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1 office 1 /**
2 * @file
3 * SNTP client options list
4 */
5  
6 /*
7 * Copyright (c) 2007-2009 Frédéric Bernon, Simon Goldschmidt
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without modification,
11 * are permitted provided that the following conditions are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright notice,
14 * this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
24 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
26 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
29 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
30 * OF SUCH DAMAGE.
31 *
32 * This file is part of the lwIP TCP/IP stack.
33 *
34 * Author: Frédéric Bernon, Simon Goldschmidt
35 *
36 */
37 #ifndef LWIP_HDR_APPS_SNTP_OPTS_H
38 #define LWIP_HDR_APPS_SNTP_OPTS_H
39  
40 #include "lwip/opt.h"
41 #include "lwip/prot/iana.h"
42  
43 /**
44 * @defgroup sntp_opts Options
45 * @ingroup sntp
46 * @{
47 */
48  
49 /** SNTP macro to change system time in seconds
50 * Define SNTP_SET_SYSTEM_TIME_US(sec, us) to set the time in microseconds
51 * instead of this one if you need the additional precision. Alternatively,
52 * define SNTP_SET_SYSTEM_TIME_NTP(sec, frac) in order to work with native
53 * NTP timestamps instead.
54 */
55 #if !defined SNTP_SET_SYSTEM_TIME || defined __DOXYGEN__
56 #define SNTP_SET_SYSTEM_TIME(sec) LWIP_UNUSED_ARG(sec)
57 #endif
58  
59 /** The maximum number of SNTP servers that can be set */
60 #if !defined SNTP_MAX_SERVERS || defined __DOXYGEN__
61 #define SNTP_MAX_SERVERS LWIP_DHCP_MAX_NTP_SERVERS
62 #endif
63  
64 /** Set this to 1 to implement the callback function called by dhcp when
65 * NTP servers are received. */
66 #if !defined SNTP_GET_SERVERS_FROM_DHCP || defined __DOXYGEN__
67 #define SNTP_GET_SERVERS_FROM_DHCP LWIP_DHCP_GET_NTP_SRV
68 #endif
69  
70 /** Set this to 1 to support DNS names (or IP address strings) to set sntp servers
71 * One server address/name can be defined as default if SNTP_SERVER_DNS == 1:
72 * \#define SNTP_SERVER_ADDRESS "pool.ntp.org"
73 */
74 #if !defined SNTP_SERVER_DNS || defined __DOXYGEN__
75 #define SNTP_SERVER_DNS 0
76 #endif
77  
78 /**
79 * SNTP_DEBUG: Enable debugging for SNTP.
80 */
81 #if !defined SNTP_DEBUG || defined __DOXYGEN__
82 #define SNTP_DEBUG LWIP_DBG_OFF
83 #endif
84  
85 /** SNTP server port */
86 #if !defined SNTP_PORT || defined __DOXYGEN__
87 #define SNTP_PORT LWIP_IANA_PORT_SNTP
88 #endif
89  
90 /** Sanity check:
91 * Define this to
92 * - 0 to turn off sanity checks (default; smaller code)
93 * - >= 1 to check address and port of the response packet to ensure the
94 * response comes from the server we sent the request to.
95 * - >= 2 to check returned Originate Timestamp against Transmit Timestamp
96 * sent to the server (to ensure response to older request).
97 * - >= 3 @todo: discard reply if any of the VN, Stratum, or Transmit Timestamp
98 * fields is 0 or the Mode field is not 4 (unicast) or 5 (broadcast).
99 * - >= 4 @todo: to check that the Root Delay and Root Dispersion fields are each
100 * greater than or equal to 0 and less than infinity, where infinity is
101 * currently a cozy number like one second. This check avoids using a
102 * server whose synchronization source has expired for a very long time.
103 */
104 #if !defined SNTP_CHECK_RESPONSE || defined __DOXYGEN__
105 #define SNTP_CHECK_RESPONSE 0
106 #endif
107  
108 /** Enable round-trip delay compensation.
109 * Compensate for the round-trip delay by calculating the clock offset from
110 * the originate, receive, transmit and destination timestamps, as per RFC.
111 *
112 * The calculation requires compiler support for 64-bit integers. Also, either
113 * SNTP_SET_SYSTEM_TIME_US or SNTP_SET_SYSTEM_TIME_NTP has to be implemented
114 * for setting the system clock with sub-second precision. Likewise, either
115 * SNTP_GET_SYSTEM_TIME or SNTP_GET_SYSTEM_TIME_NTP needs to be implemented
116 * with sub-second precision.
117 *
118 * Although not strictly required, it makes sense to combine this option with
119 * SNTP_CHECK_RESPONSE >= 2 for sanity-checking of the received timestamps.
120 * Also, in order for the round-trip calculation to work, the difference
121 * between the local clock and the NTP server clock must not be larger than
122 * about 34 years. If that limit is exceeded, the implementation will fall back
123 * to setting the clock without compensation. In order to ensure that the local
124 * clock is always within the permitted range for compensation, even at first
125 * try, it may be necessary to store at least the current year in non-volatile
126 * memory.
127 */
128 #if !defined SNTP_COMP_ROUNDTRIP || defined __DOXYGEN__
129 #define SNTP_COMP_ROUNDTRIP 0
130 #endif
131  
132 /** According to the RFC, this shall be a random delay
133 * between 1 and 5 minutes (in milliseconds) to prevent load peaks.
134 * This can be defined to a random generation function,
135 * which must return the delay in milliseconds as u32_t.
136 * Turned off by default.
137 */
138 #if !defined SNTP_STARTUP_DELAY || defined __DOXYGEN__
139 #ifdef LWIP_RAND
140 #define SNTP_STARTUP_DELAY 1
141 #else
142 #define SNTP_STARTUP_DELAY 0
143 #endif
144 #endif
145  
146 /** If you want the startup delay to be a function, define this
147 * to a function (including the brackets) and define SNTP_STARTUP_DELAY to 1.
148 */
149 #if !defined SNTP_STARTUP_DELAY_FUNC || defined __DOXYGEN__
150 #define SNTP_STARTUP_DELAY_FUNC (LWIP_RAND() % 5000)
151 #endif
152  
153 /** SNTP receive timeout - in milliseconds
154 * Also used as retry timeout - this shouldn't be too low.
155 * Default is 15 seconds. Must not be beolw 15 seconds by specification (i.e. 15000)
156 */
157 #if !defined SNTP_RECV_TIMEOUT || defined __DOXYGEN__
158 #define SNTP_RECV_TIMEOUT 15000
159 #endif
160  
161 /** SNTP update delay - in milliseconds
162 * Default is 1 hour. Must not be beolw 60 seconds by specification (i.e. 60000)
163 */
164 #if !defined SNTP_UPDATE_DELAY || defined __DOXYGEN__
165 #define SNTP_UPDATE_DELAY 3600000
166 #endif
167  
168 /** SNTP macro to get system time, used with SNTP_CHECK_RESPONSE >= 2
169 * to send in request and compare in response. Also used for round-trip
170 * delay compensation if SNTP_COMP_ROUNDTRIP != 0.
171 * Alternatively, define SNTP_GET_SYSTEM_TIME_NTP(sec, frac) in order to
172 * work with native NTP timestamps instead.
173 */
174 #if !defined SNTP_GET_SYSTEM_TIME || defined __DOXYGEN__
175 #define SNTP_GET_SYSTEM_TIME(sec, us) do { (sec) = 0; (us) = 0; } while(0)
176 #endif
177  
178 /** Default retry timeout (in milliseconds) if the response
179 * received is invalid.
180 * This is doubled with each retry until SNTP_RETRY_TIMEOUT_MAX is reached.
181 */
182 #if !defined SNTP_RETRY_TIMEOUT || defined __DOXYGEN__
183 #define SNTP_RETRY_TIMEOUT SNTP_RECV_TIMEOUT
184 #endif
185  
186 /** Maximum retry timeout (in milliseconds). */
187 #if !defined SNTP_RETRY_TIMEOUT_MAX || defined __DOXYGEN__
188 #define SNTP_RETRY_TIMEOUT_MAX (SNTP_RETRY_TIMEOUT * 10)
189 #endif
190  
191 /** Increase retry timeout with every retry sent
192 * Default is on to conform to RFC.
193 */
194 #if !defined SNTP_RETRY_TIMEOUT_EXP || defined __DOXYGEN__
195 #define SNTP_RETRY_TIMEOUT_EXP 1
196 #endif
197  
198 /**
199 * @}
200 */
201  
202 #endif /* LWIP_HDR_APPS_SNTP_OPTS_H */