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List:       busybox
Subject:    [Patch] udhcpc6: support generate a consistent iaid
From:       "zhousiqi (A)" <zhousiqi5 () huawei ! com>
Date:       2024-04-12 7:09:19
Message-ID: df3b8c27585b4251bc8f09b0eef2189c () huawei ! com
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Currently, udhcpc6 does not meet the requirements for Identity Association in RFC \
3315. This is a specific explanation of 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 allows the client to generate a consistent IAID based on the MAC address.

Signed-off-by: Zhou Siqi <zhousiqi5@huawei.com>
---
 networking/udhcp/d6_dhcpc.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index a35488d..99a53c8 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -741,6 +741,32 @@ static NOINLINE int send_d6_info_request(void)
       |     OPTION_RECONF_ACCEPT      |               0               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  */
+
+/*obtain a consistent IAID based on the MAC address*/
+static int d6_create_iaid()
+{
+       int data = 0;
+       int start_idx = 0, copy_len = 0;
+       int mac_len = 0;
+
+       mac_len = sizeof(client_data.client_mac);
+
+       /*
+        * A simple IAID is the last 4 bytes
+        * of the hardware address.
+        */
+       if (mac_len > 4) {
+               start_idx = mac_len - 4;
+               copy_len = 4;
+       } else {
+               copy_len = mac_len;
+       }
+
+       memcpy(&data, &client_data.client_mac[start_idx], copy_len);
+
+       return data;
+}
+
 /* NOINLINE: limit stack usage in caller */
 static NOINLINE int send_d6_discover(struct in6_addr *requested_ipv6)
 {
@@ -759,7 +785,7 @@ 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 */
+               *(bb__aliased_uint32_t*)client6_data.ia_na->data = d6_create_iaid(); \
/* IAID */  if (requested_ipv6) {
                         struct d6_option *iaaddr = (void*)(client6_data.ia_na->data \
+ 4+4+4);  iaaddr->code = D6_OPT_IAADDR;
@@ -777,7 +803,7 @@ 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 */
+               *(bb__aliased_uint32_t*)client6_data.ia_pd->data = d6_create_iaid(); \
/* IAID */  opt_ptr = mempcpy(opt_ptr, client6_data.ia_pd, len);
         }
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