+/* Bits for csp->content_type bitmask: */
+#define CT_TEXT 0x0001U /**< Suitable for pcrs filtering. */
+#define CT_GIF 0x0002U /**< Suitable for GIF filtering. */
+#define CT_TABOO 0x0004U /**< DO NOT filter, irrespective of other flags. */
+
+/* Although these are not, strictly speaking, content types
+ * (they are content encodings), it is simple to handle them
+ * as such.
+ */
+#define CT_GZIP 0x0010U /**< gzip-compressed data. */
+#define CT_DEFLATE 0x0020U /**< zlib-compressed data. */
+
+/**
+ * Flag to signal that the server declared the content type,
+ * so we can differentiate between unknown and undeclared
+ * content types.
+ */
+#define CT_DECLARED 0x0040U
+
+/**
+ * The mask which includes all actions.
+ */
+#define ACTION_MASK_ALL (~0UL)
+
+/**
+ * The most compatible set of actions - i.e. none.
+ */
+#define ACTION_MOST_COMPATIBLE 0x00000000UL
+
+/** Action bitmap: Block the request. */
+#define ACTION_BLOCK 0x00000001UL
+/** Action bitmap: Deanimate if it's a GIF. */
+#define ACTION_DEANIMATE 0x00000002UL
+/** Action bitmap: Downgrade HTTP/1.1 to 1.0. */
+#define ACTION_DOWNGRADE 0x00000004UL
+/** Action bitmap: Fast redirects. */
+#define ACTION_FAST_REDIRECTS 0x00000008UL
+/** Action bitmap: Remove or add "X-Forwarded-For" header. */
+#define ACTION_CHANGE_X_FORWARDED_FOR 0x00000010UL
+/** Action bitmap: Hide "From" header. */
+#define ACTION_HIDE_FROM 0x00000020UL
+/** Action bitmap: Hide "Referer" header. (sic - follow HTTP, not English). */
+#define ACTION_HIDE_REFERER 0x00000040UL
+/** Action bitmap: Hide "User-Agent" and similar headers. */
+#define ACTION_HIDE_USER_AGENT 0x00000080UL
+/** Action bitmap: This is an image. */
+#define ACTION_IMAGE 0x00000100UL
+/** Action bitmap: Sets the image blocker. */
+#define ACTION_IMAGE_BLOCKER 0x00000200UL
+/** Action bitmap: Prevent compression. */
+#define ACTION_NO_COMPRESSION 0x00000400UL
+/** Action bitmap: Change cookies to session only cookies. */
+#define ACTION_NO_COOKIE_KEEP 0x00000800UL
+/** Action bitmap: Block rending cookies. */
+#define ACTION_NO_COOKIE_READ 0x00001000UL
+/** Action bitmap: Block setting cookies. */
+#define ACTION_NO_COOKIE_SET 0x00002000UL
+/** Action bitmap: Override the forward settings in the config file */
+#define ACTION_FORWARD_OVERRIDE 0x00004000UL
+/** Action bitmap: Block as empty document */
+#define ACTION_HANDLE_AS_EMPTY_DOCUMENT 0x00008000UL
+/** Action bitmap: Limit CONNECT requests to safe ports. */
+#define ACTION_LIMIT_CONNECT 0x00010000UL
+/** Action bitmap: Redirect request. */
+#define ACTION_REDIRECT 0x00020000UL
+/** Action bitmap: Crunch or modify "if-modified-since" header. */
+#define ACTION_HIDE_IF_MODIFIED_SINCE 0x00040000UL
+/** Action bitmap: Overwrite Content-Type header. */
+#define ACTION_CONTENT_TYPE_OVERWRITE 0x00080000UL
+/** Action bitmap: Crunch specified server header. */
+#define ACTION_CRUNCH_SERVER_HEADER 0x00100000UL
+/** Action bitmap: Crunch specified client header */
+#define ACTION_CRUNCH_CLIENT_HEADER 0x00200000UL
+/** Action bitmap: Enable text mode by force */
+#define ACTION_FORCE_TEXT_MODE 0x00400000UL
+/** Action bitmap: Enable text mode by force */
+#define ACTION_CRUNCH_IF_NONE_MATCH 0x00800000UL
+/** Action bitmap: Enable content-dispostion crunching */
+#define ACTION_HIDE_CONTENT_DISPOSITION 0x01000000UL
+/** Action bitmap: Replace or block Last-Modified header */
+#define ACTION_OVERWRITE_LAST_MODIFIED 0x02000000UL
+/** Action bitmap: Replace or block Accept-Language header */
+#define ACTION_HIDE_ACCEPT_LANGUAGE 0x04000000UL
+
+
+/** Action string index: How to deanimate GIFs */
+#define ACTION_STRING_DEANIMATE 0
+/** Action string index: Replacement for "From:" header */
+#define ACTION_STRING_FROM 1
+/** Action string index: How to block images */
+#define ACTION_STRING_IMAGE_BLOCKER 2
+/** Action string index: Replacement for "Referer:" header */
+#define ACTION_STRING_REFERER 3
+/** Action string index: Replacement for "User-Agent:" header */
+#define ACTION_STRING_USER_AGENT 4
+/** Action string index: Legal CONNECT ports. */
+#define ACTION_STRING_LIMIT_CONNECT 5
+/** Action string index: Server headers containing this pattern are crunched*/
+#define ACTION_STRING_SERVER_HEADER 6
+/** Action string index: Client headers containing this pattern are crunched*/
+#define ACTION_STRING_CLIENT_HEADER 7
+/** Action string index: Replacement for the "Accept-Language:" header*/
+#define ACTION_STRING_LANGUAGE 8
+/** Action string index: Replacement for the "Content-Type:" header*/
+#define ACTION_STRING_CONTENT_TYPE 9
+/** Action string index: Replacement for the "content-dispostion:" header*/
+#define ACTION_STRING_CONTENT_DISPOSITION 10
+/** Action string index: Replacement for the "If-Modified-Since:" header*/
+#define ACTION_STRING_IF_MODIFIED_SINCE 11
+/** Action string index: Replacement for the "Last-Modified:" header. */
+#define ACTION_STRING_LAST_MODIFIED 12
+/** Action string index: Redirect URL */
+#define ACTION_STRING_REDIRECT 13
+/** Action string index: Decode before redirect? */
+#define ACTION_STRING_FAST_REDIRECTS 14
+/** Action string index: Overriding forward rule. */
+#define ACTION_STRING_FORWARD_OVERRIDE 15
+/** Action string index: Reason for the block. */
+#define ACTION_STRING_BLOCK 16
+/** Action string index: what to do with the "X-Forwarded-For" header. */
+#define ACTION_STRING_CHANGE_X_FORWARDED_FOR 17
+/** Number of string actions. */
+#define ACTION_STRING_COUNT 18
+
+
+/* To make the ugly hack in sed easier to understand */
+#define CHECK_EVERY_HEADER_REMAINING 0
+
+
+/** Index into current_action_spec::multi[] for headers to add. */
+#define ACTION_MULTI_ADD_HEADER 0
+/** Index into current_action_spec::multi[] for content filters to apply. */
+#define ACTION_MULTI_FILTER 1
+/** Index into current_action_spec::multi[] for server-header filters to apply. */
+#define ACTION_MULTI_SERVER_HEADER_FILTER 2
+/** Index into current_action_spec::multi[] for client-header filters to apply. */
+#define ACTION_MULTI_CLIENT_HEADER_FILTER 3
+/** Index into current_action_spec::multi[] for client-header tags to apply. */
+#define ACTION_MULTI_CLIENT_HEADER_TAGGER 4
+/** Index into current_action_spec::multi[] for server-header tags to apply. */
+#define ACTION_MULTI_SERVER_HEADER_TAGGER 5
+/** Number of multi-string actions. */
+#define ACTION_MULTI_COUNT 6
+
+
+/**
+ * This structure contains a list of actions to apply to a URL.
+ * It only contains positive instructions - no "-" options.
+ * It is not used to store the actions list itself, only for
+ * url_actions() to return the current values.
+ */
+struct current_action_spec
+{
+ /** Actions to apply. A bit set to "1" means perform the action. */
+ unsigned long flags;
+
+ /**
+ * Paramaters for those actions that require them.
+ * Each entry is valid if & only if the corresponding entry in "flags" is
+ * set.
+ */
+ char * string[ACTION_STRING_COUNT];
+
+ /** Lists of strings for multi-string actions. */
+ struct list multi[ACTION_MULTI_COUNT][1];
+};
+
+
+/**
+ * This structure contains a set of changes to actions.
+ * It can contain both positive and negative instructions.
+ * It is used to store an entry in the actions list.
+ */
+struct action_spec
+{
+ unsigned long mask; /**< Actions to keep. A bit set to "0" means remove action. */
+ unsigned long add; /**< Actions to add. A bit set to "1" means add action. */
+
+ /**
+ * Paramaters for those actions that require them.
+ * Each entry is valid if & only if the corresponding entry in "flags" is
+ * set.
+ */
+ char * string[ACTION_STRING_COUNT];
+
+ /** Lists of strings to remove, for multi-string actions. */
+ struct list multi_remove[ACTION_MULTI_COUNT][1];
+
+ /** If nonzero, remove *all* strings from the multi-string action. */
+ int multi_remove_all[ACTION_MULTI_COUNT];
+
+ /** Lists of strings to add, for multi-string actions. */
+ struct list multi_add[ACTION_MULTI_COUNT][1];
+};
+
+
+/**
+ * This structure is used to store action files.
+ *
+ * It contains an URL or tag pattern, and the changes to
+ * the actions. It's a linked list and should only be
+ * free'd through unload_actions_file() unless there's
+ * only a single entry.
+ */
+struct url_actions
+{
+ struct url_spec url[1]; /**< The URL or tag pattern. */
+
+ struct action_spec *action; /**< Action settings that might be shared with
+ the list entry before or after the current
+ one and can't be free'd willy nilly. */