1 files changed, 266 insertions, 0 deletions
diff --git a/networking/udhcp/serverpacket.c b/networking/udhcp/serverpacket.c
new file mode 100644
index 0000000..dcc234c
--- /dev/null
+++ b/networking/udhcp/serverpacket.c
@@ -0,0 +1,266 @@
+/* vi: set sw=4 ts=4: */
+/* serverpacket.c
+ *
+ * Construct and send DHCP server packets
+ *
+ * Russ Dill <Russ.Dill@asu.edu> July 2001
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "common.h"
+#include "dhcpc.h"
+#include "dhcpd.h"
+#include "options.h"
+
+
+/* send a packet to giaddr using the kernel ip stack */
+static int send_packet_to_relay(struct dhcpMessage *payload)
+{
+	DEBUG("Forwarding packet to relay");
+
+	return udhcp_send_kernel_packet(payload, server_config.server, SERVER_PORT,
+			payload->giaddr, SERVER_PORT);
+}
+
+
+/* send a packet to a specific arp address and ip address by creating our own ip packet */
+static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast)
+{
+	const uint8_t *chaddr;
+	uint32_t ciaddr;
+
+	if (force_broadcast) {
+		DEBUG("broadcasting packet to client (NAK)");
+		ciaddr = INADDR_BROADCAST;
+		chaddr = MAC_BCAST_ADDR;
+	} else if (payload->ciaddr) {
+		DEBUG("unicasting packet to client ciaddr");
+		ciaddr = payload->ciaddr;
+		chaddr = payload->chaddr;
+	} else if (payload->flags & htons(BROADCAST_FLAG)) {
+		DEBUG("broadcasting packet to client (requested)");
+		ciaddr = INADDR_BROADCAST;
+		chaddr = MAC_BCAST_ADDR;
+	} else {
+		DEBUG("unicasting packet to client yiaddr");
+		ciaddr = payload->yiaddr;
+		chaddr = payload->chaddr;
+	}
+	return udhcp_send_raw_packet(payload,
+		/*src*/ server_config.server, SERVER_PORT,
+		/*dst*/ ciaddr, CLIENT_PORT, chaddr,
+		server_config.ifindex);
+}
+
+
+/* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
+static int send_packet(struct dhcpMessage *payload, int force_broadcast)
+{
+	if (payload->giaddr)
+		return send_packet_to_relay(payload);
+	return send_packet_to_client(payload, force_broadcast);
+}
+
+
+static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type)
+{
+	udhcp_init_header(packet, type);
+	packet->xid = oldpacket->xid;
+	memcpy(packet->chaddr, oldpacket->chaddr, 16);
+	packet->flags = oldpacket->flags;
+	packet->giaddr = oldpacket->giaddr;
+	packet->ciaddr = oldpacket->ciaddr;
+	add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);
+}
+
+
+/* add in the bootp options */
+static void add_bootp_options(struct dhcpMessage *packet)
+{
+	packet->siaddr = server_config.siaddr;
+	if (server_config.sname)
+		strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
+	if (server_config.boot_file)
+		strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
+}
+
+
+/* send a DHCP OFFER to a DHCP DISCOVER */
+int FAST_FUNC send_offer(struct dhcpMessage *oldpacket)
+{
+	struct dhcpMessage packet;
+	struct dhcpOfferedAddr *lease = NULL;
+	uint32_t req_align, lease_time_align = server_config.lease;
+	uint8_t *req, *lease_time;
+	struct option_set *curr;
+	struct in_addr addr;
+
+	uint32_t static_lease_ip;
+
+	init_packet(&packet, oldpacket, DHCPOFFER);
+
+	static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);
+
+	/* ADDME: if static, short circuit */
+	if (!static_lease_ip) {
+		/* the client is in our lease/offered table */
+		lease = find_lease_by_chaddr(oldpacket->chaddr);
+		if (lease) {
+			if (!lease_expired(lease))
+				lease_time_align = lease->expires - time(0);
+			packet.yiaddr = lease->yiaddr;
+		/* Or the client has a requested ip */
+		} else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP))
+		 /* Don't look here (ugly hackish thing to do) */
+		 && memcpy(&req_align, req, 4)
+		 /* and the ip is in the lease range */
+		 && ntohl(req_align) >= server_config.start_ip
+		 && ntohl(req_align) <= server_config.end_ip
+		 && !static_lease_ip /* Check that its not a static lease */
+		 /* and is not already taken/offered */
+		 && (!(lease = find_lease_by_yiaddr(req_align))
+			/* or its taken, but expired */ /* ADDME: or maybe in here */
+			|| lease_expired(lease))
+		) {
+			packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */
+			/* otherwise, find a free IP */
+		} else {
+			/* Is it a static lease? (No, because find_address skips static lease) */
+			packet.yiaddr = find_address(0);
+			/* try for an expired lease */
+			if (!packet.yiaddr)
+				packet.yiaddr = find_address(1);
+		}
+
+		if (!packet.yiaddr) {
+			bb_error_msg("no IP addresses to give - OFFER abandoned");
+			return -1;
+		}
+		if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {
+			bb_error_msg("lease pool is full - OFFER abandoned");
+			return -1;
+		}
+		lease_time = get_option(oldpacket, DHCP_LEASE_TIME);
+		if (lease_time) {
+			memcpy(&lease_time_align, lease_time, 4);
+			lease_time_align = ntohl(lease_time_align);
+			if (lease_time_align > server_config.lease)
+				lease_time_align = server_config.lease;
+		}
+
+		/* Make sure we aren't just using the lease time from the previous offer */
+		if (lease_time_align < server_config.min_lease)
+			lease_time_align = server_config.lease;
+		/* ADDME: end of short circuit */
+	} else {
+		/* It is a static lease... use it */
+		packet.yiaddr = static_lease_ip;
+	}
+
+	add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
+
+	curr = server_config.options;
+	while (curr) {
+		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+			add_option_string(packet.options, curr->data);
+		curr = curr->next;
+	}
+
+	add_bootp_options(&packet);
+
+	addr.s_addr = packet.yiaddr;
+	bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
+	return send_packet(&packet, 0);
+}
+
+
+int FAST_FUNC send_NAK(struct dhcpMessage *oldpacket)
+{
+	struct dhcpMessage packet;
+
+	init_packet(&packet, oldpacket, DHCPNAK);
+
+	DEBUG("Sending NAK");
+	return send_packet(&packet, 1);
+}
+
+
+int FAST_FUNC send_ACK(struct dhcpMessage *oldpacket, uint32_t yiaddr)
+{
+	struct dhcpMessage packet;
+	struct option_set *curr;
+	uint8_t *lease_time;
+	uint32_t lease_time_align = server_config.lease;
+	struct in_addr addr;
+
+	init_packet(&packet, oldpacket, DHCPACK);
+	packet.yiaddr = yiaddr;
+
+	lease_time = get_option(oldpacket, DHCP_LEASE_TIME);
+	if (lease_time) {
+		memcpy(&lease_time_align, lease_time, 4);
+		lease_time_align = ntohl(lease_time_align);
+		if (lease_time_align > server_config.lease)
+			lease_time_align = server_config.lease;
+		else if (lease_time_align < server_config.min_lease)
+			lease_time_align = server_config.lease;
+	}
+
+	add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
+
+	curr = server_config.options;
+	while (curr) {
+		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+			add_option_string(packet.options, curr->data);
+		curr = curr->next;
+	}
+
+	add_bootp_options(&packet);
+
+	addr.s_addr = packet.yiaddr;
+	bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
+
+	if (send_packet(&packet, 0) < 0)
+		return -1;
+
+	add_lease(packet.chaddr, packet.yiaddr, lease_time_align);
+	if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
+		/* rewrite the file with leases at every new acceptance */
+		write_leases();
+	}
+
+	return 0;
+}
+
+
+int FAST_FUNC send_inform(struct dhcpMessage *oldpacket)
+{
+	struct dhcpMessage packet;
+	struct option_set *curr;
+
+	init_packet(&packet, oldpacket, DHCPACK);
+
+	curr = server_config.options;
+	while (curr) {
+		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+			add_option_string(packet.options, curr->data);
+		curr = curr->next;
+	}
+
+	add_bootp_options(&packet);
+
+	return send_packet(&packet, 0);
+}