[uri] Allow URIs to incorporate a parameter list

HTTP POST requires the ability to associate a parameter list with a
URI.  There is no standardised syntax for this.  Use a non-standard
URI syntax to incorporate the specification of a parameter list within
a URI:

  URI = [ absoluteURI | relativeURI ]
	[ "#" fragment ] [ "##params" [ "=" paramsName ] ]

e.g.

  http://boot.ipxe.org/demo/boot.php##params
  http://boot.ipxe.org/demo/boot.php##params=mylist

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/uri.c

 #include <libgen.h>
 #include <ctype.h>
 #include <ipxe/vsprintf.h>
+#include <ipxe/params.h>
 #include <ipxe/uri.h>
 
 /**
 		DBG ( " query \"%s\"", uri->query );
 	if ( uri->fragment )
 		DBG ( " fragment \"%s\"", uri->fragment );
+	if ( uri->params )
+		DBG ( " params \"%s\"", uri->params->name );
+}
+
+/**
+ * Free URI
+ *
+ * @v refcnt		Reference count
+ */
+static void free_uri ( struct refcnt *refcnt ) {
+	struct uri *uri = container_of ( refcnt, struct uri, refcnt );
+
+	if ( uri->params )
+		destroy_parameters ( uri->params );
+	free ( uri );
 }
 
 /**
 	uri = zalloc ( sizeof ( *uri ) + raw_len );
 	if ( ! uri )
 		return NULL;
+	ref_init ( &uri->refcnt, free_uri );
 	raw = ( ( ( char * ) uri ) + sizeof ( *uri ) );
 
 	/* Copy in the raw string */
 	memcpy ( raw, uri_string, raw_len );
 
-	/* Start by chopping off the fragment, if it exists */
+	/* Identify the parameter list, if present */
+	if ( ( tmp = strstr ( raw, "##params" ) ) ) {
+		*tmp = '\0';
+		tmp += 8 /* "##params" */;
+		uri->params = find_parameters ( *tmp ? ( tmp + 1 ) : NULL );
+		if ( uri->params ) {
+			claim_parameters ( uri->params );
+		} else {
+			/* Ignore non-existent submission blocks */
+		}
+	}
+
+	/* Chop off the fragment, if it exists */
 	if ( ( tmp = strchr ( raw, '#' ) ) ) {
 		*(tmp++) = '\0';
 		uri->fragment = tmp;

src/include/ipxe/uri.h

 #include <stdlib.h>
 #include <ipxe/refcnt.h>
 
+struct parameters;
+
 /** A Uniform Resource Identifier
  *
  * Terminology for this data structure is as per uri(7), except that
 	const char *query;
 	/** Fragment */
 	const char *fragment;
+	/** Form parameters */
+	struct parameters *params;
 } __attribute__ (( packed ));
 
 /** A field in a URI