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ptp-utilities.c
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ptp-utilities.c
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/*
* This file is part of Shairport Sync.
* Copyright (c) Mike Brady 2020 -- 2023
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "definitions.h"
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#ifdef COMPILE_FOR_FREEBSD
#include <netinet/in.h>
#endif
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#define __STDC_FORMAT_MACROS
#include "common.h"
#include "ptp-utilities.h"
#include <inttypes.h>
#include <unistd.h>
int shm_fd;
void *mapped_addr = NULL;
// returns a copy of the shared memory data from the nqptp
// shared memory interface, so long as it's open.
int get_nqptp_data(struct shm_structure *nqptp_data) {
// uint64_t tn = get_absolute_time_in_ns(); // if interested in timing the function...
struct shm_structure local_nqptp_data;
int response = -1; // presume the worst. Fix it on success
// We need to ensure that when we read the record, we are not reading it while it is partly
// updated and therefore inconsistent. To achieve this, we do the following:
// We ensure that the secondary record is written by NQPTP _strictly after_
// all writes to the main record are complete.
// Here we read two copies of the entire record, the second
// _strictly after_ all reads from the first are complete.
// (Strict write and read ordering is ensured using the __sync_synchronize() construct.)
// We then compare the main record in the first read to the
// secondary record in the second read.
// If they are equal, we can be sure we have not read a record that has been
// made inconsistent by an interrupted update.
if ((mapped_addr != MAP_FAILED) && (mapped_addr != NULL)) {
int loop_count = 1;
do {
__sync_synchronize();
memcpy(nqptp_data, (char *)mapped_addr, sizeof(struct shm_structure));
__sync_synchronize();
// read again strictly after a full read -- this is to read the secondary strictly after the
// primary
memcpy(&local_nqptp_data, (char *)mapped_addr, sizeof(struct shm_structure));
// check that the main and secondary data sets match
if (memcmp(&nqptp_data->main, &local_nqptp_data.secondary, sizeof(shm_structure_set)) != 0) {
usleep(2); // microseconds
loop_count++;
}
} while (
(memcmp(&nqptp_data->main, &local_nqptp_data.secondary, sizeof(shm_structure_set)) != 0) &&
(loop_count < 10));
if (loop_count == 10) {
debug(1, "get_nqptp_data -- main and secondary records don't match after %d attempts!",
loop_count);
response = -1;
} else {
response = 0;
}
} else {
if (mapped_addr == NULL)
debug(1, "get_nqptp_data failed because the mapped_addr is NULL");
else if (mapped_addr == MAP_FAILED)
debug(1, "get_nqptp_data failed because the mapped_addr is MAP_FAILED");
else
debug(1, "get_nqptp_data failed");
}
// int64_t et = get_absolute_time_in_ns() - tn;
// debug(1, "get_nqptp_data time: %.3f microseconds.", 0.001 * et);
return response;
}
int ptp_get_clock_version() {
int response = 0; // no version number information available
struct shm_structure nqptp_data;
if (get_nqptp_data(&nqptp_data) == 0) {
response = nqptp_data.version;
}
return response;
}
int ptp_get_clock_info(uint64_t *actual_clock_id, uint64_t *time_of_sample, uint64_t *raw_offset,
uint64_t *mastership_start_time) {
int response = clock_ok;
if (actual_clock_id != NULL)
*actual_clock_id = 0;
if (raw_offset != NULL)
*raw_offset = 0;
if (time_of_sample != NULL)
*time_of_sample = 0;
if (mastership_start_time != NULL)
*mastership_start_time = 0;
// if (ptp_shm_interface_open() == 0) {
struct shm_structure nqptp_data;
if (get_nqptp_data(&nqptp_data) == 0) {
if (nqptp_data.version == NQPTP_SHM_STRUCTURES_VERSION) {
// assuming a clock id can not be zero
if (nqptp_data.main.master_clock_id != 0) {
if (actual_clock_id != NULL)
*actual_clock_id = nqptp_data.main.master_clock_id;
if (time_of_sample != NULL)
*time_of_sample = nqptp_data.main.local_time;
if (raw_offset != NULL)
*raw_offset = nqptp_data.main.local_to_master_time_offset;
if (mastership_start_time != NULL)
*mastership_start_time = nqptp_data.main.master_clock_start_time;
} else {
response = clock_no_master;
}
} else {
// the version can not be zero. If zero is returned here, it means that the shared memory is
// not yet initialised, so not availalbe
if (nqptp_data.version == 0)
response = clock_service_unavailable;
else
response = clock_version_mismatch;
}
} else {
response = clock_data_unavailable;
}
return response;
}
int ptp_shm_interface_open() {
int response = 0;
debug(2, "ptp_shm_interface_open with mapped_addr = %" PRIuPTR "", mapped_addr);
if ((mapped_addr == NULL) || (mapped_addr == MAP_FAILED)) {
response = -1;
if (mapped_addr == NULL)
debug(3, "ptp_shm_interface_open is NULL");
if (mapped_addr == MAP_FAILED)
debug(3, "ptp_shm_interface_open is MAP_FAILED");
if (strcmp(config.nqptp_shared_memory_interface_name, "") != 0) {
response = 0;
int shared_memory_file_descriptor =
shm_open(config.nqptp_shared_memory_interface_name, O_RDONLY, 0);
if (shared_memory_file_descriptor >= 0) {
mapped_addr =
// needs to be PROT_READ | PROT_WRITE to allow the mapped memory to be writable for the
// mutex to lock and unlock
mmap(NULL, sizeof(struct shm_structure), PROT_READ, MAP_SHARED,
shared_memory_file_descriptor, 0);
if (mapped_addr == MAP_FAILED) {
response = -1;
}
if (close(shared_memory_file_descriptor) == -1) {
response = -1;
}
} else {
response = -1;
}
} else {
debug(1, "No config.nqptp_shared_memory_interface_name");
}
if (response == 0)
debug(2, "ptp_shm_interface_open -- success!");
else
debug(2, "ptp_shm_interface_open -- fail!");
} else {
debug(2, "ptp_shm_interface_open -- already open!");
}
return response;
}
int ptp_shm_interface_close() {
int response = -1;
if ((mapped_addr != MAP_FAILED) && (mapped_addr != NULL)) {
debug(2, "ptp_shm_interface_close");
response = munmap(mapped_addr, sizeof(struct shm_structure));
if (response != 0)
debug(1, "error unmapping shared memory.");
}
mapped_addr = NULL;
return response;
}
void ptp_send_control_message_string(const char *msg) {
size_t full_message_size =
strlen(config.nqptp_shared_memory_interface_name) + strlen(" ") + strlen(msg) + 1;
char *full_message = malloc(full_message_size);
if (full_message != NULL) {
*full_message = '\0';
snprintf(full_message, full_message_size, "%s %s", config.nqptp_shared_memory_interface_name,
msg);
debug(2, "Send control message to NQPTP: \"%s\"", full_message);
int s;
int ret;
struct addrinfo hints, *info;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_PASSIVE;
/* nqptp is only controllable via localhost */
char portstr[20];
snprintf(portstr, 20, "%d", NQPTP_CONTROL_PORT);
ret = getaddrinfo("localhost", portstr, &hints, &info);
if (ret) {
die("getaddrinfo: %s", gai_strerror(ret));
}
/* Create a datagram socket in the internet domain and use the
* default protocol (UDP).
*/
if ((s = socket(info->ai_family, info->ai_socktype, 0)) < 0) {
die("Can't open a socket to NQPTP");
}
/* Send the message in buf to the server */
if (sendto(s, full_message, full_message_size, 0, info->ai_addr, info->ai_addrlen) <
0) {
die("error sending timing_peer_list to NQPTP");
}
/* Deallocate the socket */
close(s);
freeaddrinfo(info);
/* deallocate the message string */
free(full_message);
} else {
debug(1, "Couldn't allocate memory to prepare a qualified ptp control message string.");
}
}