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udhcpc: allow zero server-id. Closes 6614.

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function                                             old     new   delta
bcast_or_ucast                                         -      47     +47
udhcp_send_kernel_packet                             271     295     +24
udhcpc_main                                         2696    2705      +9
udhcp_send_raw_packet                                456     459      +3
send_release                                          90      76     -14
send_renew                                           105      77     -28
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 3/2 up/down: 83/-42)             Total: 41 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2013-11-03 19:20:54 +01:00
parent b21bc80c76
commit 8d3efaf35e
1 changed files with 25 additions and 11 deletions
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34
networking/udhcp/dhcpc.c
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@ -667,6 +667,15 @@ static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
client_config.ifindex);
}
static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
{
if (server)
return udhcp_send_kernel_packet(packet,
ciaddr, CLIENT_PORT,
server, SERVER_PORT);
return raw_bcast_from_client_config_ifindex(packet);
}
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
/* NOINLINE: limit stack usage in caller */
static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
@ -773,11 +782,7 @@ static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
add_client_options(&packet);
bb_info_msg("Sending renew...");
if (server)
return udhcp_send_kernel_packet(&packet,
ciaddr, CLIENT_PORT,
server, SERVER_PORT);
return raw_bcast_from_client_config_ifindex(&packet);
return bcast_or_ucast(&packet, ciaddr, server);
}
#if ENABLE_FEATURE_UDHCPC_ARPING
@ -826,7 +831,11 @@ static int send_release(uint32_t server, uint32_t ciaddr)
udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
bb_info_msg("Sending release...");
return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
/* Note: normally we unicast here since "server" is not zero.
* However, there _are_ people who run "address-less" DHCP servers,
* and reportedly ISC dhcp client and Windows allow that.
*/
return bcast_or_ucast(&packet, ciaddr, server);
}
/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
@ -1648,14 +1657,19 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
* might work too.
* "Next server" and router are definitely wrong ones to use, though...
*/
/* We used to ignore pcakets without DHCP_SERVER_ID.
* I've got user reports from people who run "address-less" servers.
* They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
* They say ISC DHCP client supports this case.
*/
server_addr = 0;
temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
if (!temp) {
bb_error_msg("no server ID, ignoring packet");
continue;
/* still selecting - this server looks bad */
}
bb_error_msg("no server ID, using 0.0.0.0");
} else {
/* it IS unaligned sometimes, don't "optimize" */
move_from_unaligned32(server_addr, temp);
}
/*xid = packet.xid; - already is */
requested_ip = packet.yiaddr;