1 /***************************************************************************
2 * Copyright (c) 2024 Microsoft Corporation
3 *
4 * This program and the accompanying materials are made available under the
5 * terms of the MIT License which is available at
6 * https://opensource.org/licenses/MIT.
7 *
8 * SPDX-License-Identifier: MIT
9 **************************************************************************/
10
11
12 /**************************************************************************/
13 /**************************************************************************/
14 /** */
15 /** NetX Component */
16 /** */
17 /** Neighbor Discovery Cache */
18 /** */
19 /**************************************************************************/
20 /**************************************************************************/
21
22 #define NX_SOURCE_CODE
23
24
25 /* Include necessary system files. */
26
27 #include "nx_api.h"
28 #include "nx_ipv6.h"
29 #include "nx_nd_cache.h"
30 #include "nx_icmpv6.h"
31
32 #ifdef FEATURE_NX_IPV6
33
34
35 /**************************************************************************/
36 /* */
37 /* FUNCTION RELEASE */
38 /* */
39 /* _nx_nd_cache_fast_periodic_update PORTABLE C */
40 /* 6.1 */
41 /* AUTHOR */
42 /* */
43 /* Yuxin Zhou, Microsoft Corporation */
44 /* */
45 /* DESCRIPTION */
46 /* */
47 /* This function handles the ND entries in PROBE or INCOMPLETE state. */
48 /* It decrements the timer tick. If the ticker reaches zero */
49 /* a NS is sent. If MAX NS has been sent, this entry times out */
50 /* and is marked as INVALID. */
51 /* */
52 /* INPUT */
53 /* */
54 /* ip_ptr Pointer to the IP instance */
55 /* */
56 /* OUTPUT */
57 /* */
58 /* NONE */
59 /* */
60 /* CALLS */
61 /* */
62 /* tx_mutex_get Obtain protection mutex */
63 /* tx_mutex_put Release protection mutex */
64 /* _nx_icmpv6_send_ns Transmit a new NS message. */
65 /* */
66 /* CALLED BY */
67 /* */
68 /* _nx_nd_cache_delete_internal */
69 /* _nx_ip_thread_entry */
70 /* tx_mutex_get */
71 /* tx_mutex_put */
72 /* */
73 /* Note: */
74 /* */
75 /* This routine acquires the nx_nd_cache_protection mutex. */
76 /* Caller shall not hold this mutex before calling this function. */
77 /* */
78 /* */
79 /* RELEASE HISTORY */
80 /* */
81 /* DATE NAME DESCRIPTION */
82 /* */
83 /* 05-19-2020 Yuxin Zhou Initial Version 6.0 */
84 /* 09-30-2020 Yuxin Zhou Modified comment(s), */
85 /* resulting in version 6.1 */
86 /* */
87 /**************************************************************************/
_nx_nd_cache_fast_periodic_update(NX_IP * ip_ptr)88 VOID _nx_nd_cache_fast_periodic_update(NX_IP *ip_ptr)
89 {
90
91 INT i;
92
93 /* Loop through all entries, and invalidate the ones that are timed out. */
94 for (i = 0; i < NX_IPV6_NEIGHBOR_CACHE_SIZE; i++)
95 {
96
97 /* Check the entry is valid. */
98 if (ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_nd_status == ND_CACHE_STATE_INVALID)
99 {
100 continue;
101 }
102
103 /* Is this entry being checked for neighbor discovery? */
104 if ((ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_nd_status != ND_CACHE_STATE_PROBE) &&
105 (ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_nd_status != ND_CACHE_STATE_INCOMPLETE))
106 {
107
108 /* No, so skip over. */
109 continue;
110 }
111
112
113
114 /* Has this entry timed out? */
115 if (ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_timer_tick == 0)
116 {
117
118 /* Yes, is the max number of solicitations used up? */
119 if (ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_num_solicit == 0)
120 {
121
122 /* Yes; We already sent #num_solicit packets. So the destination
123 is unreachable. Clean up router, destination and cache table entries and crosslinks. */
124 _nx_nd_cache_delete_internal(ip_ptr, &ip_ptr -> nx_ipv6_nd_cache[i]);
125 }
126 else
127 {
128 /* Send another solicitation (NS) packet. */
129 INT uniCastNS;
130
131 uniCastNS = (ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_nd_status == ND_CACHE_STATE_PROBE);
132
133 /* Send out another mcast ns.*/
134 _nx_icmpv6_send_ns(ip_ptr, ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_dest_ip,
135 1, ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_outgoing_address, uniCastNS, &ip_ptr -> nx_ipv6_nd_cache[i]);
136
137 /* Keep track of how many we have sent. */
138 ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_num_solicit--;
139
140 /* Reset the expiration timer for sending the next NS. */
141 ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_timer_tick = ip_ptr -> nx_ipv6_retrans_timer_ticks;
142 }
143 }
144 else
145 {
146
147 /* Note that the only cache entries whose timer ticks are being decremented in this
148 function are states whose timer tick was set in actual timer ticks (as compared
149 with the slow periodic update where cache entry'timer ticks' are updated in
150 seconds. This is intentional and correct behavior. */
151 ip_ptr -> nx_ipv6_nd_cache[i].nx_nd_cache_timer_tick--;
152 }
153 }
154 }
155
156 #endif /* FEATURE_NX_IPV6 */
157
158
