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zircon-guest / third_party / toybox / 137ac1f8000b1c50b2485912de6e8f553a498230 / . / toys / pending / dhcpd.c
blob: 1426c69ed06f905a8abab2220f983d16712cc0b8 [file] [log] [blame]
/* dhcpd.c - DHCP server for dynamic network configuration.
*
* Copyright 2013 Madhur Verma <mad.flexi@gmail.com>
* Copyright 2013 Kyungwan Han <asura321@gamil.com>
*
* No Standard
USE_DHCPD(NEWTOY(dhcpd, ">1P#<0>65535=67fi:S", TOYFLAG_SBIN|TOYFLAG_ROOTONLY))
config DHCPD
bool "dhcpd"
default n
help
usage: dhcpd [-fS] [-i IFACE] [-P N] [CONFFILE]
-f Run in foreground
-i Interface to use
-S Log to syslog too
-P N Use port N (default 67)
config DEBUG_DHCP
bool "debugging messeges ON/OFF"
default n
depends on DHCPD
*/
#define FOR_dhcpd
#include "toys.h"
#include <linux/sockios.h>
#include <linux/if_ether.h>
// Todo: headers not in posix
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <netpacket/packet.h>
#if CFG_DEBUG_DHCP==1
# define dbg(fmt, arg...) printf(fmt, ##arg)
#else
# define dbg(fmt, arg...)
#endif
#define flag_get(f,v,d) ((toys.optflags & (f)) ? (v) : (d))
#define flag_chk(f) ((toys.optflags & (f)) ? 1 : 0)
#define LOG_SILENT 0x0
#define LOG_CONSOLE 0x1
#define LOG_SYSTEM 0x2
#define DHCP_MAGIC 0x63825363
#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 DHCP_NUM8 (1<<8)
#define DHCP_NUM16 (1<<9)
#define DHCP_NUM32 DHCP_NUM16 | DHCP_NUM8
#define DHCP_STRING (1<<10)
#define DHCP_STRLST (1<<11)
#define DHCP_IP (1<<12)
#define DHCP_IPLIST (1<<13)
#define DHCP_IPPLST (1<<14)
#define DHCP_STCRTS (1<<15)
// DHCP option codes (partial list). See RFC 2132 and
#define DHCP_OPT_PADDING 0x00
#define DHCP_OPT_HOST_NAME DHCP_STRING | 0x0c // either client informs server or server gives name to client
#define DHCP_OPT_REQUESTED_IP DHCP_IP | 0x32 // sent by client if specific IP is wanted
#define DHCP_OPT_LEASE_TIME DHCP_NUM32 | 0x33
#define DHCP_OPT_OPTION_OVERLOAD 0x34
#define DHCP_OPT_MESSAGE_TYPE DHCP_NUM8 | 0x35
#define DHCP_OPT_SERVER_ID DHCP_IP | 0x36 // by default server's IP
#define DHCP_OPT_PARAM_REQ DHCP_STRING | 0x37 // list of options client wants
#define DHCP_OPT_END 0xff
GLOBALS(
char *iface;
long port;
);
typedef struct __attribute__((packed)) dhcp_msg_s {
uint8_t op;
uint8_t htype;
uint8_t hlen;
uint8_t hops;
uint32_t xid;
uint16_t secs;
uint16_t flags;
uint32_t ciaddr;
uint32_t yiaddr;
uint32_t nsiaddr;
uint32_t ngiaddr;
uint8_t chaddr[16];
uint8_t sname[64];
uint8_t file[128];
uint32_t cookie;
uint8_t options[308];
} dhcp_msg_t;
typedef struct __attribute__((packed)) dhcp_raw_s {
struct iphdr iph;
struct udphdr udph;
dhcp_msg_t dhcp;
} dhcp_raw_t;
typedef struct static_lease_s {
struct static_lease_s *next;
uint32_t nip;
int mac[6];
} static_lease;
typedef struct {
uint32_t expires;
uint32_t lease_nip;
uint8_t lease_mac[6];
char hostname[20];
uint8_t pad[2];
} dyn_lease;
typedef struct option_val_s {
char *key;
uint16_t code;
void *val;
size_t len;
} option_val_t;
typedef struct __attribute__((__may_alias__)) server_config_s {
char *interface; // interface to use
int ifindex;
uint32_t server_nip;
uint32_t port;
uint8_t server_mac[6]; // our MAC address (used only for ARP probing)
void *options[256]; // list of DHCP options loaded from the config file
/* start,end are in host order: we need to compare start <= ip <= end*/
uint32_t start_ip; // start address of leases, in host order
uint32_t end_ip; // end of leases, in host order
uint32_t max_lease_sec; // maximum lease time (host order)
uint32_t min_lease_sec; // minimum lease time a client can request
uint32_t max_leases; // maximum number of leases (including reserved addresses)
uint32_t auto_time; // how long should dhcpd wait before writing a config file.
// if this is zero, it will only write one on SIGUSR1
uint32_t decline_time; // how long an address is reserved if a client returns a
// decline message
uint32_t conflict_time; // how long an arp conflict offender is leased for
uint32_t offer_time; // how long an offered address is reserved
uint32_t siaddr_nip; // "next server" bootp option
char *lease_file;
char *pidfile;
char *notify_file; // what to run whenever leases are written
char *sname; // bootp server name
char *boot_file; // bootp boot file option
struct static_lease *static_leases; // List of ip/mac pairs to assign static leases
} server_config_t;
typedef struct __attribute__((__may_alias__)) server_state_s {
uint8_t rqcode;
int listensock;
dhcp_msg_t rcvd_pkt;
uint8_t* rqopt;
dhcp_msg_t send_pkt;
static_lease *sleases;
struct arg_list *dleases;
} server_state_t;
struct config_keyword {
char *keyword;
int (*handler)(const char *str, void *var);
void *var;
char *def;
};
static option_val_t options_list[] = {
{"lease" , DHCP_NUM32 | 0x33, NULL, 0},
{"subnet" , DHCP_IP | 0x01, NULL, 0},
{"broadcast" , DHCP_IP | 0x1c, NULL, 0},
{"router" , DHCP_IP | 0x03, NULL, 0},
{"ipttl" , DHCP_NUM8 | 0x17, NULL, 0},
{"mtu" , DHCP_NUM16 | 0x1a, NULL, 0},
{"hostname" , DHCP_STRING | 0x0c, NULL, 0},
{"domain" , DHCP_STRING | 0x0f, NULL, 0},
{"search" , DHCP_STRLST | 0x77, NULL, 0},
{"nisdomain" , DHCP_STRING | 0x28, NULL, 0},
{"timezone" , DHCP_NUM32 | 0x02, NULL, 0},
{"tftp" , DHCP_STRING | 0x42, NULL, 0},
{"bootfile" , DHCP_STRING | 0x43, NULL, 0},
{"bootsize" , DHCP_NUM16 | 0x0d, NULL, 0},
{"rootpath" , DHCP_STRING | 0x11, NULL, 0},
{"wpad" , DHCP_STRING | 0xfc, NULL, 0},
{"serverid" , DHCP_IP | 0x36, NULL, 0},
{"message" , DHCP_STRING | 0x38, NULL, 0},
{"vlanid" , DHCP_NUM32 | 0x84, NULL, 0},
{"vlanpriority" , DHCP_NUM32 | 0x85, NULL, 0},
{"dns" , DHCP_IPLIST | 0x06, NULL, 0},
{"wins" , DHCP_IPLIST | 0x2c, NULL, 0},
{"nissrv" , DHCP_IPLIST | 0x29, NULL, 0},
{"ntpsrv" , DHCP_IPLIST | 0x2a, NULL, 0},
{"lprsrv" , DHCP_IPLIST | 0x09, NULL, 0},
{"swapsrv" , DHCP_IP | 0x10, NULL, 0},
{"routes" , DHCP_STCRTS | 0x21, NULL, 0},
{"staticroutes" , DHCP_STCRTS | 0x79, NULL, 0},
{"msstaticroutes" , DHCP_STCRTS | 0xf9, NULL, 0},
};
struct fd_pair { int rd; int wr; };
static server_config_t gconfig;
static server_state_t gstate;
static uint8_t infomode;
static struct fd_pair sigfd;
static int constone = 1;
// calculate options size.
static int dhcp_opt_size(uint8_t *optionptr)
{
int i = 0;
for(;optionptr[i] != 0xff; i++) if(optionptr[i] != 0x00) i += optionptr[i + 1] + 2 -1;
return i;
}
// calculates checksum for dhcp messeges.
static uint16_t dhcp_checksum(void *addr, int count)
{
int32_t sum = 0;
uint16_t tmp = 0, *source = (uint16_t *)addr;
while (count > 1) {
sum += *source++;
count -= 2;
}
if (count > 0) {
*(uint8_t*)&tmp = *(uint8_t*)source;
sum += tmp;
}
while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16);
return ~sum;
}
// gets information of INTERFACE and updates IFINDEX, MAC and IP
static int get_interface(const char *interface, int *ifindex, uint32_t *oip, uint8_t *mac)
{
struct ifreq req;
struct sockaddr_in *ip;
int fd = xsocket(AF_INET, SOCK_RAW, IPPROTO_RAW);
req.ifr_addr.sa_family = AF_INET;
xstrncpy(req.ifr_name, interface, IFNAMSIZ);
xioctl(fd, SIOCGIFFLAGS, &req);
if (!(req.ifr_flags & IFF_UP)) return -1;
if (oip) {
xioctl(fd, SIOCGIFADDR, &req);
ip = (struct sockaddr_in*) &req.ifr_addr;
dbg("IP %s\n", inet_ntoa(ip->sin_addr));
*oip = ntohl(ip->sin_addr.s_addr);
}
if (ifindex) {
xioctl(fd, SIOCGIFINDEX, &req);
dbg("Adapter index %d\n", req.ifr_ifindex);
*ifindex = req.ifr_ifindex;
}
if (mac) {
xioctl(fd, SIOCGIFHWADDR, &req);
memcpy(mac, req.ifr_hwaddr.sa_data, 6);
dbg("MAC %02x:%02x:%02x:%02x:%02x:%02x\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
}
close(fd);
return 0;
}
/*
*logs messeges to syslog or console
*opening the log is still left with applet.
*FIXME: move to more relevent lib. probably libc.c
*/
static void infomsg(uint8_t infomode, char *s, ...)
{
int used;
char *msg;
va_list p, t;
if (infomode == LOG_SILENT) return;
va_start(p, s);
va_copy(t, p);
used = vsnprintf(NULL, 0, s, t);
used++;
va_end(t);
msg = xmalloc(used);
vsnprintf(msg, used, s, p);
va_end(p);
if (infomode & LOG_SYSTEM) syslog(LOG_INFO, "%s", msg);
if (infomode & LOG_CONSOLE) printf("%s\n", msg);
free(msg);
}
/*
* Writes self PID in file PATH
* FIXME: libc implementation only writes in /var/run
* this is more generic as some implemenation may provide
* arguments to write in specific file. as dhcpd does.
*/
static void write_pid(char *path)
{
int pidfile = open(path, O_CREAT | O_WRONLY | O_TRUNC, 0666);
if (pidfile > 0) {
char pidbuf[12];
sprintf(pidbuf, "%u", (unsigned)getpid());
write(pidfile, pidbuf, strlen(pidbuf));
close(pidfile);
}
}
// Generic signal handler real handling is done in main funcrion.
static void signal_handler(int sig)
{
unsigned char ch = sig;
if (write(sigfd.wr, &ch, 1) != 1) dbg("can't send signal\n");
}
// signal setup for SIGUSR1 SIGTERM
static int setup_signal()
{
if (pipe((int *)&sigfd) < 0) {
dbg("signal pipe failed\n");
return -1;
}
fcntl(sigfd.wr , F_SETFD, FD_CLOEXEC);
fcntl(sigfd.rd , F_SETFD, FD_CLOEXEC);
int flags = fcntl(sigfd.wr, F_GETFL);
fcntl(sigfd.wr, F_SETFL, flags | O_NONBLOCK);
signal(SIGUSR1, signal_handler);
signal(SIGTERM, signal_handler);
return 0;
}
// String STR to UINT32 conversion strored in VAR
static int strtou32(const char *str, void *var)
{
char *endptr = NULL;
int base = 10;
errno=0;
*((uint32_t*)(var)) = 0;
if (str[0]=='0' && (str[1]=='x' || str[1]=='X')) {
base = 16;
str+=2;
}
long ret_val = strtol(str, &endptr, base);
if (errno) infomsg(infomode, "config : Invalid num %s",str);
else if (endptr && (*endptr!='\0'||endptr == str))
infomsg(infomode, "config : Not a valid num %s",str);
else *((uint32_t*)(var)) = (uint32_t)ret_val;
return 0;
}
// copy string STR in variable VAR
static int strinvar(const char *str, void *var)
{
char **dest = var;
if (*dest) free(*dest);
*dest = strdup(str);
return 0;
}
// IP String STR to binary data.
static int striptovar(const char *str, void *var)
{
in_addr_t addr;
*((uint32_t*)(var)) = 0;
if(!str) {
error_msg("config : NULL address string \n");
return -1;
}
if((addr = inet_addr(str)) == -1) {
error_msg("config : wrong address %s \n",str );
return -1;
}
*((uint32_t*)(var)) = (uint32_t)addr;
return 0;
}
// String to dhcp option conversion
static int strtoopt(const char *str, void *var)
{
char *option, *valstr, *grp, *tp;
uint32_t optcode = 0, inf = infomode, convtmp, mask, nip, router;
uint16_t flag = 0;
int count, size = ARRAY_LEN(options_list);
if (!*str) return 0;
if (!(option = strtok((char*)str, " \t="))) return -1;
infomode = LOG_SILENT;
strtou32(option, (uint32_t*)&optcode);
infomode = inf;
if (optcode > 0 && optcode < 256) { // raw option
for (count = 0; count < size; count++) {
if ((options_list[count].code & 0X00FF) == optcode) {
flag = (options_list[count].code & 0XFF00);
break;
}
}
} else { //string option
for (count = 0; count < size; count++) {
if (!strncmp(options_list[count].key, option, strlen(options_list[count].key))) {
flag = (options_list[count].code & 0XFF00);
optcode = (options_list[count].code & 0X00FF);
break;
}
}
}
if (count == size) {
infomsg(inf, "config : Obsolete OR Unknown Option : %s", option);
return -1;
}
if (!flag || !optcode) return -1;
if (!(valstr = strtok(NULL, " \t"))) {
dbg("config : option %s has no value defined.\n", option);
return -1;
}
dbg(" value : %-20s : ", valstr);
switch (flag) {
case DHCP_NUM32:
options_list[count].len = sizeof(uint32_t);
options_list[count].val = xmalloc(sizeof(uint32_t));
strtou32(valstr, &convtmp);
memcpy(options_list[count].val, &convtmp, sizeof(uint32_t));
break;
case DHCP_NUM16:
options_list[count].len = sizeof(uint16_t);
options_list[count].val = xmalloc(sizeof(uint16_t));
strtou32(valstr, &convtmp);
memcpy(options_list[count].val, &convtmp, sizeof(uint16_t));
break;
case DHCP_NUM8:
options_list[count].len = sizeof(uint8_t);
options_list[count].val = xmalloc(sizeof(uint8_t));
strtou32(valstr, &convtmp);
memcpy(options_list[count].val, &convtmp, sizeof(uint8_t));
break;
case DHCP_IP:
options_list[count].len = sizeof(uint32_t);
options_list[count].val = xmalloc(sizeof(uint32_t));
striptovar(valstr, options_list[count].val);
break;
case DHCP_STRING:
options_list[count].len = strlen(valstr);
options_list[count].val = strdup(valstr);
break;
case DHCP_IPLIST:
while(valstr){
options_list[count].val = xrealloc(options_list[count].val, options_list[count].len + sizeof(uint32_t));
striptovar(valstr, ((uint8_t*)options_list[count].val)+options_list[count].len);
options_list[count].len += sizeof(uint32_t);
valstr = strtok(NULL," \t");
}
break;
case DHCP_IPPLST:
break;
case DHCP_STCRTS:
/* Option binary format:
* mask [one byte, 0..32]
* ip [0..4 bytes depending on mask]
* router [4 bytes]
* may be repeated
* staticroutes 10.0.0.0/8 10.127.0.1, 10.11.12.0/24 10.11.12.1
*/
grp = strtok(valstr, ",");;
while(grp){
while(*grp == ' ' || *grp == '\t') grp++;
tp = strchr(grp, '/');
if (!tp) error_exit("wrong formated static route option");
*tp = '\0';
mask = strtol(++tp, &tp, 10);
if (striptovar(grp, (uint8_t*)&nip)<0) error_exit("wrong formated static route option");
while(*tp == ' ' || *tp == '\t' || *tp == '-') tp++;
if (striptovar(tp, (uint8_t*)&router)<0) error_exit("wrong formated static route option");
options_list[count].val = xrealloc(options_list[count].val, options_list[count].len + 1 + mask/8 + 4);
memcpy(((uint8_t*)options_list[count].val)+options_list[count].len, &mask, 1);
options_list[count].len += 1;
memcpy(((uint8_t*)options_list[count].val)+options_list[count].len, &nip, mask/8);
options_list[count].len += mask/8;
memcpy(((uint8_t*)options_list[count].val)+options_list[count].len, &router, 4);
options_list[count].len += 4;
tp = NULL;
grp = strtok(NULL, ",");
}
break;
}
return 0;
}
// Reads Static leases from STR and updates inner structures.
static int get_staticlease(const char *str, void *var)
{
struct static_lease_s *sltmp;
char *tkmac, *tkip;
int count;
if (!*str) return 0;
if (!(tkmac = strtok((char*)str, " \t"))) {
infomsg(infomode, "config : static lease : mac not found");
return 0;
}
if (!(tkip = strtok(NULL, " \t"))) {
infomsg(infomode, "config : static lease : no ip bind to mac %s", tkmac);
return 0;
}
sltmp = xzalloc(sizeof(struct static_lease_s));
for (count = 0; count < 6; count++, tkmac++) {
errno = 0;
sltmp->mac[count] = strtol(tkmac, &tkmac, 16);
if (sltmp->mac[count]>255 || sltmp->mac[count]<0 || (*tkmac && *tkmac!=':') || errno) {
infomsg(infomode, "config : static lease : mac address wrong format");
free(sltmp);
return 0;
}
}
striptovar(tkip, &sltmp->nip);
sltmp->next = gstate.sleases;
gstate.sleases = sltmp;
return 0;
}
static struct config_keyword keywords[] = {
// keyword handler variable address default
{"start" , striptovar , (void*)&gconfig.start_ip , "192.168.0.20"},
{"end" , striptovar , (void*)&gconfig.end_ip , "192.168.0.254"},
{"interface" , strinvar , (void*)&gconfig.interface , "eth0"},
{"port" , strtou32 , (void*)&gconfig.port , "67"},
{"min_lease" , strtou32 , (void*)&gconfig.min_lease_sec, "60"},
{"max_leases" , strtou32 , (void*)&gconfig.max_leases , "235"},
{"auto_time" , strtou32 , (void*)&gconfig.auto_time , "7200"},
{"decline_time" , strtou32 , (void*)&gconfig.decline_time , "3600"},
{"conflict_time", strtou32 , (void*)&gconfig.conflict_time, "3600"},
{"offer_time" , strtou32 , (void*)&gconfig.offer_time , "60"},
{"lease_file" , strinvar , (void*)&gconfig.lease_file , "/var/lib/misc/dhcpd.leases"}, //LEASES_FILE
{"pidfile" , strinvar , (void*)&gconfig.pidfile , "/var/run/dhcpd.pid"}, //DPID_FILE
{"siaddr" , striptovar , (void*)&gconfig.siaddr_nip , "0.0.0.0"},
{"option" , strtoopt , (void*)&gconfig.options , ""},
{"opt" , strtoopt , (void*)&gconfig.options , ""},
{"notify_file" , strinvar , (void*)&gconfig.notify_file , ""},
{"sname" , strinvar , (void*)&gconfig.sname , ""},
{"boot_file" , strinvar , (void*)&gconfig.boot_file , ""},
{"static_lease" , get_staticlease , (void*)&gconfig.static_leases, ""},
};
// Parses the server config file and updates the global server config accordingly.
static int parse_server_config(char *config_file, struct config_keyword *confkey)
{
FILE *fs = NULL;
char *confline_temp = NULL,*confline = NULL, *tk = NULL, *tokens[2] = {NULL, NULL};
int len, linelen, tcount, count, size = ARRAY_LEN(keywords);
for (count = 0; count < size; count++)
if (confkey[count].handler) confkey[count].handler(confkey[count].def, confkey[count].var);
if (!(fs = fopen(config_file, "r"))) perror_msg("%s", config_file);
for (len = 0, linelen = 0; fs;) {
len = getline(&confline_temp, (size_t*) &linelen, fs);
confline = confline_temp;
if (len <= 0) break;
for (; *confline == ' '; confline++, len--);
if ((confline[0] == '#') || (confline[0] == '\n')) goto free_conf_continue;
tk = strchr(confline, '#');
if (tk) {
for (; *(tk-1)==' ' || *(tk-1)=='\t'; tk--);
*tk = '\0';
}
tk = strchr(confline, '\n');
if (tk) {
for (; *(tk-1)==' ' || *(tk-1)=='\t'; tk--);
*tk = '\0';
}
for (tcount=0, tk=strtok(confline, " \t"); tk && (tcount < 2);
tcount++, tk=strtok(NULL,(tcount==1)?"":" \t")) {
while ((*tk == '\t') || (*tk == ' ')) tk++;
tokens[tcount] = xstrdup(tk);
}
if (tcount<=1) goto free_tk0_continue;
for (count = 0; count < size; count++) {
if (!strcmp(confkey[count].keyword,tokens[0])) {
dbg("got config : %15s : ", confkey[count].keyword);
if (confkey[count].handler(tokens[1], confkey[count].var) == 0)
dbg("%s \n", tokens[1]);
break;
}
}
if (tokens[1]) { free(tokens[1]); tokens[1] = NULL; }
free_tk0_continue:
if (tokens[0]) { free(tokens[0]); tokens[0] = NULL; }
free_conf_continue:
free(confline_temp);
confline_temp = NULL;
}
if (fs) fclose(fs);
return 0;
}
// opens UDP socket for listen
static int open_listensock(void)
{
struct sockaddr_in addr;
struct ifreq ifr;
if (gstate.listensock > 0) close(gstate.listensock);
dbg("Opening listen socket on *:%d %s\n", gconfig.port, gconfig.interface);
gstate.listensock = xsocket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
setsockopt(gstate.listensock, SOL_SOCKET, SO_REUSEADDR, &constone, sizeof(constone));
if (setsockopt(gstate.listensock, SOL_SOCKET, SO_BROADCAST, &constone, sizeof(constone)) == -1) {
dbg("OPEN : brodcast ioctl failed.\n");
close(gstate.listensock);
return -1;
}
memset(&ifr, 0, sizeof(ifr));
xstrncpy(ifr.ifr_name, gconfig.interface, IFNAMSIZ);
setsockopt(gstate.listensock, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr));
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = (flag_chk(FLAG_P))?htons(TT.port):htons(67); //SERVER_PORT
addr.sin_addr.s_addr = INADDR_ANY ;
if (bind(gstate.listensock, (struct sockaddr *) &addr, sizeof(addr))) {
close(gstate.listensock);
perror_exit("bind failed");
}
dbg("OPEN : success\n");
return 0;
}
// Sends data through raw socket.
static int send_packet(uint8_t broadcast)
{
struct sockaddr_ll dest_sll;
dhcp_raw_t packet;
unsigned padding;
int fd, result = -1;
uint8_t bmacaddr[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
memset(&packet, 0, sizeof(dhcp_raw_t));
memcpy(&packet.dhcp, &gstate.send_pkt, sizeof(dhcp_msg_t));
if ((fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) {
dbg("SEND : socket failed\n");
return -1;
}
memset(&dest_sll, 0, sizeof(dest_sll));
dest_sll.sll_family = AF_PACKET;
dest_sll.sll_protocol = htons(ETH_P_IP);
dest_sll.sll_ifindex = gconfig.ifindex;
dest_sll.sll_halen = 6;
memcpy(dest_sll.sll_addr, (broadcast)?bmacaddr:gstate.rcvd_pkt.chaddr , 6);
if (bind(fd, (struct sockaddr *) &dest_sll, sizeof(dest_sll)) < 0) {
dbg("SEND : bind failed\n");
close(fd);
return -1;
}
padding = 308 - 1 - dhcp_opt_size(gstate.send_pkt.options);
packet.iph.protocol = IPPROTO_UDP;
packet.iph.saddr = gconfig.server_nip;
packet.iph.daddr = (broadcast || (gstate.rcvd_pkt.ciaddr == 0))?INADDR_BROADCAST:gstate.rcvd_pkt.ciaddr;
packet.udph.source = htons(67);//SERVER_PORT
packet.udph.dest = htons(68); //CLIENT_PORT
packet.udph.len = htons(sizeof(dhcp_raw_t) - sizeof(struct iphdr) - padding);
packet.iph.tot_len = packet.udph.len;
packet.udph.check = dhcp_checksum(&packet, sizeof(dhcp_raw_t) - padding);
packet.iph.tot_len = htons(sizeof(dhcp_raw_t) - padding);
packet.iph.ihl = sizeof(packet.iph) >> 2;
packet.iph.version = IPVERSION;
packet.iph.ttl = IPDEFTTL;
packet.iph.check = dhcp_checksum(&packet.iph, sizeof(packet.iph));
result = sendto(fd, &packet, sizeof(dhcp_raw_t) - padding, 0,
(struct sockaddr *) &dest_sll, sizeof(dest_sll));
dbg("sendto %d\n", result);
close(fd);
if (result < 0) dbg("PACKET send error\n");
return result;
}
// Reads from UDP socket
static int read_packet(void)
{
int ret;
memset(&gstate.rcvd_pkt, 0, sizeof(dhcp_msg_t));
ret = read(gstate.listensock, &gstate.rcvd_pkt, sizeof(dhcp_msg_t));
if (ret < 0) {
dbg("Packet read error, ignoring. \n");
return ret; // returns -1
}
if (gstate.rcvd_pkt.cookie != htonl(DHCP_MAGIC)) {
dbg("Packet with bad magic, ignoring. \n");
return -2;
}
if (gstate.rcvd_pkt.op != 1) { //BOOTPREQUEST
dbg("Not a BOOT REQUEST ignoring. \n");
return -2;
}
if (gstate.rcvd_pkt.hlen != 6) {
dbg("hlen != 6 ignoring. \n");
return -2;
}
dbg("Received a packet. Size : %d \n", ret);
return ret;
}
// Preapres a dhcp packet with defaults and configs
static uint8_t* prepare_send_pkt(void)
{
memset((void*)&gstate.send_pkt, 0, sizeof(gstate.send_pkt));
gstate.send_pkt.op = 2; //BOOTPREPLY
gstate.send_pkt.htype = 1;
gstate.send_pkt.hlen = 6;
gstate.send_pkt.xid = gstate.rcvd_pkt.xid;
gstate.send_pkt.cookie = htonl(DHCP_MAGIC);
gstate.send_pkt.nsiaddr = gconfig.server_nip;
memcpy(gstate.send_pkt.chaddr, gstate.rcvd_pkt.chaddr, 16);
gstate.send_pkt.options[0] = DHCP_OPT_END;
return gstate.send_pkt.options;
}
// Sets a option value in dhcp packet's option field
static uint8_t* set_optval(uint8_t *optptr, uint16_t opt, void *var, size_t len)
{
while (*optptr != DHCP_OPT_END) optptr++;
*optptr++ = (uint8_t)(opt & 0x00FF);
*optptr++ = (uint8_t) len;
memcpy(optptr, var, len);
optptr += len;
*optptr = DHCP_OPT_END;
return optptr;
}
// Gets a option value from dhcp packet's option field
static uint8_t* get_optval(uint8_t *optptr, uint16_t opt, void *var)
{
size_t len;
uint8_t overloaded = 0;
while (1) {
while (*optptr == DHCP_OPT_PADDING) optptr++;
if ((*optptr & 0x00FF) == DHCP_OPT_END) break;
if ((*optptr & 0x00FF) == DHCP_OPT_OPTION_OVERLOAD) {
overloaded = optptr[2];
optptr += optptr[1] + 2;
}
len = optptr[1];
if (*optptr == (opt & 0x00FF))
switch (opt & 0xFF00) {
case DHCP_NUM32: // FALLTHROUGH
case DHCP_IP:
memcpy(var, optptr+2, sizeof(uint32_t));
optptr += len + 2;
return optptr;
break;
case DHCP_NUM16:
memcpy(var, optptr+2, sizeof(uint16_t));
optptr += len + 2;
return optptr;
break;
case DHCP_NUM8:
memcpy(var, optptr+2, sizeof(uint8_t));
optptr += len + 2;
return optptr;
break;
case DHCP_STRING:
var = xstrndup((char*) optptr, len);
optptr += len + 2;
return optptr;
break;
}
optptr += len + 2;
}
if ((overloaded == 1) | (overloaded == 3)) get_optval((uint8_t*)&gstate.rcvd_pkt.file, opt, var);
if ((overloaded == 2) | (overloaded == 3)) get_optval((uint8_t*)&gstate.rcvd_pkt.sname, opt, var);
return optptr;
}
// Retrives Requested Parameter list from dhcp req packet.
static uint8_t get_reqparam(uint8_t **list)
{
uint8_t len, *optptr;
if(*list) free(*list);
for (optptr = gstate.rcvd_pkt.options;
*optptr && *optptr!=((DHCP_OPT_PARAM_REQ) & 0x00FF); optptr+=optptr[1]+2);
len = *++optptr;
*list = xzalloc(len+1);
memcpy(*list, ++optptr, len);
return len;
}
// Sets values of req param in dhcp offer packet.
static uint8_t* set_reqparam(uint8_t *optptr, uint8_t *list)
{
uint8_t reqcode;
int count, size = ARRAY_LEN(options_list);
while (*list) {
reqcode = *list++;
for (count = 0; count < size; count++) {
if ((options_list[count].code & 0X00FF)==reqcode) {
if (!(options_list[count].len) || !(options_list[count].val)) break;
for (; *optptr && *optptr!=DHCP_OPT_END; optptr+=optptr[1]+2);
*optptr++ = (uint8_t) (options_list[count].code & 0x00FF);
*optptr++ = (uint8_t) options_list[count].len;
memcpy(optptr, options_list[count].val, options_list[count].len);
optptr += options_list[count].len;
*optptr = DHCP_OPT_END;
break;
}
}
}
return optptr;
}
static void run_notify(char **argv)
{
struct stat sts;
volatile int error = 0;
pid_t pid;
if (stat(argv[0], &sts) == -1 && errno == ENOENT) {
infomsg(infomode, "notify file: %s : not exist.", argv[0]);
return;
}
fflush(NULL);
pid = vfork();
if (pid < 0) {
dbg("Fork failed.\n");
return;
}
if (!pid) {
execvp(argv[0], argv);
error = errno;
_exit(111);
}
if (error) {
waitpid(pid, NULL, 0);
errno = error;
}
dbg("script complete.\n");
}
static int write_leasefile(void)
{
int fd;
uint32_t curr, tmp_time;
int64_t timestamp;
struct arg_list *listdls = gstate.dleases;
dyn_lease *dls;
if ((fd = open(gconfig.lease_file, O_WRONLY | O_CREAT | O_TRUNC, 0600)) < 0) {
perror_msg("can't open %s ", gconfig.lease_file);
return fd;
}
curr = timestamp = time(NULL);
timestamp = SWAP_BE64(timestamp);
writeall(fd, &timestamp, sizeof(timestamp));
while (listdls) {
dls = (dyn_lease*)listdls->arg;
tmp_time = dls->expires;
dls->expires -= curr;
if ((int32_t) dls->expires < 0) goto skip;
dls->expires = htonl(dls->expires);
writeall(fd, dls, sizeof(dyn_lease));
skip:
dls->expires = tmp_time;
listdls = listdls->next;
}
close(fd);
if (gconfig.notify_file) {
char *argv[3];
argv[0] = gconfig.notify_file;
argv[1] = gconfig.lease_file;
argv[2] = NULL;
run_notify(argv);
}
return 0;
}
// Update max lease time from options.
static void set_maxlease(void)
{
int count, size = ARRAY_LEN(options_list);
for (count = 0; count < size; count++)
if (options_list[count].val && options_list[count].code == (DHCP_OPT_LEASE_TIME)) {
gconfig.max_lease_sec = *((uint32_t*)options_list[count].val);
break;
}
if (!gconfig.max_lease_sec) gconfig.max_lease_sec = (60*60*24*10);// DEFAULT_LEASE_TIME;
}
// Returns lease time for client.
static uint32_t get_lease(uint32_t req_exp)
{
uint32_t now = time(NULL);
req_exp = req_exp - now;
if ((req_exp <= 0) || (req_exp > gconfig.max_lease_sec))
return gconfig.max_lease_sec;
if (req_exp < gconfig.min_lease_sec)
return gconfig.min_lease_sec;
return req_exp;
}
// Verify ip NIP in current leases ( assigned or not)
static int verifyip_in_lease(uint32_t nip, uint8_t mac[6])
{
static_lease *sls;
struct arg_list *listdls;
for (listdls = gstate.dleases; listdls; listdls = listdls->next) {
if (((dyn_lease*) listdls->arg)->lease_nip == nip) {
if (((int32_t)(((dyn_lease*) listdls->arg)->expires) - time(NULL)) < 0)
return 0;
return -1;
}
if (!memcmp(((dyn_lease*) listdls->arg)->lease_mac, mac, 6)) return -1;
}
for (sls = gstate.sleases; sls; sls = sls->next)
if (sls->nip == nip) return -2;
if ((ntohl(nip) < gconfig.start_ip) || (ntohl(nip) > gconfig.end_ip))
return -3;
return 0;
}
// add ip assigned_nip to dynamic lease.
static int addip_to_lease(uint32_t assigned_nip, uint8_t mac[6], uint32_t *req_exp, char *hostname, uint8_t update)
{
dyn_lease *dls;
struct arg_list *listdls = gstate.dleases;
uint32_t now = time(NULL);
while (listdls) {
if (!memcmp(((dyn_lease*) listdls->arg)->lease_mac, mac, 6)) {
if (update) *req_exp = get_lease(*req_exp + ((dyn_lease*) listdls->arg)->expires);
((dyn_lease*) listdls->arg)->expires = *req_exp + now;
return 0;
}
listdls = listdls->next;
}
dls = xzalloc(sizeof(dyn_lease));
memcpy(dls->lease_mac, mac, 6);
dls->lease_nip = assigned_nip;
if (hostname) memcpy(dls->hostname, hostname, 20);
if (update) *req_exp = get_lease(*req_exp + now);
dls->expires = *req_exp + now;
listdls = xzalloc(sizeof(struct arg_list));
listdls->next = gstate.dleases;
listdls->arg = (char*)dls;
gstate.dleases = listdls;
return 0;
}
// delete ip assigned_nip from dynamic lease.
static int delip_from_lease(uint32_t assigned_nip, uint8_t mac[6], uint32_t del_time)
{
struct arg_list *listdls = gstate.dleases;
while (listdls) {
if (!memcmp(((dyn_lease*) listdls->arg)->lease_mac, mac, 6)) {
((dyn_lease*) listdls->arg)->expires = del_time + time(NULL);
return 0;
}
listdls = listdls->next;
}
return -1;
}
// returns a IP from static, dynamic leases or free ip pool, 0 otherwise.
static uint32_t getip_from_pool(uint32_t req_nip, uint8_t mac[6], uint32_t *req_exp, char *hostname)
{
uint32_t nip = 0;
static_lease *sls = gstate.sleases;
struct arg_list *listdls = gstate.dleases, *tmp = NULL;
if (req_nip && (!verifyip_in_lease(req_nip, mac))) nip = req_nip;
if (!nip) {
while (listdls) {
if (!memcmp(((dyn_lease*)listdls->arg)->lease_mac, mac, 6)) {
nip = ((dyn_lease*)listdls->arg)->lease_nip;
if (tmp) tmp->next = listdls->next;
else gstate.dleases = listdls->next;
free(listdls->arg);
free(listdls);
if (verifyip_in_lease(nip, mac) < 0) nip = 0;
break;
}
tmp = listdls;
listdls = listdls->next;
}
}
if (!nip) {
while (sls) {
if (memcmp(sls->mac, mac, 6) == 0) {
nip = sls->nip;
break;
}
sls = sls->next;
}
}
if (!nip) {
for (nip = htonl(gconfig.start_ip); ntohl(nip) <= gconfig.end_ip; ) {
if (!verifyip_in_lease(nip, mac)) break;
nip = ntohl(nip);
nip = htonl(++nip);
}
if (ntohl(nip) > gconfig.end_ip) {
nip = 0;
infomsg(infomode, "can't find free IP in IP Pool.");
}
}
if (nip) addip_to_lease(nip, mac, req_exp, hostname, 1);
return nip;
}
static int read_leasefile(void)
{
uint32_t passed, ip;
int32_t tmp_time;
int64_t timestamp;
dyn_lease *dls;
int ret = -1, fd = open(gconfig.lease_file, O_RDONLY);
if (fd < 0) return fd;
dls = xzalloc(sizeof(dyn_lease));
if (read(fd, &timestamp, sizeof(timestamp)) != sizeof(timestamp)) goto error_exit;
timestamp = SWAP_BE64(timestamp);
passed = time(NULL) - timestamp;
if ((uint64_t)passed > 12 * 60 * 60) goto error_exit;
while (read(fd, dls, sizeof(dyn_lease)) == sizeof(dyn_lease)) {
ip = ntohl(dls->lease_nip);
if (ip >= gconfig.start_ip && ip <= gconfig.end_ip) {
tmp_time = ntohl(dls->expires) - passed;
if (tmp_time < 0) continue;
addip_to_lease(dls->lease_nip, dls->lease_mac, (uint32_t*)&tmp_time, dls->hostname, 0);
}
}
ret = 0;
error_exit:
free(dls);
close(fd);
return ret;
}
void dhcpd_main(void)
{
struct timeval tv;
int retval;
uint8_t *optptr, msgtype = 0;
uint32_t waited = 0, serverid = 0, requested_nip = 0;
uint32_t reqested_lease = 0, ip_pool_size = 0;
char *hstname = NULL;
fd_set rfds;
infomode = LOG_CONSOLE;
if (!(flag_chk(FLAG_f))) {
daemon(0,0);
infomode = LOG_SILENT;
}
if (flag_chk(FLAG_S)) {
openlog("UDHCPD :", LOG_PID, LOG_DAEMON);
infomode |= LOG_SYSTEM;
}
setlinebuf(stdout);
parse_server_config((toys.optc==1)?toys.optargs[0]:"/etc/dhcpd.conf", keywords); //DHCPD_CONF_FILE
infomsg(infomode, "toybox dhcpd started");
gconfig.start_ip = ntohl(gconfig.start_ip);
gconfig.end_ip = ntohl(gconfig.end_ip);
ip_pool_size = gconfig.end_ip - gconfig.start_ip + 1;
if (gconfig.max_leases > ip_pool_size) {
error_msg("max_leases=%u is too big, setting to %u", (unsigned) gconfig.max_leases, ip_pool_size);
gconfig.max_leases = ip_pool_size;
}
write_pid(gconfig.pidfile);
set_maxlease();
read_leasefile();
if(TT.iface) gconfig.interface = TT.iface;
if (get_interface(gconfig.interface, &gconfig.ifindex, &gconfig.server_nip,
gconfig.server_mac)<0)
perror_exit("Failed to get interface %s", gconfig.interface);
gconfig.server_nip = htonl(gconfig.server_nip);
setup_signal();
open_listensock();
fcntl(gstate.listensock, F_SETFD, FD_CLOEXEC);
for (;;) {
uint32_t timestmp = time(NULL);
FD_ZERO(&rfds);
FD_SET(gstate.listensock, &rfds);
FD_SET(sigfd.rd, &rfds);
tv.tv_sec = gconfig.auto_time - waited;
tv.tv_usec = 0;
retval = 0;
serverid = 0;
msgtype = 0;
int maxfd = (sigfd.rd > gstate.listensock)? sigfd.rd : gstate.listensock;
dbg("select waiting ....\n");
retval = select(maxfd + 1, &rfds, NULL, NULL, (gconfig.auto_time?&tv:NULL));
if (retval < 0) {
if (errno == EINTR) {
waited += (unsigned) time(NULL) - timestmp;
continue;
}
dbg("Error in select wait again...\n");
continue;
}
if (!retval) { // Timed out
dbg("select wait Timed Out...\n");
waited = 0;
write_leasefile();
if (get_interface(gconfig.interface, &gconfig.ifindex, &gconfig.server_nip, gconfig.server_mac)<0)
perror_exit("Interface lost %s\n", gconfig.interface);
gconfig.server_nip = htonl(gconfig.server_nip);
continue;
}
if (FD_ISSET(sigfd.rd, &rfds)) { // Some Activity on RDFDs : is signal
unsigned char sig;
if (read(sigfd.rd, &sig, 1) != 1) {
dbg("signal read failed.\n");
continue;
}
switch (sig) {
case SIGUSR1:
infomsg(infomode, "Received SIGUSR1");
write_leasefile();
continue;
case SIGTERM:
infomsg(infomode, "Received SIGTERM");
write_leasefile();
unlink(gconfig.pidfile);
exit(0);
break;
default: break;
}
}
if (FD_ISSET(gstate.listensock, &rfds)) { // Some Activity on RDFDs : is socket
dbg("select listen sock read\n");
if (read_packet() < 0) {
open_listensock();
continue;
}
waited += time(NULL) - timestmp;
get_optval((uint8_t*)&gstate.rcvd_pkt.options, DHCP_OPT_MESSAGE_TYPE, &gstate.rqcode);
if (gstate.rqcode == 0 || gstate.rqcode < DHCPDISCOVER
|| gstate.rqcode > DHCPINFORM) {
dbg("no or bad message type option, ignoring packet.\n");
continue;
}
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_SERVER_ID, &serverid);
if (serverid && (serverid != gconfig.server_nip)) {
dbg("server ID doesn't match, ignoring packet.\n");
continue;
}
switch (gstate.rqcode) {
case DHCPDISCOVER:
msgtype = DHCPOFFER;
dbg("Message Type : DHCPDISCOVER\n");
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_REQUESTED_IP, &requested_nip);
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_HOST_NAME, &hstname);
reqested_lease = gconfig.offer_time;
get_reqparam(&gstate.rqopt);
optptr = prepare_send_pkt();
gstate.send_pkt.yiaddr = getip_from_pool(requested_nip, gstate.rcvd_pkt.chaddr, &reqested_lease, hstname);
if(!gstate.send_pkt.yiaddr){
msgtype = DHCPNAK;
optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1);
send_packet(1);
break;
}
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_LEASE_TIME, &reqested_lease);
reqested_lease = htonl(get_lease(reqested_lease + time(NULL)));
optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1);
optptr = set_optval(optptr, DHCP_OPT_SERVER_ID, &gconfig.server_nip, 4);
optptr = set_optval(optptr, DHCP_OPT_LEASE_TIME, &reqested_lease, 4);
optptr = set_reqparam(optptr, gstate.rqopt);
send_packet(1);
break;
case DHCPREQUEST:
msgtype = DHCPACK;
dbg("Message Type : DHCPREQUEST\n");
optptr = prepare_send_pkt();
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_REQUESTED_IP, &requested_nip);
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_LEASE_TIME, &reqested_lease);
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_HOST_NAME, &hstname);
gstate.send_pkt.yiaddr = getip_from_pool(requested_nip, gstate.rcvd_pkt.chaddr, &reqested_lease, hstname);
if (!serverid) reqested_lease = gconfig.max_lease_sec;
if (!gstate.send_pkt.yiaddr) {
msgtype = DHCPNAK;
optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1);
send_packet(1);
break;
}
optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1);
optptr = set_optval(optptr, DHCP_OPT_SERVER_ID, &gconfig.server_nip, 4);
reqested_lease = htonl(reqested_lease);
optptr = set_optval(optptr, DHCP_OPT_LEASE_TIME, &reqested_lease, 4);
send_packet(1);
write_leasefile();
break;
case DHCPDECLINE:// FALL THROUGH
case DHCPRELEASE:
dbg("Message Type : DHCPDECLINE or DHCPRELEASE \n");
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_SERVER_ID, &serverid);
if (serverid != gconfig.server_nip) break;
get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_REQUESTED_IP, &requested_nip);
delip_from_lease(requested_nip, gstate.rcvd_pkt.chaddr, (gstate.rqcode==DHCPRELEASE)?0:gconfig.decline_time);
break;
default:
dbg("Message Type : %u\n", gstate.rqcode);
break;
}
}
}
}