SWW_APPS: an app's Core Rule Set fixes apply only to the hostnames that serve it (closes #220)

Each app's fixes are one .conf file, whose first rule skips the rest
unless Inspect sets tx.app_<name>, and one entry in apps. SWW_APPS names
each hostname's apps. A hostname gets only its apps' fixes; while
SWW_APPS is unset, every hostname gets every app's fixes.

A hostname in SWW_APPS that is not a DNS name, such as *.example.com,
stops the start. Unset, SWW_APPS is logged at start as null; set
empty, as "".

Model: opus-5-5

internal/coreruleset/drupal.conf

@@ -1,4 +1,4 @@
-# The tenth change: on Drupal's paths, some fields skip the rules that refused
+# Drupal's fixes: on Drupal's paths, some fields skip the rules that refused
 # ordinary Drupal requests there. They are the fields where Drupal sends a
 # search, a name, a file name or an address. Each exclusion runs with the
 # request, before the rules it switches off, so this file is loaded before the
@@ -25,6 +25,13 @@
 #   932230: ls -la
 #   932235: python3
 
+# Unless SWW_APPS lists drupal for the request's hostname, every rule below is
+# skipped. Inspect sets tx.app_drupal when it does.
+# The skip reaches only phase 1, so a rule of a later phase must check
+# tx.app_drupal itself.
+SecRule &TX:app_drupal "@eq 0" \
+    "id:900790,phase:1,pass,nolog,skipAfter:END_DRUPAL"
+
 # Every admin page's filters and autocompletes, and the page to return to:
 #   title: /admin/content?title=python3
 #   name: /admin/content/media?name=python3
@@ -237,3 +244,5 @@ SecRule REQUEST_FILENAME "@rx ^(?:/[a-z]{2,3}(?:-[a-z]+)?)?/user/password$" \
     SecRule &ARGS_GET:json.mail "@eq 0" \
         "ctl:ruleRemoveTargetById=932120;ARGS:json.mail,\
         ctl:ruleRemoveTargetById=932260;ARGS:json.mail"
+
+SecMarker END_DRUPAL