Handle i4btrace captures if they're from a machine with the opposite

byte order from the machine that's reading them.

svn path=/trunk/; revision=1338

3 files changed, 62 insertions, 19 deletions

diff --git a/wiretap/i4btrace.c b/wiretap/i4btrace.c
index 2445b9c490..80df4367b7 100644
--- a/wiretap/i4btrace.c
+++ b/wiretap/i4btrace.c
@@ -1,6 +1,6 @@
 /* i4btrace.c
  *
- * $Id: i4btrace.c,v 1.1 1999/12/12 22:40:09 gram Exp $
+ * $Id: i4btrace.c,v 1.2 1999/12/15 02:25:50 guy Exp $
  *
  * Wiretap Library
  * Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
@@ -34,10 +34,19 @@
 
 static int i4btrace_read(wtap *wth, int *err);
 
+/*
+ * Test some fields in the header to see if they make sense.
+ */
+#define	I4B_HDR_IS_OK(hdr) \
+	(!((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 || \
+	    (unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 || \
+	    (unsigned)hdr.trunc > 2048))
+
 int i4btrace_open(wtap *wth, int *err)
 {
 	int bytes_read;
 	i4b_trace_hdr_t hdr;
+	gboolean byte_swapped = FALSE;
 
 	/* I4B trace files have no magic in the header... Sigh */
 	file_seek(wth->fh, 0, SEEK_SET);
@@ -51,10 +60,28 @@ int i4btrace_open(wtap *wth, int *err)
 	}
 
 	/* Silly heuristic... */
-	if ((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 ||
-			(unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 ||
-			(unsigned)hdr.trunc > 2048)
-		return 0;
+	if (!I4B_HDR_IS_OK(hdr)) {
+		/*
+		 * OK, try byte-swapping the header fields.
+		 */
+		hdr.length = BSWAP32(hdr.length);
+		hdr.unit = BSWAP32(hdr.unit);
+		hdr.type = BSWAP32(hdr.type);
+		hdr.dir = BSWAP32(hdr.dir);
+		hdr.trunc = BSWAP32(hdr.trunc);
+		if (!I4B_HDR_IS_OK(hdr)) {
+			/*
+			 * It doesn't look valid in either byte order.
+			 */
+			return 0;
+		}
+
+		/*
+		 * It looks valid byte-swapped, so assume it's a
+		 * trace written in the opposite byte order.
+		 */
+		byte_swapped = TRUE;
+	}
 
 	file_seek(wth->fh, 0, SEEK_SET);
 	wth->data_offset = 0;
@@ -69,6 +96,7 @@ int i4btrace_open(wtap *wth, int *err)
 	wth->capture.i4btrace->start = hdr.time.tv_sec;
 	wth->capture.i4btrace->bchannel_prot[0] = -1;
 	wth->capture.i4btrace->bchannel_prot[1] = -1;
+	wth->capture.i4btrace->byte_swapped = byte_swapped;
 
 	wth->file_encap = WTAP_ENCAP_PER_PACKET;
 
@@ -100,8 +128,22 @@ static int i4btrace_read(wtap *wth, int *err)
 		return 0;
 	}
 	wth->data_offset += sizeof hdr;
-	length = pletohs(&hdr.length) - sizeof(hdr);
-	if (length == 0) return 0;
+	if (wth->capture.i4btrace->byte_swapped) {
+		/*
+		 * Byte-swap the header.
+		 */
+		hdr.length = BSWAP32(hdr.length);
+		hdr.unit = BSWAP32(hdr.unit);
+		hdr.type = BSWAP32(hdr.type);
+		hdr.dir = BSWAP32(hdr.dir);
+		hdr.trunc = BSWAP32(hdr.trunc);
+		hdr.count = BSWAP32(hdr.count);
+		hdr.time.tv_sec = BSWAP32(hdr.time.tv_sec);
+		hdr.time.tv_usec = BSWAP32(hdr.time.tv_usec);
+	}
+	length = hdr.length - sizeof(hdr);
+	if (length == 0)
+		return 0;
 
 	wth->phdr.len = length;
 	wth->phdr.caplen = length;
diff --git a/wiretap/libpcap.c b/wiretap/libpcap.c
index e290a3d790..92da968682 100644
--- a/wiretap/libpcap.c
+++ b/wiretap/libpcap.c
@@ -1,6 +1,6 @@
 /* libpcap.c
  *
- * $Id: libpcap.c,v 1.27 1999/12/11 00:40:39 guy Exp $
+ * $Id: libpcap.c,v 1.28 1999/12/15 02:25:50 guy Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@verdict.uthscsa.edu>
@@ -53,16 +53,6 @@
 #define	PCAP_MODIFIED_MAGIC		0xa1b2cd34
 #define	PCAP_SWAPPED_MODIFIED_MAGIC	0x34cdb2a1
 
-/* Macros to byte-swap 32-bit and 16-bit quantities. */
-#define	BSWAP32(x) \
-	((((x)&0xFF000000)>>24) | \
-	 (((x)&0x00FF0000)>>8) | \
-	 (((x)&0x0000FF00)<<8) | \
-	 (((x)&0x000000FF)<<24))
-#define	BSWAP16(x) \
-	 ((((x)&0xFF00)>>8) | \
-	  (((x)&0x00FF)<<8))
-
 /* On some systems, the FDDI MAC addresses are bit-swapped. */
 #if !defined(ultrix) && !defined(__alpha) && !defined(__bsdi__)
 #define BIT_SWAPPED_MAC_ADDRS
diff --git a/wiretap/wtap.h b/wiretap/wtap.h
index da07c6fa3d..36eaca4707 100644
--- a/wiretap/wtap.h
+++ b/wiretap/wtap.h
@@ -1,6 +1,6 @@
 /* wtap.h
  *
- * $Id: wtap.h,v 1.61 1999/12/15 01:34:16 guy Exp $
+ * $Id: wtap.h,v 1.62 1999/12/15 02:25:50 guy Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@verdict.uthscsa.edu>
@@ -160,6 +160,7 @@ typedef struct {
 } radcom_t;
 
 typedef struct {
+	gboolean byte_swapped;
 	time_t	start;
 	int bchannel_prot[2];	/* For the V.120 heuristic */
 } i4btrace_t;
@@ -475,6 +476,16 @@ int wtap_pcap_encap_to_wtap_encap(int encap);
 #define	WTAP_ERR_ZLIB_MAX			-100
 #define	WTAP_ERR_ZLIB_MIN			-300
 
+/* Macros to byte-swap 32-bit and 16-bit quantities. */
+#define	BSWAP32(x) \
+	((((x)&0xFF000000)>>24) | \
+	 (((x)&0x00FF0000)>>8) | \
+	 (((x)&0x0000FF00)<<8) | \
+	 (((x)&0x000000FF)<<24))
+#define	BSWAP16(x) \
+	 ((((x)&0xFF00)>>8) | \
+	  (((x)&0x00FF)<<8))
+
 /* Turn host-byte-order values into little-endian values. */
 #ifdef WORDS_BIGENDIAN
 #define htoles(s) ((guint16)                       \