radiotap: Fix compiler issues with packed structures

Replace the Radiotap parser platform.h file with use of helper functions
from utils/common.h to avoid compiler issues with the updated design and
getting pointers to members of packet structs.

Silence the warning about _next_bitmap assignment. This pointer is
dereferenced only with operations that are safe for unaligned access, so
the compiler warning is not helpful here.

__packed might not be defined in this context, so use STRUCT_PACKED from
utils/common.h.

Fixes: e6ac269433 ("radiotap: Update radiotap parser")
Signed-off-by: Jouni Malinen <j@w1.fi>

src/utils/platform.h

@@ -1,21 +1,18 @@
+/*
+ * Platform definitions for Radiotap parser
+ * Copyright (c) 2021, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
 #ifndef PLATFORM_H
 #define PLATFORM_H
 
 #include "includes.h"
 #include "common.h"
 
-#define le16_to_cpu		le_to_host16
-#define le32_to_cpu		le_to_host32
-
-#define get_unaligned(p)					\
-({								\
-	struct packed_dummy_struct {				\
-		typeof(*(p)) __val;				\
-	} __attribute__((packed)) *__ptr = (void *) (p);	\
-								\
-	__ptr->__val;						\
-})
-#define get_unaligned_le16(p)	le16_to_cpu(get_unaligned((le16 *)(p)))
-#define get_unaligned_le32(p)	le32_to_cpu(get_unaligned((le32 *)(p)))
+#define get_unaligned_le16(p)	WPA_GET_LE16((void *) (p))
+#define get_unaligned_le32(p)	WPA_GET_LE32((void *) (p))
 
 #endif /* PLATFORM_H */

src/utils/radiotap.c

@@ -111,7 +111,7 @@ int ieee80211_radiotap_iterator_init(
 	iterator->_arg = (uint8_t *)radiotap_header + sizeof(*radiotap_header);
 	iterator->_next_ns_data = NULL;
 	iterator->_reset_on_ext = 0;
-	iterator->_next_bitmap = &radiotap_header->it_present;
+	iterator->_next_bitmap = (le32 *) (((u8 *) radiotap_header) + offsetof(struct ieee80211_radiotap_header, it_present));
 	iterator->_next_bitmap++;
 	iterator->_vns = vns;
 	iterator->current_namespace = &radiotap_ns;

src/utils/radiotap.h

@@ -39,7 +39,7 @@ struct ieee80211_radiotap_header {
 	 * @it_present: (first) present word
 	 */
 	le32 it_present;
-} __packed;
+} STRUCT_PACKED;
 
 /* version is always 0 */
 #define PKTHDR_RADIOTAP_VERSION	0