Allow for calling find_dhcp_option() with "options" set to NULL, in order

to search through all registered option blocks.

Move some static inlines that are likely to be used frequently into
dhcpopts.c as normal functions, to save space.

src/include/gpxe/dhcp.h

 extern unsigned long dhcp_num_option ( struct dhcp_option *option );
 extern struct dhcp_option *
 find_dhcp_option ( struct dhcp_option_block *options, unsigned int tag );
-extern struct dhcp_option * find_global_dhcp_option ( unsigned int tag );
 extern void register_dhcp_options ( struct dhcp_option_block *options );
 extern void unregister_dhcp_options ( struct dhcp_option_block *options );
 extern void init_dhcp_options ( struct dhcp_option_block *options,
 extern struct dhcp_option *
 set_dhcp_option ( struct dhcp_option_block *options, unsigned int tag,
 		  const void *data, size_t len );
-
-/**
- * Find DHCP numerical option, and return its value
- *
- * @v options		DHCP options block
- * @v tag		DHCP option tag to search for
- * @ret value		Numerical value of the option, or 0 if not found
- *
- * This function exists merely as a notational shorthand for a call to
- * find_dhcp_option() followed by a call to dhcp_num_option().  It is
- * not possible to distinguish between the cases "option not found"
- * and "option has a value of zero" using this function; if this
- * matters to you then issue the two constituent calls directly and
- * check that find_dhcp_option() returns a non-NULL value.
- */
-static inline unsigned long
-find_dhcp_num_option ( struct dhcp_option_block *options, unsigned int tag ) {
-	return dhcp_num_option ( find_dhcp_option ( options, tag ) );
-}
-
-/**
- * Find DHCP numerical option, and return its value
- *
- * @v tag		DHCP option tag to search for
- * @ret value		Numerical value of the option, or 0 if not found
- *
- * This function exists merely as a notational shorthand for a call to
- * find_global_dhcp_option() followed by a call to dhcp_num_option().
- * It is not possible to distinguish between the cases "option not
- * found" and "option has a value of zero" using this function; if
- * this matters to you then issue the two constituent calls directly
- * and check that find_global_dhcp_option() returns a non-NULL value.
- */
-static inline unsigned long
-find_global_dhcp_num_option ( unsigned int tag ) {
-	return dhcp_num_option ( find_global_dhcp_option ( tag ) );
-}
-
-/**
- * Delete DHCP option
- *
- * @v options		DHCP options block
- * @v tag		DHCP option tag
- */
-static inline void delete_dhcp_option ( struct dhcp_option_block *options,
-					unsigned int tag ) {
-	set_dhcp_option ( options, tag, NULL, 0 );
-}
+extern struct dhcp_option * find_global_dhcp_option ( unsigned int tag );
+extern unsigned long find_dhcp_num_option ( struct dhcp_option_block *options,
+					    unsigned int tag );
+extern unsigned long find_global_dhcp_num_option ( unsigned int tag );
+extern void delete_dhcp_option ( struct dhcp_option_block *options,
+				 unsigned int tag );
 
 #endif /* _GPXE_DHCP_H */

src/net/dhcpopts.c

  *
  * @v options		DHCP options block
  * @v tag		DHCP option tag to search for
+ * @ret encapsulator	Encapsulating DHCP option
  * @ret option		DHCP option, or NULL if not found
  *
  * Searches for the DHCP option matching the specified tag within the
- * block of data.  Encapsulated options may be searched for by using
- * DHCP_ENCAP_OPT() to construct the tag value.
+ * DHCP option block.  Encapsulated options may be searched for by
+ * using DHCP_ENCAP_OPT() to construct the tag value.
+ *
+ * If the option is encapsulated, and @c encapsulator is non-NULL, it
+ * will be filled in with a pointer to the encapsulating option.
  *
  * This routine is designed to be paranoid.  It does not assume that
  * the option data is well-formatted, and so must guard against flaws
  * such as options missing a @c DHCP_END terminator, or options whose
  * length would take them beyond the end of the data block.
  */
-struct dhcp_option * find_dhcp_option ( struct dhcp_option_block *options,
-					unsigned int tag ) {
+static struct dhcp_option *
+find_dhcp_option_with_encap ( struct dhcp_option_block *options,
+			      unsigned int tag,
+			      struct dhcp_option **encapsulator ) {
 	unsigned int original_tag __attribute__ (( unused )) = tag;
 	struct dhcp_option *option = options->data;
 	ssize_t remaining = options->len;
 		/* Check for start of matching encapsulation block */
 		if ( DHCP_IS_ENCAP_OPT ( tag ) &&
 		     ( option->tag == DHCP_ENCAPSULATOR ( tag ) ) ) {
+			if ( encapsulator )
+				*encapsulator = option;
 			/* Continue search within encapsulated option block */
 			tag = DHCP_ENCAPSULATED ( tag );
 			remaining = option->len;
 }
 
 /**
- * Find DHCP option within all registered DHCP options blocks
+ * Find DHCP option within DHCP options block
  *
+ * @v options		DHCP options block, or NULL
  * @v tag		DHCP option tag to search for
  * @ret option		DHCP option, or NULL if not found
  *
- * Searches within all registered DHCP option blocks for the specified
- * tag.  Encapsulated options may be searched for by using
- * DHCP_ENCAP_OPT() to construct the tag value.
+ * Searches for the DHCP option matching the specified tag within the
+ * DHCP option block.  Encapsulated options may be searched for by
+ * using DHCP_ENCAP_OPT() to construct the tag value.
  *
- * Where multiple option blocks contain the same DHCP option, the
- * option from the highest-priority block will be returned.  (Priority
- * of an options block is determined by the value of the @c
- * DHCP_EB_PRIORITY option within the block, if present; the default
- * priority is zero).
+ * If @c options is NULL, all registered option blocks will be
+ * searched.  Where multiple option blocks contain the same DHCP
+ * option, the option from the highest-priority block will be
+ * returned.  (Priority of an options block is determined by the value
+ * of the @c DHCP_EB_PRIORITY option within the block, if present; the
+ * default priority is zero).
  */
-struct dhcp_option * find_global_dhcp_option ( unsigned int tag ) {
-	struct dhcp_option_block *options;
+struct dhcp_option * find_dhcp_option ( struct dhcp_option_block *options,
+					unsigned int tag ) {
 	struct dhcp_option *option;
 
-	list_for_each_entry ( options, &option_blocks, list ) {
-		if ( ( option = find_dhcp_option ( options, tag ) ) )
-			return option;
+	if ( options ) {
+		return find_dhcp_option_with_encap ( options, tag, NULL );
+	} else {
+		list_for_each_entry ( options, &option_blocks, list ) {
+			if ( ( option = find_dhcp_option ( options, tag ) ) )
+				return option;
+		}
+		return NULL;
 	}
-	return NULL;
 }
 
 /**
 	size_t new_len = ( len ? ( len + DHCP_OPTION_HEADER_LEN ) : 0 );
 
 	/* Find old instance of this option, if any */
-	option = find_dhcp_option ( options, tag );
+	option = find_dhcp_option_with_encap ( options, tag, &encapsulator );
 	if ( option ) {
 		old_len = dhcp_option_len ( option );
 		DBG ( "Resizing DHCP option %s from length %d to %d\n",
 	
 	/* Ensure that encapsulator exists, if required */
 	if ( DHCP_IS_ENCAP_OPT ( tag ) ) {
-		encapsulator = find_dhcp_option ( options, encap_tag );
 		if ( ! encapsulator )
 			encapsulator = set_dhcp_option ( options, encap_tag,
 							 empty_encapsulator,
 
 	return option;
 }
+
+/**
+ * Find DHCP option within all registered DHCP options blocks
+ *
+ * @v tag		DHCP option tag to search for
+ * @ret option		DHCP option, or NULL if not found
+ *
+ * This function exists merely as a notational shorthand for
+ * find_dhcp_option() with @c options set to NULL.
+ */
+struct dhcp_option * find_global_dhcp_option ( unsigned int tag ) {
+	return find_dhcp_option ( NULL, tag );
+}
+
+/**
+ * Find DHCP numerical option, and return its value
+ *
+ * @v options		DHCP options block
+ * @v tag		DHCP option tag to search for
+ * @ret value		Numerical value of the option, or 0 if not found
+ *
+ * This function exists merely as a notational shorthand for a call to
+ * find_dhcp_option() followed by a call to dhcp_num_option().  It is
+ * not possible to distinguish between the cases "option not found"
+ * and "option has a value of zero" using this function; if this
+ * matters to you then issue the two constituent calls directly and
+ * check that find_dhcp_option() returns a non-NULL value.
+ */
+unsigned long find_dhcp_num_option ( struct dhcp_option_block *options,
+				     unsigned int tag ) {
+	return dhcp_num_option ( find_dhcp_option ( options, tag ) );
+}
+
+/**
+ * Find DHCP numerical option, and return its value
+ *
+ * @v tag		DHCP option tag to search for
+ * @ret value		Numerical value of the option, or 0 if not found
+ *
+ * This function exists merely as a notational shorthand for a call to
+ * find_global_dhcp_option() followed by a call to dhcp_num_option().
+ * It is not possible to distinguish between the cases "option not
+ * found" and "option has a value of zero" using this function; if
+ * this matters to you then issue the two constituent calls directly
+ * and check that find_global_dhcp_option() returns a non-NULL value.
+ */
+unsigned long find_global_dhcp_num_option ( unsigned int tag ) {
+	return dhcp_num_option ( find_global_dhcp_option ( tag ) );
+}
+
+/**
+ * Delete DHCP option
+ *
+ * @v options		DHCP options block
+ * @v tag		DHCP option tag
+ *
+ * This function exists merely as a notational shorthand for a call to
+ * set_dhcp_option() with @c len set to zero.
+ */
+void delete_dhcp_option ( struct dhcp_option_block *options,
+			  unsigned int tag ) {
+	set_dhcp_option ( options, tag, NULL, 0 );
+}