[1765] | 1 | /* vi: set sw=4 ts=4: */
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[2725] | 2 | /*
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| 3 | * udhcp server
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[821] | 4 | * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
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| 5 | * Chris Trew <ctrew@moreton.com.au>
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| 6 | *
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| 7 | * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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| 8 | *
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[2725] | 9 | * This program is free software; you can redistribute it and/or modify
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| 10 | * it under the terms of the GNU General Public License as published by
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| 11 | * the Free Software Foundation; either version 2 of the License, or
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| 12 | * (at your option) any later version.
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| 13 | *
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| 14 | * This program is distributed in the hope that it will be useful,
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| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 17 | * GNU General Public License for more details.
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| 18 | *
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| 19 | * You should have received a copy of the GNU General Public License
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| 20 | * along with this program; if not, write to the Free Software
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| 21 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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[821] | 22 | */
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[3232] | 23 |
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| 24 | //usage:#define udhcpd_trivial_usage
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| 25 | //usage: "[-fS]" IF_FEATURE_UDHCP_PORT(" [-P N]") " [CONFFILE]"
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| 26 | //usage:#define udhcpd_full_usage "\n\n"
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| 27 | //usage: "DHCP server\n"
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| 28 | //usage: "\n -f Run in foreground"
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| 29 | //usage: "\n -S Log to syslog too"
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| 30 | //usage: IF_FEATURE_UDHCP_PORT(
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| 31 | //usage: "\n -P N Use port N (default 67)"
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| 32 | //usage: )
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| 33 |
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[1765] | 34 | #include <syslog.h>
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| 35 | #include "common.h"
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[2725] | 36 | #include "dhcpc.h"
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[821] | 37 | #include "dhcpd.h"
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| 38 |
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| 39 |
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[2725] | 40 | /* Send a packet to a specific mac address and ip address by creating our own ip packet */
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| 41 | static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
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| 42 | {
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| 43 | const uint8_t *chaddr;
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| 44 | uint32_t ciaddr;
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| 45 |
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| 46 | // Was:
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| 47 | //if (force_broadcast) { /* broadcast */ }
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| 48 | //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ }
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| 49 | //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ }
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| 50 | //else { /* unicast to dhcp_pkt->yiaddr */ }
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| 51 | // But this is wrong: yiaddr is _our_ idea what client's IP is
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| 52 | // (for example, from lease file). Client may not know that,
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| 53 | // and may not have UDP socket listening on that IP!
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| 54 | // We should never unicast to dhcp_pkt->yiaddr!
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| 55 | // dhcp_pkt->ciaddr, OTOH, comes from client's request packet,
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| 56 | // and can be used.
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| 57 |
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| 58 | if (force_broadcast
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| 59 | || (dhcp_pkt->flags & htons(BROADCAST_FLAG))
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| 60 | || dhcp_pkt->ciaddr == 0
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| 61 | ) {
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| 62 | log1("Broadcasting packet to client");
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| 63 | ciaddr = INADDR_BROADCAST;
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| 64 | chaddr = MAC_BCAST_ADDR;
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| 65 | } else {
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| 66 | log1("Unicasting packet to client ciaddr");
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| 67 | ciaddr = dhcp_pkt->ciaddr;
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| 68 | chaddr = dhcp_pkt->chaddr;
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| 69 | }
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| 70 |
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| 71 | udhcp_send_raw_packet(dhcp_pkt,
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| 72 | /*src*/ server_config.server_nip, SERVER_PORT,
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| 73 | /*dst*/ ciaddr, CLIENT_PORT, chaddr,
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| 74 | server_config.ifindex);
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| 75 | }
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| 76 |
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| 77 | /* Send a packet to gateway_nip using the kernel ip stack */
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| 78 | static void send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
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| 79 | {
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| 80 | log1("Forwarding packet to relay");
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| 81 |
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| 82 | udhcp_send_kernel_packet(dhcp_pkt,
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| 83 | server_config.server_nip, SERVER_PORT,
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| 84 | dhcp_pkt->gateway_nip, SERVER_PORT);
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| 85 | }
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| 86 |
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| 87 | static void send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
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| 88 | {
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| 89 | if (dhcp_pkt->gateway_nip)
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| 90 | send_packet_to_relay(dhcp_pkt);
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| 91 | else
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| 92 | send_packet_to_client(dhcp_pkt, force_broadcast);
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| 93 | }
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| 94 |
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| 95 | static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type)
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| 96 | {
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| 97 | /* Sets op, htype, hlen, cookie fields
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| 98 | * and adds DHCP_MESSAGE_TYPE option */
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| 99 | udhcp_init_header(packet, type);
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| 100 |
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| 101 | packet->xid = oldpacket->xid;
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| 102 | memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
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| 103 | packet->flags = oldpacket->flags;
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| 104 | packet->gateway_nip = oldpacket->gateway_nip;
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| 105 | packet->ciaddr = oldpacket->ciaddr;
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| 106 | udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip);
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| 107 | }
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| 108 |
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| 109 | /* Fill options field, siaddr_nip, and sname and boot_file fields.
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| 110 | * TODO: teach this code to use overload option.
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| 111 | */
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| 112 | static void add_server_options(struct dhcp_packet *packet)
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| 113 | {
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| 114 | struct option_set *curr = server_config.options;
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| 115 |
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| 116 | while (curr) {
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| 117 | if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
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| 118 | udhcp_add_binary_option(packet, curr->data);
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| 119 | curr = curr->next;
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| 120 | }
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| 121 |
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| 122 | packet->siaddr_nip = server_config.siaddr_nip;
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| 123 |
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| 124 | if (server_config.sname)
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| 125 | strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
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| 126 | if (server_config.boot_file)
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| 127 | strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
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| 128 | }
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| 129 |
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| 130 | static uint32_t select_lease_time(struct dhcp_packet *packet)
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| 131 | {
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| 132 | uint32_t lease_time_sec = server_config.max_lease_sec;
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| 133 | uint8_t *lease_time_opt = udhcp_get_option(packet, DHCP_LEASE_TIME);
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| 134 | if (lease_time_opt) {
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| 135 | move_from_unaligned32(lease_time_sec, lease_time_opt);
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| 136 | lease_time_sec = ntohl(lease_time_sec);
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| 137 | if (lease_time_sec > server_config.max_lease_sec)
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| 138 | lease_time_sec = server_config.max_lease_sec;
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| 139 | if (lease_time_sec < server_config.min_lease_sec)
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| 140 | lease_time_sec = server_config.min_lease_sec;
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| 141 | }
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| 142 | return lease_time_sec;
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| 143 | }
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| 144 |
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| 145 | /* We got a DHCP DISCOVER. Send an OFFER. */
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| 146 | /* NOINLINE: limit stack usage in caller */
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[3232] | 147 | static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
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| 148 | uint32_t static_lease_nip,
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| 149 | struct dyn_lease *lease,
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| 150 | uint8_t *requested_ip_opt)
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[2725] | 151 | {
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| 152 | struct dhcp_packet packet;
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| 153 | uint32_t lease_time_sec;
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| 154 | struct in_addr addr;
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| 155 |
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| 156 | init_packet(&packet, oldpacket, DHCPOFFER);
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| 157 |
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| 158 | /* If it is a static lease, use its IP */
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| 159 | packet.yiaddr = static_lease_nip;
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| 160 | /* Else: */
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| 161 | if (!static_lease_nip) {
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| 162 | /* We have no static lease for client's chaddr */
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| 163 | uint32_t req_nip;
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| 164 | const char *p_host_name;
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| 165 |
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| 166 | if (lease) {
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| 167 | /* We have a dynamic lease for client's chaddr.
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| 168 | * Reuse its IP (even if lease is expired).
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| 169 | * Note that we ignore requested IP in this case.
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| 170 | */
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| 171 | packet.yiaddr = lease->lease_nip;
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| 172 | }
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| 173 | /* Or: if client has requested an IP */
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[3232] | 174 | else if (requested_ip_opt != NULL
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[2725] | 175 | /* (read IP) */
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[3232] | 176 | && (move_from_unaligned32(req_nip, requested_ip_opt), 1)
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[2725] | 177 | /* and the IP is in the lease range */
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| 178 | && ntohl(req_nip) >= server_config.start_ip
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| 179 | && ntohl(req_nip) <= server_config.end_ip
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| 180 | /* and */
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| 181 | && ( !(lease = find_lease_by_nip(req_nip)) /* is not already taken */
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| 182 | || is_expired_lease(lease) /* or is taken, but expired */
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| 183 | )
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| 184 | ) {
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| 185 | packet.yiaddr = req_nip;
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| 186 | }
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| 187 | else {
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| 188 | /* Otherwise, find a free IP */
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| 189 | packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr);
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| 190 | }
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| 191 |
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| 192 | if (!packet.yiaddr) {
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| 193 | bb_error_msg("no free IP addresses. OFFER abandoned");
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| 194 | return;
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| 195 | }
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| 196 | /* Reserve the IP for a short time hoping to get DHCPREQUEST soon */
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| 197 | p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
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| 198 | lease = add_lease(packet.chaddr, packet.yiaddr,
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| 199 | server_config.offer_time,
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| 200 | p_host_name,
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| 201 | p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
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| 202 | );
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| 203 | if (!lease) {
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| 204 | bb_error_msg("no free IP addresses. OFFER abandoned");
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| 205 | return;
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| 206 | }
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| 207 | }
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| 208 |
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| 209 | lease_time_sec = select_lease_time(oldpacket);
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| 210 | udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
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| 211 | add_server_options(&packet);
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| 212 |
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| 213 | addr.s_addr = packet.yiaddr;
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| 214 | bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
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| 215 | /* send_packet emits error message itself if it detects failure */
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| 216 | send_packet(&packet, /*force_bcast:*/ 0);
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| 217 | }
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| 218 |
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| 219 | /* NOINLINE: limit stack usage in caller */
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| 220 | static NOINLINE void send_NAK(struct dhcp_packet *oldpacket)
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| 221 | {
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| 222 | struct dhcp_packet packet;
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| 223 |
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| 224 | init_packet(&packet, oldpacket, DHCPNAK);
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| 225 |
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| 226 | log1("Sending NAK");
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| 227 | send_packet(&packet, /*force_bcast:*/ 1);
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| 228 | }
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| 229 |
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| 230 | /* NOINLINE: limit stack usage in caller */
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| 231 | static NOINLINE void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
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| 232 | {
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| 233 | struct dhcp_packet packet;
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| 234 | uint32_t lease_time_sec;
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| 235 | struct in_addr addr;
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| 236 | const char *p_host_name;
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| 237 |
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| 238 | init_packet(&packet, oldpacket, DHCPACK);
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| 239 | packet.yiaddr = yiaddr;
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| 240 |
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| 241 | lease_time_sec = select_lease_time(oldpacket);
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| 242 | udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
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| 243 |
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| 244 | add_server_options(&packet);
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| 245 |
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| 246 | addr.s_addr = yiaddr;
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| 247 | bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
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| 248 | send_packet(&packet, /*force_bcast:*/ 0);
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| 249 |
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| 250 | p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
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| 251 | add_lease(packet.chaddr, packet.yiaddr,
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| 252 | lease_time_sec,
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| 253 | p_host_name,
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| 254 | p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
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| 255 | );
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| 256 | if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
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| 257 | /* rewrite the file with leases at every new acceptance */
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| 258 | write_leases();
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| 259 | }
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| 260 | }
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| 261 |
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| 262 | /* NOINLINE: limit stack usage in caller */
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| 263 | static NOINLINE void send_inform(struct dhcp_packet *oldpacket)
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| 264 | {
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| 265 | struct dhcp_packet packet;
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| 266 |
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| 267 | /* "If a client has obtained a network address through some other means
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| 268 | * (e.g., manual configuration), it may use a DHCPINFORM request message
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| 269 | * to obtain other local configuration parameters. Servers receiving a
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| 270 | * DHCPINFORM message construct a DHCPACK message with any local
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| 271 | * configuration parameters appropriate for the client without:
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| 272 | * allocating a new address, checking for an existing binding, filling
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| 273 | * in 'yiaddr' or including lease time parameters. The servers SHOULD
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| 274 | * unicast the DHCPACK reply to the address given in the 'ciaddr' field
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| 275 | * of the DHCPINFORM message.
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| 276 | * ...
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| 277 | * The server responds to a DHCPINFORM message by sending a DHCPACK
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| 278 | * message directly to the address given in the 'ciaddr' field
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| 279 | * of the DHCPINFORM message. The server MUST NOT send a lease
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| 280 | * expiration time to the client and SHOULD NOT fill in 'yiaddr'."
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| 281 | */
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| 282 | //TODO: do a few sanity checks: is ciaddr set?
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| 283 | //Better yet: is ciaddr == IP source addr?
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| 284 | init_packet(&packet, oldpacket, DHCPACK);
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| 285 | add_server_options(&packet);
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| 286 |
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| 287 | send_packet(&packet, /*force_bcast:*/ 0);
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| 288 | }
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| 289 |
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| 290 |
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[821] | 291 | /* globals */
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[2725] | 292 | struct dyn_lease *g_leases;
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| 293 | /* struct server_config_t server_config is in bb_common_bufsiz1 */
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[821] | 294 |
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| 295 |
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[2725] | 296 | int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 297 | int udhcpd_main(int argc UNUSED_PARAM, char **argv)
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[821] | 298 | {
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[2725] | 299 | int server_socket = -1, retval, max_sock;
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| 300 | uint8_t *state;
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[1765] | 301 | unsigned timeout_end;
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| 302 | unsigned num_ips;
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| 303 | unsigned opt;
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[821] | 304 | struct option_set *option;
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[2725] | 305 | IF_FEATURE_UDHCP_PORT(char *str_P;)
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[821] | 306 |
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[2725] | 307 | #if ENABLE_FEATURE_UDHCP_PORT
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| 308 | SERVER_PORT = 67;
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| 309 | CLIENT_PORT = 68;
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| 310 | #endif
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[821] | 311 |
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[2725] | 312 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
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| 313 | opt_complementary = "vv";
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| 314 | #endif
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| 315 | opt = getopt32(argv, "fSv"
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| 316 | IF_FEATURE_UDHCP_PORT("P:", &str_P)
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[3232] | 317 | IF_UDHCP_VERBOSE(, &dhcp_verbose)
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[2725] | 318 | );
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[1765] | 319 | if (!(opt & 1)) { /* no -f */
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| 320 | bb_daemonize_or_rexec(0, argv);
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[2725] | 321 | logmode = LOGMODE_NONE;
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[1765] | 322 | }
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[2725] | 323 | /* update argv after the possible vfork+exec in daemonize */
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| 324 | argv += optind;
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[1765] | 325 | if (opt & 2) { /* -S */
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[2725] | 326 | openlog(applet_name, LOG_PID, LOG_DAEMON);
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[1765] | 327 | logmode |= LOGMODE_SYSLOG;
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| 328 | }
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[2725] | 329 | #if ENABLE_FEATURE_UDHCP_PORT
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| 330 | if (opt & 8) { /* -P */
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| 331 | SERVER_PORT = xatou16(str_P);
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| 332 | CLIENT_PORT = SERVER_PORT + 1;
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| 333 | }
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| 334 | #endif
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[1765] | 335 | /* Would rather not do read_config before daemonization -
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| 336 | * otherwise NOMMU machines will parse config twice */
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| 337 | read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
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| 338 |
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| 339 | /* Make sure fd 0,1,2 are open */
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| 340 | bb_sanitize_stdio();
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| 341 | /* Equivalent of doing a fflush after every \n */
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| 342 | setlinebuf(stdout);
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| 343 |
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| 344 | /* Create pidfile */
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| 345 | write_pidfile(server_config.pidfile);
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[2725] | 346 | /* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */
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[1765] | 347 |
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[2725] | 348 | bb_info_msg("%s (v"BB_VER") started", applet_name);
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[1765] | 349 |
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[2725] | 350 | option = udhcp_find_option(server_config.options, DHCP_LEASE_TIME);
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| 351 | server_config.max_lease_sec = DEFAULT_LEASE_TIME;
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[1765] | 352 | if (option) {
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[2725] | 353 | move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
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| 354 | server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
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[821] | 355 | }
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| 356 |
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| 357 | /* Sanity check */
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[1765] | 358 | num_ips = server_config.end_ip - server_config.start_ip + 1;
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[821] | 359 | if (server_config.max_leases > num_ips) {
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[1765] | 360 | bb_error_msg("max_leases=%u is too big, setting to %u",
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| 361 | (unsigned)server_config.max_leases, num_ips);
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[821] | 362 | server_config.max_leases = num_ips;
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| 363 | }
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| 364 |
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[2725] | 365 | g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0]));
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[821] | 366 | read_leases(server_config.lease_file);
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| 367 |
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[2725] | 368 | if (udhcp_read_interface(server_config.interface,
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| 369 | &server_config.ifindex,
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| 370 | &server_config.server_nip,
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| 371 | server_config.server_mac)
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| 372 | ) {
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[1765] | 373 | retval = 1;
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| 374 | goto ret;
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| 375 | }
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[821] | 376 |
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| 377 | /* Setup the signal pipe */
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| 378 | udhcp_sp_setup();
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| 379 |
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[3232] | 380 | continue_with_autotime:
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[1765] | 381 | timeout_end = monotonic_sec() + server_config.auto_time;
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| 382 | while (1) { /* loop until universe collapses */
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[3232] | 383 | fd_set rfds;
|
---|
| 384 | struct dhcp_packet packet;
|
---|
[2725] | 385 | int bytes;
|
---|
| 386 | struct timeval tv;
|
---|
| 387 | uint8_t *server_id_opt;
|
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[3232] | 388 | uint8_t *requested_ip_opt;
|
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[2725] | 389 | uint32_t requested_nip = requested_nip; /* for compiler */
|
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[3232] | 390 | uint32_t static_lease_nip;
|
---|
| 391 | struct dyn_lease *lease, fake_lease;
|
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[821] | 392 |
|
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[1765] | 393 | if (server_socket < 0) {
|
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[2725] | 394 | server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
|
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[1765] | 395 | server_config.interface);
|
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| 396 | }
|
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[821] | 397 |
|
---|
| 398 | max_sock = udhcp_sp_fd_set(&rfds, server_socket);
|
---|
| 399 | if (server_config.auto_time) {
|
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[1765] | 400 | tv.tv_sec = timeout_end - monotonic_sec();
|
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[821] | 401 | tv.tv_usec = 0;
|
---|
| 402 | }
|
---|
[1765] | 403 | retval = 0;
|
---|
[821] | 404 | if (!server_config.auto_time || tv.tv_sec > 0) {
|
---|
| 405 | retval = select(max_sock + 1, &rfds, NULL, NULL,
|
---|
| 406 | server_config.auto_time ? &tv : NULL);
|
---|
[1765] | 407 | }
|
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[821] | 408 | if (retval == 0) {
|
---|
| 409 | write_leases();
|
---|
[3232] | 410 | goto continue_with_autotime;
|
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[1765] | 411 | }
|
---|
| 412 | if (retval < 0 && errno != EINTR) {
|
---|
[2725] | 413 | log1("Error on select");
|
---|
[821] | 414 | continue;
|
---|
| 415 | }
|
---|
| 416 |
|
---|
| 417 | switch (udhcp_sp_read(&rfds)) {
|
---|
| 418 | case SIGUSR1:
|
---|
[2725] | 419 | bb_info_msg("Received SIGUSR1");
|
---|
[821] | 420 | write_leases();
|
---|
| 421 | /* why not just reset the timeout, eh */
|
---|
[3232] | 422 | goto continue_with_autotime;
|
---|
[821] | 423 | case SIGTERM:
|
---|
[2725] | 424 | bb_info_msg("Received SIGTERM");
|
---|
[3232] | 425 | write_leases();
|
---|
[1765] | 426 | goto ret0;
|
---|
[2725] | 427 | case 0: /* no signal: read a packet */
|
---|
| 428 | break;
|
---|
| 429 | default: /* signal or error (probably EINTR): back to select */
|
---|
| 430 | continue;
|
---|
[821] | 431 | }
|
---|
| 432 |
|
---|
[2725] | 433 | bytes = udhcp_recv_kernel_packet(&packet, server_socket);
|
---|
[1765] | 434 | if (bytes < 0) {
|
---|
[2725] | 435 | /* bytes can also be -2 ("bad packet data") */
|
---|
[821] | 436 | if (bytes == -1 && errno != EINTR) {
|
---|
[2725] | 437 | log1("Read error: %s, reopening socket", strerror(errno));
|
---|
[821] | 438 | close(server_socket);
|
---|
| 439 | server_socket = -1;
|
---|
| 440 | }
|
---|
| 441 | continue;
|
---|
| 442 | }
|
---|
[2725] | 443 | if (packet.hlen != 6) {
|
---|
| 444 | bb_error_msg("MAC length != 6, ignoring packet");
|
---|
[821] | 445 | continue;
|
---|
| 446 | }
|
---|
[2725] | 447 | if (packet.op != BOOTREQUEST) {
|
---|
| 448 | bb_error_msg("not a REQUEST, ignoring packet");
|
---|
| 449 | continue;
|
---|
| 450 | }
|
---|
| 451 | state = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
|
---|
| 452 | if (state == NULL || state[0] < DHCP_MINTYPE || state[0] > DHCP_MAXTYPE) {
|
---|
| 453 | bb_error_msg("no or bad message type option, ignoring packet");
|
---|
| 454 | continue;
|
---|
| 455 | }
|
---|
[821] | 456 |
|
---|
[3232] | 457 | /* Get SERVER_ID if present */
|
---|
| 458 | server_id_opt = udhcp_get_option(&packet, DHCP_SERVER_ID);
|
---|
| 459 | if (server_id_opt) {
|
---|
| 460 | uint32_t server_id_network_order;
|
---|
| 461 | move_from_unaligned32(server_id_network_order, server_id_opt);
|
---|
| 462 | if (server_id_network_order != server_config.server_nip) {
|
---|
| 463 | /* client talks to somebody else */
|
---|
| 464 | log1("server ID doesn't match, ignoring");
|
---|
| 465 | continue;
|
---|
| 466 | }
|
---|
| 467 | }
|
---|
| 468 |
|
---|
[2725] | 469 | /* Look for a static/dynamic lease */
|
---|
| 470 | static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
|
---|
| 471 | if (static_lease_nip) {
|
---|
| 472 | bb_info_msg("Found static lease: %x", static_lease_nip);
|
---|
| 473 | memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
|
---|
| 474 | fake_lease.lease_nip = static_lease_nip;
|
---|
| 475 | fake_lease.expires = 0;
|
---|
| 476 | lease = &fake_lease;
|
---|
[1765] | 477 | } else {
|
---|
[2725] | 478 | lease = find_lease_by_mac(packet.chaddr);
|
---|
[821] | 479 | }
|
---|
| 480 |
|
---|
[3232] | 481 | /* Get REQUESTED_IP if present */
|
---|
| 482 | requested_ip_opt = udhcp_get_option(&packet, DHCP_REQUESTED_IP);
|
---|
| 483 | if (requested_ip_opt) {
|
---|
| 484 | move_from_unaligned32(requested_nip, requested_ip_opt);
|
---|
[2725] | 485 | }
|
---|
| 486 |
|
---|
[821] | 487 | switch (state[0]) {
|
---|
[2725] | 488 |
|
---|
[821] | 489 | case DHCPDISCOVER:
|
---|
[2725] | 490 | log1("Received DISCOVER");
|
---|
[821] | 491 |
|
---|
[3232] | 492 | send_offer(&packet, static_lease_nip, lease, requested_ip_opt);
|
---|
[821] | 493 | break;
|
---|
[2725] | 494 |
|
---|
[821] | 495 | case DHCPREQUEST:
|
---|
[2725] | 496 | log1("Received REQUEST");
|
---|
| 497 | /* RFC 2131:
|
---|
[821] | 498 |
|
---|
[2725] | 499 | o DHCPREQUEST generated during SELECTING state:
|
---|
[821] | 500 |
|
---|
[2725] | 501 | Client inserts the address of the selected server in 'server
|
---|
| 502 | identifier', 'ciaddr' MUST be zero, 'requested IP address' MUST be
|
---|
| 503 | filled in with the yiaddr value from the chosen DHCPOFFER.
|
---|
[821] | 504 |
|
---|
[2725] | 505 | Note that the client may choose to collect several DHCPOFFER
|
---|
| 506 | messages and select the "best" offer. The client indicates its
|
---|
| 507 | selection by identifying the offering server in the DHCPREQUEST
|
---|
| 508 | message. If the client receives no acceptable offers, the client
|
---|
| 509 | may choose to try another DHCPDISCOVER message. Therefore, the
|
---|
| 510 | servers may not receive a specific DHCPREQUEST from which they can
|
---|
| 511 | decide whether or not the client has accepted the offer.
|
---|
[821] | 512 |
|
---|
[2725] | 513 | o DHCPREQUEST generated during INIT-REBOOT state:
|
---|
[821] | 514 |
|
---|
[2725] | 515 | 'server identifier' MUST NOT be filled in, 'requested IP address'
|
---|
| 516 | option MUST be filled in with client's notion of its previously
|
---|
| 517 | assigned address. 'ciaddr' MUST be zero. The client is seeking to
|
---|
| 518 | verify a previously allocated, cached configuration. Server SHOULD
|
---|
| 519 | send a DHCPNAK message to the client if the 'requested IP address'
|
---|
| 520 | is incorrect, or is on the wrong network.
|
---|
| 521 |
|
---|
| 522 | Determining whether a client in the INIT-REBOOT state is on the
|
---|
| 523 | correct network is done by examining the contents of 'giaddr', the
|
---|
| 524 | 'requested IP address' option, and a database lookup. If the DHCP
|
---|
| 525 | server detects that the client is on the wrong net (i.e., the
|
---|
| 526 | result of applying the local subnet mask or remote subnet mask (if
|
---|
| 527 | 'giaddr' is not zero) to 'requested IP address' option value
|
---|
| 528 | doesn't match reality), then the server SHOULD send a DHCPNAK
|
---|
| 529 | message to the client.
|
---|
| 530 |
|
---|
| 531 | If the network is correct, then the DHCP server should check if
|
---|
| 532 | the client's notion of its IP address is correct. If not, then the
|
---|
| 533 | server SHOULD send a DHCPNAK message to the client. If the DHCP
|
---|
| 534 | server has no record of this client, then it MUST remain silent,
|
---|
| 535 | and MAY output a warning to the network administrator. This
|
---|
| 536 | behavior is necessary for peaceful coexistence of non-
|
---|
| 537 | communicating DHCP servers on the same wire.
|
---|
| 538 |
|
---|
| 539 | If 'giaddr' is 0x0 in the DHCPREQUEST message, the client is on
|
---|
| 540 | the same subnet as the server. The server MUST broadcast the
|
---|
| 541 | DHCPNAK message to the 0xffffffff broadcast address because the
|
---|
| 542 | client may not have a correct network address or subnet mask, and
|
---|
| 543 | the client may not be answering ARP requests.
|
---|
| 544 |
|
---|
| 545 | If 'giaddr' is set in the DHCPREQUEST message, the client is on a
|
---|
| 546 | different subnet. The server MUST set the broadcast bit in the
|
---|
| 547 | DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the
|
---|
| 548 | client, because the client may not have a correct network address
|
---|
| 549 | or subnet mask, and the client may not be answering ARP requests.
|
---|
| 550 |
|
---|
| 551 | o DHCPREQUEST generated during RENEWING state:
|
---|
| 552 |
|
---|
| 553 | 'server identifier' MUST NOT be filled in, 'requested IP address'
|
---|
| 554 | option MUST NOT be filled in, 'ciaddr' MUST be filled in with
|
---|
| 555 | client's IP address. In this situation, the client is completely
|
---|
| 556 | configured, and is trying to extend its lease. This message will
|
---|
| 557 | be unicast, so no relay agents will be involved in its
|
---|
| 558 | transmission. Because 'giaddr' is therefore not filled in, the
|
---|
| 559 | DHCP server will trust the value in 'ciaddr', and use it when
|
---|
| 560 | replying to the client.
|
---|
| 561 |
|
---|
| 562 | A client MAY choose to renew or extend its lease prior to T1. The
|
---|
| 563 | server may choose not to extend the lease (as a policy decision by
|
---|
| 564 | the network administrator), but should return a DHCPACK message
|
---|
| 565 | regardless.
|
---|
| 566 |
|
---|
| 567 | o DHCPREQUEST generated during REBINDING state:
|
---|
| 568 |
|
---|
| 569 | 'server identifier' MUST NOT be filled in, 'requested IP address'
|
---|
| 570 | option MUST NOT be filled in, 'ciaddr' MUST be filled in with
|
---|
| 571 | client's IP address. In this situation, the client is completely
|
---|
| 572 | configured, and is trying to extend its lease. This message MUST
|
---|
| 573 | be broadcast to the 0xffffffff IP broadcast address. The DHCP
|
---|
| 574 | server SHOULD check 'ciaddr' for correctness before replying to
|
---|
| 575 | the DHCPREQUEST.
|
---|
| 576 |
|
---|
| 577 | The DHCPREQUEST from a REBINDING client is intended to accommodate
|
---|
| 578 | sites that have multiple DHCP servers and a mechanism for
|
---|
| 579 | maintaining consistency among leases managed by multiple servers.
|
---|
| 580 | A DHCP server MAY extend a client's lease only if it has local
|
---|
| 581 | administrative authority to do so.
|
---|
| 582 | */
|
---|
[3232] | 583 | if (!requested_ip_opt) {
|
---|
[2725] | 584 | requested_nip = packet.ciaddr;
|
---|
| 585 | if (requested_nip == 0) {
|
---|
| 586 | log1("no requested IP and no ciaddr, ignoring");
|
---|
| 587 | break;
|
---|
[1765] | 588 | }
|
---|
[821] | 589 | }
|
---|
[2725] | 590 | if (lease && requested_nip == lease->lease_nip) {
|
---|
| 591 | /* client requested or configured IP matches the lease.
|
---|
| 592 | * ACK it, and bump lease expiration time. */
|
---|
| 593 | send_ACK(&packet, lease->lease_nip);
|
---|
| 594 | break;
|
---|
| 595 | }
|
---|
[3232] | 596 | /* No lease for this MAC, or lease IP != requested IP */
|
---|
| 597 |
|
---|
| 598 | if (server_id_opt /* client is in SELECTING state */
|
---|
| 599 | || requested_ip_opt /* client is in INIT-REBOOT state */
|
---|
| 600 | ) {
|
---|
| 601 | /* "No, we don't have this IP for you" */
|
---|
[2725] | 602 | send_NAK(&packet);
|
---|
[3232] | 603 | } /* else: client is in RENEWING or REBINDING, do not answer */
|
---|
| 604 |
|
---|
[821] | 605 | break;
|
---|
[2725] | 606 |
|
---|
[821] | 607 | case DHCPDECLINE:
|
---|
[2725] | 608 | /* RFC 2131:
|
---|
| 609 | * "If the server receives a DHCPDECLINE message,
|
---|
| 610 | * the client has discovered through some other means
|
---|
| 611 | * that the suggested network address is already
|
---|
| 612 | * in use. The server MUST mark the network address
|
---|
| 613 | * as not available and SHOULD notify the local
|
---|
| 614 | * sysadmin of a possible configuration problem."
|
---|
| 615 | *
|
---|
| 616 | * SERVER_ID must be present,
|
---|
| 617 | * REQUESTED_IP must be present,
|
---|
| 618 | * chaddr must be filled in,
|
---|
| 619 | * ciaddr must be 0 (we do not check this)
|
---|
| 620 | */
|
---|
| 621 | log1("Received DECLINE");
|
---|
| 622 | if (server_id_opt
|
---|
[3232] | 623 | && requested_ip_opt
|
---|
[2725] | 624 | && lease /* chaddr matches this lease */
|
---|
| 625 | && requested_nip == lease->lease_nip
|
---|
| 626 | ) {
|
---|
| 627 | memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
|
---|
| 628 | lease->expires = time(NULL) + server_config.decline_time;
|
---|
[821] | 629 | }
|
---|
| 630 | break;
|
---|
[2725] | 631 |
|
---|
[821] | 632 | case DHCPRELEASE:
|
---|
[2725] | 633 | /* "Upon receipt of a DHCPRELEASE message, the server
|
---|
| 634 | * marks the network address as not allocated."
|
---|
| 635 | *
|
---|
| 636 | * SERVER_ID must be present,
|
---|
| 637 | * REQUESTED_IP must not be present (we do not check this),
|
---|
| 638 | * chaddr must be filled in,
|
---|
| 639 | * ciaddr must be filled in
|
---|
| 640 | */
|
---|
| 641 | log1("Received RELEASE");
|
---|
| 642 | if (server_id_opt
|
---|
| 643 | && lease /* chaddr matches this lease */
|
---|
| 644 | && packet.ciaddr == lease->lease_nip
|
---|
| 645 | ) {
|
---|
| 646 | lease->expires = time(NULL);
|
---|
| 647 | }
|
---|
[821] | 648 | break;
|
---|
[2725] | 649 |
|
---|
[821] | 650 | case DHCPINFORM:
|
---|
[2725] | 651 | log1("Received INFORM");
|
---|
[821] | 652 | send_inform(&packet);
|
---|
| 653 | break;
|
---|
| 654 | }
|
---|
| 655 | }
|
---|
[1765] | 656 | ret0:
|
---|
| 657 | retval = 0;
|
---|
| 658 | ret:
|
---|
| 659 | /*if (server_config.pidfile) - server_config.pidfile is never NULL */
|
---|
| 660 | remove_pidfile(server_config.pidfile);
|
---|
| 661 | return retval;
|
---|
[821] | 662 | }
|
---|