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3293bc1469
busybox/networking/udhcp/d6_dhcpc.c
Denys Vlasenko 3293bc1469 udhcpd: fix "not dying on SIGTERM" 
Fixes:
	commit 52a515d187
	"udhcp: use poll() instead of select()"
	Feb 16 2017

udhcp_sp_read() is meant to check whether signal pipe indeed has some data to read.
In the above commit, it was changed as follows:

-	if (!FD_ISSET(signal_pipe.rd, rfds))
+	if (!pfds[0].revents)
		return 0;

The problem is, the check was working for select() purely by accident.
Caught signal interrupts select()/poll() syscalls, they return with EINTR
(regardless of SA_RESTART flag in sigaction). _Then_ signal handler is invoked.
IOW: they can't see any changes to fd state caused by signal haldler
(in our case, signal handler makes signal pipe ready to be read).

For select(), it means that rfds[] bit array is unmodified, bit of signal
pipe's read fd is still set, and the above check "works": it thinks select()
says there is data to read.

This accident does not work for poll(): .revents stays clear, and we do not
try reading signal pipe as we should. In udhcpd, we fall through and block
in socket read. Further SIGTERM signals simply cause socket read to be
interrupted and then restarted (since SIGTERM handler has SA_RESTART=1).

Fixing this as follows: remove the check altogether. Set signal pipe read fd
to nonblocking mode. Always read it in udhcp_sp_read().
If read fails, assume it's EAGAIN and return 0 ("no signal seen").

udhcpd avoids reading signal pipe on every recvd packet by looping if EINTR
(using safe_poll()) - thus ensuring we have correct .revents for all fds -
and calling udhcp_sp_read() only if pfds[0].revents!=0.

udhcpc performs much fewer reads (typically it sleeps >99.999% of the time),
there is no need to optimize it: can call udhcp_sp_read() after each poll
unconditionally.

To robustify socket reads, unconditionally set pfds[1].revents=0
in udhcp_sp_fd_set() (which is before poll), and check it before reading
network socket in udhcpd.

TODO:
This might still fail: if pfds[1].revents=POLLIN, socket read may still block.
There are rare cases when select/poll indicates that data can be read,
but then actual read still blocks (one such case is UDP packets with
wrong checksum). General advise is, if you use a poll/select loop,
keep all your fds nonblocking.
Maybe we should also do that to our network sockets?

function                                             old     new   delta
udhcp_sp_setup                                        55      65     +10
udhcp_sp_fd_set                                       54      60      +6
udhcp_sp_read                                         46      36     -10
udhcpd_main                                         1451    1437     -14
udhcpc_main                                         2723    2708     -15
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/3 up/down: 16/-39)            Total: -23 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-10 19:34:39 +01:00

1708 lines
56 KiB
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/* vi: set sw=4 ts=4: */
/*
* DHCPv6 client.
*
* WARNING: THIS CODE IS INCOMPLETE.
*
* Copyright (C) 2011-2017 Denys Vlasenko.
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config UDHCPC6
//config: bool "udhcpc6"
//config: default n # not yet ready
//config: depends on FEATURE_IPV6
//config: help
//config: udhcpc6 is a DHCPv6 client
//config:
//config:config FEATURE_UDHCPC6_RFC3646
//config: bool "Support RFC 3646 (DNS server and search list)"
//config: default y
//config: depends on UDHCPC6
//config: help
//config: List of DNS servers and domain search list can be requested with
//config: "-O dns" and "-O search". If server gives these values,
//config: they will be set in environment variables "dns" and "search".
//config:
//config:config FEATURE_UDHCPC6_RFC4704
//config: bool "Support RFC 4704 (Client FQDN)"
//config: default y
//config: depends on UDHCPC6
//config: help
//config: You can request FQDN to be given by server using "-O fqdn".
//config:
//config:config FEATURE_UDHCPC6_RFC4833
//config: bool "Support RFC 4833 (Timezones)"
//config: default y
//config: depends on UDHCPC6
//config: help
//config: You can request POSIX timezone with "-O tz" and timezone name
//config: with "-O timezone".
//applet:IF_UDHCPC6(APPLET(udhcpc6, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_UDHCPC6) += d6_dhcpc.o d6_packet.o d6_socket.o common.o socket.o signalpipe.o
//kbuild:lib-$(CONFIG_FEATURE_UDHCPC6_RFC3646) += domain_codec.o
//kbuild:lib-$(CONFIG_FEATURE_UDHCPC6_RFC4704) += domain_codec.o
#include <syslog.h>
/* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
#define WANT_PIDFILE 1
#include "common.h"
#include "dhcpd.h"
#include "dhcpc.h"
#include "d6_common.h"
#include <netinet/if_ether.h>
#include <netpacket/packet.h>
#include <linux/filter.h>
/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
static const struct dhcp_optflag d6_optflags[] = {
#if ENABLE_FEATURE_UDHCPC6_RFC3646
{ OPTION_6RD | OPTION_LIST | OPTION_REQ, D6_OPT_DNS_SERVERS },
{ OPTION_DNS_STRING | OPTION_LIST | OPTION_REQ, D6_OPT_DOMAIN_LIST },
#endif
#if ENABLE_FEATURE_UDHCPC6_RFC4704
{ OPTION_DNS_STRING, D6_OPT_CLIENT_FQDN },
#endif
#if ENABLE_FEATURE_UDHCPC6_RFC4833
{ OPTION_STRING, D6_OPT_TZ_POSIX },
{ OPTION_STRING, D6_OPT_TZ_NAME },
#endif
{ 0, 0 }
};
/* Must match d6_optflags[] order */
static const char d6_option_strings[] ALIGN1 =
#if ENABLE_FEATURE_UDHCPC6_RFC3646
"dns" "\0" /* D6_OPT_DNS_SERVERS */
"search" "\0" /* D6_OPT_DOMAIN_LIST */
#endif
#if ENABLE_FEATURE_UDHCPC6_RFC4704
"fqdn" "\0" /* D6_OPT_CLIENT_FQDN */
#endif
#if ENABLE_FEATURE_UDHCPC6_RFC4833
"tz" "\0" /* D6_OPT_TZ_POSIX */
"timezone" "\0" /* D6_OPT_TZ_NAME */
#endif
"\0";
#if ENABLE_LONG_OPTS
static const char udhcpc6_longopts[] ALIGN1 =
"interface\0" Required_argument "i"
"now\0" No_argument "n"
"pidfile\0" Required_argument "p"
"quit\0" No_argument "q"
"release\0" No_argument "R"
"request\0" Required_argument "r"
"requestprefix\0" No_argument "d"
"script\0" Required_argument "s"
"timeout\0" Required_argument "T"
"retries\0" Required_argument "t"
"tryagain\0" Required_argument "A"
"syslog\0" No_argument "S"
"request-option\0" Required_argument "O"
"no-default-options\0" No_argument "o"
"foreground\0" No_argument "f"
USE_FOR_MMU(
"background\0" No_argument "b"
)
/// IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
;
#endif
/* Must match getopt32 option string order */
enum {
OPT_i = 1 << 0,
OPT_n = 1 << 1,
OPT_p = 1 << 2,
OPT_q = 1 << 3,
OPT_R = 1 << 4,
OPT_r = 1 << 5,
OPT_s = 1 << 6,
OPT_T = 1 << 7,
OPT_t = 1 << 8,
OPT_S = 1 << 9,
OPT_A = 1 << 10,
OPT_O = 1 << 11,
OPT_o = 1 << 12,
OPT_x = 1 << 13,
OPT_f = 1 << 14,
OPT_d = 1 << 15,
/* The rest has variable bit positions, need to be clever */
OPTBIT_d = 15,
USE_FOR_MMU( OPTBIT_b,)
///IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
///IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
};
#if ENABLE_FEATURE_UDHCPC6_RFC4704
static const char opt_fqdn_req[] = {
(D6_OPT_CLIENT_FQDN >> 8), (D6_OPT_CLIENT_FQDN & 0xff),
0, 2, /* optlen */
0, /* flags: */
/* S=0: server SHOULD NOT perform AAAA RR updates */
/* O=0: client MUST set this bit to 0 */
/* N=0: server SHOULD perform updates (PTR RR only in our case, since S=0) */
0 /* empty DNS-encoded name */
};
#endif
/*** Utility functions ***/
static void *d6_find_option(uint8_t *option, uint8_t *option_end, unsigned code)
{
/* "length minus 4" */
int len_m4 = option_end - option - 4;
while (len_m4 >= 0) {
/* Next option's len is too big? */
if (option[3] > len_m4)
return NULL; /* yes. bogus packet! */
/* So far we treat any opts with code >255
* or len >255 as bogus, and stop at once.
* This simplifies big-endian handling.
*/
if (option[0] != 0 || option[2] != 0)
return NULL;
/* Option seems to be valid */
/* Does its code match? */
if (option[1] == code)
return option; /* yes! */
len_m4 -= option[3] + 4;
option += option[3] + 4;
}
return NULL;
}
static void *d6_copy_option(uint8_t *option, uint8_t *option_end, unsigned code)
{
uint8_t *opt = d6_find_option(option, option_end, code);
if (!opt)
return opt;
return xmemdup(opt, opt[3] + 4);
}
/*** Script execution code ***/
static char** new_env(void)
{
client6_data.env_ptr = xrealloc_vector(client6_data.env_ptr, 3, client6_data.env_idx);
return &client6_data.env_ptr[client6_data.env_idx++];
}
/* put all the parameters into the environment */
static void option_to_env(uint8_t *option, uint8_t *option_end)
{
#if ENABLE_FEATURE_UDHCPC6_RFC3646
int addrs, option_offset;
#endif
/* "length minus 4" */
int len_m4 = option_end - option - 4;
while (len_m4 >= 0) {
uint32_t v32;
char ipv6str[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")];
if (option[0] != 0 || option[2] != 0)
break;
/* Check if option-length exceeds size of option */
if (option[3] > len_m4)
break;
switch (option[1]) {
//case D6_OPT_CLIENTID:
//case D6_OPT_SERVERID:
case D6_OPT_IA_NA:
case D6_OPT_IA_PD:
option_to_env(option + 16, option + 4 + option[3]);
break;
//case D6_OPT_IA_TA:
case D6_OPT_IAADDR:
/* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | OPTION_IAADDR | option-len |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* | IPv6 address |
* | |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | preferred-lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | valid-lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
sprint_nip6(ipv6str, option + 4);
*new_env() = xasprintf("ipv6=%s", ipv6str);
move_from_unaligned32(v32, option + 4 + 16 + 4);
*new_env() = xasprintf("lease=%u", (unsigned)v32);
break;
//case D6_OPT_ORO:
//case D6_OPT_PREFERENCE:
//case D6_OPT_ELAPSED_TIME:
//case D6_OPT_RELAY_MSG:
//case D6_OPT_AUTH:
//case D6_OPT_UNICAST:
//case D6_OPT_STATUS_CODE:
//case D6_OPT_RAPID_COMMIT:
//case D6_OPT_USER_CLASS:
//case D6_OPT_VENDOR_CLASS:
//case D6_OPT_VENDOR_OPTS:
//case D6_OPT_INTERFACE_ID:
//case D6_OPT_RECONF_MSG:
//case D6_OPT_RECONF_ACCEPT:
case D6_OPT_IAPREFIX:
/* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | OPTION_IAPREFIX | option-length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | preferred-lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | valid-lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | prefix-length | |
* +-+-+-+-+-+-+-+-+ IPv6 prefix |
* | (16 octets) |
* | |
* | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* +-+-+-+-+-+-+-+-+
*/
move_from_unaligned32(v32, option + 4 + 4);
*new_env() = xasprintf("ipv6prefix_lease=%u", (unsigned)v32);
sprint_nip6(ipv6str, option + 4 + 4 + 4 + 1);
*new_env() = xasprintf("ipv6prefix=%s/%u", ipv6str, (unsigned)(option[4 + 4 + 4]));
break;
#if ENABLE_FEATURE_UDHCPC6_RFC3646
case D6_OPT_DNS_SERVERS: {
char *dlist;
/* Make sure payload-size is a multiple of 16 */
if ((option[3] & 0x0f) != 0)
break;
/* Get the number of addresses on the option */
addrs = option[3] >> 4;
/* Setup environment variable */
*new_env() = dlist = xmalloc(4 + addrs * 40 - 1);
dlist = stpcpy(dlist, "dns=");
option_offset = 0;
while (addrs--) {
sprint_nip6(dlist, option + 4 + option_offset);
dlist += 39;
option_offset += 16;
if (addrs)
*dlist++ = ' ';
}
break;
}
case D6_OPT_DOMAIN_LIST: {
char *dlist;
dlist = dname_dec(option + 4, (option[2] << 8) | option[3], "search=");
if (!dlist)
break;
*new_env() = dlist;
break;
}
#endif
#if ENABLE_FEATURE_UDHCPC6_RFC4704
case D6_OPT_CLIENT_FQDN: {
char *dlist;
if (option[3] == 0)
break;
/* Work around broken ISC DHCPD6.
* ISC DHCPD6 does not implement RFC 4704 correctly: It says the first
* byte of option-payload should contain flags where the bits 7-3 are
* reserved for future use and MUST be zero. Instead ISC DHCPD6 just
* writes the entire FQDN as string to option-payload. We assume a
* broken server here if any of the reserved bits are set.
*/
if (option[4] & 0xf8) {
*new_env() = xasprintf("fqdn=%.*s", (int)option[3], (char*)option + 4);
break;
}
dlist = dname_dec(option + 5, (/*(option[2] << 8) |*/ option[3]) - 1, "fqdn=");
if (!dlist)
break;
*new_env() = dlist;
break;
}
#endif
#if ENABLE_FEATURE_UDHCPC6_RFC4833
/* RFC 4833 Timezones */
case D6_OPT_TZ_POSIX:
*new_env() = xasprintf("tz=%.*s", (int)option[3], (char*)option + 4);
break;
case D6_OPT_TZ_NAME:
*new_env() = xasprintf("tz_name=%.*s", (int)option[3], (char*)option + 4);
break;
#endif
}
len_m4 -= 4 + option[3];
option += 4 + option[3];
}
}
static char **fill_envp(struct d6_packet *packet)
{
char **envp, **curr;
client6_data.env_ptr = NULL;
client6_data.env_idx = 0;
*new_env() = xasprintf("interface=%s", client_config.interface);
if (packet)
option_to_env(packet->d6_options, packet->d6_options + sizeof(packet->d6_options));
envp = curr = client6_data.env_ptr;
while (*curr)
putenv(*curr++);
return envp;
}
/* Call a script with a par file and env vars */
static void d6_run_script(struct d6_packet *packet, const char *name)
{
char **envp, **curr;
char *argv[3];
envp = fill_envp(packet);
/* call script */
log1("executing %s %s", client_config.script, name);
argv[0] = (char*) client_config.script;
argv[1] = (char*) name;
argv[2] = NULL;
spawn_and_wait(argv);
for (curr = envp; *curr; curr++) {
log2(" %s", *curr);
bb_unsetenv_and_free(*curr);
}
free(envp);
}
/*** Sending/receiving packets ***/
static ALWAYS_INLINE uint32_t random_xid(void)
{
uint32_t t = rand() & htonl(0x00ffffff);
return t;
}
/* Initialize the packet with the proper defaults */
static uint8_t *init_d6_packet(struct d6_packet *packet, char type, uint32_t xid)
{
struct d6_option *clientid;
memset(packet, 0, sizeof(*packet));
packet->d6_xid32 = xid;
packet->d6_msg_type = type;
clientid = (void*)client_config.clientid;
return mempcpy(packet->d6_options, clientid, clientid->len + 2+2);
}
static uint8_t *add_d6_client_options(uint8_t *ptr)
{
uint8_t *start = ptr;
unsigned option;
ptr += 4;
for (option = 1; option < 256; option++) {
if (client_config.opt_mask[option >> 3] & (1 << (option & 7))) {
ptr[0] = (option >> 8);
ptr[1] = option;
ptr += 2;
}
}
if ((ptr - start - 4) != 0) {
start[0] = (D6_OPT_ORO >> 8);
start[1] = D6_OPT_ORO;
start[2] = ((ptr - start - 4) >> 8);
start[3] = (ptr - start - 4);
} else
ptr = start;
#if ENABLE_FEATURE_UDHCPC6_RFC4704
ptr = mempcpy(ptr, &opt_fqdn_req, sizeof(opt_fqdn_req));
#endif
/* Add -x options if any */
//...
return ptr;
}
static int d6_mcast_from_client_config_ifindex(struct d6_packet *packet, uint8_t *end)
{
static const uint8_t FF02__1_2[16] = {
0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02,
};
return d6_send_raw_packet(
packet, (end - (uint8_t*) packet),
/*src*/ &client6_data.ll_ip6, CLIENT_PORT6,
/*dst*/ (struct in6_addr*)FF02__1_2, SERVER_PORT6, MAC_BCAST_ADDR,
client_config.ifindex
);
}
/* Milticast a DHCPv6 Solicit packet to the network, with an optionally requested IP.
*
* RFC 3315 17.1.1. Creation of Solicit Messages
*
* The client MUST include a Client Identifier option to identify itself
* to the server. The client includes IA options for any IAs to which
* it wants the server to assign addresses. The client MAY include
* addresses in the IAs as a hint to the server about addresses for
* which the client has a preference. ...
*
* The client uses IA_NA options to request the assignment of non-
* temporary addresses and uses IA_TA options to request the assignment
* of temporary addresses. Either IA_NA or IA_TA options, or a
* combination of both, can be included in DHCP messages.
*
* The client SHOULD include an Option Request option (see section 22.7)
* to indicate the options the client is interested in receiving. The
* client MAY additionally include instances of those options that are
* identified in the Option Request option, with data values as hints to
* the server about parameter values the client would like to have
* returned.
*
* The client includes a Reconfigure Accept option (see section 22.20)
* if the client is willing to accept Reconfigure messages from the
* server.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CLIENTID | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. DUID .
. (variable length) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IA_NA | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. IA_NA-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IAADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. IAaddr-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ORO | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| requested-option-code-1 | requested-option-code-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RECONF_ACCEPT | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
/* NOINLINE: limit stack usage in caller */
static NOINLINE int send_d6_discover(uint32_t xid, struct in6_addr *requested_ipv6)
{
struct d6_packet packet;
uint8_t *opt_ptr;
unsigned len;
/* Fill in: msg type, client id */
opt_ptr = init_d6_packet(&packet, D6_MSG_SOLICIT, xid);
/* Create new IA_NA, optionally with included IAADDR with requested IP */
free(client6_data.ia_na);
client6_data.ia_na = NULL;
if (option_mask32 & OPT_r) {
len = requested_ipv6 ? 2+2+4+4+4 + 2+2+16+4+4 : 2+2+4+4+4;
client6_data.ia_na = xzalloc(len);
client6_data.ia_na->code = D6_OPT_IA_NA;
client6_data.ia_na->len = len - 4;
*(uint32_t*)client6_data.ia_na->data = rand(); /* IAID */
if (requested_ipv6) {
struct d6_option *iaaddr = (void*)(client6_data.ia_na->data + 4+4+4);
iaaddr->code = D6_OPT_IAADDR;
iaaddr->len = 16+4+4;
memcpy(iaaddr->data, requested_ipv6, 16);
}
opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, len);
}
/* IA_PD */
free(client6_data.ia_pd);
client6_data.ia_pd = NULL;
if (option_mask32 & OPT_d) {
len = 2+2+4+4+4;
client6_data.ia_pd = xzalloc(len);
client6_data.ia_pd->code = D6_OPT_IA_PD;
client6_data.ia_pd->len = len - 4;
*(uint32_t*)client6_data.ia_pd->data = rand(); /* IAID */
opt_ptr = mempcpy(opt_ptr, client6_data.ia_pd, len);
}
/* Add options:
* "param req" option according to -O, options specified with -x
*/
opt_ptr = add_d6_client_options(opt_ptr);
bb_error_msg("sending %s", "discover");
return d6_mcast_from_client_config_ifindex(&packet, opt_ptr);
}
/* Multicast a DHCPv6 request message
*
* RFC 3315 18.1.1. Creation and Transmission of Request Messages
*
* The client uses a Request message to populate IAs with addresses and
* obtain other configuration information. The client includes one or
* more IA options in the Request message. The server then returns
* addresses and other information about the IAs to the client in IA
* options in a Reply message.
*
* The client generates a transaction ID and inserts this value in the
* "transaction-id" field.
*
* The client places the identifier of the destination server in a
* Server Identifier option.
*
* The client MUST include a Client Identifier option to identify itself
* to the server. The client adds any other appropriate options,
* including one or more IA options (if the client is requesting that
* the server assign it some network addresses).
*
* The client MUST include an Option Request option (see section 22.7)
* to indicate the options the client is interested in receiving. The
* client MAY include options with data values as hints to the server
* about parameter values the client would like to have returned.
*
* The client includes a Reconfigure Accept option (see section 22.20)
* indicating whether or not the client is willing to accept Reconfigure
* messages from the server.
*/
/* NOINLINE: limit stack usage in caller */
static NOINLINE int send_d6_select(uint32_t xid)
{
struct d6_packet packet;
uint8_t *opt_ptr;
/* Fill in: msg type, client id */
opt_ptr = init_d6_packet(&packet, D6_MSG_REQUEST, xid);
/* server id */
opt_ptr = mempcpy(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2);
/* IA NA (contains requested IP) */
if (client6_data.ia_na)
opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
/* IA PD */
if (client6_data.ia_pd)
opt_ptr = mempcpy(opt_ptr, client6_data.ia_pd, client6_data.ia_pd->len + 2+2);
/* Add options:
* "param req" option according to -O, options specified with -x
*/
opt_ptr = add_d6_client_options(opt_ptr);
bb_error_msg("sending %s", "select");
return d6_mcast_from_client_config_ifindex(&packet, opt_ptr);
}
/* Unicast or broadcast a DHCP renew message
*
* RFC 3315 18.1.3. Creation and Transmission of Renew Messages
*
* To extend the valid and preferred lifetimes for the addresses
* associated with an IA, the client sends a Renew message to the server
* from which the client obtained the addresses in the IA containing an
* IA option for the IA. The client includes IA Address options in the
* IA option for the addresses associated with the IA. The server
* determines new lifetimes for the addresses in the IA according to the
* administrative configuration of the server. The server may also add
* new addresses to the IA. The server may remove addresses from the IA
* by setting the preferred and valid lifetimes of those addresses to
* zero.
*
* The server controls the time at which the client contacts the server
* to extend the lifetimes on assigned addresses through the T1 and T2
* parameters assigned to an IA.
*
* At time T1 for an IA, the client initiates a Renew/Reply message
* exchange to extend the lifetimes on any addresses in the IA. The
* client includes an IA option with all addresses currently assigned to
* the IA in its Renew message.
*
* If T1 or T2 is set to 0 by the server (for an IA_NA) or there are no
* T1 or T2 times (for an IA_TA), the client may send a Renew or Rebind
* message, respectively, at the client's discretion.
*
* The client sets the "msg-type" field to RENEW. The client generates
* a transaction ID and inserts this value in the "transaction-id"
* field.
*
* The client places the identifier of the destination server in a
* Server Identifier option.
*
* The client MUST include a Client Identifier option to identify itself
* to the server. The client adds any appropriate options, including
* one or more IA options. The client MUST include the list of
* addresses the client currently has associated with the IAs in the
* Renew message.
*
* The client MUST include an Option Request option (see section 22.7)
* to indicate the options the client is interested in receiving. The
* client MAY include options with data values as hints to the server
* about parameter values the client would like to have returned.
*/
/* NOINLINE: limit stack usage in caller */
static NOINLINE int send_d6_renew(uint32_t xid, struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
{
struct d6_packet packet;
uint8_t *opt_ptr;
/* Fill in: msg type, client id */
opt_ptr = init_d6_packet(&packet, DHCPREQUEST, xid);
/* server id */
opt_ptr = mempcpy(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2);
/* IA NA (contains requested IP) */
if (client6_data.ia_na)
opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
/* IA PD */
if (client6_data.ia_pd)
opt_ptr = mempcpy(opt_ptr, client6_data.ia_pd, client6_data.ia_pd->len + 2+2);
/* Add options:
* "param req" option according to -O, options specified with -x
*/
opt_ptr = add_d6_client_options(opt_ptr);
bb_error_msg("sending %s", "renew");
if (server_ipv6) {
return d6_send_kernel_packet(
&packet, (opt_ptr - (uint8_t*) &packet),
our_cur_ipv6, CLIENT_PORT6,
server_ipv6, SERVER_PORT6,
client_config.ifindex
/* TODO? send_flags: MSG_DONTROUTE (see IPv4 code for reason why) */
);
}
return d6_mcast_from_client_config_ifindex(&packet, opt_ptr);
}
/* Unicast a DHCP release message */
static int send_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
{
struct d6_packet packet;
uint8_t *opt_ptr;
/* Fill in: msg type, client id */
opt_ptr = init_d6_packet(&packet, D6_MSG_RELEASE, random_xid());
/* server id */
opt_ptr = mempcpy(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2);
/* IA NA (contains our current IP) */
if (client6_data.ia_na)
opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
/* IA PD */
if (client6_data.ia_pd)
opt_ptr = mempcpy(opt_ptr, client6_data.ia_pd, client6_data.ia_pd->len + 2+2);
bb_error_msg("sending %s", "release");
return d6_send_kernel_packet(
&packet, (opt_ptr - (uint8_t*) &packet),
our_cur_ipv6, CLIENT_PORT6,
server_ipv6, SERVER_PORT6,
client_config.ifindex
);
}
/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
/* NOINLINE: limit stack usage in caller */
static NOINLINE int d6_recv_raw_packet(struct in6_addr *peer_ipv6, struct d6_packet *d6_pkt, int fd)
{
int bytes;
struct ip6_udp_d6_packet packet;
bytes = safe_read(fd, &packet, sizeof(packet));
if (bytes < 0) {
log1("packet read error, ignoring");
/* NB: possible down interface, etc. Caller should pause. */
return bytes; /* returns -1 */
}
if (bytes < (int) (sizeof(packet.ip6) + sizeof(packet.udp))) {
log1("packet is too short, ignoring");
return -2;
}
if (bytes < sizeof(packet.ip6) + ntohs(packet.ip6.ip6_plen)) {
/* packet is bigger than sizeof(packet), we did partial read */
log1("oversized packet, ignoring");
return -2;
}
/* ignore any extra garbage bytes */
bytes = sizeof(packet.ip6) + ntohs(packet.ip6.ip6_plen);
/* make sure its the right packet for us, and that it passes sanity checks */
if (packet.ip6.ip6_nxt != IPPROTO_UDP
|| (packet.ip6.ip6_vfc >> 4) != 6
|| packet.udp.dest != htons(CLIENT_PORT6)
/* || bytes > (int) sizeof(packet) - can't happen */
|| packet.udp.len != packet.ip6.ip6_plen
) {
log1("unrelated/bogus packet, ignoring");
return -2;
}
//How to do this for ipv6?
// /* verify UDP checksum. IP header has to be modified for this */
// memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
// /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
// packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
// check = packet.udp.check;
// packet.udp.check = 0;
// if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
// log1("packet with bad UDP checksum received, ignoring");
// return -2;
// }
if (peer_ipv6)
*peer_ipv6 = packet.ip6.ip6_src; /* struct copy */
log1("received %s", "a packet");
d6_dump_packet(&packet.data);
bytes -= sizeof(packet.ip6) + sizeof(packet.udp);
memcpy(d6_pkt, &packet.data, bytes);
return bytes;
}
/*** Main ***/
static int sockfd = -1;
#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static smallint listen_mode;
/* initial state: (re)start DHCP negotiation */
#define INIT_SELECTING 0
/* discover was sent, DHCPOFFER reply received */
#define REQUESTING 1
/* select/renew was sent, DHCPACK reply received */
#define BOUND 2
/* half of lease passed, want to renew it by sending unicast renew requests */
#define RENEWING 3
/* renew requests were not answered, lease is almost over, send broadcast renew */
#define REBINDING 4
/* manually requested renew (SIGUSR1) */
#define RENEW_REQUESTED 5
/* release, possibly manually requested (SIGUSR2) */
#define RELEASED 6
static smallint state;
static int d6_raw_socket(int ifindex)
{
int fd;
struct sockaddr_ll sock;
/*
* Comment:
*
* I've selected not to see LL header, so BPF doesn't see it, too.
* The filter may also pass non-IP and non-ARP packets, but we do
* a more complete check when receiving the message in userspace.
*
* and filter shamelessly stolen from:
*
* http://www.flamewarmaster.de/software/dhcpclient/
*
* There are a few other interesting ideas on that page (look under
* "Motivation"). Use of netlink events is most interesting. Think
* of various network servers listening for events and reconfiguring.
* That would obsolete sending HUP signals and/or make use of restarts.
*
* Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
* License: GPL v2.
*
* TODO: make conditional?
*/
#if 0
static const struct sock_filter filter_instr[] = {
/* load 9th byte (protocol) */
BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
/* jump to L1 if it is IPPROTO_UDP, else to L4 */
BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
/* L1: load halfword from offset 6 (flags and frag offset) */
BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
/* jump to L4 if any bits in frag offset field are set, else to L2 */
BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
/* L2: skip IP header (load index reg with header len) */
BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
/* load udp destination port from halfword[header_len + 2] */
BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
/* jump to L3 if udp dport is CLIENT_PORT6, else to L4 */
BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
/* L3: accept packet */
BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
/* L4: discard packet */
BPF_STMT(BPF_RET|BPF_K, 0),
};
static const struct sock_fprog filter_prog = {
.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
/* casting const away: */
.filter = (struct sock_filter *) filter_instr,
};
#endif
log2("opening raw socket on ifindex %d", ifindex);
fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6));
log2("got raw socket fd %d", fd);
memset(&sock, 0, sizeof(sock)); /* let's be deterministic */
sock.sll_family = AF_PACKET;
sock.sll_protocol = htons(ETH_P_IPV6);
sock.sll_ifindex = ifindex;
/*sock.sll_hatype = ARPHRD_???;*/
/*sock.sll_pkttype = PACKET_???;*/
/*sock.sll_halen = ???;*/
/*sock.sll_addr[8] = ???;*/
xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
#if 0
if (CLIENT_PORT6 == 546) {
/* Use only if standard port is in use */
/* Ignoring error (kernel may lack support for this) */
if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
sizeof(filter_prog)) >= 0)
log1("attached filter to raw socket fd %d", fd); // log?
}
#endif
log1("created raw socket");
return fd;
}
static void change_listen_mode(int new_mode)
{
log1("entering listen mode: %s",
new_mode != LISTEN_NONE
? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
: "none"
);
listen_mode = new_mode;
if (sockfd >= 0) {
close(sockfd);
sockfd = -1;
}
if (new_mode == LISTEN_KERNEL)
sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT6, client_config.interface);
else if (new_mode != LISTEN_NONE)
sockfd = d6_raw_socket(client_config.ifindex);
/* else LISTEN_NONE: sockfd stays closed */
}
/* Called only on SIGUSR1 */
static void perform_renew(void)
{
bb_error_msg("performing DHCP renew");
switch (state) {
case BOUND:
change_listen_mode(LISTEN_KERNEL);
case RENEWING:
case REBINDING:
state = RENEW_REQUESTED;
break;
case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
d6_run_script(NULL, "deconfig");
case REQUESTING:
case RELEASED:
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
break;
case INIT_SELECTING:
break;
}
}
static void perform_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
{
/* send release packet */
if (state == BOUND
|| state == RENEWING
|| state == REBINDING
|| state == RENEW_REQUESTED
) {
bb_error_msg("unicasting a release");
send_d6_release(server_ipv6, our_cur_ipv6); /* unicast */
}
bb_error_msg("entering released state");
/*
* We can be here on: SIGUSR2,
* or on exit (SIGTERM) and -R "release on quit" is specified.
* Users requested to be notified in all cases, even if not in one
* of the states above.
*/
d6_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_NONE);
state = RELEASED;
}
///static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
///{
/// uint8_t *storage;
/// int len = strnlen(str, 255);
/// storage = xzalloc(len + extra + OPT_DATA);
/// storage[OPT_CODE] = code;
/// storage[OPT_LEN] = len + extra;
/// memcpy(storage + extra + OPT_DATA, str, len);
/// return storage;
///}
#if BB_MMU
static void client_background(void)
{
bb_daemonize(0);
logmode &= ~LOGMODE_STDIO;
/* rewrite pidfile, as our pid is different now */
write_pidfile(client_config.pidfile);
}
#endif
//usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
//usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
//usage:#else
//usage:# define IF_UDHCP_VERBOSE(...)
//usage:#endif
//usage:#define udhcpc6_trivial_usage
//usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"odR] [-i IFACE] [-r IPv6] [-s PROG] [-p PIDFILE]\n"
//usage: " [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
//usage:#define udhcpc6_full_usage "\n"
//usage: "\n -i IFACE Interface to use (default eth0)"
//usage: "\n -p FILE Create pidfile"
//usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
//usage: "\n -B Request broadcast replies"
//usage: "\n -t N Send up to N discover packets"
//usage: "\n -T N Pause between packets (default 3 seconds)"
//usage: "\n -A N Wait N seconds (default 20) after failure"
//usage: "\n -f Run in foreground"
//usage: USE_FOR_MMU(
//usage: "\n -b Background if lease is not obtained"
//usage: )
//usage: "\n -n Exit if lease is not obtained"
//usage: "\n -q Exit after obtaining lease"
//usage: "\n -R Release IP on exit"
//usage: "\n -S Log to syslog too"
//usage: IF_FEATURE_UDHCP_PORT(
//usage: "\n -P N Use port N (default 546)"
//usage: )
////usage: IF_FEATURE_UDHCPC_ARPING(
////usage: "\n -a Use arping to validate offered address"
////usage: )
//usage: "\n -O OPT Request option OPT from server (cumulative)"
//usage: "\n -o Don't request any options (unless -O is given)"
//usage: "\n -r IPv6 Request this address ('no' to not request any IP)"
//usage: "\n -d Request prefix"
//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
//usage: "\n Examples of string, numeric, and hex byte opts:"
//usage: "\n -x hostname:bbox - option 12"
//usage: "\n -x lease:3600 - option 51 (lease time)"
//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
//usage: IF_UDHCP_VERBOSE(
//usage: "\n -v Verbose"
//usage: )
//usage: "\nSignals:"
//usage: "\n USR1 Renew lease"
//usage: "\n USR2 Release lease"
int udhcpc6_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
{
const char *str_r;
IF_FEATURE_UDHCP_PORT(char *str_P;)
void *clientid_mac_ptr;
llist_t *list_O = NULL;
llist_t *list_x = NULL;
int tryagain_timeout = 20;
int discover_timeout = 3;
int discover_retries = 3;
struct in6_addr srv6_buf;
struct in6_addr ipv6_buf;
struct in6_addr *requested_ipv6;
uint32_t xid = 0;
int packet_num;
int timeout; /* must be signed */
unsigned already_waited_sec;
unsigned opt;
int retval;
setup_common_bufsiz();
/* We want random_xid to be random */
srand(monotonic_us());
/* Default options */
IF_FEATURE_UDHCP_PORT(SERVER_PORT6 = 547;)
IF_FEATURE_UDHCP_PORT(CLIENT_PORT6 = 546;)
client_config.interface = "eth0";
client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
/* Parse command line */
opt = getopt32long(argv, "^"
/* O,x: list; -T,-t,-A take numeric param */
"i:np:qRr:s:T:+t:+SA:+O:*ox:*fd"
USE_FOR_MMU("b")
///IF_FEATURE_UDHCPC_ARPING("a")
IF_FEATURE_UDHCP_PORT("P:")
"v"
"\0" IF_UDHCP_VERBOSE("vv") /* -v is a counter */
, udhcpc6_longopts
, &client_config.interface, &client_config.pidfile, &str_r /* i,p */
, &client_config.script /* s */
, &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
, &list_O
, &list_x
IF_FEATURE_UDHCP_PORT(, &str_P)
IF_UDHCP_VERBOSE(, &dhcp_verbose)
);
requested_ipv6 = NULL;
option_mask32 |= OPT_r;
if (opt & OPT_r) {
if (strcmp(str_r, "no") == 0) {
option_mask32 -= OPT_r;
} else {
if (inet_pton(AF_INET6, str_r, &ipv6_buf) <= 0)
bb_error_msg_and_die("bad IPv6 address '%s'", str_r);
requested_ipv6 = &ipv6_buf;
}
}
#if ENABLE_FEATURE_UDHCP_PORT
if (opt & OPT_P) {
CLIENT_PORT6 = xatou16(str_P);
SERVER_PORT6 = CLIENT_PORT6 + 1;
}
#endif
while (list_O) {
char *optstr = llist_pop(&list_O);
unsigned n = bb_strtou(optstr, NULL, 0);
if (errno || n > 254) {
n = udhcp_option_idx(optstr, d6_option_strings);
n = d6_optflags[n].code;
}
client_config.opt_mask[n >> 3] |= 1 << (n & 7);
}
if (!(opt & OPT_o)) {
unsigned i, n;
for (i = 0; (n = d6_optflags[i].code) != 0; i++) {
if (d6_optflags[i].flags & OPTION_REQ) {
client_config.opt_mask[n >> 3] |= 1 << (n & 7);
}
}
}
while (list_x) {
char *optstr = llist_pop(&list_x);
char *colon = strchr(optstr, ':');
if (colon)
*colon = ' ';
/* now it looks similar to udhcpd's config file line:
* "optname optval", using the common routine: */
udhcp_str2optset(optstr, &client_config.options, d6_optflags, d6_option_strings);
if (colon)
*colon = ':'; /* restore it for NOMMU reexec */
}
if (d6_read_interface(client_config.interface,
&client_config.ifindex,
&client6_data.ll_ip6,
client_config.client_mac)
) {
return 1;
}
/* Create client ID based on mac, set clientid_mac_ptr */
{
struct d6_option *clientid;
clientid = xzalloc(2+2+2+2+6);
clientid->code = D6_OPT_CLIENTID;
clientid->len = 2+2+6;
clientid->data[1] = 3; /* DUID-LL */
clientid->data[3] = 1; /* ethernet */
clientid_mac_ptr = clientid->data + 2+2;
memcpy(clientid_mac_ptr, client_config.client_mac, 6);
client_config.clientid = (void*)clientid;
}
#if !BB_MMU
/* on NOMMU reexec (i.e., background) early */
if (!(opt & OPT_f)) {
bb_daemonize_or_rexec(0 /* flags */, argv);
logmode = LOGMODE_NONE;
}
#endif
if (opt & OPT_S) {
openlog(applet_name, LOG_PID, LOG_DAEMON);
logmode |= LOGMODE_SYSLOG;
}
/* Make sure fd 0,1,2 are open */
bb_sanitize_stdio();
/* Create pidfile */
write_pidfile(client_config.pidfile);
/* Goes to stdout (unless NOMMU) and possibly syslog */
bb_error_msg("started, v"BB_VER);
/* Set up the signal pipe */
udhcp_sp_setup();
state = INIT_SELECTING;
d6_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
packet_num = 0;
timeout = 0;
already_waited_sec = 0;
/* Main event loop. select() waits on signal pipe and possibly
* on sockfd.
* "continue" statements in code below jump to the top of the loop.
*/
for (;;) {
int tv;
struct pollfd pfds[2];
struct d6_packet packet;
uint8_t *packet_end;
/* silence "uninitialized!" warning */
unsigned timestamp_before_wait = timestamp_before_wait;
//bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
/* Was opening raw or udp socket here
* if (listen_mode != LISTEN_NONE && sockfd < 0),
* but on fast network renew responses return faster
* than we open sockets. Thus this code is moved
* to change_listen_mode(). Thus we open listen socket
* BEFORE we send renew request (see "case BOUND:"). */
udhcp_sp_fd_set(pfds, sockfd);
tv = timeout - already_waited_sec;
retval = 0;
/* If we already timed out, fall through with retval = 0, else... */
if (tv > 0) {
log1("waiting %u seconds", tv);
timestamp_before_wait = (unsigned)monotonic_sec();
retval = poll(pfds, 2, tv < INT_MAX/1000 ? tv * 1000 : INT_MAX);
if (retval < 0) {
/* EINTR? A signal was caught, don't panic */
if (errno == EINTR) {
already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
continue;
}
/* Else: an error occured, panic! */
bb_perror_msg_and_die("poll");
}
}
/* If timeout dropped to zero, time to become active:
* resend discover/renew/whatever
*/
if (retval == 0) {
/* When running on a bridge, the ifindex may have changed
* (e.g. if member interfaces were added/removed
* or if the status of the bridge changed).
* Refresh ifindex and client_mac:
*/
if (d6_read_interface(client_config.interface,
&client_config.ifindex,
&client6_data.ll_ip6,
client_config.client_mac)
) {
goto ret0; /* iface is gone? */
}
memcpy(clientid_mac_ptr, client_config.client_mac, 6);
/* We will restart the wait in any case */
already_waited_sec = 0;
switch (state) {
case INIT_SELECTING:
if (!discover_retries || packet_num < discover_retries) {
if (packet_num == 0)
xid = random_xid();
/* multicast */
send_d6_discover(xid, requested_ipv6);
timeout = discover_timeout;
packet_num++;
continue;
}
leasefail:
d6_run_script(NULL, "leasefail");
#if BB_MMU /* -b is not supported on NOMMU */
if (opt & OPT_b) { /* background if no lease */
bb_error_msg("no lease, forking to background");
client_background();
/* do not background again! */
opt = ((opt & ~OPT_b) | OPT_f);
} else
#endif
if (opt & OPT_n) { /* abort if no lease */
bb_error_msg("no lease, failing");
retval = 1;
goto ret;
}
/* wait before trying again */
timeout = tryagain_timeout;
packet_num = 0;
continue;
case REQUESTING:
if (!discover_retries || packet_num < discover_retries) {
/* send multicast select packet */
send_d6_select(xid);
timeout = discover_timeout;
packet_num++;
continue;
}
/* Timed out, go back to init state.
* "discover...select...discover..." loops
* were seen in the wild. Treat them similarly
* to "no response to discover" case */
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
goto leasefail;
case BOUND:
/* 1/2 lease passed, enter renewing state */
state = RENEWING;
client_config.first_secs = 0; /* make secs field count from 0 */
change_listen_mode(LISTEN_KERNEL);
log1("entering renew state");
/* fall right through */
case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
case_RENEW_REQUESTED:
case RENEWING:
if (timeout > 60) {
/* send an unicast renew request */
/* Sometimes observed to fail (EADDRNOTAVAIL) to bind
* a new UDP socket for sending inside send_renew.
* I hazard to guess existing listening socket
* is somehow conflicting with it, but why is it
* not deterministic then?! Strange.
* Anyway, it does recover by eventually failing through
* into INIT_SELECTING state.
*/
send_d6_renew(xid, &srv6_buf, requested_ipv6);
timeout >>= 1;
continue;
}
/* Timed out, enter rebinding state */
log1("entering rebinding state");
state = REBINDING;
/* fall right through */
case REBINDING:
/* Switch to bcast receive */
change_listen_mode(LISTEN_RAW);
/* Lease is *really* about to run out,
* try to find DHCP server using broadcast */
if (timeout > 0) {
/* send a broadcast renew request */
send_d6_renew(xid, /*server_ipv6:*/ NULL, requested_ipv6);
timeout >>= 1;
continue;
}
/* Timed out, enter init state */
bb_error_msg("lease lost, entering init state");
d6_run_script(NULL, "deconfig");
state = INIT_SELECTING;
client_config.first_secs = 0; /* make secs field count from 0 */
/*timeout = 0; - already is */
packet_num = 0;
continue;
/* case RELEASED: */
}
/* yah, I know, *you* say it would never happen */
timeout = INT_MAX;
continue; /* back to main loop */
} /* if poll timed out */
/* poll() didn't timeout, something happened */
/* Is it a signal? */
switch (udhcp_sp_read()) {
case SIGUSR1:
client_config.first_secs = 0; /* make secs field count from 0 */
already_waited_sec = 0;
perform_renew();
if (state == RENEW_REQUESTED) {
/* We might be either on the same network
* (in which case renew might work),
* or we might be on a completely different one
* (in which case renew won't ever succeed).
* For the second case, must make sure timeout
* is not too big, or else we can send
* futile renew requests for hours.
* (Ab)use -A TIMEOUT value (usually 20 sec)
* as a cap on the timeout.
*/
if (timeout > tryagain_timeout)
timeout = tryagain_timeout;
goto case_RENEW_REQUESTED;
}
/* Start things over */
packet_num = 0;
/* Kill any timeouts, user wants this to hurry along */
timeout = 0;
continue;
case SIGUSR2:
perform_d6_release(&srv6_buf, requested_ipv6);
timeout = INT_MAX;
continue;
case SIGTERM:
bb_error_msg("received %s", "SIGTERM");
goto ret0;
}
/* Is it a packet? */
if (!pfds[1].revents)
continue; /* no */
{
int len;
/* A packet is ready, read it */
if (listen_mode == LISTEN_KERNEL)
len = d6_recv_kernel_packet(&srv6_buf, &packet, sockfd);
else
len = d6_recv_raw_packet(&srv6_buf, &packet, sockfd);
if (len == -1) {
/* Error is severe, reopen socket */
bb_error_msg("read error: "STRERROR_FMT", reopening socket" STRERROR_ERRNO);
sleep(discover_timeout); /* 3 seconds by default */
change_listen_mode(listen_mode); /* just close and reopen */
}
/* If this packet will turn out to be unrelated/bogus,
* we will go back and wait for next one.
* Be sure timeout is properly decreased. */
already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
if (len < 0)
continue;
packet_end = (uint8_t*)&packet + len;
}
if ((packet.d6_xid32 & htonl(0x00ffffff)) != xid) {
log1("xid %x (our is %x), ignoring packet",
(unsigned)(packet.d6_xid32 & htonl(0x00ffffff)), (unsigned)xid);
continue;
}
switch (state) {
case INIT_SELECTING:
if (packet.d6_msg_type == D6_MSG_ADVERTISE)
goto type_is_ok;
/* DHCPv6 has "Rapid Commit", when instead of Advertise,
* server sends Reply right away.
* Fall through to check for this case.
*/
case REQUESTING:
case RENEWING:
case RENEW_REQUESTED:
case REBINDING:
if (packet.d6_msg_type == D6_MSG_REPLY) {
uint32_t lease_seconds;
struct d6_option *option;
unsigned address_timeout;
unsigned prefix_timeout;
type_is_ok:
address_timeout = 0;
prefix_timeout = 0;
option = d6_find_option(packet.d6_options, packet_end, D6_OPT_STATUS_CODE);
if (option && (option->data[0] | option->data[1]) != 0) {
/* return to init state */
bb_error_msg("received DHCP NAK (%u)", option->data[4]);
d6_run_script(&packet, "nak");
if (state != REQUESTING)
d6_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
sleep(3); /* avoid excessive network traffic */
state = INIT_SELECTING;
client_config.first_secs = 0; /* make secs field count from 0 */
requested_ipv6 = NULL;
timeout = 0;
packet_num = 0;
already_waited_sec = 0;
continue;
}
option = d6_copy_option(packet.d6_options, packet_end, D6_OPT_SERVERID);
if (!option) {
bb_error_msg("no server ID, ignoring packet");
continue;
/* still selecting - this server looks bad */
}
//Note: we do not bother comparing server IDs in Advertise and Reply msgs.
//server_id variable is used solely for creation of proper server_id option
//in outgoing packets. (why DHCPv6 even introduced it is a mystery).
free(client6_data.server_id);
client6_data.server_id = option;
if (packet.d6_msg_type == D6_MSG_ADVERTISE) {
/* enter requesting state */
state = REQUESTING;
timeout = 0;
packet_num = 0;
already_waited_sec = 0;
continue;
}
/* It's a D6_MSG_REPLY */
/*
* RFC 3315 18.1.8. Receipt of Reply Messages
*
* Upon the receipt of a valid Reply message in response to a Solicit
* (with a Rapid Commit option), Request, Confirm, Renew, Rebind or
* Information-request message, the client extracts the configuration
* information contained in the Reply. The client MAY choose to report
* any status code or message from the status code option in the Reply
* message.
*
* The client SHOULD perform duplicate address detection [17] on each of
* the addresses in any IAs it receives in the Reply message before
* using that address for traffic. If any of the addresses are found to
* be in use on the link, the client sends a Decline message to the
* server as described in section 18.1.7.
*
* If the Reply was received in response to a Solicit (with a Rapid
* Commit option), Request, Renew or Rebind message, the client updates
* the information it has recorded about IAs from the IA options
* contained in the Reply message:
*
* - Record T1 and T2 times.
*
* - Add any new addresses in the IA option to the IA as recorded by
* the client.
*
* - Update lifetimes for any addresses in the IA option that the
* client already has recorded in the IA.
*
* - Discard any addresses from the IA, as recorded by the client, that
* have a valid lifetime of 0 in the IA Address option.
*
* - Leave unchanged any information about addresses the client has
* recorded in the IA but that were not included in the IA from the
* server.
*
* Management of the specific configuration information is detailed in
* the definition of each option in section 22.
*
* If the client receives a Reply message with a Status Code containing
* UnspecFail, the server is indicating that it was unable to process
* the message due to an unspecified failure condition. If the client
* retransmits the original message to the same server to retry the
* desired operation, the client MUST limit the rate at which it
* retransmits the message and limit the duration of the time during
* which it retransmits the message.
*
* When the client receives a Reply message with a Status Code option
* with the value UseMulticast, the client records the receipt of the
* message and sends subsequent messages to the server through the
* interface on which the message was received using multicast. The
* client resends the original message using multicast.
*
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | OPTION_IA_NA | option-len |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | IAID (4 octets) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | T1 |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | T2 |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* . IA_NA-options .
* . .
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
*
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | OPTION_IAADDR | option-len |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* | IPv6 address |
* | |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | preferred-lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | valid-lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* . .
* . IAaddr-options .
* . .
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
if (option_mask32 & OPT_r) {
struct d6_option *iaaddr;
free(client6_data.ia_na);
client6_data.ia_na = d6_copy_option(packet.d6_options, packet_end, D6_OPT_IA_NA);
if (!client6_data.ia_na) {
bb_error_msg("no %s option, ignoring packet", "IA_NA");
continue;
}
if (client6_data.ia_na->len < (4 + 4 + 4) + (2 + 2 + 16 + 4 + 4)) {
bb_error_msg("%s option is too short:%d bytes",
"IA_NA", client6_data.ia_na->len);
continue;
}
iaaddr = d6_find_option(client6_data.ia_na->data + 4 + 4 + 4,
client6_data.ia_na->data + client6_data.ia_na->len,
D6_OPT_IAADDR
);
if (!iaaddr) {
bb_error_msg("no %s option, ignoring packet", "IAADDR");
continue;
}
if (iaaddr->len < (16 + 4 + 4)) {
bb_error_msg("%s option is too short:%d bytes",
"IAADDR", iaaddr->len);
continue;
}
/* Note: the address is sufficiently aligned for cast:
* we _copied_ IA-NA, and copy is always well-aligned.
*/
requested_ipv6 = (struct in6_addr*) iaaddr->data;
move_from_unaligned32(lease_seconds, iaaddr->data + 16 + 4);
lease_seconds = ntohl(lease_seconds);
/// TODO: check for 0 lease time?
bb_error_msg("%s obtained, lease time %u",
"IPv6", /*inet_ntoa(temp_addr),*/ (unsigned)lease_seconds);
address_timeout = lease_seconds;
}
if (option_mask32 & OPT_d) {
struct d6_option *iaprefix;
free(client6_data.ia_pd);
client6_data.ia_pd = d6_copy_option(packet.d6_options, packet_end, D6_OPT_IA_PD);
if (!client6_data.ia_pd) {
bb_error_msg("no %s option, ignoring packet", "IA_PD");
continue;
}
if (client6_data.ia_pd->len < (4 + 4 + 4) + (2 + 2 + 4 + 4 + 1 + 16)) {
bb_error_msg("%s option is too short:%d bytes",
"IA_PD", client6_data.ia_pd->len);
continue;
}
iaprefix = d6_find_option(client6_data.ia_pd->data + 4 + 4 + 4,
client6_data.ia_pd->data + client6_data.ia_pd->len,
D6_OPT_IAPREFIX
);
if (!iaprefix) {
bb_error_msg("no %s option, ignoring packet", "IAPREFIX");
continue;
}
if (iaprefix->len < (4 + 4 + 1 + 16)) {
bb_error_msg("%s option is too short:%d bytes",
"IAPREFIX", iaprefix->len);
continue;
}
move_from_unaligned32(lease_seconds, iaprefix->data + 4);
lease_seconds = ntohl(lease_seconds);
bb_error_msg("%s obtained, lease time %u",
"prefix", /*inet_ntoa(temp_addr),*/ (unsigned)lease_seconds);
prefix_timeout = lease_seconds;
}
if (!address_timeout)
address_timeout = prefix_timeout;
if (!prefix_timeout)
prefix_timeout = address_timeout;
/* note: "int timeout" will not overflow even with 0xffffffff inputs here: */
timeout = (prefix_timeout < address_timeout ? prefix_timeout : address_timeout) / 2;
/* paranoia: must not be too small */
if (timeout < 0x10)
timeout = 0x10;
/* enter bound state */
d6_run_script(&packet, state == REQUESTING ? "bound" : "renew");
state = BOUND;
change_listen_mode(LISTEN_NONE);
if (opt & OPT_q) { /* quit after lease */
goto ret0;
}
/* future renew failures should not exit (JM) */
opt &= ~OPT_n;
#if BB_MMU /* NOMMU case backgrounded earlier */
if (!(opt & OPT_f)) {
client_background();
/* do not background again! */
opt = ((opt & ~OPT_b) | OPT_f);
}
#endif
already_waited_sec = 0;
continue; /* back to main loop */
}
continue;
/* case BOUND: - ignore all packets */
/* case RELEASED: - ignore all packets */
}
/* back to main loop */
} /* for (;;) - main loop ends */
ret0:
if (opt & OPT_R) /* release on quit */
perform_d6_release(&srv6_buf, requested_ipv6);
retval = 0;
ret:
/*if (client_config.pidfile) - remove_pidfile has its own check */
remove_pidfile(client_config.pidfile);
return retval;
}
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