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e5abf3ad2b
When chronyd gets a kernel or hardware transmit timestamp after sending an NTP message to a server, peer, or client (using interleaved mode), it needs the address and content of the message to be able to correctly assign the timestamp to the server, peer, or client. The timestamps are processed asynchronously. The kernel provides with each timestamp the data-link frame that was timestamped, but chronyd can extract the necessary data only from plain IPv4 and IPv6 packets in Ethernet frames, possibly including VLAN tags. If the NTP packets are transmitted by a non-Ethernet device, or they are encapsulated in another layer (e.g. a WireGuard tunnel), chronyd is not able to extract the data and use the kernel or hardware transmit timestamps, having to fall back to less accurate daemon timestamps. Add an alternative method using transmit IDs assigned to each message (supported since Linux 6.13), which are provided by the kernel with the timestamp in the error queue, and map them to messages, addresses and ports saved in a ring buffer, whose size can be configured by the new maxtxbuffers directive. Fow now, set the default maxtxbuffers to 0 (disabled). If set to a non-zero value, allocate the ring buffer to the maximum size on start. As a future improvement, it could be allocated only when the extraction of the UDP payload fails, or the extracted message is not the expected NTP message. The size could grow dynamically when a transmit ID is missed.
47 lines
1.7 KiB
C
47 lines
1.7 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Miroslav Lichvar 2016
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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This is the header file for the Linux-specific NTP socket I/O bits.
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*/
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#ifndef GOT_NTP_IO_LINUX_H
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#define GOT_NTP_IO_LINUX_H
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#include "socket.h"
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extern void NIO_Linux_Initialise(void);
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extern void NIO_Linux_Finalise(void);
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extern int NIO_Linux_IsHwTsEnabled(void);
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extern int NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events);
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extern int NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
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NTP_Local_Timestamp *local_ts, int event);
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extern void NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd,
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NTP_Remote_Address *remote_addr);
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#endif
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