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dnsmasq/src/rfc2131.c
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/* dnsmasq is Copyright (c) 2000-2007 Simon Kelley
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; version 2 dated June, 1991.
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.
*/
#include "dnsmasq.h"
#define BOOTREQUEST 1
#define BOOTREPLY 2
#define DHCP_COOKIE 0x63825363
/* The Linux in-kernel DHCP client silently ignores any packet
smaller than this. Sigh........... */
#define MIN_PACKETSZ 300
#define OPTION_PAD 0
#define OPTION_NETMASK 1
#define OPTION_ROUTER 3
#define OPTION_DNSSERVER 6
#define OPTION_HOSTNAME 12
#define OPTION_DOMAINNAME 15
#define OPTION_BROADCAST 28
#define OPTION_VENDOR_CLASS_OPT 43
#define OPTION_REQUESTED_IP 50
#define OPTION_LEASE_TIME 51
#define OPTION_OVERLOAD 52
#define OPTION_MESSAGE_TYPE 53
#define OPTION_SERVER_IDENTIFIER 54
#define OPTION_REQUESTED_OPTIONS 55
#define OPTION_MESSAGE 56
#define OPTION_MAXMESSAGE 57
#define OPTION_T1 58
#define OPTION_T2 59
#define OPTION_VENDOR_ID 60
#define OPTION_CLIENT_ID 61
#define OPTION_SNAME 66
#define OPTION_FILENAME 67
#define OPTION_USER_CLASS 77
#define OPTION_CLIENT_FQDN 81
#define OPTION_AGENT_ID 82
#define OPTION_SUBNET_SELECT 118
#define OPTION_END 255
#define SUBOPT_SUBNET_SELECT 5 /* RFC 3527 */
#define DHCPDISCOVER 1
#define DHCPOFFER 2
#define DHCPREQUEST 3
#define DHCPDECLINE 4
#define DHCPACK 5
#define DHCPNAK 6
#define DHCPRELEASE 7
#define DHCPINFORM 8
#define have_config(config, mask) ((config) && ((config)->flags & (mask)))
#define option_len(opt) ((int)(((unsigned char *)(opt))[1]))
#define option_ptr(opt) ((void *)&(((unsigned char *)(opt))[2]))
static unsigned int calc_time(struct dhcp_context *context, struct dhcp_config *config,
struct dhcp_lease *lease, unsigned char *opt, time_t now);
static void option_put(struct dhcp_packet *mess, unsigned char *end, int opt, int len, unsigned int val);
static void option_put_string(struct dhcp_packet *mess, unsigned char *end,
int opt, char *string, int null_term);
static struct in_addr option_addr(unsigned char *opt);
static unsigned int option_uint(unsigned char *opt, int size);
static void log_packet(struct daemon *daemon, char *type, void *addr,
unsigned char *ext_mac, int mac_len, char *interface, char *string);
static unsigned char *option_find(struct dhcp_packet *mess, size_t size, int opt_type, int minsize);
static unsigned char *option_find1(unsigned char *p, unsigned char *end, int opt, int minsize);
static size_t dhcp_packet_size(struct dhcp_packet *mess);
static void clear_packet(struct dhcp_packet *mess, unsigned char *end);
static void do_options(struct dhcp_context *context,
struct dhcp_packet *mess,
unsigned char *real_end,
unsigned char *req_options,
struct daemon *daemon,
char *hostname,
struct dhcp_netid *netid,
struct in_addr subnet_addr,
unsigned char fqdn_flags,
int null_term,
unsigned char *agent_id);
/* find a good value to use as MAC address for logging and address-allocation hashing.
This is normally just the chaddr field from the DHCP packet,
but eg Firewire will have hlen == 0 and use the client-id instead.
This could be anything, but will normally be EUI64 for Firewire.
We assume that if the first byte of the client-id equals the htype byte
then the client-id is using the usual encoding and use the rest of the
client-id: if not we can use the whole client-id. This should give
sane MAC address logs. */
static unsigned char *extended_hwaddr(int hwtype, int hwlen, unsigned char *hwaddr,
int clid_len, unsigned char *clid, int *len_out)
{
if (hwlen == 0 && clid && clid_len > 3)
{
if ((clid[0] == ARPHRD_EUI64 && hwtype == ARPHRD_IEEE1394) || clid[0] == hwtype)
{
*len_out = clid_len - 1 ;
return clid + 1;
}
else
{
*len_out = clid_len;
return clid;
}
}
*len_out = hwlen;
return hwaddr;
}
size_t dhcp_reply(struct daemon *daemon, struct dhcp_context *context, char *iface_name,
size_t sz, time_t now, int unicast_dest)
{
unsigned char *opt, *clid = NULL;
struct dhcp_lease *ltmp, *lease = NULL;
struct dhcp_vendor *vendor;
struct dhcp_opt *dopt;
struct dhcp_mac *mac;
struct dhcp_netid_list *id_list;
int clid_len = 0, ignore = 0, do_classes = 0, selecting = 0;
struct dhcp_packet *mess = daemon->dhcp_packet.iov_base;
unsigned char *end = (unsigned char *)(mess + 1);
char *hostname = NULL, *offer_hostname = NULL, *client_hostname = NULL;
int hostname_auth = 0, borken_opt = 0;
unsigned char *req_options = NULL;
char *message = NULL;
unsigned int time;
struct dhcp_config *config;
struct dhcp_netid *netid = NULL;
struct in_addr subnet_addr, fallback;
unsigned short fuzz = 0;
unsigned int mess_type = 0;
unsigned char fqdn_flags = 0;
unsigned char *agent_id = NULL;
unsigned char *emac = NULL;
int emac_len;
subnet_addr.s_addr = 0;
if (mess->op != BOOTREQUEST || mess->hlen > DHCP_CHADDR_MAX)
return 0;
if (mess->htype == 0 && mess->hlen != 0)
return 0;
/* check for DHCP rather than BOOTP */
if ((opt = option_find(mess, sz, OPTION_MESSAGE_TYPE, 1)))
{
mess_type = option_uint(opt, 1);
/* only insist on a cookie for DHCP. */
if (*((u32 *)&mess->options) != htonl(DHCP_COOKIE))
return 0;
/* two things to note here: expand_buf may move the packet,
so reassign mess from daemon->packet. Also, the size
sent includes the IP and UDP headers, hence the magic "-28" */
if ((opt = option_find(mess, sz, OPTION_MAXMESSAGE, 2)))
{
size_t size = (size_t)option_uint(opt, 2) - 28;
if (size > DHCP_PACKET_MAX)
size = DHCP_PACKET_MAX;
else if (size < sizeof(struct dhcp_packet))
size = sizeof(struct dhcp_packet);
if (expand_buf(&daemon->dhcp_packet, size))
{
mess = daemon->dhcp_packet.iov_base;
end = ((unsigned char *)mess) + size;
}
}
/* Some buggy clients set ciaddr when they shouldn't, so clear that here since
it can affect the context-determination code. */
if ((option_find(mess, sz, OPTION_REQUESTED_IP, INADDRSZ) || mess_type == DHCPDISCOVER))
mess->ciaddr.s_addr = 0;
if ((opt = option_find(mess, sz, OPTION_AGENT_ID, 1)))
{
/* Any agent-id needs to be copied back out, verbatim, as the last option
in the packet. Here, we shift it to the very end of the buffer, if it doesn't
get overwritten, then it will be shuffled back at the end of processing.
Note that the incoming options must not be overwritten here, so there has to
be enough free space at the end of the packet to copy the option. */
unsigned int total = option_len(opt) + 2;
unsigned char *last_opt = option_find(mess, sz, OPTION_END, 0);
if (last_opt && last_opt < end - total)
{
agent_id = end - total;
memcpy(agent_id, opt, total);
}
/* look for RFC3527 Link selection sub-option */
if ((opt = option_find1(option_ptr(opt), option_ptr(opt) + option_len(opt), SUBOPT_SUBNET_SELECT, INADDRSZ)))
subnet_addr = option_addr(opt);
}
/* Check for RFC3011 subnet selector - only if RFC3527 one not present */
if (subnet_addr.s_addr == 0 && (opt = option_find(mess, sz, OPTION_SUBNET_SELECT, INADDRSZ)))
subnet_addr = option_addr(opt);
/* If there is no client identifier option, use the hardware address */
if ((opt = option_find(mess, sz, OPTION_CLIENT_ID, 1)))
{
clid_len = option_len(opt);
clid = option_ptr(opt);
}
/* do we have a lease in store? */
lease = lease_find_by_client(mess->chaddr, mess->hlen, mess->htype, clid, clid_len);
/* If this request is missing a clid, but we've seen one before,
use it again for option matching etc. */
if (lease && !clid && lease->clid)
{
clid_len = lease->clid_len;
clid = lease->clid;
}
/* find mac to use for logging and hashing */
emac = extended_hwaddr(mess->htype, mess->hlen, mess->chaddr, clid_len, clid, &emac_len);
}
for (mac = daemon->dhcp_macs; mac; mac = mac->next)
if (mac->hwaddr_len == mess->hlen &&
(mac->hwaddr_type == mess->htype || mac->hwaddr_type == 0) &&
memcmp_masked(mac->hwaddr, mess->chaddr, mess->hlen, mac->mask))
{
mac->netid.next = netid;
netid = &mac->netid;
}
/* Determine network for this packet. Our caller will have already linked all the
contexts which match the addresses of the receiving interface but if the
machine has an address already, or came via a relay, or we have a subnet selector,
we search again. If we don't have have a giaddr or explicit subnet selector,
use the ciaddr. This is necessary because a machine which got a lease via a
relay won't use the relay to renew. If matching a ciaddr fails but we have a context
from the physical network, continue using that to allow correct DHCPNAK generation later. */
if (mess->giaddr.s_addr || subnet_addr.s_addr || mess->ciaddr.s_addr)
{
struct dhcp_context *context_tmp, *context_new = NULL;
struct in_addr addr;
int force = 0;
if (subnet_addr.s_addr)
{
addr = subnet_addr;
force = 1;
}
else if (mess->giaddr.s_addr)
{
addr = mess->giaddr;
force = 1;
}
else
{
/* If ciaddr is in the hardware derived set of contexts, leave that unchanged */
addr = mess->ciaddr;
for (context_tmp = context; context_tmp; context_tmp = context_tmp->current)
if (context_tmp->netmask.s_addr &&
is_same_net(addr, context_tmp->start, context_tmp->netmask) &&
is_same_net(addr, context_tmp->end, context_tmp->netmask))
{
context_new = context;
break;
}
}
if (!context_new)
for (context_tmp = daemon->dhcp; context_tmp; context_tmp = context_tmp->next)
if (context_tmp->netmask.s_addr &&
is_same_net(addr, context_tmp->start, context_tmp->netmask) &&
is_same_net(addr, context_tmp->end, context_tmp->netmask))
{
context_tmp->current = context_new;
context_new = context_tmp;
}
if (context_new || force)
context = context_new;
}
if (!context)
{
syslog(LOG_WARNING, _("no address range available for DHCP request %s %s"),
subnet_addr.s_addr ? _("with subnet selector") : _("via"),
subnet_addr.s_addr ? inet_ntoa(subnet_addr) : (mess->giaddr.s_addr ? inet_ntoa(mess->giaddr) : iface_name));
return 0;
}
/* keep _a_ local address available. */
fallback = context->local;
mess->op = BOOTREPLY;
config = find_config(daemon->dhcp_conf, context, clid, clid_len,
mess->chaddr, mess->hlen, mess->htype, NULL);
if (mess_type == 0)
{
/* BOOTP request */
struct dhcp_netid id;
struct in_addr *logaddr = NULL;
/* must have a MAC addr for bootp */
if (mess->htype == 0 || mess->hlen == 0)
return 0;
if (have_config(config, CONFIG_DISABLE))
message = _("disabled");
end = mess->options + 64; /* BOOTP vend area is only 64 bytes */
if (have_config(config, CONFIG_NAME))
hostname = config->hostname;
if (have_config(config, CONFIG_NETID))
{
config->netid.next = netid;
netid = &config->netid;
}
/* Match incoming filename field as a netid. */
if (mess->file[0])
{
memcpy(daemon->dhcp_buff2, mess->file, sizeof(mess->file));
daemon->dhcp_buff2[sizeof(mess->file) + 1] = 0; /* ensure zero term. */
id.net = (char *)daemon->dhcp_buff2;
id.next = netid;
netid = &id;
}
for (id_list = daemon->dhcp_ignore; id_list; id_list = id_list->next)
if (match_netid(id_list->list, netid, 0))
message = _("disabled");
if (!message)
{
if (have_config(config, CONFIG_ADDR))
{
logaddr = &config->addr;
mess->yiaddr = config->addr;
if ((lease = lease_find_by_addr(config->addr)) &&
(lease->hwaddr_len != mess->hlen ||
lease->hwaddr_type != mess->htype ||
memcmp(lease->hwaddr, mess->chaddr, lease->hwaddr_len) != 0))
message = _("address in use");
}
else if (!(daemon->options & OPT_BOOTP_DYNAMIC))
message = _("no address configured");
else
{
if (!(lease = lease_find_by_client(mess->chaddr, mess->hlen, mess->htype, NULL, 0)) ||
!address_available(context, lease->addr))
{
if (lease)
{
/* lease exists, wrong network. */
lease_prune(lease, now);
lease = NULL;
}
if (!address_allocate(context, daemon, &mess->yiaddr, mess->chaddr, mess->hlen, netid, now))
message = _("no address available");
}
else
mess->yiaddr = lease->addr;
}
if (!message &&
!lease &&
(!(lease = lease_allocate(mess->yiaddr))))
message = _("no leases left");
if (!message && !(context = narrow_context(context, mess->yiaddr)))
message = _("wrong network");
if (!message)
{
logaddr = &mess->yiaddr;
if (context->netid.net)
{
context->netid.next = netid;
netid = &context->netid;
}
lease_set_hwaddr(lease, mess->chaddr, NULL, mess->hlen, mess->htype, 0);
if (hostname)
lease_set_hostname(lease, hostname, daemon->domain_suffix, 1);
lease_set_expires(lease, 0xffffffff, now); /* infinite lease */
clear_packet(mess, end);
do_options(context, mess, end, NULL, daemon,
hostname, netid, subnet_addr, 0, 0, NULL);
}
}
log_packet(daemon, NULL, logaddr, mess->chaddr, mess->hlen, iface_name, message);
return message ? dhcp_packet_size(mess) : 0;
}
if ((opt = option_find(mess, sz, OPTION_CLIENT_FQDN, 4)))
{
/* http://tools.ietf.org/wg/dhc/draft-ietf-dhc-fqdn-option/draft-ietf-dhc-fqdn-option-10.txt */
int len = option_len(opt);
char *pq = daemon->dhcp_buff;
unsigned char *pp, *op = option_ptr(opt);
fqdn_flags = *op;
len -= 3;
op += 3;
pp = op;
/* Always force update, since the client has no way to do it itself. */
if (!(fqdn_flags & 0x01))
fqdn_flags |= 0x02;
fqdn_flags &= ~0x08;
fqdn_flags |= 0x01;
if (fqdn_flags & 0x04)
while (*op != 0 && ((op + (*op) + 1) - pp) < len)
{
memcpy(pq, op+1, *op);
pq += *op;
op += (*op)+1;
*(pq++) = '.';
}
else
{
memcpy(pq, op, len);
if (len > 0 && op[len-1] == 0)
borken_opt = 1;
pq += len + 1;
}
if (pq != daemon->dhcp_buff)
pq--;
*pq = 0;
if (canonicalise(daemon->dhcp_buff))
offer_hostname = client_hostname = daemon->dhcp_buff;
}
else if ((opt = option_find(mess, sz, OPTION_HOSTNAME, 1)))
{
int len = option_len(opt);
memcpy(daemon->dhcp_buff, option_ptr(opt), len);
/* Microsoft clients are broken, and need zero-terminated strings
in options. We detect this state here, and do the same in
any options we send */
if (len > 0 && daemon->dhcp_buff[len-1] == 0)
borken_opt = 1;
else
daemon->dhcp_buff[len] = 0;
if (canonicalise(daemon->dhcp_buff))
client_hostname = daemon->dhcp_buff;
}
if (have_config(config, CONFIG_NAME))
{
hostname = config->hostname;
hostname_auth = 1;
/* be careful not to send an OFFER with a hostname not matching the DISCOVER. */
if (fqdn_flags != 0 || !client_hostname || hostname_isequal(hostname, client_hostname))
offer_hostname = hostname;
}
else if (client_hostname && (hostname = strip_hostname(daemon, client_hostname)) && !config)
{
/* Search again now we have a hostname.
Only accept configs without CLID and HWADDR here, (they won't match)
to avoid impersonation by name. */
struct dhcp_config *new = find_config(daemon->dhcp_conf, context, NULL, 0,
mess->chaddr, mess->hlen,
mess->htype, hostname);
if (!have_config(new, CONFIG_CLID) && !have_config(new, CONFIG_HWADDR))
config = new;
}
if (have_config(config, CONFIG_NETID))
{
config->netid.next = netid;
netid = &config->netid;
}
/* user-class options are, according to RFC3004, supposed to contain
a set of counted strings. Here we check that this is so (by seeing
if the counts are consistent with the overall option length) and if
so zero the counts so that we don't get spurious matches between
the vendor string and the counts. If the lengths don't add up, we
assume that the option is a single string and non RFC3004 compliant
and just do the substring match. dhclient provides these broken options.
The code, later, which sends user-class data to the lease-change script
relies on the transformation done here.
*/
if ((opt = option_find(mess, sz, OPTION_USER_CLASS, 1)))
{
unsigned char *ucp = option_ptr(opt);
int tmp, j;
for (j = 0; j < option_len(opt); j += ucp[j] + 1);
if (j == option_len(opt))
for (j = 0; j < option_len(opt); j = tmp)
{
tmp = j + ucp[j] + 1;
ucp[j] = 0;
}
}
for (vendor = daemon->dhcp_vendors; vendor; vendor = vendor->next)
if ((opt = option_find(mess, sz, vendor->is_vendor ? OPTION_VENDOR_ID : OPTION_USER_CLASS, 1)))
{
int i;
for (i = 0; i <= (option_len(opt) - vendor->len); i++)
if (memcmp(vendor->data, option_ptr(opt)+i, vendor->len) == 0)
{
vendor->netid.next = netid;
netid = &vendor->netid;
break;
}
}
/* mark vendor-encapsulated options which match the client-supplied vendor class */
opt = option_find(mess, sz, OPTION_VENDOR_ID, 1);
for (dopt = daemon->vendor_opts; dopt; dopt = dopt->next)
{
int i, len = 0;
dopt->flags &= ~DHOPT_VENDOR_MATCH;
if (opt)
{
if (dopt->vendor_class)
len = strlen((char *)dopt->vendor_class);
for (i = 0; i <= (option_len(opt) - len); i++)
if (len == 0 || memcmp(dopt->vendor_class, option_ptr(opt)+i, len) == 0)
{
dopt->flags |= DHOPT_VENDOR_MATCH;
break;
}
}
}
/* if all the netids in the ignore list are present, ignore this client */
for (id_list = daemon->dhcp_ignore; id_list; id_list = id_list->next)
if (match_netid(id_list->list, netid, 0))
ignore = 1;
/* Can have setting to ignore the client ID for a particular MAC address or hostname */
if (have_config(config, CONFIG_NOCLID))
clid = NULL;
if ((opt = option_find(mess, sz, OPTION_REQUESTED_OPTIONS, 0)))
{
req_options = (unsigned char *)daemon->dhcp_buff2;
memcpy(req_options, option_ptr(opt), option_len(opt));
req_options[option_len(opt)] = OPTION_END;
}
switch (mess_type)
{
case DHCPDECLINE:
if (!(opt = option_find(mess, sz, OPTION_SERVER_IDENTIFIER, INADDRSZ)) ||
(context->local.s_addr != option_addr(opt).s_addr))
return 0;
/* sanitise any message. Paranoid? Moi? */
if ((opt = option_find(mess, sz, OPTION_MESSAGE, 1)))
{
char *p = option_ptr(opt), *q = daemon->dhcp_buff;
int i;
for (i = option_len(opt); i > 0; i--)
{
char c = *p++;
if (isprint(c))
*q++ = c;
}
*q++ = 0; /* add terminator */
}
if (!(opt = option_find(mess, sz, OPTION_REQUESTED_IP, INADDRSZ)))
return 0;
log_packet(daemon, "DECLINE", option_ptr(opt), emac, emac_len, iface_name, daemon->dhcp_buff);
if (lease && lease->addr.s_addr == option_addr(opt).s_addr)
lease_prune(lease, now);
if (have_config(config, CONFIG_ADDR) &&
config->addr.s_addr == option_addr(opt).s_addr)
{
prettyprint_time(daemon->dhcp_buff, DECLINE_BACKOFF);
syslog(LOG_WARNING, _("disabling DHCP static address %s for %s"),
inet_ntoa(config->addr), daemon->dhcp_buff);
config->flags |= CONFIG_DECLINED;
config->decline_time = now;
}
else
/* make sure this host gets a different address next time. */
for (; context; context = context->current)
context->addr_epoch++;
return 0;
case DHCPRELEASE:
if (!(context = narrow_context(context, mess->ciaddr)) ||
!(opt = option_find(mess, sz, OPTION_SERVER_IDENTIFIER, INADDRSZ)) ||
(context->local.s_addr != option_addr(opt).s_addr))
return 0;
if (lease && lease->addr.s_addr == mess->ciaddr.s_addr)
lease_prune(lease, now);
else
message = _("unknown lease");
log_packet(daemon, "RELEASE", &mess->ciaddr, emac, emac_len, iface_name, message);
return 0;
case DHCPDISCOVER:
if (ignore || have_config(config, CONFIG_DISABLE))
{
message = _("ignored");
opt = NULL;
}
else
{
struct in_addr addr, conf;
if ((opt = option_find(mess, sz, OPTION_REQUESTED_IP, INADDRSZ)))
addr = option_addr(opt);
conf.s_addr = 0;
if (have_config(config, CONFIG_ADDR))
{
char *addrs = inet_ntoa(config->addr);
if ((ltmp = lease_find_by_addr(config->addr)) && ltmp != lease)
{
int len;
unsigned char *mac = extended_hwaddr(ltmp->hwaddr_type, ltmp->hwaddr_len,
ltmp->hwaddr, ltmp->clid_len, ltmp->clid, &len);
syslog(LOG_WARNING, _("not using configured address %s because it is leased to %s"),
addrs, print_mac(daemon, mac, len));
}
else
{
struct dhcp_context *tmp;
for (tmp = context; tmp; tmp = tmp->current)
if (context->router.s_addr == config->addr.s_addr)
break;
if (tmp)
syslog(LOG_WARNING, _("not using configured address %s because it is in use by the server or relay"), addrs);
else if (have_config(config, CONFIG_DECLINED) &&
difftime(now, config->decline_time) < (float)DECLINE_BACKOFF)
syslog(LOG_WARNING, _("not using configured address %s because it was previously declined"), addrs);
else
conf = config->addr;
}
}
if (conf.s_addr)
mess->yiaddr = conf;
else if (lease && address_available(context, lease->addr))
mess->yiaddr = lease->addr;
else if (opt && address_available(context, addr) && !lease_find_by_addr(addr) &&
!config_find_by_address(daemon->dhcp_conf, addr))
mess->yiaddr = addr;
else if (!address_allocate(context, daemon, &mess->yiaddr, mess->chaddr, mess->hlen, netid, now))
message = _("no address available");
}
log_packet(daemon, "DISCOVER", opt ? option_ptr(opt) : NULL, emac, emac_len, iface_name, message);
if (message || !(context = narrow_context(context, mess->yiaddr)))
return 0;
log_packet(daemon, "OFFER" , &mess->yiaddr, emac, emac_len, iface_name, NULL);
if (context->netid.net)
{
context->netid.next = netid;
netid = &context->netid;
}
time = calc_time(context, config, lease, option_find(mess, sz, OPTION_LEASE_TIME, 4), now);
clear_packet(mess, end);
option_put(mess, end, OPTION_MESSAGE_TYPE, 1, DHCPOFFER);
option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(context->local.s_addr));
option_put(mess, end, OPTION_LEASE_TIME, 4, time);
/* T1 and T2 are required in DHCPOFFER by HP's wacky Jetdirect client. */
if (time != 0xffffffff)
{
option_put(mess, end, OPTION_T1, 4, (time/2));
option_put(mess, end, OPTION_T2, 4, (time*7)/8);
}
do_options(context, mess, end, req_options, daemon, offer_hostname,
netid, subnet_addr, fqdn_flags, borken_opt, agent_id);
return dhcp_packet_size(mess);
case DHCPREQUEST:
if (ignore || have_config(config, CONFIG_DISABLE))
return 0;
if ((opt = option_find(mess, sz, OPTION_REQUESTED_IP, INADDRSZ)))
{
/* SELECTING or INIT_REBOOT */
mess->yiaddr = option_addr(opt);
/* send vendor and user class info for new or recreated lease */
do_classes = 1;
if ((opt = option_find(mess, sz, OPTION_SERVER_IDENTIFIER, INADDRSZ)))
{
/* SELECTING */
selecting = 1;
for (; context; context = context->current)
if (context->local.s_addr == option_addr(opt).s_addr)
break;
if (!context)
return 0;
/* If a lease exists for this host and another address, squash it. */
if (lease && lease->addr.s_addr != mess->yiaddr.s_addr)
{
lease_prune(lease, now);
lease = NULL;
}
}
else
{
/* INIT-REBOOT */
if (!lease && !(daemon->options & OPT_AUTHORITATIVE))
return 0;
if (lease && lease->addr.s_addr != mess->yiaddr.s_addr)
message = _("wrong address");
}
}
else
{
/* RENEWING or REBINDING */
/* Check existing lease for this address.
We allow it to be missing if dhcp-authoritative mode
as long as we can allocate the lease now - checked below.
This makes for a smooth recovery from a lost lease DB */
if ((lease && mess->ciaddr.s_addr != lease->addr.s_addr) ||
(!lease && !(daemon->options & OPT_AUTHORITATIVE)))
{
message = _("lease not found");
/* ensure we broadcast NAK */
unicast_dest = 0;
}
/* desynchronise renewals */
fuzz = rand16();
mess->yiaddr = mess->ciaddr;
}
log_packet(daemon, "REQUEST", &mess->yiaddr, emac, emac_len, iface_name, NULL);
if (!message)
{
struct dhcp_config *addr_config;
struct dhcp_context *tmp = NULL;
if (have_config(config, CONFIG_ADDR))
for (tmp = context; tmp; tmp = tmp->current)
if (context->router.s_addr == config->addr.s_addr)
break;
if (!(context = narrow_context(context, mess->yiaddr)))
{
/* If a machine moves networks whilst it has a lease, we catch that here. */
message = _("wrong network");
/* ensure we broadcast NAK */
unicast_dest = 0;
}
/* Check for renewal of a lease which is outside the allowed range. */
else if (!address_available(context, mess->yiaddr) &&
(!have_config(config, CONFIG_ADDR) || config->addr.s_addr != mess->yiaddr.s_addr))
message = _("address not available");
/* Check if a new static address has been configured. Be very sure that
when the client does DISCOVER, it will get the static address, otherwise
an endless protocol loop will ensue. */
else if (!tmp && !selecting &&
have_config(config, CONFIG_ADDR) &&
(!have_config(config, CONFIG_DECLINED) ||
difftime(now, config->decline_time) > (float)DECLINE_BACKOFF) &&
config->addr.s_addr != mess->yiaddr.s_addr &&
(!(ltmp = lease_find_by_addr(config->addr)) || ltmp == lease))
message = _("static lease available");
/* Check to see if the address is reserved as a static address for another host */
else if ((addr_config = config_find_by_address(daemon->dhcp_conf, mess->yiaddr)) && addr_config != config)
message = _("address reserved");
else if ((ltmp = lease_find_by_addr(mess->yiaddr)) && ltmp != lease)
message = _("address in use");
else if (!clid && mess->hlen == 0)
message = _("no unique-id");
else if (!lease)
{
if ((lease = lease_allocate(mess->yiaddr)))
do_classes = 1;
else
message = _("no leases left");
}
}
if (message)
{
log_packet(daemon, "NAK", &mess->yiaddr, emac, emac_len, iface_name, message);
mess->yiaddr.s_addr = 0;
clear_packet(mess, end);
option_put(mess, end, OPTION_MESSAGE_TYPE, 1, DHCPNAK);
option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ,
ntohl(context ? context->local.s_addr : fallback.s_addr));
option_put_string(mess, end, OPTION_MESSAGE, message, borken_opt);
/* This fixes a problem with the DHCP spec, broadcasting a NAK to a host on
a distant subnet which unicast a REQ to us won't work. */
if (!unicast_dest || mess->giaddr.s_addr != 0 ||
mess->ciaddr.s_addr == 0 || is_same_net(context->local, mess->ciaddr, context->netmask))
{
mess->flags |= htons(0x8000); /* broadcast */
mess->ciaddr.s_addr = 0;
}
}
else
{
if (do_classes)
{
lease->changed = 1;
/* copy user-class and vendor class into new lease, for the script */
if ((opt = option_find(mess, sz, OPTION_USER_CLASS, 1)))
{
int len = option_len(opt);
unsigned char *ucp = option_ptr(opt);
/* If the user-class option started as counted strings, the first byte will be zero. */
if (len != 0 && ucp[0] == 0)
ucp++, len--;
if (lease->userclass)
free(lease->userclass);
if ((lease->userclass = malloc(len+1)))
{
memcpy(lease->userclass, ucp, len);
lease->userclass[len] = 0;
lease->userclass_len = len+1;
}
}
if ((opt = option_find(mess, sz, OPTION_VENDOR_ID, 1)))
{
int len = option_len(opt);
unsigned char *ucp = option_ptr(opt);
if (lease->vendorclass)
free(lease->vendorclass);
if ((lease->vendorclass = malloc(len+1)))
{
memcpy(lease->vendorclass, ucp, len);
lease->vendorclass[len] = 0;
lease->vendorclass_len = len+1;
}
}
}
if (!hostname_auth && (client_hostname = host_from_dns(daemon, mess->yiaddr)))
{
hostname = client_hostname;
hostname_auth = 1;
}
if (context->netid.net)
{
context->netid.next = netid;
netid = &context->netid;
}
time = calc_time(context, config, NULL, option_find(mess, sz, OPTION_LEASE_TIME, 4), now);
lease_set_hwaddr(lease, mess->chaddr, clid, mess->hlen, mess->htype, clid_len);
/* if all the netids in the ignore_name list are present, ignore client-supplied name */
if (!hostname_auth)
{
for (id_list = daemon->dhcp_ignore_names; id_list; id_list = id_list->next)
if ((!id_list->list) || match_netid(id_list->list, netid, 0))
break;
if (id_list)
hostname = NULL;
}
if (hostname)
lease_set_hostname(lease, hostname, daemon->domain_suffix, hostname_auth);
lease_set_expires(lease, time, now);
log_packet(daemon, "ACK", &mess->yiaddr, emac, emac_len, iface_name, hostname);
clear_packet(mess, end);
option_put(mess, end, OPTION_MESSAGE_TYPE, 1, DHCPACK);
option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(context->local.s_addr));
option_put(mess, end, OPTION_LEASE_TIME, 4, time);
if (time != 0xffffffff)
{
while (fuzz > (time/16))
fuzz = fuzz/2;
option_put(mess, end, OPTION_T1, 4, (time/2) - fuzz);
option_put(mess, end, OPTION_T2, 4, ((time/8)*7) - fuzz);
}
do_options(context, mess, end, req_options, daemon, hostname,
netid, subnet_addr, fqdn_flags, borken_opt, agent_id);
}
return dhcp_packet_size(mess);
case DHCPINFORM:
if (ignore || have_config(config, CONFIG_DISABLE))
message = _("ignored");
log_packet(daemon, "INFORM", &mess->ciaddr, emac, emac_len, iface_name, message);
if (message || mess->ciaddr.s_addr == 0 ||
!(context = narrow_context(context, mess->ciaddr)))
return 0;
log_packet(daemon, "ACK", &mess->ciaddr, emac, emac_len, iface_name, hostname);
if (context->netid.net)
{
context->netid.next = netid;
netid = &context->netid;
}
clear_packet(mess, end);
option_put(mess, end, OPTION_MESSAGE_TYPE, 1, DHCPACK);
option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(context->local.s_addr));
if (!hostname)
hostname = host_from_dns(daemon, mess->yiaddr);
do_options(context, mess, end, req_options, daemon, hostname,
netid, subnet_addr, fqdn_flags, borken_opt, agent_id);
return dhcp_packet_size(mess);
}
return 0;
}
static unsigned int calc_time(struct dhcp_context *context, struct dhcp_config *config,
struct dhcp_lease *lease, unsigned char *opt, time_t now)
{
unsigned int time = have_config(config, CONFIG_TIME) ? config->lease_time : context->lease_time;
if (opt)
{
unsigned int req_time = option_uint(opt, 4);
if (req_time < 120 )
req_time = 120; /* sanity */
if (time == 0xffffffff || (req_time != 0xffffffff && req_time < time))
time = req_time;
}
else if (lease && lease->expires != 0 && difftime(lease->expires, now) > 0.0)
{
unsigned int lease_time = (unsigned int)difftime(lease->expires, now);
/* put a floor on lease-remaining time. */
if (lease_time < 360 )
lease_time = 360;
if (time > lease_time)
time = lease_time;
}
return time;
}
static void log_packet(struct daemon *daemon, char *type, void *addr,
unsigned char *ext_mac, int mac_len, char *interface, char *string)
{
struct in_addr a;
/* addr may be misaligned */
if (addr)
memcpy(&a, addr, sizeof(a));
syslog(LOG_INFO, "%s%s(%s) %s%s%s %s",
type ? "DHCP" : "BOOTP",
type ? type : "",
interface,
addr ? inet_ntoa(a) : "",
addr ? " " : "",
print_mac(daemon, ext_mac, mac_len),
string ? string : "");
}
static unsigned char *option_find1(unsigned char *p, unsigned char *end, int opt, int minsize)
{
while (*p != OPTION_END)
{
if (p >= end)
return NULL; /* malformed packet */
else if (*p == OPTION_PAD)
p++;
else
{
int opt_len;
if (p >= end - 2)
return NULL; /* malformed packet */
opt_len = option_len(p);
if (p >= end - (2 + opt_len))
return NULL; /* malformed packet */
if (*p == opt && opt_len >= minsize)
return p;
p += opt_len + 2;
}
}
return opt == OPTION_END ? p : NULL;
}
static unsigned char *option_find(struct dhcp_packet *mess, size_t size, int opt_type, int minsize)
{
unsigned char *ret, *overload;
/* skip over DHCP cookie; */
if ((ret = option_find1(&mess->options[0] + sizeof(u32), ((unsigned char *)mess) + size, opt_type, minsize)))
return ret;
/* look for overload option. */
if (!(overload = option_find1(&mess->options[0] + sizeof(u32), ((unsigned char *)mess) + size, OPTION_OVERLOAD, 1)))
return NULL;
/* Can we look in filename area ? */
if ((overload[2] & 1) &&
(ret = option_find1(&mess->file[0], &mess->file[128], opt_type, minsize)))
return ret;
/* finally try sname area */
if ((overload[2] & 2) &&
(ret = option_find1(&mess->sname[0], &mess->sname[64], opt_type, minsize)))
return ret;
return NULL;
}
static struct in_addr option_addr(unsigned char *opt)
{
/* this worries about unaligned data in the option. */
/* struct in_addr is network byte order */
struct in_addr ret;
memcpy(&ret, option_ptr(opt), INADDRSZ);
return ret;
}
static unsigned int option_uint(unsigned char *opt, int size)
{
/* this worries about unaligned data and byte order */
unsigned int ret = 0;
int i;
unsigned char *p = option_ptr(opt);
for (i = 0; i < size; i++)
ret = (ret << 8) | *p++;
return ret;
}
static unsigned char *dhcp_skip_opts(unsigned char *start)
{
while (*start != 0)
start += start[1] + 2;
return start;
}
/* only for use when building packet: doesn't check for bad data. */
static unsigned char *find_overload(struct dhcp_packet *mess)
{
unsigned char *p = &mess->options[0] + sizeof(u32);
while (*p != 0)
{
if (*p == OPTION_OVERLOAD)
return p;
p += p[1] + 2;
}
return NULL;
}
static size_t dhcp_packet_size(struct dhcp_packet *mess)
{
unsigned char *p = dhcp_skip_opts(&mess->options[0] + sizeof(u32));
unsigned char *overload;
size_t ret;
/* add END options to the regions. */
if ((overload = find_overload(mess)))
{
if (option_uint(overload, 1) & 1)
*dhcp_skip_opts(mess->file) = OPTION_END;
if (option_uint(overload, 1) & 2)
*dhcp_skip_opts(mess->sname) = OPTION_END;
}
*p++ = OPTION_END;
ret = (size_t)(p - (unsigned char *)mess);
if (ret < MIN_PACKETSZ)
ret = MIN_PACKETSZ;
return ret;
}
static unsigned char *free_space(struct dhcp_packet *mess, unsigned char *end, int opt, int len)
{
unsigned char *p = dhcp_skip_opts(&mess->options[0] + sizeof(u32));
if (p + len + 3 >= end)
/* not enough space in options area, try and use overload, if poss */
{
unsigned char *overload;
if (!(overload = find_overload(mess)) &&
(mess->file[0] == 0 || mess->sname[0] == 0))
{
/* attempt to overload fname and sname areas, we've reserved space for the
overflow option previuously. */
overload = p;
*(p++) = OPTION_OVERLOAD;
*(p++) = 1;
}
p = NULL;
/* using filename field ? */
if (overload)
{
if (mess->file[0] == 0)
overload[2] |= 1;
if (overload[2] & 1)
{
p = dhcp_skip_opts(mess->file);
if (p + len + 3 >= mess->file + sizeof(mess->file))
p = NULL;
}
if (!p)
{
/* try to bring sname into play (it may be already) */
if (mess->sname[0] == 0)
overload[2] |= 2;
if (overload[2] & 2)
{
p = dhcp_skip_opts(mess->sname);
if (p + len + 3 >= mess->sname + sizeof(mess->file))
p = NULL;
}
}
}
if (!p)
syslog(LOG_WARNING, _("cannot send DHCP option %d: no space left in packet"), opt);
}
if (p)
{
*(p++) = opt;
*(p++) = len;
}
return p;
}
static void option_put(struct dhcp_packet *mess, unsigned char *end, int opt, int len, unsigned int val)
{
int i;
unsigned char *p = free_space(mess, end, opt, len);
if (p)
for (i = 0; i < len; i++)
*(p++) = val >> (8 * (len - (i + 1)));
}
static void option_put_string(struct dhcp_packet *mess, unsigned char *end, int opt,
char *string, int null_term)
{
unsigned char *p;
size_t len = strlen(string);
if (null_term && len != 255)
len++;
if ((p = free_space(mess, end, opt, len)))
memcpy(p, string, len);
}
/* return length, note this only does the data part */
static int do_opt(struct dhcp_opt *opt, unsigned char *p, struct in_addr local, int null_term)
{
int len = opt->len;
if ((opt->flags & DHOPT_STRING) && null_term && len != 255)
len++;
if (p && len != 0)
{
if (opt->flags & DHOPT_ADDR)
{
int j;
struct in_addr *a = (struct in_addr *)opt->val;
for (j = 0; j < opt->len; j+=INADDRSZ, a++)
{
/* zero means "self" (but not in vendorclass options.) */
if (a->s_addr == 0)
memcpy(p, &local, INADDRSZ);
else
memcpy(p, a, INADDRSZ);
p += INADDRSZ;
}
}
else
memcpy(p, opt->val, len);
}
return len;
}
static int in_list(unsigned char *list, int opt)
{
int i;
/* If no requested options, send everything, not nothing. */
if (!list)
return 1;
for (i = 0; list[i] != OPTION_END; i++)
if (opt == list[i])
return 1;
return 0;
}
static struct dhcp_opt *option_find2(struct dhcp_netid *netid, struct dhcp_opt *opts, int opt)
{
struct dhcp_opt *tmp;
for (tmp = opts; tmp; tmp = tmp->next)
if (tmp->opt == opt)
if (match_netid(tmp->netid, netid, 1) || match_netid(tmp->netid, netid, 0))
return tmp;
return netid ? option_find2(NULL, opts, opt) : NULL;
}
static void clear_packet(struct dhcp_packet *mess, unsigned char *end)
{
memset(mess->sname, 0, sizeof(mess->sname));
memset(mess->file, 0, sizeof(mess->file));
memset(&mess->options[0] + sizeof(u32), 0, end - (&mess->options[0] + sizeof(u32)));
mess->siaddr.s_addr = 0;
}
static void do_options(struct dhcp_context *context,
struct dhcp_packet *mess,
unsigned char *real_end,
unsigned char *req_options,
struct daemon *daemon,
char *hostname,
struct dhcp_netid *netid,
struct in_addr subnet_addr,
unsigned char fqdn_flags,
int null_term,
unsigned char *agent_id)
{
struct dhcp_opt *opt, *config_opts = daemon->dhcp_opts;
struct dhcp_boot *boot;
unsigned char *p, *end = agent_id ? agent_id : real_end;
int len;
unsigned char f0 = 0, s0 = 0;
/* decide which dhcp-boot option we're using */
for (boot = daemon->boot_config; boot; boot = boot->next)
if (match_netid(boot->netid, netid, 0))
break;
if (!boot)
/* No match, look for one without a netid */
for (boot = daemon->boot_config; boot; boot = boot->next)
if (match_netid(boot->netid, netid, 1))
break;
mess->siaddr = context->local;
/* See if we can send the boot stuff as options.
To do this we need a requested option list, BOOTP
and very old DHCP clients won't have this.
Some PXE ROMs have bugs (surprise!) and need zero-terminated
names, so we always send those. */
if (boot)
{
if (boot->sname)
{
if (req_options && in_list(req_options, OPTION_SNAME))
option_put_string(mess, end, OPTION_SNAME, boot->sname, 1);
else
strncpy((char *)mess->sname, boot->sname, sizeof(mess->sname)-1);
}
if (boot->file)
{
if (req_options && in_list(req_options, OPTION_FILENAME))
option_put_string(mess, end, OPTION_FILENAME, boot->file, 1);
else
strncpy((char *)mess->file, boot->file, sizeof(mess->file)-1);
}
if (boot->next_server.s_addr)
mess->siaddr = boot->next_server;
}
/* We don't want to do option-overload for BOOTP, so make the file and sname
fields look like they are in use, even when they aren't. This gets restored
at the end of this function. */
if (!req_options)
{
f0 = mess->file[0];
mess->file[0] = 1;
s0 = mess->sname[0];
mess->sname[0] = 1;
}
/* At this point, if mess->sname or mess->file are zeroed, they are available
for option overload, reserve space for the overload option. */
if (mess->file[0] == 0 || mess->sname[0] == 0)
end -= 3;
/* rfc3011 says this doesn't need to be in the requested options list. */
if (subnet_addr.s_addr)
option_put(mess, end, OPTION_SUBNET_SELECT, INADDRSZ, ntohl(subnet_addr.s_addr));
if (!option_find2(netid, config_opts, OPTION_NETMASK))
option_put(mess, end, OPTION_NETMASK, INADDRSZ, ntohl(context->netmask.s_addr));
/* May not have a "guessed" broadcast address if we got no packets via a relay
from this net yet (ie just unicast renewals after a restart */
if (context->broadcast.s_addr &&
!option_find2(netid, config_opts, OPTION_BROADCAST))
option_put(mess, end, OPTION_BROADCAST, INADDRSZ, ntohl(context->broadcast.s_addr));
/* Same comments as broadcast apply, and also may not be able to get a sensible
default when using subnet select. User must configure by steam in that case. */
if (context->router.s_addr &&
in_list(req_options, OPTION_ROUTER) &&
!option_find2(netid, config_opts, OPTION_ROUTER))
option_put(mess, end, OPTION_ROUTER, INADDRSZ, ntohl(context->router.s_addr));
if (in_list(req_options, OPTION_DNSSERVER) &&
!option_find2(netid, config_opts, OPTION_DNSSERVER))
option_put(mess, end, OPTION_DNSSERVER, INADDRSZ, ntohl(context->local.s_addr));
if (daemon->domain_suffix && in_list(req_options, OPTION_DOMAINNAME) &&
!option_find2(netid, config_opts, OPTION_DOMAINNAME))
option_put_string(mess, end, OPTION_DOMAINNAME, daemon->domain_suffix, null_term);
/* Note that we ignore attempts to set the hostname using
--dhcp-option=12,<name> and the fqdn using
--dhc-option=81,<name> */
if (hostname)
{
if (in_list(req_options, OPTION_HOSTNAME))
option_put_string(mess, end, OPTION_HOSTNAME, hostname, null_term);
if (fqdn_flags != 0)
{
int len = strlen(hostname) + 3;
if (fqdn_flags & 0x04)
len += 2;
else if (null_term)
len++;
if (daemon->domain_suffix)
len += strlen(daemon->domain_suffix) + 1;
if ((p = free_space(mess, end, OPTION_CLIENT_FQDN, len)))
{
*(p++) = fqdn_flags;
*(p++) = 255;
*(p++) = 255;
if (fqdn_flags & 0x04)
{
p = do_rfc1035_name(p, hostname);
if (daemon->domain_suffix)
p = do_rfc1035_name(p, daemon->domain_suffix);
*p++ = 0;
}
else
{
memcpy(p, hostname, strlen(hostname));
p += strlen(hostname);
if (daemon->domain_suffix)
{
*(p++) = '.';
memcpy(p, daemon->domain_suffix, strlen(daemon->domain_suffix));
p += strlen(daemon->domain_suffix);
}
if (null_term)
*(p++) = 0;
}
}
}
}
for (opt=config_opts; opt; opt = opt->next)
{
if (opt->opt == OPTION_HOSTNAME ||
opt->opt == OPTION_CLIENT_FQDN ||
opt->opt == OPTION_MAXMESSAGE ||
opt->opt == OPTION_VENDOR_CLASS_OPT ||
opt->opt == OPTION_OVERLOAD ||
opt->opt == OPTION_PAD ||
opt->opt == OPTION_END ||
!in_list(req_options, opt->opt) ||
opt != option_find2(netid, config_opts, opt->opt))
continue;
/* For the options we have default values on
dhc-option=<optionno> means "don't include this option"
not "include a zero-length option" */
if (opt->len == 0 &&
(opt->opt == OPTION_NETMASK ||
opt->opt == OPTION_BROADCAST ||
opt->opt == OPTION_ROUTER ||
opt->opt == OPTION_DNSSERVER))
continue;
len = do_opt(opt, NULL, context->local, null_term);
if ((p = free_space(mess, end, opt->opt, len)))
do_opt(opt, p, context->local, null_term);
}
if (in_list(req_options, OPTION_VENDOR_CLASS_OPT))
{
int enc_len = 0;
/* find size in advance */
for (opt = daemon->vendor_opts; opt; opt = opt->next)
if (opt->flags & DHOPT_VENDOR_MATCH)
{
if (!match_netid(opt->netid, netid, 1) && !match_netid(opt->netid, netid, 0))
opt->flags &= ~DHOPT_VENDOR_MATCH;
else
{
int new = enc_len + do_opt(opt, NULL, context->local, null_term) + 2;
if (new <= 255)
enc_len = new;
else
{
syslog(LOG_WARNING, _("cannot send encapsulated option %d: no space left in wrapper"), opt->opt);
opt->flags &= ~DHOPT_VENDOR_MATCH;
}
}
}
if ((p = free_space(mess, end, OPTION_VENDOR_CLASS_OPT, enc_len)))
{
for (opt = daemon->vendor_opts; opt; opt = opt->next)
if (opt->flags & DHOPT_VENDOR_MATCH)
{
len = do_opt(opt, p + 2, context->local, null_term);
*(p++) = opt->opt;
*(p++) = len;
}
}
}
/* move agent_id back down to the end of the packet */
if (agent_id)
{
p = dhcp_skip_opts(&mess->options[0] + sizeof(u32));
memmove(p, agent_id, real_end - agent_id);
p += real_end - agent_id;
memset(p, 0, real_end - p); /* in case of overlap */
}
/* restore BOOTP anti-overload hack */
if (!req_options)
{
mess->file[0] = f0;
mess->sname[0] = s0;
}
}
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