Skip the LLC and SNAP headers with -x.

Have llc_print() return the length of the LLC header, plus the length of
the SNAP header, if available - or, if it couldn't dissect the payload,
return the *negative* of that sum.  Use that return value in link-layer
printers.

1 files changed, 8 insertions, 6 deletions

diff --git a/print-ipfc.c b/print-ipfc.c
index b2869eb8..6d07f80e 100644
--- a/print-ipfc.c
+++ b/print-ipfc.c
@@ -76,15 +76,16 @@ ipfc_hdr_print(netdissect_options *ndo,
 	ND_PRINT((ndo, "%s %s %d: ", srcname, dstname, length));
 }
 
-static void
+static u_int
 ipfc_print(netdissect_options *ndo, const u_char *p, u_int length, u_int caplen)
 {
 	const struct ipfc_header *ipfcp = (const struct ipfc_header *)p;
 	struct ether_header ehdr;
+	int llc_hdrlen;
 
 	if (caplen < IPFC_HDRLEN) {
 		ND_PRINT((ndo, "[|ipfc]"));
-		return;
+		return (caplen);
 	}
 	/*
 	 * Get the network addresses into a canonical form
@@ -100,14 +101,17 @@ ipfc_print(netdissect_options *ndo, const u_char *p, u_int length, u_int caplen)
 	caplen -= IPFC_HDRLEN;
 
 	/* Try to print the LLC-layer header & higher layers */
-	if (llc_print(ndo, p, length, caplen, ESRC(&ehdr), EDST(&ehdr)) == 0) {
+	llc_hdrlen = llc_print(ndo, p, length, caplen, ESRC(&ehdr), EDST(&ehdr));
+	if (llc_hdrlen < 0) {
 		/*
 		 * Some kinds of LLC packet we cannot
 		 * handle intelligently
 		 */
 		if (!ndo->ndo_suppress_default_print)
 			ND_DEFAULTPRINT(p, caplen);
+		llc_hdrlen = -llc_hdrlen;
 	}
+	return (IPFC_HDRLEN + llc_hdrlen);
 }
 
 /*
@@ -119,7 +123,5 @@ ipfc_print(netdissect_options *ndo, const u_char *p, u_int length, u_int caplen)
 u_int
 ipfc_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, register const u_char *p)
 {
-	ipfc_print(ndo, p, h->len, h->caplen);
-
-	return (IPFC_HDRLEN);
+	return (ipfc_print(ndo, p, h->len, h->caplen));
 }