ui,popups: allow to select snap paths automatically

In the same way that we automatically select AppImages paths, now we'll
also select snap paths.

Usually these paths start with /snap, followed by the name of the app, a
revision number and the path to the executable:

/snap/firefox/12345/usr/lib/firefox/firefox

Internally the rule will create this regular expression, to match the
the snap regardless of the revision:
^\/snap\/firefox\/[0-9]+\/usr\/lib\/firefox\/firefox$

Closes: #1439.

Author: gustavo-iniguez-goya

ui/opensnitch/dialogs/prompt/__init__.py

@@ -475,6 +475,8 @@ def _render_connection(self, con):
         self._add_fixed_options_to_combo(self.whatCombo, con, uid)
         if con.process_path.startswith(_constants.APPIMAGE_PREFIX):
             self._add_appimage_pattern_to_combo(self.whatCombo, con)
+        elif con.process_path.startswith(_constants.SNAP_PREFIX):
+            self._add_snap_pattern_to_combo(self.whatCombo, con)
         self._add_dst_networks_to_combo(self.whatCombo, con.dst_ip)
 
         if con.dst_host != "" and con.dst_host != con.dst_ip:
@@ -556,6 +558,22 @@ def _add_appimage_pattern_to_combo(self, combo, con):
             _constants.FIELD_APPIMAGE
         )
 
+    def _add_snap_pattern_to_combo(self, combo, con):
+        """snap absolute path usually starts with /snap/, followed by a revision
+        number which changes after every installation or update.
+        """
+        snap_path = con.process_path
+        snap_parts = snap_path.split('/')
+        app = snap_parts[2]
+        app_path = "/".join(snap_parts[4:])
+        from_field = "from {0}/{1}/*/{2}".format(_constants.SNAP_PREFIX, app, app_path)
+
+        combo.addItem(
+            QC.translate("popups", from_field),
+            _constants.FIELD_SNAP
+        )
+
+
     def _add_dst_networks_to_combo(self, combo, dst_ip):
         alias = NetworkAliases.get_alias(dst_ip)
         if alias:

ui/opensnitch/dialogs/prompt/_constants.py

@@ -18,6 +18,7 @@
 FIELD_DST_NETWORK   = "dst_network"
 FIELD_DST_HOST      = "simple_host"
 FIELD_APPIMAGE      = "appimage_path"
+FIELD_SNAP          = "snap_path"
 
 DURATION_30s    = "30s"
 DURATION_5m     = "5m"
@@ -28,6 +29,7 @@
 # don't translate
 
 APPIMAGE_PREFIX = "/tmp/.mount_"
+SNAP_PREFIX = "/snap"
 
 # label displayed in the pop-up combo
 DURATION_session = QC.translate("popups", "until reboot")

ui/opensnitch/dialogs/prompt/_utils.py

@@ -157,6 +157,11 @@ def set_default_target(combo, con, cfg, app_name, app_args):
         if idx != -1:
             combo.setCurrentIndex(idx)
             return
+    elif con.process_path.startswith(_constants.SNAP_PREFIX):
+        idx = combo.findData(_constants.FIELD_SNAP)
+        if idx != -1:
+            combo.setCurrentIndex(idx)
+            return
 
     if int(con.process_id) > 0 and app_name != "" and app_args != "":
         combo.setCurrentIndex(int(cfg.getSettings(cfg.DEFAULT_TARGET_KEY)))
@@ -213,3 +218,12 @@ def get_combo_operator(data, comboText, con):
         appimage_path = os.path.dirname(con.process_path).replace('.', r'\.')
         appimage_path = appimage_path[0:len(_constants.APPIMAGE_PREFIX)+7]
         return Config.RULE_TYPE_REGEXP, Config.OPERAND_PROCESS_PATH, r'^{0}[0-9A-Za-z]{{6,7}}\/.*{1}$'.format(appimage_path, appimage_bin)
+
+    elif data == _constants.FIELD_SNAP:
+        snap_path = con.process_path
+        snap_parts = snap_path.split('/')
+        snap_prefix = snap_parts[1]
+        app = snap_parts[2]
+        app_path = r'\/'.join(snap_parts[4:])
+        regexp = r'^\/{0}\/{1}\/[0-9]+\/{2}$'.format(snap_prefix, app, app_path)
+        return Config.RULE_TYPE_REGEXP, Config.OPERAND_PROCESS_PATH, regexp