5 #include <sys/socket.h>
7 #include <netinet/in.h>
18 extern int GetRandInt(int nMax);
21 * NTP uses two fixed point formats. The first (l_fp) is the "long"
22 * format and is 64 bits long with the decimal between bits 31 and 32.
23 * This is used for time stamps in the NTP packet header (in network
24 * byte order) and for internal computations of offsets (in local host
25 * byte order). We use the same structure for both signed and unsigned
26 * values, which is a big hack but saves rewriting all the operators
27 * twice. Just to confuse this, we also sometimes just carry the
28 * fractional part in calculations, in both signed and unsigned forms.
29 * Anyway, an l_fp looks like:
32 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
33 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
35 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
37 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
38 * REF http://www.eecis.udel.edu/~mills/database/rfc/rfc2030.txt
54 inline void Ntp2Unix(uint32_t &n, time_t &u)
56 // Ntp's time scale starts in 1900, Unix in 1970.
58 u = n - 0x83aa7e80; // 2208988800 1970 - 1900 in seconds
61 inline void ntohl_fp(l_fp *n, l_fp *h)
63 (h)->Ul_i.Xl_ui = ntohl((n)->Ul_i.Xl_ui);
64 (h)->Ul_f.Xl_uf = ntohl((n)->Ul_f.Xl_uf);
68 uint8_t li_vn_mode; /* leap indicator, version and mode */
69 uint8_t stratum; /* peer stratum */
70 uint8_t ppoll; /* peer poll interval */
71 int8_t precision; /* peer clock precision */
72 uint32_t rootdelay; /* distance to primary clock */
73 uint32_t rootdispersion; /* clock dispersion */
74 uint32_t refid; /* reference clock ID */
75 l_fp ref; /* time peer clock was last updated */
76 l_fp org; /* originate time stamp */
77 l_fp rec; /* receive time stamp */
78 l_fp xmt; /* transmit time stamp */
80 uint32_t exten[1]; /* misused */
81 uint8_t mac[5 * sizeof(uint32_t)]; /* mac */
84 int nServersCount = 103;
86 std::string NtpServers[103] = {
114 "ntp1.niiftri.irkutsk.ru",
115 "ntp2.niiftri.irkutsk.ru",
126 "nist1-pa.ustiming.org",
131 "nist1-macon.macon.ga.us",
132 "nist.netservicesgroup.com",
133 "nisttime.carsoncity.k12.mi.us",
134 "nist1-lnk.binary.net",
136 "time-a.timefreq.bldrdoc.gov",
137 "time-b.timefreq.bldrdoc.gov",
138 "time-c.timefreq.bldrdoc.gov",
140 "utcnist.colorado.edu",
141 "utcnist2.colorado.edu",
142 "ntp-nist.ldsbc.net",
143 "nist1-lv.ustiming.org",
145 "nist-time-server.eoni.com",
146 "nist-time-server.eoni.com",
156 "ntp1.meraka.csir.co.za",
160 "ntp1.neology.co.za",
161 "ntp2.neology.co.za",
162 "tick.meraka.csir.co.za",
163 "tock.meraka.csir.co.za",
165 "ntp1.meraka.csir.co.za",
166 "ntp2.meraka.csir.co.za",
194 "ntp.cis.strath.ac.uk",
208 // ... To be continued
211 bool InitWithRandom(SOCKET &sockfd, socklen_t &servlen, struct sockaddr *pcliaddr)
215 while(nAttempt < 100)
220 int nServerNum = GetRandInt(nServersCount);
222 std::vector<CNetAddr> vIP;
223 bool fRet = LookupHost(NtpServers[nServerNum].c_str(), vIP, 10, true);
227 struct sockaddr_in servaddr;
228 servaddr.sin_family = AF_INET;
229 servaddr.sin_port = htons(123);
232 for(unsigned int i = 0; i < vIP.size(); i++)
234 if ((found = vIP[i].GetInAddr(&servaddr.sin_addr)))
243 sockfd = socket(AF_INET, SOCK_DGRAM, 0);
245 if (sockfd == INVALID_SOCKET)
246 continue; // socket initialization error
248 if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == -1 )
250 continue; // "connection" error
253 *pcliaddr = *((struct sockaddr *) &servaddr);
254 servlen = sizeof(servaddr);
261 bool InitWithHost(std::string &strHostName, SOCKET &sockfd, socklen_t &servlen, struct sockaddr *pcliaddr)
265 std::vector<CNetAddr> vIP;
266 bool fRet = LookupHost(strHostName.c_str(), vIP, 10, true);
270 struct sockaddr_in servaddr;
271 servaddr.sin_family = AF_INET;
272 servaddr.sin_port = htons(123);
275 for(unsigned int i = 0; i < vIP.size(); i++)
277 if ((found = vIP[i].GetInAddr(&servaddr.sin_addr)))
286 sockfd = socket(AF_INET, SOCK_DGRAM, 0);
288 if (sockfd == INVALID_SOCKET)
289 return false; // socket initialization error
291 if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == -1 )
293 return false; // "connection" error
297 *pcliaddr = *((struct sockaddr *) &servaddr);
298 servlen = sizeof(servaddr);
304 int64_t DoReq(SOCKET sockfd, socklen_t servlen, struct sockaddr cliaddr)
309 if (ioctlsocket(sockfd, FIONBIO, &nOne) == SOCKET_ERROR)
311 printf("ConnectSocket() : ioctlsocket non-blocking setting failed, error %d\n", WSAGetLastError());
313 if (fcntl(sockfd, F_SETFL, O_NONBLOCK) == SOCKET_ERROR)
315 printf("ConnectSocket() : fcntl non-blocking setting failed, error %d\n", errno);
320 struct pkt *msg = new pkt;
321 struct pkt *prt = new pkt;
328 msg->rootdispersion=0;
330 msg->ref.Ul_i.Xl_i=0;
331 msg->ref.Ul_f.Xl_f=0;
332 msg->org.Ul_i.Xl_i=0;
333 msg->org.Ul_f.Xl_f=0;
334 msg->rec.Ul_i.Xl_i=0;
335 msg->rec.Ul_f.Xl_f=0;
336 msg->xmt.Ul_i.Xl_i=0;
337 msg->xmt.Ul_f.Xl_f=0;
340 int retcode = sendto(sockfd, (char *) msg, len, 0, &cliaddr, servlen);
342 printf("sendto() failed: %d", retcode);
347 struct timeval timeout = {5, 0};
349 FD_SET(sockfd, &fdset);
351 retcode = select(sockfd + 1, &fdset, NULL, NULL, &timeout);
354 printf("recvfrom() error");
358 recvfrom(sockfd, (char *) msg, len, 0, NULL, NULL);
360 ntohl_fp(&msg->rec, &prt->rec);
361 ntohl_fp(&msg->xmt, &prt->xmt);
363 time_t seconds_receive;
364 time_t seconds_transmit;
366 Ntp2Unix(prt->rec.Ul_i.Xl_ui, seconds_receive);
367 Ntp2Unix(prt->xmt.Ul_i.Xl_ui, seconds_transmit);
372 return (seconds_receive + seconds_transmit) / 2;
377 struct sockaddr cliaddr;
382 if (!InitWithRandom(sockfd, servlen, &cliaddr))
385 int64_t nTime = DoReq(sockfd, servlen, cliaddr);
392 int64_t NtpGetTime(std::string &strHostName)
394 struct sockaddr cliaddr;
399 if (!InitWithHost(strHostName, sockfd, servlen, &cliaddr))
402 int64_t nTime = DoReq(sockfd, servlen, cliaddr);