]> The Tcpdump Group git mirrors - tcpdump/blobdiff - print-isoclns.c
CVE-2017-13040/MPTCP: Clean up printing DSS suboption.
[tcpdump] / print-isoclns.c
index d9a69093d127259bff3e93b9e192881a54e9e1cb..6285502845247c95ac3bb999bb934ccf99a84d2b 100644 (file)
  *
  * Original code by Matt Thomas, Digital Equipment Corporation
  *
- * Extensively modified by Hannes Gredler (hannes@juniper.net) for more
+ * Extensively modified by Hannes Gredler (hannes@gredler.at) for more
  * complete IS-IS & CLNP support.
  */
 
-#define NETDISSECT_REWORKED
+/* \summary: ISO CLNS, ESIS, and ISIS printer */
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
-#include <tcpdump-stdinc.h>
+#include <netdissect-stdinc.h>
 
 #include <string.h>
 
-#include "interface.h"
+#include "netdissect.h"
 #include "addrtoname.h"
 #include "ether.h"
 #include "nlpid.h"
@@ -42,6 +43,8 @@
 #include "oui.h"
 #include "signature.h"
 
+static const char tstr[] = " [|isis]";
+
 /*
  * IS-IS is defined in ISO 10589.  Look there for protocol definitions.
  */
@@ -103,6 +106,7 @@ static const struct tok isis_pdu_values[] = {
 #define ISIS_TLV_AUTH                10  /* iso10589, rfc3567 */
 #define ISIS_TLV_CHECKSUM            12  /* rfc3358 */
 #define ISIS_TLV_CHECKSUM_MINLEN 2
+#define ISIS_TLV_POI                 13  /* rfc6232 */
 #define ISIS_TLV_LSP_BUFFERSIZE      14  /* iso10589 rev2 */
 #define ISIS_TLV_LSP_BUFFERSIZE_MINLEN 2
 #define ISIS_TLV_EXT_IS_REACH        22  /* draft-ietf-isis-traffic-05 */
@@ -152,6 +156,7 @@ static const struct tok isis_tlv_values[] = {
     { ISIS_TLV_LSP,                "LSP entries"},
     { ISIS_TLV_AUTH,               "Authentication"},
     { ISIS_TLV_CHECKSUM,           "Checksum"},
+    { ISIS_TLV_POI,                "Purge Originator Identifier"},
     { ISIS_TLV_LSP_BUFFERSIZE,     "LSP Buffersize"},
     { ISIS_TLV_EXT_IS_REACH,       "Extended IS Reachability"},
     { ISIS_TLV_IS_ALIAS_ID,        "IS Alias ID"},
@@ -446,10 +451,10 @@ static const struct tok isis_mt_capability_subtlv_values[] = {
 };
 
 struct isis_spb_mcid {
-  u_int8_t  format_id;
-  u_int8_t  name[32];
-  u_int8_t  revision_lvl[2];
-  u_int8_t  digest[16];
+  uint8_t  format_id;
+  uint8_t  name[32];
+  uint8_t  revision_lvl[2];
+  uint8_t  digest[16];
 };
 
 struct isis_subtlv_spb_mcid {
@@ -458,11 +463,11 @@ struct isis_subtlv_spb_mcid {
 };
 
 struct isis_subtlv_spb_instance {
-  u_int8_t cist_root_id[8];
-  u_int8_t cist_external_root_path_cost[4];
-  u_int8_t bridge_priority[2];
-  u_int8_t spsourceid[4];
-  u_int8_t no_of_trees;
+  uint8_t cist_root_id[8];
+  uint8_t cist_external_root_path_cost[4];
+  uint8_t bridge_priority[2];
+  uint8_t spsourceid[4];
+  uint8_t no_of_trees;
 };
 
 #define CLNP_SEGMENT_PART  0x80
@@ -553,39 +558,39 @@ static const struct tok isis_ptp_adjancey_values[] = {
 };
 
 struct isis_tlv_ptp_adj {
-    u_int8_t adjacency_state;
-    u_int8_t extd_local_circuit_id[4];
-    u_int8_t neighbor_sysid[SYSTEM_ID_LEN];
-    u_int8_t neighbor_extd_local_circuit_id[4];
+    uint8_t adjacency_state;
+    uint8_t extd_local_circuit_id[4];
+    uint8_t neighbor_sysid[SYSTEM_ID_LEN];
+    uint8_t neighbor_extd_local_circuit_id[4];
 };
 
-static void osi_print_cksum(netdissect_options *, const u_int8_t *pptr, u_int16_t checksum,
-                            u_int checksum_offset, u_int length);
-static int clnp_print(netdissect_options *, const u_int8_t *, u_int);
-static void esis_print(netdissect_options *, const u_int8_t *, u_int);
-static int isis_print(netdissect_options *, const u_int8_t *, u_int);
+static void osi_print_cksum(netdissect_options *, const uint8_t *pptr,
+                           uint16_t checksum, int checksum_offset, u_int length);
+static int clnp_print(netdissect_options *, const uint8_t *, u_int);
+static void esis_print(netdissect_options *, const uint8_t *, u_int);
+static int isis_print(netdissect_options *, const uint8_t *, u_int);
 
 struct isis_metric_block {
-    u_int8_t metric_default;
-    u_int8_t metric_delay;
-    u_int8_t metric_expense;
-    u_int8_t metric_error;
+    uint8_t metric_default;
+    uint8_t metric_delay;
+    uint8_t metric_expense;
+    uint8_t metric_error;
 };
 
 struct isis_tlv_is_reach {
     struct isis_metric_block isis_metric_block;
-    u_int8_t neighbor_nodeid[NODE_ID_LEN];
+    uint8_t neighbor_nodeid[NODE_ID_LEN];
 };
 
 struct isis_tlv_es_reach {
     struct isis_metric_block isis_metric_block;
-    u_int8_t neighbor_sysid[SYSTEM_ID_LEN];
+    uint8_t neighbor_sysid[SYSTEM_ID_LEN];
 };
 
 struct isis_tlv_ip_reach {
     struct isis_metric_block isis_metric_block;
-    u_int8_t prefix[4];
-    u_int8_t mask[4];
+    uint8_t prefix[4];
+    uint8_t mask[4];
 };
 
 static const struct tok isis_is_reach_virtual_values[] = {
@@ -602,59 +607,59 @@ static const struct tok isis_restart_flag_values[] = {
 };
 
 struct isis_common_header {
-    u_int8_t nlpid;
-    u_int8_t fixed_len;
-    u_int8_t version;                  /* Protocol version */
-    u_int8_t id_length;
-    u_int8_t pdu_type;                 /* 3 MSbits are reserved */
-    u_int8_t pdu_version;              /* Packet format version */
-    u_int8_t reserved;
-    u_int8_t max_area;
+    uint8_t nlpid;
+    uint8_t fixed_len;
+    uint8_t version;                   /* Protocol version */
+    uint8_t id_length;
+    uint8_t pdu_type;                  /* 3 MSbits are reserved */
+    uint8_t pdu_version;               /* Packet format version */
+    uint8_t reserved;
+    uint8_t max_area;
 };
 
 struct isis_iih_lan_header {
-    u_int8_t circuit_type;
-    u_int8_t source_id[SYSTEM_ID_LEN];
-    u_int8_t holding_time[2];
-    u_int8_t pdu_len[2];
-    u_int8_t priority;
-    u_int8_t lan_id[NODE_ID_LEN];
+    uint8_t circuit_type;
+    uint8_t source_id[SYSTEM_ID_LEN];
+    uint8_t holding_time[2];
+    uint8_t pdu_len[2];
+    uint8_t priority;
+    uint8_t lan_id[NODE_ID_LEN];
 };
 
 struct isis_iih_ptp_header {
-    u_int8_t circuit_type;
-    u_int8_t source_id[SYSTEM_ID_LEN];
-    u_int8_t holding_time[2];
-    u_int8_t pdu_len[2];
-    u_int8_t circuit_id;
+    uint8_t circuit_type;
+    uint8_t source_id[SYSTEM_ID_LEN];
+    uint8_t holding_time[2];
+    uint8_t pdu_len[2];
+    uint8_t circuit_id;
 };
 
 struct isis_lsp_header {
-    u_int8_t pdu_len[2];
-    u_int8_t remaining_lifetime[2];
-    u_int8_t lsp_id[LSP_ID_LEN];
-    u_int8_t sequence_number[4];
-    u_int8_t checksum[2];
-    u_int8_t typeblock;
+    uint8_t pdu_len[2];
+    uint8_t remaining_lifetime[2];
+    uint8_t lsp_id[LSP_ID_LEN];
+    uint8_t sequence_number[4];
+    uint8_t checksum[2];
+    uint8_t typeblock;
 };
 
 struct isis_csnp_header {
-    u_int8_t pdu_len[2];
-    u_int8_t source_id[NODE_ID_LEN];
-    u_int8_t start_lsp_id[LSP_ID_LEN];
-    u_int8_t end_lsp_id[LSP_ID_LEN];
+    uint8_t pdu_len[2];
+    uint8_t source_id[NODE_ID_LEN];
+    uint8_t start_lsp_id[LSP_ID_LEN];
+    uint8_t end_lsp_id[LSP_ID_LEN];
 };
 
 struct isis_psnp_header {
-    u_int8_t pdu_len[2];
-    u_int8_t source_id[NODE_ID_LEN];
+    uint8_t pdu_len[2];
+    uint8_t source_id[NODE_ID_LEN];
 };
 
 struct isis_tlv_lsp {
-    u_int8_t remaining_lifetime[2];
-    u_int8_t lsp_id[LSP_ID_LEN];
-    u_int8_t sequence_number[4];
-    u_int8_t checksum[2];
+    uint8_t remaining_lifetime[2];
+    uint8_t lsp_id[LSP_ID_LEN];
+    uint8_t sequence_number[4];
+    uint8_t checksum[2];
 };
 
 #define ISIS_COMMON_HEADER_SIZE (sizeof(struct isis_common_header))
@@ -664,10 +669,10 @@ struct isis_tlv_lsp {
 #define ISIS_CSNP_HEADER_SIZE (sizeof(struct isis_csnp_header))
 #define ISIS_PSNP_HEADER_SIZE (sizeof(struct isis_psnp_header))
 
-void isoclns_print(netdissect_options *ndo,
-                   const u_int8_t *p, u_int length, u_int caplen)
+void
+isoclns_print(netdissect_options *ndo, const uint8_t *p, u_int length)
 {
-       if (caplen <= 1) { /* enough bytes on the wire ? */
+       if (!ND_TTEST(*p)) { /* enough bytes on the wire ? */
                ND_PRINT((ndo, "|OSI"));
                return;
        }
@@ -679,7 +684,7 @@ void isoclns_print(netdissect_options *ndo,
 
        case NLPID_CLNP:
                if (!clnp_print(ndo, p, length))
-                       print_unknown_data(ndo, p, "\n\t", caplen);
+                       print_unknown_data(ndo, p, "\n\t", length);
                break;
 
        case NLPID_ESIS:
@@ -688,7 +693,7 @@ void isoclns_print(netdissect_options *ndo,
 
        case NLPID_ISIS:
                if (!isis_print(ndo, p, length))
-                       print_unknown_data(ndo, p, "\n\t", caplen);
+                       print_unknown_data(ndo, p, "\n\t", length);
                break;
 
        case NLPID_NULLNS:
@@ -703,11 +708,9 @@ void isoclns_print(netdissect_options *ndo,
                ip_print(ndo, p + 1, length - 1);
                break;
 
-#ifdef INET6
        case NLPID_IP6:
                ip6_print(ndo, p + 1, length - 1);
                break;
-#endif
 
        case NLPID_PPP:
                ppp_print(ndo, p + 1, length - 1);
@@ -717,8 +720,8 @@ void isoclns_print(netdissect_options *ndo,
                if (!ndo->ndo_eflag)
                        ND_PRINT((ndo, "OSI NLPID 0x%02x unknown", *p));
                ND_PRINT((ndo, "%slength: %u", ndo->ndo_eflag ? "" : ", ", length));
-               if (caplen > 1)
-                       print_unknown_data(ndo, p, "\n\t", caplen);
+               if (length > 1)
+                       print_unknown_data(ndo, p, "\n\t", length);
                break;
        }
 }
@@ -739,19 +742,19 @@ static const struct tok clnp_pdu_values[] = {
 };
 
 struct clnp_header_t {
-    u_int8_t nlpid;
-    u_int8_t length_indicator;
-    u_int8_t version;
-    u_int8_t lifetime; /* units of 500ms */
-    u_int8_t type;
-    u_int8_t segment_length[2];
-    u_int8_t cksum[2];
+    uint8_t nlpid;
+    uint8_t length_indicator;
+    uint8_t version;
+    uint8_t lifetime; /* units of 500ms */
+    uint8_t type;
+    uint8_t segment_length[2];
+    uint8_t cksum[2];
 };
 
 struct clnp_segment_header_t {
-    u_int8_t data_unit_id[2];
-    u_int8_t segment_offset[2];
-    u_int8_t total_length[2];
+    uint8_t data_unit_id[2];
+    uint8_t segment_offset[2];
+    uint8_t total_length[2];
 };
 
 /*
@@ -761,13 +764,13 @@ struct clnp_segment_header_t {
 
 static int
 clnp_print(netdissect_options *ndo,
-           const u_int8_t *pptr, u_int length)
+           const uint8_t *pptr, u_int length)
 {
-       const u_int8_t *optr,*source_address,*dest_address;
+       const uint8_t *optr,*source_address,*dest_address;
         u_int li,tlen,nsap_offset,source_address_length,dest_address_length, clnp_pdu_type, clnp_flags;
        const struct clnp_header_t *clnp_header;
        const struct clnp_segment_header_t *clnp_segment_header;
-        u_int8_t rfd_error_major,rfd_error_minor;
+        uint8_t rfd_error_major,rfd_error_minor;
 
        clnp_header = (const struct clnp_header_t *) pptr;
         ND_TCHECK(*clnp_header);
@@ -787,6 +790,18 @@ clnp_print(netdissect_options *ndo,
             return (0);
         }
 
+       if (li > length) {
+            ND_PRINT((ndo, " length indicator(%u) > PDU size (%u)!", li, length));
+            return (0);
+       }
+
+        if (li < sizeof(struct clnp_header_t)) {
+            ND_PRINT((ndo, " length indicator %u < min PDU size:", li));
+            while (pptr < ndo->ndo_snapend)
+                ND_PRINT((ndo, "%02X", *pptr++));
+            return (0);
+        }
+
         /* FIXME further header sanity checking */
 
         clnp_pdu_type = clnp_header->type & CLNP_PDU_TYPE_MASK;
@@ -794,22 +809,46 @@ clnp_print(netdissect_options *ndo,
 
         pptr += sizeof(struct clnp_header_t);
         li -= sizeof(struct clnp_header_t);
+
+        if (li < 1) {
+            ND_PRINT((ndo, "li < size of fixed part of CLNP header and addresses"));
+            return (0);
+        }
+       ND_TCHECK(*pptr);
         dest_address_length = *pptr;
-        dest_address = pptr + 1;
+        pptr += 1;
+        li -= 1;
+        if (li < dest_address_length) {
+            ND_PRINT((ndo, "li < size of fixed part of CLNP header and addresses"));
+            return (0);
+        }
+        ND_TCHECK2(*pptr, dest_address_length);
+        dest_address = pptr;
+        pptr += dest_address_length;
+        li -= dest_address_length;
 
-        pptr += (1 + dest_address_length);
-        li -= (1 + dest_address_length);
+        if (li < 1) {
+            ND_PRINT((ndo, "li < size of fixed part of CLNP header and addresses"));
+            return (0);
+        }
+       ND_TCHECK(*pptr);
         source_address_length = *pptr;
-        source_address = pptr +1;
-
-        pptr += (1 + source_address_length);
-        li -= (1 + source_address_length);
+        pptr += 1;
+        li -= 1;
+        if (li < source_address_length) {
+            ND_PRINT((ndo, "li < size of fixed part of CLNP header and addresses"));
+            return (0);
+        }
+        ND_TCHECK2(*pptr, source_address_length);
+        source_address = pptr;
+        pptr += source_address_length;
+        li -= source_address_length;
 
         if (ndo->ndo_vflag < 1) {
             ND_PRINT((ndo, "%s%s > %s, %s, length %u",
                    ndo->ndo_eflag ? "" : ", ",
-                   isonsap_string(source_address, source_address_length),
-                   isonsap_string(dest_address, dest_address_length),
+                   isonsap_string(ndo, source_address, source_address_length),
+                   isonsap_string(ndo, dest_address, dest_address_length),
                    tok2str(clnp_pdu_values,"unknown (%u)",clnp_pdu_type),
                    length));
             return (1);
@@ -833,11 +872,15 @@ clnp_print(netdissect_options *ndo,
 
         ND_PRINT((ndo, "\n\tsource address (length %u): %s\n\tdest   address (length %u): %s",
                source_address_length,
-               isonsap_string(source_address, source_address_length),
+               isonsap_string(ndo, source_address, source_address_length),
                dest_address_length,
-               isonsap_string(dest_address, dest_address_length)));
+               isonsap_string(ndo, dest_address, dest_address_length)));
 
         if (clnp_flags & CLNP_SEGMENT_PART) {
+                if (li < sizeof(const struct clnp_segment_header_t)) {
+                    ND_PRINT((ndo, "li < size of fixed part of CLNP header, addresses, and segment part"));
+                    return (0);
+                }
                clnp_segment_header = (const struct clnp_segment_header_t *) pptr;
                 ND_TCHECK(*clnp_segment_header);
                 ND_PRINT((ndo, "\n\tData Unit ID: 0x%04x, Segment Offset: %u, Total PDU Length: %u",
@@ -851,21 +894,21 @@ clnp_print(netdissect_options *ndo,
         /* now walk the options */
         while (li >= 2) {
             u_int op, opli;
-            const u_int8_t *tptr;
+            const uint8_t *tptr;
 
-            ND_TCHECK2(*pptr, 2);
             if (li < 2) {
                 ND_PRINT((ndo, ", bad opts/li"));
                 return (0);
             }
+            ND_TCHECK2(*pptr, 2);
             op = *pptr++;
             opli = *pptr++;
             li -= 2;
-            ND_TCHECK2(*pptr, opli);
             if (opli > li) {
                 ND_PRINT((ndo, ", opt (%d) too long", op));
                 return (0);
             }
+            ND_TCHECK2(*pptr, opli);
             li -= opli;
             tptr = pptr;
             tlen = opli;
@@ -875,11 +918,23 @@ clnp_print(netdissect_options *ndo,
                    op,
                    opli));
 
+            /*
+             * We've already checked that the entire option is present
+             * in the captured packet with the ND_TCHECK2() call.
+             * Therefore, we don't need to do ND_TCHECK()/ND_TCHECK2()
+             * checks.
+             * We do, however, need to check tlen, to make sure we
+             * don't run past the end of the option.
+            */
             switch (op) {
 
 
             case CLNP_OPTION_ROUTE_RECORDING: /* those two options share the format */
             case CLNP_OPTION_SOURCE_ROUTING:
+                    if (tlen < 2) {
+                            ND_PRINT((ndo, ", bad opt len"));
+                            return (0);
+                    }
                     ND_PRINT((ndo, "%s %s",
                            tok2str(clnp_option_sr_rr_values,"Unknown",*tptr),
                            tok2str(clnp_option_sr_rr_string_values, "Unknown Option %u", op)));
@@ -906,17 +961,25 @@ clnp_print(netdissect_options *ndo,
                                     ND_TCHECK2(*source_address, source_address_length);
                                     ND_PRINT((ndo, "\n\t    NSAP address (length %u): %s",
                                            source_address_length,
-                                           isonsap_string(source_address, source_address_length)));
+                                           isonsap_string(ndo, source_address, source_address_length)));
                             }
                             tlen-=source_address_length+1;
                     }
                     break;
 
             case CLNP_OPTION_PRIORITY:
+                    if (tlen < 1) {
+                            ND_PRINT((ndo, ", bad opt len"));
+                            return (0);
+                    }
                     ND_PRINT((ndo, "0x%1x", *tptr&0x0f));
                     break;
 
             case CLNP_OPTION_QOS_MAINTENANCE:
+                    if (tlen < 1) {
+                            ND_PRINT((ndo, ", bad opt len"));
+                            return (0);
+                    }
                     ND_PRINT((ndo, "\n\t    Format Code: %s",
                            tok2str(clnp_option_scope_values, "Reserved", *tptr&CLNP_OPTION_SCOPE_MASK)));
 
@@ -928,12 +991,20 @@ clnp_print(netdissect_options *ndo,
                     break;
 
             case CLNP_OPTION_SECURITY:
+                    if (tlen < 2) {
+                            ND_PRINT((ndo, ", bad opt len"));
+                            return (0);
+                    }
                     ND_PRINT((ndo, "\n\t    Format Code: %s, Security-Level %u",
                            tok2str(clnp_option_scope_values,"Reserved",*tptr&CLNP_OPTION_SCOPE_MASK),
                            *(tptr+1)));
                     break;
 
             case CLNP_OPTION_DISCARD_REASON:
+                if (tlen < 1) {
+                        ND_PRINT((ndo, ", bad opt len"));
+                        return (0);
+                }
                 rfd_error_major = (*tptr&0xf0) >> 4;
                 rfd_error_minor = *tptr&0x0f;
                 ND_PRINT((ndo, "\n\t    Class: %s Error (0x%01x), %s (0x%01x)",
@@ -1006,20 +1077,20 @@ static const struct tok esis_pdu_values[] = {
 };
 
 struct esis_header_t {
-       u_int8_t nlpid;
-       u_int8_t length_indicator;
-       u_int8_t version;
-       u_int8_t reserved;
-       u_int8_t type;
-       u_int8_t holdtime[2];
-       u_int8_t cksum[2];
+       uint8_t nlpid;
+       uint8_t length_indicator;
+       uint8_t version;
+       uint8_t reserved;
+       uint8_t type;
+       uint8_t holdtime[2];
+       uint8_t cksum[2];
 };
 
 static void
 esis_print(netdissect_options *ndo,
-           const u_int8_t *pptr, u_int length)
+           const uint8_t *pptr, u_int length)
 {
-       const u_int8_t *optr;
+       const uint8_t *optr;
        u_int li,esis_pdu_type,source_address_length, source_address_number;
        const struct esis_header_t *esis_header;
 
@@ -1051,13 +1122,13 @@ esis_print(netdissect_options *ndo,
         }
 
        if (li > length) {
-            ND_PRINT((ndo, " length indicator(%d) > PDU size (%d)!", li, length));
+            ND_PRINT((ndo, " length indicator(%u) > PDU size (%u)!", li, length));
             return;
        }
 
        if (li < sizeof(struct esis_header_t) + 2) {
-            ND_PRINT((ndo, " length indicator < min PDU size %d:", li));
-            while (--length != 0)
+            ND_PRINT((ndo, " length indicator %u < min PDU size:", li));
+            while (pptr < ndo->ndo_snapend)
                 ND_PRINT((ndo, "%02X", *pptr++));
             return;
        }
@@ -1093,7 +1164,7 @@ esis_print(netdissect_options *ndo,
 
        switch (esis_pdu_type) {
        case ESIS_PDU_REDIRECT: {
-               const u_int8_t *dst, *snpa, *neta;
+               const uint8_t *dst, *snpa, *neta;
                u_int dstl, snpal, netal;
 
                ND_TCHECK(*pptr);
@@ -1112,7 +1183,7 @@ esis_print(netdissect_options *ndo,
                dst = pptr;
                pptr += dstl;
                 li -= dstl;
-               ND_PRINT((ndo, "\n\t  %s", isonsap_string(dst, dstl)));
+               ND_PRINT((ndo, "\n\t  %s", isonsap_string(ndo, dst, dstl)));
 
                ND_TCHECK(*pptr);
                if (li < 1) {
@@ -1146,10 +1217,18 @@ esis_print(netdissect_options *ndo,
                pptr += netal;
                 li -= netal;
 
-               if (netal == 0)
-                       ND_PRINT((ndo, "\n\t  %s", etheraddr_string(snpa)));
+               if (snpal == 6)
+                       ND_PRINT((ndo, "\n\t  SNPA (length: %u): %s",
+                              snpal,
+                              etheraddr_string(ndo, snpa)));
                else
-                       ND_PRINT((ndo, "\n\t  %s", isonsap_string(neta, netal)));
+                       ND_PRINT((ndo, "\n\t  SNPA (length: %u): %s",
+                              snpal,
+                              linkaddr_string(ndo, snpa, LINKADDR_OTHER, snpal)));
+               if (netal != 0)
+                       ND_PRINT((ndo, "\n\t  NET (length: %u) %s",
+                              netal,
+                              isonsap_string(ndo, neta, netal)));
                break;
        }
 
@@ -1182,7 +1261,7 @@ esis_print(netdissect_options *ndo,
                }
                 ND_PRINT((ndo, "\n\t  NET (length: %u): %s",
                        source_address_length,
-                       isonsap_string(pptr, source_address_length)));
+                       isonsap_string(ndo, pptr, source_address_length)));
                 pptr += source_address_length;
                 li -= source_address_length;
                 source_address_number--;
@@ -1204,7 +1283,7 @@ esis_print(netdissect_options *ndo,
                 ND_PRINT((ndo, ", bad ish/li"));
                 return;
             }
-            ND_PRINT((ndo, "\n\t  NET (length: %u): %s", source_address_length, isonsap_string(pptr, source_address_length)));
+            ND_PRINT((ndo, "\n\t  NET (length: %u): %s", source_address_length, isonsap_string(ndo, pptr, source_address_length)));
             pptr += source_address_length;
             li -= source_address_length;
             break;
@@ -1221,7 +1300,7 @@ esis_print(netdissect_options *ndo,
         /* now walk the options */
         while (li != 0) {
             u_int op, opli;
-            const u_int8_t *tptr;
+            const uint8_t *tptr;
 
             if (li < 2) {
                 ND_PRINT((ndo, ", bad opts/li"));
@@ -1297,14 +1376,11 @@ isis_print_mcid(netdissect_options *ndo,
 {
   int i;
 
+  ND_TCHECK(*mcid);
   ND_PRINT((ndo,  "ID: %d, Name: ", mcid->format_id));
 
-  for(i=0; i<32; i++)
-  {
-    ND_PRINT((ndo, "%c", mcid->name[i]));
-    if(mcid->name[i] == '\0')
-        break;
-  }
+  if (fn_printzp(ndo, mcid->name, 32, ndo->ndo_snapend))
+    goto trunc;
 
   ND_PRINT((ndo, "\n\t              Lvl: %d", EXTRACT_16BITS(mcid->revision_lvl)));
 
@@ -1312,18 +1388,22 @@ isis_print_mcid(netdissect_options *ndo,
 
   for(i=0;i<16;i++)
     ND_PRINT((ndo, "%.2x ", mcid->digest[i]));
+
+trunc:
+  ND_PRINT((ndo, "%s", tstr));
 }
 
 static int
 isis_print_mt_port_cap_subtlv(netdissect_options *ndo,
-                              const u_int8_t *tptr, int len)
+                              const uint8_t *tptr, int len)
 {
   int stlv_type, stlv_len;
   const struct isis_subtlv_spb_mcid *subtlv_spb_mcid;
   int i;
 
-  while (len > 0)
+  while (len > 2)
   {
+    ND_TCHECK2(*tptr, 2);
     stlv_type = *(tptr++);
     stlv_len  = *(tptr++);
 
@@ -1336,14 +1416,20 @@ isis_print_mt_port_cap_subtlv(netdissect_options *ndo,
     /*len -= TLV_TYPE_LEN_OFFSET;*/
     len = len -2;
 
+    /* Make sure the subTLV fits within the space left */
+    if (len < stlv_len)
+      goto trunc;
+    /* Make sure the entire subTLV is in the captured data */
+    ND_TCHECK2(*(tptr), stlv_len);
+
     switch (stlv_type)
     {
       case ISIS_SUBTLV_SPB_MCID:
       {
-        if (!ND_TTEST2(*(tptr), ISIS_SUBTLV_SPB_MCID_MIN_LEN))
-          goto trunctlv;
+       if (stlv_len < ISIS_SUBTLV_SPB_MCID_MIN_LEN)
+         goto trunc;
 
-        subtlv_spb_mcid = (struct isis_subtlv_spb_mcid *)tptr;
+        subtlv_spb_mcid = (const struct isis_subtlv_spb_mcid *)tptr;
 
         ND_PRINT((ndo,  "\n\t         MCID: "));
         isis_print_mcid(ndo, &(subtlv_spb_mcid->mcid));
@@ -1356,16 +1442,17 @@ isis_print_mt_port_cap_subtlv(netdissect_options *ndo,
 
           /*tptr += SPB_MCID_MIN_LEN;
             len -= SPB_MCID_MIN_LEN; */
-        tptr = tptr + sizeof(struct isis_subtlv_spb_mcid);
-        len = len - sizeof(struct isis_subtlv_spb_mcid);
+        tptr = tptr + ISIS_SUBTLV_SPB_MCID_MIN_LEN;
+        len = len - ISIS_SUBTLV_SPB_MCID_MIN_LEN;
+        stlv_len = stlv_len - ISIS_SUBTLV_SPB_MCID_MIN_LEN;
 
         break;
       }
 
       case ISIS_SUBTLV_SPB_DIGEST:
       {
-        if (!ND_TTEST2(*(tptr), ISIS_SUBTLV_SPB_DIGEST_MIN_LEN))
-          goto trunctlv;
+        if (stlv_len < ISIS_SUBTLV_SPB_DIGEST_MIN_LEN)
+          goto trunc;
 
         ND_PRINT((ndo, "\n\t        RES: %d V: %d A: %d D: %d",
                         (*(tptr) >> 5), (((*tptr)>> 4) & 0x01),
@@ -1384,20 +1471,15 @@ isis_print_mt_port_cap_subtlv(netdissect_options *ndo,
         }
 
         len = len - ISIS_SUBTLV_SPB_DIGEST_MIN_LEN;
+        stlv_len = stlv_len - ISIS_SUBTLV_SPB_DIGEST_MIN_LEN;
 
         break;
       }
 
       case ISIS_SUBTLV_SPB_BVID:
       {
-        if (!ND_TTEST2(*(tptr), stlv_len))
-          goto trunctlv;
-
-        while (len)
+        while (stlv_len >= ISIS_SUBTLV_SPB_BVID_MIN_LEN)
         {
-          if (!ND_TTEST2(*(tptr), ISIS_SUBTLV_SPB_BVID_MIN_LEN))
-            goto trunctlv;
-
           ND_PRINT((ndo, "\n\t           ECT: %08x",
                       EXTRACT_32BITS(tptr)));
 
@@ -1410,31 +1492,36 @@ isis_print_mt_port_cap_subtlv(netdissect_options *ndo,
 
           tptr = tptr + 2;
           len = len - ISIS_SUBTLV_SPB_BVID_MIN_LEN;
+          stlv_len = stlv_len - ISIS_SUBTLV_SPB_BVID_MIN_LEN;
         }
 
         break;
       }
 
       default:
-          break;
+        break;
     }
+    tptr += stlv_len;
+    len -= stlv_len;
   }
 
   return 0;
 
-  trunctlv:
-    ND_PRINT((ndo, "\n\t\t packet exceeded snapshot"));
+  trunc:
+    ND_PRINT((ndo, "\n\t\t"));
+    ND_PRINT((ndo, "%s", tstr));
     return(1);
 }
 
 static int
 isis_print_mt_capability_subtlv(netdissect_options *ndo,
-                                const u_int8_t *tptr, int len)
+                                const uint8_t *tptr, int len)
 {
   int stlv_type, stlv_len, tmp;
 
-  while (len > 0)
+  while (len > 2)
   {
+    ND_TCHECK2(*tptr, 2);
     stlv_type = *(tptr++);
     stlv_len  = *(tptr++);
 
@@ -1446,12 +1533,17 @@ isis_print_mt_capability_subtlv(netdissect_options *ndo,
 
     len = len - 2;
 
+    /* Make sure the subTLV fits within the space left */
+    if (len < stlv_len)
+      goto trunc;
+    /* Make sure the entire subTLV is in the captured data */
+    ND_TCHECK2(*(tptr), stlv_len);
+
     switch (stlv_type)
     {
       case ISIS_SUBTLV_SPB_INSTANCE:
-
-          if (!ND_TTEST2(*(tptr), ISIS_SUBTLV_SPB_INSTANCE_MIN_LEN))
-            goto trunctlv;
+          if (stlv_len < ISIS_SUBTLV_SPB_INSTANCE_MIN_LEN)
+            goto trunc;
 
           ND_PRINT((ndo, "\n\t        CIST Root-ID: %08x", EXTRACT_32BITS(tptr)));
           tptr = tptr+4;
@@ -1473,11 +1565,12 @@ isis_print_mt_capability_subtlv(netdissect_options *ndo,
           tmp = *(tptr++);
 
           len = len - ISIS_SUBTLV_SPB_INSTANCE_MIN_LEN;
+          stlv_len = stlv_len - ISIS_SUBTLV_SPB_INSTANCE_MIN_LEN;
 
           while (tmp)
           {
-            if (!ND_TTEST2(*(tptr), ISIS_SUBTLV_SPB_INSTANCE_VLAN_TUPLE_LEN))
-              goto trunctlv;
+            if (stlv_len < ISIS_SUBTLV_SPB_INSTANCE_VLAN_TUPLE_LEN)
+              goto trunc;
 
             ND_PRINT((ndo, "\n\t         U:%d, M:%d, A:%d, RES:%d",
                       *(tptr) >> 7, (*(tptr) >> 6) & 0x01,
@@ -1495,15 +1588,15 @@ isis_print_mt_capability_subtlv(netdissect_options *ndo,
 
             tptr = tptr + 3;
             len = len - ISIS_SUBTLV_SPB_INSTANCE_VLAN_TUPLE_LEN;
+            stlv_len = stlv_len - ISIS_SUBTLV_SPB_INSTANCE_VLAN_TUPLE_LEN;
             tmp--;
           }
 
           break;
 
       case ISIS_SUBTLV_SPBM_SI:
-
-          if (!ND_TTEST2(*(tptr), 6))
-            goto trunctlv;
+          if (stlv_len < 8)
+            goto trunc;
 
           ND_PRINT((ndo, "\n\t        BMAC: %08x", EXTRACT_32BITS(tptr)));
           tptr = tptr+4;
@@ -1517,8 +1610,8 @@ isis_print_mt_capability_subtlv(netdissect_options *ndo,
           len = len - 8;
           stlv_len = stlv_len - 8;
 
-          while (stlv_len)
-          {
+          while (stlv_len >= 4) {
+            ND_TCHECK2(*tptr, 4);
             ND_PRINT((ndo, "\n\t        T: %d, R: %d, RES: %d, ISID: %d",
                     (EXTRACT_32BITS(tptr) >> 31),
                     (EXTRACT_32BITS(tptr) >> 30) & 0x01,
@@ -1535,23 +1628,30 @@ isis_print_mt_capability_subtlv(netdissect_options *ndo,
       default:
         break;
     }
+    tptr += stlv_len;
+    len -= stlv_len;
   }
   return 0;
 
-  trunctlv:
-    ND_PRINT((ndo, "\n\t\t packet exceeded snapshot"));
+  trunc:
+    ND_PRINT((ndo, "\n\t\t"));
+    ND_PRINT((ndo, "%s", tstr));
     return(1);
 }
 
 /* shared routine for printing system, node and lsp-ids */
 static char *
-isis_print_id(const u_int8_t *cp, int id_len)
+isis_print_id(const uint8_t *cp, int id_len)
 {
     int i;
     static char id[sizeof("xxxx.xxxx.xxxx.yy-zz")];
     char *pos = id;
+    int sysid_len;
 
-    for (i = 1; i <= SYSTEM_ID_LEN; i++) {
+    sysid_len = SYSTEM_ID_LEN;
+    if (sysid_len > id_len)
+        sysid_len = id_len;
+    for (i = 1; i <= sysid_len; i++) {
         snprintf(pos, sizeof(id) - (pos - id), "%02x", *cp++);
        pos += strlen(pos);
        if (i == 2 || i == 4)
@@ -1592,7 +1692,7 @@ isis_print_metric_block(netdissect_options *ndo,
 
 static int
 isis_print_tlv_ip_reach(netdissect_options *ndo,
-                        const u_int8_t *cp, const char *ident, int length)
+                        const uint8_t *cp, const char *ident, int length)
 {
        int prefix_len;
        const struct isis_tlv_ip_reach *tlv_ip_reach;
@@ -1615,12 +1715,12 @@ isis_print_tlv_ip_reach(netdissect_options *ndo,
                if (prefix_len == -1)
                        ND_PRINT((ndo, "%sIPv4 prefix: %s mask %s",
                                ident,
-                              ipaddr_string((tlv_ip_reach->prefix)),
-                              ipaddr_string((tlv_ip_reach->mask))));
+                              ipaddr_string(ndo, (tlv_ip_reach->prefix)),
+                              ipaddr_string(ndo, (tlv_ip_reach->mask))));
                else
                        ND_PRINT((ndo, "%sIPv4 prefix: %15s/%u",
                                ident,
-                              ipaddr_string((tlv_ip_reach->prefix)),
+                              ipaddr_string(ndo, (tlv_ip_reach->prefix)),
                               prefix_len));
 
                ND_PRINT((ndo, ", Distribution: %s, Metric: %u, %s",
@@ -1659,16 +1759,15 @@ isis_print_tlv_ip_reach(netdissect_options *ndo,
 
 static int
 isis_print_ip_reach_subtlv(netdissect_options *ndo,
-                           const u_int8_t *tptr, int subt, int subl,
-                           const char *ident) {
-
-        /* first lets see if we know the subTLVs name*/
-       ND_PRINT((ndo, "%s%s subTLV #%u, length: %u",
-                 ident, tok2str(isis_ext_ip_reach_subtlv_values, "unknown", subt),
-                 subt, subl));
+                           const uint8_t *tptr, int subt, int subl,
+                           const char *ident)
+{
+    /* first lets see if we know the subTLVs name*/
+    ND_PRINT((ndo, "%s%s subTLV #%u, length: %u",
+              ident, tok2str(isis_ext_ip_reach_subtlv_values, "unknown", subt),
+              subt, subl));
 
-       if (!ND_TTEST2(*tptr,subl))
-           goto trunctlv;
+    ND_TCHECK2(*tptr,subl);
 
     switch(subt) {
     case ISIS_SUBTLV_EXTD_IP_REACH_MGMT_PREFIX_COLOR: /* fall through */
@@ -1697,8 +1796,9 @@ isis_print_ip_reach_subtlv(netdissect_options *ndo,
     }
     return(1);
 
-trunctlv:
-    ND_PRINT((ndo, "%spacket exceeded snapshot", ident));
+trunc:
+    ND_PRINT((ndo, "%s", ident));
+    ND_PRINT((ndo, "%s", tstr));
     return(0);
 }
 
@@ -1709,13 +1809,13 @@ trunctlv:
 
 static int
 isis_print_is_reach_subtlv(netdissect_options *ndo,
-                           const u_int8_t *tptr, u_int subt, u_int subl,
-                           const char *ident) {
-
+                           const uint8_t *tptr, u_int subt, u_int subl,
+                           const char *ident)
+{
         u_int te_class,priority_level,gmpls_switch_cap;
         union { /* int to float conversion buffer for several subTLVs */
             float f;
-            u_int32_t i;
+            uint32_t i;
         } bw;
 
         /* first lets see if we know the subTLVs name*/
@@ -1723,8 +1823,7 @@ isis_print_is_reach_subtlv(netdissect_options *ndo,
                  ident, tok2str(isis_ext_is_reach_subtlv_values, "unknown", subt),
                  subt, subl));
 
-       if (!ND_TTEST2(*tptr,subl))
-           goto trunctlv;
+       ND_TCHECK2(*tptr, subl);
 
         switch(subt) {
         case ISIS_SUBTLV_EXT_IS_REACH_ADMIN_GROUP:
@@ -1739,7 +1838,7 @@ isis_print_is_reach_subtlv(netdissect_options *ndo,
         case ISIS_SUBTLV_EXT_IS_REACH_IPV4_INTF_ADDR:
         case ISIS_SUBTLV_EXT_IS_REACH_IPV4_NEIGHBOR_ADDR:
             if (subl >= sizeof(struct in_addr))
-              ND_PRINT((ndo, ", %s", ipaddr_string(tptr)));
+              ND_PRINT((ndo, ", %s", ipaddr_string(ndo, tptr)));
             break;
         case ISIS_SUBTLV_EXT_IS_REACH_MAX_LINK_BW :
        case ISIS_SUBTLV_EXT_IS_REACH_RESERVABLE_BW:
@@ -1769,6 +1868,7 @@ isis_print_is_reach_subtlv(netdissect_options *ndo,
             tptr++;
             /* decode BCs until the subTLV ends */
             for (te_class = 0; te_class < (subl-1)/4; te_class++) {
+                ND_TCHECK2(*tptr, 4);
                 bw.i = EXTRACT_32BITS(tptr);
                 ND_PRINT((ndo, "%s  Bandwidth constraint CT%u: %.3f Mbps",
                        ident,
@@ -1830,11 +1930,13 @@ isis_print_is_reach_subtlv(netdissect_options *ndo,
               case GMPLS_PSC2:
               case GMPLS_PSC3:
               case GMPLS_PSC4:
+                ND_TCHECK2(*tptr, 6);
                 bw.i = EXTRACT_32BITS(tptr);
                 ND_PRINT((ndo, "%s  Min LSP Bandwidth: %.3f Mbps", ident, bw.f * 8 / 1000000));
                 ND_PRINT((ndo, "%s  Interface MTU: %u", ident, EXTRACT_16BITS(tptr + 4)));
                 break;
               case GMPLS_TSC:
+                ND_TCHECK2(*tptr, 8);
                 bw.i = EXTRACT_32BITS(tptr);
                 ND_PRINT((ndo, "%s  Min LSP Bandwidth: %.3f Mbps", ident, bw.f * 8 / 1000000));
                 ND_PRINT((ndo, "%s  Indication %s", ident,
@@ -1857,12 +1959,10 @@ isis_print_is_reach_subtlv(netdissect_options *ndo,
         }
         return(1);
 
-trunctlv:
-    ND_PRINT((ndo, "%spacket exceeded snapshot", ident));
+trunc:
     return(0);
 }
 
-
 /*
  * this is the common IS-REACH decoder it is called
  * from various EXTD-IS REACH style TLVs (22,24,222)
@@ -1870,8 +1970,8 @@ trunctlv:
 
 static int
 isis_print_ext_is_reach(netdissect_options *ndo,
-                        const u_int8_t *tptr, const char *ident, int tlv_type) {
-
+                        const uint8_t *tptr, const char *ident, int tlv_type)
+{
     char ident_buffer[20];
     int subtlv_type,subtlv_len,subtlv_sum_len;
     int proc_bytes = 0; /* how many bytes did we process ? */
@@ -1901,7 +2001,7 @@ isis_print_ext_is_reach(netdissect_options *ndo,
                 return(0);
             subtlv_type=*(tptr++);
             subtlv_len=*(tptr++);
-            /* prepend the ident string */
+            /* prepend the indent string */
             snprintf(ident_buffer, sizeof(ident_buffer), "%s  ",ident);
             if (!isis_print_is_reach_subtlv(ndo, tptr, subtlv_type, subtlv_len, ident_buffer))
                 return(0);
@@ -1920,8 +2020,8 @@ isis_print_ext_is_reach(netdissect_options *ndo,
 
 static int
 isis_print_mtid(netdissect_options *ndo,
-                const u_int8_t *tptr, const char *ident) {
-
+                const uint8_t *tptr, const char *ident)
+{
     if (!ND_TTEST2(*tptr, 2))
         return(0);
 
@@ -1947,14 +2047,10 @@ isis_print_mtid(netdissect_options *ndo,
 
 static int
 isis_print_extd_ip_reach(netdissect_options *ndo,
-                         const u_int8_t *tptr, const char *ident, u_int16_t afi) {
-
+                         const uint8_t *tptr, const char *ident, uint16_t afi)
+{
     char ident_buffer[20];
-#ifdef INET6
-    u_int8_t prefix[sizeof(struct in6_addr)]; /* shared copy buffer for IPv4 and IPv6 prefixes */
-#else
-    u_int8_t prefix[sizeof(struct in_addr)]; /* shared copy buffer for IPv4 prefixes */
-#endif
+    uint8_t prefix[sizeof(struct in6_addr)]; /* shared copy buffer for IPv4 and IPv6 prefixes */
     u_int metric, status_byte, bit_length, byte_length, sublen, processed, subtlvtype, subtlvlen;
 
     if (!ND_TTEST2(*tptr, 4))
@@ -1975,9 +2071,8 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
             return (0);
         }
         processed++;
-#ifdef INET6
     } else if (afi == AF_INET6) {
-        if (!ND_TTEST2(*tptr, 1)) /* fetch status & prefix_len byte */
+        if (!ND_TTEST2(*tptr, 2)) /* fetch status & prefix_len byte */
             return (0);
         status_byte=*(tptr++);
         bit_length=*(tptr++);
@@ -1988,7 +2083,6 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
             return (0);
         }
         processed+=2;
-#endif
     } else
         return (0); /* somebody is fooling us */
 
@@ -2004,15 +2098,13 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
     if (afi == AF_INET)
         ND_PRINT((ndo, "%sIPv4 prefix: %15s/%u",
                ident,
-               ipaddr_string(prefix),
+               ipaddr_string(ndo, prefix),
                bit_length));
-#ifdef INET6
-    if (afi == AF_INET6)
+    else if (afi == AF_INET6)
         ND_PRINT((ndo, "%sIPv6 prefix: %s/%u",
                ident,
-               ip6addr_string(prefix),
+               ip6addr_string(ndo, prefix),
                bit_length));
-#endif
 
     ND_PRINT((ndo, ", Distribution: %s, Metric: %u",
            ISIS_MASK_TLV_EXTD_IP_UPDOWN(status_byte) ? "down" : "up",
@@ -2020,17 +2112,13 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
 
     if (afi == AF_INET && ISIS_MASK_TLV_EXTD_IP_SUBTLV(status_byte))
         ND_PRINT((ndo, ", sub-TLVs present"));
-#ifdef INET6
-    if (afi == AF_INET6)
+    else if (afi == AF_INET6)
         ND_PRINT((ndo, ", %s%s",
                ISIS_MASK_TLV_EXTD_IP6_IE(status_byte) ? "External" : "Internal",
                ISIS_MASK_TLV_EXTD_IP6_SUBTLV(status_byte) ? ", sub-TLVs present" : ""));
-#endif
 
     if ((afi == AF_INET  && ISIS_MASK_TLV_EXTD_IP_SUBTLV(status_byte))
-#ifdef INET6
      || (afi == AF_INET6 && ISIS_MASK_TLV_EXTD_IP6_SUBTLV(status_byte))
-#endif
        ) {
         /* assume that one prefix can hold more
            than one subTLV - therefore the first byte must reflect
@@ -2047,7 +2135,7 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
                 return (0);
             subtlvtype=*(tptr++);
             subtlvlen=*(tptr++);
-            /* prepend the ident string */
+            /* prepend the indent string */
             snprintf(ident_buffer, sizeof(ident_buffer), "%s  ",ident);
             if (!isis_print_ip_reach_subtlv(ndo, tptr, subtlvtype, subtlvlen, ident_buffer))
                 return(0);
@@ -2058,6 +2146,20 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
     return (processed);
 }
 
+/*
+ * Clear checksum and lifetime prior to signature verification.
+ */
+static void
+isis_clear_checksum_lifetime(void *header)
+{
+    struct isis_lsp_header *header_lsp = (struct isis_lsp_header *) header;
+
+    header_lsp->checksum[0] = 0;
+    header_lsp->checksum[1] = 0;
+    header_lsp->remaining_lifetime[0] = 0;
+    header_lsp->remaining_lifetime[1] = 0;
+}
+
 /*
  * isis_print
  * Decode IS-IS packets.  Return 0 on error.
@@ -2065,13 +2167,13 @@ isis_print_extd_ip_reach(netdissect_options *ndo,
 
 static int
 isis_print(netdissect_options *ndo,
-           const u_int8_t *p, u_int length)
+           const uint8_t *p, u_int length)
 {
     const struct isis_common_header *isis_header;
 
     const struct isis_iih_lan_header *header_iih_lan;
     const struct isis_iih_ptp_header *header_iih_ptp;
-    struct isis_lsp_header *header_lsp;
+    const struct isis_lsp_header *header_lsp;
     const struct isis_csnp_header *header_csnp;
     const struct isis_psnp_header *header_psnp;
 
@@ -2080,9 +2182,9 @@ isis_print(netdissect_options *ndo,
     const struct isis_tlv_is_reach *tlv_is_reach;
     const struct isis_tlv_es_reach *tlv_es_reach;
 
-    u_int8_t pdu_type, max_area, id_length, tlv_type, tlv_len, tmp, alen, lan_alen, prefix_len;
-    u_int8_t ext_is_len, ext_ip_len, mt_len;
-    const u_int8_t *optr, *pptr, *tptr;
+    uint8_t pdu_type, max_area, id_length, tlv_type, tlv_len, tmp, alen, lan_alen, prefix_len;
+    uint8_t ext_is_len, ext_ip_len, mt_len;
+    const uint8_t *optr, *pptr, *tptr;
     u_short packet_len,pdu_len, key_id;
     u_int i,vendor_id;
     int sigcheck;
@@ -2093,10 +2195,12 @@ isis_print(netdissect_options *ndo,
                  TLV verification */
     isis_header = (const struct isis_common_header *)p;
     ND_TCHECK(*isis_header);
+    if (length < ISIS_COMMON_HEADER_SIZE)
+        goto trunc;
     pptr = p+(ISIS_COMMON_HEADER_SIZE);
     header_iih_lan = (const struct isis_iih_lan_header *)pptr;
     header_iih_ptp = (const struct isis_iih_ptp_header *)pptr;
-    header_lsp = (struct isis_lsp_header *)pptr;
+    header_lsp = (const struct isis_lsp_header *)pptr;
     header_csnp = (const struct isis_csnp_header *)pptr;
     header_psnp = (const struct isis_psnp_header *)pptr;
 
@@ -2123,6 +2227,16 @@ isis_print(netdissect_options *ndo,
        return (0);
     }
 
+    if (length < isis_header->fixed_len) {
+       ND_PRINT((ndo, "fixed header length %u > packet length %u", isis_header->fixed_len, length));
+       return (0);
+    }
+
+    if (isis_header->fixed_len < ISIS_COMMON_HEADER_SIZE) {
+       ND_PRINT((ndo, "fixed header length %u < minimum header size %u", isis_header->fixed_len, (u_int)ISIS_COMMON_HEADER_SIZE));
+       return (0);
+    }
+
     max_area = isis_header->max_area;
     switch(max_area) {
     case 0:
@@ -2165,259 +2279,256 @@ isis_print(netdissect_options *ndo,
     pdu_type=isis_header->pdu_type;
 
     /* in non-verbose mode print the basic PDU Type plus PDU specific brief information*/
-    if (ndo->ndo_vflag < 1) {
+    if (ndo->ndo_vflag == 0) {
         ND_PRINT((ndo, "%s%s",
                ndo->ndo_eflag ? "" : ", ",
                tok2str(isis_pdu_values, "unknown PDU-Type %u", pdu_type)));
+    } else {
+        /* ok they seem to want to know everything - lets fully decode it */
+        ND_PRINT((ndo, "%slength %u", ndo->ndo_eflag ? "" : ", ", length));
 
-       switch (pdu_type) {
-
-       case ISIS_PDU_L1_LAN_IIH:
-       case ISIS_PDU_L2_LAN_IIH:
-           ND_PRINT((ndo, ", src-id %s",
-                   isis_print_id(header_iih_lan->source_id, SYSTEM_ID_LEN)));
-           ND_PRINT((ndo, ", lan-id %s, prio %u",
-                   isis_print_id(header_iih_lan->lan_id,NODE_ID_LEN),
-                   header_iih_lan->priority));
-           break;
-       case ISIS_PDU_PTP_IIH:
-           ND_PRINT((ndo, ", src-id %s", isis_print_id(header_iih_ptp->source_id, SYSTEM_ID_LEN)));
-           break;
-       case ISIS_PDU_L1_LSP:
-       case ISIS_PDU_L2_LSP:
-           ND_PRINT((ndo, ", lsp-id %s, seq 0x%08x, lifetime %5us",
-                  isis_print_id(header_lsp->lsp_id, LSP_ID_LEN),
-                  EXTRACT_32BITS(header_lsp->sequence_number),
-                  EXTRACT_16BITS(header_lsp->remaining_lifetime)));
-           break;
-       case ISIS_PDU_L1_CSNP:
-       case ISIS_PDU_L2_CSNP:
-           ND_PRINT((ndo, ", src-id %s", isis_print_id(header_csnp->source_id, NODE_ID_LEN)));
-           break;
-       case ISIS_PDU_L1_PSNP:
-       case ISIS_PDU_L2_PSNP:
-           ND_PRINT((ndo, ", src-id %s", isis_print_id(header_psnp->source_id, NODE_ID_LEN)));
-           break;
-
-       }
-       ND_PRINT((ndo, ", length %u", length));
-
-        return(1);
-    }
-
-    /* ok they seem to want to know everything - lets fully decode it */
-    ND_PRINT((ndo, "%slength %u", ndo->ndo_eflag ? "" : ", ", length));
-
-    ND_PRINT((ndo, "\n\t%s, hlen: %u, v: %u, pdu-v: %u, sys-id-len: %u (%u), max-area: %u (%u)",
-           tok2str(isis_pdu_values,
-                   "unknown, type %u",
-                   pdu_type),
-           isis_header->fixed_len,
-           isis_header->version,
-           isis_header->pdu_version,
-          id_length,
-          isis_header->id_length,
-           max_area,
-           isis_header->max_area));
-
-    if (ndo->ndo_vflag > 1) {
-        if (!print_unknown_data(ndo, optr, "\n\t", 8)) /* provide the _o_riginal pointer */
-            return(0);                         /* for optionally debugging the common header */
+        ND_PRINT((ndo, "\n\t%s, hlen: %u, v: %u, pdu-v: %u, sys-id-len: %u (%u), max-area: %u (%u)",
+               tok2str(isis_pdu_values,
+                       "unknown, type %u",
+                       pdu_type),
+               isis_header->fixed_len,
+               isis_header->version,
+               isis_header->pdu_version,
+               id_length,
+               isis_header->id_length,
+               max_area,
+               isis_header->max_area));
+
+        if (ndo->ndo_vflag > 1) {
+            if (!print_unknown_data(ndo, optr, "\n\t", 8)) /* provide the _o_riginal pointer */
+                return (0);                         /* for optionally debugging the common header */
+        }
     }
 
     switch (pdu_type) {
 
     case ISIS_PDU_L1_LAN_IIH:
     case ISIS_PDU_L2_LAN_IIH:
-       if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE)) {
-           ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
-                  isis_header->fixed_len, (unsigned long)ISIS_IIH_LAN_HEADER_SIZE));
-           return (0);
-       }
+        if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE)) {
+            ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
+                     isis_header->fixed_len, (unsigned long)(ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE)));
+            return (0);
+        }
+        ND_TCHECK(*header_iih_lan);
+        if (length < ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE)
+            goto trunc;
+        if (ndo->ndo_vflag == 0) {
+            ND_PRINT((ndo, ", src-id %s",
+                      isis_print_id(header_iih_lan->source_id, SYSTEM_ID_LEN)));
+            ND_PRINT((ndo, ", lan-id %s, prio %u",
+                      isis_print_id(header_iih_lan->lan_id,NODE_ID_LEN),
+                      header_iih_lan->priority));
+            ND_PRINT((ndo, ", length %u", length));
+            return (1);
+        }
+        pdu_len=EXTRACT_16BITS(header_iih_lan->pdu_len);
+        if (packet_len>pdu_len) {
+           packet_len=pdu_len; /* do TLV decoding as long as it makes sense */
+           length=pdu_len;
+        }
 
-       pdu_len=EXTRACT_16BITS(header_iih_lan->pdu_len);
-       if (packet_len>pdu_len) {
-            packet_len=pdu_len; /* do TLV decoding as long as it makes sense */
-            length=pdu_len;
-       }
+        ND_PRINT((ndo, "\n\t  source-id: %s,  holding time: %us, Flags: [%s]",
+                  isis_print_id(header_iih_lan->source_id,SYSTEM_ID_LEN),
+                  EXTRACT_16BITS(header_iih_lan->holding_time),
+                  tok2str(isis_iih_circuit_type_values,
+                          "unknown circuit type 0x%02x",
+                          header_iih_lan->circuit_type)));
 
-       ND_TCHECK(*header_iih_lan);
-       ND_PRINT((ndo, "\n\t  source-id: %s,  holding time: %us, Flags: [%s]",
-               isis_print_id(header_iih_lan->source_id,SYSTEM_ID_LEN),
-               EXTRACT_16BITS(header_iih_lan->holding_time),
-               tok2str(isis_iih_circuit_type_values,
-                       "unknown circuit type 0x%02x",
-                       header_iih_lan->circuit_type)));
-
-       ND_PRINT((ndo, "\n\t  lan-id:    %s, Priority: %u, PDU length: %u",
-               isis_print_id(header_iih_lan->lan_id, NODE_ID_LEN),
-               (header_iih_lan->priority) & ISIS_LAN_PRIORITY_MASK,
-               pdu_len));
+        ND_PRINT((ndo, "\n\t  lan-id:    %s, Priority: %u, PDU length: %u",
+                  isis_print_id(header_iih_lan->lan_id, NODE_ID_LEN),
+                  (header_iih_lan->priority) & ISIS_LAN_PRIORITY_MASK,
+                  pdu_len));
 
-       if (ndo->ndo_vflag > 1) {
-               if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_IIH_LAN_HEADER_SIZE))
-                       return(0);
-       }
+        if (ndo->ndo_vflag > 1) {
+            if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_IIH_LAN_HEADER_SIZE))
+                return (0);
+        }
 
-       packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE);
-       pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE);
-       break;
+        packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE);
+        pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_LAN_HEADER_SIZE);
+        break;
 
     case ISIS_PDU_PTP_IIH:
-       if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE)) {
-           ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
-                  isis_header->fixed_len, (unsigned long)ISIS_IIH_PTP_HEADER_SIZE));
-           return (0);
-       }
-
-       pdu_len=EXTRACT_16BITS(header_iih_ptp->pdu_len);
-       if (packet_len>pdu_len) {
+        if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE)) {
+            ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
+                      isis_header->fixed_len, (unsigned long)(ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE)));
+            return (0);
+        }
+        ND_TCHECK(*header_iih_ptp);
+        if (length < ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE)
+            goto trunc;
+        if (ndo->ndo_vflag == 0) {
+            ND_PRINT((ndo, ", src-id %s", isis_print_id(header_iih_ptp->source_id, SYSTEM_ID_LEN)));
+            ND_PRINT((ndo, ", length %u", length));
+            return (1);
+        }
+        pdu_len=EXTRACT_16BITS(header_iih_ptp->pdu_len);
+        if (packet_len>pdu_len) {
             packet_len=pdu_len; /* do TLV decoding as long as it makes sense */
             length=pdu_len;
-       }
+        }
 
-       ND_TCHECK(*header_iih_ptp);
-       ND_PRINT((ndo, "\n\t  source-id: %s, holding time: %us, Flags: [%s]",
-               isis_print_id(header_iih_ptp->source_id,SYSTEM_ID_LEN),
-               EXTRACT_16BITS(header_iih_ptp->holding_time),
-               tok2str(isis_iih_circuit_type_values,
-                       "unknown circuit type 0x%02x",
-                       header_iih_ptp->circuit_type)));
+        ND_PRINT((ndo, "\n\t  source-id: %s, holding time: %us, Flags: [%s]",
+                  isis_print_id(header_iih_ptp->source_id,SYSTEM_ID_LEN),
+                  EXTRACT_16BITS(header_iih_ptp->holding_time),
+                  tok2str(isis_iih_circuit_type_values,
+                          "unknown circuit type 0x%02x",
+                          header_iih_ptp->circuit_type)));
 
-       ND_PRINT((ndo, "\n\t  circuit-id: 0x%02x, PDU length: %u",
-               header_iih_ptp->circuit_id,
-               pdu_len));
+        ND_PRINT((ndo, "\n\t  circuit-id: 0x%02x, PDU length: %u",
+                  header_iih_ptp->circuit_id,
+                  pdu_len));
 
-       if (ndo->ndo_vflag > 1) {
-               if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_IIH_PTP_HEADER_SIZE))
-                       return(0);
-       }
+        if (ndo->ndo_vflag > 1) {
+            if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_IIH_PTP_HEADER_SIZE))
+                return (0);
+        }
 
-       packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE);
-       pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE);
-       break;
+        packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE);
+        pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_IIH_PTP_HEADER_SIZE);
+        break;
 
     case ISIS_PDU_L1_LSP:
     case ISIS_PDU_L2_LSP:
-       if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE)) {
-           ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
-                  isis_header->fixed_len, (unsigned long)ISIS_LSP_HEADER_SIZE));
-           return (0);
-       }
-
-       pdu_len=EXTRACT_16BITS(header_lsp->pdu_len);
-       if (packet_len>pdu_len) {
+        if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE)) {
+            ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
+                   isis_header->fixed_len, (unsigned long)ISIS_LSP_HEADER_SIZE));
+            return (0);
+        }
+        ND_TCHECK(*header_lsp);
+        if (length < ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE)
+            goto trunc;
+        if (ndo->ndo_vflag == 0) {
+            ND_PRINT((ndo, ", lsp-id %s, seq 0x%08x, lifetime %5us",
+                      isis_print_id(header_lsp->lsp_id, LSP_ID_LEN),
+                      EXTRACT_32BITS(header_lsp->sequence_number),
+                      EXTRACT_16BITS(header_lsp->remaining_lifetime)));
+            ND_PRINT((ndo, ", length %u", length));
+            return (1);
+        }
+        pdu_len=EXTRACT_16BITS(header_lsp->pdu_len);
+        if (packet_len>pdu_len) {
             packet_len=pdu_len; /* do TLV decoding as long as it makes sense */
             length=pdu_len;
-       }
+        }
 
-       ND_TCHECK(*header_lsp);
-       ND_PRINT((ndo, "\n\t  lsp-id: %s, seq: 0x%08x, lifetime: %5us\n\t  chksum: 0x%04x",
+        ND_PRINT((ndo, "\n\t  lsp-id: %s, seq: 0x%08x, lifetime: %5us\n\t  chksum: 0x%04x",
                isis_print_id(header_lsp->lsp_id, LSP_ID_LEN),
                EXTRACT_32BITS(header_lsp->sequence_number),
                EXTRACT_16BITS(header_lsp->remaining_lifetime),
                EXTRACT_16BITS(header_lsp->checksum)));
 
+        osi_print_cksum(ndo, (const uint8_t *)header_lsp->lsp_id,
+                        EXTRACT_16BITS(header_lsp->checksum),
+                        12, length-12);
 
-        osi_print_cksum(ndo, (u_int8_t *)header_lsp->lsp_id,
-                        EXTRACT_16BITS(header_lsp->checksum), 12, length-12);
-
-        /*
-         * Clear checksum and lifetime prior to signature verification.
-         */
-        header_lsp->checksum[0] = 0;
-        header_lsp->checksum[1] = 0;
-        header_lsp->remaining_lifetime[0] = 0;
-        header_lsp->remaining_lifetime[1] = 0;
-
-
-       ND_PRINT((ndo, ", PDU length: %u, Flags: [ %s",
+        ND_PRINT((ndo, ", PDU length: %u, Flags: [ %s",
                pdu_len,
                ISIS_MASK_LSP_OL_BIT(header_lsp->typeblock) ? "Overload bit set, " : ""));
 
-       if (ISIS_MASK_LSP_ATT_BITS(header_lsp->typeblock)) {
-           ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_DEFAULT_BIT(header_lsp->typeblock) ? "default " : ""));
-           ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_DELAY_BIT(header_lsp->typeblock) ? "delay " : ""));
-           ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_EXPENSE_BIT(header_lsp->typeblock) ? "expense " : ""));
-           ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_ERROR_BIT(header_lsp->typeblock) ? "error " : ""));
-           ND_PRINT((ndo, "ATT bit set, "));
-       }
-       ND_PRINT((ndo, "%s", ISIS_MASK_LSP_PARTITION_BIT(header_lsp->typeblock) ? "P bit set, " : ""));
-       ND_PRINT((ndo, "%s ]", tok2str(isis_lsp_istype_values, "Unknown(0x%x)",
-                 ISIS_MASK_LSP_ISTYPE_BITS(header_lsp->typeblock))));
+        if (ISIS_MASK_LSP_ATT_BITS(header_lsp->typeblock)) {
+            ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_DEFAULT_BIT(header_lsp->typeblock) ? "default " : ""));
+            ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_DELAY_BIT(header_lsp->typeblock) ? "delay " : ""));
+            ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_EXPENSE_BIT(header_lsp->typeblock) ? "expense " : ""));
+            ND_PRINT((ndo, "%s", ISIS_MASK_LSP_ATT_ERROR_BIT(header_lsp->typeblock) ? "error " : ""));
+            ND_PRINT((ndo, "ATT bit set, "));
+        }
+        ND_PRINT((ndo, "%s", ISIS_MASK_LSP_PARTITION_BIT(header_lsp->typeblock) ? "P bit set, " : ""));
+        ND_PRINT((ndo, "%s ]", tok2str(isis_lsp_istype_values, "Unknown(0x%x)",
+                  ISIS_MASK_LSP_ISTYPE_BITS(header_lsp->typeblock))));
 
-       if (ndo->ndo_vflag > 1) {
-               if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_LSP_HEADER_SIZE))
-                       return(0);
-       }
+        if (ndo->ndo_vflag > 1) {
+            if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_LSP_HEADER_SIZE))
+                return (0);
+        }
 
-       packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE);
-       pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE);
-       break;
+        packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE);
+        pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_LSP_HEADER_SIZE);
+        break;
 
     case ISIS_PDU_L1_CSNP:
     case ISIS_PDU_L2_CSNP:
-       if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE)) {
-           ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
-                  isis_header->fixed_len, (unsigned long)ISIS_CSNP_HEADER_SIZE));
-           return (0);
-       }
-
-       pdu_len=EXTRACT_16BITS(header_csnp->pdu_len);
-       if (packet_len>pdu_len) {
+        if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE)) {
+            ND_PRINT((ndo, ", bogus fixed header length %u should be %lu",
+                      isis_header->fixed_len, (unsigned long)(ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE)));
+            return (0);
+        }
+        ND_TCHECK(*header_csnp);
+        if (length < ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE)
+            goto trunc;
+        if (ndo->ndo_vflag == 0) {
+            ND_PRINT((ndo, ", src-id %s", isis_print_id(header_csnp->source_id, NODE_ID_LEN)));
+            ND_PRINT((ndo, ", length %u", length));
+            return (1);
+        }
+        pdu_len=EXTRACT_16BITS(header_csnp->pdu_len);
+        if (packet_len>pdu_len) {
             packet_len=pdu_len; /* do TLV decoding as long as it makes sense */
             length=pdu_len;
-       }
+        }
 
-       ND_TCHECK(*header_csnp);
-       ND_PRINT((ndo, "\n\t  source-id:    %s, PDU length: %u",
+        ND_PRINT((ndo, "\n\t  source-id:    %s, PDU length: %u",
                isis_print_id(header_csnp->source_id, NODE_ID_LEN),
                pdu_len));
-       ND_PRINT((ndo, "\n\t  start lsp-id: %s",
+        ND_PRINT((ndo, "\n\t  start lsp-id: %s",
                isis_print_id(header_csnp->start_lsp_id, LSP_ID_LEN)));
-       ND_PRINT((ndo, "\n\t  end lsp-id:   %s",
+        ND_PRINT((ndo, "\n\t  end lsp-id:   %s",
                isis_print_id(header_csnp->end_lsp_id, LSP_ID_LEN)));
 
-       if (ndo->ndo_vflag > 1) {
-               if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_CSNP_HEADER_SIZE))
-                       return(0);
-       }
+        if (ndo->ndo_vflag > 1) {
+            if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_CSNP_HEADER_SIZE))
+                return (0);
+        }
 
-       packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE);
-       pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE);
+        packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE);
+        pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_CSNP_HEADER_SIZE);
         break;
 
     case ISIS_PDU_L1_PSNP:
     case ISIS_PDU_L2_PSNP:
-       if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE)) {
-           ND_PRINT((ndo, "- bogus fixed header length %u should be %lu",
-                  isis_header->fixed_len, (unsigned long)ISIS_PSNP_HEADER_SIZE));
-           return (0);
-       }
-
-       pdu_len=EXTRACT_16BITS(header_psnp->pdu_len);
-       if (packet_len>pdu_len) {
+        if (isis_header->fixed_len != (ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE)) {
+            ND_PRINT((ndo, "- bogus fixed header length %u should be %lu",
+                   isis_header->fixed_len, (unsigned long)(ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE)));
+            return (0);
+        }
+        ND_TCHECK(*header_psnp);
+        if (length < ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE)
+            goto trunc;
+        if (ndo->ndo_vflag == 0) {
+            ND_PRINT((ndo, ", src-id %s", isis_print_id(header_psnp->source_id, NODE_ID_LEN)));
+            ND_PRINT((ndo, ", length %u", length));
+            return (1);
+        }
+        pdu_len=EXTRACT_16BITS(header_psnp->pdu_len);
+        if (packet_len>pdu_len) {
             packet_len=pdu_len; /* do TLV decoding as long as it makes sense */
             length=pdu_len;
-       }
+        }
 
-       ND_TCHECK(*header_psnp);
-       ND_PRINT((ndo, "\n\t  source-id:    %s, PDU length: %u",
+        ND_PRINT((ndo, "\n\t  source-id:    %s, PDU length: %u",
                isis_print_id(header_psnp->source_id, NODE_ID_LEN),
                pdu_len));
 
-       if (ndo->ndo_vflag > 1) {
-               if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_PSNP_HEADER_SIZE))
-                       return(0);
-       }
+        if (ndo->ndo_vflag > 1) {
+            if (!print_unknown_data(ndo, pptr, "\n\t  ", ISIS_PSNP_HEADER_SIZE))
+                return (0);
+        }
 
-       packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE);
-       pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE);
-       break;
+        packet_len -= (ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE);
+        pptr = p + (ISIS_COMMON_HEADER_SIZE+ISIS_PSNP_HEADER_SIZE);
+        break;
 
     default:
-       if (!print_unknown_data(ndo, pptr, "\n\t  ", length))
-           return(0);
+        if (ndo->ndo_vflag == 0) {
+            ND_PRINT((ndo, ", length %u", length));
+            return (1);
+        }
+       (void)print_unknown_data(ndo, pptr, "\n\t  ", length);
        return (0);
     }
 
@@ -2425,24 +2536,15 @@ isis_print(netdissect_options *ndo,
      * Now print the TLV's.
      */
 
-    while (packet_len >= 2) {
-        if (pptr == ndo->ndo_snapend) {
-            return (1);
-        }
-
-       if (!ND_TTEST2(*pptr, 2)) {
-           ND_PRINT((ndo, "\n\t\t packet exceeded snapshot (%ld) bytes",
-                   (long)(pptr - ndo->ndo_snapend)));
-           return (1);
-       }
+    while (packet_len > 0) {
+       ND_TCHECK2(*pptr, 2);
+       if (packet_len < 2)
+           goto trunc;
        tlv_type = *pptr++;
        tlv_len = *pptr++;
         tmp =tlv_len; /* copy temporary len & pointer to packet data */
         tptr = pptr;
        packet_len -= 2;
-       if (tlv_len > packet_len) {
-           break;
-       }
 
         /* first lets see if we know the TLVs name*/
        ND_PRINT((ndo, "\n\t    %s TLV #%u, length: %u",
@@ -2452,32 +2554,33 @@ isis_print(netdissect_options *ndo,
                tlv_type,
                tlv_len));
 
-        if (tlv_len == 0) /* something is malformed */
+        if (tlv_len == 0) /* something is invalid */
            continue;
 
+       if (packet_len < tlv_len)
+           goto trunc;
+
         /* now check if we have a decoder otherwise do a hexdump at the end*/
        switch (tlv_type) {
        case ISIS_TLV_AREA_ADDR:
-           if (!ND_TTEST2(*tptr, 1))
-               goto trunctlv;
+           ND_TCHECK2(*tptr, 1);
            alen = *tptr++;
            while (tmp && alen < tmp) {
+               ND_TCHECK2(*tptr, alen);
                ND_PRINT((ndo, "\n\t      Area address (length: %u): %s",
                        alen,
-                       isonsap_string(tptr, alen)));
+                       isonsap_string(ndo, tptr, alen)));
                tptr += alen;
                tmp -= alen + 1;
                if (tmp==0) /* if this is the last area address do not attemt a boundary check */
                     break;
-               if (!ND_TTEST2(*tptr, 1))
-                   goto trunctlv;
+               ND_TCHECK2(*tptr, 1);
                alen = *tptr++;
            }
            break;
        case ISIS_TLV_ISNEIGH:
            while (tmp >= ETHER_ADDR_LEN) {
-                if (!ND_TTEST2(*tptr, ETHER_ADDR_LEN))
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, ETHER_ADDR_LEN);
                 ND_PRINT((ndo, "\n\t      SNPA: %s", isis_print_id(tptr, ETHER_ADDR_LEN)));
                 tmp -= ETHER_ADDR_LEN;
                 tptr += ETHER_ADDR_LEN;
@@ -2495,8 +2598,7 @@ isis_print(netdissect_options *ndo,
             tmp --;
             ND_PRINT((ndo, "\n\t      LAN address length %u bytes ", lan_alen));
            while (tmp >= lan_alen) {
-                if (!ND_TTEST2(*tptr, lan_alen))
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, lan_alen);
                 ND_PRINT((ndo, "\n\t\tIS Neighbor: %s", isis_print_id(tptr, lan_alen)));
                 tmp -= lan_alen;
                 tptr +=lan_alen;
@@ -2542,16 +2644,14 @@ isis_print(netdissect_options *ndo,
             }
             break;
         case ISIS_TLV_IS_REACH:
-           if (!ND_TTEST2(*tptr,1))  /* check if there is one byte left to read out the virtual flag */
-                goto trunctlv;
+           ND_TCHECK2(*tptr,1);  /* check if there is one byte left to read out the virtual flag */
             ND_PRINT((ndo, "\n\t      %s",
                    tok2str(isis_is_reach_virtual_values,
                            "bogus virtual flag 0x%02x",
                            *tptr++)));
            tlv_is_reach = (const struct isis_tlv_is_reach *)tptr;
             while (tmp >= sizeof(struct isis_tlv_is_reach)) {
-               if (!ND_TTEST(*tlv_is_reach))
-                   goto trunctlv;
+               ND_TCHECK(*tlv_is_reach);
                ND_PRINT((ndo, "\n\t      IS Neighbor: %s",
                       isis_print_id(tlv_is_reach->neighbor_nodeid, NODE_ID_LEN)));
                isis_print_metric_block(ndo, &tlv_is_reach->isis_metric_block);
@@ -2563,8 +2663,7 @@ isis_print(netdissect_options *ndo,
         case ISIS_TLV_ESNEIGH:
            tlv_es_reach = (const struct isis_tlv_es_reach *)tptr;
             while (tmp >= sizeof(struct isis_tlv_es_reach)) {
-               if (!ND_TTEST(*tlv_es_reach))
-                   goto trunctlv;
+               ND_TCHECK(*tlv_es_reach);
                ND_PRINT((ndo, "\n\t      ES Neighbor: %s",
                        isis_print_id(tlv_es_reach->neighbor_sysid, SYSTEM_ID_LEN)));
                isis_print_metric_block(ndo, &tlv_es_reach->isis_metric_block);
@@ -2607,7 +2706,6 @@ isis_print(netdissect_options *ndo,
            }
            break;
 
-#ifdef INET6
        case ISIS_TLV_IP6_REACH:
            while (tmp>0) {
                 ext_ip_len = isis_print_extd_ip_reach(ndo, tptr, "\n\t      ", AF_INET6);
@@ -2637,20 +2735,17 @@ isis_print(netdissect_options *ndo,
 
        case ISIS_TLV_IP6ADDR:
            while (tmp>=sizeof(struct in6_addr)) {
-               if (!ND_TTEST2(*tptr, sizeof(struct in6_addr)))
-                   goto trunctlv;
+               ND_TCHECK2(*tptr, sizeof(struct in6_addr));
 
                 ND_PRINT((ndo, "\n\t      IPv6 interface address: %s",
-                      ip6addr_string(tptr)));
+                      ip6addr_string(ndo, tptr)));
 
                tptr += sizeof(struct in6_addr);
                tmp -= sizeof(struct in6_addr);
            }
            break;
-#endif
        case ISIS_TLV_AUTH:
-           if (!ND_TTEST2(*tptr, 1))
-               goto trunctlv;
+           ND_TCHECK2(*tptr, 1);
 
             ND_PRINT((ndo, "\n\t      %s: ",
                    tok2str(isis_subtlv_auth_values,
@@ -2659,36 +2754,29 @@ isis_print(netdissect_options *ndo,
 
            switch (*tptr) {
            case ISIS_SUBTLV_AUTH_SIMPLE:
-               for(i=1;i<tlv_len;i++) {
-                   if (!ND_TTEST2(*(tptr + i), 1))
-                       goto trunctlv;
-                   ND_PRINT((ndo, "%c", *(tptr + i)));
-               }
+               if (fn_printzp(ndo, tptr + 1, tlv_len - 1, ndo->ndo_snapend))
+                   goto trunctlv;
                break;
            case ISIS_SUBTLV_AUTH_MD5:
                for(i=1;i<tlv_len;i++) {
-                   if (!ND_TTEST2(*(tptr + i), 1))
-                       goto trunctlv;
+                   ND_TCHECK2(*(tptr + i), 1);
                    ND_PRINT((ndo, "%02x", *(tptr + i)));
                }
                if (tlv_len != ISIS_SUBTLV_AUTH_MD5_LEN+1)
-                    ND_PRINT((ndo, ", (malformed subTLV) "));
+                    ND_PRINT((ndo, ", (invalid subTLV) "));
 
-#ifdef HAVE_LIBCRYPTO
-                sigcheck = signature_verify(ndo, optr, length,
-                                            (unsigned char *)tptr + 1);
-#else
-                sigcheck = CANT_CHECK_SIGNATURE;
-#endif
+                sigcheck = signature_verify(ndo, optr, length, tptr + 1,
+                                            isis_clear_checksum_lifetime,
+                                            header_lsp);
                 ND_PRINT((ndo, " (%s)", tok2str(signature_check_values, "Unknown", sigcheck)));
 
                break;
             case ISIS_SUBTLV_AUTH_GENERIC:
+               ND_TCHECK2(*(tptr + 1), 2);
                 key_id = EXTRACT_16BITS((tptr+1));
                 ND_PRINT((ndo, "%u, password: ", key_id));
-                for(i=1 + sizeof(u_int16_t);i<tlv_len;i++) {
-                    if (!ND_TTEST2(*(tptr + i), 1))
-                        goto trunctlv;
+                for(i=1 + sizeof(uint16_t);i<tlv_len;i++) {
+                    ND_TCHECK2(*(tptr + i), 1);
                     ND_PRINT((ndo, "%02x", *(tptr + i)));
                 }
                 break;
@@ -2703,32 +2791,26 @@ isis_print(netdissect_options *ndo,
        case ISIS_TLV_PTP_ADJ:
            tlv_ptp_adj = (const struct isis_tlv_ptp_adj *)tptr;
            if(tmp>=1) {
-               if (!ND_TTEST2(*tptr, 1))
-                   goto trunctlv;
+               ND_TCHECK2(*tptr, 1);
                ND_PRINT((ndo, "\n\t      Adjacency State: %s (%u)",
                       tok2str(isis_ptp_adjancey_values, "unknown", *tptr),
                         *tptr));
                tmp--;
            }
            if(tmp>sizeof(tlv_ptp_adj->extd_local_circuit_id)) {
-               if (!ND_TTEST2(tlv_ptp_adj->extd_local_circuit_id,
-                            sizeof(tlv_ptp_adj->extd_local_circuit_id)))
-                   goto trunctlv;
+               ND_TCHECK(tlv_ptp_adj->extd_local_circuit_id);
                ND_PRINT((ndo, "\n\t      Extended Local circuit-ID: 0x%08x",
                       EXTRACT_32BITS(tlv_ptp_adj->extd_local_circuit_id)));
                tmp-=sizeof(tlv_ptp_adj->extd_local_circuit_id);
            }
            if(tmp>=SYSTEM_ID_LEN) {
-               if (!ND_TTEST2(tlv_ptp_adj->neighbor_sysid, SYSTEM_ID_LEN))
-                   goto trunctlv;
+               ND_TCHECK2(tlv_ptp_adj->neighbor_sysid, SYSTEM_ID_LEN);
                ND_PRINT((ndo, "\n\t      Neighbor System-ID: %s",
                       isis_print_id(tlv_ptp_adj->neighbor_sysid, SYSTEM_ID_LEN)));
                tmp-=SYSTEM_ID_LEN;
            }
            if(tmp>=sizeof(tlv_ptp_adj->neighbor_extd_local_circuit_id)) {
-               if (!ND_TTEST2(tlv_ptp_adj->neighbor_extd_local_circuit_id,
-                            sizeof(tlv_ptp_adj->neighbor_extd_local_circuit_id)))
-                   goto trunctlv;
+               ND_TCHECK(tlv_ptp_adj->neighbor_extd_local_circuit_id);
                ND_PRINT((ndo, "\n\t      Neighbor Extended Local circuit-ID: 0x%08x",
                       EXTRACT_32BITS(tlv_ptp_adj->neighbor_extd_local_circuit_id)));
            }
@@ -2737,8 +2819,7 @@ isis_print(netdissect_options *ndo,
        case ISIS_TLV_PROTOCOLS:
            ND_PRINT((ndo, "\n\t      NLPID(s): "));
            while (tmp>0) {
-               if (!ND_TTEST2(*(tptr), 1))
-                   goto trunctlv;
+               ND_TCHECK2(*(tptr), 1);
                ND_PRINT((ndo, "%s (0x%02x)",
                        tok2str(nlpid_values,
                                "unknown",
@@ -2753,8 +2834,7 @@ isis_print(netdissect_options *ndo,
 
     case ISIS_TLV_MT_PORT_CAP:
     {
-      if (!ND_TTEST2(*(tptr), 2))
-        goto trunctlv;
+      ND_TCHECK2(*(tptr), 2);
 
       ND_PRINT((ndo, "\n\t       RES: %d, MTID(s): %d",
               (EXTRACT_16BITS (tptr) >> 12),
@@ -2771,8 +2851,7 @@ isis_print(netdissect_options *ndo,
 
     case ISIS_TLV_MT_CAPABILITY:
 
-      if (!ND_TTEST2(*(tptr), 2))
-        goto trunctlv;
+      ND_TCHECK2(*(tptr), 2);
 
       ND_PRINT((ndo, "\n\t      O: %d, RES: %d, MTID(s): %d",
                 (EXTRACT_16BITS(tptr) >> 15) & 0x01,
@@ -2788,16 +2867,14 @@ isis_print(netdissect_options *ndo,
       break;
 
        case ISIS_TLV_TE_ROUTER_ID:
-           if (!ND_TTEST2(*pptr, sizeof(struct in_addr)))
-               goto trunctlv;
-           ND_PRINT((ndo, "\n\t      Traffic Engineering Router ID: %s", ipaddr_string(pptr)));
+           ND_TCHECK2(*pptr, sizeof(struct in_addr));
+           ND_PRINT((ndo, "\n\t      Traffic Engineering Router ID: %s", ipaddr_string(ndo, pptr)));
            break;
 
        case ISIS_TLV_IPADDR:
            while (tmp>=sizeof(struct in_addr)) {
-               if (!ND_TTEST2(*tptr, sizeof(struct in_addr)))
-                   goto trunctlv;
-               ND_PRINT((ndo, "\n\t      IPv4 interface address: %s", ipaddr_string(tptr)));
+               ND_TCHECK2(*tptr, sizeof(struct in_addr));
+               ND_PRINT((ndo, "\n\t      IPv4 interface address: %s", ipaddr_string(ndo, tptr)));
                tptr += sizeof(struct in_addr);
                tmp -= sizeof(struct in_addr);
            }
@@ -2805,49 +2882,40 @@ isis_print(netdissect_options *ndo,
 
        case ISIS_TLV_HOSTNAME:
            ND_PRINT((ndo, "\n\t      Hostname: "));
-           while (tmp>0) {
-               if (!ND_TTEST2(*tptr, 1))
-                   goto trunctlv;
-               ND_PRINT((ndo, "%c", *tptr++));
-                tmp--;
-           }
+           if (fn_printzp(ndo, tptr, tmp, ndo->ndo_snapend))
+               goto trunctlv;
            break;
 
        case ISIS_TLV_SHARED_RISK_GROUP:
            if (tmp < NODE_ID_LEN)
                break;
-           if (!ND_TTEST2(*tptr, NODE_ID_LEN))
-                goto trunctlv;
+           ND_TCHECK2(*tptr, NODE_ID_LEN);
            ND_PRINT((ndo, "\n\t      IS Neighbor: %s", isis_print_id(tptr, NODE_ID_LEN)));
            tptr+=(NODE_ID_LEN);
            tmp-=(NODE_ID_LEN);
 
            if (tmp < 1)
                break;
-           if (!ND_TTEST2(*tptr, 1))
-                goto trunctlv;
+           ND_TCHECK2(*tptr, 1);
            ND_PRINT((ndo, ", Flags: [%s]", ISIS_MASK_TLV_SHARED_RISK_GROUP(*tptr++) ? "numbered" : "unnumbered"));
            tmp--;
 
            if (tmp < sizeof(struct in_addr))
                break;
-           if (!ND_TTEST2(*tptr, sizeof(struct in_addr)))
-                goto trunctlv;
-           ND_PRINT((ndo, "\n\t      IPv4 interface address: %s", ipaddr_string(tptr)));
+           ND_TCHECK2(*tptr, sizeof(struct in_addr));
+           ND_PRINT((ndo, "\n\t      IPv4 interface address: %s", ipaddr_string(ndo, tptr)));
            tptr+=sizeof(struct in_addr);
            tmp-=sizeof(struct in_addr);
 
            if (tmp < sizeof(struct in_addr))
                break;
-           if (!ND_TTEST2(*tptr, sizeof(struct in_addr)))
-                goto trunctlv;
-           ND_PRINT((ndo, "\n\t      IPv4 neighbor address: %s", ipaddr_string(tptr)));
+           ND_TCHECK2(*tptr, sizeof(struct in_addr));
+           ND_PRINT((ndo, "\n\t      IPv4 neighbor address: %s", ipaddr_string(ndo, tptr)));
            tptr+=sizeof(struct in_addr);
            tmp-=sizeof(struct in_addr);
 
            while (tmp>=4) {
-                if (!ND_TTEST2(*tptr, 4))
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, 4);
                 ND_PRINT((ndo, "\n\t      Link-ID: 0x%08x", EXTRACT_32BITS(tptr)));
                 tptr+=4;
                 tmp-=4;
@@ -2857,18 +2925,14 @@ isis_print(netdissect_options *ndo,
        case ISIS_TLV_LSP:
            tlv_lsp = (const struct isis_tlv_lsp *)tptr;
            while(tmp>=sizeof(struct isis_tlv_lsp)) {
-               if (!ND_TTEST((tlv_lsp->lsp_id)[LSP_ID_LEN-1]))
-                   goto trunctlv;
+               ND_TCHECK((tlv_lsp->lsp_id)[LSP_ID_LEN-1]);
                ND_PRINT((ndo, "\n\t      lsp-id: %s",
                        isis_print_id(tlv_lsp->lsp_id, LSP_ID_LEN)));
-               if (!ND_TTEST2(tlv_lsp->sequence_number, 4))
-                   goto trunctlv;
+               ND_TCHECK2(tlv_lsp->sequence_number, 4);
                ND_PRINT((ndo, ", seq: 0x%08x", EXTRACT_32BITS(tlv_lsp->sequence_number)));
-               if (!ND_TTEST2(tlv_lsp->remaining_lifetime, 2))
-                   goto trunctlv;
+               ND_TCHECK2(tlv_lsp->remaining_lifetime, 2);
                ND_PRINT((ndo, ", lifetime: %5ds", EXTRACT_16BITS(tlv_lsp->remaining_lifetime)));
-               if (!ND_TTEST2(tlv_lsp->checksum, 2))
-                   goto trunctlv;
+               ND_TCHECK2(tlv_lsp->checksum, 2);
                ND_PRINT((ndo, ", chksum: 0x%04x", EXTRACT_16BITS(tlv_lsp->checksum)));
                tmp-=sizeof(struct isis_tlv_lsp);
                tlv_lsp++;
@@ -2878,15 +2942,29 @@ isis_print(netdissect_options *ndo,
        case ISIS_TLV_CHECKSUM:
            if (tmp < ISIS_TLV_CHECKSUM_MINLEN)
                break;
-           if (!ND_TTEST2(*tptr, ISIS_TLV_CHECKSUM_MINLEN))
-               goto trunctlv;
+           ND_TCHECK2(*tptr, ISIS_TLV_CHECKSUM_MINLEN);
            ND_PRINT((ndo, "\n\t      checksum: 0x%04x ", EXTRACT_16BITS(tptr)));
             /* do not attempt to verify the checksum if it is zero
              * most likely a HMAC-MD5 TLV is also present and
              * to avoid conflicts the checksum TLV is zeroed.
              * see rfc3358 for details
              */
-            osi_print_cksum(ndo, optr, EXTRACT_16BITS(tptr), tptr-optr, length);
+            osi_print_cksum(ndo, optr, EXTRACT_16BITS(tptr), tptr-optr,
+                length);
+           break;
+
+       case ISIS_TLV_POI:
+           if (tlv_len >= SYSTEM_ID_LEN + 1) {
+               ND_TCHECK2(*tptr, SYSTEM_ID_LEN + 1);
+               ND_PRINT((ndo, "\n\t      Purge Originator System-ID: %s",
+                      isis_print_id(tptr + 1, SYSTEM_ID_LEN)));
+           }
+
+           if (tlv_len == 2 * SYSTEM_ID_LEN + 1) {
+               ND_TCHECK2(*tptr, 2 * SYSTEM_ID_LEN + 1);
+               ND_PRINT((ndo, "\n\t      Received from System-ID: %s",
+                      isis_print_id(tptr + SYSTEM_ID_LEN + 1, SYSTEM_ID_LEN)));
+           }
            break;
 
        case ISIS_TLV_MT_SUPPORTED:
@@ -2902,7 +2980,7 @@ isis_print(netdissect_options *ndo,
                     tptr+=mt_len;
                     tmp-=mt_len;
                } else {
-                   ND_PRINT((ndo, "\n\t      malformed MT-ID"));
+                   ND_PRINT((ndo, "\n\t      invalid MT-ID"));
                    break;
                }
            }
@@ -2912,8 +2990,7 @@ isis_print(netdissect_options *ndo,
             /* first attempt to decode the flags */
             if (tmp < ISIS_TLV_RESTART_SIGNALING_FLAGLEN)
                 break;
-            if (!ND_TTEST2(*tptr, ISIS_TLV_RESTART_SIGNALING_FLAGLEN))
-                goto trunctlv;
+            ND_TCHECK2(*tptr, ISIS_TLV_RESTART_SIGNALING_FLAGLEN);
             ND_PRINT((ndo, "\n\t      Flags [%s]",
                    bittok2str(isis_restart_flag_values, "none", *tptr)));
             tptr+=ISIS_TLV_RESTART_SIGNALING_FLAGLEN;
@@ -2925,8 +3002,7 @@ isis_print(netdissect_options *ndo,
 
             if (tmp < ISIS_TLV_RESTART_SIGNALING_HOLDTIMELEN)
                 break;
-            if (!ND_TTEST2(*tptr, ISIS_TLV_RESTART_SIGNALING_HOLDTIMELEN))
-                goto trunctlv;
+            ND_TCHECK2(*tptr, ISIS_TLV_RESTART_SIGNALING_HOLDTIMELEN);
 
             ND_PRINT((ndo, ", Remaining holding time %us", EXTRACT_16BITS(tptr)));
             tptr+=ISIS_TLV_RESTART_SIGNALING_HOLDTIMELEN;
@@ -2934,8 +3010,7 @@ isis_print(netdissect_options *ndo,
 
             /* is there an additional sysid field present ?*/
             if (tmp == SYSTEM_ID_LEN) {
-                    if (!ND_TTEST2(*tptr, SYSTEM_ID_LEN))
-                            goto trunctlv;
+                    ND_TCHECK2(*tptr, SYSTEM_ID_LEN);
                     ND_PRINT((ndo, ", for %s", isis_print_id(tptr,SYSTEM_ID_LEN)));
             }
            break;
@@ -2943,16 +3018,14 @@ isis_print(netdissect_options *ndo,
         case ISIS_TLV_IDRP_INFO:
            if (tmp < ISIS_TLV_IDRP_INFO_MINLEN)
                break;
-            if (!ND_TTEST2(*tptr, ISIS_TLV_IDRP_INFO_MINLEN))
-                goto trunctlv;
+            ND_TCHECK2(*tptr, ISIS_TLV_IDRP_INFO_MINLEN);
             ND_PRINT((ndo, "\n\t      Inter-Domain Information Type: %s",
                    tok2str(isis_subtlv_idrp_values,
                            "Unknown (0x%02x)",
                            *tptr)));
             switch (*tptr++) {
             case ISIS_SUBTLV_IDRP_ASN:
-                if (!ND_TTEST2(*tptr, 2)) /* fetch AS number */
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, 2); /* fetch AS number */
                 ND_PRINT((ndo, "AS Number: %u", EXTRACT_16BITS(tptr)));
                 break;
             case ISIS_SUBTLV_IDRP_LOCAL:
@@ -2967,15 +3040,13 @@ isis_print(netdissect_options *ndo,
         case ISIS_TLV_LSP_BUFFERSIZE:
            if (tmp < ISIS_TLV_LSP_BUFFERSIZE_MINLEN)
                break;
-            if (!ND_TTEST2(*tptr, ISIS_TLV_LSP_BUFFERSIZE_MINLEN))
-                goto trunctlv;
+            ND_TCHECK2(*tptr, ISIS_TLV_LSP_BUFFERSIZE_MINLEN);
             ND_PRINT((ndo, "\n\t      LSP Buffersize: %u", EXTRACT_16BITS(tptr)));
             break;
 
         case ISIS_TLV_PART_DIS:
             while (tmp >= SYSTEM_ID_LEN) {
-                if (!ND_TTEST2(*tptr, SYSTEM_ID_LEN))
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, SYSTEM_ID_LEN);
                 ND_PRINT((ndo, "\n\t      %s", isis_print_id(tptr, SYSTEM_ID_LEN)));
                 tptr+=SYSTEM_ID_LEN;
                 tmp-=SYSTEM_ID_LEN;
@@ -2985,16 +3056,14 @@ isis_print(netdissect_options *ndo,
         case ISIS_TLV_PREFIX_NEIGH:
            if (tmp < sizeof(struct isis_metric_block))
                break;
-            if (!ND_TTEST2(*tptr, sizeof(struct isis_metric_block)))
-                goto trunctlv;
+            ND_TCHECK2(*tptr, sizeof(struct isis_metric_block));
             ND_PRINT((ndo, "\n\t      Metric Block"));
             isis_print_metric_block(ndo, (const struct isis_metric_block *)tptr);
             tptr+=sizeof(struct isis_metric_block);
             tmp-=sizeof(struct isis_metric_block);
 
             while(tmp>0) {
-                if (!ND_TTEST2(*tptr, 1))
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, 1);
                 prefix_len=*tptr++; /* read out prefix length in semioctets*/
                 if (prefix_len < 2) {
                     ND_PRINT((ndo, "\n\t\tAddress: prefix length %u < 2", prefix_len));
@@ -3003,10 +3072,9 @@ isis_print(netdissect_options *ndo,
                 tmp--;
                 if (tmp < prefix_len/2)
                     break;
-                if (!ND_TTEST2(*tptr, prefix_len / 2))
-                    goto trunctlv;
+                ND_TCHECK2(*tptr, prefix_len / 2);
                 ND_PRINT((ndo, "\n\t\tAddress: %s/%u",
-                       isonsap_string(tptr, prefix_len / 2), prefix_len * 4));
+                       isonsap_string(ndo, tptr, prefix_len / 2), prefix_len * 4));
                 tptr+=prefix_len/2;
                 tmp-=prefix_len/2;
             }
@@ -3015,16 +3083,14 @@ isis_print(netdissect_options *ndo,
         case ISIS_TLV_IIH_SEQNR:
            if (tmp < ISIS_TLV_IIH_SEQNR_MINLEN)
                break;
-            if (!ND_TTEST2(*tptr, ISIS_TLV_IIH_SEQNR_MINLEN)) /* check if four bytes are on the wire */
-                goto trunctlv;
+            ND_TCHECK2(*tptr, ISIS_TLV_IIH_SEQNR_MINLEN); /* check if four bytes are on the wire */
             ND_PRINT((ndo, "\n\t      Sequence number: %u", EXTRACT_32BITS(tptr)));
             break;
 
         case ISIS_TLV_VENDOR_PRIVATE:
            if (tmp < ISIS_TLV_VENDOR_PRIVATE_MINLEN)
                break;
-            if (!ND_TTEST2(*tptr, ISIS_TLV_VENDOR_PRIVATE_MINLEN)) /* check if enough byte for a full oui */
-                goto trunctlv;
+            ND_TCHECK2(*tptr, ISIS_TLV_VENDOR_PRIVATE_MINLEN); /* check if enough byte for a full oui */
             vendor_id = EXTRACT_24BITS(tptr);
             ND_PRINT((ndo, "\n\t      Vendor: %s (%u)",
                    tok2str(oui_values, "Unknown", vendor_id),
@@ -3069,25 +3135,35 @@ isis_print(netdissect_options *ndo,
     return (1);
 
  trunc:
-    ND_PRINT((ndo, "[|isis]"));
+    ND_PRINT((ndo, "%s", tstr));
     return (1);
 
  trunctlv:
-    ND_PRINT((ndo, "\n\t\t packet exceeded snapshot"));
+    ND_PRINT((ndo, "\n\t\t"));
+    ND_PRINT((ndo, "%s", tstr));
     return(1);
 }
 
 static void
-osi_print_cksum(netdissect_options *ndo,
-                const u_int8_t *pptr, u_int16_t checksum,
-                    u_int checksum_offset, u_int length)
+osi_print_cksum(netdissect_options *ndo, const uint8_t *pptr,
+               uint16_t checksum, int checksum_offset, u_int length)
 {
-        u_int16_t calculated_checksum;
+        uint16_t calculated_checksum;
 
-        /* do not attempt to verify the checksum if it is zero */
-        if (!checksum) {
-                ND_PRINT((ndo, "(unverified)"));
+        /* do not attempt to verify the checksum if it is zero,
+         * if the offset is nonsense,
+         * or the base pointer is not sane
+         */
+        if (!checksum
+            || checksum_offset < 0
+            || !ND_TTEST2(*(pptr + checksum_offset), 2)
+            || (u_int)checksum_offset > length
+            || !ND_TTEST2(*pptr, length)) {
+                ND_PRINT((ndo, " (unverified)"));
         } else {
+#if 0
+                printf("\nosi_print_cksum: %p %u %u\n", pptr, checksum_offset, length);
+#endif
                 calculated_checksum = create_osi_cksum(pptr, checksum_offset, length);
                 if (checksum == calculated_checksum) {
                         ND_PRINT((ndo, " (correct)"));