WB: Modernize packet parsing style.

Enable ND_LONGJMP_FROM_TCHECK. Remove ND_TTEST*() instances that were
excess and convert the rest to ND_TCHECK*() with comments. Do not guard
ndo_snapend directly. Make sure that functions specific to message types
do not return on truncated data and return -1 when they have looked deep
enough to tell an invalid packet. In wb_print() deduplicate some code and
report invalid packets as invalid instead of truncated, also consider an
unknown packet type invalid. Update a test.

1 files changed, 38 insertions, 45 deletions

diff --git a/print-wb.c b/print-wb.c
index 3e562af4..184809cb 100644
--- a/print-wb.c
+++ b/print-wb.c
@@ -27,6 +27,7 @@
 
 #include "netdissect-stdinc.h"
 
+#define ND_LONGJMP_FROM_TCHECK
 #include "netdissect.h"
 #include "addrtoname.h"
 #include "extract.h"
@@ -203,7 +204,7 @@ wb_id(netdissect_options *ndo,
 	u_int nid;
 
 	ND_PRINT(" wb-id:");
-	if (len < sizeof(*id) || !ND_TTEST_SIZE(id))
+	if (len < sizeof(*id))
 		return (-1);
 	len -= sizeof(*id);
 
@@ -214,6 +215,8 @@ wb_id(netdissect_options *ndo,
 	       GET_BE_U_4(id->pi_mslot),
 	       GET_IPADDR_STRING(id->pi_mpage.p_sid),
 	       GET_BE_U_4(id->pi_mpage.p_uid));
+	/* now the rest of the fixed-size part of struct pkt_id */
+	ND_TCHECK_SIZE(id);
 
 	nid = GET_BE_U_2(id->pi_ps.nid);
 	if (len < sizeof(*io) * nid)
@@ -223,18 +226,15 @@ wb_id(netdissect_options *ndo,
 	sitename = (const u_char *)(io + nid);
 
 	c = '<';
-	for (i = 0; i < nid && ND_TTEST_SIZE(io); ++io, ++i) {
+	for (i = 0; i < nid; ++io, ++i) {
 		ND_PRINT("%c%s:%u",
 		    c, GET_IPADDR_STRING(io->id), GET_BE_U_4(io->off));
 		c = ',';
 	}
-	if (i >= nid) {
-		ND_PRINT("> \"");
-		(void)nd_print(ndo, sitename, sitename + len);
-		ND_PRINT("\"");
-		return (0);
-	}
-	return (-1);
+	ND_PRINT("> \"");
+	(void)nd_print(ndo, sitename, sitename + len);
+	ND_PRINT("\"");
+	return (0);
 }
 
 static int
@@ -242,7 +242,7 @@ wb_rreq(netdissect_options *ndo,
         const struct pkt_rreq *rreq, u_int len)
 {
 	ND_PRINT(" wb-rreq:");
-	if (len < sizeof(*rreq) || !ND_TTEST_SIZE(rreq))
+	if (len < sizeof(*rreq))
 		return (-1);
 
 	ND_PRINT(" please repair %s %s:%u<%u:%u>",
@@ -259,13 +259,15 @@ wb_preq(netdissect_options *ndo,
         const struct pkt_preq *preq, u_int len)
 {
 	ND_PRINT(" wb-preq:");
-	if (len < sizeof(*preq) || !ND_TTEST_SIZE(preq))
+	if (len < sizeof(*preq))
 		return (-1);
 
 	ND_PRINT(" need %u/%s:%u",
 	       GET_BE_U_4(preq->pp_low),
 	       GET_IPADDR_STRING(preq->pp_page.p_sid),
 	       GET_BE_U_4(preq->pp_page.p_uid));
+	/* now the rest of the fixed-size part of struct pkt_req */
+	ND_TCHECK_SIZE(preq);
 	return (0);
 }
 
@@ -275,14 +277,13 @@ wb_prep(netdissect_options *ndo,
 {
 	u_int n;
 	const struct pgstate *ps;
-	const u_char *ep = ndo->ndo_snapend;
 
 	ND_PRINT(" wb-prep:");
-	if (len < sizeof(*prep) || !ND_TTEST_SIZE(prep))
+	if (len < sizeof(*prep))
 		return (-1);
 	n = GET_BE_U_4(prep->pp_n);
 	ps = (const struct pgstate *)(prep + 1);
-	while (n != 0 && ND_TTEST_SIZE(ps)) {
+	while (n != 0) {
 		const struct id_off *io, *ie;
 		char c = '<';
 
@@ -290,8 +291,10 @@ wb_prep(netdissect_options *ndo,
 		    GET_BE_U_4(ps->slot),
 		    GET_IPADDR_STRING(ps->page.p_sid),
 		    GET_BE_U_4(ps->page.p_uid));
+		/* now the rest of the fixed-size part of struct pgstate */
+		ND_TCHECK_SIZE(ps);
 		io = (const struct id_off *)(ps + 1);
-		for (ie = io + GET_U_1(ps->nid); io < ie && ND_TTEST_SIZE(io); ++io) {
+		for (ie = io + GET_U_1(ps->nid); io < ie; ++io) {
 			ND_PRINT("%c%s:%u", c, GET_IPADDR_STRING(io->id),
 			    GET_BE_U_4(io->off));
 			c = ',';
@@ -300,7 +303,7 @@ wb_prep(netdissect_options *ndo,
 		ps = (const struct pgstate *)io;
 		n--;
 	}
-	return ((const u_char *)ps <= ep? 0 : -1);
+	return 0;
 }
 
 static void
@@ -313,10 +316,6 @@ wb_dops(netdissect_options *ndo, const struct pkt_dop *dop,
 	for ( ; ss <= es; ++ss) {
 		u_int t;
 
-		if (!ND_TTEST_SIZE(dh)) {
-			nd_print_trunc(ndo);
-			break;
-		}
 		t = GET_U_1(dh->dh_type);
 
 		ND_PRINT(" %s", tok2str(dop_str, "dop-%u!", t));
@@ -342,7 +341,7 @@ wb_rrep(netdissect_options *ndo,
 	const struct pkt_dop *dop = &rrep->pr_dop;
 
 	ND_PRINT(" wb-rrep:");
-	if (len < sizeof(*rrep) || !ND_TTEST_SIZE(rrep))
+	if (len < sizeof(*rrep))
 		return (-1);
 	len -= sizeof(*rrep);
 
@@ -365,7 +364,7 @@ wb_drawop(netdissect_options *ndo,
           const struct pkt_dop *dop, u_int len)
 {
 	ND_PRINT(" wb-dop:");
-	if (len < sizeof(*dop) || !ND_TTEST_SIZE(dop))
+	if (len < sizeof(*dop))
 		return (-1);
 	len -= sizeof(*dop);
 
@@ -391,13 +390,13 @@ wb_print(netdissect_options *ndo,
 {
 	const struct pkt_hdr *ph;
 	uint8_t type;
+	int print_result;
 
 	ndo->ndo_protocol = "wb";
 	ph = (const struct pkt_hdr *)hdr;
-	if (len < sizeof(*ph) || !ND_TTEST_SIZE(ph)) {
-		nd_print_trunc(ndo);
-		return;
-	}
+	if (len < sizeof(*ph))
+		goto invalid;
+	ND_TCHECK_SIZE(ph);
 	len -= sizeof(*ph);
 
 	if (GET_U_1(ph->ph_flags))
@@ -410,43 +409,37 @@ wb_print(netdissect_options *ndo,
 		return;
 
 	case PT_ID:
-		if (wb_id(ndo, (const struct pkt_id *)(ph + 1), len) >= 0)
-			return;
-		nd_print_trunc(ndo);
+		print_result = wb_id(ndo, (const struct pkt_id *)(ph + 1), len);
 		break;
 
 	case PT_RREQ:
-		if (wb_rreq(ndo, (const struct pkt_rreq *)(ph + 1), len) >= 0)
-			return;
-		nd_print_trunc(ndo);
+		print_result = wb_rreq(ndo, (const struct pkt_rreq *)(ph + 1), len);
 		break;
 
 	case PT_RREP:
-		if (wb_rrep(ndo, (const struct pkt_rrep *)(ph + 1), len) >= 0)
-			return;
-		nd_print_trunc(ndo);
+		print_result = wb_rrep(ndo, (const struct pkt_rrep *)(ph + 1), len);
 		break;
 
 	case PT_DRAWOP:
-		if (wb_drawop(ndo, (const struct pkt_dop *)(ph + 1), len) >= 0)
-			return;
-		nd_print_trunc(ndo);
+		print_result = wb_drawop(ndo, (const struct pkt_dop *)(ph + 1), len);
 		break;
 
 	case PT_PREQ:
-		if (wb_preq(ndo, (const struct pkt_preq *)(ph + 1), len) >= 0)
-			return;
-		nd_print_trunc(ndo);
+		print_result = wb_preq(ndo, (const struct pkt_preq *)(ph + 1), len);
 		break;
 
 	case PT_PREP:
-		if (wb_prep(ndo, (const struct pkt_prep *)(ph + 1), len) >= 0)
-			return;
-		nd_print_trunc(ndo);
+		print_result = wb_prep(ndo, (const struct pkt_prep *)(ph + 1), len);
 		break;
 
 	default:
 		ND_PRINT(" wb-%u!", type);
-		return;
+		print_result = -1;
 	}
+	if (print_result < 0)
+		goto invalid;
+	return;
+
+invalid:
+	nd_print_invalid(ndo);
 }