X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/7678647d1ad55f9d9976740e6e0dc97bc8377daf..d511b994b9931460771dc56c70b791204178d157:/print-atm.c

diff --git a/print-atm.c b/print-atm.c
index 189831a6..aecc58b6 100644
--- a/print-atm.c
+++ b/print-atm.c
@@ -19,8 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 #ifndef lint
-static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-atm.c,v 1.27 2002-12-04 19:12:39 hannes Exp $ (LBL)";
+static const char rcsid[] _U_ =
+    "@(#) $Header: /tcpdump/master/tcpdump/print-atm.c,v 1.35 2003-11-16 09:36:13 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -39,42 +39,81 @@ static const char rcsid[] =
 #include "ethertype.h"
 #include "atm.h"
 #include "atmuni31.h"
+#include "llc.h"
 
 #include "ether.h"
 
+/*
+ * Print an RFC 1483 LLC-encapsulated ATM frame.
+ */
+static void
+atm_llc_print(const u_char *p, int length, int caplen)
+{
+	u_short extracted_ethertype;
+
+	if (!llc_print(p, length, caplen, NULL, NULL,
+	    &extracted_ethertype)) {
+		/* ether_type not known, print raw packet */
+		if (extracted_ethertype) {
+			printf("(LLC %s) ",
+		etherproto_string(htons(extracted_ethertype)));
+		}
+		if (!xflag && !qflag)
+			default_print(p, caplen);
+	}
+}
+
+/*
+ * Given a SAP value, generate the LLC header value for a UI packet
+ * with that SAP as the source and destination SAP.
+ */
+#define LLC_UI_HDR(sap)	((sap)<<16 | (sap<<8) | 0x03)
+
 /*
  * This is the top level routine of the printer.  'p' points
  * to the LLC/SNAP header of the packet, 'h->ts' is the timestamp,
  * 'h->length' is the length of the packet off the wire, and 'h->caplen'
  * is the number of bytes actually captured.
  */
-void
-atm_if_print(u_char *user _U_, const struct pcap_pkthdr *h, const u_char *p)
+u_int
+atm_if_print(const struct pcap_pkthdr *h, const u_char *p)
 {
 	u_int caplen = h->caplen;
 	u_int length = h->len;
-
-	++infodelay;
-	ts_print(&h->ts);
+	u_int32_t llchdr;
+	u_int hdrlen = 0;
 
 	if (caplen < 8) {
 		printf("[|atm]");
-		goto out;
+		return (caplen);
 	}
 
 	/*
-	 * Some printers want to check that they're not walking off the
-	 * end of the packet.
-	 * Rather than pass it all the way down, we set this global.
+	 * Extract the presumed LLC header into a variable, for quick
+	 * testing.
+	 * Then check for a header that's neither a header for a SNAP
+	 * packet nor an RFC 2684 routed NLPID-formatted PDU nor
+	 * an 802.2-but-no-SNAP IP packet.
 	 */
-	snapend = p + caplen;
-
-	if (EXTRACT_24BITS(p) == 0xaaaa03) {
+	llchdr = EXTRACT_24BITS(p);
+	if (llchdr != LLC_UI_HDR(LLCSAP_SNAP) &&
+	    llchdr != LLC_UI_HDR(LLCSAP_ISONS) &&
+	    llchdr != LLC_UI_HDR(LLCSAP_IP)) {
 		/*
 		 * XXX - assume 802.6 MAC header from Fore driver.
-		 * XXX - should we also assume it's not a MAC header
-		 * if it begins with 0xfe 0xfe 0x03, for RFC 2684
-		 * routed NLPID-formatted PDUs?
+		 *
+		 * Unfortunately, the above list doesn't check for
+		 * all known SAPs, doesn't check for headers where
+		 * the source and destination SAP aren't the same,
+		 * and doesn't check for non-UI frames.  It also
+		 * runs the risk of an 802.6 MAC header that happens
+		 * to begin with one of those values being
+		 * incorrectly treated as an 802.2 header.
+		 *
+		 * So is that Fore driver still around?  And, if so,
+		 * is it still putting 802.6 MAC headers on ATM
+		 * packets?  If so, could it be changed to use a
+		 * new DLT_IEEE802_6 value if we added it?
 		 */
 		if (eflag)
 			printf("%08x%08x %08x%08x ",
@@ -85,15 +124,10 @@ atm_if_print(u_char *user _U_, const struct pcap_pkthdr *h, const u_char *p)
 		p += 20;
 		length -= 20;
 		caplen -= 20;
+		hdrlen += 20;
 	}
-
-        /* lets call into the generic LLC handler */
-	llc_print(p, length, caplen, NULL, NULL, NULL);
-
-	if (xflag)
-		default_print(p, caplen);
- out:
-	putchar('\n');
+	atm_llc_print(p, length, caplen);
+	return (hdrlen);
 }
 
 /*
@@ -162,40 +196,33 @@ atm_print(u_int vpi, u_int vci, u_int traftype, const u_char *p, u_int length,
 	if (eflag)
 		printf("VPI:%u VCI:%u ", vpi, vci);
 
-	/*
-	 * Some printers want to check that they're not walking off the
-	 * end of the packet.
-	 * Rather than pass it all the way down, we set this global.
-	 */
-	snapend = p + caplen;
-
 	if (vpi == 0) {
 		switch (vci) {
 
 		case PPC:
 			sig_print(p, caplen);
-			goto out;
+			return;
 
 		case BCC:
 			printf("broadcast sig: ");
-			goto out;
+			return;
 
 		case OAMF4SC:
 			printf("oamF4(segment): ");
-			goto out;
+			return;
 
 		case OAMF4EC:
 			printf("oamF4(end): ");
-			goto out;
+			return;
 
 		case METAC:
 			printf("meta: ");
-			goto out;
+			return;
 
 		case ILMIC:
 			printf("ilmi: ");
 			snmp_print(p, length);
-			goto out;
+			return;
 		}
 	}
 
@@ -205,17 +232,12 @@ atm_print(u_int vpi, u_int vci, u_int traftype, const u_char *p, u_int length,
 	default:
 		/*
 		 * Assumes traffic is LLC if unknown.
-                 * call into the generic LLC handler
 		 */
-		llc_print(p, length, caplen, NULL, NULL, NULL);
+		atm_llc_print(p, length, caplen);
 		break;
 
 	case ATM_LANE:
 		lane_print(p, length, caplen);
 		break;
 	}
-
-out:
-	if (xflag)
-		default_print(p, caplen);
 }