Magellan Linux

  • Back to homepage
    • /[magellan-source]/trunk/mkinitrd-magellan/busybox/networking/udhcp/serverpacket.c

    Contents of /trunk/mkinitrd-magellan/busybox/networking/udhcp/serverpacket.c

    Parent Directory Parent Directory | Revision Log Revision Log

    Revision 984 - (show annotations) (download)
    Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
    File MIME type: text/plain
    File size: 8159 byte(s) 
    -updated to busybox-1.16.1 and enabled blkid/uuid support in default config
    1 /* vi: set sw=4 ts=4: */
    2 /* serverpacket.c
    3 *
    4 * Construct and send DHCP server packets
    5 *
    6 * Russ Dill <Russ.Dill@asu.edu> July 2001
    7 *
    8 * This program is free software; you can redistribute it and/or modify
    9 * it under the terms of the GNU General Public License as published by
    10 * the Free Software Foundation; either version 2 of the License, or
    11 * (at your option) any later version.
    12 *
    13 * This program is distributed in the hope that it will be useful,
    14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
    15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    16 * GNU General Public License for more details.
    17 *
    18 * You should have received a copy of the GNU General Public License
    19 * along with this program; if not, write to the Free Software
    20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
    21 */
    22
    23 #include "common.h"
    24 #include "dhcpc.h"
    25 #include "dhcpd.h"
    26 #include "options.h"
    27
    28
    29 /* send a packet to gateway_nip using the kernel ip stack */
    30 static int send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
    31 {
    32 log1("Forwarding packet to relay");
    33
    34 return udhcp_send_kernel_packet(dhcp_pkt,
    35 server_config.server_nip, SERVER_PORT,
    36 dhcp_pkt->gateway_nip, SERVER_PORT);
    37 }
    38
    39
    40 /* send a packet to a specific mac address and ip address by creating our own ip packet */
    41 static int send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
    42 {
    43 const uint8_t *chaddr;
    44 uint32_t ciaddr;
    45
    46 // Was:
    47 //if (force_broadcast) { /* broadcast */ }
    48 //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ }
    49 //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ }
    50 //else { /* unicast to dhcp_pkt->yiaddr */ }
    51 // But this is wrong: yiaddr is _our_ idea what client's IP is
    52 // (for example, from lease file). Client may not know that,
    53 // and may not have UDP socket listening on that IP!
    54 // We should never unicast to dhcp_pkt->yiaddr!
    55 // dhcp_pkt->ciaddr, OTOH, comes from client's request packet,
    56 // and can be used.
    57
    58 if (force_broadcast
    59 || (dhcp_pkt->flags & htons(BROADCAST_FLAG))
    60 || !dhcp_pkt->ciaddr
    61 ) {
    62 log1("Broadcasting packet to client");
    63 ciaddr = INADDR_BROADCAST;
    64 chaddr = MAC_BCAST_ADDR;
    65 } else {
    66 log1("Unicasting packet to client ciaddr");
    67 ciaddr = dhcp_pkt->ciaddr;
    68 chaddr = dhcp_pkt->chaddr;
    69 }
    70
    71 return udhcp_send_raw_packet(dhcp_pkt,
    72 /*src*/ server_config.server_nip, SERVER_PORT,
    73 /*dst*/ ciaddr, CLIENT_PORT, chaddr,
    74 server_config.ifindex);
    75 }
    76
    77
    78 /* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
    79 static int send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
    80 {
    81 if (dhcp_pkt->gateway_nip)
    82 return send_packet_to_relay(dhcp_pkt);
    83 return send_packet_to_client(dhcp_pkt, force_broadcast);
    84 }
    85
    86
    87 static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type)
    88 {
    89 udhcp_init_header(packet, type);
    90 packet->xid = oldpacket->xid;
    91 memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
    92 packet->flags = oldpacket->flags;
    93 packet->gateway_nip = oldpacket->gateway_nip;
    94 packet->ciaddr = oldpacket->ciaddr;
    95 add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server_nip);
    96 }
    97
    98
    99 /* add in the bootp options */
    100 static void add_bootp_options(struct dhcp_packet *packet)
    101 {
    102 packet->siaddr_nip = server_config.siaddr_nip;
    103 if (server_config.sname)
    104 strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
    105 if (server_config.boot_file)
    106 strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
    107 }
    108
    109
    110 static uint32_t select_lease_time(struct dhcp_packet *packet)
    111 {
    112 uint32_t lease_time_sec = server_config.max_lease_sec;
    113 uint8_t *lease_time_opt = get_option(packet, DHCP_LEASE_TIME);
    114 if (lease_time_opt) {
    115 move_from_unaligned32(lease_time_sec, lease_time_opt);
    116 lease_time_sec = ntohl(lease_time_sec);
    117 if (lease_time_sec > server_config.max_lease_sec)
    118 lease_time_sec = server_config.max_lease_sec;
    119 if (lease_time_sec < server_config.min_lease_sec)
    120 lease_time_sec = server_config.min_lease_sec;
    121 }
    122 return lease_time_sec;
    123 }
    124
    125
    126 /* send a DHCP OFFER to a DHCP DISCOVER */
    127 int FAST_FUNC send_offer(struct dhcp_packet *oldpacket)
    128 {
    129 struct dhcp_packet packet;
    130 uint32_t req_nip;
    131 uint32_t lease_time_sec = server_config.max_lease_sec;
    132 uint32_t static_lease_ip;
    133 uint8_t *req_ip_opt;
    134 const char *p_host_name;
    135 struct option_set *curr;
    136 struct in_addr addr;
    137
    138 init_packet(&packet, oldpacket, DHCPOFFER);
    139
    140 static_lease_ip = get_static_nip_by_mac(server_config.static_leases, oldpacket->chaddr);
    141
    142 /* ADDME: if static, short circuit */
    143 if (!static_lease_ip) {
    144 struct dyn_lease *lease;
    145
    146 lease = find_lease_by_mac(oldpacket->chaddr);
    147 /* The client is in our lease/offered table */
    148 if (lease) {
    149 signed_leasetime_t tmp = lease->expires - time(NULL);
    150 if (tmp >= 0)
    151 lease_time_sec = tmp;
    152 packet.yiaddr = lease->lease_nip;
    153 }
    154 /* Or the client has requested an IP */
    155 else if ((req_ip_opt = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL
    156 /* (read IP) */
    157 && (move_from_unaligned32(req_nip, req_ip_opt), 1)
    158 /* and the IP is in the lease range */
    159 && ntohl(req_nip) >= server_config.start_ip
    160 && ntohl(req_nip) <= server_config.end_ip
    161 /* and is not already taken/offered */
    162 && (!(lease = find_lease_by_nip(req_nip))
    163 /* or its taken, but expired */
    164 || is_expired_lease(lease))
    165 ) {
    166 packet.yiaddr = req_nip;
    167 }
    168 /* Otherwise, find a free IP */
    169 else {
    170 packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr);
    171 }
    172
    173 if (!packet.yiaddr) {
    174 bb_error_msg("no IP addresses to give - OFFER abandoned");
    175 return -1;
    176 }
    177 p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
    178 if (add_lease(packet.chaddr, packet.yiaddr,
    179 server_config.offer_time,
    180 p_host_name,
    181 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
    182 ) == 0
    183 ) {
    184 bb_error_msg("lease pool is full - OFFER abandoned");
    185 return -1;
    186 }
    187 lease_time_sec = select_lease_time(oldpacket);
    188 } else {
    189 /* It is a static lease... use it */
    190 packet.yiaddr = static_lease_ip;
    191 }
    192
    193 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
    194
    195 curr = server_config.options;
    196 while (curr) {
    197 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
    198 add_option_string(packet.options, curr->data);
    199 curr = curr->next;
    200 }
    201
    202 add_bootp_options(&packet);
    203
    204 addr.s_addr = packet.yiaddr;
    205 bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
    206 return send_packet(&packet, 0);
    207 }
    208
    209
    210 int FAST_FUNC send_NAK(struct dhcp_packet *oldpacket)
    211 {
    212 struct dhcp_packet packet;
    213
    214 init_packet(&packet, oldpacket, DHCPNAK);
    215
    216 log1("Sending NAK");
    217 return send_packet(&packet, 1);
    218 }
    219
    220
    221 int FAST_FUNC send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
    222 {
    223 struct dhcp_packet packet;
    224 struct option_set *curr;
    225 uint32_t lease_time_sec;
    226 struct in_addr addr;
    227 const char *p_host_name;
    228
    229 init_packet(&packet, oldpacket, DHCPACK);
    230 packet.yiaddr = yiaddr;
    231
    232 lease_time_sec = select_lease_time(oldpacket);
    233
    234 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
    235
    236 curr = server_config.options;
    237 while (curr) {
    238 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
    239 add_option_string(packet.options, curr->data);
    240 curr = curr->next;
    241 }
    242
    243 add_bootp_options(&packet);
    244
    245 addr.s_addr = packet.yiaddr;
    246 bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
    247
    248 if (send_packet(&packet, 0) < 0)
    249 return -1;
    250
    251 p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
    252 add_lease(packet.chaddr, packet.yiaddr,
    253 lease_time_sec,
    254 p_host_name,
    255 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
    256 );
    257 if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
    258 /* rewrite the file with leases at every new acceptance */
    259 write_leases();
    260 }
    261
    262 return 0;
    263 }
    264
    265
    266 int FAST_FUNC send_inform(struct dhcp_packet *oldpacket)
    267 {
    268 struct dhcp_packet packet;
    269 struct option_set *curr;
    270
    271 init_packet(&packet, oldpacket, DHCPACK);
    272
    273 curr = server_config.options;
    274 while (curr) {
    275 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
    276 add_option_string(packet.options, curr->data);
    277 curr = curr->next;
    278 }
    279
    280 add_bootp_options(&packet);
    281
    282 return send_packet(&packet, 0);
    283 }