使用SNTP(Windows C ）从服务器获取时间/日期

Get time/date from server with sntp(windows c++)

本文关键字：获取 服务器 取时间 日期 SNTP Windows 使用      更新时间：2023-10-16

我正在搜索C/C 的工作代码，该代码从服务器（ntp.belnet.be）获得时间和日期。它与UDP一起使用，并使用端口123。

有人可以帮忙吗？

//sending pakket
memset(&sntp_msg_header, 0, sizeof sntp_msg_header);
sntp_msg_header.flags = 27;
sntp_msg_header.originate_timestamp_secs = time(NULL);
// Get data in rxmsg
...
...
// print time
timeval = ntohl(rxmsg.transmit_timestamp_secs) - ((70ul * 365ul + 17ul) * 86400ul);
printf("%s", ctime(&timeval));

这就是我到目前为止所拥有的。但是我无法从中获得正确的数据。我希望这是更多信息。

如果找到了：

import socket
import struct
import sys
import time
TIME1970 = 2208988800L      # Thanks to F.Lundh
client = socket.socket( socket.AF_INET, socket.SOCK_DGRAM )
data = 'x1b' + 47 * ''
client.sendto( data, ( sys.argv[1], 123 ))
data, address = client.recvfrom( 1024 )
if data:
    print 'Response received from:', address
    t = struct.unpack( '!12I', data )[10]
    t -= TIME1970
    print 'tTime=%s' % time.ctime(t)

，但它在Python中。有人可以将其更改为C ，还是有一个转换器？

这就是我使用的。它不是很优雅，但是应该足以使这个想法跨越。基本思想是拥有与网络发送和接收的结构相匹配的结构。反向的尼亚斯最初是不可思议的。值得一提的是，这几乎对错误条件无济于事。您需要解决这个问题。：）

#define ReverseEndianInt(x) ((x) = 
    ((x)&0xff000000) >> 24 |
    ((x)&0x00ff0000) >> 8 |
    ((x)&0x0000ff00) << 8 |
    ((x)&0x000000ff) << 24)
/**
 * NTP Fixed-Point Timestamp Format.
 * From [RFC 5905](http://tools.ietf.org/html/rfc5905).
 */
struct Timestamp
{
    unsigned int seconds; /**< Seconds since Jan 1, 1900. */
    unsigned int fraction; /**< Fractional part of seconds. Integer number of 2^-32 seconds. */
    /**
     * Reverses the Endianness of the timestamp.
     * Network byte order is big endian, so it needs to be switched before
     * sending or reading.
     */
    void ReverseEndian() {
        ReverseEndianInt(seconds);
        ReverseEndianInt(fraction);
    }
    /**
     * Convert to time_t.
     * Returns the integer part of the timestamp in unix time_t format,
     * which is seconds since Jan 1, 1970.
     */
    time_t to_time_t()
    {
        return (seconds - ((70 * 365 + 17) * 86400))&0x7fffffff;
    }
};
/**
 * A Network Time Protocol Message.
 * From [RFC 5905](http://tools.ietf.org/html/rfc5905).
 */
struct NTPMessage
{
    unsigned int mode :3; /**< Mode of the message sender. 3 = Client, 4 = Server */
    unsigned int version :2; /**< Protocol version. Should be set to 3. */
    unsigned int leap :2; /**< Leap seconds warning. See the [RFC](http://tools.ietf.org/html/rfc5905#section-7.3) */
    unsigned char stratum; /**< Servers between client and physical timekeeper. 1 = Server is Connected to Physical Source. 0 = Unknown. */
    unsigned char poll; /**< Max Poll Rate. In log2 seconds. */
    unsigned char precision; /**< Precision of the clock. In log2 seconds. */
    unsigned int sync_distance; /**< Round-trip to reference clock. NTP Short Format. */
    unsigned int drift_rate; /**< Dispersion to reference clock. NTP Short Format. */
    unsigned char ref_clock_id[4]; /**< Reference ID. For Stratum 1 devices, a 4-byte string. For other devices, 4-byte IP address. */
    Timestamp ref; /**< Reference Timestamp. The time when the system clock was last updated. */
    Timestamp orig; /**< Origin Timestamp. Send time of the request. Copied from the request. */
    Timestamp rx; /**< Recieve Timestamp. Reciept time of the request. */
    Timestamp tx; /**< Transmit Timestamp. Send time of the response. If only a single time is needed, use this one. */

    /**
     * Reverses the Endianness of all the timestamps.
     * Network byte order is big endian, so they need to be switched before
     * sending and after reading.
     *
     * Maintaining them in little endian makes them easier to work with
     * locally, though.
     */
    void ReverseEndian() {
        ref.ReverseEndian();
        orig.ReverseEndian();
        rx.ReverseEndian();
        tx.ReverseEndian();
    }
    /**
     * Recieve an NTPMessage.
     * Overwrites this object with values from the recieved packet.
     */
    int recv(int sock)
    {
        int ret = ::recv(sock, (char*)this, sizeof(*this), 0);
        ReverseEndian();
        return ret;
    }
    /**
     * Send an NTPMessage.
     */
    int sendto(int sock, struct sockaddr_in* srv_addr)
    {
        ReverseEndian();
        int ret = ::sendto(sock, (const char*)this, sizeof(*this), 0, (sockaddr*)srv_addr, sizeof(*srv_addr));
        ReverseEndian();
        return ret;
    }
    /**
     * Zero all the values.
     */
    void clear()
    {
        memset(this, 0, sizeof(*this));
    }
};

您会这样使用它，也许在main()中。

WSADATA wsaData;
DWORD ret = WSAStartup(MAKEWORD(2,0), &wsaData);
char *host = "pool.ntp.org"; /* Don't distribute stuff pointing here, it's not polite. */
//char *host = "time.nist.gov"; /* This one's probably ok, but can get grumpy about request rates during debugging. */
NTPMessage msg;
/* Important, if you don't set the version/mode, the server will ignore you. */
msg.clear();
msg.version = 3;
msg.mode = 3 /* client */;
NTPMessage response;
response.clear();
int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
sockaddr_in srv_addr;
memset(&srv_addr, 0, sizeof(srv_addr));
dns_lookup(host, &srv_addr); /* Helper function defined below. */
msg.sendto(sock, &srv_addr);
response.recv(sock);
time_t t = response.tx.to_time_t();
char *s = ctime(&t);
printf("The time is %s.", s);
WSACleanup();

有很多获取IP和端口的方法，但是GetAddrinfo在Windows上做了不错的工作：

int dns_lookup(const char *host, sockaddr_in *out)
{
    struct addrinfo *result;
    int ret = getaddrinfo(host, "ntp", NULL, &result);
    for (struct addrinfo *p = result; p; p = p->ai_next)
    {
        if (p->ai_family != AF_INET)
            continue;
        memcpy(out, p->ai_addr, sizeof(*out));
    }
    freeaddrinfo(result);
}

自然，此解决方案与海滩鲸鱼一样便携，但对我™都有用。

c/ 中的插座比大多数其他语言（尤其是被解释和较新的汇编）的插座略愉快。

为什么不使用

的官方实施
  • http://ntp.org/downloads.html

当然，NTP需要mingw，但是那里有一些库。

  • http://www.hillstone-software.com/hs_ntp_details.htm（它不是免费的，但可以免费尝试，也不是必需的）

Windows自服务器2000版本以来还具有NTP内置。我无法验证它，但是它至少应该在系统上起作用。

。
  • w32tm /help（查找/query部分）
  • 更多文档：http：//technet.microsoft.com/en-us/library/cc773263(v=ws.10).aspx
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