StatsD: Add user input validation to the application

Added code to accept user input and validate it before
allowing it to be sent to the StatsD server.

ASTERISK-25419
Reported By: Ashley Sanders

Change-Id: I55c7ce44326a68ad6c5c1514b9575ac50f25bbc3

apps/app_statsd.c

@@ -26,11 +26,16 @@
 
 ASTERISK_REGISTER_FILE()
 
+#include <math.h>
+
 #include "asterisk/module.h"
 #include "asterisk/logger.h"
+#include "asterisk/app.h"
+#include "asterisk/pbx.h"
+#include "asterisk/strings.h"
 
 /*** DOCUMENTATION
-	<application name="Statsd" language="en_US">
+	<application name="StatsD" language="en_US">
 		<synopsis>
 			Allow statistics to be passed to the StatsD server from the dialplan.
 		</synopsis>
@@ -46,20 +51,180 @@ ASTERISK_REGISTER_FILE()
 			</parameter>
 		</syntax>
 		<description>
-			<para>This dialplan application sends statistics to the StatsD server
-			specified inside of <literal>statsd.conf</literal>.</para>
+			<para>This dialplan application sends statistics to the StatsD
+			server specified inside of <literal>statsd.conf</literal>.</para>
 		</description>
 	</application>
  ***/
 
-static const char app[] = "Statsd";
+static const char app[] = "StatsD";
 
-static int statsd_exec(struct ast_channel *chan, const char *data)
+/*!
+ * \brief Check to ensure the value is within the allowed range.
+ *
+ * \param value The value of the statistic to be sent to StatsD.
+ * \param metric The metric type to be sent to StatsD.
+ *
+ * This function checks to see if the value given to the StatsD daialplan
+ * application is within the allowed range as specified by StatsD. A counter
+ * is the only metric type allowed to be initialized as a negative number.
+ *
+ * \retval zero on success.
+ * \retval 1 on error.
+ */
+static int value_in_range(const char *value, const char *metric)
 {
-	ast_log(LOG_NOTICE, "StatsD application callback is working!\n");
+	double numerical_value = strtod(value, NULL);
+
+	if (!strcmp(metric, "counter")) {
+		if (numerical_value < pow(-2, 63) || numerical_value > pow(2, 63)) {
+			ast_log(AST_LOG_WARNING, "Value %lf out of range!\n", numerical_value);
+			return 1;
+		}
+	} else {
+		if (numerical_value < 0 || numerical_value > pow(2, 64)) {
+			ast_log(AST_LOG_WARNING, "Value %lf out of range!\n", numerical_value);
+			return 1;
+		}
+	}
+
 	return 0;
 }
 
+/*!
+ * \brief Check to ensure the metric type is a valid metric type.
+ *
+ * \param metric The metric type to be sent to StatsD.
+ *
+ * This function checks to see if the metric type given to the StatsD dialplan
+ * is a valid metric type. Metric types are determined by StatsD.
+ *
+ * \retval zero on success.
+ * \retval 1 on error.
+ */
+static int validate_metric(const char *metric)
+{
+	const char *valid_metrics[] = {"gauge","set","timer","counter"};
+	int i;
+
+	if (ast_strlen_zero(metric)) {
+		ast_log(AST_LOG_ERROR, "Missing metric type argument.\n");
+		return 1;
+	}
+
+	for (i = 0; i < ARRAY_LEN(valid_metrics); i++) {
+		if (!strcmp(valid_metrics[i], metric)) {
+			return 0;
+		}
+	}
+
+	ast_log(AST_LOG_ERROR, "Invalid metric type %s.\n", metric);
+
+	return 1;
+}
+
+/*!
+ * \brief Check to ensure the statistic name is valid.
+ *
+ * \param name The variable name to be sent to StatsD.
+ *
+ * This function checks to see if the statistic name given to the StatsD
+ * dialplan application is valid by ensuring that the name does not have any
+ * invalid characters.
+ *
+ * \retval zero on success.
+ * \retval 1 on error.
+ */
+static int validate_name(const char *name)
+{
+	if (ast_strlen_zero(name) || (strstr(name, "|") != NULL)) {
+		ast_log(AST_LOG_ERROR, "Statistic name %s is missing or contains a pipe (|)"
+			" character.\n", name);
+		return 1;
+	}
+
+	return 0;
+}
+
+/*!
+ * \brief Check to ensure the value is valid.
+ *
+ * \param value The value of the statistic to be sent to StatsD.
+ * \param metric The metric type to be sent to StatsD.
+ *
+ * This function checks to see if the value given to the StatsD daialplan
+ * application is valid by testing if it is numeric. A plus or minus is only
+ * allowed at the beginning of the value if it is a counter or a gauge.
+ *
+ * \retval zero on success.
+ * \retval 1 on error.
+ */
+static int validate_value(const char *value, const char *metric)
+{
+	const char *actual_value;
+
+	if (ast_strlen_zero(value)) {
+		ast_log(AST_LOG_ERROR, "Missing value argument.\n");
+		return 1;
+	}
+
+	if (!strcmp(metric, "gauge") || !strcmp(metric, "counter")) {
+		if ((value[0] == '+') || (value[0] == '-')) {
+			actual_value = &value[1];
+			if (ast_strlen_zero(actual_value)) {
+				ast_log(AST_LOG_ERROR, "Value argument %s only contains a sign"
+					" operator.\n", value);
+				return 1;
+			}
+		} else {
+			actual_value = &value[0];
+		}
+	} else {
+		actual_value = &value[0];
+	}
+
+	if (!isdigit(*actual_value)) {
+		ast_log(AST_LOG_ERROR, "Value of %s is not a valid number!\n", actual_value);
+		return 1;
+	}
+
+	if (value_in_range(actual_value, metric)) {
+		return 1;
+	}
+
+	return 0;
+}
+
+static int statsd_exec(struct ast_channel *chan, const char *data)
+{
+	char *stats;
+
+	AST_DECLARE_APP_ARGS(args,
+			AST_APP_ARG(metric_type);
+			AST_APP_ARG(statistic_name);
+			AST_APP_ARG(value);
+	);
+
+	if (!data) {
+		ast_log(AST_LOG_ERROR, "No parameters were provided. Correct format is "
+			"StatsD(metric_type,statistic_name,value). All parameters are required.\n");
+		return 1;
+	}
+
+	stats = ast_strdupa(data);
+	AST_STANDARD_APP_ARGS(args, stats);
+
+	/* If any of the validations fail, emit a warning message. */
+	if (validate_metric(args.metric_type) || validate_name(args.statistic_name)
+		|| validate_value(args.value, args.metric_type)) {
+		ast_log(AST_LOG_WARNING, "Invalid parameters provided. Correct format is "
+			"StatsD(metric_type,statistic_name,value). All parameters are required.\n");
+
+		return 1;
+	}
+
+	return 0;
+}
 
 static int unload_module(void)
 {
@@ -71,4 +236,4 @@ static int load_module(void)
 	return ast_register_application_xml(app, statsd_exec);
 }
 
-AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Statsd Dialplan Application");
+AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "StatsD Dialplan Application");