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1 office 1 /**
2 * @file net_ipv4_arp_probe.c
3 * @author Ambroz Bizjak <ambrop7@gmail.com>
4 *
5 * @section LICENSE
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the
15 * names of its contributors may be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * @section DESCRIPTION
30 *
31 * ARP probing module.
32 *
33 * Synopsis:
34 * net.ipv4.arp_probe(string ifname, string addr)
35 *
36 * Description:
37 * Monitors local presence of an IPv4 host on a network interface.
38 * On initialization, may take some time to determine whether
39 * the host is present or not, then goes to UP state. When it
40 * determines that presence has changed, toggles itself DOWN then
41 * UP to expose the new determination.
42 *
43 * Variables:
44 * exists - "true" if the host exists, "false" if not
45 */
46  
47 #include <stdlib.h>
48  
49 #include <misc/ipaddr.h>
50 #include <arpprobe/BArpProbe.h>
51  
52 #include <ncd/module_common.h>
53  
54 #include <generated/blog_channel_ncd_net_ipv4_arp_probe.h>
55  
56 #define STATE_UNKNOWN 1
57 #define STATE_EXIST 2
58 #define STATE_NOEXIST 3
59  
60 struct instance {
61 NCDModuleInst *i;
62 BArpProbe arpprobe;
63 int state;
64 };
65  
66 static void instance_free (struct instance *o, int is_error);
67  
68 static void arpprobe_handler (struct instance *o, int event)
69 {
70 switch (event) {
71 case BARPPROBE_EVENT_EXIST: {
72 ASSERT(o->state == STATE_UNKNOWN || o->state == STATE_NOEXIST)
73  
74 ModuleLog(o->i, BLOG_INFO, "exist");
75  
76 if (o->state == STATE_NOEXIST) {
77 // signal down
78 NCDModuleInst_Backend_Down(o->i);
79 }
80  
81 // signal up
82 NCDModuleInst_Backend_Up(o->i);
83  
84 // set state exist
85 o->state = STATE_EXIST;
86 } break;
87  
88 case BARPPROBE_EVENT_NOEXIST: {
89 ASSERT(o->state == STATE_UNKNOWN || o->state == STATE_EXIST)
90  
91 ModuleLog(o->i, BLOG_INFO, "noexist");
92  
93 if (o->state == STATE_EXIST) {
94 // signal down
95 NCDModuleInst_Backend_Down(o->i);
96 }
97  
98 // signal up
99 NCDModuleInst_Backend_Up(o->i);
100  
101 // set state noexist
102 o->state = STATE_NOEXIST;
103 } break;
104  
105 case BARPPROBE_EVENT_ERROR: {
106 ModuleLog(o->i, BLOG_ERROR, "error");
107  
108 // die
109 instance_free(o, 1);
110 return;
111 } break;
112  
113 default: ASSERT(0);
114 }
115 }
116  
117 static void func_new (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
118 {
119 struct instance *o = vo;
120 o->i = i;
121  
122 // read arguments
123 NCDValRef arg_ifname;
124 NCDValRef arg_addr;
125 if (!NCDVal_ListRead(params->args, 2, &arg_ifname, &arg_addr)) {
126 ModuleLog(o->i, BLOG_ERROR, "wrong arity");
127 goto fail0;
128 }
129 if (!NCDVal_IsStringNoNulls(arg_ifname) || !NCDVal_IsString(arg_addr)) {
130 ModuleLog(o->i, BLOG_ERROR, "wrong type");
131 goto fail0;
132 }
133  
134 // parse address
135 uint32_t addr;
136 if (!ipaddr_parse_ipv4_addr(NCDVal_StringMemRef(arg_addr), &addr)) {
137 ModuleLog(o->i, BLOG_ERROR, "wrong address");
138 goto fail0;
139 }
140  
141 // null terminate ifname
142 NCDValNullTermString ifname_nts;
143 if (!NCDVal_StringNullTerminate(arg_ifname, &ifname_nts)) {
144 ModuleLog(i, BLOG_ERROR, "NCDVal_StringNullTerminate failed");
145 goto fail0;
146 }
147  
148 // init arpprobe
149 int res = BArpProbe_Init(&o->arpprobe, ifname_nts.data, addr, i->params->iparams->reactor, o, (BArpProbe_handler)arpprobe_handler);
150 NCDValNullTermString_Free(&ifname_nts);
151 if (!res) {
152 ModuleLog(o->i, BLOG_ERROR, "BArpProbe_Init failed");
153 goto fail0;
154 }
155  
156 // set state unknown
157 o->state = STATE_UNKNOWN;
158 return;
159  
160 fail0:
161 NCDModuleInst_Backend_DeadError(i);
162 }
163  
164 static void instance_free (struct instance *o, int is_error)
165 {
166 // free arpprobe
167 BArpProbe_Free(&o->arpprobe);
168  
169 if (is_error) {
170 NCDModuleInst_Backend_DeadError(o->i);
171 } else {
172 NCDModuleInst_Backend_Dead(o->i);
173 }
174 }
175  
176 static void func_die (void *vo)
177 {
178 struct instance *o = vo;
179  
180 instance_free(o, 0);
181 }
182  
183 static int func_getvar (void *vo, const char *name, NCDValMem *mem, NCDValRef *out)
184 {
185 struct instance *o = vo;
186 ASSERT(o->state == STATE_EXIST || o->state == STATE_NOEXIST)
187  
188 if (!strcmp(name, "exists")) {
189 *out = ncd_make_boolean(mem, o->state == STATE_EXIST);
190 return 1;
191 }
192  
193 return 0;
194 }
195  
196 static struct NCDModule modules[] = {
197 {
198 .type = "net.ipv4.arp_probe",
199 .func_new2 = func_new,
200 .func_die = func_die,
201 .func_getvar = func_getvar,
202 .alloc_size = sizeof(struct instance)
203 }, {
204 .type = NULL
205 }
206 };
207  
208 const struct NCDModuleGroup ncdmodule_net_ipv4_arp_probe = {
209 .modules = modules
210 };