mirror of
https://gitlab.isc.org/isc-projects/dhcp
synced 2025-08-31 14:25:41 +00:00
Full protocol
This commit is contained in:
Ted Lemon
438
server/dhcp.c
438
server/dhcp.c
@@ -49,8 +49,157 @@ static char copyright[] =
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void dhcp (packet)
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struct packet *packet;
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{
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struct lease *uid_lease, *ip_lease, *hw_lease, *lease;
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struct iaddr cip;
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dump_packet (packet);
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switch (packet -> packet_type) {
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case DHCPDISCOVER:
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dhcpdiscover (packet);
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break;
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case DHCPREQUEST:
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dhcprequest (packet);
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break;
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case DHCPDECLINE:
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case DHCPRELEASE:
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dhcprelease (packet);
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break;
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default:
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break;
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}
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}
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void dhcpdiscover (packet)
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struct packet *packet;
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{
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struct lease *lease = find_lease (packet);
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/* If we didn't find a lease, try to allocate one... */
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if (!lease) {
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lease = packet -> subnet -> last_lease;
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/* If there are no leases in that subnet that have
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expired, we have nothing to offer this client. */
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if (lease -> ends >= cur_time) {
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note ("no free leases on subnet %s",
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piaddr (packet -> subnet -> net));
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return;
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}
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lease -> host = (struct host_decl *)0;
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}
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ack_lease (packet, lease, DHCPOFFER, cur_time + 120);
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}
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void dhcprequest (packet)
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struct packet *packet;
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{
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struct lease *lease = find_lease (packet);
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/* Look for server identifier... */
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if (packet -> options [DHO_DHCP_SERVER_IDENTIFIER].len) {
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/* If there is one, and it isn't this server, and
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we have a lease for this client, let it go. */
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if (memcmp (packet ->
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options [DHO_DHCP_SERVER_IDENTIFIER].data,
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siaddr.iabuf, siaddr.len)) {
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if (lease)
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release_lease (lease);
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return;
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}
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} else {
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/* If no server identifier, drop it on the floor -
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it's a protocol violation. */
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return;
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}
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/* If we didn't find a lease, try to allocate one... */
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if (!lease) {
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nak_lease (packet);
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}
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ack_lease (packet, lease, DHCPOFFER, cur_time + 120);
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}
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void dhcprelease (packet)
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struct packet *packet;
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{
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struct lease *lease = find_lease (packet);
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/* If we didn't find a lease, try to allocate one... */
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if (lease) {
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release_lease (lease);
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}
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}
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void nak_lease (packet)
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struct packet *packet;
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{
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struct sockaddr_in to;
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int result;
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struct dhcp_packet raw;
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unsigned char nak = DHCPNAK;
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struct packet outgoing;
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struct tree_cache *options [256];
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struct tree_cache dhcpnak_tree;
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memset (options, 0, sizeof options);
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memset (&outgoing, 0, sizeof outgoing);
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memset (&raw, 0, sizeof raw);
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outgoing.raw = &raw;
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/* Set DHCP_MESSAGE_TYPE to DHCPNAK */
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options [DHO_DHCP_MESSAGE_TYPE] = &dhcpnak_tree;
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options [DHO_DHCP_MESSAGE_TYPE] -> value = &nak;
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options [DHO_DHCP_MESSAGE_TYPE] -> len = sizeof nak;
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options [DHO_DHCP_MESSAGE_TYPE] -> buf_size = sizeof nak;
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options [DHO_DHCP_MESSAGE_TYPE] -> timeout = 0xFFFFFFFF;
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options [DHO_DHCP_MESSAGE_TYPE] -> tree = (struct tree *)0;
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/* Set up the option buffer... */
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cons_options (packet, &outgoing, options, 0);
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raw.ciaddr = packet -> raw -> ciaddr;
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memcpy (&raw.siaddr, siaddr.iabuf, 4);
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raw.giaddr = packet -> raw -> giaddr;
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raw.xid = packet -> raw -> xid;
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raw.secs = packet -> raw -> secs;
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raw.flags = packet -> raw -> flags;
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raw.hops = packet -> raw -> hops;
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raw.op = BOOTREPLY;
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/* If this was gatewayed, send it back to the gateway... */
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if (raw.giaddr.s_addr)
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to.sin_addr = raw.giaddr;
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/* Otherwise, broadcast it on the local network. */
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else
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inet_aton ("204.254.239.255", &to.sin_addr); /* XXX bcst bug */
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/* to.sin_addr.s_addr = INADDR_BROADCAST; XXX */
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to.sin_port = htons (ntohs (server_port) + 1); /* XXX */
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to.sin_family = AF_INET;
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to.sin_len = sizeof to;
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memset (to.sin_zero, 0, sizeof to.sin_zero);
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note ("Sending dhcp NAK to %s, port %d",
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inet_ntoa (to.sin_addr), htons (to.sin_port));
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errno = 0;
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result = sendto (packet -> client_sock, &raw, outgoing.packet_length,
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0, (struct sockaddr *)&to, sizeof to);
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if (result < 0)
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warn ("sendto: %m");
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}
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void ack_lease (packet, lease, offer, when)
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struct packet *packet;
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struct lease *lease;
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unsigned char offer;
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TIME when;
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{
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struct lease lt;
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TIME lease_time;
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@@ -61,12 +210,160 @@ void dhcp (packet)
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struct sockaddr_in to;
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int result;
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unsigned char dhcpoffer = DHCPOFFER;
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struct tree_cache dhcpoffer_tree;
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unsigned char lease_time_buf [4];
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struct tree_cache lease_time_tree;
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struct tree_cache server_id_tree;
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dump_packet (packet);
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/* At this point, we have a lease that we can offer the client.
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Now we construct a lease structure that contains what we want,
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and call supersede_lease to do the right thing with it. */
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memset (<, 0, sizeof lt);
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/* Use the ip address of the lease that we finally found in
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the database. */
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lt.ip_addr = lease -> ip_addr;
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/* Start now. */
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lt.starts = cur_time;
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/* Figure out how long a lease to assign. */
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if (packet -> options [DHO_DHCP_LEASE_TIME].len == 4) {
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lease_time = getULong (packet ->
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options [DHO_DHCP_LEASE_TIME].data);
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/* Don't let the client ask for a longer lease than
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is supported for this subnet. */
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if (lease_time > packet -> subnet -> max_lease_time)
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lease_time = packet -> subnet -> max_lease_time;
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} else
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lease_time = packet -> subnet -> default_lease_time;
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lt.offered_expiry = cur_time + lease_time;
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if (when)
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lt.ends = when;
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lt.timestamp = cur_time;
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/* Record the uid, if given... */
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if (packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].len) {
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lt.uid_len =
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packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].len;
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lt.uid = packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].data;
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packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].data =
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(unsigned char *)0;
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packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].len = 0;
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}
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/* Record the hardware address, if given... */
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lt.hardware_addr.hlen = packet -> raw -> hlen;
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lt.hardware_addr.htype = packet -> raw -> htype;
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memcpy (lt.hardware_addr.haddr, packet -> raw -> chaddr,
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packet -> raw -> hlen);
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lt.host = lease -> host; /* XXX */
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lt.contain = lease -> contain;
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/* Record the transaction id... */
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lt.xid = packet -> raw -> xid;
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/* Install the new information about this lease in the database. */
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supersede_lease (lease, <);
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/* Send a response to the client... */
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memset (&outgoing, 0, sizeof outgoing);
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memset (&raw, 0, sizeof raw);
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outgoing.raw = &raw;
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/* Copy in the filename if given; otherwise, flag the filename
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buffer as available for options. */
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bufs |= 1; /* XXX */
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/* Copy in the server name if given; otherwise, flag the
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server_name buffer as available for options. */
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bufs |= 2; /* XXX */
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memcpy (raw.chaddr, packet -> raw -> chaddr, packet -> raw -> hlen);
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raw.hlen = packet -> raw -> hlen;
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raw.htype = packet -> raw -> htype;
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/* Start out with the subnet options... */
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memcpy (options, packet -> subnet -> options, sizeof options);
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/* Now put in options that override those. */
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options [DHO_DHCP_MESSAGE_TYPE] = &dhcpoffer_tree;
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options [DHO_DHCP_MESSAGE_TYPE] -> value = &offer;
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options [DHO_DHCP_MESSAGE_TYPE] -> len = sizeof offer;
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options [DHO_DHCP_MESSAGE_TYPE] -> buf_size = sizeof offer;
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options [DHO_DHCP_MESSAGE_TYPE] -> timeout = 0xFFFFFFFF;
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options [DHO_DHCP_MESSAGE_TYPE] -> tree = (struct tree *)0;
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options [DHO_DHCP_SERVER_IDENTIFIER] = &server_id_tree;
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options [DHO_DHCP_SERVER_IDENTIFIER] -> value = siaddr.iabuf;
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options [DHO_DHCP_SERVER_IDENTIFIER] -> len = siaddr.len;
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options [DHO_DHCP_SERVER_IDENTIFIER] -> buf_size = siaddr.len;
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options [DHO_DHCP_SERVER_IDENTIFIER] -> timeout = 0xFFFFFFFF;
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options [DHO_DHCP_SERVER_IDENTIFIER] -> tree = (struct tree *)0;
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putULong (lease_time_buf, lease -> offered_expiry - cur_time);
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options [DHO_DHCP_LEASE_TIME] = &lease_time_tree;
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options [DHO_DHCP_LEASE_TIME] -> value = lease_time_buf;
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options [DHO_DHCP_LEASE_TIME] -> len = sizeof lease_time_buf;
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options [DHO_DHCP_LEASE_TIME] -> buf_size = sizeof lease_time_buf;
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options [DHO_DHCP_LEASE_TIME] -> timeout = 0xFFFFFFFF;
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options [DHO_DHCP_LEASE_TIME] -> tree = (struct tree *)0;
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cons_options (packet, &outgoing, options, bufs);
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raw.ciaddr = packet -> raw -> ciaddr;
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memcpy (&raw.yiaddr, lease -> ip_addr.iabuf, 4);
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memcpy (&raw.siaddr, siaddr.iabuf, 4);
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raw.giaddr = packet -> raw -> giaddr;
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dump_packet (&outgoing);
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raw.xid = packet -> raw -> xid;
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raw.secs = packet -> raw -> secs;
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raw.flags = packet -> raw -> flags;
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raw.hops = packet -> raw -> hops;
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raw.op = BOOTREPLY;
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/* If this was gatewayed, send it back to the gateway... */
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if (raw.giaddr.s_addr)
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to.sin_addr = raw.giaddr;
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/* If it comes from a client who already knows its address,
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sent it directly to that client. */
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else if (raw.ciaddr.s_addr && offer == DHCPACK)
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to.sin_addr = packet -> raw -> ciaddr;
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/* Otherwise, if we can (we can't), unicast it to the client's
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hardware address */
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/* Otherwise, broadcast it on the local network. */
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else
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inet_aton ("204.254.239.255", &to.sin_addr); /* XXX bcst bug */
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/* to.sin_addr.s_addr = INADDR_BROADCAST; XXX */
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to.sin_port = htons (ntohs (server_port) + 1); /* XXX */
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to.sin_family = AF_INET;
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to.sin_len = sizeof to;
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memset (to.sin_zero, 0, sizeof to.sin_zero);
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note ("Sending dhcp reply to %s, port %d",
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inet_ntoa (to.sin_addr), htons (to.sin_port));
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errno = 0;
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result = sendto (packet -> client_sock, &raw, outgoing.packet_length,
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0, (struct sockaddr *)&to, sizeof to);
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if (result < 0)
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warn ("sendto: %m");
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}
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struct lease *find_lease (packet)
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struct packet *packet;
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{
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struct lease *uid_lease, *ip_lease, *hw_lease, *lease;
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struct iaddr cip;
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/* Try to find a lease that's been assigned to the specified
|
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unique client identifier. */
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@@ -151,136 +448,5 @@ void dhcp (packet)
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lease = hw_lease;
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}
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/* If we didn't find a lease, try to allocate one... */
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if (!lease) {
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lease = packet -> subnet -> last_lease;
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/* If there are no leases in that subnet that have
|
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expired, we have nothing to offer this client. */
|
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if (lease -> ends >= cur_time) {
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note ("no free leases on subnet %s",
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piaddr (packet -> subnet -> net));
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return;
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}
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lease -> host = (struct host_decl *)0;
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}
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/* At this point, we have a lease that we can offer the client.
|
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Now we construct a lease structure that contains what we want,
|
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and call supersede_lease to do the right thing with it. */
|
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|
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memset (<, 0, sizeof lt);
|
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|
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/* Use the ip address of the lease that we finally found in
|
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the database. */
|
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lt.ip_addr = lease -> ip_addr;
|
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|
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/* Start now. */
|
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lt.starts = cur_time;
|
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|
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/* Figure out how long a lease to assign. */
|
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if (packet -> options [DHO_DHCP_LEASE_TIME].len == 4) {
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lease_time = getULong (packet ->
|
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options [DHO_DHCP_LEASE_TIME].data);
|
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|
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/* Don't let the client ask for a longer lease than
|
||||
is supported for this subnet. */
|
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if (lease_time > packet -> subnet -> max_lease_time)
|
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lease_time = packet -> subnet -> max_lease_time;
|
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} else
|
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lease_time = packet -> subnet -> default_lease_time;
|
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lt.ends = cur_time + lease_time;
|
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|
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lt.timestamp = cur_time;
|
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|
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/* Record the uid, if given... */
|
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if (packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].len) {
|
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lt.uid_len =
|
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packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].len;
|
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lt.uid = packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].data;
|
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packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].data =
|
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(unsigned char *)0;
|
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packet -> options [DHO_DHCP_CLIENT_IDENTIFIER].len = 0;
|
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}
|
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|
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/* Record the hardware address, if given... */
|
||||
lt.hardware_addr.hlen = packet -> raw -> hlen;
|
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lt.hardware_addr.htype = packet -> raw -> htype;
|
||||
memcpy (lt.hardware_addr.haddr, packet -> raw -> chaddr,
|
||||
packet -> raw -> hlen);
|
||||
|
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lt.host = lease -> host; /* XXX */
|
||||
lt.contain = lease -> contain;
|
||||
|
||||
/* Record the transaction id... */
|
||||
lt.xid = packet -> raw -> xid;
|
||||
|
||||
/* Install the new information about this lease in the database. */
|
||||
supersede_lease (lease, <);
|
||||
|
||||
/* Send a response to the client... */
|
||||
|
||||
memset (&outgoing, 0, sizeof outgoing);
|
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memset (&raw, 0, sizeof raw);
|
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outgoing.raw = &raw;
|
||||
|
||||
/* Copy in the filename if given; otherwise, flag the filename
|
||||
buffer as available for options. */
|
||||
bufs |= 1; /* XXX */
|
||||
|
||||
/* Copy in the server name if given; otherwise, flag the
|
||||
server_name buffer as available for options. */
|
||||
bufs |= 2; /* XXX */
|
||||
|
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memcpy (raw.chaddr, packet -> raw -> chaddr, packet -> raw -> hlen);
|
||||
raw.hlen = packet -> raw -> hlen;
|
||||
raw.htype = packet -> raw -> htype;
|
||||
|
||||
/* Start out with the subnet options... */
|
||||
memcpy (options, packet -> subnet -> options, sizeof options);
|
||||
|
||||
/* Now put in options that override those. */
|
||||
options [DHO_DHCP_MESSAGE_TYPE] = &dhcpoffer_tree;
|
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options [DHO_DHCP_MESSAGE_TYPE] -> value = &dhcpoffer;
|
||||
options [DHO_DHCP_MESSAGE_TYPE] -> len = sizeof dhcpoffer;
|
||||
options [DHO_DHCP_MESSAGE_TYPE] -> buf_size = sizeof dhcpoffer;
|
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options [DHO_DHCP_MESSAGE_TYPE] -> timeout = 0xFFFFFFFF;
|
||||
options [DHO_DHCP_MESSAGE_TYPE] -> tree = (struct tree *)0;
|
||||
|
||||
|
||||
putULong (lease_time_buf, lease -> ends - cur_time);
|
||||
options [DHO_DHCP_LEASE_TIME] = &lease_time_tree;
|
||||
options [DHO_DHCP_LEASE_TIME] -> value = lease_time_buf;
|
||||
options [DHO_DHCP_LEASE_TIME] -> len = sizeof lease_time_buf;
|
||||
options [DHO_DHCP_LEASE_TIME] -> buf_size = sizeof lease_time_buf;
|
||||
options [DHO_DHCP_LEASE_TIME] -> timeout = 0xFFFFFFFF;
|
||||
options [DHO_DHCP_LEASE_TIME] -> tree = (struct tree *)0;
|
||||
|
||||
cons_options (packet, &outgoing, options, bufs);
|
||||
|
||||
raw.ciaddr = packet -> raw -> ciaddr;
|
||||
memcpy (&raw.yiaddr, lease -> ip_addr.iabuf, 4);
|
||||
memcpy (&raw.siaddr, siaddr.iabuf, 4);
|
||||
raw.giaddr = packet -> raw -> giaddr;
|
||||
|
||||
raw.xid = packet -> raw -> xid;
|
||||
raw.secs = packet -> raw -> secs;
|
||||
raw.flags = packet -> raw -> flags;
|
||||
raw.hops = packet -> raw -> hops;
|
||||
raw.op = BOOTREPLY;
|
||||
|
||||
to.sin_port = htons (2000);
|
||||
to.sin_addr.s_addr = INADDR_BROADCAST;
|
||||
to.sin_family = AF_INET;
|
||||
to.sin_len = sizeof to;
|
||||
memset (to.sin_zero, 0, sizeof to.sin_zero);
|
||||
|
||||
note ("Sending dhcp reply to %s, port %d",
|
||||
inet_ntoa (to.sin_addr), htons (to.sin_port));
|
||||
|
||||
errno = 0;
|
||||
result = sendto (packet -> client_sock, &raw, outgoing.packet_length,
|
||||
0, (struct sockaddr *)&to, sizeof to);
|
||||
if (result < 0)
|
||||
warn ("sendto: %m");
|
||||
return lease;
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user