[git commit master] dhcpd: apparently, sometimes IP is in ciaddr, not requested_ip...
Denys Vlasenko
vda.linux at googlemail.com
Sun Mar 21 05:46:09 UTC 2010
commit: http://git.busybox.net/busybox/commit/?id=53f72bb3f0bd81b1d3af8939a16ec730c7e750c3
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
also revert the part which appempted to "fix" that in client
function old new delta
udhcpd_main 1949 1964 +15
send_renew 142 105 -37
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 15/-37) Total: -22 bytes
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/udhcp/clientpacket.c | 13 -----
networking/udhcp/dhcpd.c | 101 +++++++++++++++++++++++++++++++++++---
2 files changed, 93 insertions(+), 21 deletions(-)
diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c
index a0be428..b4a75be 100644
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -156,20 +156,7 @@ int FAST_FUNC send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
- /* RFC 2131:
- * "3.2 Client-server interaction - reusing a previously
- * allocated network address"...
- * The client broadcasts a DHCPREQUEST message on its local subnet.
- * The message includes the client's network address in the
- * REQUESTED_IP option. As the client has not received its
- * network address, it MUST NOT fill in the 'ciaddr' field."
- *
- * FIXME: we seem to not follow this, we do set ciaddr.
- */
packet.ciaddr = ciaddr;
- add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr);
- if (server)
- add_simple_option(packet.options, DHCP_SERVER_ID, server);
add_param_req_option(&packet);
bb_info_msg("Sending renew...");
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index a529e1b..d6e90cd 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -48,7 +48,7 @@ static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadc
if (force_broadcast
|| (dhcp_pkt->flags & htons(BROADCAST_FLAG))
- || !dhcp_pkt->ciaddr
+ || dhcp_pkt->ciaddr == 0
) {
log1("Broadcasting packet to client");
ciaddr = INADDR_BROADCAST;
@@ -466,16 +466,101 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
case DHCPREQUEST:
log1("Received REQUEST");
-
- /* RFC 2131: "The REQUESTED_IP option MUST be set
- * to the value of 'yiaddr' in the DHCPOFFER message
- * from the server." */
+/* RFC 2131:
+
+o DHCPREQUEST generated during SELECTING state:
+
+ Client inserts the address of the selected server in 'server
+ identifier', 'ciaddr' MUST be zero, 'requested IP address' MUST be
+ filled in with the yiaddr value from the chosen DHCPOFFER.
+
+ Note that the client may choose to collect several DHCPOFFER
+ messages and select the "best" offer. The client indicates its
+ selection by identifying the offering server in the DHCPREQUEST
+ message. If the client receives no acceptable offers, the client
+ may choose to try another DHCPDISCOVER message. Therefore, the
+ servers may not receive a specific DHCPREQUEST from which they can
+ decide whether or not the client has accepted the offer.
+
+o DHCPREQUEST generated during INIT-REBOOT state:
+
+ 'server identifier' MUST NOT be filled in, 'requested IP address'
+ option MUST be filled in with client's notion of its previously
+ assigned address. 'ciaddr' MUST be zero. The client is seeking to
+ verify a previously allocated, cached configuration. Server SHOULD
+ send a DHCPNAK message to the client if the 'requested IP address'
+ is incorrect, or is on the wrong network.
+
+ Determining whether a client in the INIT-REBOOT state is on the
+ correct network is done by examining the contents of 'giaddr', the
+ 'requested IP address' option, and a database lookup. If the DHCP
+ server detects that the client is on the wrong net (i.e., the
+ result of applying the local subnet mask or remote subnet mask (if
+ 'giaddr' is not zero) to 'requested IP address' option value
+ doesn't match reality), then the server SHOULD send a DHCPNAK
+ message to the client.
+
+ If the network is correct, then the DHCP server should check if
+ the client's notion of its IP address is correct. If not, then the
+ server SHOULD send a DHCPNAK message to the client. If the DHCP
+ server has no record of this client, then it MUST remain silent,
+ and MAY output a warning to the network administrator. This
+ behavior is necessary for peaceful coexistence of non-
+ communicating DHCP servers on the same wire.
+
+ If 'giaddr' is 0x0 in the DHCPREQUEST message, the client is on
+ the same subnet as the server. The server MUST broadcast the
+ DHCPNAK message to the 0xffffffff broadcast address because the
+ client may not have a correct network address or subnet mask, and
+ the client may not be answering ARP requests.
+
+ If 'giaddr' is set in the DHCPREQUEST message, the client is on a
+ different subnet. The server MUST set the broadcast bit in the
+ DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the
+ client, because the client may not have a correct network address
+ or subnet mask, and the client may not be answering ARP requests.
+
+o DHCPREQUEST generated during RENEWING state:
+
+ 'server identifier' MUST NOT be filled in, 'requested IP address'
+ option MUST NOT be filled in, 'ciaddr' MUST be filled in with
+ client's IP address. In this situation, the client is completely
+ configured, and is trying to extend its lease. This message will
+ be unicast, so no relay agents will be involved in its
+ transmission. Because 'giaddr' is therefore not filled in, the
+ DHCP server will trust the value in 'ciaddr', and use it when
+ replying to the client.
+
+ A client MAY choose to renew or extend its lease prior to T1. The
+ server may choose not to extend the lease (as a policy decision by
+ the network administrator), but should return a DHCPACK message
+ regardless.
+
+o DHCPREQUEST generated during REBINDING state:
+
+ 'server identifier' MUST NOT be filled in, 'requested IP address'
+ option MUST NOT be filled in, 'ciaddr' MUST be filled in with
+ client's IP address. In this situation, the client is completely
+ configured, and is trying to extend its lease. This message MUST
+ be broadcast to the 0xffffffff IP broadcast address. The DHCP
+ server SHOULD check 'ciaddr' for correctness before replying to
+ the DHCPREQUEST.
+
+ The DHCPREQUEST from a REBINDING client is intended to accommodate
+ sites that have multiple DHCP servers and a mechanism for
+ maintaining consistency among leases managed by multiple servers.
+ A DHCP server MAY extend a client's lease only if it has local
+ administrative authority to do so.
+*/
if (!requested_opt) {
- log1("no requested IP, ignoring");
- break;
+ requested_nip = packet.ciaddr;
+ if (requested_nip == 0) {
+ log1("no requested IP and no ciaddr, ignoring");
+ break;
+ }
}
if (lease && requested_nip == lease->lease_nip) {
- /* client requests IP which matches the lease.
+ /* client requested or configured IP matches the lease.
* ACK it, and bump lease expiration time. */
send_ACK(&packet, lease->lease_nip);
break;
--
1.6.3.3
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