mirror of
https://github.com/pi-hole/dnsmasq.git
synced 2025-12-19 18:28:25 +00:00
import of dnsmasq-2.0.tar.gz
This commit is contained in:
Simon Kelley
273
src/dhcp.c
Normal file
273
src/dhcp.c
Normal file
@@ -0,0 +1,273 @@
|
||||
/* dnsmasq is Copyright (c) 2000-2003 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.
|
||||
*/
|
||||
|
||||
/* Author's email: simon@thekelleys.org.uk */
|
||||
|
||||
#include "dnsmasq.h"
|
||||
|
||||
void dhcp_packet(struct dhcp_context *context, char *packet,
|
||||
struct dhcp_opt *dhcp_opts, struct dhcp_config *dhcp_configs,
|
||||
time_t now, char *namebuff, char *domain_suffix,
|
||||
char *dhcp_file, char *dhcp_sname,
|
||||
struct in_addr dhcp_next_server)
|
||||
{
|
||||
struct udp_dhcp_packet *rawpacket = (struct udp_dhcp_packet *) packet;
|
||||
struct dhcp_packet *mess = (struct dhcp_packet *)&rawpacket->data;
|
||||
int sz, newlen;
|
||||
|
||||
sz = recvfrom(context->fd, &rawpacket->data,
|
||||
PACKETSZ - (sizeof(struct ip) + sizeof(struct udphdr)),
|
||||
0, NULL, 0);
|
||||
if ((unsigned int)sz > (sizeof(*mess) - sizeof(mess->options)))
|
||||
{
|
||||
lease_prune(NULL, now); /* lose any expired leases */
|
||||
newlen = dhcp_reply(context, mess, sz, now, namebuff, dhcp_opts,
|
||||
dhcp_configs, domain_suffix, dhcp_file,
|
||||
dhcp_sname, dhcp_next_server );
|
||||
lease_update_dns(0);
|
||||
|
||||
if (newlen != 0)
|
||||
{
|
||||
int broadcast = ntohs(mess->flags) & 0x8000;
|
||||
|
||||
/* newlen -ve forces broadcast */
|
||||
if (newlen < 0)
|
||||
{
|
||||
broadcast = 1;
|
||||
newlen = -newlen;
|
||||
}
|
||||
|
||||
if (mess->giaddr.s_addr || mess->ciaddr.s_addr)
|
||||
{
|
||||
/* To send to BOOTP relay or configured client, use
|
||||
the IP packet */
|
||||
|
||||
struct sockaddr_in dest;
|
||||
dest.sin_family = AF_INET;
|
||||
|
||||
if (mess->giaddr.s_addr)
|
||||
{
|
||||
dest.sin_port = htons(DHCP_SERVER_PORT);
|
||||
dest.sin_addr = mess->giaddr;
|
||||
}
|
||||
else
|
||||
{
|
||||
dest.sin_port = htons(DHCP_CLIENT_PORT);
|
||||
dest.sin_addr = mess->ciaddr;
|
||||
}
|
||||
|
||||
sendto(context->fd, mess, newlen, 0, (struct sockaddr *)&dest, sizeof(dest));
|
||||
}
|
||||
else
|
||||
{
|
||||
/* Hairy stuff, packet either has to go to the
|
||||
net broadcast or the destination can't reply to ARP yet,
|
||||
but we do know the physical address.
|
||||
Build the packet by steam, and send directly, bypassing
|
||||
the kernel IP stack */
|
||||
|
||||
u32 i, sum;
|
||||
#ifdef HAVE_PF_PACKET
|
||||
struct sockaddr_ll dest;
|
||||
|
||||
dest.sll_family = AF_PACKET;
|
||||
dest.sll_halen = ETHER_ADDR_LEN;
|
||||
dest.sll_ifindex = context->ifindex;
|
||||
dest.sll_protocol = htons(ETHERTYPE_IP);
|
||||
|
||||
if (broadcast)
|
||||
{
|
||||
memset(dest.sll_addr, 255, ETHER_ADDR_LEN);
|
||||
rawpacket->ip.ip_dst.s_addr = INADDR_BROADCAST;
|
||||
}
|
||||
else
|
||||
{
|
||||
memcpy(dest.sll_addr, mess->chaddr, ETHER_ADDR_LEN);
|
||||
rawpacket->ip.ip_dst.s_addr = mess->yiaddr.s_addr;
|
||||
}
|
||||
#endif
|
||||
|
||||
#ifdef HAVE_BPF
|
||||
struct ether_header header;
|
||||
struct iovec iov [2];
|
||||
|
||||
header.ether_type = htons(ETHERTYPE_IP);
|
||||
memcpy(header.ether_shost, context->hwaddr, ETHER_ADDR_LEN);
|
||||
|
||||
if (broadcast)
|
||||
{
|
||||
memset(header.ether_dhost, 255, ETHER_ADDR_LEN);
|
||||
rawpacket->ip.ip_dst.s_addr = INADDR_BROADCAST;
|
||||
}
|
||||
else
|
||||
{
|
||||
memcpy(header.ether_dhost, mess->chaddr, ETHER_ADDR_LEN);
|
||||
rawpacket->ip.ip_dst.s_addr = mess->yiaddr.s_addr;
|
||||
}
|
||||
#endif
|
||||
|
||||
rawpacket->ip.ip_p = IPPROTO_UDP;
|
||||
rawpacket->ip.ip_src.s_addr = context->serv_addr.s_addr;
|
||||
rawpacket->ip.ip_len = htons(sizeof(struct ip) +
|
||||
sizeof(struct udphdr) +
|
||||
newlen) ;
|
||||
rawpacket->ip.ip_hl = sizeof(struct ip) / 4;
|
||||
rawpacket->ip.ip_v = IPVERSION;
|
||||
rawpacket->ip.ip_tos = 0;
|
||||
rawpacket->ip.ip_id = htons(0);
|
||||
rawpacket->ip.ip_off = htons(0x4000); /* don't fragment */
|
||||
rawpacket->ip.ip_ttl = IPDEFTTL;
|
||||
rawpacket->ip.ip_sum = 0;
|
||||
for (sum = 0, i = 0; i < sizeof(struct ip) / 2; i++)
|
||||
sum += ((u16 *)&rawpacket->ip)[i];
|
||||
while (sum>>16)
|
||||
sum = (sum & 0xffff) + (sum >> 16);
|
||||
rawpacket->ip.ip_sum = (sum == 0xffff) ? sum : ~sum;
|
||||
|
||||
rawpacket->udp.uh_sport = htons(DHCP_SERVER_PORT);
|
||||
rawpacket->udp.uh_dport = htons(DHCP_CLIENT_PORT);
|
||||
((u8 *)&rawpacket->data)[newlen] = 0; /* for checksum, in case length is odd. */
|
||||
rawpacket->udp.uh_sum = 0;
|
||||
rawpacket->udp.uh_ulen = sum = htons(sizeof(struct udphdr) + newlen);
|
||||
sum += htons(IPPROTO_UDP);
|
||||
for (i = 0; i < 4; i++)
|
||||
sum += ((u16 *)&rawpacket->ip.ip_src)[i];
|
||||
for (i = 0; i < (sizeof(struct udphdr) + newlen + 1) / 2; i++)
|
||||
sum += ((u16 *)&rawpacket->udp)[i];
|
||||
while (sum>>16)
|
||||
sum = (sum & 0xffff) + (sum >> 16);
|
||||
rawpacket->udp.uh_sum = (sum == 0xffff) ? sum : ~sum;
|
||||
|
||||
#ifdef HAVE_PF_PACKET
|
||||
sendto(context->rawfd, rawpacket, ntohs(rawpacket->ip.ip_len),
|
||||
0, (struct sockaddr *)&dest, sizeof(dest));
|
||||
#endif
|
||||
|
||||
#ifdef HAVE_BPF
|
||||
iov[0].iov_base = (char *)&header;
|
||||
iov[0].iov_len = sizeof(struct ether_header);
|
||||
iov[1].iov_base = (char *)rawpacket;
|
||||
iov[1].iov_len = ntohs(rawpacket->ip.ip_len);
|
||||
writev(context->rawfd, iov, 2);
|
||||
#endif
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
int address_available(struct dhcp_context *context, struct in_addr taddr)
|
||||
{
|
||||
/* Check is an address is OK for this network, ie
|
||||
within allowable range and not in an existing lease */
|
||||
|
||||
unsigned int addr, start, end;
|
||||
|
||||
addr = ntohl(taddr.s_addr);
|
||||
start = ntohl(context->start.s_addr);
|
||||
end = ntohl(context->end.s_addr);
|
||||
|
||||
if (addr < start)
|
||||
return 0;
|
||||
|
||||
if (addr > end)
|
||||
return 0;
|
||||
|
||||
if (lease_find_by_addr(taddr))
|
||||
return 0;
|
||||
|
||||
return 1;
|
||||
}
|
||||
|
||||
int address_allocate(struct dhcp_context *context, struct dhcp_config *configs,
|
||||
struct in_addr *addrp)
|
||||
{
|
||||
/* Find a free address: exlude anything in use and anything allocated to
|
||||
a particular hwaddr/clientid/hostname in our configuration */
|
||||
|
||||
struct dhcp_config *config;
|
||||
struct in_addr start = context->last;
|
||||
|
||||
do {
|
||||
if (context->last.s_addr == context->end.s_addr)
|
||||
context->last = context->start;
|
||||
else
|
||||
context->last.s_addr = htonl(ntohl(context->last.s_addr) + 1);
|
||||
|
||||
|
||||
if (!lease_find_by_addr(context->last))
|
||||
{
|
||||
for (config = configs; config; config = config->next)
|
||||
if (config->addr.s_addr == context->last.s_addr)
|
||||
break;
|
||||
|
||||
if (!config)
|
||||
{
|
||||
*addrp = context->last;
|
||||
return 1;
|
||||
}
|
||||
}
|
||||
} while (context->last.s_addr != start.s_addr);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int is_addr_in_context(struct dhcp_context *context, struct dhcp_config *config)
|
||||
{
|
||||
if (!context)
|
||||
return 1;
|
||||
if (config->addr.s_addr == 0)
|
||||
return 1;
|
||||
if ((config->addr.s_addr & context->netmask.s_addr) == (context->start.s_addr & context->netmask.s_addr))
|
||||
return 1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
struct dhcp_config *find_config(struct dhcp_config *configs,
|
||||
struct dhcp_context *context,
|
||||
unsigned char *clid, int clid_len,
|
||||
unsigned char *hwaddr, char *hostname)
|
||||
{
|
||||
struct dhcp_config *config;
|
||||
|
||||
if (clid_len)
|
||||
for (config = configs; config; config = config->next)
|
||||
{
|
||||
if (config->clid_len == clid_len &&
|
||||
memcmp(config->clid, clid, clid_len) == 0 &&
|
||||
is_addr_in_context(context, config))
|
||||
return config;
|
||||
|
||||
/* dhcpcd prefixes ASCII client IDs by zero which is wrong, but we try and
|
||||
cope with that here */
|
||||
if (*clid == 0 && config->clid_len == clid_len-1 &&
|
||||
memcmp(config->clid, clid+1, clid_len-1) == 0 &&
|
||||
is_addr_in_context(context, config))
|
||||
return config;
|
||||
}
|
||||
|
||||
for (config = configs; config; config = config->next)
|
||||
if (memcmp(config->hwaddr, hwaddr, ETHER_ADDR_LEN) == 0 &&
|
||||
is_addr_in_context(context, config))
|
||||
return config;
|
||||
|
||||
if (hostname)
|
||||
for (config = configs; config; config = config->next)
|
||||
if (config->hostname && strcmp(config->hostname, hostname) == 0 &&
|
||||
is_addr_in_context(context, config))
|
||||
return config;
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user