6 #include <sys/socket.h>
7 #include <netinet/in.h>
17 extern int GetRandInt(int nMax);
20 * NTP uses two fixed point formats. The first (l_fp) is the "long"
21 * format and is 64 bits long with the decimal between bits 31 and 32.
22 * This is used for time stamps in the NTP packet header (in network
23 * byte order) and for internal computations of offsets (in local host
24 * byte order). We use the same structure for both signed and unsigned
25 * values, which is a big hack but saves rewriting all the operators
26 * twice. Just to confuse this, we also sometimes just carry the
27 * fractional part in calculations, in both signed and unsigned forms.
28 * Anyway, an l_fp looks like:
31 * 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
32 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
34 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
36 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
37 * REF http://www.eecis.udel.edu/~mills/database/rfc/rfc2030.txt
53 inline void Ntp2Unix(uint32_t &n, time_t &u)
55 // Ntp's time scale starts in 1900, Unix in 1970.
57 u = n - 0x83aa7e80; // 2208988800 1970 - 1900 in seconds
60 inline void ntohl_fp(l_fp *n, l_fp *h)
62 (h)->Ul_i.Xl_ui = ntohl((n)->Ul_i.Xl_ui);
63 (h)->Ul_f.Xl_uf = ntohl((n)->Ul_f.Xl_uf);
67 uint8_t li_vn_mode; /* leap indicator, version and mode */
68 uint8_t stratum; /* peer stratum */
69 uint8_t ppoll; /* peer poll interval */
70 int8_t precision; /* peer clock precision */
71 uint32_t rootdelay; /* distance to primary clock */
72 uint32_t rootdispersion; /* clock dispersion */
73 uint32_t refid; /* reference clock ID */
74 l_fp ref; /* time peer clock was last updated */
75 l_fp org; /* originate time stamp */
76 l_fp rec; /* receive time stamp */
77 l_fp xmt; /* transmit time stamp */
79 uint32_t exten[1]; /* misused */
80 uint8_t mac[5 * sizeof(uint32_t)]; /* mac */
83 int nServersCount = 65;
85 std::string NtpServers[65] = {
115 "ntp1.niiftri.irkutsk.ru",
116 "ntp2.niiftri.irkutsk.ru",
121 "nist1-pa.ustiming.org",
126 "nist1-macon.macon.ga.us",
127 "nist.netservicesgroup.com",
128 "nisttime.carsoncity.k12.mi.us",
129 "nist1-lnk.binary.net",
131 "time-a.timefreq.bldrdoc.gov",
132 "time-b.timefreq.bldrdoc.gov",
133 "time-c.timefreq.bldrdoc.gov",
135 "utcnist.colorado.edu",
136 "utcnist2.colorado.edu",
137 "ntp-nist.ldsbc.net",
138 "nist1-lv.ustiming.org",
140 "nist-time-server.eoni.com",
141 "nist-time-server.eoni.com",
147 "ntp1.meraka.csir.co.za",
151 "ntp1.neology.co.za",
152 "ntp2.neology.co.za",
153 "tick.meraka.csir.co.za",
154 "tock.meraka.csir.co.za",
156 "ntp1.meraka.csir.co.za",
157 "ntp2.meraka.csir.co.za",
163 // ... To be continued
166 bool InitWithRandom(SOCKET &sockfd, socklen_t &servlen, struct sockaddr *pcliaddr)
170 while(nAttempt < 100)
175 int nServerNum = GetRandInt(nServersCount);
177 std::vector<CNetAddr> vIP;
178 bool fRet = LookupHost(NtpServers[nServerNum].c_str(), vIP, 10, true);
182 struct sockaddr_in servaddr;
183 servaddr.sin_family = AF_INET;
184 servaddr.sin_port = htons(123);
187 for(unsigned int i = 0; i < vIP.size(); i++)
189 if ((found = vIP[i].GetInAddr(&servaddr.sin_addr)))
198 sockfd = socket(AF_INET, SOCK_DGRAM, 0);
200 if (sockfd == INVALID_SOCKET)
201 continue; // socket initialization error
203 if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == -1 )
205 continue; // "connection" error
208 *pcliaddr = *((struct sockaddr *) &servaddr);
209 servlen = sizeof(servaddr);
216 bool InitWithHost(std::string &strHostName, SOCKET &sockfd, socklen_t &servlen, struct sockaddr *pcliaddr)
220 std::vector<CNetAddr> vIP;
221 bool fRet = LookupHost(strHostName.c_str(), vIP, 10, true);
225 struct sockaddr_in servaddr;
226 servaddr.sin_family = AF_INET;
227 servaddr.sin_port = htons(123);
230 for(unsigned int i = 0; i < vIP.size(); i++)
232 if ((found = vIP[i].GetInAddr(&servaddr.sin_addr)))
241 sockfd = socket(AF_INET, SOCK_DGRAM, 0);
243 if (sockfd == INVALID_SOCKET)
244 return false; // socket initialization error
246 if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == -1 )
248 return false; // "connection" error
251 *pcliaddr = *((struct sockaddr *) &servaddr);
252 servlen = sizeof(servaddr);
258 int64_t DoReq(SOCKET sockfd, socklen_t servlen, struct sockaddr cliaddr)
260 struct pkt *msg = new pkt;
261 struct pkt *prt = new pkt;
268 msg->rootdispersion=0;
270 msg->ref.Ul_i.Xl_i=0;
271 msg->ref.Ul_f.Xl_f=0;
272 msg->org.Ul_i.Xl_i=0;
273 msg->org.Ul_f.Xl_f=0;
274 msg->rec.Ul_i.Xl_i=0;
275 msg->rec.Ul_f.Xl_f=0;
276 msg->xmt.Ul_i.Xl_i=0;
277 msg->xmt.Ul_f.Xl_f=0;
280 sendto(sockfd, (char *) msg, len, 0, &cliaddr, servlen);
281 int n = recvfrom(sockfd, (char *) msg, len, 0, NULL, NULL);
283 ntohl_fp(&msg->rec, &prt->rec);
284 ntohl_fp(&msg->xmt, &prt->xmt);
286 time_t seconds_receive;
287 time_t seconds_transmit;
289 Ntp2Unix(prt->rec.Ul_i.Xl_ui, seconds_receive);
290 Ntp2Unix(prt->xmt.Ul_i.Xl_ui, seconds_transmit);
295 return (seconds_receive + seconds_transmit) / 2;
300 struct sockaddr cliaddr;
305 if (!InitWithRandom(sockfd, servlen, &cliaddr))
308 int64_t nTime = DoReq(sockfd, servlen, cliaddr);
315 int64_t NtpGetTime(std::string &strHostName)
317 struct sockaddr cliaddr;
322 if (!InitWithHost(strHostName, sockfd, servlen, &cliaddr))
325 int64_t nTime = DoReq(sockfd, servlen, cliaddr);