ntp: update packet processing to NTPv4 (RFC 5905)

broadcast.c

@@ -68,7 +68,6 @@ timeout_handler(void *arbitrary)
   Destination *d = (Destination *) arbitrary;
   NTP_Packet message;
   /* Parameters read from reference module */
-  int version;
   int leap;
   int are_we_synchronised, our_stratum;
   NTP_Leap leap_status;
@@ -77,8 +76,6 @@ timeout_handler(void *arbitrary)
   double our_root_delay, our_root_dispersion;
   struct timeval local_transmit;
 
-  version = 3;
-
   LCL_ReadCookedTime(&local_transmit, NULL);
   REF_GetReferenceParams(&local_transmit,
                          &are_we_synchronised, &leap_status,
@@ -93,7 +90,7 @@ timeout_handler(void *arbitrary)
     leap = LEAP_Unsynchronised;
   }
 
-  message.lvm = ((leap << 6) &0xc0) | ((version << 3) & 0x38) | (MODE_BROADCAST & 0x07);
+  message.lvm = NTP_LVM(leap, NTP_VERSION, MODE_BROADCAST);
   message.stratum = our_stratum;
   message.poll = 6; /* FIXME: what should this be? */
   message.precision = LCL_GetSysPrecisionAsLog();
@@ -115,7 +112,7 @@ timeout_handler(void *arbitrary)
   ts_fuzz = UTI_GetNTPTsFuzz(message.precision);
   LCL_ReadCookedTime(&local_transmit, NULL);
   UTI_TimevalToInt64(&local_transmit, &message.transmit_ts, ts_fuzz);
-  NIO_SendNormalPacket(&message, &d->addr, &d->local_addr);
+  NIO_SendPacket(&message, &d->addr, &d->local_addr, NTP_NORMAL_PACKET_LENGTH);
 
   /* Requeue timeout.  Don't care if interval drifts gradually, so just do it
    * at the end. */

keys.c

@@ -174,7 +174,7 @@ determine_hash_delay(uint32_t key_id)
 
   for (i = 0; i < 10; i++) {
     LCL_ReadRawTime(&before);
-    KEY_GenerateAuth(key_id, (unsigned char *)&pkt, NTP_NORMAL_PACKET_SIZE,
+    KEY_GenerateAuth(key_id, (unsigned char *)&pkt, NTP_NORMAL_PACKET_LENGTH,
         (unsigned char *)&pkt.auth_data, sizeof (pkt.auth_data));
     LCL_ReadRawTime(&after);
 

ntp.h

@@ -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
+#define NTP_NORMAL_PACKET_LENGTH offsetof(NTP_Packet, auth_keyid)
-   network.  Even though we won't be using them (yet?!), this must be
-   large enough to hold NTP control messages. */
 
-/* Define the maximum number of bytes that can be read in a single
+/* The buffer used to hold a datagram read from the network */
-   message.  (This is cribbed from ntp.h in the xntpd source code). */
+typedef struct {
-
-#define MAX_NTP_MESSAGE_SIZE (468+12+16+4)
-
-typedef union {
   NTP_Packet ntp_pkt;
-  uint8_t arbitrary[MAX_NTP_MESSAGE_SIZE];
+  uint8_t extensions[NTP_MAX_EXTENSIONS_LENGTH];
-} ReceiveBuffer;
+} 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 */

ntp_core.h

@@ -60,7 +60,7 @@ extern void NCR_ResetInstance(NCR_Instance inst);
 
 /* This routine is called when a new packet arrives off the network,
    and it relates to a source we have an ongoing protocol exchange with */
-extern void NCR_ProcessKnown(NTP_Packet *message, struct timeval *now, double now_err, NCR_Instance data, int sock_fd, int length);
+extern void NCR_ProcessKnown(NTP_Packet *message, struct timeval *now, double now_err, NCR_Instance data, NTP_Local_Address *local_addr, int length);
 
 /* This routine is called when a new packet arrives off the network,
    and we do not recognize its source */

ntp_io.c

@@ -423,7 +423,7 @@ read_from_socket(void *anything)
      to read, otherwise it will block. */
 
   int status, sock_fd;
-  ReceiveBuffer message;
+  NTP_Receive_Buffer message;
   union sockaddr_in46 where_from;
   unsigned int flags = 0;
   struct timeval now;
@@ -439,7 +439,7 @@ read_from_socket(void *anything)
 
   SCH_GetLastEventTime(&now, &now_err, NULL);
 
-  iov.iov_base = message.arbitrary;
+  iov.iov_base = &message.ntp_pkt;
   iov.iov_len = sizeof(message);
   msg.msg_name = &where_from;
   msg.msg_namelen = sizeof(where_from);
@@ -507,7 +507,7 @@ read_from_socket(void *anything)
           UTI_IPToString(&local_addr.ip_addr), local_addr.sock_fd);
     }
 
-    if (status >= NTP_NORMAL_PACKET_SIZE && status <= sizeof(NTP_Packet)) {
+    if (status >= NTP_NORMAL_PACKET_LENGTH) {
 
       NSR_ProcessReceive((NTP_Packet *) &message.ntp_pkt, &now, now_err,
                          &remote_addr, &local_addr, status);
@@ -521,7 +521,7 @@ read_from_socket(void *anything)
 }
 
 /* ================================================== */
-/* Send a packet to given address */
+/* Send a packet to remote address from local address */
 
 static int
 send_packet(void *packet, int packetlen, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
@@ -628,19 +628,10 @@ send_packet(void *packet, int packetlen, NTP_Remote_Address *remote_addr, NTP_Lo
 }
 
 /* ================================================== */
-/* Send an unauthenticated packet to a given address */
+/* Send a packet to a given address */
 
 int
-NIO_SendNormalPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
+NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr, int length)
 {
-  return send_packet((void *) packet, NTP_NORMAL_PACKET_SIZE, remote_addr, local_addr);
+  return send_packet((void *) packet, length, remote_addr, local_addr);
-}
-
-/* ================================================== */
-/* Send an authenticated packet to a given address */
-
-int
-NIO_SendAuthenticatedPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr, int auth_len)
-{
-  return send_packet((void *) packet, NTP_NORMAL_PACKET_SIZE + auth_len, remote_addr, local_addr);
 }

ntp_io.h

@@ -51,9 +51,6 @@ extern void NIO_CloseClientSocket(int sock_fd);
 extern int NIO_IsServerSocket(int sock_fd);
 
 /* Function to transmit a packet */
-extern int NIO_SendNormalPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr);
+extern int NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr, int length);
-
-/* Function to transmit an authenticated packet */
-extern int NIO_SendAuthenticatedPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr, int auth_len);
 
 #endif /* GOT_NTP_IO_H */

ntp_sources.c

@@ -518,7 +518,7 @@ NSR_ProcessReceive(NTP_Packet *message, struct timeval *now, double now_err, NTP
   find_slot(remote_addr, &slot, &found);
   if (found == 2) { /* Must match IP address AND port number */
     NCR_ProcessKnown(message, now, now_err, get_record(slot)->data,
-                     local_addr->sock_fd, length);
+                     local_addr, length);
   } else {
     NCR_ProcessUnknown(message, now, now_err, remote_addr, local_addr, length);
   }