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ntp: update packet processing to NTPv4 (RFC 5905)

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This commit is contained in:
Miroslav Lichvar
2014-10-13 13:26:23 +02:00
parent 740e8130dd
commit 8fbfe55e92
8 changed files with 435 additions and 529 deletions
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45
ntp.h
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@@ -38,7 +38,20 @@ typedef struct {
typedef uint32_t NTP_int32;
#define MAX_NTP_AUTH_DATA_LEN MAX_HASH_LENGTH
/* The NTP protocol version that we support */
#define NTP_VERSION 4
/* The minimum valid length of an extension field */
#define NTP_MIN_EXTENSION_LENGTH 16
/* The maximum assumed length of all extension fields in received
packets (RFC 5905 doesn't specify a limit on length or number of
extension fields in one packet) */
#define NTP_MAX_EXTENSIONS_LENGTH 1024
/* The minimum and maximum supported length of MAC */
#define NTP_MIN_MAC_LENGTH 16
#define NTP_MAX_MAC_LENGTH MAX_HASH_LENGTH
/* Type definition for leap bits */
typedef enum {
@@ -69,24 +82,28 @@ typedef struct {
NTP_int64 originate_ts;
NTP_int64 receive_ts;
NTP_int64 transmit_ts;
/* Optional extension fields, we don't send packets with them yet */
/* uint8_t extensions[] */
/* Optional message authentication code (MAC) */
NTP_int32 auth_keyid;
uint8_t auth_data[MAX_NTP_AUTH_DATA_LEN];
uint8_t auth_data[NTP_MAX_MAC_LENGTH];
} NTP_Packet;
/* We have to declare a buffer type to hold a datagram read from the
network. Even though we won't be using them (yet?!), this must be
large enough to hold NTP control messages. */
#define NTP_NORMAL_PACKET_LENGTH offsetof(NTP_Packet, auth_keyid)
/* Define the maximum number of bytes that can be read in a single
message. (This is cribbed from ntp.h in the xntpd source code). */
#define MAX_NTP_MESSAGE_SIZE (468+12+16+4)
typedef union {
/* The buffer used to hold a datagram read from the network */
typedef struct {
NTP_Packet ntp_pkt;
uint8_t arbitrary[MAX_NTP_MESSAGE_SIZE];
} ReceiveBuffer;
uint8_t extensions[NTP_MAX_EXTENSIONS_LENGTH];
} NTP_Receive_Buffer;
#define NTP_NORMAL_PACKET_SIZE offsetof(NTP_Packet, auth_keyid)
/* Macros to work with the lvm field */
#define NTP_LVM_TO_LEAP(lvm) (((lvm) >> 6) & 0x3)
#define NTP_LVM_TO_VERSION(lvm) (((lvm) >> 3) & 0x7)
#define NTP_LVM_TO_MODE(lvm) ((lvm) & 0x7)
#define NTP_LVM(leap, version, mode) \
((((leap) << 6) & 0xc0) | (((version) << 3) & 0x38) | ((mode) & 0x07))
#endif /* GOT_NTP_H */