RFC3118] and "Dynamic
Host Configuration Protocol for IPv6 (DHCPv6)" [RFC3315]
SHOULD be used to protect the integrity of the DHCP
options.
and then also that it's not just 3118 it's also 3315 in the next paragraph.

3) s5: In the 3rd paragraph, is security meant to be confidentiality/privacy protection?  I think what you're trying to say is:

DHCP, initially, is a broadcast request (a client looking for a
server), and a unicast response (answer from a server) type of
protocol.  There is no privacy protection for DHCP messages, an
eavesdropper who can monitor the link between the DHCP server
and requesting client can discover the Location URI.

And then add the following maybe at the end of the section:

Link-layer confidentiality and integrity protection may also be
employed to reduce the risk of location disclosure and tampering.

IANA has reviewed draft-ietf-geopriv-dhcp-lbyr-uri-option-15 and has the following comments:

IANA has questions about the IANA Actions requested in this document.

Upon approval of this document there appear to be three actions requested of IANA.

First, the document asks that: "IANA registers this IPv4 Option number XXX (to
be assigned by IANA once this document becomes an RFC)."  IANA believes that
this request is actually for a DHCP Option Number as usually registered in the
BOOTP Vendor Extensions and DHCP Options subregistry of the Dynamic Host
Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry
located at:

http://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xml

However, the authors provide no further information about how the value is to be
registered (for instance, name data length, meaning, etc.).

IANA Question -> could the authors provide a more robust and precise description
of their first request for registration in the IANA Considerations Section of
their document?

Second, the document also asks that: "IANA registers this IPv6 Option-Code XXX
(to be assigned by IANA once this document becomes an RFC).  IANA believes this
request is actually for a DHCPv6 Option Code as usually registered in the DHCP
Option Codes subregistry of the Dynamic Host Configuration Protocol for IPv6
(DHCPv6) registry located at:

www.iana.org/assignments/dhcpv6-parameters/dhcpv6-parameters.xml

IANA Question -> could the authors provide a more robust and precise description
of their second request for registration in the IANA Considerations Section of
their document?

Third, the authors request the creation of a new registry for acceptable
location types.

IANA Question -> What should the name of the registry be?  Where should it be
located?  In an existing registry or in a brand new registry?

IANA understands that the new registry would be managed through the Standards
Track process.  Initial values are provided for the new registry as follows:

+------------+----------------------------------------+---------------+
|  LuriType  |  Name                                | Reference    |
+------------+----------------------------------------+---------------+
|    1      |  Location URI                        | [ RFC-to-be ] |
|    2      |  Valid-For                            | [ RFC-to-be ] |
+------------+----------------------------------------+---------------+

IANA requires further clarity on all three actions requested by this document.

    * RFC XXXX is to be replaced with this document's RFC-Editor RFC
      number.

  Additions to this registry require a standards track RFC.

Note: The actions requested in this document will not be completed
until the document has been approved for publication as an RFC.
This message is only to confirm what actions will be performed.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (Dynamic Host Configuration Protocol (DHCP) IPv4 and IPv6 Option for a Location Uniform Resource Identifier (URI)) to Proposed Standard


The IESG has received a request from the Geographic Location/Privacy WG
(geopriv) to consider the following document:
- 'Dynamic Host Configuration Protocol (DHCP) IPv4 and IPv6 Option for a
  Location Uniform Resource Identifier (URI)'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2012-06-14. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document creates a Dynamic Host Configuration Protocol (DHCP)
  Option for transmitting a client's geolocation Uniform Resource
  Identifier (URI). This Location URI can then be dereferenced in a
  separate transaction by the client or sent to another entity and
  dereferenced to learn physically where the client is located.





The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-geopriv-dhcp-lbyr-uri-option/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-geopriv-dhcp-lbyr-uri-option/ballot/


No IPR declarations have been submitted directly on this I-D.

Shepherd Writeup by Alissa Cooper -

(1) What type of RFC is being requested (BCP, Proposed Standard,

Internet Standard, Informational, Experimental, or Historic)?  Why

is this the proper type of RFC?  Is this type of RFC indicated in the

title page header?


The type of RFC being requested is Proposed Standard. This is the proper RFC type because this draft is defining a new DHCP option and DHCP is an Internet standards track protocol.


(2) The IESG approval announcement includes a Document Announcement

Write-Up. Please provide such a Document Announcement Write-Up. Recent

examples can be found in the "Action" announcements for approved

documents. The approval announcement contains the following sections:


Technical Summary

This document creates a Dynamic Host Configuration Protocol (DHCP) Option for transmitting a Uniform Resource Identifier (URI) that points to a client's geolocation. The URI can be dereferenced in a separate transaction to obtain the client's geolocation.


Working Group Summary

This document represents the consensus of the GEOPRIV working group. The document went through several revisions in order to establish a clear understanding of the security model surrounding location URIs passed via DHCP, but WG participants are now satisfied with the description of the model provided in the document.


Document Quality

This document has been extensively reviewed by GEOPRIV participants and members of the DHC WG. The most recent round of DHC reviews resulted in changes to the document to ensure that the option specified here does not conflict with DHCP lease expiration behavior.


Personnel

Alissa Cooper is the document shepherd. Robert Sparks is the responsible area director.


(3) Briefly describe the review of this document that was performed by

the Document Shepherd.  If this version of the document is not ready

for publication, please explain why the document is being forwarded to

the IESG.


The shepherd conducted a thorough review of the document before submitting the -11 version for publication in April of 2011. Since then, the document has had further review from the DHC WG. The shepherd was involved in drafting changes to the document to satisfy the DHC reviewers and has reviewed the final changes to the document.


(4) Does the document Shepherd have any concerns about the depth or

breadth of the reviews that have been performed? 


No.


(5) Do portions of the document need review from a particular or from

broader perspective, e.g., security, operational complexity, AAA, DNS,

DHCP, XML, or internationalization? If so, describe the review that

took place.


The necessary DHC reviews have already taken place.


(6) Describe any specific concerns or issues that the Document Shepherd

has with this document that the Responsible Area Director and/or the

IESG should be aware of? For example, perhaps he or she is uncomfortable

with certain parts of the document, or has concerns whether there really

is a need for it. In any event, if the WG has discussed those issues and

has indicated that it still wishes to advance the document, detail those

concerns here.


The shepherd has no specific technical concerns with this document to which to call attention.


(7) Has each author confirmed that any and all appropriate IPR

disclosures required for full conformance with the provisions of BCP 78

and BCP 79 have already been filed. If not, explain why.


The author has confirmed that no disclosures need to be filed.


(8) Has an IPR disclosure been filed that references this document?

If so, summarize any WG discussion and conclusion regarding the IPR

disclosures.


No IPR disclosures have been filed against this document (although there was a message about IPR posted to IETF-Discussion on October 13, 2010).


(9) How solid is the WG consensus behind this document? Does it

represent the strong concurrence of a few individuals, with others

being silent, or does the WG as a whole understand and agree with it? 


The GEOPRIV working group has discussed this document at length and reached consensus about its content. Disagreements within the group have been resolved.


(10) Has anyone threatened an appeal or otherwise indicated extreme

discontent? If so, please summarise the areas of conflict in separate

email messages to the Responsible Area Director. (It should be in a

separate email because this questionnaire is publicly available.)


There have been no threatened appeals or expressions of extreme discontent against this document.


(11) Identify any ID nits the Document Shepherd has found in this

document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts

Checklist). Boilerplate checks are not enough; this check needs to be

thorough.


The copyright year needs to be updated to 2012. The reference to RFC 5808 should be changed to informative rather than normative. The references to RFC 3825 should be changed to refer to RFC 6225, which obsoleted RFC 3825 since this document was first publication requested.


(12) Describe how the document meets any required formal review

criteria, such as the MIB Doctor, media type, and URI type reviews.


No formal reviews are necessary for this document. The URI types were discussed at length during the early life of the document.


(13) Have all references within this document been identified as

either normative or informative?


Yes.


(14) Are there normative references to documents that are not ready for

advancement or are otherwise in an unclear state? If such normative

references exist, what is the plan for their completion?


There are no such references.


(15) Are there downward normative references references (see RFC 3967)?

If so, list these downward references to support the Area Director in the

Last Call procedure.


There is one downward normative reference that is listed by mistake and should be changed to informative.


(16) Will publication of this document change the status of any

existing RFCs? Are those RFCs listed on the title page header, listed

in the abstract, and discussed in the introduction? If the RFCs are not

listed in the Abstract and Introduction, explain why, and point to the

part of the document where the relationship of this document to the

other RFCs is discussed. If this information is not in the document,

explain why the WG considers it unnecessary.


Publication of this document will not change the status of any existing RFCs.


(17) Describe the Document Shepherd's review of the IANA considerations

section, especially with regard to its consistency with the body of the

document. Confirm that all protocol extensions that the document makes

are associated with the appropriate reservations in IANA registries.

Confirm that any referenced IANA registries have been clearly

identified. Confirm that newly created IANA registries include a

detailed specification of the initial contents for the registry, that

allocations procedures for future registrations are defined, and a

reasonable name for the new registry has been suggested (see RFC 5226).


The shepherd has verified that the document's IANA consideration section exists and is consistent with the body of the document. The document makes three requests of IANA: a v4 option number, a v6 option code, and a registry of location types (LuriTypes).


(18) List any new IANA registries that require Expert Review for future

allocations. Provide any public guidance that the IESG would find

useful in selecting the IANA Experts for these new registries.


No proposed registries require Expert Review.


(19) Describe reviews and automated checks performed by the Document

Shepherd to validate sections of the document written in a formal

language, such as XML code, BNF rules, MIB definitions, etc.


No such sections exist.

(1.a) The document shepherd for this document is Alissa Cooper. The document shepherd has personally reviewed the document and believes that this document is fit for publication.

(1.b) This document has been thoroughly reviewed by the GEOPRIV working group, as well as key members of the DHC working group.

(1.c) There are no specific areas within this document that necessitate additional external review, but it may be helpful to get another DHC reviewer during LC.

(1.d) The shepherd has no specific technical concerns with this document to which to call attention. It could benefit from an editorial review to ensure that the concepts are expressed in an understandable way to those outside the WG. No IPR disclosures have been filed against this document (although there was a message about IPR posted to IETF-Discussion on October 13, 2010).

(1.e) The GEOPRIV working group has discussed this document at length and reached consensus about its content. Disagreements within the group have been resolved.

(1.f) There have been no threatened appeals or expressions of extreme discontent against this document.

(1.g) The shepherd has checked the document for ID nits. The document's Trust boilerplate needs to be updated to the most recent version, and it has a form feed error. Otherwise, the document meets the checklist criteria and has no need for any additional reviews.

(1.h) The document's references are split into normative and informative sections. There are two references in the normative section, to RFC 4119 and RFC 5808, which should be in the informative section, and a reference in the informative section, to RFC 2616, which should be in the normative section. Once RFC 5808 is moved to the appropriate section there will be no downward references.

(1.i) The shepherd has verified that the document's IANA consideration section exists and is consistent with the body of the document. The document makes four requests of IANA: a v4 option number, a v6 option code, a registry of acceptable URI types, and a registry for location types.

(1.j) There are no instances of formal language in this document.

(1.k) Announcement Writeup:

Technical Summary:

This document creates a Dynamic Host Configuration Protocol (DHCP) Option for transmitting a Uniform Resource Identifier (URI) that points to a client's geolocation. The URI can be dereferenced in a separate transaction to obtain the client's geolocation.

Working Group Summary:

This document represents the consensus of the GEOPRIV working group. The document went through several revisions in order to establish a clear understanding of the security model surrounding location URIs passed via DHCP, but WG participants are now satisfied with the description of the model provided in the document.

Document Quality:

This document has been extensively reviewed by GEOPRIV participants.