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udhcpc: ignore NAKs from "wrong" servers. Closes 4267

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function                                             old     new   delta
udhcpc_main                                         2716    2814     +98

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2014-02-27 18:15:50 +01:00
parent fca0ee5959
commit e2318bbad7
1 changed files with 24 additions and 1 deletions
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25
networking/udhcp/dhcpc.c
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@ -1232,7 +1232,7 @@ static void client_background(void)
int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int udhcpc_main(int argc UNUSED_PARAM, char **argv)
{
uint8_t *temp, *message;
uint8_t *message;
const char *str_V, *str_h, *str_F, *str_r;
IF_FEATURE_UDHCP_PORT(char *str_P;)
void *clientid_mac_ptr;
@ -1640,6 +1640,8 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
case INIT_SELECTING:
/* Must be a DHCPOFFER */
if (*message == DHCPOFFER) {
uint8_t *temp;
/* What exactly is server's IP? There are several values.
* Example DHCP offer captured with tchdump:
*
@ -1689,6 +1691,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
if (*message == DHCPACK) {
uint32_t lease_seconds;
struct in_addr temp_addr;
uint8_t *temp;
temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
if (!temp) {
@ -1766,6 +1769,26 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
continue; /* back to main loop */
}
if (*message == DHCPNAK) {
/* If network has more than one DHCP server,
* "wrong" server can reply first, with a NAK.
* Do not interpret it as a NAK from "our" server.
*/
if (server_addr != 0) {
uint32_t svid;
uint8_t *temp;
temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
if (!temp) {
non_matching_svid:
log1("%s with wrong server ID, ignoring packet",
"Received DHCP NAK"
);
continue;
}
move_from_unaligned32(svid, temp);
if (svid != server_addr)
goto non_matching_svid;
}
/* return to init state */
bb_info_msg("Received DHCP NAK");
udhcp_run_script(&packet, "nak");