53f72bb3f
Denys Vlasenko
2010-03-21
Subject
dhcpd: apparently, sometimes IP is in ciaddr, not requested_ip...
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networking/udhcp/clientpacket.c+0 -13
| @@ -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..."); | |
networking/udhcp/dhcpd.c+93 -8
| @@ -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; | |