]> The Tcpdump Group git mirrors - tcpdump/blobdiff - print-lwres.c
gre: add support for MikroTik Ethernet-over-IP hack.
[tcpdump] / print-lwres.c
index d253da9d96c3b3e7582d42a21da66ea4fe9e9eb3..b8f9b49ae598c3b410de1bfa31032b0b5f54310b 100644 (file)
  * SUCH DAMAGE.
  */
 
-#define NETDISSECT_REWORKED
+/* \summary: BIND9 Lightweight Resolver protocol printer */
+
 #ifdef HAVE_CONFIG_H
-#include "config.h"
+#include <config.h>
 #endif
 
-#include <tcpdump-stdinc.h>
-
-#include "nameser.h"
+#include "netdissect-stdinc.h"
 
-#include <stdio.h>
-#include <string.h>
-
-#include "interface.h"
+#define ND_LONGJMP_FROM_TCHECK
+#include "netdissect.h"
 #include "addrtoname.h"
-#include "extract.h"                    /* must come after interface.h */
+#include "extract.h"
+
+#include "nameser.h"
 
 /* BIND9 lib/lwres/include/lwres */
-typedef u_int32_t lwres_uint32_t;
-typedef u_int16_t lwres_uint16_t;
-typedef u_int8_t lwres_uint8_t;
+/*
+ * Use nd_uint16_t for lwres_uint16_t
+ * Use nd_uint32_t for lwres_uint32_t
+*/
 
 struct lwres_lwpacket {
-       lwres_uint32_t          length;
-       lwres_uint16_t          version;
-       lwres_uint16_t          pktflags;
-       lwres_uint32_t          serial;
-       lwres_uint32_t          opcode;
-       lwres_uint32_t          result;
-       lwres_uint32_t          recvlength;
-       lwres_uint16_t          authtype;
-       lwres_uint16_t          authlength;
+       nd_uint32_t             length;
+       nd_uint16_t             version;
+       nd_uint16_t             pktflags;
+       nd_uint32_t             serial;
+       nd_uint32_t             opcode;
+       nd_uint32_t             result;
+       nd_uint32_t             recvlength;
+       nd_uint16_t             authtype;
+       nd_uint16_t             authlength;
 };
 
 #define LWRES_LWPACKETFLAG_RESPONSE    0x0001U /* if set, pkt is a response */
@@ -74,13 +74,13 @@ struct lwres_lwpacket {
 
 typedef struct {
        /* public */
-       lwres_uint16_t                  datalength;
+       nd_uint16_t                     datalength;
        /* data follows */
 } lwres_nooprequest_t;
 
 typedef struct {
        /* public */
-       lwres_uint16_t                  datalength;
+       nd_uint16_t                     datalength;
        /* data follows */
 } lwres_noopresponse_t;
 
@@ -92,29 +92,32 @@ typedef struct {
 typedef struct lwres_addr lwres_addr_t;
 
 struct lwres_addr {
-       lwres_uint32_t                  family;
-       lwres_uint16_t                  length;
-       /* address folows */
+       nd_uint32_t                     family;
+       nd_uint16_t                     length;
+       /* address follows */
 };
+#define LWRES_ADDR_LEN                 6
 
 typedef struct {
        /* public */
-       lwres_uint32_t                  flags;
-       lwres_uint32_t                  addrtypes;
-       lwres_uint16_t                  namelen;
+       nd_uint32_t                     flags;
+       nd_uint32_t                     addrtypes;
+       nd_uint16_t                     namelen;
        /* name follows */
 } lwres_gabnrequest_t;
+#define LWRES_GABNREQUEST_LEN          10
 
 typedef struct {
        /* public */
-       lwres_uint32_t                  flags;
-       lwres_uint16_t                  naliases;
-       lwres_uint16_t                  naddrs;
-       lwres_uint16_t                  realnamelen;
+       nd_uint32_t                     flags;
+       nd_uint16_t                     naliases;
+       nd_uint16_t                     naddrs;
+       nd_uint16_t                     realnamelen;
        /* aliases follows */
        /* addrs follows */
        /* realname follows */
 } lwres_gabnresponse_t;
+#define LWRES_GABNRESPONSE_LEN         10
 
 /*
  * get name by address
@@ -122,19 +125,20 @@ typedef struct {
 #define LWRES_OPCODE_GETNAMEBYADDR     0x00010002U
 typedef struct {
        /* public */
-       lwres_uint32_t                  flags;
-       lwres_addr_t                    addr;
-       /* addr body follows */
+       nd_uint32_t                     flags;
+       /* addr follows */
 } lwres_gnbarequest_t;
+#define LWRES_GNBAREQUEST_LEN          4
 
 typedef struct {
        /* public */
-       lwres_uint32_t                  flags;
-       lwres_uint16_t                  naliases;
-       lwres_uint16_t                  realnamelen;
+       nd_uint32_t                     flags;
+       nd_uint16_t                     naliases;
+       nd_uint16_t                     realnamelen;
        /* aliases follows */
        /* realname follows */
 } lwres_gnbaresponse_t;
+#define LWRES_GNBARESPONSE_LEN         8
 
 /*
  * get rdata by name
@@ -143,25 +147,27 @@ typedef struct {
 
 typedef struct {
        /* public */
-       lwres_uint32_t                  flags;
-       lwres_uint16_t                  rdclass;
-       lwres_uint16_t                  rdtype;
-       lwres_uint16_t                  namelen;
+       nd_uint32_t                     flags;
+       nd_uint16_t                     rdclass;
+       nd_uint16_t                     rdtype;
+       nd_uint16_t                     namelen;
        /* name follows */
 } lwres_grbnrequest_t;
+#define LWRES_GRBNREQUEST_LEN          10
 
 typedef struct {
        /* public */
-       lwres_uint32_t                  flags;
-       lwres_uint16_t                  rdclass;
-       lwres_uint16_t                  rdtype;
-       lwres_uint32_t                  ttl;
-       lwres_uint16_t                  nrdatas;
-       lwres_uint16_t                  nsigs;
+       nd_uint32_t                     flags;
+       nd_uint16_t                     rdclass;
+       nd_uint16_t                     rdtype;
+       nd_uint32_t                     ttl;
+       nd_uint16_t                     nrdatas;
+       nd_uint16_t                     nsigs;
        /* realname here (len + name) */
        /* rdata here (len + name) */
        /* signatures here (len + name) */
 } lwres_grbnresponse_t;
+#define LWRES_GRBNRESPONSE_LEN         16
 
 #define LWRDATA_VALIDATED      0x00000001
 
@@ -176,166 +182,144 @@ static const struct tok opcode[] = {
        { LWRES_OPCODE_GETADDRSBYNAME,  "getaddrsbyname", },
        { LWRES_OPCODE_GETNAMEBYADDR,   "getnamebyaddr", },
        { LWRES_OPCODE_GETRDATABYNAME,  "getrdatabyname", },
-       { 0,                            NULL, },
+       { 0,                            NULL, },
 };
 
 /* print-domain.c */
 extern const struct tok ns_type2str[];
 extern const struct tok ns_class2str[];
 
-static int
+static unsigned
 lwres_printname(netdissect_options *ndo,
-                size_t l, const char *p0)
+                u_int l, const u_char *p0)
 {
-       const char *p;
-       size_t i;
-
-       p = p0;
-       /* + 1 for terminating \0 */
-       if (p + l + 1 > (const char *)ndo->ndo_snapend)
-               goto trunc;
-
-       ND_PRINT((ndo, " "));
-       for (i = 0; i < l; i++)
-               safeputchar(ndo, *p++);
-       p++;    /* skip terminating \0 */
-
-       return p - p0;
-
-  trunc:
-       return -1;
+       ND_PRINT(" ");
+       nd_printjn(ndo, p0, l);
+       p0 += l;
+       if (GET_U_1(p0))
+               ND_PRINT(" (not NUL-terminated!)");
+       return l + 1;
 }
 
-static int
+static unsigned
 lwres_printnamelen(netdissect_options *ndo,
-                   const char *p)
+                   const u_char *p)
 {
-       u_int16_t l;
+       uint16_t l;
        int advance;
 
-       if (p + 2 > (const char *)ndo->ndo_snapend)
-               goto trunc;
-       l = EXTRACT_16BITS(p);
+       l = GET_BE_U_2(p);
        advance = lwres_printname(ndo, l, p + 2);
-       if (advance < 0)
-               goto trunc;
        return 2 + advance;
-
-  trunc:
-       return -1;
 }
 
-static int
+static unsigned
 lwres_printbinlen(netdissect_options *ndo,
-                  const char *p0)
+                  const u_char *p0)
 {
-       const char *p;
-       u_int16_t l;
+       const u_char *p;
+       uint16_t l;
        int i;
 
        p = p0;
-       if (p + 2 > (const char *)ndo->ndo_snapend)
-               goto trunc;
-       l = EXTRACT_16BITS(p);
-       if (p + 2 + l > (const char *)ndo->ndo_snapend)
-               goto trunc;
+       l = GET_BE_U_2(p);
        p += 2;
-       for (i = 0; i < l; i++)
-               ND_PRINT((ndo, "%02x", *p++));
-       return p - p0;
-
-  trunc:
-       return -1;
+       for (i = 0; i < l; i++) {
+               ND_PRINT("%02x", GET_U_1(p));
+               p++;
+       }
+       return 2 + l;
 }
 
 static int
 lwres_printaddr(netdissect_options *ndo,
-                lwres_addr_t *ap)
+                const u_char *p0)
 {
-       u_int16_t l;
-       const char *p;
+       const u_char *p;
+       const lwres_addr_t *ap;
+       uint16_t l;
        int i;
 
-       ND_TCHECK(ap->length);
-       l = EXTRACT_16BITS(&ap->length);
-       /* XXX ap points to packed struct */
-       p = (const char *)&ap->length + sizeof(ap->length);
-       ND_TCHECK2(*p, l);
+       p = p0;
+       ap = (const lwres_addr_t *)p;
+       l = GET_BE_U_2(ap->length);
+       p += LWRES_ADDR_LEN;
+       ND_TCHECK_LEN(p, l);
 
-       switch (EXTRACT_32BITS(&ap->family)) {
+       switch (GET_BE_U_4(ap->family)) {
        case 1: /* IPv4 */
                if (l < 4)
                        return -1;
-               ND_PRINT((ndo, " %s", ipaddr_string(p)));
-               p += sizeof(struct in_addr);
+               ND_PRINT(" %s", GET_IPADDR_STRING(p));
+               p += sizeof(nd_ipv4);
                break;
-#ifdef INET6
        case 2: /* IPv6 */
                if (l < 16)
                        return -1;
-               ND_PRINT((ndo, " %s", ip6addr_string(p)));
-               p += sizeof(struct in6_addr);
+               ND_PRINT(" %s", GET_IP6ADDR_STRING(p));
+               p += sizeof(nd_ipv6);
                break;
-#endif
        default:
-               ND_PRINT((ndo, " %u/", EXTRACT_32BITS(&ap->family)));
-               for (i = 0; i < l; i++)
-                       ND_PRINT((ndo, "%02x", *p++));
+               ND_PRINT(" %u/", GET_BE_U_4(ap->family));
+               for (i = 0; i < l; i++) {
+                       ND_PRINT("%02x", GET_U_1(p));
+                       p++;
+               }
        }
 
-       return p - (const char *)ap;
-
-  trunc:
-       return -1;
+       return ND_BYTES_BETWEEN(p, p0);
 }
 
 void
 lwres_print(netdissect_options *ndo,
-            register const u_char *bp, u_int length)
+            const u_char *bp, u_int length)
 {
+       const u_char *p;
        const struct lwres_lwpacket *np;
-       u_int32_t v;
-       const char *s;
+       uint32_t v;
+       const u_char *s;
        int response;
        int advance;
        int unsupported = 0;
 
+       ndo->ndo_protocol = "lwres";
        np = (const struct lwres_lwpacket *)bp;
-       ND_TCHECK(np->authlength);
+       ND_TCHECK_2(np->authlength);
 
-       ND_PRINT((ndo, " lwres"));
-       v = EXTRACT_16BITS(&np->version);
+       ND_PRINT(" lwres");
+       v = GET_BE_U_2(np->version);
        if (ndo->ndo_vflag || v != LWRES_LWPACKETVERSION_0)
-               ND_PRINT((ndo, " v%u", v));
+               ND_PRINT(" v%u", v);
        if (v != LWRES_LWPACKETVERSION_0) {
-               s = (const char *)np + EXTRACT_32BITS(&np->length);
+               uint32_t pkt_len = GET_BE_U_4(np->length);
+               ND_TCHECK_LEN(bp, pkt_len);
+               s = bp + pkt_len;
                goto tail;
        }
 
-       response = EXTRACT_16BITS(&np->pktflags) & LWRES_LWPACKETFLAG_RESPONSE;
+       response = GET_BE_U_2(np->pktflags) & LWRES_LWPACKETFLAG_RESPONSE;
 
        /* opcode and pktflags */
-       v = EXTRACT_32BITS(&np->opcode);
-       s = tok2str(opcode, "#0x%x", v);
-       ND_PRINT((ndo, " %s%s", s, response ? "" : "?"));
+       v = GET_BE_U_4(np->opcode);
+       ND_PRINT(" %s%s", tok2str(opcode, "#0x%x", v), response ? "" : "?");
 
        /* pktflags */
-       v = EXTRACT_16BITS(&np->pktflags);
+       v = GET_BE_U_2(np->pktflags);
        if (v & ~LWRES_LWPACKETFLAG_RESPONSE)
-               ND_PRINT((ndo, "[0x%x]", v));
+               ND_PRINT("[0x%x]", v);
 
        if (ndo->ndo_vflag > 1) {
-               ND_PRINT((ndo, " ("));  /*)*/
-               ND_PRINT((ndo, "serial:0x%x", EXTRACT_32BITS(&np->serial)));
-               ND_PRINT((ndo, " result:0x%x", EXTRACT_32BITS(&np->result)));
-               ND_PRINT((ndo, " recvlen:%u", EXTRACT_32BITS(&np->recvlength)));
+               ND_PRINT(" ("); /*)*/
+               ND_PRINT("serial:0x%x", GET_BE_U_4(np->serial));
+               ND_PRINT(" result:0x%x", GET_BE_U_4(np->result));
+               ND_PRINT(" recvlen:%u", GET_BE_U_4(np->recvlength));
                /* BIND910: not used */
                if (ndo->ndo_vflag > 2) {
-                       ND_PRINT((ndo, " authtype:0x%x", EXTRACT_16BITS(&np->authtype)));
-                       ND_PRINT((ndo, " authlen:%u", EXTRACT_16BITS(&np->authlength)));
+                       ND_PRINT(" authtype:0x%x", GET_BE_U_2(np->authtype));
+                       ND_PRINT(" authlen:%u", GET_BE_U_2(np->authlength));
                }
                /*(*/
-               ND_PRINT((ndo, ")"));
+               ND_PRINT(")");
        }
 
        /* per-opcode content */
@@ -343,98 +327,91 @@ lwres_print(netdissect_options *ndo,
                /*
                 * queries
                 */
-               lwres_gabnrequest_t *gabn;
-               lwres_gnbarequest_t *gnba;
-               lwres_grbnrequest_t *grbn;
-               u_int32_t l;
+               const lwres_gabnrequest_t *gabn;
+               const lwres_gnbarequest_t *gnba;
+               const lwres_grbnrequest_t *grbn;
+               uint32_t l;
 
                gabn = NULL;
                gnba = NULL;
                grbn = NULL;
 
-               switch (EXTRACT_32BITS(&np->opcode)) {
+               p = (const u_char *)(np + 1);
+               switch (GET_BE_U_4(np->opcode)) {
                case LWRES_OPCODE_NOOP:
+                       s = p;
                        break;
                case LWRES_OPCODE_GETADDRSBYNAME:
-                       gabn = (lwres_gabnrequest_t *)(np + 1);
-                       ND_TCHECK(gabn->namelen);
-                       /* XXX gabn points to packed struct */
-                       s = (const char *)&gabn->namelen +
-                           sizeof(gabn->namelen);
-                       l = EXTRACT_16BITS(&gabn->namelen);
+                       gabn = (const lwres_gabnrequest_t *)p;
+                       ND_TCHECK_2(gabn->namelen);
 
                        /* BIND910: not used */
                        if (ndo->ndo_vflag > 2) {
-                               ND_PRINT((ndo, " flags:0x%x",
-                                   EXTRACT_32BITS(&gabn->flags)));
+                               ND_PRINT(" flags:0x%x",
+                                   GET_BE_U_4(gabn->flags));
                        }
 
-                       v = EXTRACT_32BITS(&gabn->addrtypes);
+                       v = GET_BE_U_4(gabn->addrtypes);
                        switch (v & (LWRES_ADDRTYPE_V4 | LWRES_ADDRTYPE_V6)) {
                        case LWRES_ADDRTYPE_V4:
-                               ND_PRINT((ndo, " IPv4"));
+                               ND_PRINT(" IPv4");
                                break;
                        case LWRES_ADDRTYPE_V6:
-                               ND_PRINT((ndo, " IPv6"));
+                               ND_PRINT(" IPv6");
                                break;
                        case LWRES_ADDRTYPE_V4 | LWRES_ADDRTYPE_V6:
-                               ND_PRINT((ndo, " IPv4/6"));
+                               ND_PRINT(" IPv4/6");
                                break;
                        }
                        if (v & ~(LWRES_ADDRTYPE_V4 | LWRES_ADDRTYPE_V6))
-                               ND_PRINT((ndo, "[0x%x]", v));
+                               ND_PRINT("[0x%x]", v);
 
+                       s = p + LWRES_GABNREQUEST_LEN;
+                       l = GET_BE_U_2(gabn->namelen);
                        advance = lwres_printname(ndo, l, s);
-                       if (advance < 0)
-                               goto trunc;
                        s += advance;
                        break;
                case LWRES_OPCODE_GETNAMEBYADDR:
-                       gnba = (lwres_gnbarequest_t *)(np + 1);
-                       ND_TCHECK(gnba->addr);
+                       gnba = (const lwres_gnbarequest_t *)p;
+                       ND_TCHECK_4(gnba->flags);
 
                        /* BIND910: not used */
                        if (ndo->ndo_vflag > 2) {
-                               ND_PRINT((ndo, " flags:0x%x",
-                                   EXTRACT_32BITS(&gnba->flags)));
+                               ND_PRINT(" flags:0x%x",
+                                   GET_BE_U_4(gnba->flags));
                        }
 
-                       s = (const char *)&gnba->addr;
-
-                       advance = lwres_printaddr(ndo, &gnba->addr);
+                       s = p + LWRES_GNBAREQUEST_LEN;
+                       advance = lwres_printaddr(ndo, s);
                        if (advance < 0)
-                               goto trunc;
+                               goto invalid;
                        s += advance;
                        break;
                case LWRES_OPCODE_GETRDATABYNAME:
                        /* XXX no trace, not tested */
-                       grbn = (lwres_grbnrequest_t *)(np + 1);
-                       ND_TCHECK(grbn->namelen);
+                       grbn = (const lwres_grbnrequest_t *)p;
+                       ND_TCHECK_2(grbn->namelen);
 
                        /* BIND910: not used */
                        if (ndo->ndo_vflag > 2) {
-                               ND_PRINT((ndo, " flags:0x%x",
-                                   EXTRACT_32BITS(&grbn->flags)));
+                               ND_PRINT(" flags:0x%x",
+                                   GET_BE_U_4(grbn->flags));
                        }
 
-                       ND_PRINT((ndo, " %s", tok2str(ns_type2str, "Type%d",
-                           EXTRACT_16BITS(&grbn->rdtype))));
-                       if (EXTRACT_16BITS(&grbn->rdclass) != C_IN) {
-                               ND_PRINT((ndo, " %s", tok2str(ns_class2str, "Class%d",
-                                   EXTRACT_16BITS(&grbn->rdclass))));
+                       ND_PRINT(" %s", tok2str(ns_type2str, "Type%u",
+                           GET_BE_U_2(grbn->rdtype)));
+                       if (GET_BE_U_2(grbn->rdclass) != C_IN) {
+                               ND_PRINT(" %s", tok2str(ns_class2str, "Class%u",
+                                   GET_BE_U_2(grbn->rdclass)));
                        }
 
-                       /* XXX grbn points to packed struct */
-                       s = (const char *)&grbn->namelen +
-                           sizeof(grbn->namelen);
-                       l = EXTRACT_16BITS(&grbn->namelen);
-
+                       s = p + LWRES_GRBNREQUEST_LEN;
+                       l = GET_BE_U_2(grbn->namelen);
                        advance = lwres_printname(ndo, l, s);
-                       if (advance < 0)
-                               goto trunc;
                        s += advance;
                        break;
                default:
+                       s = p;
                        unsupported++;
                        break;
                }
@@ -442,140 +419,124 @@ lwres_print(netdissect_options *ndo,
                /*
                 * responses
                 */
-               lwres_gabnresponse_t *gabn;
-               lwres_gnbaresponse_t *gnba;
-               lwres_grbnresponse_t *grbn;
-               u_int32_t l, na;
-               u_int32_t i;
+               const lwres_gabnresponse_t *gabn;
+               const lwres_gnbaresponse_t *gnba;
+               const lwres_grbnresponse_t *grbn;
+               uint32_t l, na;
+               uint32_t i;
 
                gabn = NULL;
                gnba = NULL;
                grbn = NULL;
 
-               switch (EXTRACT_32BITS(&np->opcode)) {
+               p = (const u_char *)(np + 1);
+               switch (GET_BE_U_4(np->opcode)) {
                case LWRES_OPCODE_NOOP:
+                       s = p;
                        break;
                case LWRES_OPCODE_GETADDRSBYNAME:
-                       gabn = (lwres_gabnresponse_t *)(np + 1);
-                       ND_TCHECK(gabn->realnamelen);
-                       /* XXX gabn points to packed struct */
-                       s = (const char *)&gabn->realnamelen +
-                           sizeof(gabn->realnamelen);
-                       l = EXTRACT_16BITS(&gabn->realnamelen);
+                       gabn = (const lwres_gabnresponse_t *)p;
+                       ND_TCHECK_2(gabn->realnamelen);
 
                        /* BIND910: not used */
                        if (ndo->ndo_vflag > 2) {
-                               ND_PRINT((ndo, " flags:0x%x",
-                                   EXTRACT_32BITS(&gabn->flags)));
+                               ND_PRINT(" flags:0x%x",
+                                   GET_BE_U_4(gabn->flags));
                        }
 
-                       ND_PRINT((ndo, " %u/%u", EXTRACT_16BITS(&gabn->naliases),
-                           EXTRACT_16BITS(&gabn->naddrs)));
+                       ND_PRINT(" %u/%u", GET_BE_U_2(gabn->naliases),
+                                 GET_BE_U_2(gabn->naddrs));
 
+                       s = p + LWRES_GABNRESPONSE_LEN;
+                       l = GET_BE_U_2(gabn->realnamelen);
                        advance = lwres_printname(ndo, l, s);
-                       if (advance < 0)
-                               goto trunc;
                        s += advance;
 
                        /* aliases */
-                       na = EXTRACT_16BITS(&gabn->naliases);
+                       na = GET_BE_U_2(gabn->naliases);
                        for (i = 0; i < na; i++) {
                                advance = lwres_printnamelen(ndo, s);
-                               if (advance < 0)
-                                       goto trunc;
                                s += advance;
                        }
 
                        /* addrs */
-                       na = EXTRACT_16BITS(&gabn->naddrs);
+                       na = GET_BE_U_2(gabn->naddrs);
                        for (i = 0; i < na; i++) {
-                               advance = lwres_printaddr(ndo, (lwres_addr_t *)s);
+                               advance = lwres_printaddr(ndo, s);
                                if (advance < 0)
-                                       goto trunc;
+                                       goto invalid;
                                s += advance;
                        }
                        break;
                case LWRES_OPCODE_GETNAMEBYADDR:
-                       gnba = (lwres_gnbaresponse_t *)(np + 1);
-                       ND_TCHECK(gnba->realnamelen);
-                       /* XXX gnba points to packed struct */
-                       s = (const char *)&gnba->realnamelen +
-                           sizeof(gnba->realnamelen);
-                       l = EXTRACT_16BITS(&gnba->realnamelen);
+                       gnba = (const lwres_gnbaresponse_t *)p;
+                       ND_TCHECK_2(gnba->realnamelen);
 
                        /* BIND910: not used */
                        if (ndo->ndo_vflag > 2) {
-                               ND_PRINT((ndo, " flags:0x%x",
-                                   EXTRACT_32BITS(&gnba->flags)));
+                               ND_PRINT(" flags:0x%x",
+                                   GET_BE_U_4(gnba->flags));
                        }
 
-                       ND_PRINT((ndo, " %u", EXTRACT_16BITS(&gnba->naliases)));
+                       ND_PRINT(" %u", GET_BE_U_2(gnba->naliases));
 
+                       s = p + LWRES_GNBARESPONSE_LEN;
+                       l = GET_BE_U_2(gnba->realnamelen);
                        advance = lwres_printname(ndo, l, s);
-                       if (advance < 0)
-                               goto trunc;
                        s += advance;
 
                        /* aliases */
-                       na = EXTRACT_16BITS(&gnba->naliases);
+                       na = GET_BE_U_2(gnba->naliases);
                        for (i = 0; i < na; i++) {
                                advance = lwres_printnamelen(ndo, s);
-                               if (advance < 0)
-                                       goto trunc;
                                s += advance;
                        }
                        break;
                case LWRES_OPCODE_GETRDATABYNAME:
                        /* XXX no trace, not tested */
-                       grbn = (lwres_grbnresponse_t *)(np + 1);
-                       ND_TCHECK(grbn->nsigs);
+                       grbn = (const lwres_grbnresponse_t *)p;
+                       ND_TCHECK_2(grbn->nsigs);
 
                        /* BIND910: not used */
                        if (ndo->ndo_vflag > 2) {
-                               ND_PRINT((ndo, " flags:0x%x",
-                                   EXTRACT_32BITS(&grbn->flags)));
+                               ND_PRINT(" flags:0x%x",
+                                   GET_BE_U_4(grbn->flags));
                        }
 
-                       ND_PRINT((ndo, " %s", tok2str(ns_type2str, "Type%d",
-                           EXTRACT_16BITS(&grbn->rdtype))));
-                       if (EXTRACT_16BITS(&grbn->rdclass) != C_IN) {
-                               ND_PRINT((ndo, " %s", tok2str(ns_class2str, "Class%d",
-                                   EXTRACT_16BITS(&grbn->rdclass))));
+                       ND_PRINT(" %s", tok2str(ns_type2str, "Type%u",
+                           GET_BE_U_2(grbn->rdtype)));
+                       if (GET_BE_U_2(grbn->rdclass) != C_IN) {
+                               ND_PRINT(" %s", tok2str(ns_class2str, "Class%u",
+                                   GET_BE_U_2(grbn->rdclass)));
                        }
-                       ND_PRINT((ndo, " TTL "));
-                       relts_print(EXTRACT_32BITS(&grbn->ttl));
-                       ND_PRINT((ndo, " %u/%u", EXTRACT_16BITS(&grbn->nrdatas),
-                           EXTRACT_16BITS(&grbn->nsigs)));
-
-                       /* XXX grbn points to packed struct */
-                       s = (const char *)&grbn->nsigs+ sizeof(grbn->nsigs);
+                       ND_PRINT(" TTL ");
+                       unsigned_relts_print(ndo,
+                                            GET_BE_U_4(grbn->ttl));
+                       ND_PRINT(" %u/%u", GET_BE_U_2(grbn->nrdatas),
+                                 GET_BE_U_2(grbn->nsigs));
 
+                       s = p + LWRES_GRBNRESPONSE_LEN;
                        advance = lwres_printnamelen(ndo, s);
-                       if (advance < 0)
-                               goto trunc;
                        s += advance;
 
                        /* rdatas */
-                       na = EXTRACT_16BITS(&grbn->nrdatas);
+                       na = GET_BE_U_2(grbn->nrdatas);
                        for (i = 0; i < na; i++) {
                                /* XXX should decode resource data */
                                advance = lwres_printbinlen(ndo, s);
-                               if (advance < 0)
-                                       goto trunc;
                                s += advance;
                        }
 
                        /* sigs */
-                       na = EXTRACT_16BITS(&grbn->nsigs);
+                       na = GET_BE_U_2(grbn->nsigs);
                        for (i = 0; i < na; i++) {
                                /* XXX how should we print it? */
                                advance = lwres_printbinlen(ndo, s);
-                               if (advance < 0)
-                                       goto trunc;
                                s += advance;
                        }
                        break;
                default:
+                       s = p;
                        unsupported++;
                        break;
                }
@@ -583,14 +544,14 @@ lwres_print(netdissect_options *ndo,
 
   tail:
        /* length mismatch */
-       if (EXTRACT_32BITS(&np->length) != length) {
-               ND_PRINT((ndo, " [len: %u != %u]", EXTRACT_32BITS(&np->length),
-                   length));
+       if (GET_BE_U_4(np->length) != length) {
+               ND_PRINT(" [len: %u != %u]", GET_BE_U_4(np->length),
+                         length);
        }
-       if (!unsupported && s < (const char *)np + EXTRACT_32BITS(&np->length))
-               ND_PRINT((ndo, "[extra]"));
+       if (!unsupported && ND_BYTES_BETWEEN(s, bp) < GET_BE_U_4(np->length))
+               ND_PRINT("[extra]");
        return;
 
-  trunc:
-       ND_PRINT((ndo, "[|lwres]"));
+  invalid:
+       nd_print_invalid(ndo);
 }