The "__attribute__((packed))" tag on structures causes some files not to

compile with Sun C, as "interface.h" isn't being included before the
structures are being declared.

Furthermore, in the files that Sun C *can* compile, it doesn't cause Sun
C to generate code that's safe with unaligned accesses, as
"__attribute__" is defined as a do-nothing macro with compilers that
don't support it.

Therefore, we get rid of that tag on the structures to which it was
added, and instead use "EXTRACT_16BIT()" and "EXTRACT_32BIT()" to fetch
16-bit and 32-bit big-endian quantities from packets.  We also fix some
other references to multi-byte quantities to get rid of code that tries
to do unaligned loads on platforms that don't support them.

We also throw in a hack that makes those macros use
"__attribute__((packed))" on structures containing only one 16-bit or
32-bit integer to get the compiler to generate unaligned-safe code
rather than doing it by hand.  (GCC on SPARC produces the same code that
doing it by hand does; I don't know if GCC on any other big-endian
strict-alignment processor generates better code for that case.  On
little-endian processors, as "ntohs()" and "ntohl()" might be functions,
that might actually produce worse code.)

Fix some places to use "%u" rather than "%d" to print unsigned
quantities.

1 files changed, 4 insertions, 3 deletions

diff --git a/print-ipcomp.c b/print-ipcomp.c
index 8cdb779d..bc76448f 100644
--- a/print-ipcomp.c
+++ b/print-ipcomp.c
@@ -21,7 +21,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-ipcomp.c,v 1.16 2002-11-09 17:19:26 itojun Exp $";
+    "@(#) $Header: /tcpdump/master/tcpdump/print-ipcomp.c,v 1.17 2002-12-11 07:14:03 guy Exp $";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -37,7 +37,7 @@ struct ipcomp {
 	u_int8_t comp_nxt;	/* Next Header */
 	u_int8_t comp_flags;	/* Length of data, in 32bit */
 	u_int16_t comp_cpi;	/* Compression parameter index */
-} __attribute__((packed));
+};
 
 #if defined(HAVE_LIBZ) && defined(HAVE_ZLIB_H)
 #include <zlib.h>
@@ -45,6 +45,7 @@ struct ipcomp {
 
 #include "interface.h"
 #include "addrtoname.h"
+#include "extract.h"
 
 int
 ipcomp_print(register const u_char *bp, int *nhdr)
@@ -57,7 +58,7 @@ ipcomp_print(register const u_char *bp, int *nhdr)
 #endif
 
 	ipcomp = (struct ipcomp *)bp;
-	cpi = (u_int16_t)ntohs(ipcomp->comp_cpi);
+	cpi = EXTRACT_16BITS(&ipcomp->comp_cpi);
 
 	/* 'ep' points to the end of available data. */
 	ep = snapend;