e2318bbad
Denys Vlasenko
2014-02-27
Subject
udhcpc: ignore NAKs from "wrong" servers. Closes 4267
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Commit Diff GitHub →
networking/udhcp/dhcpc.c+24 -1
| @@ -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"); | |