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/***
This file is part of systemd.
Copyright (C) 2013 Intel Corporation. All rights reserved.
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <net/ethernet.h>
#include "util.h"
#include "list.h"
#include "dhcp-protocol.h"
#include "dhcp-internal.h"
#include "sd-dhcp-client.h"
#define DHCP_CLIENT_MIN_OPTIONS_SIZE 312
struct DHCPLease {
uint32_t lifetime;
uint32_t address;
uint32_t server_address;
uint32_t subnet_mask;
uint32_t router;
};
typedef struct DHCPLease DHCPLease;
struct sd_dhcp_client {
DHCPState state;
sd_event *event;
sd_event_source *timeout_resend;
int index;
int fd;
union sockaddr_union link;
sd_event_source *receive_message;
uint8_t *req_opts;
size_t req_opts_size;
uint32_t last_addr;
struct ether_addr mac_addr;
uint32_t xid;
usec_t start_time;
DHCPLease *lease;
};
static const uint8_t default_req_opts[] = {
DHCP_OPTION_SUBNET_MASK,
DHCP_OPTION_ROUTER,
DHCP_OPTION_HOST_NAME,
DHCP_OPTION_DOMAIN_NAME,
DHCP_OPTION_DOMAIN_NAME_SERVER,
DHCP_OPTION_NTP_SERVER,
};
int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option)
{
size_t i;
assert_return(client, -EINVAL);
assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
switch(option) {
case DHCP_OPTION_PAD:
case DHCP_OPTION_OVERLOAD:
case DHCP_OPTION_MESSAGE_TYPE:
case DHCP_OPTION_PARAMETER_REQUEST_LIST:
case DHCP_OPTION_END:
return -EINVAL;
default:
break;
}
for (i = 0; i < client->req_opts_size; i++)
if (client->req_opts[i] == option)
return -EEXIST;
if (!GREEDY_REALLOC(client->req_opts, client->req_opts_size,
client->req_opts_size + 1))
return -ENOMEM;
client->req_opts[client->req_opts_size - 1] = option;
return 0;
}
int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
const struct in_addr *last_addr)
{
assert_return(client, -EINVAL);
assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
if (last_addr)
client->last_addr = last_addr->s_addr;
else
client->last_addr = INADDR_ANY;
return 0;
}
int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index)
{
assert_return(client, -EINVAL);
assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
assert_return(interface_index >= -1, -EINVAL);
client->index = interface_index;
return 0;
}
int sd_dhcp_client_set_mac(sd_dhcp_client *client,
const struct ether_addr *addr)
{
assert_return(client, -EINVAL);
assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
memcpy(&client->mac_addr, addr, ETH_ALEN);
return 0;
}
static int client_stop(sd_dhcp_client *client, int error)
{
assert_return(client, -EINVAL);
assert_return(client->state != DHCP_STATE_INIT &&
client->state != DHCP_STATE_INIT_REBOOT, -EALREADY);
client->receive_message =
sd_event_source_unref(client->receive_message);
if (client->fd >= 0)
close(client->fd);
client->fd = -1;
client->timeout_resend = sd_event_source_unref(client->timeout_resend);
switch (client->state) {
case DHCP_STATE_INIT:
case DHCP_STATE_SELECTING:
client->start_time = 0;
client->state = DHCP_STATE_INIT;
break;
case DHCP_STATE_INIT_REBOOT:
case DHCP_STATE_REBOOTING:
case DHCP_STATE_REQUESTING:
case DHCP_STATE_BOUND:
case DHCP_STATE_RENEWING:
case DHCP_STATE_REBINDING:
break;
}
if (client->lease) {
free(client->lease);
client->lease = NULL;
}
return 0;
}
static int client_packet_init(sd_dhcp_client *client, uint8_t type,
DHCPMessage *message, uint16_t secs,
uint8_t **opt, size_t *optlen)
{
int err;
*opt = (uint8_t *)(message + 1);
if (*optlen < 4)
return -ENOBUFS;
*optlen -= 4;
message->op = BOOTREQUEST;
message->htype = 1;
message->hlen = ETHER_ADDR_LEN;
message->xid = htobe32(client->xid);
/* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
refuse to issue an DHCP lease if 'secs' is set to zero */
message->secs = htobe16(secs);
memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
(*opt)[0] = 0x63;
(*opt)[1] = 0x82;
(*opt)[2] = 0x53;
(*opt)[3] = 0x63;
*opt += 4;
err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
&type);
if (err < 0)
return err;
/* Some DHCP servers will refuse to issue an DHCP lease if the Cliient
Identifier option is not set */
err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
ETH_ALEN, &client->mac_addr);
if (err < 0)
return err;
if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
err = dhcp_option_append(opt, optlen,
DHCP_OPTION_PARAMETER_REQUEST_LIST,
client->req_opts_size,
client->req_opts);
if (err < 0)
return err;
}
return 0;
}
static uint16_t client_checksum(void *buf, int len)
{
uint32_t sum;
uint16_t *check;
int i;
uint8_t *odd;
sum = 0;
check = buf;
for (i = 0; i < len / 2 ; i++)
sum += check[i];
if (len & 0x01) {
odd = buf;
sum += odd[len];
}
return ~((sum & 0xffff) + (sum >> 16));
}
static int client_send_discover(sd_dhcp_client *client, uint16_t secs)
{
int err = 0;
_cleanup_free_ DHCPPacket *discover;
size_t optlen, len;
uint8_t *opt;
optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
len = sizeof(DHCPPacket) + optlen;
discover = malloc0(len);
if (!discover)
return -ENOMEM;
err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
secs, &opt, &optlen);
if (err < 0)
return err;
if (client->last_addr != INADDR_ANY) {
err = dhcp_option_append(&opt, &optlen,
DHCP_OPTION_REQUESTED_IP_ADDRESS,
4, &client->last_addr);
if (err < 0)
return err;
}
err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
if (err < 0)
return err;
discover->ip.version = IPVERSION;
discover->ip.ihl = sizeof(discover->ip) >> 2;
discover->ip.tot_len = htobe16(len);
discover->ip.protocol = IPPROTO_UDP;
discover->ip.saddr = INADDR_ANY;
discover->ip.daddr = INADDR_BROADCAST;
discover->udp.source = htobe16(DHCP_PORT_CLIENT);
discover->udp.dest = htobe16(DHCP_PORT_SERVER);
discover->udp.len = htobe16(len - sizeof(discover->ip));
discover->ip.check = discover->udp.len;
discover->udp.check = client_checksum(&discover->ip.ttl,
len - 8);
discover->ip.ttl = IPDEFTTL;
discover->ip.check = 0;
discover->ip.check = client_checksum(&discover->ip,
sizeof(discover->ip));
err = dhcp_network_send_raw_socket(client->fd, &client->link,
discover, len);
return err;
}
static int client_timeout_resend(sd_event_source *s, uint64_t usec,
void *userdata)
{
sd_dhcp_client *client = userdata;
usec_t next_timeout;
uint16_t secs;
int err = 0;
switch (client->state) {
case DHCP_STATE_INIT:
case DHCP_STATE_SELECTING:
if (!client->start_time)
client->start_time = usec;
secs = (usec - client->start_time) / USEC_PER_SEC;
next_timeout = usec + 2 * USEC_PER_SEC + (random() & 0x1fffff);
err = sd_event_add_monotonic(client->event, next_timeout,
10 * USEC_PER_MSEC,
client_timeout_resend, client,
&client->timeout_resend);
if (err < 0)
goto error;
if (client_send_discover(client, secs) >= 0)
client->state = DHCP_STATE_SELECTING;
break;
case DHCP_STATE_INIT_REBOOT:
case DHCP_STATE_REBOOTING:
case DHCP_STATE_REQUESTING:
case DHCP_STATE_BOUND:
case DHCP_STATE_RENEWING:
case DHCP_STATE_REBINDING:
break;
}
return 0;
error:
client_stop(client, err);
/* Errors were dealt with when stopping the client, don't spill
errors into the event loop handler */
return 0;
}
static int client_parse_offer(uint8_t code, uint8_t len, const uint8_t *option,
void *user_data)
{
DHCPLease *lease = user_data;
be32_t val;
switch(code) {
case DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
if (len == 4) {
memcpy(&val, option, 4);
lease->lifetime = be32toh(val);
}
break;
case DHCP_OPTION_SERVER_IDENTIFIER:
if (len >= 4)
memcpy(&lease->server_address, option, 4);
break;
case DHCP_OPTION_SUBNET_MASK:
if (len >= 4)
memcpy(&lease->subnet_mask, option, 4);
break;
case DHCP_OPTION_ROUTER:
if (len >= 4)
memcpy(&lease->router, option, 4);
break;
}
return 0;
}
static int client_receive_offer(sd_dhcp_client *client, DHCPPacket *offer,
size_t len)
{
size_t hdrlen;
DHCPLease *lease;
if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
return -EINVAL;
hdrlen = offer->ip.ihl * 4;
if (hdrlen < 20 || hdrlen > len || client_checksum(&offer->ip,
hdrlen))
return -EINVAL;
offer->ip.check = offer->udp.len;
offer->ip.ttl = 0;
if (hdrlen + be16toh(offer->udp.len) > len ||
client_checksum(&offer->ip.ttl, be16toh(offer->udp.len) + 12))
return -EINVAL;
if (be16toh(offer->udp.source) != DHCP_PORT_SERVER ||
be16toh(offer->udp.dest) != DHCP_PORT_CLIENT)
return -EINVAL;
if (offer->dhcp.op != BOOTREPLY)
return -EINVAL;
if (be32toh(offer->dhcp.xid) != client->xid)
return -EINVAL;
if (memcmp(&offer->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
ETHER_ADDR_LEN))
return -EINVAL;
lease = new0(DHCPLease, 1);
if (!lease)
return -ENOMEM;
len = len - DHCP_IP_UDP_SIZE;
if (dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
lease) != DHCP_OFFER)
goto error;
lease->address = offer->dhcp.yiaddr;
if (lease->address == INADDR_ANY ||
lease->server_address == INADDR_ANY ||
lease->subnet_mask == INADDR_ANY ||
lease->lifetime == 0)
goto error;
client->lease = lease;
return 0;
error:
free(lease);
return -ENOMSG;
}
static int client_receive_raw_message(sd_event_source *s, int fd,
uint32_t revents, void *userdata)
{
sd_dhcp_client *client = userdata;
uint8_t buf[sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE];
int buflen = sizeof(buf);
int len;
DHCPPacket *message;
len = read(fd, &buf, buflen);
if (len < 0)
goto error;
message = (DHCPPacket *)&buf;
switch (client->state) {
case DHCP_STATE_SELECTING:
if (client_receive_offer(client, message, len) >= 0) {
client->receive_message =
sd_event_source_unref(client->receive_message);
close(client->fd);
client->fd = -1;
client->timeout_resend =
sd_event_source_unref(client->timeout_resend);
client->state = DHCP_STATE_REQUESTING;
}
break;
case DHCP_STATE_INIT:
case DHCP_STATE_INIT_REBOOT:
case DHCP_STATE_REBOOTING:
case DHCP_STATE_REQUESTING:
case DHCP_STATE_BOUND:
case DHCP_STATE_RENEWING:
case DHCP_STATE_REBINDING:
break;
}
error:
return 0;
}
int sd_dhcp_client_start(sd_dhcp_client *client)
{
int err;
assert_return(client, -EINVAL);
assert_return(client->index >= 0, -EINVAL);
assert_return(client->state == DHCP_STATE_INIT ||
client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
client->xid = random_u();
client->fd = dhcp_network_bind_raw_socket(client->index,
&client->link);
if (client->fd < 0) {
err = client->fd;
goto error;
}
err = sd_event_add_io(client->event, client->fd, EPOLLIN,
client_receive_raw_message, client,
&client->receive_message);
if (err < 0)
goto error;
err = sd_event_add_monotonic(client->event, now(CLOCK_MONOTONIC), 0,
client_timeout_resend, client,
&client->timeout_resend);
if (err < 0)
goto error;
return 0;
error:
client_stop(client, err);
return err;
}
int sd_dhcp_client_stop(sd_dhcp_client *client)
{
return client_stop(client, 0);
}
sd_dhcp_client *sd_dhcp_client_new(sd_event *event)
{
sd_dhcp_client *client;
assert_return(event, NULL);
client = new0(sd_dhcp_client, 1);
if (!client)
return NULL;
client->event = sd_event_ref(event);
client->state = DHCP_STATE_INIT;
client->index = -1;
client->fd = -1;
client->req_opts_size = ELEMENTSOF(default_req_opts);
client->req_opts = memdup(default_req_opts, client->req_opts_size);
if (!client->req_opts) {
free(client);
return NULL;
}
return client;
}
|