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Add support for SO_TIMESTAMP control messages

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SO_TIMESTAMP messages contain kernel time stamps for received packets,
this should improve accuracy and avoid the impact of CPU scheduling
latencies.
This commit is contained in:
Miroslav Lichvar 2009-08-07 17:24:19 +02:00
parent 0666d04ab2
commit 8de55124a8
1 changed files with 20 additions and 0 deletions
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20
ntp_io.c
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@ -119,6 +119,12 @@ NIO_Initialise(void)
/* Don't quit - we might survive anyway */
}
/* Enable receiving of timestamp control messages */
if (setsockopt(sock_fd, SOL_SOCKET, SO_TIMESTAMP, (char *)&on_off, sizeof(on_off)) < 0) {
LOG(LOGS_ERR, LOGF_NtpIO, "Could not set timestamp socket options");
/* Don't quit - we might survive anyway */
}
/* We want the local IP info too */
if (setsockopt(sock_fd, IPPROTO_IP, IP_PKTINFO, (char *)&on_off, sizeof(on_off)) < 0) {
LOG(LOGS_ERR, LOGF_NtpIO, "Could not request packet info using socket option");
@ -233,6 +239,20 @@ read_from_socket(void *anything)
memcpy(&ipi, CMSG_DATA(cmsg), sizeof(ipi));
remote_addr.local_ip_addr = ntohl(ipi.ipi_spec_dst.s_addr);
}
if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SO_TIMESTAMP) {
struct timeval tv;
double correction;
memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv));
correction = LCL_GetOffsetCorrection(&tv);
UTI_AddDoubleToTimeval(&tv, correction, &tv);
#if 0
UTI_DiffTimevalsToDouble(&correction, &now, &tv);
LOG(LOGS_INFO, LOGF_NtpIO, "timestamp diff: %f", correction);
#endif
now = tv;
}
}
if (status == NTP_NORMAL_PACKET_SIZE) {