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/**
* @file net_ipv4_arp_probe.c
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @section DESCRIPTION
*
* ARP probing module.
*
* Synopsis:
* net.ipv4.arp_probe(string ifname, string addr)
*
* Description:
* Monitors local presence of an IPv4 host on a network interface.
* On initialization, may take some time to determine whether
* the host is present or not, then goes to UP state. When it
* determines that presence has changed, toggles itself DOWN then
* UP to expose the new determination.
*
* Variables:
* exists - "true" if the host exists, "false" if not
*/
#include <stdlib.h>
#include <misc/ipaddr.h>
#include <arpprobe/BArpProbe.h>
#include <ncd/module_common.h>
#include <generated/blog_channel_ncd_net_ipv4_arp_probe.h>
#define STATE_UNKNOWN 1
#define STATE_EXIST 2
#define STATE_NOEXIST 3
struct instance {
NCDModuleInst *i;
BArpProbe arpprobe;
int state;
};
static void instance_free (struct instance *o, int is_error);
static void arpprobe_handler (struct instance *o, int event)
{
switch (event) {
case BARPPROBE_EVENT_EXIST: {
ASSERT(o->state == STATE_UNKNOWN || o->state == STATE_NOEXIST)
ModuleLog(o->i, BLOG_INFO, "exist");
if (o->state == STATE_NOEXIST) {
// signal down
NCDModuleInst_Backend_Down(o->i);
}
// signal up
NCDModuleInst_Backend_Up(o->i);
// set state exist
o->state = STATE_EXIST;
} break;
case BARPPROBE_EVENT_NOEXIST: {
ASSERT(o->state == STATE_UNKNOWN || o->state == STATE_EXIST)
ModuleLog(o->i, BLOG_INFO, "noexist");
if (o->state == STATE_EXIST) {
// signal down
NCDModuleInst_Backend_Down(o->i);
}
// signal up
NCDModuleInst_Backend_Up(o->i);
// set state noexist
o->state = STATE_NOEXIST;
} break;
case BARPPROBE_EVENT_ERROR: {
ModuleLog(o->i, BLOG_ERROR, "error");
// die
instance_free(o, 1);
return;
} break;
default: ASSERT(0);
}
}
static void func_new (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
{
struct instance *o = vo;
o->i = i;
// read arguments
NCDValRef arg_ifname;
NCDValRef arg_addr;
if (!NCDVal_ListRead(params->args, 2, &arg_ifname, &arg_addr)) {
ModuleLog(o->i, BLOG_ERROR, "wrong arity");
goto fail0;
}
if (!NCDVal_IsStringNoNulls(arg_ifname) || !NCDVal_IsString(arg_addr)) {
ModuleLog(o->i, BLOG_ERROR, "wrong type");
goto fail0;
}
// parse address
uint32_t addr;
if (!ipaddr_parse_ipv4_addr(NCDVal_StringMemRef(arg_addr), &addr)) {
ModuleLog(o->i, BLOG_ERROR, "wrong address");
goto fail0;
}
// null terminate ifname
NCDValNullTermString ifname_nts;
if (!NCDVal_StringNullTerminate(arg_ifname, &ifname_nts)) {
ModuleLog(i, BLOG_ERROR, "NCDVal_StringNullTerminate failed");
goto fail0;
}
// init arpprobe
int res = BArpProbe_Init(&o->arpprobe, ifname_nts.data, addr, i->params->iparams->reactor, o, (BArpProbe_handler)arpprobe_handler);
NCDValNullTermString_Free(&ifname_nts);
if (!res) {
ModuleLog(o->i, BLOG_ERROR, "BArpProbe_Init failed");
goto fail0;
}
// set state unknown
o->state = STATE_UNKNOWN;
return;
fail0:
NCDModuleInst_Backend_DeadError(i);
}
static void instance_free (struct instance *o, int is_error)
{
// free arpprobe
BArpProbe_Free(&o->arpprobe);
if (is_error) {
NCDModuleInst_Backend_DeadError(o->i);
} else {
NCDModuleInst_Backend_Dead(o->i);
}
}
static void func_die (void *vo)
{
struct instance *o = vo;
instance_free(o, 0);
}
static int func_getvar (void *vo, const char *name, NCDValMem *mem, NCDValRef *out)
{
struct instance *o = vo;
ASSERT(o->state == STATE_EXIST || o->state == STATE_NOEXIST)
if (!strcmp(name, "exists")) {
*out = ncd_make_boolean(mem, o->state == STATE_EXIST);
return 1;
}
return 0;
}
static struct NCDModule modules[] = {
{
.type = "net.ipv4.arp_probe",
.func_new2 = func_new,
.func_die = func_die,
.func_getvar = func_getvar,
.alloc_size = sizeof(struct instance)
}, {
.type = NULL
}
};
const struct NCDModuleGroup ncdmodule_net_ipv4_arp_probe = {
.modules = modules
};