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ntp: skip IPv6 extension headers

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Handle IPv6 packets with extension headers received from the error queue
on Linux.
This commit is contained in:
Miroslav Lichvar 2017-08-02 15:01:27 +02:00
parent b896bb5a78
commit 9aac179367
1 changed files with 34 additions and 5 deletions
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39
ntp_io_linux.c
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@ -512,14 +512,43 @@ extract_udp_data(unsigned char *msg, NTP_Remote_Address *remote_addr, int len)
len -= ihl + 8, msg += ihl + 8;
#ifdef FEAT_IPV6
} else if (len >= 48 && msg[0] >> 4 == 6) {
/* IPv6 extension headers are not supported */
if (msg[6] != 17)
return 0;
int eh_len, next_header = msg[6];
memcpy(&addr.in6.sin6_addr.s6_addr, msg + 24, 16);
addr.in6.sin6_port = *(uint16_t *)(msg + 40 + 2);
len -= 40, msg += 40;
/* Skip IPv6 extension headers if present */
while (next_header != 17) {
switch (next_header) {
case 44: /* Fragment Header */
/* Process only the first fragment */
if (ntohs(*(uint16_t *)(msg + 2)) >> 3 != 0)
return 0;
eh_len = 8;
break;
case 0: /* Hop-by-Hop Options */
case 43: /* Routing Header */
case 60: /* Destination Options */
case 135: /* Mobility Header */
eh_len = 8 * (msg[1] + 1);
break;
case 51: /* Authentication Header */
eh_len = 4 * (msg[1] + 2);
break;
default:
return 0;
}
if (eh_len < 8 || len < eh_len + 8)
return 0;
next_header = msg[0];
len -= eh_len, msg += eh_len;
}
addr.in6.sin6_port = *(uint16_t *)(msg + 2);
addr.in6.sin6_family = AF_INET6;
len -= 48, msg += 48;
len -= 8, msg += 8;
#endif
} else {
return 0;