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Utilities: Fix building ntpquery without SO_TIMESTAMP

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If SO_TIMESTAMP is unsupported, we won't be able to determine
kernelspace-to-userspace latency. But other than that, things should
still build and work.

(It's a separate question of what "kernelspace-to-userspace latency"
even means on a microkernel system, where the network card drivers, the
network stack, and ntpquery(1) are all running as userspace programs.)

Also, don't fail completely if settting receive timeout fails.
This commit is contained in:
Sergey Bugaev 2023-09-03 22:15:38 +03:00 • committed by Andrew Kaster
parent 7cb765173c
commit e6cf125535
1 changed files with 12 additions and 2 deletions
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14
Userland/Utilities/ntpquery.cpp
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@ -146,15 +146,17 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
5, 0
};
if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) < 0) {
perror("setsockopt");
return 1;
perror("setsockopt(SO_RCVTIMEO)");
warnln("Continuing without a timeout");
}
#ifdef SO_TIMESTAMP
int enable = 1;
if (setsockopt(fd, SOL_SOCKET, SO_TIMESTAMP, &enable, sizeof(enable)) < 0) {
perror("setsockopt");
return 1;
}
#endif
sockaddr_in peer_address;
memset(&peer_address, 0, sizeof(peer_address));
@ -208,12 +210,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
return 1;
}
#ifdef SO_TIMESTAMP
cmsghdr* cmsg = CMSG_FIRSTHDR(&msg);
VERIFY(cmsg->cmsg_level == SOL_SOCKET);
VERIFY(cmsg->cmsg_type == SCM_TIMESTAMP);
VERIFY(!CMSG_NXTHDR(&msg, cmsg));
timeval kernel_receive_time;
memcpy(&kernel_receive_time, CMSG_DATA(cmsg), sizeof(kernel_receive_time));
#endif
// Checks 3 and 4 from end of section 5 of rfc4330.
if (packet.version_number() != 3 && packet.version_number() != 4) {
@ -240,10 +244,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
NtpTimestamp origin_timestamp = ntp_timestamp_from_timeval(local_transmit_time);
NtpTimestamp receive_timestamp = be64toh(packet.receive_timestamp);
NtpTimestamp transmit_timestamp = be64toh(packet.transmit_timestamp);
#ifdef SO_TIMESTAMP
NtpTimestamp destination_timestamp = ntp_timestamp_from_timeval(kernel_receive_time);
timeval kernel_to_userspace_latency;
timersub(&userspace_receive_time, &kernel_receive_time, &kernel_to_userspace_latency);
#else
NtpTimestamp destination_timestamp = ntp_timestamp_from_timeval(userspace_receive_time);
#endif
if (set_time) {
// FIXME: Do all the time filtering described in 5905, or at least correct for time of flight.
@ -278,9 +286,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
outln("Transmit timestamp: {:#016x} ({})", transmit_timestamp, format_ntp_timestamp(transmit_timestamp).characters());
outln("Destination timestamp: {:#016x} ({})", destination_timestamp, format_ntp_timestamp(destination_timestamp).characters());
#ifdef SO_TIMESTAMP
// When the system isn't under load, user-space t and packet_t are identical. If a shell with `yes` is running, it can be as high as 30ms in this program,
// which gets user-space time immediately after the recvmsg() call. In programs that have an event loop reading from multiple sockets, it could be higher.
outln("Receive latency: {}.{:06} s", (i64)kernel_to_userspace_latency.tv_sec, (int)kernel_to_userspace_latency.tv_usec);
#endif
}
// Parts of the "Clock Filter" computations, https://tools.ietf.org/html/rfc5905#section-10