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Diffstat (limited to 'lib/ClockTAI.cpp')
| -rw-r--r-- | lib/ClockTAI.cpp | 562 |
1 files changed, 562 insertions, 0 deletions
diff --git a/lib/ClockTAI.cpp b/lib/ClockTAI.cpp new file mode 100644 index 0000000..42497f4 --- /dev/null +++ b/lib/ClockTAI.cpp @@ -0,0 +1,562 @@ +/* + Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, + 2011, 2012 Her Majesty the Queen in Right of Canada (Communications + Research Center Canada) + + Copyright (C) 2019 + Matthias P. Braendli, matthias.braendli@mpb.li + + http://www.opendigitalradio.org + */ +/* + This file is part of ODR-DabMux. + + ODR-DabMux is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as + published by the Free Software Foundation, either version 3 of the + License, or (at your option) any later version. + + ODR-DabMux is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with ODR-DabMux. If not, see <http://www.gnu.org/licenses/>. +*/ + +/* This file downloads the TAI-UTC bulletins from the from IETF and parses them + * so that correct time can be communicated in EDI timestamps. + * + * This file contains self-test code that can be executed by running + * g++ -g -Wall -DTEST -DHAVE_CURL -std=c++11 -lcurl -pthread \ + * ClockTAI.cpp Log.cpp RemoteControl.cpp -lboost_system -o taitest && ./taitest + */ + +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif + +#include "ClockTAI.h" +#include "Log.h" + +#include <time.h> +#include <stdio.h> +#include <errno.h> +#if SUPPORT_SETTING_CLOCK_TAI +# include <sys/timex.h> +#endif +#ifdef HAVE_CURL +# include <curl/curl.h> +#endif +#include <array> +#include <string> +#include <iostream> +#include <algorithm> +#include <regex> + +using namespace std; + +#ifdef TEST +static bool wait_longer = true; +#endif + +constexpr int download_retry_interval_hours = 1; + +// Offset between NTP time and POSIX time: +// timestamp_unix = timestamp_ntp - ntp_unix_offset +const int64_t ntp_unix_offset = 2208988800L; + +// leap seconds insertion bulletin is available from the IETF and in the TZ +// distribution +static array<const char*, 2> default_tai_urls = { + "https://www.ietf.org/timezones/data/leap-seconds.list", + "https://raw.githubusercontent.com/eggert/tz/master/leap-seconds.list", +}; + +// According to the Filesystem Hierarchy Standard, the data in +// /var/tmp "must not be deleted when the system is booted." +static const char *tai_cache_location = "/var/tmp/odr-dabmux-leap-seconds.cache"; + +// read TAI offset from a valid bulletin in IETF format +static int parse_ietf_bulletin(const std::string& bulletin) +{ + // Example Line: + // 3692217600 37 # 1 Jan 2017 + // + // NTP timestamp<TAB>leap seconds<TAB># some comment + // The NTP timestamp starts at epoch 1.1.1900. + // The difference between NTP timestamps and unix epoch is 70 + // years i.e. 2208988800 seconds + + std::regex regex_bulletin(R"(([0-9]+)\s+([0-9]+)\s+#.*)"); + + time_t now = time(nullptr); + + int tai_utc_offset = 0; + + int tai_utc_offset_valid = false; + + stringstream ss(bulletin); + + /* We cannot just take the last line, because it might + * be in the future, announcing an upcoming leap second. + * + * So we need to look at the current date, and compare it + * with the date of the leap second. + */ + for (string line; getline(ss, line); ) { + + std::smatch bulletin_entry; + + bool is_match = std::regex_search(line, bulletin_entry, regex_bulletin); + if (is_match) { + if (bulletin_entry.size() != 3) { + throw runtime_error( + "Incorrect number of matched TAI IETF bulletin entries"); + } + const string bulletin_ntp_timestamp(bulletin_entry[1]); + const string bulletin_offset(bulletin_entry[2]); + + const int64_t timestamp_unix = + std::atoll(bulletin_ntp_timestamp.c_str()) - ntp_unix_offset; + + const int offset = std::atoi(bulletin_offset.c_str()); + // Ignore entries announcing leap seconds in the future + if (timestamp_unix < now) { + tai_utc_offset = offset; + tai_utc_offset_valid = true; + } +#if TEST + else { + cerr << "IETF Ignoring offset " << bulletin_offset << + " at TS " << bulletin_ntp_timestamp << + " in the future" << endl; + } +#endif + } + } + + if (not tai_utc_offset_valid) { + throw runtime_error("No data in TAI bulletin"); + } + + return tai_utc_offset; +} + + +struct bulletin_state { + bool valid = false; + int64_t expiry = 0; + int offset = 0; + + bool usable() const { return valid and expiry > 0; } +}; + +static bulletin_state parse_bulletin(const string& bulletin) +{ + // The bulletin contains one line that specifies an expiration date + // in NTP time. If that point in time is in the future, we consider + // the bulletin valid. + // + // The entry looks like this: + //#@ 3707596800 + + bulletin_state ret; + + std::regex regex_expiration(R"(#@\s+([0-9]+))"); + + time_t now = time(nullptr); + + stringstream ss(bulletin); + + for (string line; getline(ss, line); ) { + std::smatch bulletin_entry; + + bool is_match = std::regex_search(line, bulletin_entry, regex_expiration); + if (is_match) { + if (bulletin_entry.size() != 2) { + throw runtime_error( + "Incorrect number of matched TAI IETF bulletin expiration"); + } + const string expiry_data_str(bulletin_entry[1]); + const int64_t expiry_unix = + std::atoll(expiry_data_str.c_str()) - ntp_unix_offset; + +#ifdef TEST + etiLog.level(info) << "Bulletin expires in " << expiry_unix - now; +#endif + ret.expiry = expiry_unix - now; + try { + ret.offset = parse_ietf_bulletin(bulletin); + ret.valid = true; + } + catch (const runtime_error& e) { + etiLog.level(warn) << "Bulletin expiry ok but parse error: " << e.what(); + } + break; + } + } + return ret; +} + + +// callback that receives data from cURL +static size_t fill_bulletin(char *ptr, size_t size, size_t nmemb, void *ctx) +{ + auto *bulletin = reinterpret_cast<stringstream*>(ctx); + + size_t len = size * nmemb; + for (size_t i = 0; i < len; i++) { + *bulletin << ptr[i]; + } + return len; +} + +static string download_tai_utc_bulletin(const char* url) +{ + stringstream bulletin; + +#ifdef HAVE_CURL + CURL *curl; + CURLcode res; + + curl = curl_easy_init(); + if (curl) { + curl_easy_setopt(curl, CURLOPT_URL, url); + /* Tell libcurl to follow redirection */ + curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); + curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fill_bulletin); + curl_easy_setopt(curl, CURLOPT_WRITEDATA, &bulletin); + + res = curl_easy_perform(curl); + /* always cleanup ! */ + curl_easy_cleanup(curl); + + if (res != CURLE_OK) { + throw runtime_error( "TAI-UTC bulletin download failed: " + + string(curl_easy_strerror(res))); + } + } + return bulletin.str(); +#else + throw runtime_error("Cannot download TAI Clock information without cURL"); +#endif // HAVE_CURL +} + +static string load_bulletin_from_file(const char* cache_filename) +{ + // Clear the bulletin + ifstream f(cache_filename); + if (not f.good()) { + return {}; + } + + stringstream ss; + ss << f.rdbuf(); + f.close(); + + return ss.str(); +} + +ClockTAI::ClockTAI(const std::vector<std::string>& bulletin_urls) : + RemoteControllable("clocktai") +{ + RC_ADD_PARAMETER(expiry, "Number of seconds until TAI Bulletin expires"); + + if (bulletin_urls.empty()) { + etiLog.level(debug) << "Initialising default TAI Bulletin URLs"; + for (const auto url : default_tai_urls) { + m_bulletin_urls.push_back(url); + } + } + else { + etiLog.level(debug) << "Initialising user-configured TAI Bulletin URLs"; + m_bulletin_urls = bulletin_urls; + } + + for (const auto url : m_bulletin_urls) { + etiLog.level(info) << "TAI Bulletin URL: '" << url << "'"; + } +} + +int ClockTAI::get_valid_offset() +{ + int offset = 0; + bool offset_valid = false; + + std::unique_lock<std::mutex> lock(m_data_mutex); + + const auto state = parse_bulletin(m_bulletin); + if (state.usable()) { +#if TEST + etiLog.level(info) << "Bulletin already valid"; +#endif + offset = state.offset; + offset_valid = true; + } + else { + const auto cache_bulletin = load_bulletin_from_file(tai_cache_location); + const auto cache_state = parse_bulletin(cache_bulletin); + + if (cache_state.usable()) { + m_bulletin = cache_bulletin; + offset = cache_state.offset; + offset_valid = true; +#if TEST + etiLog.level(info) << "Bulletin from cache valid with offset=" << offset; +#endif + } + else { + for (const auto url : m_bulletin_urls) { + try { +#if TEST + etiLog.level(info) << "Load bulletin from " << url; +#endif + const auto new_bulletin = download_tai_utc_bulletin(url.c_str()); + const auto new_state = parse_bulletin(new_bulletin); + if (new_state.usable()) { + m_bulletin = new_bulletin; + offset = new_state.offset; + offset_valid = true; + + etiLog.level(debug) << "Loaded valid TAI Bulletin from " << + url << " giving offset=" << offset; + } + else { + etiLog.level(debug) << "Skipping invalid TAI bulletin from " + << url; + } + } + catch (const runtime_error& e) { + etiLog.level(warn) << + "TAI-UTC offset could not be retrieved from " << + url << " : " << e.what(); + } + + if (offset_valid) { + update_cache(tai_cache_location); + break; + } + } + } + } + + if (offset_valid) { + // With the current evolution of the offset, we're probably going + // to reach 500 long after DAB gets replaced by another standard. + if (offset < 0 or offset > 500) { + stringstream ss; + ss << "TAI offset " << offset << " out of range"; + throw range_error(ss.str()); + } + + return offset; + } + else { + // Try again later + throw download_failed(); + } +} + + +int ClockTAI::get_offset() +{ + using namespace std::chrono; + const auto time_now = system_clock::now(); + + std::unique_lock<std::mutex> lock(m_data_mutex); + + if (not m_offset_valid) { +#ifdef TEST + // Assume we've downloaded it in the past: + + m_offset = 37; // Valid in early 2017 + m_offset_valid = true; + + // Simulate requiring a new download + m_bulletin_download_time = time_now - hours(24 * 40); +#else + // First time we run we must block until we know + // the offset + lock.unlock(); + try { + m_offset = get_valid_offset(); + } + catch (const download_failed&) { + throw runtime_error("Unable to download TAI bulletin"); + } + lock.lock(); + m_offset_valid = true; + m_bulletin_download_time = time_now; +#endif + etiLog.level(info) << + "Initialised TAI-UTC offset to " << m_offset << "s."; + } + + if (time_now - m_bulletin_download_time > hours(24 * 31)) { + // Refresh if it's older than one month. Leap seconds are + // announced several months in advance + etiLog.level(debug) << "Trying to refresh TAI bulletin"; + + if (m_offset_future.valid()) { + auto state = m_offset_future.wait_for(seconds(0)); + switch (state) { + case future_status::ready: + try { + m_offset = m_offset_future.get(); + m_offset_valid = true; + m_bulletin_download_time = time_now; + + etiLog.level(info) << + "Updated TAI-UTC offset to " << m_offset << "s."; + } + catch (const download_failed&) { + etiLog.level(warn) << + "TAI-UTC download failed, will retry in " << + download_retry_interval_hours << " hour(s)"; + + m_bulletin_download_time += hours(download_retry_interval_hours); + } +#ifdef TEST + wait_longer = false; +#endif + break; + + case future_status::deferred: + case future_status::timeout: + // Not ready yet +#ifdef TEST + etiLog.level(debug) << " async not ready yet"; +#endif + break; + } + } + else { +#ifdef TEST + etiLog.level(debug) << " Launch async"; +#endif + m_offset_future = async(launch::async, &ClockTAI::get_valid_offset, this); + } + } + + return m_offset; +} + +#if SUPPORT_SETTING_CLOCK_TAI +int ClockTAI::update_local_tai_clock(int offset) +{ + struct timex timex_request; + timex_request.modes = ADJ_TAI; + timex_request.constant = offset; + + int err = adjtimex(&timex_request); + if (err == -1) { + perror("adjtimex"); + } + + printf("adjtimex: %d, tai %d\n", err, timex_request.tai); + + return err; +} +#endif + +void ClockTAI::update_cache(const char* cache_filename) +{ + ofstream f(cache_filename); + if (not f.good()) { + throw runtime_error("TAI-UTC bulletin open cache for writing"); + } + + f << m_bulletin; + f.close(); +} + + +void ClockTAI::set_parameter(const string& parameter, const string& value) +{ + if (parameter == "expiry") { + throw ParameterError("Parameter '" + parameter + + "' is read-only in controllable " + get_rc_name()); + } + else { + throw ParameterError("Parameter '" + parameter + + "' is not exported by controllable " + get_rc_name()); + } +} + +const string ClockTAI::get_parameter(const string& parameter) const +{ + if (parameter == "expiry") { + std::unique_lock<std::mutex> lock(m_data_mutex); + const int64_t expiry = parse_bulletin(m_bulletin).expiry; + if (expiry > 0) { + return to_string(expiry); + } + else { + return "Bulletin expired or invalid!"; + } + } + else { + throw ParameterError("Parameter '" + parameter + + "' is not exported by controllable " + get_rc_name()); + } +} + +#if 0 +// Example testing code +void debug_tai_clk() +{ + struct timespec rt_clk; + + int err = clock_gettime(CLOCK_REALTIME, &rt_clk); + if (err) { + perror("REALTIME clock_gettime failed"); + } + + struct timespec tai_clk; + + err = clock_gettime(CLOCK_TAI, &tai_clk); + if (err) { + perror("TAI clock_gettime failed"); + } + + printf("RT - TAI = %ld\n", rt_clk.tv_sec - tai_clk.tv_sec); + + + struct timex timex_request; + timex_request.modes = 0; // Do not set anything + + err = adjtimex(&timex_request); + if (err == -1) { + perror("adjtimex"); + } + + printf("adjtimex: %d, tai %d\n", err, timex_request.tai); +} +#endif + +#if TEST +int main(int argc, char **argv) +{ + using namespace std; + + ClockTAI tai({}); + + while (wait_longer) { + try { + etiLog.level(info) << + "Offset is " << tai.get_offset(); + } + catch (const exception &e) { + etiLog.level(error) << + "Exception " << e.what(); + } + + this_thread::sleep_for(chrono::seconds(2)); + } + + return 0; +} +#endif + |