mind MSVC's UNALIGNED macro (GH #335 pt.2)

[tcpdump] / tcpdump-stdinc.h

diff --git a/tcpdump-stdinc.h b/tcpdump-stdinc.h
index 5aba8fdcc0252d936257c964a6d6abbcca5d274b..eb6c9428d9064260a68948128a3a8df3921fa656 100644 (file)
--- a/tcpdump-stdinc.h
+++ b/tcpdump-stdinc.h
@@ -69,8 +69,6 @@
 #define read _read
 #define close _close
 #define O_RDONLY _O_RDONLY
-
-typedef short ino_t;
 #endif /* __MINGW32__ */
 
 #ifdef __MINGW32__
@@ -84,6 +82,13 @@ extern const char *inet_ntop (int, const void *, char *, size_t);
 extern int inet_pton (int, const char *, void *);
 extern int inet_aton (const char *cp, struct in_addr *addr);
 
+/*
+ * With MSVC, for C, __inline is used to make a function an inline.
+ */
+#ifdef _MSC_VER
+#define inline __inline
+#endif
+
 #ifndef INET6_ADDRSTRLEN
 #define INET6_ADDRSTRLEN 46
 #endif
@@ -131,8 +136,45 @@ typedef char* caddr_t;
 
 #endif /* WIN32 */
 
-#ifdef INET6
-#include "ip6.h"
+#ifndef HAVE___ATTRIBUTE__
+#define __attribute__(x)
+#endif
+
+/*
+ * Used to declare a structure unaligned, so that the C compiler,
+ * if necessary, generates code that doesn't assume alignment.
+ * This is required because there is no guarantee that the packet
+ * data we get from libpcap/WinPcap is properly aligned.
+ *
+ * This assumes that, for all compilers that support __attribute__:
+ *
+ *     1) they support __attribute__((packed));
+ *
+ *     2) for all instruction set architectures requiring strict
+ *        alignment, declaring a structure with that attribute
+ *        causes the compiler to generate code that handles
+ *        misaligned 2-byte, 4-byte, and 8-byte integral
+ *        quantities.
+ *
+ * It does not (yet) handle compilers where you can get the compiler
+ * to generate code of that sort by some other means.
+ *
+ * This is required in order to, for example, keep the compiler from
+ * generating, for
+ *
+ *     if (bp->bp_htype == 1 && bp->bp_hlen == 6 && bp->bp_op == BOOTPREQUEST) {
+ *
+ * in print-bootp.c, code that loads the first 4-byte word of a
+ * "struct bootp", masking out the bp_hops field, and comparing the result
+ * against 0x01010600.
+ *
+ * Note: this also requires that padding be put into the structure,
+ * at least for compilers where it's implemented as __attribute__((packed)).
+ */
+#if defined(_MSC_VER) && defined(UNALIGNED)
+/* MSVC may have its own macro defined with the same name and purpose. */
+#else
+#define UNALIGNED      __attribute__((packed))
 #endif
 
 #if defined(WIN32) || defined(MSDOS)