void
test_GenerateAuthenticatedPacket(void)
{
static const int EXPECTED_PKTLEN = LEN_PKT_NOMAC + MAX_MD5_LEN;
struct key testkey;
struct pkt testpkt;
struct timeval xmt;
l_fp expected_xmt, actual_xmt;
char expected_mac[MAX_MD5_LEN];
testkey.next = NULL;
testkey.key_id = 30;
testkey.key_len = 9;
memcpy(testkey.key_seq, "123456789", testkey.key_len);
strlcpy(testkey.typen, "MD5", sizeof(testkey.typen));
testkey.typei = keytype_from_text(testkey.typen, NULL);
GETTIMEOFDAY(&xmt, NULL);
xmt.tv_sec += JAN_1970;
TEST_ASSERT_EQUAL(EXPECTED_PKTLEN,
generate_pkt(&testpkt, &xmt, testkey.key_id, &testkey));
TEST_ASSERT_EQUAL(LEAP_NOTINSYNC, PKT_LEAP(testpkt.li_vn_mode));
TEST_ASSERT_EQUAL(NTP_VERSION, PKT_VERSION(testpkt.li_vn_mode));
TEST_ASSERT_EQUAL(MODE_CLIENT, PKT_MODE(testpkt.li_vn_mode));
TEST_ASSERT_EQUAL(STRATUM_UNSPEC, PKT_TO_STRATUM(testpkt.stratum));
TEST_ASSERT_EQUAL(8, testpkt.ppoll);
TVTOTS(&xmt, &expected_xmt);
NTOHL_FP(&testpkt.xmt, &actual_xmt);
TEST_ASSERT_TRUE(LfpEquality(expected_xmt, actual_xmt));
TEST_ASSERT_EQUAL(testkey.key_id, ntohl(testpkt.exten[0]));
TEST_ASSERT_EQUAL(MAX_MD5_LEN - 4, /* Remove the key_id, only keep the mac. */
make_mac(&testpkt, LEN_PKT_NOMAC, MAX_MD5_LEN-4, &testkey, expected_mac));
TEST_ASSERT_EQUAL_MEMORY(expected_mac, (char*)&testpkt.exten[1], MAX_MD5_LEN -4);
}
TEST_F(mainTest, GenerateUnauthenticatedPacket) {
pkt testpkt;
timeval xmt;
GETTIMEOFDAY(&xmt, NULL);
xmt.tv_sec += JAN_1970;
EXPECT_EQ(LEN_PKT_NOMAC,
generate_pkt(&testpkt, &xmt, 0, NULL));
EXPECT_EQ(LEAP_NOTINSYNC, PKT_LEAP(testpkt.li_vn_mode));
EXPECT_EQ(NTP_VERSION, PKT_VERSION(testpkt.li_vn_mode));
EXPECT_EQ(MODE_CLIENT, PKT_MODE(testpkt.li_vn_mode));
EXPECT_EQ(STRATUM_UNSPEC, PKT_TO_STRATUM(testpkt.stratum));
EXPECT_EQ(8, testpkt.ppoll);
l_fp expected_xmt, actual_xmt;
TVTOTS(&xmt, &expected_xmt);
NTOHL_FP(&testpkt.xmt, &actual_xmt);
EXPECT_TRUE(LfpEquality(expected_xmt, actual_xmt));
}
TEST_F(mainTest, GenerateAuthenticatedPacket) {
key testkey;
testkey.next = NULL;
testkey.key_id = 30;
testkey.key_len = 9;
memcpy(testkey.key_seq, "123456789", testkey.key_len);
memcpy(testkey.type, "MD5", 3);
pkt testpkt;
timeval xmt;
GETTIMEOFDAY(&xmt, NULL);
xmt.tv_sec += JAN_1970;
const int EXPECTED_PKTLEN = LEN_PKT_NOMAC + MAX_MD5_LEN;
EXPECT_EQ(EXPECTED_PKTLEN,
generate_pkt(&testpkt, &xmt, testkey.key_id, &testkey));
EXPECT_EQ(LEAP_NOTINSYNC, PKT_LEAP(testpkt.li_vn_mode));
EXPECT_EQ(NTP_VERSION, PKT_VERSION(testpkt.li_vn_mode));
EXPECT_EQ(MODE_CLIENT, PKT_MODE(testpkt.li_vn_mode));
EXPECT_EQ(STRATUM_UNSPEC, PKT_TO_STRATUM(testpkt.stratum));
EXPECT_EQ(8, testpkt.ppoll);
l_fp expected_xmt, actual_xmt;
TVTOTS(&xmt, &expected_xmt);
NTOHL_FP(&testpkt.xmt, &actual_xmt);
EXPECT_TRUE(LfpEquality(expected_xmt, actual_xmt));
EXPECT_EQ(testkey.key_id, ntohl(testpkt.exten[0]));
char expected_mac[MAX_MD5_LEN];
ASSERT_EQ(MAX_MD5_LEN - 4, // Remove the key_id, only keep the mac.
make_mac((char*)&testpkt, LEN_PKT_NOMAC, MAX_MD5_LEN, &testkey, expected_mac));
EXPECT_TRUE(memcmp(expected_mac, (char*)&testpkt.exten[1], MAX_MD5_LEN -4) == 0);
}
void
test_GenerateUnauthenticatedPacket(void)
{
struct pkt testpkt;
struct timeval xmt;
l_fp expected_xmt, actual_xmt;
GETTIMEOFDAY(&xmt, NULL);
xmt.tv_sec += JAN_1970;
TEST_ASSERT_EQUAL(LEN_PKT_NOMAC,
generate_pkt(&testpkt, &xmt, 0, NULL));
TEST_ASSERT_EQUAL(LEAP_NOTINSYNC, PKT_LEAP(testpkt.li_vn_mode));
TEST_ASSERT_EQUAL(NTP_VERSION, PKT_VERSION(testpkt.li_vn_mode));
TEST_ASSERT_EQUAL(MODE_CLIENT, PKT_MODE(testpkt.li_vn_mode));
TEST_ASSERT_EQUAL(STRATUM_UNSPEC, PKT_TO_STRATUM(testpkt.stratum));
TEST_ASSERT_EQUAL(8, testpkt.ppoll);
TVTOTS(&xmt, &expected_xmt);
NTOHL_FP(&testpkt.xmt, &actual_xmt);
TEST_ASSERT_TRUE(LfpEquality(expected_xmt, actual_xmt));
}
int
process_pkt (
struct pkt *rpkt,
sockaddr_u *sas,
int pkt_len,
int mode,
struct pkt *spkt,
const char * func_name
)
{
unsigned int key_id = 0;
struct key *pkt_key = NULL;
int is_authentic = 0;
unsigned int exten_words, exten_words_used = 0;
int mac_size;
/*
* Parse the extension field if present. We figure out whether
* an extension field is present by measuring the MAC size. If
* the number of words following the packet header is 0, no MAC
* is present and the packet is not authenticated. If 1, the
* packet is a crypto-NAK; if 3, the packet is authenticated
* with DES; if 5, the packet is authenticated with MD5; if 6,
* the packet is authenticated with SHA. If 2 or 4, the packet
* is a runt and discarded forthwith. If greater than 6, an
* extension field is present, so we subtract the length of the
* field and go around again.
*/
if (pkt_len < (int)LEN_PKT_NOMAC || (pkt_len & 3) != 0) {
unusable:
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp %s: Funny packet length: %i. Discarding package.\n", func_name, pkt_len);
return PACKET_UNUSEABLE;
}
/* skip past the extensions, if any */
exten_words = ((unsigned)pkt_len - LEN_PKT_NOMAC) >> 2;
while (exten_words > 6) {
unsigned int exten_len;
exten_len = ntohl(rpkt->exten[exten_words_used]) & 0xffff;
exten_len = (exten_len + 7) >> 2; /* convert to words, add 1 */
if (exten_len > exten_words || exten_len < 5)
goto unusable;
exten_words -= exten_len;
exten_words_used += exten_len;
}
switch (exten_words) {
case 1:
key_id = ntohl(rpkt->exten[exten_words_used]);
printf("Crypto NAK = 0x%08x\n", key_id);
break;
case 5:
case 6:
/* Look for the key used by the server in the specified keyfile
* and if existent, fetch it or else leave the pointer untouched */
key_id = ntohl(rpkt->exten[exten_words_used]);
get_key(key_id, &pkt_key);
if (!pkt_key) {
printf("unrecognized key ID = 0x%08x\n", key_id);
break;
}
/* Seems like we've got a key with matching keyid */
/* Generate a md5sum of the packet with the key from our keyfile
* and compare those md5sums */
mac_size = exten_words << 2;
if (!auth_md5((char *)rpkt, pkt_len - mac_size, mac_size - 4, pkt_key)) {
break;
}
/* Yay! Things worked out! */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(sas);
printf("sntp %s: packet received from %s successfully authenticated using key id %i.\n",
func_name, hostname, key_id);
free(hostname);
}
is_authentic = 1;
break;
case 0:
break;
default:
goto unusable;
break;
}
if (!is_authentic) {
if (ENABLED_OPT(AUTHENTICATION)) {
/* We want a authenticated packet */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(sas);
printf("sntp %s: packet received from %s is not authentic. Will discard it.\n",
func_name, hostname);
free(hostname);
}
return SERVER_AUTH_FAIL;
}
/* We don't know if the user wanted authentication so let's
* use it anyways */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(sas);
printf("sntp %s: packet received from %s is not authentic. Authentication not enforced.\n",
func_name, hostname);
free(hostname);
}
}
/* Check for server's ntp version */
if (PKT_VERSION(rpkt->li_vn_mode) < NTP_OLDVERSION ||
PKT_VERSION(rpkt->li_vn_mode) > NTP_VERSION) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp %s: Packet shows wrong version (%i)\n",
func_name, PKT_VERSION(rpkt->li_vn_mode));
return SERVER_UNUSEABLE;
}
/* We want a server to sync with */
if (PKT_MODE(rpkt->li_vn_mode) != mode &&
PKT_MODE(rpkt->li_vn_mode) != MODE_PASSIVE) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp %s: mode %d stratum %i\n", func_name,
PKT_MODE(rpkt->li_vn_mode), rpkt->stratum);
return SERVER_UNUSEABLE;
}
/* Stratum is unspecified (0) check what's going on */
if (STRATUM_PKT_UNSPEC == rpkt->stratum) {
char *ref_char;
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp %s: Stratum unspecified, going to check for KOD (stratum: %i)\n",
func_name, rpkt->stratum);
ref_char = (char *) &rpkt->refid;
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp %s: Packet refid: %c%c%c%c\n", func_name,
ref_char[0], ref_char[1], ref_char[2], ref_char[3]);
/* If it's a KOD packet we'll just use the KOD information */
if (ref_char[0] != 'X') {
if (strncmp(ref_char, "DENY", 4) == 0)
return KOD_DEMOBILIZE;
if (strncmp(ref_char, "RSTR", 4) == 0)
return KOD_DEMOBILIZE;
if (strncmp(ref_char, "RATE", 4) == 0)
return KOD_RATE;
/* There are other interesting kiss codes which might be interesting for authentication */
}
}
/* If the server is not synced it's not really useable for us */
if (LEAP_NOTINSYNC == PKT_LEAP(rpkt->li_vn_mode)) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp %s: Server not in sync, skipping this server\n", func_name);
return SERVER_UNUSEABLE;
}
/*
* Decode the org timestamp and make sure we're getting a response
* to our last request, but only if we're not in broadcast mode.
*/
#ifdef DEBUG
printf("rpkt->org:\n");
l_fp_output(&rpkt->org, stdout);
printf("spkt->xmt:\n");
l_fp_output(&spkt->xmt, stdout);
#endif
if (mode != MODE_BROADCAST && !L_ISEQU(&rpkt->org, &spkt->xmt)) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp process_pkt: pkt.org and peer.xmt differ\n");
return PACKET_UNUSEABLE;
}
return pkt_len;
}
int
handle_pkt(
int rpktl,
struct pkt * rpkt,
sockaddr_u * host,
const char * hostname
)
{
char disptxt[32];
const char * addrtxt;
struct timeval tv_dst;
int cnt;
int sw_case;
int digits;
int stratum;
char * ref;
char * ts_str;
const char * leaptxt;
double offset;
double precision;
double synch_distance;
char * p_SNTP_PRETEND_TIME;
time_t pretend_time;
#if SIZEOF_TIME_T == 8
long long ll;
#else
long l;
#endif
ts_str = NULL;
if (rpktl > 0)
sw_case = 1;
else
sw_case = rpktl;
switch (sw_case) {
case SERVER_UNUSEABLE:
return -1;
break;
case PACKET_UNUSEABLE:
break;
case SERVER_AUTH_FAIL:
break;
case KOD_DEMOBILIZE:
/* Received a DENY or RESTR KOD packet */
addrtxt = stoa(host);
ref = (char *)&rpkt->refid;
add_entry(addrtxt, ref);
msyslog(LOG_WARNING, "KOD code %c%c%c%c from %s %s",
ref[0], ref[1], ref[2], ref[3], addrtxt, hostname);
break;
case KOD_RATE:
/*
** Hmm...
** We should probably call add_entry() with an
** expiration timestamp of several seconds in the future,
** and back-off even more if we get more RATE responses.
*/
break;
case 1:
TRACE(3, ("handle_pkt: %d bytes from %s %s\n",
rpktl, stoa(host), hostname));
gettimeofday_cached(base, &tv_dst);
p_SNTP_PRETEND_TIME = getenv("SNTP_PRETEND_TIME");
if (p_SNTP_PRETEND_TIME) {
pretend_time = 0;
#if SIZEOF_TIME_T == 4
if (1 == sscanf(p_SNTP_PRETEND_TIME, "%ld", &l))
pretend_time = (time_t)l;
#elif SIZEOF_TIME_T == 8
if (1 == sscanf(p_SNTP_PRETEND_TIME, "%lld", &ll))
pretend_time = (time_t)ll;
#else
# include "GRONK: unexpected value for SIZEOF_TIME_T"
#endif
if (0 != pretend_time)
tv_dst.tv_sec = pretend_time;
}
offset_calculation(rpkt, rpktl, &tv_dst, &offset,
&precision, &synch_distance);
time_derived = TRUE;
for (digits = 0; (precision *= 10.) < 1.; ++digits)
/* empty */ ;
if (digits > 6)
digits = 6;
ts_str = tv_to_str(&tv_dst);
stratum = rpkt->stratum;
if (0 == stratum)
stratum = 16;
if (synch_distance > 0.) {
cnt = snprintf(disptxt, sizeof(disptxt),
" +/- %f", synch_distance);
if ((size_t)cnt >= sizeof(disptxt))
snprintf(disptxt, sizeof(disptxt),
"ERROR %d >= %d", cnt,
(int)sizeof(disptxt));
} else {
disptxt[0] = '\0';
}
switch (PKT_LEAP(rpkt->li_vn_mode)) {
case LEAP_NOWARNING:
leaptxt = "no-leap";
break;
case LEAP_ADDSECOND:
leaptxt = "add-leap";
break;
case LEAP_DELSECOND:
leaptxt = "del-leap";
break;
case LEAP_NOTINSYNC:
leaptxt = "unsync";
break;
default:
leaptxt = "LEAP-ERROR";
break;
}
msyslog(LOG_INFO, "%s %+.*f%s %s s%d %s%s", ts_str,
digits, offset, disptxt,
hostnameaddr(hostname, host), stratum,
leaptxt,
(time_adjusted)
? " [excess]"
: "");
free(ts_str);
if (p_SNTP_PRETEND_TIME)
return 0;
if (!time_adjusted &&
(ENABLED_OPT(STEP) || ENABLED_OPT(SLEW)))
return set_time(offset);
return EX_OK;
}
return 1;
}
/*
** Check if it's data for us and whether it's useable or not.
**
** If not, return a failure code so we can delete this server from our list
** and continue with another one.
*/
int
process_pkt (
struct pkt *rpkt,
sockaddr_u *sender,
int pkt_len,
int mode,
struct pkt *spkt,
const char * func_name
)
{
u_int key_id;
struct key * pkt_key;
int is_authentic;
int mac_size;
u_int exten_len;
u_int32 * exten_end;
u_int32 * packet_end;
l_fp sent_xmt;
l_fp resp_org;
// key_id = 0;
pkt_key = NULL;
is_authentic = (HAVE_OPT(AUTHENTICATION)) ? 0 : -1;
/*
* Parse the extension field if present. We figure out whether
* an extension field is present by measuring the MAC size. If
* the number of words following the packet header is 0, no MAC
* is present and the packet is not authenticated. If 1, the
* packet is a crypto-NAK; if 3, the packet is authenticated
* with DES; if 5, the packet is authenticated with MD5; if 6,
* the packet is authenticated with SHA. If 2 or 4, the packet
* is a runt and discarded forthwith. If greater than 6, an
* extension field is present, so we subtract the length of the
* field and go around again.
*/
if (pkt_len < (int)LEN_PKT_NOMAC || (pkt_len & 3) != 0) {
msyslog(LOG_ERR,
"%s: Incredible packet length: %d. Discarding.",
func_name, pkt_len);
return PACKET_UNUSEABLE;
}
/* HMS: the following needs a bit of work */
/* Note: pkt_len must be a multiple of 4 at this point! */
packet_end = (void*)((char*)rpkt + pkt_len);
exten_end = skip_efields(rpkt->exten, packet_end);
if (NULL == exten_end) {
msyslog(LOG_ERR,
"%s: Missing extension field. Discarding.",
func_name);
return PACKET_UNUSEABLE;
}
/* get size of MAC in cells; can be zero */
exten_len = (u_int)(packet_end - exten_end);
/* deduce action required from remaining length */
switch (exten_len) {
case 0: /* no Legacy MAC */
break;
case 1: /* crypto NAK */
/* Only if the keyID is 0 and there were no EFs */
key_id = ntohl(*exten_end);
printf("Crypto NAK = 0x%08x from %s\n", key_id, stoa(sender));
break;
case 3: /* key ID + 3DES MAC -- unsupported! */
msyslog(LOG_ERR,
"%s: Key ID + 3DES MAC is unsupported. Discarding.",
func_name);
return PACKET_UNUSEABLE;
case 5: /* key ID + MD5 MAC */
case 6: /* key ID + SHA MAC */
/*
** Look for the key used by the server in the specified
** keyfile and if existent, fetch it or else leave the
** pointer untouched
*/
key_id = ntohl(*exten_end);
get_key(key_id, &pkt_key);
if (!pkt_key) {
printf("unrecognized key ID = 0x%08x\n", key_id);
break;
}
/*
** Seems like we've got a key with matching keyid.
**
** Generate a md5sum of the packet with the key from our
** keyfile and compare those md5sums.
*/
mac_size = exten_len << 2;
if (!auth_md5(rpkt, pkt_len - mac_size,
mac_size - 4, pkt_key)) {
is_authentic = FALSE;
break;
}
/* Yay! Things worked out! */
is_authentic = TRUE;
TRACE(1, ("sntp %s: packet from %s authenticated using key id %d.\n",
func_name, stoa(sender), key_id));
break;
default:
msyslog(LOG_ERR,
"%s: Unexpected extension length: %d. Discarding.",
func_name, exten_len);
return PACKET_UNUSEABLE;
}
switch (is_authentic) {
case -1: /* unknown */
break;
case 0: /* not authentic */
return SERVER_AUTH_FAIL;
break;
case 1: /* authentic */
break;
default: /* error */
break;
}
/* Check for server's ntp version */
if (PKT_VERSION(rpkt->li_vn_mode) < NTP_OLDVERSION ||
PKT_VERSION(rpkt->li_vn_mode) > NTP_VERSION) {
msyslog(LOG_ERR,
"%s: Packet shows wrong version (%d)",
func_name, PKT_VERSION(rpkt->li_vn_mode));
return SERVER_UNUSEABLE;
}
/* We want a server to sync with */
if (PKT_MODE(rpkt->li_vn_mode) != mode &&
PKT_MODE(rpkt->li_vn_mode) != MODE_PASSIVE) {
msyslog(LOG_ERR,
"%s: mode %d stratum %d", func_name,
PKT_MODE(rpkt->li_vn_mode), rpkt->stratum);
return SERVER_UNUSEABLE;
}
/* Stratum is unspecified (0) check what's going on */
if (STRATUM_PKT_UNSPEC == rpkt->stratum) {
char *ref_char;
TRACE(1, ("%s: Stratum unspecified, going to check for KOD (stratum: %d)\n",
func_name, rpkt->stratum));
ref_char = (char *) &rpkt->refid;
TRACE(1, ("%s: Packet refid: %c%c%c%c\n", func_name,
ref_char[0], ref_char[1], ref_char[2], ref_char[3]));
/* If it's a KOD packet we'll just use the KOD information */
if (ref_char[0] != 'X') {
if (strncmp(ref_char, "DENY", 4) == 0)
return KOD_DEMOBILIZE;
if (strncmp(ref_char, "RSTR", 4) == 0)
return KOD_DEMOBILIZE;
if (strncmp(ref_char, "RATE", 4) == 0)
return KOD_RATE;
/*
** There are other interesting kiss codes which
** might be interesting for authentication.
*/
}
}
/* If the server is not synced it's not really useable for us */
if (LEAP_NOTINSYNC == PKT_LEAP(rpkt->li_vn_mode)) {
msyslog(LOG_ERR,
"%s: %s not in sync, skipping this server",
func_name, stoa(sender));
return SERVER_UNUSEABLE;
}
/*
* Decode the org timestamp and make sure we're getting a response
* to our last request, but only if we're not in broadcast mode.
*/
if (MODE_BROADCAST == mode)
return pkt_len;
if (!L_ISEQU(&rpkt->org, &spkt->xmt)) {
NTOHL_FP(&rpkt->org, &resp_org);
NTOHL_FP(&spkt->xmt, &sent_xmt);
msyslog(LOG_ERR,
"%s response org expected to match sent xmt",
stoa(sender));
msyslog(LOG_ERR, "resp org: %s", prettydate(&resp_org));
msyslog(LOG_ERR, "sent xmt: %s", prettydate(&sent_xmt));
return PACKET_UNUSEABLE;
}
return pkt_len;
}
/* Fetch data, check if it's data for us and whether it's useable or not. If not, return
* a failure code so we can delete this server from our list and continue with another one.
*/
int
recvpkt (
SOCKET rsock,
struct pkt *rpkt,
struct pkt *spkt
)
{
sockaddr_u sender;
char *rdata /* , done */;
register int a;
int has_mac, is_authentic, pkt_len, orig_pkt_len;
/* Much space, just to be sure */
rdata = emalloc(sizeof(char) * 256);
pkt_len = recvdata(rsock, &sender, rdata, 256);
#if 0 /* done uninitialized */
if (!done) {
/* Do something about it, first check for a maximum length of ntp packets,
* probably that's something we can avoid
*/
}
#endif
if (pkt_len < 0) {
if (ENABLED_OPT(NORMALVERBOSE)) {
printf("sntp recvpkt failed: %d.\n", pkt_len);
}
free(rdata);
return pkt_len;
}
/* Some checks to see if that packet is intended for us */
/* No MAC, no authentication */
if (LEN_PKT_NOMAC == pkt_len)
has_mac = 0;
/* If there's more than just the NTP packet it should be a MAC */
else if (pkt_len > LEN_PKT_NOMAC)
has_mac = pkt_len - LEN_PKT_NOMAC;
else {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: Funny packet length: %i. Discarding package.\n", pkt_len);
free(rdata);
return PACKET_UNUSEABLE;
}
/* Packet too big */
if (pkt_len > LEN_PKT_MAC) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: Received packet is too big (%i bytes), trying again to get a useable packet\n",
pkt_len);
free(rdata);
return PACKET_UNUSEABLE;
}
orig_pkt_len = pkt_len;
pkt_len = min(pkt_len, sizeof(struct pkt));
for (a = 0; a < pkt_len; a++)
/* FIXME! */
if (a < orig_pkt_len)
((char *) rpkt)[a] = rdata[a];
else
((char *) rpkt)[a] = 0;
free(rdata);
rdata = NULL;
/* MAC could be useable for us */
if (has_mac) {
/* Two more things that the MAC must conform to */
if(has_mac > MAX_MAC_LEN || has_mac % 4 != 0) {
is_authentic = 0; /* Or should we discard this packet? */
}
else {
if (MAX_MAC_LEN == has_mac) {
struct key *pkt_key = NULL;
/*
* Look for the key used by the server in the specified keyfile
* and if existent, fetch it or else leave the pointer untouched
*/
get_key(rpkt->mac[0], &pkt_key);
/* Seems like we've got a key with matching keyid */
if (pkt_key != NULL) {
/*
* Generate a md5sum of the packet with the key from our keyfile
* and compare those md5sums
*/
if (!auth_md5((char *) rpkt, has_mac, pkt_key)) {
if (ENABLED_OPT(AUTHENTICATION)) {
/* We want a authenticated packet */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(&sender);
printf("sntp recvpkt: Broadcast packet received from %s is not authentic. Will discard this packet.\n",
hostname);
free(hostname);
}
return SERVER_AUTH_FAIL;
}
else {
/*
* We don't know if the user wanted authentication so let's
* use it anyways
*/
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(&sender);
printf("sntp recvpkt: Broadcast packet received from %s is not authentic. Authentication not enforced.\n",
hostname);
free(hostname);
}
is_authentic = 0;
}
}
else {
/* Yay! Things worked out! */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(&sender);
printf("sntp recvpkt: Broadcast packet received from %s successfully authenticated using key id %i.\n",
hostname, rpkt->mac[0]);
free(hostname);
}
is_authentic = 1;
}
}
}
}
}
/* Check for server's ntp version */
if (PKT_VERSION(rpkt->li_vn_mode) < NTP_OLDVERSION ||
PKT_VERSION(rpkt->li_vn_mode) > NTP_VERSION) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: Packet got wrong version (%i)\n", PKT_VERSION(rpkt->li_vn_mode));
return SERVER_UNUSEABLE;
}
/* We want a server to sync with */
if (PKT_MODE(rpkt->li_vn_mode) != MODE_SERVER &&
PKT_MODE(rpkt->li_vn_mode) != MODE_PASSIVE) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: mode %d stratum %i\n",
PKT_MODE(rpkt->li_vn_mode), rpkt->stratum);
return SERVER_UNUSEABLE;
}
/* Stratum is unspecified (0) check what's going on */
if (STRATUM_PKT_UNSPEC == rpkt->stratum) {
char *ref_char;
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: Stratum unspecified, going to check for KOD (stratum: %i)\n", rpkt->stratum);
ref_char = (char *) &rpkt->refid;
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: Packet refid: %c%c%c%c\n", ref_char[0], ref_char[1], ref_char[2], ref_char[3]);
/* If it's a KOD packet we'll just use the KOD information */
if (ref_char[0] != 'X') {
if (!strncmp(ref_char, "DENY", 4))
return KOD_DEMOBILIZE;
if (!strncmp(ref_char, "RSTR", 4))
return KOD_DEMOBILIZE;
if (!strncmp(ref_char, "RATE", 4))
return KOD_RATE;
/* There are other interesting kiss codes which might be interesting for authentication */
}
}
/* If the server is not synced it's not really useable for us */
if (LEAP_NOTINSYNC == PKT_LEAP(rpkt->li_vn_mode)) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: Server not in sync, skipping this server\n");
return SERVER_UNUSEABLE;
}
/*
* Decode the org timestamp and make sure we're getting a response
* to our last request.
*/
#ifdef DEBUG
printf("rpkt->org:\n");
l_fp_output(&rpkt->org, stdout);
printf("spkt->xmt:\n");
l_fp_output(&spkt->xmt, stdout);
#endif
if (!L_ISEQU(&rpkt->org, &spkt->xmt)) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recvpkt: pkt.org and peer.xmt differ\n");
return PACKET_UNUSEABLE;
}
return pkt_len;
}
int
recv_bcst_pkt (
SOCKET rsock,
struct pkt *rpkt,
sockaddr_u *sas
)
{
sockaddr_u sender;
register int a;
int is_authentic, has_mac = 0, orig_pkt_len;
char *rdata = emalloc(sizeof(char) * 256);
int pkt_len = recv_bcst_data(rsock, rdata, 256, sas, &sender);
if (pkt_len < 0) {
free(rdata);
return BROADCAST_FAILED;
}
/* No MAC, no authentication */
if (LEN_PKT_NOMAC == pkt_len)
has_mac = 0;
/* If there's more than just the NTP packet it should be a MAC */
else if(pkt_len > LEN_PKT_NOMAC)
has_mac = pkt_len - LEN_PKT_NOMAC;
else
if(ENABLED_OPT(NORMALVERBOSE)) {
printf("sntp recv_bcst_pkt: Funny packet length: %i. Discarding package.\n", pkt_len);
free(rdata);
return PACKET_UNUSEABLE;
}
/* Packet too big */
if(pkt_len > LEN_PKT_NOMAC + MAX_MAC_LEN) {
if(ENABLED_OPT(NORMALVERBOSE))
printf("sntp recv_bcst_pkt: Received packet is too big (%i bytes), trying again to get a useFable packet\n",
pkt_len);
free(rdata);
return PACKET_UNUSEABLE;
}
orig_pkt_len = pkt_len;
pkt_len = min(pkt_len, sizeof(struct pkt));
/* Let's copy the received data to the packet structure */
for (a = 0; a < pkt_len; a++)
if (a < orig_pkt_len)
((char *)rpkt)[a] = rdata[a];
else
((char *)rpkt)[a] = 0;
free(rdata);
/* MAC could be useable for us */
if (has_mac) {
/* Two more things that the MAC must conform to */
if (has_mac > MAX_MAC_LEN || has_mac % 4 != 0) {
is_authentic = 0; /* Or should we discard this packet? */
}
else {
if (MAX_MAC_LEN == has_mac) {
struct key *pkt_key = NULL;
/* Look for the key used by the server in the specified keyfile
* and if existent, fetch it or else leave the pointer untouched */
get_key(rpkt->mac[0], &pkt_key);
/* Seems like we've got a key with matching keyid */
if (pkt_key != NULL) {
/* Generate a md5sum of the packet with the key from our keyfile
* and compare those md5sums */
if (!auth_md5((char *) rpkt, has_mac, pkt_key)) {
if (ENABLED_OPT(AUTHENTICATION)) {
/* We want a authenticated packet */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(sas);
printf("sntp recv_bcst_pkt: Broadcast packet received from %s is not authentic. Will discard this packet.\n",
hostname);
free(hostname);
}
return SERVER_AUTH_FAIL;
}
else {
/* We don't know if the user wanted authentication so let's
* use it anyways */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(sas);
printf("sntp recv_bcst_pkt: Broadcast packet received from %s is not authentic. Authentication not enforced.\n",
hostname);
free(hostname);
}
is_authentic = 0;
}
}
else {
/* Yay! Things worked out! */
if (ENABLED_OPT(NORMALVERBOSE)) {
char *hostname = ss_to_str(sas);
printf("sntp recv_bcst_pkt: Broadcast packet received from %s successfully authenticated using key id %i.\n",
hostname, rpkt->mac[0]);
free(hostname);
}
is_authentic = 1;
}
}
}
}
}
/* Check for server's ntp version */
if (PKT_VERSION(rpkt->li_vn_mode) < NTP_OLDVERSION ||
PKT_VERSION(rpkt->li_vn_mode) > NTP_VERSION) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recv_bcst_pkt: Packet shows wrong version (%i)\n",
PKT_VERSION(rpkt->li_vn_mode));
return SERVER_UNUSEABLE;
}
/* We want a server to sync with */
if (PKT_MODE(rpkt->li_vn_mode) != MODE_BROADCAST
&& PKT_MODE(rpkt->li_vn_mode) != MODE_PASSIVE) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recv_bcst_pkt: mode %d stratum %i\n",
PKT_MODE(rpkt->li_vn_mode), rpkt->stratum);
return SERVER_UNUSEABLE;
}
if (STRATUM_PKT_UNSPEC == rpkt->stratum) {
char *ref_char;
if (ENABLED_OPT(NORMALVERBOSE))
printf("sntp recv_bcst_pkt: Stratum unspecified, going to check for KOD (stratum: %i)\n", rpkt->stratum);
ref_char = (char *) &rpkt->refid;
/* If it's a KOD packet we'll just use the KOD information */
if (ref_char[0] != 'X') {
if (strncmp(ref_char, "DENY", 4))
return KOD_DEMOBILIZE;
if (strncmp(ref_char, "RSTR", 4))
return KOD_DEMOBILIZE;
if (strncmp(ref_char, "RATE", 4))
return KOD_RATE;
/* There are other interesting kiss codes which might be interesting for authentication */
}
}
/* If the server is not synced it's not really useable for us */
if (LEAP_NOTINSYNC == PKT_LEAP(rpkt->li_vn_mode)) {
if (ENABLED_OPT(NORMALVERBOSE))
printf("recv_bcst_pkt: Server not in sync, skipping this server\n");
return SERVER_UNUSEABLE;
}
return pkt_len;
}
