/*
* ntp_crypto_random_buf:
*
* Returns 0 on success, -1 on error.
*/
int
ntp_crypto_random_buf(
void *buf,
size_t nbytes
)
{
#ifdef USE_OPENSSL_CRYPTO_RAND
int rc;
rc = RAND_bytes(buf, size2int_chk(nbytes));
if (1 != rc) {
unsigned long err;
char *err_str;
err = ERR_get_error();
err_str = ERR_error_string(err, NULL);
/* XXX: Log the error */
(void)&err_str;
return -1;
}
return 0;
#else
arc4random_buf(buf, nbytes);
return 0;
#endif
}
/*
* sendrequest - format and send a request packet
*
* Historically, ntpdc has used a fixed-size request packet regardless
* of the actual payload size. When authenticating, the timestamp, key
* ID, and digest have been placed just before the end of the packet.
* With the introduction in late 2009 of support for authenticated
* ntpdc requests using larger 20-octet digests (vs. 16 for MD5), we
* come up four bytes short.
*
* To maintain interop while allowing for larger digests, the behavior
* is unchanged when using 16-octet digests. For larger digests, the
* timestamp, key ID, and digest are placed immediately following the
* request payload, with the overall packet size variable. ntpd can
* distinguish 16-octet digests by the overall request size being
* REQ_LEN_NOMAC + 4 + 16 with the auth bit enabled. When using a
* longer digest, that request size should be avoided.
*
* With the form used with 20-octet and larger digests, the timestamp,
* key ID, and digest are located by ntpd relative to the start of the
* packet, and the size of the digest is then implied by the packet
* size.
*/
static int
sendrequest(
int implcode,
int reqcode,
int auth,
size_t qitems,
size_t qsize,
const char *qdata
)
{
struct req_pkt qpkt;
size_t datasize;
size_t reqsize;
u_long key_id;
l_fp ts;
l_fp * ptstamp;
size_t maclen;
char * pass;
ZERO(qpkt);
qpkt.rm_vn_mode = RM_VN_MODE(0, 0, 0);
qpkt.implementation = (u_char)implcode;
qpkt.request = (u_char)reqcode;
datasize = qitems * qsize;
if (datasize && qdata != NULL) {
memcpy(qpkt.u.data, qdata, datasize);
qpkt.err_nitems = ERR_NITEMS(0, qitems);
qpkt.mbz_itemsize = MBZ_ITEMSIZE(qsize);
} else {
qpkt.err_nitems = ERR_NITEMS(0, 0);
qpkt.mbz_itemsize = MBZ_ITEMSIZE(qsize); /* allow for optional first item */
}
if (!auth || (keyid_entered && info_auth_keyid == 0)) {
qpkt.auth_seq = AUTH_SEQ(0, 0);
return sendpkt(&qpkt, req_pkt_size);
}
if (info_auth_keyid == 0) {
key_id = getkeyid("Keyid: ");
if (!key_id) {
fprintf(stderr, "Invalid key identifier\n");
return 1;
}
info_auth_keyid = key_id;
}
if (!authistrusted(info_auth_keyid)) {
pass = getpass_keytype(info_auth_keytype);
if ('\0' == pass[0]) {
fprintf(stderr, "Invalid password\n");
return 1;
}
authusekey(info_auth_keyid, info_auth_keytype,
(u_char *)pass);
authtrust(info_auth_keyid, 1);
}
qpkt.auth_seq = AUTH_SEQ(1, 0);
if (info_auth_hashlen > 16) {
/*
* Only ntpd which expects REQ_LEN_NOMAC plus maclen
* octets in an authenticated request using a 16 octet
* digest (that is, a newer ntpd) will handle digests
* larger than 16 octets, so for longer digests, do
* not attempt to shorten the requests for downlevel
* ntpd compatibility.
*/
if (REQ_LEN_NOMAC != req_pkt_size)
return 1;
reqsize = REQ_LEN_HDR + datasize + sizeof(*ptstamp);
/* align to 32 bits */
reqsize = (reqsize + 3) & ~3;
} else
reqsize = req_pkt_size;
ptstamp = (void *)((char *)&qpkt + reqsize);
ptstamp--;
get_systime(&ts);
L_ADD(&ts, &delay_time);
HTONL_FP(&ts, ptstamp);
maclen = authencrypt(
info_auth_keyid, (void *)&qpkt, size2int_chk(reqsize));
if (!maclen) {
fprintf(stderr, "Key not found\n");
return 1;
} else if (maclen != (size_t)(info_auth_hashlen + sizeof(keyid_t))) {
fprintf(stderr,
"%zu octet MAC, %zu expected with %zu octet digest\n",
maclen, (info_auth_hashlen + sizeof(keyid_t)),
info_auth_hashlen);
return 1;
}
return sendpkt(&qpkt, reqsize + maclen);
}
