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busybox/networking/udhcpc.c
Glenn L McGrath 192ff35d9c Remove empty loops
2002-08-23 14:36:59 +00:00

1601 lines
40 KiB
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/* dhcpd.c
*
* udhcp DHCP client
*
* Russ Dill <Russ.Dill@asu.edu> July 2001
*
* Converted to busybox by Glenn McGrath August 2002
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/file.h>
#include <unistd.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <time.h>
#include <string.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <sys/types.h>
#include <sys/wait.h>
#if __GLIBC__ >=2 && __GLIBC_MINOR >= 1
#include <netpacket/packet.h>
#include <net/ethernet.h>
#else
#include <asm/types.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#endif
#include "libbb.h"
static int state;
static unsigned long requested_ip; /* = 0 */
static unsigned long server_addr;
static unsigned long timeout;
static int packet_num; /* = 0 */
static int fd_main;
/* #define DEBUG */
#define VERSION "0.9.7"
#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static int listen_mode;
#define DEFAULT_SCRIPT "/usr/share/udhcpc/default.script"
#define DHCP_END 0xFF
#define TYPE_MASK 0x0F
#define BROADCAST_FLAG 0x8000
#define SERVER_PORT 67
#define DHCP_MAGIC 0x63825363
#define BOOTREQUEST 1
#define BOOTREPLY 2
#define ETH_10MB 1
#define ETH_10MB_LEN 6
#define OPTION_FIELD 0
#define FILE_FIELD 1
#define SNAME_FIELD 2
#define INIT_SELECTING 0
#define REQUESTING 1
#define BOUND 2
#define RENEWING 3
#define REBINDING 4
#define INIT_REBOOT 5
#define RENEW_REQUESTED 6
#define RELEASED 7
#define CLIENT_PORT 68
#define DHCPDISCOVER 1
#define DHCPOFFER 2
#define DHCPREQUEST 3
#define DHCPDECLINE 4
#define DHCPACK 5
#define DHCPNAK 6
#define DHCPRELEASE 7
#define DHCPINFORM 8
/* DHCP option codes (partial list) */
#define DHCP_PADDING 0x00
#define DHCP_SUBNET 0x01
#define DHCP_TIME_OFFSET 0x02
#define DHCP_ROUTER 0x03
#define DHCP_TIME_SERVER 0x04
#define DHCP_NAME_SERVER 0x05
#define DHCP_DNS_SERVER 0x06
#define DHCP_LOG_SERVER 0x07
#define DHCP_COOKIE_SERVER 0x08
#define DHCP_LPR_SERVER 0x09
#define DHCP_HOST_NAME 0x0c
#define DHCP_BOOT_SIZE 0x0d
#define DHCP_DOMAIN_NAME 0x0f
#define DHCP_SWAP_SERVER 0x10
#define DHCP_ROOT_PATH 0x11
#define DHCP_IP_TTL 0x17
#define DHCP_MTU 0x1a
#define DHCP_BROADCAST 0x1c
#define DHCP_NTP_SERVER 0x2a
#define DHCP_WINS_SERVER 0x2c
#define DHCP_REQUESTED_IP 0x32
#define DHCP_LEASE_TIME 0x33
#define DHCP_OPTION_OVER 0x34
#define DHCP_MESSAGE_TYPE 0x35
#define DHCP_SERVER_ID 0x36
#define DHCP_PARAM_REQ 0x37
#define DHCP_MESSAGE 0x38
#define DHCP_MAX_SIZE 0x39
#define DHCP_T1 0x3a
#define DHCP_T2 0x3b
#define DHCP_VENDOR 0x3c
#define DHCP_CLIENT_ID 0x3d
/* miscellaneous defines */
#define MAC_BCAST_ADDR (unsigned char *) "\xff\xff\xff\xff\xff\xff"
#define OPT_CODE 0
#define OPT_LEN 1
#define OPT_DATA 2
enum {
OPTION_IP = 1,
OPTION_IP_PAIR,
OPTION_STRING,
OPTION_BOOLEAN,
OPTION_U8,
OPTION_U16,
OPTION_S16,
OPTION_U32,
OPTION_S32
};
#define OPTION_REQ 0x10 /* have the client request this option */
#define OPTION_LIST 0x20 /* There can be a list of 1 or more of these */
#ifdef SYSLOG
# define LOG(level, str, args...) do { printf(str, ## args); \
printf("\n"); \
syslog(level, str, ## args); } while(0)
# define OPEN_LOG(name) openlog(name, 0, 0)
# define CLOSE_LOG() closelog()
#else
# define LOG_EMERG "EMERGENCY!"
# define LOG_ALERT "ALERT!"
# define LOG_CRIT "critical!"
# define LOG_WARNING "warning"
# define LOG_ERR "error"
# define LOG_INFO "info"
# define LOG_DEBUG "debug"
# define LOG(level, str, args...) do { printf("%s, " str "\n", level, ## args); } while(0)
# define OPEN_LOG(name)
# define CLOSE_LOG()
#endif
#ifdef DEBUG
# undef DEBUG
# define DEBUG(level, str, args...) LOG(level, str, ## args)
# define DEBUGGING
#else
# define DEBUG(level, str, args...)
#endif
struct dhcpMessage {
u_int8_t op;
u_int8_t htype;
u_int8_t hlen;
u_int8_t hops;
u_int32_t xid;
u_int16_t secs;
u_int16_t flags;
u_int32_t ciaddr;
u_int32_t yiaddr;
u_int32_t siaddr;
u_int32_t giaddr;
u_int8_t chaddr[16];
u_int8_t sname[64];
u_int8_t file[128];
u_int32_t cookie;
u_int8_t options[308]; /* 312 - cookie */
};
struct client_config_t {
char foreground; /* Do not fork */
char quit_after_lease; /* Quit after obtaining lease */
char abort_if_no_lease; /* Abort if no lease */
char *interface; /* The name of the interface to use */
char *pidfile; /* Optionally store the process ID */
char *script; /* User script to run at dhcp events */
unsigned char *clientid; /* Optional client id to use */
unsigned char *hostname; /* Optional hostname to use */
int ifindex; /* Index number of the interface to use */
unsigned char arp[6]; /* Our arp address */
};
struct client_config_t client_config = {
/* Default options. */
abort_if_no_lease:0,
foreground:0,
quit_after_lease:0,
interface:"eth0",
pidfile:NULL,
script:DEFAULT_SCRIPT,
clientid:NULL,
hostname:NULL,
ifindex:0,
arp:"\0\0\0\0\0\0", /* appease gcc-3.0 */
};
struct dhcp_option {
char name[10];
char flags;
unsigned char code;
};
struct udp_dhcp_packet {
struct iphdr ip;
struct udphdr udp;
struct dhcpMessage data;
};
static const struct dhcp_option options[] = {
/* name[10] flags code */
{"subnet", OPTION_IP | OPTION_REQ, 0x01},
{"timezone", OPTION_S32, 0x02},
{"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03},
{"timesvr", OPTION_IP | OPTION_LIST, 0x04},
{"namesvr", OPTION_IP | OPTION_LIST, 0x05},
{"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06},
{"logsvr", OPTION_IP | OPTION_LIST, 0x07},
{"cookiesvr", OPTION_IP | OPTION_LIST, 0x08},
{"lprsvr", OPTION_IP | OPTION_LIST, 0x09},
{"hostname", OPTION_STRING | OPTION_REQ, 0x0c},
{"bootsize", OPTION_U16, 0x0d},
{"domain", OPTION_STRING | OPTION_REQ, 0x0f},
{"swapsvr", OPTION_IP, 0x10},
{"rootpath", OPTION_STRING, 0x11},
{"ipttl", OPTION_U8, 0x17},
{"mtu", OPTION_U16, 0x1a},
{"broadcast", OPTION_IP | OPTION_REQ, 0x1c},
{"ntpsrv", OPTION_IP | OPTION_LIST, 0x2a},
{"wins", OPTION_IP | OPTION_LIST, 0x2c},
{"requestip", OPTION_IP, 0x32},
{"lease", OPTION_U32, 0x33},
{"dhcptype", OPTION_U8, 0x35},
{"serverid", OPTION_IP, 0x36},
{"message", OPTION_STRING, 0x38},
{"tftp", OPTION_STRING, 0x42},
{"bootfile", OPTION_STRING, 0x43},
{"", 0x00, 0x00}
};
/* Lengths of the different option types */
static const unsigned char option_lengths[] = {
[OPTION_IP] = 4,
[OPTION_IP_PAIR] = 8,
[OPTION_BOOLEAN] = 1,
[OPTION_STRING] = 1,
[OPTION_U8] = 1,
[OPTION_U16] = 2,
[OPTION_S16] = 2,
[OPTION_U32] = 4,
[OPTION_S32] = 4
};
/* get a rough idea of how long an option will be (rounding up...) */
static const unsigned char max_option_length[] = {
[OPTION_IP] = sizeof("255.255.255.255 "),
[OPTION_IP_PAIR] = sizeof("255.255.255.255 ") * 2,
[OPTION_STRING] = 1,
[OPTION_BOOLEAN] = sizeof("yes "),
[OPTION_U8] = sizeof("255 "),
[OPTION_U16] = sizeof("65535 "),
[OPTION_S16] = sizeof("-32768 "),
[OPTION_U32] = sizeof("4294967295 "),
[OPTION_S32] = sizeof("-2147483684 "),
};
/* return the position of the 'end' option (no bounds checking) */
static int end_option(unsigned char *optionptr)
{
int i = 0;
while (optionptr[i] != DHCP_END) {
if (optionptr[i] == DHCP_PADDING)
i++;
else
i += optionptr[i + OPT_LEN] + 2;
}
return i;
}
/* add an option string to the options (an option string contains an option code,
* length, then data) */
static int add_option_string(unsigned char *optionptr, unsigned char *string)
{
int end = end_option(optionptr);
/* end position + string length + option code/length + end option */
if (end + string[OPT_LEN] + 2 + 1 >= 308) {
LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!",
string[OPT_CODE]);
return 0;
}
DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]);
memcpy(optionptr + end, string, string[OPT_LEN] + 2);
optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
return string[OPT_LEN] + 2;
}
/* add a one to four byte option to a packet */
static int add_simple_option(unsigned char *optionptr, unsigned char code,
u_int32_t data)
{
char length = 0;
int i;
unsigned char option[2 + 4];
unsigned char *u8;
u_int16_t *u16;
u_int32_t *u32;
u_int32_t aligned;
u8 = (unsigned char *) &aligned;
u16 = (u_int16_t *) & aligned;
u32 = &aligned;
for (i = 0; options[i].code; i++)
if (options[i].code == code) {
length = option_lengths[options[i].flags & TYPE_MASK];
}
if (!length) {
DEBUG(LOG_ERR, "Could not add option 0x%02x", code);
return 0;
}
option[OPT_CODE] = code;
option[OPT_LEN] = length;
switch (length) {
case 1:
*u8 = data;
break;
case 2:
*u16 = data;
break;
case 4:
*u32 = data;
break;
}
memcpy(option + 2, &aligned, length);
return add_option_string(optionptr, option);
}
static u_int16_t checksum(void *addr, int count)
{
/* Compute Internet Checksum for "count" bytes
* beginning at location "addr".
*/
register int32_t sum = 0;
u_int16_t *source = (u_int16_t *) addr;
while (count > 1) {
/* This is the inner loop */
sum += *source++;
count -= 2;
}
/* Add left-over byte, if any */
if (count > 0) {
sum += *(unsigned char *) source;
}
/* Fold 32-bit sum to 16 bits */
while (sum >> 16) {
sum = (sum & 0xffff) + (sum >> 16);
}
return ~sum;
}
/* Constuct a ip/udp header for a packet, and specify the source and dest hardware address */
static int raw_packet(struct dhcpMessage *payload, u_int32_t source_ip,
int source_port, u_int32_t dest_ip, int dest_port,
unsigned char *dest_arp, int ifindex)
{
int l_fd;
int result;
struct sockaddr_ll dest;
struct udp_dhcp_packet packet;
if ((l_fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) {
DEBUG(LOG_ERR, "socket call failed: %s", sys_errlist[errno]);
return -1;
}
memset(&dest, 0, sizeof(dest));
memset(&packet, 0, sizeof(packet));
dest.sll_family = AF_PACKET;
dest.sll_protocol = htons(ETH_P_IP);
dest.sll_ifindex = ifindex;
dest.sll_halen = 6;
memcpy(dest.sll_addr, dest_arp, 6);
if (bind(l_fd, (struct sockaddr *) &dest, sizeof(struct sockaddr_ll)) < 0) {
DEBUG(LOG_ERR, "bind call failed: %s", sys_errlist[errno]);
close(l_fd);
return -1;
}
packet.ip.protocol = IPPROTO_UDP;
packet.ip.saddr = source_ip;
packet.ip.daddr = dest_ip;
packet.udp.source = htons(source_port);
packet.udp.dest = htons(dest_port);
packet.udp.len = htons(sizeof(packet.udp) + sizeof(struct dhcpMessage)); /* cheat on the psuedo-header */
packet.ip.tot_len = packet.udp.len;
memcpy(&(packet.data), payload, sizeof(struct dhcpMessage));
packet.udp.check = checksum(&packet, sizeof(struct udp_dhcp_packet));
packet.ip.tot_len = htons(sizeof(struct udp_dhcp_packet));
packet.ip.ihl = sizeof(packet.ip) >> 2;
packet.ip.version = IPVERSION;
packet.ip.ttl = IPDEFTTL;
packet.ip.check = checksum(&(packet.ip), sizeof(packet.ip));
result =
sendto(l_fd, &packet, sizeof(struct udp_dhcp_packet), 0,
(struct sockaddr *) &dest, sizeof(dest));
if (result <= 0) {
DEBUG(LOG_ERR, "write on socket failed: %s", sys_errlist[errno]);
}
close(l_fd);
return result;
}
/* Let the kernel do all the work for packet generation */
static int kernel_packet(struct dhcpMessage *payload, u_int32_t source_ip,
int source_port, u_int32_t dest_ip, int dest_port)
{
int n = 1;
int l_fd, result;
struct sockaddr_in client;
if ((l_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
return -1;
}
if (setsockopt(l_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &n, sizeof(n)) ==
-1) {
return -1;
}
memset(&client, 0, sizeof(client));
client.sin_family = AF_INET;
client.sin_port = htons(source_port);
client.sin_addr.s_addr = source_ip;
if (bind(l_fd, (struct sockaddr *) &client, sizeof(struct sockaddr)) ==
-1) {
return -1;
}
memset(&client, 0, sizeof(client));
client.sin_family = AF_INET;
client.sin_port = htons(dest_port);
client.sin_addr.s_addr = dest_ip;
if (connect(l_fd, (struct sockaddr *) &client, sizeof(struct sockaddr)) ==
-1) {
return -1;
}
result = write(l_fd, payload, sizeof(struct dhcpMessage));
close(l_fd);
return result;
}
/* initialize a packet with the proper defaults */
static void init_packet(struct dhcpMessage *packet, char type)
{
struct vendor {
char vendor, length;
char str[sizeof("udhcp " VERSION)];
}
vendor_id = {
DHCP_VENDOR, sizeof("udhcp " VERSION) - 1, "udhcp " VERSION};
memset(packet, 0, sizeof(struct dhcpMessage));
switch (type) {
case DHCPDISCOVER:
case DHCPREQUEST:
case DHCPRELEASE:
case DHCPINFORM:
packet->op = BOOTREQUEST;
break;
case DHCPOFFER:
case DHCPACK:
case DHCPNAK:
packet->op = BOOTREPLY;
}
packet->htype = ETH_10MB;
packet->hlen = ETH_10MB_LEN;
packet->cookie = htonl(DHCP_MAGIC);
packet->options[0] = DHCP_END;
add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
memcpy(packet->chaddr, client_config.arp, 6);
add_option_string(packet->options, client_config.clientid);
if (client_config.hostname) {
add_option_string(packet->options, client_config.hostname);
}
add_option_string(packet->options, (unsigned char *) &vendor_id);
}
/* Add a paramater request list for stubborn DHCP servers. Pull the data
* from the struct in options.c. Don't do bounds checking here because it
* goes towards the head of the packet. */
static void add_requests(struct dhcpMessage *packet)
{
int end = end_option(packet->options);
int i, len = 0;
packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
for (i = 0; options[i].code; i++) {
if (options[i].flags & OPTION_REQ) {
packet->options[end + OPT_DATA + len++] = options[i].code;
}
}
packet->options[end + OPT_LEN] = len;
packet->options[end + OPT_DATA + len] = DHCP_END;
}
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
static inline int send_discover(unsigned long xid, unsigned long requested)
{
struct dhcpMessage packet;
init_packet(&packet, DHCPDISCOVER);
packet.xid = xid;
if (requested) {
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
}
add_requests(&packet);
DEBUG(LOG_DEBUG, "Sending discover...");
return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
/* Broadcasts a DHCP request message */
static inline int send_selecting(unsigned long xid, unsigned long server,
unsigned long requested)
{
struct dhcpMessage packet;
struct in_addr addr;
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
add_simple_option(packet.options, DHCP_SERVER_ID, server);
add_requests(&packet);
addr.s_addr = requested;
DEBUG(LOG_DEBUG, "Sending select for %s...", inet_ntoa(addr));
return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
/* Unicasts or broadcasts a DHCP renew message */
static int send_renew(unsigned long xid, unsigned long server,
unsigned long ciaddr)
{
struct dhcpMessage packet;
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
packet.ciaddr = ciaddr;
add_requests(&packet);
DEBUG(LOG_DEBUG, "Sending renew...");
if (server) {
return kernel_packet(&packet, ciaddr, CLIENT_PORT, server,
SERVER_PORT);
}
return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
/* Create a random xid */
static unsigned long random_xid(void)
{
static int initialized;
if (!initialized) {
srand(time(0));
initialized++;
}
return rand();
}
/* just a little helper */
static void change_mode(int new_mode)
{
DEBUG(LOG_INFO, "entering %s listen mode",
new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
close(fd_main);
fd_main = -1;
listen_mode = new_mode;
}
/* SIGUSR1 handler (renew) */
static void renew_requested(int sig)
{
sig = 0;
LOG(LOG_INFO, "Received SIGUSR1");
if (state == BOUND || state == RENEWING || state == REBINDING ||
state == RELEASED) {
change_mode(LISTEN_KERNEL);
packet_num = 0;
state = RENEW_REQUESTED;
}
if (state == RELEASED) {
change_mode(LISTEN_RAW);
state = INIT_SELECTING;
}
/* Kill any timeouts because the user wants this to hurry along */
timeout = 0;
}
/* get an option with bounds checking (warning, not aligned). */
static unsigned char *get_option(struct dhcpMessage *packet, int code)
{
int i, length;
unsigned char *optionptr;
int over = 0, done = 0, curr = OPTION_FIELD;
optionptr = packet->options;
i = 0;
length = 308;
while (!done) {
if (i >= length) {
LOG(LOG_WARNING, "bogus packet, option fields too long.");
return NULL;
}
if (optionptr[i + OPT_CODE] == code) {
if (i + 1 + optionptr[i + OPT_LEN] >= length) {
LOG(LOG_WARNING, "bogus packet, option fields too long.");
return NULL;
}
return optionptr + i + 2;
}
switch (optionptr[i + OPT_CODE]) {
case DHCP_PADDING:
i++;
break;
case DHCP_OPTION_OVER:
if (i + 1 + optionptr[i + OPT_LEN] >= length) {
LOG(LOG_WARNING, "bogus packet, option fields too long.");
return NULL;
}
over = optionptr[i + 3];
i += optionptr[OPT_LEN] + 2;
break;
case DHCP_END:
if (curr == OPTION_FIELD && over & FILE_FIELD) {
optionptr = packet->file;
i = 0;
length = 128;
curr = FILE_FIELD;
} else if (curr == FILE_FIELD && over & SNAME_FIELD) {
optionptr = packet->sname;
i = 0;
length = 64;
curr = SNAME_FIELD;
} else {
done = 1;
}
break;
default:
i += optionptr[OPT_LEN + i] + 2;
}
}
return NULL;
}
static int sprintip(char *dest, char *pre, unsigned char *ip)
{
return sprintf(dest, "%s%d.%d.%d.%d ", pre, ip[0], ip[1], ip[2], ip[3]);
}
/* Fill dest with the text of option 'option'. */
static inline void fill_options(char *dest, unsigned char *option,
const struct dhcp_option *type_p)
{
int type, optlen;
u_int16_t val_u16;
int16_t val_s16;
u_int32_t val_u32;
int32_t val_s32;
int len = option[OPT_LEN - 2];
dest += sprintf(dest, "%s=", type_p->name);
type = type_p->flags & TYPE_MASK;
optlen = option_lengths[type];
for (;;) {
switch (type) {
case OPTION_IP_PAIR:
dest += sprintip(dest, "", option);
*(dest++) = '/';
option += 4;
optlen = 4;
case OPTION_IP: /* Works regardless of host byte order. */
dest += sprintip(dest, "", option);
break;
case OPTION_BOOLEAN:
dest += sprintf(dest, *option ? "yes " : "no ");
break;
case OPTION_U8:
dest += sprintf(dest, "%u ", *option);
break;
case OPTION_U16:
memcpy(&val_u16, option, 2);
dest += sprintf(dest, "%u ", ntohs(val_u16));
break;
case OPTION_S16:
memcpy(&val_s16, option, 2);
dest += sprintf(dest, "%d ", ntohs(val_s16));
break;
case OPTION_U32:
memcpy(&val_u32, option, 4);
dest += sprintf(dest, "%lu ", (unsigned long) ntohl(val_u32));
break;
case OPTION_S32:
memcpy(&val_s32, option, 4);
dest += sprintf(dest, "%ld ", (long) ntohl(val_s32));
break;
case OPTION_STRING:
memcpy(dest, option, len);
dest[len] = '\0';
return; /* Short circuit this case */
}
option += optlen;
len -= optlen;
if (len <= 0) {
break;
}
}
}
static char *find_env(const char *prefix, char *defaultstr)
{
extern char **environ;
char **ptr;
const int len = strlen(prefix);
for (ptr = environ; *ptr != NULL; ptr++) {
if (strncmp(prefix, *ptr, len) == 0) {
return *ptr;
}
}
return defaultstr;
}
/* put all the paramaters into an environment */
static char **fill_envp(struct dhcpMessage *packet)
{
/* supported options are easily added here */
int num_options = 0;
int i, j;
char **envp;
unsigned char *temp;
char over = 0;
if (packet == NULL) {
num_options = 0;
} else {
for (i = 0; options[i].code; i++) {
if (get_option(packet, options[i].code)) {
num_options++;
}
}
if (packet->siaddr) {
num_options++;
}
if ((temp = get_option(packet, DHCP_OPTION_OVER))) {
over = *temp;
}
if (!(over & FILE_FIELD) && packet->file[0]) {
num_options++;
}
if (!(over & SNAME_FIELD) && packet->sname[0]) {
num_options++;
}
}
envp = xmalloc((num_options + 5) * sizeof(char *));
envp[0] = xmalloc(sizeof("interface=") + strlen(client_config.interface));
sprintf(envp[0], "interface=%s", client_config.interface);
envp[1] = find_env("PATH", "PATH=/bin:/usr/bin:/sbin:/usr/sbin");
envp[2] = find_env("HOME", "HOME=/");
if (packet == NULL) {
envp[3] = NULL;
return envp;
}
envp[3] = xmalloc(sizeof("ip=255.255.255.255"));
sprintip(envp[3], "ip=", (unsigned char *) &packet->yiaddr);
for (i = 0, j = 4; options[i].code; i++) {
if ((temp = get_option(packet, options[i].code))) {
envp[j] =
xmalloc(max_option_length[(&options[i])->flags & TYPE_MASK] *
(temp[OPT_LEN - 2] /
option_lengths[(&options[i])->flags & TYPE_MASK]) +
strlen((&options[i])->name) + 2);
fill_options(envp[j], temp, &options[i]);
j++;
}
}
if (packet->siaddr) {
envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
sprintip(envp[j++], "siaddr=", (unsigned char *) &packet->yiaddr);
}
if (!(over & FILE_FIELD) && packet->file[0]) {
/* watch out for invalid packets */
packet->file[sizeof(packet->file) - 1] = '\0';
envp[j] = xmalloc(sizeof("boot_file=") + strlen(packet->file));
sprintf(envp[j++], "boot_file=%s", packet->file);
}
if (!(over & SNAME_FIELD) && packet->sname[0]) {
/* watch out for invalid packets */
packet->sname[sizeof(packet->sname) - 1] = '\0';
envp[j] = xmalloc(sizeof("sname=") + strlen(packet->sname));
sprintf(envp[j++], "sname=%s", packet->sname);
}
envp[j] = NULL;
return envp;
}
/* Call a script with a par file and env vars */
static void run_script(struct dhcpMessage *packet, const char *name)
{
int pid;
char **envp;
if (client_config.script == NULL) {
return;
}
/* call script */
pid = fork();
if (pid) {
waitpid(pid, NULL, 0);
return;
} else if (pid == 0) {
envp = fill_envp(packet);
/* close fd's? */
/* exec script */
DEBUG(LOG_INFO, "execle'ing %s", client_config.script);
execle(client_config.script, client_config.script, name, NULL, envp);
LOG(LOG_ERR, "script %s failed: %s",
client_config.script, sys_errlist[errno]);
exit(1);
}
}
/* SIGUSR2 handler (release) */
static void release_requested(int sig)
{
sig = 0;
LOG(LOG_INFO, "Received SIGUSR2");
/* send release packet */
if (state == BOUND || state == RENEWING || state == REBINDING) {
struct dhcpMessage packet;
init_packet(&packet, DHCPRELEASE);
packet.xid = random_xid();
packet.ciaddr = requested_ip;
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested_ip);
add_simple_option(packet.options, DHCP_SERVER_ID, server_addr);
DEBUG(LOG_DEBUG, "Sending release...");
kernel_packet(&packet, requested_ip, CLIENT_PORT, server_addr,
SERVER_PORT);
run_script(NULL, "deconfig");
}
change_mode(LISTEN_NONE);
state = RELEASED;
timeout = 0x7fffffff;
}
static int pidfile_acquire(char *pidfile)
{
int pid_fd;
if (pidfile == NULL) {
return -1;
}
pid_fd = open(pidfile, O_CREAT | O_WRONLY, 0644);
if (pid_fd < 0) {
LOG(LOG_ERR, "Unable to open pidfile %s: %s\n",
pidfile, strerror(errno));
} else {
lockf(pid_fd, F_LOCK, 0);
}
return pid_fd;
}
static void pidfile_write_release(int pid_fd)
{
FILE *out;
if (pid_fd < 0) {
return;
}
if ((out = fdopen(pid_fd, "w")) != NULL) {
fprintf(out, "%d\n", getpid());
fclose(out);
}
lockf(pid_fd, F_UNLCK, 0);
close(pid_fd);
}
/* Exit and cleanup */
static void exit_client(int retval)
{
unlink(client_config.pidfile);
if (client_config.pidfile) {
unlink(client_config.pidfile);
}
CLOSE_LOG();
exit(retval);
}
/* SIGTERM handler */
static void terminate(int sig)
{
sig = 0;
LOG(LOG_INFO, "Received SIGTERM");
exit_client(0);
}
static inline int read_interface(char *interface, int *ifindex,
u_int32_t * addr, unsigned char *arp)
{
int l_fd;
struct ifreq ifr;
struct sockaddr_in *s_in;
memset(&ifr, 0, sizeof(struct ifreq));
if ((l_fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) >= 0) {
ifr.ifr_addr.sa_family = AF_INET;
strcpy(ifr.ifr_name, interface);
if (addr) {
if (ioctl(l_fd, SIOCGIFADDR, &ifr) == 0) {
s_in = (struct sockaddr_in *) &ifr.ifr_addr;
*addr = s_in->sin_addr.s_addr;
DEBUG(LOG_INFO, "%s (our ip) = %s", ifr.ifr_name,
inet_ntoa(s_in->sin_addr));
} else {
LOG(LOG_ERR, "SIOCGIFADDR failed!: %s", sys_errlist[errno]);
return -1;
}
}
if (ioctl(l_fd, SIOCGIFINDEX, &ifr) == 0) {
DEBUG(LOG_INFO, "adapter index %d", ifr.ifr_ifindex);
*ifindex = ifr.ifr_ifindex;
} else {
LOG(LOG_ERR, "SIOCGIFINDEX failed!: %s", sys_errlist[errno]);
return -1;
}
if (ioctl(l_fd, SIOCGIFHWADDR, &ifr) == 0) {
memcpy(arp, ifr.ifr_hwaddr.sa_data, 6);
DEBUG(LOG_INFO,
"adapter hardware address %02x:%02x:%02x:%02x:%02x:%02x",
arp[0], arp[1], arp[2], arp[3], arp[4], arp[5]);
} else {
LOG(LOG_ERR, "SIOCGIFHWADDR failed!: %s", sys_errlist[errno]);
return -1;
}
} else {
LOG(LOG_ERR, "socket failed!: %s", sys_errlist[errno]);
return -1;
}
close(l_fd);
return 0;
}
static inline int listen_socket(unsigned int ip, int port, char *inf)
{
struct ifreq interface;
int l_fd;
struct sockaddr_in addr;
int n = 1;
DEBUG(LOG_INFO, "Opening listen socket on 0x%08x:%d %s\n", ip, port, inf);
if ((l_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
DEBUG(LOG_ERR, "socket call failed: %s", sys_errlist[errno]);
return -1;
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(port);
addr.sin_addr.s_addr = ip;
if (setsockopt(l_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &n, sizeof(n)) ==
-1) {
close(l_fd);
return -1;
}
if (setsockopt(l_fd, SOL_SOCKET, SO_BROADCAST, (char *) &n, sizeof(n)) ==
-1) {
close(l_fd);
return -1;
}
strncpy(interface.ifr_ifrn.ifrn_name, inf, IFNAMSIZ);
if (setsockopt
(l_fd, SOL_SOCKET, SO_BINDTODEVICE, (char *) &interface,
sizeof(interface)) < 0) {
close(l_fd);
return -1;
}
if (bind(l_fd, (struct sockaddr *) &addr, sizeof(struct sockaddr)) == -1) {
close(l_fd);
return -1;
}
return l_fd;
}
static int raw_socket(int ifindex)
{
int l_fd;
struct sockaddr_ll sock;
DEBUG(LOG_INFO, "Opening raw socket on ifindex %d\n", ifindex);
if ((l_fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) {
DEBUG(LOG_ERR, "socket call failed: %s", sys_errlist[errno]);
return -1;
}
sock.sll_family = AF_PACKET;
sock.sll_protocol = htons(ETH_P_IP);
sock.sll_ifindex = ifindex;
if (bind(l_fd, (struct sockaddr *) &sock, sizeof(sock)) < 0) {
DEBUG(LOG_ERR, "bind call failed: %s", sys_errlist[errno]);
close(l_fd);
return -1;
}
return l_fd;
}
/* read a packet from socket fd, return -1 on read error, -2 on packet error */
static int get_packet(struct dhcpMessage *packet, int l_fd)
{
int bytes;
int i;
const char broken_vendors[][8] = {
"MSFT 98",
""
};
char unsigned *vendor;
memset(packet, 0, sizeof(struct dhcpMessage));
bytes = read(l_fd, packet, sizeof(struct dhcpMessage));
if (bytes < 0) {
DEBUG(LOG_INFO, "couldn't read on listening socket, ignoring");
return -1;
}
if (ntohl(packet->cookie) != DHCP_MAGIC) {
LOG(LOG_ERR, "received bogus message, ignoring");
return -2;
}
DEBUG(LOG_INFO, "Received a packet");
if (packet->op == BOOTREQUEST
&& (vendor = get_option(packet, DHCP_VENDOR))) {
for (i = 0; broken_vendors[i][0]; i++) {
if (vendor[OPT_LEN - 2] ==
(unsigned char) strlen(broken_vendors[i])
&& !strncmp(vendor, broken_vendors[i], vendor[OPT_LEN - 2])) {
DEBUG(LOG_INFO, "broken client (%s), forcing broadcast",
broken_vendors[i]);
packet->flags |= htons(BROADCAST_FLAG);
}
}
}
return bytes;
}
static inline int get_raw_packet(struct dhcpMessage *payload, int l_fd)
{
int bytes;
struct udp_dhcp_packet packet;
u_int32_t source, dest;
u_int16_t check;
memset(&packet, 0, sizeof(struct udp_dhcp_packet));
bytes = read(l_fd, &packet, sizeof(struct udp_dhcp_packet));
if (bytes < 0) {
DEBUG(LOG_INFO, "couldn't read on raw listening socket -- ignoring");
usleep(500000); /* possible down interface, looping condition */
return -1;
}
if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) {
DEBUG(LOG_INFO, "message too short, ignoring");
return -1;
}
if (bytes < ntohs(packet.ip.tot_len)) {
DEBUG(LOG_INFO, "Truncated packet");
return -1;
}
/* ignore any extra garbage bytes */
bytes = ntohs(packet.ip.tot_len);
/* Make sure its the right packet for us, and that it passes sanity checks */
if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION ||
packet.ip.ihl != sizeof(packet.ip) >> 2
|| packet.udp.dest != htons(CLIENT_PORT)
|| bytes > (int) sizeof(struct udp_dhcp_packet)
|| ntohs(packet.udp.len) != (short) (bytes - sizeof(packet.ip))) {
DEBUG(LOG_INFO, "unrelated/bogus packet");
return -1;
}
/* check IP checksum */
check = packet.ip.check;
packet.ip.check = 0;
if (check != checksum(&(packet.ip), sizeof(packet.ip))) {
DEBUG(LOG_INFO, "bad IP header checksum, ignoring");
return -1;
}
/* verify the UDP checksum by replacing the header with a psuedo header */
source = packet.ip.saddr;
dest = packet.ip.daddr;
check = packet.udp.check;
packet.udp.check = 0;
memset(&packet.ip, 0, sizeof(packet.ip));
packet.ip.protocol = IPPROTO_UDP;
packet.ip.saddr = source;
packet.ip.daddr = dest;
packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */
if (check && check != checksum(&packet, bytes)) {
DEBUG(LOG_ERR, "packet with bad UDP checksum received, ignoring");
return -1;
}
memcpy(payload, &(packet.data),
bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
if (ntohl(payload->cookie) != DHCP_MAGIC) {
LOG(LOG_ERR, "received bogus message (bad magic) -- ignoring");
return -1;
}
DEBUG(LOG_INFO, "oooooh!!! got some!");
return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
}
int udhcpc_main(int argc, char *argv[])
{
unsigned char *temp, *message;
unsigned long t1 = 0, t2 = 0, xid = 0;
unsigned long start = 0, lease;
fd_set rfds;
int retval;
struct timeval tv;
int c, len;
struct dhcpMessage packet;
struct in_addr temp_addr;
int pid_fd;
time_t now;
static struct option l_options[] = {
{"clientid", required_argument, 0, 'c'},
{"foreground", no_argument, 0, 'f'},
{"hostname", required_argument, 0, 'H'},
{"help", no_argument, 0, 'h'},
{"interface", required_argument, 0, 'i'},
{"now", no_argument, 0, 'n'},
{"pidfile", required_argument, 0, 'p'},
{"quit", no_argument, 0, 'q'},
{"request", required_argument, 0, 'r'},
{"script", required_argument, 0, 's'},
{"version", no_argument, 0, 'v'},
{0, 0, 0, 0}
};
/* get options */
while (1) {
int option_index = 0;
c = getopt_long(argc, argv, "c:fH:hi:np:qr:s:v", l_options,
&option_index);
if (c == -1) {
break;
}
switch (c) {
case 'c':
len = strlen(optarg);
if (len > 255) {
len = 255;
}
if (client_config.clientid) {
free(client_config.clientid);
}
client_config.clientid = xmalloc(len + 2);
client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
client_config.clientid[OPT_LEN] = len;
client_config.clientid[OPT_DATA] = '\0';
strncpy(client_config.clientid + 3, optarg, len - 1);
break;
case 'f':
client_config.foreground = 1;
break;
case 'H':
len = strlen(optarg);
if (len > 255) {
len = 255;
}
if (client_config.hostname) {
free(client_config.hostname);
}
client_config.hostname = xmalloc(len + 2);
client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
client_config.hostname[OPT_LEN] = len;
strncpy(client_config.hostname + 2, optarg, len);
break;
case 'h':
puts("Usage: udhcpcd [OPTIONS]\n\n"
" -c, --clientid=CLIENTID Client identifier\n"
" -H, --hostname=HOSTNAME Client hostname\n"
" -f, --foreground Do not fork after getting lease\n"
" -i, --interface=INTERFACE Interface to use (default: eth0)\n"
" -n, --now Exit with failure if lease cannot be\n"
" immediately negotiated.\n"
" -p, --pidfile=file Store process ID of daemon in file\n"
" -q, --quit Quit after obtaining lease\n"
" -r, --request=IP IP address to request (default: none)\n"
" -s, --script=file Run file at dhcp events (default:\n"
" " DEFAULT_SCRIPT ")\n"
" -v, --version Display version");
return 0;
case 'i':
client_config.interface = optarg;
break;
case 'n':
client_config.abort_if_no_lease = 1;
break;
case 'p':
client_config.pidfile = optarg;
break;
case 'q':
client_config.quit_after_lease = 1;
break;
case 'r':
requested_ip = inet_addr(optarg);
break;
case 's':
client_config.script = optarg;
break;
case 'v':
printf("udhcpcd, version %s\n\n", VERSION);
exit_client(0);
break;
}
}
OPEN_LOG("udhcpc");
LOG(LOG_INFO, "udhcp client (v%s) started", VERSION);
pid_fd = pidfile_acquire(client_config.pidfile);
pidfile_write_release(pid_fd);
if (read_interface
(client_config.interface, &client_config.ifindex, NULL,
client_config.arp) < 0) {
exit_client(1);
}
if (!client_config.clientid) {
client_config.clientid = xmalloc(6 + 3);
client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
client_config.clientid[OPT_LEN] = 7;
client_config.clientid[OPT_DATA] = 1;
memcpy(client_config.clientid + 3, client_config.arp, 6);
}
/* setup signal handlers */
signal(SIGUSR1, renew_requested);
signal(SIGUSR2, release_requested);
signal(SIGTERM, terminate);
state = INIT_SELECTING;
run_script(NULL, "deconfig");
change_mode(LISTEN_RAW);
for (;;) {
tv.tv_sec = timeout - time(0);
tv.tv_usec = 0;
FD_ZERO(&rfds);
if (listen_mode != LISTEN_NONE && fd_main < 0) {
if (listen_mode == LISTEN_KERNEL) {
fd_main =
listen_socket(INADDR_ANY, CLIENT_PORT,
client_config.interface);
} else {
fd_main = raw_socket(client_config.ifindex);
}
if (fd_main < 0) {
LOG(LOG_ERR, "FATAL: couldn't listen on socket, %s",
sys_errlist[errno]);
exit_client(0);
}
}
if (fd_main >= 0) {
FD_SET(fd_main, &rfds);
}
if (tv.tv_sec > 0) {
DEBUG(LOG_INFO, "Waiting on select...\n");
retval = select(fd_main + 1, &rfds, NULL, NULL, &tv);
} else {
retval = 0; /* If we already timed out, fall through */
}
now = time(0);
if (retval == 0) {
/* timeout dropped to zero */
switch (state) {
case INIT_SELECTING:
if (packet_num < 3) {
if (packet_num == 0) {
xid = random_xid();
}
/* send discover packet */
send_discover(xid, requested_ip); /* broadcast */
timeout = now + ((packet_num == 2) ? 10 : 2);
packet_num++;
} else {
if (client_config.abort_if_no_lease) {
LOG(LOG_INFO, "No lease, failing.");
exit_client(1);
}
/* wait to try again */
packet_num = 0;
timeout = now + 60;
}
break;
case RENEW_REQUESTED:
case REQUESTING:
if (packet_num < 3) {
/* send request packet */
if (state == RENEW_REQUESTED) {
send_renew(xid, server_addr, requested_ip); /* unicast */
} else {
send_selecting(xid, server_addr, requested_ip); /* broadcast */
}
timeout = now + ((packet_num == 2) ? 10 : 2);
packet_num++;
} else {
/* timed out, go back to init state */
state = INIT_SELECTING;
timeout = now;
packet_num = 0;
change_mode(LISTEN_RAW);
}
break;
case BOUND:
/* Lease is starting to run out, time to enter renewing state */
state = RENEWING;
change_mode(LISTEN_KERNEL);
DEBUG(LOG_INFO, "Entering renew state");
/* fall right through */
case RENEWING:
/* Either set a new T1, or enter REBINDING state */
if ((t2 - t1) <= (lease / 14400 + 1)) {
/* timed out, enter rebinding state */
state = REBINDING;
timeout = now + (t2 - t1);
DEBUG(LOG_INFO, "Entering rebinding state");
} else {
/* send a request packet */
send_renew(xid, server_addr, requested_ip); /* unicast */
t1 = (t2 - t1) / 2 + t1;
timeout = t1 + start;
}
break;
case REBINDING:
/* Either set a new T2, or enter INIT state */
if ((lease - t2) <= (lease / 14400 + 1)) {
/* timed out, enter init state */
state = INIT_SELECTING;
LOG(LOG_INFO, "Lease lost, entering init state");
run_script(NULL, "deconfig");
timeout = now;
packet_num = 0;
change_mode(LISTEN_RAW);
} else {
/* send a request packet */
send_renew(xid, 0, requested_ip); /* broadcast */
t2 = (lease - t2) / 2 + t2;
timeout = t2 + start;
}
break;
case RELEASED:
/* yah, I know, *you* say it would never happen */
timeout = 0x7fffffff;
break;
}
} else if (retval > 0 && listen_mode != LISTEN_NONE
&& FD_ISSET(fd_main, &rfds)) {
/* a packet is ready, read it */
if (listen_mode == LISTEN_KERNEL) {
len = get_packet(&packet, fd_main);
} else {
len = get_raw_packet(&packet, fd_main);
}
if (len == -1 && errno != EINTR) {
DEBUG(LOG_INFO, "error on read, %s, reopening socket",
sys_errlist[errno]);
change_mode(listen_mode); /* just close and reopen */
}
if (len < 0) {
continue;
}
if (packet.xid != xid) {
DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
(unsigned long) packet.xid, xid);
continue;
}
if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
continue;
}
switch (state) {
case INIT_SELECTING:
/* Must be a DHCPOFFER to one of our xid's */
if (*message == DHCPOFFER) {
if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
memcpy(&server_addr, temp, 4);
xid = packet.xid;
requested_ip = packet.yiaddr;
/* enter requesting state */
state = REQUESTING;
timeout = now;
packet_num = 0;
} else {
DEBUG(LOG_ERR, "No server ID in message");
}
}
break;
case RENEW_REQUESTED:
case REQUESTING:
case RENEWING:
case REBINDING:
if (*message == DHCPACK) {
if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
LOG(LOG_ERR,
"No lease time with ACK, using 1 hour lease");
lease = 60 * 60;
} else {
memcpy(&lease, temp, 4);
lease = ntohl(lease);
}
/* enter bound state */
t1 = lease / 2;
/* little fixed point for n * .875 */
t2 = (lease * 0x7) >> 3;
temp_addr.s_addr = packet.yiaddr;
LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
inet_ntoa(temp_addr), lease);
start = now;
timeout = t1 + start;
requested_ip = packet.yiaddr;
run_script(&packet,
((state == RENEWING
|| state == REBINDING) ? "renew" : "bound"));
state = BOUND;
change_mode(LISTEN_NONE);
{
int pid_fd2;
if (client_config.quit_after_lease) {
exit_client(0);
} else if (!client_config.foreground) {
pid_fd2 = pidfile_acquire(client_config.pidfile); /* hold lock during fork. */
if (daemon(0, 0) == -1) {
perror("fork");
exit_client(1);
}
client_config.foreground = 1; /* Do not fork again. */
pidfile_write_release(pid_fd2);
}
}
} else if (*message == DHCPNAK) {
/* return to init state */
LOG(LOG_INFO, "Received DHCP NAK");
run_script(&packet, "nak");
if (state != REQUESTING) {
run_script(NULL, "deconfig");
}
state = INIT_SELECTING;
timeout = now;
requested_ip = 0;
packet_num = 0;
change_mode(LISTEN_RAW);
sleep(3); /* avoid excessive network traffic */
}
break;
/* case BOUND, RELEASED: - ignore all packets */
}
} else if (retval == -1 && errno == EINTR) {
/* a signal was caught */
} else {
/* An error occured */
DEBUG(LOG_ERR, "Error on select");
}
}
return 0;
}
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