One document matched: draft-ietf-mip6-mipext-advapi-03.txt
Differences from draft-ietf-mip6-mipext-advapi-02.txt
INTERNET-DRAFT Samita Chakrabarti
Expires: March, 2005 Erik Nordmark
Sun Microsystems, Inc.
September, 2004
Extension to Sockets API for Mobile IPv6
<draft-ietf-mip6-mipext-advapi-03.txt>
Status of this Memo
By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with
RFC 3668.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
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This Internet Draft expires March, 2005.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document describes data structures and API support for Mobile
IPv6 as an extension to Advanced Socket API for IPv6.
Mobility Support in IPv6 introduces mobility protocol header
for IPv6. It is expected that future Mobile IPv6 applications
and implementations may need to access Mobility binding messages
and Return Routability messages for diagnostic, packet accounting
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and local policy setting purposes. In order to provide portability
for Mobile IP applications that use sockets under IPv6,
standardization is needed for the Mobile IPv6 specific APIs.
This document provides mechanism for API access to retrieve and set
information for Mobility Header messages, Home Address destination
options and type 2 Routing header extension headers. It discusses
the common data structures and definitions that might be used by
advanced Mobile IPv6 socket applications.
Table of Contents
1. Introduction ............................................. 3
2. Common Structures and Definitions ........................ 4
2.1 The Mobility Header Data Structures ................. 5
2.2 Mobility Header Constants ........................... 8
2.3 IPv6 Home Address Destination Option ................ 10
2.4 Type 2 Routing Header ............................... 10
2.5 ICMP Mobile IPv6 Messages ........................... 11
2.6 IPv6 Neighbor Discovery Changes ..................... 12
3. Access to Home Address Destination Option and Routing Headers
................................ 13
3.1 Routing Header Access Functions ..................... 15
3.2 Home Address Destination Option Access Functions .... 16
4. Mobility Protocol Headers ............................... 17
4.1 Receiving and Sending Mobility Header Messages ....... 18
5. Protocols File ........................................... 19
6. IPv4-Mapped IPv6 Addresses ............................... 19
7. Security Considerations .................................. 19
8. IANA Considerations ...................................... 20
9. References ............................................... 20
10. Acknowledgement ......................................... 20
11. Changes from last revisions ............................. 20
12. Authors' Addresses ...................................... 21
13. Full Copyright Statement ................................ 22
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1. Introduction
Mobility Support in IPv6 [2] defines a new Mobility Protocol header,
Home Address destination option and a new Routing Header type.
It is expected that Mobile IPv6 user-level implementations and some
applications will need to access and process these IPv6 extension
headers. This document is an extension to existing Advanced Sockets
API document [1]; it addresses the IPv6 Sockets API for Mobile IPv6
protocol support. The target applications for this socket API is
believed to be the debugging and diagnostic applications as well as
some policy applications which would like to receive a copy of
protocol information at the application layer.
Note that user applications for transferring data between two
systems may not need to be mobility aware. Future IPv6 mobility
aware applications may use this socket API for per-packet
information for further processing at the application layer
program interface.
This document can be divided into the following parts.
1. Definitions of constants and structures for C programs that
capture the Mobile IPv6 packet formats on the wire. A common
definition of these is useful at least for packet snooping
appplications. This is captured in section 2.
2. Notes on how to use the IPv6 Advanced API to access Home Address
options and type 2 Routing Headers. This is captured in
section 3.
3. Notes on how user-level applications can observe MH (Mobility
Header) packets using raw sockets (in section 4). The IPv6 RAW
socket interface described in this document, allows applications
to receive MH packets whether or not the systems MH processing
takes place in the "kernel" or at the "user space".
4. Suggested name for /etc/protocols (in section 5).
It is anticipated that Mobile IPv6 will be used widely from mobile
devices to Server and Routing platforms. Thus it is useful to have
a standard API for portability of Mobile IPv6 applications on a
wide variety of platforms and operating systems.
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The packet information along with access to the extension headers
(Routing header and Destination options) are specified using the
"ancillary data" fields that were added to the 4.3BSD Reno sockets
API in 1990. The reason is that these ancillary data fields are
part of the Posix.1g standard and should therefore be adopted by
most vendors. This is in conformance with Advanced Sockets API for
IPv6 [1].
This document does not address application access to either the
authentication header or the encapsulating security payload header.
All examples in this document omit error checking in the favor of
brevity.
We note that many of the functions and socket options defined in this
document may have error returns that are not defined in this
document. Many of these possible error returns will be recognized
only as implementations proceed.
Data types in this document follow the Posix.1g format: intN_t means a
signed integer of exactly N bits (e.g., int16_t) and uintN_t means an
unsigned integer of exactly N bits (e.g., uint32_t).
This document provides guidelines on Mobile IPv6 socket applications
and believes that some other appropriate standardization body will
standardize the APIs along with other IPv6 advanced socket APIs.
2. Common Structures and Definitions
This API assumes that the fields in the protocol headers are left in
the network byte order, which is big-endian for the Internet
protocols. If not, then either these constants or the fields being
tested must be converted at run-time, using something like htons() or
htonl().
A new header file : <netinet/ip6mh.h>
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2.1. The Mobility Header Data Structures
2.1.1 The ip6_mh Structure
The following structure is defined as a result of including
<netinet/ip6mh.h>. This is fixed part of the Mobility Header.
struct ip6_mh {
uint8_t ip6mh_proto; /* NO_NXTHDR by default */
uint8_t ip6mh_hdrlen; /* Header Len in unit of 8 Octets
excluding the first 8 Octets */
uint8_t ip6mh_type; /* Type of Mobility Header */
uint8_t ip6mh_reserved; /* Reserved */
uint16_t ip6mh_cksum; /* Mobility Header Checksum */
/* Followed by type specific messages */
};
2.1.2 Binding Refresh Request Mobility Message
struct ip6_mh_binding_request {
struct ip6_mh ip6mhbr_hdr;
uint16_t ip6mhbr_reserved;
/* Followed by optional Mobility Options */
};
2.1.3 Home Address Test Init (HoTI) Message
struct ip6_mh_home_test_init {
struct ip6_mh ip6mhhti_hdr;
uint16_t ip6mhhti_reserved;
uint32_t ip6mhhti_cookie[2]; /* 64 bit Cookie by MN */
/* Followed by optional Mobility Options */
};
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2.1.4 Care-of Address Test Init (CoTI) Message
struct ip6_mh_careof_test_init {
struct ip6_mh ip6mhcti_hdr;
uint16_t ip6mhcti_reserved;
uint32_t ip6mhcti_cookie[2]; /* 64 bit Cookie by MN */
/* Followed by optional Mobility Options */
};
2.1.5 Home Address Test (HOT) Message
struct ip6_mh_home_test {
struct ip6_mh ip6mht_hdr;
uint16_t ip6mhht_nonce_index;
uint32_t ip6mhht_cookie[2]; /* Cookie from HOTI msg */
uint32_t ip6mhht_keygen[2]; /* 64 Bit Key by CN */
/* Followed by optional Mobility Options */
};
2.1.6 Care Of Address Test (COT) Message
struct ip6_mh_careof_test {
struct ip6_mh ip6mhct_hdr;
uint16_t ip6mhct_nonce_index;
uint32_t ip6mhct_cookie[2]; /* Cookie from COTI message */
uint32_t ip6mhct_keygen[2]; /* 64bit key by CN */
/* Followed by optional Mobility Options */
};
2.1.7 Binding Update Mobility Message
struct ip6_mh_binding_update {
struct ip6_mh ip6mhbu_hdr;
uint16_t ip6mhbu_seqno; /* Sequence Number */
uint16_t ip6mhbu_flags;
uint16_t ip6mhbu_lifetime; /* Time in unit of 4 sec */
/* Followed by optional Mobility Options */
};
/* Binding Update Flags, in network byte-order */
#define IP6_MH_BU_ACK 0x8000 /* Request a binding ack */
#define IP6_MH_BU_HOME 0x4000 /* Home Registration */
#define IP6_MH_BU_LLOCAL 0x2000 /* Link-local compatibility */
#define IP6_MH_BU_KEYM 0x1000 /* Key management mobility */
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2.1.8 Binding Acknowledgment Mobility Message
struct ip6_mh_binding_ack {
struct ip6_mh ip6mhba_hdr;
uint8_t ip6mhba_status; /* Status code */
uint8_t ip6mhba_flags;
uint16_t ip6mhba_seqno;
uint16_t ip6mhba_lifetime;
/* Followed by optional Mobility Options */
};
/* Binding Acknowledgement Flags */
#define IP6_MH_BA_KEYM 0x80 /* Key management mobility */
2.1.9 Binding Error Mobility Message
struct ip6_mh_binding_error {
struct ip6_mh ip6mhbe_hdr;
uint8_t ip6mhbe_status; /* Error Status */
uint8_t ip6mhbe_reserved;
struct in6_addr ip6mhbe_homeaddr;
/* Followed by optional Mobility Options */
};
2.1.10 Mobility Option TLV data structure
struct ip6_mh_opt {
uint8_t ip6mhopt_type; /* Option Type */
uint8_t ip6mhopt_len; /* Option Length */
/* Followed by variable length Option Data in bytes */
};
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2.1.11 Mobility Option Data Structures
2.1.11.1 Binding Refresh Advice
struct ip6_mh_opt_refresh_advice {
uint8_t ip6mora_type;
uint8_t ip6mora_len;
uint16_t ip6mora_interval; /* Refresh interval in 4 sec */
};
2.1.11.2 Alternate Care-of Address
struct ip6_mh_opt_altcoa {
uint8_t ip6moa_type;
uint8_t ip6moa_len;
struct in6_addr ip6moa_addr; /* Alternate Care-of Address */
};
2.1.11.3 Nonce Indices
struct ip6_mh_opt_nonce_index {
uint8_t ip6moni_type;
uint8_t ip6moni_len;
uint16_t ip6moni_home_nonce;
uint16_t ip6moni_coa_nonce;
};
2.1.11.4 Binding Authorization Data
struct ip6_mh_opt_auth_data {
uint8_t ip6moad_type;
uint8_t ip6moad_len;
uint8_t ip6moad_data[12];
};
2.2 Mobility Header Constants
IPv6 Next Header Value for Mobility:
<netinet/in.h>
#define IPPROTO_MH 135 /* IPv6 Mobility Header: IANA */
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Mobility Header Message Types:
<netinet/ip6mh.h>
#define IP6_MH_TYPE_BRR 0 /* Binding Refresh Request */
#define IP6_MH_TYPE_HOTI 1 /* HOTI Message */
#define IP6_MH_TYPE_COTI 2 /* COTI Message */
#define IP6_MH_TYPE_HOT 3 /* HOT Message */
#define IP6_MH_TYPE_COT 4 /* COT Message */
#define IP6_MH_TYPE_BU 5 /* Binding Update */
#define IP6_MH_TYPE_BACK 6 /* Binding ACK */
#define IP6_MH_TYPE_BERROR 7 /* Binding Error */
Mobility Header Message Option Types:
<netinet/ip6mh.h>
#define IP6_MHOPT_PAD1 0x00 /* PAD1 */
#define IP6_MHOPT_PADN 0x01 /* PADN */
#define IP6_MHOPT_BREFRESH 0x02 /* Binding Refresh */
#define IP6_MHOPT_ALTCOA 0x03 /* Alternate COA */
#define IP6_MHOPT_NONCEID 0x04 /* Nonce Index */
#define IP6_MHOPT_BAUTH 0x05 /* Binding Auth Data */
Status values accompanied with Mobility Binding Acknowledgement:
<netinet/ip6mh.h>
#define IP6_MH_BAS_ACCEPTED 0 /* BU accepted */
#define IP6_MH_BAS_PRFX_DISCOV 1 /* Accepted, but prefix
discovery Required */
#define IP6_MH_BAS_UNSPECIFIED 128 /* Reason unspecified */
#define IP6_MH_BAS_PROHIBIT 129 /* Administratively
prohibited */
#define IP6_MH_BAS_INSUFFICIENT 130 /* Insufficient
resources */
#define IP6_MH_BAS_HA_NOT_SUPPORTED 131 /* HA registration not
supported */
#define IP6_MH_BAS_NOT_HOME_SUBNET 132 /* Not Home subnet */
#define IP6_MH_BAS_NOT_HA 133 /* Not HA for this
mobile node */
#define IP6_MH_BAS_DAD_FAILED 134 /* DAD failed */
#define IP6_MH_BAS_SEQNO_BAD 135 /* Sequence number out
of range */
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#define IP6_MH_BAS_HOME_NI_EXPIRED 136 /* Expired Home nonce
index */
#define IP6_MH_BAS_COA_NI_EXPIRED 137 /* Expired Care-of
nonce index */
#define IP6_MH_BAS_NI_EXPIRED 138 /* Expired Nonce
Indices */
#define IP6_MH_BAS_REG_NOT_ALLOWED 139 /* Registration type
change disallowed */
Status values for the Binding Error mobility messages:
<netinet/ip6mh.h>
#define IP6_MH_BES_UNKNOWN_HAO 1 /* Unknown binding for HOA */
#define IP6_MH_BES_UNKNOWN_MH 2 /* Unknown MH Type */
2.3. IPv6 Home Address Destination Option
<netinet/ip6.h>
/* Home Address Destination Option */
struct ip6_opt_home_address {
uint8_t ip6oha_type;
uint8_t ip6oha_len;
uint8_t ip6oha_addr[16]; /* Home Address */
};
Option Type Definition:
#define IP6OPT_HOME_ADDRESS 0xc9 /* 11 0 01001 */
2.4 Type 2 Routing Header
<netinet/ip6.h>
/* Type 2 Routing header for Mobile IPv6 */
struct ip6_rthdr2 {
uint8_t ip6r2_nxt; /* next header */
uint8_t ip6r2_len; /* length : always 2 */
uint8_t ip6r2_type; /* always 2 */
uint8_t ip6r2_segleft; /* segments left: always 1 */
uint32_t ip6r2_reserved; /* reserved field */
struct in6_addr ip6r2_homeaddr; /* Home Address */
};
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2.5 New ICMP Messages for Mobile IPv6
ICMP message types and definitions for Mobile IPv6 are defined in
<netinet/icmp6.h>
#define MIP6_HA_DISCOVERY_REQUEST 144
#define MIP6_HA_DISCOVERY_REPLY 145
#define MIP6_PREFIX_SOLICIT 146
#define MIP6_PREFIX_ADVERT 147
The following data structures can be used for the ICMP message
types discussed in section 6.5 through 6.8 in the base Mobile
IPv6 [2] specification.
struct mip6_dhaad_req { /* Dynamic HA Address Discovery */
struct icmp6_hdr mip6_dhreq_hdr;
};
#define mip6_dhreq_type mip6_dhreq_hdr.icmp6_type
#define mip6_dhreq_code mip6_dhreq_hdr.icmp6_code
#define mip6_dhreq_cksum mip6_dhreq_hdr.icmp6_cksum
#define mip6_dhreq_id mip6_dhreq_hdr.icmp6_data16[0]
#define mip6_dhreq_reserved mip6_dhreq_hdr.icmp6_data16[1]
struct mip6_dhaad_rep { /* HA Address Discovery Reply */
struct icmp6_hdr mip6_dhrep_hdr;
/* Followed by Home Agent IPv6 addresses */
};
#define mip6_dhrep_type mip6_dhrep_hdr.icmp6_type
#define mip6_dhrep_code mip6_dhrep_hdr.icmp6_code
#define mip6_dhrep_cksum mip6_dhrep_hdr.icmp6_cksum
#define mip6_dhrep_id mip6_dhrep_hdr.icmp6_data16[0]
#define mip6_dhrep_reserved mip6_dhrep_hdr.icmp6_data16[1]
struct mip6_prefix_solicit { /* Mobile Prefix Solicitation */
struct icmp6_hdr mip6_ps_hdr;
};
#define mip6_ps_type mip6_ps_hdr.icmp6_type
#define mip6_ps_code mip6_ps_hdr.icmp6_code
#define mip6_ps_cksum mip6_ps_hdr.icmp6_cksum
#define mip6_ps_id mip6_ps_hdr.icmp6_data16[0]
#define mip6_ps_reserved mip6_ps_hdr.icmp6_data16[1]
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struct mip6_prefix_advert { /* Mobile Prefix Adverisements */
struct icmp6_hdr mip6_pa_hdr;
/* Followed by one or more PI options */
};
#define mip6_pa_type mip6_pa_hdr.icmp6_type
#define mip6_pa_code mip6_pa_hdr.icmp6_code
#define mip6_pa_cksum mip6_pa_hdr.icmp6_cksum
#define mip6_pa_id mip6_pa_hdr.icmp6_data16[0]
#define mip6_pa_flags_reserved mip6_pa_hdr.icmp6_data16[1]
#define MIP6_PA_FLAG_MANAGED 0x8000
#define MIP6_PA_FLAG_OTHER 0x4000
Prefix options are defined in IPv6 Advanced Socket API [1].
Mobile IPv6 Base specification [2] describes the modified
behavior in 'Modifications to IPv6 Neighbor Discovery' section.
Prefix Options for Mobile IP are defined in the following section.
2.6 IPv6 Neighbor Discovery Changes
IPv6 Neighbor Discovery changes are also defined in
<netinet/icmp6.h>
New 'Home Agent' flag in router advertisement:
#define ND_RA_FLAG_HOMEAGENT 0x20 /* Home Agent flag in RA */
New Router flag with prefix information of the home agent:
#define ND_OPT_PI_FLAG_ROUTER 0x20 /* Router flag in PI */
As per Mobile IPv6 specification [2] a Home Agent MUST include
at least one prefix option with the Rouer Address (R) bit set.
Advanced Socket API [1] defines data structure for prefix option
as follows:
struct nd_opt_prefix_info { /* prefix information */
uint8_t nd_opt_pi_type;
uint8_t nd_opt_pi_len;
uint8_t nd_opt_pi_prefix_len;
uint8_t nd_opt_pi_flags_reserved;
uint32_t nd_opt_pi_valid_time;
uint32_t nd_opt_pi_preferred_time;
uint32_t nd_opt_pi_reserved2;
struct in6_addr nd_opt_pi_prefix;
};
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New advertisement interval option and home agent information
options are defined in Mobile IPv6 [2] base specification.
struct nd_opt_adv_interval { /* Advertisement interval option */
uint8_t nd_opt_ai_type;
uint8_t nd_opt_ai_len;
uint16_t nd_opt_ai_reserved;
uint32_t nd_opt_ai_interval;
};
The option types for the new Mobile IPv6 specific options:
#define ND_OPT_ADV_INTERVAL 7 /* Adv Interval Option */
#define ND_OPT_HA_INFORMATION 8 /* HA Information option */
struct nd_opt_homeagent_info { /* Home Agent information */
uint8_t nd_opt_hai_type;
uint8_t nd_opt_hai_len;
uint16_t nd_opt_hai_reserved;
uint16_t nd_opt_hai_preference;
uint16_t nd_opt_hai_lifetime;
};
3. Access to Home Address Destination Option and Routing Headers
Applications that need to be able to access home address destination
option and routing header type 2 information should use the same
mechanism defined in Advanced Sockets API for IPv6 in section 4.
In order to receive Home Address destination option or Route Header
Type 2 extension header, application must call setsockopt() to turn
on the corresponding flag:
int on = 1;
setsockopt(fd, IPPROTO_IPV6, IPV6_RECVRTHDR, &on, sizeof(on));
setsockopt(fd, IPPROTO_IPV6, IPV6_RECVDSTOPTS, &on, sizeof(on));
When any of these options are enabled, the corresponding data is
returned as control information by recvmsg(), as one or more
ancillary data objects. Receiving the above information for TCP
applications is not defined in this document (see section 4.1 of
Advanced Sockets API for IPv6 [1]).
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For sending Home Address destination option, ancillary data can be
used to specify the option content for a single datagram. This
only applies to datagram and raw sockets; not to TCP sockets.
Advanced API [1] document restricts one IPV6_xxx ancillary data
object for a particular extension header in the control buffer.
Thus there would be a single ancillary data object for Home address
destination option in a ancillary data buffer. If the kernel
implementation supports this API, it is responsible for extracting
the Home address destination option data object and placing it as
destination option extension header in compliance with section
6.3 of Mobile IPv6 [2] base specification.
For TCP data packets with Home Address destination option may be
used with "sticky" option for all transmitted packets. However,
at this point, it is unknown why an application would want to
set Home Address option or Route Header Type 2 extension header
along with its data packets as Mobile IPv6 protocol takes care of
them transparently at the protocol stack.
However, the following socket option parameters and cmsghdr fields
may be used for sending.
opt level/ optname/ optval/
cmsg_level cmsg_type cmsg_data[]
------------ ------------ ------------------------
IPPROTO_IPV6 IPV6_DSTOPTS ip6_dest structure
IPPROTO_IPV6 IPV6_RTHDR ip6_rthdr structure
Some IPv6 implementations may support "sticky" options [1] for IPv6
destination option for datagram sockets.
Behavior of legacy IPv6 socket applications:
Mobile IPv6 un-aware applications or existing IPv6 socket
applications that do not know about the new routing header type 2
and Home Address destination option, SHOULD ignore these new
routing header type and Home Address destination option upon
receipt of them.
3.1 Routing Header access functions
While accessing Routing header Type 2 extension header, one MUST
use type = 2 and segment = 1. The following existing functions
defined in Advanced API for IPv6 Sockets [1] are supported
for Mobile IPv6 applications for sending and receiving Routing
Header Type 2 headers:
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For sending:
size_t inet6_rth_space(int type, int segments);
void *inet6_rth_init(void *bp, int bp_len, int type, int segments);
int inet6_rth_add(void *bp, const struct in6_addr *addr);
For receiving:
int inet6_rth_segments(const void *bp);
struct in6_addr *inet6_rth_getaddr(const void *bp, int index);
NOTE: Reversing operation is not possible using Route Header Type 2
extension header.
Detail description and examples of accessing a IPv6 Routing Header
are discussed in Advanced Sockets API for IPv6 [1].
However, section 7 of Adavanced API for IPv6 Sockets [1] indicates
that multiple types of routing headers can be received as multiple
ancillary data objects to the application (with cmsg_type set to
IPV6_RTHDR). Currently there is no API functions defined to return
the routing header type, hence this document defines a function
for getting the type of the received routing header.
int inet6_rth_gettype(const void *bp);
3.1.1 Content of Routing Header Type 2
It is assumed that no portable applications will send routing hader
Type 2 ancillary data from application layer, since many
implementations take care of that at the kernel layer and may not
support API for sending routing header type 2. However, if any
Mobile IPv6 implementation requires to send/process pakcets at the
user level, it can use the API mentioned in section 3.1 and set
value of routing header as the home-address as specified in [2].
For user level applications that receive routing header type 2,
inet6_rth_getaddr() returns the Care-Of-Address or the original
destination address of the received packet. This is in compliance
with the existing Routing header Type=0 processing for IPv6 [1].
Thus on the receive side, the socket application will always
receive data packets at its original home-address.
The implementations are responsible for processing the routing
header type 2 packet as per Mobile IPv6 RFC [2], before passing
the routing header type 2 information to the Socket API.
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3.2 Home Address Destination Option access functions
The application must enable the IPV6_RECVDSTOPTS socket option in
order to receive the Home Address destination option:
int on = 1;
setsockopt(fd, IPPROTO_IPV6, IPV6_RECVDSTOPTS, &on, sizeof(on));
Each Destination option header is returned as one ancillary data
object described by a cmsghdr structure with cmsg_level set to
IPPROTO_IPV6 and cmsg_type set to IPV6_DSTOPTS.
The receive side Home Address destination option is further
processed by calling the inet6_opt_next(), inet6_opt_find(),
and inet6_opt_get_value() functions as defined in Advanced API
for IPv6 sockets [1].
This document assumes that portable Mobile IPv6 applications will
not send Home Address Destination Option from the application level,
as many Mobile IPv6 implementations take care of sending Home Address
option and routing header type 2 at the kernel. However, some
embedded software implementations may require to implement the IPv6
packet processing/sending at the user level; those implementations
may choose to provide API spport for sending home-address option
at the application layer. For API which support sending Home Address
destination options, they are normally constructed by using the
inet6_opt_init(), inet6_opt_append(), inet6_opt_finish(), and
inet6_opt_set_val() functions, described in Section 10 of Advanced
sockets API for IPv6 [1].
3.2.1 Content of Home Address Destination option
The received ancillary data object for Home Address destination
option SHOULD contain the Care-Of-Address of the mobile node. It
is assumed that the initial processing of the Home Address
destination option will verify the validity of home-address as
described in 6.3 and 9.5 of Mobile IPv6 Specification [2] and
swap the source address of the packet (COA) with the content of
Home Address destination option.
All portable Mobile IPv6 aware applications MUST receive the
home-address as source address of the incoming packet from the
socket-level functions like recvfrom(), recvmsg(), accept() and
getpeername(). This is necessary for:
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- maintaining consistency between simple user-level
applications running between mobile nodes and the
diagnostic applications on home-agent or on
correspondent node, which use this API.
- obtaining the COA address of the mobile node when
Home Address destination option is used.
- maintaining consistency of existing IPv6 Socket APIs
and processing of Home Address destination option.
If an implementation supports send-side Home Address destination
API, then it must follow the same rule for data content as
specified in Mobile IPv6 RFC [2] for sending home-address option.
Thus the home-address option will contain the home-address and
the implementation will use the care-of-address as the source
address of the outgoing packet.
4. Mobility Protocol Headers
Mobile IPv6 [2] defines a new IPv6 protocol header to carry mobility
messages between Mobile Nodes, Home Agents and Correspondent Nodes.
These protocol headers carry Mobile IPv6 Binding messages as well as
Return Routability [2] messages. Currently the specification [2]
does not allow transport packets (piggybacking) along with the
mobility messages. Thus the mobility protocol header can be
accessed through a IPv6 RAW socket. A IPv6 RAW socket that is opened
for protocol IPPROTO_MH should always be able to see all the MH
(Mobility Header) packets. It is possible that future applications
may implement part of Mobile IPv6 signal processing at the
application level. Having a RAW socket interface may also enable
an application to execute the Return Routability protocol or other
future authentication protocol involving mobility header at the user
level.
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4.1 Receiving and Sending Mobility Header Messages
This specification recommends IPv6 RAW sockets mechanism to send
and receive Mobility Header (MH) packets. The behavior is similar to
ICMPV6 processing, where kernel passes a copy of the mobility header
packet to the receiving socket. Depending on the implementation
kernel may process the mobility header as well in addition to passing
the mobility header to the application.
In order to comply with the restriction in Advanced Sockets API for
IPv6 [1], applications should set IPV6_CHECKSUM socket option with
IPPROTO_MH protocol RAW Sockets. A Mobile IPv6 implementation
that supports Mobile IPv6 API, must implement Mobility Header
API checksum calculation by default at the kernel for both incoming
and outbound path. A Mobile IPv6 implementation must not return error
on IPV6_CHECKSUM socket option setting, even if the socket option is
a NO-OP function for that implementation because it verifies the
checksum at the kernel level. Mobility Header checksum procedure
is described in Mobile IPv6 Protocol [2] specification.
Again, it is recommended that the applications set the IPV6_CHECKSUM
socket option along with the RAW sockets for IPPROTO_MH protocol,
for application portability.
As an example, a program that wants to send or receive mobility
header protocol(MH), could open a socket as following:
fd = socket(AF_INET6, SOCK_RAW, IPPROTO_MH);
int offset = 4;
setsockopt(fd, IPPROTO_IPV6, IPV6_CHECKSUM, &offset,
sizeof(offset));
For example, if an implementation likes to handle HOTI/HOT and
COTI/COT message processing, it can do so by using IPv6 RAW Sockets
for IPPROTO_MH at the application layer.
The same application may also set IPV6_RECVDSTOPTS socket option for
receiving home-address option in a binding update [2] from the mobile
node.
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5. Protocols File
Many hosts provide the file /etc/protocols that contains the names
of the various IP protocols and their protocol numbers. The protocol
numbers are obtained through function getprotoXXX() functions.
The following addition should be made to the /etc/protocols file,
in addition to what is defined in section 2.4 of Advanced Sockets
API for IPv6 [1].
The protocol number for Mobility Header:
(http://www.iana.org/assignments/protocol-numbers)
ipv6-mh 135 # Mobility Protocol Header
6. IPv4-Mapped IPv6 Addresses
The same rule applies as described in section 13 of Advanced Sockets
API for IPv6 [1]. Thus processing of IPv4-mapped IPv6 addresses
for the Mobile IPv6 specific socket options are out of scope of this
document.
7. Security Considerations
The setting of Home Address Destination option and Route Header
Type 2 IPV6_RTHDR socket option may not be allowed at the
application level in order to prevent denial-of-service attacks
or man in the middle attacks by hackers.
Sending and receiving of mobility header messages are possible by
IPv6 RAW sockets. Thus it is assumed that this operation is only
possible by priviledged users. However, this API does not prevent
the existing security threat from a hacker by sending bogus mobility
header or other IPv6 packets using Home Address option and Type 2
Routing Header extension.
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8. IANA Considerations
This document does not define a new protocol. However, it uses
Mobility Header Protocol for IPv6 to define an API for
/etc/protocols file.
(ref: http://www.iana.org/assignments/protocol-numbers)
9. References
Normative References:
[1] Stevens, W. R, Thomas, M., Nordmark, E., Jinmei, T., "Advanced
Sockets API for IPv6", RFC 3542, May 2003
April 19, 2002.
[2] Johnson, D., Perkins, C., Arkko, J., "Mobility Support in IPv6",
RFC3775, June, 2004.
Informative References:
[3] Deering, S., Hinden, R., "Internet Protocol, Version 6
(IPv6), Specification", RFC 2460, Dec. 1998.
10. Acknowledgement
Thanks to Brian Haley for the thorough review of this draft and many
helpful comments. Keiichi Shima, Alexandru Petrescu, Ryuji Wakikawa,
Vijay Devarapalli, Jim Bound, Suvidh Mathur, Karen Nielsen, Mark
Brost, Vladislav Yasevich and other mobile-ip working group members
provided valuable input. Antti Tuominen suggested the routing header
type function for this API document.
11. Changes from last revisions
Version 03 changes:
* Modified new ICMPv6 type definition values to match RFC3775.
Version 02 changes:
* Added section 3.1.1 and 3.2.1 to clarify content of routing header
type 2 and destination options.
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* Clarified existing socket application behavior in section 3.
* Updated introduction to clarify scope of the applications wrt
this API
* Added IANA section and Full Copyright statement and internet
draft boiler plate
* Updated acknowledgement section and fixed typo etc.
The following changes were made in 01 version per feedback from the
implementors at Connectathon 2004.
* Section 2.1.11.2 now defines alternate COA address data structure
as struct in6_addr for consistency. It was defined as 16 unit
of bytes.
* Added Binding Update Authdata of 12 bytes in the
struct ip6_mh_opt_auth_data
* Added a new function inet6_rth_gettype() in section 3.1 in order
to distinguish routing header type 2 ancillary data items from
type 0 routing header ancillary data items on the receive side.
* Updated the Acknowledgement and Authors' address section
12. Authors' Addresses
Samita Chakrabarti
Sun Microsystems, Inc.
4150 Network Circle, UMPK17-203
Santa Clara, CA 95054, USA
Email: samita.chakrabarti@Sun.com
Erik Nordmark
Sun Microsystems Laboratories
4150 Network Circle, UMPK17-308
Santa Clara, CA 95054, USA
Email: Erik.Nordmark@sun.com
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13. Full Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
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such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
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rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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