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udhcpc6: generate a consistent IAID

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Currently, udhcpc6 does not meet the requirements for
Identity Association in RFC 3315.
This is a specific explanation in RFC 3315 protocol:
https://datatracker.ietf.org/doc/html/rfc3315#section-10
"The IAID uniquely identifies the IA and must be chosen to be unique
   among the IAIDs on the client.  The IAID is chosen by the client.
   For any given use of an IA by the client, the IAID for that IA MUST
   be consistent across restarts of the DHCP client."
This patch makes the client generate a consistent IAID based on the MAC address.

function                                             old     new   delta
send_d6_discover                                     285     270     -15

Signed-off-by: Zhou Siqi <zhousiqi5@huawei.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Zhou Siqi 2025-02-09 13:50:18 +01:00 • committed by Denys Vlasenko
parent 779cca899f
commit 4115439496
1 changed files with 27 additions and 2 deletions
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29
networking/udhcp/d6_dhcpc.c
View file

@ -622,6 +622,31 @@ static NOINLINE int send_d6_info_request(void)
return d6_mcast_from_client_data_ifindex(&packet, opt_ptr);
}
/*
* RFC 3315 10. Identity Association
*
* An "identity-association" (IA) is a construct through which a server
* and a client can identify, group, and manage a set of related IPv6
* addresses. Each IA consists of an IAID and associated configuration
* information.
*
* A client must associate at least one distinct IA with each of its
* network interfaces for which it is to request the assignment of IPv6
* addresses from a DHCP server. The client uses the IAs assigned to an
* interface to obtain configuration information from a server for that
* interface. Each IA must be associated with exactly one interface.
*
* The IAID uniquely identifies the IA and must be chosen to be unique
* among the IAIDs on the client. The IAID is chosen by the client.
* For any given use of an IA by the client, the IAID for that IA MUST
* be consistent across restarts of the DHCP client...
*/
/* Generate IAID. We base it on our MAC address' last 4 bytes */
static void generate_iaid(uint8_t *iaid)
{
memcpy(iaid, &client_data.client_mac[2], 4);
}
/* Multicast a DHCPv6 Solicit packet to the network, with an optionally requested IP.
*
* RFC 3315 17.1.1. Creation of Solicit Messages
@ -721,7 +746,7 @@ static NOINLINE int send_d6_discover(struct in6_addr *requested_ipv6)
client6_data.ia_na = xzalloc(len);
client6_data.ia_na->code = D6_OPT_IA_NA;
client6_data.ia_na->len = len - 4;
*(bb__aliased_uint32_t*)client6_data.ia_na->data = rand(); /* IAID */
generate_iaid(client6_data.ia_na->data); /* IAID */
if (requested_ipv6) {
struct d6_option *iaaddr = (void*)(client6_data.ia_na->data + 4+4+4);
iaaddr->code = D6_OPT_IAADDR;
@ -739,7 +764,7 @@ static NOINLINE int send_d6_discover(struct in6_addr *requested_ipv6)
client6_data.ia_pd = xzalloc(len);
client6_data.ia_pd->code = D6_OPT_IA_PD;
client6_data.ia_pd->len = len - 4;
*(bb__aliased_uint32_t*)client6_data.ia_pd->data = rand(); /* IAID */
generate_iaid(client6_data.ia_na->data); /* IAID */
opt_ptr = mempcpy(opt_ptr, client6_data.ia_pd, len);
}