[ipv6] Fix definition of IN6_IS_ADDR_LINKLOCAL()

Fix an erroneous htonl() in the definition of IN6_IS_ADDR_LINKLOCAL(),
and add self-tests for the IN6_IS_ADDR_xxx() family of macros.

Reported-by: Marin Hannache <git@mareo.fr>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/in.h

 
 #define IN6_IS_ADDR_LINKLOCAL( addr )					\
 	( ( *( ( const uint16_t * ) (addr) ) & htons ( 0xffc0 ) ) ==	\
-	  htonl ( 0xfe80 ) )
+	  htons ( 0xfe80 ) )
 
 /**
  * IPv4 socket address

src/tests/ipv6_test.c

 /** Define inline IPv6 address */
 #define IPV6(...) { __VA_ARGS__ }
 
+/** The unspecified IPv6 address */
+static const struct in6_addr sample_unspecified = {
+	.s6_addr = IPV6 ( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ),
+};
+
+/** A sample link-local IPv6 address */
+static const struct in6_addr sample_link_local = {
+	.s6_addr = IPV6 ( 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			  0x00, 0x00, 0x69, 0xff, 0xfe, 0x50, 0x58, 0x45 ),
+};
+
+/** A sample global IPv6 address */
+static const struct in6_addr sample_global = {
+	.s6_addr = IPV6 ( 0x20, 0x01, 0x0b, 0xa8, 0x00, 0x00, 0x01, 0xd4,
+			  0x00, 0x00, 0x00, 0x00, 0x69, 0x50, 0x58, 0x45 ),
+};
+
+/** A sample multicast IPv6 address */
+static const struct in6_addr sample_multicast = {
+	.s6_addr = IPV6 ( 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 ),
+};
+
 /**
  * Report an inet6_ntoa() test result
  *
  */
 static void ipv6_test_exec ( void ) {
 
+	/* Address testing macros */
+	ok (   IN6_IS_ADDR_UNSPECIFIED ( &sample_unspecified ) );
+	ok ( ! IN6_IS_ADDR_UNSPECIFIED ( &sample_link_local ) );
+	ok ( ! IN6_IS_ADDR_UNSPECIFIED ( &sample_global ) );
+	ok ( ! IN6_IS_ADDR_UNSPECIFIED ( &sample_multicast ) );
+	ok ( ! IN6_IS_ADDR_MULTICAST ( &sample_unspecified ) );
+	ok ( ! IN6_IS_ADDR_MULTICAST ( &sample_link_local ) );
+	ok ( ! IN6_IS_ADDR_MULTICAST ( &sample_global ) );
+	ok (   IN6_IS_ADDR_MULTICAST ( &sample_multicast ) );
+	ok ( ! IN6_IS_ADDR_LINKLOCAL ( &sample_unspecified ) );
+	ok (   IN6_IS_ADDR_LINKLOCAL ( &sample_link_local ) );
+	ok ( ! IN6_IS_ADDR_LINKLOCAL ( &sample_global ) );
+	ok ( ! IN6_IS_ADDR_LINKLOCAL ( &sample_multicast ) );
+
 	/* inet6_ntoa() tests */
 	inet6_ntoa_ok ( IPV6 ( 0x20, 0x01, 0x0b, 0xa8, 0x00, 0x00, 0x01, 0xd4,
 			       0x00, 0x00, 0x00, 0x00, 0x69, 0x50, 0x58, 0x45 ),