/* dhcp6.c - DHCP6 client for dynamic network configuration.
*
* Copyright 2015 Rajni Kant <rajnikant12345@gmail.com>
*
* Not in SUSv4.
USE_DHCP6(NEWTOY(dhcp6, "r:A#<0T#<0t#<0s:p:i:SRvqnbf", TOYFLAG_SBIN|TOYFLAG_ROOTONLY))
config DHCP6
bool "dhcp6"
default n
help
usage: dhcp6 [-fbnqvR] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]
Configure network dynamicaly using DHCP.
-i Interface to use (default eth0)
-p Create pidfile
-s Run PROG at DHCP events
-t Send up to N Solicit packets
-T Pause between packets (default 3 seconds)
-A Wait N seconds after failure (default 20)
-f Run in foreground
-b Background if lease is not obtained
-n Exit if lease is not obtained
-q Exit after obtaining lease
-R Release IP on exit
-S Log to syslog too
-r Request this IP address
-v Verbose
Signals:
USR1 Renew current lease
USR2 Release current lease
*/
#define FOR_dhcp6
#include "toys.h"
#include <linux/sockios.h>
#include <linux/if_ether.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/udp.h>
#include <linux/if_packet.h>
#include <syslog.h>
GLOBALS(
char *interface_name, *pidfile, *script;
long retry, timeout, errortimeout;
char *req_ip;
int length, state, request_length, sock, sock1, status, retval, retries;
struct timeval tv;
uint8_t transction_id[3];
struct sockaddr_in6 input_socket6;
)
#define DHCP6SOLICIT 1
#define DHCP6ADVERTISE 2 // server -> client
#define DHCP6REQUEST 3
#define DHCP6CONFIRM 4
#define DHCP6RENEW 5
#define DHCP6REBIND 6
#define DHCP6REPLY 7 // server -> client
#define DHCP6RELEASE 8
#define DHCP6DECLINE 9
#define DHCP6RECONFIGURE 10 // server -> client
#define DHCP6INFOREQUEST 11
#define DHCP6RELAYFLOW 12 // relay -> relay/server
#define DHCP6RELAYREPLY 13 // server/relay -> relay
// DHCPv6 option codes (partial). See RFC 3315
#define DHCP6_OPT_CLIENTID 1
#define DHCP6_OPT_SERVERID 2
#define DHCP6_OPT_IA_NA 3
#define DHCP6_OPT_IA_ADDR 5
#define DHCP6_OPT_ORO 6
#define DHCP6_OPT_PREFERENCE 7
#define DHCP6_OPT_ELAPSED_TIME 8
#define DHCP6_OPT_RELAY_MSG 9
#define DHCP6_OPT_STATUS_CODE 13
#define DHCP6_OPT_IA_PD 25
#define DHCP6_OPT_IA_PREFIX 26
#define DHCP6_STATUS_SUCCESS 0
#define DHCP6_STATUS_NOADDRSAVAIL 2
#define DHCP6_DUID_LLT 1
#define DHCP6_DUID_EN 2
#define DHCP6_DUID_LL 3
#define DHCP6_DUID_UUID 4
#define DHCPC_SERVER_PORT 547
#define DHCPC_CLIENT_PORT 546
#define LOG_SILENT 0x0
#define LOG_CONSOLE 0x1
#define LOG_SYSTEM 0x2
typedef struct __attribute__((packed)) dhcp6_msg_s {
uint8_t msgtype, transaction_id[3], options[524];
} dhcp6_msg_t;
typedef struct __attribute__((packed)) optval_duid_llt {
uint16_t type;
uint16_t hwtype;
uint32_t time;
uint8_t lladdr[6];
} DUID;
typedef struct __attribute__((packed)) optval_ia_na {
uint32_t iaid, t1, t2;
} IA_NA;
typedef struct __attribute__((packed)) dhcp6_raw_s {
struct ip6_hdr iph;
struct udphdr udph;
dhcp6_msg_t dhcp6;
} dhcp6_raw_t;
typedef struct __attribute__((packed)) dhcp_data_client {
uint16_t status_code;
uint32_t iaid , t1,t2, pf_lf, va_lf;
uint8_t ipaddr[17] ;
} DHCP_DATA;
static DHCP_DATA dhcp_data;
static dhcp6_raw_t *mymsg;
static dhcp6_msg_t mesg;
static DUID *duid;
static void (*dbg)(char *format, ...);
static void dummy(char *format, ...)
{
return;
}
static void logit(char *format, ...)
{
int used;
char *msg;
va_list p, t;
uint8_t infomode = LOG_SILENT;
if (toys.optflags & FLAG_S) infomode |= LOG_SYSTEM;
if(toys.optflags & FLAG_v) infomode |= LOG_CONSOLE;
va_start(p, format);
va_copy(t, p);
used = vsnprintf(NULL, 0, format, t);
used++;
va_end(t);
msg = xmalloc(used);
vsnprintf(msg, used, format, p);
va_end(p);
if (infomode & LOG_SYSTEM) syslog(LOG_INFO, "%s", msg);
if (infomode & LOG_CONSOLE) printf("%s", msg);
free(msg);
return;
}
static void get_mac(uint8_t *mac, char *interface)
{
int fd;
struct ifreq req;
if (!mac) return;
fd = xsocket(AF_INET6, SOCK_RAW, IPPROTO_RAW);
req.ifr_addr.sa_family = AF_INET6;
xstrncpy(req.ifr_name, interface, IFNAMSIZ);
xioctl(fd, SIOCGIFHWADDR, &req);
memcpy(mac, req.ifr_hwaddr.sa_data, 6);
xclose(fd);
}
static void fill_option(uint16_t option_id, uint16_t option_len, uint8_t **dhmesg)
{
uint8_t *tmp = *dhmesg;
*((uint16_t*)tmp) = htons(option_id);
*(uint16_t*)(tmp+2) = htons(option_len);
*dhmesg += 4;
TT.length += 4;
}
static void fill_clientID()
{
uint8_t *tmp = &mesg.options[TT.length];
if(!duid) {
uint8_t mac[7] = {0,};
duid = (DUID*)malloc(sizeof(DUID));
duid->type = htons(1);
duid->hwtype = htons(1);
duid->time = htonl((uint32_t)(time(NULL) - 946684800) & 0xffffffff);
fill_option(DHCP6_OPT_CLIENTID,14,&tmp);
get_mac(mac, TT.interface_name);
memcpy(duid->lladdr,mac, 6);
memcpy(tmp,(uint8_t*)duid,sizeof(DUID));
}
else {
fill_option(DHCP6_OPT_CLIENTID,14,&tmp);
memcpy(tmp,(uint8_t*)duid,sizeof(DUID));
}
TT.length += sizeof(DUID);
}
// TODO: make it generic for multiple options.
static void fill_optionRequest()
{
uint8_t *tmp = &mesg.options[TT.length];
fill_option(DHCP6_OPT_ORO,4,&tmp);
*(uint16_t*)(tmp+4) = htons(23);
*(uint16_t*)(tmp+6) = htons(24);
TT.length += 4;
}
static void fill_elapsedTime()
{
uint8_t *tmp = &mesg.options[TT.length];
fill_option(DHCP6_OPT_ELAPSED_TIME, 2, &tmp);
*(uint16_t*)(tmp+6) = htons(0);
TT.length += 2;
}
static void fill_iaid()
{
IA_NA iana;
uint8_t *tmp = &mesg.options[TT.length];
fill_option(DHCP6_OPT_IA_NA, 12, &tmp);
iana.iaid = rand();
iana.t1 = 0xffffffff;
iana.t2 = 0xffffffff;
memcpy(tmp, (uint8_t*)&iana, sizeof(IA_NA));
TT.length += sizeof(IA_NA);
}
//static void mode_raw(int *sock_t)
static void mode_raw()
{
int constone = 1;
struct sockaddr_ll sockll;
if (TT.sock > 0) xclose(TT.sock);
TT.sock = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6));
memset(&sockll, 0, sizeof(sockll));
sockll.sll_family = AF_PACKET;
sockll.sll_protocol = htons(ETH_P_IPV6);
sockll.sll_ifindex = if_nametoindex(TT.interface_name);
if (bind(TT.sock, (struct sockaddr *) &sockll, sizeof(sockll))) {
xclose(TT.sock);
error_exit("MODE RAW : Bind fail.\n");
}
if (setsockopt(TT.sock, SOL_PACKET, PACKET_HOST,&constone, sizeof(int)) < 0) {
if (errno != ENOPROTOOPT) error_exit("MODE RAW : Bind fail.\n");
}
}
static void generate_transection_id()
{
int i, r = rand() % 0xffffff;
for (i=0; i<3; i++) {
TT.transction_id[i] = r%0xff;
r = r/10;
}
}
static void set_timeout(int seconds)
{
TT.tv.tv_sec = seconds;
TT.tv.tv_usec = 100000;
}
static void send_msg(int type)
{
struct sockaddr_in6 addr6;
int sendlength = 0;
memset(&addr6, 0, sizeof(addr6));
addr6.sin6_family = AF_INET6;
addr6.sin6_port = htons(DHCPC_SERVER_PORT); //SERVER_PORT
inet_pton(AF_INET6, "ff02::1:2", &addr6.sin6_addr);
mesg.msgtype = type;
generate_transection_id();
memcpy(mesg.transaction_id, TT.transction_id, 3);
if (type == DHCP6SOLICIT) {
TT.length = 0;
fill_clientID();
fill_optionRequest();
fill_elapsedTime();
fill_iaid();
sendlength = sizeof(dhcp6_msg_t) - 524 + TT.length;
} else if (type == DHCP6REQUEST || type == DHCP6RELEASE || type == DHCP6RENEW)
sendlength = TT.request_length;
dbg("Sending message type: %d\n", type);
sendlength = sendto(TT.sock1, &mesg, sendlength , 0,(struct sockaddr *)&addr6,
sizeof(struct sockaddr_in6 ));
if (sendlength <= 0) dbg("Error in sending message type: %d\n", type);
}
uint8_t *get_msg_ptr(uint8_t *data, int data_length, int msgtype)
{
uint16_t type = *((uint16_t*)data), length = *((uint16_t*)(data+2));
type = ntohs(type);
if (type == msgtype) return data;
length = ntohs(length);
while (type != msgtype) {
data_length -= (4 + length);
if (data_length <= 0) break;
data = data + 4 + length;
type = ntohs(*((uint16_t*)data));
length = ntohs(*((uint16_t*)(data+2)));
if (type == msgtype) return data;
}
return NULL;
}
static uint8_t *check_server_id(uint8_t *data, int data_length)
{
return get_msg_ptr(data, data_length, DHCP6_OPT_SERVERID);
}
static int check_client_id(uint8_t *data, int data_length)
{
if ((data = get_msg_ptr(data, data_length, DHCP6_OPT_CLIENTID))) {
DUID one = *((DUID*)(data+4));
DUID two = *((DUID*)&mesg.options[4]);
if (!memcmp(&one, &two, sizeof(DUID))) return 1;
}
return 0;
}
static int validate_ids()
{
if (!check_server_id(mymsg->dhcp6.options,
TT.status - ((char*)&mymsg->dhcp6.options[0] - (char*)mymsg) )) {
dbg("Invalid server id: %d\n");
return 0;
}
if (!check_client_id(mymsg->dhcp6.options,
TT.status - ((char*)&mymsg->dhcp6.options[0] - (char*)mymsg) )) {
dbg("Invalid client id: %d\n");
return 0;
}
return 1;
}
static void parse_ia_na(uint8_t *data, int data_length)
{
uint8_t *t = get_msg_ptr(data, data_length, DHCP6_OPT_IA_NA);
uint16_t iana_len, content_len = 0;
memset(&dhcp_data,0,sizeof(dhcp_data));
if (!t) return;
iana_len = ntohs(*((uint16_t*)(t+2)));
dhcp_data.iaid = ntohl(*((uint32_t*)(t+4)));
dhcp_data.t1 = ntohl(*((uint32_t*)(t+8)));
dhcp_data.t2 = ntohl(*((uint32_t*)(t+12)));
t += 16;
iana_len -= 12;
while(iana_len > 0) {
uint16_t sub_type = ntohs(*((uint16_t*)(t)));
switch (sub_type) {
case DHCP6_OPT_IA_ADDR:
content_len = ntohs(*((uint16_t*)(t+2)));
memcpy(dhcp_data.ipaddr,t+4,16);
if (TT.state == DHCP6SOLICIT) {
if (TT.req_ip) {
struct addrinfo *res = NULL;
if(!getaddrinfo(TT.req_ip, NULL, NULL,&res)) {
dbg("Requesting IP: %s\n", TT.req_ip);
memcpy (&TT.input_socket6, res->ai_addr, res->ai_addrlen);
memcpy(t+4, TT.input_socket6.sin6_addr.__in6_u.__u6_addr8, 16);
} else xprintf("Invalid IP: %s\n",TT.req_ip);
freeaddrinfo(res);
}
}
dhcp_data.pf_lf = ntohl(*((uint32_t*)(t+20)));
dhcp_data.va_lf = ntohl(*((uint32_t*)(t+24)));
iana_len -= (content_len + 4);
t += (content_len + 4);
break;
case DHCP6_OPT_STATUS_CODE:
content_len = ntohs(*((uint16_t*)(t+2)));
dhcp_data.status_code = ntohs(*((uint16_t*)(t+4)));
iana_len -= (content_len + 4);
t += (content_len + 4);
break;
default:
content_len = ntohs(*((uint16_t*)(t+2)));
iana_len -= (content_len + 4);
t += (content_len + 4);
break;
}
}
}
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);
}
}
// Creates environment pointers from RES to use in script
static int fill_envp(DHCP_DATA *res)
{
int ret = setenv("interface", TT.interface_name, 1);
if (ret) return ret;
inet_ntop(AF_INET6, res->ipaddr, toybuf, INET6_ADDRSTRLEN);
ret = setenv("ip",(const char*)toybuf , 1);
return ret;
}
// Executes Script NAME.
static void run_script(DHCP_DATA *res, char *name)
{
volatile int error = 0;
struct stat sts;
pid_t pid;
char *argv[3];
char *script = (toys.optflags & FLAG_s) ? TT.script
: "/usr/share/dhcp/default.script";
if (stat(script, &sts) == -1 && errno == ENOENT) return;
if (!res || fill_envp(res)) {
dbg("Failed to create environment variables.\n");
return;
}
dbg("Executing %s %s\n", script, name);
argv[0] = (char*)script;
argv[1] = (char*)name;
argv[2] = NULL;
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;
perror_msg("script exec failed");
}
dbg("script complete.\n");
}
static void lease_fail()
{
dbg("Lease failed.\n");
run_script(NULL, "leasefail");
if (toys.optflags & FLAG_n) {
xclose(TT.sock);
xclose(TT.sock1);
error_exit("Lease Failed, Exiting.");
}
if (toys.optflags & FLAG_b) {
dbg("Lease failed. Going to daemon mode.\n");
if (daemon(0,0)) perror_exit("daemonize");
if (toys.optflags & FLAG_p) write_pid(TT.pidfile);
toys.optflags &= ~FLAG_b;
toys.optflags |= FLAG_f;
}
}
// Generic signal handler real handling is done in main funcrion.
static void signal_handler(int sig)
{
dbg("Caught signal: %d\n", sig);
switch (sig) {
case SIGUSR1:
dbg("SIGUSR1.\n");
if (TT.state == DHCP6RELEASE || TT.state == DHCP6REQUEST ) {
TT.state = DHCP6SOLICIT;
set_timeout(0);
return;
}
dbg("SIGUSR1 sending renew.\n");
send_msg(DHCP6RENEW);
TT.state = DHCP6RENEW;
TT.retries = 0;
set_timeout(0);
break;
case SIGUSR2:
dbg("SIGUSR2.\n");
if (TT.state == DHCP6RELEASE) return;
if (TT.state != DHCP6CONFIRM ) return;
dbg("SIGUSR2 sending release.\n");
send_msg(DHCP6RELEASE);
TT.state = DHCP6RELEASE;
TT.retries = 0;
set_timeout(0);
break;
case SIGTERM:
case SIGINT:
dbg((sig == SIGTERM)?"SIGTERM.\n":"SIGINT.\n");
if ((toys.optflags & FLAG_R) && TT.state == DHCP6CONFIRM)
send_msg(DHCP6RELEASE);
if(sig == SIGINT) exit(0);
break;
default: break;
}
}
// signal setup for SIGUSR1 SIGUSR2 SIGTERM
static int setup_signal()
{
signal(SIGUSR1, signal_handler);
signal(SIGUSR2, signal_handler);
signal(SIGTERM, signal_handler);
signal(SIGINT, signal_handler);
return 0;
}
void dhcp6_main(void)
{
struct sockaddr_in6 sinaddr6;
int constone = 1;
fd_set rfds;
srand(time(NULL));
setlinebuf(stdout);
dbg = dummy;
TT.state = DHCP6SOLICIT;
if (toys.optflags & FLAG_v) dbg = logit;
if (!TT.interface_name) TT.interface_name = "eth0";
if (toys.optflags & FLAG_p) write_pid(TT.pidfile);
if (!TT.retry) TT.retry = 3;
if (!TT.timeout) TT.timeout = 3;
if (!TT.errortimeout) TT.errortimeout = 20;
if (toys.optflags & FLAG_S) {
openlog("DHCP6 :", LOG_PID, LOG_DAEMON);
dbg = logit;
}
dbg("Interface: %s\n", TT.interface_name);
dbg("pid file: %s\n", TT.pidfile);
dbg("Retry count: %d\n", TT.retry);
dbg("Timeout : %d\n", TT.timeout);
dbg("Error timeout: %d\n", TT.errortimeout);
setup_signal();
TT.sock1 = xsocket(PF_INET6, SOCK_DGRAM, 0);
memset(&sinaddr6, 0, sizeof(sinaddr6));
sinaddr6.sin6_family = AF_INET6;
sinaddr6.sin6_port = htons(DHCPC_CLIENT_PORT);
sinaddr6.sin6_scope_id = if_nametoindex(TT.interface_name);
sinaddr6.sin6_addr = in6addr_any ;
xsetsockopt(TT.sock1, SOL_SOCKET, SO_REUSEADDR, &constone, sizeof(constone));
if (bind(TT.sock1, (struct sockaddr *)&sinaddr6, sizeof(sinaddr6))) {
xclose(TT.sock1);
error_exit("bind failed");
}
mode_raw();
set_timeout(0);
for (;;) {
int maxfd = TT.sock;
if (TT.sock >= 0) FD_SET(TT.sock, &rfds);
TT.retval = 0;
if ((TT.retval = select(maxfd + 1, &rfds, NULL, NULL, &TT.tv)) < 0) {
if(errno == EINTR) continue;
perror_exit("Error in select");
}
if (!TT.retval) {
if (TT.state == DHCP6SOLICIT || TT.state == DHCP6CONFIRM) {
dbg("State is solicit, sending solicit packet\n");
run_script(NULL, "deconfig");
send_msg(DHCP6SOLICIT);
TT.state = DHCP6SOLICIT;
TT.retries++;
if(TT.retries > TT.retry) set_timeout(TT.errortimeout);
else if (TT.retries == TT.retry) {
dbg("State is solicit, retry count is max.\n");
lease_fail();
set_timeout(TT.errortimeout);
} else set_timeout(TT.timeout);
continue;
} else if (TT.state == DHCP6REQUEST || TT.state == DHCP6RENEW ||
TT.state == DHCP6RELEASE) {
dbg("State is %d , sending packet\n", TT.state);
send_msg(TT.state);
TT.retries++;
if (TT.retries > TT.retry) set_timeout(TT.errortimeout);
else if (TT.retries == TT.retry) {
lease_fail();
set_timeout(TT.errortimeout);
} else set_timeout(TT.timeout);
continue;
}
} else if (FD_ISSET(TT.sock, &rfds)) {
if ((TT.status = read(TT.sock, toybuf, sizeof(toybuf))) <= 0) continue;
mymsg = (dhcp6_raw_t*)toybuf;
if (ntohs(mymsg->udph.dest) == 546 &&
!memcmp(mymsg->dhcp6.transaction_id, TT.transction_id, 3)) {
if (TT.state == DHCP6SOLICIT) {
if (mymsg->dhcp6.msgtype == DHCP6ADVERTISE ) {
if (!validate_ids()) {
dbg("Invalid id recieved, solicit.\n");
TT.state = DHCP6SOLICIT;
continue;
}
dbg("Got reply to request or solicit.\n");
TT.retries = 0;
set_timeout(0);
TT.request_length = TT.status - ((char*)&mymsg->dhcp6 - (char*)mymsg);
memcpy((uint8_t*)&mesg, &mymsg->dhcp6, TT.request_length);
parse_ia_na(mesg.options, TT.request_length);
dbg("Status code:%d\n", dhcp_data.status_code);
inet_ntop(AF_INET6, dhcp_data.ipaddr, toybuf, INET6_ADDRSTRLEN);
dbg("Advertiesed IP: %s\n", toybuf);
TT.state = DHCP6REQUEST;
} else {
dbg("Invalid solicit.\n");
continue;
}
} else if (TT.state == DHCP6REQUEST || TT.state == DHCP6RENEW ) {
if (mymsg->dhcp6.msgtype == DHCP6REPLY) {
if (!validate_ids()) {
dbg("Invalid id recieved, %d.\n", TT.state);
TT.state = DHCP6REQUEST;
continue;
}
dbg("Got reply to request or renew.\n");
TT.request_length = TT.status - ((char*)&mymsg->dhcp6 - (char*)mymsg);
memcpy((uint8_t*)&mesg, &mymsg->dhcp6, TT.request_length);
parse_ia_na(mymsg->dhcp6.options, TT.request_length);
dbg("Status code:%d\n", dhcp_data.status_code);
inet_ntop(AF_INET6, dhcp_data.ipaddr, toybuf, INET6_ADDRSTRLEN);
dbg("Got IP: %s\n", toybuf);
TT.retries = 0;
run_script(&dhcp_data, (TT.state == DHCP6REQUEST) ?
"request" : "renew");
if (toys.optflags & FLAG_q) {
if (toys.optflags & FLAG_R) send_msg(DHCP6RELEASE);
break;
}
TT.state = DHCP6CONFIRM;
set_timeout((dhcp_data.va_lf)?dhcp_data.va_lf:INT_MAX);
dbg("Setting timeout to intmax.");
if (TT.state == DHCP6REQUEST || !(toys.optflags & FLAG_f)) {
dbg("Making it a daemon\n");
if (daemon(0,0)) perror_exit("daemonize");
toys.optflags |= FLAG_f;
if (toys.optflags & FLAG_p) write_pid(TT.pidfile);
}
dbg("Making it a foreground.\n");
continue;
} else {
dbg("Invalid reply.\n");
continue;
}
} else if (TT.state == DHCP6RELEASE) {
dbg("Got reply to release.\n");
run_script(NULL, "release");
set_timeout(INT_MAX);
}
}
}
}
xclose(TT.sock1);
xclose(TT.sock);
}