diff options
Diffstat (limited to 'networking/udhcp/serverpacket.c')
| -rw-r--r-- | networking/udhcp/serverpacket.c | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/networking/udhcp/serverpacket.c b/networking/udhcp/serverpacket.c new file mode 100644 index 000000000..fe880b4a0 --- /dev/null +++ b/networking/udhcp/serverpacket.c @@ -0,0 +1,275 @@ +/* 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 <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> +#include <string.h> +#include <time.h> + +#include "common.h" +#include "serverpacket.h" +#include "dhcpd.h" +#include "options.h" +#include "static_leases.h" + +/* send a packet to giaddr using the kernel ip stack */ +static int send_packet_to_relay(struct dhcpMessage *payload) +{ + DEBUG(LOG_INFO, "Forwarding packet to relay"); + + return 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) +{ + uint8_t *chaddr; + uint32_t ciaddr; + + if (force_broadcast) { + DEBUG(LOG_INFO, "broadcasting packet to client (NAK)"); + ciaddr = INADDR_BROADCAST; + chaddr = MAC_BCAST_ADDR; + } else if (payload->ciaddr) { + DEBUG(LOG_INFO, "unicasting packet to client ciaddr"); + ciaddr = payload->ciaddr; + chaddr = payload->chaddr; + } else if (ntohs(payload->flags) & BROADCAST_FLAG) { + DEBUG(LOG_INFO, "broadcasting packet to client (requested)"); + ciaddr = INADDR_BROADCAST; + chaddr = MAC_BCAST_ADDR; + } else { + DEBUG(LOG_INFO, "unicasting packet to client yiaddr"); + ciaddr = payload->yiaddr; + chaddr = payload->chaddr; + } + return raw_packet(payload, server_config.server, SERVER_PORT, + 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) +{ + int ret; + + if (payload->giaddr) + ret = send_packet_to_relay(payload); + else ret = send_packet_to_client(payload, force_broadcast); + return ret; +} + + +static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type) +{ + 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 sendOffer(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 */ + if ((lease = find_lease_by_chaddr(oldpacket->chaddr))) { + 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) >= ntohl(server_config.start) && + ntohl(req_align) <= ntohl(server_config.end) && + + !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) { + LOG(LOG_WARNING, "no IP addresses to give -- OFFER abandoned"); + return -1; + } + + if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) { + LOG(LOG_WARNING, "lease pool is full -- OFFER abandoned"); + return -1; + } + + if ((lease_time = get_option(oldpacket, DHCP_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; + LOG(LOG_INFO, "sending OFFER of %s", inet_ntoa(addr)); + return send_packet(&packet, 0); +} + + +int sendNAK(struct dhcpMessage *oldpacket) +{ + struct dhcpMessage packet; + + init_packet(&packet, oldpacket, DHCPNAK); + + DEBUG(LOG_INFO, "sending NAK"); + return send_packet(&packet, 1); +} + + +int sendACK(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; + + if ((lease_time = get_option(oldpacket, DHCP_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; + LOG(LOG_INFO, "sending ACK to %s", inet_ntoa(addr)); + + if (send_packet(&packet, 0) < 0) + return -1; + + add_lease(packet.chaddr, packet.yiaddr, lease_time_align); + + return 0; +} + + +int 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); +} |