Hello:
draft-chakrabarti-mobileip-mipext-advapi-01.txt has been submitted
at the mobileip working group. This draft discusses new data structures
for mobility headers, changes in neighbor discovery API and accessing
mobility headers, home address destination options and type 2 routing
headers.
The updates to the draft will be discussed in the MIPv6 working group.
The updates of the draft was based on the working group input since
last IETF. The attached draft (version 2) has some minor modifications
and corrections up to the last minute discussions.
Thanks,
-Samita
INTERNET-DRAFT Samita Chakrabarti
Expires: January, 2003 Erik Nordmark
Sun Microsystems, Inc.
July, 2003
Extension to Sockets API for Mobile IPv6
<draft-chakrabarti-mobileip-mipext-advapi-02.txt>
Status of this Memo
This document is an Internet-Draft and is subject to
all provisions of Section 10 of RFC2026.
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 Internet-
Drafts.
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."
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
http://www.ietf.org/shadow.html.
This Internet Draft expires January, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document describes data structures and API support for Mobile
IPv6 as an extension to Advanced Socket API support 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
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.
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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 also 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
................................ 14
3.1 Routing Header Access Functions ..................... 14
3.2 Home Address Destination Option Access Functions .... 14
4. Mobility Protocol Headers ............................... 15
4.1 Receiving and Sending Mobility Header Messages ..... 15
5. Protocols File ........................................... 17
6. IPv4-Mapped IPv6 Addresses ............................... 17
7. Security Considerations .................................. 17
8. References ............................................... 18
9. Acknowledgement .......................................... 18
10. Authors' Addresses ....................................... 18
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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.
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 API for
IPv6 sockets [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.
Datatypes 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_resvd; /* Reserved */
uint16_t ip6mh_cksum; /* Mobility Header Checksum */
/* Followed by type specific messages */
};
2.1.2 Binding Refresh Request Mobility Message
struct ip6mh_binding_request {
struct ip6_mh ip6mhbr_hdr;
uint16_t ip6mhbr_resvd;
/* Followed by optional Mobility Options */
};
2.1.3 Home Address Test Init (HoTI) Message
struct ip6mh_home_test_init {
struct ip6_mh ip6mhti_hdr;
uint16_t ip6mhti_resvd;
uint32_t ip6mhti_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 ip6mh_careof_test_init {
struct ip6_mh ip6mhcti_hdr;
uint16_t ip6mhcti_resvd;
uint32_t ip6mhcti_cookie[2]; /* 64 bit Cookie by MN */
/* Followed by optional Mobility Options */
};
2.1.5 Home Address Test (HOT) Message
struct ip6mh_home_test {
struct ip6_mh ip6mht_hdr;
uint16_t ip6mht_nonce_index;
uint32_t ip6mht_cookie[2]; /* Cookie from HOTI msg */
uint32_t ip6mht_keygen[2]; /* 64 Bit Key by CN */
/* Followed by optional Mobility Options */
};
2.1.6 Care Of Address Test (COT) Message
struct ip6mh_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 ip6mh_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 IP6MH_BU_ACK 0x8000 /* Request a binding ack */
#define IP6MH_BU_HOME 0x4000 /* Home Registration */
#define IP6MH_BU_LLOCAL 0x2000 /* Link-local compatibility */
#define IP6MH_BU_KEYM 0x1000 /* Key management mobility */
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2.1.8 Binding Acknowledgment Mobility Message
struct ip6mh_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 IP6MH_BA_KEYM 0x80 /* Key management mobility */
2.1.9 Binding Error Mobility Message
struct ip6mh_binding_error {
struct ip6_mh ip6mhbe_hdr;
uint8_t ip6mhbe_status; /* Error Status */
uint8_t ip6mhbe_resvd;
struct in6_addr ip6mhbe_homeaddr;
/* Followed by optional Mobility Options */
};
2.1.10 Mobility Option TLV data structure
struct ip6mh_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 ip6mh_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 ip6mh_opt_altcoa {
uint8_t ip6moa_type;
uint8_t ip6moa_len;
uint8_t ip6moa_addr[16]; /* Alternate Care-of Address */
};
2.1.11.3 Nonce Indices
struct ip6mh_opt_nonce_index {
uint8_t ip6moni_type;
uint8_t ip6moni_len;
uint16_t ip6moni_hm_nonce;
uint16_t ip6moni_coa_nonce;
};
2.1.11.4 Binding Authorization Data
struct ip6mh_opt_auth_data {
uint8_t ip6moad_type;
uint8_t ip6moad_len;
/* Followed by authentication data */
};
2.2 Mobility Header Constants
IPv6 Next Header Value for Mobility:
<netinet/in.h>
#define IPPROTO_MH 62 /* IPv6 Mobility Header: IANA-TBD */
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Mobility Header Message Types:
<netinet/ip6mh.h>
#define IP6MH_TYPE_BRR 0 /* Binding Refresh Request */
#define IP6MH_TYPE_HOTI 1 /* HOTI Message */
#define IP6MH_TYPE_COTI 2 /* COTI Message */
#define IP6MH_TYPE_HOT 3 /* HOT Message */
#define IP6MH_TYPE_COT 4 /* COT Message */
#define IP6MH_TYPE_BU 5 /* Binding Update */
#define IP6MH_TYPE_BACK 6 /* Binding ACK */
#define IP6MH_TYPE_BERROR 7 /* Binding Error */
Mobility Header Message Option Types:
<netinet/ip6mh.h>
#define IP6MHOPT_PAD1 0x00 /* PAD1 */
#define IP6MHOPT_PADN 0x01 /* PADN */
#define IP6MHOPT_BREFRESH 0x02 /* Binding Refresh */
#define IP6MHOPT_ALTCOA 0x03 /* Alternate COA */
#define IP6MHOPT_NONCEID 0x04 /* Nonce Index */
#define IP6MHOPT_BAUTH 0x05 /* Binding Auth Data */
Status values accompanied with Mobility Binding Acknowledgement:
<netinet/ip6mh.h>
#define IP6MH_BAS_ACCEPTED 0 /* BU accepted */
#define IP6MH_BAS_PRFX_DISCOV 1 /* Accepted, but prefix
discovery Required */
#define IP6MH_BAS_UNSPECIFIED 128 /* Reason unspecified */
#define IP6MH_BAS_PROHIBIT 129 /* Administratively
prohibited */
#define IP6MH_BAS_INSUFFICIENT 130 /* Insufficient
resources */
#define IP6MH_BAS_HA_NOT_SUPPORTED 131 /* HA registration not
supported */
#define IP6MH_BAS_NOT_HOME_SUBNET 132 /* Not Home subnet */
#define IP6MH_BAS_NOT_HA 133 /* Not HA for this
mobile node */
#define IP6MH_BAS_DAD_FAILED 134 /* DAD failed */
#define IP6MH_BAS_SEQNO_BAD 135 /* Sequence number out
of range */
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#define IP6MH_BAS_HOME_NI_EXPIRED 136 /* Expired Home nonce
index */
#define IP6MH_BAS_COA_NI_EXPIRED 137 /* Expired Care-of
nonce index */
#define IP6MH_BAS_NI_EXPIRED 138 /* Expired Nonce
Indices */
#define IP6MH_BAS_REG_NOT_ALLOWED 139 /* Registration type
change disallowed */
Status values for the Binding Error mobility messages:
<netinet/ip6mh.h>
#define IP6MH_BES_UNKNOWN_HAO 1 /* Unknown binding for HOA */
#define IP6MH_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 ip6hoa_type;
uint8_t ip6hoa_len;
uint8_t ip6hoa_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 MIP_HA_DISCOVERY_REQUEST 150
#define MIP_HA_DISCOVERY_REPLY 151
#define MIP_PREFIX_SOLICIT 152
#define MIP_PREFIX_ADVERT 153
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 mip_dhaad_req { /* Dynamic HA Address Discovery */
struct icmp6_hdr mip_dhreq_hdr;
};
#define mip_dhreq_type mip_dhreq_hdr.icmp6_type
#define mip_dhreq_code mip_dhreq_hdr.icmp6_code
#define mip_dhreq_cksum mip_dhreq_hdr.icmp6_cksum
#define mip_dhreq_id mip_dhreq_hdr.icmp6_data16[0]
#define mip_dhreq_reserved mip_dhreq_hdr.icmp6_data16[1]
struct mip_dhaad_rep { /* HA Address Discovery Reply */
struct icmp6_hdr mip_dhrep_hdr;
/* Followed by Home Agent IPv6 addresses */
};
#define mip_dhrep_type mip_dhrep_hdr.icmp6_type
#define mip_dhrep_code mip_dhrep_hdr.icmp6_code
#define mip_dhrep_cksum mip_dhrep_hdr.icmp6_cksum
#define mip_dhrep_id mip_dhrep_hdr.icmp6_data16[0]
#define mip_dhrep_reserved mip_dhrep_hdr.icmp6_data16[1]
struct mip_prefix_solicit { /* Mobile Prefix Solicitation */
struct icmp6_hdr mip_ps_hdr;
};
#define mip_ps_type mip_ps_hdr.icmp6_type
#define mip_ps_code mip_ps_hdr.icmp6_code
#define mip_ps_cksum mip_ps_hdr.icmp6_cksum
#define mip_ps_id mip_ps_hdr.icmp6_data16[0]
#define mip_ps_reserved mip_ps_hdr.icmp6_data16[1]
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struct mip_prefix_advert { /* Mobile Prefix Adverisements */
struct icmp6_hdr mip_pa_hdr;
/* Followed by one or more PI options */
};
#define mip_pa_type mip_pa_hdr.icmp6_type
#define mip_pa_code mip_pa_hdr.icmp6_code
#define mip_pa_cksum mip_pa_hdr.icmp6_cksum
#define mip_pa_id mip_pa_hdr.icmp6_data16[0]
#define mip_pa_flags_reserved mip_pa_hdr.icmp6_data16[1]
#define MIP_PA_FLAG_MANAGED 0x8000
#define MIP_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_adv_type;
uint8_t nd_opt_adv_len;
uint16_t nd_opt_adv_reserved;
uint32_t nd_opt_adv_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.
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 along with its data packets as Mobile IPv6
protocol takes care of it transparently at the protocol stack.
Similarly it is not clear that if an application would need to
set Router Header Type 2 extension to send data packets as it
is taken care by the Mobile IPv6 protocol depending on the
binding cache information. Thus this document does not specifically
discuss the sending of Route Header Type 2 extension header.
However, the following socket option parameters and cmsghdr fields
may be used for sending the Home Address destination options.
opt level/ optname/ optval/
cmsg_level cmsg_type cmsg_data[]
------------ ------------ ------------------------
IPPROTO_IPV6 IPV6_DSTOPTS ip6_dest structure
Some IPv6 implementations may support "sticky" options [1] for IPv6
destination option for datagram sockets.
3.1 Routing Header access functions
While accessing Routing header Type 2 extension header, one MUST
use type = 2 and segment = 1. The following functions are supported
for Mobile IPv6 applications for sending and receiving Routing
Header Type 2 headers:
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);
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.
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Detail description and examples of accessing a IPv6 Routing Header
are discussed in Advanced API for IPv6 Sockets [1].
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.
These options are then 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 Mobile IPv6 applications will not be
allowed to send Home Address Destination Option from the
application level, as Mobile IPv6 kernel takes care of sending
home-address option and routing header type 2. However, the order
of extension headers in conjunction with Home Address option sending
is specified in Mobility Support in IPv6 [2] in section 6.3.
The Destination options are normally constructed using the
inet6_opt_init(), inet6_opt_append(), inet6_opt_finish(), and
inet6_opt_set_val() functions, described in Section 10 of IPv6
Advanced API sockets [1].
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
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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.
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. If IPV6_CHECKSUM socket
option is set on the RAW socket, kernel will calculate the checksum
by default and place it on the mobility header before sending it out.
Similarly, if IPV6_CHECKSUM is set, the protocol stack will verify
the MH checksum on the inbound path and it will discard any MH
packet with invalid checksums. Mobility Header checksum procedure
is described in Mobile IPv6 Protocol [2] specification.
Thus when IPPROTO_MH is used as the protocol field in the RAW
socket() call and IPV6_CHECKSUM option is not set, the application
needs to fill the checksum field of the mobility header for outbound
data. Similarly the application needs to do checksum validity check
for the received packet. However, it is recommended that the
application set the IPV6_CHECKSUM socket option along with the RAW
sockets for IPPROTO_MH.
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 is pending IANA
(http://www.iana.orgassignments/protocol-numbers) assignment.
ipv6-mh 62 # Mobility Protocol Header
6. IPv4-Mapped IPv6 Addresses
The same rule applies as described in section 13 of IPv6 Advanced
API for Sockets [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 extension header.
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8. 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"
draft-ietf-mobileip-ipv6-22.txt, May, 2003.
[3] Deering, S., Hinden, R., "Internet Protocol, Version 6
(IPv6), Specification", RFC 2460, Dec. 1998.
9. Acknowledgement
Thanks to Brian Haley for the thorough review of this draft. Keiichi Shima,
Alexandru Petrescu, Ryuji Wakikawa, Vijay Devarapalli, Jim Bound, Suvidh
Mathur and other mobile-ip working group members provided valuable input
during the API design discussion.
10. Authors' Addresses
Samita Chakrabarti
Sun Microsystems, Inc.
4150 Network Circle
Santa Clara, CA 95054, USA
Email: [EMAIL PROTECTED]
Erik Nordmark
Sun Microsystems Laboratories
180, avenue de l'Europe
38334 SAINT ISMIER Cedex, France
Email: [EMAIL PROTECTED]
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