/* packet-null.c
* Routines for null packet disassembly
*
- * $Id: packet-null.c,v 1.2 1998/09/27 22:12:33 gerald Exp $
+ * $Id: packet-null.c,v 1.20 2000/03/27 17:53:19 gram Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@zing.org>
#include <sys/types.h>
#endif
-#include <gtk/gtk.h>
-#include <stdio.h>
+#include <glib.h>
+
+#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
-#include <pcap.h>
+#endif
-#include "ethereal.h"
#include "packet.h"
+#include "packet-atalk.h"
+#include "packet-ip.h"
+#include "packet-ipv6.h"
+#include "packet-ipx.h"
+#include "packet-osi.h"
+#include "packet-ppp.h"
+#include "etypes.h"
+
+extern const value_string etype_vals[];
+
+/* protocols and header fields */
+static int proto_null = -1;
+static int hf_null_etype = -1;
+static int hf_null_family = -1;
+
+static gint ett_null = -1;
+
+/* Null/loopback structs and definitions */
+
+/* Macro to byte-swap 32-bit quantities. */
+#define BSWAP32(x) \
+ ((((x)&0xFF000000)>>24) | \
+ (((x)&0x00FF0000)>>8) | \
+ (((x)&0x0000FF00)<<8) | \
+ (((x)&0x000000FF)<<24))
+
+/* BSD AF_ values. */
+#define BSD_AF_INET 2
+#define BSD_AF_ISO 7
+#define BSD_AF_APPLETALK 16
+#define BSD_AF_IPX 23
+#define BSD_AF_INET6_BSD 24 /* OpenBSD (and probably NetBSD), BSD/OS */
+#define BSD_AF_INET6_FREEBSD 28
+
+/* Family values. */
+static const value_string family_vals[] = {
+ {BSD_AF_INET, "IP" },
+ {BSD_AF_ISO, "OSI" },
+ {BSD_AF_APPLETALK, "Appletalk" },
+ {BSD_AF_IPX, "Netware IPX/SPX"},
+ {BSD_AF_INET6_BSD, "IPv6" },
+ {BSD_AF_INET6_FREEBSD, "IPv6" },
+ {0, NULL }
+};
void
-dissect_null( const u_char *pd, frame_data *fd, GtkTree *tree ) {
- e_nullhdr nh;
- GtkWidget *ti, *fh_tree;
-
- nh.null_next = pd[0];
- nh.null_len = pd[1];
- memcpy((char *)&nh.null_family, (char *)&pd[2], sizeof(nh.null_family));
-
- /* load the top pane info. This should be overwritten by
- the next protocol in the stack */
- if(fd->win_info[COL_NUM]) {
- strcpy(fd->win_info[COL_SOURCE], "N/A" );
- strcpy(fd->win_info[COL_DESTINATION], "N/A" );
- strcpy(fd->win_info[COL_PROTOCOL], "N/A" );
- strcpy(fd->win_info[COL_INFO], "Null/Loopback" );
- }
+capture_null( const u_char *pd, packet_counts *ld )
+{
+ guint32 null_header;
+
+ /*
+ * BSD drivers that use DLT_NULL - including the FreeBSD 3.2 ISDN-for-BSD
+ * drivers, as well as the 4.4-Lite and FreeBSD loopback drivers -
+ * appear to stuff the AF_ value for the protocol, in *host* byte
+ * order, in the first four bytes.
+ *
+ * However, according to Gerald Combs, a FreeBSD ISDN PPP dump that
+ * Andreas Klemm sent to ethereal-dev has a packet type of DLT_NULL,
+ * and the family bits look like PPP's protocol field. (Was this an
+ * older, or different, ISDN driver?) Looking at what appears to be
+ * that capture file, it appears that it's using PPP in HDLC framing,
+ * RFC 1549, wherein the first two octets of the frame are 0xFF
+ * (address) and 0x03 (control), so the header bytes are, in order:
+ *
+ * 0xFF
+ * 0x03
+ * high-order byte of a PPP protocol field
+ * low-order byte of a PPP protocol field
+ *
+ * when reading it on a little-endian machine; that means it's
+ * PPPP03FF, where PPPP is a byte-swapped PPP protocol field.
+ *
+ * "libpcap" for Linux uses DLT_NULL only for the loopback device.
+ * The loopback driver in Linux 2.0.36, at least, puts an *Ethernet*
+ * header at the beginning of loopback packets; however, "libpcap"
+ * for Linux compensates for this by skipping the source and
+ * destination MAC addresses, replacing them with 2 bytes of 0.
+ * This means that if we're reading the capture on a little-endian
+ * machine, the header, treated as a 32-bit integer, looks like
+ *
+ * EEEEEEEEEEEEEEEE0000000000000000
+ *
+ * where "EEEEEEEEEEEEEEEE" is the Ethernet type, and if we're reading
+ * it on a big-endian machine, it looks like
+ *
+ * 0000000000000000EEEEEEEEEEEEEEEE
+ *
+ * The Ethernet type might or might not be byte-swapped; I haven't
+ * bothered thinking about that yet.
+ *
+ * AF_ values are (relatively) small integers, and shouldn't have their
+ * upper 16 bits zero; Ethernet types have to fit in 16 bits and
+ * thus must have their upper 16 bits zero. Therefore, if the upper
+ * 16 bits of the field aren't zero, it's in the wrong byte order.
+ *
+ * Ethernet types are bigger than 1536, and AF_ values are smaller
+ * than 1536, so we needn't worry about one being mistaken for
+ * the other. (There may be a problem if the 16-bit Ethernet
+ * type is byte-swapped as a 16-bit quantity, but if when treated
+ * as a 32-bit quantity its upper 16 bits are zero, but I'll think
+ * about that one later.)
+ *
+ * As for the PPP protocol field values:
+ *
+ * 0x0000 does not appear to be a valid PPP protocol field value,
+ * so the upper 16 bits will be non-zero, and we'll byte swap it.
+ * It'll then be
+ *
+ * 0xFF03PPPP
+ *
+ * where PPPP is a non-byte-swapped PPP protocol field; we'll
+ * check for the upper 16 bits of the byte-swapped field being
+ * non-zero and, if so, assume the lower 16 bits are a PPP
+ * protocol field (AF_ and Ethernet protocol fields should leave
+ * the upper 16 bits zero - unless somebody stuff something else
+ * there; see below).
+ *
+ * So, to compensate for this mess, we:
+ *
+ * check if the first two octets are 0xFF and 0x03 and, if so,
+ * treat it as a PPP frame;
+ *
+ * otherwise, byte-swap the value if its upper 16 bits aren't zero,
+ * and compare the lower 16 bits of the value against Ethernet
+ * and AF_ types.
+ *
+ * If, as implied by an earlier version of the "e_nullhdr" structure,
+ * the family is only 16 bits, and there are "next" and "len" fields
+ * before it, that all goes completely to hell. (Note that, for
+ * the BSD header, we could byte-swap it if the capture was written
+ * on a machine with the opposite byte-order to ours - the "libpcap"
+ * header lets us determine that - but it's more of a mess for Linux,
+ * given that the effect of inserting the two 0 bytes depends only
+ * on the byte order of the machine reading the file.)
+ */
+ if (pd[0] == 0xFF && pd[1] == 0x03) {
+ /*
+ * Hand it to PPP.
+ */
+ capture_ppp(pd, ld);
+ } else {
+ /*
+ * Treat it as a normal DLT_NULL header.
+ */
+ memcpy((char *)&null_header, (char *)&pd[0], sizeof(null_header));
+
+ if ((null_header & 0xFFFF0000) != 0) {
+ /* Byte-swap it. */
+ null_header = BSWAP32(null_header);
+ }
+
+ /*
+ * The null header value must be greater than the IEEE 802.3 maximum
+ * frame length to be a valid Ethernet type; if it is, hand it
+ * to "ethertype()", otherwise treat it as a BSD AF_type (we wire
+ * in the values of the BSD AF_ types, because the values
+ * in the file will be BSD values, and the OS on which
+ * we're building this might not have the same values or
+ * might not have them defined at all; XXX - what if different
+ * BSD derivatives have different values?).
+ */
+ if (null_header > IEEE_802_3_MAX_LEN)
+ capture_ethertype(null_header, 4, pd, ld);
+ else {
+ switch (null_header) {
- /* populate a tree in the second pane with the status of the link
- layer (ie none) */
- if(tree) {
- ti = add_item_to_tree( GTK_WIDGET(tree), 0, 4,
- "Null/Loopback (%d on link, %d captured)", fd->pkt_len,
- fd->cap_len );
- fh_tree = gtk_tree_new();
- add_subtree(ti, fh_tree, ETT_NULL);
- add_item_to_tree(fh_tree, 0, 1, "Next: %02x", nh.null_next);
- add_item_to_tree(fh_tree, 1, 1, "Length: %02x", nh.null_len);
- add_item_to_tree(fh_tree, 2, 2, "Family: %04x", nh.null_family);
+ case BSD_AF_INET:
+ capture_ip(pd, 4, ld);
+ break;
+
+ default:
+ ld->other++;
+ break;
+ }
+ }
}
+}
+
+void
+dissect_null( const u_char *pd, frame_data *fd, proto_tree *tree )
+{
+ guint32 null_header;
+ proto_tree *fh_tree;
+ proto_item *ti;
- /*
- From what I've read in various sources, this is supposed to be an
- address family, e.g. AF_INET. However, a FreeBSD ISDN PPP dump that
- Andreas Klemm sent to ethereal-dev has a packet type of DLT_NULL, and
- the family bits look like PPP's protocol field. A dump of the loopback
- interface on my Linux box also has a link type of DLT_NULL (as it should
- be), but the family bits look like ethernet's protocol type. To
- further confuse matters, nobody seems to be paying attention to byte
- order.
- - gcc
- */
-
- switch (nh.null_family) {
- case 0x0008:
- case 0x0800:
- case 0x0021:
- case 0x2100:
- dissect_ip(pd, 4, fd, tree);
- break;
- default:
- dissect_data(pd, 4, fd, tree);
- break;
+ /*
+ * See comment in "capture_null()" for an explanation of what we're
+ * doing.
+ */
+ if (pd[0] == 0xFF && pd[1] == 0x03) {
+ /*
+ * Hand it to PPP.
+ */
+ dissect_ppp(pd, 0, fd, tree);
+ } else {
+ /*
+ * Treat it as a normal DLT_NULL header.
+ */
+ memcpy((char *)&null_header, (char *)&pd[0], sizeof(null_header));
+
+ if ((null_header & 0xFFFF0000) != 0) {
+ /* Byte-swap it. */
+ null_header = BSWAP32(null_header);
+ }
+
+ /* load the top pane info. This should be overwritten by
+ the next protocol in the stack */
+ if(check_col(fd, COL_RES_DL_SRC))
+ col_add_str(fd, COL_RES_DL_SRC, "N/A" );
+ if(check_col(fd, COL_RES_DL_DST))
+ col_add_str(fd, COL_RES_DL_DST, "N/A" );
+ if(check_col(fd, COL_PROTOCOL))
+ col_add_str(fd, COL_PROTOCOL, "N/A" );
+ if(check_col(fd, COL_INFO))
+ col_add_str(fd, COL_INFO, "Null/Loopback" );
+
+ /*
+ * The null header value must be greater than the IEEE 802.3 maximum
+ * frame length to be a valid Ethernet type; if it is, hand it
+ * to "ethertype()", otherwise treat it as a BSD AF_type (we wire
+ * in the values of the BSD AF_ types, because the values
+ * in the file will be BSD values, and the OS on which
+ * we're building this might not have the same values or
+ * might not have them defined at all; XXX - what if different
+ * BSD derivatives have different values?).
+ */
+ if (null_header > IEEE_802_3_MAX_LEN) {
+ if (tree) {
+ ti = proto_tree_add_item(tree, proto_null, 0, 4, NULL);
+ fh_tree = proto_item_add_subtree(ti, ett_null);
+ } else
+ fh_tree = NULL;
+ ethertype(null_header, 4, pd, fd, tree, fh_tree, hf_null_etype);
+ } else {
+ /* populate a tree in the second pane with the status of the link
+ layer (ie none) */
+ if (tree) {
+ ti = proto_tree_add_item(tree, proto_null, 0, 4, NULL);
+ fh_tree = proto_item_add_subtree(ti, ett_null);
+ proto_tree_add_item(fh_tree, hf_null_family, 0, 4, null_header);
+ }
+
+ switch (null_header) {
+
+ case BSD_AF_INET:
+ dissect_ip(pd, 4, fd, tree);
+ break;
+
+ case BSD_AF_APPLETALK:
+ dissect_ddp(pd, 4, fd, tree);
+ break;
+
+ case BSD_AF_IPX:
+ dissect_ipx(pd, 4, fd, tree);
+ break;
+
+ case BSD_AF_ISO:
+ dissect_osi(pd, 4, fd, tree);
+ break;
+
+ case BSD_AF_INET6_BSD:
+ case BSD_AF_INET6_FREEBSD:
+ dissect_ipv6(pd, 4, fd, tree);
+ break;
+
+ default:
+ dissect_data(pd, 4, fd, tree);
+ break;
+ }
+ }
}
}
+
+void
+proto_register_null(void)
+{
+ static hf_register_info hf[] = {
+
+ /* registered here but handled in ethertype.c */
+ { &hf_null_etype,
+ { "Type", "null.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0,
+ "" }},
+
+ { &hf_null_family,
+ { "Family", "null.family", FT_UINT32, BASE_HEX, VALS(family_vals), 0x0,
+ "" }}
+ };
+ static gint *ett[] = {
+ &ett_null,
+ };
+
+ proto_null = proto_register_protocol ("Null/Loopback", "null" );
+ proto_register_field_array(proto_null, hf, array_length(hf));
+ proto_register_subtree_array(ett, array_length(ett));
+}
git.samba.org / obnox / wireshark / wip.git / blobdiff