[peerdist] Add support for constructing and decoding discovery messages

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

src/include/ipxe/errfile.h

@@ -246,6 +246,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define ERRFILE_rndis			( ERRFILE_NET | 0x003d0000 )
 #define ERRFILE_pccrc			( ERRFILE_NET | 0x003e0000 )
 #define ERRFILE_stp			( ERRFILE_NET | 0x003f0000 )
+#define ERRFILE_pccrd			( ERRFILE_NET | 0x00400000 )
 
 #define ERRFILE_image		      ( ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_elf		      ( ERRFILE_IMAGE | 0x00010000 )

src/include/ipxe/pccrd.h

@@ -0,0 +1,47 @@
+#ifndef _IPXE_PCCRD_H
+#define _IPXE_PCCRD_H
+
+/** @file
+ *
+ * Peer Content Caching and Retrieval: Discovery Protocol [MS-PCCRD]
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/** PeerDist discovery port */
+#define PEERDIST_DISCOVERY_PORT 3702
+
+/** PeerDist discovery IPv4 address (239.255.255.250) */
+#define PEERDIST_DISCOVERY_IPV4 \
+	( ( 239 << 24 ) | ( 255 << 16 ) | ( 255 << 8 ) | ( 250 << 0 ) )
+
+/** PeerDist discovery IPv6 address (ff02::c) */
+#define PEERDIST_DISCOVERY_IPV6 \
+	{ 0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xc }
+
+/** A PeerDist discovery reply block count */
+struct peerdist_discovery_block_count {
+	/** Count (as an eight-digit hex value) */
+	char hex[8];
+} __attribute__ (( packed ));
+
+/** A PeerDist discovery reply */
+struct peerdist_discovery_reply {
+	/** List of segment ID strings
+	 *
+	 * The list is terminated with a zero-length string.
+	 */
+	char *ids;
+	/** List of peer locations
+	 *
+	 * The list is terminated with a zero-length string.
+	 */
+	char *locations;
+};
+
+extern char * peerdist_discovery_request ( const char *uuid, const char *id );
+extern int peerdist_discovery_reply ( char *data, size_t len,
+				      struct peerdist_discovery_reply *reply );
+
+#endif /* _IPXE_PCCRD_H */