Andrew Johnson
b5df3e002a
Fix EditorConfig failure in modules/libcom/RTEMS/epicsNtp.c Add dbDefs to Sphinx API index, move devLib to libcom Rename internal CA enum tag to fix Doxygen complaint Set Clang's minimum MacOS version for aarch64 CPUs
94 lines
3.3 KiB
C
94 lines
3.3 KiB
C
/*************************************************************************\
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* (C) 2014 David Lettier.
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* http://www.lettier.com/
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* use of UDP funktions and implement timeout, HPJ 15.12.2025
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\*************************************************************************/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <arpa/inet.h>
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#include <rtems.h>
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#include "epicsNtp.h"
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int epicsNtpGetTime(char *ntpIp, struct timespec *now)
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{
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int sockfd, n; // Socket file descriptor and the n return result from writing/reading from the socket.
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int portno = 123; // NTP UDP port number.
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// Create and zero out the packet. All 48 bytes worth.
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ntp_packet packet = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
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memset( &packet, 0, sizeof( ntp_packet ) );
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// Set the first byte's bits to 00,011,011 for li = 0, vn = 3, and mode = 3. The rest will be left set to zero.
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*( ( char * ) &packet + 0 ) = 0x1b; // Represents 27 in base 10 or 00011011 in base 2.
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/* Create an UDP socket, use IP address of given nameserver, set the port number
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struct sockaddr_in serv_addr; // Server address data structure.
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add timout of 2 seconds.
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*/
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struct sockaddr_in serv_addr = {
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.sin_family = AF_INET,
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.sin_addr.s_addr = inet_addr(ntpIp),
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.sin_port = htons( portno ),
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};
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sockfd = socket( AF_INET, SOCK_DGRAM, 0 );
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if ( sockfd < 0 ) {
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perror( "epicsNtpGetTime creating socket" );
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return -1;
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}
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/* Set receive timeout to 2 seconds */
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struct timeval tv = { .tv_sec = 2, .tv_usec = 0 };
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if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
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perror("setsockopt");
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return -1;
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}
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// Send it the NTP packet it wants. If n == -1, it failed.
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n = sendto(sockfd, ( char* ) &packet, sizeof( ntp_packet ), 0, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
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if ( n < 0 ) {
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perror( "epicsNtpGetTime sending NTP request" );
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close( sockfd );
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return -1;
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}
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// Wait and receive the packet back from the server. If n == -1, it failed.
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n = recvfrom(sockfd, ( char* ) &packet, sizeof( ntp_packet ), 0, NULL, NULL);
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if (n < 0) {
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if (errno == EAGAIN || errno == EWOULDBLOCK) {
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printf("Timeout - no response\n");
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} else {
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perror( "epicsNtpGetTime reading NTP reply" );
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}
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close( sockfd );
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return -1;
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} else {
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printf("Received %zd bytes\n", n);
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}
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close( sockfd );
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// These two fields contain the time-stamp seconds as the packet left the NTP server.
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// The number of seconds correspond to the seconds passed since 1900.
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// ntohl() converts the bit/byte order from the network's to host's "endianness".
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packet.txTm_s = ntohl( packet.txTm_s ); // Time-stamp seconds.
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packet.txTm_f = ntohl( packet.txTm_f ); // Time-stamp fraction of a second.
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// Extract the 32 bits that represent the time-stamp seconds (since NTP epoch) from when the packet left the server.
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// Subtract 70 years worth of seconds from the seconds since 1900.
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// This leaves the seconds since the UNIX epoch of 1970.
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// (1900)------------------(1970)**************************************(Time Packet Left the Server)
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time_t txTm = ( time_t ) ( packet.txTm_s - NTP_TIMESTAMP_DELTA );
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now->tv_sec = txTm;
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return 0;
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}
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