1149 lines
38 KiB
C
1149 lines
38 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
|
||
/***
|
||
Copyright © 2013 Intel Corporation. All rights reserved.
|
||
***/
|
||
|
||
#include <sys/ioctl.h>
|
||
|
||
#include "sd-dhcp-server.h"
|
||
|
||
#include "alloc-util.h"
|
||
#include "dhcp-internal.h"
|
||
#include "dhcp-server-internal.h"
|
||
#include "fd-util.h"
|
||
#include "in-addr-util.h"
|
||
#include "io-util.h"
|
||
#include "sd-id128.h"
|
||
#include "siphash24.h"
|
||
#include "string-util.h"
|
||
#include "unaligned.h"
|
||
|
||
#define DHCP_DEFAULT_LEASE_TIME_USEC USEC_PER_HOUR
|
||
#define DHCP_MAX_LEASE_TIME_USEC (USEC_PER_HOUR*12)
|
||
|
||
static void dhcp_lease_free(DHCPLease *lease) {
|
||
if (!lease)
|
||
return;
|
||
|
||
free(lease->client_id.data);
|
||
free(lease);
|
||
}
|
||
|
||
/* configures the server's address and subnet, and optionally the pool's size and offset into the subnet
|
||
* the whole pool must fit into the subnet, and may not contain the first (any) nor last (broadcast) address
|
||
* moreover, the server's own address may be in the pool, and is in that case reserved in order not to
|
||
* accidentally hand it out */
|
||
int sd_dhcp_server_configure_pool(sd_dhcp_server *server, struct in_addr *address, unsigned char prefixlen, uint32_t offset, uint32_t size) {
|
||
struct in_addr netmask_addr;
|
||
be32_t netmask;
|
||
uint32_t server_off, broadcast_off, size_max;
|
||
|
||
assert_return(server, -EINVAL);
|
||
assert_return(address, -EINVAL);
|
||
assert_return(address->s_addr != INADDR_ANY, -EINVAL);
|
||
assert_return(prefixlen <= 32, -ERANGE);
|
||
|
||
assert_se(in4_addr_prefixlen_to_netmask(&netmask_addr, prefixlen));
|
||
netmask = netmask_addr.s_addr;
|
||
|
||
server_off = be32toh(address->s_addr & ~netmask);
|
||
broadcast_off = be32toh(~netmask);
|
||
|
||
/* the server address cannot be the subnet address */
|
||
assert_return(server_off != 0, -ERANGE);
|
||
|
||
/* nor the broadcast address */
|
||
assert_return(server_off != broadcast_off, -ERANGE);
|
||
|
||
/* 0 offset means we should set a default, we skip the first (subnet) address
|
||
and take the next one */
|
||
if (offset == 0)
|
||
offset = 1;
|
||
|
||
size_max = (broadcast_off + 1) /* the number of addresses in the subnet */
|
||
- offset /* exclude the addresses before the offset */
|
||
- 1; /* exclude the last (broadcast) address */
|
||
|
||
/* The pool must contain at least one address */
|
||
assert_return(size_max >= 1, -ERANGE);
|
||
|
||
if (size != 0)
|
||
assert_return(size <= size_max, -ERANGE);
|
||
else
|
||
size = size_max;
|
||
|
||
if (server->address != address->s_addr || server->netmask != netmask || server->pool_size != size || server->pool_offset != offset) {
|
||
|
||
free(server->bound_leases);
|
||
server->bound_leases = new0(DHCPLease*, size);
|
||
if (!server->bound_leases)
|
||
return -ENOMEM;
|
||
|
||
server->pool_offset = offset;
|
||
server->pool_size = size;
|
||
|
||
server->address = address->s_addr;
|
||
server->netmask = netmask;
|
||
server->subnet = address->s_addr & netmask;
|
||
|
||
if (server_off >= offset && server_off - offset < size)
|
||
server->bound_leases[server_off - offset] = &server->invalid_lease;
|
||
|
||
/* Drop any leases associated with the old address range */
|
||
hashmap_clear_with_destructor(server->leases_by_client_id, dhcp_lease_free);
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
int sd_dhcp_server_is_running(sd_dhcp_server *server) {
|
||
assert_return(server, false);
|
||
|
||
return !!server->receive_message;
|
||
}
|
||
|
||
void client_id_hash_func(const void *p, struct siphash *state) {
|
||
const DHCPClientId *id = p;
|
||
|
||
assert(id);
|
||
assert(id->length);
|
||
assert(id->data);
|
||
|
||
siphash24_compress(&id->length, sizeof(id->length), state);
|
||
siphash24_compress(id->data, id->length, state);
|
||
}
|
||
|
||
int client_id_compare_func(const void *_a, const void *_b) {
|
||
const DHCPClientId *a, *b;
|
||
int r;
|
||
|
||
a = _a;
|
||
b = _b;
|
||
|
||
assert(!a->length || a->data);
|
||
assert(!b->length || b->data);
|
||
|
||
r = CMP(a->length, b->length);
|
||
if (r != 0)
|
||
return r;
|
||
|
||
return memcmp(a->data, b->data, a->length);
|
||
}
|
||
|
||
static const struct hash_ops client_id_hash_ops = {
|
||
.hash = client_id_hash_func,
|
||
.compare = client_id_compare_func
|
||
};
|
||
|
||
static sd_dhcp_server *dhcp_server_free(sd_dhcp_server *server) {
|
||
DHCPLease *lease;
|
||
|
||
assert(server);
|
||
|
||
log_dhcp_server(server, "UNREF");
|
||
|
||
sd_dhcp_server_stop(server);
|
||
|
||
sd_event_unref(server->event);
|
||
|
||
free(server->timezone);
|
||
free(server->dns);
|
||
free(server->ntp);
|
||
|
||
while ((lease = hashmap_steal_first(server->leases_by_client_id)))
|
||
dhcp_lease_free(lease);
|
||
hashmap_free(server->leases_by_client_id);
|
||
|
||
free(server->bound_leases);
|
||
return mfree(server);
|
||
}
|
||
|
||
DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_dhcp_server, sd_dhcp_server, dhcp_server_free);
|
||
|
||
int sd_dhcp_server_new(sd_dhcp_server **ret, int ifindex) {
|
||
_cleanup_(sd_dhcp_server_unrefp) sd_dhcp_server *server = NULL;
|
||
|
||
assert_return(ret, -EINVAL);
|
||
assert_return(ifindex > 0, -EINVAL);
|
||
|
||
server = new0(sd_dhcp_server, 1);
|
||
if (!server)
|
||
return -ENOMEM;
|
||
|
||
server->n_ref = 1;
|
||
server->fd_raw = -1;
|
||
server->fd = -1;
|
||
server->address = htobe32(INADDR_ANY);
|
||
server->netmask = htobe32(INADDR_ANY);
|
||
server->ifindex = ifindex;
|
||
|
||
server->leases_by_client_id = hashmap_new(&client_id_hash_ops);
|
||
if (!server->leases_by_client_id)
|
||
return -ENOMEM;
|
||
|
||
server->default_lease_time = DIV_ROUND_UP(DHCP_DEFAULT_LEASE_TIME_USEC, USEC_PER_SEC);
|
||
server->max_lease_time = DIV_ROUND_UP(DHCP_MAX_LEASE_TIME_USEC, USEC_PER_SEC);
|
||
|
||
*ret = TAKE_PTR(server);
|
||
|
||
return 0;
|
||
}
|
||
|
||
int sd_dhcp_server_attach_event(sd_dhcp_server *server, sd_event *event, int64_t priority) {
|
||
int r;
|
||
|
||
assert_return(server, -EINVAL);
|
||
assert_return(!server->event, -EBUSY);
|
||
|
||
if (event)
|
||
server->event = sd_event_ref(event);
|
||
else {
|
||
r = sd_event_default(&server->event);
|
||
if (r < 0)
|
||
return r;
|
||
}
|
||
|
||
server->event_priority = priority;
|
||
|
||
return 0;
|
||
}
|
||
|
||
int sd_dhcp_server_detach_event(sd_dhcp_server *server) {
|
||
assert_return(server, -EINVAL);
|
||
|
||
server->event = sd_event_unref(server->event);
|
||
|
||
return 0;
|
||
}
|
||
|
||
sd_event *sd_dhcp_server_get_event(sd_dhcp_server *server) {
|
||
assert_return(server, NULL);
|
||
|
||
return server->event;
|
||
}
|
||
|
||
int sd_dhcp_server_stop(sd_dhcp_server *server) {
|
||
assert_return(server, -EINVAL);
|
||
|
||
server->receive_message =
|
||
sd_event_source_unref(server->receive_message);
|
||
|
||
server->fd_raw = safe_close(server->fd_raw);
|
||
server->fd = safe_close(server->fd);
|
||
|
||
log_dhcp_server(server, "STOPPED");
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int dhcp_server_send_unicast_raw(sd_dhcp_server *server,
|
||
DHCPPacket *packet, size_t len) {
|
||
union sockaddr_union link = {
|
||
.ll.sll_family = AF_PACKET,
|
||
.ll.sll_protocol = htobe16(ETH_P_IP),
|
||
.ll.sll_ifindex = server->ifindex,
|
||
.ll.sll_halen = ETH_ALEN,
|
||
};
|
||
|
||
assert(server);
|
||
assert(server->ifindex > 0);
|
||
assert(server->address);
|
||
assert(packet);
|
||
assert(len > sizeof(DHCPPacket));
|
||
|
||
memcpy(&link.ll.sll_addr, &packet->dhcp.chaddr, ETH_ALEN);
|
||
|
||
dhcp_packet_append_ip_headers(packet, server->address, DHCP_PORT_SERVER,
|
||
packet->dhcp.yiaddr,
|
||
DHCP_PORT_CLIENT, len);
|
||
|
||
return dhcp_network_send_raw_socket(server->fd_raw, &link, packet, len);
|
||
}
|
||
|
||
static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
|
||
uint16_t destination_port,
|
||
DHCPMessage *message, size_t len) {
|
||
union sockaddr_union dest = {
|
||
.in.sin_family = AF_INET,
|
||
.in.sin_port = htobe16(destination_port),
|
||
.in.sin_addr.s_addr = destination,
|
||
};
|
||
struct iovec iov = {
|
||
.iov_base = message,
|
||
.iov_len = len,
|
||
};
|
||
uint8_t cmsgbuf[CMSG_LEN(sizeof(struct in_pktinfo))] = {};
|
||
struct msghdr msg = {
|
||
.msg_name = &dest,
|
||
.msg_namelen = sizeof(dest.in),
|
||
.msg_iov = &iov,
|
||
.msg_iovlen = 1,
|
||
.msg_control = cmsgbuf,
|
||
.msg_controllen = sizeof(cmsgbuf),
|
||
};
|
||
struct cmsghdr *cmsg;
|
||
struct in_pktinfo *pktinfo;
|
||
|
||
assert(server);
|
||
assert(server->fd >= 0);
|
||
assert(message);
|
||
assert(len > sizeof(DHCPMessage));
|
||
|
||
cmsg = CMSG_FIRSTHDR(&msg);
|
||
assert(cmsg);
|
||
|
||
cmsg->cmsg_level = IPPROTO_IP;
|
||
cmsg->cmsg_type = IP_PKTINFO;
|
||
cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
|
||
|
||
/* we attach source interface and address info to the message
|
||
rather than binding the socket. This will be mostly useful
|
||
when we gain support for arbitrary number of server addresses
|
||
*/
|
||
pktinfo = (struct in_pktinfo*) CMSG_DATA(cmsg);
|
||
assert(pktinfo);
|
||
|
||
pktinfo->ipi_ifindex = server->ifindex;
|
||
pktinfo->ipi_spec_dst.s_addr = server->address;
|
||
|
||
if (sendmsg(server->fd, &msg, 0) < 0)
|
||
return -errno;
|
||
|
||
return 0;
|
||
}
|
||
|
||
static bool requested_broadcast(DHCPRequest *req) {
|
||
assert(req);
|
||
|
||
return req->message->flags & htobe16(0x8000);
|
||
}
|
||
|
||
int dhcp_server_send_packet(sd_dhcp_server *server,
|
||
DHCPRequest *req, DHCPPacket *packet,
|
||
int type, size_t optoffset) {
|
||
be32_t destination = INADDR_ANY;
|
||
uint16_t destination_port = DHCP_PORT_CLIENT;
|
||
int r;
|
||
|
||
assert(server);
|
||
assert(req);
|
||
assert(req->max_optlen);
|
||
assert(optoffset <= req->max_optlen);
|
||
assert(packet);
|
||
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &optoffset, 0,
|
||
SD_DHCP_OPTION_SERVER_IDENTIFIER,
|
||
4, &server->address);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &optoffset, 0,
|
||
SD_DHCP_OPTION_END, 0, NULL);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
/* RFC 2131 Section 4.1
|
||
|
||
If the ’giaddr’ field in a DHCP message from a client is non-zero,
|
||
the server sends any return messages to the ’DHCP server’ port on the
|
||
BOOTP relay agent whose address appears in ’giaddr’. If the ’giaddr’
|
||
field is zero and the ’ciaddr’ field is nonzero, then the server
|
||
unicasts DHCPOFFER and DHCPACK messages to the address in ’ciaddr’.
|
||
If ’giaddr’ is zero and ’ciaddr’ is zero, and the broadcast bit is
|
||
set, then the server broadcasts DHCPOFFER and DHCPACK messages to
|
||
0xffffffff. If the broadcast bit is not set and ’giaddr’ is zero and
|
||
’ciaddr’ is zero, then the server unicasts DHCPOFFER and DHCPACK
|
||
messages to the client’s hardware address and ’yiaddr’ address. In
|
||
all cases, when ’giaddr’ is zero, the server broadcasts any DHCPNAK
|
||
messages to 0xffffffff.
|
||
|
||
Section 4.3.2
|
||
|
||
If ’giaddr’ is set in the DHCPREQUEST message, the client is on a
|
||
different subnet. The server MUST set the broadcast bit in the
|
||
DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the
|
||
client, because the client may not have a correct network address
|
||
or subnet mask, and the client may not be answering ARP requests.
|
||
*/
|
||
if (req->message->giaddr) {
|
||
destination = req->message->giaddr;
|
||
destination_port = DHCP_PORT_SERVER;
|
||
if (type == DHCP_NAK)
|
||
packet->dhcp.flags = htobe16(0x8000);
|
||
} else if (req->message->ciaddr && type != DHCP_NAK)
|
||
destination = req->message->ciaddr;
|
||
|
||
if (destination != INADDR_ANY)
|
||
return dhcp_server_send_udp(server, destination,
|
||
destination_port, &packet->dhcp,
|
||
sizeof(DHCPMessage) + optoffset);
|
||
else if (requested_broadcast(req) || type == DHCP_NAK)
|
||
return dhcp_server_send_udp(server, INADDR_BROADCAST,
|
||
destination_port, &packet->dhcp,
|
||
sizeof(DHCPMessage) + optoffset);
|
||
else
|
||
/* we cannot send UDP packet to specific MAC address when the
|
||
address is not yet configured, so must fall back to raw
|
||
packets */
|
||
return dhcp_server_send_unicast_raw(server, packet,
|
||
sizeof(DHCPPacket) + optoffset);
|
||
}
|
||
|
||
static int server_message_init(sd_dhcp_server *server, DHCPPacket **ret,
|
||
uint8_t type, size_t *_optoffset,
|
||
DHCPRequest *req) {
|
||
_cleanup_free_ DHCPPacket *packet = NULL;
|
||
size_t optoffset = 0;
|
||
int r;
|
||
|
||
assert(server);
|
||
assert(ret);
|
||
assert(_optoffset);
|
||
assert(IN_SET(type, DHCP_OFFER, DHCP_ACK, DHCP_NAK));
|
||
|
||
packet = malloc0(sizeof(DHCPPacket) + req->max_optlen);
|
||
if (!packet)
|
||
return -ENOMEM;
|
||
|
||
r = dhcp_message_init(&packet->dhcp, BOOTREPLY,
|
||
be32toh(req->message->xid), type, ARPHRD_ETHER,
|
||
req->max_optlen, &optoffset);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
packet->dhcp.flags = req->message->flags;
|
||
packet->dhcp.giaddr = req->message->giaddr;
|
||
memcpy(&packet->dhcp.chaddr, &req->message->chaddr, ETH_ALEN);
|
||
|
||
*_optoffset = optoffset;
|
||
*ret = TAKE_PTR(packet);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int server_send_offer(sd_dhcp_server *server, DHCPRequest *req,
|
||
be32_t address) {
|
||
_cleanup_free_ DHCPPacket *packet = NULL;
|
||
size_t offset;
|
||
be32_t lease_time;
|
||
int r;
|
||
|
||
r = server_message_init(server, &packet, DHCP_OFFER, &offset, req);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
packet->dhcp.yiaddr = address;
|
||
|
||
lease_time = htobe32(req->lifetime);
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4,
|
||
&lease_time);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_SUBNET_MASK, 4, &server->netmask);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
if (server->emit_router) {
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_ROUTER, 4, &server->address);
|
||
if (r < 0)
|
||
return r;
|
||
}
|
||
|
||
r = dhcp_server_send_packet(server, req, packet, DHCP_OFFER, offset);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int server_send_ack(sd_dhcp_server *server, DHCPRequest *req,
|
||
be32_t address) {
|
||
_cleanup_free_ DHCPPacket *packet = NULL;
|
||
size_t offset;
|
||
be32_t lease_time;
|
||
int r;
|
||
|
||
r = server_message_init(server, &packet, DHCP_ACK, &offset, req);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
packet->dhcp.yiaddr = address;
|
||
|
||
lease_time = htobe32(req->lifetime);
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4,
|
||
&lease_time);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_SUBNET_MASK, 4, &server->netmask);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
if (server->emit_router) {
|
||
r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_ROUTER, 4, &server->address);
|
||
if (r < 0)
|
||
return r;
|
||
}
|
||
|
||
if (server->n_dns > 0) {
|
||
r = dhcp_option_append(
|
||
&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_DOMAIN_NAME_SERVER,
|
||
sizeof(struct in_addr) * server->n_dns, server->dns);
|
||
if (r < 0)
|
||
return r;
|
||
}
|
||
|
||
if (server->n_ntp > 0) {
|
||
r = dhcp_option_append(
|
||
&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_NTP_SERVER,
|
||
sizeof(struct in_addr) * server->n_ntp, server->ntp);
|
||
if (r < 0)
|
||
return r;
|
||
}
|
||
|
||
if (server->timezone) {
|
||
r = dhcp_option_append(
|
||
&packet->dhcp, req->max_optlen, &offset, 0,
|
||
SD_DHCP_OPTION_NEW_TZDB_TIMEZONE,
|
||
strlen(server->timezone), server->timezone);
|
||
if (r < 0)
|
||
return r;
|
||
}
|
||
|
||
r = dhcp_server_send_packet(server, req, packet, DHCP_ACK, offset);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int server_send_nak(sd_dhcp_server *server, DHCPRequest *req) {
|
||
_cleanup_free_ DHCPPacket *packet = NULL;
|
||
size_t offset;
|
||
int r;
|
||
|
||
r = server_message_init(server, &packet, DHCP_NAK, &offset, req);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
return dhcp_server_send_packet(server, req, packet, DHCP_NAK, offset);
|
||
}
|
||
|
||
static int server_send_forcerenew(sd_dhcp_server *server, be32_t address,
|
||
be32_t gateway, uint8_t chaddr[]) {
|
||
_cleanup_free_ DHCPPacket *packet = NULL;
|
||
size_t optoffset = 0;
|
||
int r;
|
||
|
||
assert(server);
|
||
assert(address != INADDR_ANY);
|
||
assert(chaddr);
|
||
|
||
packet = malloc0(sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE);
|
||
if (!packet)
|
||
return -ENOMEM;
|
||
|
||
r = dhcp_message_init(&packet->dhcp, BOOTREPLY, 0,
|
||
DHCP_FORCERENEW, ARPHRD_ETHER,
|
||
DHCP_MIN_OPTIONS_SIZE, &optoffset);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
r = dhcp_option_append(&packet->dhcp, DHCP_MIN_OPTIONS_SIZE,
|
||
&optoffset, 0, SD_DHCP_OPTION_END, 0, NULL);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
memcpy(&packet->dhcp.chaddr, chaddr, ETH_ALEN);
|
||
|
||
r = dhcp_server_send_udp(server, address, DHCP_PORT_CLIENT,
|
||
&packet->dhcp,
|
||
sizeof(DHCPMessage) + optoffset);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int parse_request(uint8_t code, uint8_t len, const void *option, void *userdata) {
|
||
DHCPRequest *req = userdata;
|
||
|
||
assert(req);
|
||
|
||
switch(code) {
|
||
case SD_DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
|
||
if (len == 4)
|
||
req->lifetime = unaligned_read_be32(option);
|
||
|
||
break;
|
||
case SD_DHCP_OPTION_REQUESTED_IP_ADDRESS:
|
||
if (len == 4)
|
||
memcpy(&req->requested_ip, option, sizeof(be32_t));
|
||
|
||
break;
|
||
case SD_DHCP_OPTION_SERVER_IDENTIFIER:
|
||
if (len == 4)
|
||
memcpy(&req->server_id, option, sizeof(be32_t));
|
||
|
||
break;
|
||
case SD_DHCP_OPTION_CLIENT_IDENTIFIER:
|
||
if (len >= 2) {
|
||
uint8_t *data;
|
||
|
||
data = memdup(option, len);
|
||
if (!data)
|
||
return -ENOMEM;
|
||
|
||
free(req->client_id.data);
|
||
req->client_id.data = data;
|
||
req->client_id.length = len;
|
||
}
|
||
|
||
break;
|
||
case SD_DHCP_OPTION_MAXIMUM_MESSAGE_SIZE:
|
||
|
||
if (len == 2 && unaligned_read_be16(option) >= sizeof(DHCPPacket))
|
||
req->max_optlen = unaligned_read_be16(option) - sizeof(DHCPPacket);
|
||
|
||
break;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static void dhcp_request_free(DHCPRequest *req) {
|
||
if (!req)
|
||
return;
|
||
|
||
free(req->client_id.data);
|
||
free(req);
|
||
}
|
||
|
||
DEFINE_TRIVIAL_CLEANUP_FUNC(DHCPRequest*, dhcp_request_free);
|
||
|
||
static int ensure_sane_request(sd_dhcp_server *server, DHCPRequest *req, DHCPMessage *message) {
|
||
assert(req);
|
||
assert(message);
|
||
|
||
req->message = message;
|
||
|
||
/* set client id based on MAC address if client did not send an explicit
|
||
one */
|
||
if (!req->client_id.data) {
|
||
void *data;
|
||
|
||
data = malloc0(ETH_ALEN + 1);
|
||
if (!data)
|
||
return -ENOMEM;
|
||
|
||
((uint8_t*) data)[0] = 0x01;
|
||
memcpy((uint8_t*) data + 1, &message->chaddr, ETH_ALEN);
|
||
|
||
req->client_id.length = ETH_ALEN + 1;
|
||
req->client_id.data = data;
|
||
}
|
||
|
||
if (req->max_optlen < DHCP_MIN_OPTIONS_SIZE)
|
||
req->max_optlen = DHCP_MIN_OPTIONS_SIZE;
|
||
|
||
if (req->lifetime <= 0)
|
||
req->lifetime = MAX(1ULL, server->default_lease_time);
|
||
|
||
if (server->max_lease_time > 0 && req->lifetime > server->max_lease_time)
|
||
req->lifetime = server->max_lease_time;
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int get_pool_offset(sd_dhcp_server *server, be32_t requested_ip) {
|
||
assert(server);
|
||
|
||
if (!server->pool_size)
|
||
return -EINVAL;
|
||
|
||
if (be32toh(requested_ip) < (be32toh(server->subnet) | server->pool_offset) ||
|
||
be32toh(requested_ip) >= (be32toh(server->subnet) | (server->pool_offset + server->pool_size)))
|
||
return -ERANGE;
|
||
|
||
return be32toh(requested_ip & ~server->netmask) - server->pool_offset;
|
||
}
|
||
|
||
#define HASH_KEY SD_ID128_MAKE(0d,1d,fe,bd,f1,24,bd,b3,47,f1,dd,6e,73,21,93,30)
|
||
|
||
int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
|
||
size_t length) {
|
||
_cleanup_(dhcp_request_freep) DHCPRequest *req = NULL;
|
||
_cleanup_free_ char *error_message = NULL;
|
||
DHCPLease *existing_lease;
|
||
int type, r;
|
||
|
||
assert(server);
|
||
assert(message);
|
||
|
||
if (message->op != BOOTREQUEST ||
|
||
message->htype != ARPHRD_ETHER ||
|
||
message->hlen != ETHER_ADDR_LEN)
|
||
return 0;
|
||
|
||
req = new0(DHCPRequest, 1);
|
||
if (!req)
|
||
return -ENOMEM;
|
||
|
||
type = dhcp_option_parse(message, length, parse_request, req, &error_message);
|
||
if (type < 0)
|
||
return 0;
|
||
|
||
r = ensure_sane_request(server, req, message);
|
||
if (r < 0)
|
||
/* this only fails on critical errors */
|
||
return r;
|
||
|
||
existing_lease = hashmap_get(server->leases_by_client_id,
|
||
&req->client_id);
|
||
|
||
switch(type) {
|
||
|
||
case DHCP_DISCOVER: {
|
||
be32_t address = INADDR_ANY;
|
||
unsigned i;
|
||
|
||
log_dhcp_server(server, "DISCOVER (0x%x)",
|
||
be32toh(req->message->xid));
|
||
|
||
if (!server->pool_size)
|
||
/* no pool allocated */
|
||
return 0;
|
||
|
||
/* for now pick a random free address from the pool */
|
||
if (existing_lease)
|
||
address = existing_lease->address;
|
||
else {
|
||
struct siphash state;
|
||
uint64_t hash;
|
||
uint32_t next_offer;
|
||
|
||
/* even with no persistence of leases, we try to offer the same client
|
||
the same IP address. we do this by using the hash of the client id
|
||
as the offset into the pool of leases when finding the next free one */
|
||
|
||
siphash24_init(&state, HASH_KEY.bytes);
|
||
client_id_hash_func(&req->client_id, &state);
|
||
hash = htole64(siphash24_finalize(&state));
|
||
next_offer = hash % server->pool_size;
|
||
|
||
for (i = 0; i < server->pool_size; i++) {
|
||
if (!server->bound_leases[next_offer]) {
|
||
address = server->subnet | htobe32(server->pool_offset + next_offer);
|
||
break;
|
||
}
|
||
|
||
next_offer = (next_offer + 1) % server->pool_size;
|
||
}
|
||
}
|
||
|
||
if (address == INADDR_ANY)
|
||
/* no free addresses left */
|
||
return 0;
|
||
|
||
r = server_send_offer(server, req, address);
|
||
if (r < 0)
|
||
/* this only fails on critical errors */
|
||
return log_dhcp_server_errno(server, r, "Could not send offer: %m");
|
||
|
||
log_dhcp_server(server, "OFFER (0x%x)", be32toh(req->message->xid));
|
||
return DHCP_OFFER;
|
||
}
|
||
case DHCP_DECLINE:
|
||
log_dhcp_server(server, "DECLINE (0x%x): %s", be32toh(req->message->xid), strna(error_message));
|
||
|
||
/* TODO: make sure we don't offer this address again */
|
||
|
||
return 1;
|
||
|
||
case DHCP_REQUEST: {
|
||
be32_t address;
|
||
bool init_reboot = false;
|
||
int pool_offset;
|
||
|
||
/* see RFC 2131, section 4.3.2 */
|
||
|
||
if (req->server_id) {
|
||
log_dhcp_server(server, "REQUEST (selecting) (0x%x)",
|
||
be32toh(req->message->xid));
|
||
|
||
/* SELECTING */
|
||
if (req->server_id != server->address)
|
||
/* client did not pick us */
|
||
return 0;
|
||
|
||
if (req->message->ciaddr)
|
||
/* this MUST be zero */
|
||
return 0;
|
||
|
||
if (!req->requested_ip)
|
||
/* this must be filled in with the yiaddr
|
||
from the chosen OFFER */
|
||
return 0;
|
||
|
||
address = req->requested_ip;
|
||
} else if (req->requested_ip) {
|
||
log_dhcp_server(server, "REQUEST (init-reboot) (0x%x)",
|
||
be32toh(req->message->xid));
|
||
|
||
/* INIT-REBOOT */
|
||
if (req->message->ciaddr)
|
||
/* this MUST be zero */
|
||
return 0;
|
||
|
||
/* TODO: check more carefully if IP is correct */
|
||
address = req->requested_ip;
|
||
init_reboot = true;
|
||
} else {
|
||
log_dhcp_server(server, "REQUEST (rebinding/renewing) (0x%x)",
|
||
be32toh(req->message->xid));
|
||
|
||
/* REBINDING / RENEWING */
|
||
if (!req->message->ciaddr)
|
||
/* this MUST be filled in with clients IP address */
|
||
return 0;
|
||
|
||
address = req->message->ciaddr;
|
||
}
|
||
|
||
pool_offset = get_pool_offset(server, address);
|
||
|
||
/* verify that the requested address is from the pool, and either
|
||
owned by the current client or free */
|
||
if (pool_offset >= 0 &&
|
||
server->bound_leases[pool_offset] == existing_lease) {
|
||
DHCPLease *lease;
|
||
usec_t time_now = 0;
|
||
|
||
if (!existing_lease) {
|
||
lease = new0(DHCPLease, 1);
|
||
if (!lease)
|
||
return -ENOMEM;
|
||
lease->address = address;
|
||
lease->client_id.data = memdup(req->client_id.data,
|
||
req->client_id.length);
|
||
if (!lease->client_id.data) {
|
||
free(lease);
|
||
return -ENOMEM;
|
||
}
|
||
lease->client_id.length = req->client_id.length;
|
||
memcpy(&lease->chaddr, &req->message->chaddr,
|
||
ETH_ALEN);
|
||
lease->gateway = req->message->giaddr;
|
||
} else
|
||
lease = existing_lease;
|
||
|
||
r = sd_event_now(server->event,
|
||
clock_boottime_or_monotonic(),
|
||
&time_now);
|
||
if (r < 0) {
|
||
if (!existing_lease)
|
||
dhcp_lease_free(lease);
|
||
return r;
|
||
}
|
||
|
||
lease->expiration = req->lifetime * USEC_PER_SEC + time_now;
|
||
|
||
r = server_send_ack(server, req, address);
|
||
if (r < 0) {
|
||
/* this only fails on critical errors */
|
||
log_dhcp_server_errno(server, r, "Could not send ack: %m");
|
||
|
||
if (!existing_lease)
|
||
dhcp_lease_free(lease);
|
||
|
||
return r;
|
||
} else {
|
||
log_dhcp_server(server, "ACK (0x%x)",
|
||
be32toh(req->message->xid));
|
||
|
||
server->bound_leases[pool_offset] = lease;
|
||
hashmap_put(server->leases_by_client_id,
|
||
&lease->client_id, lease);
|
||
|
||
return DHCP_ACK;
|
||
}
|
||
|
||
} else if (init_reboot) {
|
||
r = server_send_nak(server, req);
|
||
if (r < 0)
|
||
/* this only fails on critical errors */
|
||
return log_dhcp_server_errno(server, r, "Could not send nak: %m");
|
||
|
||
log_dhcp_server(server, "NAK (0x%x)", be32toh(req->message->xid));
|
||
return DHCP_NAK;
|
||
}
|
||
|
||
break;
|
||
}
|
||
|
||
case DHCP_RELEASE: {
|
||
int pool_offset;
|
||
|
||
log_dhcp_server(server, "RELEASE (0x%x)",
|
||
be32toh(req->message->xid));
|
||
|
||
if (!existing_lease)
|
||
return 0;
|
||
|
||
if (existing_lease->address != req->message->ciaddr)
|
||
return 0;
|
||
|
||
pool_offset = get_pool_offset(server, req->message->ciaddr);
|
||
if (pool_offset < 0)
|
||
return 0;
|
||
|
||
if (server->bound_leases[pool_offset] == existing_lease) {
|
||
server->bound_leases[pool_offset] = NULL;
|
||
hashmap_remove(server->leases_by_client_id, existing_lease);
|
||
dhcp_lease_free(existing_lease);
|
||
}
|
||
|
||
return 0;
|
||
}}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int server_receive_message(sd_event_source *s, int fd,
|
||
uint32_t revents, void *userdata) {
|
||
_cleanup_free_ DHCPMessage *message = NULL;
|
||
uint8_t cmsgbuf[CMSG_LEN(sizeof(struct in_pktinfo))];
|
||
sd_dhcp_server *server = userdata;
|
||
struct iovec iov = {};
|
||
struct msghdr msg = {
|
||
.msg_iov = &iov,
|
||
.msg_iovlen = 1,
|
||
.msg_control = cmsgbuf,
|
||
.msg_controllen = sizeof(cmsgbuf),
|
||
};
|
||
struct cmsghdr *cmsg;
|
||
ssize_t buflen, len;
|
||
int r;
|
||
|
||
assert(server);
|
||
|
||
buflen = next_datagram_size_fd(fd);
|
||
if (buflen < 0)
|
||
return buflen;
|
||
|
||
message = malloc(buflen);
|
||
if (!message)
|
||
return -ENOMEM;
|
||
|
||
iov = IOVEC_MAKE(message, buflen);
|
||
|
||
len = recvmsg(fd, &msg, 0);
|
||
if (len < 0) {
|
||
if (IN_SET(errno, EAGAIN, EINTR))
|
||
return 0;
|
||
|
||
return -errno;
|
||
}
|
||
if ((size_t)len < sizeof(DHCPMessage))
|
||
return 0;
|
||
|
||
CMSG_FOREACH(cmsg, &msg) {
|
||
if (cmsg->cmsg_level == IPPROTO_IP &&
|
||
cmsg->cmsg_type == IP_PKTINFO &&
|
||
cmsg->cmsg_len == CMSG_LEN(sizeof(struct in_pktinfo))) {
|
||
struct in_pktinfo *info = (struct in_pktinfo*)CMSG_DATA(cmsg);
|
||
|
||
/* TODO figure out if this can be done as a filter on
|
||
* the socket, like for IPv6 */
|
||
if (server->ifindex != info->ipi_ifindex)
|
||
return 0;
|
||
|
||
break;
|
||
}
|
||
}
|
||
|
||
r = dhcp_server_handle_message(server, message, (size_t) len);
|
||
if (r < 0)
|
||
log_dhcp_server_errno(server, r, "Couldn't process incoming message: %m");
|
||
|
||
return 0;
|
||
}
|
||
|
||
int sd_dhcp_server_start(sd_dhcp_server *server) {
|
||
int r;
|
||
|
||
assert_return(server, -EINVAL);
|
||
assert_return(server->event, -EINVAL);
|
||
assert_return(!server->receive_message, -EBUSY);
|
||
assert_return(server->fd_raw < 0, -EBUSY);
|
||
assert_return(server->fd < 0, -EBUSY);
|
||
assert_return(server->address != htobe32(INADDR_ANY), -EUNATCH);
|
||
|
||
r = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
|
||
if (r < 0) {
|
||
r = -errno;
|
||
sd_dhcp_server_stop(server);
|
||
return r;
|
||
}
|
||
server->fd_raw = r;
|
||
|
||
r = dhcp_network_bind_udp_socket(server->ifindex, INADDR_ANY, DHCP_PORT_SERVER);
|
||
if (r < 0) {
|
||
sd_dhcp_server_stop(server);
|
||
return r;
|
||
}
|
||
server->fd = r;
|
||
|
||
r = sd_event_add_io(server->event, &server->receive_message,
|
||
server->fd, EPOLLIN,
|
||
server_receive_message, server);
|
||
if (r < 0) {
|
||
sd_dhcp_server_stop(server);
|
||
return r;
|
||
}
|
||
|
||
r = sd_event_source_set_priority(server->receive_message,
|
||
server->event_priority);
|
||
if (r < 0) {
|
||
sd_dhcp_server_stop(server);
|
||
return r;
|
||
}
|
||
|
||
log_dhcp_server(server, "STARTED");
|
||
|
||
return 0;
|
||
}
|
||
|
||
int sd_dhcp_server_forcerenew(sd_dhcp_server *server) {
|
||
unsigned i;
|
||
int r = 0;
|
||
|
||
assert_return(server, -EINVAL);
|
||
assert(server->bound_leases);
|
||
|
||
for (i = 0; i < server->pool_size; i++) {
|
||
DHCPLease *lease = server->bound_leases[i];
|
||
|
||
if (!lease || lease == &server->invalid_lease)
|
||
continue;
|
||
|
||
r = server_send_forcerenew(server, lease->address,
|
||
lease->gateway,
|
||
lease->chaddr);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
log_dhcp_server(server, "FORCERENEW");
|
||
}
|
||
|
||
return r;
|
||
}
|
||
|
||
int sd_dhcp_server_set_timezone(sd_dhcp_server *server, const char *tz) {
|
||
int r;
|
||
|
||
assert_return(server, -EINVAL);
|
||
assert_return(timezone_is_valid(tz, LOG_DEBUG), -EINVAL);
|
||
|
||
if (streq_ptr(tz, server->timezone))
|
||
return 0;
|
||
|
||
r = free_and_strdup(&server->timezone, tz);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
return 1;
|
||
}
|
||
|
||
int sd_dhcp_server_set_max_lease_time(sd_dhcp_server *server, uint32_t t) {
|
||
assert_return(server, -EINVAL);
|
||
|
||
if (t == server->max_lease_time)
|
||
return 0;
|
||
|
||
server->max_lease_time = t;
|
||
return 1;
|
||
}
|
||
|
||
int sd_dhcp_server_set_default_lease_time(sd_dhcp_server *server, uint32_t t) {
|
||
assert_return(server, -EINVAL);
|
||
|
||
if (t == server->default_lease_time)
|
||
return 0;
|
||
|
||
server->default_lease_time = t;
|
||
return 1;
|
||
}
|
||
|
||
int sd_dhcp_server_set_dns(sd_dhcp_server *server, const struct in_addr dns[], unsigned n) {
|
||
assert_return(server, -EINVAL);
|
||
assert_return(dns || n <= 0, -EINVAL);
|
||
|
||
if (server->n_dns == n &&
|
||
memcmp(server->dns, dns, sizeof(struct in_addr) * n) == 0)
|
||
return 0;
|
||
|
||
if (n <= 0) {
|
||
server->dns = mfree(server->dns);
|
||
server->n_dns = 0;
|
||
} else {
|
||
struct in_addr *c;
|
||
|
||
c = newdup(struct in_addr, dns, n);
|
||
if (!c)
|
||
return -ENOMEM;
|
||
|
||
free(server->dns);
|
||
server->dns = c;
|
||
server->n_dns = n;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
int sd_dhcp_server_set_ntp(sd_dhcp_server *server, const struct in_addr ntp[], unsigned n) {
|
||
assert_return(server, -EINVAL);
|
||
assert_return(ntp || n <= 0, -EINVAL);
|
||
|
||
if (server->n_ntp == n &&
|
||
memcmp(server->ntp, ntp, sizeof(struct in_addr) * n) == 0)
|
||
return 0;
|
||
|
||
if (n <= 0) {
|
||
server->ntp = mfree(server->ntp);
|
||
server->n_ntp = 0;
|
||
} else {
|
||
struct in_addr *c;
|
||
|
||
c = newdup(struct in_addr, ntp, n);
|
||
if (!c)
|
||
return -ENOMEM;
|
||
|
||
free(server->ntp);
|
||
server->ntp = c;
|
||
server->n_ntp = n;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
int sd_dhcp_server_set_emit_router(sd_dhcp_server *server, int enabled) {
|
||
assert_return(server, -EINVAL);
|
||
|
||
if (enabled == server->emit_router)
|
||
return 0;
|
||
|
||
server->emit_router = enabled;
|
||
|
||
return 1;
|
||
}
|