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/*
* Copyright 2013, The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "SNTPClient.h"
#include <media/stagefright/foundation/ALooper.h>
#include <media/stagefright/Utils.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
namespace android {
SNTPClient::SNTPClient() {
}
status_t SNTPClient::requestTime(const char *host) {
struct hostent *ent;
int64_t requestTimeNTP, requestTimeUs;
ssize_t n;
int64_t responseTimeUs, responseTimeNTP;
int64_t originateTimeNTP, receiveTimeNTP, transmitTimeNTP;
int64_t roundTripTimeNTP, clockOffsetNTP;
status_t err = UNKNOWN_ERROR;
int s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) {
err = -errno;
goto bail;
}
ent = gethostbyname(host);
if (ent == NULL) {
err = -ENOENT;
goto bail2;
}
struct sockaddr_in hostAddr;
memset(hostAddr.sin_zero, 0, sizeof(hostAddr.sin_zero));
hostAddr.sin_family = AF_INET;
hostAddr.sin_port = htons(kNTPPort);
hostAddr.sin_addr.s_addr = *(in_addr_t *)ent->h_addr;
uint8_t packet[kNTPPacketSize];
memset(packet, 0, sizeof(packet));
packet[0] = kNTPModeClient | (kNTPVersion << 3);
requestTimeNTP = getNowNTP();
requestTimeUs = ALooper::GetNowUs();
writeTimeStamp(&packet[kNTPTransmitTimeOffset], requestTimeNTP);
n = sendto(
s, packet, sizeof(packet), 0,
(const struct sockaddr *)&hostAddr, sizeof(hostAddr));
if (n < 0) {
err = -errno;
goto bail2;
}
memset(packet, 0, sizeof(packet));
do {
n = recv(s, packet, sizeof(packet), 0);
} while (n < 0 && errno == EINTR);
if (n < 0) {
err = -errno;
goto bail2;
}
responseTimeUs = ALooper::GetNowUs();
responseTimeNTP = requestTimeNTP + makeNTP(responseTimeUs - requestTimeUs);
originateTimeNTP = readTimeStamp(&packet[kNTPOriginateTimeOffset]);
receiveTimeNTP = readTimeStamp(&packet[kNTPReceiveTimeOffset]);
transmitTimeNTP = readTimeStamp(&packet[kNTPTransmitTimeOffset]);
roundTripTimeNTP =
makeNTP(responseTimeUs - requestTimeUs)
- (transmitTimeNTP - receiveTimeNTP);
clockOffsetNTP =
((receiveTimeNTP - originateTimeNTP)
+ (transmitTimeNTP - responseTimeNTP)) / 2;
mTimeReferenceNTP = responseTimeNTP + clockOffsetNTP;
mTimeReferenceUs = responseTimeUs;
mRoundTripTimeNTP = roundTripTimeNTP;
err = OK;
bail2:
close(s);
s = -1;
bail:
return err;
}
int64_t SNTPClient::adjustTimeUs(int64_t timeUs) const {
uint64_t nowNTP =
mTimeReferenceNTP + makeNTP(timeUs - mTimeReferenceUs);
int64_t nowUs =
(nowNTP >> 32) * 1000000ll
+ ((nowNTP & 0xffffffff) * 1000000ll) / (1ll << 32);
nowUs -= ((70ll * 365 + 17) * 24) * 60 * 60 * 1000000ll;
return nowUs;
}
// static
void SNTPClient::writeTimeStamp(uint8_t *dst, uint64_t ntpTime) {
*dst++ = (ntpTime >> 56) & 0xff;
*dst++ = (ntpTime >> 48) & 0xff;
*dst++ = (ntpTime >> 40) & 0xff;
*dst++ = (ntpTime >> 32) & 0xff;
*dst++ = (ntpTime >> 24) & 0xff;
*dst++ = (ntpTime >> 16) & 0xff;
*dst++ = (ntpTime >> 8) & 0xff;
*dst++ = ntpTime & 0xff;
}
// static
uint64_t SNTPClient::readTimeStamp(const uint8_t *dst) {
return U64_AT(dst);
}
// static
uint64_t SNTPClient::getNowNTP() {
struct timeval tv;
gettimeofday(&tv, NULL /* time zone */);
uint64_t nowUs = tv.tv_sec * 1000000ll + tv.tv_usec;
nowUs += ((70ll * 365 + 17) * 24) * 60 * 60 * 1000000ll;
return makeNTP(nowUs);
}
// static
uint64_t SNTPClient::makeNTP(uint64_t deltaUs) {
uint64_t hi = deltaUs / 1000000ll;
uint64_t lo = ((1ll << 32) * (deltaUs % 1000000ll)) / 1000000ll;
return (hi << 32) | lo;
}
} // namespace android
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