mysql: Be more explicit when parsing database URI but don't log password

This avoids logging the password that's potentially contained in the URI
and also gives clearer instructions about what's missing.

Also clears the memory that stores the URI/password.

src/libstrongswan/plugins/mysql/mysql_database.c

@@ -754,6 +754,7 @@ METHOD(database_t, destroy, void,
 	this->mutex->destroy(this->mutex);
 	free(this->host);
 	free(this->username);
+	memwipe(this->password, this->password ? strlen(this->password) : 0);
 	free(this->password);
 	free(this->database);
 	free(this);
@@ -761,12 +762,13 @@ METHOD(database_t, destroy, void,
 
 static bool parse_uri(private_mysql_database_t *this, char *uri)
 {
+	const int scheme_len = strlen("mysql://");
 	char *username, *password, *host, *port = "0", *database, *pos;
 
 	/**
 	 * parse mysql://username:pass@host:port/database uri
 	 */
-	username = strdup(uri + 8);
+	username = strdup(uri + scheme_len);
 	pos = strchr(username, ':');
 	if (pos)
 	{
@@ -798,13 +800,26 @@ static bool parse_uri(private_mysql_database_t *this, char *uri)
 				this->password = strdup(password);
 				this->database = strdup(database);
 				this->port = atoi(port);
+				memwipe(username, strlen(uri) - scheme_len);
 				free(username);
 				return TRUE;
 			}
+			DBG1(DBG_LIB, "parsing MySQL database uri 'mysql://%s:***@%s' "
+				 "failed: missing '/database' part", username, host);
+		}
+		else
+		{
+			DBG1(DBG_LIB, "parsing MySQL database uri 'mysql://%s:***' "
+				 "failed: missing '@host[:port]/database' part", username);
 		}
 	}
+	else
+	{
+		DBG1(DBG_LIB, "parsing MySQL database uri of the form "
+			 "'mysql://username:[password]@host[:port]/database' failed");
+	}
+	memwipe(username, strlen(uri) - scheme_len);
 	free(username);
-	DBG1(DBG_LIB, "parsing MySQL database uri '%s' failed", uri);
 	return FALSE;
 }