Internet DRAFT - draft-yao-dnsext-bname
draft-yao-dnsext-bname
Network Working Group J. Yao
Internet-Draft X. Lee
Intended status: Standards Track CNNIC
Expires: November 24, 2016 P. Vixie
CNNIC-Farsight Joint Laboratory
May 23, 2016
Bundled DNS Name Redirection
draft-yao-dnsext-bname-06.txt
Abstract
This document defines a new DNS Resource Record called "BNAME", which
provides the capability to map itself and its subtree of the DNS name
space to another domain. It differs from the CNAME record which only
maps a single node of the DNS name space, from the DNAME which only
maps the subtree of the DNS name space to another domain.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 24, 2016.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Yao, et al. Expires November 24, 2016 [Page 1]
Internet-Draft bname May 2016
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The BNAME Resource Record . . . . . . . . . . . . . . . . . . 3
3.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. The BNAME Substitution . . . . . . . . . . . . . . . . . 4
3.3. The BNAME Rules . . . . . . . . . . . . . . . . . . . . . 4
3.4. BNAME Examples . . . . . . . . . . . . . . . . . . . . . 4
4. Query Processing . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Processing by Servers . . . . . . . . . . . . . . . . . . 5
4.2. Processing by Resolvers . . . . . . . . . . . . . . . . . 8
5. Signaling of BNAME . . . . . . . . . . . . . . . . . . . . . 9
6. BNAME in DNSSEC . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. BNAME-aware Resolvers . . . . . . . . . . . . . . . . . . 10
6.2. Compatibility with BNAME unaware resolvers . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
10. Change History . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. draft-yao-dnsext-bname: Version 00 . . . . . . . . . . . 11
10.2. draft-yao-dnsext-bname: Version 01 . . . . . . . . . . . 11
10.3. draft-yao-dnsext-bname: Version 02 . . . . . . . . . . . 12
10.4. draft-yao-dnsext-bname: Version 03 . . . . . . . . . . . 12
10.5. draft-yao-dnsext-bname: Version 04 . . . . . . . . . . . 12
10.6. draft-yao-dnsext-bname: Version 05 . . . . . . . . . . . 12
10.7. draft-yao-dnsext-bname: Version 06 . . . . . . . . . . . 12
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
Yao, et al. Expires November 24, 2016 [Page 2]
Internet-Draft bname May 2016
1. Introduction
For some names, the internet users may want them to be identical in
the DNS resolution. For example, exmaple.ong==example.ngo,
cnnic.cn==cnnic.net.cn. The BNAME represents for bundle names. This
document defines a new DNS Resource Record called "BNAME", which
provides the capability to map an entire tree of the DNS name space
to another domain. It means that the BNAME redirects both itself and
its descendants to its owner. The DNAME [RFC6672] does not redirect
itself, only the descendants. The domain name that owns a DNAME
record is allowed to have other resource record types at that domain
name. The domain name that owns a BNAME record is not allowed to
have other resource record types at that domain name unless they are
the DNSSEC related resource record types defined in [RFC4033],
[RFC4034], [RFC4035] and [RFC5155]. A server MAY refuse to load a
zone that has data at a sub-domain of a domain name owning a BNAME RR
or that has other data except the DNSSEC related resource record
types and BNAME at that name. BNAME is a singleton type, meaning
only one BNAME is allowed per name except the DNSSEC related resource
record types. Resolvers, servers and zone content administrators
should be cautious that usage of BNAME or its combination with CNAME
or DNAME may lead to form loops. The loops should be avoided.
1.1. Terminology
All the basic terms used in this specification are defined in the
documents [RFC1034], [RFC1035] and [RFC2672].
2. Motivation
CNAME can redirect itself to other name. DNAME can rediret its
children to other name. In practice, many names need redirect itself
and its children to another name. For example, we expect
exmaple.TLD1 to be identical with the example.TLD2 in the DNS
resolution. Without the BNAME mechanism, current mechanisms such as
DNAME or CNAME are not enough capable to redirect itself and its
children to another name at the same time.
3. The BNAME Resource Record
3.1. Format
The BNAME RR has mnemonic BNAME and type code xx (decimal). Its
RDATA is comprised of a single field, <target>, which contains a
fully qualified domain name that must be sent in uncompressed form
[RFC1035], [RFC3597]. The <target> field MUST be present. The
presentation format of <target> is that of a domain name [RFC1035].
The wildcards in the BNAME RR SHOULD NOT be used.
Yao, et al. Expires November 24, 2016 [Page 3]
Internet-Draft bname May 2016
<owner> <ttl> <class> BNAME <target>
The effect of the BNAME RR is the substitution of the record's
<target> for its owner name, as a suffix of a domain name. This
substitution has to be applied for every BNAME RR found in the
resolution process, which allows fairly lengthy valid chains of BNAME
RRs.
3.2. The BNAME Substitution
A BNAME substitution is performed by replacing the suffix labels of
the name or the whole name being sought matching the owner name of
the BNAME resource record with the string of labels in the RDATA
field. The matching labels end with the root label in all cases.
Only whole labels are replaced.
3.3. The BNAME Rules
There are two rules which governs the use of BNAMEs in a zone file.
The first one is that there SHOULD be no descendants under the owner
of the BNAME. The second one is that no resource records can co-
exist with the BNAME for the same name except the DNSSEC related
resource record types. It means that if a BNAME RR is present at a
node N, there MUST be no other data except the DNSSEC related
resource record types at N and no data at any descendant of N. This
restriction applies only to records of the same class as the BNAME
record.
3.4. BNAME Examples
The table below shows some examples of the BNAME usage.
QNAME owner BNAME target result
---------------- -------------- -------------- -----------------
com. example.com. example.net. <no match>
com. com. net. net.
example.com. example.com. example.net. example.net.
a.example.com. example.com. example.net. a.example.net.
a.b.example.com. example.com. example.net. a.b.example.net.
ab.example.com. b.example.com. example.net. <no match>
bar.example.com. example.com. example.net. bar.example.net.
a.b.example.com. b.example.com. example.net. a.example.net.
a.example.com. example.com. b.example.net. a.b.example.net.
Table 1. BNAME Usage Examples.
Yao, et al. Expires November 24, 2016 [Page 4]
Internet-Draft bname May 2016
If the owner name of the CNAME RR is regarded as the target of the MX
RR, it may cause some problems. Some mail servers may directly
connect the owner name of the CNAME instead of the name pointed by
CNAME for mail delivery and cause the undelivery of the mails. BNAME
has the similar problems with CNAME. This document specifies that
the owner name of the BNAME should not be the targets of some RRs
such as MX, SRV and PTR. In case that the owner name of the BNAME RR
is the target of some RRs, it should be cautious.
4. Query Processing
To exploit the BNAME mechanism the name resolution algorithms
[RFC1034] must be modified slightly for both servers and resolvers.
Both modified algorithms incorporate the operation of making a
substitution on a name (either QNAME or SNAME) under control of a
BNAME record. This operation will be referred to as "the BNAME
substitution".
4.1. Processing by Servers
For a server performing non-recursive service steps 3.a, 3.c and 4 of
section 4.3.2 [RFC1034] are changed to check for a BNAME record, and
to return certain BNAME records from zone data and the cache.
If the owner name of the bname is the suffix of the name queryed, or
same, when preparing a response, a server performing a BNAME
substitution will in all cases include the relevant BNAME RR in the
answer section. A CNAME RR is synthesized and included in the answer
section. This will help the client to reach the correct DNS data.
The server MUST know BNAME. The provided synthesized CNAME RR if
there has one, MUST have
The same CLASS as the QCLASS of the query,
TTL equal to the corresponding BNAME RR,
An <owner> equal to the QNAME in effect at the moment the BNAME RR
was encountered, and
An RDATA field containing the new QNAME formed by the action of
the BNAME substitution.
Yao, et al. Expires November 24, 2016 [Page 5]
Internet-Draft bname May 2016
The revised server algorithm is:
1. Set or clear the value of recursion available in the response
depending on whether the name server is willing to provide
recursive service. If recursive service is available and
requested via the RD bit in the query, go to step 5, otherwise
step 2.
2. Search the available zones for the zone which is the nearest
ancestor to QNAME. If such a zone is found, go to step 3,
otherwise step 4.
3. Start matching down, label by label, in the zone. The matching
process can terminate several ways:
Yao, et al. Expires November 24, 2016 [Page 6]
Internet-Draft bname May 2016
a. If the whole of QNAME is matched, we have found the node.
If the data at the node is a CNAME, and QTYPE doesn't match
CNAME, copy the CNAME RR into the answer section of the
response, change QNAME to the canonical name in the CNAME RR,
and go back to step 1.
If the data at the node is a BNAME, and QTYPE doesn't
match BNAME, copy the BNAME RR
and also a corresponding,
synthesized CNAME RR
into the answer section of the
response, change QNAME to the name carried as RDATA in
the BNAME RR, and go back to step 1.
Otherwise, copy all RRs which match QTYPE into the answer
section and go to step 6.
b. If a match would take us out of the authoritative data, we have
a referral. This happens when we encounter a node with NS RRs
marking cuts along the bottom of a zone.
Copy the NS RRs for the subzone into the authority section of
the reply. Put whatever addresses are available into the
additional section, using glue RRs if the addresses are not
available from authoritative data or the cache. Go to step 4.
c. If at some label, a match is impossible (i.e., the
corresponding label does not exist), look to see whether the
last label matched has a BNAME record.
If a BNAME record exists at that point, copy that record into
the answer section. If substitution of its <target> for its
<owner> in QNAME would overflow the legal size for a <domain-
name>, set RCODE to YXDOMAIN [RFC2136] and exit; otherwise
perform the substitution and continue. The server SHOULD
synthesize a corresponding CNAME record and include it in the
answer section. Go back to step 1.
If there was no BNAME record, look to see if the "*" label
exists.
Yao, et al. Expires November 24, 2016 [Page 7]
Internet-Draft bname May 2016
If the "*" label does not exist, check whether the name we are
looking for is the original QNAME in the query or a name we
have followed due to a CNAME. If the name is original, set an
authoritative name error in the response and exit. Otherwise
just exit.
If the "*" label does exist, match RRs at that node against
QTYPE. If any match, copy them into the answer section, but
set the owner of the RR to be QNAME, and not the node with the
"*" label. Go to step 6.
4. Start matching down in the cache. If QNAME is found in the cache,
copy all RRs attached to it that match QTYPE or BNAME RR into the answer
section. If QNAME is not found in the cache but a BNAME record is
present at an ancestor of QNAME, copy that BNAME record into the
answer section. If there was no delegation from authoritative
data, look for the best one from the cache, and put it in the
authority section. Go to step 6.
5. Use the local resolver or a copy of its algorithm (see resolver
section of this memo) to answer the query. Store the results,
including any intermediate CNAMEs and BNAMEs, in the answer
section of the response.
6. Using local data only, attempt to add other RRs which may be
useful to the additional section of the query. Exit.
Note that there will be at most one ancestor with a BNAME as
described in step 4 unless some zone's data is in violation of the
no-descendants limitation of the owner of the BNAME. If
some descedants are found when a BNAME record is encountered,
the server can stop search of step 3c or
step 4.
4.2. Processing by Resolvers
A resolver or a server providing recursive service must be modified
to treat a BNAME as somewhat analogous to a CNAME. The resolver
algorithm of [RFC1034] section 5.3.3 is modified to renumber step 4.d
as 4.e and insert a new 4.d. The complete algorithm becomes:
Yao, et al. Expires November 24, 2016 [Page 8]
Internet-Draft bname May 2016
1. See if the answer is in local information, and if so return it to
the client.
2. Find the best servers to ask.
3. Send them queries until one returns a response.
4. Analyze the response, either:
a. if the response answers the question or contains a name error,
cache the data as well as returning it back to the client.
b. if the response contains a better delegation to other servers,
cache the delegation information, and go to step 2.
c. if the response shows a CNAME and that is not the answer
itself, cache the CNAME, change the SNAME to the canonical name
in the CNAME RR and go to step 1.
d. if the response shows a BNAME and that is not the answer
itself, cache the BNAME and the CNAME if there has one.
If substitution of the BNAME's
<target> for its <owner> in the SNAME would overflow the legal
size for a <domain-name>, return an implementation-dependent
error to the application; otherwise perform the substitution
and go to step 1.
e. if the response shows a server failure or other bizarre
contents, delete the server from the SLIST and go back to step
3.
A resolver or recursive server which understands BNAME records but
sends non-extended queries MUST augment step 4.c by deleting from the
reply any CNAME records which have an <owner> which is a subdomain of
the <owner> of any BNAME record in the response.
5. Signaling of BNAME
A new UB (Understand BNAME) bit in the EDNS flags field [RFC2671]can
be used to signal that the resolvers can understand BNAME. BNAME
aware resolvers can set the Understand-BNAME (UB bit) to receive a
response without the synthesized CNAME or DNAME. The UB bit is part
of the EDNS extended RCODE and Flags field[RFC2671]. Resolvers MUST
set this in a query to know BNAME.
Below are Updated EDNS extended RCODE and Flags fields [RFC2671]:
Yao, et al. Expires November 24, 2016 [Page 9]
Internet-Draft bname May 2016
+0 (MSB) +1 (LSB)
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
0: | EXTENDED-RCODE | VERSION |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
2: |DO|UB| Z |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
6. BNAME in DNSSEC
6.1. BNAME-aware Resolvers
With the deployment of DNSSEC, more and more servers and resolvers
will support DNSSEC. In order to make BNAME valid in DNSSEC
verification, the DNSSEC enabled resolvers and servers MUST support
BNAME.
The BNAME aware resolvers MUST set DO bit and UB bit when sending
DNSSEC queries to servers. The synthesized CNAME in the answer
section for the BNAME may not be signed if there has one. DNSSEC
validators MUST understand BNAME, verify the BNAME and then checking
that the CNAME was properly synthesized in order to verify the
synthesized CNAME. The BNAME enabled resolver (validator) should do
somewhat analogous to a CNAME for further query.
In any negative response, the NSEC or NSEC3 [RFC5155] record type bit
map SHOULD be checked to see that there was no BNAME that could have
been applied. If the BNAME bit in the type bit map is set and the
query type is not BNAME, then BNAME substitution should have been
done.
6.2. Compatibility with BNAME unaware resolvers
In order to have a compatibility with BNAME unaware resolvers, the
BNAME aware servers receiving queries from BNAME unaware resolvers
with DO bit set but no UB bit set should do the following things if
BNAME is put into the response and the query type is not BNAME:
o Issue the corresponding CNAME signature when querying the same
owner name with BNAME based on the question name, and put into the
answer section.
o Issue the corresponding DNAME and its signature when querying the
children of the same owner name of BNAME based on the question
name, and put into the answer section.
Yao, et al. Expires November 24, 2016 [Page 10]
Internet-Draft bname May 2016
In order to satisfy the BNAME query, the server should prepares the
siganture of CNAME and DNAME of the owner name of the BNAME
beforehand.
The BNAME unaware resolvers with DNSSEC enabled are supposed to
neglect the BNAME RR. If the corresponding CNAME signature is found,
the validators will use it to verify the CNAME. If the corresponding
CNAME signature is not found, but the corresponding DNAME with
signature is found, the validators will use it to verify the CNAME.
7. IANA Considerations
This document updates the IANA registry "DOMAIN NAME SYSTEM
PARAMETERS" (http://www.iana.org/assignments/dns-parameters) in sub-
registry "TYPES", by defining one new type. IANA is requested to
assign the number to BNAME.
8. Security Considerations
CNAME, DNAME, and BNAME may form a loop chain, which will cause the
unresolvable of some names. The BNAME should avoid point to some
name which is the owner name of CNAME or DNAME RRs.
9. Acknowledgements
Because the BNAME is very similar to DNAME, the authors learn a lot
from [RFC2672]. Many ideas are from the discussion in the DNSOP and
DNSEXT mailling list. Thanks a lot to all in the list. Many
important comments and suggestions are contributed by many members of
the DNSEXT and DNSOP WGs. The authors especially thanks the
following ones:Niall O'Reilly, Glen Zorn, Mark Andrews, George
Barwood,Olafur Gudmundsson, Sun Guonian and Hanfeng for improving
this document.
10. Change History
[[CREF1: RFC Editor: Please remove this section.]]
10.1. draft-yao-dnsext-bname: Version 00
o Bundle DNS Name Redirection
10.2. draft-yao-dnsext-bname: Version 01
o Improve the algorithm
o Improve the text
Yao, et al. Expires November 24, 2016 [Page 11]
Internet-Draft bname May 2016
10.3. draft-yao-dnsext-bname: Version 02
o Add the DNSSEC discussion
o Improve the text
10.4. draft-yao-dnsext-bname: Version 03
o Update the DNSSEC discussion
o Update the IANA consideration
10.5. draft-yao-dnsext-bname: Version 04
o Improve the text
10.6. draft-yao-dnsext-bname: Version 05
o add section: bname examples
o add section: Signaling of BNAME
10.7. draft-yao-dnsext-bname: Version 06
o redesign with DNSSEC verification
o Issue the corresponding CNAME signature when querying the same
owner name with BNAME based on the question name when UB is not
set
o Issue the corresponding DNAME and its signature when querying the
children of the same owner name of BNAME based on the question
name when UB is not set
11. References
11.1. Normative References
[ASCII] American National Standards Institute (formerly United
States of America Standards Institute), "USA Code for
Information Interchange", ANSI X3.4-1968, 1968.
[EDNS0] Vixie, P., "Extension Mechanisms for DNS (EDNS0)",
RFC 2671, August 1999.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>.
Yao, et al. Expires November 24, 2016 [Page 12]
Internet-Draft bname May 2016
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)",
RFC 2136, DOI 10.17487/RFC2136, April 1997,
<http://www.rfc-editor.org/info/rfc2136>.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)",
RFC 2671, DOI 10.17487/RFC2671, August 1999,
<http://www.rfc-editor.org/info/rfc2671>.
[RFC2672] Crawford, M., "Non-Terminal DNS Name Redirection",
RFC 2672, DOI 10.17487/RFC2672, August 1999,
<http://www.rfc-editor.org/info/rfc2672>.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record
(RR) Types", RFC 3597, DOI 10.17487/RFC3597, September
2003, <http://www.rfc-editor.org/info/rfc3597>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 3629, November 2003.
[RFC3743] Konishi, K., Huang, K., Qian, H., and Y. Ko, "Joint
Engineering Team (JET) Guidelines for Internationalized
Domain Names (IDN) Registration and Administration for
Chinese, Japanese, and Korean", RFC 3743,
DOI 10.17487/RFC3743, April 2004,
<http://www.rfc-editor.org/info/rfc3743>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005,
<http://www.rfc-editor.org/info/rfc4033>.
Yao, et al. Expires November 24, 2016 [Page 13]
Internet-Draft bname May 2016
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<http://www.rfc-editor.org/info/rfc4034>.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<http://www.rfc-editor.org/info/rfc4035>.
[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
<http://www.rfc-editor.org/info/rfc5155>.
[RFC6672] Rose, S. and W. Wijngaards, "DNAME Redirection in the
DNS", RFC 6672, DOI 10.17487/RFC6672, June 2012,
<http://www.rfc-editor.org/info/rfc6672>.
11.2. Informative References
[RFC2672bis]
Rose, S. and W. Wijngaards, "Update to DNAME Redirection
in the DNS", ietf-dnsext-rfc2672bis-dname-17.txt (work in
progress), 6 2009.
Authors' Addresses
Jiankang YAO
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing
Phone: +86 10 58813007
Email: yaojk@cnnic.cn
Xiaodong LEE
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing
Phone: +86 10 58813020
Email: xl@cnnic.cn
Yao, et al. Expires November 24, 2016 [Page 14]
Internet-Draft bname May 2016
Paul Vixie
CNNIC-Farsight Joint Laboratory
4 South 4th Street,Zhongguancun,Haidian District
Beijing, Beijing 100190
China
Phone: +1 650 489 7919
Email: vixie@fsi.io
Yao, et al. Expires November 24, 2016 [Page 15]
