Melchior FRANZ:

The following patches to SimGear & FlightGear ...

- create an FGMetar abstraction layer, whose purpose is:
  * provide defaults for unset values
  * interpolate/randomize data (GREATER_THAN)
  * derive additional values (time, age, snow cover)
  * consider minimum identifier (CAVOK, mil. color codes)
- add rain/hail/snow/snowcover support on the METAR side
- add max age of METAR data handling (currently set to
- add support for an external METAR cache proxy server
- add CAVOK handling
- set missing year/month in regular METAR messages
- fix a small bug in metar.cxx (wrong return value)

simgear/environment/metar.cxx

@@ -26,6 +26,7 @@
  */
 
 #include <string>
+#include <time.h>
 
 #include <simgear/io/sg_socket.hxx>
 #include <simgear/debug/logstream.hxx>
@@ -59,8 +60,10 @@
  * double d = n.getDewpoint_C();
  * @endcode
  */
-SGMetar::SGMetar(const string& m, const string& proxy, const string& port, const string& auth) :
+SGMetar::SGMetar(const string& m, const string& proxy, const string& port,
+		const string& auth, const time_t time) :
 	_grpcount(0),
+	_x_proxy(false),
 	_year(-1),
 	_month(-1),
 	_day(-1),
@@ -74,13 +77,17 @@ SGMetar::SGMetar(const string& m, const string& proxy, const string& port, const
 	_wind_range_to(-1),
 	_temp(NaN),
 	_dewp(NaN),
-	_pressure(NaN)
+	_pressure(NaN),
+	_rain(false),
+	_hail(false),
+	_snow(false),
+	_cavok(false)
 {
 	if (m.length() == 4 && isalnum(m[0]) && isalnum(m[1]) && isalnum(m[2]) && isalnum(m[3])) {
 		for (int i = 0; i < 4; i++)
 			_icao[i] = toupper(m[i]);
 		_icao[4] = '\0';
-		_data = loadData(_icao, proxy, port, auth);
+		_data = loadData(_icao, proxy, port, auth, time);
 	} else {
 		_data = new char[m.length() + 2];	// make room for " \0"
 		strcpy(_data, m.c_str());
@@ -92,7 +99,8 @@ SGMetar::SGMetar(const string& m, const string& proxy, const string& port, const
 	_icao[0] = '\0';
 
 	// NOAA preample
-	scanPreambleDate();
+	if (!scanPreambleDate())
+		useCurrentDate();
 	scanPreambleTime();
 
 	// METAR header
@@ -127,6 +135,7 @@ SGMetar::SGMetar(const string& m, const string& proxy, const string& port, const
 		delete[] _data;
 		throw sg_io_exception("metar data incomplete (" + _url + ')');
 	}
+
 	_url = "";
 }
 
@@ -143,6 +152,16 @@ SGMetar::~SGMetar()
 }
 
 
+void SGMetar::useCurrentDate()
+{
+	struct tm now;
+	time_t now_sec = time(0);
+	gmtime_r(&now_sec, &now);
+	_year = now.tm_year + 1900;
+	_month = now.tm_mon + 1;
+}
+
+
 /**
   * If called with "KSFO" loads data from
   * @code
@@ -157,10 +176,15 @@ SGMetar::~SGMetar()
   * @return pointer to Metar data string, allocated by new char[].
   * @see rfc2068.txt for proxy spec ("Proxy-Authorization")
   */
-char *SGMetar::loadData(const char *id, const string& proxy, const string& port, const string& auth)
+char *SGMetar::loadData(const char *id, const string& proxy, const string& port,
+		const string& auth, time_t time)
 {
+	const int buflen = 512;
+	char buf[2 * buflen];
+
 	string host = proxy.empty() ? "weather.noaa.gov" : proxy;
 	string path = "/pub/data/observations/metar/stations/";
+
 	path += string(id) + ".TXT";
 	_url = "http://weather.noaa.gov" + path;
 
@@ -174,24 +198,25 @@ char *SGMetar::loadData(const char *id, const string& proxy, const string& port,
 	string get = "GET ";
 	if (!proxy.empty())
 		get += "http://weather.noaa.gov";
-	get += path + " HTTP/1.0\r\n";
+
+	sprintf(buf, "%ld", time);
+	get += path + " HTTP/1.0\015\012X-Time: " + buf + "\015\012";
+
+	if (!auth.empty())
+		get += "Proxy-Authorization: " + auth + "\015\012";
+
+	get += "\015\012";
 	sock->writestring(get.c_str());
 
-	if (!auth.empty()) {
-		get = "Proxy-Authorization: " + auth + "\r\n";
-		sock->writestring(get.c_str());
-	}
-
-	sock->writestring("\r\n");
-
 	int i;
-	const int buflen = 512;
-	char buf[2 * buflen];
 
 	// skip HTTP header
-	while ((i = sock->readline(buf, buflen)))
+	while ((i = sock->readline(buf, buflen))) {
 		if (i <= 2 && isspace(buf[0]) && (!buf[1] || isspace(buf[1])))
 			break;
+		if (!strncmp(buf, "X-MetarProxy: ", 9))
+			_x_proxy = true;
+	}
 	if (i) {
 		i = sock->readline(buf, buflen);
 		if (i)
@@ -392,7 +417,7 @@ bool SGMetar::scanWind()
 	if (gust != NaN)
 		_gust_speed = gust * factor;
 	_grpcount++;
-	return false;
+	return true;
 }
 
 
@@ -643,14 +668,15 @@ bool SGMetar::scanWeather()
 	}
 
 	string pre, post;
+	int intensity = 0;
 	if (*m == '-')
-		m++, pre = "light ";
+		m++, pre = "light ", intensity = 1;
 	else if (*m == '+')
-		m++, pre = "heavy ";
+		m++, pre = "heavy ", intensity = 3;
 	else if (!strncmp(m, "VC", 2))
 		m += 2, post = "in the vicinity ";
 	else
-		pre = "moderate ";
+		pre = "moderate ", intensity = 2;
 
 	int i;
 	for (i = 0; i < 3; i++) {
@@ -662,6 +688,12 @@ bool SGMetar::scanWeather()
 		if (!(a = scanToken(&m, phenomenon)))
 			break;
 		weather += string(a->text) + " ";
+		if (!strcmp(a->id, "RA"))
+			_rain = intensity;
+		else if (!strcmp(a->id, "HA"))
+			_hail = intensity;
+		else if (!strcmp(a->id, "SN"))
+			_snow = intensity;
 	}
 	if (!weather.length())
 		return false;
@@ -714,8 +746,13 @@ bool SGMetar::scanSkyCondition()
 		m += i;
 		if (!scanBoundary(&m))
 			return false;
-		cl._coverage = 0;
+
-		_clouds.push_back(cl);
+		if (i == 3) {
+			cl._coverage = 0;
+			_clouds.push_back(cl);
+		} else {
+			_cavok = true;
+		}
 		_m = m;
 		return true;
 	}
@@ -907,10 +944,11 @@ bool SGMetar::scanRunwayReport()
 
 	if (!strncmp(m, "CLRD", 4)) {
 		m += 4;							// runway cleared
-		r._deposit = "cleared";
+		r._deposit_string = "cleared";
 	} else {
 		if (scanNumber(&m, &i, 1)) {
-			r._deposit = runway_deposit[i];
+			r._deposit = i;
+			r._deposit_string = runway_deposit[i];
 		} else if (*m == '/')
 			m++;
 		else
@@ -1137,4 +1175,24 @@ const struct Token *SGMetar::scanToken(char **str, const struct Token *list)
 	return longest;
 }
 
+
+void SGMetarCloud::set(double alt, int cov)
+{
+	_altitude = alt;
+	if (cov != -1)
+		_coverage = cov;
+}
+
+
+void SGMetarVisibility::set(double dist, int dir, int mod, int tend)
+{
+	_distance = dist;
+	if (dir != -1)
+		_direction = dir;
+	if (mod != -1)
+		_modifier = mod;
+	if (tend != 1)
+		_tendency = tend;
+}
+
 #undef NaN

simgear/environment/metar.hxx

@@ -67,6 +67,8 @@ public:
 		DECREASING
 	};
 
+	void set(double dist, int dir = -1, int mod = -1, int tend = -1);
+
 	inline double	getVisibility_m()	const { return _distance; }
 	inline double	getVisibility_ft()	const { return _distance == NaN ? NaN : _distance * SG_METER_TO_FEET; }
 	inline double	getVisibility_sm()	const { return _distance == NaN ? NaN : _distance * SG_METER_TO_SM; }
@@ -87,7 +89,8 @@ class SGMetarRunway {
 	friend class SGMetar;
 public:
 	SGMetarRunway() :
-		_deposit(0),
+		_deposit(-1),
+		_deposit_string(0),
 		_extent(-1),
 		_extent_string(0),
 		_depth(NaN),
@@ -96,7 +99,8 @@ public:
 		_comment(0),
 		_wind_shear(false) {}
 
-	inline const char		*getDeposit()		const { return _deposit; }
+	inline int			getDeposit()		const { return _deposit; }
+	inline const char		*getDepositString()	const { return _deposit_string; }
 	inline double			getExtent()		const { return _extent; }
 	inline const char		*getExtentString()	const { return _extent_string; }
 	inline double			getDepth()		const { return _depth; }
@@ -110,7 +114,8 @@ public:
 protected:
 	SGMetarVisibility _min_visibility;
 	SGMetarVisibility _max_visibility;
-	const char	*_deposit;
+	int		_deposit;
+	const char	*_deposit_string;
 	int		_extent;
 	const char	*_extent_string;
 	double		_depth;
@@ -131,6 +136,8 @@ public:
 		_type(0),
 		_type_long(0) {}
 
+	void set(double alt, int cov = -1);
+
 	inline int	getCoverage()		const { return _coverage; }
 	inline double	getAltitude_m()		const { return _altitude; }
 	inline double	getAltitude_ft()	const { return _altitude == NaN ? NaN : _altitude * SG_METER_TO_FEET; }
@@ -147,7 +154,8 @@ protected:
 
 class SGMetar {
 public:
-	SGMetar(const string& m, const string& proxy = "", const string& port = "", const string &auth = "");
+	SGMetar(const string& m, const string& proxy = "", const string& port = "",
+			const string &auth = "", const time_t time = 0);
 	~SGMetar();
 
 	enum ReportType {
@@ -159,6 +167,7 @@ public:
 
 	inline const char *getData()		const { return _data; }
 	inline const char *getUnusedData()	const { return _m; }
+	inline const bool getProxy()		const { return _x_proxy; }
 	inline const char *getId()		const { return _icao; }
 	inline int	getYear()		const { return _year; }
 	inline int	getMonth()		const { return _month; }
@@ -193,6 +202,11 @@ public:
 	inline double	getPressure_hPa()	const { return _pressure == NaN ? NaN : _pressure / 100; }
 	inline double	getPressure_inHg()	const { return _pressure == NaN ? NaN : _pressure * SG_PA_TO_INHG; }
 
+	inline int	getRain()		const { return _rain; }
+	inline int	getHail()		const { return _hail; }
+	inline int	getSnow()		const { return _snow; }
+	inline bool	getCAVOK()		const { return _cavok; }
+
 	double		getRelHumidity()	const;
 
 	inline vector<SGMetarCloud>& getClouds()	{ return _clouds; }
@@ -202,6 +216,7 @@ public:
 protected:
 	string	_url;
 	int	_grpcount;
+	bool	_x_proxy;
 	char	*_data;
 	char	*_m;
 	char	_icao[5];
@@ -219,6 +234,10 @@ protected:
 	double	_temp;
 	double	_dewp;
 	double	_pressure;
+	int	_rain;
+	int	_hail;
+	int	_snow;
+	bool	_cavok;
 
 	SGMetarVisibility		_min_visibility;
 	SGMetarVisibility		_max_visibility;
@@ -230,6 +249,7 @@ protected:
 
 	bool	scanPreambleDate();
 	bool	scanPreambleTime();
+	void	useCurrentDate();
 
 	bool	scanType();
 	bool	scanId();
@@ -253,7 +273,8 @@ protected:
 	int	scanNumber(char **str, int *num, int min, int max = 0);
 	bool	scanBoundary(char **str);
 	const struct Token *scanToken(char **str, const struct Token *list);
-	char	*loadData(const char *id, const string& proxy, const string& port, const string &auth);
+	char	*loadData(const char *id, const string& proxy, const string& port,
+			const string &auth, time_t time);
 	void	normalizeData();
 };