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dhcp4: filter bogus DNS/NTP server addresses silently

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if we receive a bogus lease with a DNS/NTP server within local scope let's
politely ignore.

Fixes: #4524
This commit is contained in:
Lennart Poettering 2016-11-18 17:19:44 +01:00
parent 49ad68298a
commit d9ec2e632d
1 changed files with 19 additions and 0 deletions
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19
src/libsystemd-network/sd-dhcp-lease.c
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@ -383,6 +383,23 @@ static int lease_parse_domain(const uint8_t *option, size_t len, char **ret) {
return 0;
}
static void filter_bogus_addresses(struct in_addr *addresses, size_t *n) {
size_t i, j;
/* Silently filter DNS/NTP servers supplied to us that do not make outside of the local scope. */
for (i = 0, j = 0; i < *n; i ++) {
if (in4_addr_is_null(addresses+i) ||
in4_addr_is_localhost(addresses+i))
continue;
addresses[j++] = addresses[i];
}
*n = j;
}
static int lease_parse_in_addrs(const uint8_t *option, size_t len, struct in_addr **ret, size_t *n_ret) {
assert(option);
assert(ret);
@ -404,6 +421,8 @@ static int lease_parse_in_addrs(const uint8_t *option, size_t len, struct in_add
if (!addresses)
return -ENOMEM;
filter_bogus_addresses(addresses, &n_addresses);
free(*ret);
*ret = addresses;
*n_ret = n_addresses;