1 files changed, 138 insertions, 0 deletions
diff --git a/print-null.c b/print-null.c
new file mode 100644
index 0000000..a1b03f8
--- /dev/null
+++ b/print-null.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 1991, 1993, 1994, 1995, 1996, 1997
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+/* \summary: BSD loopback device printer */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+
+#define ND_LONGJMP_FROM_TCHECK
+#include "netdissect.h"
+#include "extract.h"
+#include "af.h"
+
+
+/*
+ * The DLT_NULL packet header is 4 bytes long. It contains a host-byte-order
+ * 32-bit integer that specifies the family, e.g. AF_INET.
+ *
+ * Note here that "host" refers to the host on which the packets were
+ * captured; that isn't necessarily *this* host.
+ *
+ * The OpenBSD DLT_LOOP packet header is the same, except that the integer
+ * is in network byte order.
+ */
+#define	NULL_HDRLEN 4
+
+/*
+ * Byte-swap a 32-bit number.
+ * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
+ * big-endian platforms.)
+ */
+#define	SWAPLONG(y) \
+((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
+
+static void
+null_hdr_print(netdissect_options *ndo, uint32_t family, u_int length)
+{
+	if (!ndo->ndo_qflag) {
+		ND_PRINT("AF %s (%u)",
+			tok2str(bsd_af_values,"Unknown",family),family);
+	} else {
+		ND_PRINT("%s",
+			tok2str(bsd_af_values,"Unknown AF %u",family));
+	}
+
+	ND_PRINT(", length %u: ", length);
+}
+
+/*
+ * This is the top level routine of the printer.  'p' points
+ * to the ether header of the packet, 'h->ts' is the timestamp,
+ * 'h->len' is the length of the packet off the wire, and 'h->caplen'
+ * is the number of bytes actually captured.
+ */
+void
+null_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
+{
+	u_int length = h->len;
+	u_int caplen = h->caplen;
+	uint32_t family;
+
+	ndo->ndo_protocol = "null";
+	ND_TCHECK_LEN(p, NULL_HDRLEN);
+	ndo->ndo_ll_hdr_len += NULL_HDRLEN;
+
+	family = GET_HE_U_4(p);
+
+	/*
+	 * This isn't necessarily in our host byte order; if this is
+	 * a DLT_LOOP capture, it's in network byte order, and if
+	 * this is a DLT_NULL capture from a machine with the opposite
+	 * byte-order, it's in the opposite byte order from ours.
+	 *
+	 * If the upper 16 bits aren't all zero, assume it's byte-swapped.
+	 */
+	if ((family & 0xFFFF0000) != 0)
+		family = SWAPLONG(family);
+
+	if (ndo->ndo_eflag)
+		null_hdr_print(ndo, family, length);
+
+	length -= NULL_HDRLEN;
+	caplen -= NULL_HDRLEN;
+	p += NULL_HDRLEN;
+
+	switch (family) {
+
+	case BSD_AFNUM_INET:
+		ip_print(ndo, p, length);
+		break;
+
+	case BSD_AFNUM_INET6_BSD:
+	case BSD_AFNUM_INET6_FREEBSD:
+	case BSD_AFNUM_INET6_DARWIN:
+		ip6_print(ndo, p, length);
+		break;
+
+	case BSD_AFNUM_ISO:
+		isoclns_print(ndo, p, length);
+		break;
+
+	case BSD_AFNUM_APPLETALK:
+		atalk_print(ndo, p, length);
+		break;
+
+	case BSD_AFNUM_IPX:
+		ipx_print(ndo, p, length);
+		break;
+
+	default:
+		/* unknown AF_ value */
+		if (!ndo->ndo_eflag)
+			null_hdr_print(ndo, family, length + NULL_HDRLEN);
+		if (!ndo->ndo_suppress_default_print)
+			ND_DEFAULTPRINT(p, caplen);
+	}
+}