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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2022 Felix Fietkau <nbd@nbd.name>
*/
#include "dhcpsnoop.h"
#include "msg.h"
const char *dhcpsnoop_parse_ipv4(const void *buf, size_t len, uint16_t port, uint32_t *expire)
{
const struct dhcpv4_message *msg = buf;
const uint8_t *pos, *end;
uint32_t leasetime = 0, rebind = 0, renew = 0;
char type = 0;
if (port != 67 && port != 68)
return NULL;
if (len < sizeof(*msg))
return NULL;
if (ntohl(msg->magic) != DHCPV4_MAGIC)
return NULL;
pos = msg->options;
end = buf + len;
while (pos < end) {
const uint8_t *opt = pos++;
if (*opt == DHCPV4_OPT_END)
break;
if (*opt == DHCPV4_OPT_PAD)
continue;
if (pos >= end || 1 + *pos > end - pos)
break;
pos += *pos + 1;
if (pos >= end)
break;
switch (*opt) {
case DHCPV4_OPT_MSG_TYPE:
if (!opt[1])
continue;
type = opt[2];
break;
case DHCPV4_OPT_LEASETIME:
if (opt[1] != 4)
continue;
leasetime = *((uint32_t *) &opt[2]);
break;
case DHCPV4_OPT_REBIND:
if (opt[1] != 4)
continue;
rebind = *((uint32_t *) &opt[2]);
break;
case DHCPV4_OPT_RENEW:
if (opt[1] != 4)
continue;
renew = *((uint32_t *) &opt[2]);
break;
}
}
if (renew)
*expire = renew;
else if (rebind)
*expire = rebind;
else if (leasetime)
*expire = leasetime;
else
*expire = 24 * 60 * 60;
*expire = ntohl(*expire);
switch(type) {
case DHCPV4_MSG_ACK:
return "ack";
case DHCPV4_MSG_DISCOVER:
return "discover";
case DHCPV4_MSG_OFFER:
return "offer";
case DHCPV4_MSG_REQUEST:
return "request";
}
return NULL;
}
const char *dhcpsnoop_parse_ipv6(const void *buf, size_t len, uint16_t port)
{
const struct dhcpv6_message *msg = buf;
if (port != 546 && port != 547)
return NULL;
switch(msg->msg_type) {
case DHCPV6_MSG_SOLICIT:
return "solicit";
case DHCPV6_MSG_REPLY:
return "reply";
case DHCPV6_MSG_RENEW:
return "renew";
default:
return NULL;
}
}
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